Preparation,characterization of chitosan/bamboo charcoal/poly(methacrylate) composite beads

Preparation and characterization of a low-cost, novel steam-activated bamboo charcoal (BC) and poly(methacrylate) (PMAA) bound with chitosan (CTS) to form chitosan/bamboo charcoal/poly(methacrylate) (CTS/BC/PMAA) composite beads is reported for the first time in this paper. The characteristics are revealed by techniques such as X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), scanning electron microscopy (SEM), Brunauer Emmett Teller (BET), solution pH and pH at point of zero charge \((\hbox {pH}_{\mathrm {pzc}})\). The composite beads possessed a dominant acidic surface group of 0.663 mmol \(\hbox {g}^{\mathrm {-1}}\), as revealed by Boehm titration method. This acidity was confirmed by its solution pH of 6.46; \(\hbox {pH}_{\mathrm {pzc}}\) of 6.70 and increase in oxygen surface via XPS analysis. \(\hbox {N}_{\mathrm {2}}\) adsorption–desorption isotherms at 77 K of the beads revealed high BET surface area (SA) of 681.15 \(\hbox {m}^{\mathrm {2}}\hbox {g}^{\mathrm {-1}}\). Langmuir model affords a SA of 773.34 \(\hbox {m}^{\mathrm {2}}\hbox {g}^{\mathrm {-1}}\). SEM showed the microporous nature of the composite beads. The properties of CTS/BC/PMAA composite beads were compared to CTS/BC and neat BC. Thermal stability and successful coating of 5.1 wt% of PMAA and 6.8 wt% of CTS to CTS/BC/PMAA beads were shown by DSC and TGA analyses. The composite beads showed low carbon particle released at pH 7.4 and 6.8. Furthermore, dynamic adsorption revealed that CTS/BC/PMAA composite beads can be used to capture a polar substance, such as creatinine.     

Automated insertion of package dies onto wire and into a textile yarn sheath

Microsystem Technologies - Wider adoption of electronic textiles requires integration of small electronic components into textile fabrics, without comprising the textile qualities. A solution is to...     

The development of ancient Mesoamerican metallurgy

Over the last twenty years, there has been a discernable increase in the number of scholars who have focused their research on metal production, working and use in antiquity, a field of study which has come to be known as archaeometallurgy. Materials scientists and conservators have worked primarily in the laboratory while archaeologists have conducted fieldwork geared to the study of metal technology in a cultural context with laboratory analysis as one portion of the interpretive program.     

Can phosphorus fertilisers alone increase levels of soil nitrogen in New Zealand hill country pastures?

In New Zealand grazed pastures, nitrogen (N) fixation by clover is the traditional method of supplying N to the grasses that make up the bulk of the pasture sward. In order to stimulate satisfactory clover growth, phosphorus (P) fertilisers are applied at levels which are generally more than adequate for grass requirements. These legumes then provided N through biological nitrogen fixation. However, studies conducted in New Zealand hill country pastures have revealed that these pastures are still highly N responsive. These results draw attention to a key issue with respect to N fertility in hill country pasture and the question arises as to the value of large P fertiliser applications to overcome N deficiency through clover growth. Here we used modelling approach to evaluate the effectiveness of adding P fertilisers to stimulate clover growth for improving soil N status in hill country pastures and to explore why the hill pastures are N responsive. In addition an attempt was made to explore the potential of fertiliser N in hill pastures based on the current model outcomes and the measured values of pasture production under non-limiting N.     

Microstructure and Crystallography of Titanium Nitride Whiskers Grown by a Vapor–Liquid–Solid Process

Titanium nitride whiskers having diameters of 0.5 to 1.5 μm and aspect ratios in the range of 20 to 50 have been produced by a new commercially scalable vapor–liquid–solid process. Electron microscopy studies have shown that most of the whiskers can be classified into two types based upon structure and morphology. The whiskers of one type are single crystals and have a growth direction of (100). Whiskers of the second type are comprised of two crystals having a common (110) growth direction. Both types have smooth surfaces and relatively few internal defects. Additionally, a small percentage of whiskers have considerable internal structure related to significant magnesium impurities.     

Small and Moderate Colour Differences

In nineteen regions of colour space groups of about 30 samples, differing by small to moderate amounts from one designated as ‘the standard’ were generated by offset printing. Twenty observers estimated the perceived size of each of these differences twice, using cateogry scaling - the judgements were not based on acceptability. The samples were placed, in turn, adjacent to the standard on a middle gray surround, subtended 4d? on the retina, were illuminated with semidiffuse fluorescent light, simulating daylight at about 45d? incidence, and viewed along the normal. The visual data were converted from an ordinal to an interval scale. The samples were measured by abridged spectro-photometry, and CIE coordinates, obtained by integration using the spectral-power distribution of the illumination source and the 1931 2d? standard observer. Colour differences were calculated by eleven formulae and correlated with the visual interval-scale results. The usual low correlation coefficients were found. The data are analysed colour by colour and significant differences are noted. Collectively, the Adams Chromatic Value (ANL AB 40), Saunderson-Milner, and CIE 1976 L*a*b* formulae gave better performances.     

Photodimers of 9-Haloanthracenes as Initiators in Atom Transfer Radical Polymerization: Effect of the Bridgehead Halogen

Summary Photodimers of 9-chloroanthracene, formed by a [4+4] cycloaddition reaction of 9-chloroanthracene, were used as initiators in the atom transfer radical polymerization of styrene and compared to results previously obtained using photodimers of 9-bromoanthracene as the initiator. Heat-induced cleavage of the photodimer coupled with slow initiation from the bridgehead radical have been used to account for the lack of control in the systems, and thus changing the halogen on the initiating photodimer could support or refute this model. Reactions performed using analogous procedures produced polymers with number average molecular weight (M_n) values significantly higher in the case of 9-chloroanthracene photodimer-initiated systems, with similar polydispersity index (PDI) values observed in trials catalyzed with CuCl or CuBr. Polymer products showed absorbance bands indicative of regenerated anthracene in all cases, consistent with heat-induced cleavage of the photodimer during the course of the polymerization. Kinetic plots demonstrated that the polymerizations initiated with photodimers of 9-chloroanthracene showed maximum M_n values were obtained after approximately 10% monomer conversion, with a decline in M_n as a function of monomer conversion after this point. The data support slower initiation in the case of 9-chloroanthracene photodimers, followed by heat-induced cleavage throughout the polymerization system.     

Thermal Oxidation of Aluminum Nitride Powder

The oxidation kinetics, morphology, and crystallinity of aluminum nitride (AlN) powder thermally oxidized in flowing oxygen were determined from 800° to 1150°C. At 800°C the oxidation became detectable with weight change. AlN powder was almost completely oxidized at 1050°C after only 0.5 h. Amorphous aluminum oxide formed at relatively low temperatures (800°–1000°C), with a linear oxidation rate governed by the oxygen–nitride interfacial reaction. Transmission electron microscopy displayed individual aluminum oxide grains which formed a discontinuous oxide layer at this temperature range. The aluminum oxide was crystalline at higher temperatures (>1000°C), as detected by X-ray diffraction, and the density of oxide grains increased with temperature.     

The influence of n-6 and n-3 fatty acids on kidney phospholipid composition and on eicosanoid production in aging rats

Changes in eicosanoid production may contribute to some of the complications of the aging process such as atherosclerosis and glomerular sclerosis. Polyunsaturated fatty acids of the n-6 and n-3 series are precursors of eicosanoids. We fed diets containing safflower oil as a source of n-6 fatty acids, fish oil as a source of n-3 fatty acids or beef tallow as a source of saturated fats to three groups of normal rats from 2–18 months of age. We demonstrated incorporation of the n-3 fatty acids, 20:5n-3 and 22:6n-3 into kidney phospholipids. Feeding of the diet containing n-3 fatty acids was associated with a markedly decreased giomerular production of PGE, 6-keto-PGF_1α and TXB₂. It also decreased the aortic production of 6-keto-PGF_1α and platelet production of TXB₂. No significant effect of n-6 fatty acids on dienoic eicosanoid production was observed. There were no adverse effects on kidney function as measured by urinary protein excretion and serum creatinine levels or on renal morphology by any diet. A diet enriched in n-3 fatty acids for 18 months remains effective in decreasing dienoic eicosanoids in the aging rat.     

Relation of stressful life events to metabolic control among adolescents with diabetes: 5-year longitudinal study.

Objective: To determine the relation of stressful life events to metabolic control. Design: We interviewed adolescents with Type 1 diabetes (n = 132; average age at enrollment = 12 years) annually for 5 years. Measures: Each year we administered measures of stressful life events, psychological distress, and self-care behavior. We downloaded data from blood glucose meters, and obtained measures of metabolic control (hemoglobin A1c) from medical records. Results: Using longitudinal growth curve modeling, stressful life events predicted greater psychological distress, poorer self-care behavior, and worse metabolic control in both cross-sectional and longitudinal (lagged) analyses. Cross-sectionally, many of these relations were stronger among older than younger adolescents. Self-care behavior partly mediated this association. Conclusion: Stressful life events are related to poor metabolic control—especially for older adolescents. A primary mechanism appears to be a lack of good self care. (PsycINFO Database Record (c) 2010 APA, all rights reserved)