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Summary: Background: Current literature informs us that bivalent vaccines will generate a broader serum neutralizing antibody response to multiple SARS-CoV-2 variants, but studies on how this breadth relates to the memory B cell (MBC) and T cell responses are sparse. This study compared breadth of neutralising antibody, and memory B and T cell responses to monovalent or a bivalent ancestral/Omicron BA.1 COVID-19 booster vaccine. Methods: At baseline and 1-month post-booster, neutralisation activity and frequencies of receptor binding domain (RBD)-specific MBCs and Spike-specific memory T cells were measured against a panel of variants. Findings: Both vaccines boosted neutralising antibodies to 5 variants - Wuhan-Hu-1, Delta, BA.1, BA.5 and JN.1, the latter of which had not yet emerged at the time of sample collection. The bivalent vaccine induced a significantly larger increase in nAb against BA.1 and JN.1. Both vaccines boosted RBD-specific MBC responses to Wuhan-Hu-1, Delta, BA.1 and BA.5 variants with a significantly greater increase for BA.1 in the bivalent group. The breadth of MBCs was significantly higher in those who received the bivalent boost and correlated with nAb breadth. Both vaccines significantly boosted Spike-specific T cell responses to the Wuhan-Hu-1 and BA.5 variants, but only the bivalent vaccine boosted BA.1 responses. Interpretation: These results suggest that the bivalent vaccine confers an advantage against future novel variants due to increased frequency of broadly reactive RBD-specific B cells. Funding: Work supported by NSW Health for the NSW Vaccine, Infection and Immunology Collaborative (VIIM).

Hispanic and African American student-fathers are an invisible population in the student support literature on college campuses. In this qualitative study, we examined the lived experiences of 17 student-fathers attending Hispanic Serving Institutions and Historically Black Colleges and Universities. Six themes emerged from our data: family support, uncertainty in parenting practices, co-parenting relationships, responsibility as a father, negative stereotypes, and fatherhood as motivation. Our findings have implications for institutions of higher education.

Abstract Background The COVID-19 pandemic produced system-level changes within the criminal legal system and community-based substance use disorder (SUD) treatment system with impacts on recovery efforts. This study examines rural and urban clinicians’ perspectives of COVID-19 on SUD treatment delivery for people on community supervision. Methods Virtual qualitative interviews were conducted between April and October 2020 with 25 community supervision clinicians employed by Kentucky’s Department of Corrections (DOC), who conduct assessments and facilitate community-based treatment linkages for individuals on probation or parole. Transcripts were analyzed in NVivo using directed content analysis methods. Results Clinicians were predominantly white (92%) and female (88%) with an average of over 9 years working in the SUD treatment field and 4.6 years in their current job. Four COVID-19 themes were identified by both rural and urban clinicians including: (1) telehealth increases the modes of communication, but (2) also creates paperwork and technological challenges, (3) telehealth requires more effort for inter/intra-agency collaboration, and (4) it limits client information (e.g., no urine drug screens). Two additional rural-specific themes emerged related to COVID-19: (5) increasing telehealth options removes SUD treatment transportation barriers and (6) requires flexibility with programmatic requirements for rural clients. Conclusions Findings indicate the need for community-based SUD treatment providers approved or contracted by DOC to support and train clients to access technology and improve information-sharing with community supervision officers. A positive lesson learned from COVID-19 transitions was a reduction in costly travel for rural clients, allowing for greater engagement and treatment adherence. Telehealth should continue to be included within the SUD continuum of care, especially to promote equitable services for individuals from rural areas.

ABSTRACT: Heat stress is a prominent issue in livestock production, even for intensively housed dairy herds in Canada. Production records and meteorological data can be combined to assess heat tolerance in dairy cattle. The overall aim of this study was to evaluate the possibility of genetic evaluation for heat tolerance in Canadian dairy cattle. The 2 specific objectives were (1) to estimate the genetic parameters for milk, fat, and protein yield for Holsteins while accounting for high environmental heat loads, and (2) to determine if a genotype-by-environment interaction causes reranking of top-ranked sires between environments with low and high heat loads. A repeatability test-day model with a heat stress function was used to evaluate the genetic merit for milk, fat, and protein yield under heat stress and at thermal comfort for first parity in 5 regions in Canada. The heat stress function for each trait was defined using a specific temperature-humidity index (THI) threshold. The purpose of this function was to quantify the level of heat stress that was experienced by the dairy cattle. The estimated genetic correlation between the general additive genetic effect and the additive effect on the slope of the change in the trait phenotype for milk, fat, and protein yield ranged from −0.16 to −0.30, −0.20 to −0.44, and −0.28 to −0.42, respectively. These negative correlations imply that there is an antagonistic relationship between sensitivity to heat stress and level of production. The heritabilities for milk, fat, and protein yield at 15 units above the THI threshold ranged from 0.15 to 0.27, 0.11 to 0.15, and 0.11 to 0.15, respectively. Finally, the rank correlations between the breeding values from a repeatability model with no heat stress effect and the breeding values accounting for heat stress for the 100 top-ranked bulls indicated possible interaction between milk production traits and THI, resulting in substantial reranking of the top-ranked sires in Canada, especially for milk yield. This is the first study to implement weather data from the NASA POWER database in a genetic evaluation of heat tolerance in dairy cattle. The NASA POWER database is a novel alternative meteorological resource that is potentially more reliable and consistent and with broader coverage than weather station data increasing the number of animals that could be included in a heat stress evaluation.

Introduction Raising the price of cigarettes via taxation has been promoted by the World Health Organization as an important tobacco control strategy. Price elasticity of cigarettes is not uniform and is dependent upon individual and environmental determinants. Many studies have examined the determinants of price-induced smoking, taking into account sociodemographic characteristics and consumption patterns. Little research has been conducted on the association between anti-smoking environments and price-induced smoking behavior. This study addresses the deficit within the Chinese context. Methods Participants were 2852 male smokers identified through a multi-stage survey sampling process encompassing 6 cities in China between July and December 2016. A standardized questionnaire tapped price-induced smoking reduction and related information. Both unadjusted and adjusted logistic regression methods were applied in the analyses. Results In all, 25.5% (95% CI: 22.5–27.9) of smokers in this study decreased their smoking expenditures following the 2015 excise tax increase. The adjusted logistic regression analysis showed that increased exposures to an anti-smoking information environment (AOR=1.39; 95% CI: 1.10–1.79), restricted smoking in their home (AOR=1.67; 95% CI: 1.32–2.08) and workplace (AOR=1.43; 95% CI: 1.09–1.85) were more likely to report diminished cigarette smoking following the tax increases. Conclusions This study adds to understanding price-induced smoking behavior among urban male Chinese smokers. Strengthening of excise tax policies needs to intensify environmental smoking restrictions and public education campaigns to increase the sensitivity of cigarette price changes among smokers.

William D Chey,1 Darren M Brenner,2 Brooks D Cash,3 Martin Hale,4 Jeremy Adler,5 Mansi S Jamindar,6 Carol B Rockett,6 June S Almenoff,6 Enoch Bortey,7 Jeffrey Gudin8 1Department of Internal Medicine, Division of Gastroenterology and Hepatology, Michigan Medicine, Ann Arbor, MI, USA; 2Departments of Medicine and Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA; 3Division of Gastroenterology, Hepatology, and Nutrition at the University of Texas Health Science Center at Houston, Houston, TX, USA; 4Gold Coast Research, L.L.C, Miami, FL, USA; 5Pacific Pain Medicine Consultants, Encinitas, CA, USA; 6Medical Affairs, RedHill Biopharma, Inc, Raleigh, NC, USA; 7Pharmaceutical Development Strategies, L.L.C, Chapel Hill, NC, USA; 8Department of Anesthesiology and Pain Management, University of Miami, Miami, FL, USACorrespondence: June S Almenoff, Email jalmenoff@redhillus.comObjective: This study evaluates the onset, magnitude, and consistency of improvement of opioid-induced constipation (OIC) symptoms with naloxegol treatment.Methods: This was a pooled analysis of two Phase 3, double-blind, randomized, placebo-controlled studies (KODIAC-04/05, NCT01309841/NCT01323790) in patients with chronic non-cancer pain and OIC treated with naloxegol 25mg or 12.5mg daily. This analysis assessed improvements in response rates, frequency of spontaneous bowel movement (SBM) and complete SBMs (CSBM), OIC constipation symptoms (straining, stool consistency), time to first post-dose SBM and CSBM, and onset of adverse events over the 12-week period.Subjects: The population of 1337 subjects had a mean age of 52 years and mean duration of opioid use of 3.6 years at baseline. Mean SBM frequency was 1.4/week.Results: Naloxegol 25mg and 12.5mg demonstrated significantly higher response rates vs placebo (PBO) [41.9% (P < 0.001), 37.8% (P = 0.008), 29.4% respectively]. Rapid (within 1 week) and sustained (over 12 weeks) symptom improvement was significantly greater for naloxegol vs PBO (P < 0.05). Both doses showed statistically significant and clinically meaningful improvements in straining, stool consistency, number of SBMs and CSBMs/wk. Significantly shorter times to first post-dose SBM and CSBM were observed with naloxegol vs PBO (SBM HR: 25mg = 1.90, 12.5mg= 1.60; CSBM HR: 25mg = 1.42, 12.5mg = 1.36; P < 0.001 for each regimen). Adverse events occurred more frequently in the naloxegol 25mg group and were most frequently reported during the first week.Conclusion: In patients with chronic non-cancer pain, naloxegol 25mg and 12.5mg demonstrated significantly higher response rates and rapid and sustained improvements in OIC symptoms compared with PBO.Keywords: opioid-induced constipation, naloxegol, clinical trials

BackgroundNational Malaria Control Programmes (NMCPs) currently make limited use of parasite genetic data. We have developed GenRe-Mekong, a platform for genetic surveillance of malaria in the Greater Mekong Subregion (GMS) that enables NMCPs to implement large-scale surveillance projects by integrating simple sample collection procedures in routine public health procedures.MethodsSamples from symptomatic patients are processed by SpotMalaria, a high-throughput system that produces a comprehensive set of genotypes comprising several drug resistance markers, species markers and a genomic barcode. GenRe-Mekong delivers Genetic Report Cards, a compendium of genotypes and phenotype predictions used to map prevalence of resistance to multiple drugs.ResultsGenRe-Mekong has worked with NMCPs and research projects in eight countries, processing 9623 samples from clinical cases. Monitoring resistance markers has been valuable for tracking the rapid spread of parasites resistant to the dihydroartemisinin-piperaquine combination therapy. In Vietnam and Laos, GenRe-Mekong data have provided novel knowledge about the spread of these resistant strains into previously unaffected provinces, informing decision-making by NMCPs.ConclusionsGenRe-Mekong provides detailed knowledge about drug resistance at a local level, and facilitates data sharing at a regional level, enabling cross-border resistance monitoring and providing the public health community with valuable insights. The project provides a rich open data resource to benefit the entire malaria community.FundingThe GenRe-Mekong project is funded by the Bill and Melinda Gates Foundation (OPP11188166, OPP1204268). Genotyping and sequencing were funded by the Wellcome Trust (098051, 206194, 203141, 090770, 204911, 106698/B/14/Z) and Medical Research Council (G0600718). A proportion of samples were collected with the support of the UK Department for International Development (201900, M006212), and Intramural Research Program of the National Institute of Allergy and Infectious Diseases.

Abstract The emergence of resistance to antiviral drugs increasingly used to treat SARS-CoV-2 infections has been recognised as a significant threat to COVID-19 control. In addition, some SARS-CoV-2 variants of concern appear to be intrinsically resistant to several classes of these antiviral agents. Therefore, there is a critical need for rapid recognition of clinically relevant polymorphisms in SARS-CoV-2 genomes associated with significant reduction of drug activity in virus neutralisation experiments. Here we present SABRes, a bioinformatic tool, which leverages on expanding public datasets of SARS-CoV-2 genomes and allows detection of drug resistance mutations in consensus genomes as well as in viral subpopulations. We have applied SABRes to detect resistance-conferring mutations in 25,197 genomes generated over the course of the SARS-CoV-2 pandemic in Australia and identified 299 genomes containing resistance conferring mutations to the five antiviral therapeutics that retain effectiveness against currently circulating strains of SARS-CoV-2 – Sotrovimab, Bebtelovimab, Remdesivir, Nirmatrelvir and Molnupiravir. These genomes accounted for a 1.18% prevalence of resistant isolates discovered by SABRes, including 80 genomes with resistance conferring mutations found in viral subpopulations. Timely recognition of these mutations within subpopulations is critical as these mutations can provide an advantage under selective pressure and presents an important step forward in our ability to monitor SARS-CoV-2 drug resistance.

Malaria and iron deficiency (ID) are common and interrelated public health problems in African children. Observational data suggest that interrupting malaria transmission reduces the prevalence of ID1. To test the hypothesis that malaria might cause ID, we used sickle cell trait (HbAS, rs334 ), a genetic variant that confers specific protection against malaria2, as an instrumental variable in Mendelian randomization analyses. HbAS was associated with a 30% reduction in ID among children living in malaria-endemic countries in Africa (n = 7,453), but not among individuals living in malaria-free areas (n = 3,818). Genetically predicted malaria risk was associated with an odds ratio of 2.65 for ID per unit increase in the log incidence rate of malaria. This suggests that an intervention that halves the risk of malaria episodes would reduce the prevalence of ID in African children by 49%.

ABSTRACT Constantly evolving viral populations affect the specificity of primers and the quality of genomic surveillance. This study presents a framework for the continuous optimization of sequencing efficiency for public health surveillance based on the ongoing evolution of the COVID-19 pandemic. SARS-CoV-2 genomic clustering capacity based on three amplification-based whole genome sequencing schemes was assessed using decreasing thresholds of genome coverage and measured against epidemiologically linked cases. The overall genome coverage depth and individual amplicon depth were used to calculate an amplification efficiency metric. Significant loss of genome coverage over time was documented, which was recovered by optimization of primer pooling or implementation of new primer sets. A minimum of 95% genome coverage was required to cluster 94% of epidemiologically defined SARS-CoV-2 transmission events. Clustering resolution fell to 70% when only 85% genome coverage was achieved. The framework presented in this study can provide public health genomic surveillance programs with a systematic process to ensure an agile and effective laboratory response during rapidly evolving viral outbreaks. IMPORTANCE This study provides a laboratory framework to ensure ongoing relevance and performance of amplification-based whole genome sequencing to strengthen public health surveillance during extended outbreaks or pandemics. The framework integrates regular reviews of the performance of a genomic surveillance system and highlights the importance of ongoing monitoring and the identification and implementation of improvements to whole genome sequencing methods to enhance public health responses to pathogen outbreaks.

Alkali halide postdeposition treatments (PDTs) have become a key tool to maximize efficiency in Cu(InxGa1−x)Se2 (CIGS) photovoltaics. RbF PDTs have emerged as an alternative to the more common Na‐ and K‐based techniques. This study utilizes temperature‐dependent current–voltage (JVT) measurements to study a unique RbF PDT performed in a S atmosphere. The samples are measured before and after 6 months in a desiccator to study device stability. Both samples contain Na and K which diffuse from the soda–lime glass substrate. A reference sample and a RbF + S PDT sample both show the development of a rear contact barrier after aging. The contact barrier is higher for the RbF + S PDT sample, leading to decreased current in forward bias. Series resistance is also higher in the RbF + S PDT device which leads to lower fill factor. However, after aging the reference sample has a larger decrease in open‐circuit voltage (VOC). Ideality factor measurements suggest Shockley–Read–Hall recombination dominates both samples. VOC versus temperature and a temperature‐dependent activation energy model are used to calculate diode activation energies for each sample condition. Both techniques produce similar values that indicate recombination primarily occurs within the bulk absorber.

The premise of Open Science is that research and medical management will progress faster if data and knowledge are openly shared. The value of Open Science is nowhere more important and appreciated than in the rare disease (RD) community. Research into RDs has been limited by insufficient patient data and resources, a paucity of trained disease experts, and lack of therapeutics, leading to long delays in diagnosis and treatment. These issues can be ameliorated by following the principles and practices of sharing that are intrinsic to Open Science. Here, we describe how the RD community has adopted the core pillars of Open Science, adding new initiatives to promote care and research for RD patients and, ultimately, for all of medicine. We also present recommendations that can advance Open Science more globally.

ABSTRACT: Weather station data and test-day production records can be combined to quantify the effects of heat stress on production traits in dairy cattle. However, meteorological data sets that are retrieved from ground-based weather stations can be limited by spatial and temporal data gaps. The National Aeronautics and Space Administration Prediction of Worldwide Energy Resources (NASA POWER) database provides meteorological data over regions where surface measurements are sparse or nonexistent. The first aim of this study was to determine whether NASA POWER data are a viable alternative resource of weather data for studying heat stress in Canadian Holsteins. The results showed that average, minima, and maxima ambient temperature and dewpoint temperature as well as 4 different types of temperature-humidity index (THI) values from NASA POWER were highly correlated to the corresponding values from weather stations (regression R2 > 0.80). However, the NASA POWER values for the daily average, minima, and maxima wind speed and relative humidity were poorly correlated to the corresponding weather station values (regression R2 = 0.10 to 0.49). The second aim of this study was to quantify the influence of heat stress on Canadian dairy cattle. This was achieved by determining the THI values at which milk, protein, and fat yield started to decline due to heat stress as well as the rates of decline in these traits after the respective thresholds, using segmented polynomial regression models. This was completed for both primiparous and multiparous cows from 5 regions in Canada (Ontario, Quebec, British Columbia, the Prairies, and the Atlantic Maritime). The results showed that all production traits were negatively affected by heat stress and that the patterns of responses for milk, fat, and protein yields to increasing THI differed from each other. We found 3 THI thresholds for milk yield, 1 for fat yield, and 2 for protein yield. All thresholds marked a change in rate of decrease in production yield per unit THI, except for the first milk yield threshold, which marked a greater rate of increase. The first thresholds for milk yield ranged between 47 and 50, the second thresholds ranged between 61 and 69, and the third thresholds ranged between 72 and 76 THI units. The single THI threshold for fat yield ranged between 48 and 55 THI units. Finally, the first and second thresholds ranged between 58 and 62 THI units and 72 and 73 THI units for protein yield, respectively.

Abstract Background Estimating the economic costs of self-injury mortality (SIM) can inform health planning and clinical and public health interventions, serve as a basis for their evaluation, and provide the foundation for broadly disseminating evidence-based policies and practices. SIM is operationalized as a composite of all registered suicides at any age, and 80% of drug overdose (intoxication) deaths medicolegally classified as ‘accidents,’ and 90% of corresponding undetermined (intent) deaths in the age group 15 years and older. It is the long-term practice of the United States (US) Centers for Disease Control and Prevention (CDC) to subsume poisoning (drug and nondrug) deaths under the injury rubric. This study aimed to estimate magnitude and change in SIM and suicide costs in 2019 dollars for the United States (US), including the 50 states and the District of Columbia. Methods Cost estimates were generated from underlying cause-of-death data for 1999/2000 and 2018/2019 from the US Centers for Disease Control and Prevention’s (CDC’s) Wide-ranging ONline Data for Epidemiologic Research (WONDER). Estimation utilized the updated version of Medical and Work Loss Cost Estimation Methods for CDC’s Web-based Injury Statistics Query and Reporting System (WISQARS). Exposures were medical expenditures, lost work productivity, and future quality of life loss. Main outcome measures were disaggregated, annual-averaged total and per capita costs of SIM and suicide for the nation and states in 1999/2000 and 2018/2019. Results 40,834 annual-averaged self-injury deaths in 1999/2000 and 101,325 in 2018/2019 were identified. Estimated national costs of SIM rose by 143% from $0.46 trillion to $1.12 trillion. Ratios of quality of life and work losses to medical spending in 2019 US dollars in 2018/2019 were 1,476 and 526, respectively, versus 1,419 and 526 in 1999/2000. Total national suicide costs increased 58%—from $318.6 billion to $502.7 billion. National per capita costs of SIM doubled from $1,638 to $3,413 over the observation period; costs of the suicide component rose from $1,137 to $1,534. States in the top quintile for per capita SIM, those whose cost increases exceeded 152%, concentrated in the Great Lakes, Southeast, Mideast and New England. States in the bottom quintile, those with per capita cost increases below 70%, were located in the Far West, Southwest, Plains, and Rocky Mountain regions. West Virginia exhibited the largest increase at 263% and Nevada the smallest at 22%. Percentage per capita cost increases for suicide were smaller than for SIM. Only the Far West, Southwest and Mideast were not represented in the top quintile, which comprised states with increases of 50% or greater. The bottom quintile comprised states with per capita suicide cost increases below 24%. Regions represented were the Far West, Southeast, Mideast and New England. North Dakota and Nevada occupied the extremes on the cost change continuum at 75% and − 1%, respectively. Conclusion The scale and surge in the economic costs of SIM to society are large. Federal and state prevention and intervention programs should be financed with a clear understanding of the total costs—fiscal, social, and personal—incurred by deaths due to self-injurious behaviors.

Using whole genome sequencing and broad sampling across the nation, the genetic diversity of the malaria mosquito An. minimus across Cambodia is described.

Introduction While many studies have confirmed that smoking is causally associated with various diseases, some have found an association between smoking and human functional impairment. Relationships between smoking and poor healthrelated quality of life (HRQoL) have been investigated in general populations. However, these studies have examined only individual-level correlates. This study examined the association between smoking and poor HRQoL, at both the individual and contextual levels, in university settings across China. Methods Large-scale survey sampling was conducted among 11659 healthprofession students from 31 Chinese universities. HRQoL was measured by the EQ-5D instrument. This multilevel, multivariable analysis utilized unadjusted and adjusted methods. Results Prevalence of poor HRQoL in this study was 2.7% (95% CI: 1.9–3.5). Multilevel logistic regression analysis revealed that frequent (OR=3.18; 95% CI: 2.35–4.33) and occasional smokers (OR=2.73; 95% CI: 1.61–4.65) and universities with high (OR=2.68; 95% CI: 1.34–5.35) and medium smoking prevalence (OR=1.49; 95% CI: 0.95–5.35) had excess odds of poor HRQoL compared to their respective referents, non-smokers and universities with a low smoking prevalence. Conclusions This multilevel study provides new evidence that smoking is associated with poor HRQL. Findings underscore the importance of alerting the populace that functional impairment is linked to smoking.

Blood group O is associated with protection against severe malaria and reduced size and stability of P. falciparum-host red blood cell (RBC) rosettes compared to non-O blood groups. Whether the non-O blood groups encoded by the specific ABO genotypes AO, BO, AA, BB and AB differ in their associations with severe malaria and rosetting is unknown. The A and B antigens are host RBC receptors for rosetting, hence we hypothesized that the higher levels of A and/or B antigen on RBCs from AA, BB and AB genotypes compared to AO/BO genotypes could lead to larger rosettes, increased microvascular obstruction and higher risk of malaria pathology. We used a case-control study of Kenyan children and in vitro adhesion assays to test the hypothesis that "double dose" non-O genotypes (AA, BB, AB) are associated with increased risk of severe malaria and larger rosettes than "single dose" heterozygotes (AO, BO). In the case-control study, compared to OO, the double dose genotypes consistently had higher odds ratios (OR) for severe malaria than single dose genotypes, with AB (OR 1.93) and AO (OR 1.27) showing most marked difference (p = 0.02, Wald test). In vitro experiments with blood group A-preferring P. falciparum parasites showed that significantly larger rosettes were formed with AA and AB host RBCs compared to OO, whereas AO and BO genotypes rosettes were indistinguishable from OO. Overall, the data show that ABO genotype influences P. falciparum rosetting and support the hypothesis that double dose non-O genotypes confer a greater risk of severe malaria than AO/BO heterozygosity.

Elemental intermixing at the CdS/CuIn 1−x Ga x Se 2 (CIGS) heterojunction in thin-film photovoltaic devices plays a crucial role in carrier separation and thus device efficiency. Using scanning transmission electron microcopy in combination with energy dispersive X-ray mapping, we find that by controlling the oxygen in the sputtering gas during physical vapor deposition (PVD) of the CdS, we can tailor the degree of elemental intermixing. More oxygen suppresses Cu migration from the CIGS into the CdS, while facilitating Zn doping in the CdS from the ZnO transparent contact. Very high oxygen levels induce nanocrystallinity in the CdS, while moderate or no oxygen content can promote complete CdS epitaxy on the CIGS grains. Regions of cubic Cu 2 S phase were observed in the Cu-rich CdCuS when no oxygen is included in the CdS deposition process. In the process-of-record sample (moderate O 2 ) that exhibits the highest solar conversion efficiency, we observe a ~26-nm-thick Cu-deficient CIGS surface counter-doped with the highest Cd concentration among all of the samples. Cd movement into the CIGS was found to be less than 10 nm deep for samples with either high or zero O 2 . The results are consistent with the expectation that Cd doping of the CIGS surface and lack of Zn diffusion into the buffer both enhance device performance.

Elemental intermixing at the CdS/CuIn 1−x Ga x Se 2 (CIGS) heterojunction in thin-film photovoltaic devices plays a crucial role in carrier separation and thus device efficiency. Using scanning transmission electron microcopy in combination with energy dispersive X-ray mapping, we find that by controlling the oxygen in the sputtering gas during physical vapor deposition (PVD) of the CdS, we can tailor the degree of elemental intermixing. More oxygen suppresses Cu migration from the CIGS into the CdS, while facilitating Zn doping in the CdS from the ZnO transparent contact. Very high oxygen levels induce nanocrystallinity in the CdS, while moderate or no oxygen content can promote complete CdS epitaxy on the CIGS grains. Regions of cubic Cu 2 S phase were observed in the Cu-rich CdCuS when no oxygen is included in the CdS deposition process. In the process-of-record sample (moderate O 2 ) that exhibits the highest solar conversion efficiency, we observe a ~26-nm-thick Cu-deficient CIGS surface counter-doped with the highest Cd concentration among all of the samples. Cd movement into the CIGS was found to be less than 10 nm deep for samples with either high or zero O 2 . The results are consistent with the expectation that Cd doping of the CIGS surface and lack of Zn diffusion into the buffer both enhance device performance.