386 research outputs found
Liquidus surfaces in a part of the systems ZnO-PbO-SiO_2 and ZnO-"FeO"-SiO_2
Liquidus surfaces in a part of the systems ZnO-PbO-SiO_2 and ZnO-"FeO"-SiO_2 were constructed by quenching method. The experiments were carried out in air in the system ZnO-PbO-SiO_2. In the part investigated the primary phases were three ternary compounds (PbOă»ZnOă»SiO_2, 2PbOă»ZnOă»2SiO_2 and barysilite) , three lead silicates, Zn_2SiO_4 and SiO_2. Isotherms on the liquidus surface of each primary phase field were determined from 750 to 1300â. In the system ZnO-"FeO"-SiO_2 the experiments were carried out in an atmosphere of purified nitrogen. In the part investigated the primary phases were Fe_2SiO_4, Zn_2SiO_4 and SiO_2. Isotherms on the liquidus surface of each primary phase field from 1150 to 1300â and the ternary eutectic (1130â, 15.9% ZnO, 48.2% "FeO" and 35.9% SiO_2) were determined
Modular and predictable assembly of porous organic molecular crystals
Nanoporous molecular frameworks are important in applications such as separation, storage and catalysis. Empirical rules exist for their assembly but it is still challenging to place and segregate functionality in three-dimensional porous solids in a predictable way. Indeed, recent studies of mixed crystalline frameworks suggest a preference for the statistical distribution of functionalities throughout the pores rather than, for example, the functional group localization found in the reactive sites of enzymes. This is a potential limitation for 'one-pot' chemical syntheses of porous frameworks from simple starting materials. An alternative strategy is to prepare porous solids from synthetically preorganized molecular pores. In principle, functional organic pore modules could be covalently prefabricated and then assembled to produce materials with specific properties. However, this vision of mix-and-match assembly is far from being realized, not least because of the challenge in reliably predicting three-dimensional structures for molecular crystals, which lack the strong directional bonding found in networks. Here we show that highly porous crystalline solids can be produced by mixing different organic cage modules that self-assemble by means of chiral recognition. The structures of the resulting materials can be predicted computationally, allowing in silico materials design strategies. The constituent pore modules are synthesized in high yields on gram scales in a one-step reaction. Assembly of the porous co-crystals is as simple as combining the modules in solution and removing the solvent. In some cases, the chiral recognition between modules can be exploited to produce porous organic nanoparticles. We show that the method is valid for four different cage modules and can in principle be generalized in a computationally predictable manner based on a lock-and-key assembly between modules
Study on Selective Separation of Cesium Using a Macroporous Silica-Based Supramolecular Recognition Absorbent
Using under-ice hyperspectral transmittance to determine land-fast sea-ice algal biomass in Saroma-ko Lagoon, Hokkaido, Japan
Sea ice, which forms in polar and nonpolar areas, transmits light to ice-associated (sympagic) algal communities. To noninvasively study the distribution of sea-ice algae, empirical relations to estimate its biomass from under-ice hyperspectral irradiance have been developed in the Arctic and Antarctica but lack for nonpolar regions. This study examines relationships between normalised difference indices (NDI) calculated from hyperspectral transmittance and sympagic algal biomass in the nonpolar Saroma-ko Lagoon. We analysed physico-biogeochemical properties of snow and land-fast sea ice supporting 27 paired bio-optical measurements along three transects covering an area of over 250 m à 250 m in February 2019. Snow depth (0.08 ± 0.01 m) and ice-bottom brine volume fraction (0.21 ± 0.02) showed low (0.06) and high (0.58) correlations with sea-ice core bottom section chlorophyll a (Chl. a), respectively. Spatial analyses unveiled the patch size of sea-ice Chl. a to be ~65 m, which is in the same range reported from previous studies. A selected NDI (669, 596 nm) explained 63% of algal biomass variability. This reflects the bio-optical properties and environmental conditions of the lagoon that favour the wavelength pair in the orange/red part of the spectrum and suggests the necessity of a specific bio-optical relationship for Saroma-ko Lagoon
Blood pressure variability and cardiovascular risk in the PROspective study of pravastatin in the elderly at risk (PROSPER)
Variability in blood pressure predicts cardiovascular disease in young- and middle-aged subjects, but relevant data for older individuals are sparse. We analysed data from the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) study of 5804 participants aged 70â82 years with a history of, or risk factors for cardiovascular disease. Visit-to-visit variability in blood pressure (standard deviation) was determined using a minimum of five measurements over 1 year; an inception cohort of 4819 subjects had subsequent in-trial 3 years follow-up; longer-term follow-up (mean 7.1 years) was available for 1808 subjects. Higher systolic blood pressure variability independently predicted long-term follow-up vascular and total mortality (hazard ratio per 5 mmHg increase in standard deviation of systolic blood pressure = 1.2, 95% confidence interval 1.1â1.4; hazard ratio 1.1, 95% confidence interval 1.1â1.2, respectively). Variability in diastolic blood pressure associated with increased risk for coronary events (hazard ratio 1.5, 95% confidence interval 1.2â1.8 for each 5 mmHg increase), heart failure hospitalisation (hazard ratio 1.4, 95% confidence interval 1.1â1.8) and vascular (hazard ratio 1.4, 95% confidence interval 1.1â1.7) and total mortality (hazard ratio 1.3, 95% confidence interval 1.1â1.5), all in long-term follow-up. Pulse pressure variability was associated with increased stroke risk (hazard ratio 1.2, 95% confidence interval 1.0â1.4 for each 5 mmHg increase), vascular mortality (hazard ratio 1.2, 95% confidence interval 1.0â1.3) and total mortality (hazard ratio 1.1, 95% confidence interval 1.0â1.2), all in long-term follow-up. All associations were independent of respective mean blood pressure levels, age, gender, in-trial treatment group (pravastatin or placebo) and prior vascular disease and cardiovascular disease risk factors. Our observations suggest variability in diastolic blood pressure is more strongly associated with vascular or total mortality than is systolic pressure variability in older high-risk subjects
Significant nutrient consumption in the dark subsurface layer during a diatom bloom: a case study on Funka Bay, Hokkaido, Japan
We conducted repetitive observations in Funka Bay,
Hokkaido, Japan, on 15 February, 4 and 15 March, and 14 April 2019. The
diatom spring bloom peaked on 4Â March and started declining on 15Â March.
Funka Bay winter water remained below 30âm depth, which was below the
surface mixed-layer and dark-layer depth (0.1â% of the surface photosynthetically active radiation, PAR, depth) on 4
and 15Â March. In the subsurface layer at depths of 30â50âm, concentrations
of NO3-, PO43-, and Si(OH)4 decreased by half
between these dates, even in the dark. Incubation experiments using the
diatom Thalassiosira nordenskioeldii showed that this diatom could consume added nutrients in the dark at
substantial rates after pre-culturing to deplete nutrients. Incubation
experiments using natural seawater collected in the growing phase of the bloom on 8 March 2022 also showed that nutrient-depleted phytoplankton could consume
added nutrients in the dark. We excluded three physical
process â water mixing, diffusive transport, and subduction â as possible main
reasons for the decrease in nutrients in the subsurface layer. We conclude
that the nutrient reduction in the subsurface layer (30â50âm) between 4 and
15 March 2019 could be explained by nutrient consumption by diatoms in the dark in that
layer.</p
Status of 48Ca double beta decay search and its future prospect in CANDLES
CANDLES(CAlcium fluoride for the study of Neutrinos and Dark matters by Low Energy Spectrometer) is the experiment to search for the neutrino-less double beta decay(0vÎČÎČ) of 48Ca with CaF2 scintillator. 48Ca has the highest QÎČÎČ-value (4.3 MeV) among all isotope candidates for 0vÎČÎČ. It enables us to measure signals with very low background condition. After rejection analysis with 131 days Ă 86 kg data for background events from radioactive contaminations in the CaF2 scintillators, no events are observed in the QÎČÎČ-value region. As a result, the 0vÎČÎČ half-life of 48Ca is greater than 6.2 Ă 1022 yr (90% confidence level). For further high sensitive measurement of 48Ca 0vÎČÎČ search, we have been developing the 48Ca enrichment and CaF2 scintillating bolometer techniques. In this paper, the latest result for CANDLES and the status of scintillating bolometer development are described
Carotid artery calcification at the initiation of hemodialysis is a risk factor for cardiovascular events in patients with end-stage renal disease: a cohort study
<p>Abstract</p> <p>Background</p> <p>Vascular calcification has been recognized as a risk factor for cardiovascular (CV) events in patients with end-stage renal disease (ESRD). However, the association of carotid artery calcification (CAAC) with CV events remains unknown. The aim of this study was to elucidate whether CAAC is associated with composite CV events in ESRD patients.</p> <p>Methods</p> <p>One-hundred thirty-three patients who had been started on hemodialysis between 2004 and 2008 were included in this retrospective cohort study. These patients received multi-detector computed tomography to assess CAAC at the initiation of hemodialysis. Composite CV events, including ischemic heart disease, heart failure, cerebrovascular diseases, and CV deaths after the initiation of hemodialysis, were examined in each patient.</p> <p>Results</p> <p>CAAC was found in 94 patients (71%). At the end of follow-up, composite CV events were seen in 47 patients: ischemic heart disease in 20, heart failure in 8, cerebrovascular disease in 12, and CV deaths in 7. The incidence of CAAC was 87% in patients with CV events, which was significantly higher than the rate (62%) in those without. Kaplan-Meier analysis showed a significant increase in composite CV events in patients with CAAC compared with those without CAAC (p = 0.001, log-rank test). Univariate analysis using a Cox hazards model showed that age, smoking, common carotid artery intima-media thickness and CAAC were risk factors for composite CV events. In multivariate analysis, only CAAC was a significant risk factor for composite CV events (hazard ratio, 2.85; 95% confidence interval, 1.18-8.00; p = 0.02).</p> <p>Conclusions</p> <p>CAAC is an independent risk factor for CV events in ESRD patients. The assessment of CAAC at the initiation of hemodialysis is useful for predicting the prognosis.</p
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