Crystal chemistry and single-phase synthesis of Gd3+ substituted Co–Zn ferrite nanoparticles for enhanced magnetic properties

Rare earth (RE) ions are known to improve the magnetic interactions in spinel ferrites if they are accommodated in the lattice, whereas the formation of a secondary phase leads to the degradation of the magnetic properties of materials. Therefore, it is necessary to solubilize the RE ions in a spinel lattice to get the most benefit. In this context, this work describes the synthesis of Co–Zn ferrite nanoparticles and the Gd³⁺ doping effect on the tuning of their magnetic properties. The modified sol–gel synthesis approach offered a facile way to synthesize ferrite nanoparticles using water as the solvent. X-ray diffraction with Rietveld refinement confirmed that both pure Co–Zn ferrite and Gd³⁺ substituted Co–Zn ferrite maintained single-phase cubic spinel structures. Energy dispersive spectroscopy was used to determine the elemental compositions of the nanoparticles. Field and temperature dependent magnetic characteristics were measured by employing a vibration sample magnetometer in field cooled (FC)/zero field cooled (ZFC) modes. Magnetic interactions were also determined by Mössbauer spectroscopy. The saturation magnetization and coercivity of Co–Zn ferrite were improved with the Gd³⁺ substitution due to the Gd³⁺ (4f⁷)–Fe³⁺ (3d⁵) interactions. The increase in magnetization and coercivity makes these Gd³⁺ substituted materials applicable for use in magnetic recording media and permanent magnets.

Rare earth (RE) ions are known to improve the magnetic interactions in spinel ferrites if they are accommodated in the lattice, whereas the formation of a secondary phase leads to the degradation of the magnetic properties of materials.     

Improved outcomes after aortic valve surgery for chronic aortic regurgitation with severe left ventricular dysfunction.

OBJECTIVES: Among patients undergoing aortic valve surgery for chronic aortic regurgitation (AR), we sought to: 1) compare survival among those with and without severe left ventricular dysfunction (LVD); 2) identify risk factors for death, including LVD and date of operation; and 3) estimate contemporary risk for cardiomyopathic patients. BACKGROUND: Patients with chronic AR and severe LVD have been considered high risk for aortic valve surgery, with limited prognosis. Transplantation is considered for some. METHODS: From 1972 to 1999, 724 patients underwent surgery for chronic AR; 88 (12%) had severe LVD. They were propensity matched to patients with nonsevere LVD to compare hospital mortality, interaction of operative date with severity of LVD, and late survival. Propensity score-adjusted multivariable analysis was performed for all 724 patients to identify risk factors for death. RESULTS: Survival was lower (p = 0.04) among patients with severe LVD than among matched patients with nonsevere LVD (30-day, 1-, 5-, and 25-year survival estimates were 91% vs. 96%, 81% vs. 92%, 68% vs. 81%, and 5% vs. 12%, respectively). However, survival of patients with severe LVD improved dramatically across the study time frame (p = 0.0004): hospital mortality decreased from 50% in 1975 to 0% after 1985, and time-related survival in patients with severe LVD operated on since 1985 became equivalent to that of matched patients with nonsevere LVD (p = 0.96). CONCLUSIONS: Neutralizing risk of severe LVD has improved early and late survival such that aortic valve surgery for chronic AR and cardiomyopathy is no longer a high-risk procedure for which transplantation is the best option.     

Sterility in Zambia

Background : Several regions such as Zambia in sub-Saharan Africa experience very high levels of sterility. Current explanations for high levels of sterility in Zambia have focused on biological determinants and have paid little attention to the plausible effects of social determinants of sterility. Aim : This study has two objectives. The first objective is to examine the extent of sterility in Zambia during 1980 and 1990. The second objective is to assess the contribution of selected social determinants to the current levels of sterility in Zambia. Subjects and methods : Sterility among women in Zambia is calculated for two periods in 1980 and 1990 using census data. The study used parity progression ratios for the calculation of sterility rates. Selected social determinants of Zambian sterility were obtained from the Demographic Health Survey (ZDHS). Net effects of selected social determinants were examined using logistic regression. Results : High sterility levels were found in a few Zambian Provinces. During 1980 and 1990, the rates for North Western, Eastern and Western provinces remained considerably higher than for other Zambian provinces. It was found that social level variables remained strong and significant even after controlling for the effects of incidence of biological factors such as sexually transmitted diseases (STDs). Conclusions : The findings of the study support the importance of developing social policies for eradicating sterility. The argument that sterility is biological and that it is not amenable to social interventions perhaps needs revision in the light of the findings of this study.     

Development and validation of the General Health Numeracy Test (GHNT)

Objective

Because existing numeracy measures may not optimally assess ‘health numeracy’, we developed and validated the General Health Numeracy Test (GHNT).

Methods

An iterative pilot testing process produced 21 GHNT items that were administered to 205 patients along with validated measures of health literacy, objective numeracy, subjective numeracy, and medication understanding and medication adherence. We assessed the GHNT's internal consistency reliability, construct validity, and explored its predictive validity.

Results

On average, participants were 55.0 ± 13.8 years old, 64.9% female, 29.8% non-White, and 51.7% had incomes ≤$39 K with 14.4 ± 2.9 years of education. Psychometric testing produced a 6-item version (GHNT-6). The GHNT-21 and GHNT-6 had acceptable-good internal consistency reliability (KR-20 = 0.87 vs. 0.77, respectively). Both versions were positively associated with income, education, health literacy, objective numeracy, and subjective numeracy (all p < .001). Furthermore, both versions were associated with participants’ understanding of their medications and medication adherence in unadjusted analyses, but only the GHNT-21 was associated with medication understanding in adjusted analyses.

Conclusions

The GHNT-21 and GHNT-6 are reliable and valid tools for assessing health numeracy.

Practice implications

Brief, reliable, and valid assessments of health numeracy can assess a patient's numeracy status, and may ultimately help providers and educators tailor education to patients.     

Activation of defense response in common bean against stem rot disease triggered by Trichoderma erinaceum and Trichoderma viride

White mold and stem rot is a common disease of Phaseolus vulgaris caused by Sclerotinia sclerotiorum. Biological control is a promising alternative for the control of this disease. In the present study, two Trichoderma spp., T. erinaceum and T. viride, and the consortium of both were evaluated as biocontrol agents against sclerotinia stem rot disease. The results revealed that T. erinaceum (NAIMCC-F-02171) and T. viride (NAIMCC-F-02500) when applied alone, significantly suppressed the infection rate of S. sclerotiorum and increased the rate of survival of plants by 74.5%. On the contrary, the combination of both the Trichoderma spp. was found to be more effective in reducing stem rot by 57.2% and increasing the survival of plants by 87.5% when compared to the individual Trichoderma applications. Further, the exogenous supplementation of Trichoderma activated antioxidative machineries, such as peroxidase, polyphenol oxidase, superoxide dismutase, catalase, and ascorbic acid in the plant. Besides, hydrogen peroxide and superoxide-free radical accumulation were also found to be reduced when T. erinaceum and T. viride were used either individually or in combination under the pathogen-challenged condition. Additionally, the photopigments in the bioprimed plants were markedly increased. Moreover, the combined inoculation of the two isolates yielded the highest records of growth parameters (root weight, shoot length, and leaf weight) compared with individual inoculation. Therefore, based on the above results, it was concluded that the combination of T. erinaceum and T. viride can be effectively used as an alternative to control white mold and stem rot caused by S. sclerotiorum.     

Quantum dot-sensitized O-linked heptazine polymer photocatalyst for the metal-free visible light hydrogen generation

Metal-free organic polymer photocatalysts have attracted dramatic attention in the field of visible light-induced hydrogen evolution reaction (HER). Herein, we showed a polymeric O-linked heptazine polymer (OLHP) decorated with S, N co-doped graphene quantum dots (S,N-GQDs) as a photosensitizer to generate hydrogen upon quantum dot sensitization. Both of these heptazine-based systems show effective photosensitization with strong π–π interactions and enhanced photocatalytic H₂ generation (24 times) as metal-free systems. Electrochemical impedance and optical measurements show effective charge transfer kinetics with decreased charge recombination, which is responsible for the enhanced photocatalytic activity. As a result, a significant high apparent quantum yield (AQY) with highest value of 10.2% was obtained for our photocatalyst OLHP/S,N-GQD10.

A polymeric O-linked heptazine polymer (OLHP) decorated with S, N co-doped graphene quantum dots (S,N-GQDs) as a photosensitizer to utilize visible light (λ > 420 nm) for hydrogen generation.