Layered post-transition-metal dichalcogenide SnGe2N4 as a promising photoelectric material: a DFT study

First-principles calculations were performed to study a novel layered SnGe₂N₄ compound, which was found to be dynamically and thermally stable in the 2H phase, with the space group P$\bar{6}$m2 and lattice constant a = 3.143 Å. Due to its hexagonal structure, SnGe₂N₄ exhibits isotropic mechanical properties on the x–y plane, where the Young’s modulus is 335.49 N m⁻¹ and the Poisson’s ratio is 0.862. The layered 2H SnGe₂N₄ is a semiconductor with a direct band gap of 1.832 eV, allowing the absorption of infrared and visible light at a rate of about 10⁴ cm⁻¹. The DOS is characterized by multiple high peaks in the valence and conduction bands, making it possible for this semiconductor to absorb light in the ultraviolet region with an even higher rate of 10⁵ cm⁻¹. The band structure, with a strongly concave downward conduction band and rather flat valence band, leads to a high electron mobility of 1061.66 cm² V⁻¹ s⁻¹, which is substantially greater than the hole mobility of 28.35 cm² V⁻¹ s⁻¹. This difference in mobility is favorable for electron–hole separation. These advantages make layered 2H SnGe₂N₄ a very promising photoelectric material. Furthermore, the electronic structure of 2H SnGe₂N₄ responds well to strain and an external electric field due to the specificity of the p–d hybridization, which predominantly constructs the valence bands. As a result, strain and external electric fields can efficiently tune the band gap value of 2H SnGe₂N₄, where compressive strain widens the band gap, meanwhile tensile strain and external electric fields cause band gap reduction. In particular, the band gap is decreased by about 0.25 eV when the electric field strength increases by 0.1 V Å⁻¹, making a semiconductor–metal transition possible for the layered SnGe₂N₄.

The promising photoelectric semiconductor 2H SnGe₂N₄ has a tunable electronic structure which is favorable for the absorption of light in the infrared and visible regions.     

3D flower-like molybdenum disulfide modified graphite felt as a positive material for vanadium redox flow batteries

3D flower-like molybdenum disulfide microsphere modified graphite felt (MoS₂/GF) with excellent electrocatalytic activity and redox reversibility for the VO²⁺/VO₂⁺ couple is successfully fabricated by a facile hydrothermal method. The results show that the hydrothermal reaction time has a deep influence on the MoS₂ structure; an open 3D flower-like MoS₂ structure with a layer spacing of 0.63 nm is uniformly grafted on the GF surface for a reaction time of 36 h. With the presence of MoS₂, the total resistance (1.58 Ω) and charge transfer resistance (0.01 Ω) of MoS₂/GF-36 are smaller than that of the heat treated GF (2.04 Ω and 11.27 Ω, respectively), indicating that the electrode has better conductivity and more favorable electron transfer ability. As expected, a significant increase in the capacity and energy efficiency is obtained with the MoS₂/GF-36 electrode. These satisfactory results are attributed to the 3D flower-like structure on the surface of the electrode, which increases the contact area between the electrode and the electrolyte. More importantly, the MoS₂/GF electrode with excellent stability has great application prospect in vanadium redox flow batteries (VRFBs).

The open flower-like structure facilitates vanadium ion transport. The capacity and efficiency of a battery using MoS₂/GF are dramatically increased.     

The development of novel bioactive porous titanium as a bone reconstruction material

Porous titanium fabricated by the resin-impregnated titanium substitute technique has good mechanical strength and osteoconduction. The alkali treatment of the titanium surface creates a bioactive surface. Alkali-treated porous titanium is expected to accelerate bone formation. The purpose of this study was to evaluate the bone reconstruction ability of alkali-treated porous titanium. Porous titanium (85% porosity) was treated with an alkali solution (5 N NaOH, 24 h). To assess material properties, we analyzed the surface structure by scanning electron microscopy (SEM) and mechanical strength testing. To assess bioactivity, each sample was soaked in a simulated body fluid (Hank''s solution) for 7 days. Surface observations, weight change ratio measurement (after/before being soaked in Hank''s solution) and surface elemental analysis were performed. We also designed an in vivo study with rabbit femurs. After 2 and 3 weeks of implantation, histological observations and histomorphometric bone formation ratio analysis were performed. All data were statistically analyzed using a Student''s t-test (P < 0.05) (this study was approved by the Hiroshima University animal experiment ethics committee: A11-5-5). Non-treated porous titanium (control) appeared to have a smooth surface and the alkali-treated porous titanium (ATPT) had a nano-sized needle-like rough surface. ATPT had similar mechanical strength to that of the control. After soaking into the Hank''s solution, we observed apatite-like crystals in the SEM image, weight gain, and high Ca and P contents in ATPT. There was significant bone formation at an early stage in ATPT compared with that in control. It was suggested that the alkali-treated porous titanium had a bioactive surface and induced bone reconstruction effectively. This novel bioactive porous titanium can be expected to be a good bone reconstruction material.

Porous titanium fabricated by the resin-impregnated titanium substitute technique has good mechanical strength and osteoconduction.     

Preparation and investigation of a novel iodine-based visible polyvinyl alcohol embolization material

Polyvinyl alcohol (PVA) embolization particles, currently used in clinical practice, have good expansibility and are capable of permanent embolization. However, the lack of adhesion of embolization particles contributes to facilitated recanalization after embolization, while the lack of visualization facilitates misembolization. At present, embolization materials with good expansion, adhesion, and visualization potential are urgently required in clinical practice. Here, we report the development of PVA/gelatin/iohexol (I) fiber blocks as a novel embolization material for liver embolization in rats. In our work, electrospun PVA/gelatin/I nanofibrous mats were first prepared, homogenized, centrifuged in a gradient manner, and freeze-dried to obtain fiber blocks (fiber diameter ​= ​296.2 ​± ​74.23 ​nm, length 99.6 ​± ​17.0 ​μm ​× ​width 46.9 ​± ​13.3 ​μm). The fiber blocks exhibited excellent cytocompatibility and hemocompatibility. Fiber blocks with a PVA/gelatin/I mass ratio of 8:2:10 were selected due to their excellent expansibility and adhesive properties. The PVA/gelatin/I fiber blocks display excellent liver embolic effects and computed tomography (CT) imaging potential due to a combination of the following characteristics: expansibility of PVA and gelatin, adhesive property of gelatin, and CT imaging potential of I. The developed fiber block material is an embolic material that may potentially be used in interventional medicine.     

Borophene as a promising anode material for sodium-ion batteries with high capacity and high rate capability using DFT

Two-dimensional boron synthesized by the chemical vapor deposition method is an atomically thin layer of boron with both light weight and metallicity. To investigate the potential of borophene as an anode material in sodium-ion batteries, first-principles calculations and ab initio molecular dynamics simulations were carried out. The calculated results reveal that after introducing vacancy defects, the special puckered structure becomes relatively flat and the metallic nature of the defective borophene is enhanced, while the defects in borophene can weaken sodium adsorption. A single sodium atom is preferentially absorbed on the B_V site. The adsorption energies gradually reduce with an increase in sodium concentration due to the increased Na–Na repulsion. The fully sodium storage phase of borophene corresponds to NaB₂ with a theoretical specific capacity of 1240 mA h g⁻¹, which is much larger than that of other two-dimensional materials. Most interestingly, sodium ion flows in the furrows of puckered borophene are extremely fast with a low energy barrier of 30 meV. Meanwhile, sodium diffusion on borophene was found to be highly anisotropic, as further verified by the results of the ab initio molecular dynamics simulations. The sodiated-borophene nanostructure shows enhanced electronic conductivity during the whole sodiation process, which is superior to other anode materials. Borophene is expected to be a promising candidate with high capacity and high rate capability for anode materials in sodium-ion batteries.

Two-dimensional boron synthesized by the chemical vapor deposition method is an atomically thin layer of boron with both light weight and metallicity.     

A review on the use of DFT for the prediction of the properties of nanomaterials

Nanostructured materials have gained immense attraction because of their extraordinary properties compared to the bulk materials to be used in a plethora of applications in myriad fields. In this review article, we have discussed how the Density Functional Theory (DFT) calculation can be used to explain some of the properties of nanomaterials. With some specific examples here, it has been shown that how closely the different properties of nanomaterials (such as optical, optoelectronics, catalytic and magnetic) predicted by DFT calculations match well with the experimentally determined values. Some examples were discussed in detail to inspire the experimental scientists to conduct DFT-based calculations along with the experiments to derive a better understanding of the experimentally obtained results as well as to predict the properties of the nanomaterial. We have pointed out the challenges associated with DFT, and potential future perspectives of this new exciting field.

Depiction of unusual properties of nanomaterials through DFT studies.     

大鼠坐骨神经缺损修复中应用新型可降解材料的可行性研究

目的:探讨新型的人工合成的可降解材料Poly(DL-lactide-co-ε-caprolac-tone)修复周围神经损伤的可行性。方法:将Poly(DL-lactide-co-ε-caprolactone)用特殊方法制成长10mm,内径1.3mm,壁厚0.5mm的神经套管。健康成年SD大鼠24只,随机分为3组,每组8只。实验组用Poly(DL-lactide-co-ε-caprolactone)神经套管,对照I组用自体神经移植,对照II组用硅胶管桥接。3组均修复5mm长坐骨神经缺损,术后3个月分别观察3组大鼠的足跟溃疡时间、步态、关节活动,计算坐骨神经指数(sciaticnervefunctionindex,SFI),测量坐骨神经动作电位的潜伏期、波幅和传导速度。并行常规苏木精-伊红(HE)染色和S-100免疫组织化学染色(常规ABC法),以及运动终板的免疫组织化学和透射电镜观察超微结构。结果:实验组术后3个月各组坐骨神经动作电位的波幅和传导速度与对照II组比较,差异有显著性意义;HE染色显示神经套管桥接处神经结构连续性良好,移植段可见神经纤维通过,同时可见新生的血管。S-100免疫反应阳性的雪旺氏细胞沿神经纤维分布成条带状。运动终板乙酰胆碱酯酶阳性反应加深,于腓肠肌的中上部形成终板带,经结合镀银染色可见再生神经束及发出的分支与运动终板相连。电镜观察超微结构接近正常的运动终板。结论:Poly(DL-lactide-co-ε-ca     

Theoretical prediction of HfB2 monolayer,a two-dimensional Dirac cone material with remarkable Fermi velocity

Searching for new two-dimensional (2D) Dirac cone materials has been popular since the discovery of graphene with a Dirac cone structure. Based on density functional theory (DFT) calculations, we theoretically designed a HfB₂ monolayer as a new 2D Dirac material by introducing the transition metal Hf into a graphene-like boron framework. This newly predicted HfB₂ monolayer has pronounced thermal and kinetic stabilities along with a Dirac cone with a massless Dirac fermion and Fermi velocities (3.59 × 10⁵ and 6.15 × 10⁵ m s⁻¹) comparable to that of graphene (8.2 × 10⁵ m s⁻¹). This study enriches the diversity and promotes the application of 2D Dirac cone materials.

A novel 2D boron-based Dirac cone material: a HfB₂ monolayer.     

新型止血材料SURGICELTM和明胶海绵在神经外科手术中的应用（英文）

背景:新型止血材料SURGICELTM在其他科室显微手术中已取得较好的临床效果,而在神经外科中尚无前瞻性随机对照的研究结果报道。目的:比较明胶海绵和新型止血材料SURGICELTM控制神经外科术中出血及局部渗血的效果。方法:选择苏州市立医院神经外科2008-04/2010-12进行颅脑手术的患者60例,按随机数字表法分为SURGICELTM止血组30例和明胶海绵止血组30例。术中各自使用这两种止血材料进行止血。结果与结论:明胶海绵止血组止血失败率为10%(3/30),显著高于SURGICELTM止血组[3%(1/30)],差异有显著性意义(P<0.05)。SURGICELTM止血组止血时间为(2.43±0.75)min,明胶海绵止血组止血时间为(4.23±0.89)min,两组比较差异有显著性意义(P<0.05),术后均未发生过敏反应和排斥反应。新型止血材料SURGICELTM较传统明胶海绵可以更迅速地控制神经外科手术中的出血及局部渗血,止血成功率明显提高。     

Unorthodox synthesis,biological activity and DFT studies of novel and multifunctionalized naphthoxocine derivatives

A new promising protocol has been developed for the synthesis of scarce oxocine derivatives 3a–e and 6 through addition of amine-based nucleophiles such as hydroxylamine hydrochloride, primary amine and hydrazide to chromonylidene benzothiazol-2-ylacetonitrile 2 in refluxing dioxane under metal free reaction conditions in moderate to good yields. Other nitrogen nucleophiles such as piperidine, hydrazine and thiosemicarbazide failed to afford the corresponding oxocinols, and instead pyridine derivatives 7, 8 and 10 were obtained exclusively. Predictive study for the biological activities using PASS (prediction of activity spectra for biologically active substances) online software showed optimistic activities for oxocinols 3a–e in the treatment of cancer, influenza A and microbial infections. Additionally, DFT studies of oxocine derivatives 3a–e and 6 indicated the presence of required thermodynamics parameters for the application in dye-sensitized solar cells (DSSCs).

A new promising protocol has been developed for the synthesis of scarce oxocine derivatives through addition of amine-based nucleophiles to chromonylidene benzothiazol-2-ylacetonitrile under metal free reaction conditions in moderate to good yields.     

Diaminopyrene modified reduced graphene oxide as a novel electrode material for excellent performance supercapacitors

In this paper, novel reduced graphene oxide (rGO) composites (DAPrGOs) modified by diaminopyrene (DAP) were successfully synthesized via a facile solvothermal reaction method and used for supercapacitors. Compared with the pristine rGO, the DAPrGO1 electrode showed distinctly better performance (397.63 F g⁻¹vs. 80.29 F g⁻¹ of pristine rGO at 0.5 A g⁻¹) with small charge transfer resistance. When a symmetric device was fabricated using DAPrGO1 as the active material, it also exhibited a high capacitance of 82.70 F g⁻¹ at 0.5 A g⁻¹ with an energy density of 25.84 W h kg⁻¹ at a power density of 375 W kg⁻¹, and even offered a high power density of 7500 W kg⁻¹ (18.71 W h kg⁻¹) at 10 A g⁻¹. Moreover, the device possessed good electrochemical stability up to 20 000 cycles, implying promising applications in energy storage fields.

Schematic illustration of the facile synthesis process of DAPrGOs nanocomposites, Ragone plots and the superior cyclic stability of the assembled DAPrGO1//DAPrGO1 SSS.     

Hybrid material by anchoring a ruthenium(ii) imine complex to SiO2: preparation,characterization and DFT studies

Ruthenium–silica hybrid material (RuCl₂(PR₃)₂-2-PyCH-AMPTSi/SiO₂) was prepared and characterized by various spectroscopic techniques. A deconvolution procedure was applied to the spectroscopic data to deconstruct the overlapped bands. A density functional theoretical approach was applied to get insights into the electronic structure of the ruthenium coordination site and the functional RI-PBE-D3/Def2TZVP basis set was used for the optimization. Relativistic effects were considered using the zero-order regular approximation (ZORA). The anchoring process, evinced for each step of the synthesis of the hybrid material, was tracked by FT-IR analyses. The transitions observed in the FT-IR spectra were verified by DFT analyses, which agree with the experimental data. In the DRS-UV-Vis spectra, three main bands were detected by the deconvolution procedure that correspond to the charge transfer transitions, with the main contributions from ruthenium-chlorine and imine–pyridine fragments. TD-DFT results reveal that ruthenium-chlorine antibonding orbitals act as main charge donors, while pyridine–imine is the main charge acceptor.

Ruthenium–silica hybrid materials were synthesized. The process was tracked by FT-IR, DRS-UV-Vis, DFT and deconvolution analyses, finding experimental–theoretical correlation.     

Aqueous starch acetate dispersion as a novel coating material for controlled release products.

The aim of this study was to evaluate film-formation properties of a novel, organic solvent-free aqueous dispersion of potato starch acetate (SA; degree of substitution 2.8) and its ability to control drug release from a coated tablet. Initially, film-formation mechanisms and drug permeabilities of both organic solvent and dispersion-based SA free films (prepared by cast or spraying techniques) were investigated. The SA dispersion was suitable for the fluid-bed coating process, forming strong films with complete coalescent polymeric spheres. The model compounds predominantly permeated via the micro-pores of SA free films, which resulted from the leaching of water-soluble excipients from the dispersion. Thus, the permeation rate depended on the film structure rather than the physico-chemical properties of the penetrant. In the case of SA-coated tablet, drug release was sustained when the coating level was increased (from 12% to 20%, stated as a weight gain), and also as lipophilicity of the drug increased. When compared to the reference polymer dispersion (Surelease), SA coatings showed better mechanical properties against the osmotic pressure caused by a hydrophilic core tablet. These results clearly demonstrate that SA dispersion has high utility as a novel aqueous coating material for controlled release products.     

A novel adaptive ensemble classification framework for ADME prediction

It has now become clear that in silico prediction of ADME (absorption, distribution, metabolism, and elimination) characteristics is an important component of the drug discovery process. Therefore, there has been considerable interest in the development of in silico modeling of ADME prediction in recent years. Despite the advances in this field, there remains challenges when facing the unbalanced and high dimensionality problems simultaneously. In this work, we introduce a novel adaptive ensemble classification framework named as AECF to deal with the above issues. AECF includes four components which are (1) data balancing, (2) generating individual models, (3) combining individual models, and (4) optimizing the ensemble. We considered five sampling methods, seven base modeling techniques, and ten ensemble rules to build a choice pool. The proper route of constructing predictive models was determined automatically according to the imbalance ratio (IR). With the adaptive characteristics of AECF, it can be used to work on the different kinds of ADME data, and the balanced data is a special case in AECF. We evaluated the performance of our approach using five extensive ADME datasets concerning Caco-2 cell permeability (CacoP), human intestinal absorption (HIA), oral bioavailability (OB), and P-glycoprotein (P-gp) binders (substrates/inhibitors, PS/PI). The performance of AECF was evaluated on two independent datasets, and the average AUC values were 0.8574–0.8602, 0.8968–0.9182, 0.7821–0.7981, 0.8139–0.8311, and 0.8874–0.8898 for CacoP, HIA, OB, PS and PI, respectively. Our results show that AECF can provide better performance and generality compared with individual models and two representative ensemble methods bagging and boosting. Furthermore, the degree of complementarity among the AECF ensemble members was investigated for the purpose of elucidating the potential advantages of our framework. We found that AECF can effectively select complementary members to construct predictive models by our auto-adaptive optimization approach, and the additional diversity in both sample and feature space mainly contribute to the complementarity of ensemble members.

AECF is a GA based ensemble method. It includes four components which are (1) data balancing, (2) generating individual models, (3) combining individual models, and (4) optimizing the ensemble.     

Preparation of a novel PEG-clay hybrid as a DDS material: dispersion stability and sustained release profiles.

An advanced hybrid drug carrier has been developed using porous nanocrystals of a swelling clay mineral conjugated with a block copolymer containing poly(ethylene glycol) and polyamine segments. Synthetic hectorite (Laponite) modified with (alpha-acetal-poly(ethylene glycol)-block-[poly(2-(N,N-dimethylamino) ethyl methacrylate)] (Acetal-PEG-b-PAMA) produced a homogeneous dispersion of organic-inorganic hybrid in an aqueous solution, which showed flocculation-resistive properties with an elevated ionic strength. The zeta-potential measurement revealed that nonionic PEG brush layers are formed on the surface of the clay nanocrystals since negative charge of the clay surface was completely neutralized by the positive charge of the cationic PAMA segment and the entire surface charge is successfully shielded by the effect of nonionic PEG segment in the block copolymer. This charge neutralization is in good agreement with the dispersion stability in solutions of high ionic strength. The average particle size of the PEG-modified hybrid particle was estimated to be 120 nm by a dynamic light scattering (DLS) method. When pyrene was used as the model compound of hydrophobic drug, it was incorporated into the nanopore in the clay mineral without showing any remarkable expansion of the basal spacings. Fluorescence spectra and powder X-ray diffraction patterns demonstrated that pyrene molecules are captured in an amorphous state in the range of low pyrene content (<5%), while excimer formation was seen at the higher pyrene concentration (>5%). The PEG-clay hybrid act as a carrier for sustained release of hydrophobic substances due to the high affinity (K = 1.52 x 10(4)) between the drug and clay surface.     

Problems with the use of whole blood as a sample material in novel direct glucose analysers

We report a marked shift in whole-blood glucose measurements when a widely available glucose analyser is used. We compared a conventional glucose dehydrogenase (GDHG) method after protein precipitation and a direct polarographic method in conjunction with immobilized glucose oxidase. The polarographic method gave mean whole blood glucose levels from 79% to 95% of those measured by the GDHG method. No such difference was found in either plasma or serum samples or in water-based control samples. The stability of glucose in fluoride oxalate tubes appears to be poorer than is usually assumed. We observed a 5-10% decrease in whole-blood glucose concentrations during the first hour after sampling under routine conditions.     

Phenalenyl based neutral radical as a novel electrochromic material modulating visible to short-wave infrared light

Applications for energy saving smart windows require materials which can switch from transmissive to black states in both the visible and short-wave IR range. We introduce an electrochromic phenalenyl based neutral radical small molecule and design devices capable of modulating light in both of these ranges.

A phenalenyl based small molecule can modulate from a transmissive to black state in the visible to short-wave infrared range.