硅源对合成高硅ZSM-5分子筛的影响

考察了3种不同来源的硅胶对合成高硅ZSM-5分子筛的影响,并探讨了影响合成的原因。研究结果表明:硅胶比表面积的大小对分子筛的合成具有较大的影响,硅胶比表面积越大,合成效果越好。采用改进的合成方法(预解聚法和低温陈化法)可得到无石英杂晶的高硅ZSM-5分子筛。

Predicting the Degradability of Bioceramics through a DFT-based Descriptor

Bioceramics have attracted extensive attention for bone defect repair due to their excellent bioactivity and degradability.However,challenges remain in matching the rate between bioceramic degradation and new bone formation,necessitating a deeper understanding of their degradation properties.In this study,density functional theory(DFT)calculations was employed to explore the structural and electronic characteristics of silicate bioceramics.These findings reveal a linear correlation between the maximum isosurface value of the valence band maximum(VBM_(Fmax))and the degradability of silicate bioceramics.This correlation was subsequently validated through degradation experiments.Furthermore,the investigation on phosphate bioceramics demonstrates the potential of this descriptor in predicting the degradability of a broader range of bioceramics.This discovery offers valuable insights into the degradation mechanism of bioceramics and holds promise for accelerating the design and development of bioceramics with controllable degradation.

Reaction behavior of ferric oxide in system Fe_2O_3-SiO_2-Al_2O_3 during reductive sintering process

Pure compounds and kaolin were employed to investigate the reaction behavior of ferric oxide in thetrinarysystem Fe2O3?SiO2?Al2O3 during reductive sintering process. The thermodynamic analyses and reductive sintering experimental results show that ferrous oxide generated from the reduction of ferric oxide by carbon can react with silicon dioxide and aluminum oxide to form ferrous silicate and hercynite at 1173 K, respectively. In the trinary system Fe2O3?SiO2?Al2O3, ferrous oxide obtained from ferric oxide reduction preferentially reacts with aluminum oxide to form hercynite, and the reaction of ferrous oxide with silicon dioxide occurs only when there is surplus ferrous oxide after the exhaustion of aluminum oxide. When sintering temperature rises to 1473 K, hercynite further reacts with silicon dioxide to form mullite and ferrous oxide. Results presented in this work may throw a new light upon the separation of alumina and silica present in Al/Fe-bearing materials with low mass ratio of alumina to silica in alumina production.

类人胶原蛋白疤痕修复硅凝胶(可痕TM)治疗增生性瘢痕的研究

目的评价类人胶原蛋白疤痕修复硅凝胶(可痕^(TM))治疗增生性瘢痕的有效性和安全性。方法选取河南省人民医院门诊符合入选/排除标准的增生性瘢痕患者30例,随机数字表法分为对照组和试验组,对照组采用芭克硅胶软膏,试验组采用类人胶原蛋白疤痕修复硅凝胶(可痕^(TM)),持续应用3月,停止应用产品后3月继续观察效果,整个研究共6月;应用产品后的1月、2月、3月、6月来院随访检查,数码相机拍照,对瘢痕硬度、色泽、柔软度、血管分布进行检测;患者对瘢痕自觉症状进行视觉模拟评分;记录用药期间不良反应和不良事件。结果治疗后瘢痕色泽、柔软度、厚度与治疗前对比,差异具有统计学意义(P<0.05);治疗前后对照组与试验组之间瘢痕色泽、柔软度、厚度对比,差异无统计学意义(P>0.05)。结论类人胶原蛋白疤痕修复硅凝胶(可痕^(TM))治疗增生性瘢痕有效、安全,且治疗效果与芭克硅胶软膏无差异。

"类人胶原蛋白疤痕修复硅凝胶"治疗增生期增生性瘢痕多中心随机对照临床研究

目的评价"类人胶原蛋白疤痕修复硅凝胶"治疗增生期增生性瘢痕的临床效果。方法采用多中心随机对照临床研究方法,分析比较"类人胶原蛋白疤痕修复硅凝胶(可痕®)"与Silicone Gel(芭克硅凝胶软膏)对伤后或手术后4~6个月处于增生期的增生性瘢痕患者的临床治疗效果,并比较3~18岁未成年人和19~45岁成年人的疗效差别。2017年3月至2019年3月北京蔡景龙瘢痕医学研究中心(蔡景龙医疗美容门诊部)、南通大学附属医院、河南省人民医院就诊的88例患者,根据随机数字表法随机分为试验组(可痕治疗组)、对照组(芭克硅胶治疗组),每组又分成年和未成年2个亚组。试验组58例,其中成年组39例、未成年组19例;对照组30例,其中成年组20例、未成年组10例。观察、统计、分析治疗前及治疗后第4、8、12、24周各组瘢痕色泽、厚度、血管分布、柔软度、患者自觉症状、临床疗效评分及不良反应的差异。结果治疗前试验组和对照组指标评分,除试验组中未成年组的柔软度、成年组的厚度评分略高于对照组(P<0.05)外,其余参数的比较差异均无统计学意义(P>0.05)。试验组和对照组治疗后第4、8、12、24周的疗效评分指标比较,差异均有统计学意义(P<0.05),但未成年组与成年组2组间差异均无统计学意义(P>0.05);每个时间点各指标评分比较差异均存在统计学意义(P<0.05),疗效评价时间与用药分组和年龄分组均不存在交互作用(P>0.05),且不受组别或年龄分组的影响(P>0.05);各组均无不良反应发生。结论"类人胶原蛋白疤痕修复硅凝胶"治疗增生期增生性瘢痕安全有效,临床疗效非劣于对照组芭克硅凝胶软膏。

Molecular dynamics study of viscosity of aqueous NaCl solution confined in nanoscale channels

A physical model of bulk-nanochannel-bulk with buffer baths is built up using nonequilibrium molecular dynamics （MD） simulation to study the effects of vibrating silicon atoms on the viscosity of aqueous NaCl solutions confined in the nanochannel. The simulation is performed under different moving speeds of the upper wall, different heights and different surface charge densities in the nanochannel. The simulation results indicate that with the increase in the surface charge density and the decrease in the nanochannel height and the shear rate, the vibration effect of silicon atoms on the shear viscosity of the confined fluid in the nanochannel cannot be ignored. Compared with still silicon atoms, the vibrating silicon atoms result in the decrease in the viscosity when the height of the nanochannel is less than 0.8 nm and the shear rate is less than 1.0 ×10^11 s^-1, and the effect of the vibrating silicon atoms on the shear viscosity is significant when the shear rate is small. This is due to the fact that the vibrating silicon atoms weaken the interactions between the counter-ions （Na^＋ ） and the charged surface.

Evolution of Self-Organized Ge Quantum Dots During Ultra High Vacuum Annealing

The evolution of self organized Ge quantum dots structure is investigated by scanning tunneling microscopy and atomic force microscopy during annealing treatment up to 700℃ in an ultra high vacuum(UHV) system.When the sample temperature rises to 630℃,a great amount of new dots emerge on the wetting layer,which are believed to be incoherent islands compared with the dislocation free coherent islands formed during molecular beam epitaxy growth.

Microstructures and mechanical properties of in-situ TiB2/Al−xSi−0.3Mg composites

In-situ 2 vol.%TiB2 particle reinforced Al−xSi−0.3Mg(x=7,9,12,15 wt.%)composites were prepared by the salt−metal reaction,and the microstructures and mechanical properties were investigated.The results show that the TiB2 particles with a diameter of 20−80 nm and the eutectic Si with a length of 1−10μm are the main strengthening phases in the TiB2/Al−xSi−0.3Mg composites.The TiB2 particles promote grain refinement and modify the eutectic Si from needle-like to short-rod shape.However,the strengthening effect of TiB2 particles is weakened as the Si content exceeds the eutectic composition,which can be attributed to the formation of large and irregular primary Si.The axial tensile test results and fractography observations indicate that these composites show more brittle fracture characteristics than the corresponding alloy matrixes.

Two new species of Sellaphora(Bacillariophyta) from a deep oligotrophic plateau lake,Lake Fuxian in subtropical China

We describe two new species of Sellaphora from Lake Fuxian, Ytmnan Plateau, China. Based on both light and scanning electron microscopy, these species are described as S. yunnanensis sp. nov. and S. sinensis sp. nov. The primary features of S. yunnanens＆ are： elliptical to linear-elliptical valves with broadly rounded ends, straight filiform raphe, almost straight central endings and small, slightly expanding central pores, small central area, symmetrical or slightly asymmetrical central nodule. The primary features of S. sinensis are： elliptical valves, obtusely rounded ends, similar raphe and axial area, transapically less expanded central area, larger, elliptical central nodule. We compare these species to those of a similar shape and morphology.

Mechariical and Abrasion Properties of Polyethylene Terephthalate Films Coated with SiO2/Epoxy Hybrid Material

Hybrid materials were prepared using a silane coupling agent, tetraethoxysilane （ TEOS ） as the precursor, dilute hydrochloric acid as the catalyst, and epoxy as the matrices. The films coated with hybrid materials were expected to improve abrasion resistance and mechanical properties. The morphology, mechanical properties, adhesion, and abrasion resistance of the polyethylene terephthalate （PET） films were characterized using an atomic force microscope, a tensile testing machine, a bagger knife, and a reciprocating fabric abrasion tester. The result of research indicated that the modification significantly affected the abrasion resistance and roughness. The-tensile strength and abrasion resistance of the modified PET films increased by 40% and 50% respectively at 3 % TEOS mass fraction.

Synthesis of a Novel Solid Acid with both Sulfonic and Carbonyl Acid Groups and Its Catalytic Activities in Acetalization

The novel solid acid with both sulfonic and carbonyl acid groups has been synthesized from 3-((2-sulfoethoxy) carbonyl)acrylic acid and tetraethyl orthosilicate(TEOS). The catalytic activities were investigated through the acetalization. The results showed that the novel solid acid was very efficient for the reactions with the high yields. The high acidity, high stability and reusability were the key feature of the novel solid acid. Moreover, the sulfonic and carbonyl acid groups could cooperate during the catalytic process, which improved its catalytic activities. The catalyst shows recyclability, and hold great potential for replacement of homogeneous catalysts.

Initial Processes of Sulfur Adsorption on Si（100） Surface

The adsorption of one monolayer S atoms on ideal Si（100） surface is studied by using the self-consistent tight binding linear muffon-tin orbital method. Energies of adsorption systems ors atoms on different sites are calculated. It is found that the adsorbed S atoms are more favorable on B1 site （bridge site） with a distance 0.131 nm above the Si surface. The .S, Si mixed layer might exist at S/Si（100） interface. The layer projected density of states are calculated and compared with that of the clean surface. The charge transfers are also investigated.

局部注射复方倍他米松联合类人胶原蛋白瘢痕修复硅凝胶治疗增生性瘢痕的疗效评价

目的评价局部注射复方倍他米松注射液联合类人胶原蛋白瘢痕修复硅凝胶治疗增生性瘢痕的疗效。方法将2018年12月至2020年10月沈阳积水潭医院收治的70例增生性瘢痕患者按随机数字表法分为实验组和对照组,每组35例。实验组采取局部注射复方倍他米松注射液+外涂类人胶原蛋白瘢痕修复凝胶治疗,将复方倍他米松注射液(≤40 mg)注入患者瘢痕组织内,直至瘢痕呈膨隆状态、瘢痕表皮微白,每4周注射1次;每次注射后第2天开始,取适量类人胶原蛋白瘢痕修复凝胶(1~2 mg)均匀涂抹于瘢痕表面,2次/d,待瘢痕组织缩小、变平后,停用复方倍他米松,仅外用类人胶原蛋白瘢痕修复凝胶,注射3~4次为1个疗程。对照组仅采用复方倍他米松注射液治疗,方法及剂量同实验组。每4周注射1次,待瘢痕组织缩小、变平后停止治疗,注射3~4次为1个疗程。观察2组患者治疗期间不良反应发生情况,瘢痕变平及颜色接近正常皮肤时间,治疗后16周对患者临床疗效进行判定,门诊随访半年,记录患者瘢痕复发情况。数据比较采用t检验和χ^(2)检验。结果治疗过程中,实验组患者中出现皮肤萎缩1例、毛囊炎1例,不良反应发生率为5.7%;对照组患者中出现皮肤萎缩1例,毛囊炎2例,不良反应发生率为8.6%,2组比较差异无统计学意义(χ^(2)=0.001,P>0.05)。实验组瘢痕变平时间为(4.50±2.80)周,瘢痕颜色接近正常皮肤的时间为(7.5±2.7)周,对照组瘢痕变平时间为(6.23±2.80)周,瘢痕颜色接近正常皮肤的时间为(14.5±4.7)周,2组比较差异均有统计学意义(t=8.312、12.532,P<0.05)。治疗后16周,实验组显效28例,有效5例,无效2例,治疗的总有效率为94.3%;对照组显效30例,有效4例,无效1例,治疗的总有效率为97.1%,2组比较差异无统计学意义(χ^(2)=0.001,P>0.05)。随访半年,实验组瘢痕复发率为3.0%(1/33),对照组为11.8%(4/34),2组比较差异有统计学意义(χ^(2)=3.858,P<0.05)。结论局部注射复方倍他米松注射液联合类人胶原蛋白瘢痕修复硅凝胶治疗增生性瘢痕具有复发率低、瘢痕变平时间及颜色恢复时间明显缩短的优点,值得推广。

Responses of Phytolith in Guinea Grass(Leymus chinensis) Leaves to Simulated Warming,Nitrogen Deposition and Elevated CO_2 Concentration in Songnen Grassland,Northeast China

Deposited in plant cells and their intercellular space,phytoliths,a special form of silica,could be used to determine information on plant structure and physiology especially their size and content.With the hypothesis that phytolith in plant would change under variable climate and environment,the dominant plant species in Songnen grassland,guinea grass(Leymus chinensis),was treated by an open-top chamber(OTC) to elevate CO2 concentration,infrared heaters,and artificial nitrogen(N) addition for three years from 2006–2008.Phytoliths were extracted by wet-ashing method and analyzed by variance analysis and so on.We found that the responses to elevated CO2 are complicated,and warming is positive while N addition is negative to the deposition of phytoliths in L.chinensis leaves.Especially,warming could reduce the negative impact of N addition on phytolith in L.chinensis.The short cell's taxonomic in graminea is significant because of no disappearance with simulated environmental changes.The phytolith originated in the long cell and plant intercellular space are more sensitive to elevated CO2 concentration,warming,and N addition,and could become some new indicators for environmental changes.In conclusion,different phytolith types have various responses to simulated warming,N addition and elevated CO2 concentration.

Towards Cheaper Solar Cells： A New Path to Grow Silicon Ribbons

The silicon wafer accounts nearly half of the photovoltaic module cost, and hence on this issue an important opportunity remains for further decreasing the cost of photovoltaics. It is well known that ribbon technology has a large potential for costs reduction by avoiding kerr losses since no saw processes are used, preventing material losses up to 50% of the initial feedstock. On the other hand we ought to ask ourselves why we should use solid silicon feedstock, which has already undergone a crystallization process with high energy content to recrystallize it again in a crucible, spending even more energy, when we can go directly from the gaseous feedstock source to the final ribbon. The cost cutting strategy that supports the Silicon over Dust Substrate （SDS） technology, here presented, is based on the belief that ribbon technology and the silicon feedstock issue will play an important role on ＂wafer＂ cost reduction.

∧-related Quantum Interference of ^2П [Case（a）] Diatom on Rotational Energy Transfer

To study theoretically the relationship between the integral interference angle and the scat- tering angle in collisional quantum interference, the integral interference angle of atom- ^2П[case（a）] diatomic molecules system is described. To simulate the experiment theoretically, the theoretical model on collision-induced rotational energy transfer in an atom- ^2П[case（a）]diatom system is presented based on the first order Born approximation taking into account of the long-range interaction potential. For the ^2П electronic state in the Hund＇s case（a） diatom, the degree of the interference is discussed. The interference angles of collision-induced rotational energy transfer of CN（A^2П） in Hund＇s case（a） with He, Ne, and Ar are calculated quantitatively. The key parameters in the determination of integral interference angles are obtained.

A novel fabrication of meso-porous silica film by sol-gol of TEOS

A homogeneous crack-free nano- or meso-porous silica films on silicon was fabricated by colloidal silica sol derived by hydrolyzing tetraethyl orthosilicate (TEOS) catalyzing with (C4H9)4N+OH- in water medium. The solution with ratio of H2O/TEOS15, R4N+ and glycerol as templates, combining with the hydrolyzed intermediate, controlled the silica aggregating; the templated silica film with heterostructure was developed into homogeneous nano-porous then meso-porous silica films after being annealed from 750 C to 850 C; the formation mechanism of the porous silica films was discussed; morphologies of the silica films were characterized. The refractive indexes of the porous silica films were 1.2561.458, the thermal conductivity < 0.7 W/m/K. The fabricating procedure and the sequence had not been reported before.

Thermodynamic behaviors of SiCl_2 in silicon deposition by gas phase zinc reduction of silicon tetrachloride

The modified Siemens process,which is the major process of producing polycrystalline silicon through current technologies,is a high temperature,slow,semi-batch process and the product is expensive primarily due to the large energy consumption.Therefore,the zinc reduction process,which can produce solar-grade silicon in a cost effective manner,should be redeveloped for these conditions.The SiCl2 generation ratio,which stands for the degree of the side reactions,can be decomposed to SiCl4 and ZnCl2 in gas phase zinc atmosphere in the exit where the temperature is very low.Therefore,the lower SiCl2 generation ratio is profitable with lower power consumption.Based on the thermodynamic data for the related pure substances,the relations of the SiCl2 generation ratio and pressure,temperature and the feed molar ratio（n（Zn）/n（SiCl4） are investigated and the graphs thereof are plotted.And the diagrams of Kpθ-T at standard atmosphere pressure have been plotted to account for the influence of temperature on the SiCl2 generation ratio.Furthermore,the diagram of Kpθ-T at different pressures have also been plotted to give an interpretation of the influence of pressure on the SiCl2 generation ratio.The results show that SiCl2 generation ratio increases with increasing temperature,and the higher pressure and excess gas phase zinc can restrict SiCl2 generation ratio.Finally,suitable operational conditions in the practical process of polycrystalline silicon manufacture by gas phase zinc reduction of SiCl4 have been established with 1200 K,0.2 MPa and the feed molar ratio（n（Zn） /n（SiCl4）） of 4 at the entrance.Under these conditions,SiCl2 generation ratio is very low,which indicates that the side reactions can be restricted and the energy consumption is reasonable.

Atomic Design of Polarity of GaN Films Grown on SIC（0001）

Ab initio total energy calculations are used to determine the interface structure of GaN films grown on 6H-SiC(0001)with different substrate reconstructions.The results indicate that GaN films grown on bare SiC(0001)are of the Ga-polarity,while GaN films grown on SiC(0001)with Si adlayer are of the N-polarity if there is no N-Si interchange at the interface.With the interchange,the GaN films are of the Ga-polarity.

Collision-induced Rotational Energy Transfer in an Atom-Diatom System

As a further theoretical study of the collision-induced quantum interference on rotational energy transfer in an atom-diatom system, based on the first-Born approximation of time-dependent perturbation theory, taking into account the anisotropic Lennard-Jones interaction potential and the long-range interaction potential, the differential interference angles in singlet-triplet mixed states of CO A^1Π（v=9）-e3∑-（v=1） system in collision with He, Ne, Ar, and other partners were calculated theoretically. The relationships of differential interference angle versus impact parameters, including collision parameter b and velocity, are obtained.