应用聚甲基丙烯酸甲酯制作兔肾小球铸型

目的:探索采用聚甲基丙烯酸甲酯填充剂进行兔肾小球铸型的效果。方法:胸主动脉插管,应用聚甲基丙烯酸甲酯填充剂灌注肾动脉。结果:肾动脉及其大分支血管饱满,连续性好,肾小球肉眼可见,光镜下呈黑色球状,可见肾入球及出球小动脉,扫描电镜示肾小球内部毛细血管网及其次级分支,血管线形流畅,表面光滑。结论:采用聚甲基丙烯酸甲酯作为肾小球铸型填充剂,肾小球显示清晰、完整,能达到预期效果。     

Synthesis,Characterization, and Polymerization Kinetics of Novel Ladder‐Like Polysilsesquioxanes Containing Side‐Chain Propyl Methacrylate Groups

Three ladder‐like polysilsesquioxanes containing side‐chain propyl methacrylate groups have been synthesized successfully by stepwise coupling polymerization. The prepared ladder‐like polymers are polysilsesquioxanes containing 100 mol‐% propyl methacrylate side groups and two copolymers containing 70 mol‐% methyl or phenyl groups and 30 mol‐% propyl methacrylate side groups. They were characterized by FT‐IR, ¹H NMR, proton‐decoupled ¹³C NMR, and ²⁹Si NMR spectroscopies, gel‐permeation chromatography (GPC), wide‐angle X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and thermo‐gravimetric analysis (TGA). Characterization data indicate that these polymers have ordered ladder‐like structures with possible defects. At appropriate conditions, crystals of homopolymer were grown and are in the shape of a parallelogram. All three polymers were cured by 2,2′‐azoisobutyronitrile (1% w/w) and the kinetics for the bulk polymerization of these polysilsesquioxanes was followed by dynamic DSC method. Ozawa and Kissinger methods were used to calculate the activation energy for curing. Both the frequency factor and the activation energy of the homopolymer were found to be higher than the copolymers. Cured samples had a higher thermal stability than uncured samples.

Chemical structure of LPS.     

Polymerization of Methyl Methacrylate with Chloro Zirconocene Enolates

Summary: The polymerization of methyl methacrylate (MMA) in the presence of the neutral chloro zirconocene enolates, Cp₂ZrCl[OC(OMe)?CMe₂] ( 1 ), Me₄C₂(Cp)₂ZrCl[OC(OMe)?CMe₂] ( 2 ), and Me₂C(Cp)₂ZrCl[OC(OMe)?CMe₂] ( 3 ), was investigated. None of these compounds is catalytically active on its own. They could be activated by adding Ph₃CB(C₆F₅)₄ ( 4 ); however, only if the initial concentration of enolate is higher than that of the perfluorated phenyl borate. Polymers were produced with a number average molar mass of up to 100 000 g/mol and a dispersion index of 1.1–1.3 with mixtures comprising 1 and 4 or 2 and 4 . The degree of polymerization depends only on the quantity of excess enolate and not on the absolute concentration of the initiator components. In contrast, a mixture of 3 and 4 was not very active. Kinetic modeling of the systems as well as NMR spectroscopic investigations indicate that a bimetallic mechanism can describe chain growth. The activity of these catalytic systems depends on the structure of the ligand. The two zirconocenes with bridged cyclopentadienyl ligands, ( 2 ) and ( 3 ), convert MMA considerably slower. In addition to the methyl zirconocene enolates with unbridged cyclopentadienyl ligands, the corresponding chloro zirconocene enolates are also suitable for the polymerization of MMA. The latter compounds offer the advantage that preparations for the production of the initiators are comparatively simple.

Structures of investigated initiators.     

ATRP of Allyl Methacrylate with Alkyl Methacrylates – Crosslinking of Poly(methacrylate)s with Allyl Ester Side Groups

Summary: Random copolymers of methyl methacrylate (MMA), butyl methacrylate (BMA) and allyl methacrylate (AMA) were prepared via atom transfer radical polymerization (ATRP). AMA is a bifunctional monomer with two double bonds of different reactivity: a highly reactive methacrylate double bond and an allyl ester double bond of lower reactivity. In order to obtain linear polymers with pendant allyl ester groups, the copolymerization conditions have to be optimized with respect to the concentration of AMA, the catalyst system applied – especially the ligand – and the temperature. By means of kinetic studies the reaction parameters for a controlled polymerization were determined. The results obtained show that the higher the temperature and the amount of AMA is the higher is the probability of irregular chain growth and side reactions induced by the pendant allyl ester groups such as hydrogen abstraction from the allyl position or radical addition to the allyl ester double bond. The random copolymers were photochemically crosslinked by using 2,2‐dimethoxy‐2‐phenylacetophenone as photoinitiator. The thermal properties of linear and crosslinked polymers were determined. The glass transition temperatures of both show no significant difference at low AMA content and thus low crosslinking densities.

GPC eluograms of MMA/BMA (70:30) copolymers with 5 mol‐% AMA at different conversions.     

Biochemical characteristics and water exchange in the surface layer of human joint cartilage

We compared the contents of collagen, glycosaminoglycans, and various forms of water in the surface layer and whole tissue of joint cartilages of different localization. It was found that the surface layer is characterized by reduced content of glycosaminoglycans compared to the whole tissue and higher water-holding capacity due high content of bound water.     

Reactive Compatibilization of PA6/LDPE Blends with Glycidyl Methacrylate Functionalized Polyolefins

Summary: Blends of polyamide‐6 (PA6) and low density polyethylene (LDPE) were compatibilized by melt mixing with various polyolefins functionalized with glycidyl methacrylate (GMA), i.e., GMA grafted LDPE (LDPE‐g‐GMA), GMA grafted styrene‐ethylene/butylene‐styrene block copolymer (SEBS‐g‐GMA) and ethylene‐co‐glycidyl methacrylate copolymer (E‐GMA). Blends with PA6/LDPE composition ratios of 25/75 and 75/25 wt.‐%/wt.‐% were prepared in a Brabender internal mixer and their properties were evaluated by SEM, rheological measurements and DSC. Morphological investigation by SEM showed a neat improvement of phase dispersion and interfacial adhesion in all compatibilized blends when compared to PA6/LDPE binary blends. The variation of the dispersed phase size was analyzed as a function of blend composition, compatibilizer concentration and GMA content. The emulsification curves of compatibilized blends showed that the equilibrium size of dispersed particles at the saturation concentration of copolymer was lower when PA6 was the major component. The finest dispersion of the LDPE phase (<0.25 μm) was observed in the presence of SEBS‐g‐GMA copolymer. LDPE‐g‐GMA and E‐GMA displayed a similar compatibilizing efficiency. In all cases, the blends with a polyamide matrix presented a marked rise in torque and melt viscosity with increasing compatibilizer content. These effects were accounted for by a reaction between the epoxide groups of LDPE‐g‐GMA and the carboxyl/amine end‐groups of PA6, leading to the formation of an interchain graft copolymer. The phase transition processes of PA6 in the blends were influenced by the compatibilizer content and the interfacial interactions between the polymer components, suggesting a different role for the compatibilizer at the PA6/LDPE interface.

SEM micrograph of PA6/LDPE 25/75 blend compatibilized with 2.5 phr SEBS‐g‐GMA.     

Energy Consumption for the Desalination of Salt Water Using Polyelectrolyte Hydrogels as the Separation Agent

The energy consumption for a novel desalination approach using charged hydrogels under externally applied pressure is experimentally measured and calculated. The salt separation is based on a partial rejection of mobile salt ions caused by the fixed charges inside the polyelectrolyte network. Self‐synthesized and commercial poly(acrylic acid) hydrogels are used to study the desalination performance in reference to sodium chloride solutions within the concentration range of 0.1–35 g L⁻¹. The influence of various synthetic parameters, such as the degree of crosslinking (DC) and the size and shape of the particles, is investigated. Furthermore, the effect of process parameters including the amount of the feed solution, the applied pressure profile, and the swelling time of the hydrogel is discussed. The best energy estimation found so far, is 8.9 kWh m⁻³ fresh water if a poly(acrylic acid) with a DC of 5 mol% is used in an infinite large salt bath.     

更年期综合征妇女心理健康状况分析

目的 探讨更年期综合征妇女心理健康状况.方法 用Kupperman改良评分表、SCL-90对158例年龄在45～55岁之间的妇女进行调查,并将Kupperman改良评分大于或等于14分者定为更年期综合征组即研究组,小于或等于13分者定为对照组.结果 研究组(56例)SCL-90中9个因子均分均高于对照组(102例)(P＜0.01);与国内常模相比,研究组躯体化、抑郁、焦虑及恐怖4个因子分较高,有显著性差异(P＜0.01或P＜0.05).结论 更年期综合征症状明显的妇女心理健康状况差,应引起临床医生的高度重视.     

阻塞性睡眠呼吸暂停综合征的情绪状况

目的 探讨阻塞性睡眠呼吸暂停综合征（OSAS）患者情绪状况的改变。方法 对63例疑诊OSAS的患者行全夜多导睡眠图（PSG）检查，根据呼吸暂停低通气指数（AHI）分为OSAS组和对照组，对其进行抑郁和焦虑症状评定，比较两组中各指标的差异性。结果 OSAS患者SAS、SDS得分均升高。OSAS患者抑郁和焦虑的发生率分别为44．2％和32．6％，明显高于对照组，以抑郁尤为明显。结论 OSAS患者存在明显情绪障碍。     

Kinetic and Copolymer Composition Investigations of the Free Radical Copolymerization of 1‐Octene with Glycidyl Methacrylate

Kinetic and copolymer composition investigations of the free radical copolymerization of 1‐octene with glycidyl methacrylate are reported. The chemical structure of the obtained copolymers is elucidated by ¹H, ¹³C, heteronuclear single quantum coherence nuclear magnetic resonance (NMR) and infrared spectroscopies. ¹H NMR measurements indicate that a maximum statistical incorporation of 1‐octene in the copolymer chain of 32 mol% is obtained when 90 mol% of this comonomer is used in the initial monomer feed of the copolymerization reaction. Furthermore, the reactivity ratios of this comonomer system are estimated using the obtained experimental data, which are fitted to the integral form of the copolymerization equation utilizing a nonlinear least squares approach. To the best of knowledge, this is the first report on the reactivity ratios of this specific comonomer system. To evaluate the potential of the obtained materials as dispersants, the effect of the polymer concentration on the dispersion of copper nanopowders in organic solvents is studied for a copolymer with a 1‐octene composition of 25 mol%.     

Two Cationic Copper(I) Catalysts with N‐Donor Ligands for the Polymerization of Methyl Methacrylate

Two new copper(I) complexes, [Cu(bdmpm)₂](PF₆) ( 1 ) [bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)methane (bdmpm)] and [Cu(µ‐bdmpp)(MeCN)]₂(PF₆)₂ ( 2 ) [2,6‐bis(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)pyridine (bdmpp)], were prepared by reactions of [Cu(MeCN)₄](PF₆) with bdmpm or bdmpp in MeCN. X‐ray analysis revealed that 1 is a mononuclear complex with the central Cu being chelated by two bdmpm ligands. 2 has a double‐stranded helicate structure in which each of the two [Cu(µ‐bdmpp)(MeCN)]⁺ cations is linked by the other bdmpp ligand. Both 1 and 2 exhibited high catalytic activity in the polymerization of methyl methacrylate (MMA). Even though the ratio of MMA to catalyst was raised up to 1 000:1, the PDI for 1 (reaction time was fixed at 5 h) is below 1.6 and the conversion is up to 66.0% while that for 2 (reaction time was fixed at 6 h) is below 1.5 and the conversion is up to 75.2%. In addition, the effects of solvents, reaction temperatures as well as ratios of MMA to catalyst were also investigated.

     

Surface Photografting Polymerization of Methyl Methacrylate in N,N‐dimethylformamide on Low Density Polyethylene Film

Summary: It was found that without additional photoinitiator, methyl methacrylate (MMA) dissolved in common solvent N,N‐dimethylformamide (DMF) could be photografted steadily on low‐density polyethylene (LDPE) film surface under UV irradiation. In short irradiation time (4 min) and at room temperature, high grafting efficiency (approaching 100%) and remarkable graft polymer amount (grafting percent is about 4.6%) was obtained. The possible reaction mechanism was based on the photosensitivity of DMF, which induced this photografting polymerization. This finding is useful to develop photoinitiator‐free grafting or photopolymerization system. Using SEM, special discrete globular structure was found on the MMA‐grafted LDPE film surface, and a possible model was proposed to interpret it.

     

Hydrolytic Stability of Methacrylamide and Methacrylate in Gelatin Methacryloyl and Decoupling of Gelatin Methacrylamide from Gelatin Methacryloyl through Hydrolysis

Gelatin methacryloyl (GelMA; GM) is a promising nature‐derived photocurable material that can mimic the extracellular matrix because GelMA features tailorable mechanical properties, proteolytic degradation, and good cell adhesion. GelMA contains not only methacrylamide but also methacrylate. However, the hydrolytic stability of methacrylamide and methacrylate groups of GelMA in aqueous solutions has not been scrutinized. Here, the structural change of GelMA through hydrolysis is investigated for the first time. The structural change of hydrolyzed GelMA is quantitatively identified using colorimetric and ¹H NMR methods. The methacrylate groups decompose markedly at high pH solutions, but the methacrylamide groups remain stable. Further, pure gelatin methacrylamide is successfully decoupled from GelMA for a better understanding of GelMA structure and future use for biomedical applications.     

ATRP of Methyl Methacrylate in the Presence of Ionic Liquids with Ferrous and Cuprous Anions

The atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was studied in the presence of ionic liquids possessing a range of counterions. Iron mediated ATRP can be carried out in the absence of added organic ligands in the presence of ionic liquids. However, copper mediated ATRP of MMA requires the presence of an added organic ligand when the ionic liquid has a halide or a carbonate anion, but not with a phosphonate anion. The ionic liquids containing transition metal salts can readily be separated from the polymerization media and regeneration of the catalyst in the ionic liquids has been successful.     

Propagation and Termination Kinetics of Poly(Ethylene Glycol) Methyl Ether Methacrylate in Aqueous Solution

The propagation rate coefficient, k_p, of poly(ethylene glycol) methyl ether methacrylate (M_n ≈500 g mol^?1) has been measured via pulsed‐laser polymerization (PLP)–size‐exclusion‐chromatography in aqueous solution between 5 wt% monomer and bulk polymerization at temperatures from 22 to 77 °C. k_p increases significantly toward higher water content, as is observed for other water‐soluble monomers. This entropy‐motivated effect enhances the pre‐exponential. The activation energy, E_A(k_p), is more or less identical to the characteristic value of methacrylates. The chain‐length‐dependent rate coefficient, k_t^i,i, for termination of two radicals of chain length i has been investigated at low degrees of monomer conversion via the single‐pulse–PLP–electron paramagnetic resonance technique. k_t^i,i turned out to be adequately represented by the composite model designed by the Russell group. The power‐law exponents for the chain‐length dependence of small and long radicals are close to the numbers reported for other monomers. The rate coefficient for termination of two radicals of chain length unity scales with the fluidity of the reaction mixture. Viscosity measurements prior to polymerization thus enable estimates of termination rate.

     

The Influence of Hydrogen Bonding on the Propagation Rate Coefficient in Free‐Radical Polymerizations of Hydroxypropyl Methacrylate

The propagation rate coefficient k_p was determined for hydroxypropyl methacrylate by applying pulsed laser initiated polymerizations and subsequent analysis of the polymer by size‐exclusion chromatography. k_p data were derived for polymerizations in bulk and in several solvents: toluene, tetrahydrofuran (THF), benzyl alcohol, and supercritical CO₂. With the exception of THF, no solvent influence on k_p was observed. For polymerizations in THF k_p values 40% below the corresponding bulk data were obtained. In addition, the activation energy of k_p for polymerizations in THF is higher than for the other systems. The results are explained by a complexation of the OH group contained in the ester group with THF. As a consequence, H bonds between OH groups and carbonyl O atoms, which occur in the other systems, are not formed in the presence of THF. This explanation is supported by Raman spectra, which show that association of carbonyl groups does not occur for systems containing THF, whereas for all other systems the occurrence of two peaks at 1 703 cm^?1 and 1 720 cm^?1 is indicative of the vibrations of two different – associated vs. not associated – types of carbonyl groups. Based on the change in activation energy it is suggested that a true kinetic solvent effect occurs.

Temperature dependence of k_p for HPMA polymerizations in bulk and in solution of THF. The literature data for bulk polymerizations are taken from ref. 22 . Open symbols refer to ν_rep = 10 Hz and filled symbols to ν_rep = 25 Hz.     

Modification of Brain Processing Techniques: Tissue Embedding in Glycol Methacrylate and Stain Modifications

Abstract

Increased interest in quantitation of the histopathological changes in a variety of neurological disorders (including neurodegenerative disease such as Alzheimer's disease) continues in an attempt to develop specific clinical-histopathological correlations. Most previous efforts at quantitation have used paraffin embedded sections of brain tissue, although plastic embedded sections have recently become a preferable alternative because they provide greatly reduced tissue shrinkage and distortion during processing, and greater clarity and improved resolution to the tissue sections. We have developed techniques for glycol methacrylate embedding and sectioning of brain tissue blocks on a standard histology laboratory microtome. In addition, we have modified routine diagnostic and investigational neurohistological stains for use in glycol methacrylate embedded brain sections, including hematoxylin and eosin, modified Bielschowsky stain, Jamarri silver technique, Einarson's Nissl stain, gallocyanin-Darrow red myelin stain, and the thioflavine-S-hematoxylin stain. The use of plastic embedded sections with appropriate stains will permit critical histopathological evaluation of nervous system tissue from patients with a variety of neurological disorders. (J Histotechnol 12:201, 1989)     

Effect of LiClO4 and LiCl Additives on the Kinetics of Anionic Polymerization of Methyl Methacrylate in Toluene‐Tetrahydrofuran Mixed Solvent

The kinetics of anionic polymerization of MMA has been studied at ?78 °C in toluene‐THF (9:1 v/v) using 1,1′‐diphenylhexyl lithium as initiator in the presence of lithium perchlorate and lithium chloride as Lewis acid additives. The control of the polymerization is lost in the absence of additives as evident from the non‐linear first‐order time‐conversion plot and polymers with broad multimodal molecular weight distribution. The presence of LiClO₄ and LiCl in 10:1 and 5:1 ratio, respectively, over the initiator brings about sufficient control, yielding polymers of narrow unimodal distribution throughout the polymerization. The reaction in the presence of the additives follows first‐order kinetics free of termination and transfer. Moreover, the order with respect to the active centers is found to be almost unity, which signifies a probable disaggregation of ion‐pairs to a single complexed propagating species.

GPC elugrams at different conversions for MMA polymerization in the presence of LiClO₄.     

Concurrent Initiation by Air in the Atom Transfer Radical Polymerization of Methyl Methacrylate

The effect of air in atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was studied. Air initiated polymerization was clearly noticed by the appearance of a low molecular weight peak in the synthesis of high molecular weight poly(isobutylene)‐graft‐poly(methyl methacrylate) (M _n = 5.0 × 10⁵ g/mol). The concentration of chains initiated by oxygen (air) was ≈8 × 10^?4 mol/L, determined using the Gladstone‐Dale relationship. The tentatively proposed mechanism for air initiated polymerization was supported by kinetic studies. Similar to typical ATRP systems, the rate of air initiated polymerization increased with temperature, [MMA], amount of air, and activity of the catalyst complex. Polymers with lower polydispersities (M _w/M _n = 1.13) were obtained in the presence of Cu(II) as compared to Cu(I) catalyst complex system.

Kinetic plots for the air initiated bulk polymerization of MMA at (?) 20 °C, (?) 50 °C, and (?) 90 °C.     

Qualitative and quantitative ultrashort‐TE MRI of cortical bone

Osteoporosis causes over 1.5 million fractures per year, costing about $15 billion annually in the USA. Current guidelines utilize bone mineral density (BMD) to assess fracture risk; however, BMD alone only accounts for 30–50% of fractures. The other two major components of bone, organic matrix and water, contribute significantly to bone mechanical properties, but cannot be assessed with conventional imaging techniques in spite of the fact that they make up about 57% of cortical bone by volume. Conventional clinical MRI usually detects signals from water in tissues without difficulty, but cannot detect the water bound to the organic matrix, or the free water in the microscopic pores of the Haversian and the lacunar‐canalicular system of cortical bone, because of their very short apparent transverse relaxation times (T₂*). In recent years, a new class of sequences, ultrashort‐TE (UTE) sequences, with nominal TEs of less than 100 µs, which are much shorter than the TEs available with conventional sequences, have received increasing interest. These sequences can detect water signals from within cortical bone and provide an opportunity to study disease of this tissue in a new way. This review summarizes the recent developments in qualitative UTE imaging (techniques and contrast mechanisms to produce bone images with high contrast) and quantitative UTE imaging (techniques to quantify the MR properties, including T₁, T₂* and the magnetization transfer ratio, and tissue properties, including bone perfusion, as well as total, bound and free water content) of cortical bone in vitro and in vivo. The limitations of the current techniques for clinical applications and future directions are also discussed. Copyright © 2012 John Wiley & Sons, Ltd.