Role of DNA methylation in the association of lung function with body mass index: a two-step epigenetic Mendelian randomisation study

Low lung function has been associated with increased body mass index (BMI). The aim of this study was to investigate whether the effect of BMI on lung function is mediated by DNA methylation.; We used individual data from 285,495 participants in four population-based cohorts: the European Community Respiratory Health Survey, the Northern Finland Birth Cohort 1966, the Swiss Study on Air Pollution and Lung Disease in Adults, and the UK Biobank. We carried out Mendelian randomisation (MR) analyses in two steps using a two-sample approach with SNPs as instrumental variables (IVs) in each step. In step 1 MR, we estimated the causal effect of BMI on peripheral blood DNA methylation (measured at genome-wide level) using 95 BMI-associated SNPs as IVs. In step 2 MR, we estimated the causal effect of DNA methylation on FEV; 1; , FVC, and FEV; 1; /FVC using two SNPs acting as methQTLs occurring close (in cis) to CpGs identified in the first step. These analyses were conducted after exclusion of weak IVs (F statistic < 10) and MR estimates were derived using the Wald ratio, with standard error from the delta method. Individuals whose data were used in step 1 were not included in step 2.; In step 1, we found that BMI might have a small causal effect on DNA methylation levels (less than 1% change in methylation per 1 kg/m2 increase in BMI) at two CpGs (cg09046979 and cg12580248). In step 2, we found no evidence of a causal effect of DNA methylation at cg09046979 on lung function. We could not estimate the causal effect of DNA methylation at cg12580248 on lung function as we could not find publicly available data on the association of this CpG with SNPs.; To our knowledge, this is the first paper to report the use of a two-step MR approach to assess the role of DNA methylation in mediating the effect of a non-genetic factor on lung function. Our findings do not support a mediating effect of DNA methylation in the association of lung function with BMI

A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa

[Figure: see text]

Emergence and spread of two SARS-CoV-2 variants of interest in Nigeria.

Identifying the dissemination patterns and impacts of a virus of economic or health importance during a pandemic is crucial, as it informs the public on policies for containment in order to reduce the spread of the virus. In this study, we integrated genomic and travel data to investigate the emergence and spread of the SARS-CoV-2 B.1.1.318 and B.1.525 (Eta) variants of interest in Nigeria and the wider Africa region. By integrating travel data and phylogeographic reconstructions, we find that these two variants that arose during the second wave in Nigeria emerged from within Africa, with the B.1.525 from Nigeria, and then spread to other parts of the world. Data from this study show how regional connectivity of Nigeria drove the spread of these variants of interest to surrounding countries and those connected by air-traffic. Our findings demonstrate the power of genomic analysis when combined with mobility and epidemiological data to identify the drivers of transmission, as bidirectional transmission within and between African nations are grossly underestimated as seen in our import risk index estimates

A year of genomic surveillance reveals how the SARS-CoV-2 pandemic unfolded in Africa.

The progression of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic in Africa has so far been heterogeneous, and the full impact is not yet well understood. In this study, we describe the genomic epidemiology using a dataset of 8746 genomes from 33 African countries and two overseas territories. We show that the epidemics in most countries were initiated by importations predominantly from Europe, which diminished after the early introduction of international travel restrictions. As the pandemic progressed, ongoing transmission in many countries and increasing mobility led to the emergence and spread within the continent of many variants of concern and interest, such as B.1.351, B.1.525, A.23.1, and C.1.1. Although distorted by low sampling numbers and blind spots, the findings highlight that Africa must not be left behind in the global pandemic response, otherwise it could become a source for new variants

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance.

Investment in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing in Africa over the past year has led to a major increase in the number of sequences that have been generated and used to track the pandemic on the continent, a number that now exceeds 100,000 genomes. Our results show an increase in the number of African countries that are able to sequence domestically and highlight that local sequencing enables faster turnaround times and more-regular routine surveillance. Despite limitations of low testing proportions, findings from this genomic surveillance study underscore the heterogeneous nature of the pandemic and illuminate the distinct dispersal dynamics of variants of concern-particularly Alpha, Beta, Delta, and Omicron-on the continent. Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve while the continent faces many emerging and reemerging infectious disease threats. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Herstellung von CdTe-Dünnschichtsolarzellen bei reduzierten Abscheidetemperaturen

CdTe ist ein sehr aussichtsreiches Absorbermaterial für Dünnschichtsolarzellen. Mit CdTe-Solarzellen wurden bereits Wirkungsgrade bis zu 17,3% erzielt. Die CdS und CdTe Schichten für diese Solarzellen können mit den verschiedensten Abscheidetechniken, wie Sputtern, Chemische Badabscheidung (CVD), Druckverfahren, Hochvakuumverdampfen (HVE) und Close Space Sublimation (CSS) hergestellt werden. Hohe Durchsätze machen CSS zu einer attraktiven Methode für die industrielle Großproduktion. Um mit CdTe-Dünnschichtsolarzellen hohe Wirkungsgrade erzielen zu können, müssen kleine Löcher in den Halbleiterschichten, sogenannte „Pinholes“ , wie auch Rekombinationsverluste an den Grenzflächen vermieden werden. Die Grenzfläche von CdTe und dem transparenten Frontkontaktmaterial (TCO) weist eine sehr hohe Dichte an Grenzflächendefekten auf. Um diese Grenzfläche zu vermeiden, wird eine geschlossene CdS-Schicht zwischen dem Fronkontakt und der CdTe-Schicht benötigt. Da CdS jedoch Licht mit Wellenlängen unter 500 nm absorbiert, muss die CdS-Schicht möglichst dünn sein, um Absorptionsverluste zu minimieren. Das Wachstum der mit CSS abgeschiedenen CdS-Schichten wurde daher systematisch, im Hinblick auf den Einfluss der Prozessparameter untersucht. Dafür wurden die Abscheiderate und Substrattemperatur variiert und die CdS-Schichten mit Photoelektronenspektroskopie (XPS/UPS), Röntgenbeugung (XRD), Rasterelektronenspektroskopie (REM), Rasterkraftmikroskopie(AFM) und Optischer Transmission charakterisiert. Die REM, AFM und XRD-Untersuchungen zeigen, dass die Morphologie der Schichten hauptsächlich durch die Abscheiderate beeinflusst wird. Erste Experimente weisen zudem darauf hin, dass sich die Verwendung einer hohen Abscheiderate bei der Herstellung der CdS-Schicht positiv auf die Leerlaufspannung der Solarzelle auswirkt. Neben fluordotiertem Zinnoxid (FTO) wurde auch aluminiumdotiertes Zinkoxid (AZO) als Substratmaterial für die CdS-Abscheidung verwendet. Die Vorzugsorientierung der CdS-Kristalle, Korngröße sowie die Oberflächenrauigkeit der CdS-Schichten wird dabei stark von der Wahl des Substrat-Materials beeinflusst. Auch für die Herstellung der CdTe-Schicht, ist CSS eine attraktive Methode. Um damit Wirkungsgrade über 10% zu erzielen, wurden bisher Substrattemperaturen über 450 °C benötigt. Durch eine Verringerung der Substrattemperatur können jedoch die Produktionskosten reduziert und die Verwendung von weniger temperaturstabilen Frontkontaktmaterialien wie AZO ermöglicht werden. In dieser Arbeit wird ein Tieftemperatur-CSS-Prozess zur Abscheidung der CdTe-Schicht eingeführt mit dem hoch effiziente Solarzellen realisiert werden können. Die CdTe-Schicht wurde dabei mit einer Substrattemperatur von ≤ 340°C abgeschieden, was deutlich unter der üblicherweise verwendeten Temperatur (> 500°C) liegt. Die CdTe-Schichten wurden mit einem CdCl2-Aktivierungsschritt nachbehandelt. Dabei wurden unterschiedliche optimale Aktivierungstemperaturen und Zeiten für Hochtemperaturzellen (Tsub = 520°C) und Tieftemperaturzellen (Tsub ≤ 340°C) ermittelt. Die Auswirkungen des Aktivierungsschritts auf die Morphologie der Schichten wurden mittels XRD, AFM, REM-Aufsichten und REM-Querschnitten untersucht. Dabei wird Kornwachstum, eine starke Rekristallisation sowie eine Verringerung der Konzentration an planaren Defekten und der Porosität an den Korngrenzen insbesondere für Tieftemperatur-CdTe-Schichten beobachtet. Die Oberfläche der Tieftemperatur-CdTe-Schichten ist dabei auch nach der Aktivierung noch deutlich glatter als die der Hochtemperatur-Schichten. Es sollte also mit dem Tieftemperatur-Prozess möglich sein, dünnere CdTe-Schichten zu verwenden ohne Pinholes und Kurzschlüsse zu riskieren. Mit dem eingeführten Tieftemperatur-CdTe-Prozess konnten Wirkungsgrade bis zu 10,9 % mit kupferfreiem Rückkontakt und 12,0 % mit kupferhaltigem Rückkontakt erzielt werden. Dieser Prozess ist somit konkurrenzfähig zu anderen Prozessen, die eine höhere Temperatur oder geringeren Durchsatz erfordern. Zusätzlich werden erste Ergebnisse mit Tieftemperatur-Solarzellen auf AZO-Frontkontakten gezeigt. Die geringe chemische Stabilität von AZO verursacht während des Aktivierungs- und Ätzschrittes leider einige Schwierigkeiten, welche das Erzielen hoher Wirkungsgrade verhindert. Hier wird noch eine weitergehende Entwicklung im Hinblick auf die Rückkontaktbildung und die Verwendung von schützenden Pufferschichten für diese Frontkontakte benötigt

12% efficient CdTe/CdS thin film solar cells deposited by low-temperature close space sublimation

We report 12% efficient CdS/CdTe thin film solar cells prepared by low temperature close space sublimation (CSS). Both semiconductor films, CdS and CdTe, were deposited by high vacuum CSS in superstrate configuration on glass substrates with fluorine doped tin oxide (FTO) front contact. The CdTe deposition was carried out at a substrate temperature (Tsub) of 340° C, which is much lower than that used in conventional processes (&#62;500 ° C). The CdTe films were treated with the usual CdCl 2 activation process. Different optimal annealing times and temperatures were found for low-temperature cells (Tsub 340°C) compared to high-temperature cells (Tsub = 520°C). The influence of the activation step on the morphology of high-temperature and low-temperature CdTe is determined by XRD, AFM, SEM top views, and SEM cross-sections. Grain growth, strong recrystallization, and a reduction of planar defects during the activation step are observed, especially for low-temperature CdTe. Further, the influence of CdS deposition parameters on the solar cell performance is investigated by using three different sets of parameters with different deposition rates and substrate temperatures for the CdS preparation. Efficiencies about 10.9% with a copper-free back contact and 12.0% with a copper-containing back contact were achieved using the low temperature CdTe process

12% efficient CdTe/CdS thin film solar cells deposited by low-temperature close space sublimation

We report 12% efficient CdS/CdTe thin film solar cells prepared by low temperature close space sublimation (CSS). Both semiconductor films, CdS and CdTe, were deposited by high vacuum CSS in superstrate configuration on glass substrates with fluorine doped tin oxide (FTO) front contact. The CdTe deposition was carried out at a substrate temperature (Tsub) of 340° C, which is much lower than that used in conventional processes (>500° C). The CdTe films were treated with the usual CdCl2 activation process. Different optimal annealing times and temperatures were found for low-temperature cells (Tsub 340° C) compared to high-temperature cells (Tsub ¼ 520° C). The influence of the activation step on the morphology of high-temperature and low-temperature CdTe is determined by XRD, AFM, SEM top views, and SEM cross-sections. Grain growth, strong recrystallization, and a reduction of planar defects during the activation step are observed, especially for low-temperature CdTe. Further, the influence of CdS deposition parameters on the solar cell performance is investigated by using three different sets of parameters with different deposition rates and substrate temperatures for the CdS preparation. Efficiencies about 10.9% with a copper-free back contact and 12.0% with a copper-containing back contact were achieved using the low temperature CdTe process