Oxidation of pinane over phthalocyanine complexes supported on activated carbon: Effect of the support surface treatment

The oxidation of cis-pinane with tert-butyl hydroperoxide, at room temperature and atmospheric pressure, was carried out in the presence of iron-phthalocyanines supported on activated carbons. The carbon supports were prepared from a NORIT activated carbon, which was modified by different chemical and thermal treatments (including oxidation in the gas and liquid phases). The carbon samples were characterized by nitrogen adsorption, mass titration and temperature programmed desorption (TPD). The TPD profiles were analysed by a simple deconvolution method, allowing for the determination of the amount of oxygen containing functional groups on the carbon surface. The main reaction product is 2-pinane hydroperoxide (77% selectivity at 91% conversion). Formation of 2-pinanol, pinocampheol and verbanol and the respective ketones was also observed. The influence of the surface chemistry of the carbon supports on catalytic activity and product selectivity is studied. The catalysts prepared from supports with very high or very low oxygen content exhibit low activity, whereas for supports with intermediate oxygen contents a good correlation between the amount of phenols and lactones and catalytic activity is obtained.     

Dry-pressed anodized titania nanotube/CH3NH3PbI3 single crystal heterojunctions: The beneficial role of N doping

Highly ordered, anodically grown TiO₂ nanotubes on titanium supports were annealed in ammonia atmosphere in order to incorporate nitrogen doping (≤2?at.%) in the titanium oxide lattice. FESEM micrographs revealed nanotubes with an average outer diameter of 101.5?±?1.5?nm and an average wall thickness of about 13?nm. Anatase crystals were formed inside the tubes after annealing in ammonia atmosphere for 30?min. With further annealing, rutile peaks appeared due to the thermal oxidation of the foil and rise as the duration of heat treatment was increased. The concentration and chemical nature of nitrogen in the nanotube arrays can be correlated to the optical response of dry-pressed heterojunctions of doped TiO₂/CH₃NH₃PbI₃ single crystals. The N-TiO₂/perovskite heterojunction with the highest amount of interstitial nitrogen exhibited an improved photocurrent, indicating the importance of the semiconductor doping-based heterojunction optimization strategies to deliver competitive levels of halide perovskite-based optoelectronic devices to be envisioned for urban infrastructures.     

Averaging technique in flash analog-to-digital converters

The averaging technique is used in flash analog-to-digital converters to reduce nonlinearities resulting from random offset voltages of the pre-amplifiers, which stand before the comparators. The main contribution of this paper is to provide further insight into this technique, through exact closed-form expressions obtained for the output voltage, gain, integral nonlinearity and differential nonlinearity in averaged pre-amplifiers. These theoretical results are compared with HSPICE simulations, and a very good agreement is found. Finally an automatic design procedure is described, which is based on the expressions derived, and a design example is given.     

Accelerating Scientific Discovery Through Computation and Visualization II

This is the second in a series of articles describing a wide variety of projects at NIST that synergistically combine physical science and information science. It describes, through examples, how the Scientific Applications and Visualization Group (SAVG) at NIST has utilized high performance parallel computing, visualization, and machine learning to accelerate research. The examples include scientific collaborations in the following areas: (1) High Precision Energies for few electron atomic systems, (2) Flows of suspensions, (3) X-ray absorption, (4) Molecular dynamics of fluids, (5) Nanostructures, (6) Dendritic growth in alloys, (7) Screen saver science, (8) genetic programming.     

Astrocytomas and choroid plexus tumors in two families with identical p53 germline mutations

Germline p53 mutations carry an increased risk of development of breast cancer, soft tissue and osteosarcomas, brain tumors, leukemia and adrenocortical carcinomas. Cerebral neoplasms are usually of astrocytic lineage and occur in 40% of affected families. This report presents clinical, neuropathological and molecular genetic data from 2 families in France with an identical p53 germline mutation in codon 248 (CGG->TGG; Arg->Trp) and a clustering of CNS tumors. The youngest patient in each family developed a malignant choroid plexus tumor while several young adults of both kindred succumbed to low-grade astrocytoma, anaplastic astrocytoma or glioblastoma. The only non-neural neoplasm was an adrenocortical carcinoma in a boy aged 4 years who developed an anaplastic choroid plexus papilloma 2 years later. Of 2 previously reported inherited choroid plexus tumors, 1 occurred in a family which also carried a germline mutation in codon 248. It remains to be shown whether this unusual pattern of CNS tumors is due to an organ-specific effect of this particular p53 mutation or whether it reflects the genetic background of the affected families.     

Fabrication of PMMA/zeolite nanofibrous membrane through electrospinning and its adsorption behavior

The present work investigates the effect of various solution parameters and electrospinning parameters on the characteristics of electrospun nanofibrous membranes. Scanning electron microscopy was used to analyze the surface morphology of the nanofibrous membrane. Adsorption test on methyl orange was also carried out and analyzed using the UV–vis. Results showed that increasing voltage decreased mean nanofiber diameter. Meanwhile, increasing PMMA concentration, feed rate, distance between collector‐and‐needle tip increased mean nanofiber diameter. Zeolite concentration and needle size did not affect the surface morphology significantly. The UV–vis spectra of the adsorption test showed that ～93%, 85.5%, and 78% of methyl orange were adsorbed for 30, 50, and 100 mg L^?1 initial dye concentration, respectively, within 11 min. The maximum adsorption capacity was found to be 95.33 mg g^?1. Therefore, PMMA/zeolite nanofibrous membranes possess the adsorption capability toward effective dye removal. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44450.     

Mechanical activation of talc in high-energy speed rotary mechanoactivator

This paper presents the results of research on mechanical activation of raw talc in a high-energy speed rotary mechanoactivator. The results of research on effect of mechanically activated talc on the degree of recovery Fe₂O₃ by hydrometallurgical method are also presented. The process and mechanism of mechanical activation in this type of mechanoactivator were achieved by impact.The variable parameters of the mechanoactivator operation were: rate of rotor revolutions (n₀ = 10,000 and n₀ = 20,000 rpm), circle sieve mesh (80, 120, 200 and 500 μm) and the current intensity. The following parameters of the dry mechanical activation process were studied: mechanical activation time, rotor speed, mechanoactivator capacity and specific energy consumption. The mechanically activated powder was examined by application of differential thermal and thermogravimetric analyses, analysis of the degree of mechanical activation and the specific surface area as well.According to the obtained results, the highest rate of mechanical activation was obtained with a nominal mechanoactivator load. The degree of mechanical activation increases with increasing the rate of rotor revolution, circle sieve mesh size and with the increasing mechanoactivator load. It was shown that high-grade talc concentrate with low content of Fe₂O₃ can be obtained by physical-chemical process. A new approach for obtaining high-grade talc concentrate was achieved trough mechanically activated talc effect on the degree of recovery of Fe₂O₃ by hydrometallurgical process.     

Neuronal apoptosis in fatal familial insomnia

BACKGROUND: Neurobehavioral symptoms have been reported anecdotally with aspartame. OBJECTIVE: This study sought to determine whether aspartame can disrupt cognitive, neurophysiologic, or behavioral functioning in normal individuals. DESIGN: Forty-eight healthy volunteers completed a randomized, double-blind, placebo-controlled, crossover study. The first month was aspartame free. Subjects then consumed sodas and capsules with placebo, aspartame, or sucrose for 20 d each. Order was randomized and subjects were assigned to either a high- (45 mg x kg body wt(-1) x d(-1)) or low- (15 mg x kg body wt(-1) x d(-1)) dose aspartame group. Neuropsychologic and laboratory testing was done on day 10 of each treatment period to determine possible acute effects and on day 20 for possible chronic effects. RESULTS: Plasma phenylalanine concentrations increased significantly during aspartame treatment. Neuropsychologic results; adverse experiences; amino acid, insulin, and glucose values; and electroencephalograms were compared by sex and by treatment. No significant differences were found for any dependent measure. CONCLUSION: Large daily doses of aspartame had no effect on neuropsychologic, neurophysiologic, or behavioral functioning in healthy young adults.     

A CMOS analog-digital audio processor for a portable radiotelephone

A mixed analog-digital (A/D) integrated circuit (IC) specifically designed to realize the audio processing functions needed for a portable radiotelephone (PRT) application is described. Multirate signal processing techniques are used to reduce the capacitance spread, and hence the overall silicon area, of the chip, as well as to minimize the settling requirements of the amplifiers for lower power consumption. This, together with programmable power-saving control circuitry also incorporated on-chip, considerably extends the lifetime of the battery. A semicustom design methodology is employed to implement such an application-specific integrated circuit (ASIC) in a 3-μm CMOS double-poly processing technology. Experimental results are presented to demonstrate the correct operation and functionality of the prototype chips     

The effect of opioid antagonists in local regulation of testicular response to acute stress in adult rats

The present study examined the effects of naloxone (N) and naltrexone-methobromide (NMB; an opioid receptor antagonist that does not cross the blood-brain barrier) on testicular steroidogenesis during acute immobilization stress (IMO; 2 h) in adult rats. Unstressed rats as well as IMO rats were treated by unilateral intratesticular injection of N (20 micrograms/testis), NMB (36 micrograms/testis), or vehicle at the beginning of and at 1 h of the IMO period. In IMO rats serum T levels were significantly reduced, while serum luteinizing hormone levels were not affected. N and NMB normalized serum T levels in IMO rats and had no effects in controls. In IMO rats the activities of 3 beta-hydroxysteroid dehydrogenase (HSD) and P450(17 alpha, lyase) were significantly reduced, while the activity of 17 beta-HSD was not affected. N and NMB antagonized the inhibitory effect of IMO on 3 beta-HSD and P450(17 alpha, lyase) but did not alter enzyme activity in freely moving rats. Acute IMO decreased basal and human chorionic gonadotropin-stimulated androgen production by hemitestis preparation, but N (10(-4) M) added directly to the incubation medium blocked the decrease and had no effect on testes from freely moving control rats. These results support the conclusion that endogenous opioid peptides are potentially important paracrine regulators of testicular steroidogenesis under stress conditions.