Elucidation of the fine structure of poly(vinyl chloride) by hydrogenation and 13C-NMR analysis of low molecular weight fractions

The following experiment was performed based on the assumption that the characteristic structural features of high molecular weight poly(vinyl chloride) (PVC) should be present to the same extent in its low molecular weight fractions. Two PVC fractions of molecular weight, 1500 and 800, respectively, (0.14% of total polymer) were isolated from bulk PVC (M_n 32,000) by extraction with methanol. This extract was transformed into paraffins by a new hydrogenation method using an excess of Raney nickel in order to facilitate identification. ¹³C-NMR spectral data of the paraffins showed that almost 2 out of 1000 carbon atoms were linked to a side chain with more than five carbon atoms, and 5 out of 1000 carbon atoms were methyl branched. Gas chromatography-mass spectrometry (GC–MS) analyses confirmed that the low molecular weight paraffins consisted of a sequence of even-numbered homologs. These findings suggest indirectly that the surprisingly low degradation temperature of PVC is due to the arrangement of the chlorine atoms rather than to the branching of the alkyl chain.     

Social competence and psychiatric diagnosis.

It was hypothesized that symptoms reflect a patient's social competence or maturity level and that this level is related to the diagnosis he receives. Symptom scales based on empirical relations between symptoms and competence levels were constructed for 3 spheres of functioning: thought, affect, and action. Results obtained with 504 psychiatric patients showed that: (1) placement on each symptom scale was significantly related to diagnosis, and (2) patients who could be rated on all 3 scales showed consistent placement across scales. The latter finding was interpreted as indicating that the maturity dimension is a pervasive one, thus lending further support to the view that maturity plays an important role in the process of diagnosis. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Biotransformation of 2-Benzoxazolinone to 2-Amino-(3<Emphasis Type="Italic">H</Emphasis>)-Phenoxazin-3-one and 2-Acetylamino-(3<Emphasis Type="Italic">H</Emphasis>)-Phenoxazin-3-one in Soil

An alternative to the use of synthetic pesticides is to exploit the natural defense chemicals produced by cereals. An important class of allelochemicals is cyclic hydroxamic acids and related benzoxazolinones. A prolonged degradation experiment of the allelochemical compound from rye 2-benzoxazolinone (BOA) was carried out for up to 90 d at 15°C at three different concentration levels, 3, 3000, and 30,000 nmol BOA· g soil^–1, respectively, in a sandy loam soil. Two main degradation products, 2-amino-(3H)-phenoxazin-3-one (APO) and 2-acetylamino-(3H)-phenoxazin-3-one (AAPO), were identified and quantified by LC-ESI-MS-MS. The half-life of BOA increased with higher levels of BOA added to the soil. Half-lives of BOA, APO, and AAPO were determined by fitting a single first-order model to the degradation data. Half-life of BOA was determined to be 0.6 d in the 3 nmol BOA g soil^–1 treatment. Half-lives of BOA, APO, and AAPO were 3.1, 2.7, and 2.1 d, respectively, in the 3000 nmol BOA· g soil^–1 treatment. In the 30,000 nmol BOA· g soil^–1 treatment, the half-lives were 31 d for BOA and 45 d for APO. The microbial community structure was not affected by addition of BOA to the soil as investigated by analysis of signature fatty acids. The results suggest that the exploitability of BOA for crop protection is dependent on the existing concentration of BOA in the soil and the timing of incorporation of hydroxamic acid synthesizing crops into the soil.     

Paired helical filaments (PHFs) are a family of single filament structures with a common helical turn period: negatively stained PHF imaged by TEM and measured before and after sonication, deglycosylation, and dephosphorylation

Isolated paired helical filaments (PHFs) were visualized on glutaraldehyde vapor-treated thin approximately 10-nm thick indirect carbon films using high-resolution transmission electron microscopy (TEM) and the negative stain, phosphotungstate acid (PTA) at near neutral pH of 6.8. PHF preparations were prepared with and without 1 minute of sonication. These same PHF were also deglycosylated with endoglycosidase F/N-glycosidase F for 1 hour or the PHF were dephosphorylated with PP-2A for 1 hour. The negatively stained PHF filaments were quantitatively studied by measuring their wide regions (W) their thin regions (T) and their helical turn period (L) and these separate parameters were averaged for each filament. In the unsonicated PHF preparation there were PHF, cylindrical filaments with periodic thin regions (CF-PT), cylindrical filaments (CF), as well as 2.0-nm tau polymer-like filaments. The CF-PT were characterized by W, T, and L measurements and the CF were characterized by diameter measurements. The paired helical filament model proposed by Kidd (1963, Nature 197:192-193) of two approximately 10 nm filaments twisting around each other every approximately 80 nm with a thin region of 10 nm and a wide region of 25 nm does not correspond to the PHF structures found. None of the PHF we observed were composed of a pair of filaments and all of the PHF appear to be a single filament. The wide regions ranged from 12.5-27 nm and the thin regions ranged from 4.5-12.3 nm. The helical turn periods ranged from 76-85 nm and were generally about 80 nm. Only the helical turn period of approximately 80 nm was a common property of the whole family of PHF structures. The CF-PT appear to be a PHF precursor filament. Deglycosylation of the PHF and CF-PT reduced their sizes by 0.5-0.6 nm and 0.7-1.0 nm, respectively, and the right-hand helicity of the PHF was lost after deglycosylation. Dephosphorylation with PP-2A reduced the PHF wide regions by 6.0 nm and the thin regions by 2.6 nm.     

Community assessment of availability, consumption, and cultural acceptability of food sources of (pro)vitamin A: toward the development of a dietary intervention among preschool children in rural Burkina Faso

BACKGROUND: Vitamin A deficiency remains a public health problem in Burkina Faso and elsewhere in the developing world. Dietary diversification is a promising strategy that needs to be explored to strengthen the country's ongoing supplementation program. OBJECTIVE: The purpose of this study was to identify locally available and acceptable (pro)vitamin A-rich foods to be included in a dietary intervention addressing vitamin A deficiency in children aged six months to three years. METHODS: A food ethnographic study combining recall methods, observation, and focused group discussion was conducted in the dry and rainy seasons. Thirty-five mother-child pairs were randomly selected and included in the study. RESULTS: The dietary pattern of children was characterized by low diversity with extremely low energy and vitamin A intake in both seasons. The study identified the availability of numerous (pro)vitamin A-rich foods, but these foods are either not consumed or consumed by few in low amounts and/or in low frequencies. The main constraining factors identified are related to financial accessibility (for liver), seasonal availability (for egg, milk, mango, papaya, and green leafy vegetables), and beliefs related to consumption and preparation (for green leafy vegetables). However, the study also revealed that the study population associated all identified (pro)vitamin A-rich foods with positive attributes such as health, strength, and vitamin richness, which might offer an entry point for designing and implementing dietary interventions. CONCLUSIONS: Based on the findings of this formative research, intervention strategies with mango and liver are proposed to improve the vitamin A intake and status of children in the rural areas of Burkina Faso.     

Optical Detections From Worn and Unworn Titanium Compound Surfaces

Wear-induced roughness in terms of grooves, sharp ridges, and edges leads to scattering of the reflected light and leads unavoidably to a reduction of the optical signals in a standard specular geometry. However, by using a double-layer system consisting of titanium aluminum nitride (TiAlN) on top of a titanium nitride (TiN) layer we obtain an increase in the reflected light as a result of wear. The relative change of reflectance of light from the tribological TiAlN coated surface to the underlying layer of TiN is similar for non-worn surfaces and for surfaces exposed to an abrasive wear process. The induced roughness reduces the signals from worn samples, in a standard specular geometry, by up to 30% compared with unworn samples. Our model system of TiAlN coatings on top of ‘optical’ signal layers of TiN deposited on a 100Cr6 steel substrate, was exposed to a reciprocating wear process with up to 10⁵ repetitive cycles in a linear tribometer. The worn TiAlN layers of thicknesses up to 3 μm, with strongly developed grooves and ridges, were subsequently used for the reflectance measurements. The results show that optical reflectance monitoring is a potential technique for intelligent determination of a residual thickness of realistic tribological coatings prior to complete wear.     

3D‐Printing of High‐κ Thiol‐Ene Resins with Spiro‐Orthoesters as Anti‐Shrinkage Additive

Tri(ethylene glycol) divinyl ether and the spiro‐orthoester 2‐((allyloxy)methy)‐1,4,6‐trioxospiro[4.4]nonane can be formulated in different ratios and crosslinked by thiol‐ene reactions. The spiro‐orthoester is used as anti‐shrinkage additive, enabling shrinkage reduction of up to 39%. Addition of a radical photoinitiator for the thiol‐ene reaction and a cationic photoinitiator for the double ring‐opening of the spiro‐orthoester enables dual‐curing for application in 3D‐printing. The formulation free of the spiro‐orthoester shows gelation during the printing process and, correspondingly, low resolution. The formulations containing the spiro‐orthoester exhibit higher resolutions in the range of 50 µm. The resins containing mixtures of tri(ethylene glycol) divinyl ether and the spiro‐orthoester show permittivities as high as 10⁴. The dielectric loss factor of the resins is in the range of 0.5–7.6, and the conductivity in the range of 1.3?10^?11 to 2.0?10^?11 S cm^?1. These high‐κ materials can be 3D‐printed by digital light processing for the next generation of electronic materials.     

Effects of Cancer Presence and Therapy on the Platelet Proteome

Platelets are involved in tumor angiogenesis and cancer progression. Previous studies indicated that cancer could affect platelet content. In the current study, we investigated whether cancer-associated proteins can be discerned in the platelets of cancer patients, and whether antitumor treatment may affect the platelet proteome. Platelets were isolated from nine patients with different cancer types and ten healthy volunteers. From three patients, platelets were isolated before and after the start of antitumor treatment. Mass spectrometry-based proteomics of gel-fractionated platelet proteins were used to compare patients versus controls and before and after treatment initiation. A total of 4059 proteins were detected, of which 50 were significantly more abundant in patients, and 36 more in healthy volunteers. Eight of these proteins overlapped with our previous cancer platelet proteomics study. From these data, we selected potential biomarkers of cancer including six upregulated proteins (RNF213, CTSG, PGLYRP1, RPL8, S100A8, S100A9) and two downregulated proteins (GPX1, TNS1). Antitumor treatment resulted in increased levels of 432 proteins and decreased levels of 189 proteins. In conclusion, the platelet proteome may be affected in cancer patients and platelets are a potential source of cancer biomarkers. In addition, we found in a small group of patients that anticancer treatment significantly changes the platelet proteome.     

Mycotoxin exposure and human cancer risk: A systematic review of epidemiological studies

In recent years, there has been an increasing interest in investigating the carcinogenicity of mycotoxins in humans. This systematic review aims to provide an overview of data linking exposure to different mycotoxins with human cancer risk. Publications (2019 and earlier) of case–control or longitudinal cohort studies were identified in PubMed and EMBASE. These articles were then screened by independent reviewers and their quality was assessed according to the Newcastle–Ottawa scale. Animal, cross‐sectional, and molecular studies satisfied criteria for exclusion. In total, 14 articles were included: 13 case–control studies and 1 longitudinal cohort study. Included articles focused on associations of mycotoxin exposure with primary liver, breast, and cervical cancer. Overall, a positive association between the consumption of aflatoxin‐contaminated foods and primary liver cancer risk was verified. Two case–control studies in Africa investigated the relationship between zearalenone and its metabolites and breast cancer risk, though conflicting results were reported. Two case–control studies investigated the association between hepatocellular carcinoma and fumonisin B1 exposure, but no significant associations were observed. This systematic review incorporates several clear observations of dose‐dependent associations between aflatoxins and liver cancer risk, in keeping with IARC Monograph conclusions. Only few human epidemiological studies investigated the associations between mycotoxin exposures and cancer risk. To close this gap, more in‐depth research is needed to unravel evidence for other common mycotoxins, such as deoxynivalenol and ochratoxin A. The link between mycotoxin exposures and cancer risk has mainly been established in experimental studies, and needs to be confirmed in human epidemiological studies to support the evidence‐based public health strategies.