Mean intrinsic tensile properties of stone groundwood fibers from softwood

Stone groundwood (SGW) is a fibrous matter commonly prepared in a high yield process, and mainly used for papermaking applications. In this work, the use of SGW fibers is explored as reinforcing element of polypropylene (PP) composites. Due to its chemical and superficial features, the use of coupling agents is needed for a good adhesion and stress transfer across the fiber-matrix interface. The intrinsic strength of the reinforcement is a key parameter to predict the mechanical properties of the composite and to perform an interface analysis. The main objective of the present work was the determination of the intrinsic tensile strength of stone groundwood fibers. Coupled and non-coupled PP composites from stone groundwood fibers were prepared. The influence of the surface morphology and the quality at interface on the final properties of the composite was analyzed and compared to that of fiberglass PP composites. The intrinsic tensile properties of stone groundwood fibers, as well as the fiber orientation factor and the interfacial shear strength of the current composites were determined

Complement Factor B Polymorphism and the Phenotype of Early Age-related Macular Degeneration.

Abstract Purpose: Age-related macular degeneration (AMD) has been associated with a number of polymorphisms in genes in the complement pathway. We examined the potential genotype-phenotype correlation of complement factor B (CFB) (R32Q) polymorphisms in Caucasian patients with AMD. Methods: Data from a Central European cohort of 349 patients with early AMD in at least one eye were analyzed for potential associations of the CFB (R32Q/rs641153) polymorphism with phenotypic features of early AMD. Early AMD was classified according to the International Classification and Grading System into predominant drusen size, largest drusen, drusen covered surface, central or ring-like location, peripheral drusen, and pigmentary changes. The potential association with single nucleotide polymorphisms on CFB (R32Q/rs641153) was evaluated for all patients, corrected for age, sex, and the polymorphisms of CFH (Y402H) and ARMS2 (A69S). Results: CFB (R32Q) polymorphisms showed a significant association with smaller drusen size (largest drusen ≤250 µm, p = 0.021, predominant drusen ≤125 µm, p = 0.016), with smaller surface covered by drusen (≤10%; p = 0.02), and with more frequent occurrence of peripheral drusen (p = 0.007). No association was found for pigmentary changes. Conclusions: The CFB (R32Q) polymorphism was associated with AMD characterized by small drusen only, and appeared to be protective of large drusen (OR 0.48/0.45) and of larger drusen covered area (OR 0.34). Furthermore, peripheral drusen were more frequently found (OR 2.27). This result supports the role of complement components and their polymorphisms in drusen formation and may enable a better understanding of AMD pathogenesis.

Stone-ground wood pulp-reinforced polypropylene composites: water uptake and thermal properties

Two of the drawbacks of using natural-based composites in industrial applications are thermal instability and water uptake capacity. In this work, mechanical wood pulp was used to reinforce polypropylene at a level of 20 to 50 wt. %. Composites were mixed by means of a Brabender internal mixer for both non-coupled and coupled formulations. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to determine the thermal properties of the composites. The water uptake behavior was evaluated by immersion of the composites in water until an equilibrium state was reached. Results of water absorption tests revealed that the amount of water absorption was clearly dependent upon the fiber content. The coupled composites showed lower water absorption compared to the uncoupled composites. The incorporation of mechanical wood pulp into the polypropylene matrix produced a clear nucleating effect by increasing the crystallinity degree of the polymer and also increasing the temperature of polymer degradation. The maximum degradation temperature for stone ground wood pulp–reinforced composites was in the range of 330 to 345 ºC

Tensile strength characteristics of polypropylene composites reinforced with stone groundwood fibers from softwood

The behavior of stone groundwood / polypropylene injection-molded composites was evaluated with and without coupling agent. Stone groundwood (SGW) is a fibrous material commonly prepared in a high yield process and mainly used for papermaking applications. In this work, the use of SGW fibers was explored as a reinforcing element of polypropylene (PP) composites. The surface charge density of the composite components was evaluated, as well as the fiber’s length and diameter inside the composite material. Two mixing extrusion processes were evaluated, and the use of a kinetic mixer, instead of an internal mixer, resulted in longer mean fiber lengths of the reinforcing fibers. On the other hand, the accessibility of surface hydroxyl groups of stone groundwood fibers was improved by treating the fibers with 5% of sodium hydroxide, resulting in a noticeable increase of the tensile strength of the composites, for a similar percentage of coupling agent. A new parameter called Fiber Tensile Strength Factor is defined and used as a baseline for the comparison of the properties of the different composite materials. Finally the competitiveness of stone groundwood / polypropylene / polypropylene-co-maleic anhydride system, which compared favorably to sized glass-fiber / polypropylene GF/PP and glass-fiber / polypropylene / polypropylene-co-maleic anhydride composite formulations, was quantified by means of the fiber tensile strength factor

Gain-of-function haplotype in the epithelial calcium channel TRPV6 is a risk factor for renal calcium stone formation.

The rate-limiting step of dietary calcium absorption in the intestine requires the brush border calcium entry channel TRPV6. The TRPV6 gene was completely sequenced in 170 renal calcium stone patients. The frequency of an ancestral TRPV6 haplotype consisting of three non-synonymous polymorphisms (C157R, M378V, M681T) was significantly higher (P = 0.039) in calcium stone formers (8.4%; derived = 502, ancestral = 46) compared to non-stone-forming individuals (5.4%; derived = 645, ancestral = 37). Mineral metabolism was investigated on four different calcium regimens: (i) free-choice diet, (ii) low calcium diet, (iii) fasting and (iv) after a 1 g oral calcium load. When patients homozygous for the derived haplotype were compared with heterozygous patients, no differences were found with respect to the plasma concentrations of 1,25-vitamin D, PTH and calcium, and the urinary excretion of calcium. In one stone-forming patient, the ancestral haplotype was found to be homozygous. This patient had absorptive hypercalciuria. We therefore expressed the ancestral protein (157R+378V+681T) in Xenopus oocytes and found a significantly enhanced calcium permeability when tested by a (45)Ca(2+) uptake assay (7.11 +/- 1.93 versus 3.61 +/- 1.01 pmol/min/oocyte for ancestral versus derived haplotype, P < 0.01). These results suggest that the ancestral gain-of-function haplotype in TRPV6 plays a role in calcium stone formation in certain forms of absorptive hypercalciuria.

Emotional and neuroendocrine regulation in very preterm and full-term infants at six months of age

Emotional and neuroendocrine regulation have been shown to be associated. However, results are inconsistent. This paper explores the functioning and relationships between these two systems in 54 healthy preterm and 25 full-term born infants at six months of age. Results showed significant differences between very preterm and full-term children in emotional intensity and regulation, as well as in neuroendocrine regulation. No evidence of an association between neuroendocrine and emotional regulations was found. Results suggest a possible delay in the maturation of the neuroendocrine system as well as in emotional regulation in very preterm infants.

Cognitive features in euthymic bipolar patients in old age.

OBJECTIVES: Studies of cognition in bipolar disorder (BD) have reported impairments in processing speed, working memory, episodic memory, and executive function, but they have primarily focused on young and middle-aged adults. In such studies, the severity of cognitive deficits increases with the duration of illness. Therefore, one would expect more pronounced deficits in patients with longstanding BD. The first aim of the present study was to determine the pattern and the magnitude of cognitive impairment in older euthymic BD patients. The second aim was to explore the interrelationship between these cognitive deficits and determine whether they reflect a single core impairment or the co-occurrence of independent cognitive deficits. METHODS: Twenty-two euthymic elderly BD patients and 22 controls, matched for gender, age, and education, underwent a comprehensive neuropsychological assessment. RESULTS: Compared to controls, BD patients had significantly reduced performance in processing speed, working memory, verbal fluency, and episodic memory, but not in executive function. Hierarchical regression analyses showed that verbal fluency and working memory impairments were fully mediated by changes in processing speed. This was not the case for the episodic memory dysfunction. CONCLUSION: The cognitive profile in older euthymic BD cases is similar to the one described in younger BD cohorts. Our results further suggest that impaired processing speed plays a major role in the cognitive changes observed in BD patients except for deficits in episodic memory, thus providing strong evidence that processing speed and episodic memory are two core deficits in elderly BD patients.

Point Mutations in the Monocarboxylate Transporter SLC16A12 Lead to Juvenile and Age-Related Cataract

Purpose: Previously we reported on a premature termination mutation in SLC16A12 that leads to dominant juvenile cataract and renal glucosuria. To assess the mutation rate and genotype-phenotype correlations of SLC16A12 in juvenile or age-related forms of cataract, we performed a mutation screen in cataract patients. Methods: Clinical data of approximately 660 patients were collected, genomic DNA was isolated and analyzed. Exons 3 to 8 including flanking intron sequences of SLC16A12 were PCR amplified and DNA sequence was determined. Selected mutations were tested by cell culture assays, in silico analysis and RT-PCR. Results: We found sequence alterations at a rate of approximately 1/75 patients. None of them was found in 360 control alleles. Alterations affect splice site and regulatory region but most mutations caused an amino acid substitution. The majority of the coding region mutations maps to trans-membrane domains. One mutation located to the 5'UTR. It affects translational efficiency of SLC16A12. In addition, we identified a cataract-predisposing SNP in the non-coding region that causes allele-specific splicing of the 5'UTR region. Conclusions: Altered translational efficiency of the solute carrier SLC16A12 and its allele-specific splicing strongly support a model of challenged homeostasis to cause various forms of cataract. In addition, the pathogenic property of the here reported sequence alterations is supported by the lack of known sequence variations within the coding region of SLC16A12. Due to the relatively high mutation rate, we suggest to include SLC16A12 in diagnostic cataract screening. Generally, our data recommend the assessment of regulatory sequences for diagnostic purposes.

Dépistage et prévention chez les aînés: quelles interventions proposer, à qui, et jusqu'à quel âge [Screening and prevention in the elderly: which interventions should be proposed, to whom, and up to what age?].

Recommendations on preventive services rarely mention how to apply them to older people. Even though general criteria (prevalence of disease, quality of screening tests) that influence screening's efficacy remain important, appropriateness of screening in older persons depends much more on individual criteria, such as comorbidity, functional status, and life expectancy. More than with any other age group, patients preferences regarding future investigation and treatment guide the clinical decision. This article focuses on primary and secondary prevention, and discusses specific criteria to consider in each patient. A table summarizes the appropriate recommendations.

Age-associated modulations of cerebral oscillatory patterns related to attention control.

Visual attention depends on bottom-up sensory activation and top-down attentional guidance. Although aging is known to affect sensory processing, its impact on the top-down control of attention remains a matter of debate. We investigated age-related modulations of brain oscillatory activity during visual attention using a variant of the attention network test (ANT) in 20 young and 28 elderly adults. We examined the EEG oscillatory responses to warning and target signals, and explored the correlates of temporal and spatial orienting as well as conflict resolution at target presentation. Time-frequency analysis was performed between 4 and 30Hz, and the relationship between behavioral and brain oscillatory responses was analyzed. Whereas temporal cueing and conflict had similar reaction time effects in both age groups, spatial cueing was more beneficial to older than younger subjects. In the absence of cue, posterior alpha activation was drastically reduced in older adults, pointing to an age-related decline in anticipatory attention. Following both cues and targets, older adults displayed pronounced motor-related activation in the low beta frequency range at the expense of attention-related posterior alpha activation prominent in younger adults. These findings support the recruitment of alternative motor-related circuits in the elderly, in line with the dedifferentiation hypothesis. Furthermore, older adults showed reduced midparietal alpha inhibition induced by temporal orienting as well as decreased posterior alpha activation associated with both spatial orienting and conflict resolution. Altogether, the results are consistent with an overall reduction of task-related alpha activity in the elderly, and provide functional evidence that younger and older adults engage distinct brain circuits at different oscillatory frequencies during attentional functions.

Innovation and firm growth: Does firm age play a role?

This paper explores the relationship between firm growth, innovation and firm age. We hypothesize that young firms undertake riskier innovation activities and are more oriented towards employment growth than towards harvesting returns in the form of sales growth. Using an extensive sample of Community Innovation Survey for the period 2004-2010, we apply quantile regressions and a Heckman sample selection technique to study the impact of R&D activities on firm growth according to firm age. Our results show that R&D intensity is positively associated with firm growth. However, for young firms R&D shows an increasing influence across the quantiles, while for old firms R&D shows a stable or perhaps decreasing effect over the quantiles. Firm age shows a significant negative impact among young firms, while for the sample of old firms the impact of firm age becomes non-significant. Our Heckman estimations show the evolution of the impact of the R&D on firm growth confirming a significant impact on sales and productivity growth, while the impact is negligible for employment growth. Keywords: firm age, firm growth, innovation, quantile regression. JEL CODES: L25, L20