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Mobile edge computing (MEC) is a key enabler of time-critical vehicle-to-everything (V2X) applications. Under MEC, a vehicle has the option to offload computationally intensive tasks to a nearby edge server or to a remote cloud server. Determining where to execute a task necessitates accurate estimation of the end-to-end (E2E) offloading delay. In this paper, we first conduct extensive measurements of the round-trip time (RTT) between a vehicular user and edge/cloud servers. Using these measurements, we present a latency-estimation framework for optimal task offloading. The propagation delay, measured by the RTT, is divided into two components: one that follows a trackable trend (baseline) and the other (residual) that is quasi-random. For the baseline component, we first cluster measured RTTs into several groups, depending on signal strength indicators. For each group, we develop a Long Short-Term Memory (LSTM) regression model. A statistical approach is provided for predicting the residual component, which combines the Epanechnikov Kernel and moving average functions. Predicted propagation delays are incorporated into virtual simulations to estimate the transmission, queuing, and processing delays, hence accounting for the E2E delay. Based on the estimated E2E delay, we design a task offloading scheme that minimizes the offloading latency while maintaining a low packet loss rate. Simulation results show that the proposed offloading strategy can reduce the E2E delay by approximately 60% compared to a random offloading scheme while keeping the packet loss rate below 3%.

Background: Caregiver burden consists of disease specific and perceived stressors, respectively referred to as objective and subjective indicators of burden, and is associated with negative outcomes. Previous research has found that care partners to persons living with cognitive impairment and elevated levels of amyloid-β, as measured by a positron emission tomography (PET) scan, may experience caregiver burden. Aims: To elucidate the relationship between amyloid scan results and subjective and objective indicators of burden. Methods: A parallel mixed-methods design using survey data from 1338 care partners to persons with mild cognitive impairment (MCI) and dementia who received an amyloid scan from the CARE-IDEAS study; and semi-structured interviews with a subsample of 62 care partners. Logistic regression models were used to investigate objective factors associated with caregiver burden. A thematic analysis of semi-structured interviews was used to investigate subjective indicators by exploring care partners' perceptions of their role following an amyloid scan. Results: Elevated amyloid was not associated with burden. However, the scan result influenced participants perceptions of their caregiving role and coping strategies. Care partners to persons with elevated amyloid expected increasing responsibility, whereas partners to persons without elevated amyloid and mild cognitive impairment did not anticipate changes to their role. Care partners to persons with elevated amyloid reported using knowledge gained from the scan to develop coping strategies. All care partners described needing practical and emotional support. Conclusions: Amyloid scans can influence subjective indicators of burden and present the opportunity to identify and address care partners' support needs.

This article proposes an intervalestimation method for discrete-time Lipschitz nonlinear systems via observer design and ellipsoidal analysis. A robust observer with novel structure is presented, which provides more degrees of design freedom and can be applied to enhance the interval estimation performance. To handle the nonlinear term in Lipschitz systems, we use the reformulated Lipschitz property to transform the nonlinear error dynamics into a linear parameter-varying form. After the transformation, the robustness performance of the proposed observer is characterized with the aid of peak-to-peak index. Furthermore, the comprehensive interval estimation results are obtained by using the peak-to-peak performance and the ellipsoidal analysis. Numerical simulation results are conducted to demonstrate the viability and validity of the presented method.

Reinforcing electronic and ionic conductivity is very important to realize the high-rate Li2ZnTi3O8(LZTO) anode for Lithium-ion batteries (LIBs). Here, we reported a synthetic strategy toward in situ growth of homodispersed Li2ZnTi3O8on ultralight 3D carbon aerogels (CAs) via facile heat treatment and activation process taking LiOH as activating agent. Such an optimized composite obtains a specific surface area of 154.427 m2 g−1and a high pore volume. The strong interaction between the LZTO and N-doped CAs, a highly electrical conductivity and multidimensional ion transport channels of the hybrid result in a high capacity, outstanding high-rate performance and long cycle life. As a result, the NPC-LZTO electrode (NPC-LZTO-B) delivers a commendable reversible capacity at high-rate (e.g. 162.4 mAh g−1at 5 A g−1(22 C) and 127.3 mAh g−1at 10 A g−1) and durable long-term performance (capacity retention of 73% after 4500 cycles at 5 A g−1). Moreover, the kinetic analysis confirms that the feature of pseudocapacitance boosts lithium-ion storage performance at high rate. Porous carbon aerogels frame constructed LZTO nanocomposite electrodes provide a facile way to design high durable LIBs anode.

In this article, 3-D vector-based model predictive current control (MPCC) for the open-end winding permanent magnet synchronous generator (OEW-PMSG) system driven by a dual inverter with a common dc bus is proposed to suppress the zero-sequence current. First, the 3-D voltage vector distribution of this system is analyzed and their zero-sequence voltages are investigated. Then, in order to reduce the computation burden of prediction control caused by vector enumeration, an improved current prediction control is developed, in which candidate voltage vectors for the dual inverter are determined according to the position of the zero-sequence reference voltage vector and the sector location of the $\alpha \beta $ -axis reference voltage vector. Moreover, to further improve the steady-state control performance of the whole generation system, a separate vector-selection method for the dual inverter is proposed. In this method, the first inverter applies one voltage vector in a control period and the voltage vector of the second inverter is synthesized by two vectors and selected in 3-D space. Finally, experiments are carried out to validate proposed methods, and the comparison experiments indicate that the proposed method has better control performance compared to conventional methods.

To eliminate the weighting factor, suppress the zero-sequence current, and reduce the computation burden in the conventional model predictive torque control (MPTC) of the open-winding permanent magnet synchronous motor (OW-PMSM) system with a common dc bus, a vector partition selection-based full-torque control is proposed. The instantaneous power theory is introduced to make the control of the torque, the flux linkage, and the zero-sequence current, which is equivalent to the control of the real torque, the virtual torque, and the zero torque. Then, the full-torque-based cost function is designed to avoid the weighting factor in the proposed method. In addition, to reduce the calculation burden caused by the large number of candidate voltage vectors, a vector partition selection strategy in 3-D space is presented. Then, the candidate vectors are reduced from 27 to 6 or 7 in every control period. Finally, the experimental results verify the effectiveness of the proposed method.

This study attempts to evaluate the rationality of the spatial layout of shopping malls and identify the urban area with poor shopping mall accessibility, as well as to provide a reference and assist decision-making for planning. Using the case of Nanjing, China, this study developed a method to evaluate the accessibility of shopping malls by three transport modes (car traffic, public transit, and bicycle). Specially, we divide the urban space into a regular hexagonal grid and harvest the total travel time from each of 7204 hexagon centroids to each of 129 shopping malls using the Baidu Internet map. The door-to-door travel time approach is used to evaluate all travel stages (walking, waiting, transfer, and transportation) based on travel time calculations. We further divide the shopping malls into two levels (super-regional and regional) based on the Dianping App’s information and develop the indicator of accessibility to shopping malls: the number of shopping malls within tolerance time thresholds and apply the closest facility and cumulative opportunities methods to measure accessibility scores. The results show that the accessibility estimations vary greatly with transport modes. The accessibility of shopping malls presents a concentric ring trend centered on the city center under the car traffic and bicycle modes. And public transit accessibility tends to axially extend due to the topology of bus routes and metro lines. In particular, we observe that the accessibility of shopping malls in Nanjing has an uneven spatial distribution pattern, with high accessibility values in the central urban areas and lots of underserved areas in urban fringe regions. Based on the accessibility measurements, we finally map the poor accessibility area and propose corresponding implications for urban planning.

Topological insulators are bulk semiconductors that manifest in-gap surface states with massless Dirac-like dispersion due to the topological bulk-boundary correspondence principle1–3. These surface states can be manipulated by the interface environment to display various emergent phenomena4–11. Here, we use angle-resolved photoemission spectroscopy and scanning tunnelling microscopy to investigate the interplay of crystallographic inhomogeneity with the topologically ordered band structure in a model topological insulator. We develop quantitative analysis methods to obtain spectroscopic information, in spite of a limited dwell time on each measured point. We find that the band energies vary on the scale of 50 meV across the sample surface, and this enables single sample measurements that are analogous to a multi-sample doping series. By focusing separately on the bulk and surface electrons we reveal a hybridization-like interplay between fluctuations in the surface and bulk state energetics.

This paper proposes a state augmentation approach to achieve interval fault estimation for descriptor systems with unknown but bounded disturbances and measurement noises. An augmented descriptor system, which is equivalent to the original system, is constructed while the fault vector is considered as an auxiliary state. Based on this augmented system, a robust fault estimation observer is designed to estimate the actuator faults. Under this augmented descriptor form, the conservatism of observer gain matrix can be significantly reduced by introducing more design degrees of freedom. Moreover, interval estimation of actuator faults can be achieved by using zonotopic techniques. Finally, a DC motor model simulation is used to illustrate the effectiveness of the proposed approach.

This paper is concerned with the interval estimation for discrete-time linear switched systems affected by unknown disturbances and noises. A novel interval estimation approach is proposed by integrating robust observer design with zonotopic techniques. By introducing L∞ technique into observer design, the proposed approach is effective in attenuating the influence of unknown disturbances and noises, and improving the accuracy of interval estimation. Based on the designed observer, the interval estimation can be obtained by using zonotopic analysis. Numerical simulation results are conducted to demonstrate the feasibility and effectiveness of the proposed approach.

Rocaglates are a family of natural products isolated from the genus Aglaiawhich possess a highly substituted cyclopenta[b]benzofuran skeleton and inhibit cap-dependent protein synthesis. Rocaglates are attractive compounds due to their potential for inhibiting tumor cell maintenance in vivoby specifically targeting eukaryotic initiation factor 4A (eIF4A) and interfering with recruitment of ribosomes to mRNA. In this paper, we describe an intercepted retro-Nazarov reaction utilizing intramolecular tosyl migration to generate a reactive oxyallyl cation on the rocaglate skeleton. Trapping of the oxyallyl cation with a diverse range of nucleophiles has been used to generate over 50 novel amidino-rocaglate (ADR) and amino-rocaglate derivatives. Subsequently, these derivatives were evaluated for their ability to inhibit cap-dependent protein synthesis where they were found to outperform previous lead compounds including the rocaglate hydroxamate CR-1-31-B.

As a unique rocaglate (flavagline) natural product, aglaroxin C displays intriguing biological activity by inhibiting hepatitis C viral entry. To further elucidate structure–activity relationships and diversify the pyrimidinone scaffold, we report a concise synthesis of aglaroxin C utilizing a highly regioselective pyrimidinone condensation. We have prepared more than 40 aglaroxin C analogues utilizing various amidine condensation partners. Through biological evaluation of analogues, we have discovered two lead compounds, CMLD012043 and CMLD012044, which show preferential bias for the inhibition of hepatitis C viral entry vs translation inhibition. Overall, the study demonstrates the power of chemical synthesis to produce natural product variants with both target inhibition bias and improved therapeutic indexes.

Abstract: An account of the total synthesis of (±)-, (+)-heliespirone A and (±)-, (−)-heliespirone C is presented. In the first-generation total synthesis, we found rac-24a could be easily transformed to rac-heliespirones A & C in a biomimic way. Taking the disappointing diastereoselectivity of prenylation from 3 to 4, the nonselective dihydroxylation from 4 to 5 and the lenthy route in strategy A into account, we designed a different synthetic plan targeting a highly enantioselective, concise and protective-group free synthesis of heliespirones A & C. The palladium-catalyzed Michael addition and Sharpless AD played the key roles in the formation of optical lactone V, which could be easily transformed to compound I through two additional steps and the succedent operations were the same as those in the first-generation total synthesis. Our synthetic efforts indicated the bio-generation of heliespirones A & C from 24a should be a real process in nature.

Spinel lithium titanate (Li4Ti5O12) has been widely used as anode electrode for long-life lithium ion batteries (LIBs), however, it suffers from inherent poor electronic and ionic conductivity which limits its further development. Here, a composite macroporous conductive network is constructed by carbon nanotubes (CNTs) and few-layer titanium carbide (Ti3C2s) and used for the modification of Li4Ti5O12-TiO2. Owing to the excellent mechanical properties of CNTs and Ti3C2s, the prepared Ti3C2s-CNTs-Li4Ti5O12/TiO2(T-C-L) material can be directly used as binder-free electrode. Specifically, CNTs serve as a connection skeleton to stabilize the electrode structure and provide a conductive network to improve electron transport capabilities; the addition of Ti3C2s is beneficial to the formation of macropores which can further improve ion diffusion; the existence of TiO2phase can improve its capacity as well as rate capability. Reasonable design and the synergistic effect of each component endow T-C-L outstanding Li-storage performance and Mg-storage performance. When combined with lithium belt to form a pouch battery, the T-C-L also exhibits satisfactory bending performance, which further expand its practicality. These results show great promise of the prepared T-C-L for LIBs and magnesium ion batteries (MIBs) and provide a modification method for other electrode materials that suffer from poor ion/electron diffusion capabilities.

Rocaglates are a diverse family of biologically active molecules that have gained tremendous interest in recent years due to their promising activities in pre-clinical cancer studies. As a result, this family of compounds has been significantly expanded through the development of efficient synthetic schemes. However, it is unknown whether all of the members of the rocaglate family act through similar mechanisms of action. Here, we present a comprehensive study comparing the biological activities of >200 rocaglates to better understand how the presence of different chemical entities influences their biological activities. Through this, we find that most rocaglates preferentially repress the translation of mRNAs containing purine-rich 5′ leaders, but certain rocaglates lack this bias in translation repression. We also uncover an aspect of rocaglate mechanism of action in which the pool of translationally active eIF4F is diminished due to the sequestration of the complex onto RNA.