Search

Microneedles, especially hollow microneedles (HMNs), play an important role in drug delivery, but most of the current HMNs are manufactured based on silicon microfabrication (lithography, etching, etc.), which are slightly conservative due to the lack of low‐cost, batch‐scale and customized preparation approach, especially for the HMNs with flexible substrate. For the first time, we propose the use of a high‐precision 3D printed master mold followed by a dual‐molding process for the preparation of HMNs with different shapes, heights, and inner and outer diameters to satisfy different drug delivery needs. The 3D printed master mold and negative mold can be reused, thereby significantly reducing the cost. HMNs are based on biocompatible materials, such as heat‐curing polymers or light‐curing resins. The thickness and rigidity/flexibility characteristics of the substrate can be customized for different applications. The drug delivery efficiency of the fabricated HMNs was verified by the in situ treatment of psoriasis on the backs of mice, which required only a 0.1‐fold oral dose to achieve similar efficacy, and the associated side effects and drug toxicity were reduced. Thus, this dual‐molding process can reinvigorate HMNs development. [ABSTRACT FROM AUTHOR]

As the grid‐connected interface device of wind and photovoltaic power generation, the voltage source converter (VSC) must pass the low voltage ride‐through (LVRT) test. However, existing literature demonstrates that under weak grid conditions, there is a possibility of severe fluctuations in the terminal voltage of VSC during transiting from the pre‐sag normal operation mode to the LVRT mode. Unfortunately, it will make VSC frequently enter and exit LVRT mode. In order to address the tricky problem of transient instability of VSC riding‐through severe grid voltage sag under the weak grid, in this paper, the full‐order large‐signal model of VSC is established first. Then, based on the established model, the analysis indicates VSC will face the risk of losing stability under the weak grid during LVRT due to current transients. By studying the impacts of low short circuit ratio (SCR) on the basin of attraction of the post‐sag equilibrium point, the intrinsic mechanism of VSC losing stability under weak grid conditions is revealed. Moreover, considering that the transient stability is related to the current control, the stability‐enhanced LVRT control ensuring both small‐signal stability and transient stability of VSC during LVRT is proposed. Finally, the correctness of the above theoretical analysis is verified by real‐time simulation [ABSTRACT FROM AUTHOR]

Groundwater exploitations in semi‐arid regions result in significant declines of groundwater levels and streamflow and even trigger seasonal streamflow drying up, which may bring adverse impacts on riparian ecosystems. It is critical to explore future streamflow changes caused by variable climate scenarios and groundwater exploitation intensities; however, a comprehensive assessment of the streamflow drying up frequency remains lacking. Furthermore, the thresholds of controlling factors beyond which streamflow drying up occurs have rarely been explored. Here we develop an integrated surface water‐groundwater model for the Taoer River Basin (TRB), a typical semi‐arid watershed in northeast China. We apply the model to multiple future scenarios to reveal the frequency of potential streamflow drying up and explore the thresholds of controlling factors of streamflow drying up based on a decision tree method. We find that the groundwater level in the lower region of the TRB (LTRB) is hard to recover to the riverbed elevation and the streamflow drying up frequency is still high unless the groundwater exploitation is reduced by 50%. However, this leads to a competition between the ecological and economic objectives. Our results also show that the streamflow drying up frequency in the LTRB is very sensitive to the upstream water inflow that can be regulated through the reservoir operation or inter‐basin water diversion, indicating the importance of a basin scale strategic management. The findings of this paper can help policy makers sustainably exploit water resources in semi‐arid regions. [ABSTRACT FROM AUTHOR]

BACKGROUND: A reduced level of fatty acid oxidation (FAO) by skeletal muscle leads to the accumulation of intermuscular fat (IMF), which is linked to impaired exercise capacity. Previously, we have reported that Lactiplantibacillus plantarum fermented barley extract (LFBE) has effective anti‐obesity properties. In this study, the effects of LFBE on muscle were investigated. RESULTS: LFBE improved running endurance and muscle strength, which was caused by the elevation of FAO in muscle. In addition, LFBE renovated muscle regeneration through the upregulation of paired box 7 and myogenic differentiation 1 expression avoiding the injury of skeletal muscle fibers. Furthermore, total polyphenol isolated from LFBE (FTP) reinforced mobility and showed a significant protective effect on maintaining muscle fiber morphogenesis in Caenorhabditis elegans. Transmission electron microscope observation suggested FTP induced mitophagy in C. elegans body wall muscle, which was strongly connected with enhanced FAO in mitochondria. CONCLUSIONS: Our findings highlighted the beneficial bioactivities of FTP and its potential application for stimulating mitophagy and muscle function in obese individuals. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The increased complexity and scaling down of electronic devices lead to great challenges in extracting an interesting nanoscale area of the device for transmission electron microscopy (TEM) characterization. The traditional TEM sample preparation methods, such as electrolytic polishing, can not precisely process a specific area of the device. Focused ion beam (FIB) technology is an advanced in situ specimen preparation method for TEM. FIB can not only locate specific position and mill a TEM sample with the nanoscale resolution, but also manipulate the sample in a controlled manner in real time. With the development of electronic devices, variations, and optimizations of the FIB method for advanced devices with new structures have been reported. In this review, the TEM sample preparation methods for fin field‐effect transistor, high electron mobility transistor, enhanced dynamic random‐access memory, and 2D material‐based devices are discussed. Their advantages, disadvantages, and an overview of the applications are summarized. Based on current research, future research directions for enhancing the quality of TEM samples are suggested. [ABSTRACT FROM AUTHOR]

We investigate the thermal and electrochemical properties of xFe2O3‐(100‐x) P2O5 glass (x = 20, 30, 40, and 50 mol%) and 50Fe2O3‐50P2O5 (50FeP) glass‐ceramics as anodes for lithium‐ion batteries (LiBs). The results show that both the glass transition temperature and the energy bandgap monotonically decrease with the increasing Fe2O3 while a critical Fe2O3 content of 30 mol% is found to give glass the highest thermal stability, the largest capacity at 1 Ag‐1, and the lowest charge‐transfer resistance before cycling. Moreover, Fe3(P2O7)2 crystals formed during heat treatment in 50FeP glass effectively enhances the electrochemical properties. The optimum heat treatment condition for 50FeP glass is found at 1033 K for 4 h, that is, 1033 K‐4 h sample enables a reversible capacity of 237 mA h g−1 at the end of 1000 cycles at 1 Ag‐1, which is more than 1.5 times higher than that of the 50FeP glass‐based anode. These findings suggest that the Fe2O3‐P2O5 glass‐ceramics hold significant potential for the effective development of new types of glass anodes for future advanced LiBs. [ABSTRACT FROM AUTHOR]

Chiral indolines represent important structural motifs in a large number of natural products and pharmaceutics. Chiral succinimideunits are also found in a wide range of natural products and pharmaceutical substances. Herein we report an enantioselective dearomative [3+2] annulation of 3‐hydroxymaleimides with azonaphthalenes using a chiral squaramide‐tertiary amine as catalyst. The reactions afforded a large variety of novel succinimide fused indolines in moderate to good yields (up to 99 %) with generally good enantioselectivities (up to 98 % ee). The absolute configuration of one product was assigned by an X‐ray crystal structural analysis and a plausible reaction mechanism was proposed accordingly. Afterwards, under different conditions, one product was treated with triethylsilane and provided two kinds of reductive products in moderate to good yields with good enantioselectivities. [ABSTRACT FROM AUTHOR]

Antiangiogenic tyrosine kinase inhibitors (AA‐TKIs) have become a promising therapeutic strategy for colorectal cancer (CRC). In clinical practice, a significant proportion of cancer patients temporarily discontinue AA‐TKI treatment due to recurrent toxicities, economic burden or acquired resistance. However, AA‐TKI therapy withdrawal‐induced tumour revascularization frequently occurs, hampering the clinical application of AA‐TKIs. Here, this study demonstrates that tumour perivascular cells mediate tumour revascularization after withdrawal of AA‐TKI therapy. Pharmacological inhibition and genetic ablation of perivascular cells largely attenuate the rebound effect of CRC vascularization in the AA‐TKI cessation experimental settings. Mechanistically, tumour perivascular cell‐derived extracellular vehicles (TPC‐EVs) contain Gas6 that instigates the recruitment of endothelial progenitor cells (EPCs) for tumour revascularization via activating the Axl pathway. Gas6 silence and an Axl inhibitor markedly inhibit tumour revascularization by impairing EPC recruitment. Consequently, combination therapy of regorafenib with the Axl inhibitor improves overall survival in mice metastatic CRC model by inhibiting tumour growth. Together, these data shed new mechanistic insights into perivascular cells in off‐AA‐TKI‐induced tumour revascularization and indicate that blocking the Axl signalling may provide an attractive anticancer approach for sustaining long‐lasting angiostatic effects to improve the therapeutic outcomes of antiangiogenic drugs in CRC. [ABSTRACT FROM AUTHOR]

BACKGROUND Barley contains a relatively high concentration of the mixed‐linkage (1 → 3) (1 → 4) β‐glucan, which has been reported to be a functional food with prebiotic potential. In the current study we compared the properties of two neutral barley β‐glucans, obtained from raw barley: raw barley β‐glucan (RBG) and Lactobacillus plantarum dy‐1‐fermented barley (FBG). RESULTS: Molecular characteristics revealed that the molecular weight of barley β‐glucan decreased from 1.13 × 105 D to 6.35 × 104 D after fermentation. Fermentation also improved the water / oil holding capacity, solubility, and swelling capacity of barley β‐glucan. Both RBG and FBG significantly improved the locomotive behavior of nematodes, thereby increasing their energy consumption and reducing fat deposition – the effect was more significant with FBG. These effects could potentially depend on nhr‐49, TGF‐daf‐7 mediated pathways and so on, in which nhr‐49 factor is particularly required. CONCLUSION: These results suggested that fermentation may enhance in vitro physiological activities of barley β‐glucan, thereby altering the effects on the lipid metabolism in vivo. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Chiral α‐mercapto‐β‐amino acid derivatives are highly significant for the development of new synthetic methodology and pharmaceutics. Until now, only a few catalytic asymmetric transformations for the synthesis of optically active α‐mercapto‐β‐amino acid derivatives have been developed. In continuation of our ongoing research on asymmetric hydrosilylation, herein we report a one‐pot asymmetric hydrosilylation‐transacylation of N‐unprotected α‐acylthio‐β‐enamino esters by employing a chiral picolinamide Lewis base as a catalyst. The reactions afforded a wide variety of α‐mercapto‐β‐acylamido esters with good yields (up to 99%) in good diastereoselectivities (>20 : 1 d.r.) and moderate to good enantioselectivities (up to 86% ee). Furthermore, the absolute configuration of one product was determined and the configurations of other products were assigned by analogy. Finally, based on the absolute configuration of the product, a mechanism was proposed. One cold pot: An asymmetric hydrosilylation−transacylation of α‐acylthio‐β‐enamino esters provided several α‐mercapto‐β‐acylamido esters in good yields and with excellent diastereoselectivities and moderate to good enantioselectivities. [ABSTRACT FROM AUTHOR]

Two‐dimensional material (2D) that possesses atomic thin geometry and remarkable properties is a star material for the fundamental researches and advanced applications. Defects in 2D materials are critical and fundamental to understand the chemical, physical, and optical properties. Photoluminescence arises in 2D materials owing to various physical phenomena including activator/dopant‐induced luminescence and defect‐related emissions, and so forth. With the advanced transmission electron microscopy (TEM) technologies, such as aberration correction and low voltage technologies, the morphology, chemical compositions and electronic structures of defects in 2D material could be directly characterized at the atomic scale. In this review, we introduce the applications of state‐of‐the‐art TEM technologies on the studies of the role of atomic defects in the photoluminescence characteristics in 2D material. The challenges in spatial and time resolution are also discussed. It is proved that TEM is a powerful tool to pinpoint the relationship between the defects and the photoluminescence characteristics. [ABSTRACT FROM AUTHOR]

1,2‐Dihydroisoquinolines are important building blocks of many natural products and phamarceuticals. In continuation of our ongoing research on transformations of quinone derivatives, herein we present a catalyst‐free cascade annulation of β‐enamino esters with 2‐(2‐nitrovinyl)‐1,4‐benzoquinone, which allowed for the synthesis of various novel 1,2‐dihydroisoquinoline derivatives in moderate to good yields (60 %–99 %). This method is applicable to a wide variety of β‐enamino esters. The structure of one product was determined by an x‐ray crystal analysis. Moreover, a plausible mechanism was proposed. [ABSTRACT FROM AUTHOR]

To screen and evaluate possible functional factors in the bamboo lignin moiety that could block non‐productive adsorption of enzyme proteins on lignin, milled wood lignin (MWL) and Fenton oxidized lignin (FOLs) were prepared and incorporated in the enzymatic hydrolysis of Avicel. The addition of MWL decreased the 72 h glucose yields of cellulose from 57.1 % to 45.3 %, while FOLs effectively improved the enzymatic digestibility up to 69.5 %, which was 22 % higher than the system without the use of FOLs. The adsorption affinity and binding strength of cellulase with FOLs were lower than that with MWL. After Fenton pretreatment, hydrophilicity of lignins increased due to formation of C−O− and O−C=O bonds. Furthermore, high surface negative charges on FOLs resulted in strong electrostatic repulsion against the negatively charged cellulases. Finally, analysis of FOLs with 13C and 2D‐HSQC NMR indicated that the cleavage of β‐O‐4 linkages and demethoxylation occurred, and that less condensed structures at the Cβ and Cγ positions were observed. These oxidation reactions of the bamboo lignin lead to the formation of functional factors to alleviate irreversible adsorption of cellulase onto FOLs, and thus were responsible for promoting enzymatic digestibility efficiency. These Fenton reactions of the bamboo lignin lead to formation of functional factors to alleviate irreversible adsorption of cellulase onto FOLs, and thus were responsible for promoting the enzymatic digestibility efficiency. [ABSTRACT FROM AUTHOR]

BACKGROUND Cereal fermentations have shown significant potential in improvement and design of the nutritional quality and health effects of foods and ingredients. In the present study, the effect of supplementary Lactobacillus plantarum dy-1 fermented barley ( LFB) on obesity in high-fat diet ( HFD)-induced obese rats was investigated. RESULTS LFB treatment showed a lower rate of increase in body weight and percentage of body fat and a reversal of HFD-induced glucose intolerance, with ameliorated hyperinsulinemia, decreased levels of triglycerides and total cholesterol, and inhibited concentration of interleukin ( IL)-1β, IL-6 and tumor necrosis factor-α. Moreover, LFB treatment also showed the strongest inhibition of nuclear factor ( NF)- kB activation and exhibited the greatest effects in blocking the degradation of the inhibitor of NF-kB and inhibiting p38 and JNK1 phosphorylation compared with HFD and raw barley treatment. CONCLUSIONS It was clear that Lactobacillus plantarum dy-1 fermentation significantly improves the anti-obesity properties of barley. The results establish the foundation for ameliorating diet-induced obesity of product with LFB as nutritional supplements. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

In massive multiple‐input–multiple‐output system, the accurate channel state information at the transmitter (CSIT) is required to achieve the high beamforming gain and spectral efficiency. To reduce the feedback overhead for CSIT acquisition in frequency division duplex system, a prior CSIT estimation with 1‐bit feedback per dimension is proposed to alleviate the overhead burden. Specifically, by exploiting the slow variation of channel support between the consecutive frames, the channel support in the previous frame is regarded as the prior information for CSIT estimation of current frame. Then, the received compressed channel measurements at the user side are quantized to 1 bit per measurement and only the sign information is fed back to the base station (BS). At the BS side, the CSIT recovery from the 1‐bit channel feedback information is formulated as a 1‐bit sparse complex‐value signal recovery problem with prior information. Finally, a prior support complex binary iterative hard thresholding algorithm is proposed to perform the CSIT estimation at the BS side. Simulation results demonstrate that the proposed scheme can reduce both the pilot and feedback overhead for CSIT estimation. [ABSTRACT FROM AUTHOR]

Summary: The multiuser millimeter wave (mmWave) MIMO system has been considered as a promising technology for future 5G cellular networks since high volume of data rates can be achieved by simultaneously supporting multiple users. However, the channel estimation is challenging due to the multiuser interference in frequency‐selective hybrid mmWave MIMO system. In this paper, we focus on the multiuser uplink wideband channel estimation with frequency selectivity. Specifically, a layer‐precoder reuse strategy is proposed, in which each transmission frame is divided into several subframes and the users share a common precoder at each subchannel of different subcarriers. Then, instead of only estimating channel of one user, multiuser frequency‐selective channel can be jointly estimated via a sparse recovery formulation. Furthermore, by exploiting the common sparsity among subchannels in frequency‐selective mmWave system, a distributed compressed sensing (DCS)–based channel estimation is proposed to jointly acquire the channel state information of all users via weighted least square to further reduce the pilot overhead. In addition, the Cramer‐Rao lower bound (CRLB) is derived for multiuser frequency‐selective channel estimation. Simulation results demonstrate that the proposed DCS‐based method can asymptotically approach the CRLB of channel estimation. A layer‐precoder reuse strategy is proposed, in which each transmission frame is divided into several subframes and the users share a common precoder at each subchannel of different subcarriers. Multiusers frequency‐selective channel can be jointly estimated via a sparse recovery formulation via the proposed distributed compressed sensing‐based channel‐estimation algorithm by exploiting the common sparsity. The Cramer‐Rao lower bound (CRLB) is derived for multiuser frequency‐selective channel estimation. [ABSTRACT FROM AUTHOR]