A New Approach to Morphology Studies on Diacrylate Polymer Networks Using X‐Ray Powder Diffraction

X‐ray powder diffraction (XRPD) and Fourier transform infrared (FTIR) spectroscopy are used to characterize the morphology of diacrylate polymer networks, obtained by photoinduced homo‐ and copolymerizations. XRPD reveals the presence of three sized groups of microgel agglomerates. The dimensions of the microgel agglomerates (D) and the degree of conversion (DC) are explained by the monomer chemical structure, the strength of hydrogen bonds, and relate to selected polymer mechanical properties. The D value increases and the DC decreases as the strength of the hydrogen bonds increases. Copolymerization with monomers lacking groups forming strong hydrogen bonds results in more homogeneous networks with improved mechanical properties.

     

Dithieno[3,2‐b:2′,3′‐d]pyrrole and Benzothiadiazole‐Based Semicrystalline Copolymer for Photovoltaic Devices with Indene‐C60 Bisadduct

A semicrystalline low‐bandgap polymer (PDTPBT) based on alternating dithienopyrrole and benzothiadiazole moieties as a pair of the indene‐C₆₀ bisadduct (ICBA) for polymeric solar cells is reported. The lowest unoccupied molecular orbital (LUMO) level of PDTPBT is measured to be ?3.47 eV, ensuring sufficient energy offset for photoinduced charge transfer to ICBA. Photovoltaic cells are fabricated with ICBA and [6,6]‐phenyl‐C₇₁‐butyric acid methyl ester (PC₇₁BM) as an acceptor. By replacing PC₇₁BM with ICBA, the open‐circuit voltage is increased by 0.23 V and the resulting power conversion efficiency is improved from 1.17% to 1.71%. To optimize the ICBA‐based devices, crystalline low‐bandgap structures should be designed carefully as a pair of ICBA by considering the energy‐level offset for charge separation and crystalline interchain ordering, for minimizing the intercalated ICBAs inside the polymer domain.

     

Determination of Poly(4,4′‐diphenylsulfonyl terephthalamide) Crystalline Structure Via WAXD and Molecular Simulations

The crystal structure of poly(4,4′‐diphenylsulfonyl terephthalamide) (pt‐PSA) is studied by X‐ray diffraction and molecular simulation. Although the number of observed reflections is limited to warrant a precise determination of the unit cell structure and symmetry, a reasonable monoclinic unit cell is suggested with dimensions of a = 0.645 nm, b = 0.488 nm, c = 3.010 nm, and γ = 122.5°. A twofold molecule with two monomeric units forming a large zigzag conformation satisfies the X‐ray diffraction data. A layer structure is formed in the crystal phase, which is stabilized by the hydrogen bond between ? NH and ? C?O and the parallel‐displaced π–π stacking from the distortional coplanarity of the benzene rings and amide group.

     

Bone Demineralization With Citric Acid Enhances Adhesion and Spreading of Preosteoblasts

Background: Previous studies have demonstrated that bone demineralization can improve consolidation in bone grafts. The biologic mechanisms underlying this phenomenon remain unclear. Methods: Twelve adult male guinea pigs were used in this experiment. Forty‐five bone samples removed from the calvaria of nine animals were divided in groups (n = 9) according to the time of demineralization with citric acid (50%, pH 1): 15, 30, 90, and 180 seconds and non‐demineralized samples (control). Preosteoblasts (MC3T3‐E1) were cultured on the bone samples for 24, 48, and 72 hours (n = 3). Fifteen samples removed from the remaining three animals were analyzed by scanning electron microcopy/energy dispersive spectrometry (SEM/EDS) after demineralization (n = 3). Results: The number of preosteoblasts increased significantly with time in all groups. The bone surface area covered by these cells increased with time, except in the control group. Intragroup differences occurred between 24 and 72 hours (P <0.05). Samples demineralized for 30 seconds showed greater area covered by preosteoblast cells than for the other times of demineralization in all periods of cell culture (P <0.05) without a statistically significant difference compared with 15 seconds. SEM/EDS showed diminished content of calcium (Ca) after 15 seconds of demineralization, but the Ca content increased after 180 seconds of demineralization (P <0.05). The phosphorus (P) amount increased significantly only after 30 seconds of demineralization (P <0.5). The sulfur (S) content was increased in demineralized samples in relation to non‐demineralized ones, reaching the highest level after 90 seconds, when the difference became significant in relation to all the other times of demineralization (P <0.05). Magnesium (Mg) content did not differ significantly between demineralized and non‐demineralized samples. Conclusions: Bone surfaces demineralized for 30 seconds increased the spreading of preosteoblasts as well as the surface area covered by these cells. Bone demineralization deserves to be studied in periodontal and maxillofacial regenerative procedures.     

C形臂X光机急性扫描诱导的生物效应研究

目的 探讨研究C形臂X光机急性扫描对小鼠机体功能的影响.方法 健康雄性BALB/c小鼠60只随机分为对照组、单次、四次、八次和十二次扫描组,每组12只.对照组小鼠不扫描,其余组用C形臂X光机对小鼠进行全身扫描.在照射后24小时,采用生物化学方法检测小鼠甲状腺组织中超氧化物歧化酶（SOD）和丙二醛（MDA）的水平;采用酶联免疫吸附试验（ELISA）检测血清中IL-4和IFN-γ的变化;流式细胞仪检测各照射组小鼠外周血淋巴细胞和骨髓细胞的凋亡水平.结果 与对照组比较,小鼠甲状腺组织中的MDA水平在八次以上扫描后分别升高了2.39、3.49倍（P＜0.05）,而SOD水平在四次以上扫描后分别降低了19.23％、25.80％和27.95％ （P ＜0.05）;血清IFN-γ和IL-4水平在四次以上扫描后分别降低了14.71％和22.60％、22.99％和44.05％、31.70％和44.43％ （P＜0.05）,但均未影响IFN-γ/IL-4值（P＞0.05）;小鼠外周血淋巴细胞的凋亡水平在八次以上扫描后分别增加了1.68、2.40倍（P＜0.05）,骨髓细胞的凋亡水平在十二次扫描后增加了2.02倍（P＜0.05）.结论 C形臂X光机多次扫描改变了机体的氧化水平和免疫学相关指标.另外,机体通过启动凋亡来维持基因组稳定性.     

The Gallbladder of the Electric Ray Torpedo Marmorata Risso Displays Excrescent Cholecystocytes with Merocrine and Apocrine‐Like Secretions

The gallbladder of Torpedo marmorata exhibits a mucosal surface layer of simple columnar epithelium with very tall cholecystocytes. The apical domain of each cell has few microvilli, but many mucous vesicles that are secreted by exocytosis at the cell apices. The apical regions may also elongate and undergo self‐excision while shedding mucus and cell debris into the gallbladder lumen in a manner similar to that described in mammals as a result of sex steroid treatment to induce gallstones and to that found in the cholecystitis associated with cholelithiasis. Numerous small mitochondria, spherical to elongated, are distributed throughout the cells, while the nuclei are often located in the lower third of each cell. In the lower part of the cholecystocytes, large and very densely contrasted lysosomes can be found. All cells are tightly joined by junctional complexes, including long, highly contrasted desmosomes. The fibromuscular layer is made of a loose stroma with a limited muscular component and a poor blood supply. Large diameter blood vessels can only be found in the subserosal layer. It is hypothesized that the obligatorily carnivorous diet of this ureotelic fish has resulted in the evolution of a gallbladder ultrastructure resembling that found in cholecystitis but without the associated cholelithiasis. Anat Rec, 2013. © 2012 Wiley Periodicals, Inc.     

Low-dose hepatic computed tomography perfusion imaging and its preliminary study

OBJECTIVE: Computed tomography perfusion imaging (CTPI) is a rapid and non‐invasive functional imaging method that reflects hemodynamic changes of liver diseases. However, its large radiation dosage limits its clinical application. We aimed to evaluate the feasibility of low‐dose CTPI in normal liver and its preliminary application in hepatocellular carcinoma (HCC). METHODS: CTPI was performed in 34 healthy volunteers randomly divided into three groups with different applications of tube current, including a conventional dose group, a median‐dose group and a low‐dose group. The perfusion parameters of each group were compared and a low‐dose CTPI was performed in 13 patients with HCC. RESULTS: Relatively satisfying images and perfusion parameters of liver CTPI were acquired with the different tube currents. There were no significant differences between the parameters of the three groups (P > 0.05). The effective dosage of conventional, median and low‐dose liver CTPI were 19.62 mSv, 12.61 mSv, and 7.01 mSv, respectively. The radiation dosage of low‐dose liver CTPI was reduced to 64.27% compared with that of the conventional group. The hepatic blood flow, hepatic blood volume and hepatic perfusion index of HCC were higher than background liver parenchyma and normal liver. CONCLUSIONS: Low‐dose liver CTPI obtained similar perfusion parameters result to that of the conventional‐dose, whereas the radiation dosage was reduced by 2/3. Low‐dose liver CTPI can reflect the hemodynamic change of HCC. Low‐dose liver CTPI has potential clinical value for diagnosis and differential diagnosis of liver diseases.     

Effects of different sterilization methods on surface characteristics and biofilm formation on zirconia in vitro

Objective

The current laboratory study was to investigate the effect of different sterilization treatments on surface characteristics of zirconia, and biofilm formation on zirconia surface after exposure to these sterilization treatments.

电子束CT检测犬心肌梗死及计算机后处理研究

目的：评价电子束CT（EBCT）显示急性心肌梗死的能力和限制及计算机后处理对其的影响。方法：将6只犬制成心肌梗死模型后，1．5，6，12，20h作EBCT增强扫描，然后处死犬，作心脏标本大块病理切片，硝基蓝四唑（NBT）染色前，后拍照，然后再采集光镜标本，将EBCT图像和病理切片照片输入计算机进行处理，计算心肌梗死面积并进行对照分析，结果：EBCT图像上急性心肌梗死的部位及形态显示清晰，随着结扎时间的延长，心肌梗死的体积略有缩小，最后一次EBCT扫描图像所显示的梗死区大小与染色结果相仿，相关系数为0．994（P＜0．001），结论：EBCT可对急性心肌梗死的部位，形态与大小做出准确的评价，计算机后处理 病变大小分析的准确性。