路已断 梦未醒?——关于“小产权房”现象的深层次思考

近两年热兴的"小产权房"是城市违法建设的一种特殊形式。对待"小产权房"是否也能像对待传统违法建设一样,一拆了事,是一个还需仔细斟酌的问题。本文从重庆市一处"小产权房"的具体案例入手,分析了"小产权房"究竟如何违法,剖析了上层政府对"小产权房"持坚决的否定态度、而农民却对此十分热衷的深层次原因,提出了对待"小产权房"所应该采取的正确态度,指出解决"小产权房"的根本出路在于在规范建设的同时又保护好农民利益,而其中的关键在于如何让土地收益成为农民财产性收入的重要组成部分。     

直面旧工业区“未合法”工业用地的改造困境——以深圳为例

如何对大量"未合法"工业用地进行改造,成为深圳无法回避的问题。本文通过"未合法"工业用地基本特征和改造困境的分析,展望其模糊产权和土地发展权的演进趋势。结合深圳城市更新相关政策制度,对"未合法"工业用地改造规划进行新的定位,建议将其作为土地管理制度改革的试点、城市二次开发的创新模式、法定图则动态的实施细则。并从保证股份公司产权边界完整、分类落实土地权属信息、空间量化改造意愿等方面,提出相关改造规划的编制建议。     

108 m3聚合釜引发剂用量及加入技术对树脂质量的影响

引发剂是调节氯乙烯悬浮聚合反应速率,并影响聚合放热、聚合周期和聚合釜生产能力的重要助剂。引发剂对氯乙烯悬浮聚合动力学的影响主要与引发剂的活性、用量有关。引发剂用量、加入方式和前后期使用比例等对树脂质量也有明显的影响。     

Synthetic Activity of Recombinant Whole Cell Biocatalysts Containing 2-Deoxy-D-ribose-5-phosphate Aldolase from Pectobacterium atrosepticum

In nature 2-deoxy-D-ribose-5-phosphate aldolase (DERA) catalyses the reversible formation of 2-deoxyribose 5-phosphate from D-glyceraldehyde 3-phosphate and acetaldehyde. In addition, this enzyme can use acetaldehyde as the sole substrate, resulting in a tandem aldol reaction, yielding 2,4,6-trideoxy-D-erythro-hexapyranose, which spontaneously cyclizes. This reaction is very useful for the synthesis of the side chain of statin-type drugs used to decrease cholesterol levels in blood. One of the main challenges in the use of DERA in industrial processes, where high substrate loads are needed to achieve the desired productivity, is its inactivation by high acetaldehyde concentration. In this work, the utility of different variants of Pectobacterium atrosepticum DERA (PaDERA) as whole cell biocatalysts to synthesize 2-deoxyribose 5-phosphate and 2,4,6-trideoxy-D-erythro-hexapyranose was analysed. Under optimized conditions, E. coli BL21 (PaDERA C-His AA C49M) whole cells yields 99 % of both products. Furthermore, this enzyme is able to tolerate 500 mM acetaldehyde in a whole-cell experiment which makes it suitable for industrial applications.     

用活化低等级粉煤灰开发绿色新型胶凝材料的试验研究

介绍了对低等级粉煤灰进行活化处理开发绿色新型胶凝材料的意义、技术路线、试验结果及分析。     

Ti-xCr-yCu钛基材料的制备及组织性能研究

研究了Al-Cu-Li-(0.35Mg)-(0.2In)合金的拉伸性能、时效析出相类型及其分布。T6峰时效时,Al-Cu-Li合金的时效析出相为T1(Al2CuLi)和?? (Al2Cu)相。添加0.2%In时,T6态时效早期形成许多方块状的立方相Al5Cu6Li2,且随时间延长其尺寸保持稳定;同时,可促进? ?相析出;相应合金的时效响应加速,强度提高。同时添加In和Mg可抑制Al5Cu6Li2相析出,但促进T1相析出。In和Mg的复合微合金化效果小于2050铝锂合金中Ag和Mg的复合微合金化效果,因而In+Mg复合微合金化铝锂合金T6态强度低于Ag+Mg复合微合金化的2050铝锂合金。T8态时效时,时效前预变形产生的位错抑制了In元素单独添加和In+Mg复合添加的微合金化效果。     

提高嵌入式时栅传感器精度的测头设计方法

为了提高嵌入式时栅传感器的测量精度,结合传感器自身的特点,从布置方式和数据处理方式两方面设计了特殊的测头结构。首先利用谐波分析确定传感器误差的主要频次,然后分别针对长短周期的误差采用多组测头对径和间隔特定空间角度的测头布置方式,测头之间采用数字量相加的数据处理方式,最后通过实验验证了这种测头结构和数据处理方式的有效性。结果表明,与单测头结构相比,这种方式将长周期误差降低了75%,短周期误差降低了83.6%,更有效地提高了嵌入式时栅传感器的测量精度。     

Synthesis of Gemini‐Like Methyl Acrylate‐Acrylic Acid‐Methyl Acrylate Triblock Copolymers Surfactants by RAFT Polymerization in Solution and Investigation of their Behavior at the Air–Water Interface

A series of methyl acrylate‐acrylic acid amphiphilic triblock copolymers (PMA‐PAA‐PMA) were prepared by solution polymerization using S,S′‐bis (α,α‐dimethy1acetic acid) trithiocarbonate (BDAT) as a reversible addition fragmentation chain transfer (RAFT) agent and methyl acrylate (MA) as the first monomer. The triblock copolymers and their common MA homopolymer precursors were characterized in terms of their compositions, molecular weights and behavior at the air–water interface using ¹H‐NMR spectroscopy, thermogravimetric analysis, gel permeation chromatography, surface tension, transmission electron microscopy (TEM) and dynamic light scattering respectively. The results indicated that PMA‐PAA‐PMA was successfully synthesized through RAFT polymerization. The polydispersity index (PDI) decreased when the molar ratio [n(MA)/n(AA)] increased, the lowest PDI was obtained at 5.23 wt% RAFT and the molecular weights were consistent with the theoretical value as the RAFT agent percentage varied. The polymer neutralized by sodium hydroxide solution shows a low critical micelle concentration (CMC), which was <10^?2 mol L^?1 in water. The A_min values increased and showed a maximum with decreased AA chain length. TEM showed that the neutralized polymer formed a special vesicle structure with large pore structure which led to a low CMC and surface tension of water.     

Smoke and toxicity suppression by zinc salts in flame‐retardant polyurethane‐polyisocyanurate foams filled with phosphonate and chlorinated phosphate

Three types of zinc salts, ZnAl₂O₄, ZnFe₂O_4, and Zn₂SiO_4, were prepared by coprecipitation. Potential smoke and toxicity suppression by zinc salts in flame‐retardant polyurethane‐polyisocyanurate foams (FPUR‐PIR) with dimethylmethylphosphonate (DMMP) and tris (2‐chloropropyl) phosphate (TCPP) were investigated. The crystal structure and dispersity of zinc salts in FPUR‐PIR were characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Smoke density, flame retardancy, and thermal degradation were studied using smoke density rating (SDR), limiting oxygen index (LOI), the cone calorimeter test, and thermogravimetry coupled with FTIR spectrophotometry (TGA‐FTIR). The results indicated that pure zinc salts were obtained and evenly dispersed on the cell wall of FPUR‐PIR. SDR and the specific extinction area (SEA) were significantly decreased, the time to second heat release rate peak (pk‐HRR) of FRUP‐PIR was delayed after incorporation of the zinc salts; zinc salts partially inhibited phosphorus oxide release into the gas phase, enhanced the condensed phase effect of phosphorus, reduced, and prolonged the release of isocyanate compound and hydrogen cyanide from FRUP‐PIR; due to an increase in the amount of char residues, which indicated the suppression of smoke and toxicity volatiles. ZnFe₂O₄ resulted in better char formation at the initial degradation stage of FPUR‐PIR, and ZnAl₂O₄ retained more phosphorus in the solid phase at higher temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41846.