液相合成法制备超微粒羟基磷灰石的研究

羟基磷灰石是人体和动物骨骼的主要无机成分,具有良好的生物活性和生物相容性,是极其重要的生物医学材料。介绍了液相合成法制备超微粒羟基磷灰石的研究动态,包括化学沉淀法、水热反应法、溶胶凝胶法、微乳液法,以及现代新技术在液相合成法制备超微粒羟基磷灰石中的应用研究。指出多种方法的交叉合理运用是制备超微粒羟基磷灰石发展的方向。     

基于颜色矢量角的彩色图像检索算法研究

通过分析利用颜色直方图进行图像检索时存在的问题,提出了一种基于图像边缘空间分布特征的图像检索算法.即利用颜色矢量角对亮度不敏感,对色度和饱和度敏感的特性来提取图像的边缘信息.在图像的边缘空间,提取图像边缘点的颜色矢量角直方图,以此来描述图像的内容.该算法充分利用了图像的颜色信息、边缘信息及形状信息,实验表明该算法具有较好的光照不变性、尺度不变性、平移不变性和旋转不变性.     

Prefrontal cortical projections to the hypothalamus in macaque monkeys

The organization of projections from the macaque orbital and medial prefrontal cortex (OMPFC) to the hypothalamus and related regions of the diencephalon and midbrain was studied with retrograde and anterograde tracing techniques. Almost all of the prefrontal cortical projections to the hypothalamus arise from areas within the "medial prefrontal network," as defined previously by Carmichael and Price ([1996] J. Comp. Neurol. 371:179-207). Outside of the OMPFC, only a few neurons in the temporal pole, anterior cingulate and insular cortex project to the hypothalamus. Axons from the OMPFC also innervate the basal forebrain, zona incerta, and ventral midbrain. Within the medial prefrontal network, different regions project to distinct parts of the hypothalamus. The medial wall areas 25 and 32 send the heaviest projections to the hypothalamus; axons from these areas are especially concentrated in the anterior hypothalamic area and the ventromedial hypothalamic nucleus. Orbital areas 13a, 12o, and Iai, which are related to the medial prefrontal network, selectively innervate the lateral hypothalamic area, especially its posterior part. The cellular regions of the paraventricular, supraoptic, suprachiasmatic, arcuate, and mammillary nuclei are conspicuously devoid of cortical axons, but many axons abut the borders of these nuclei and may contact dendrites that extend from them. Areas within the orbital prefrontal network on the posterior orbital surface and agranular insula send only weak projections to the posterior lateral hypothalamic area. The rostral orbital surface does not contribute to the cortico-hypothalamic projection.     

不同原始颗粒尺寸的PHE对PA66/PHE共混物力学性能影响

使用不同原始颗粒尺寸的聚酚氧(PHE)通过双螺杆挤出机分别与尼龙(PA)66共混制备PA66/PHE共混物.测试其力学性能,并用扫描电子显微镜(SEM)表征.研究发现,小颗粒尺寸的PHE制备的PA66/PHE共混物的分散相尺寸小、分散均匀且冲击强度得到提高,呈现协同效应,而拉伸强度基本与纯PA66保持一致;大颗粒尺寸的PHE制备的PA66/PHE共混物的分散相尺寸较大且容易发生团聚,其冲击强度降低,而拉伸强度有所增加.     

Texture and Structure Measurements and Analyses for Evaluation of Fish and Fillet Freshness Quality: A Review

Recently, food safety and quality have become critical issues of great concern throughout the world. Fish is one of the most vulnerable and perishable aquatic products. The evaluation of fish and fillet freshness is therefore very significant in research and development for providing premium and supreme quality for human health and acceptance by consumers, as well as for international trade. The texture and structure of fish muscle are important freshness quality attributes that depend on several parameters such as hardness, cohesiveness, springiness, chewiness, resilience, and adhesiveness, as well as the internal cross‐linking of connective tissue and the detachment of fibers. This review aims to present recent advances of texture and structure measurements and analyses, including sensory evaluation and instrumental methods, for indicating and evaluating fish freshness quality. Factors affecting these measurements are detailed and correlations between texture and structure are discussed. Moreover, the limitations and challenges of fish texture and structure measurements are described and some viewpoints about current work and future trends are also presented.     

Preparation of O‐carboxymethyl‐N‐trimethyl chitosan chloride and flocculation of the wastewater in sugar refinery

A novel water soluble amphiphilic O‐ carboxymethyl‐N‐trimethyl Chitosan chloride (CMTMC) was synthesized. The structure of this material was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹³C nuclear magnetic resonance (¹³C‐NMR) spectroscopy and X‐ray diffraction (XRD) techniques. The results showed that CMTMC had been successfully prepared. To determine the flocculation performance of the synthesized amphiphilic polymer, a comparison was made among Chitosan (CS), N‐trimethyl chitosan chloride (TMC), O‐carboxymethyl chitosan (CMC), and CMTMC on the turbidity and COD removal efficiency of 1% (v/v) wastewater in sugar refinery suspensions at pH 5.0, 7.0 and 9.0 at a dosage range of 0–8 mg/L. The results showed that the water soluble amphiphilic polymer CMTMC, which contains longer polymer anion and polymer cation, had the best performance not only in turbidity removal but also in COD removal on sugar refinery wastewater. The using of CMTMC as a flocculant to treat wastewater in sugar refinery was actually more effective than CS, CMC, and TMC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Volatile Profiles of Rapeseed Oil Flavored with Basil,Oregano, and Thyme as a Function of Flavoring Conditions

The flavoring of oils with herbs gives a specific taste and aroma to the oils and may increase their antimicrobial and antioxidant activity. The volatile aroma compounds in flavored rapeseed oil were studied as a function of flavoring conditions, by means of headspace solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) analysis. Rapeseed oils were flavored with dried basil, oregano, and thyme at two different concentrations (3 and 6%) and were heated at different temperatures and for various time intervals, followed by filtration. In the headspace of flavored oils, the main volatiles of the dried herbs were detected. In general, the share of monoterpenes in the headspace of flavored oil was higher than in the original dried herbs, while sesquiterpenes and phenolic compounds were detected to a considerably lower extent in the oil than in the herbs. The concentrations of the volatiles detected in the oil increased with increasing heating time and temperature.     

Applied Voltage and Near‐Infrared Light Enable Healing of Superhydrophobicity Loss Caused by Severe Scratches in Conductive Superhydrophobic Films

The fabrication of self‐healing/healable superhydrophobic films that can conveniently and repeatedly restore the loss of superhydrophobicity caused by severe mechanical damage, such as deep and wide surface scratches, remains challenging. In the present work, conductive superhydrophobic films that are healable by means of an applied voltage or near infrared (NIR) light irradiation are fabricated by depositing a layer of Ag nanoparticles and Ag nanowires (AgNPs‐AgNWs) on a thermally healable polycaprolactone (PCL)/poly(vinyl alcohol) (PVA) composite film, followed by the deposition of 1H,1H,2H,2H‐perfluorodecanethiol. The AgNPs‐AgNWs layer not only provides micro‐ and nanoscaled hierarchical structures in support of superhydrophobicity but also serves as an electrothermal or photothermal heater to enable healing of the underlying PCL/PVA film under the assistance of a low applied voltage or low‐power NIR light irradiation. Because of the strong adhesion between the PCL/PVA film and the AgNPs‐AgNWs layer, the healability of the PCL/PVA film is successfully conveyed to the conductive superhydrophobic layer, which can rapidly and repeatedly restore the loss of superhydrophobicity caused by cuts several hundreds of micrometers wide. The combined electrothermal and superhydrophobic properties endow the healable conductive superhydrophobic films with improved durability and usefulness as self‐cleaning, antiicing, and snow‐removing surfaces.     

激光标刻、电解标刻对GH4169疲劳性能的影响

对GH4169合金进行激光标刻和电解标刻处理,研究了两种标刻工艺后GH4169合金的高周疲劳性能及其断裂机理。结果表明,激光标刻、电解标刻后试样的抗拉强度下降幅度很小,几乎不影响合金的抗拉强度,与未标刻的GH4169合金疲劳寿命相比,激光标刻后合金疲劳寿命下降19.2%,电解标刻后疲劳寿命下降16.0%。从标刻截面处观察发现激光标刻后的形貌较为尖锐,电解标刻的陷坑形貌较为圆滑。通过观察裂纹源区形貌发现未标刻试样裂纹从合金表面处萌生,激光标刻试样缺口处产生了高应力集中,加快了裂纹的萌生速率。电解标刻位置存在呈灰暗色的化学蚀刻层,进而引起裂纹的萌生和扩展,综合比较下航空用电解标刻工艺所标刻的试样比激光标刻工艺疲劳性能更优。     

Electrical Current Signatures of DNA Base Modifications in Single Molecules Immobilized in the α-Hemolysin Ion Channel

Nanopore technology holds high potential for next-generation DNA sequencing. This method operates by drawing an individual single-stranded DNA molecule through a nanoscale pore, while monitoring the current deflections that occur as the DNA passes through. Individual current levels for the four DNA nucleotides have been established by immobilization of an end biotinylated strand in the pore, in which the nucleotide of interest is suspended at the most sensitive region of the ion channel. Due to the inherent reactivity of DNA bases, many modified nucleotides in the genome exist as a result of oxidative and UV insults, among others. Herein, the current levels for common DNA damage lesions 8-oxo-7,8-dihydroguanine, spiroiminodihydantoin, guanidinohydantoin, uridine, abasic sites, thymine dimers, thymine glycol, and 5-iodocytosine were assessed through immobilization experiments. In some cases, the current difference between the damaged and canonical nucleotides was not well resolved; therefore, we took advantage of the chemical reactivity of the new functional groups present to make amine adducts that shifted the current levels outside the range of the native nucleotides. Among the adducts studied, only the 2-aminomethyl-18-crown-6 adduct was able to give a large current shift in the immobilization experiment, as well as being observed in a translocation experiment. The results show potential in providing current-level modulators for identification of some types of DNA damage. In principle, any DNA base modification that can be converted chemically or enzymatically into an abasic site could be identified in this way.