High photoelectric conversion efficiency and fast relaxation time of FA_(0.4)MA_(0.6)PbI_(3) applied in ultrafast modulation of terahertz waves

Active control of terahertz(THz)waves is attracting tremendous attentions in terahertz communications and active photonic devices.Perovskite,due to its excellent photoelectric conversion performance and simple manufacturing process,has emerged as a promising candidate for optoelectronic applications.However,the exploration of perovskites in optically controlled THz modulators is still limited.In this work,the photoelectric properties and carrier dynamics of FA_(0.4)MA_(0.6)PbI_(3)perovskite films were investigated by optical pumped terahertz probe(OPTP)system.The ultrafast carrier dynamics reveal that FA_(0.4)MA_(0.6)PbI_(3)thin film exhibits rapid switching and relaxation time within picosecond level,suggesting that FA_(0.4)MA_(0.6)PbI_(3)is an ideal candidate for active THz devices with ultrafast response.Furthermore,as a proof of concept,a FA_(0.4)MA_(0.6)PbI_(3)-based metadevice with integrating plasma-induced transparency(PIT)effect was fabricated to achieve ultrafast modulation of THz wave.The experimental results demonstrated that the switching time of FA_(0.4)MA_(0.6)PbI_(3)-based THz modulator is near to 3.5 ps,and the threshold of optical pump is as low as 12.7μJ cm^(-2).The simulation results attribute the mechanism of ultrafast THz modulation to photo-induced free carriers in the FA_(0.4)MA_(0.6)PbI_(3)layer,which progressively shorten the capacitive gap of PIT resonator.This study not only illuminates the potential of FA_(0.4)MA_(0.6)PbI_(3)in THz modulation,but also contributes to the field of ultrafast photonic devices.

Twinning behaviors of Mg-Sn alloy with basal or prismatic Mg_(2)Sn

The Mg-Sn alloys,with basal or prismatic Mg_(2)Sn laths,were employed to reveal the effect of precipitate orientation on twinning behavior quantitatively.The Mg-5wt.%Sn alloys with basal or prismatic Mg_(2)Sn were compressed to study the twinning behaviors.Subsequently,an Orowan strengthening model was developed to quantitatively investigate the critical resolved shear stress(CRSS)increment of precipitates on twinning.The results revealed that the prismatic precipitates hindered the transfer and growth of tensile twins more effectively compared with the basal precipitates.The decreased proportion of tensile twins containing prismatic Mg_(2)Sn might be attributed to a larger CRSS increment for tensile twins compared with that for basal precipitates.The obvious decreased twinning transfer in the alloy with prismatic Mg_(2)Sn could be due to its higher geometrically necessary dislocation and enhanced CRSS of tensile twins.Notably,the prismatic precipitates have a better hindering effect on tensile twins during compression.

Structure Regulation of Electric Double Layer via Hydrogen Bonding Effect to Realize High-Stability Lithium-Metal Batteries

The interfacial chemistry of solid electrolyte interphases(SEI)on lithium(Li)electrode is directly determined by the structural chemistry of the electric double layer(EDL)at the interface.Herein,a strategy for regulating the structural chemistry of EDL via the introduction of intermolecular hydrogen bonds has been proposed(p-hydroxybenzoic acid(pHA)is selected as proof-of-concept).According to the molecular dynamics(MD)simulation and density functional theory(DFT)calculation results,the existence of hydrogen bonds realizes the anion structural rearrangement in the EDL,reduces the lowest unoccupied molecular orbital(LUMO)energy level of anions in the EDL,and the number of free solvent molecules,which promotes the formation of inorganic species-enriched SEI and eventually achieves the dendrite-free Li deposition.Based on this strategy,Li‖Cu cells can stably run over 185 cycles with an accumulated active Li loss of only 2.27 mAh cm^(-2),and the long-term cycle stability of Li‖Li cells is increased to 1200 h.In addition,the full cell pairing with the commercial LiFePO_(4)(LFP)cathodes exhibits stable cycling performance at 1C,with a capacity retention close to 90%after 200 cycles.

Carbon-doped CuFe_(2)O_(4) with C-O-M channels for enhanced Fenton-like degradation of tetracycline hydrochloride: From construction to mechanism

Carbon-doped copper ferrite(C–CuFe_(2)O_(4))was synthesized by a simple two-step hydrothermal method,which showed enhanced tetracycline hydrochloride(TCH)removal efficiency as compared to the pure CuFe_(2)O_(4) in Fenton-like reaction.A removal efficiency of 94%was achieved with 0.2 g L^(-1) catalyst and 20 mmol L^(-1) H_(2)O_(2) within 90 min.We demonstrated that 5%C–CuFe_(2)O_(4) catalyst in the presence of H_(2)O_(2) was significantly efficient for TCH degradation under the near-neutral pH(5–9)without buffer.Multiple techniques,including SEM,TEM,XRD,FTIR,Raman,XPS M€ossbauer and so on,were conducted to investigate the structures,morphologies and electronic properties of as-prepared samples.The introduction of carbon can effectively accelerate electron transfer by cooperating with Cu and Fe to activate H_(2)O_(2) to generate·OH and·O_(2)^(-).Particularly,theoretical calculations display that the p,p,d orbital hybridization of C,O,Cu and Fe can form C–O–Cu and C–O–Fe bonds,and the electrons on carbon can transfer to metal Cu and Fe along the C–O–Fe and C–O–Cu channels,thus forming electron-rich reactive centers around Fe and Cu.This work provides lightful reference for the modification of spinel ferrites in Fenton-like application.

鱼肝油软膏联合地奈德乳膏治疗儿童变应性接触性皮炎疗效及皮肤屏障修复作用研究

目的研究鱼肝油软膏联合地奈德乳膏治疗儿童变应性接触性皮炎(ACD)的疗效及对患儿皮损皮肤屏障的修复效果。方法选取ACD患儿80例随机分为对照组和试验组,每组各40例。对照组给予地奈德乳膏治疗,试验组给予鱼肝油软膏联合地奈德乳膏治疗。治疗2周后,比较两组患儿治疗前后主客观症状评分及皮肤屏障功能指标[角质层含水量、表皮油脂含量及表皮水分丢失量(TEWL)]的变化,以及两组疗效。Spearman相关性分析试验组临床疗效与角质层含水量、表皮油脂含量及TEWL的相关性。结果治疗后,两组局部烧灼感、瘙痒、丘疹、红斑等症状体征评分及水疱数目均较前降低(P<0.01);且试验组上述评分均低于对照组(P<0.05)。两组表皮油脂含量、角质层含水量均较前升高(P<0.05),TEWL则较前降低(P<0.05);且试验组各项皮肤屏障功能指标均优于对照组(P<0.05)。试验组临床疗效高于对照组(92.50%vs.75.00%,P<0.05)。试验组总有效率与表皮油脂含量、角质层含水量呈正相关(r_(s)=0.496,0.438,P<0.05),与TEWL水平呈负相关(r_(s)=-0.483,P<0.05)。结论鱼肝油软膏联合地奈德乳膏治疗儿童ACD,可以有效缓解局部病灶症状,修复损伤皮肤屏障,优于单用地奈德乳膏治疗。

Microstructure and mechanical properties of Mg-3Sn-1Ca reinforced with AlN nano-particles

Microstructural evolution and strengthening mechanisms of Mg-3Sn-1Ca based alloys with additions of different amounts of Al N nanoparticles were investigated.It was found that with increasing the amount of AlN nano-particles the grain size decreases obviously.The existence of AlN nano-particles could refine the primary crystal phases CaMgSn,which provided more heterogeneous nucleation sites for the formation of magnesium.Moreover,such nano-particles could also restrict the grain growth during solidification.After adding AlN nano-particles,both the tensile properties at room temperature and high temperature 250℃and the hardness are largely improved.The improvement of strength is attributed to grain refinement and second phase refinement.

Effect of potential difference between nano-Al_(2)O_(3)whisker and Mg matrix on the dispersion of Mg composites

The potential difference between positive and negative ions was utilized to improve the homogenized dispersion of nanoscale Al_(2)O_(3) whiskers in Mg matrix composites.The Mg powders were decorated with sodium dodecylbenzene sulfonate(C_(18)H_(29)NaO_(3)S,SDBS)and were introduced to the cathode group on their surface.The Al_(2)O_(3) whiskers were modified by the cetyl trimethyl ammonium bromide(C_(19)H_(42)BrN,CTAB)and were featured in the anode group.The suitable contents of CTAB and SDBS,the application atmosphere,and the type of solvents were investigated.Dispersion results showed that adding 2wt%SDBS into Mg powders and adding 2wt%CTAB into Al_(2)O_(3) whiskers pro-moted the formation of more uniformly mixed composite powders,compared to those of conventional ball milling via scanning electron micro-scopy(SEM)analysis.Meanwhile,the calculated results derived from first-principle calculations also demonstrated the stronger cohesion between Al_(2)O_(3) whisker reinforcements and Mg matrix than undecorated composite powders.After preparation by powder metallurgy,the mor-phology,grain size,hardness,and standard deviation coefficient of composites were analyzed to evaluate the dispersed efficiency.The results indicated that the modification of homogenized dispersed Al_(2)O_(3) whiskers in composites contributed to the refinement of 26%in grain size and the improvement of 20%in hardness compared with pure Mg,and the reduction of 32.5%in the standard deviation coefficient of hardness compared with the ball-milling sample.

二烯丙基二硫在RORα抑制人胃癌细胞上皮间质转化中的作用

目的探讨二烯丙基二硫(DADS)是否上调维甲酸相关孤核受体α(RORα)抑制人胃癌细胞株MGC803细胞上皮-间质转化(EMT)。方法相差显微镜观察MGC803细胞形态的改变。逆转录PCR(RTPCR)、蛋白免疫印迹法(Western blot)、免疫荧光与免疫组织化学检测EMT的相关分子表达。裸鼠实验检测DADS与沉默RORα对移植瘤生长的影响。结果相差显微镜显示,沉默RORα细胞较MGC803细胞大小与形状差异更明显。DADS作用后,细胞大小较一致,呈圆形或椭圆形,梭形细胞减少,异型性下降。RT-PCR与Western blot显示,DADS处理后较处理前各组RORαm RNA与蛋白表达上调(P<0.05)。DADS作用对照组与空载体组较沉默组效果更为明显(P<0.05)。RORα沉默较对照组和空载体组细胞锌指转录因子(Snail)和波形蛋白(Vimentin)m RNA与蛋白表达上调,而E-钙黏蛋白(E-cadherin)m RNA与蛋白下调(P<0.05)。DADS处理后,各组Snail蛋白下调、Vimentin m RNA与蛋白下调和E-cadherin m RNA与蛋白上调(P<0.05)。免疫荧光显示,沉默组细胞Snail与Vimentin阳性表达较对照组增强,而E-cadherin阳性表达减弱。DADS作用后,结果相反。裸鼠移植瘤实验显示,RORα沉默组移植瘤较对照组生长加快和体重增加(P<0.05),增殖细胞核抗原(Ki-67)、Snail、CD34及Vimentin阳性表达较对照组增加,而E-cadherin阳性降低。DADS处理各组移植瘤生长与体积减慢与减小,Ki-67、Snail、CD34与Vimentin阳性表达较对照组减弱,而E-cadherin阳性表达增强。结论 DADS通过上调RORα可体内外抑制人胃癌MGC803细胞EMT。

Correlation between pre-miR-146a C/G polymorphism and gastric cancer risk in Chinese population

AIM:To investigate the association between pre-miR- 146a C/G polymorphism and gastric cancer risk. METHODS:We performed a hospital-based,case-control study using polymerase chain reaction-restriction fragment length polymorphism method in 608 individuals(304 gastric cancer patients and 304 age and sex matched cancer-free controls).RESULTS:The frequencies of pre-miR-146a C/G genotypes in the case group were significantly different from those in the control groups(P=0.037).Compared with CC genotype carriers,subjects with the variant genotypes(GC+GG)had a 58%increased risk of gastric cancer(adjusted OR=1.58,95%CI:1.11-2.20,P= 0.009).Moreover,a higher gastric cancer risk was especially evident in younger individuals aged≤58 years, nonsmokers,and males(adjusted OR=1.76,95%CI: 1.08-2.87,P=0.024;adjusted OR=1.55,95%CI: 1.06-2.28,P=0.025;adjusted OR=1.53,95%CI: 1.04-2.27,P=0.033;respectively). CONCLUSION:Pre-miR-146a C/G polymorphism might be associated with an elevated risk of gastric cancer in Chinese population.

Association betweenITGA2 C807T polymorphism and gastric cancer risk

AIM： To evaluate the impact of the ITGA2 gene polymorphism on gastric cancer risk. METHODS： A hospital-based case-control study was conducted, including 307 gastric cancer patients and 307 age- and gender-matched control subjects. The genotypes were identified by polymerase chain reaction-restriction fragment length polymorphism assay. RESULTS： The frequencies of the wild and variant genotypes in cases were significantly different from those of controls （P = 0.019）. Compared with individuals with the wild genotype CC, subjects with the variant genotypes （CT ＋ IT） had a significantly higher risk of gastric cancer （adjusted odds ratio = 1.57, 95% CI = 1.13-2.17, P = 0.007）. In stratified analyses, the elevated gastric cancer risk was especially evident in older individuals aged 〉 58 years, nonsmokers and rural subjects. Further analyses revealed that the variant genotypes were associated with poor tumor differentiation and adjacent organ invasion in the sub-analysis of gastric cancer patients. CONCLUSION： The ITGA2 gene C807T polymorphism may be associated with an increased risk of gastric cancer, differentiation and invasion of gastric cancer.

Effect of Ca addition on grain refinement of Mg–9Li–1Al alloy

The as-cast and as-extruded Mg–9Li–1Al–xCa alloys(x=0,0.2;wt%)were prepared by a simple alloying process followed by hot extrusion with an extrusion ratio of 28.2.The microstructures of the as-cast and as-extruded Mg–9Li–1Al–xCa alloys were observed to investigate the effect of calcium(Ca)element on the Mg–9Li–1Al(LA91)alloy,and the crystallographic calculations between Al_(2)Ca and the matrix(α-Mg andβ-Li phases)were examined on the basis of the edge-to-edge matching model.The experimental results indicate that the addition of 0.2 wt%Ca into LA91 alloy reduce the size of theα-Mg phases in the as-cast alloy and that ofβ-Li phases in the as-extruded alloy due to the Al_(2)Ca particles distributed inside the matrix.Crystallographic calculation results suggested that there is a good crystallographic matching between the matrix and Al_(2)Ca,which confirmed that Al_(2)Ca particles can act as a heterogeneous nucleation site for bothα-Mg andβ-Li phases and were effective grain refiners for LA91 alloy.

The effect of temperature on phase equilibria of polyethylene glycol(PEG8000)-K_(2)SO_(4)-H_(2)O at T=(288.15,298.15,308.15)K

The phase behavior of potassium sulfate(K_(2)SO_(4))in polyethylene glycol with molecular weight 8000(PEG8000)andwater(H_(2)O)mixed solvent at 288.15,298.15,and 308.15 Kwere determined.According to the results,when the temperature are 288.15 and 298.15 K,there is only a solid-liquid phase equilibrium relationship in the system,and the phase diagrams are both divided into three parts which respectively are the regions of unsaturated homogeneous liquid(L),one liquid and one solid K_(2)SO_(4)(L+S)and one liquid and twosolids K_(2)SO_(4) and PEG8000(L+2S).The solubility of K_(2)SO_(4) in PEG8000-H_(2)O mixed solvent decreased with the addition of the PEG8000 in the solution.Comparing the diagrams of 288.15 and 298.15 K,the sizes of regions of(L)and(L+S)increased and that of(L+2S)decreased with the increase of temperature.While at 308.15 K,solid-liquid and liquid-liquid equilibrium coexist,and there are six parts in the complete phase diagram at 308.15 K,adding the areas of one liquid and one solid K_(2)SO_(4)(L+S),two liquids(2 L),two liquids and one solid K_(2)SO_(4)(2 L+S).The equations developed by Merchuk,Hu,and Jayapalwere used to fit the binodal curves data of the systemat 308.15 K,meanwhile,the experimental tie-line data of the system at 308.15 K were correlated by Othmer-Tobias equation and Bancroft equation.

Fatigue Life Prediction of Rolling Bearings Based on Modified SWT Mean Stress Correction

The existing engineering empirical life analysis models are not capable of considering the constitutive behavior of materials under contact loads;as a consequence,these methods may not be accurate to predict fatigue lives of roll-ing bearings.In addition,the contact stress of bearing in operation is cyclically pulsating,it also means that the bear-ing undergo non-symmetrical fatigue loadings.Since the mean stress has great effects on fatigue life,in this work,a novel fatigue life prediction model based on the modified SWT mean stress correction is proposed as a basis of which to estimate the fatigue life of rolling bearings,in which,takes sensitivity of materials and mean stress into account.A compensation factor is introduced to overcome the inaccurate predictions resulted from the Smith,Watson,and Topper(SWT)model that considers the mean stress effect and sensitivity while assuming the sensitivity coefficient of all materials to be 0.5.Moreover,the validation of the model is finalized by several practical experimental data and the comparison to the conventional SWT model.The results show the better performance of the proposed model,especially in the accuracy than the existing SWT model.This research will shed light on a new direction for predicting the fatigue life of rolling bearings.

Diterpene Synthases and Their Responsible Cyclic Natural Products

This review provides an overview of diterpene synthases which were initially identified via genetic and/or biochemical means,traversing all organisms researched to date.

Long-cycling lithium-oxygen batteries enabled by tailoring Li nucleation and deposition via lithiophilic oxygen vacancy in Vo-TiO_(2)/Ti_(3)C_(2)Tx composite anodes

Uncontrollable Li dendrite growth and infinite volume fluctuation during durative plating and stripping process gravely hinder the application of metallic Li electrode in lithium-oxygen batteries.Herein,oxygen vacancy-rich TiO_(2)(Vo-TiO_(2))nanoparticles(NPs)uniformly dispersing on Ti_(3)C_(2)T_(x)(Vo-TiO_(2)/Ti_(3)C_(2) T_(x))with excellent lithiophilicity feature are presented as effective composite anodes,on which a dense and uniform Li growth behavior is observed.Based on electrochemical studies,mutiphysics simulation and theoretical calculation,it is found that Vo-TiO_(2) coupling with three dimensional(3 D)conductive Ti_(3)C_(2) T_(x) MXene forms highly ordered lithiophilic sites which succeed in guiding Li ions flux and adsorption,thus modulating the uniform Li nucleation and growth.As a result,this composite electrode is capable of preserving Li with high areal capacity of~10 mAh cm^(-2) without the presence of dendrites and large volume expansion.Consequently,the as-prepared Vo-TiO_(2)/Ti_(3)C_(2) T_(x)@Li anode shows outstanding performance including low voltage hysteresis(~19 mV)and superior durability(over 750 h).When assembling with the Vo-TiO_(2)/Ti_(3)C_(2) T_(x)@Li anodes,lithium-oxygen batteries also deliver enhanced cycling stability and improved rate performance.This work demonstrates the effectiveness of oxygen vacancies in guiding Li nucleating and plating behavior at initial stage and brings a promising strategy for promoting the development of advanced Li metal-based batteries.

Optimization of Rooting Medium for Tissue Culture Seedlings of Dendrobium officinale by Response Surface Methodology

[Objectives] To increase the survival rate of tissue culture seedlings of Dendrobium officinale,and optimize the conditions of rooting medium by the response surface methodology( RSM). [Methods]The effects of 6-BA concentration,NAA concentration,potato amount and the amount of mashed banana on the growth of seedlings were determined by single factor experiment and were analyzed by Box-Behnken design and response surface methodology. [Results]The optimal culture conditions: rooting medium 1/2 MS + 6-BA 0. 24 mg/L + mashed banana 87. 63 g/L + potato 89. 30 g/L + NAA 0. 52 mg/L + sucrose 20. 0 g/L + activated carbon 4. 0 g/L + agar 7. 0 g/L,p H 5. 8,and light intensity 2 000 Lx. [Conclusions]The model established by response surface methodology has a good predictability and could be used to optimize the conditions of tissue culture and rooting medium of D. officinale.

Identification of enzymes responsible for the reduction of geraniol to citronellol

The reduction of geraniol to citronellol is the first step for the synthesis of natural phytol in the production of tocopherols and natural vitamin K.Baker's yeast was used in the bioreduction described above as a whole-cell biocatalyst.However,the enzyme responsible for the reduction of geraniol to citronellol is not yet known.Four old yellow enzyme(OYE)genes were cloned from yeast and plants,and expressed in Escherichia coli for a high level of recombinant proteins.The recombinant protein displayed a catalytic activity of converting geraniol to citronellol as a sole product verified by GC-MS analyses.The recombinant OYE2 intact cells were found to show 3.7 and 1.9-fold higher activity than that of yeast cells and the recombinant crude extracts,respectively.Compared to the recombinant fusion enzyme,the entrokinase-cleaved enzyme displayed nearly identical activity for geraniol reduction.To our knowledge,this is the first enzyme identified to catalyze the formation of citronellol from geraniol by reducing the allylic alcohol double bond,which is normally known as inactivating group for the old yellow enzymes.

Long Term Perinatal Deltamethrin Exposure Alters Electrophysiological Properties of Embryonic Ventricular Cardiomyocyte

Increased use of pyrethroids and the exposure to pyrethroids for pregnant women and children have raised the concerns over the potential effect of pyrethroids on developmental cardiotoxicity and other abnormalities.The purpose of this study was to investigate whether long tenn peri natal deltamethrin exposure altered embryonic cardiac electrophysiology in mice.Pregnant mice were administered with 0 or 3 mg/kg of deltamethrin by gavage daily from gestational day(gd)10.5 to gd 17.5.Whole cell patch-clamp technique was used in electrophysiological study,and real time RT-PCR was applied to analyze the molecular changes for the electrophysiological properties.Deltamethrin exposure resulted in increased mortality of pregnant mice and decreased viability of embryos.Moreover,deltamethrin slowed the maximum depolarization velocity(Vmax),prolonged the action potential duration(APD)and depolarized the maximuin diastolic potential(MDP)of embryonic cardiomyocytes.Additionally,perinatal deltamethrin exposure decreased the mRNA expression of Na^+channel regulatory subunit Navpl,inward rectifier K^+channel subunit Kir2.1,and delayed rectifier K^+channel subunit MERG while the L-type Ca^2+channel subunit,Cavl.2 expression was increased.On the contraiy,deltamethrin administration did not significantly alter the regulation ofβ-adrenergic or muscarinic receptor on embryonic cardiomyocytes.In conclusion,deltamethrin exposure at perinatal stage significantly alters mRNA expression of embryonic cardiac ion channels and therefore influences embryonic cardiac electrophysiological properties.This highlights the need to understand the persistent effects of pyrethroid exposure on cardiac function during embryonic development due to potential for cardiac arrhythmogenicity.

Ku80 gene G-1401T promoter polymorphism and risk of gastric cancer

AIM:To evaluate the possible relationship between the Ku80 gene polymorphism and the risk of gastric cancer in China.METHODS:In this hospital-based case-control study of gastric cancer in Jiangsu Province,China,we investigated the association of the Ku80 G-1401T (rs828907) polymorphism with gastric cancer risk.A total of 241 patients with gastric cancer and 273 age-and sexmatched control subjects were genotyped and analyzed by polymerase chain reaction-restriction fragment length polymorphism.RESULTS:The frequencies of genotypes GG,GT and TT were 65.6%,22.8% and 11.6% in gastric cancer cases,respectively,and 75.8%,17.6% and 6.6% in controls,respectively.There were significant differences between gastric cancer and control groups in the distribution of their genotypes (P=0.03) and allelic frequencies (P=0.002) in the Ku80 promoter G-1401T polymorphism.CONCLUSION:The T allele of Ku80 G-1401T may be associated with the development of gastric cancer.

Generalized δ-entropy condition to Riemann solution for Chaplygin gas in traffic flow

The Riemann problem for the Aw-Rascle model in the traffic flow with the Delta initial data for the Chaplygin gas is studied. The solutions are constructed globally under the generalized Rankine-Hugoniot relations, the δ-entropy conditions, and the generalized δ-entropy conditions. A new Delta wave, which is called a primary Delta wave, is defined in some solutions. The primary Delta wave satisfies the generalized Rankine- Hugoniot relations and the generalized δ-entropy conditions. It generates initially from the Delta initial data, which either evaluates a Delta wave, whose weight becomes stronger and stronger, or disappears at a finite time.