Adsorption and photocatalysed destruction of cationic and anionic dyes on mesoporous titania films: Reactions at the air-solid interface

Cationic dyes, such as methylene blue (MB), Thionine (TH) and Basic Fuschin (BF), but not anionic dyes, such as Acid Orange 7 (AO7), Acid Blue 9 (AB9) and Acid Fuschin (AF), are readily adsorbed onto mesoporous titania films at high pH (pH 11), i.e. well above the pzc of titania (pH 6.5), due to electrostatic forces of attraction and repulsion, respectively. The same anionic dyes, but not the cationic dyes, are readily adsorbed on the same titania films at low pH (pH 3), i.e. well below titania's pzc. MB appears to adsorb on mesoporous titania films at pH 11 as the trimer (lambda(max) = 570 nm) but, upon drying, although the trimer still dominates, there is an absorption peak at 665 nm, especially notable at low [MB], which may be due to the monomer, but more likely MB J-aggregates. In contrast, the absorption spectrum of AO7 adsorbed onto the mesoporous titania film at low pH is very similar to the dye monomer. For both MB and AO7 the kinetics of adsorption are first order and yield high rate constants (3.71 and 1.481 g(-1) min(-1)), indicative of a strong adsorption process. Indeed, both MB and AO7 stained films retained much of their colour when left overnight in dye-free pH 11 and 3 solutions, respectively, indicating the strong nature of the adsorption. The kinetics of the photocatalytic bleaching of the MB-titania films at high pH are complex and not well-described by the Julson-Ollis kinetic model [A.J. Julson, D.F. Ollis, Appl. Catal. B. 65 (2006) 315]. Instead, there appears to be an initial fast but not simple demethylation step, followed by a zero-order bleaching and further demethylation steps. In contrast, the kinetics of photocatalytic bleaching of the AO7-titania film give a good fit to the Julson-Ollis kinetic model, yielding values for the various fitting parameters not too dissimilar to those reported for AO7 adsorbed on P25 titania powder. (C) 2008 Elsevier B.V. All rights reserved.

Retention of toxic chromium from aqueous phase by H3PO4-activated lignin: Effect of salts and desorption studies

In this study, the feasibility of using H₃PO₄-activated lignin for hexavalent chromium adsorption has been investigated. The composite of activated lignin was characterized using FTIR, XRD and SEM with EDAX analysis. It was observed that the pH had a strong effect on the adsorption capacity; adsorption of Cr(VI) was more favorable at acidic pH with maximum uptake at pH 2. The adsorption equilibrium data were best represented by Koble-Corrigan isotherm. The monolayer sorption capacity obtained from the Langmuir model was found to be 77.85 mg/g. Adsorption showed pseudo-second order rate kinetics and the process involving the rate-controlling step is complex as it involves both film and intraparticle diffusion processes. The NaOH desorbing agent was able to release approximately 84% of metal ions. Thermodynamic parameters showed that the sorption process is exothermic and non-spontaneous. The overall Cr(VI) retention on the activated lignin surface perhaps includes both the physical adsorption of Cr(VI) and the consequent reduction of Cr(VI) to Cr(III). (C) 2011 Elsevier B.V. All rights reserved.

Association of dietary fat intakes with risk of esophageal and gastric cancer in the NIH-AARP diet and health study

The aim of our study was to investigate whether intakes of total fat and fat subtypes were associated with esophageal adenocarcinoma (EAC), esophageal squamous cell carcinoma (ESCC), gastric cardia or gastric noncardia adenocarcinoma. From 1995–1996, dietary intake data was reported by 494,978 participants of the NIH-AARP cohort. The 630 EAC, 215 ESCC, 454 gastric cardia and 501 gastric noncardia adenocarcinomas accrued to the cohort. Cox proportional hazards regression was used to examine the association between the dietary fat intakes, whilst adjusting for potential confounders. Although apparent associations were observed in energy-adjusted models, multivariate adjustment attenuated results to null [e.g., EAC energy adjusted hazard ratio (HR) and 95% confidence interval (95% CI) 1.66 (1.27–2.18) p for trend <0.01; EAC multivariate adjusted HR (95% CI) 1.17 (0.84–1.64) p for trend 5 0.58]. Similar patterns were also observed for fat subtypes [e.g., EAC saturated fat, energy adjusted HR (95% CI) 1.79 (1.37–2.33) p for trend <0.01; EAC saturated fat, multivariate adjusted HR (95% CI) 1.27 (0.91–1.78) p for trend 5 0.28]. However, in multivariate models an inverse association for polyunsaturated fat (continuous) was seen for EAC in subjects with a body mass index (BMI) in the normal range (18.5–<25 kg/m2) [HR (95% CI) 0.76 (0.63–0.92)], that was not present in overweight subjects [HR (95% CI) 1.04 (0.96–1.14)], or in unstratified analysis [HR (95% CI) 0.97 (0.90–1.05)]. p for interaction 5 0.02. Overall, we found null associations between the dietary fat intakes with esophageal or gastric cancer risk; although a protective effect of polyunsaturated fat intake was seen for EAC in subjects with a normal BMI.

Pan-serotypic detection of foot-and-mouth disease virus using a minor groove binder probe reverse transcription polymerase chain reaction assay

A novel assay for the pan-serotypic detection of foot-and-mouth disease virus (FMDV) was designed using a 5' conjugated minor groove binder (MGB) probe real-time RT-PCR system. This assay targets the 3D region of the FMDV genome and is capable of detecting 20 copies of a transcribed RNA standard. The linear range of the test was eight logs from 2 x 10(1) to 2 x 10(8) copies and amplification time was approximately 2 h. Using a panel of 83 RNA samples from representative FMDV isolates, the diagnostic sensitivity of this test was shown to be equivalent to a TaqMan real-time RT-PCR that targets the 5' untranslated region of FMDV. Furthermore, the assay does not detect viruses causing similar clinical diseases in pigs such as swine vesicular disease virus and vesicular stomatitis virus, nor does it detect marine caliciviruses causing vesicular exanthema. The development of this assay provides a useful tool for the differential diagnosis of FMD, potentially for use in statutory or emergency testing programmes, or for detection of FMDV RNA in research applications. (C) 2011 Elsevier B.V. All rights reserved.

Experimental studies of near-surface temperature cycling and surface wetting of stone and its implications for salt weathering

It has long been accepted that thermal and moisture regimes within stonework exert a major influence upon patterns of salt movement and, subsequently, the type and severity of salt-induced decay. For example, it is suggested that slow drying is more likely to bring dissolved salts to the surface, whereas rapid drying could result in the retention of some salt at or near the frequent wetting depth. In reality however, patterns of heating, cooling and surface wetting regimes that drive them – are complex and inconsistent responses to a wide range of environmental controls. As a first step to understanding the complexity of these relationships, this paper reports a series of experiments within a climatic cabinet designed to replicate the effects of short-term temperature fluctuations on the surface and sub-surface temperature regimes of a porous Jurassic limestone, and how they are influenced by surface wetting, ambient temperature and surface airflow. Preliminary results confirm the significance of very steep temperature/stress gradients within the outer centimetre or less of exposed stone under short-duration cycles of heating and cooling. This is important because this is the zone in which many stone decay processes, particularly salt weathering, operate, these processes invariably respond to temperature and moisture fluctuations, and short-term interruptions to insolation could, for example,
trigger these fluctuations on numerous occasions over a day. The data also indicate that there are complex patterns of temperature reversal with depth that are influenced in their intensity and location by surface wetting and moisture penetration, airflow across the surface and ambient air temperature. The presence of multiple temperature reversals and their variation over the course of heating and cooling phases belies previous assumtions of smooth, exponential increases and decreases in subsurface temperatures in response, for example to diurnal patterns of heating and cooling

Social work education and political conflict: preparing students to address the needs of victims and survivors of the Troubles in Northern Ireland

This paper reports on the evaluation of a European PEACE III sponsored teaching and learning project that was designed to enable social work students to better understand the needs of victims and survivors of the conflict in Northern Ireland. The paper begins with an introduction to policy, practice and educational contexts before reviewing the literature on social work, conflict and trauma. It also summarises key, innovative pedagogical approaches used in the teaching, including the use of ground rules, teaching teams consisting of lecturer and service user dyads, learning exercises and case studies. The paper then explains the evaluation methodology. This involved two surveys which returned 144 student and 34 practice teacher questionnaires. The findings revealed that
students were generally committed to this form of teaching and engagement with victims and survivors of the conflict, although some students reported that their attitudes towards this subject had were not changed. Some students also discussed how the conflict had affected their lives and the lives of families and friends; it is argued that such biographical details are crucial in developing new pedagogical approaches in this area.
Practice teachers who supervised some of these students on placement reported general levels of satisfaction with preparedness to work with conflict related situations but were less convinced that organisations were so committed. The paper concludes with a discussion of the study limitations and a recommendation for more robust methods of teaching and evaluation in this area of social work education and practice.

Speciation and distribution of arsenic and localization of nutrients in rice grains

Arsenic (As) contamination of rice grains and the generally low concentration of micronutrients in rice have been recognized as a major concern for human health. Here, we investigated the speciation and localization of As and the distribution of (micro)nutrients in rice grains because these are key factors controlling bioavailability of nutrients and contaminants. Bulk total and speciation analyses using high-pressure liquid chromatography (HPLC)-inductively coupled plasma mass spectrometry (ICP-MS) and X-ray absorption near-edge spectroscopy (XANES) was complemented by spatially resolved microspectroscopic techniques (micro-XANES, micro-X-ray fluorescence (micro-XRF) and particle induced X-ray emission (PIXE)) to investigate both speciation and distribution of As and localization of nutrients in situ. The distribution of As and micronutrients varied between the various parts of the grains (husk, bran and endosperm) and was characterized by element-specific distribution patterns. The speciation of As in bran and endosperm was dominated by As(III)-thiol complexes. The results indicate that the translocation from the maternal to filial tissues may be a bottleneck for As accumulation in the grain. Strong similarities between the distribution of iron (Fe), manganese (Mn) and phosphorus (P) and between zinc (Zn) and sulphur (S) may be indicative of complexation mechanisms in rice grains.

Uptake, translocation and transformation of arsenate and arsenite in sunflower (Helianthus annuus):formation of arsenic-phytochelatin complexes during exposure to high arsenic concentrations

The aim of the study was to determine the time-dependent formation of arsenic-phytochelatin (As-PC) complexes in the roots, stems and leaves of an arsenic-nontolerant plant (Helianthus annuus) during exposure to 66 mol l(-1) arsenite (As(III)) or arsenate (As(V)). We used our previously developed method of simultaneous element-specific (inductively coupled plasma mass spectrometry, ICP-MS) and molecular-specific (electrospray-ionization mass spectrometry, ES-MS) detection systems interfaced with a suitable chromatographic column and eluent conditions, which enabled us to identify and quantify As-PC complexes directly. Roots of As-exposed H. annuus contained up to 14 different arsenic species, including the complex of arsenite with two (gamma-Glu-Cys)(2)-Gly molecules [As((III))-(PC(2))(2)], the newly identified monomethylarsonic phytochelatin-2 or (gamma-Glu-Cys)(2)-Gly CH(3)As (MA((III))-PC(2)) and at least eight not yet identified species. The complex of arsenite with (gamma-Glu-Cys)(3)-Gly (As((III))-PC(3)) and the complex of arsenite with glutathione (GSH) and (gamma-Glu-Cys)(2)-Gly (GS-As((III))-PC(2)) were present in all samples (roots, stems and leaves) taken from plants exposed to As. The GS-As((III))-PC(2) complex was the dominant complex after 1 h of exposure. As((III))-PC(3) became the predominant As-PC complex after 3 h, binding up to 40% of the As present in the exposed plants. No As-PC complexes were found in sap (mainly xylem sap from the root system), in contrast to roots, stems and leaves, which is unequivocal evidence that As-PC complexes are not involved in the translocation of As from root to leaves of H. annuus.

Synthesis and NMR Characterization of Titanium and Zirconium Oxides Incorporated in SBA-15

Single oxides of Ti and Zr incorporated SBA-15 were prepared and characterized by N-2 adsorption, NMR, and XPS techniques. Si-29 MAS NMR results suggest the formation of Si-O-X linkages (X: Ti or Zr) by an increase in the ratio of Q(3)/Q(4) in the presence of Ti or Zr. XPS analysis of Ti-SBA-15 catalysts indicate the presence of Ti-O-Si bonds in addition to Ti-O-Ti and Si-O-Si bonds, supporting the NMR evidence.

The band structures of gallium and indium selenide

The band structures of the group III-VI monochalcogenides GaSe and InSe have been calculated using a semi-empirical tight-binding method in a two-dimensional approximation. Many of the discrepancies between experimental work and previous calculations for GaSe have been resolved. The results for InSe appear for the first time.

Origin of the Increase of Activity and Selectivity of Nickel Doped by Au, Ag, and Cu for Acetylene Hydrogenation

Activity and selectivity are both important issues in heterogeneous catalysis and recent experimental results have shown that Ni catalysts doped by gold exhibit high activity for the hydrogenation of acetylene with good selectivity of ethylene formation. To unravel the underlying mechanism for this observation, the general trend of activity and selectivity of Ni surfaces doped by Au, Ag, and Cu has been investigated using density functional theory calculations. Complete energy profiles from C2H2 to C2H4 on Ni(111), Au/Ni(111), Ag/Ni(111) and Cu/Ni(111) are obtained and their turnover frequencies (TOFs) are computed. The results show that acetylene adsorption on Ni catalyst is strong which leads to the low activity while the doping of Au, Ag, and Cu on the Ni catalyst weakens the acetylene adsorption, giving rise to the increase of activity. The selectivity of ethylene formation is also quantified by using the energy difference between the hydrogenation barriers and the absolute value of the adsorption energies of ethylene. It is found that the selectivity of ethylene formation increases by doping Au and Ag, while those of Cu/Ni and Ni are similar.

Bactericidal activity of Lys49 and Asp49 myotoxic phospholipases A2 from Bothrops asper snake venom--synthetic Lys49 myotoxin II-(115-129)-peptide identifies its bactericidal region

Mammalian group-II phospholipases A2 (PLA2) of inflammatory fluids display bactericidal properties, which are dependent on their enzymatic activity. This study shows that myotoxins II (Lys49) and III (Asp49), two group-II PLA2 isoforms from the venom of Bothrops asper, are lethal to a broad spectrum of bacteria. Since the catalytically inactive Lys49 myotoxin II isoform has similar bactericidal effects to its catalytically active Asp49 counterpart, a bactericidal mechanism that is independent of an intrinsic PLA2 activity is demonstrated. Moreover, a synthetic 13-residue peptide of myotoxin II, comprising residues 115-129 (common numbering system) near the C-terminal loop, reproduced the bactericidal effect of the intact protein. Following exposure to the peptide or the protein, accelerated uptake of the hydrophobic probe N-phenyl-N-naphthylamine was observed in susceptible but not in resistant bacteria, indicating that the lethal effect was initiated on the bacterial membrane. The outer membrane, isolated lipopolysaccharide (LPS), and lipid A of susceptible bacteria showed higher binding to the myotoxin II-(115-129)-peptide than the corresponding moieties of resistant strains. Bacterial LPS chimeras indicated that LPS is a relevant target for myotoxin II-(115-129)-peptide. When heterologous LPS of the resistant strain was present in the context of susceptible bacteria, the chimera became resistant, and vice versa. Myotoxin II represents a group-II PLA2 with a direct bactericidal effect that is independent of an intrinsic enzymatic activity, but adscribed to the presence of a short cluster of basic/hydrophobic amino acids near its C-terminal loop.

Comparison of dynamics of wildtype and V94M human UDP-galactose 4-epimerase-A computational perspective on severe epimerase-deficiency galactosemia

UDP-galactose 4'-epimerase (GALE) catalyzes the interconversion of UDP-galactose and UDP-glucose, an important step in galactose catabolism. Type III galactosemia, an inherited metabolic disease, is associated with mutations in human GALE. The V94M mutation has been associated with a very severe form of type III galactosemia. While a variety of structural and biochemical studies have been reported that elucidate differences between the wildtype and this mutant form of human GALE, little is known about the dynamics of the protein and how mutations influence structure and function. We performed molecular dynamics simulations on the wildtype and V94M enzyme in different states of substrate and cofactor binding. In the mutant, the average distance between the substrate and both a key catalytic residue (Tyr157) and the enzyme-bound NAD(+) cofactor and the active site dynamics are altered making substrate binding slightly less stable. However, overall stability or dynamics of the protein is not altered. This is consistent with experimental findings that the impact is largely on the turnover number (kcat), with less substantial effects on Km. Active site fluctuations were found to be correlated in enzyme with substrate bound to just one of the subunits in the homodimer suggesting inter-subunit communication. Greater active site loop mobility in human GALE compared to the equivalent loop in Escherichia coli GALE explains why the former can catalyze the interconversion of UDP-N-acetylgalactosamine and UDP-N-acetylglucosamine while the bacterial enzyme cannot. This work illuminates molecular mechanisms of disease and may inform the design of small molecule therapies for type III galactosemia.

A prospective cohort study of obesity and risk of oesophageal and gastric adenocarcinoma in the NIH-AARP Diet and Health Study

Objective: The incidence of oesophageal adenocarcinoma (EAC) has increased rapidly over the past 40 years and accumulating evidence suggests that obesity, as measured by body mass index (BMI), is a major risk factor. It remains unclear whether abdominal obesity is associated with EAC and gastric adenocarcinoma.

Design: Cox proportional hazards regression was used to examine associations between overall and abdominal obesity with EAC and gastric adenocarcinoma among 218 854 participants in the prospective NIHeAARP cohort.

Results: 253 incident EAC, 191 gastric cardia adenocarcinomas and 125 gastric non-cardia adenocarcinomas accrued to the cohort. Overall obesity (BMI) was positively associated with EAC and gastric
cardia adenocarcinoma risk (highest ($35 kg/m2) vs referent (18.5e<25 kg/m2); HR 2.11, 95% CI 1.09 to 4.09 and HR 3.67, 95% CI 2.00 to 6.71, respectively). Waist circumference was also positively associated with EAC and gastric cardia adenocarcinoma risk (highest vs referent; HR 2.01, 95% CI 1.35 to 3.00 and HR 2.22, 95% CI 1.43 to 3.47, respectively), whereas waist-to-hip ratio (WHR) was positively associated with EAC risk only (highest vs referent; HR 1.81, 95% CI 1.24 to 2.64) and persisted in patients with normal BMI (18.5e<25 kg/m2). Mutual adjustment of WHR and BMI attenuated
both, but did not eliminate the positive associations for either with risk of EAC. In contrast, the majority of the anthropometric variables were not associated with adenocarcinomas of the gastric non-cardia.

Conclusion Overall obesity was associated with a higher risk of EAC and gastric cardia adenocarcinoma, whereas abdominal obesity was found to be associated with increased EAC risk; even in people with normal BMI