Mechanical properties of HDPE–PS–SEBS blends

Blends of high-density polyethylene (HDPE), polystyrene (PS), and an SEBS triblock copolymer were extruded, pelletized, and injection molded. The binary HDPE–PS blends exhibit very poor ductibility; however, addition of the SEBS block copolymer greatly improves this characteristic but with an accompanying loss in strength and modulus. The modified blends are very tough and have mechanical properties suitable for many end use applications. However, weld lines pose a problem and should be avoided with these blends.     

Synthesis of Organotin Polyesters from Reaction of the Salt of <Emphasis Type="SmallCaps">d</Emphasis>-Camphoric Acid and Organotin Dihalides and Initial Anticancer Activity

Organotin polyesters were synthesized from d-camphoric acid. Since d-camphoric acid is a natural product, this is part of the green chemistry initiative. Further, synthesis occurred employing commercially available reactants and the interfacial system which is used industrially to synthesize aramids and polycarbonates. Thus, scale-up is straightforward. Polymers were synthesized employing the interfacial reaction between various organotin dihalides and the salt of d-camphoric acid. Reaction was rapid occurring in 30 s and less. Product yield was good except for the product from dioctyltin dichloride. The products are polymeric with chain lengths from 230 to 2200. Structural characterization with infrared spectrometry and MALDI MS are consistent with the formation of organotin polyesters containing the camphoric acid moiety within its backbone. IR shows formation of the Sn–OOC(O) linkage with the polymer having a combination of bridging and non-bridging geometrical arrangements about the tin atom. MALDI MS shows ion fragment to two and three repeat units. The products exhibit good ability to inhibit a battery of cancer cells including those from pancreatic cancer. The effective concentration for inhibition of the cancer cell lines are generally in the same range as those found for cisplatin and in the ng/mL range.     

Synthesis and Characterization,Including Cancer Cell Line Inhibition,of Group VA (Group 15)-Containing Polyesters from Reaction with Camphoric Acid

Polyesters were rapidly synthesized employing interfacial polymerization from reaction of the salt of camphoric acid with Group VA (Group 15) triphenylmetallic dihalides. Yields range from 25 to 46 percent with chain lengths about 250. Infrared spectroscopy shows the formation of two new bands one assigned to the symmetrical M–O stretching and the second assigned to the asymmetrical M–O stretching. The bridging structure about the metal atom increases as the metal atom size increases. MALDI MS and proton NMR are consistent with the formation of the polyester structure. Ion fragment clusters to four to six units are identified. The polymers show good inhibition of a group of cancer cell lines including two pancreatic human cancer cell lines. In comparison with other metal/camphoric acid polymers, the metallocene polymers exhibit low EC₅₀ to the nanogram/ml range, and CI₅₀ values greater than one thousand for the hafnocene and zirconocene products. If this trend continues, the emphasis should be on the Group IVB metallocenes with respect to efforts to create anticancer drugs.     

Microfluidic platform for controlled synthesis of polymeric nanoparticles

A central challenge in the development of drug-encapsulated polymeric nanoparticles is the inability to control the mixing processes required for their synthesis resulting in variable nanoparticle physicochemical properties. Nanoparticles may be developed by mixing and nanoprecipitation of polymers and drugs dissolved in organic solvents with nonsolvents. We used rapid and tunable mixing through hydrodynamic flow focusing in microfluidic channels to control nanoprecipitation of poly(lactic- co-glycolic acid)- b-poly(ethylene glycol) diblock copolymers as a model polymeric biomaterial for drug delivery. We demonstrate that by varying (1) flow rates, (2) polymer composition, and (3) polymer concentration we can optimize the size, improve polydispersity, and control drug loading and release of the resulting nanoparticles. This work suggests that microfluidics may find applications for the development and optimization of polymeric nanoparticles in the newly emerging field of nanomedicine.     

Algal biomass constituent analysis: method uncertainties and investigation of the underlying measuring chemistries

Algal biomass compositional analysis data form the basis of a large number of techno-economic process analysis models that are used to investigate and compare different processes in algal biofuels production. However, the analytical methods used to generate these data are far from standardized. This work investigated the applicability of common methods for rapid chemical analysis of biomass samples with respect to accuracy and precision. This study measured lipids, protein, carbohydrates, ash, and moisture of a single algal biomass sample at 3 institutions by 8 independent researchers over 12 separate workdays. Results show statistically significant differences in the results from a given analytical method among laboratories but not between analysts at individual laboratories, suggesting consistent training is a critical issue for empirical analytical methods. Significantly different results from multiple lipid and protein measurements were found to be due to different measurement chemistries. We identified a set of compositional analysis procedures that are in best agreement with data obtained by more advanced analytical procedures. The methods described here and used for the round robin experiment do not require specialized instrumentation, and with detailed analytical documentation, the differences between laboratories can be markedly reduced.     

Innate immune responses and health of individually reared Holstein calves after placement into transition-pens 23 d after weaning

Sixty-four Holstein dairy bull calves were all reared in individual calf-hutches and pens until they were randomly assigned to treatments of Grouped (pens of 3, n=36 calves) or Control (left in home hutch, n=8 calves) at age 68±2·3 d (body weight 74·9±1·5 kg). Blood was drawn at age 66, 70, 74 and 88 d for ex-vivo immunological and biochemical analyses. Calf starter intake was measured daily and individual body weights were measured at age 68, 78, and 89 (±2·3 sd) d. Grouped-calves consumed less starter (P<0·05), and weighed 6·4±1·99 kg less (P<0·05) than Control-calves by age 89 d. Group housing was a mild stressor, as evident by a transient suppression in neutrophil oxidative burst at age 70 d, but there was a lack of difference in the neutrophil:lymphocyte ratio of peripheral leucocytes and neutrophil expression of L-selectin at age 70 and 74 d. However, grouped-calves had elevated total peripheral leukocyte counts at age 70 d (P<0·05) and tended (P<0·10) to be greater at age 74 and 88 d. In addition, neutrophil phagocytosis of Escherichia coli increased (P<0·05) at age 74 d in Grouped-calves. These data indicate that moving calves into transition-pens with 3 calves per group decreases performance, but this may not be due primarily to extreme stress or disease. These data do indicate that it is important that calves have a competent immune system and any potential stressors are limited when they are moved into transition-pens because they are exposed to a wider diversity and (or) load of pathogens.     

A tunable plasmon resonance in gold nanobelts

Plasmonic nanowires with sub-100-nm rectangular cross sections were found to exhibit a strong transverse plasmon peak at visible wavelengths. By correlating atomic force microscopy measurements of individual nanobelts with their dark-field scattering spectra, it is seen that the transverse peak tunes with cross-sectional aspect ratio. Simulations revealed that the scattering plasmonic modes are transverse antisymmetric excitations across the nanobelt width. Unlike larger diameter silver nanowires, these nanobelts exhibit sharp, tunable plasmon resonances similar to those of nanoparticles.     

A model of dual attitudes.

When an attitude changes from A? to A?, what happens to A?? Most theories assume, at least implicitly, that the new attitude replaces the former one. The authors argue that a new attitude can override, but not replace, the old one, resulting in dual attitudes. Dual attitudes are defined as different evaluations of the same attitude object: an automatic, implicit attitude and an explicit attitude. The attitude that people endorse depends on whether they have the cognitive capacity to retrieve the explicit attitude and whether this overrides their implicit attitude. A number of literatures consistent with these hypotheses are reviewed, and the implications of the dual-attitude model for attitude theory and measurement are discussed. For example, by including only explicit measures, previous studies may have exaggerated the ease with which people change their attitudes. Even if an explicit attitude changes, an implicit attitude can remain the same. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stream quality in a small urbanised catchment

River-length patterns in the chemistry and biology of the Charlton Brook, an unclassified watercourse in Sheffield, England, have been examined. Five sampling sites for macroinvertebrates and pollutant analysis were used, in conjunction with Environment Agency's General Quality Assessment (GQA) methodologies and hydraulic analysis of the catchment. Sites were strategically located to account for the tributaries and the brook downstream of their confluence, to assess the potential impact from surface water outfalls (SWOs). Variations in GQA parameters indicate a significant drop in quality downstream of the SWOs that discharge to the study watercourse, with a marked drop in biological diversity noted at the onset of urbanisation. The decline in biological quality however is greater than that suggested by physicochemical analysis alone. There was a significant inverse relationship between impermeable area and biological diversity. Analysis of polycyclic aromatic hydrocarbons (PAHs) and trace metals in sediment from the watercourse showed significant yet irregular variations between sites. The potential toxicity of instream metal concentrations was determined using cumulative criterion unit (CCU) scores, which highlighted cadmium, copper and lead as the major sources of potential chronic instream toxicity. The threshold for likely harm to aquatic life is exceeded at all sites. In the absence of different physical characteristics, comparisons of the chemical and biological data indicate that the benthic macroinvertebrate population of such watercourses are adversely affected by the stormwater inputs.     

Xylose-Configured Cyclophellitols as Selective Inhibitors for Glucocerebrosidase

Glucocerebrosidase (GBA), a lysosomal retaining β-d -glucosidase, has recently been shown to hydrolyze β-d -xylosides and to transxylosylate cholesterol. Genetic defects in GBA cause the lysosomal storage disorder Gaucher disease (GD), and also constitute a risk factor for developing Parkinson's disease. GBA and other retaining glycosidases can be selectively visualized by activity-based protein profiling (ABPP) using fluorescent probes composed of a cyclophellitol scaffold having a configuration tailored to the targeted glycosidase family. GBA processes β-d -xylosides in addition to β-d -glucosides, this in contrast to the other two mammalian cellular retaining β-d -glucosidases, GBA2 and GBA3. Here we show that the xylopyranose preference also holds up for covalent inhibitors: xylose-configured cyclophellitol and cyclophellitol aziridines selectively react with GBA over GBA2 and GBA3 in vitro and in vivo, and that the xylose-configured cyclophellitol is more potent and more selective for GBA than the classical GBA inhibitor, conduritol B-epoxide (CBE). Both xylose-configured cyclophellitol and cyclophellitol aziridine cause accumulation of glucosylsphingosine in zebrafish embryo, a characteristic hallmark of GD, and we conclude that these compounds are well suited for creating such chemically induced GD models.