Kinetics and thermal crystallinity of recycled PET. II. Topographic study on thermal crystallinity of the injection-molded recycled PET

The injected specimens of recycled poly(ethylene terephthalate) (R-PET) and its blends with engineering PET (E-PET) are studied with differential scanning calorimetry (DSC). Specimens are dissected into three segments of (1) outer skin, (2) middle, and (3) the core for the topographic study of their separate crystallinities, which are induced by different crystallization rates in the injection mode. DSC thermograms reveal the different crystallinity states among these three segments with decreasing crystallinity from core to middle to the skin segments and the times and contact of injection-molded specimens with the mold during the cooling cycle after the injection of the specimens. With the same procedures of injection molding, comparisons of crystallinity among various specimens of virgin blow molding grade PET (B-PET), E-PET, and R-PET are made. There are little differences in crystallinity among three segments of B- or E-PET specimens. In contrast, a higher degree of crystallinity in the core segment than either middle or skin segments is observed for the R-PET. This may contribute to the faster crystallization rate of the R-PET in the mold. Specimens of R-/E-PET blends follow the R-PET pattern, even in 20% of R-PET in the blend. This faster crystallization rate of R-PET is confirmed with the lowering crystallization temperatures (T_c) of the R-PET and R-/E-PET blended specimens in the DSC heating process. Dynamic DSC cooling analysis reveals a high order of crystallinity in R-PET and R-/E-PET blends. Gel permeation chromatography (GPC) measurements of molecular weights and distributions support the orderly structure for R-PET. Terminal group analysis and intrinsic viscosity measurements of the R-PET support the chain modification of R-PET during the thermal treatments in accordance with the evidences of smaller M_w and narrower molecular-weight distribution from the GPC findings for the recycled PET. © 1996 John Wiley & Sons, Inc.     

智能手机如何实现数据同步化

手机的使用模式相当简单:用户端口只要离PC数尺的距离,蓝牙手机就能自动进行电子邮件、相片、工作清单、联络人等数据的同步化.但有时用户对蓝牙的同步化与数据传输功能仍存在一些困惑,如PC虽然有蓝牙功能,但却经常无法连上手机如第一次就想让蓝牙功能顺利执行仍需要一些技巧,并不能立马使用等.本文详细为您讲述如何使智能手机实现数据同步化.     

Role of Tyrosine Kinase Syk in Thrombus Stabilisation at High Shear

Understanding the pathways involved in the formation and stability of the core and shell regions of a platelet-rich arterial thrombus may result in new ways to treat arterial thrombosis. The distinguishing feature between these two regions is the absence of fibrin in the shell which indicates that in vitro flow-based assays over thrombogenic surfaces, in the absence of coagulation, can be used to resemble this region. In this study, we have investigated the contribution of Syk tyrosine kinase in the stability of platelet aggregates (or thrombi) formed on collagen or atherosclerotic plaque homogenate at arterial shear (1000 s⁻¹). We show that post-perfusion of the Syk inhibitor PRT-060318 over preformed thrombi on both surfaces enhances thrombus breakdown and platelet detachment. The resulting loss of thrombus stability led to a reduction in thrombus contractile score which could be detected as early as 3 min after perfusion of the Syk inhibitor. A similar loss of thrombus stability was observed with ticagrelor and indomethacin, inhibitors of platelet adenosine diphosphate (ADP) receptor and thromboxane A₂ (TxA₂), respectively, and in the presence of the Src inhibitor, dasatinib. In contrast, the Btk inhibitor, ibrutinib, causes only a minor decrease in thrombus contractile score. Weak thrombus breakdown is also seen with the blocking GPVI nanobody, Nb21, which indicates, at best, a minor contribution of collagen to the stability of the platelet aggregate. These results show that Syk regulates thrombus stability in the absence of fibrin in human platelets under flow and provide evidence that this involves pathways additional to activation of GPVI by collagen.     

选择同轴电缆和双绞线

因其性能的限制,铜缆的应用几次走到了尽头。之后,新工艺和元件的推出又使它得到了重生。对于两种最常用的高性能铜缆,同轴电缆和双绞线理论上是有局限性的,然而,我们离这些极限有多近呢？     

Redox State of Iron and Its Related Effects in the CaO–P2O5–Fe2O3 Glasses

Iron exists in Fe²⁺ and Fe³⁺ states in CaO–P₂O₅–Fe₂O₃ glasses and they impart characteristic optical absorption bands that allow analysis of relative proportion of the two species. This communication reports the redox states of glasses melted under air, argon, and oxygen atmospheres and relates them to the dissolution rates. The dissolution rate was found to be related to the redox state and it is lowered if the glass is melted under oxidizing atmospheres.     

Molecular Interactions of Tannic Acid with Proteins Associated with SARS-CoV-2 Infectivity

The overall impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on our society is unprecedented. The identification of small natural ligands that could prevent the entry and/or replication of the coronavirus remains a pertinent approach to fight the coronavirus disease (COVID-19) pandemic. Previously, we showed that the phenolic compounds corilagin and 1,3,6-tri-O-galloyl-β-D-glucose (TGG) inhibit the interaction between the SARS-CoV-2 spike protein receptor binding domain (RBD) and angiotensin-converting enzyme 2 (ACE2), the SARS-CoV-2 target receptor on the cell membrane of the host organism. Building on these promising results, we now assess the effects of these phenolic ligands on two other crucial targets involved in SARS-CoV-2 cell entry and replication, respectively: transmembrane protease serine 2 (TMPRSS2) and 3-chymotrypsin like protease (3CLpro) inhibitors. Since corilagin, TGG, and tannic acid (TA) share many physicochemical and structural properties, we investigate the binding of TA to these targets. In this work, a combination of experimental methods (biochemical inhibition assays, surface plasmon resonance, and quartz crystal microbalance with dissipation monitoring) confirms the potential role of TA in the prevention of SARS-CoV-2 infectivity through the inhibition of extracellular RBD/ACE2 interactions and TMPRSS2 and 3CLpro activity. Moreover, molecular docking prediction followed by dynamic simulation and molecular mechanics Poisson–Boltzmann surface area (MMPBSA) free energy calculation also shows that TA binds to RBD, TMPRSS2, and 3CLpro with higher affinities than TGG and corilagin. Overall, these results suggest that naturally occurring TA is a promising candidate to prevent and inhibit the infectivity of SARS-CoV-2.     

Fuel choice and aggregate energy demand in the residential and commercial sectors

The energy demand response of the residential and commercial sectors to fuel price changes is of increasing importance to public policy makers. In this paper, the demands for energy in both sectors are examined separately using a refined data base. For each sector, a multinomial logit formulation is utilized, along with an aggregate demand equation to determine analytically short- and long-run fuel price elasticities of demand for the major fuels consumed. It is found that increases in energy prices have a greater effect on energy demand in the commercial sector. Furthermore, in both sectors, raising electricity prices has a greater effect for conserving energy (both end-use and primary) than do equal price rises for natural gas or heating oils.