Single-atom Zn for boosting supercapacitor performance

Single-atom metal-incorporated carbon nanomaterials(CMs)have shown great potential towards broad catalytic applications.In this work,we show that N-doped porous...     

Early reduction of immune activation in lymphoid tissue following highly active HIV therapy

OBJECTIVE: To evaluate immune reconstitution within HIV-infected lymphoid tissue during highly active antiretroviral therapy (HAART). DESIGN AND METHODS: In situ cellular responses were studied in sequential tonsillar biopsies in three asymptomatic HIV-infected (CD4 cells greater than 400 x 10(6)/l) antiretroviral treatment-naive volunteers enrolled in a clinical trial to determine the early effect of HAART. Computerized image analysis was used to study immunohistochemically stained sequential tonsil sections for the patterns of local cytokine production, chemokine receptor expression and cellular distribution. Replicate quantitative assessments of samples before and after 4 weeks of therapy were used for the evaluation of drug effects and compared with four uninfected controls. Tonsillar HIV proviral-DNA was determined by fluorescent in situ 5'-nuclease assay. RESULTS: HIV-infected tonsil tissue was characterized by extensive pro-inflammatory and type 1 cytokine expression. A five- to 15-fold elevation of interleukin (IL)-1 alpha, IL-12, IL-2 and interferon (IFN)-gamma protein expression was found compared with controls, and each encompassed a mean of at least 4.5% of the tissue compartment. This was reduced by 20-90% in all individuals after 4 weeks of HAART. In contrast, type 2 cytokine expression (IL-4, IL-10), plus tumour necrosis factor (TNF)-alpha, remained low throughout the study. HAART reduced, by 40%, the expression of HIV co-receptors, CCR5 and CXCR4, which initially were elevated four to six times over the control values. In addition, the myelomonocytic inflammatory proteins, CD68 and calprotectin, diminished by 26-83% after therapy. The HIV RNA was reduced to undetectable levels in plasma by HAART. However, a large pool of tonsil cells (2-7%), remained HIV DNA positive after 4 weeks of therapy. CONCLUSIONS: Although immune activation may be the direct consequence of HIV replication, HAART-associated reconstitution begins with a reduction in inflammatory cytokine production which precedes the elimination of local proviral reservoirs.     

Passive heating and cooling strategies in an approaches of retrofit in Rome

The main aim of this intervention is the energetic rescue of a building now employed as a library. Problems connected with the differences between the windowed surface and the opaque partition were so consistent that an accurate analysis was necessary to know the behavior of the shell subjected to the effects induced by the external climate.     

Microscopic insight into the single step growth of in-plane heterostructures between graphene and hexagonal boron nitride

Graphene-h-BN hybrid nanostructures are grown in one step on the Pt(111) surface by ultra-high vacuum chemical vapor deposition using a single precursor, the dimethylamino borane complex. By varying the deposition conditions, different nanostructures ranging from a fully continuous hybrid monolayer to well-separated Janus nanodots can be obtained. The growth starts with heterogeneous nucleation on morphological defects such as Pt step edges and proceeds by the addition of small clusters formed by the decomposition of the dimethylamino borane complex. Scanning tunneling microscopy measurements indicate that a sharp zigzag in-plane boundary is formed when graphene grows aligned with the Pt substrate and consequently with the h-BN layer as well. When graphene is rotated by 30°, the graphene armchair edges are seamlessly connected to h-BN zigzag edges. This is confirmed by a thorough density functional theory (DFT) study. Angle resolved photoemission spectroscopy (ARPES) data suggests that both h-BN and graphene present the typical electronic structure of self-standing non-interacting materials.

     

Direct ink writing of silica-carbon-calcite composite scaffolds from a silicone resin and fillers

Calcite-based composite scaffolds have been successfully 3D-printed by direct ink writing, starting from a paste comprising a silicone polymer and calcite (CaCO₃) powders. The firing in nitrogen, at 600?°C, after preliminary cross-linking step at 350?°C, determined the transformation of the polymer matrix into a silica-carbon nano-composite, embedding unreacted calcite particles. Compared to previously developed silica-calcite scaffolds, obtained after firing in air, the new composites exhibited a significant strength improvement (up to ～10?MPa, for a total open porosity of 56%). The new formulation did not compromise the in vitro bioactivity and the biocompatibility of the scaffolds, as shown by dissolution studies in SBF and preliminary cell culture tests, with human fibroblasts. Due to the simplicity of the processing and the outstanding mechanical performances, the developed scaffolds are promising candidates for bone tissue engineering applications.     

Renal water-electrolyte excretion and its control mechanisms. Current status of knowledge

The literature on hydronatriuresis control processes operating at the level of individual renal functional units and of the organ as a whole is analysed. 1) Elementary sodium salt and water tubular transport mechanisms. In converting the filtrate into urine, the kidney expends metabolic energy: this is used in the (active) transport of sodium salts; (passive) transport of water takes place along the osmotic gradients created by salt transfer. The proximal tubules reabsorb the sodium bic-rbonate actively. The reabsorption of the osmitic equivalent of water has the effect of concentrating NaCl in the tubular fluid. An important role in the reabsorption of NaCl is played by passive diffusion from the lumen to the interstitial fluid; the remainder is transferred actively, perhaps by an electrically neutral pump. With respect to the other nephronic segments, the proximal tubule has a relatively high passive permeability to water and salts: active transport here must not surmount high friction resistances nor take place against important concentration gradients. The low permeability of the distal nephron, on the other hand, increases the energy cost of salt transport; for the same reason, important electrochemical gradients are created and the composition of tubular fluid is drastically altered. 2) Elementary mechanisms of tubular potassium transport. Potassium is reabsorbed actively along the whole nephron by a luminal pump. The proximal tubules and Henle loops promote practically complete absorption of filtrated potassium. The distal tubules and collectors have the two-fold capacity of secreting and reabsorbing cation: the quantity of potassium excreted with the urine depends on the degree of excess of the secretion process. At distal tubular level, potassium secretion is a passive phenomenon dependent on the favourable transluminal gradient of the cation's electrochemical potential. 3) Renal function and volume homoeostasis of extracellular fluid. The organism's sodium content is largely controlled by renal excretion of sodium; homoeostasis of the sodium mass guarantees volume homoeostasis of the extracellular fluid through thirst and osmotic secretion of ADH. Extracellular fluid volume errors are picked up by the organism to the extent to which they translate themselves into pressure variations in the low pressure vascular system or into variations in haematic constituent concentration within the vascular sector, produced with velocities independent, at least in the short term, of the volume of extracellular fluid. In control of natriuria are the glomerular filtrate, intrarenal distribution of blood flow and tubular reabsorption of sodium; in its turn, the latter is subject to nervous and hormonal influences and influences from the physical environment surrounding the nephrons...