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Arranging dense donors around a single acceptor for the assembly of efficient light-harvesting antennas is a long-standing challenge due to the intractable aggregation-caused quenching of dense donors. Herein, we designed a cationic aggregation-induced emission (AIE) amphiphile to self-assemble with natural DNA duplexes. As an efficient donor, the as-prepared cationic AIE amphiphile could be densely attached to the phosphate groups of natural DNA duplexes by using the smaller cationic trimethylammonium. The long alkyl chain between the cationic trimethylammonium and the AIE fluorophore allowed for avoiding the insufficient binding caused by the steric hindrance of the AIE fluorophore, resulting in a remarkably high donor/acceptor ratio comparable to that of the widely developed custom DNA assemblies. The proposed self-assembly strategy provided novel flexible avenues for the assembling of finely controlled and efficient light-harvesting systems into natural DNA with little synthetic modifications and low cost. [ABSTRACT FROM AUTHOR]

A physics-informed neural network (PINN) that combines deep learning with physics is studied to solve the nonlinear Schrödinger equation for learning nonlinear dynamics in fiber optics. A systematic investigation and comprehensive verification on PINN for multiple physical effects in optical fibers is carried out, including dispersion, self-phase modulation, and higher-order nonlinear effects. Moreover, both the special case (soliton propagation) and general case (multipulse propagation) are investigated and realized with PINN. In existing studies, PINN is mainly effective for a single scenario. To overcome this problem, the physical parameters (i.e., pulse peak power and amplitudes of subpulses) are hereby embedded as additional input parameter controllers, which allow PINN to learn the physical constraints of different scenarios and perform good generalizability. Furthermore, PINN exhibits better performance than the data-driven neural network using much less data, and its computational complexity (in terms of number of multiplications) is much lower than that of the split-step Fourier method. The results show that PINN is not only an effective partial differential equation solver, but also a prospective technique to advance the scientific computing and automatic modeling in fiber optics. [ABSTRACT FROM AUTHOR]

Power systems around the world are rapidly transitioning to much higher shares of inverter‐based resources (IBRs) with few synchronous generators remaining online. IBRs and synchronous generators have fundamentally different dynamic performance characteristics resulting in a difference in the overall power system dynamic performance. IBRs are generally more flexible and controllable than synchronous generators; however, at the same time they exhibit significantly more complex control systems. Furthermore, new and emerging capabilities are being developed progressively and in particular the so‐called grid‐forming inverters (GFM). GFM offer several new capabilities not previously possible with conventional grid‐following inverters (GFL). However, they are not well understood currently when applied in a mega scale and moving forward when they will likely take over the role synchronous generators have been performing for several decades as the workhorse of system security support. Key questions currently in the technical community include the extent to which GFM shall be similar or different to each of the synchronous machines and conventional GFL, and how various control strategies can assist in maximising the grid support capabilities sought and minimise or ideally eliminate any adverse impacts. The objective of this special issue is to provide insights into some of these unknowns. [ABSTRACT FROM AUTHOR]

Solubilization locations play a critical role in developing advanced surfactants and improving solubilization power in micelle‐based applications. However, the current polarity‐based techniques for measuring solubilization locations could come to conflicting conclusions. The key challenge is the unpredictable polarities in the micellar microenvironment. Now, an approach that is independent of micellar polarities is used to measure solubilization locations by covalently linking tetraphenylethylene (TPE) to the alkyl chain end of cationic surfactants. The solubilization locations of solubilized acceptors in the TPE‐cored spherical micelles were accurately measured by calculating the Förster resonance energy transfer distance between anchored TPE donors and solubilized acceptors. Solubilization locations of solubilized substances in the micellar interior and at the micellar surface depend on their size and hydrophobicity, respectively. [ABSTRACT FROM AUTHOR]

Polypeptide-based amphiphilic brush copolymers PLL-g-(PBLG-b-PEG) and PLL-g-(PZLL-b-PEG) with a poly(L-lysine) (PLL) backbone and amphiphilic oligo(γ-benzyl-L-glutamate)-b-poly(ethylene glycol) (PBLG-b-PEG) or oligo(e-benzyloxycarbonyl-L-lysine)-b-poly (ethylene glycol) (PZLL-b-PEG) side chains were synthesised, characterised, and evaluated as unimolecular nanocontainers to encapsulate hydrophobic guest molecules. The structure of these brush polymers was modulated by tuning the length of the PLL, PBLG/PZLL, and PEG segments. The final products were characterised with ¹H nuclear magnetic resonance and gel permeation chromatography. The morphology and aggregation behaviours of brush copolymers were examined by using a transmission electron microscope and dynamic light scattering. It was revealed that these water-soluble brush copolymers resembled unimolecular micelles in an aqueous solution. An encapsulation study was performed using pyrene and oil red O as the model compounds, and the results showed that hydrophobic molecules could be solubilised in these unimolecular micelles with high loading capacities. The synthesised polypeptide-based amphiphilic brush copolymers could serve as promising unimolecular nanocarriers for the delivery of hydrophobic drugs. [ABSTRACT FROM AUTHOR]

A The DC distribution technology brings challenges and opportunities to the penetration of large-scale distributed renewable energy sources. In a medium-voltage DC (MVDC) distribution network, operation mode switch occurs owing to some large disturbances. To manage these disturbances and achieve seamless switch of the operation mode, a hierarchical control strategy with two layers, namely local and global layers, is proposed in this work. The novel local layer controller called P--U--I controller is designed to enhance the voltage stability, improve system controllability and suppress overcurrent under large disturbances. This controller only needs local information and does not rely on fast communication. Furthermore, as the scale of the DC distribution network expands continuously, the number of system operation mode increases in geometric progression. Therefore, a global layer controller based on breadth-first search algorithm is proposed. This controller can automatically identify the system topology and adjust the control mode of converters to optimise the system operating characteristics. Thus, this hierarchical control strategy can accurately control the system power in steady state, suppress overcurrent under large disturbances and suit large-scale DC distribution networks. Finally, a three-terminal MVDC distribution network simulation model established on power systems computer-aided design and RT-LAB validates the proposed strategy. [ABSTRACT FROM AUTHOR]

Focusing on high-efficiency sequential feature learning for short-term voltage stability (SVS) assessment, this study develops a light-duty time series (TS) learning machine based on symbolic TS datasets, namely wordbooks. Numerous cumbersome TS acquired from post-contingency synchrophasor measurements are first tactfully transformed into short symbolic words, constituting a compact and light wordbook. By centralising the intra-class words in the wordbook, a series of keywords are quickly extracted without iteration to perform wordbook learning. Owing to the portability of the wordbook, online SVS assessment models can be derived extremely fast from it. With such merits, wordbook learning is designed to be periodically conducted by studying new cases from up-to-minute measurements, resulting in enhanced adaptability to inconstant unknown situations. Fractional affixes that frequently occur in the wordbook are further extracted for pattern discovery of voltage instability. Test results on the realistic Hong Kong power grid illustrate the effectiveness and advantages of the proposed learning machine. [ABSTRACT FROM AUTHOR]

Short-term voltage stability (STVS) issue poses a significant threat to receiving-end power systems with high penetration of induction motors. To improve STVS of a receiving-end system in a limited geographic area, this study proposes a local-area STVS control system (LVCS). LVCS consists of phasor measurement units (PMUs), a local-area centralised controller (LCC), generator-level actuators (GLAs) and high-speed communication networks. The PMUs or GLAs are pre-deployed according to the observability or controllability of STVS. LCC receives and processes voltage measurements from PMUs to generate supplementary excitation control signals (SECSs). The SECSs are next forwarded to and executed by GLAs. Simulation studies on a practical receiving-end system in China Southern Power Grid demonstrate that: once the target system suffers a serious fault, LVCS can 'feel' the voltage sag at critical buses and enforce the excitation control of generators to inject more dynamic var into the receiving-end system. As a result, the increasing var demand is met locally and STVS can be improved considerably. Time delay caused by synchrophasor transmission has also been considered in the design of LVCS to make it feasible in practice. Thus, the proposed LVCS offers a new and effective solution to the STVS problem. [ABSTRACT FROM AUTHOR]

ABSTRACT The Qilianshan [ shan means 'mountain(s)' in Chinese] are important for understanding the Quaternary glaciations which occurred along the north-eastern margins of the Tibetan Plateau (TP). Two sets of moraines identified in the Gangshika Valley on the southern slopes of the Qilianshan, and in the Jindonggou Valley on the northern slopes of the Lenglongling Ridge in the eastern Qilianshan, were dated using optically stimulated luminescence (OSL) dating. The De values of the sediments were determined using single aliquot regeneration (SAR) and 'global standardized growth curve' (gSGC) procedures. The gSGC method was first applied to glacial sediment and proved to be adaptable. Based on De distribution analysis, and a comparison between the ages of coarse-grained (90-125 μm) quartz, we concluded that the minimum age model (MAM) OSL age obtained may be closer to the burial age of the sediments. The first set of moraines in the Gangshika Valley was formed at 18.1 ± 1.8 ka. The second set of moraines in both the Gangshika and the Jindonggou valleys was mainly formed at ∼12.5-10.7 ka, consistent with the Younger Drays chronozone, most probably covering the moraines produced at 14.3 ± 1.4 ka. These results indicate that the glaciers along the Lenglongling Ridge were sensitive to abrupt decreases in temperature. [ABSTRACT FROM AUTHOR]

The direct visualization of micelle transitions is a long-standing challenge owing to the intractable aggregationcaused quenching of light emission in the micelle solution. Herein, we report the synthesis of a surfactant with a tetraphenylethene (TPE) core and aggregation-induced emission (AIE) characteristics. The transition processes of surfactant micelles and the microemulsion droplets (MEDs) formed by the surfactant with a TPE core were clearly visualized by a high-contrast fluorescence imaging method. The fluorescence intensity of the MEDs decreased as the size of MEDs increased as a result of weakening of the restriction of intramolecular rotation (RIR). The results of this study deepen our understanding of micelle-transition processes and provide solid evidence in favor of the hypothesis that the AIE phenomenon has its origin in the RIR of fluorophores in the aggregate state. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editor discusses various reports within the issue on topics including dynamic synchrophasor estimation, voltage controllability and renewable energy.

The effect of compounding procedure on morphology and crystallization behavior of isotactic polypropylene/high-density polyethylene/carbon black (iPP/HDPE/CB) composite was investigated. iPP/HDPE/CB composites were prepared by four compounding procedures (A: iPP + HDPE + CB; B: iPP/HDPE + CB; C: HDPE/CB + iPP; D: iPP/CB + HDPE). Scanning electron microscopy observation showed that CB particles are mainly distributed in HDPE in all composites, and the phase morphology of composites was obviously affected by a compounding procedure. The size of the HDPE/CB domains in the composites prepared by procedures A and D decreased with the increase in CB content, whereas that of HDPE/CB in the composites prepared by procedures B and C rarely changed with the increase in CB content. The crystallization behaviors of the composites were significantly affected by their phase morphology, which resulted from the variation of compounding procedure. The isothermal crystallization rate of iPP in the composites prepared by procedures A and D was obviously increased, which may originate from the small HDPE/CB droplets dispersed in the iPP phase. The non-isothermal crystallization curves of composites prepared by procedure D represented two peaks because the iPP component in these composites had the fastest crystallization rate, whereas the curves of composites prepared by other compounding sequences only exhibited one peak. Moreover, the crystallinity of HDPE almost increased by one time with the incorporation of only 1 phr CB because the CB particles selectively located in the HDPE phase, and the crystallinity of HDPE decreased with the further increase of CB content because of the strong restriction of CB on the HDPE chains. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this work, gradient materials with low electrical resistivity were prepared by compounding isotactic polypropylene (iPP)/high density polyethylene (HDPE) blends with carbon black (CB) through extruding and injection molding. Contact angle measurements and morphology measurements showed that the CB particles were selectively located in HDPE phase and the final composites had a gradient structure that the HDPE/CB phase exhibited different morphologies in the skin layer and core layer of the composites under different processing procedures. The main factors influencing the formation of the functional gradient materials (FGM), including screw speed during extruding, iPP types and CB contents were discussed. They affect the phase morphology by shear stress, the restoration of HDPE phase, and the viscosity ratio of polymer blends, respectively. In conclusion, iPP/HDPE/CB FGM could be formed easily in the composites blending with the iPP type with narrow molecular weight distribution (MWD) and higher CB content extruded at higher screw speed. The electrical properties of iPP/HDPE/CB composites were studied and the results showed that screw speed in extrusion significantly influenced the percolation curve and electrical property of the final composites. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Citation Liu L-P, Huang W, Lu Y-C, Liao A-H. Enhanced maternal anti-fetal immunity contributes to the severity of hypertensive disorder complicating pregnancy. Am J Reprod Immunol 2010 Problem The aim of this study was to evaluate how fetal monocyte activation and maternal anti-fetal antigen-specific antibody-secreting cells (ASC) affect the severity of hypertensive disorder complicating pregnancy (HDCP). Method of study Forty-six healthy third-trimester pregnant women and 20 patients with gestational hypertension, 20 with mild pre-ecalmpsia and another 20 with severe pre-eclampsia were included in the study. Interleukin-6 (IL-6) release from cord blood monocytes was examined by intracellular cytokine staining and flow cytometric analysis. Moreover, the maternal anti-fetal antigen-specific ASC were detected by enzyme-linked immunospot assay. Results A significantly increased percentage of IL-6-positive monocytes were detected in the cord blood of study groups compared with the controls ( P < 0.01). The percentage of IL-6-positive monocytes was increased as the disease progressed ( P < 0.05). There were more anti-fetal antigen-specific ASC in the study groups than those in the controls ( P < 0.001). Furthermore, the anti-fetal antigen-specific ASC showed difference in gestational hypertensive and severe pre-eclamptic groups ( P < 0.05). Conclusion We conclude that the fetal monocyte activation and the increase in maternal anti-fetal antigen-specific ASC were related to the incidence and severity of HDCP. These results provide both indirect and direct evidence for the occurrence of exaggerated maternal humoral immunity against the fetal antigens in HDCP. [ABSTRACT FROM AUTHOR]

A theoretical study of optical properties of subwavelength-diameter silica fibers is presented, with an emphasis on the interplay between dispersion and nonlinearity. The normalized dispersion and effective nonlinearity are used to analyze the diameter-dependent relative strength at all wavelengths. The dispersion and nonlinearity length are calculated for guiding waveguide dimension design for possible applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2086–2090, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23552 [ABSTRACT FROM AUTHOR]

A novel interrogation of fiber Bragg grating (FBG) in a strain sensor, which is based on Er-doped fiber laser's transient regime, is reported. The applied strain on FBG changes the laser cavity loss, which in turn modifies the laser's transient regime. The strain value can be obtained by measuring the build-up time of the laser. This method translates wavelength shift information into time domain that can be accurately measured with low-cost electronic devices. In the experiment, the strain sensitivity can be adjusted by simply controlling the pumping level of the laser, a sensitivity of 1.66 μℇ/μs is achieved under fitful pumping level. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48:1904–1904, 2006; Published online in Wiley InterScience (www.interscience.wiley.com(. DOI 10.1002/mop.21773 [ABSTRACT FROM AUTHOR]

Changes in expression of Na, K-ATPase (NKA) and morphometry of mitochondrion-rich (MR) cells in gills of tilapia were investigated on a 96–hr time course following transfer from seawater (SW) to fresh water (FW). A transient decline in plasma osmolality and Na+, Cl- concentrations occurred from 3 hrs onward. Gills responded to FW transfer by decreasing NKA activity as early as 3 hrs from transfer. This response was followed by a significant decrease in the NKA isoform α1–mRNA abundance, which was detected by real-time PCR at 6 hrs post transfer. Next, a decrease of α1–protein amounts were observed from 6 hrs until 24 hrs post transfer. Additionally, during the time course of FW transfer, modifications in number and size of subtypes of gill MR cells were observed although no significant difference was found in densities of all subtypes of MR cells. These modifications were found as early as 3 hrs, evident at 6 hrs (exhibition of 3 subtypes of MR cells), and mostly completed by 24 hrs post transfer. Such rapid responses (in 3 hrs) as concurrent changes in branchial NKA expression and modifications of MR cell subtypes are thought to improve the osmoregulatory capacity of tilapia in acclimation from hypertonic SW to hypotonic FW. J. Exp. Zool. 301A:85–96, 2004. © 2004 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

A novel device using a phase-shifted long-period grating cascaded with one normal long-period grating is designed to flatten the gain spectrum of EDFAs with all of three gain peaks. The experimental results show that the 3-dB bandwidth of flattened EDFA is 46 nm, and gain peak-to-peak is approximately 0.9 dB. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 153–157, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10853 [ABSTRACT FROM AUTHOR]

The characteristics of an apodized long-period grating are studied experimentally and theoretically. It has no side-lobes and almost zero insertion loss in the pass band. Changing the dc and maximum ac index along the z direction of LPG can conveniently control wavelength and the value of peak loss. Suitable spectral profile of gain-flattening filter with low insertion loss is obtained by writing two or three consecutive apodized sub-gratings in one fiber with the different UV power level in the second exposure. The experiment results are in good agreement with the simulation results. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 283–286, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10583 [ABSTRACT FROM AUTHOR]

Tunable fibre Bragg grating (FBG)-based reconfigureably non-blocking optical cross connect (OXC) using multi-port optical circulators (MOCs) are proposed and presented. In an FBG–MOC-based OXC, system insertion loss, system differential insertion loss together with OXC dimensions have been analysed and compared with FBG–OC-based OXC structure using three-port optical circulators (OCs). Optical crosstalk in a multiwavlength FBG–OC-based OXC is discussed, and two crosstalk mechanisms, intraband and interband are identified. To compare FBG based OXC with other OXC structures, an analytical model of intraband optical crosstalk is presented. Results show that tunable FBGs based OXCs are attractive OXC schemes as crosstalk level is independent of the number of wavelength channel per fibre. For the worst case the coherent crosstalk is the dominant crosstalk, which is about 20–30 dB higher than the incoherent crosstalk, depending on the sitching state of the cascaded 2×2 OXCs. However, in practical applications incoherent crosstalk is usually dominant, since it is highly unlikely that all the same wavelength-channels will originate from the same optical source. And the crosstalk of FBGs is the dominant crosstalk. Copyright © 2001 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The performance of WDM networks using shortest path routing is studied under wavelength continuous (WC) and non-continuous (NWC) constraints and dynamic traffic loading. Approximate analytical models are presented for the performance studies of such systems. Results of numerical calculations based on these models and simulations are given for different network topologies for the purposes of comparison. These analytical and simulation results are used to study the performance of these WDM networks under dynamic traffic loading. Copyright © 2001 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

We demonstrate a highly birefringent photonic-crystal fiber by utilizing combined asymmetric core design and intentional stress-induced anisotropy. Based on spectral measurements of the polarization-mode interference, we measure that the fiber has a beat length of about 0.33 mm at 1545 nm. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 42: 498–500, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20348 [ABSTRACT FROM AUTHOR]

A simple switchable dual-wavelength Er-doped fiber-ring laser using a fiber Bragg grating (FBG) written in high-birefringence (HiBi) fibers is proposed. Due to the two-peak reflections with orthogonal polarizations of the FBG, the polarization hole-burning effect in the cavity is greatly enhanced. Experimental results show that a stable dual-wavelength laser with very close wavelength separation (0.39 nm) can be generated at room temperature. Furthermore, the FBG in the HiBi fiber offers flexibility for selection of the laser wavelength. By adjusting a polarization controller, the laser can be switched between the stable single- or dual-wavelength lasing operations. [ABSTRACT FROM AUTHOR]

A cantilever beam and fiber Bragg grating are used to measure acceleration. The output signal is insensitive to temperature variations from -20°C to 40°C, and the output signal fluctuates less than 5% without any temperature compensation schemes. For the experimental system, a linear output range of 8 g can be detected. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 151–153, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10852 [ABSTRACT FROM AUTHOR]

In this paper we propose a new method for the measurement of the relative group delay of WDM components, based on photonic microwave technique using a low frequency (below 1.3 GHz) scalar network analyzer. Experimental results demonstrate that this technique has the advantages of low cost, simplicity, and high accuracy (less than ±1 ps). © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 346–348, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10602 [ABSTRACT FROM AUTHOR]

A sensor array employing the distributed Bragg reflector (DBR) fibre laser is presented. This array could be utilised as a multi-channel multi-functional detector for bending radius, transverse load and axial strain by simultaneously monitoring the lasing wavelength and the output beat note frequency. The measurement theory of the DBR fibre laser is explained, and it is then experimentally verified with a three-probe array. The system's detection sensitivities for curvature, transverse load and axial strain are found to be 600 MHz/cm-2, 1.3 MHz/g and 1.263 pm/με, respectively. [ABSTRACT FROM AUTHOR]

We present and demonstrate experimentally a new method for measuring the polarization mode dispersion (PMD) of chirped fiber Bragg gratings. The technique can also be used to measure chromatic dispersion (CD) more accurately by eliminating the influence of PMD. [ABSTRACT FROM AUTHOR]