Molecular Structure,Crystallinity, and Morphology of Uncompatibilized and Compatibilized Blends of Polyethylene/Nylon 12

The present study is aimed at investigating differences in molecular structure, crystallinity, and morphology between uncompatibilized and compatibilized blends of high‐density polyethylene (HDPE) and Nylon 12 by using Fourier‐transform (FT) Raman spectroscopy, wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Uncompatibilized and compatibilized blends of HDPE/Nylon 12 with a Nylon 12 content ranging from 10 to 90 wt.‐% with an increment of 10 wt.‐% were prepared. The compatibilized polymer blends were prepared by adding a small amount of maleic anhydride (MAH) and it was found that 0.5 wt.‐% MAH yielded a good dispersion. SEM images show that both kind of blends have a different miscibility behavior. The uncompatibilized and compatibilized blends yield quite different X‐ray diffraction patterns; the latter blends with a Nylon 12 content > 70 wt.‐% show orientational effects in the X‐ray pattern of the HDPE. The crystallinity of the HDPE of both blends was evaluated by the full width at half intensity of the (110) reflection of HDPE. To do that, the diffraction peaks were analyzed by a curve‐fitting method. To evaluate the crystallinity from Raman spectra, the intensity ratio of the two bands at 1 129 and 1 110 cm^?1 was used. Of note is that the 1 129 cm^?1 band is caused by a symmetric C? C stretching mode of all‐trans ? (CH₂)_n? groups arising only from HDPE. The Raman spectra and X‐ray diffraction measurements revealed that when the Nylon 12 content reaches 70 wt.‐%, the crystallinity of HDPE in the compatibilized blends becomes higher than that of HDPE in the uncompatibilized blends. This result is different from the general trend of crystallinity of HDPE in polymer blends. The difference suggests that the effect of the high viscosity of the Nylon‐rich phase on the crystallinity is more significant than the effect of the impurity (MAH‐grafted PE). It seems that the extension of the Nylon 12‐rich phase during the extrusion process leads to orientational effects because of the increase in the interaction between MAH and HDPE.

SEM images of HDPE/Nylon 12 compatibilized (top) and uncompatibilized (bottom) blends with a Nylon 12 content of 20 wt.‐%.     

Thermal Behavior,Structure and Morphology of Propene/Higher 1‐Olefin Copolymers

Summary: Propene‐based random copolymers, synthesized with two isospecific methylaluminoxane‐activated ansa‐zirconocenes and containing even and odd carbon‐numbered higher 1‐olefins, were investigated by DSC and WAXD. Nature and amount of co‐units affect primary and secondary crystallization as well as melting behavior; their role is discussed in the light of microstructural features of the macromolecular chains. The specific role of 1‐olefin comonomers in the development of the γ‐polymorph was assessed by crystallizing selected samples at relatively high temperatures. A good agreement between the fraction of γ‐phase calculated from the deconvolution of the DSC melting endotherms and from WAXD analysis was found. The γ‐phase content nicely correlates with the average length of the isotactic sequences. In the WAXD patterns of some propene/1‐butene copolymers a new reflection at 2θ ? 10°, likely corresponding to the newly discovered trigonal modification of isotactic polypropene, was found.

Room temperature WAXD of copolymer M‐PBu7.5 after isothermal crystallization at two different temperatures.     

Synthesis,structure and crystal morphology of nylon 16

The new polyamide nylon 16 was produced by polycondensation of 16-aminohexadecanoic acid in bulk at 210°C. The monomer was obtained by ring-opening hydrolysis of 2-azacycloheptadecanone which was prepared from commercial 8-cyclohexadecen-1-one through a four-step synthesis route. The polymer has a molecular weight of 13 000 and melts at 164°C. Fiber X-ray diffraction and single crystal electron diffraction measurements revealed that nylon 16 crystallizes in a monoclinic lattice with the parameters a = 0.483 nm, b = 0.935 nm, c = 4.16 nm (chain axis), γ = 121° containing two chains in the unit cell. The packing for the chains was found to be similar to that described for the γ-form characteristic of nylons, whereas a crystal phase in the α-form was not observed. Lamellar crystals of nylon 16 grown in 2-octanol were examined by electron microscopy, and their structure and morphology is discussed in relation to the crystal model conventionally accepted for the γ-form of nylons.     

Influence of Crystallization Conditions on the Crystal Order and Dynamic Thermal Behavior of Nylon 1010

Nylon 1010 crystals with different size and perfection were prepared under various crystallization conditions. Temperature‐varied X‐ray diffraction and transmission electron microscopy were used to investigate the structure and morphology of these crystals. The pseudo‐hexagonal phase (also known as γ modification) of nylon 1010 was obtained by heating the quenched sample to a high temperature, where this phase is stable. Cooling of the γ modification sample immediately resulted in a Brill transition into the triclinic form. The WAXD and TEM results showed that the crystal structure at room temperature as well as its thermal behavior on heating is strongly influenced by the crystallization conditions. No Brill transition temperature was observed for large or perfect crystals in both the heating and the cooling process, i. e. for melt‐crystallized spherulitic crystals and lamellar single crystals grown from dilute solution. This shows that the Brill transition depends on the size and perfection of the crystal.     

Synthesis,Morphology, and Properties of Polyurethane‐triazoles by Click Chemistry

To explore the applications of click chemistry in polyurethane materials, a series of novel linear polyurethane‐triazoles (PUTs) are prepared using the in situ click reaction of propargyl‐terminated polyurethanes with 1,4‐dibromobutane in the presence of sodium azide. The PUT structures are confirmed by ¹H NMR, Fourier transform infrared (FTIR) spectroscopy, and elemental analysis, and the number‐average molecular weights of PUTs range from (3.74–11.16) × 10⁴ g mol^?1, determined by gel permeation chromatography. The triazole ring content is characterized and the effects of incorporating the triazole rings on the properties and morphologies of PUTs are examined. Because of the extra dipole–dipole interaction and hydrogen bonds of 1,4‐disubstituted triazole in the hard segments, microphase separation of the PUTs is enhanced compared with conventional polyurethane extended with 1,4‐butanediol. The tensile strengths of PUTs, from 21.8 to 39.0 MPa, are higher than conventional polytriazole elastomers, owing to the physical crosslinks formed by the hydrogen bonds in the PUTs. However, the thermal stability of the PUTs decreases as the hard segment content increases.

     

Regulation of Calcite Crystal Morphology by Intracrystalline Acidic Proteins and Glycoproteins

Many biologically formed calcite crystals contain intracrystalline macromolecules. The ways in which they interact with growing calcite crystals were evaluated by monitoring changes in the morphology of calcite crystals grown in vitro in their presence. Macromolecules were extracted from within isolated prisms from the prismatic layer of the shell of the mollusk Atrina rigida and from spines of the sea urchin Paracentrotus lividus. Two modes of interaction were identified; the interaction of highly acidic proteins with calcite planes perpendicular to the c crystallographic axis and the interaction of glycoproteins with planes roughly parallel to the c axis. By different preparative procedures we demonstrated that the polysaccharide moieties of the sea urchin spine glycoproteins are directly involved in the latter mode of interactions. We suggest that organisms utilize the abilities of these macromolecules to interact in different ways with calcite crystals, and in so doing fine-tune aspects of the control of crystal growth in vivo.     

Crystal Structure of the 2''-Specific and Double-Stranded RNA-Activated Interferon-Induced Antiviral Protein 2''-5''-Oligoadenylate Synthetase

Toll-like receptors (TLRs) are pattern recognition receptors of the innate immune system, which recognize molecular structures on pathogens or cellular stress-associated molecules. TLR–ligand interactions trigger activation of inflammatory signal transduction and expression of genes involved in host defense. In this study, we have examined the requirement for different TLR adaptor molecules in virus-induced chemokine expression and are currently trying to identify the TLR involved. We have found that both a herpesvirus [herpes simplex virus (HSV)] and a paramyxovirus (Sendai virus) require a functional genome to induce expression or proinflammatory chemokines in human and murine monocytic cell lines. For both viruses, this is independent of the TLR adaptor molecules TRIF and Mal. However, overexpression of the Vaccinia virus-encoded inhibitor of TLR-signalling A52R or dominant-negative MyD88 totally inhibited HSV-induced RANTES expression but only partially prevented Sendai virus from inducing this chemokine. This suggests that HSV-induced RANTES expression occurs via a TLR pathways, whereas Sendai virus utilizes both TLR-dependent and -independent pathways to stimulate expression of RANTES. We are currently trying to identify the TLRs involved. Data from these studies will also be presented at the meeting.     

Synthesis, subcellular localization and VP16 interaction of the herpes simplex virus type 2 UL46 gene product

Summary.  We developed a rabbit polyclonal antiserum reactive against a recombinant 6x His-UL46 fusion protein expressed in*Escherichia coli, and using this antiserum identified the UL46 gene product of herpes simplex virus type 2 (HSV-2) to be phosphoproteins with apparent molecular masses of 82-, 84-, and 86-kDa in infected Vero cells. The UL46 protein was produced in the late phase of infection in a manner highly dependent on viral DNA synthesis, and was mainly distributed at the edge of the nucleus in the cytoplasm. Although its kinetics of production and its progress of distribution were different from those of the major tegument protein VP16 (the UL48 gene product or α-trans-inducing factor (αTIF)), most of the UL46 protein colocalized with VP16 in the late phase of infection, and copurified with it in column chromatography. Moreover, our data showed that the HSV-2 UL46 protein, when coexpressed with VP16, enhanced α4 promotor-regulated gene expression in a transient luciferase reporter assay, while the expression of the UL46 protein alone suppressed it. Received December 16, 1999 Accepted February 23, 2000     

Crystallization,Morphology, and Enzymatic Degradation of Polyhydroxybutyrate/Polycaprolactone (PHB/PCL) Blends

Two types of mixtures were prepared by solution blending: high molecular weight polyhydroxybutyrate (PHB)/poly(ε‐caprolactone) (PCL) and PHB/low molecular weight chemically modified PCLs (mPCL). The morphology, crystallization, and enzymatic degradation of the blends were studied by differential scanning calorimetry, polarized light optical microscopy, scanning electron microscopy, ¹H NMR, and weight loss measurements. In addition, enzymatic degradation studies were performed by an exposure to Aspergillus flavus. High molecular weight PHB/PCL blends were found to be immiscible in the entire composition range. Phenomena such as PCL fractionated crystallization and a decrease in PHB nucleation density were detected. When PHB was blended with mPCLs, the blends were partially miscible; two phases were formed, but the PHB‐rich phase exhibited clear signs of miscibility through a depression of both the T_m and the T_g of the PHB component (which was stronger with lower molecular weight mPCL), and an increase in the growth rate of PHB spherulites in the blends as compared to neat PHB or to the PHB component in the PHB/PCL blends. The biodegradation by a exposure to A. flavus showed that the blends are synergistically attacked in comparison to the homopolymers. Two factors may influence the improved degradation rate of the blends: the dispersion of the components and their crystallinity that was reduced in view of the fractionated crystallization and impurities transfer. In the case of the PHB/mPCL blends, the increased miscibility between the components caused a reduction in the degradation rate.

     

Her-2/neu、DPC4和P16在胰腺癌中的表达及其意义

目的观察Her-2/neu、P16和DPC4基因在胰腺癌中的表达,并探讨其与胰腺癌发生、发展的关系。方法应用免疫组织化学法检测Her-2/neu、P16和DPC4基因在34例胰腺癌和12例胰腺良性病变和正常组织中的表达水平,将结果与患者的临床病理学资料进行统计。结果胰腺癌Her-2/neu表达水平和P16表达缺失水平显著高于胰腺良性病变和正常组织(P<0.05);胰腺癌DPC4表达水平低于胰腺良性病变和正常组织。高、中度分化胰腺癌DPC4表达水平显著高于低分化胰腺癌(P<0.05);有淋巴结转移的胰腺癌Her-2/neu和P16表达水平显著低于无淋巴结转移的胰腺癌(P<0.05);随TNM分期增高,Her-2/neu表达阳性率显著降低(Ⅰ期85.7%;Ⅱ期54.5%,Ⅲ期36.4%,Ⅳ期0.0%)(P<0.05);P16表达阳性率亦显著降低(Ⅰ期100.0%;Ⅱ期72.7%,Ⅲ期54.5%,Ⅳ期20.0%)(P<0.05)。Her-2/neu与P16和DPC4与Her-2/neu的表达密切相关(P<0.05);P16与DPC4的表达极密切相关(P<0.01)。结论Her-2/neu、P16和DPC4的表达对估计胰腺癌的生物学行为和判断预后有较大帮助。P16和DPC4的表达对胰腺癌的进展可能有协同作用。     

抗GD2/抗CD16单链双特异性抗体的构建及在大肠杆菌中的表达

利用重叠PCR(overlap-PCR)将抗GD2表面抗原GD2的单链抗体基因m-ScFv和抗CD16的单链抗体基因NM3E2融合在一起,得到新型的单链双特异性抗体基因n-m,双抗的联接肽序列为SerGly4Ser,在肽连的C端引入了6×his以利于纯化。该双特异性抗体基因的序列经测序验证后,连接表达载体pET-22b( ),转化大肠杆菌菌株BL21(DE3),诱导表达,凝胶成像系统扫描显示表达的外源融合蛋白约占菌体总蛋白的27%。表达蛋白分泌于胞质空间,经超声波破胞后收集上清,经Ni 亲和层析柱分离,纯度可达90%以上。经SDS-PAGE及Westernblotting鉴定表达蛋白的分子量为53KD,与预期的相符。     

Synthesis,Thermal and Dielectric Properties of a Photocrosslinkable Ferroelectric Liquid Crystal and its Copolymers

A series of new ferroelectric liquid crystal (FLC) copolymers based on a photocrosslinkable ferroelectric liquid crystal was synthesized. Chemical structures were analyzed by ¹H NMR and FT‐IR spectroscopy. Liquid crystal phases of these photocrosslinkable materials were characterized by differential scanning calorimetry, optical polarizing microscopy, and X‐ray diffraction measurements. A wide temperature range of chiral smectic (S*_C) phase (approximately 100°C) was found for the monomer and its copolymers. Microscopic phase separation was observed when the graft ratios of the FLC monomer were 15%, 35%, and 55%. Dielectric relaxation behavior of the ferroelectric liquid crystal copolymers was investigated by broadband dielectric relaxation spectroscopy. As the graft content of liquid crystal decreased, the relaxation intensity and frequency of the S*_C phase increased. The relationship between thermal dynamics and chemical structure was also discussed.     

Effect of the Polyimide Structure and ZnO Concentration on the Morphology and Characteristics of Polyimide/ZnO Nanohybrid Films

Summary: A series of polyimide/ZnO nanohybrid films with different ZnO content were prepared from a rigid pyromellitic dianhydride‐4,4′‐diaminodiphenyl ether (PMDA‐ODA) polyimide (PI) and a flexible 3,3′,4,4′‐benzophenonetetracarboxylic acid dianhydride‐4,4′‐diaminodiphenyl ether (BTDA‐ODA) PI with ZnO nanoparticles (3–4 nm). Fourier‐transform infrared (FT‐IR) and X‐ray photoelectron spectroscopy (XPS) depict that the ZnO nanoparticles function as a physical cross‐linking agent with PI through hydrogen bonding between the OH on the ZnO nanoparticles and the C?O of the imide groups. ZnO nanoparticles in the rigid PMDA‐ODA matrix cause a larger percentage decrease in the coefficient of linear thermal expansion (CTE) than in the flexible BTDA‐ODA matrix. The BTDA‐ODA/ZnO hybrid films have two transition peaks in dynamic mechanical tan δ curves, but PMDA‐ODA/ZnO hybrid films only have one transition peak. Thermogravimetric analysis reveals that ZnO decreases the thermal degradation temperature (T_d) in both hybrid films, but less so in PMDA‐ODA/ZnO films. Transmission electron microscopy (TEM) images reveal that the rigid matrix induces larger particle size (30–40 nm) compared to the flexible matrix (10–15 nm).

Illustration of the interaction between ZnO nanoparticles and PI.     

Morphology,paleoanthropology, and neanderthals

Morphology carries the primary signal of events in the evolutionary history of any group of organisms but has been relatively neglected by paleoanthropologists, those who study the history of the human species. Partly this is the result of historical influences, but it is also due to a rather fundamentalist adherence among paleoanthropologists to the tenets of the Neodarwinian Evolutionary Synthesis. The result has been a general paleoanthropological desire to project the species Homo sapiens back into the past as far and in as linear a manner as possible. However, it is clear that the human fossil record, like that of most other taxa, reveals a consistent pattern of systematic diversity—a diversity totally unreflected in the conventional minimalist interpretation of that record. Thus, the Neanderthals, both morphologically and behaviorally as distinctive a group of hominids as ever existed, are conventionally classified simply as a subspecies of our own species Homo sapiens—a classification that robs these extinct relatives of their evolutionary individuality. Only when we recognize the Neanderthals as a historically distinctive evolutionary entity, demanding understanding in its own terms, will we be able to do them proper justice. And we will only be able to do this by restoring morphology to its proper place of primacy in human evolutionary studies. Anat. Rec. (New Anat.) 253:113–117, 1998. © 1998 Wiley-Liss, Inc.     

Structure,expression pattern and biological activity of molecular complex TREM-2/DAP12

DNAX-activating protein of 12 kDa (DAP12) is a member of type I transmembrane adapter proteins containing immunoreceptor tyrosine-based activation motifs (ITAMs). In humans DAP12 gene is located on chromosome 19q13.1. DAP12 forms a molecular complex with triggering receptor expressed on myeloid cells two (TREM-2). TREM-2 ligation leads to the activation of Src family kinases, phosphorylation of tyrosine residues in the ITAM of DAP12, recruitment of the Syk and ZAP70 tyrosine kinases and initiation of an intracellular signaling cascade. Depending on the cell type, DAP12/TREM-2 activation plays an important role in activation and differentiation of osteoclasts, phagocytosis of bacteria, brain and bone homeostasis and inhibition of the toll-like receptor (TLR) signaling in macrophages and dendritic cells. A proper understanding of the function of this complex receptor has been restrained because of the elusive nature of TREM-2 ligands.