6,330 research outputs found
Tracking ocean heat uptake during the surface warming hiatus.
Ocean heat uptake is observed to penetrate deep into the Atlantic and Southern Oceans during the recent hiatus of global warming. Here we show that the deep heat penetration in these two basins is not unique to the hiatus but is characteristic of anthropogenic warming and merely reflects the depth of the mean meridional overturning circulation in the basin. We find, however, that heat redistribution in the upper 350 m between the Pacific and Indian Oceans is closely tied to the surface warming hiatus. The Indian Ocean shows an anomalous warming below 50 m during hiatus events due to an enhanced heat transport by the Indonesian throughflow in response to the intensified trade winds in the equatorial Pacific. Thus, the Pacific and Indian Oceans are the key regions to track ocean heat uptake during the surface warming hiatus
Far-Field Tunable Nano-focusing Based on Metallic Slits Surrounded with Nonlinear-Variant Widths and Linear-Variant Depths of Circular Dielectric Grating
In this work, we design a new tunable nanofocusing lens by the linear-variant
depths and nonlinear-variant widths of circular grating for far field practical
applications. The constructively interference of cylindrical surface plasmon
launched by the subwavelength metallic structure can form a
subdiffraction-limited focus, and the focal length of the this structures can
be adjusted if the each groove depth and width of circular grating are arranged
in traced profile. According to the numerical calculation, the range of
focusing points shift is much more than other plasmonic lens, and the relative
phase of emitting light scattered by surface plasmon coupling circular grating
can be modulated by the nonlinear-variant width and linear-variant depth. The
simulation result indicates that the different relative phase of emitting light
lead to variant focal length. We firstly show a unique phenomenon for the
linear-variant depths and nonlinear-variant widths of circular grating that the
positive change and negative change of the depths and widths of grooves can
result in different of variation trend between relative phases and focal
lengths. These results paved the road for utilizing the plasmonic lens in
high-density optical storage, nanolithography, superresolution optical
microscopic imaging, optical trapping, and sensing.Comment: 14pages,9figure
A New Two-Dimensional Functional Material with Desirable Bandgap and Ultrahigh Carrier Mobility
Two-dimensional (2D) semiconductors with direct and modest bandgap and
ultrahigh carrier mobility are highly desired functional materials for
nanoelectronic applications. Herein, we predict that monolayer CaP3 is a new 2D
functional material that possesses not only a direct bandgap of 1.15 eV (based
on HSE06 computation), and also a very high electron mobility up to 19930 cm2
V-1 s-1, comparable to that of monolayer phosphorene. More remarkably, contrary
to the bilayer phosphorene which possesses dramatically reduced carrier
mobility compared to its monolayer counterpart, CaP3 bilayer possesses even
higher electron mobility (22380 cm2 V-1 s-1) than its monolayer counterpart.
The bandgap of 2D CaP3 can be tuned over a wide range from 1.15 to 0.37 eV
(HSE06 values) through controlling the number of stacked CaP3 layers. Besides
novel electronic properties, 2D CaP3 also exhibits optical absorption over the
entire visible-light range. The combined novel electronic, charge mobility, and
optical properties render 2D CaP3 an exciting functional material for future
nanoelectronic and optoelectronic applications
Enzymology and energetics of thiosulphate oxidation by 'Thiobacillus' A2
The mechanism of thiosulphate oxidation by Thiobacillus versutus (A2) was investigated in an attempt to elucidate the enzyme system and the energetic processes involved. The theoretical maximum growth yield of the organism on thiosulphate was 7 (g dry wt/mol). Thiosulphate oxidation was coupled to the electron transport chain through c-type cytochrome(s). Cell-free extracts catalyzed the complete oxidation of thiosulphate and linked the associated electron transport to ATP synthesis with a P/0 ratio of about one. On the basis of these data and a knowledge of the biochemistry of the organism, a requirement reduction of one mole of approximately three ATP for NAD+ was deduced and the involvement of an oxygenase in thiosulphate oxidation ruled out. Enzymes for conversion of thiosulphate to sulphate were located in the cytoplasm, but oxygen uptake required the membrane fraction, which provided cytochrome c and cytochrome oxidase and could be replaced by its counterparts from mammalian sources.
The crude extract was fractionated by ammonium sulphate, then resolved into three major fractions involved in thiosulphate oxidation by chromatography on DEAE-Sepharose-CL 6B. Four essential components, enzyme A, enzyme B, cytochrome c_511 and cytochrome c_512.5 and sulphite : cytochrome c oxidoreductase were finally highly purified from the three fractions by means of gel filtration, hydrophobic interaction chromatography, isoelectric focusing, chromatofocusing and gel electrophoresis.
Enzyme A (Mr 16,000) and Enzyme B (Ilr 64,000) were colourless proteins both necessary for the thiosulphate-oxidizing reaction. Cytochrome c_511 (Mr 260,000) and cytochrome c_512.5 (Mr 56,000) were multihaem c-type cytochromes, each with a dual Em, 7 of -115, +240 and about -50 and *220 mV respectively. The four components, each comprising 0.6 to 1.57. of the cellular protein, catalyzed complete oxidation of thiosulphate in the presence of an electron transport system. The reaction proceeded in an integral way as neither cleavage of thiosulphate nor any intermediates (e.g. sulphite) were detected and the individual or specific functions of the four components were not identified. The two cytochromes may serve not only as electron carriers but could also have other enzyme functions. Sulphite : cytochromo c oxidoreductase was an important component in the enzyme system, but further study of its function was hampered by its low concentration (less than 0.52 of the cellular proteins) and its intimate association with cytochrome c_511.
Rhodanese was proven not to be a part of the thiosulphate-oxidizing system. A generalized mechanism and a model system are proposed for the path of thiosulphate oxidation to sulphate, the involvement of the four essential components and the role of dual Em 7 of the cytochromes in feeding electrons into ATP and NADII-generating electron transport. The problems remaining to be resolved and possible routes to their solution, are outlined
Psychosocial Determinants of Insomnia in Adolescents: Roles of Mental Health, Behavioral Health, and Social Environment
The theoretical explanation of human problems is derived from the complex interplay of psychological, social, economic, political, and physical factors.
Aims: This study examined the roles of behavioral health (i.e., alcohol abuse and suicidality) and social environment (i.e., family support, school connectedness, and favorable neighborhood) and mental health [i.e., depression, anxiety, and attention deficit hyperactivity disorder (ADHD)] in predicting insomnia in adolescents in an ecological perspective.
Methods: Approximately 6445 high school students in Taiwan were administered an anonymous self-report survey. Hierarchical multiple regression was performed to examine how multidimensional social environment, behavioral health, and mental health factors were associated with insomnia in adolescents.
Results: The prevalence rate of insomnia in the sample was 30%. The results indicated that alcohol abuse (β = 0.04), suicidality (β = 0.06), depression (β = 0.29), anxiety (β = 0.14), and ADHD (β = 0.11) were positively associated with insomnia (p \u3c 0.001), whereas family support (β = −0.06), school connectedness (β = −0.05), and favorable neighborhood (β = −0.10) were negatively associated with insomnia (p \u3c 0.001). Sex did not predict insomnia, but age was positively associated with insomnia (β = 0.09, p \u3c 0.001). Among all predictors of insomnia in the study, mental health factors, especially depression, play a major role on insomnia among adolescents, and is as much important as social environment factors.
Conclusion: This study demonstrated how both psychosocial variables (social environment and behavioral health) and psychological symptoms were associated with insomnia in adolescents when the demographic variables (sex and age) were controlled and provided valuable information and evidence for clinicians, social workers, and health professionals who provide support to adolescents with insomnia. Applying an ecological approach in practice can aid in understanding at individual, family, school, and community levels and in identifying the strengths and weaknesses of their interactions with each other.
Implications: This perspective enables practitioners in effectively treating problems and addressing the needs of the various levels, including the individual, family, school, and the broader community. Thus, prevention and intervention of insomnia in adolescents should focus on multidimensional risk and protective factors, including mental health, behavioral health, and social environment, in the context of an ecological system
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