Ruddlesden–Popper perovskite sulfides A3B2S7: A new family of ferroelectric photovoltaic materials for the visible spectrum

Perovskite ferroelectric materials exhibit the novel ferroelectric photovoltaic effect, where photon-excited electron–hole pairs can be separated by ferroelectric polarization. Especially, semiconducting ferroelectric materials with small band gaps (E[subscript g]) have been extensively studied for applications in solar energy conversion. Traditional route for creating semiconducting ferroelectrics requires cation doping, where E[subscript g] of the insulating perovskite ferroelectric oxides are reduced via substitution of certain cations. But cation doping tends to reduce the carrier mobility due to the scattering, and usually lead to poor photovoltaic efficiency. In the present work, based on first-principles calculations, we propose and demonstrate a new strategy for designing stoichiometric semiconducting perovskite ferroelectric materials. Specifically, we choose the parent non-polar semiconducting perovskite sulfides AB S[subscript 3] with Pnma symmetry, and turn them into ferroelectric Ruddlesden–Popper A[subscript 3]B[subscript 2]S[subscript 7] perovskites with spontaneous polarizations. Our predicted Ruddlesden–Popper Ca[subscript 3]Zr[subscript 2]S[subscript 7] and other derived compounds exhibit the room-temperature stable ferroelectricity, small band gaps (E[subscript g] < 2.2 eV) suitable for the absorption of visible light, and large visible-light absorption exceeding that of Si.National Basic Research Program of China (973 Program) (Contract 2012CB619402)National Natural Science Foundation (China) (Contract 11574244)China. Ministry of Education (Program for Innovative Research Team in University. Contract IRT13034)National Science Foundation (U.S.) (Grant DMR-1410636

cis-1,2-Bis{[4-(4-pyrid­yl)pyrimidin-2-yl]sulfanylmeth­yl}benzene

The mol­ecular skeleton of the title mol­ecule, C26H20N6S2, adopts a cis conformation with the two arms positioned on one side of the benzene ring plane. Intra­molecular π–π inter­actions between the pyrimidine rings [centroid–centroid distance = 3.654 (2) Å] and between the pyridine rings [centroid–centroid distance = 3.775 (2) Å] help to set the mol­ecular conformation; the pyrimidine rings, as well as the pyridine rings, are nearly parallel, forming dihedral angles of 4.12 (14) and 2.46 (14)°, respectively

The impact of corruption on firms’ access to bank loans: evidence from China

Current theories cannot explain the coexistence of China’s 40 years of rapid economic growth and its imperfect financial system, insufficient investor protection, and government intervention. This study empirically tests hypotheses regarding the effects of corruption on firms’ access to bank loans using econometric models based on survey data of 2,848 enterprises in China collected by the World Bank. The results show an inverted U-shaped relationship between corruption and firms’ access to bank loans: a low level of corruption increases firms’ access to bank loans, whereas a high level of corruption hinders firms from obtaining bank loans. Mild corruption may be a suboptimal choice for firms seeking bank loans, and bank funds allocation based on corruption can achieve Pareto optimality among firms. Moreover, government guarantees are conducive to firms’ access to financing and the link between corruption and firms’ access to bank loans can be explained by the role of government guarantees. The improvement of institutional quality is positively associated with firms’ access to bank loans and weakens the effects of corruption on firms’ external financing. This study thus sheds light on the real effects of corruption and the determinants of firms’ access to bank loans in developing countries

Adsorption of phenylacetylene on Si(100)-2×1: Reaction mechanism and formation of a styrene-like π-conjugation system

This is the published version. Copyright 2003 American Physical SocietyThe interactions of phentylacetylene and phenylacetylene−α−d1 with Si(100)−2×1 have been studied as a model system to mechanistically understand the adsorption of conjugated π-electron aromatic substitutions on Si(100)−2×1. Vibrational signatures show that phenylacetylene covalently binds to the surface through a [2+2]-like cycloaddition pathway between the external C≡C and Si=Si dimer, forming styrene-like conjugation structure which was further supported by the chemical-shift of C 1s core level. These experimental results are consistent with the density-functional theory [B3LYP/6−311//+G(d)] calculations. The resulting styrene-like conjugation structures may possibly be employed as an intermediate for further organic syntheses and fabrication of molecular architecture for modification and functionalization of Si surfaces, or as a monomer for polymerization on Si surfaces

Multi-behaviors coordination controller design with enzymatic numerical P systems for robots

Membrane computing models are parallel and distributed natural computing models. These models are often referred to as P systems. This paper proposes a novel multi-behaviors coordination controller model using enzymatic numerical P systems for autonomous mobile robots navigation in unknown environments. An environment classifier is constructed to identify different environment patterns in the maze-like environment and the multi-behavior coordination controller is constructed to coordinate the behaviors of the robots in different environments. Eleven sensory prototypes of local environments are presented to design the environment classifier, which needs to memorize only rough information , for solving the problems of poor obstacle clearance and sensor noise. A switching control strategy and multi-behaviors coordinator are developed without detailed environmental knowledge and heavy computation burden, for avoiding the local minimum traps or oscillation problems and adapt to the unknown environments. Also, a serial behaviors control law is constructed on the basis of Lyapunov stability theory aiming at the specialized environment, for realizing stable navigation and avoiding actuator saturation. Moreover, both environment classifier and multi-behavior coordination controller are amenable to the addition of new environment models or new behaviors due to the modularity of the hierarchical architecture of P systems. The simulation of wheeled mobile robots shows the effectiveness of this approach

Description of variation of genlculate&#x27;s features of _Phyllodiaptomustunguidus_ shen et Tai and sex-linked inheritance of Calanoida in freshwater

In the present paper, variation of genlculate&#x27;s features of _Phyllodiaptomustunguidus_ shen et Tai of Calanoida are described.The authors find that the right first antenna of female species has changed into genlculate and first antenna of male species changed into genlculate, which can be explained by X-sex-linked inheritance. This isn&#x27;t a disease but a genetic characteristic that is better for the living of the species

Cough Test during Tension-Free Vaginal Tape Procedure in Preventing Postoperative Urinary Retention

Objective. To discuss the practical value of the cough test during the tension-free vaginal tape (TVT) procedure. Methods. In the first group, 41 patients of female stress incontinence received TVT operations which were performed according to the Ulmsten’s method strictly, only that the stress of tape was adjusted in light of the cough test. In the second group, 44 patients of female stress incontinence received TVT operations in which the tape was put under the urethral tract without stress, not adjusted by cough test. Results. The cure rate was 38/41 (92.6%) in the cough test group and 41/44 (93.1%) in the noncough test group; detrusor pressure-uroflow study indicated that there were 11 cases in the obstruction zone in the cough test group while only 3 cases were in the obstruction zone in the noncough test group; 4 cases of urinary retention and 5 cases of voiding dysfunction were found in the cough test group, while difficulties of urination were not found in the non-cough test group. Conclusion. Adjusting the tape stress in accordance with the cough test during the TVT can increase the opportunity of urinary retention or difficulty of urination after operation. So there is no benefit of the cough test during tension-free vaginal tape procedure in preventing post-operative urinary retention

A cyclometalated palladium-azo complex as a differential chromogenic probe for amino acids in aqueous solution

Solutions of a cyclometalated palladium-azo complex exhibited differential UV-Vis absorption spectra in the presence of alpha-amino acids with different side chain groups

High level expression of bikunin in Pichia pastoris by fusion of human serum albumin

Bikunin is a proteoglycan exhibiting broad-spectrum inhibitory activity against serine proteases and could potentially suppress tumor cell invasion and metastasis. Here, we have successfully expressed recombinant human bikunin (rh-bikunin) in Pichia pastoris and also established the purification procedure. Different fusion genes of h-UTI and domain I, domain I and domain II, domain I, domain II and domain III of human serum albumin (HSA) were inserted into expression vector pPICZαA. After expressed in shake flask, rh-bikunin was produced in an 30-L fermenter and purified by affinity chromatography and cation exchange chromatography. The final expression levels were 200 mg/L and we got totally 1.08 g (3650 IU/mg) of active purified rh-bikunin (purity is 98%) from 20 L of fermentation broth. The rh-bikunin consists of unique form with molecular masses of 25 kDa, and has the same N-terminals sequence as human native bikunin. This study provided a new method for high level expression of active rh-bikunin by using HSA as fusion parter

不同年龄和性别精神分裂症患者脑白质扩散张量成像的临床研究*

Objective: Diffusion tensor imaging (DTI) was used to analyze the changes of white matter fiber FA in patients with schizophrenia of different ages and genders, and to explore the reference of clinical imaging. Methods: Retrospective analysis of the clinical diagnosis of schizophrenia patients and healthy subjects in all 50 cases, were given routine examination of brain MRI parallel diffusion tensor imaging, comparison of different age and gender in different parts of the brain white matter changes of FA value. Results: (1) the FA values of white matter in different age groups were different between the patients and the normal group (P &lt; 0.05). The normal group right superior frontal gyrus, left parietal lobe and left anterior cingulate gyrus of the cerebral white matter fiber FA value increased gradually before the age of 30, at the age of 30 and reached the peak gradually decreased after 30 years old. The left frontal gyrus and corpus callosum in patients with group pressure (after) of cerebral white matter fiber FA value increased gradually before the age of 30, at the age of 30 and reached the peak gradually decreased after 30 years old. (2) the FA values of white matter in different parts of male and female patients were different (P &lt; 0.05). The white matter fiber FA in the left anterior capsule of the normal group was higher in males than in females. The FA value of bilateral occipital white matter in male patients was lower than that in female; the FA values of the central white matter in the left and right sides of the brain stem were higher in males than in females. Conclusion: the changes of FA value in the white matter of some parts of the brain in the normal group and the patient group are influenced by age and sex.  目的  运用扩散张量成像分析不同年龄和性别精神分裂症患者脑白质纤维FA值的变化，探讨临床影像学参考依据。方法  回顾性分析经临床确诊的精神分裂症患者和健康者各50例，均作颅脑MRI常规检查并行扩散张量成像，比较不同年龄和性别各部位脑白质FA值变化特点。结果  （1）患者组和正常组不同年龄各部位脑白质FA值有差异（P＜0.05）。正常组中右额上回、左顶叶及左扣带回前部脑白质纤维FA值在30岁前逐渐增高，30岁达高峰，在30岁后逐渐减少。患者组中左额上回及胼胝体压部（后）脑白质纤维FA值在30岁前逐渐增高，30岁达高峰，在30岁后逐渐减少。（2）患者组和正常组男女各部位脑白质FA值有差异（P＜0.05）。发现正常组中左侧内囊前肢脑白质纤维FA值男性较女性高。患者组中双侧枕叶脑白质纤维FA值男性较女性低；脑干左右侧中心脑白质FA值男性较女性高。结论  正常组和患者组大脑某些部位脑白质纤维FA值量的变化受年龄、性别的影响