Boosting Gas-Phase TiO2 Photocatalysis with Weak Electric Field Strengths of Volt/Centimeter.

Among semiconductor nanomaterials, titanium dioxide is at the forefront of heterogeneous photocatalysis, but its catalytic activity greatly suffers from the loss of photoexcited charge carriers through deleterious recombination processes. Here, we investigate the impact of an external electric field (EEF) applied to conventional P25 TiO2 nanopowder with or without Au nanoparticles (NPs) to circumvent this issue. The study of two redox reactions in the gas phase, water splitting and toluene degradation, reveals an enhancement of the photocatalytic activity with rather modest electric fields of a few volt/centimeters only. Such an improvement arises from the electric-field-induced quenching of the green emission in anatase, allowing the photoexcited charge carriers to be transferred to the adsorbed reactants instead of pointless radiative recombinations. Applying an EEF across a trap-rich metal oxide material, such as TiO2, which, when impregnated with Au NPs, leads, respectively, to 12- and 6-fold enhancements in the production of hydrogen and the oxidation of toluene for an electric field of 8 V/cm, without any electrolysis, is a simple and elegant strategy to meet higher photocatalytic efficiencies.

Mortality-related risk factors of inpatients with diabetes and COVID-19: A multicenter retrospective study in Belgium.

BACKGROUND AND AIMS: We describe mortality-related risk factors of inpatients with diabetes and coronavirus disease 2019 (COVID-19) in Belgium. METHODS: We conducted a multicenter retrospective study from March to May, 2020, in 8 Belgian centers. Data on admission of patients with diabetes and COVID-19 were collected. Survivors were compared to non-survivors to identify prognostic risk factors for in-hospital death using multivariate analysis in both the total population and in the subgroup of patients admitted in the intensive care unit (ICU). RESULTS: The study included 375 patients. The mortality rate was 26.4% (99/375) in the total population and 40% (27/67) in the ICU. Multivariate analysis identified older age (HR 1.05 [CI 1.03-1.07], P<0.0001) and male gender (HR 2.01 [1.31-3.07], P=0.0013) as main independent risk factors for in-hospital death in the total population. Metformin (HR 0.51 [0.34-0.78], P=0.0018) and renin-angiotensin-aldosterone system blockers (HR 0.56 [0.36-0.86], P=0.0088) use before admission were independent protective factors. In the ICU, chronic kidney disease (CKD) was identified as an independent risk factor for death (HR 4.96 [2.14-11.5], P<0.001). CONCLUSION: In-hospital mortality due to the first wave of COVID-19 pandemic in Belgium was high in patients with diabetes. We found that advanced age and male gender were independent risk factors for in-hospital death. We also showed that metformin use before admission was associated with a significant reduction of COVID-19-related in-hospital mortality. Finally, we showed that CKD is a COVID-19-related mortality risk factor in patients with diabetes admitted in the ICU.

Spontaneous Volumetric Tumor Regression During Wait-and-Scan Management of 952 Sporadic Vestibular Schwannomas.

OBJECTIVE: Spontaneous tumor shrinkage during wait-and-scan management of sporadic vestibular schwannoma is generally considered an uncommon phenomenon. However, most data informing this understanding stem from single-slice linear tumor measurements taken in the axial imaging plane. The objective of the current work was to characterize the regression capacity of sporadic vestibular schwannomas using volumetric tumor measurements. STUDY DESIGN: Retrospective cohort study using slice-by-slice, three-dimensional volumetric tumor measurements. SETTING: Three tertiary referral centers. PATIENTS: Patients with sporadic vestibular schwannoma. INTERVENTIONS: Wait-and-scan. MAIN OUTCOME MEASURES: Regression-free survival rates with regression defined as a decrease of at least 20% of the tumor volume. RESULTS: Among 952 patients undergoing a total of 3,505 magnetic resonance imaging studies during observation, 123 experienced volumetric tumor regression after diagnosis at a median of 1.2 years (interquartile range, 0.6-2.9 yr). Volumetric regression-free survival rates (95% confidence interval; number still at risk) at 1, 3, and 5 years after diagnosis were 94% (92-95%; 662), 86% (83-89%; 275), and 78% (73-82%; 132), respectively. Among 405 patients who demonstrated an initial period of tumor growth but continued wait-and-scan management, 48 experienced volumetric regression at a median of 1.2 years (interquartile range, 0.8-2.6 yr) after initial growth. Volumetric regression-free survival rates at 1, 3, and 5 years after initial growth were 94% (92-97%; 260), 84% (79-89%; 99), and 75% (67-83%; 43), respectively. Ultimately, only 82 of the 952 patients studied showed exclusively volumetric tumor regression (i.e., without any periods of tumor growth) by the time of last follow-up. CONCLUSION: Spontaneous volumetric tumor shrinkage during wait-and-scan management occurs more frequently than suggested by previous studies using linear tumor measurements and can even occur after previous episodes of documented tumor growth. These data further highlight the dynamic nature of vestibular schwannoma growth. To this end, the application of natural history data to patient management requires a nuanced approach that parallels the complex tumor behavior of vestibular schwannoma.

Recent climate change has driven divergent hydrological shifts in high-latitude peatlands.

High-latitude peatlands are changing rapidly in response to climate change, including permafrost thaw. Here, we reconstruct hydrological conditions since the seventeenth century using testate amoeba data from 103 high-latitude peat archives. We show that 54% of the peatlands have been drying and 32% have been wetting over this period, illustrating the complex ecohydrological dynamics of high latitude peatlands and their highly uncertain responses to a warming climate.

Unmet Healthcare Needs among College Students during the COVID-19 Pandemic: Implications for System-Wide and Structural Changes for Service Delivery.

BACKGROUND: During the COVID-19 pandemic, college students faced health disparities in addition to a negative burden on academic performance; however, little is reported in the literature regarding healthcare utilization. METHODS: A cross-sectional survey was conducted among consenting college student participants aged 18 or older from a Hispanic-serving institution. Descriptive and bivariate statistics were used to analyze demographic characteristics and the types of healthcare services needed by such characteristics. Logistic regression was used to adjust for noted sex differences in associations between reporting limited healthcare services and types of healthcare services. RESULTS: The study population of 223 participants was mostly Hispanic/Latino (65%) and female (73%). Of the population, 11% reported they could not obtain needed healthcare services, with time being reported as the most common reason. Significant associations were found between seeking general healthcare services/routine screening, seeking mental health services, and seeking sexual health services with reporting limited healthcare services, with sex-adjusted odds ratios and 95% confidence intervals of 1.90 (95% CI: 1.08, 3.36), 3.21 (95% CI: 1.44, 4.15), and 2.58 (95% CI: 1.05, 6.35), respectively. CONCLUSIONS: Availability and inability to obtain health services may exacerbate college student health disparities. Targeted interventions are needed in the population to mitigate the potential burdens of unmet healthcare needs, particularly among minority college students.

The testate amoebae of New Zealand: A checklist, identification key and assessment of biogeographic patterns.

New Zealand (NZ) is a well-known hotspot of biodiversity and endemism for macroscopic organisms, but its microbial diversity is comparatively poorly documented. We assembled all records on NZ testate amoebae published since the early 20th century and present a comprehensive taxonomic checklist for NZ. Testate amoebae are reported from six major habitat types across both the North and South Islands of NZ, but the sampling effort is ecologically and geographically biased in favour of wetlands and the South Island. As a result, 93% of all 128 morphotypes recorded in NZ occur in wetlands, 28% are restricted to the South Island, and diversity is greater at higher latitudes. Around 50% of morphotypes have a broad latitudinal distribution across the NZ mainland, whereas 15% have narrow latitudinal ranges. Future research should aim to broaden the geographical and ecological ranges. We predict that our list of NZ testate amoebae will expand substantially with future work, and that the latitudinal diversity gradient will be inverted. We also introduce an interactive, fully illustrated, online Lucid key for the rapid identification of NZ testate amoebae. As many morphospecies are cosmopolitan, this key provides a useful tool for testate amoebae identification in other parts of the world.

Is intermittent antiretroviral therapy a satisfactory strategy for the management of patients living with HIV?

Many innovations, such as long-acting agents, new delivery modalities (injectable and nanoparticles), and novel paradigms (immunotherapy or dual therapy), have been introduced to facilitate the administration of antiretroviral treatment (ART) to patients infected with HIV and improve their adherence and quality of life without altering the drugs' effectiveness. Studies have investigated the use of intermittent treatment, especially weekends-off ART in HIV-suppressed patients. In this review, we analyzed data concerning intermittent ART to help determine if this strategy is reasonable for the management of patients living with HIV. The results of early studies, in 2007-2015, were encouraging, but the studies were flawed because of the small number of patients included, the absence of a control arm, and random designs with variable patterns of ART administration. From 2016, studies have included more patients, and some are prospective, randomized controlled studies. While non-nucleoside reverse transcriptase inhibitors have been most studied, treatment with integrase inhibitors also has been reported, with the findings that viral resistance did not appear when treatment failed with dolutegravir but not with raltegravir. The most recent study, QUATUOR, found that a 4-day on, 3-day off pattern was non-inferior to the continuous pattern (7 days on). Better-quality studies with long-term follow-up (96 weeks or more) are needed to determine the validity of intermittent treatment and the optimal regimens and monitoring to be used in the management of viro-logically suppressed patients living with HIV.

A case of antisynthetase syndrome with chilblains-like lesions and microangiopathy.

We present the case of a 50-year-old woman with febrile myalgia, chilblains-like lesions, and cough. Antinuclear antibodies and anti-PL-12 antisynthetase autoantibodies were found in complementary examinations. Interstitial lung disease was found on chest computed tomography. Nailfold capillaroscopy showed microangiopathic lesions. Antisynthetase syndrome is a recently described entity in inflammatory myopathies, with specific clinical criteria. Interstitial lung disease is very common, especially in anti-PL-12 associated antisynthetase syndrome. Raynaud's phenomenon is another well-defined criterion. However, microangiopathic damage is probably underestimated and the role of nailfold capillaroscopy in the diagnosis has not been established yet.

COVID-19 Outbreak in a Hemodialysis Center: A Retrospective Monocentric Case Series.

BACKGROUND: The rapid worldwide spread of COVID-19 has posed a serious threat to patients treated with kidney replacement therapy (KRT). Moreover, the impact of the disease on hemodialysis centers, the patients, and the health care workers is still not completely understood. OBJECTIVE: We present the analysis of a COVID-19 outbreak in a hemodialysis center in Belgium and report the incidence, clinical course, and outcome of the disease. DESIGN: A retrospective cross-sectional cohort study. SETTING: A hemodialysis center during the COVID-19 outbreak. PATIENTS: A total of 62 patients on maintenance hemodialysis at a tertiary care center in Belgium attended by 26 health care workers. MEASUREMENTS: Baseline patients' characteristics were retrieved. The incidence, clinical course, and outcome were reported. The differences between COVID-19 survivors and nonsurvivors were assessed along with the differences between COVID-19-hospitalized and nonhospitalized patients. The incidence of the disease and outcome of health care workers were also reported. METHODS: Proportions for categorical variables were compared using the Fisher exact test and χ2. The Mann-Whitney rank sum test was used to compare continuous variables. Univariate analysis and a binomial logistic regression were used to explore variables as predictors of death. RESULTS: Between March 6 and April 14, 2020, 40 of 62 (65%) patients tested positive for severe acute respiratory syndrome beta coronavirus 2 (SARS-CoV-2) along with 18 of 26 (69%) health care professionals. Twenty-five (63%) of the infected patients were hospitalized with a median time for hospitalization-to-discharge of 8 (interquartile range [IQR] = 4-12) days. Eleven (28%) COVID-19-related deaths were recorded with a median time for onset of symptoms-to-death of 9 (IQR = 5-14) days. Lymphocytopenia was prevalent among the cohort and was found in 9 of 11 (82%) reported deaths (P = .4). There was no influence of the use of angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers on COVID-19-related deaths (P = .3). Advanced age, cardiovascular disease (CVD), and obstructive sleep apnea syndrome were all found to be significantly related to death. Of the 18 infected health care professionals, 13 (72%) were symptomatic and 2 (11%) were hospitalized. There was no reported death among the health care workers. LIMITATIONS: Limited follow-up time compared with the course of the disease along with a small sample size. CONCLUSIONS: Patients treated with KRT show a high mortality rate secondary to COVID-19. CVD and age are shown to impact survival. Proactive measures must be taken to prevent the spread of the virus in such facilities. TRIAL REGISTRATION: Not applicable as this is a retrospective study.

Quantifying the effect of testate amoeba decomposition on peat-based water-table reconstructions.

Testate amoebae are a widely-used tool for palaeohydrological reconstruction from peatlands. However, it has been observed that weak idiosomic siliceous tests (WISTs) are common in uppermost peats, but very rarely found as subfossils deeper in the peat profile. This taphonomic problem has been noted widely and it has been established that WISTs disaggregate and/or dissolve in the low pH condition of ombrotrophic peatlands. Here we investigate the effect of this taphonomic problem on water-table reconstructions from thirty European peatlands through the comparison of reconstructions based on all taxa and those with WISTs removed. In almost all cases the decomposition of WISTs does not introduce discernible bias to peatland water-table reconstructions. However, some discrepancy is apparent when large abundances of Corythion-Trinema type are present (9-12 cm deviation with 50-60% abundance of this particular taxon). We recommend that WISTs should be removed before carrying out water-table reconstructions, and that the minimum count of testate amoebae per sample should exclude WISTs to ensure the development of robust reconstructions.

Decreased carbon accumulation feedback driven by climate-induced drying of two southern boreal bogs over recent centuries.

Northern boreal peatlands are important ecosystems in modulating global biogeochemical cycles, yet their biological communities and related carbon dynamics are highly sensitive to changes in climate. Despite this, the strength and recent direction of these feedbacks are still unclear. The response of boreal peatlands to climate warming has received relatively little attention compared with other northern peatland types, despite forming a large northern hemisphere-wide ecosystem. Here, we studied the response of two ombrotrophic boreal peatlands to climate variability over the last c. 200 years for which local meteorological data are available. We used remains from plants and testate amoebae to study historical changes in peatland biological communities. These data were supplemented by peat property (bulk density, carbon and nitrogen content), 14 C, 210 Pb and 137 Cs analyses and were used to infer changes in peatland hydrology and carbon dynamics. In total, six peat cores, three per study site, were studied that represent different microhabitats: low hummock (LH), high lawn and low lawn. The data show a consistent drying trend over recent centuries, represented mainly as a change from wet habitat Sphagnum spp. to dry habitat S. fuscum. Summer temperature and precipitation appeared to be important drivers shaping peatland community and surface moisture conditions. Data from the driest microhabitat studied, LH, revealed a clear and strong negative linear correlation (R2  = .5031; p < .001) between carbon accumulation rate and peat surface moisture conditions: under dry conditions, less carbon was accumulated. This suggests that at the dry end of the moisture gradient, availability of water regulates carbon accumulation. It can be further linked to the decreased abundance of mixotrophic testate amoebae under drier conditions (R2  = .4207; p < .001). Our study implies that if effective precipitation decreases in the future, the carbon uptake capacity of boreal bogs may be threatened.

Efficient Singlet Oxygen Photogeneration by Zinc Porphyrin Dimers upon One- and Two-Photon Excitation.

The development of photodynamic therapy (PDT) at depth requires photosensitizers which have both sufficient quantum yield for singlet oxygen generation and strong two-photon absorption. Here, we show that this can be achieved by conjugated linkage of zinc porphyrins to make dimers. We determined the quantum yield of generation of 1O2 , ϕΔ, by measuring emission at 1270 nm using a near-infrared streak camera and found it to increase from 15% for a single porphyrin unit to 27-47% for the dimers with a conjugated linker. Then, we recorded the spectra of two-photon absorption cross section, σ2, by a focus-tunable Z-scan method, which allows for nondestructive investigation of light-sensitive materials. We observed a strong enhancement of the two-photon absorption coefficient in the dimers, especially those with an alkyne linker. These results lead to an excellent figure of merit for two-photon production of singlet oxygen (expressed by the product σ2 × Ï•Δ) in the porphyrin dimers, of around 3700 GM, which is very promising for applications involving treatment of deep tumors by PDT.

Periosteal Flap in Cochlear Implantation, How I Do It?

This clinical report describes and evaluates a novel periosteal flap design. This technique was applied in 26 patients who underwent cochlear implantation surgery at two tertiary referral centers. No complications were observed during or after the surgery. Additionally, there was no evidence of device migration, wound infection, wound hematoma, or delayed wound healing. Notably, the mastoid emissary vein was intact in all cases. In conclusion, this modified anterior-based periosteal flap is a safe procedure and is aimed at avoiding mastoid emissary vein bleeding and allowing complete repositioning of the periosteum over the implanted device.

Ultrafast Through-Space Electronic Energy Transfer in Molecular Dyads Built around Dynamic Spacer Units.

A pair of complementary molecular dyads have been synthesized around a 1,2-diaminocyclohexyl spacer that itself undergoes ring inversion. Despite these conformational exchange processes, the donor and acceptor occupy quite restricted spatial regions, and they are not interchangeable. The donor and acceptor pair comprise disparate boron dipyrromethene dyes selected to display favorable electronic energy transfer (EET). Steady-state emission spectroscopy confirms that through-space EET from donor to acceptor is almost quantitative, aided by the relatively short separations. Ultrafast time-resolved fluorescence spectroscopy has allowed determination of the rates of EET for both dyads. Surprisingly, in view of the close proximity of donor and acceptor (center-to-center separations less than 20 Å), the EET dynamics are well-accounted for in terms of the computed molecular conformations and conventional Förster theory. One dyad appears as a single family of conformations, but EET for the second dyad corresponds to dual-exponential kinetics. In this latter case, an intramolecular hydrogen bond helps stabilize an open geometry, wherein EET is relatively slow.

Ecosystem state shifts during long-term development of an Amazonian peatland.

The most carbon (C)-dense ecosystems of Amazonia are areas characterized by the presence of peatlands. However, Amazonian peatland ecosystems are poorly understood and are threatened by human activities. Here, we present an investigation into long-term ecohydrological controls on C accumulation in an Amazonian peat dome. This site is the oldest peatland yet discovered in Amazonia (peat initiation ca. 8.9 ka BP), and developed in three stages: (i) peat initiated in an abandoned river channel with open water and aquatic plants; (ii) inundated forest swamp; and (iii) raised peat dome (since ca. 3.9 ka BP). Local burning occurred at least three times in the past 4,500 years. Two phases of particularly rapid C accumulation (ca. 6.6-6.1 and ca. 4.9-3.9 ka BP), potentially resulting from increased net primary productivity, were seemingly driven by drier conditions associated with widespread drought events. The association of drought phases with major ecosystem state shifts (open water wetland-forest swamp-peat dome) suggests a potential climatic control on the developmental trajectory of this tropical peatland. A third drought phase centred on ca. 1.8-1.1 ka BP led to markedly reduced C accumulation and potentially a hiatus during the peat dome stage. Our results suggest that future droughts may lead to phases of rapid C accumulation in some inundated tropical peat swamps, although this can lead ultimately to a shift to ombrotrophy and a subsequent return to slower C accumulation. Conversely, in ombrotrophic peat domes, droughts may lead to reduced C accumulation or even net loss of peat. Increased surface wetness at our site in recent decades may reflect a shift towards a wetter climate in western Amazonia. Amazonian peatlands represent important carbon stores and habitats, and are important archives of past climatic and ecological information. They should form key foci for conservation efforts.

Size dependence of efficiency of PbS quantum dots in NiO-based dye sensitised solar cells and mechanistic charge transfer investigation.

Quantum dots (QDs) are very attractive materials for solar cells due to their high absorption coefficients, size dependence and easy tunability of their optical and electronic properties due to quantum confinement. Particularly interesting are PbS QDs owing to their broad spectral absorption until long wavelengths, their easy processability and low cost. Here, we used control of the PbS QD size to understand charge transfer processes at the interfaces of a NiO semiconductor and explain the optimal QD size in photovoltaic devices. Towards this goal, we have synthesized a series of PbS QDs with different diameters (2.8 nm to 4 nm) and investigated charge transfer dynamics by time resolved spectroscopy and their ability to act as sensitizers in nanocrystalline NiO based solar cells using the cobalt tris(4,4'-ditert-butyl-2,2'-bipyridine) complex as a redox mediator. We found that PbS QDs with an average diameter of 3.0 nm show the highest performance in terms of efficient charge transfer and light harvesting efficiency. Our study showed that hole injection from the PbS QDs to the NiO valence band (VB) is an efficient process even with low injection driving force (-0.3 eV) and occurs in 6-10 ns. Furthermore we found that direct electrolyte reduction (photoinduced electron transfer to the cobalt redox mediator) also occurs in parallel to the hole injection with a rate constant of similar magnitude (10-20 ns). In spite of its large driving force, the rate constant of the oxidative quenching of PbS by Co(iii) diminishes more steeply than hole injection on NiO when the diameter of PbS increases. This is understood as the consequence of increasing the trap states that limit electron shift. We believe that our detailed findings will advance the future design of QD sensitized photocathodes.

Taxonomic Implications of Morphological Complexity Within the Testate Amoeba Genus Corythion from the Antarctic Peninsula.

Precise and sufficiently detailed morphological taxonomy is vital in biology, for example in the accurate interpretation of ecological and palaeoecological datasets, especially in polar regions, where biodiversity is poor. Testate amoebae on the Antarctic Peninsula (AP) are well-documented and variations in their population size have recently been interpreted as a proxy for microbial productivity changes in response to recent regional climate change. AP testate amoeba assemblages are dominated by a small number of globally ubiquitous taxa. We examine morphological variation in Corythion spp. across the AP, finding clear evidence supporting the presence of two morphospecies. Corythion constricta (Certes 1889) was identified on the AP for the first time and has potentially been previously misidentified. Furthermore, a southerly trend of decreasing average test size in Corythion dubium (Taránek 1881) along the AP suggests adaptive polymorphism, although the precise drivers of this remain unclear, with analysis hindered by limited environmental data. Further work into morphological variation in Corythion is needed elsewhere, alongside molecular analyses, to evaluate the potential for (pseudo)cryptic diversity within the genus. We advocate a parsimonious taxonomical approach that recognises genetic diversity but also examines and develops accurate morphological divisions and descriptions suitable for light microscopy-based ecological and palaeoecological studies.

Kinetics of Light-Induced Intramolecular Energy Transfer in Different Conformational States of NADH.

When bound to a protein, the coenzyme NAD+/NADH typically exists in an extended conformation, while in aqueous solutions it can be characterized by an equilibrium of folded and unfolded structures. It was recognized long ago that in the folded conformation light absorption at the adenine ring initiates an effective energy transfer (ET) toward the nicotinamide group, but the mechanism of this process is still unexplored. Here we apply ultrafast transient absorption measurements on NADH combined with compartmental model analysis for following the kinetics of the ET. We find that the actual ET is extremely rapid (∼70 fs). The high rate can be well described by a Förster-type mechanism, promoted by both the special photophysical properties of adenine and the subnanometer inter-ring distance. The rapid ET creates a vibrationally hot excited state on nicotinamide, the vibrational and electronic relaxation of which is characterized by 1.7 and 650 ps, respectively.