Functional Nanostructures from Sol-Gel Synthesis Using Keggin Polyoxometallate Phosphotungstic Acid as a Precursor.

Subjecting phosphotungstic acid solutions to low pH in combination with introduction of polyvalent cations led to the formation of nanostructured microspheres of approximately 2 µm in size, as shown by scanning electron microscopy, which were almost insoluble and resistant to degradation at neutral and high pH. These microspheres were composed of secondary nanospheres with diameters around 20 nm as revealed by transmission electron microscopy and atomic force microscopy. Investigations of the crystal structure of a potential intermediate of this process, namely, acidic lanthanum phosphotungstate, [La(H2O)9](H3O)3[PW12O40]2(H2O)19, showed a tight network of hydrogen bonding, permitting closer packing of phosphotungstic acid anions, thereby confirming the mechanism of the observed self-assembly process. The new material demonstrated promising electrochemical properties in oxygen evolution reactions with the high stability of the obtained electrode material.

Compositional Control as the Key for Achieving Highly Efficient OER Electrocatalysis with Cobalt Phosphates Decorated Nanocarbon Florets.

Compositional interplay of two different cobalt phosphates (Co(H2 PO4 )2 ; Co-DP and Co(PO3 )2 ; Co-MP) loaded on morphologically engineered high surface area nanocarbon leads to an increased electrocatalytic efficiency for oxygen evolution reaction (OER) in near neutral conditions. This is reflected as significant reduction in the onset overpotential (301 mV) and enhanced current density (30 mA cm-2 @ 577 mV). In order to achieve uniform surface loading, organic-soluble thermolabile cobalt-bis(di-tert-butylphosphate) is synthesized in situ inside the nanocarbon matrix and subsequently pyrolyzed at 150 °C to produce Co(H2 PO4 )2 /Co(PO3 )2 (80:20 wt%). Annealing this sample at 200 or 250 °C results in the redistribution of the two phosphate systems to 55:45 or 20:80 (wt%), respectively. Detailed electrochemical measurements clearly establish that the 55:45 (wt%) sample prepared at 200 °C performs the best as a catalyst, owing to a relay mechanism that enhances the kinetics of the 4e- transfer OER process, which is substantiated by micro-Raman spectroscopic studies. It is also unraveled that the engineered nanocarbon support simultaneously enhances the interfacial charge-transfer pathway, resulting in the reduction of onset overpotential, compared to earlier investigated cobalt phosphate systems.

Production of poly-3-(hydroxybutyrate-co-hydroxyvalerate) by Haloferax mediterranei using rice-based ethanol stillage with simultaneous recovery and re-use of medium salts.

Haloferax mediterranei holds promise for competitive industrial-scale production of polyhydroxyalkanoate (PHA) because cheap carbon sources can be used thus lowering production costs. Although high salt concentration in production medium permits a non-sterile, low-cost process, salt disposal after process completion is a problem as current environmental standards do not allow total dissolved solids (TDS) above 2000 mg/l in discharge water. As the first objective of this work, the waste product of rice-based ethanol industry, stillage, was used for the production of PHA by H. mediterranei in shake flasks. Utilization of raw stillage led to 71 ± 2% (of dry cell weight) PHA accumulation and 16.42 ± 0.02 g/l PHA production. The product yield coefficient was 0.35 while 0.17 g/l h volumetric productivity was attained. Simultaneous reduction of BOD5 and COD values of stillage by 83% was accomplished. The PHA was isolated by osmotic lysis of cells, purification by sodium dodecyl sulfate and organic solvents. The biopolymer was identified as poly-3-(hydroxybutyrate-co-15.4 mol%-hydroxyvalerate) (PHBV). This first report on utilization of rice-based ethanol stillage for PHBV production by H. mediterranei is currently the most cost effective. As the second objective, directional properties of decanoic acid together with temperature dependence of water solubility in decanoic acid were applied for two-stage desalination of the spent stillage medium. We report for the first time, recovery and re-use of 96% of the medium salts for PHA production thus removing the major bottleneck in the potential application of H. mediterranei for industrial production of PHBV. Final discharge water had TDS content of 670 mg/l.

The mechanistic role of a support-catalyst interface in electrocatalytic water reduction by Co3O4 supported nanocarbon florets.

Comprehending the mechanistic involvement of a support-catalyst interface is critical for effective design of industrially relevant electrocatalytic processes such as the alkaline hydrogen evolution reaction (alHER). The understanding of the kinetically sluggish alHER exhibited by both Pt and Pt-group-metal-free catalysts is primarily derived from indirect electrochemical parameters such as the Tafel slope. To address these issues, we establish the critical role of a nanocarbon floret (NCF) based electrochemical support in generating a key cobalt-oxohydroxo (OH-Co[double bond, length as m-dash]O) intermediate during the alHER through operando Raman spectro-electrochemistry. Specifically, interfacial nano-engineering of a newly designed carbon support (NCF) with a spinel Co3O4 nanocube catalyst is demonstrated to achieve a facile alHER (-0.46 V@10 mA cm-2). Such an efficient alHER is mainly attributed to the unique lamellar morphology with a high mesoporous surface area (936 m2 g-1) of the NCF which catalyses the rate-determining water dissociation step and facilitates rapid ion diffusion. The dissociated water drives the formation of the OH-Co[double bond, length as m-dash]O intermediate, spectroscopically captured for the first time through the emergence of a νOH-Co[double bond, length as m-dash]O Raman peak (1074 cm-1). The subsequent alHER proceeds through the Volmer-Heyrovsky route (119 mV dec-1) via the Td Co2+↔ Co3+↔ Co4+ oxidative pathway. Concomitant graphitization of the NCF through the disappearance of νsp3C-H (2946 cm-1) supports the co-operative dynamics at the Co3O4-NCF interface. Thus, the NCF positively contributes towards the lowering of the overpotential with a low charge-transfer resistance (Rct = 35.8 Ω) and high double layer capacitance (Cdl = 410 mF cm-2).

Anxiety and Stress at Different Stages of Treatment in Women Undergoing In vitro Fertilization-Intracytoplasmic Sperm Injection.

AIM: The aim of the present study is to evaluate the state anxiety (the present state of mind), trait anxiety (general anxiety), as well as perceived stress in women undergoing in vitro fertilization (IVF) treatment at three stages: T1 (on the day of start of stimulation), T2 (on the day of embryo transfer), and T3 (10 days after embryo transfer). The data at T3 level were collected telephonically. METHODOLOGY: The present study was carried out on 137 women undergoing IVF intracytoplasmic sperm injection cycle at four different clinics of four cities from October to April 2016. State-trait anxiety inventory (Spielberger) and perceived stress scale (Okun, et al.) were used as the tools. STATISTICAL ANALYSIS: The analysis was done at two levels; descriptive and inferential (analysis of variance [ANOVA], Student's t-test, Levene's test) using SPSS v16. RESULTS: The state anxiety was higher at all the three levels than trait anxiety. The overt anxiety was highest at T3 level (mean = 45.77) followed by T1 level (mean = 44.23) and T2 level (mean = 43.04). Perceived stress was elevated at T1 level (mean = 17.93) followed by T3 level (mean = 17.28) and T2 level (mean = 16.72). The results of ANOVA showed a significant difference in anxiety among all the three levels (P = 0.036), but no significant difference was found for perceived stress (P = 0.169). t-test revealed that there was a significant difference between state and trait anxiety at T1, T2, and T3 levels (P = 0.01, P = 0.21, P = 0.00, respectively). A significant difference was only seen between the T1 and T2 levels in perceived stress (P = 0.052). In state anxiety, a significant difference was observed only between T2 and T3 levels (P = 0.23). CONCLUSION: It was observed that anxiety and stress are present in women throughout the treatment. The waiting period (T3) is the most anxious for them and their level of state anxiety is higher compared to their trait anxiety. Perceived stress is observed to be more on the day of start of stimulation followed by the waiting period.

Electrochemical, top-down nanostructured pseudocapacitive electrodes for enhanced specific capacitance and cycling efficiency.

Stabilization of the electroactive redox centers on ideally polarisable conductive electrodes is a critical challenge for realizing stable, high performing pseudocapacitive energy storage devices. Here, we report a top-down, electrochemical nanostructuring route based on voltammetric cycling to stabilize ß-MnO2 on a single walled carbon nanotube (CNT) scaffold from a MnMoO4 precursor. Such in situ nanostructuring results in controlled disintegration of an ∼8 µm almond like structure to form ∼29 nm ß-MnO2 resulting in a 59% increase in the specific surface area and a 31% increase in the porosity of the pseudocapacitive electrode. Consequently, the specific capacitance and areal capacitance increase by ∼75% and ∼40%, respectively. Such controlled, top-down nanostructuring is confirmed through binding energy changes to Mo 3d, C 1s, O 1s and Mn 2p respectively in XPS. Furthermore, Raman spectral mapping confirms the sequential nanostructuring initiating from the interface of CNTs with MnMoO4 and proceeding outwards. Thus, the process yields the final CNT/ß-MnO2 electrode that is electrically conductive, facilitates rapid charge transfer, and has increased capacitance and longer stability. Furthermore, the charge-transfer resistance and equivalent resistance are significantly lower compared to conventional activated carbon based electrodes.