An efficient purification method for detonation nanodiamonds

This article reports the purification process of detonation soot to obtain pure nanodiamond powder. Nanodiamonds are synthesized by detonation using a high explosive mixture composed of trinitrotoluene and hexogen. The detonation of the charge leads to a powder containing nanodiamonds as well as metallic impurities and sp² carbon species. Further, to remove metallic particles, an unusual acidic treatment (hydrofluoric/nitric acids; i.e. fluorinated aqua regia) was set up. To eliminate sp² carbon species such as graphite and amorphous carbon, a thermal oxidation treatment was performed at 420 °C under air in a furnace during several hours. Transmission Electronic Microscopy, Raman spectroscopy, X-ray diffraction and Thermo-Gravimetric Analysis showed that this purification process is very efficient. From TGA measurements, a model of the carbon grain combustion was developed by considering graphitic shells surrounding the nanodiamond particles, and was used to demonstrate that the selective oxidation of graphite was experimentally realistic. Moreover, another model was set up from specific area measurements to evaluate the thickness of the functional groups surrounding the nanodiamonds after the oxidation of sp² carbonaceous species. The treatment described herein was achieved on several tens of grams of product and could be easily adapted to the industrial scale.     

Improvements of metabolic imbalances after enteral sodium bicarbonate supplementation in infants of very low birth weight (VLBW)

One of the main points of clinical care is the catch-up growth of VLBW infants especially those of small gestational age (SGA). The required high amounts of protein are often not tolerated [1]. Metabolic imbalances due to immaturities of protein metabolism are described [2, 3] also in infants SGA feeding amounts of proteins comparable to mature newborns [4]. Remarkable signs of overloading by proteins are the elevation of amino acid and the bile acid concentrations in the serum [3, 5, 6]. In some of those cases [7] late metabolic acidosis (LMA) is to be seen. There is evidence in the literature that sodium bicarbonate influences nitrogen [8] and ionic balances [9] in newborn animals without any signs of acidosis, besides its simple buffer function. The aim of this study was to control changes of metabolic imbalances after bicarbonate supplementation before development of acidosis in predisposed infants. Therefore we determined parameters, which were significantly changed with LMA [6] during two feeding schedules: firstly, during bolus supplementation in infants feeding (2.0 +/- 0.4) g/kg BW.d protein and secondly during chronic supplementation of bicarbonate to (3.0 +/- 0.4) g/kg BW.d protein. In relation to the improvement of the nitrogen balance in growing lambs [7] we supposed comparable effect of bicarbonate on metabolic imbalances caused by protein overloading.     

4‐Biphenylalanine‐ and 3‐Phenyltyrosine‐Derived Hydroxamic Acids as Inhibitors of the JumonjiC‐Domain‐Containing Histone Demethylase KDM4A

Overexpression of the histone lysine demethylase KDM4A, which regulates H3K9 and H3K36 methylation states, has been related to the pathology of several human cancers. We found that a previously reported hydroxamate‐based histone deacetylase (HDAC) inhibitor (SW55) was also able to weakly inhibit this demethylase with an IC₅₀ value of 25.4 μm . Herein we report the synthesis and biochemical evaluations, with two orthogonal in vitro assays, of a series of derivatives of this lead structure. With extensive chemical modifications on the lead structure, also by exploiting the versatility of the radical arylation with aryldiazonium salts, we were able to increase the potency of the derivatives against KDM4A to the low‐micromolar range and, more importantly, to obtain demethylase selectivity with respect to HDACs. Cell‐permeable derivatives clearly showed a demethylase‐inhibition‐dependent antiproliferative effect against HL‐60 human promyelocytic leukemia cells.     

A nucleation and growth model of vertically-oriented carbon nanofibers or nanotubes by plasma-enhanced catalytic chemical vapor deposition

Carbon nanofibers are grown by direct current and hot filaments-activated catalytic chemical vapor deposition while varying the power of the hot filaments. Observations of these carbon nanofibers vertically oriented on a SiO2 (8 nm thick)/Si(100) substrate covered with Co nanoparticles (10-15 nm particle size) by Scanning Electron and Transmission Electron Microscopies show the presence of a graphitic "nest" either on the surface of the substrate or at the end of the specific nanofiber that does not encapsulate the catalytic particle. Strictly in our conditions, the activation by hot filaments is required to grow nanofibers with a C2H2 - H2 gas mixture, as large amounts of amorphous carbon cover the surface of the substrate without using hot filaments. From these observations as well as data of the literature, it is proposed that the nucleation of carbon nanofibers occurs through a complex process involving several steps: carbon concentration gradient starting from the catalytic carbon decomposition and diffusion from the surface of the catalytic nanoparticles exposed to the activated gas and promoted by energetic ionic species of the gas phase; subsequent graphitic condensation of a "nest" at the interface of the Co particle and substrate. The large concentration of highly reactive hydrogen radicals mainly provided by activation with hot filaments precludes further spreading out of this interfacial carbon nest over the entire surface of the substrate and thus selectively orientates the growth towards the condensation of graphene over facets that are perpendicular to the surface. Carbon nanofibers can then be grown within the well-known Vapor-Liquid-Solid process. Thus the effect of energetic ions and highly reactive neutrals like atomic hydrogen in the preferential etching of carbon on the edge of graphene shells and on the broadening of the carbon nanofiber is underlined.     

Dermatofibrosarcoma protuberans and the Bednar tumor: treatment in the pediatric population

Dermatofibrosarcoma protuberans (DFSP) is a low-intermediate-grade cutaneous sarcoma that has a marked propensity for local recurrence after excision. The Bednar variant of this tumor is even less common and is distinguished histologically by the dispersal of melanin containing cells in an otherwise typical DFSP. Both are considered to be tumors of the third and forth decades of life, but both DFSP and the Bednar variant have been described in children. Until this report of a congenital Bednar tumor, only the DFSP has also been described in the neonate. The histopathology and surgical management of DFSP and Bednar tumors are outlined with emphasis on reported experience in the pediatric population. The surgical management of these lesions in children is based on numerous series in adults and the limited pediatric experience. The recommended treatment is wide excision with 3-cm margins of visibly uninvolved tissue and inclusion of superficial fascia.     

Improvements of metabolic imbalances after enteral sodium bicarbonate supplementation in infants of very low birth weight (VLBW) (Short communication)

One of the main points of clinical care is the catch-up growth of VLBW infants especially those of small gestational age (SGA). The required high amounts of protein are often not tolerated [1]. Metabolic imbalances due to immaturities of protein metabolism are described [2, 3] also in infants SGA feeding amounts of proteins comparable to mature newborns [4]. Remarkable signs of overloading by proteins are the elevation of amino acid and the bile acid concentrations in the serum [3, 5, 6]. In some of those cases [7] late metabolic acidosis (LMA) is to be seen. There is evidence in the literature that sodium bicarbonate influences nitrogen [8] and ionic balances [9] in newborn animals without any signs of acidosis, besides its simple buffer function. The aim of this study was to control changes of metabolic imbalances after bicarbonate supplementation before development of acidosis in predisposed infants. Therefore we determined parameters, which were significantly changed with LMA [6] during two feeding schedules: firstly, during bolus supplementation in infants feeding (2.0 ± 0.4) g/kg BW · d protein and secondly during chronic supplementation of bicarbonate to (3.0 ± 0.4) g/kg BW · d protein. In relation to the improvement of the nitrogen balance in growing lambs [7] we supposed comparable effect of bicarbonate on metabolic imbalances caused by protein overloading.     

Angiogenesis promoted by vascular endothelial growth factor: regulation through alpha1beta1 and alpha2beta1 integrins

Vascular endothelial growth factor (VEGF), also known as vascular permeability factor, is a cytokine of central importance for the angiogenesis associated with cancers and other pathologies. Because angiogenesis often involves endothelial cell (EC) migration and proliferation within a collagen-rich extracellular matrix, we investigated the possibility that VEGF promotes neovascularization through regulation of collagen receptor expression. VEGF induced a 5- to 7-fold increase in dermal microvascular EC surface protein expression of two collagen receptors-the alpha1beta1 and alpha2beta1 integrins-through induction of mRNAs encoding the alpha1 and alpha2 subunits. In contrast, VEGF did not induce increased expression of the alpha3beta1 integrin, which also has been implicated in collagen binding. Integrin alpha1-blocking and alpha2-blocking antibodies (Ab) each partially inhibited attachment of microvascular EC to collagen I, and alpha1-blocking Ab also inhibited attachment to collagen IV and laminin-1. Induction of alpha1beta1 and alpha2beta1 expression by VEGF promoted cell spreading on collagen I gels which was abolished by a combination of alpha1-blocking and alpha2-blocking Abs. In vivo, a combination of alpha1-blocking and alpha2-blocking Abs markedly inhibited VEGF-driven angiogenesis; average cross-sectional area of individual new blood vessels was reduced 90% and average total new vascular area was reduced 82% without detectable effects on the pre-existing vasculature. These data indicate that induction of alpha1beta1 and alpha2beta1 expression by EC is an important mechanism by which VEGF promotes angiogenesis and that alpha1beta1 and alpha2beta1 antagonists may prove effective in inhibiting VEGF-driven angiogenesis in cancers and other important pathologies.     

Mutation Testing Applied to Estelle Specifications

Many researchers have pursued the establishment of a low-cost, effective testing and validation strategy at the program level as well as at the specification level. Mutation Testing is an error-based approach, originally introduced for program testing, that provides testers a systematic way to evaluate how good a given test set is. Some studies have also investigated its use to generate test sets. In this article, the application of Mutation Testing for validating Estelle specifications is proposed. A mutant operator set for Estelle—one of the crucial points for effectively applying Mutation Testing—is defined, addressing: the validation of the behavior of the modules, the communication among modules and the architecture of the specification. In this scope, these operators can be taken as a fault model. Considering this context, a strategy for validating Estelle-based specification is proposed and exemplified using the Alternating-bit protocol.     

Visualizing and segmenting large volumetric data sets

Current systems for segmenting and visualizing volumetric data sets characteristically require the user to possess a technical sophistication in volume visualization techniques, thus restricting the potential audience of users. As large volumetric data sets become more common, segmentation and visualization tools need to deemphasize the technical aspects of visualization and let users exploit their content knowledge of the data set. This proves especially critical in an educational setting. In anatomical education, data sets such as the Visible Human Project provide significant learning opportunities, but students must have tools that let them apply, refine, and build on their anatomical knowledge without technical obstacles. I describe a software environment that uses immersive virtual reality technology to let users immediately apply their expert knowledge to exploring and visualizing volumetric data sets