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Spinal cord injury (SCI) is damage to any part of the spinal cord resulting in paralysis, bowel and/or bladder incontinence, and loss of sensation and other bodily functions. Current treatments for chronic SCI are focused on managing symptoms and preventing further damage to the spinal cord with limited neuro-restorative interventions. Recent research and independent clinical trials of spinal cord stimulation (SCS) or intensive neuro-rehabilitation including neuro-robotics in participants with SCI have suggested potential malleability of the neuronal networks for neurological recovery. We hypothesize that epidural electrical stimulation (EES) delivered via SCS in conjunction with mental imagery practice and robotic neuro-rehabilitation can synergistically improve volitional motor function below the level of injury in participants with chronic clinically motor-complete SCI. In our pilot clinical RESTORES trial (RESToration Of Rehabilitative function with Epidural spinal Stimulation), we investigate the feasibility of this combined multi-modal approach in restoring volitional motor control and achieving independent overground locomotion in participants with chronic motor complete thoracic SCI. Secondary aims are to assess the safety of this combination therapy including the off-label SCS usage as well as improving functional outcome measures. To our knowledge, this is the first clinical trial that investigates the combined impact of this multi-modal EES and rehabilitation strategy in participants with chronic motor complete SCI. Two participants with chronic motor-complete thoracic SCI were recruited for this pilot trial. Both participants have successfully regained volitional motor control below their level of SCI injury and achieved independent overground walking within a month of post-operative stimulation and rehabilitation. There were no adverse events noted in our trial and there was an improvement in post-operative truncal stability score. Results from this pilot study demonstrates the feasibility of combining EES, mental imagery practice and robotic rehabilitation in improving volitional motor control below level of SCI injury and restoring independent overground walking for participants with chronic motor-complete SCI. Our team believes that this provides very exciting promise in a field currently devoid of disease-modifying therapies. [ABSTRACT FROM AUTHOR]

5Meta-estimation of relative risk of subgroup interactions Reference 1 Wan K, Feng Z, Hajat S. Temperature-related mortality and associated vulnerabilities: evidence from Scotland using extended time-series datasets. The daily mean temperature data was mislabelled during the analysis - the temperature data in the West was mislabelled as North, the temperature data in the East was mislabelled as West and the temperature data in the North was mislabelled as East. Correction: Temperature-related mortality and associated vulnerabilities: evidence from Scotland using extended time-series datasets. [Extracted from the article]

Summary: This article first investigates robust iterative learning control (ILC) problem of a class of large‐scale interconnected systems, which consist of many subsystems described by two‐dimensional linear discrete first Fornasini–Marchesini systems with iteration‐dependent uncertainties arising from not only boundary states, disturbances, but also reference trajectory. A decentralized P‐type ILC law without any information exchanges with other subsystems is proposed such that the ultimate ILC tracking error of each subsystem can converge to a bounded range, the bound of which depends continuously on the bounds of all iteration‐dependent uncertainties considered. Especially, if these iteration‐dependent uncertainties are convergent progressively along the iteration direction, perfect ILC tracking on 2‐D reference trajectory can be obtained. Additionally, a modified ILC law with compensation technique is used to a class of large‐scale interconnected systems composed of many subsystems represented by two‐dimensional linear discrete second Fornasini–Marchesini systems. Two simulation examples are used to demonstrate the effectiveness and validity of the obtained ILC results. Finally, some comparative discussions are given. [ABSTRACT FROM AUTHOR]

Background: Adverse health impacts have been found under extreme temperatures in many parts of the world. The majority of such research to date for the UK has been conducted on populations in England, whilst the impacts of ambient temperature on health outcomes in Scottish populations remain largely unknown.Methods: This study uses time-series regression analysis with distributed lag non-linear models to characterise acute relationships between daily mean ambient temperature and mortality in Scotland including the four largest cities (Aberdeen, Dundee, Edinburgh and Glasgow) and three regions during 1974-2018. Increases in mortality risk under extreme cold and heat in individual cities and regions were aggregated using multivariate meta-analysis. Cold results are summarised by comparing the relative risk (RR) of death at the 1st percentile of localised temperature distributions compared to the 10th percentile, and heat effects as the RR at the 99th compared to the 90th percentile.Results: Adverse cold effects were observed in all cities and regions, and heat effects were apparent in all cities and regions except northern Scotland. Aggregate all-cause mortality risk in Scotland was estimated to increase by 10% (95% confidence interval, CI: 7%, 13%) under extreme cold and 4% (CI: 2%, 5%) under extreme heat. People in urban areas experienced higher mortality risk under extreme cold and heat than those in rural regions. The elderly had the highest RR under both extreme cold and heat. Males experienced greater cold effects than females, whereas the reverse was true with heat effects, particularly among the elderly. Those who were unmarried had higher RR than those married under extreme heat, and the effect remained after controlling for age. The younger population living in the most deprived areas experienced higher cold and heat effects than in less deprived areas. Deaths from respiratory diseases were most sensitive to both cold and heat exposures, although mortality risk for cardiovascular diseases was also heightened, particularly in the elderly. Cold effects were lower in the most recent 15 years, which may be linked to policies and actions in preventing the vulnerable population from cold impacts. No temporal trend was found with the heat effect.Conclusions: This study assesses mortality risk associated with extreme temperatures in Scotland and identifies those groups who would benefit most from targeted actions to reduce cold- and heat-related mortalities. [ABSTRACT FROM AUTHOR]

In the coded caching problem, as originally formulated by Maddah-Ali and Niesen, a server communicates via a noiseless shared broadcast link to multiple users that have local storage capability. In order for a user to decode its demanded file from the coded multicast transmission, the demands of all the users must be globally known, which may violate the privacy of the users. To overcome this privacy problem, Wan and Caire recently proposed several schemes that attain coded multicasting gain while simultaneously guarantee information theoretic privacy of the users’ demands. In Device-to-Device (D2D) networks, the demand privacy problem is further exacerbated by the fact that each user is also a transmitter, which appears to be needing the knowledge of the files demanded by the remaining users in order to form its coded multicast transmission. This paper shows how to solve this seemingly infeasible problem. The main contribution of this paper is the development of new achievable and converse bounds for D2D coded caching that are to within a constant factor of one another when privacy of the users’ demands must be guaranteed even in the presence of colluding users (i.e., when some users share cached contents and demanded file indices). First, a D2D private caching scheme is proposed, whose key feature is the addition of virtual users in the system in order to “hide” the demands of the real users. By comparing the achievable D2D private load with an existing converse bound for the shared-link model without demand privacy constraint, the proposed scheme is shown to be order optimal, except for the very low memory size regime with more files than users. Second, in order to shed light into the open parameter regime, a new achievable scheme and a new converse bound under the constraint of uncoded cache placement (i.e., when each user stores directly a subset of the bits of the library) are developed for the case of two users, and shown to be to within a constant factor of one another for all system parameters. Finally, the two-user converse bound is extended to any number of users by a cut-set type argument. With this new converse bound, the virtual users scheme is shown to be order optimal in all parameter regimes under the constraint of uncoded cache placement and user collusion. [ABSTRACT FROM AUTHOR]

The launch of the selection process for National Development Zones(NDZs) marked a fundamental change in the construction of development zones, making it an essential position for local authorities to implement high-quality development. Based on the data of prefecture-level cities in China from 2000 to 2018, this paper examines the impact and mechanism of selecting NDZs on urban green innovation through a double-difference spatial durbin model using the selection of NDZs as a "quasi-natural experiment". The study finds that the selection of NDZs can promote green innovation in cities and has a significant window-radiating effect. The heterogeneity test results show that the implementation of the selection policy for development zones in non-old industrial cities, large and medium-sized cities, cities with easy access to transportation, and cities with high market orientation are more likely to promote urban green innovation. At the same time, the higher the level of government governance and the better the level of economic development of the development zones, the more it helps to realize the effects of the selection policy. The results of the mechanism test show that the selection of NDZs has a positive impact on urban green innovation through environmental regulation effects, resource allocation effects, and policy amplification effects. [ABSTRACT FROM AUTHOR]

An impurity-free Pb(Fe 1/2 Nb 1/2)O 3 (PFN) ceramic was prepared using a conventional solid-state reaction method with precisely controlled sintering temperature. The PFN ceramic exhibits monoclinic symmetry and shows a dense morphology with equiaxed grains of about 1–2 μm. It exhibits a diffused phase transition at approximately 381 K. From the data of dielectric loss tangent and the imaginary parts of impedance and electrical modulus, a non-Debye type dielectric relaxation was investigated, and it was found that the short-range hopping of oxygen vacancies contributes to the dielectric relaxation and the relaxation time distribution is temperature independent. The PFN ceramic exhibits slim ferroelectric hysteresis loops and a linear magnetic hysteresis loop, indicating that the PFN ceramic is paramagnetic; the band gap is estimated to be 2.04 eV. Photoconductivity and photovoltaic responses with a nonzero open-circuit voltage and short-circuit photocurrent were detected. Moreover, magnetoconductivity was measured. This work implies that the PFN ceramic is a potential candidate for magnetoelectric and photovoltaic applications. [ABSTRACT FROM AUTHOR]

The extent to which populations will successfully adapt to continued warming temperatures will be a crucial factor in determining future health burdens. Previous health impact assessments of future temperature-related mortality burdens mostly disregard adaptation or make simplistic assumptions. We apply a novel evidence-based approach to model adaptation that takes into account the fact that adaptation potential is likely to vary at different temperatures. Temporal changes in age-specific mortality risk associated with low and high temperatures were characterised for Scotland between 1974 and 2018 using temperature-specific RR ratios to reflect past changes in adaptive capacity. Three scenarios of future adaption were constructed consistent with the SSPs. These adaptation projections were combined with climate and population projections to estimate the mortality burdens attributable to high (above the 90th percentile of the historical temperature distribution) and low (below the 10th percentile) temperatures up to 2080 under five RCP-SSP scenarios. A decomposition analysis was conducted to attribute the change in the mortality burden into adaptation, climate and population. In 1980–2000, the heat burden (21 deaths/year) was smaller than the colder burden (312 deaths/year). In the 2060–2080 period, the heat burden was projected to be the highest under RCP8.5-SSP5 (1285 deaths/year), and the cold burden was the highest under RCP4.5-SSP4 (320 deaths/year). The net burden was lowest under RCP2.6-SSP1 and highest under RCP8.5-SSP5. Improvements in adaptation was the largest factor reducing the cold burden under RCP2.6-SSP1 whilst temperature increase was the biggest factor contributing to the high heat burdens under RCP8.5-SSP5. Ambient heat will become a more important health determinant than cold in Scotland under all climate change and socio-economic scenarios. Adaptive capacity will not fully counter projected increases in heat deaths, underscoring the need for more ambitious climate mitigation measures for Scotland and elsewhere. • A novel evidence-based approach is used to reflect adaptation to extreme temperatures. • Future health burdens associated with extreme temperatures are affected by adaptation. • The projected deaths related to extreme heat are higher than cold in Scotland by 2080. • More than half of the increase in the heat burden by 2080 is attributable to global warming. • The net temperature burden is lowest under RCP2.6-SSP1 and highest under RCP8.5-SSP5. [ABSTRACT FROM AUTHOR]

[Display omitted] • Methods for adaptation projections are varied, with no consistent method established. • Many methods of including adaptation in projections are not based on evidence. • Including adaptation in projections considerably influences estimated mortality. • Combination or framework methods have been developed in more recent years. • Adaptation uncertainty should be included in future health impact assessments. Exposure to high and low ambient temperatures can cause harm to human health. Due to global warming, heat-related health effects are likely to increase substantially in future unless populations adapt to living in a warmer world. Adaptation to temperature may occur through physiological acclimatisation, behavioural mechanisms, and planned adaptation. A fundamental step in informing responses to climate change is understanding how adaptation can be appropriately accounted for when estimating future health burdens. Previous studies modelling adaptation have used a variety of methods, and it is often unclear how underlying assumptions of adaptation are made and if they are based on evidence. Consequently, the most appropriate way to quantitatively model adaptation in projections of health impacts is currently unknown. With increasing interest from decisionmakers around implementation of adaptation strategies, it is important to consider the role of adaptation in anticipating future health burdens of climate change. To address this, a literature review using systematic scoping methods was conducted to document the quantitative methods employed by studies projecting future temperature-related health impacts under climate change that also consider adaptation. Approaches employed in studies were coded into methodological categories. Categories were discussed and refined between reviewers during synthesis. Fifty-nine studies were included and grouped into eight methodological categories. Methods of including adaptation in projections have changed over time with more recent studies using a combination of approaches or modelling adaptation based on specific adaptation strategies or socioeconomic conditions. The most common approaches to model adaptation are heat threshold shifts and reductions in the exposure–response slope. Just under 20% of studies were identified as using an intervention-based empirical basis for statistical assumptions. Including adaptation in projections considerably reduced the projected temperature-mortality burden in the future. Researchers should ensure that all future impact assessments include adaptation uncertainty in projections and assumptions are based on empirical evidence. [ABSTRACT FROM AUTHOR]

Coded caching is a promising technique to smooth out network traffic by storing part of the library content at the users’ local caches. The seminal work on coded caching for single file retrieval by Maddah-Ali and Niesen (MAN) showed the existence of a global caching gain that scales with the total memory in the system, in addition to the known local caching gain in uncoded systems. This paper formulates a novel cache-aided matrix multiplication retrieval problem, relevant for data analytics and machine learning applications. In the considered problem, each cache-aided user requests the product of two matrices from the library. A structure-agnostic solution is to treat each possible matrix product as an independent file and use the MAN coded caching scheme for single file retrieval. This paper proposes two structure-aware schemes, which partition each matrix in the library by either rows or columns and let a subset of users cache some sub-matrices, that improve on the structure-agnostic scheme. For the case where the library matrices are “fat” matrices, the structure-aware row-partition scheme is shown to be order optimal under some constraint. [ABSTRACT FROM AUTHOR]

Caching at the wireless edge nodes is a promising way to boost the spatial and spectral efficiency, for the sake of alleviating networks from content-related traffic. Coded caching originally introduced by Maddah-Ali and Niesen significantly speeds up communication efficiency by transmitting multicast messages simultaneously useful to multiple users. Most prior works on coded caching are based on the assumption that each user may request all content in the library. However, in many applications the users are interested only in a limited set of content that depends on their location. For example, assisted self-driving vehicles may access super High-Definition maps of the area through which they are travelling. Motivated by these considerations, this paper formulates the coded caching problem for location-based content with edge cache nodes. The considered problem includes a content server with access to ${\mathsf N}$ location-based files (e.g., High-Definition maps), ${\mathsf K}$ edge cache nodes located at different regions, and ${\mathsf K}$ users (i.e., vehicles) each of which is in the serving region of one cache node and can retrieve the cached content of this cache node with negligible cost. Depending on the location, each user only requests a file from a location-dependent subset of the library. The objective is to minimize the worst-case load (i.e., the worst-case number of broadcasted bits from the content server among all possible demands). For this novel coded caching problem, we propose a highly non-trivial converse bound under uncoded cache placement (i.e., each cache node directly copies some library bits in its cache), which shows that a simple achievable scheme is optimal under uncoded cache placement. In addition, this achievable scheme is also proved to be generally order optimal within a factor of 3. Finally, we extend the coded caching problem for location-based content to the multiaccess coded caching topology originally proposed by Hachem et al., where each user is connected to ${\mathsf L}$ nearest cache nodes. When ${\mathsf L}\geq 2$ , we characterize the exact optimality on the worst-case load. [ABSTRACT FROM AUTHOR]

This paper first investigates robust tracking problem of a high-order iterative learning control (HOILC) algorithm for two classes of two-dimensional linear discrete time-varying Fornasini–Marchesini systems (2-D LDTVFMS) and 2-D LDTVFMS with input delays with iteration-dependent reference trajectory described by a high-order internal model (HOIM) operator, boundary states and disturbances. An extended high-order linear discrete inequality is proposed to guarantee the ILC tracking error of 2-D LDTVFMS converge robustly to a bounded range, the bound of which is relied on iteration-dependent uncertainties from reference trajectory, boundary states and disturbances. A simulation example on a practical thermal process is used to validate the effectiveness and feasibility of the proposed HOILC law. Additionally, it is verified by theory analysis and simulation that no matter how the ILC controller gain is selected, the convergence condition in Theorem 2 of Wan and Li [(2021). High-order internal model based iterative learning control for 2-D linear FMMI systems with iteration-varying trajectory tracking. IEEE Transactions on Systems Man and Cybernetics: Systems, 51, 1462–1472] is not satisfied. Using the proposed HOILC law, perfect tracking result in Theorem 2 of Wan and Li (2021) can be obtained. [ABSTRACT FROM AUTHOR]

Caching is an efficient way to reduce network traffic congestion during peak hours by storing some content at the users’ local caches. For the shared-link network with end-user-caches, Maddah-Ali and Niesen proposed a two-phase coded caching strategy. In practice, users may communicate with the server through intermediate relays. This paper studies the tradeoff between the memory size ${\mathsf M}$ and the network load ${\mathsf R}$ for the networks where a server with ${\mathsf N}$ files is connected to ${\mathsf H}$ relays (without caches), which in turn are connected to ${\mathsf K}$ users equipped with caches of ${\mathsf M}$ files. When each user is connected to a different subset of ${\mathsf r}$ relays, i.e., ${\mathsf K}= \binom {\mathsf H}{\mathsf r}$ , the system is referred to as a combination network with end-user-caches. In this work, converse bounds are derived for the practically motivated case of uncoded cache contents, that is, bits of the various files are directly pushed into the user caches without any coding. In this case, once the cache contents and the users’ demands are known, the problem reduces to a general index coding problem. This paper shows that relying on a well-known “acyclic index coding converse bound” results in converse bounds that are not tight for combination networks with end-user-caches. A novel converse bound that leverages the network topology is proposed, which is the tightest converse bound known to date. As a result of independent interest, an inequality that generalizes the well-known sub-modularity of entropy is derived. Several novel caching schemes are proposed, based on the Maddah-Ali and Niesen cache placement. These schemes leverage the structure of the combination network or/and perform interference elimination at the end-users. The proposed schemes are proved: (i) to be (order) optimal for some $({\mathsf N}, {\mathsf M}, {\mathsf H}, {\mathsf r})$ parameters regimes under the constraint of uncoded cache placement, and (ii) to outperform the state-of-the-art schemes in numerical evaluations. [ABSTRACT FROM AUTHOR]

This paper formulates a distributed computation problem, where a master asks ${\mathsf N}$ distributed workers to compute a linearly separable function. The task function can be expressed as ${\mathsf K}_{\mathrm{ c}}$ linear combinations of ${\mathsf K}$ messages, where each message is a function of one dataset. Our objective is to find the optimal tradeoff between the computation cost (number of uncoded datasets assigned to each worker) and the communication cost (number of symbols the master must download), such that from the answers of any ${\mathsf N}_{\mathrm{ r}}$ out of ${\mathsf N}$ workers the master can recover the task function with high probability, where the coefficients of the ${\mathsf K}_{\mathrm{ c}}$ linear combinations are uniformly i.i.d. over some large enough finite field. The formulated problem can be seen as a generalized version of some existing problems, such as distributed gradient coding and distributed linear transform. In this paper, we consider the specific case where the computation cost is minimum, and propose novel achievability schemes and converse bounds for the optimal communication cost. Achievability and converse bounds coincide for some system parameters; when they do not match, we prove that the achievable distributed computing scheme is optimal under the constraint of a widely used ‘cyclic assignment’ scheme on the datasets. Our results also show that when ${\mathsf K}= {\mathsf N}$ , with the same communication cost as the optimal distributed gradient coding scheme proposed by Tandon et al. from which the master recovers one linear combination of ${\mathsf K}$ messages, our proposed scheme can let the master recover any additional ${\mathsf N}_{\mathrm{ r}}-1$ independent linear combinations of messages with high probability. [ABSTRACT FROM AUTHOR]

The double Zernike polynomials can describe the aperture dependence and field dependence of non-coaxial optical system aberrations simultaneously, and characterize the complex optical aberrations, which are of great value in the optical system design and alignment. In this paper, the specific analytic forms of all third-order double Zernike aberrations in decentered and/or tilted optical systems are derived based on the nodal aberration theory. This paper realizes the orthogonalization of the third-order aberrations with different aperture dependence and field dependence. The calculation process of the third-order double Zernike aberrations is presented. The ray tracing of the Cassegrain telescope verifies the analytic derivation of the double Zernike aberrations. • Using Double Zernike polynomials to express third-order aberrations in decentered and/or tilted optical systems. • The analysis of the third-order aberrations field dependence. • Using Double Zernike coefficients to calculate full field rms. • Using full field rms to represent the optical system as-built performance. [ABSTRACT FROM AUTHOR]

This paper studies the distributed linearly separable computation problem, which is a generalization of many existing distributed computing problems such as distributed gradient coding and distributed linear transform. A master asks ${\mathsf {N}}$ distributed workers to compute a linearly separable function of ${\mathsf {K}}$ datasets, which is a set of ${\mathsf {K}}_{\mathrm{ c}}$ linear combinations of ${\mathsf {K}}$ equal-length messages (each message is a function of one dataset). We assign some datasets to each worker in an uncoded manner, who then computes the corresponding messages and returns some function of these messages, such that from the answers of any ${\mathsf {N}}_{\mathrm{ r}}$ out of ${\mathsf {N}}$ workers the master can recover the task function with high probability. In the literature, the specific case where ${\mathsf {K}}_{\mathrm{ c}}=1$ or where the computation cost is minimum has been considered. In this paper, we focus on the general case (i.e., general ${\mathsf {K}}_{\mathrm{ c}} $ and general computation cost) and aim to find the minimum communication cost. We first propose a novel converse bound on the communication cost under the constraint of the popular cyclic assignment (widely considered in the literature), which assigns the datasets to the workers in a cyclic way. Motivated by the observation that existing strategies for distributed computing fall short of achieving the converse bound, we propose a novel distributed computing scheme for some system parameters. The proposed computing scheme is optimal for any assignment when ${\mathsf {K}}_{\mathrm{ c}}$ is large and is optimal under the cyclic assignment when the numbers of workers and datasets are equal or ${\mathsf {K}}_{\mathrm{ c}}$ is small. In addition, it is order optimal within a factor of 2 under the cyclic assignment for the remaining cases. [ABSTRACT FROM AUTHOR]

This paper considers the multiaccess coded caching systems formulated by Hachem et al., including a central server containing $N$ files connected to $K$ cache-less users through an error-free shared link, and $K$ cache-nodes, each equipped with a cache memory size of $M$ files. Each user has access to $L$ neighbouring cache-nodes with a cyclic wrap-around topology. The coded caching scheme proposed by Hachem et al. suffers from the case that $L$ does not divide $K$ , where the needed number of transmissions (a.k.a. load) is at most four times the load expression for the case where $L$ divides $K$. Our main contribution is to propose a novel transformation approach to smartly extend the schemes satisfying some conditions for the well known shared-link caching systems to the multiaccess caching systems. Then we can get many coded caching schemes with different subpacketizations for multiaccess coded caching system. These resulting schemes have the maximum local caching gain (i.e., the cached contents stored at any $L$ neighbouring cache-nodes are different such that the number of retrieval packets by each user from the connected cache-nodes is maximal) and the same coded caching gain as the original schemes. Applying the transformation approach to the well-known shared-link coded caching scheme proposed by Maddah-Ali and Niesen, we obtain a new multiaccess coded caching scheme that achieves the same load as the scheme of Hachem et al. but for any system parameters. Under the constraint of the cache placement used in this new multiaccess coded caching scheme, our delivery strategy is approximately optimal when $K$ is sufficiently large. Finally, we also show that the transmission load of the proposed scheme can be further reduced by compressing the multicast message. [ABSTRACT FROM AUTHOR]

In this article, robust and convergent properties of iterative learning control (ILC) laws are investigated for two kinds of two-dimensional (2-D) linear discrete systems (LDS) in the second Fornasini–Marchesini’s model (FMMII). The iteration-dependent uncertainties in reference trajectories, boundary states, and disturbances are considered in the ILC designs of 2-D FMMII. By virtue of the lifting matrix/vector technique, the ILC processes of two kinds of 2-D FMMII are transformed into 2-D linear inequalities. As a result, robust and convergent conditions are obtained for the proposed ILC laws. It is theoretically proved that by using the proposed ILC laws, under the discussed iteration-dependent uncertainties, the ILC tracking errors of 2-D FMMII can be driven into a residual range, the bound of which is relevant to the bound parameters of uncertainties. In particular, when the iteration-dependent uncertainties of 2-D FMMII are progressively convergent in iteration domain, an accurate tracking to the desired reference trajectory can be realized except at the boundaries. Numerical simulations are used to illustrate the validity and feasibility of the designed ILC laws. [ABSTRACT FROM AUTHOR]

We consider the problem of cache-aided Multiuser Private Information Retrieval (MuPIR) which is an extension of the single-user cache-aided PIR problem to the case of multiple users. In cache-aided MuPIR, each of the $K_{\mathrm{ u}}$ cache-equipped users wishes to privately retrieve a message out of $K$ messages from $N$ databases each having access to the entire message library. Demand privacy requires that any individual database learns nothing about the demands of all users. The users are connected to each database via an error-free shared-link. In this paper, we aim to characterize the optimal trade-off between user cache memory and communication load for such systems. First, we propose a novel approach of cache-aided interference alignment (CIA), for the MuPIR problem with $K=2$ messages, $K_{\mathrm{ u}}=2$ users and $N\ge 2$ databases. The CIA approach is optimal when the cache placement is uncoded. For general cache placement, the CIA approach is optimal when $N=2$ and 3 verified by the computer-aided converse approach. Second, for the general case, we propose a product design (PD) which incorporates the PIR code into the linear caching code. The product design is shown to be order optimal within a multiplicative factor of 8 and is exactly optimal in the high memory regime. [ABSTRACT FROM AUTHOR]

Background: After the low quality of Chinese clinical practice guidelines (CPGs) for respiratory diseases published from 1979 to 2013 was reported, some handbooks were published to standardize guidelines' development recently. There was a great increase in the production and dissemination of CPGs annually in China, whose quality and potential impact were unknown. Methods: A systematic search of four literature databases was performed for the period January 2013 to December 2018 to identify Chinese CPGs for respiratory diseases. Eligible CPGs were evaluated using the appraisal of guidelines for research and evaluation II (AGREE II) instrument. Results: A total of 197 CPGs were identified for review. Compared with the result of previous study, the increased scores of the six AGREE II domains were screened: Scope and purpose (57.3% vs. 57.8%), Stakeholder involvement (17.6% vs. 25.0%), Rigor of development (10.2% vs. 13.2%), Clarity and presentation (55.2% vs. 58.4%), Applicability (9.3% vs. 25.9%), and Editorial independence (1.1% vs. 6.3%). The improved overall assessment for included CPGs were: Recommended (4, 2.0% vs. 0, 0%) and Recommended with modifications (26, 13.2% vs. 3, 2.8%). The improved level of evidence used to make recommendations were 59, 11.9% versus 168, 22.4% and 88, 17.7% versus 195, 26.0%, A and B, respectively. Conclusions: The overall quality of CPGs for respiratory diseases published from 2013 to 2018 in China was slightly improved, but had a big gap with the optimum level, especially in Rigor of development and Editorial independence. Increased efforts are required to enable the development of high‐quality evidence‐based CPGs for respiratory diseases. [ABSTRACT FROM AUTHOR]

The coded caching scheme originally proposed by Maddah-Ali and Niesen (MAN) transmits coded multicast messages from a server to users equipped with caches via a capacitated shared-link and was shown to be information theoretically optimal within a constant multiplicative factor. This work extends the MAN scheme to a class of two-hop wired-wireless networks including one server connected via fronthaul links to a layer of H helper nodes (access points/base stations), which in turn communicate via a wireless access network to K users, each equipped with its own cache. Two variants are considered, which differ in the modeling of the access segment. Both models should be regarded as abstractions at the “network layer” for physical scenarios such as local area networks and cellular networks, spatially distributed over a certain coverage area. The key of our approach consists of routing MAN-type multicast messages through the network and formulating the optimal routing scheme as an optimization problem that can be solved exactly or for which we give powerful heuristic algorithms. Our approach addresses at once many of the open practical problems identified as stumbling blocks for the application of coded caching in practical scenarios, namely: asynchronous streaming sessions, finite file size, scalability of the scheme to large and spatially distributed networks, user mobility and random activity (users joining and leaving the system at arbitrary times), decentralized prefetching of the cache contents, end-to-end encryption of HTTPS requests, which renders the helper nodes oblivious of the users’ demands. [ABSTRACT FROM AUTHOR]

Coded caching has the potential to greatly reduce network traffic by leveraging the cheap and abundant storage available in end-user devices so as to create multicast opportunities in the delivery phase. In the seminal work by Maddah-Ali and Niesen (MAN), the shared-link coded caching problem was formulated, where each user demands one file (i.e., single file retrieval). This article generalizes the MAN caching problem formulation from single file retrieval on the binary filed to general scalar linear function retrieval on an arbitrary finite field. The proposed novel scheme is linear, based on MAN uncoded cache placement, and leverages ideas from interference alignment. Quite surprisingly, the worst-case load of the proposed scheme among all possible demands is the same as the one of the scheme by Yu, Maddah-Ali, and Avestimehr (YMA) for single file retrieval. The proposed scheme has thus the same optimality guarantees as YMA, namely, it is optimal under the constraint of uncoded cache placement, and is optimal to within a factor 2 otherwise. Some extensions of the proposed scheme are then discussed. It is shown that the proposed scheme works not only on arbitrary finite field, but also on any commutative ring. The key idea of this article can be also extended to all scenarios to which the original MAN scheme has been extended, including but not limited to demand-private retrieval and Device-to-Device networks. [ABSTRACT FROM AUTHOR]

Maddah-Ali and Niesen (MAN) in 2014 showed that coded caching in single bottleneck-link broadcast networks allows serving an arbitrarily large number of cache-equipped users with a total link load (bits per unit time) that does not scale with the number of users. Since then, the general topic of coded caching has generated enormous interest both from the information theoretic and (network) coding theoretic viewpoint, and from the viewpoint of applications. Building on the MAN work, this paper considers a particular network topology referred to as cache-aided Fog Radio Access Network (Fog-RAN), that includes a Macro-cell Base Station (MBS) co-located with the content server, several cache-equipped Small-cell Base Stations (SBSs), and many users without caches. Some users are served directly by the MBS broadcast downlink, while other users are served by the SBSs. The SBSs can also exchange data via rounds of direct communication via a side channel, referred to as “sidelink”. For this novel Fog-RAN model, the fundamental tradeoff among (a) the amount of cache memory at the SBSs, (b) the load on the downlink (from MBS to directly served users and SBSs), and (c) the aggregate load on the sidelink is studied, under the standard worst-case demand scenario. We propose a converse bound whose key novelty is to jointly bound the downlink load an the sidelink load. For the achievability, by leveraging the network topology, we propose two classes of memory-loads point, where the SBS sidelink load is minimum and the MBS downlink load is minimum, respectively. By memory-sharing between these two classes of memory-loads points, some exact or order optimality results are obtained. Several existing models (e.g., Device-to-Device coded caching, single bottleneck-link coded caching with shared caches, single bottleneck-link caching coded caching with cache-less users) are recovered as special cases of this network model and by-product results of independent interest are given. Finally, the role of topology-aware versus topology-agnostic caching is discussed. [ABSTRACT FROM AUTHOR]

This paper is concerned with iterative learning control (ILC) algorithms for two-dimensional (2-D) linear discrete systems described by the first Fornasini–Marchesini model (FMMI) with iteration-varying reference trajectories/profiles. The variation of reference trajectories in iteration domain is represented by a high-order internal model (HOIM) formula. Robustness and convergence of two types of HOIM-based ILC laws with different boundary conditions are investigated, respectively. A strategy employed in this paper is to reconstruct the HOIM-based ILC process of the 2-D linear FMMI system into a set of 2-D linear inequalities or a 2-D linear Roesser model such that sufficient robustness/convergence conditions of the HOIM-based ILC laws are obtained. Under random boundary conditions, the designed ILC law (9) is capable to drive the ILC tracking error into a bounded range. Moreover, under the HOIM-based boundary conditions, a perfect tracking to the iteration-varying reference trajectories can be achieved by utilizing the proposed ILC law (32). Two simulation examples are given to validate the effectiveness of the two proposed ILC algorithms. [ABSTRACT FROM AUTHOR]

Developing green-safe, efficient and recyclable catalysts is crucial for the chemical industry. So far, organic photocatalysis has been proved to be an environmentally friendly and energy-efficient synthetic technology compared with traditional metal catalysis. As a versatile catalytic platform, hyper-crosslinked polymers (HCPs) with large surface area and high stability are easily prepared. In this report, we successfully constructed two porous HCP photocatalysts (TZ-HCPs) featuring s-tetrazine units and surface areas larger than 700 m2 g−1 through Friedel–Crafts alkylation reactions. The rational energy-band structures and coexisting micro- and mesopores endow TZ-HCPs with excellent activities to realize the green synthesis of benzimidazoles (28 examples, up to 99% yield, 0.5–4.0 h) in ethanol. Furthermore, at least 21 iterative catalytic runs mediated by TZ-HCP1D were performed efficiently, with 96–99% yield. This study of TZ-HCPs sheds light on the wide-ranging prospects of application of HCPs as metal-free and green photocatalysts for the preparation of fine chemicals. [ABSTRACT FROM AUTHOR]

A solid inclusion is embedded in a soft matrix supported by a rigid substrate. To simulate finger palpation, a spherical indenter exerts a vertical load on the matrix surface, followed by a lateral motion. A deep inclusion first rises close to the surface, dives under the indenter, and emerges from the leeside of the traversing indenter. The inclusion trajectory is essentially symmetric about the axis where the inclusion lies. A shallow inclusion is first pushed sideways, but an instability causes it to jump spontaneously to the rear following an asymmetric path. Such instability is a specific feature in hyperelastic materials. [ABSTRACT FROM AUTHOR]

In the present day, when centralized energy storage technology is becoming increasingly mature, the cooperative energy sharing framework between the combined cooling, heating, and power (CCHP) systems and a shared energy storage provider (SESP) can effectively promote the local consumption of renewable energy and reduce the social energy cost. In this study, the optimal operation models of CCHP and SESP are first developed by considering the electric energy trading of the CCHP and the SESP. Then the CCHP–SESP cooperative operation model is established based on Nash bargaining theory, followed by equating it into two subproblems of coalition social energy cost minimization and electric energy trading payment negotiation. The alternating direction method of multipliers approach is introduced to solve the energy‐sharing problems in a distributed way. Numerical simulation results show the effectiveness of the proposed energy‐sharing framework. Simulation results show that the proposed bargaining‐based energy‐sharing framework can significantly reduce the social energy cost and improve the utilization rate of energy storage resources. [ABSTRACT FROM AUTHOR]

Bipolar redox‐active organic molecule (BROM) is a feasible strategy to address the cross‐contamination issue of the electrolyte and, thus, improve the stability of the flow battery. Herein, a highly‐soluble BROM is developed by combining the 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) and viologen moieties, and extensive characterizations are performed to evaluate its applicability in flow battery. Salient findings are as follows. First, the compound, viz. 1‐(1‐oxyl‐2,2,6,6‐tetramethylpiperidin‐4‐yl)‐1′‐(3‐(trimethylammonio)propyl)‐4,4′‐bipyridinium trichloride ((TPABPy)Cl3), features highly hydrophilic groups and yields a high aqueous solubility of 1.76 m. Second, the electrochemical result reveals that the (TPABPy)Cl3 displays two pairs of highly reversible peaks at −0.56 and 0.76 V, which respectively correspond to the viologen and TEMPO moieties. The electronic structure during the redox reactions is identified by both the density functional theory calculation and the electron paramagnetic resonance. Third, the flow battery fed with the 1.0 m (TPABPy)Cl3 solution delivers a high capacity of 25 Ah L−1 and a superior stability over the non‐bipolar counterparts. More to the point, the capacity decay can be effectively recovered by applying the polarity‐inversion rebalance strategy on the BROM. In summary, this work provides a molecular engineering way to rationally design a BROM to improve the capacity and stability of aqueous organic redox flow batteries. [ABSTRACT FROM AUTHOR]

An ouzo droplet is a multicomponent liquid comprising ethanol, water, and anise oil, each possessing distinct thermophysical properties, volatility, and mutual miscibility. Evaporation leads to the complex physicochemical process of coupled mass and heat transfer, spontaneous emulsification, and liquid–liquid phase separation, known as the ouzo effect. An acoustically levitated ouzo droplet undergoes five characteristic stages of evaporation based on temporal temperature variation. Such levitated droplet shows a significantly longer lifespan upon evaporation because of the thermal isolation in air, as well as a drastic initial cooling. Sessile droplets, on the other hand, have heat transferred from the surroundings via the substrate to replenish latent heat of vaporization. A conductive substrate thus helps the droplet to stay close to the ambience and a shorter lifespan. A rudimentary theoretical model based on dimensional analysis is developed and shows consistency with measurements. [ABSTRACT FROM AUTHOR]

We fitted 75 pulses from 44 gamma‐ray burst (GRB) prompt emission lightcurves, including four short ones and 40 long ones. Each pulse is fitted by a fast‐rising exponential‐decay (FRED) model. The statistical properties of these pulses are analyzed and compared with previous works. We found that the FRED model is almost suitable to describe all the pulses. We reconfirmed that there is a linear correlation between the full width at half maximum FWHM$$ \mathrm{FWHM} $$ and the pulse rising time Trise$$ {T}_{\mathrm{rise}} $$, which supports the idea that the individual pulse is emitted at once within one explosion. Moreover, we found that several pulses do not obey the FWHM−Trise$$ \mathrm{FWHM}-{T}_{\mathrm{rise}} $$ correlation, this implies that the radiation process of the prompt emission especially in the multi‐pulse GRBs might involve more than one type and even possibly change with time. The innovation of this work lies in examining the statistical characteristics of lightcurves of both long and short‐duration GRBs and re‐evaluating the applicability of empirical relationships discovered by predecessors to both types of GRBs while paying special attention to the existence of outlier pulses. This work has positive implications for further exploring the diversity of GRB prompt radiation mechanisms. [ABSTRACT FROM AUTHOR]

In this paper, convergent property of a saturation-strategy-based iterative learning control (ILC) law is first investigated for a class of two-dimensional linear discrete first Fornasini–Marchesini model (2-D LDFFM) with input saturation. A three-dimensional dynamical process is transformed into a 2-D dynamical process by row scanning approach or column scanning approach. As a result, it is theoretical proved no matter which method is adopted, perfect tracking on the desired reference surface is accomplished by virtue of the 2-D linear inequality theory. Numerical simulation on a practical thermal process is used to illustrate the effectiveness and feasibility of the designed ILC law. In addition, ILC convergence analysis for 2-D LDFFM with input delay and input saturation is discussed. [ABSTRACT FROM AUTHOR]

Data shuffling of training data among different computing nodes (workers) has been identified as a core element to improve the statistical performance of modern large-scale machine learning algorithms. Data shuffling is often considered as one of the most significant bottlenecks in such systems due to the heavy communication load. Under a master-worker architecture (where a master has access to the entire dataset and only communication between the master and the workers is allowed) coding has been recently proved to considerably reduce the communication load. This work considers a different communication paradigm referred to as decentralized data shuffling, where workers are allowed to communicate with one another via a shared link. The decentralized data shuffling problem has two phases: workers communicate with each other during the data shuffling phase, and then workers update their stored content during the storage phase. The main challenge is to derive novel converse bounds and achievable schemes for decentralized data shuffling by considering the asymmetry of the workers’ storages (i.e., workers are constrained to store different files in their storages based on the problem setting), in order to characterize the fundamental limits of this problem. For the case of uncoded storage (i.e., each worker directly stores a subset of bits of the dataset), this paper proposes converse and achievable bounds (based on distributed interference alignment and distributed clique-covering strategies) that are within a factor of 3/2 of one another. The proposed schemes are also exactly optimal under the constraint of uncoded storage for either large storage size or at most four workers in the system. [ABSTRACT FROM AUTHOR]

A binder-free Ni (oxy)hydroxide on Ni foam was prepared through an in-situ electrochemical activation method. Ni (oxy)hydroxide is active for the oxygen evolution reaction. The Ni (oxy)hydroxide directly formed on the surface of Ni foam as a binder-free catalyst not only exhibited large electrochemically active area, but also displayed low interfacial electronic resistance and low charge transfer resistance. Therefore, the optimized Ni (oxy)hydroxide exhibits an overpotential of 288 and 370 mV at 10 and 500 mA cm−2, respectively, in 1.0 M KOH for the oxygen evolution reaction, as well as favorable during 240 h at 100 mA cm−2. • Electrochemical activation method is a time and energy-saving method. • Strong electronic interaction between NiOOH and Ni favors electron transfer. • High valence Ni in NiOOH enhances the chemisorption of OH− during OER. • In situ formation of NiOOH layer reduces the interfacial electronic resistance. [ABSTRACT FROM AUTHOR]

Caching is an efficient way to reduce network traffic congestion during peak hours, by storing some content at the user’s local cache memory, even without knowledge of user’s later demands. Maddah-Ali and Niesen proposed a two-phase (placement phase and delivery phase) coded caching strategy for broadcast channels with cache-aided users. This paper investigates the same model under the constraint that content is placed uncoded within the caches, that is, when bits of the files are simply copied within the caches. When the cache contents are uncoded and the users’ demands are revealed, the caching problem can be connected to an index coding problem. This paper focuses on deriving fundamental performance limits for the caching problem by using tools for the index coding problem that were either known or are newly developed in this work. First, a converse bound for the caching problem under the constraint of uncoded cache placement is proposed based on the “acyclic index coding converse bound.” This converse bound is proved to be achievable by the Maddah-Ali and Niesen’s scheme when the number of files is not less than the number of users, and by a newly derived index coding achievable scheme otherwise. The proposed index coding achievable scheme is based on distributed source coding and strictly improves on the widely used “composite (index) coding” achievable bound and its improvements, and is of independent interest. An important consequence of the findings of this paper is that advancements on the coded caching problem posed by Maddah-Ali and Niesen are thus only possible by considering strategies with coded placement phase. A recent work by Yu et al has however shown that coded cache placement can at most half the network load compared to the results presented in this paper. [ABSTRACT FROM AUTHOR]

We consider a cache-aided wireless device-to-device (D2D) network of the type introduced by Ji et al., where the placement phase is orchestrated by a central server. We assume that the devices’ caches are filled with uncoded data, and the whole content database is contained in the collection of caches. After the cache placement phase, the files requested by the users are serviced by inter-device multicast communication. For such a system setting, we provide the exact characterization of the optimal load-memory trade-off under the assumptions of uncoded placement and one-shot delivery. In particular, we derive both the minimum average (under uniformly distributed demands) and the minimum worst-case sum-load of the D2D transmissions, for given individual cache memory size at disposal of each user. Furthermore, we show that the performance of the proposed scheme is within factor 4 of the information-theoretic optimum. Capitalizing on the one-shot delivery property, we also propose an extension of the presented scheme that provides robustness against random user inactivity. [ABSTRACT FROM AUTHOR]

Pediatric intracranial aneurysms are extremely rare. In this age group, cerebral vascular anomalies have been associated with the development of intracranial aneurysms. We present a case of a previously well 11-year-old boy who presented with seizures secondary to a giant, unruptured, and partially thrombosed right middle cerebral artery (MCA) aneurysm. Extensive workup for underlying infective and autoimmune etiology was negative. Of interest, this vascular lesion was found to originate from an anomalous M2 branch, which ran an aberrant parallel course within the Sylvian fissure to the main and distally bifurcating MCA. The patient underwent successful surgical clipping and excision of the giant aneurysm. Because of the infrequency of the diagnosis, clinical presentation, and its unique neurovascular anatomy, the management of this case is discussed in corroboration with current literature. In addition, highlighting this unusual case in an individual adds to the growing body of literature for better disease understanding, especially in the pediatric population. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metagenome sequencing reveals changes in functional genes under the impact of Ce(III). • The performance of the reactor began to drop when the Ce(III) content got to 25 mg/L. • Elevated Ce(III) concentration leads to shift of the dominant anammox bacteria. • Ca. brocadia and Ca. jettenia also have genes for other nitrogen metabolic pathways. • Ce(III) increased the abundance of functional genes associated with EPS production. The high Ce(III) content in ionic rare-earth tailings wastewater has hindered the application of anammox process in this field. Here, the effect of Ce(III) on the performance of anammox processes was investigated, and the evolution of microbial communities and functional genes was explored using metagenomic sequencing. The results showed that the reactor nitrogen removal rate decreased when the Ce(III) concentration reached 25 mg/L, although ammonia nitrogen removal (92.31%) and nitrogen removal efficiency (81.33%) remained at a high level; however, both showed a significant decreasing trend. The relative abundance of anammox bacteria increased continuously from P1–P5, reaching 48.81%, whereas the relative abundance of Candidatus jettenia reached 33.71% at P5, which surpassed that of Candidatus brocadia as the most abundant anammox bacteria, and further analysis of functional genes and metabolic pathways revealed that Candidatus brocadia was richer in biochemical metabolic genes, whereas Candidatus jettenia had richer efflux genes. [ABSTRACT FROM AUTHOR]

Targeting at the ambient noise test of a large-scale fan, a sparse measurement method is proposed to deal with placing test-points. According to the acoustic and propagational characteristics of fan noise and the principle of sound pressure test, the sparsification of test-points is presented for optimizing the microphone locations. The outdoor ambient sound pressures of fan noise are tested at the sparse points and processed by time-frequency refinement analysis. As results of that, sparse measurement can obtain the messages of sound field effectively and thus get a comprehensive evaluation on the noise. This study extends the application of sound pressure test and provides a base for quantitative sparse measurement on ambient noises. [ABSTRACT FROM AUTHOR]

The theory of two-dimensional linear quaternion-valued differential equations (QDEs) was recently established {see the work of Kou and Xia [Stud. Appl. Math. 141(1), 3–45 (2018)]}. They observed some profound differences between QDEs and ordinary differential equations. Also, an algorithm to evaluate the fundamental matrix by employing the eigenvalues and eigenvectors was presented in the work of Kou and Xia [Stud. Appl. Math. 141(1), 3–45 (2018)]. However, the fundamental matrix can be constructed providing that the eigenvalues are simple. If the linear system has multiple eigenvalues, how to construct the fundamental matrix? In particular, if the number of independent eigenvectors might be less than the dimension of the system, that is, the numbers of the eigenvectors are not enough to construct a fundamental matrix, how to find the "missing solutions"? The main purpose of this paper is to answer this question. [ABSTRACT FROM AUTHOR]

Highlights • Automatic STN detection improves the efficiency and accuracy of target location. • Both spike independent and dependent features are useful for detection of STN. • Further research required for STN sub territories. Abstract Objective This study seeks to systematically review the selection of features and algorithms for machine learning and automation in deep brain stimulation surgery (DBS) for Parkinson's disease. This will assist in consolidating current knowledge and accuracy levels to allow greater understanding and research to be performed in automating this process, which could lead to improved clinical outcomes. Methods A systematic literature review search was conducted for all studies that utilized machine learning and DBS in Parkinson's disease. Results Ten studies were identified from 2006 utilizing machine learning in DBS surgery for Parkinson's disease. Different combinations of both spike independent and spike dependent features have been utilized with different machine learning algorithms to attempt to delineate the subthalamic nucleus (STN) and its surrounding structures. Conclusion The state-of-the-art algorithms achieve good accuracy and error rates with relatively short computing time, however, the currently achievable accuracy is not sufficiently robust enough for clinical practice. Moreover, further research is required for identifying subterritories of the STN. Significance This is a comprehensive summary of current machine learning algorithms that discriminate the STN and its adjacent structures for DBS surgery in Parkinson's disease. [ABSTRACT FROM AUTHOR]

Fingering of an inviscid liquid droplet upon impact on a super-hydrophobic surface is revisited. Generation of coronal fingers is investigated here using a transverse rim instability analysis based on the toroidal curvature of rim, instead of the linear front assumption in the classical Rayleigh-Plateau (R-P) model. The governing equations are formulated from the first principles and solved numerically. For a droplet with a known volume and impact velocity, the model predicts the number of spires upon impact, k. Here k is found to be the largest wave number with a positive growth rate on the droplet rim and is shown to be in the order of (Weber)3/5. The theoretical model is consistent with our water droplet experiments for 60 < We < 160, superseding the R-P prediction. [ABSTRACT FROM AUTHOR]

Five new oleanane-type triterpenoid saponins, oleiferasaponins D1-D5 (1-5), were isolated from the defatted seeds of Camellia oleifera Abel. Their structures were elucidated by spectroscopic and chemical methods. The cytotoxic activities of compounds 1-5 were evaluated against five human tumor cell lines (HCT-116, HepG2, BGC-823, NCI-H1650, and A2780). Compounds 1-2 exhibited cytotoxic activity against five human cancer cell lines, with IC50 values ranging from 3.31 to 10.23 μM. Compounds 3-5 showed moderate cytotoxic activities toward the tested cell lines. [ABSTRACT FROM AUTHOR]

The thermal, mechanical and durability properties of lightweight strain hardening cementitious composite (LSHCC) as well as the effectiveness of using LSHCC for structural retrofitting of unreinforced masonry (URM) wall is reported in this study. The proper range of water content, dosage of superplasticiser and viscosity modifying agent was explored from the survivability test of glass micro hollow bubble (3M-S15), which was much more fragile but effective in reducing the thermal conductivity of the composite than other studies. Then, the tensile properties of LSHCC with plastic-state density of about 1300–1400 kg/m 3 from different proportion of replacement of ordinary Portland cement (OPC) by fly ash (FA) and ground granulated blast-furnace slag (GGBS) as well as different volume fraction of polyvinyl alcohol (PVA) fibre were measured. The tensile ductility of LSHCC of replacement by FA was in general better than pure OPC or with GGBS blends. The tensile strength and ductility of LSHCC with 1.75% volume fraction of PVA fibre was about 3 MPa and 2–4%, respectively. The compressive strength ranged from 14 to 31 MPa. The thermal conductivity of selected LSHCC ranged from 0.34 to 0.51 W/m·K. The coefficient of water permeability of LSHCC was comparable with reference normal concrete and the engineered cementitious composite (ECC-M45) in the literature. The coefficient of chloride diffusivity of most LSHCC in this study was lower than the reference concrete because of the chloride binding of FA and GGBS. However, the carbonation rate of the LSHCC was generally higher. Three sets of LSHCC with similar tensile strength but different ductility were chosen for the evaluation of the effectiveness on structural retrofitting of an unreinforced masonry wall by in-plane and out-of-plane pushover analysis. The parameters of a finite element model with smeared crack material model was tuned based on the stress-strain relationship of LSHCC measured from the tensile tests in this study. There was no improvement of using LSHCC with 0.6% tensile ductility. By applying a 10 mm thick LSHCC with 2.2% and 4.4% tensile ductility on each side of an URM wall, the ductility of the retrofitted wall under in-plane loading was increased by 38% and 72%, respectively while it was increased by 164% for both kinds of LSHCCs for out-of-plane loading. [ABSTRACT FROM AUTHOR]

Prefabricated lightweight concrete building fasçade can improve the energy efficiency of buildings and reduce the carbon emission of transportation. However, it is essential to maintain the dimensional stability of the full scale element. The drying shrinkage of lightweight foamed concrete was investigated in this study. The hypothesis of using the drying shrinkage of normal weight concrete to approximate that of lightweight foamed concrete of dry density about 1500 kg/m 3 counterpart was verified. Three different strategies of reducing drying shrinkage were studied. The drying shrinkage of common ingredients of ordinary Portland cement (OPC) and ground granulated blast-furnace slag (GGBS) was commonly up to 2000–3000  μ ε . The use of magnesium expansive agent with different calcination conditions could not reduce the drying shrinkage. The use of calcium sulfoaluminate (CSA) cement with OPC and GGBS could significantly reduce the drying shrinkage within 1000  μ ε in standard testing environment. The formulation developed in laboratory was scaled up in a concrete production plant for prefabricated concrete elements. A lightweight full scale panel (the wet density was about 1700 kg/m 3 ) was fabricated. The drying shrinkage of the developed formulation with CSA cement was only 161  μ ε in the field test. A hygro-mechanical model was developed to model the diffusion, shrinkage and plastic strain evolution. The incremental stress-strain constitutive relationship of the hygro-mechanical model was derived for incorporating it into general finite element routine. The model parameters were calibrated by the drying shrinkage measurements in this study. The calibrated model demonstrated the cracking potential of three typical reinforced concrete panels of three different formulations studied in this study. [ABSTRACT FROM AUTHOR]

The imidazolium salt [(S,S)-tBuNC3H3NCHPhCHPhNH2]PF6, (S,S)-11·HPF6 is a precursor to the enantiopure "Kaibene" ligand, tBu-Kaibene, (S,S)-11 featuring a tert-butyl group on the N-heterocyclic carbene (NHC) ring-nitrogen atoms. It has been prepared in high yield and purity by refluxing a chiral cyclic sulfamidate with 1-tert-butylimidazole. Similarly (S,S)-12·HPF6 with a mesityl group at the imidazolium ring-nitrogen atom has been prepared in the same fashion and serves as a source of Mes-Kaibene, (S,S)-12. These bidentate Kaibene ligands feature an NHC and a primary amine separated by a chiral linker. Salts (S,S)-11·HPF6 or (S,S)-12·HPF6 react with base and AgI or CuI to give a total of four M(Kaibene)2I compounds (M = Ag or Cu). At 22 °C, the amine-functionalized imidazolium cations undergo oxidative addition to iridium(I) in [IrCl(cod)]2 (cod = 1,5-cyclooctadiene) to generate iridium(III) hydride R-Kaibene compounds [IrHCl(cod)((S,S)-11)](PF6) (17) and [IrHCl(cod)((S,S)-12)](PF6) (18), respectively, each as a mixture of six configurational isomers. In contrast, the salt (S,S)-11·HPF6 reacts with [Ir(OtBu)(cod)]2 to produce a bimetallic iridium compound with (S,S)-11 as the bridging ligand. This compound contains interesting NH···Cl and NH···Ir noncovalent intramolecular interactions. Salt (S,S)-12·HPF6 reacts with silver oxide to yield [Ag2((S,S)-12)2](PF6)2 (20). Reagent 20 serves as an efficient transmetalation reagent to deliver to each rhodium in [RhCl(cod)]2 1 equiv of (S,S)-12 as a bidentate ligand to give [Rh(cod)((S,S)-12)](PF6). In the reaction between [IrCl(cod)]2 and 20, (S,S)-12 ends up coordinated in an iridium(III) hydride complex (22) as a tridentate ligand via the NHC, NH2, and a cyclometalated phenyl group. The two iridium hydride compounds, 18 and 22, are catalysts for the hydrogenation of a range of ketones (turnover number up to 499, turnover frequency up to 249 h-1, with er (enantiomeric ratio) up to 35:65 R:S). [ABSTRACT FROM AUTHOR]

An ultrathin (thickness 1.0 nm) 2D nitrogen-doped hierarchically porous carbon (2DNHPC) film is developed by the nanocasting method; for comparison, a 3D nitrogen-doped ordered mesoporous carbon (3DNOMC) is also synthesized. Characterizations reveal that 2DNHPC is featured by an extremely high aspect ratio (several hundred) and a bimodal pore distribution. Such a 2D hierarchically porous structure is found to facilitate both the mass transfer of the reactive species and the utilization of active site in the electrode. First, 2DNHPC yields a larger limiting current than does 3DNOMC for the oxygen reduction reaction (ORR), revealing the key role of the low dimensional structure to facilitate the mass transfer. Second, at the loading of 500 μg cm −2 , 2DNHPC shows the same kinetic current with 3DNOMC, indicating that the two catalysts have the same active site and turnover frequency. In comparison, at a lower loading of 250 μg cm −2 , the kinetic current of 2DNHPC remains unchanged, which however seriously deteriorates for 3DNOMC. This result strongly highlights the effect of the carbon dimension on the utilization efficiency of the active site. Finally, it is noted that 2DNHPC yields a comparable ORR electrocatalytic activity and long-term stability with commercial Pt catalyst in both alkaline and acid media. [ABSTRACT FROM AUTHOR]

The nature of active sites and mechanism of hydrogen evolution reaction (HER) on the nitrogen-doped carbon catalyst is extensively investigated, by combining physicochemical and electrochemical methods. Two carbon catalysts, with the same chemical nature but different nitrogen content, are employed in this investigation. Electrochemical methods are applied to investigate the electrochemical behavior at different pH values (1.0–2.0, 12.0–13.0). It is found that increasing nitrogen content has a positive effect on the electrocatalytic activity, and therefore, the doped nitrogen atoms should be the active sites. The kinetic current, normalized by the surface nitrogen content, is found to be the same for the two catalysts, confirming the above claim. As such, HER is proposed to proceed on these active sites by the Volmer-Heyrovsky mechanism. The electrochemical tests reveal that the electrocatalytic activity closely relies on the solution pH, which is due to the chemical evolution of the active site in different solutions. In acid media, the electrocatalytic activity increases with the concentration of proton, and the Tafel slope is ca. 120 mV dec −1 . It is proposed that the electrochemical desorption of proton on the doped nitrogen atoms is the rate determining step (r.d.s.). In alkaline media, the electrocatalytic activity increases with pH, because the increase in pH dramatically enhances the basicity or the surface charge density, thereby facilitating charge transfer and improving activity. In alkaline media, Tafel analysis shows that Heyrovsky step is the rate determining. [ABSTRACT FROM AUTHOR]

The effect of the pore structure of SBA-15, which is tuned by varying the hydrothermal temperature (90–150 °C), is investigated on nitrogen-doped ordered mesoporous carbon. It is found that the pore structure of SBA-15 yields effects on both the composition and the pore structure of carbon, which thereby affecting its electrocatalytic activity for the oxygen reduction reaction (ORR). XPS reveals that the nitrogen content of the template-free carbon is 2.79 at.%, while dramatically increases to 4.48, 5.01 and 4.16 at.% for the three template-aided carbon catalysts with SBA-15 synthesized at 90, 130 and 150 °C, respectively. Nitrogen ad/desorption isotherms show that the specific surface area of the template-free carbon is 257 m 2 g −1 , which increases to 724, 731 and 691 m 2 g −1 for the above three carbons. Such changes correlate well with the electrochemical results. RRDE results show that the template-aided carbon catalysts yield better activity and selectivity for the ORR than does the template-free one. And the best performance is achieved for the carbon catalyst with SBA-15 synthesized at 130 °C, which coincidentally has the highest nitrogen content and surface area. [ABSTRACT FROM AUTHOR]

Hexagonal Bi 2 Te 3 nanosheets with uniform morphology were facilely synthesized through a hydrothermal method at 180 °C. X ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and selected area electron diffraction (SAED) were employed to characterize the Bi 2 Te 3 nanosheets. The results clearly indicate that uniform Bi 2 Te 3 nanosheets with a side length of 300–400 nm were obtained. Bi 2 Te 3 nanosheet/ZnO nanoparticle (Bi 2 Te 3 NS/ZnO NP) composite photoanodes were fabricated with Bi 2 Te 3 NS concentration in the range of 0–0.25 at.%. The effect of Bi 2 Te 3 NS contents in composite photoanode on the performance of dye-sensitized solar cells (DSSCs) was systematically investigated. The photocurrent density-voltage ( J-V ) characteristics indicate that the DSSCs with Bi 2 Te 3 NS/ZnO NP composite photoanode exhibit significantly improved photovoltaic performance. Typically, the highest energy conversion efficiency of 4.10% which is increased by 46.95% compared with that of the bare ZnO can be achieved in the DSSC with 0.15 at.% Bi 2 Te 3 NS embedding. The EIS results further confirm that a moderate amount of Bi 2 Te 3 NS in photoanode could not only improve the electrons transport and suppress the charge recombination rate, but also enhance the electron collection efficiency. Furthermore, the excellent thermoelectric performance of Bi 2 Te 3 NS in the photoanode could greatly increase the electron density and lower the temperature of the DSSCs effectively. All these results suggest that the Bi 2 Te 3 NS/ZnO NP composite photoanode could highly enhance the performance of the DSSCs. [ABSTRACT FROM AUTHOR]