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The effect of tuning the depolarization field in (001)-oriented ultrathin epitaxial PbZr0.4Ti0.6O3/SrTiO3/PbZr0.4Ti0.6O3 ferroelectric heterostructures is investigated. The thickness of the dielectric spacer (SrTiO3) is maintained constant at 2 unit cells. The ferroelectric layer thickness in the heterostructure (each PbZr0.4Ti0.6O3) layer varied from 8 to 15 nm is exploited as the parameter to tune the depolarization field. Piezoresponse force microscopy reveals a domain evolution from continuous labyrinthine domains to individual nanoscale bubble domains under the influence of an increasing depolarization field. A statistical analysis of the domain features (i.e., domain wall length and domain fraction) reveals that this change in domain morphology also affects the wall roughness and its associated disorder. The local coercive voltage obtained using switching spectroscopy piezoresponse force microscopy finds the 15 nm film to have the lowest coercive voltage. This is attributed to both a strain-induced increase in tetragonality and the depolarization field-induced changes in the domain morphology. [ABSTRACT FROM AUTHOR]

BiFeO3 thin films have attracted considerable attention by virtue of their potential application in low-energy spintronic and magnonic devices. BiFeO3 possesses an intricate magnetic structure, characterized by a spin cycloid with period ∼62 nm that governs the functional magnonic response, and which can be modulated or even destroyed by strain, magnetic and electric fields, or chemical doping. The literature on (110)-oriented BiFeO3 films is not explicit in defining the conditions under which this cycloid persists, as its presence depends on synthesis method and thin-film boundary conditions, especially in the sub-100 nm thickness regime. This report aims to end "trial and error" approaches in determining the conditions under which this cycloid and its associated functional magnonic response exist. We show that in specific crystallographic orientations of epitaxial BiFeO3, an unexplored strain parameter—the distortion in the ab plane of the monoclinic unit cell—significantly influences the spin structure. Combining Mössbauer spectroscopy and low-energy Raman spectroscopy with first-principles-based effective Hamiltonian calculations, we show that both average strain and this distortion destroy the cycloid. For films grown on (110)-oriented SrTiO3 substrates, if the BiFeO3 lattice parameters a and b differ by more than about 1.2%, the cycloid is destabilized, resulting in a pseudocollinear magnetic order ground state. We are thereby able to construct a phase diagram of the spin structure for nanoscale epitaxial BiFeO3 films, which aims to resolve long-standing literature inconsistencies and provide powerful guidelines for the design of future magnonic and spintronic devices. [ABSTRACT FROM AUTHOR]

Ferroelectrics are non-centrosymmetric crystalline materials that possess a spontaneous polarization that can be switched by an electric field. The electric-field-dependent optical response of these materials makes them important for optical devices, such as modulators or beam deflectors. In the inexorable drive to miniaturization, the concept of integrated thin film optical devices has led to the incorporation of ferroelectric thin films on single-crystal substrates. These structures have appealing electro-optic modulation characteristics, interesting strain-dependent bandgaps and refractive index, as well as promising possibilities for solar harvesting. Here, we review the work on epitaxial ferroelectric (FE) films for optical applications. We first show that FE thin film materials are attractive for integrated electro-optic modulators and then show that epitaxial strain can be used to enhance the FE and optical functionality of films. Next, we describe some of the photovoltaic functionality of FE thin film materials' systems and conclude the review by highlighting some thin-film devices that exploit the aforementioned optical effects. [ABSTRACT FROM AUTHOR]

We investigate photo-induced ferroelectric domain switching in a series of Pb(Zr0.2Ti0.8)O3/ La0.7Sr0.3MnO3 (PZT/LSMO) bilayer thin films with varying surface morphologies by piezoresponse force microscopy under light illumination. We demonstrate that reverse poled ferroelectric regions can be almost fully recovered under laser irradiation of the PZT layer and that the recovery process is dependent on the surface morphology on the nanometer scale. The recovery process is well described by the Kolmogorov-Avrami-Ishibashi model, and the evolution speed is controlled by light intensity, sample thickness, and initial write voltage. Our findings shed light on optical control of the domain structure in ferroelectric thin films with different surface morphologies. [ABSTRACT FROM AUTHOR]

We have studied the magnetic order of highly strained (001)-oriented BiFeO3 (BFO) thin films using 57Fe Conversion Electron Móssbauer Spectrometry. From 90K to 620K the films exhibit a collinear antiferromagnetic structure, in contrast with the cycloidal structure observed in bulk BFO. Moreover, we find that both the planar magnetic anisotropy for compressive strain and out-of-plane anisotropy for tensile strain persist from 90K up to the Néel temperature (TN), which itself shows only a weak strain dependence. An analysis of the line asymmetry of the paramagnetic doublet for temperatures above TN is used to reveal the strain-dependent rotation of the polarization direction, consistent with previous observations. Our results show that the lattice dynamics in BFO films are strongly strain-dependent, offering avenues toward acoustic phonon devices. Finally, we use the versatility of Móssbauer spectroscopy technique to reveal various multi-property features including magnetic states, polarization direction and elastic strain. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO3) is one of the very few known single-phase multiferroic materials. While the bulk compound is rhombohedral (R), the discovery of an epitaxial strain-induced structural transition into a so-called "super tetragonal phase" (T-phase) in this material incited a flurry of research activity focused on gaining an understanding of this phase transition and its possible functionalities. This metastable phase of BiFeO3 is also multiferroic, with giant ferroelectric polarization and coexisting antiferromagnetic order, but above all it is the strain relaxation-induced phase mixtures and their outstanding piezoelectric and magnetoelectric responses which continue to intrigue and motivate the physicist and materials scientist communities. Here, we review the research into the T-phase and mixed-phase BiFeO3 system. We begin with a brief summary of the history of the T-phase and an analysis of the structure of the various phases reported in the literature. We then address important questions regarding the symmetry and octahedral rotation patterns and the (as yet underexplored) important role of chemistry in the formation of the metastable T-phase. We follow by describing the phase transitions in this material, and how these may hold promise for large magnetoelectric responses. Finally, we point out some experimental challenges inherent to the study of such a system, and potential pathways for how they may be overcome. It is our intention with this work to highlight important issues that, in our opinion, should be carefully considered by the community in order to use this fascinating materials system for a new paradigm of functionality. [ABSTRACT FROM AUTHOR]

Bismuth ferrite (BiFeO3) is one of the very few known single-phase multiferroic materials. While the bulk compound is rhombohedral (R), the discovery of an epitaxial strain-induced structural transition into a so-called "super tetragonal phase" (T-phase) in this material incited a flurry of research activity focused on gaining an understanding of this phase transition and its possible functionalities. This metastable phase of BiFeO3 is also multiferroic, with giant ferroelectric polarization and coexisting antiferromagnetic order, but above all it is the strain relaxation-induced phase mixtures and their outstanding piezoelectric and magnetoelectric responses which continue to intrigue and motivate the physicist and materials scientist communities. Here, we review the research into the T-phase and mixed-phase BiFeO3 system. We begin with a brief summary of the history of the T-phase and an analysis of the structure of the various phases reported in the literature. We then address important questions regarding the symmetry and octahedral rotation patterns and the (as yet underexplored) important role of chemistry in the formation of the metastable T-phase. We follow by describing the phase transitions in this material, and how these may hold promise for large magnetoelectric responses. Finally, we point out some experimental challenges inherent to the study of such a system, and potential pathways for how they may be overcome. It is our intention with this work to highlight important issues that, in our opinion, should be carefully considered by the community in order to use this fascinating materials system for a new paradigm of functionality. [ABSTRACT FROM AUTHOR]

We report on the optimization process to synthesize epitaxial thin films of GdTiO3 on SrLaGaO4 substrates by pulsed laser deposition. Optimized films are free of impurity phases and are fully strained. They possess a magnetic Curie temperature TC = 31.8 K with a saturation magnetization of 4.2 μB per formula unit at 10 K. Transport measurements reveal an insulating response, as expected. Optical spectroscopy indicates a band gap of ~0.7 eV, comparable to the bulk value. Our work adds ferrimagnetic orthotitanates to the palette of perovskite materials for the design of emergent strongly correlated states at oxide interfaces using a versatile growth technique such as pulsed laser deposition. [ABSTRACT FROM AUTHOR]

Multiferroics are materials with coexisting magnetic and ferroelectric orders, which show potential for electrically controlled spintronic devices. A common application of ferroelectrics is in electro-optical modulators exploiting their electric-field-dependent optical indices. The coupling of optical and magnetic degrees of freedom is attractive for designing multifunctional devices, but to date the electro-optical response of multiferroics has hardly been explored. Here we report a joint experimental and theoretical study of this effect in multiferroic BiFeO3 thin films. We confirm the large birefringence present in single crystals and determine the electro-optic coefficients r13 and r33. We present approaches to increase the obtained coefficients, for instance, by using tetragonal-like BiFeO3, and expand the potential of multiferroics to optical applications. [ABSTRACT FROM AUTHOR]

Multiferroics are compounds that show ferroelectricity and magnetism. BiFeO3, by far the most studied, has outstanding ferroelectric properties, a cycloidal magnetic order in the bulk, and many unexpected virtues such as conductive domain walls or a low bandgap of interest for photovoltaics. Although this flurry of properties makes BiFeO3 a paradigmatic multifunctional material, most are related to its ferroelectric character, and its other ferroic property-antiferromagnetism-has not been investigated extensively, especially in thin films. Here we bring insight into the rich spin physics of BiFeO3 in a detailed study of the static and dynamic magnetic response of strain-engineered films. Using Mössbauer and Raman spectroscopies combined with Landau-Ginzburg theory and effective Hamiltonian calculations, we show that the bulk-like cycloidal spin modulation that exists at low compressive strain is driven towards pseudo-collinear antiferromagnetism at high strain, both tensile and compressive. For moderate tensile strain we also predict and observe indications of a new cycloid. Accordingly, we find that the magnonic response is entirely modified, with low-energy magnon modes being suppressed as strain increases. Finally, we reveal that strain progressively drives the average spin angle from in-plane to out-of-plane, a property we use to tune the exchange bias and giant-magnetoresistive response of spin valves. [ABSTRACT FROM AUTHOR]

The Tanzania HIV Care and Treatment Plan was launched in October 2004 aiming at providing 440,000 AIDS patients with antiretroviral drugs (ARVs) and track disease progression in 1.2 million HIV+ persons by the end of the 2008. This paper is intended to provide information to stake holders of the achievements and challenges of the HIV Care and Treatment Plan since its inception in 2004. Facility patient reports are aggregated at district and then regional level before being sent to the national level where they are aggregated to form a national report. By December 2007, 210 health facilities were offering HIV care and treatment services in Tanzania. About 123,147 (5 %) of the 2,636,785 estimated people living with HIV and AIDS were enrolled, and 71,439 (13.6 %) of the estimated 527,357 AIDS cases commenced ART. More females than males started ART, F: M ratio being 3: 2. Most (49 %) patients were started ART due to low CD4 counts (<200). About 6,618 patients had their initial ARV regimen changed due to starting anti-TB treatment 679 (10 %), peripheral neuropathy 812 (12%), skin rash 378 (6 %), and stock out 247 (4 %) or other reasons (18 %), while 2,653 (42 %) had no reason recorded. The proportion of patients still alive and on ART at 6, 12 and 24 months after initiation of treatment was 60 %, 60 % and 50 %, respectively, while those collecting ARVs on schedule was 34 %, 25 % and 10 % respectively. About 3,084 patients developed TB after starting ART, of whom 1,557 (~50%) patients during the first three months of treatment. During the three years (2004-2007) of HIV care and treatment services in Tanzania, there has been an increase in the number of CTC facilities, geographical coverage of services, the number of enrolled patients and those on ART. However, the set target for ART services has not been achieved and there are significant geographical variations in these achievements, which do not correspond with either population density or disease burden. Efforts should be made to i) ensure equitable accessibility when scaling up ART services in Tanzania, ii) improve the recording and reporting system and iii) harmonize the activities of various stakeholders. [ABSTRACT FROM AUTHOR]

The application of PhotoEmission Electron Microscopy (PEEM) and Low Energy Electron Microscopy (LEEM) techniques to the study of the electronic and chemical structures of ferroelectric materials is reviewed. Electron optics in both techniques gives spatial resolution of a few tens of nanometres. PEEM images photoelectrons, whereas LEEM images reflected and elastically backscattered electrons. Both PEEM and LEEM can be used in direct and reciprocal space imaging. Together, they provide access to surface charge, work function, topography, chemical mapping, surface crystallinity, and band structure. Examples of applications for the study of ferroelectric thin films and single crystals are presented. [ABSTRACT FROM AUTHOR]

We present a comprehensive study of the physical properties of epitaxial cobalt-doped BiFeO3 films ∼50 nm thick grown on (001) LaAlO3 substrates. X-ray diffraction and magnetic characterization demonstrate high quality purely tetragonal-like (T′) phase films with no parasitic impurities. Remarkably, the step-and-terrace film surface morphology can be fully recovered following a local electric-field-induced rhombohedral-like to T′ phase transformation. Local switching spectroscopy experiments confirm the ferroelectric switching to follow previously reported transition pathways. Critically, we show unequivocal evidence for conduction at domain walls between polarization variants in T′-like BFO, making this material system an attractive candidate for domain wall-based nanoelectronics. [ABSTRACT FROM AUTHOR]

Switching dynamics of ferroelectric materials are governed by the response of domain walls to applied electric field. In epitaxial ferroelectric films, thermally-activated 'creep' motion plays a significant role in domain wall dynamics, and accordingly, detailed understanding of the system's switching properties requires that this creep motion be taken into account. Despite this importance, few studies have investigated creep motion in ferroelectric films under ac-driven force. Here, we explore ac hysteretic dynamics in epitaxial BiFeO3 thin films, through ferroelectric hysteresis measurements, and stroboscopic piezoresponse force microscopy. We reveal that identically-fabricated BiFeO3 films on SrRuO3 or La0.67Sr0.33MnO3 bottom electrodes exhibit markedly different switching behaviour, with BiFeO3/SrRuO3 presenting essentially creep-free dynamics. This unprecedented result arises from the distinctive spatial inhomogeneities of the internal fields, these being influenced by the bottom electrode's surface morphology. Our findings further highlight the importance of controlling interface and defect characteristics, to engineer ferroelectric devices with optimised performance. [ABSTRACT FROM AUTHOR]

Recently, strain engineering has been shown to be a powerful and flexible means of tailoring the properties of ABO3 perovskite thin films. The effect of epitaxial strain on the structure of the perovskite unit cell can induce a host of interesting effects, these arising from either polar cation shifts or rotation of the oxygen octahedra, or both. In the multi-ferroic perovskite bismuth ferrite (BiFeO3-BFO), both degrees of freedom exist, and thus a complex behaviour may be expected as one plays with epitaxial strain. In this paper, we review our results on the role of strain on the ferroic transition temperatures and ferroic order parameters. We find that, while the Néel temperature is almost unchanged by strain, the ferroelectric Curie temperature strongly decreases as strain increases in both the tensile and compressive ranges. Also unexpected is the very weak influence of strain on the ferroelectric polarization value. Using effective Hamiltonian calculations, we show that these peculiar behaviours arise from the competition between antiferrodistortive and polar instabilities. Finally, we present results on the magnetic order: while the cycloidal spin modulation present in the bulk survives in weakly strained films, it is destroyed at large strain and replaced by pseudo-collinear antiferromagnetic ordering. We discuss the origin of this effect and give perspectives for devices based on strain-engineered BiFeO3. [ABSTRACT FROM AUTHOR]

First-principles calculations are performed to investigate the elasto-optic properties of four different structural phases in (001) epitaxial PbTi03 films under tensile strain: a tetragonal (T) phase and an orthorhombic (0) phase, which are the ground states for small and large strain, respectively, and two lowsymmetry, monoclinic phases of Cm and Pm symmetries that have low total energy in the intermediate strain range. It is found that the refractive indices of the T and O phases respond differently to epitaxial strain, evidenced by a change of sign of their effective elasto-optic coefficients, and as a result of presently discovered correlations between refractive index, axial ratio, and magnitude of the ferroelectric polarization. The difference in refractive indices between T and O and the existence of such correlations naturally lead to large elasto-optic coefficients in the Cm and Pm states in the intermediate strain range, because Cm structurally bridges the T and 0 phases (via polarization rotation and a rapid change of its axial ratio) and Pm adopts a similar axial ratio and polarization magnitude to Cm. The present results therefore broaden the palette of functionalities of ferroelectric materials, and suggest new routes to generate systems with unprecedentedly large elasto-optic conversion. [ABSTRACT FROM AUTHOR]

We measure the ferroelectric polarization of BiFeO3 films down to 3.6 nm using low energy electron and photoelectron emission microscopy. The measured polarization decays strongly below a critical thickness of 5-7 nm predicted by continuous medium theory whereas the tetragonal distortion does not change. We resolve this apparent contradiction using first-principles-based effective Hamiltonian calcu¬lations. In ultrathin films, the energetics of near open circuit electrical boundary conditions, i.e., an unscreened depolarizing field, drive the system through a phase transition from single out-of-plane polarization to nanoscale stripe domains. It gives rise to an average polarization close to zero as measured by the electron microscopy while maintaining the relatively large tetragonal distortion imposed by the nonzero polarization state of each individual domain. [ABSTRACT FROM AUTHOR]

Background: Rights-based Respectful Maternity Care (RMC) is crucial for quality of care and improved birth outcomes, yet RMC measurements are rarely included in facility improvement initiatives. We aimed to (i) co-create a routine RMC measurement tool (RMC-T) for congested maternity units in Dar es Salaam, Tanzania, and (ii) assess the RMC-T's acceptability among women and healthcare stakeholders., Method: We employed a participatory approach utilizing multiple mixed methods. This included a scoping review, stakeholder engagement involving postnatal women, healthcare providers, health leadership, and global researchers through interviews, focus groups, and two surveys involving 201 and 838 postnatal women. Cronbach's alpha and factor analysis were conducted for validation using Stata 15. Theories of social practice and Thematic Framework of Acceptability guided the assessment of stakeholder priorities and tool acceptability., Results: The multi-phased iterative co-creation process produced the 25-question RMC-T that measures satisfaction, communication, mistreatment (including physical, verbal, and sexual abuse; neglect; discrimination; lack of privacy; unconsented care; post-birth clean-up; informal payments; and denial of care), supportive care (such as food intake and mobility), birth companionship, post-procedure pain relief, bed-sharing, and newborn respect. The pragmatic validation process prioritized stakeholder feedback over strict statistics, lowering Cronbach's alpha from 0.70 in version 1 to 0.57 for the RMC-T. Women valued the opportunity to share their experiences., Conclusions: The RMC-T is contextualized, validated, and acceptable for measuring women's experiences of RMC. Routine use in facility-based quality improvement initiatives, along with targeted actions to address gaps, will advance rights-based RMC. Further validation and community-based studies are needed.

Background: Adolescents and young adults (AYA) living with HIV have been shown to have lower rates of viral load testing and viral suppression as compared to older adults. We examined trends over time and predictors of HIV viral load monitoring and viral suppression among AYA in a large HIV treatment programme in Dar es Salaam, Tanzania., Methods: We analysed longitudinal data of AYA aged 10-24 years initiated on antiretroviral therapy between January 2017 and October 2022. Trend models were used to assess changes in HIV viral load testing and viral suppression by calendar year. Generalised estimating equations were used to examine the relationship of sociodemographic and clinical factors with HIV viral load testing and viral suppression., Results: Out of 15,759 AYA, the percentage of those who received a 6-month HIV viral load testing increased from 40.6% in 2017 to 64.7% in 2022 and, a notable annual increase of 5.6% (p < 0.001). A higher HIV viral load testing uptake was observed among 20- to 24-year-olds (87.7%) compared to 10- to 19-year-olds (80.2%) (p < 0.001). The likelihood of not receiving an HIV viral load test within 12 months of antiretroviral therapy initiation was higher among 10- to 19-year-olds (adjusted odds ratio [aOR] = 1.7; 95% confidence interval [CI] = 1.4-2.0), advanced HIV disease (aOR = 1.3; 95% CI = 1.12-1.53), normal nutrition status at enrolment aOR 2.6 (95% CI = 1.59-4.26) and initiation of non-nucleoside reverse transcriptase inhibitors regimen aOR 1.2 (95% CI = 1.08-1.34). The proportion of AYA with viral suppression increased from 83.0% in 2017 to 94.6% in 2022. Notably, the overall trend in viral suppression increased significantly at 2.4% annually. The risk of not achieving viral suppression was greater among 10- to 14-year-olds (aOR = 2; 95% CI = 1.75-2.43) and 15- to 19-year-olds (aOR = 1.4; 95% CI = 1.24-1.58) as compared to 20-24 years; being male (aOR = 1.16; 95% CI = 1.02-1.32); undernourished (aOR = 1.53; 95% CI = 1.17-1.99); in WHO Stage II (aOR = 1.16; 95% CI = 1.02-1.33) and III (aOR = 1.21; 95% CI = 1.03-1.42) and being on an non-nucleoside reverse transcriptase inhibitors regimen (aOR = 1.32; 95% CI = 1.18-1.48)., Conclusion: HIV viral load testing uptake at 6 months of antiretroviral therapy initiation and viral suppression increased from 2017 to 2022; however, overall HIV viral load testing was suboptimal. Demographic and clinical characteristics can be used to identify AYA at greater risk for not having HIV viral load test and not achieving viral suppression., (© 2024 John Wiley & Sons Ltd.)

School health and nutrition programmes are effective strategies to address the health problems among school-going children and adolescents. We examined the policy environments, successes and bottlenecks associated with school health and nutrition programmes in Tanzania. We used the 'policy triangle framework' to examine 22 national and regional school health and nutrition policies and programmes in Tanzania. We also interviewed 16 key informants to gain further insights into school health and nutrition programmes. Several school health and nutrition policies in Tanzania outline the basic elements of school-based health and nutrition services. Yet, these documents neither recognise vulnerable groups, recommend age-appropriate strategies to address children's and adolescents' varied and transient needs, nor provide a framework for implementing and tracking recommended activities. In these documents, underweight and infectious diseases, including human immunodeficiency virus/acquired immunodeficiency syndrome, are frequently identified as major concerns of young people, with little or no consideration of social determinants. Diverse strategies including school feeding, water and sanitation services, health and nutrition education and promotion of healthy behaviours are identified. In doing so, these documents adequately define the roles and responsibilities of all government actors, but young people and their guardians are not actively engaged in design and implementation. Additionally, there are several challenges to implementing these policies including budgetary constraints, limited resources, a lack of inter-sectoral coordination and insufficient capacity within targeted schools. To improve the health and nutritional status of school-going children and adolescents in Tanzania, adequate budgets, strengthened coordination and implementation efforts, the development of school-based stakeholders' capacity, as well as the involvement of all other stakeholders, including adolescents, are imperative., (© 2023 The Authors. Maternal & Child Nutrition published by John Wiley & Sons Ltd.)

Background: Children and adolescents with HIV taking antiretroviral therapy (ART) have high rates of viraemia. We assessed if genotypic resistance testing (GRT) to inform onward treatment improved treatment outcomes in Lesotho and Tanzania, two countries with little access to GRT., Methods: The Genotype-Informed Versus Empirical Management of Viremia (GIVE MOVE) open-label, parallel-group randomised controlled trial enrolled children and adolescents with HIV between the ages of 6 months and 19 years, taking ART, and with a viral load at least 400 copies per mL. Participants were recruited from ten clinical centres and hospitals in Lesotho and Tanzania. Participants were electronically randomly allocated 1:1 to receive either GRT with expert recommendation (GRT group) or repeat viral-load testing and empirical onward treatment (usual care group). Participants and study staff were not masked, but the endpoint committee and laboratory staff conducting viral-load testing were. Participants in both groups received at least three sessions of enhanced adherence counselling, and in the GRT group, blood for GRT assessed via Sanger sequencing was drawn at enrolment. The composite primary endpoint was death, hospitalisation, a new WHO HIV clinical stage 4 event, or not having documented viral suppression of less than 50 copies per mL at 36 weeks in the modified intention-to-treat population, which excluded participants who were retrospectively found to be ineligible after randomisation. Serious adverse events were analysed in the modified intention-to-treat population. The trial was registered with ClinicalTrials.gov (NCT04233242) and the trial status is completed., Findings: Between March 3, 2020, and July 5, 2022, 286 participants were enrolled and 284 were included in the modified intention-to-treat analysis (144 in the GRT group and 140 in the usual care group). Of these participants, 158 (56%) were female and 126 (44%) were male. Five (3%) in the GRT group and four (3%) in the usual care group did not complete follow-up but were included in the primary analysis. The median age across both groups was 14 years (IQR 9-16). The composite primary endpoint occurred in 67 (47%) participants in the GRT group and 73 (52%) in the usual care group (adjusted odds ratio 0·79 [95% CI 0·49 to 1·27]; adjusted risk difference -0·06 [95% CI -0·17 to 0·06]; p=0·34); all participants reaching the composite primary endpoint had no documented viral suppression at 36 weeks. No deaths were recorded, and only one clinical stage 4 event requiring hospitalisation occurred (in the usual care group); this was the only serious adverse event recorded in the study., Interpretation: GRT-informed management did not significantly improve treatment outcomes for children and adolescents with viraemia while taking ART., Funding: Fondation Botnar, Swiss National Science Foundation, and Gottfried and Julia Bangerter-Rhyner Foundation., Translations: For the Sesotho and Swahili translations of the abstract see Supplementary Materials section., Competing Interests: Declaration of interests NDL reports having received travel grants to conferences from Gilead Sciences and ViiV Healthcare, and his division received honoraria for consultancies from ViiV Healthcare and for participation in a data safety monitoring board from Pharming. All other authors declare no competing interests., (Copyright © 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Alcohol consumption in Tanzania exceeds the global average. While sociodemographic difference in alcohol consumption in Tanzania have been studied, the relationship between psycho-cognitive phenomena and alcohol consumption has garnered little attention. Our study examines how depressive symptoms and cognitive performance affect alcohol consumption, considering sociodemographic variations. We interviewed 2299 Tanzanian adults, with an average age of 53 years, to assess their alcohol consumption, depressive symptoms, cognitive performance, and sociodemographic characteristics using a zero-inflated negative binomial regression model. The logistic portion of our model revealed that the likelihood alcohol consumption increased by 8.4% (95% confidence interval [CI] 3.6%, 13.1%, p < 0.001) as depressive symptom severity increased. Conversely, the count portion of the model indicated that with each one-unit increase in the severity of depressive symptoms, the estimated number of drinks decreased by 2.3% (95% CI [0.4%, 4.0%], p = .016). Additionally, the number of drinks consumed decreased by 4.7% (95% CI [1.2%, 8.1%], p = .010) for each increased cognitive score. Men exhibited higher alcohol consumption than women, and Christians tended to consume more than Muslims. These findings suggest that middle-aged and elderly adults in Tanzania tend to consume alcohol when they feel depressed but moderate their drinking habits by leveraging their cognitive abilities., (© 2024. The Author(s).)

Social network strategy (SNS) testing uses network connections to refer individuals at high risk to HIV testing services (HTS). In Tanzania, SNS testing is offered in communities and health facilities. In communities, SNS testing targets key and vulnerable populations (KVP), while in health facilities it complements index testing by reaching unelicited index contacts. Routine data were used to assess performance and trends over time in PEPFAR-supported sites between October 2021 and March 2023. Key indicators included SNS social contacts tested, and new HIV-positives individuals identified. Descriptive and statistical analysis were conducted. Univariable and multivariable analysis were applied, and variables with P -values <0.2 at univariable analysis were considered for multivariable analysis. Overall, 121,739 SNS contacts were tested, and 7731 (6.4%) previously undiagnosed individuals living with HIV were identified. Tested contacts and identified HIV-positives were mostly aged ≥15 years (>99.7%) and females (80.6% of tests, 79.4% of HIV-positives). Most SNS contacts were tested (78,363; 64.7%) and diagnosed (6376; 82.5%) in communities. SNS tests and HIV-positives grew 11.5 and 6.1-fold respectively, from October-December 2021 to January-March 2023, with majority of clients reached in communities vs. facilities (78,763 vs. 42,976). These results indicate that SNS testing is a promising HIV case-finding approach in Tanzania.

Single crystals of (001)-oriented 0.7Pb(Mg 1/3 Nb 2/3 )-0.3PbTiO 3 (PMN-30PT) with a composition near the morphotropic phase boundary have attracted considerable attention due to their superior dielectric and electromechanical performance. Recently, a new alternating current (electric field) poling approach used for the enhancement of dielectric and piezoelectric properties. However, the microscopic domain variants that govern the performance, especially under high-frequency alternating current (AC) voltages, remain largely unexplored. In this work, the domain microstructure under AC poling reveals the presence of four monoclinic (M A ) domain variants using a suite of scanning probe microscopy methods, and X-ray diffraction (XRD) reciprocal space mapping is tuned. It is reported on the emergence of hierarchical fine domains - needle-shaped, and 109° domain walls under applied high-frequency AC poling. Time-resolved Kelvin probe force microscopy (KPFM) reveals the charge dynamics and relaxation behavior of these needle domains and walls. The findings provide new insight and guidance to the domain engineering by high-frequency AC poling for the development of advanced transducer technology., (© 2024 The Authors. Small Methods published by Wiley‐VCH GmbH.)

Background: Pre-Exposure Prophylaxis (PrEP) has demonstrated efficacy in preventing HIV infection. Female Bar Workers (FBWs) often act as informal sex workers, placing them at risk of HIV infection. Despite expressing interest in PrEP, FBWs face barriers to accessing public-sector clinics where PrEP is delivered. We developed a study to compare the effectiveness of workplace-based PrEP provision to standard-of-care facility-based provision for PrEP initiation, retention and adherence among FBWs., Methods: In this double-randomized intervention study, FBWs aged 15 years and above will be screened, consented and initiated on PrEP (emtricitabine/tenofovir disoproxil), and followed for six months. Participants will be randomized at the bar level and offered PrEP at their workplace or at a health facility. Those who are initiated will be independently individually randomized to either receive or not receive an omni-channel PrEP champion intervention (support from an experienced PrEP user) to improve PrEP adherence. We expect to screen 1,205 FBWs to enroll at least 160 HIV negative women in the study. Follow-up visits will be scheduled monthly. HIV testing will be performed at baseline, month 1, 4 and 6; and TDF testing at months 2 and 6. Primary outcomes for this trial are: (1) initiation on PrEP (proportion of those offered PrEP directly observed to initiate PrEP); and (2) adherence to PrEP (detectable urine TDF drug level at 6-months post-enrollment). The primary outcomes will be analyzed using Intention-to-Treat (ITT) analyses., Discussion: Using a randomized trial design, we will evaluate two interventions aiming to reduce barriers to uptake and retention on PrEP among FBWs, a vulnerable population at risk of HIV acquisition and onward transmission. If these interventions prove effective in promoting PrEP among FBWs, they could assist in abating the HIV epidemic in Africa., Trial Registration: Registered with German Clinical Trials Register (www.drks.de) on 29 April 2020; Registration number DRKS00018101., Competing Interests: The authors declare that there are no competing interests exist., (Copyright: © 2024 Chebet et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: There is limited evidence on COVID-19 vaccination uptake among people living with HIV (PLHIV) and health care workers (HCWs), with the current evidence concentrated in high-income countries. There is also limited documentation in the published literature regarding the feasibility and lessons from implementing targeted vaccination strategies to reach PLHIV and HCWs in low- and middle-income countries., Program Development, Piloting, and Implementation: We designed and implemented multifaceted strategies to scale up targeted COVID-19 vaccination among PLHIV and HCWs in 11 administrative regions on the mainland of Tanzania plus Zanzibar. An initial 6-week intensification strategy was implemented using a diverse partnership model comprising key stakeholders at the national- and subnational levels. A layered package of strategies included expanding the number of certified vaccinators, creating vaccination points within HIV clinics, engaging HCWs to address their concerns, and building the capacity of HCWs as "champions" to promote and facilitate vaccination. We then closely monitored COVID-19 vaccination uptake in 562 high-volume HIV clinics. Between September 2021 and September 2022, the proportion of fully vaccinated adult PLHIV increased from <1% to 97% and fully vaccinated HCWs increased from 23% to 80%., Lessons and Implications: Our intra-action review highlighted the importance of leveraging a strong foundation of existing partnerships and platforms, integrating COVID-19 vaccination points within HIV clinics, and refining strategies to increase vaccination demand while ensuring continuity of vaccine supply to meet the increased demand. Lessons from Tanzania can inform targeted vaccination of vulnerable groups in future health emergencies., (© Jalloh et al.)

Background: Anemia may be associated with poor clinical outcomes among people living with human immunodeficiency virus (HIV) (PLHIV) despite highly active antiretroviral therapy (HAART). There are concerns that iron supplementation may be unsafe to prevent and treat anemia among PLHIV., Objective: The objective of the study was to evaluate the associations of anemia and iron supplementation with mortality and viral load among PLHIV in Tanzania., Methods: We analyzed data from a cohort of 70,442 nonpregnant adult PLHIV in Tanzania conducted between 2015 and 2019. Regression models evaluated the relationships between anemia severity and iron supplement use with mortality and unsuppressed HIV-1 viral load among all participants and stratified by whether participants were initiating or continuing HAART., Results: Anemia was associated with an increased risk of mortality and unsuppressed viral load for participants who initiated or continued HAART. Iron supplement use was associated with reduced mortality risk but also had a greater risk of an unsuppressed viral load among participants continuing HAART. There was no association of iron supplement use with mortality, and unsuppressed viral load among PLHIV that were initiating HAART. There was a stronger negative association between iron supplement use and the risk of having an unsuppressed viral load among participants with stage III/IV disease compared with stage I/II disease., Conclusions: Anemia is associated with increased risk of mortality and unsuppressed viral load, but the benefits and safety of iron supplements appear to differ for those initiating compared with continuing ART as well as by HIV disease severity., (Copyright © 2024 American Society for Nutrition. Published by Elsevier Inc. All rights reserved.)

Introduction: To prevent vertical HIV transmission and ensure healthy mothers and children, pregnant women with HIV must remain on antiretroviral treatment (ART) for life. However, motivation to remain on ART may decline beyond the standard 2-year breastfeeding/postpartum period. We assessed attrition and retention in ART care among women with HIV up to 6 years since enrolment in vertical transmission prevention services in Dar es Salaam, Tanzania., Methods: A prospective cohort of 22,631 pregnant women with HIV were enrolled in vertical transmission prevention services between January 2015 and December 2017 in routine healthcare settings and followed-up to July 2021. Kaplan-Meier was used to estimate time to ART attrition (died, stopped ART or was lost to follow-up [no show ≥90 days since scheduled appointment]) and the proportion retained in care. Cox proportional hazard models were used to estimate adjusted hazard ratios (aHR) of ART attrition in relation to predictors., Results: Participants were followed-up to 6 years for a median of 3 years (IQR: 0.1-4). The overall ART attrition rate was 13.8 per 100 person-years (95% CI: 13.5-14.1), highest in the first year of enrolment at 27.1 (26.3-27.9), thereafter declined to 9.5 (8.9-10.1) in year 3 and 2.7 (2.1-3.5) in year 6. The proportion of women retained in care were 78%, 69%, 63%, 60%, 57% and 56% at 1, 2, 3, 4, 5 and 6 years, respectively. ART attrition was higher in young women aged <20 years (aHR 1.63, 95% CI: 1.38-1.92) as compared to 30-39 year-olds and women enrolled late in the third versus first trimester (aHR 1.29, 95% CI: 1.16-1.44). In contrast, attrition was lower in older women ≥40 years, women who initiated ART before versus during the index pregnancy and women attending higher-level health facilities., Conclusions: ART attrition among women with HIV remains highest in the first year of enrolment in vertical transmission prevention services and declines markedly following a transition to chronic HIV care. Targeted interventions to improve ART continuity among women with HIV during and beyond prevention of vertical transmission are vital to ending paediatric HIV and keeping women and children alive and healthy., (© 2024 The Authors. Journal of the International AIDS Society published by John Wiley & Sons Ltd on behalf of International AIDS Society.)

We report the observation of a magnetocapacitance effect at the interface between Ni and epitaxial nonpolar BiInO 3 thin films at room temperature. A detailed surface study using X-ray photoelectron spectroscopy (XPS) reveals the formation of an intermetallic Ni-Bi alloy at the Ni/BiInO 3 interface and a shift in the Bi 4f and In 3d core levels to higher binding energies with increasing Ni thickness. The latter infers band bending in BiInO 3 , corresponding to the formation of a p-type Schottky barrier. The current-voltage characteristics of the Ni/BiInO 3 /(Ba,Sr)RuO 3 /NdScO 3 (110) heterostructure show a significant dependence on the applied magnetic field and voltage cycling, which can be attributed to voltage-controlled band bending and spin-polarized charge accumulation in the vicinity of the Ni/BiInO 3 interface. The magnetocapacitance effect can be realized at room temperature without involving multiferroic materials.

To curb HIV infection rate in Tanzania, antiretroviral therapy (ART) has been scaled up since 2006, and in 2019, the country shifted to regimen including dolutegravir as a default first line. We assessed the success of ART and the contribution of HIV drug resistance (HIVDR) to unsuppressed viral loads. Between February and May 2023 a cross-sectional survey with random sampling was conducted in the six clinics in an urban cohort in Dar es Salaam. Patients with unsuppresed viral loads (local criteria viral load (VL) ≥ 1000 copies/mL) were tested for HIVDR mutations using the WHO adapted protocol for plasma samples. Mutations were interpreted using the Stanford HIVDR database. In total 600 individuals participated in this survey, the majority were female (76.83%), mean age ([Formula: see text] standard deviation) was 44.0 ([Formula: see text] 11.6) years. The median duration on ART (interquartile range) was 6.5 (3.9-10.2) years. Approximately 99% were receiving tenofovir + lamivudine + dolutegravir as a fixed dose combination. VL testing was successful in 99.67% (598/600) of survey patients and only 33 had VL ≥ 1000 copies/mL, resulting in a viral suppression level of 94.48% (565/598, 95% CI 92.34-96.17%). For 23 samples, protease and reverse transcriptase (RT) genotyping were successful, with 13 sequences containing RT inhibitor surveillance drug resistance mutations (SDRMs) (56.5%). No SDRM against protease inhibitors were detected. Thirty samples were successfully genotyped for integrase with 3 sequences (10.08%) containing integrase strand transfer inhibitor (INSTI) SDRMs. In samples successfully genotyped in the three genetic regions, 68.18% (16/22) had a genotypic susceptibility score (GSS) ≥ 2.5 for the concurrent regimen, implying factors beyond drug resistance caused the unsuppressed viral load. For five patients, GSS indicated that HIVDR may have caused the unsuppressed viral load. All three patients with INSTI resistance mutations were highly resistant to dolutegravir and accumulated nucleoside and non-nucleoside RT inhibitor HIVDR mutations. Although in this cohort the last 95 UNAIDS target was almost achieved, HIVDR mutations, including INSTIs resistance mutations were detected in HIV-positive individuals taking ART for at least one year. We recommend the design and implementation of high-impact interventions to prevent the increase of HIVDR, failure of dolutegravir and address the non-resistance factors in the study area., (© 2023. The Author(s).)

Ultrashort light pulses induce rapid deformations of crystalline lattices. In ferroelectrics, lattice deformations couple directly to the polarization, which opens the perspective to modulate the electric polarization on an ultrafast time scale. Here, we report on the temporal and spatial tracking of strain and polar modulation in a single-domain BiFeO 3 thin film by ultrashort light pulses. To map the light-induced deformation of the BiFeO 3 unit cell, we perform time-resolved optical reflectivity and time-resolved x-ray diffraction. We show that an optical femtosecond laser pulse generates not only longitudinal but also shear strains. The longitudinal strain peaks at a large amplitude of 0.6%. The access of both the longitudinal and shear strains enables to quantitatively reconstruct the ultrafast deformation of the unit cell and to infer the corresponding reorientation of the ferroelectric polarization direction in space and time. Our findings open new perspectives for ultrafast manipulation of strain-coupled ferroic orders.

In ferroelectrics, complex interactions among various degrees of freedom enable the condensation of topologically protected polarization textures. Known as ferroelectric solitons, these particle-like structures represent a new class of materials with promise for beyond-CMOS technologies due to their ultrafine size and sensitivity to external stimuli. Such polarization textures have scarcely been demonstrated in multiferroics. Here, we present evidence for ferroelectric solitons in (BiFeO 3 )/(SrTiO 3 ) superlattices. High-resolution piezoresponse force microscopy and Cs-corrected high-angle annular dark-field scanning transmission electron microscopy reveal a zoo of topologies, and polarization displacement mapping of planar specimens reveals center-convergent/divergent topological defects as small as 3 nm. Phase-field simulations verify that some of these structures can be classed as bimerons with a topological charge of ±1, and first-principles-based effective Hamiltonian computations show that the coexistence of such structures can lead to non-integer topological charges, a first observation in a BiFeO 3 -based system. Our results open new opportunities in multiferroic topotronics., (© 2023. The Author(s).)

The provision of high-quality antenatal care (ANC) is important for preventing maternal and newborn mortality and morbidity, but only around half of pregnant women in Tanzania attended four or more ANC visits in 2019. Although there is emerging evidence on the benefit of community health worker (CHW) interventions on ANC uptake, few large-scale pragmatic trials have been conducted. This pragmatic cluster-randomized trial, implemented directly through the public sector health system, assessed the impact of an intervention that trained public sector CHWs to promote the uptake of ANC. We randomized 60 administrative wards in Dar es Salaam to either a targeted CHW intervention or a standard of care. The impact of the intervention was assessed using generalized estimating equations with an independent working correlation matrix to account for clustering within wards. A total of 243 908 women were included in the analysis of our primary outcome of four or more ANC visits. The intervention significantly increased the likelihood of attending four or more ANC visits [relative risk (RR): 1.42; 95% confidence interval (CI): 1.05, 1.92] and had a modest beneficial effect on the total number of ANC visits (percent change: 7.7%; 95% CI: 0.2%, 15.5%). While slightly more women in the intervention arm attended ANC in their first trimester compared with the standard-of-care arm (19% vs 18.7%), the difference was not significant (RR: 1.02; 95% CI: 0.84, 1.22). Our findings suggest that trained CHWs can increase attendance of ANC visits in Dar es Salaam and similar settings. However, additional interventions appear necessary to promote the early initiation of ANC. This study demonstrates that routine health system data can be leveraged for outcome assessment in trials and programme evaluation and that the results are likely superior, both in terms of bias and precision, to data that are collected specifically for science., (© The Author(s) 2022. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: The UNAIDS estimate of vertical HIV transmission in Tanzania is high (11%), despite 84% uptake of antiretroviral therapy (ART) among pregnant women with HIV. We aimed to evaluate vertical transmission and its determinants by 18 months post partum among women on lifelong ART in routine health-care settings in Tanzania., Methods: We conducted a prospective cohort study in 226 health facitilies across Dar-es-Salaam, Tanzania. Eligible participants were pregnant women of any age with HIV, and later their infants, who enrolled in routine health-care services for the prevention of vertical transmission. We prospectively followed up mother-infant pairs at routine monthly visits until 18 months post partum and extracted data from the care and treatment clinic (CTC2) database, a national electronic database that stores patient-level HIV care and treatment clinic data. The primary outcome was time from birth to HIV diagnosis, defined as a positive infant HIV DNA PCR or antibody test from age 18 months. We used the Kaplan-Meier method to estimate cumulative risk of vertical transmission by 18 months post partum and Cox proportional hazards regression with shared frailties to account for potential clustering in health facilities to evaluate predictors of transmission., Findings: Between Jan 1, 2015, and Dec 31, 2017, 22 930 pregnant women with HIV (median age 30 years, IQR 25-34) enrolled on a care programme. After excluding 9140 (39·9%) women and 539 (2·4%) infants with missing outcome data, 13 251 (59·0%) mother-infant pairs were analysed, of whom 6072 (45·8%) women were already on ART before pregnancy. By 18 months post partum, 159 (1·2%) of 13 251 infants were diagnosed with HIV, equivalent to a risk of vertical transmission of 1·4% (95% CI 1·2-1·6). In the complete case analysis, the rates of vertical transmission were higher among women who enrolled in the third trimester of pregnancy than among those who enrolled in the first trimester (adjusted hazard ratio 3·01, 95% CI 1·59-5·70; p=0·0003), among women with advanced HIV disease than among those with early-stage disease (1·89, 1·22-2·93; p=0·0046), and among women who were on a second-line ART regimen than among those on a first-line regimen (3·58, 1·08-11·82; p=0·037). By contrast, the rate of vertical transmission was lower among women who were already on ART at enrolment than among those starting ART at enrolment (0·39, 0·25-0·60; p<0·0001) as well as among women in high-volume clinics than among those in low-volume clinics (0·46 (0·24-0·90; p<0·0097)., Interpretation: Provision of ART for life (WHO's option B+ recommendation) has reduced the risk of vertical transmission to less than 2% among pregnant women with HIV in routine care settings in urban Tanzania. There is still a need to improve timely HIV diagnosis and ART uptake, and to optimise follow-up for the prevention of vertical transmission and the uptake of infant HIV testing., Funding: Swedish International Development Cooperation Agency., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The role of local chemical environments in the electron energy loss spectra of complex multiferroic oxides was studied using computational and experimental techniques. The evolution of the O K-edge across an interface between bismuth ferrite (BFO) and lanthanum strontium manganate (LSMO) was considered through spectral averaging over crystallographically equivalent positions to capture the periodicity of the local O environments. Computational techniques were used to investigate the contribution of individual atomic environments to the overall spectrum, and the role of doping and strain was considered. Chemical variation, even at the low level, was found to have a major impact on the spectral features, whereas strain only induced a small chemical shift to the edge onset energy. Through a combination of these methods, it was possible to explain experimentally observed effects such as spectral flattening near the interface as the combination of spectral responses from multiple local atomic environments., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Background: Isoniazid preventive therapy (IPT) can prevent tuberculosis among people receiving antiretroviral therapy (ART). HIV programmes are now initiating patients on ART with higher average CD4 cell counts and lower tuberculosis risks under test-and-treat guidelines. We aimed to investigate how this change has affected the health impact and cost-effectiveness of IPT., Methods: We constructed a tuberculosis-HIV microsimulation model parameterised using data from a large HIV treatment programme in Dar es Salaam, Tanzania. We simulated long-term health and cost outcomes for the 211 748 individuals initiating ART between Jan 1, 2014, and Dec 31, 2020, under three scenarios: no IPT access; observed levels of IPT access (75%) and completion (71%); and full (100%) IPT access and completion. We stratified results by ART initiation year and starting CD4 cell count., Findings: Observed levels of IPT access were estimated to have averted 12 800 (95% uncertainty interval 7300 to 21 600) disability-adjusted life-years (DALYs) and saved US$23 000 (-2 268 000 to 1 388 000). Full IPT access would have averted 24 500 (15 100 to 38 300) DALYs and cost $825 000 (-1 594 000 to 4 751 000), equivalent to $23·4 per DALY averted. Lifetime health benefits of IPT were estimated to be greater for more recent ART cohorts, while lifetime costs were stable. In subgroup analyses, a higher CD4 cell count at ART initiation was associated with greater health gains from IPT (15 900 [10 300 to 22 500] DALYs averted by full IPT per 100 000 patients for CD4 count >500 cells per μL at ART initiation, versus 7400 [4500 to 11 600] for CD4 count <100 cells per μL) and lower incremental lifetime costs., Interpretation: IPT remains highly cost-effective or cost-saving for recent ART cohorts. The health impact and cost-effectiveness of IPT are estimated to improve as patients initiate ART earlier in the course of infection., Funding: US National Institutes of Health., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Resonant tunneling is a quantum-mechanical effect in which electron transport is controlled by the discrete energy levels within a quantum-well (QW) structure. A ferroelectric resonant tunneling diode (RTD) exploits the switchable electric polarization state of the QW barrier to tune the device resistance. Here, the discovery of robust room-temperature ferroelectric-modulated resonant tunneling and negative differential resistance (NDR) behaviors in all-perovskite-oxide BaTiO 3 /SrRuO 3 /BaTiO 3 QW structures is reported. The resonant current amplitude and voltage are tunable by the switchable polarization of the BaTiO 3 ferroelectric with the NDR ratio modulated by ≈3 orders of magnitude and an OFF/ON resistance ratio exceeding a factor of 2 × 10 4 . The observed NDR effect is explained an energy bandgap between Ru-t 2g and Ru-e g orbitals driven by electron-electron correlations, as follows from density functional theory calculations. This study paves the way for ferroelectric-based quantum-tunneling devices in future oxide electronics., (© 2022 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

Peer support services are increasingly being integrated in programmes for the prevention of mother-to-child HIV transmission (PMTCT). We aimed to evaluate the effect of a peer-mother interactive programme on PMTCT outcomes among pregnant women on anti-retroviral treatment (ART) in routine healthcare in Dar es Salaam, Tanzania. Twenty-three health facilities were cluster-randomized to a peer-mother intervention and 24 to a control arm. We trained 92 ART experienced women with HIV to offer peer education, adherence and psychosocial support to women enrolling in PMTCT care at the intervention facilities. All pregnant women who enrolled in PMTCT care at the 47 facilities from 1st January 2018 to 31st December 2019 were identified and followed up to 31st July 2021. The primary outcome was time to ART attrition (no show >90 days since the scheduled appointment, excluding transfers) and any difference in one-year retention in PMTCT and ART care between intervention and control facilities. Secondary outcomes were maternal viral suppression (<400 viral copies/mL) and mother-to-child HIV transmission (MTCT) by ≥12 months post-partum. Analyses were done using Kaplan Meier and Cox regression (ART retention/attrition), generalized estimating equations (viral suppression) and random effects logistic regression (MTCT); reporting rates, proportions and 95% confidence intervals (CI). There were 1957 women in the peer-mother and 1384 in the control facilities who enrolled in routine PMTCT care during 2018-2019 and were followed for a median [interquartile range (IQR)] of 23 [10, 31] months. Women in both groups had similar median age of 30 [IQR 25, 35] years, but differed slightly with regard to proportions in the third pregnancy trimester (14% versus 19%); advanced HIV (22% versus 27%); and ART naïve (55% versus 47%). Peer-mother facilities had a significantly lower attrition rate per 1000 person months (95%CI) of 14 (13, 16) versus 18 (16, 19) and significantly higher one-year ART retention (95%CI) of 78% (76, 80) versus 74% (71, 76) in un-adjusted analyses, however in adjusted analyses the effect size was not statistically significant [adjusted hazard ratio of attrition (95%CI) = 0.85 (0.67, 1.08)]. Viral suppression (95%CI) was similar in both groups [92% (91, 93) versus 91% (90, 92)], but significantly higher among ART naïve women in peer-mother [91% (89, 92)] versus control [88% (86, 90)] facilities. MTCT (95%CI) was similar in both groups [2.2% (1.4, 3.4) versus 1.5% (0.7, 2.8)]. In conclusion, we learned that integration of peer-mother services in routine PMTCT care improved ART retention among all women and viral suppression among ART naïve women but had no significant influence on MTCT., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Lyatuu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Perovskite oxides with chemical formula ABO 3 are widely studied for their properties including ferroelectricity, magnetism, strongly correlated physics, optical effects, and superconductivity. A thriving research direction using such materials is through their integration as epitaxial thin films, allowing many novel and exotic effects to be discovered. The integration of the thin film on a single crystal substrate, however, can produce unique and powerful effects, and can even induce phases in the thin film that are not stable in bulk. The substrate imposed mechanical boundary conditions such as strain, crystallographic orientation, octahedral rotation patterns, and symmetry can also affect the functional properties of perovskite films. Here, the author reviews the current state of the art in epitaxial strain and orientation engineering in perovskite oxide thin films. The paper begins by introducing the effect of uniform conventional biaxial strain, and then moves to describe how the substrate crystallographic orientation can induce symmetry changes in the film materials. Various material case studies, including ferroelectrics, magnetically ordered materials, and nonlinear optical oxides are covered. The connectivity of the oxygen octahedra between film and substrate depending on the strain level as well as the crystallographic orientation is then discussed. The review concludes with open questions and suggestions worthy of the community's focus in the future., (© 2022 IOP Publishing Ltd.)

Piezoelectrics interconvert mechanical energy and electric charge and are widely used in actuators and sensors. The best performing materials are ferroelectrics at a morphotropic phase boundary, where several phases coexist. Switching between these phases by electric field produces a large electromechanical response. In ferroelectric BiFeO 3 , strain can create a morphotropic-phase-boundary-like phase mixture and thus generate large electric-field-dependent strains. However, this enhanced response occurs at localized, randomly positioned regions of the film. Here, we use epitaxial strain and orientation engineering in tandem-anisotropic epitaxy-to craft a low-symmetry phase of BiFeO 3 that acts as a structural bridge between the rhombohedral-like and tetragonal-like polymorphs. Interferometric displacement sensor measurements reveal that this phase has an enhanced piezoelectric coefficient of ×2.4 compared with typical rhombohedral-like BiFeO 3 . Band-excitation frequency response measurements and first-principles calculations provide evidence that this phase undergoes a transition to the tetragonal-like polymorph under electric field, generating an enhanced piezoelectric response throughout the film and associated field-induced reversible strains. These results offer a route to engineer thin-film piezoelectrics with improved functionalities, with broader perspectives for other functional oxides., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Community health worker (CHW)-led community delivery of HIV antiretroviral therapy (ART) could increase ART coverage and decongest healthcare facilities. It is unknown how much patients would be willing to pay to receive ART at home and, thus, whether ART community delivery could be self-financing. Set in Dar es Salaam, this study aimed to determine patients' willingness to pay (WTP) for CHW-led ART community delivery. We sampled ART patients living in the neighbourhoods surrounding each of 48 public-sector healthcare facilities in Dar es Salaam. We asked participants (N = 1799) whether they (1) preferred ART community delivery over standard facility-based care, (2) would be willing to pay for ART community delivery and (3) would be willing to pay each of an incrementally increasing range of prices for the service. 45.0% (810/1799; 95% CI: 42.7-47.3) of participants preferred ART community delivery over standard facility-based care and 51.5% (417/810; 95% CI: 48.1-55.0) of these respondents were willing to pay for ART community delivery. Among those willing to pay, the mean and median amount that participants were willing to pay for one ART community delivery that provides a 2-months' supply of antiretroviral drugs was 3.61 purchasing-power-parity-adjusted dollars (PPP$) (95% CI: 2.96-4.26) and 1.27 PPP$ (IQR: 1.27-2.12), respectively. An important limitation of this study is that participants all resided in neighbourhoods within the catchment area of the healthcare facility at which they were interviewed and, thus, may incur less costs to attend standard facility-based ART care than other ART patients in Dar es Salaam. While there appears to be a substantial WTP, patient payments would only constitute a minority of the costs of implementing ART community delivery. Thus, major co-financing from governments or donors would likely be required., (© The Author(s) 2020. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine.)

This study describes organic thin films prepared under a range of conditions from a model series of bis- N -alkyl chloro-triazines functionalized with short alkyl chains from ethyl to hexyl. The pure films were characterized using atomic force microscopy (AFM), X-ray diffraction (XRD), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). When cast on mica, these compounds assemble as crystalline sheets made up of a synthetic bilayer along the crystallographic ab -plane with an internal hydrogen-bonded domain between external alkyl chains. These micron-scale surfaces stack along the c -axis, and increasing the alkyl chain length results in changes to the crystal morphology from needles to nanoscale plates. Thicker films produce nanoscale, pyramidal stacks of bilayers. Compared to atomically flat mica, a rougher, unetched silicon substrate produced irregular domains in the secondary bilayer. Films of mixtures comprising the ethyl derivative with butyl, pentyl, or hexyl derivative were imaged using time-of-flight secondary-ion mass spectrometry (ToF-SIMS) that indicated a trend toward a constant stoichiometry with increasing alkyl chain length. AFM of mixed films on mica showed single bilayers of height <2 nm, with an acceptable correlation to the XRD measurements, supporting a constant stoichiometry. These materials permit easy modification of mica to a micron-scale, atomically flat hydrophobic surface, and the use of mixtures with different alkyl chain lengths suggests a method to improve the quality of functional organic thin films.

Bismuth ferrite (BiFeO 3 ) is one of the most widely studied multiferroics. The coexistence of ferroelectricity and antiferromagnetism in this compound has driven an intense search for electric-field control of the magnetic order. Such efforts require a complete understanding of the various exchange interactions that underpin the magnetic behavior. An important characteristic of BiFeO 3 is its noncollinear magnetic order; namely, a long-period incommensurate spin cycloid. Here, the progress in understanding this fascinating aspect of BiFeO 3 is reviewed, with a focus on epitaxial films. The advances made in developing the theory used to capture the complexities of the cycloid are first chronicled, followed by a description of the various experimental techniques employed to probe the magnetic order. To help the reader fully grasp the nuances associated with thin films, a detailed description of the spin cycloid in the bulk is provided. The effects of various perturbations on the cycloid are then described: magnetic and electric fields, doping, epitaxial strain, finite size effects, and temperature. To conclude, an outlook on possible device applications exploiting noncollinear magnetism in BiFeO 3 films is presented. It is hoped that this work will act as a comprehensive experimentalist's guide to the spin cycloid in BiFeO 3 thin films., (© 2020 Wiley-VCH GmbH.)