Dielectric and Raman Spectroscopic Studies of Na0.5Bi0.5TiO3–BaSnO3 Ferroelectric System

A series of lead‐free perovskite solid solutions of (1 ? x) Na_0.5Bi_0.5TiO₃(NBT)—x BaSnO₃(BSN), for 0.0 ≤ x ≤ 0.15 have been synthesized using a high‐temperature solid‐state reaction route. The phase transition behaviors are studied using dielectric and Raman spectroscopic techniques. The ferroelectric to relaxor phase transition temperature (T_FR) and the temperature corresponding to maximum dielectric permittivity (T_m) are estimated from the temperature‐dependent dielectric data. Dielectric studies show diffuse phase transition around ~335°C in pure NBT and this transition temperature decreases with increase in x. The disappearance of x‐dependence of A₁ mode frequency at ~134 cm^?1 for x ≥ 0.1 is consistent with rhombohedral‐orthorhombic transition. In situ temperature dependence Raman spectroscopic studies show disappearance and discontinuous changes in the phonon mode frequencies across rhombohedral (x < 0.1)/orthorhombic (x ≥ 0.1) to tetragonal transition.     

Sunlight-mediated inactivation of MS2 coliphage via exogenous singlet oxygen produced by sensitizers in natural waters

Pathogens in sunlit surface waters can be damaged directly by UVB light. Indirect inactivation by reactive oxygen species (ROS) generated by sunlight interacting with external sensitizer molecules may also be important, but this mechanism has not been conclusively demonstrated. To better understand the role of ROS, we investigated the inactivation of MS2 coliphage, a commonly used surrogate for human enteric viruses, in water samples irradiated with a solar simulator and containing different types of sensitizers: waste stabilization pond (WSP) constituents, Fluka humic acid (FHA), and Suwannee River humic acid (SRHA). Inactivation of MS2 by the indirect mechanism was significant for all three sensitizers, and the efficiency of the sensitizers at inactivating MS2 was FHA > SRHA > WSP. Both dissolved and particulate fractions in the WSP water contributed to inactivation. In the WSP water, the indirect process was quantitatively more importantthan direct damage by UVB light, due to the rapid attenuation of UVB compared to the longer wavelengths that may initiate the indirect mechanism. Singlet oxygen (1O2) was the most important ROS involved in the inactivation of MS2. The addition of histidine, a 1O2 quencher, decreased inactivation, whereas inactivation rate constants increased in solutions of D20. Selective quenchers for other ROS showed little or no protective effect. Inactivation in WSP water was a function of the steady-state 102 concentration and could be described by a second-order rate expression.     

In‐center hemodialysis attendance: Patient perceptions of risks,barriers, and recommendations

Missed hemodialysis treatments lead to increased morbidity and mortality in the end‐stage renal disease population. Little is known about why patients have difficulty attending their scheduled in‐center dialysis treatments. Semistructured interviews with 15 adherent and 15 nonadherent hemodialysis patients were conducted to determine patients' attitudes about dialysis, health beliefs and risk perception regarding missed treatments, barriers and facilitators to hemodialysis attendance, and recommendations to improve the system to facilitate dialysis attendance. Average time on dialysis was 2.5 years for the nonadherent group and 7.3 years in the adherent group. In both groups, patients felt that dialysis is life‐saving and a necessity. A substantial number of patients in both groups understood that missing hemodialysis treatments is dangerous and several patients could clearly communicate the risk of skipping. The most common barriers to hemodialysis were inadequate or unreliable transportation (mentioned in both groups) and a lack of motivation to get to dialysis or that dialysis is not a priority (typically mentioned by the nonadherent group). Facilitators to hemodialysis attendance included explanations from the health care team regarding the risk of skipping and relationships with other dialysis patients. Patient recommendations to improve dialysis attendance included continued education about the risk of poor attendance and more accessible transportation. Patients did not feel that home dialysis would improve adherence. Hemodialysis patients must adhere to a complex and burdensome regimen. Through the elucidation of barriers and facilitators to hemodialysis attendance and through specific patient recommendations, at least three interventions may be further investigated to improve hemodialysis attendance: Improvement of the transportation system, education and supportive encouragement from the health care team, and peer support mentorship.     

Association with natural organic matter enhances the sunlight-mediated inactivation of MS2 coliphage by singlet oxygen

MS2 coliphage, a surrogate for human enteric viruses, is inactivated by singlet oxygen (1O2) produced via sunlight-mediated excitation of natural organic matter (NOM) in surface waters. The 1O2 concentration within a NOM macromolecule or supramolecular assembly ([1O2]internal) is orders of magnitude higher than in the bulk solution ([1O2]bulk). In close proximity of NOM, MS2 is thus exposed to an elevated 1O2 concentration ([1O2]NOM), and inactivation is likely to be enhanced as compared to the bulk solution. In experiments using a solar simulator, we determined [1O2]bulk, [1O2]internal, as well as the association of MS2 with four NOMs (Fluka humic acid, FHA; Suwannee river humic acid, SRHA; Aldrich humic acid, AHA; Pony lake fulvic acid, PLFA), and studied their effect on the MS2 inactivation rate constant, k(obs), over a range of 1-25 mg NOM/L. The k(obs) values were modeled as the sum of the inactivation rate constants in close proximity to the NOM and in the bulk solution, assuming Langmuir-type adsorption of NOM onto MS2. FHA and SRHA exhibited 13-22 fold greater adsorption equilibrium constants than AHA and PLFA. Inactivation in the bulk solution contributed between 2% (20 mg/L FHA) and 39% (5 mg/L AHA) toward the overall k(obs). Thus, even for the less adsorbing NOM, inactivation was dominated by [1O2]NOM rather than [1O2]bulk. Changes in solution chemistry to promote closer interactions between MS2 and NOM also enhanced k(obs). Addition of Mg2+ to neutralize the negative surface charge of MS2 and NOM increased k(obs) up to 4.1-fold. Similarly, lowering the solution pH closer to the isoelectric point of MS2 (pl = 3.9) enhanced k(ob), 51-fold in 5 mg/L AHA.     

Environmental stresses and skeletal deformities in fish from the Willamette River, Oregon

The Willamette River, one of 14 American Heritage Rivers, flows through the most densely populated and agriculturally productive region of Oregon. Previous biological monitoring of the Willamette River detected elevated frequencies of skeletal deformities in fish from certain areas of the lower (Newberg pool [NP], rivermile [RM] 26 - 55) and middle (Wheatland Ferry [WF], RM 72 - 74) river, relative to those in the upper river (Corvallis [CV], RM 125-138). The objective of this study was to determine the likely cause of these skeletal deformities. In 2002 and 2003, deformity loads in Willamette River fishes were 2-3 times greater at the NP and WF locations than at the CV location. There were some differences in water quality parameters between the NP and CV sites, but they did not readily explain the difference in deformity loads. Concentrations of bioavailable metals were below detection limits (0.6 - 1 microg/ L). Concentrations of bioavailable polychlorinated biphenyls (PCBs) and chlorinated pesticides were generally below 0.25 ng/L. Concentrations of bioavailable polycyclic aromatic hydrocarbons were generally less than 5 ng/L. Concentrations of most persistent organic pollutants were below detection limits in ovary/oocyte tissue samples and sediments, and those that were detected were not significantly different among sites. Bioassay of Willamette River water extracts provided no evidence that unidentified compounds or the complex mixture of compounds present in the extracts could induce skeletal deformities in cyprinid fish. However, metacercariae of a digenean trematode were directly associated with a large percentage of deformities detected in two Willamette River fishes, and similar deformities were reproduced in laboratoryfathead minnows exposed to cercariae extracted from Willamette River snails. Thus, the weight of evidence suggests that parasitic infection, not chemical contaminants, was the primary cause of skeletal deformities observed in Willamette River fish.     

Can bipolar disorder-specific neuropsychological impairments in children be identified?

This study examined neuropsychological deficits among children with bipolar disorder while attending to its comorbidity with attention-deficit/hyperactivity disorder (ADHD). Seventy-three unmedicated children (ages 6-17 years) with Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) bipolar disorder plus ADHD (BPD + ADHD) were compared with 102 unmedicated children with ADHD without bipolar disorder, and 120 children without bipolar disorder or ADHD. Ninety-four percent of participants were Caucasian, 58% were male, and 42% were female. On average participants were of middle to upper socioeconomic status. Participants were assessed with a comprehensive neuropsychological battery and measures of academic achievement, school failure, and special education placement. Participants with BPD + ADHD and with ADHD were impaired in interference control, verbal learning, and arithmetic achievement and had higher rates of special school services. Across all of the measures of neuropsychological functioning, the only difference observed between youths with BPD + ADHD and youths with ADHD was that youths with BPD + ADHD performed more poorly on one measure of processing speed. Thus, comorbidity with ADHD may account for many of the neuropsychological deficits observed in children with bipolar disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrochemical oxidation of the increasingly used disinfectant benzalkonium chloride

Benzalkonium chloride (BAC) is a key ingredient in many cleaning and disinfectant products due to it being an effective antiviral and biocidal agent. Because of its prolific use, especially following the recent global COVID pandemic, increased levels of BAC have been found in the environment, in particular, in wastewater, where it has negative impacts due to its toxicity. This necessitates an effective treatment for BAC in wastewater to reduce its toxicity. In this work, electrochemical oxidation of BAC on a boron-doped diamond anode was studied to successfully remove BAC. The electrochemical measurements performed at different current densities confirmed that BAC was completely oxidized within 20 min of treatment at 50 mA/cm². However, chemical oxygen demand (COD) measurements showed that around 50% of the initial BAC was completely mineralized after 1 h of degradation at 50 mA/cm², while the remaining electrooxidation of BAC resulted in the production of transformation products.     

Crosslinked Aggregates of Fusion Enzymes in Microaqueous Organic Media

Baeyer-Villiger monooxygenases (BVMOs) are attractive for selectively oxidizing various ketones using oxygen into valuable esters and lactones. However, the application of BVMOs is restrained by cofactor dependency and enzyme instability combined with water-related downsides such as low substrate loading, low oxygen capacity, and water-induced side reactions. Herein, we described a redox-neutral linear cascade with in-situ cofactor regeneration catalyzed by fused alcohol dehydrogenase and cyclohexanone monooxygenase in aqueous and microaqueous organic media. The cascade conditions have been optimized regarding substrate concentrations as well as the amounts of enzymes and cofactors with the Design of Experiments (DoE). The carrier-free immobilization technique, crosslinked enzyme aggregates (CLEAs), was applied to fusion enzymes. The resultant fusion CLEAs were proven to function in microaqueous organic systems, in which the enzyme ratios, water contents (0.5–5 vol. %), and stability have been systematically studied. The fusion CLEAs showed promising operational (up to 5 cycles) and storage stability.     

An improved adaptive FastSLAM algorithm with time-varying noise estimator

In this study, an adaptive FastSLAM (AFastSLAM) algorithm, which is obtained by estimating the time-varying noise statistics and improving FastSLAM algorithm, is proposed. This improvement was accomplished by using maximum likelihood estimation and expectation maximization criterion and a one-step smoothing algorithm in importance sampling. In addition, innovation covariance estimation (ICE) method was used to prevent loss of positive definiteness of the process and measurement noise covariance matrices. The proposed method was compared with FastSLAM by calculating the root mean square error (RMSE) using different particle numbers at varying initial process and measurement noise values. Simulation studies have shown that AFastSLAM provides much more accurate, consistent, and successful estimates than FastSLAM for both robot and landmark positions.