Gelatin-Based Metamaterial Hydrogel Films with High Conformality for Ultra-Soft Tissue Monitoring

Implantable hydrogel-based bioelectronics(IHB)can precisely monitor human health and diagnose diseases.However,achieving biodegradability,biocompatibility,and high conformality with soft tissues poses significant challenges for IHB.Gelatin is the most suitable candidate for IHB since it is a collagen hydrolysate and a substantial part of the extracellular matrix found naturally in most tissues.This study used 3D printing ultrafine fiber networks with metamaterial design to embed into ultra-low elastic modulus hydrogel to create a novel gelatin-based conductive film(GCF)with mechanical programmability.The regulation of GCF nearly covers soft tissue mechanics,an elastic modulus from 20 to 420 kPa,and a Poisson’s ratio from-0.25 to 0.52.The negative Poisson’s ratio promotes conformality with soft tissues to improve the efficiency of biological interfaces.The GCF can monitor heartbeat signals and respiratory rate by determining cardiac deformation due to its high conformability.Notably,the gelatin characteristics of the biodegradable GCF enable the sensor to monitor and support tissue restoration.The GCF metamaterial design offers a unique idea for bioelectronics to develop implantable sensors that integrate monitoring and tissue repair and a customized method for endowing implanted sensors to be highly conformal with soft tissues.

Validity ranges of interfacial wave theories in a two-layer fluid system

In the present paper, we endeavor to accomplish a diagram, which demarcates the validity ranges for interfacial wave theories in a two-layer system, to meet the needs of design in ocean engineering. On the basis of the available solutions of periodic and solitary waves, we propose a guideline as principle to identify the validity regions of the interfacial wave theories in terms of wave period T, wave height H, upper layer thickness dl, and lower layer thick-ness d2, instead of only one parameter-water depth d as in the water surface wave circumstance. The diagram proposed here happens to be Le Mehaute＇s plot for free surface waves if water depth ratio r= d1/d2 approaches to infinity and the upper layer water density p1 to zero. On the contrary, the diagram for water surface waves can be used for two-layer interfacial waves if gravity acceleration g in it is replaced by the reduced gravity defined in this study under the condition of σ=（P2 - Pl）/P2 → 1.0 and r 〉 1.0. In the end, several figures of the validity ranges for various interfacial wavetheories in the two-layer fluid are given and compared with the results for surface waves.

High efficient catalytic oxidation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid under benign conditions with nitrogen-doped graphene encapsulated Cu nanoparticles

Selective oxidation of 5-hydroxymethylfurfual(HMF) to 2,5-furandicarboxylic acid(FDCA) as a bioplastics monomer is efficiently promoted by a simple system without noble-metal and base additives. In this work, graphene oxide(GO) was first synthesised by an electrochemical method with flexible graphite paper(FGP) as start carbon material, then, nitrogen-doped graphene(NG) layers encapsulated Cu nanoparticles(NPs) was prepared by one-step thermal treatment of GO supported Cu2+ in flowing NH3 atmosphere. Compared with NG supported Cu NPs prepared by the traditional impregnation method, enhanced catalytic activity was achieved over Cu/NG and an FDCA yield of 95.2% was achieved under mild reaction conditions with tert-butylhydroperoxide(t-BuOOH) as the oxidant. Control experiments with different catalysts and different addition procedure of t-BuOOH showed the yield of HMF and various intermediates during reaction. From the changing of intermediates concentrations and reaction rates, a reaction pathway through HMF-DFF-FFCA-FDCA was proposed. This work gives a more convenient, more green,more economical and effective method in encapsulated metal NPs preparation and high selectivity in HMF oxidation to FDCA under mild conditions.

Seepage-stress coupled modeling for rainfall induced loess landslide

Although rainfall is rare on the Loess Plateau of western China, landslides occur frequently there in rainy season. Surveys report that landslide hazards always follow heavy rains. In this study, a seepage-stress coupling model for rainfall induced landslide is used to examine an actual disastrous event in Yulin by the end of July, 2017. The effects of rainfall duration, rainfall intensity and soil weakening on slope stability are studied in detail. The results illustrate that the safety factor drops sharply at first and then is gradually declining to below 1.05 during additional two days of heavy rain. With soil strength softening considered, the slope would be more unstable, in which the weakening in soil cohesion is found to be a more sensitive factor.

Strength softening models of soil and its application in rainfall-induced landslide simulation

In this study, strength softening models are developed for exploring rainfall-induced landslide mechanism based on Mohr Coulomb strength theory with both saturation degree and temporal evolution into consideration. According to the ratio of two time scales available, the model can be classified into three categories, i.e., instant softening model, delay softening model, and coupling softening model. Corresponding evolution functions are specified to represent these kinds of softening processes and then applied to simulate landslide of homogeneous slopes triggered by rainfall, therefrom, useful conclusions can be drawn in the end.

Process, mechanism and impacts of scale formation in alkaline flooding by a variable porosity and permeability model

In spite of the role of alkali in enhancing oil recovery（EOR）, the formation of precipitation during alkaline-surfactant-polymer（ASP） flooding can severely do harm to the stratum of oil reservoirs, which has been observed in situ tests of oil fields such as scale deposits found in oil stratum and at the bottom of oil wells. On the other hand,remarkable variation of stratum parameters, e.g., pore radius,porosity, and permeability due to scale formation considerably affects seepage flow and alkaline flooding process in return. The objective of this study is to firstly examine these mutual influential phenomena and corresponding mechanisms along with EOR during alkaline flooding when the effects of precipitation are no longer negligible. The chemical kinetic theory is applied for the specific fundamental reactions to describe the process of rock dissolution in silicabased reservoirs. The solubility product principle is used to analyze the mechanism of alkali scale formation in flooding.Then a 3D alkaline flooding coupling model accounting for the variation of porosity and permeability is established to quantitatively estimate the impact of alkali scales on reservoir stratum. The reliability of the present model is verified in comparison with indoor experiments and field tests of the Daqing oil field. Then, the numerical simulations on a 1/4well group in a 5-spot pattern show that the precipitation grows with alkali concentration, temperature, and injection pressure and, thus, reduces reservoir permeability and oil recovery correspondingly. As a result, the selection of alkaliwith a weak base is preferable in ASP flooding by tradeoff strategy.

Effect of the Cladding Layer Cavity on the Efficiency of 650 nm Resonant Cavity Light Emitting Diodes

High efficiency 650 nm resonant cavity light emitting diodes (RCLEDs) with a cladding layer cavity are reported. The epitaxial structure is grown with a metal-organic chemical vapor deposition (MOCVD) system. Al 0.5Ga 0.5 As/Al As is used for the distributed Bragg reflectors (DBRs), and GaInP/AlGaInP multiple-quantum wells for the active region. Two RCLED samples have been fabricated, one with a cladding layer cavity and the other without. Experimental results show that the cladding layer cavity can improve the internal quantum efficiency effectively, so that an external quantum efficiency of 7.4% at 20 mA is reached. Meanwhile, the sample with cladding layer cavity also shows a spectral stability as the injected current changing from 20 mA to 100 mA.

硫掺杂碳包覆Fe_(0.95)S_(1.05)纳米球复合材料的储钠性能

铁硫化物因其较高的理论容量,被认为是一种很有前途的钠离子电池负极材料。然而,铁硫化物在充放电过程中存在较大的体积变化,导致其倍率性能和稳定性较差。本文通过简单的一步法策略,制备了一种具有三维簇状结构的硫掺杂碳包覆的Fe_(0.95)S_(1.05)纳米球(Fe_(0.95)S_(1.05)@SC),并研究了其储钠性能。硫掺杂碳层可提高材料的导电率,缓解Fe_(0.95)S_(1.05)纳米球在反应过程中产生的体积膨胀,故提升了材料的稳定性。Fe_(0.95)S_(1.05)@SC的相互贯通的簇状结构,为电子和离子的传输提供了通道,使材料具备优异的倍率性能。在半电池体系中,Fe_(0.95)S_(1.05)@SC在0.1A·g^(-1)下循环100圈后,保留614.7 m Ah·g^(-1)的高比容量,10 A·g^(-1)下比容量仍可以达到235.7 m Ah·g^(-1)。在全电池体系中,在0.1和10 A·g^(-1)时,Fe_(0.95)S_(1.05)@SC的可逆容量分别为482.8和288.3 m Ah·g^(-1)。该材料具有良好电化学性能,在钠离子电池中具有广阔的应用前景。

Effects of incident wind/wave directions on dynamic response of a SPAR-type floating offshore wind turbine system

As a promising renewable energy,offshore wind energy currently is gaining more attention,by which the economic and efficient operation of floating wind turbine systems is a potential research direction.This study is primarily devoted to the analysis of dynamic response of the NREL-5 MW reference wind turbine supported by an OC3-Hywind SPAR-type platform using a recompiled code which combines FAST with WAMIT.To verify the reliability of the recompiled code,the free decay motions of a floating wind turbine system in still water are examined with satisfactory results.After that,thirteen scenarios with different angles between wind and wave from 0°to 90°are investigated.The dynamic responses of the turbine system in various degrees of freedom(DOFs)for different incident wind/wave directions are presented in both time and frequency domains via the fast Fourier transform.

Effects of tide-surge interaction and wave set-up/set-down on surge: case studies of tropical cyclones landing China's Zhe-Min coast

Storm surge along the China＇s Zhe-Min coast is addressed using the tightly coupled surge model ofADCIRC＋SWAN. In this study, we primarily focus on the effects of surge-tide interaction and waveset-up/set-down. And the influences of intensity and landing moment of tropical cyclone （TC） arealso presented. The results show that： water elevation without considering tide-surge interactiontends to be underestimated/overestimated when TC lands during astronomical low/high tide;tide-surge coupling effect is more pronounced north of TC track （more than 0.7 m in our cases）;irrelevant to TC＇s intensity, wave set-up south of TC track is negligible because the depth-relatedwave breaking doesn＇t occur in water body blown towards open seas.

Estimation of extreme wind speed in SCS and NWP by a non-stationary model

In offshore engineering design, it is considerably significant to have an adequately accurate estimation of marine environmental parameters, in particular, the extreme wind speed of tropical cyclone （TC） with different return periods to guarantee the safety in projected operating life period. Based on the 71-year （1945-2015） TC data in the Northwest Pacific （NWP） by the Joint Typhoon Warning Center （JTWC） of US, a notable growth of the TC intensity is observed in the context of climate change. The fact implies that the traditional stationary model might be incapable of predicting parameters in the extreme events. Therefore, a non-stationary model is proposed in this study to estimate extreme wind speed in the South China Sea （SCS） and NWP. We find that the extreme wind speeds of different return periods exhibit an evident enhancement trend, for instance, the extreme wind speeds with different return periods by non- stationary model are 4.1%-4.4% higher than stationary ones in SCS. Also, the spatial distribution of extreme wind speed in NWP has been examined with the same methodology by dividing the west sea areas of the NWP 0°-45°N, 105°E-130°E into 45 subareas of 5° × 5°, where oil and gas resources are abundant. Similarly, remarkable spacial in-homogeneity in the extreme wind speed is seen in this area： the extreme wind speed with 50-year return period in the subarea （15°N-20°N, 115°E-120°E） of Zhongsha and Dongsha Islands is 73.8 m/s, while that in the subarea of Yellow Sea （30°N-35°N, 120°E-125°E） is only 47.1 m/s. As a result, the present study demonstrates that non-stationary and in-homogeneous effects should be taken into consideration in the estimation of extreme wind speed.

On the degradation of granular materials due to internal erosion

A new state-based elasto-plastic constitutive relationship along with the discrete element model is established to estimate the degradation of granular materials due to internal erosion.Four essential effects of internal erosion such as the force network damage and relaxation are proposed and then incorporated into the constitutive relationship to formulate internal erosion impacts on the mechanical behavior of granular materials.Most manifestations in the degradation of granular materials,such as reduction of peak strength and dilatancy are predicted by the modified constitutive relationship in good agreement with the discrete element method（DEM）simulation.In particular,the sudden reduction of stress for conspicuous mass erosion in a high stress state is captured by force network damage and the relaxation mechanism.It is concluded that the new modified constitutive relationship is a potential theory to describe the degradation of granular materials due to internal erosion and would be very useful,for instance,in the prediction and assessment of piping disaster risk during the flood season.

Study on Suitable Producing Areas of Wolfiporia extensa (Peck) Ginns by TCMGIS-Ⅱ

Based on database of ecological factors and geographic information space analysis method, we analyzed suitability of Wolfiporia extensa (Peck) Ginns producing regions, in the hope of providing reference for scientific zoning and cultivation. Ecological factors we analyzed mainly include temperature, altitude, and soil. Our analysis shows that Hubei, Anhui, Yunnan, Guizhou and Sichuan provinces are regions that have highest similarity with original producing areas of Wolfiporia extensa (Peck) Ginns. This is basically consistent with actual conditions. In addition, we predicted some regions (for example, Gansu) that have not been recorded in literature, which provides scientific and reliable data support for seed introduction and expansion of Wolfiporia extensa (Peck) Ginns. Using the GIS-based program for the distribution prediction of traditional Chinese medicine (TCMGIS-II) to analyze suitability of Wolfiporia extensa (Peck) Ginns producing regions is scientific and accurate, and will provide important reference for seed introduction, cultivation and scientific zoning of Wolfiporia extensa (Peck) Ginns.

Study on the Luminescence Properties of the Strain Compensated Quantum Well

Compared with the conventional strained quantum well, the InGaAs/GaAsP strain compensated quantum well (SCQW) has better optical properties, as the well layer and the barrier layer lattice mismatch with each other which results in the introduction of stress. In this paper, we adopted the Kohn-Luttinger Hamiltonian, conducted some theoretical calculations using the transfer matrix method, and finally verified the following change trend of the InGaAs quantum well following the In-group through experiments: the growth of the low In-group can improve the epitaxial flatness of the active area;the growth of the high In-group can increase the wavelength as well as the strain. In this paper, we adopted the AlGaAs barrier material instead of the GaAsP, made an analysis on the level changes of the compensation quantum well, and successfully fostered the strain compensated quantum well structure using the metal-organic chemical vapor deposition (MOCVD) system which had better optical properties compared with the strained quantum wells.

The Study of Relaxation Time in Test of 940 nm Semiconductor Laser

Conventional test of the peak wavelength of a laser used to be applied immediately after a device is injected current. However, the results can not be considered as an accurate description to temperature characteristic. This passage puts forward a concept of relaxation time in wavelength texts, mainly based on the experiment of 940 nm strain quantum well laser, confirming that under constant current, wavelength will get through a process of rising, and then, reach the limit. This process brings the effect on spectral characteristics of a device which cannot be ignored and the accumulated heat in relaxation time will gradually impact the emission wavelength of the laser, even crest split to form bimodal phenomenon.

Salinity elevates Cd bioaccumulation of sea rice cultured under co-exposure of cadmium and salt

Salt-tolerant rice (sea rice) is a key cultivar for increasing rice yields in salinity soil.The co-existence of salinity and cadmium (Cd) toxicities in the plant-soil system has become a great challenge for sustainable agriculture,especially in some estuaries and coastal areas.However,little information is available on the Cd accumulating features of sea rice under the co-stress of Cd and salinity.In this work,a hydroponic experiment with combined Cd(0,0.2,0.8 mg/L Cd^(2+)) and saline (0,0.6%,and 1.2%NaCl,W/V) levels and a pot experiment were set to evaluate the Cd toxic risks of sea rice.The hydroponic results showed that more Cd accumulated in sea rice than that in the reported high-Cd-accumulating rice,Chang Xianggu.It indicated an interesting synergistic effect between Cd and Na levels in sea rice,and the Cd level rose significantly with a concomitant increase in Na level in both shoot(r=0.54,p<0.01) and root (r=0.66,p<0.01) of sea rice.Lower MDA content was found in sea rice,implying that the salt addition probably triggered the defensive ability against oxidative stress.The pot experiment indicated that the coexistent Cd and salinity stress further inhibited the rice growth and rice yield,and the Cd concentration in rice grain was below 0.2 mg/kg.Collectively,this work provides a general understanding of the co-stress of Cd and salinity on the growth and Cd accumulation of sea rice.Additional work is required to precisely identify the phytoremediation potential of sea rice in Cd-polluted saline soil.

Assessment of the potential storm tide inundation hazard under climate change:case studies of Southeast China coast

Four typical cases of storm tide inundation at one of the typical storm surge prone areas in China and worldwide,i.e.Southeast China coast,are presented to demostrate the impact of climate change.It is relied on the statistical trend analysis of tropical cyclone intensification(TCI)and sea level rise(SLR)considering temporally non-stationary and spatially non-uniform effects,numerical analysis taking into account the tide-surge-wave coupling effect and GIS-based analysis for inundation evaluation.The results show that the high sea surface elevation tends to occur in the bays and around the estuaries.The maximal sea surface elevations of the worst situation at present without considering TCI and SLR(i.e.scenario S2)are 6.06 m,5.82 m and 5.67 m around Aojiang,Feiyunjiang and Oujiang river estuaries,respectively.Whereas,the maximal sea surface elevations for the three estuaries would increase to 7.02 m,6.67 m and 6.44 m,respectively,when the non-stationary extreme wind speed of 100-year recurrence period and SLR equivalent to the situation of 2100s(i.e.scenario S4)are taking into account.The potential inundation area of scenario S4 would expand by 108%to about 798 km^(2) compared with scenario S2.In addition,the remotely sensed maps and inundation durations of the hardest hit regions are provided,which will aid the prevention and mitigation of storm tide inundation hazard and future coastal management there.

一种高效且轻量的RGB单帧人脸反欺诈模型

针对在仅具有三原色(red-green-blue,RGB)摄像头的通用消费设备上部署基于深度学习的人脸反欺诈(face anti-spoofing,FAS)算法时存在的挑战问题,提出一种高效且轻量的RGB单帧FAS(efficient and lightweight RGB frame-level face anti-spoofing,EL-FAS)模型。探索一种新的全局空间自注意力机制捕获全局上下文信息的依赖关系,以提高模型泛化能力并在受限条件下实现高检测性能;设计一种等通道像素级二元监督方法,强制模型从不同的像素中学习共享特征;采用Bottleneck模块搭建骨干网络以减少模型参数。试验结果表明,EL-FAS模型在OULU-NPU数据集的大多数协议上平均分类错误率R_(ACE)最低,取得较好的人脸欺诈检测效果,在SiW数据集和跨数据集测试中也取得较好的性能,并且模型轻量,参数只有1.34×10^(6)个。

A new solver for granular avalanche simulation： Indoor experiment verification and field scale case study

A new solver based on the high-resolution scheme with novel treatments of source terms and interface capture for the Savage-Hutter model is developed to simulate granular avalanche flows. The capability to simulate flow spread and deposit processes is verified through indoor experiments of a two-dimensional granular avalanche. Parameter studies show that reduction in bed friction enhances runout efficiency, and that lower earth pressure restraints enlarge the deposit spread. The April 9, 2000,Yigong avalanche in Tibet, China, is simulated as a case study by this new solver. The predicted results, including evolution process, deposit spread, and hazard impacts, generally agree with site observations. It is concluded that the new solver for the Savage-Hutter equation provides a comprehensive software platform for granular avalanche simulation at both experimental and field scales. In particular, the solver can be a valuable tool for providing necessary information for hazard forecasts, disaster mitigation, and countermeasure decisions in mountainous areas.

Mesoscale analysis of the suction stress characteristic curve for unsaturated granular materials

There is still no theoretical framework accounting for linkage between seepage and deformation of unsaturated granular materials.Using a mesoscale liquid bridge model,we propose the first approach for deriving the suction stress characteristic curve(SSCC).Then,we verify the method by obtaining both the soil-water characteristic curve and SSCC for cubic and tetrahedral granular packing.The approach is further validated by generating the SSCCs of granular packings with different particle size distributions.On this basis,a new two-parameter model is suggested that satisfactorily predicts the SSCCs of various real granular materials.The nonlinear variation of strength versus suction is also properly described by a new formula for three kinds of soil.We believe that this SSCC model can help resolve solid-fluid coupling in seepage and deformation problems in unsaturated granular engineering.