330 research outputs found

    Phytoglycogen nanoparticles : nature-derived superlubricants

    Full text link
    Phytoglycogen nanoparticles (PhG NPs), a single-molecule highly branched polysaccharide, exhibit excellent water retention, due to the abundance of close-packed hydroxyl groups forming hydrogen bonds with water. Here we report lubrication properties of close-packed adsorbed monolayers of PhG NPs acting as boundary lubricants. Using direct surface force measurements, we show that the hydrated nature of the NP layer results in its striking lubrication performance, with two distinct confinement-controlled friction coefficients. In the weak- to moderate-confinement regime, when the NP layer is compressed down to 8% of its original thickness under a normal pressure of up to 2.4 MPa, the NPs lubricate the surface with a friction coefficient of 10–3. In the strong-confinement regime, with 6.5% of the original layer thickness under a normal pressure of up to 8.1 MPa, the friction coefficient was 10–2. Analysis of the water content and energy dissipation in the confined NP film reveals that the lubrication is governed by synergistic contributions of unbound and bound water molecules, with the former contributing to lubrication properties in the weak- to moderate-confinement regime and the latter being responsible for the lubrication in the strong-confinement regime. These results unravel mechanistic insights that are essential for the design of lubricating systems based on strongly hydrated NPs

    Effect of carbon and nitrogen sources and carbon-to-nitrogen ratio on production of Exserohilum longirostratum.

    Get PDF
    The effects of carbon and nitrogen sources and the carbon-to-nitrogen ratio on the growth and sporulation of Exserohilum longirostratum were evaluated. Rice flour and malt extracts as the carbon and nitrogen sources, respectively, produced the greatest amount of mycelium. Sources that produced the most biomass were chosen as carbon and nitrogen sources in a C:N ratio test. However, in further experiments, glucose was chosen as the carbon source for the C:N ratio test because rice flour was found to be easily contaminated. Under the C:N ratio test (fixed carbon test), the highest spore production was obtained with a 5:1 ratio (4.78 × 106 spores/mL) and the highest biomass production was obtained with a 7.5:1 ratio (4.66 g/100 mL). In the fixed nitrogen test, 7.5:1 ratio provided the greatest output (4.08 × 106 spores/mL) whereas a 5:1 ratio produced the most biomass (4.33 g/100 mL). Meanwhile, the control which consisted of V8 agar without additional carbon and nitrogen source produced 1.07 × 106 spores/mL. These results provide information on the influence of carbon and nitrogen source and the C:N ratio that can be used in media for optimum growth and spore yield

    Growth, physiological and biochemical responses of Malaysia rice cultivars to water stress

    Get PDF
    The response of water deficit on rice plants varies substantially according to cultivars. Drought tolerant cultivars possess better morphological, physiological and biochemical adaptation to reduce water availability. An experiment involving water stress on rice varieties was carried out under rain shelter to examine the morphological changes (leaf rolling, root depth), stomatal responses and biochemical processes (proline and peroxidase accumulation) of five different local rice varieties. These varieties were selected based on their drought tolerant potential from an earlier varietal screening trial. The varieties were taken from both traditional (Muda, Jawi Lanjut and newly breed commercial varieties, MR 84, MR219 and MR 220) obtained from Genebank, MARDI Research Station, Seberang Prai, Kepala Batas, Pulau Pinang. These varieties were exposed to two different water regimes; water stress by withholding water and well watered condition (control). The experiment was carried out in a Complete Randomized Design (CRD) with 4 replicates. Water stress plants exhibited lower growth rate with obvious variation among rice varieties on the sensitivity to water stress. Meanwhile, the overall sensitivity of the varieties to water stress was ranked in the order; MR220>Muda>MR84>MR219>Jawi Lanjut. Water deficit decreased stomatal conductance, relative water content and root depth while peroxidase activities and proline accumulation were increased in rice grown under water stress treatment

    Corrosion of One-Step Superhydrophobic Stainless-Steel Thermal Spray Coatings

    Get PDF
    As most superhydrophobic coatings are made of soft materials, the need for harder, more robust films is evident in applications where erosional degradation is of concern. The work herein describes a methodology to produce superhydrophobic stainless-steel thermal spray coatings using the high-velocity oxygen fuel technique. Due to the use of a kerosene fuel source, a carbon-rich film is formed on the surface of the thermal spray coatings, lowering the surface energy of the high-energy metallic substrates. The thermal spray process generates a hierarchical micro-/sub-micro-structure that is needed to sustain superhydrophobicity. The effect of spray parameters such as particle velocity and temperature on the coating’s hydrophobicity state was explored, and a high particle velocity was shown to cause superhydrophobic characteristics. The coatings were characterized using scanning electron microscopy, profilometry, X-ray photoelectron spectroscopy, static water contact angle measurements, water droplet roll-off measurements, and water droplet bouncing tests. The corrosion behavior of the coatings was studied using potentiodynamic polarization measurements in order to correlate water repellency with corrosion resistance; however, all coatings demonstrated active corrosion without passivation. This study describes an interesting phenomenon where superhydrophobicity does not guarantee corrosion resistance and discusses alternative applications for such materials

    A European Renal Association (ERA) synopsis for nephrology practice of the 2023 European Society of Hypertension (ESH) Guidelines for the Management of Arterial Hypertension.

    Get PDF
    In June 2023, the European Society of Hypertension (ESH) presented and published the new 2023 ESH Guidelines for the Management of Arterial Hypertension, a document that was endorsed by the European Renal Association (ERA). Following the evolution of evidence in recent years, several novel recommendations relevant to the management of hypertension in patients with chronic kidney disease (CKD) appeared in these Guidelines. These include recommendations for target office blood pressure (BP) <130/80 mmHg in most and against target office BP <120/70 mmHg in all patients with CKD; recommendations for use of spironolactone or chlorthalidone for patients with resistant hypertension with estimated glomerular filtration rate (eGFR) higher or lower than 30 mL/min/1.73 m2, respectively; use of a sodium-glucose cotransporter 2 inhibitor for patients with CKD and estimated eGFR ≥20 mL/min/1.73 m2; use of finerenone for patients with CKD, type 2 diabetes mellitus, albuminuria, eGFR ≥25 mL/min/1.73 m2 and serum potassium <5.0 mmol/L; and revascularization in patients with atherosclerotic renovascular disease and secondary hypertension or high-risk phenotypes if stenosis ≥70% is present. The present report is a synopsis of sections of the ESH Guidelines that are relevant to the daily clinical practice of nephrologists, prepared by experts from ESH and ERA. The sections summarized are those referring to the role of CKD in hypertension staging and cardiovascular risk stratification, the evaluation of hypertension-mediated kidney damage and the overall management of hypertension in patients with CKD

    Rice growth and yield under rain shelter house as influenced by different water regimes

    Get PDF
    A pot experiment was conducted to evaluate the effect of different water regimes on growth and yield of rice (Oryza sativa L.) variety MR220. Water regimes applied were flooded (5 cm above the soil surface), saturated (water given just to saturate the soil) and field capacity (periodic irrigation applied to maintain the desired level). Significantly higher values were recorded for plant height, number of tillers, shoot and root biomass in flooded rice followed by saturated and field capacity condition. Similar trends were observed for physiological parameters like stomatal conductance, SPAD values and water use efficiency. Yield and yield components were also influenced by the water regimes. Under the field capacity condition, rice plants received comparatively less water than flooded and saturated condition, which resulted in impaired rice growth that reduced grain yield and lowered harvest index

    Sex differences in the association between plasma copeptin and incident type 2 diabetes: the Prevention of Renal and Vascular Endstage Disease (PREVEND) study

    Get PDF
    AIMS/HYPOTHESIS: Vasopressin plays a role in osmoregulation, glucose homeostasis and inflammation. Therefore, plasma copeptin, the stable C-terminal portion of the precursor of vasopressin, has strong potential as a biomarker for the cardiometabolic syndrome and diabetes. Previous results were contradictory, which may be explained by differences between men and women in responsiveness of the vasopressin system. The aim of this study was to evaluate the usefulness of copeptin for prediction of future type 2 diabetes in men and women separately. METHODS: From the Prevention of Renal and Vascular Endstage Disease (PREVEND) study, 4,063 women and 3,909 men without diabetes at baseline were included. A total of 208 women and 288 men developed diabetes during a median follow-up of 7.7 years. RESULTS: In multivariable-adjusted models, we observed a stronger association of copeptin with risk of future diabetes in women (OR 1.49 [95% CI 1.24, 1.79]) than in men (OR 1.01 [95% CI 0.85, 1.19]) (p (interaction) < 0.01). The addition of copeptin to the Data from the Epidemiological Study on the Insulin Resistance Syndrome (DESIR) clinical model improved the discriminative value (C-statistic,+0.007, p = 0.02) and reclassification (integrated discrimination improvement [IDI] = 0.004, p < 0.01) in women. However, we observed no improvement in men. The additive value of copeptin in women was maintained when other independent predictors, such as glucose, high sensitivity C-reactive protein (hs-CRP) and 24 h urinary albumin excretion (UAE), were included in the model. CONCLUSIONS/INTERPRETATION: The association of plasma copeptin with the risk of developing diabetes was stronger in women than in men. Plasma copeptin alone, and along with existing biomarkers (glucose, hs-CRP and UAE), significantly improved the risk prediction for diabetes in women
    corecore