Operando XAS/XRD and Raman Spectroscopic Study of Structural Changes of the Iron Molybdate Catalyst during Selective Oxidation of Methanol

The structural changes of an iron molybdate/molybdenum oxide (Mo/Fe=2.0) catalyst for the selective oxidation of methanol to formaldehyde were studied using combined operando X‐ray absorption spectroscopy (XAS) and X‐ray diffraction (XRD) as well as operando Raman spectroscopy. Under operating conditions, the Mo K‐edge XANES spectra showed a transition from a mixture of α‐MoO$_{3}$ and Fe$_{2}$(MoO$_{4}$)$_{3}$ towards only Fe$_{2}$(MoO$_{4}$)$_{3}$. XRD and Raman spectroscopy also showed disappearance of the α‐MoO3 phase with time on stream. The results evidenced that the α‐MoO3 component evaporated completely, while the Fe$_{2}$(MoO$_{4}$)$_{3}$ component remained stable. This was linked to a decrease in catalytic activity. Further studies unraveled that the rate of α‐MoO$_{3}$ evaporation increased with increasing MeOH concentration, decreasing O$_{2}$ concentration and increasing temperature. The simultaneous measurements of catalytic activity and spectroscopy allowed to derive a structure‐activity relationship showing that α‐MoO$_{3}$ evaporation needs to be prevented to optimize MoO$_{3}$‐based catalysts for selective oxidation of methanol

SOILS Ammonium and Nitrate Nitrogen in Soil Profiles of Long-Term Winter Wheat Fertilization Experiments

ABSTRACT Accumulation of NH~ -N and NO3 -N in soils has not been thor. oughly evaluated in long-term continuous winter wheat (Triticum aes. tivum L.) production systems. The objectives of this study were to determine long-term response of winter wheat to N fertilization and to evaluate accumulation of NH~ -N and NO3 -N in the soil profile. Four long-term winter wheat soil fertility experiments on thermic Ustoll soils that received annual applications of N for > 18 yr at selected N rates were sampled. At each location, one soil core 4.4 cm in diameter was taken to a depth of 240 cm from plots receiving variable N rates. Cores were separated into 30-cm increments and analyzed for 2 M KCI-extractable NH~ -N and NO~-N. At all locations, NH~ -N levels were not significantly different from the check (no fertilizer N) when rates were applied at or below yield goal requirements (90 or45 kg N ha -~ vs. 0 N). At N rates >90 kg N ha -~, surface (0-15 cm) NH~ -N increased compared with the check, while subsurface NH~ -N did not. Similarly, when N rates were <90 kg N ha -~, no significant differences in either surface or subsurface NO 3 -N were found. At N rates >90 kg N ha -1, NO5 -N accumulated in the subsurface soil profile (>30 cm). Estimates of N rates determined from simultaneous solutions of NO5 -N accumulation minimums and yield maximums generated from quadratic regression were greater than N rates currently recommended to achieve yield goals at all locations. For these long-term continuous winter wheat experiments, no accumulation of NH~ -N and NO5 -N occurred at recommended N rates where near maximum yields were obtained. p AST AND PRESENT use of N fertilizers for winter wheat production has been related to the potential for NOA--N contamination of surface and subsurface water. Although N fertilizers are essential for economic grain production, long-term N accumulation as a result of excessive N rates has not been monitored closely. Work by Liang et al. (1991) found that residual soil NO~--N did not increase in the soil profile (0-60 cm) over a 4-yr period when comparing N rates of 170 and 400 kg ha -1 applied to corn. MacDonald et al. (1989) indicated that following harvest, unfertilized wheat plots had inorganic N contents equal to those where 234 kg N ha -1 had been applied. This work further suggested that almost all of the NO~--N at risk to leaching over the winter period comes from mineralization of organic N and not from unused fertilizer applied in the spring; therefore, even a drastic reduction in N fertilizer use would have little effect on NO~--N leaching. Lamb et al. (1985) reported that the addition of N fertilizer increased the amount of NO~-N accumulated but did not change the accumulation pattern. Tillage system (no-till, stubble mulch, and plow) did not affect the time at which the NOA--N started to accumulate during the fallow period nor the rate of accumulation (Lamb et al., 1985). Sharpley al. (1991) reported no evidence of N accumulation the soil profile (0--180 cm) after 5 yr for either no-till or reduced-till cultural practices with N fertilizer applied to sorghum at recommended rates (0--146 kg ha-1 yr-1), although annual total N in surface runoff . was 0.76 kg N ha -1 for no-till, 0.99 kg N ha -1 for reduced-till, and 7.28 kg N ha -1 for conventional till. Smika (1990) reported that time must be allowed for the equilibration of soil conditions before evaluating NO~--N accumulation, citing research that showed less NO~--N accumulation to 120 cm for reduced-till methods compared with conventional tillage for short-term studies, but more NO~--N accumulation for reducedtill methods in long-term studies. Tracy et al. (1990) noted that tillage method (conventional, no-till) did not affect NO~--N accumulation below 5 cm; differences in NO~--N in the topsoil were attributed to organic matter incorporation over 16 yr of winter wheat farming. Varvel and Peterson (1990) reported that high N application rates (180 kg N ha-1) resulted in greater residual soil NO~--N to 150 cm for continuous corn and grain sorghum systems than for other cropping systems. This same study found that all systems had similar NO~--N accumulation at lower N application rates. Work by Liang et al. (1991) found that under irrigation, 100 kg NOA--N ha -~ was lost from the rooting zone (0-60 cm) during four growing seasons, with the majority coming from the surface 40 cm. The effects of N fertilizer rate (90 and 180 kg ha -x) and nitrification inhibitors on urea lSN leaching and balance on a irrigated sandy loam were summarized by Waiters and Malzer (1990). The higher N application rate resulted in 3.4 times more N leached over a 3-yr period (206 vs. 88 kg ha -1 to 1.2 m depth). Nitrification inhibitors delayed N losses, but did not decrease the total N lost. Westerman and Tucker (1979) noted that the presence of organic residue can lower denitrification by increased immobilization of inorganic or mineralized N. Immobilization was thus considered to be an N conserving process competing with denitrification for nitrate. Nitrate studies in field microplots showed that 17% of applied 15N (120 kg N ha -~ equivalent) was still in the 45-cm soil profile after 1 yr (Kowalenko, 1989). Webster et al. (1986) evaluated the movement (92 and 102 kg NHnNO 3 ha -~) in clay and sandy loam field microplots and found that < 1% of the fertilizer was leached beyond 130 cm in the first winter following application. Response of wheat grain yields to N fertilization has been documented in numerous soil fertility experiments. However, very few of these experiments have included evaluation for more than 3 to 5 yr that also accounted for accumulation of NOA--N and NH~--N within the soil profile. The objectives of this study were to determine the long-term response of 9

The challenges of renewed independence: The Baltic states since 1991

This article offers a comparative assessment of how successfully Estonia, Latvia, and Lithuania have coped with the challenges of renewed independence since 1991, focusing on various aspects of political, economic, and social development. In the post-communist context the Baltic states have clearly outpaced other former Soviet republics and also performed reasonably well in comparison to the countries of Eastern Europe. The convergence of the Baltic experience, which began already in the early 20th century, has continued in the recent past as well, as the three states have adopted a number of similar approaches in domestic politics, the search for security, and economic policy. They also face a number of similar unsolved problems, including considerable political alienation, tensions in relations with Russia, socioeconomic disparity, and demographic challenges. The most important difference in the issues confronting the Baltic states today continues to be the large non-Baltic, mainly Russian presence in Estonia and Latvia, a result of Soviet-era policies. How to effect the meaningful integration of a multiethnic society remains a continuing challenge in these two countries. In contrast, population shifts under Soviet rule never became massive in Lithuania, and ethnic relations are a minor issue there today

A meta-analysis of long-term effects of conservation agriculture on maize grain yield under rain-fed conditions

Conservation agriculture involves reduced tillage, permanent soil cover and crop rotations to enhance soil fertility and to supply food from a dwindling land resource. Recently, conservation agriculture has been promoted in Southern Africa, mainly for maize-based farming systems. However, maize yields under rain-fed conditions are often variable. There is therefore a need to identify factors that influence crop yield under conservation agriculture and rain-fed conditions. Here, we studied maize grain yield data from experiments lasting 5 years and more under rain-fed conditions. We assessed the effect of long-term tillage and residue retention on maize grain yield under contrasting soil textures, nitrogen input and climate. Yield variability was measured by stability analysis. Our results show an increase in maize yield over time with conservation agriculture practices that include rotation and high input use in low rainfall areas. But we observed no difference in system stability under those conditions. We observed a strong relationship between maize grain yield and annual rainfall. Our meta-analysis gave the following findings: (1) 92% of the data show that mulch cover in high rainfall areas leads to lower yields due to waterlogging; (2) 85% of data show that soil texture is important in the temporal development of conservation agriculture effects, improved yields are likely on well-drained soils; (3) 73% of the data show that conservation agriculture practices require high inputs especially N for improved yield; (4) 63% of data show that increased yields are obtained with rotation but calculations often do not include the variations in rainfall within and between seasons; (5) 56% of the data show that reduced tillage with no mulch cover leads to lower yields in semi-arid areas; and (6) when adequate fertiliser is available, rainfall is the most important determinant of yield in southern Africa. It is clear from our results that conservation agriculture needs to be targeted and adapted to specific biophysical conditions for improved impact

Assessment of xenoestrogenic exposure by a biomarker approach: application of the E-Screen bioassay to determine estrogenic response of serum extracts

BACKGROUND: Epidemiological documentation of endocrine disruption is complicated by imprecise exposure assessment, especially when exposures are mixed. Even if the estrogenic activity of all compounds were known, the combined effect of possible additive and/or inhibiting interaction of xenoestrogens in a biological sample may be difficult to predict from chemical analysis of single compounds alone. Thus, analysis of mixtures allows evaluation of combined effects of chemicals each present at low concentrations. METHODS: We have developed an optimized in vitro E-Screen test to assess the combined functional estrogenic response of human serum. The xenoestrogens in serum were separated from endogenous steroids and pharmaceuticals by solid-phase extraction followed by fractionation by high-performance liquid chromatography. After dissolution of the isolated fraction in ethanol-DMSO, the reconstituted extract was added with estrogen-depleted fetal calf serum to MCF-7 cells, the growth of which is stimulated by estrogen. After a 6-day incubation on a microwell plate, cell proliferation was assessed and compared with the effect of a 17-beta-estradiol standard. RESULTS AND CONCLUSIONS: To determine the applicability of this approach, we assessed the estrogenicity of serum samples from 30 pregnant and 60 non-pregnant Danish women thought to be exposed only to low levels of endocrine disruptors. We also studied 211 serum samples from pregnant Faroese women, whose marine diet included whale blubber that contain a high concentration of persistent halogenated pollutants. The estrogenicity of the serum from Danish controls exceeded the background in 22.7 % of the cases, while the same was true for 68.1 % of the Faroese samples. The increased estrogenicity response did not correlate with the lipid-based concentrations of individual suspected endocrine disruptors in the Faroese samples. When added along with the estradiol standard, an indication of an enhanced estrogenic response was found in most cases. Thus, the in vitro estrogenicity response offers a promising and feasible approach for an aggregated exposure assessment for xenoestrogens in serum

Agentic learning: the pedagogical implications of young trans people’s online learning strategies

This paper proposes anew conceptualisation of learning in the age of the internet, increasing systemic rigidity of formal education and intensified media manipulation and partiality. Using empirical data and drawing on Social Activity Method it elaborates the different strategies young trans people recruit in their self-learning and contends that these constitute a type of learning where the control of pedagogy, the learning environment and the subject matter lies to a significant extent, with the learner, taking place in spaces free from the influence of hegemonic transphobia. This type of learning appears to constitute an effective but complex one. As, in this instance, the learning is taking place in a wider cultural environment where the subject matter is often suppressed and subject to ideological misrepresentation by hegemonic control of the public sphere, this study suggests that learning by providing learners with greater control over pedagogy and learning environment is effective

Reversal of Obesity and Insulin Resistance by a Non-Peptidic Glucagon-Like Peptide-1 Receptor Agonist in Diet-Induced Obese Mice

BACKGROUND: Glucagon-like peptide-1 (GLP-1) is recognized as an important regulator of glucose homeostasis. Efforts to utilize GLP-1 mimetics in the treatment of diabetes have yielded clinical benefits. A major hurdle for an effective oral therapy has been the difficulty of finding a non-peptidic GLP-1 receptor (GLP-1R) agonist. While its oral bioavailability still poses significant challenges, Boc5, one of the first such compounds, has demonstrated the attainment of GLP-1R agonism in diabetic mice. The present work was to investigate whether subchronic Boc5 treatment can restore glycemic control and induce sustainable weight loss in diet-induced obese (DIO) mice, an animal model of human obesity and insulin resistance. METHODOLOGY/PRINCIPAL FINDINGS: DIO mice were treated three times a week with Boc5 (0.3, 1 and 3 mg) for 12 weeks. Body weight, body mass index (BMI), food intake, fasting glucose, intraperitoneal glucose tolerance and insulin induced glucose clearance were monitored regularly throughout the treatment. Glucose-stimulated insulin secretion, β-cell mass, islet size, body composition, serum metabolic profiles, lipogenesis, lipolysis, adipose hypertrophy and lipid deposition in the liver and muscle were also measured after 12 weeks of dosing. Boc5 dose-dependently reduced body weight, BMI and food intake in DIO mice. These changes were associated with significant decreases in fat mass, adipocyte hypertrophy and peripheral tissue lipid accumulation. Boc5 treatment also restored glycemic control through marked improvement of insulin sensitivity and normalization of β-cell mass. Administration of Boc5 (3 mg) reduced basal but enhanced insulin-mediated glucose incorporation and noradrenaline-stimulated lipolysis in isolated adipocytes from obese mice. Furthermore, circulating leptin, adiponectin, triglyceride, total cholesterol, nonesterified fatty acid and high-density lipoprotein/low-density lipoprotein ratio were normalized to various extents by Boc5 treatment. CONCLUSIONS/SIGNIFICANCE: Boc5 may produce metabolic benefits via multiple synergistic mechanisms and may represent an attractive tool for therapeutic intervention of obesity and diabetes, by means of non-peptidic GLP-1R agonism