Procyanidin A_1 and its digestive products alleviate acrylamide-induced IPEC-J2 cell damage through regulating Keap1/Nrf2 pathway

Our previous study has revealed that procyanidin A_(1)(A_(1))and its simulated digestive product(D-A,)can alleviate acrylamide(ACR)-induced intestine cell damage.However,the underlying mechanism remains unknown.In this study,we elucidated the molecular mechanism for and D-A_(1) to alleviate ACR-stimulated IPEC-J2 cell damage.ACR slightly activated nuclear factor erythroid 2-related factor 2(Nrf2)signaling and its target genes,but this activation could not reduce intestine cell damage.A_(1) and D-A_(1) could alleviate ACR-induced cell damage,but the effect was abrogated in cells transiently transfected with Nrf2 small interfering RNA(siRNA).Further investigation confirmed that A_(1) and D-A_(1) interacted with Ketch-like ECH-associated protein 1(Keapl),which boosted the stabilization of Nrf2,subsequently promoted the translocation of Nrf2 into the nucleus,and further increased the expression of antioxidant proteins,thereby inhibiting glutathione(GSH)consumption,maintaining redox balance and eventually alleviating ACR-induced cell damage.Importantly,there was no difference between A_(1) and D-A_(1) treated groups,indicating that A_(1) can tolerate gastrointestinal digestion and may be a potential compound to limit the toxicity of ACR.

Distal-scanning common path probe for optical coherence tomography

In this paper,we present a distal-scanning common path probe for optical coherence tomography(OCT)equipped with a hollow ultrasonic motor and a simple and specially designed beam-splitter.This novel probe proves to be able to effectively circumvent polarization and dispersion mismatch caused by fiber motion and is more robust to a variety of interfering factors during the imaging process,experimentally compared to a conventional noncommon path probe.Furthermore,our design counteracts the attenuation of backscattering with depth and the fall-off of the signal,resulting in a more balanced signal range and greater imaging depth.Spectral-domain OCT imaging of phantom and biological tissue is also demonstrated with a sensitivity of∼100dB and a lateral resolution of∼3μm.This low-cost probe offers simplified system configuration and excellent robustness,and is therefore particularly suitable for clinical diagnosis as one-off medical apparatus.

基于遗传算法的高精度事故重建与损伤分析

为提高交通事故的重建精度,对行人的颅脑损伤风险进行分析。基于3D激光扫描技术建立事故车辆多刚体模型,采用多目标遗传算法求取最优近似解,运用优化软件ISIGHT和多刚体动力学软件MADYMO建立耦合模型,精确重建人-车碰撞运动学响应,最后采用THUMS有限元假人模型对颅脑损伤风险进行预测分析。结果表明:事故车辆逆向重建效果良好,优化后的人车运动学行为与监控视频一致,假人的头部损伤部位和损伤情况与伤情报告完全吻合。

Determination of Tea Saponin in Camellia Seed Oil with UV and HPLC Analysis

A simple procedure is described for the HPLC and UV determination of tea saponin in tea seed oil. Determinate was accomplished with UV wavelength detection 550 nm for saponification sample, and HPLC was done under conditions: C18 analytical column of TC-C18, 4. 6 × 250 mm, column temperature at room temperature, injected sample volume was 10 μL, mobile phase’s methanol, flow-rate 0.8 ml/min and detection wavelength 280 nm.

AUTOMATED ASSESSMENT OF EPIDERMAL THICKNESS AND VASCULAR DENSITY OF PORT WINE STAINS OCT IMAGE

Optical coherence tomography(OCT)enables in vivo imaging of port wine stains(PWS)lesions.The knowledge of vascular struct ure and epidermal thickness(ET)of PWS may aid the objectivediagnosis and optimal treatment.To obtain the structural parameters more rapidly and avoiduser intervention,an automated algorithm of energy map is introduced based on intensity andedge information to extract the skin surface using dynamic programming method.Subsequently,an averaged A-scan analysis is performed to obtain the mean ET and the relative intensity ofdermis indicating the corresponding vascular density.This approach is currently successfullyapplied in clinical diagnosis and shows promising guidance and assessment of PDT treatment.

Multi-frame speckle reduction in OCT using supercontinuum pumped by noise-like pulses

In most coherent imaging modality,speckle noise is a major cause that blurs the boundary of tissues and degrades the image contrast.By utilizing the unique properties of supercontinuum(SC)generated by noise-like pulses(NLPs)and a simple multi-frame averaging technique,we achieved significant speckle reduction in spectral domain optical coherence tomography(SD-OCT).We quantitatively compared the speckle of our proposed method with those of conventional swept source OCT(SS-OCT)and SD-OCT based on commercial light sources.The experimental results show that SC pumped by NLPs combined with noncoherent averaging method achieves better denoising performance in terms of contrast to noise ratio(CNR).

Realistic Dilemma and Solution of “Vocational Skill Test” under the Background of Enrollment Reform of Classified Examination in Higher Vocational Colleges in Jilin Province

In the process of Higher Vocational classified examination enrollment reform,Jilin Province has adopted a diversified examination enrollment model and“cultural quality test+vocational skill test”evaluation method,and established the“vocational education college entrance examination”system.This paper analyzes the important role and practical difficulties of“vocational skill test”in Higher Vocational classified examination,studies the existing problems,and puts forward to reasonably divide the proportion of“cultural quality test”and“vocational skill test”,sets diversified admission standards,scientifically sets up the assessment methods and contents of“vocational skill test”,further improves the“cultural quality test+vocational skill test”evaluation method and builds a classified examination and enrollment system more in line with the characteristics of vocational education.

Phase engineering oriented defect-rich amorphous/crystalline RuO_(2) nanoporous particles for boosting oxygen evolution reaction in acid media

Imposing phase engineering to porous materials is promising to realize outperforming electrocatalytic performances by taking advantages of the merits of porous nanoarchitecture and heterophase structure.In this work,amorphous/crystalline ruthenium oxide(RuO_(2))porous particles with rationally regulated heterophases are successfully prepared by integrating the phase engineering into the porous material synthesis.The resultant defect-rich amorphous/crystalline RuO_(2)porous particles exhibit excellent electrocatalytic performance toward the oxygen evolution reaction,achieving a low overpotential of 165 mV at a current density of 10 mA·cm^(−2)and a high mass activity up to 133.8 mA·cm^(-2)at a low overpotential of 200 mV.This work indicates that the synergistic effect of amorphous/crystalline heterophase and porous structural characteristics enables RuO_(2)to trigger a superior electrocatalytic activity.

Construction of highly congested quaternary carbon centers by NHC catalysis through dearomatization

A NHC-catalyzed hypervalent iodine reagents and transition-metal free redox-neutral dearomatization of phenols is reported.This protocol provides an efficient access for highly congested quaternatry carbon centers construction.It also features operationally simplicity,mild reaction conditions and good functional group tolerance.Moreover,the reported procedure can be easily emplified to 1 g scale.Mechanism study reveals the dearomative transformation possibly undergoes a single electron transfer process with NHC radical cation as a reactive intermediate.

光学相干层析技术在朱墨时序检验中的初步研究

朱墨时序一直以来都是法庭科学文件检验领域中的难题之一。鉴于此,首先利用一种新型的光学断层成像技术,即光学相干层析(OCT)技术对朱墨时序进行检验,该技术具有原位、无损、快速和高分辨率等优点。利用一套中心波长为900nm的频域OCT系统对三种不同类型的朱墨时序样本进行OCT成像检验,比较不同类型样品朱墨交叉区域的二维断层OCT图像的特征差异,并分析特征差异产生的原因。初步实验研究结果表明,利用OCT技术可以为朱墨时序的判断提供一种有效的处理手段,为补充和丰富现有的方法体系奠定基础。

Pd-Ag alloy hollow nanostructures with interatomic charge polarization for enhanced electrocatalytic formic acid oxidation

Formic acid oxidation is an important electrocatalytic reaction in proton- exchange membrane （PEM） fuel cells, in which both active sites and species adsorption/activation play key roles. In this study, we have developed hollow Pd-Ag alloy nanostructures with high active surface areas for application to electrocatalytic formic acid oxidation. When a certain amount of Ag is incorporated into a Pd lattice, which is already a highly active material for formic acid oxidation, the electrocatalytic activity can be significantly boosted. As indicated by theoretical simulations, coupling between Pd and Ag induces polarization charges on Pd catalytic sites, which can enhance the adsorption of HCO0＊ species. As a result, the designed electrocatalysts can achieve reduced Pd usage and enhanced catalytic properties at the same time. This study represents an approach that simultaneously fabricates hollow structures to increase the number of active sites and utilizes interatomic interactions to tune species adsorption/ activation towards improved electrocatalytic performance.

Single atom accelerates ammonia photosynthesis

Atomically dispersed metal has gained much attention because of the new opportunities they offer in catalysis. However, it is still crucial to understand the mechanism of single-atom catalysis at molecular level for expanding them to other more difficult catalytic reactions, such as ammonia synthesis from nitrogen. In fact, developing ammonia synthesis under ambient conditions to overcome the high energy consumption in well-established Haber-Bosch process has fascinated scientists for many years.Herein, we demonstrate that single Cu atom yields facile valence-electron isolation from the conjugated π electron cloud of p-CN. Electron spin resonance measurements reveal that these isolated valence electrons can be easily excited to generate free electrons under photo-illumination, thus inducing high efficient photo-induced ammonia synthesis under ambient conditions.The NH_3 producing rate of copper modified carbon nitride(Cu-CN) reached 186 μmol g^(-1) h^(-1) under visible light irradiation with the quantum efficiency achieved 1.01% at 420 nm monochromatic light. This finding surely offers a model to open up a new vista for the ammonia synthesis at gentle conditions. The introduction of single atom to isolate the valence electron also represents a new paradigm for many other photocatalytic reactions, since the most photoinduced processes have been successfully exploited sharing the same origin.

Enhanced O2 reduction on atomically thin Pt-based nanoshells by integrating surface facet, interfacial electronic, and substrate stabilization effects

To fully realize the commercial viability of Pt in fuel cells, the usage of scarce Pt must be reduced while the activity and durability in 02 reduction reaction （ORR） must be enhanced. Here we report a metallic stack design achieving these goals for ORR, based on atomically precise materials synthesis. Au@Pd@Pt nanostructures with atomically thin Pt shells and high-index surfaces form an excellent platform for integrating the effects of electronic structures, surface facets, and substrate stabilization to boost ORR performance. Au@Pd@Pt trisoctahedrons （TOH） achieve mass activity 6.1 times higher than that of commercial Pt/C and dramatically enhanced durability beyond 1.0 V vs. a reversible hydrogen electrode in oxidation potential. Meanwhile, Pt comprises only 3.2% of the nanostructures. To further improve the ORR activity and demonstrate the versatility of our strategy, we implement the same design in PtNi alloy electrocatalysts. The Au@Pd@PtNi TOHs exhibit mass activity 14.3 times higher than that of commercial Pt/C as well as excellent durability. This work demonstrates an alternative strategy for fabricating high-performance and low-cost catalysts, and highlights the importance of simultaneous surface and interfacial engineering with atomic precision in designing catalysts.

Etching approach to hybrid structures of PtPd nanocages and graphene for efficient oxygen reduction reaction catalysts

Cathodic oxygen reduction reaction （ORR） is a highly important electrochemical reaction in renewable-energy technologies. In general, the surface area, exposed facets and electrical conductivity of catalysts all play important roles in determining their electrocatalytic activities, while their performance durability can be improved by integration with supporting materials. In this work we have developed a method to synthesize hybrid structures between PtPd bimetallic nanocages and graphene by employing selective epitaxial growth of single-crystal Pt shells on Pd nanocubes supported on reduced graphene oxide （rGO）, followed by Pd etching. The hollow nature, {100} surface facets and bimetallic composition of PtPd nanocages, together with the good conductivity and stability of graphene, enable high electrocatalytic performance in ORR. The obtained PtPd nanocage-rGO structures exhibit mass activity （0.534 A.m-1） and which are 4.4 times and 3.9 times greater than the specific activity （0.482 mA-cm-2） corresponding values for Pt/C.

Design of Pd{111}-TiO_2 interface for enhanced catalytic efficiency towards formic acid decomposition

Supports are commonly implemented in the industrial application of heterogeneous catalysts to improve the stability and recyclability of catalysts.The supported catalysts often show the enhanced activity and selectivity in various catalytic reactions.However,the specific contributions of electronic and steric effects to a catalytic system often remain elusive due to the lack of well-defined model systems.In this work,two types of uniform Pd nanocrystals covered by{111}facets in tetrahedral and octahedral shapes,respectively,are synthesized with identical chemical environment and loaded on Ti O_2supports to form hybrid structures(Pd{111}-Ti O_2)towards the application of formic acid decomposition.Our observation suggests that the polarization effect at the interface of Pd-Ti O_2enhances its activity in formic acid decomposition.Moreover,the Pd tetrahedrons-Ti O_2hybrid structure whose Pd{111}-Ti O_2interface possesses a larger angle shows higher catalytic activity,owing to the reduced steric effect as compared to Pd octahedrons-Ti O_2.This study reveals the nature of interface effects in formic acid decomposition,and provides a guidance for the related catalyst design.

Phosphate-induced interfacial electronic engineering in VPO_(4)-Ni_(2)P heterostructure for improved electrochemical water oxidation

Anodic oxygen evolution reaction(OER)is the key bottleneck for water electrolysis technique owing to its sluggish reaction kinetics.Interfacial engineering on the rationally designed heterostructure can regulate the electronic states efficiently for intrinsic activity improvement.Here,we report a co-phosphorization approach to construct a VPO_(4)-Ni_(2)P heterostructure on nickel foam with strongly chemical binding,wherein phosphate acts as electronic modifier for Ni_(2)P electrocatalyst.Profiting from the interfacial interaction,it is uncovered that electron shifts from Ni_(2)P to VPO_(4)to render valence increment in Ni species.Such an electronic manipulation rationalizes the chemical affinities of various oxygen intermediates in OER pathway,giving a substantially reduced energy barrier.As a result,the advanced VPO_(4)-Ni_(2)P heterostructure only requires an overpotential of 289 mV to deliver a high current density of 350 mA/cm^(2)for OER in alkaline electrolyte,together with a Tafel slope as low as 28 mV/dec.This work brings fresh insights into interfacial engineering for advanced electrocatalyst design.

Integrating bimetallic AuPd nanocatalysts with a 2D aza-fused π-conjugated microporous polymer for light-driven benzyl alcohol oxidation

Efficient catalytic system with low energy consumption exhibits increasing importance due to the upcoming energy crisis.Given this situation,it should be an admirable strategy for reducing energy input by effectively utilizing incident solar energy as a heat source during catalytic reactions.Herein,aza-fused7 r-conjugated microporous polymer(aza-CMP)with broad light absorption and high photothermal conversion efficiency was synthesized and utilized as a support for bimetallic AuPd nanocatalysts in light-driven benzyl alcohol oxidation.The AuPd nanoparticles anchored on aza-CMP(aza-CM P/Au_xPdy)exhibited excellent catalytic performance for benzyl alcohol oxidation under 50 mW/cm^2 light irradiation.The improved catalytic performance by the aza-CMP/Au_xPdy is attributed to the unique photothermal effect induced by aza-CMP,which can promote the catalytic benzyl alcohol oxidation occurring at Au Pd.This work presents a novel approach to effectively utilize solar energy for conventional catalytic reactions through photothermal effect.

Probing reaction pathways for H_(2)O-mediated HCHO photooxidation at room temperature

Photooxidation provides a promising strategy for removing the dominant indoor pollutant of HCHO,while the underlying photooxidation mechanism is still unclear,especially the exact role of H2O molecules.Herein,we utilize in-situ spectral techniques to unveil the H2O-mediated HCHO photooxidation mechanism.As an example,the synthetic defective Bi2WO6 ultrathin sheets realize high-rate HCHO photooxidation with the assistance of H2O at room temperature.In-situ electron paramagnetic resonance spectroscopy demonstrates the existence of•OH radicals,possibly stemmed from H2O oxidation by the photoexcited holes.Synchrotron-radiation vacuum ultraviolet photoionization mass spectroscopy and H218O isotope-labeling experiment directly evidence the formed•OH radicals as the source of oxygen atoms,trigger HCHO photooxidation to produce CO2,while in-situ Fourier transform infrared spectroscopy discloses the HCOO*radical is the main photooxidation intermediate.Density-functional-theory calculations further reveal the•OH formation process is the rate-limiting step,strongly verifying the critical role of H2O in promoting HCHO photooxidation.This work first clearly uncovers the H2O-mediated HCHO photooxidation mechanism,holding promise for high-efficiency indoor HCHO removal at ambient conditions.

Maneuvering charge polarization and transport in 2HMoS2 for enhanced electrocatalytic hydrogen evolution reaction

Semiconducting 2H-MoS2with high chemical stability is a promising alternative to the existing electrocatalysts for the hydrogen evolution reaction (HER); however, the HER performance largely suffers from the limited number of active S sites and low mobility for charge transport. In this work, we demonstrate that the limitations of 2H-MoS2for the HER can be overcome by forming hybrid structures with metallic nanowires. Taking the integration with Pd as a proofof- concept, we show with solid experimental evidence that the one-dimensional structure of metallic nanowires facilitates electron transport to active S sites, while the interfacial charge polarization between MoS2and Pd increases the electron density of the S sites for improved activity. As a result, the hybrid structure exhibits a current density of 122 mA·cm-2at -300 mV versus RHE and a Tafel slope of 44 mV·decade-1with excellent durability, well exceeding the performances of bare 2H-MoS2and metallic 1T-MoS2. This work provides insights into electrocatalyst design based on charge transport and polarization, which can be extended to other hybrid structures. [Figure not available: see fulltext.] © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.