163 research outputs found
Systematic Reviews and Meta-analysis: General Principles and Application for Child Health
No full textNo abstract available
Effect of iron supplementation on physical growth in children: systematic review of randomised controlled trials
No full textOBJECTIVE: To evaluate the effect of iron supplementation on physical growth in children through a systematic review of randomised controlled trials (RCTs). DATA SOURCES: Electronic databases, personal files, and hand search of reviews, bibliographies of books, abstracts and proceedings of international conferences. REVIEW METHODS: RCTs evaluating change in anthropometry with interventions that included oral or parenteral iron supplementation, or iron-fortified formula milk or cereals, were analysed. RESULTS: Twenty-five trials (26 cohorts) had relevant information. There was no evidence of publication bias. The pooled estimates (random effects model) did not document a statistically significant (P>0.05) positive effect of iron supplementation on any anthropometric variable (weight-for-age, weight-for-height, height-for-age, mid upper-arm circumference, skinfold thickness, head circumference). Significant heterogeneity was evident, and its predictors included greater weight-for-age in supplemented children in malaria hyperendemic regions and greater weight-for-height for children above 5 years of age, but a negative effect on linear growth in developed countries and with supplementation for 6 months or longer. CONCLUSIONS: This review did not document a positive effect of iron supplementation on the physical growth of children. The identified predictors of heterogeneity should be considered as exploratory and requiring confirmation, not conclusive
Unexpected aggregation induced circular dichroism, circular polarized luminescence and helical assembly from achiral hexaphenylsilole (HPS)
No full textThis work provides the finding of aggregation-induced circular dichroism (AICD), optical properties and helical assemblies of pi-pi conjugated molecule hexaphenylsilole (HPS). As an achiral molecule, HPS was found to exhibit unusual AICD and circular polarized luminescence (CPL). Upon aggregation, it self-assembled into fluorescent helical nanofiber and nanotubes. Theoretical modeling suggests that van der Waals interaction between HPS monomers plays an essential role in the formation of helical nanofibers. These kinds of molecules have important applications given the increasing demand of miniaturized optics and electronic devices.National Natural Science Foundation of China [21574085]; National Natural Science Foundation of Guangdong province [2016A030312002]SCI(E)ARTICLE4024841-24847
DISCOVERY OF THE ELECTRONIC SPECTRA OF HPS AND DPS
No full textAuthor Institution: Department of Chemistry, University of Kentucky, Lexington, KY, 40506; Department of Chemistry, Brookhaven National Lab, Upton, NY 11973The hitherto unknown electronic spectrum of the closed shell transient molecule HPS has been observed in the 685 - 846 nm region by laser-induced fluorescence and single vibronic level emission techniques. HPS (and DPS) were produced in a pulsed electric discharge jet using a precursor mixture of 3\% PH and 1\% HS (or PD and DS) in high pressure argon. The weak set of observed bands are assigned to the ^1^1 electronic transition on the basis of chemical evidence, isotope shifts and the correspondence of the vibrational frequencies, excitation energy, and band contours with predictions based on our own high level {\em ab initio} calculations. Theory predicts that the HPS bond angle decreases on electronic excitation, contrary to expectations based on Walsh diagrams
A review of small heat pipes for electronics
No full textHeat pipes (HPs) have received considerable attention in recent decades, especially in the field of cooling electronics, which requires the removal of added heat from an area of limited volume to the environment. Small HPs are widely used in electronic applications, which are normally limited by the compact structure and dimensions of the electronic device. Among small HPs, mini/micro HPs and two-phase loops (TPLs) with mini/micro wicks, including loop HPs (LHPs) and capillary pumped loops (CPLs), are preferred for their high efficiency, small dimensions, and compatible process with semiconductor devices. Particularly, TPLs possess all of the main advantages of traditional HPs with the addition of special properties that enable the transfer of heat for distances up to several metres at any orientation in the gravity field. Further, small vapour chambers (VCs), also referred to as flat HPs, are excellent candidates for electronic heat spreaders due to their light weight, geometric flexibility, and extremely high thermal conductivities. Because silicon is widely used in electronics, it is a preferred material for mini/micro HPs along with TPLs. Moreover, polymer-based small HPs are highly attractive for further development as they are inexpensive and easy to fabricate. Because the smaller wicks supply a greater capillary force, nano wicks, such as carbon nanotubes (CNTs), may represent the future of HPs due to their potentially outstanding characteristics. In this work, a review of small HPs, including their design, analysis, and fabrication, is presented.Accepted author manuscriptElectronic Components, Technology and Material
Thrombospondin 1 and vasoactive agents indirectly alter tumor blood flow.
No full textNitric oxide (NO) plays important physiological roles in the vasculature to regulate angiogenesis, blood flow, and hemostasis. In solid tumors, NO is generally acknowledged to mediate angiogenic responses to several growth factors. This contrasts with conflicting evidence that NO can acutely increase tumor perfusion through local vasodilation or diminish perfusion by preferential relaxation of peripheral vascular beds outside the tumor. Because thrombospondin 1 (TSP1) is an important physiological antagonist of NO in vascular cells, we examined whether, in addition to inhibiting tumor angiogenesis, TSP1 can acutely regulate tumor blood flow. We assessed this activity of TSP1 in the context of perfusion responses to NO as a vasodilator and epinephrine as a vasoconstrictor. Nitric oxide treatment of wild type and TSP1 null mice decreased perfusion of a syngeneic melanoma, whereas epinephrine transiently increased tumor perfusion. Acute vasoactive responses were also independent of the level of tumor-expressed TSP1 in a melanoma xenograft, but recovery of basal perfusion was modulated by TSP1 expression. In contrast, overexpression of truncated TSP1 lacking part of its CD47 binding domain lacked this modulating activity. These data indicate that TSP1 primarily regulates long-term vascular responses in tumors, in part, because the tumor vasculature has a limited capacity to acutely respond to vasoactive agents
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