729 research outputs found

    The Influence of Varying Hydrogen Ion and Alumina Concentrations on the Strength Characteristics of Handsheets Made in the Presence of Locust Bean Gum

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    Mannogalactans and particularly locust bean gum are used for a wide variety of applications. They serve as thickening agents and emulsifiers for foodstuffs, in sizing as well as finishing yarns and in creaming rubber latex. The papermaking industry is the largest user of mannogalactans. Here they are used in kraft grades, sulphite, book papers, coating raw stock, offset and printing grades, bonds, ledgers, and other fine papers and also in newsprint and other groundwood sheets. Locust bean gum and methylcellulose are effective as deflocculating agents and are said to surpass the performance of deacetylated karaya gum. Both hydration film and electrokinetic potential on the fiber are involved in fiber flocculation and dispersion (1). Locust bean gum responds to a minimum extent when used with hardwoods. However, mixed hardwood-softwood sheets, produced with a relatively high percentage of hardwood, still maintain appreciable strength properties when locust bean gum is used. Gray and Van den Akker (1) found that an addition of one percent locust bean gum greatly reduced the friction of high consistency stock in pipes. Mannogalactans, when used as beater additives will tend to increase the retention of some types of fillers. Usually the stock is beaten to maximum tear before addition of the gum. An automatic continuous dispenser has been developed (18), that supplies cooked additive to paper-machines in quantities up to 20,000 gallons per day

    Positive Voltage Hazard to EMU Crewman from Currents through Plasma

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    This paper describes the model of the EMU with a human body in the circuit that has been used by NASA to evaluate the low positive voltage hazard. The model utilizes the electron collection characterization from on orbit Langmuir probe data as representative of electron collection to a positive charged surface with a wide range of on orbit plasma temperature and density conditions. The data has been unified according to non-linear theoretical temperature and density variation of the electron saturated probe current collection theory and used as a model for the electron collection at EMU surfaces. Vulnerable paths through the EMU connecting through the crewman s body have been identified along with electrical impedance of the exposed body parts. The body impedance information is merged with the electron collection characteristics in circuit simulation software (SPICE). The assessment shows that currents can be on the order of 20 mA for a 15 V exposure and of order 4 mA at 3V. These currents formally violate NASA protocol for electric current exposures however the human factors associated with subjective consequences of noxious stimuli from low voltage exposure during the stressful conditions of EVA are an area of active inquiry

    In vivo CHI3L1 (YKL-40) expression in astrocytes in acute and chronic neurological diseases

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    <p>Abstract</p> <p>Background</p> <p>CHI3L1 (YKL-40) is up-regulated in a variety of inflammatory conditions and cancers. We have previously reported elevated CHI3L1 concentration in the cerebrospinal fluid (CSF) of human and non-human primates with lentiviral encephalitis and using immunohistochemistry showed that CHI3L1 was associated with astrocytes.</p> <p>Methods</p> <p>In the current study CHI3L1 transcription and expression were evaluated in a variety of acute and chronic human neurological diseases.</p> <p>Results</p> <p>ELISA revealed significant elevation of CHI3L1 in the CSF of multiple sclerosis (MS) patients as well as mild elevation with aging. <it>In situ </it>hybridization (ISH) showed CHI3L1 transcription mostly associated with reactive astrocytes, that was more pronounced in inflammatory conditions like lentiviral encephalitis and MS. Comparison of CHI3L1 expression in different stages of brain infarction showed that YKL40 was abundantly expressed in astrocytes during acute phases and diminished to low levels in chronic infarcts.</p> <p>Conclusions</p> <p>Taken together, these findings demonstrate that CHI3L1 is induced in astrocytes in a variety of neurological diseases but that it is most abundantly associated with astrocytes in regions of inflammatory cells.</p

    An Operational Computational Terminal Area PBL Prediction System

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    There are two fundamental goals of this research project. The first and primary goal is to develop a prognostic system which could satisfy the operational weather prediction requirements of the meteorological subsystem within the Aircraft Vortex Spacing System (AVOSS). The secondary goal is to perform indepth diagnostic analyses of the meteorological conditions affecting the Memphis field experiment held during August 1995. These two goals are interdependent because a thorough understanding of the atmospheric dynamical processes which produced the unique meteorology during the Memphis deployment will help us design a prognostic system for the planetary boundary layer (PBL) which could be utilized to support the meteorological subsystem within AVOSS. The secondary goal occupied much of the first year of the research project. This involved extensive data acquisition and indepth analyses of a spectrum of atmospheric observational data sets. Concerning the primary goal, the first part of the four-stage prognostic system in support of AVOSS entitled: Terminal Area PBL Prediction System (TAPPS) was also formulated and tested in a research environment during 1996. We describe this system, and the three stages which are planned to follow. This first part of a software system designed to meet the primary goal of this research project is relatively inexpensive to implement and run operationally

    Dietary Methionine Restriction Regulates Liver Protein Synthesis and Gene Expression Independently of Eukaryotic Initiation Factor 2 Phosphorylation in Mice

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    Background: The phosphorylation of eukaryotic initiation factor 2 (p-eIF2) during dietary amino acid insufficiency reduces protein synthesis and alters gene expression via the integrated stress response (ISR).Objective: We explored whether a Met-restricted (MR) diet activates the ISR to reduce body fat and regulate protein balance.Methods: Male and female mice aged 3-6 mo with either whole-body deletion of general control nonderepressible 2 (Gcn2) or liver-specific deletion of protein kinase R-like endoplasmic reticulum kinase (Perk) alongside wild-type or floxed control mice were fed an obesogenic diet sufficient in Met (0.86%) or an MR (0.12% Met) diet for ≤5 wk. Ala enrichment with deuterium was measured to calculate protein synthesis rates. The guanine nucleotide exchange factor activity of eIF2B was measured alongside p-eIF2 and hepatic mRNA expression levels at 2 d and 5 wk. Metabolic phenotyping was conducted at 4 wk, and body composition was measured throughout. Results were evaluated with the use of ANOVA (P < 0.05).Results: Feeding an MR diet for 2 d did not increase hepatic p-eIF2 or reduce eIF2B activity in wild-type or Gcn2-/- mice, yet many genes transcriptionally regulated by the ISR were altered in both strains in the same direction and amplitude. Feeding an MR diet for 5 wk increased p-eIF2 and reduced eIF2B activity in wild-type but not Gcn2-/- mice, yet ISR-regulated genes altered in both strains similarly. Furthermore, the MR diet reduced mixed and cytosolic but not mitochondrial protein synthesis in both the liver and skeletal muscle regardless of Gcn2 status. Despite the similarities between strains, the MR diet did not increase energy expenditure or reduce body fat in Gcn2-/- mice. Finally, feeding the MR diet to mice with Perk deleted in the liver increased hepatic p-eIF2 and altered body composition similar to floxed controls.Conclusions: Hepatic activation of the ISR resulting from an MR diet does not require p-eIF2. Gcn2 status influences body fat loss but not protein balance when Met is restricted

    Mental practice with motor imagery in stroke recovery: Randomized controlled trial of efficacy

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    This randomized controlled trial evaluated the therapeutic benefit of mental practice with motor imagery in stroke patients with persistent upper limb motor weakness. There is evidence to suggest that mental rehearsal of movement can produce effects normally attributed to practising the actual movements. Imagining hand movements could stimulate restitution and redistribution of brain activity, which accompanies recovery of hand function, thus resulting in a reduced motor deficit. Current efficacy evidence for mental practice with motor imagery in stroke is insufficient due to methodological limitations. This randomized controlled sequential cohort study included 121 stroke patients with a residual upper limb weakness within 6 months following stroke (on average &lt;3 months post-stroke). Randomization was performed using an automated statistical minimizing procedure. The primary outcome measure was a blinded rating on the Action Research Arm test. The study analysed the outcome of 39 patients involved in 4 weeks of mental rehearsal of upper limb movements during 45-min supervised sessions three times a week and structured independent sessions twice a week, compared to 31 patients who performed equally intensive non-motor mental rehearsal, and 32 patients receiving normal care without additional training. No differences between the treatment groups were found at baseline or outcome on the Action Research Arm Test (ANCOVA statistical P&thinsp;=&thinsp;0.77, and effect size partial &eta;2&thinsp;=&thinsp;0.005) or any of the secondary outcome measures. Results suggest that mental practice with motor imagery does not enhance motor recovery in patients early post-stroke. In light of the evidence, it remains to be seen whether mental practice with motor imagery is a valid rehabilitation technique in its own right

    Loss of Nmp4 optimizes osteogenic metabolism and secretion to enhance bone quality

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    A goal of osteoporosis therapy is to restore lost bone with structurally sound tissue. Mice lacking the transcription factor Nuclear Matrix Protein 4 (Nmp4, Zfp384, Ciz, ZNF384) respond to several classes of osteoporosis drugs with enhanced bone formation compared to wild type (WT) animals. Nmp4-/- mesenchymal stem/progenitor cells (MSPCs) exhibit an accelerated and enhanced mineralization during osteoblast differentiation. To address the mechanisms underlying this hyper-anabolic phenotype, we carried out RNA-sequencing and molecular and cellular analyses of WT and Nmp4-/- MSPCs during osteogenesis to define pathways and mechanisms associated with elevated matrix production. We determined that Nmp4 has a broad impact on the transcriptome during osteogenic differentiation, contributing to the expression of over 5,000 genes. Phenotypic anchoring of transcriptional data was performed for the hypothesis-testing arm through analysis of cell metabolism, protein synthesis and secretion, and bone material properties. Mechanistic studies confirmed that Nmp4-/- MSPCs exhibited an enhanced capacity for glycolytic conversion- a key step in bone anabolism. Nmp4-/- cells showed elevated collagen translation and secretion. Expression of matrix genes that contribute to bone material-level mechanical properties were elevated in Nmp4-/- cells, an observation that was supported by biomechanical testing of bone samples from Nmp4-/- and WT mice. We conclude that loss of Nmp4 increases the magnitude of glycolysis upon the metabolic switch, which fuels the conversion of the osteoblast into a super-secretor of matrix resulting in more bone with improvements in intrinsic quality

    Vitamin D levels and perinatal depressive symptoms in women at risk: a secondary analysis of the mothers, omega-3, and mental health study

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    Abstract Background Vitamin D insufficiency may be associated with depressive symptoms in non-pregnant adults. We performed this study to evaluate whether low maternal vitamin D levels are associated with depressive symptoms in pregnancy. Methods This study was a secondary analysis of a randomized trial designed to assess whether prenatal omega-3 fatty acid supplementation would prevent depressive symptoms. Pregnant women from Michigan who were at risk for depression based on Edinburgh Postnatal Depression Scale Score or history of depression were enrolled. Participants completed the Beck Depression Inventory (BDI) and Mini International Neuropsychiatric Interview at 12–20 weeks, 26–28 weeks, 34–36 weeks, and 6–8 weeks postpartum. Vitamin D levels were measured at 12–20 weeks (N = 117) and 34–36 weeks (N = 112). Complete datasets were available on 105 subjects. Using regression analyses, we evaluated the relationship between vitamin D levels with BDI scores as well as with MINI diagnoses of major depressive disorder and generalized anxiety disorder. Our primary outcome measure was the association of maternal vitamin D levels with BDI scores during early and late pregnancy and postpartum. Results We found that vitamin D levels at 12–20 weeks were inversely associated with BDI scores both at 12—20 and at 34–36 weeks’ gestation (P < 0.05, both). For every one unit increase in vitamin D in early pregnancy, the average decrease in the mean BDI score was .14 units. Vitamin D levels were not associated with diagnoses of major depressive disorder or generalized anxiety disorder. Conclusions In women at risk for depression, early pregnancy low vitamin D levels are associated with higher depressive symptom scores in early and late pregnancy. Future investigations should study whether vitamin D supplementation in early pregnancy may prevent perinatal depressive symptoms. Trial registration https://clinicaltrials.gov/ Registration Number: NCT00711971http://deepblue.lib.umich.edu/bitstream/2027.42/134615/1/12884_2016_Article_988.pd
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