Role of polyacrylate starch copolymer in water sorption

Water sorbence by saponified polyacrylonitrile-grafted polysaccharides was studied in relation to practical end uses. Graft copolymers prepared from wheat flour, corn flour, cotton wool, and rayon fibers swelled to a gel, exhibiting a 10- to 20-fold increase in sorbency over the starting materials. A further enhanced water capacity was obtained when homopolymer was not removed. Soaking the wheat flour copolymer in salts or dilute mineral acid nullified the enhanced water sorbence, which could be reversible restored by neutralization of acrylic acid functions with alkali. Swelling the copolymer in aqueous D-glucose did not impair its water capacity. The mechanism of swelling to a gel appears to involve electrolyte osmotic pressure generated by a Donnan equilibrium. Grafting starch elevated its heat of water vaporization above that of pure water, and increased its capacity to absorb water from ethanol-water vapor at 40° above that of native starch. At higher temperatures, however, the dehydrating capacity decreased to that of native flour.     

Older adults’ experiences of home maintenance issues and opportunities to maintain ageing in place

This paper addresses the question of how older adults’ experiences of home maintenance issues shape their opportunities to maintain ageing in place. We explore this question through a case study of ageing in place on Waiheke Island, near Auckland, New Zealand. We draw on in-depth interviews with 28 older adults aged 65 to 94, as well as participatory photo elicitation interviews and research journals conducted with 11 of these participants. We argue that older adults’ diverse personal circumstances and wider social contexts influence how home maintenance concerns are understood and addressed. We find that maintenance issues may cause stress and anxiety, thereby rupturing affective ties to place, limiting access to preferred identities and reducing well-being. Yet many feel connected to social networks and gain a positive sense of self and autonomy through participation in home maintenance tasks. Ultimately, how older adults experience their home maintenance issues influences their opportunities to maintain ageing in place.     

Characterization of nitrogen-fixing cyanobacteria in the Brazilian Amazon floodplain

The diversity of the free-living nitrogen-fixing cyanobacterial community in the floodplain sediments along the Solimões and Amazon Rivers and some of their tributaries (Japurá, Negro and Madeira) was investigated. Five cyanobacterial genera were morphologically identified, four of which (Nostoc, Calothrix, Cylindrospermum and Fischerella) have not previously been isolated from the Brazilian Amazon floodplain. Nostoc strains were the most commonly found heterocyst-forming cyanobacteria. Five strains (N. muscorum CENA18 and CENA61, N. piscinale CENA21, Cylindrospermum sp. CENA33 and Fischerella sp. CENA19) were selected for growth measurement, ability to fix N₂ and phylogenetic analysis, based on their widespread distribution and morphological distinction. Molecular analyses employing 16S rRNA sequences indicated that some of the isolates may represent novel cyanobacterial species. Dinitrogen fixed by these strains was measured indirectly as acetylene reduction activity and ranged from 11.5 to 22.2 nmol C₂H₄ μg Chl a⁻¹ h⁻¹. These results provide evidence of widespread and importance of nitrogen-fixing cyanobacteria as a source of N inputs in the Amazonian ecosystem.     

Complications of home hemodialysis

Home hemodialysis is regaining popularity as a treatment choice for end-stage kidney disease. This trend is fueled by numerous reports of better survival and improved quality of life with primarily home-based more frequent and/or longer hours of hemodialysis. Home hemodialysis in the contemporary era is generally very safe. Advances in machine technology have reduced technical complications and longer and more frequent treatments have reduced the risk of hypotension and cardiovascular instability. A successful home hemodialysis program must focus on patient safety to prevent serious hemorrhage from needle dislodgement and enable an aseptic cannulation technique. In addition, vigilance in relation to machine maintenance procedures and attention to water quality are key skills that patients must acquire for optimal outcomes. The possibility of increased septic events with longer and more frequent hemodialysis regimens performed in the home, the long-term psychosocial effects of home hemodialysis, and the best methods for maintaining compliance of patients in the long term are of particular contemporary interest.     

Effect of physical aging on the impact retention and heat distortion temperature of vinyl products

Physical properties of polymers change with time. Exposure of amorphous polymers to high temperature will reduce their free volume, which in turn increases their heat distortion temperature and decreases their impact strength. Heat distortion additives, such as poly(α-methylstyrene-styrene-acrylonitrile) (AMSAN), enhance the glass transition temperature of PVC and help in the impact retention of the polymer by slowing down the aging process. In this paper, physical aging of PVC is explored, effect of annealing time and temperature on the impact strength and HDT is reported, and conclusions regarding the retention of impact resistance upon aging are drawn.     

Causal Effects of Aroma Compounds on Royal Gala Apple Flavours

Volatile flavour compounds produced by Royal Gala apple have been identified by GC-MS. Major components were 2-methylbutyl acetate, butyl acetate, hexyl acetate, butanol, 2-methylbutanol and hexanol. Odour-port evaluation of the components separated by GC indicated that the first four compounds were important contributors to the aroma and flavour. Use of analytical sensory panels revealed that 2-methylbutyl acetate, butanol and hexyl acetate had the greatest causal effect on those aroma and flavour attributes considered important for Royal Gala apples.     

Scanning electrochemical microscopy of the photosynthetic reaction center of Rhodobacter sphaeroides in different environmental systems

The present work uses a scanning electrochemical microscopy technique to study systems containing the membrane-bound reaction center protein (RC) from the purple photosynthetic bacteria Rhodobacter spheroides to chromatophores (spherical reorganization of cell membrane following its mechanical rupture) and liposomes (reconstituted membrane systems at lower degree of complexity). Scanning electrochemical microscopy is a useful tool to investigate redox processes involving a RC, because the effective heterogeneous rate constants for the redox reaction with different mediators can be measured. The technique is also able to provide information on the role of the outer cell membrane permeation on the kinetics of the electron-transfer processes and to obtain more insight into the nature of the species involved.     

As-grown textured zinc oxide films by ion beam treatment and magnetron sputtering

This work presents as-grown textured ZnO:Al films by rf magnetron sputtering initiated by pre-treatment of glass substrate with mixed argon and oxygen ions. A 650 nm thick of this film exhibits surface texture features with lateral size around 500 nm; the resistivity is below 5 × 10⁻⁴ Ω · cm and the transparency in the near-infrared spectral range is high (> 80% at 1000 nm). Microcrystalline silicon thin film solar cells grown on the textured glass exhibit excellent light trapping effect with a short circuit current density of 18.2 mA/cm².     

High‐Sensitivity Real‐Time Analysis of Nanoparticle Toxicity in Green Fluorescent Protein‐Expressing Zebrafish

Gold nanoparticles (AuNP) show great potential for diagnostic and therapeutic application in humans. A great number of studies have tested the cytotoxicity of AuNP using cell culture. There is, however, an urgent need to test AuNP in vertebrate animal models that interrogate biodistribution and complex biological traits like organ development, whole body metabolism, and cognitive function. The sheer number of different compounds precludes the use of small rodent model for initial screening. The extended fish embryo test (FET) is used here to bridge the gap between cell culture and small animal models. A study on the toxicity of ultrasmall AuNP in wild type and transgenic zebrafish is presented. FET faithfully reproduce all important findings of a previous study in HeLa cells and add new important information on teratogenicity and hepatotoxicity that could not be gained from studying cultured cells.