High-performance and broadband photodetection of bicrystalline(GaN)1-x(ZnO)x solid solution nanowires via crystal defect engineering

Crystal defect engineering is widely used as an effective approach to regulate the optical and opto-electronic properties of semiconductor nanostructures.However,photogenerated electron-hole pair recombination centers caused by structural defects usually lead to the reduction of optoelectronic perfor-mance.In this work,a high-performance photodetector based on(GaN)1-x(ZnO)x solid solution nanowire with bicrystal structure is fabricated and it shows excellent photoresponse to ultraviolet and visible light.The highest responsivity of the photodetector is as high as 60,86 and 43 A/W under the irradiation of 365 nm,532 nm and 650 nm,respectively.The corresponding response time is as fast as 170,320 and 160 ms.Such wide spectral responses can be attributed to various intermediate energy levels induced by the introduction of various structural defects and dopants in the solid solution nanowire.Moreover,the peculiar bicrystal boundary along the axial direction of the nanowire provides two parallel and fast trans-mission channels for photo-generated carriers,reducing the recombination of photo-generated carriers.Our findings provide a valued example using crystal defect engineering to broaden the photoresponse range and improve the photodetector performance and thus can be extended to other material systems for various optoelectronic applications.     

Graphene films with large domain size by a two-step chemical vapor deposition process

The fundamental properties of graphene are making it an attractive material for a wide variety of applications. Various techniques have been developed to produce graphene and recently we discovered the synthesis of large area graphene by chemical vapor deposition (CVD) of methane on Cu foils. We also showed that graphene growth on Cu is a surface-mediated process and the films were polycrystalline with domains having an area of tens of square micrometers. In this paper, we report on the effect of growth parameters such as temperature, and methane flow rate and partial pressure on the growth rate, domain size, and surface coverage of graphene as determined by Raman spectroscopy, and transmission and scanning electron microscopy. On the basis of the results, we developed a two-step CVD process to synthesize graphene films with domains having an area of hundreds of square micrometers. Scanning electron microscopy and Raman spectroscopy clearly show an increase in domain size by changing the growth parameters. Transmission electron microscopy further shows that the domains are crystallographically rotated with respect to each other with a range of angles from about 13 to nearly 30°. Electrical transport measurements performed on back-gated FETs show that overall films with larger domains tend to have higher carrier mobility up to about 16,000 cm(2) V(-1) s(-1) at room temperature.     

Biological synthesis of calcite crystals using <Emphasis Type="Italic">Scindapsus aureum</Emphasis> petioles

We report a novel strategy for the biological synthesis of calcite crystals using the petioles of the plant Scindapsus aureum. The resultant calcite crystals were characterized by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffractometry, and electron diffraction. The biomolecules of S. aureum petioles were confirmed by UV–Vis and FT-IR analysis. The results showed that the spherical or rhombohedral calcite crystals were obtained in the cells of S. aureum petioles. Biomimetic synthesis of calcium carbonate (CaCO₃) in aqueous solution containing extracts of S. aureum petioles was also performed to investigate the soluble biomolecules’ influence on crystal growth of CaCO₃. It was found that twinborn spherical calcite crystals were formed, suggesting that the soluble biomolecules of S. aureum play a crucial role in directing the formation of calcite spherical particles. The possible mechanism of formation of CaCO₃ crystals using S. aureum is also discussed; the biomolecules of S. aureum may induce and control the nucleation and growth of CaCO₃ crystals.     

浅绿色彩棉纤维改性研究

研究化学改性处理对天然浅绿色彩棉纤维性能的影响。通过碱处理和戊二醛交联对纤维品质较差的浅绿色彩棉纤维进行改性。测试了碱处理及戊二醛交联后浅绿色彩棉纤维的强伸性能、弹性回复率、回潮率及纤维形态结构。试验表明:经碱处理后,浅绿色彩棉纤维强伸性能、弹性回复率得到改善,用17%氢氧化钠溶液处理10 min的浅绿色彩棉纤维性能提高较显著;经戊二醛交联后,浅绿色彩棉纤维强度增强,断裂伸长率下降,且随着接枝率的增大,断裂伸长率趋于降低,弹性回复率趋于增大。     

Diet-induced changes in alginate- and laminaran-fermenting bacterial levels in the caecal contents of rats

Brown algae contain soluble polysaccharides, such as alginic acid, fucoidan and laminaran. To assess the induction of dietary fiber-fermenting bacteria in the intestine, rats were fed diet containing no dietary fiber (control) or 2% w/w of the polysaccharides for 2 weeks. The levels of dietary fiber-fermenting bacteria in caecal contents were determined using decimal dilution culture containing 1% w/v of the fibers. Caecal microbiota in the rats was analyzed using polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). In the culture method, 4–9 log viable cells/g caecal content of alginate-fermenting bacteria was detected in rats fed alginate, while this was not detected in rats fed the control diet. Although laminaran-fermenting bacteria were detected in control rats (4–9 log viable cells/g), the level observed in rats fed laminaran was 8 or 9 log viable cells/g. On the other hand, fucoidan-fermenting bacteria were not detected in rats fed fucoidan. DGGE analysis showed laminaran administration increased the diversity of bacterial bands. Clostridium spp. and Parabacteroides distasonis were detected as typical species in rats fed alginate and laminaran. The results indicate that the intake of soluble fermentable fibers in edible brown algae can alter the intestinal microbiota and its fermentation capacity.     

二苯甲酮类紫外吸收基聚硅氧烷的合成与应用性能研究

在铂催化剂的作用下,利用4-(β-羟基-γ-烯丙氧)丙氧基-2-羟基二苯甲酮MUV-O与含氢硅油PHMS在甲苯溶剂中的硅氢加成反应,合成了一种侧链携带有二苯甲酮类紫外吸收基团的聚硅氧烷PUVSi。对产物物化性能及其在织物整理中的应用性能进行了研究。结果表明,PUVSi的相对密度和折射率随着紫外吸收基团含量的增加而增大;相对分子质量分布变宽。用PUVSi整理所得织物柔软度提高,且随着PUVSi中紫外吸收基含量从0.045%增大至0.14%,弯曲刚度经纬总和从830mN增加至880mN;工作浴液的固含量从0.3%增至1.2%,织物的紫外光透过率从81%降至60%,而织物的弯曲刚度经纬总和则从266mN下降到234mN;将N-β-氨乙基-γ-氨丙基聚二甲基硅氧烷ASO-1和加入含氢量0·14%的PHMS所制成的PUVSi(PUVSi-1)复配,其整理织物柔软性强于单独使用PUVSi-1。乳化PUVSi时乳化剂T-55的用量(对PUVSi的质量分数)30%较为适宜。     

The effect of osmosis pretreatment on hot‐air drying and microwave drying characteristics of chili (Capsicum annuum L.) flesh

Chili flesh pretreated with or without osmotic dehydration (OD) was dried in the hot‐air drying (AD) oven at 50–80 °C or in the microwave drying (MD) oven at 60–180 W. Results showed that the samples osmotically treated in mixed solution (10% salt + 50% sucrose) had the best dehydration effect as compared with single salt or sugar solutions. During the drying process, osmotically treated samples had one falling‐rate period and their effective moisture diffusivities (D_eff) showed a rapidly linear increase with the decrease in moisture content, while directly drying samples showed a three‐phase falling‐rate period and their D_eff increased gradually at the initial period and then rapidly at the final period. When the moisture content decreased, the activation energy increased gradually; however, for AD after OD, it decreased. Among all the processes, MD at 60 W after OD presented the largest vitamin C retention rate and the best colour difference, needing less drying time.     

纳米TiO_2/β-CD光催化纸耐老化性能的研究

在紫外老化箱中对原纸表面涂覆不同比例的纳米TiO2/β-环糊精(β-CD)涂料的涂布纸进行抗紫外光返黄实验,并利用SEM和FT-IR等手段分析光照前后的纸张涂层结构和涂料成分。结果表明:经紫外光照30h后,涂布纸表面涂层稍有结块,而涂料成分没有发生明显变化;光照前后涂覆不同比例的纳米TiO2/β-CD涂料的涂布纸物理性能均优于涂布原纸,其中用含量为2%纳米TiO2和1%β-CD(均相对于涂料的质量分数)的涂料涂覆的涂布纸的物理性能和光学性能最好;用含量为3%纳米TiO2和1%β-CD的涂料涂覆的涂布纸不仅不能提高纸页的抗返黄能力,反而会加速其返黄进程。     

沙棘和银杏黄酮对沙棘油的抗氧化研究

以相同添加量（０．０２％ ）的槲皮素、沙棘黄酮、银杏黄酮、ＢＨＴ对沙棘油进行了抗氧化研究。结果表明,槲皮素、沙棘黄酮、银杏黄酮都可作沙棘油的抗氧化剂。     

桉木化学浆漂白废水污染负荷及其超滤处理特性的研究

对按木化学浆漂白废水的污染负荷及其超滤处理特性进行了研究。结果表明，ＣＥＨ三段漂白废水的主要污染来自Ｃ、Ｅ两段，占总负荷的８０％左右。用本试验的ＰＳ膜进行超滤处理后，漂白废水的ＢＯＤ５值达到国家二级排放标准，其余指标均达到一级排放标准。