Investigation of structural, electronic, mechanical, & optical characteristics of Ra based-cubic hydrides RbRaX3 (X= F and cl) perovskite materials for solar cell applications: First principle study

Perovskite materials are considered the gateway of various physical applications to meet the production and consumption of energy and medical fields. Density Functional Theory (DFT) becomes the most important field in the modern era to investigate perovskite materials for various physical properties. DFT nowadays is used to explore the perovskite materials for a lot of applications like photocatalytic, optoelectronic, and photovoltaics. We discussed radium based cubic hydrides RbRaX3 (while X = F & Cl) perovskite material's electrical, optical, elastic, & physical characteristics with the help of DFT-based CASTEP code with PBE exchange-correlation efficient of GGA. The RbRaF3 & RbRaCl3 have three-dimensional nature by means of space group 221 (Pm3 m). According to electronic characteristics, the direct bandgap of RbRaF3 RbRaCl3 are 3.18eV and 2.209eV, respectively. Both compounds are brittle in nature via Poisson's ratio & Pugh's criteria. Thus, our novel RbRaX3 (X = F and Cl) compounds have excellent applications for solar cell and medical areas.

Lithium-based perovskites materials for photovoltaic solar cell and protective rays window applications: a first-principle calculations

Perovskites are the key enabler materials for the solar cell applications in the achievement of high performance and low production costs. In this article, the structural, mechanical, electronic, and optical properties of rubidium-based cubic nature perovskite LiHfO₃ and LiZnO₃ are investigated. These properties are investigated using density-functional theory with the aid of CASTEP software by introducing ultrasoft pseudo-potential plane-wave (USPPPW) and GG-approximation-PB-Ernzerhof exchange-correlation functionals. It is investigated that the proposed compounds exhibit stable cubic phase and meet the criteria of mechanical stability by the estimated elastic properties. Also, according to Pugh's criterion, it is noted that LiHfO₃ is ductile and LiZnO₃ is brittle. Furthermore, the electronic band structure investigation of LiHfO₃ and LiZnO₃ shows that they have indirect bandgap (BG). Moreover, the BG analysis of the proposed materials shows that these are easily accessible. Also, the results for partial density of states (DOS) and total DOS confirm the degree of a localized electron in the distinct band. In addition, the optical transitions in the compounds are examined by fitting the damping ratio for the notional dielectric functions scaling to the appropriate peaks. At absolute zero temperature, the materials are observed as semiconductors. Therefore, it is evident from the analysis that the proposed compounds are excellent candidates for solar cells and protective rays applications.

First-principles calculations to investigate structural, electronic, elastic and optical properties of radium based cubic fluoro-perovskite materials

Perovskite materials play a vital role in the field of material science via experimental as well as theoretical calculations. Radium semiconductor materials are considered the backbone of medical fields. These materials are considered in high technological fields to be used as controlling the decay ability. In this study, radium-based cubic fluoro-perovskite XRaF₃ (where X = Rb and Na) are calculated using a DFT (density functional theory). These compounds are cubic nature with 221 space groups that construct on CASTEP (Cambridge-serial-total-energy-package) software with ultra-soft PPPW (pseudo-potential plane-wave) and GGA (Generalized-Gradient-approximation)-PBE (Perdew-Burke-Ernzerhof) exchange-correlation functional. The structural, optical, electronic, and mechanical properties of the compounds are calculated. According to the structural properties, NaRaF₃ and RbRaF₃ have a direct bandgap with 3.10eV and 4.187eV of NaRaF₃ and RbRaF₃, respectively. Total density of states (DOS) and partial density of states (PDOS) provide confirmation to the degree of electrons localized in distinct bands. NaRaF₃ material is semiconductors and RbRaF₃ is insulator, according to electronic results. The imaginary element dispersion of the dielectric function reveals its wide variety of energy transparency. In both compounds, the optical transitions are examined by fitting the damping ratio for the notional dielectric function scaling to the appropriate peaks. The absorption and the conductivity of NaRaF₃ compound is better than the RbRaF₃ compound which make it suitable for the solar cell applications increasing the efficiency and work function. We observed that both compounds are mechanically stable with cubic structure. The criteria for the mechanical stability of compounds are also met by the estimated elastic results. These compounds have potential application in field of solar cell and medical.

Objectives

The band gap, absorption and the conductivity are necessary conditions for potential applications. Here, literature was reviewed to check computational translational insight into the relationships between absorption and conductivity for solar cell and medical applications of novel RbRaF₃ and NaRaF₃ compounds.

Multiphonon Process in Mn-Doped ZnO Nanowires

The multiphonon process plays an essential role in understanding electron-phonon coupling, which significantly influences the optical and transport properties of solids. Multiphonon processes have been observed in many materials, but how to distinguish them directly by their spectral characteristics remains controversial. Here, we report high-order Raman scattering up to 10 orders and hot luminescence involving 11 orders of phonons in Mn-doped ZnO nanowires by selecting the excitation energy. Our results show that the intensity distribution of high-order Raman scattering obeys an exponential decrease as the order number increases, while hot luminescence is fitted with a Poisson distribution with a resonance factor. Their linewidth and frequency can be well explained by two different transition models. Our work provides a paradigm for understanding the multiphonon-involved decay process of an excited state and may inspire studies of the statistical characteristics of excited state decay.

Zirconium-based cubic-perovskite materials for photocatalytic solar cell applications: a DFT study

The structural, electronic, optical, and mechanical characteristics of cubic inorganic perovskites XZrO3 (X = Rb and K) were studied using the Cambridge serial total energy package-based DFT.

Characterization and adsorption capacity of modified 3D porous aerogel from grapefruit peels for removal of oils and organic solvents

With the rapid industrialization, especially offshore oil exploitation, frequent leakage incidents of oils/organic solvents have adversely affected ecological systems and environmental resources. Therefore, great interest has been shown in developing new materials to eliminate these organic pollutants, which have become worldwide problems. In this study, a cost-effective, environmentally friendly porous aerogel with three-dimensional (3D) structure was prepared from grapefruit peel by a facile hydrothermal method as the adsorbent of oils/organic solvents. The as-prepared modified grapefruit peel aerogel (M-GPA) showed mesoporous structure with high specific surface area of 36.42 m²/g and large pore volume of 0.0371 cm³/g. The excellent hydrophobicity of M-GPA with a water contact angle of 141.2° indicated a strong potential for adsorption of oils and organic solvents. The high adsorption capacity of M-GPA for a series of oils and organic solvents was 8 to 52 times as much as its own weight. Moreover, the M-GPA was easily regenerated and a high adsorption capacity recovery above 97% was maintained after five adsorption-regeneration cycles. Therefore, the M-GPA is a promising recyclable adsorbent for the removal of oils/organic solvents from polluted water.

Surface Modification of Magnetic Iron Oxide Nanoparticles

Functionalized iron oxide nanoparticles (IONPs) are of great interest due to wide range applications, especially in nanomedicine. However, they face challenges preventing their further applications such as rapid agglomeration, oxidation, etc. Appropriate surface modification of IONPs can conquer these barriers with improved physicochemical properties. This review summarizes recent advances in the surface modification of IONPs with small organic molecules, polymers and inorganic materials. The preparation methods, mechanisms and applications of surface-modified IONPs with different materials are discussed. Finally, the technical barriers of IONPs and their limitations in practical applications are pointed out, and the development trends and prospects are discussed.

Spin-induced magnetic anisotropy in novel Co-doped GaN nanoneedles and their related photoluminescence

We demonstrate the formation and excitation of exciton magnetic polarons (EMPs) and bound magnetic polarons (BMPs) in novel Co-doped GaN.

Mammographic breast density: Predictive value for pathological response to neoadjuvant chemotherapy in breast cancer patients

BACKGROUND

This study aims to evaluate the relation between mammographic breast density (BD) and pathological response to neoadjuvant chemotherapy.

METHODS

In this retrospective study, 241 breast cancer patients who received neoadjuvant chemotherapy were included. BD was assessed in mammograms already performed at diagnosis. Pathological complete response (pCR) and pathological stage were correlated with BD, tumour phenotype and other clinico-pathological factors.

RESULTS

Patients with low BD had better pCR compared to those with high density (30.5% vs 19.5% respectively, OR = 1.8, 95% CI = 0.98-3.3, p = 0.056) which was more pronounced after adjustment with body mass index (BMI) (OR = 2.4, 95% CI = 1.2-4.8, p = 0.011). HER2-positive disease (32.5% vs. 18.4%, OR = 2.2, 95% = 1.2-4.0, p = 0.01), lower BMI (OR = 1.1, 95% CI = 1.03-1.15, p = 0.004) and lower clinical stage (p = 0.002) were significant predictors of pCR in univariate analysis. In multivariate analysis, low BD (OR = 2.7, 95% CI = 1.3-5.5, p = 0.006) and lower BMI (OR = 1.1, 95% CI = 1.03-1.17, p = 0.003) were independent predictors of better pCR, while early clinical stage (I, II) was of borderline significance (OR = 2.6, 95% CI = 0.99-6.7, p = 0.052). High BD (OR = 1.8, 95% CI = 1.1-3.2, p = 0.03), advanced clinical stage (III) (OR = 1.5, 95% CI = 1.03-2.1, p = 0.03) and higher BMI (OR = 1.06, 95% CI = 1.02-1.11, p = 0.006) were significant predictors of advanced pathological stage.

CONCLUSION

Low mammographic BD, low BMI and early clinical stage were associated with improved pCR rate and lower pathological stage after neoadjuvant chemotherapy. BD had more pronounced association with response to chemotherapy after adjustment with BMI.

Efficacy of combined metformin-clomiphene citrate in comparison with clomiphene citrate alone in infertile women with polycystic ovarian syndrome (PCOS)

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy in women and is associated with the reproductive and metabolic disorders.

OBJECTIVES

To compare the ovulation and conception rates after the treatment with Clomiphene Citrate (CC) alone and in combination with metformin in infertile patients presented with polycystic ovarian syndrome (PCOS).

MATERIAL & METHODS

This randomized controlled trial of independent cases and controls was conducted in the Department of Obstetrics and Gynecology, Hera General Hospital, Makkah, Saudi Arabia, during 2008. The 42 subjects diagnosed as PCOS were divided into group A and B (21 subjects in each) for the management with CC + metformin and CC alone, respectively. Group A received 500mg of metformin continuously, three times a day from the first cycle, for 6 months or until the pregnancy was confirmed. In both groups, CC was started with a dose of 50 mg from day-2 until day-6 of the menstrual cycle. The dose of CC was increased to 100 mg in the second and 150 mg in the third cycle, and then 150 mg remained for the rest of three cycles. With ovulation, the dose of CC was unaltered in both groups. Data were analyzed by using SPSS version 16.

RESULTS

More than 50% of the females in both groups had a body mass index of >25. Group A achieved a higher rate of regular cycles, ovulation success, and conception than group B (71.4% vs. 38.1%; p=0.03), (76.2% vs. 38.1%; p=0.021) and (66.6% vs. 28.6%, p=0.01), respectively.

CONCLUSION

Management with metformin + CC increased the ovulation and conception rates.

Prevalence of intestinal parasites and bacteria among food handlers in a tertiary care hospital

Objectives:

The aim of this work is to determine the prevalence of intestinal parasites and bacteria among the food handlers.

Materials and Methods:

Two hundred food-handlers were subjected to a cross-sectional study working in the kitchen of a tertiary care hospital, i.e., Alnoor Specialist Hospital, Makkah, Saudi Arabia from February 2 to 27, 2009. The stool samples were examined for intestinal parasites following direct microscopic examination, formol ether concentration (Ritchie), and staining with modified acid fast staining techniques. For enteropathogenic bacteria samples were inoculated onto MacConkey's agar, deoxycholate citrate agar, xylose lysine deoxycholate agar as per the World Health Organization protocol. Fingernail materials were examined microscopically for enteropathogenic bacteria and parasites.

Results:

The majority (80%) of the food-handlers were young adults aged from 22 to 42 years. No intestinal parasites were detected from fingernail contents. Forty six (23%) stool specimens were positive for intestinal para¬sites. Giardia lamblia 18 (9%) was most frequent among the 10 different types of detected intestinal parasites followed by Entamoeba histolytica 9 (4.5%). No pathogenic bacteria were detected in all stool samples, whereas finger nails showed isolation of microorganisms as coagulase-negative staphylococci 79 (39.5%), followed by Staphylococcus aureus 35 (17.5%).

Conclusion:

The findings emphasized the importance of food handlers as potential sources of infections and suggested health institutions for appropriate hygienic and sanitary control measures.

The epidemiology of stroke in Pakistan: past, present, and future

Stroke is a major public health problem in developing countries of South Asia. In this paper, we review the epidemiology of stroke in Pakistan. Most of the available data are based on hospital-centred case series addressing established stroke risk factors, stroke-related mortality and disability, functional status, and case fatality rates. There are limited population-based data regarding the prevalence of established stroke risk factors in the general population, and no epidemiologic studies have been conducted to specifically identify potential stroke risk factors unique to the region. The limited data that are available from Pakistan indicate that stroke epidemiology differs between Pakistan and Western populations - in Pakistan first stroke occurs at a younger age, particularly among women, and there is a higher proportion of haemorrhagic strokes. Besides the established stroke risk factors (e.g. hypertension, smoking, and diabetes) some potentially unique stroke risk factors related to life style and dietary habits such as huqqa smoking, use of dalda and desi ghee, and orally consumed forms of tobacco, may exist in Pakistan, and warrant further investigation. The shortage of trained stroke epidemiologists is a major limiting factor to the conduct of epidemiological stroke studies in Pakistan. Epidemiologic data are essential to guide health policy development aimed at decreasing the mortality and morbidity from stroke in Pakistan. To facilitate this process, medical professionals in Pakistan could participate in the World Health Organization's STEPwise approach to stroke surveillance, which provides a framework for data collection and comparison between and within populations.

EBSD characterization of carbide-carbide boundaries in WC-Co composites

A sample of WC-6wt%Co was investigated for grain boundary character distribution and occurrence of coincidence site lattice (CSL) boundaries on a statistical basis. For this purpose orientation measurements of the grains were carried out using electron back-scattered diffraction (EBSD). The dominant misorientation relationships were determined by complementary EBSD data representation tools such as orientation maps, misorientation angle distribution histograms and the sectioned three-dimensional misorientation space. It was found that the grain boundary character distribution of the material is nearly random and the CSL boundaries are not present in statistically significant amounts. It was also found that the amount of binder phase does not play a role in the formation of special boundaries. The paper focuses on the methodology of characterizing grain boundaries in a hexagonal material using EBSD.