FABRICATION AND CHARACTERIZATION OF ACTIVE NANOSTRUCTURES

Three different nanostructure active devices have been designed, fabricated and characterized. Junctionless transistors based on highly-doped silicon nanowires fabricated using a bottom-up fabrication approach are first discussed. The fabrication avoids the ion implantation step since silicon nanowires are doped in-situ during growth. Germanium junctionless transistors fabricated with a top down approach starting from a germanium on insulator substrate and using a gate stack of high-k dielectrics and GeO2 are also presented. The levels and origin of low-frequency noise in junctionless transistor devices fabricated from silicon nanowires and also from GeOI devices are reported. Low-frequency noise is an indicator of the quality of the material, hence its characterization can reveal the quality and perhaps reliability of fabricated transistors. A novel method based on low-frequency noise measurement to envisage trap density in the semiconductor bandgap near the semiconductor/oxide interface of nanoscale silicon junctionless transistors (JLTs) is presented. Low-frequency noise characterization of JLTs biased in saturation is conducted at different gate biases. The noise spectrum indicates either a Lorentzian or 1/f. A simple analysis of the low-frequency noise data leads to the density of traps and their energy within the semiconductor bandgap. The level of noise in silicon JLT devices is lower than reported values on transistors fabricated using a top-down approach. This noise level can be significantly improved by improving the quality of dielectric and the channel interface

Adaptation of the client diagnostic questionnaire for East Africa

Research increasingly involves cross-cultural work with non-English-speaking populations, necessitating translation and cultural validation of research tools. This paper describes the process of translating and criterion validation of the Client Diagnostic Questionnaire (CDQ) for use in a multisite study in Kenya and Uganda. The English CDQ was translated into Swahili, Dholuo (Kenya) and Runyankole/Rukiga (Uganda) by expert translators. The translated documents underwent face validation by a bilingual committee, who resolved unclear statements, agreed on final translations and reviewed back translations to English. A diagnostic interview by a mental health specialist was used for criterion validation, and Kappa statistics assessed the strength of agreement between non-specialist scores and mental health professionals’ diagnoses. Achieving semantic equivalence between translations was a challenge. Validation analysis was done with 30 participants at each site (median age 32.3 years (IQR = (26.5, 36.3)); 58 (64.4%) female). The sensitivity was 86.7%, specificity 64.4%, positive predictive value 70.9% and negative predictive value 82.9%. Diagnostic accuracy by the non-specialist was 75.6%. Agreement was substantial for major depressive episode and positive alcohol (past 6 months) and alcohol abuse (past 30 days). Agreement was moderate for other depressive disorders, panic disorder and psychosis screen; fair for generalized anxiety, drug abuse (past 6 months) and Post Traumatic Stress Disorder (PTSD); and poor for drug abuse (past 30 days). Variability of agreement between sites was seen for drug use (past 6 months) and PTSD. Our study successfully adapted the CDQ for use among people living with HIV in East Africa. We established that trained non-specialists can use the CDQ to screen for common mental health and substance use disorders with reasonable accuracy. Its use has the potential to increase case identification, improve linkage to mental healthcare, and improve outcomes. We recommend further studies to establish the psychometric properties of the translated tool

Understanding factors influencing home pregnancy test use among women in western Kenya: A qualitative analysis

BackgroundThere are limited data on home pregnancy test use among women in low-and-middle-income countries. A prior survey found that only 20% of women in western Kenya used a home pregnancy test to confirm their pregnancies before going to antenatal care. This qualitative study aims to understand why women do not use home pregnancy tests in early pregnancy.MethodsFrom April 2021 to July 2021, we interviewed women from four antenatal care clinics in Homa Bay and Siaya counties. We recruited women previously enrolled in the PrEP Implementation for Mothers in Antenatal care (PrIMA) study, a cluster-randomized trial that evaluated the best approaches to implementing PrEP in maternal and child health clinics in Western Kenya (NCT03070600). Interviews were conducted via phone, audio recorded, translated, and transcribed verbatim. We coded and analyzed the transcripts to capture factors influencing women's capability, opportunity, and motivation to use home pregnancy tests.ResultsWe conducted 48 semistructured interviews with women aged 21–42 years. Twenty-seven women did not use a home pregnancy test in their most recent pregnancy. Seventeen of these women reported not using a home pregnancy test before. Lack of knowledge, mistrust in the accuracy of tests, preferring to rely on signs and symptoms of pregnancy or get a test from the health facility, cost, and accessibility were key barriers to home pregnancy test use.ConclusionImproving the uptake of home pregnancy testing during early pregnancy will require efforts to enhance community knowledge of test use and associated benefits and reduce cost burdens by making tests more affordable and accessible

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Multiphoton Absorption Coefficients of Organic-Inorganic Lead Halide Perovskites CH3NH3PbX3 (X = Cl, Br, I) Single Crystals

Hybrid organic inorganic lead halide perovskites have recorded unprecedented improvement in efficiency as fourth-generation photovoltaic materials. Recently, they have attracted enormous interest in nonlinear optics stemming basically from their excellent optoelectronic properties. Here, we investigate multiphoton absorption (MPA) in high-quality MAPbX(3) (MA = CH3NH3 and X = Cl, Br, I) bulk single crystals synthesized by an inverse temperature crystallization (ITC) method. The two-photon absorption (2PA) coefficients under picosecond pulse excitation are determined to be beta = 23 +/- 2 cm/GW and 9 +/- 1 cm/GW for MAPbI(3) and MAPbBr(3) at lambda = 1064 nm, and 13 +/- 2 cm/GW for MAPbCl(3) at lambda = 532 nm. The 2PA coefficients are comparable to those of conventional semiconductors having similar bandgaps and can be explained by a two-band model. Furthermore, we characterize the three-photon absorption behavior of MAPbCl(3) at lambda = 1064 nm, yielding gamma = 0.05 +/- 0.01 cm(3)/GW(2). The polarization dependence of MPA is also probed to experimentally estimate the degree of anisotropy. The hybrid perovskites are promising materials for nonlinear optical applications due to polarization dependent MPA response and subsequent strong photoluminescence emission, especially for the Br- and I-containing compounds. © 2017 American Chemical Society1231sciescopu

Phase transitions of formamidinium lead iodide perovskite under pressure

The pressure-induced structural evolution of formamidinium-based perovskite FAPbI3 was investigated using in situ synchrotron X-ray diffraction and laser-excited photoluminescence methods. Cubic α-FAPbI3 ( Pm3̅ m) partially and irreversibly transformed to hexagonal δ-FAPbI3 ( P63 mc) at a pressure less than 0.1 GPa. Structural transitions of α-FAPbI3 followed the sequence of Pm3̅ m → P4/ mbm → Im3̅ → partial amorphous during compression to 6.59 GPa, whereas the δ-phase converted to an orthorhombic Cmc21 structure between 1.26 and 1.73 GPa. During decompression, FAPbI3 recovered the P63 mc structure of the δ-phase as a minor component (∼18 wt %) from 2.41-1.40 GPa and the Pm3̅ m structure of the α-phase becomes dominant (∼82 wt %) at 0.10 GPa but with an increased fraction of δ-FAPbI3. The photoluminescence behaviors from both the α- and δ-forms were likely controlled by radiative recombination at the defect levels rather than band-edge emission during pressure cycling. FAPbI3 polymorphism is exquisitely sensitive to pressure. While modest pressures can engineer FAPbI3-based photovoltaic devices, irreversible δ-phase crystallization may be a limiting factor and should be taken into account

Multiphoton Absorption Coefficients of Organic–Inorganic Lead Halide Perovskites CH₃NH₃PbX₃ (X = Cl, Br, I) Single Crystals

Hybrid organic–inorganic lead halide perovskites have recorded unprecedented improvement in efficiency as fourth-generation photovoltaic materials. Recently, they have attracted enormous interest in nonlinear optics stemming basically from their excellent optoelectronic properties. Here, we investigate multiphoton absorption (MPA) in high-quality MAPbX₃ (MA = CH₃NH₃ and X = Cl, Br, I) bulk single crystals synthesized by an inverse-temperature crystallization (ITC) method. The two-photon absorption (2PA) coefficients under picosecond pulse excitation are determined to be β = 23 ± 2 cm/GW and 9 ± 1 cm/GW for MAPbI₃ and MAPbBr₃ at λ = 1064 nm, and 13 ± 2 cm/GW for MAPbCl₃ at λ = 532 nm. The 2PA coefficients are comparable to those of conventional semiconductors having similar bandgaps and can be explained by a two-band model. Furthermore, we characterize the three-photon absorption behavior of MAPbCl₃ at λ = 1064 nm, yielding γ = 0.05 ± 0.01 cm³/GW². The polarization dependence of MPA is also probed to experimentally estimate the degree of anisotropy. The hybrid perovskites are promising materials for nonlinear optical applications due to polarization-dependent MPA response and subsequent strong photoluminescence emission, especially for the Br- and I-containing compounds

Traditional Uses, Phytochemistry, and Pharmacological Properties of the Genus <i>Blechnum</i>—A Narrative Review

Blechnum L. is a genus belonging to the Blechnaceae family with 236 accepted species that grow in intertropical, subtropical, and southern temperate regions. Several species of the genus have long been used in folk medicines to treat a broad spectrum of ailments, including typhoid, urinary infections, influenza, wounds, pulmonary complaints, blisters, boils, and antihelmintic-related complications. So far, about 91 chemical compounds have been isolated from different parts of 20 Blechnum species. Among these metabolites, phenolic compounds, sterols, and fatty acids are the main constituents. Modern pharmacological investigations revealed several isolated compounds and extracts to exhibit exceptional biological properties including the antioxidant, antimicrobial, anti-inflammatory, anticancer, insecticidal, antitrematocidal and wound healing. In various tests, both quercetin-7′,3′,4′-trimethoxy and phytol metabolites showed potential antioxidant and antitrematocidal properties, while ponasterone exhibited insecticidal activity. Despite having a broad range of traditional medicinal benefits and biological properties, understanding the scientific connotations based on the available data is still challenging. This article presents a comprehensive review of the traditional uses, phytochemical compounds, and pharmacological aspects of the Blechnum species