Evaluation of humic acid photocatalytic degradation by UV–vis and fluorescence spectroscopy

Photodegradation of humic substances causes drastic changes in the UV–vis absorption and fluorescence properties of humic acids. In this study it is intended to fulfill the lack of knowledge about the spectral changes of humic acids during photocatalytic oxidation processes and elucidate the effects observed on the molecular size distribution of humic acid focusing on their analysis by UV–vis and fluorescence spectroscopy.

As confirmed by the spectroscopic evaluation of the molecular size distribution data, photocatalytic degradation of humic acid leads to the formation of lower molecular size (small fractions) and higher UV absorbing compounds. For fractions less than 10 kDa, UV₂₅₄ absorbing moieties in treated humic acid samples become higher than that of raw humic acid designating the generation of new species during photocatalysis. UV–vis spectroscopic changes were also evaluated by the parameters relating to the concomitant removal of the total organic carbon as well as by the ratios using absorption values at discrete wavelengths. Moreover, the fluorescence spectra of treated humic acid samples show decreasing intensity profiles with increasing photocatalytic irradiation time.     

The TeO2-Na2O System: Thermal Behavior,Structural Properties,and Phase Equilibria

Thermal behavior, structural properties, and phase equilibria of the (100−x)TeO₂-xNa₂O system were studied in the 5 ≤ x ≤ 50 mol% composition range. Investigation of glass formation behavior in the binary system was realized, and the glass formation range was determined as 7.5 ≤ x ≤ 40 mol%. Differential thermal analysis (DTA) and Fourier transform infrared (FTIR) spectroscopy techniques were used for thermal and structural characterization of the glasses. Influence of Na₂O content on glass transition temperature (T_g), glass stability (∆T), density (ρ), molar volume (V_M), oxygen molar volume (V_O), and oxygen packing density (OPD) values of sodium tellurite glasses was evaluated considering the structural transformations in the glass network. For the phase equilibria studies, DTA, X-ray diffraction (XRD), and scanning electron microscopy/energy dispersive X-ray (SEM/EDS) techniques were utilized to characterize the heat-treated samples. According to the phase equilibria studies, three eutectic regions were detected in the 0 < x < 50 mol% composition range of the (100−x)TeO₂-xNa₂O system. A new invariant endothermic reaction was detected for the compositions between 40 ≤ x ≤ 45 mol%. Na₂O.8TeO₂ (11.11 mol% Na₂O) compound that was claimed to exist in the binary system in the literature was found to be the metastable δ-TeO₂ phase.     

Evidence for a Turner syndrome locus or loci at Xp11.2-p22.1

Turner syndrome is the complex human phenotype associated with complete or partial monosomy X. Principle features of Turner syndrome include short stature, ovarian failure, and a variety of other anatomic and physiological abnormalities, such as webbed neck, lymphedema, cardiovascular and renal anomalies, hypertension, and autoimmune thyroid disease. We studied 28 apparently nonmosaic subjects with partial deletions of Xp, in order to map loci responsible for various components of the Turner syndrome phenotype. Subjects were carefully evaluated for the presence or absence of Turner syndrome features, and their deletions were mapped by FISH with a panel of Xp markers. Using a statistical method to examine genotype/phenotype correlations, we mapped one or more Turner syndrome traits to a critical region in Xp11.2-p22.1. These traits included short stature, ovarian failure, high-arched palate, and autoimmune thyroid disease. The results are useful for genetic counseling of individuals with partial monosomy X. Study of additional subjects should refine the localization of Turner syndrome loci and provide a rational basis for exploration of candidate genes.     

Combining functional near-infrared spectroscopy and EEG measurements for the diagnosis of attention-deficit hyperactivity disorder

Neural Computing and Applications - Recently multimodal neuroimaging which combines signals from different brain modalities has started to be considered as a potential to improve the accuracy of...     

Comparative study of bone mineralization in children and adolescents with familial short stature and a control group

Within the past year there has been a dramatic increase in the number of molecular epidemiologic studies reported in the literature, particularly those evaluating gene-gene and gene-environment interactions. Molecular epidemiologic studies have become more sophisticated owing to collaborations between laboratory scientists and epidemiologists, and because these studies are now conducted on well-characterized populations with appropriate study design. Although there continue to be inconsistencies across some studies, it is clear that the evaluation of gene-gene and gene-environment interactions can delineate portions of the population who are particularly sensitive to certain carcinogenic exposures, based on polymorphisms in genes involved in preventing and controlling carcinogenesis. Identification of these subsets of susceptible individuals can result in the design of preventive strategies targeting the most "at risk" populations.     

Processing and properties of modified polyamide 66-organoclay nanocomposites

Binary polyamide 66 nanocomposites containing 2 wt % organoclay, polyamide 66 blend containing 5 wt % impact modifier, and ternary polyamide 66 nanocomposites containing 2 wt % organoclay and 5 wt % impact modifier were prepared by melt compounding method. The effects of E-GMA and the types of the organoclays on the interaction between the organoclay and the polymer, dispersion of the organoclay, morphology, mechanical, flow, and thermal properties of the nanocomposites were investigated. Partial exfoliation and improved mechanical properties are observed for Cloisite® 15A and Cloisite® 25A nanocomposites. On the other hand, the organoclay was intercalated or in the form of tactoids in Cloisite® 30B nanocomposites. Components of the nanocomposites containing Cloisite® 15A and Cloisite® 25A were compounded in different addition orders. Mixing sequence of the components affected both the dispersion of the organoclay and the mechanical properties drastically. SEM analyses revealed that homogeneous dispersion of the organoclay results in a decrease in the domain sizes and promotes the improvements in the toughness of the materials. Melt viscosity was also found to have a profound effect on the dispersion of the organoclay according to MFI and XRD results. Crystallinity of the nanocomposites did not change significantly. It is only the type of the constituents and their addition order what dramatically influence the nanocomposite properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Template‐Assisted Synthesis of Metallic 1T′‐Sn0.3W0.7S2 Nanosheets for Hydrogen Evolution Reaction

Crystal phase control still remains a challenge for the precise synthesis of 2D layered metal dichalcogenide (LMD) materials. The T′ phase structure has profound influences on enhancing electrical conductivity, increasing active sites, and improving intrinsic catalytic activity, which are urgently needed for enhancing hydrogen evolution reaction (HER) activity. Theoretical calculations suggest that metastable T′ phase 2D Sn_1?xW_xS₂ alloys can be formed by combining W with 1T tin disulfide (SnS₂) as a template to achieve a semiconductor‐to‐metallic transition. Herein, 2D Sn_1?xW_xS₂ alloys with varying x are prepared by adjusting the molar ratio of reactants via hydrothermal synthesis, among which Sn_0.3W_0.7S₂ displays a maximum of concentration of 81% in the metallic phase and features a distorted octahedral‐coordinated metastable 1T′ phase structure. The obtained 1T′‐Sn_0.3W_0.7S₂ has high intrinsic electrical conductivity, lattice distortion, and defects, showing a prominently improved HER catalytic performance. Metallic Sn_0.3W_0.7S₂ coupled with carbon black exhibits at least a 215‐fold improvement compared to pristine SnS₂. It has excellent long‐term durability and HER activity. This work reveals a general phase transition strategy by using T phase materials as templates and merging heteroatoms to achieve synthetic metastable phase 2D LMDs that have a significantly improved HER catalytic performance.     

Effect of the Icing with Rosemary Extract on the Oxidative Stability and Biogenic Amine Formation in Sardine (Sardinella aurita) During Chilled Storage

The effect of icing with the rosemary extract on the quality and safety of sardines (Sardinella aurita) was assessed through the chemical, sensory and microbiological methods. The sensory acceptability limit was 12?days for sardine stored in traditional ice and 15?days for sardine stored in ice prepared from rosemary extract solution. There were no significant differences between sardine stored in ice with both 0.05% and 0.1% rosemary extract in terms of sensory acceptability. Storage of sardine in ice containing rosemary extract improved the sensory and some of the chemical quality parameters as compared with the traditional icing, which resulted in a significant extension in the shelf life of sardine. Eleven biogenic amines were determined for food quality and safety. Icing containing rosemary extract had a positive effect, causing low biogenic amine content, especially histamine and putrescine. Histamine content of sardine also increased rapidly with time when the number of bacteria reached above 10⁶ cell/g, which is a good correlation between histamine content and number of bacteria. Consequently, the application of ice containing rosemary extract improved the quality and safety of sardine, which can be explored by the food industry.     

Effect of the type of frying oil on volatile compounds of goatfish (Upeneus pori) during cold storage

The effect of different types of oil (sunflower, soybean, corn and canola oil) on the volatile formation of fried goatfish (Upeneus pori) during refrigerated (2 °C) storage period were assessed in this study. When using the SPME technique, forty‐three compounds were detected. Among the detected compounds twelve aldehydes, nine alcohols, nine acids, three ketones, four amines and seven other compounds were found in raw and fried goatfish during refrigerated storage periods. Frying with different types of oil had significant influence on the volatile compounds of goatfish. However, considerable differences observed in the formation of some volatile compounds depending on type of frying oil. It was also concluded that, changes in volatile compounds during cold storage periods were not good spoilages markers for fried goatfish.     

Evaluation of an application factor for determining the safe concentration of agricultural and industrial chemicals

Present investigations were undertaken to evaluate the “Application Factor” (being a fraction of TL₅₀) for a number of chemicals by determining 96 h LC₅₀ and Maximum allowable toxicant concentration (MATC) using larvae and early juveniles of Cirrhina mrigala. The chemicals used were thiotox, aldrin, chlordane, lindane, benzene hexachloride (organochlorine pesticides); malathion, metasystox, dichlorvos, thiometon, abate (organophosphate pesticides); carbofuran, sevin (carbamate pesticides); phenol, 2,4-dinitrophenol, pentachlorophenol (phenolic compounds); copper sulphate, cadmium chloride, zinc sulphate, mercuric chloride (heavy metals) and swascofix P₁₄, swanic 6L, swascol 1L, swascol 3L, swascol 4L (synthetic detergent). Application factors for these chemicals range between 0.036 and 0.079. It was observed that the values of Application Factor for most of the chemicals remained within the limited range, in spite of a wide range in their MATC.