Low Contribution Research Articles

Gender disparity in Canadian Institutes of Health Research funding within neurology

BackgroundDespite efforts to advance equity, diversity and inclusion, women face gender-based barriers in research, including in neurology. Compared with men, women are less likely to hold leadership positions and be...

PERHITUNGAN AWAL IMBUHAN AIRTANAH ALAMI DAERAH ALIRAN SUNGAI CIKAPUNDUNG-GANDOK (KAJIAN PERBANDINGAN)

Groundwater recharge is a crucial factor in determining the permissible groundwater extraction within a watershed. In the Cikapundung watershed, the contribution of groundwater to raw water supply has been continuously declining, prompting a shift from groundwater to surface water usage. This study aims to quantify the groundwater recharge volume and recharge coefficient for each geological formation within the Cikapundung-Gandok watershed, covering an area of 90.4 km², and to compare the results with previous studies. The analysis estimates recharge volumes based on rainfall data from 8 stations around the Cikapundung-Gandok watershed from 2010 to 2019, geological formation data, and alternative recharge coefficients. The difference in recharge volume from previous studies is 393,348 m³/year or 1%. Two formations, Qvu and Qyu, which were not identified in earlier studies, supplement the existing geological dataset. The selected recharge volume for the Cikapundung-Gandok watershed is 33,232,004 m³/year or 1.05 m³/s, with the lowest contribution from the Lava formation (Qyl) at 1,364,504 m³/year or 0.04 m³/s and the highest from the Old Volcanic Product (Qvu) at 14,072,243 m³/year or 0.45 m³/s. The tentative recharge coefficients for each rock formation are as follows: Colluvium (Qc) 30%; Unweathered Old Volcanic Product (Qvu) 20%; Sand Tuff (Qyd) 10%; Lava (Qyl) 25%; Pumiceous Tuff (Qyt) 20%; and Young Volcanic Product (Qyu) 20%. The groundwater recharge data obtained can be used to set groundwater extraction limits and to plan for groundwater management using a conservative approach to ensure long-term sustainability.Keywords: groundwater recharge, recharge coefficient, geological formation, groundwater exploitation, Cikapundung-Gandok Watershed

Different right ventricular mechanics in atrial and ventricular secondary tricuspid regurgitation and their prognostic role. A multicentric three-dimensional echocardiography study

Abstract Background/Introduction Secondary tricuspid regurgitation (STR) can develop from markedly different etiologies. Both progressive dilation and dysfunction of the right atrium (atrial phenotype, ASTR), and adverse right ventricular (RV) remodeling (ventricular phenotype, VSTR) may result in STR. RV function is a major determinant of outcome in patients with STR. However, data about how RV function adapts to ASTR and VSTR are scarce, and the prognostic implications of RV mechanics in ASTR and VSTR remain to be clarified. Purpose Accordingly, we aimed to investigate the RV mechanical patterns in ASTR and VSTR and to examine their prognostic role using three-dimensional (3D) echocardiography. Methods We enrolled 192 patients with STR (60% women) who underwent clinically indicated transthoracic echocardiography in a multicentric prospective observational study. The primary outcome was defined as a composite of heart failure hospitalization or cardiac death. STR etiology was assessed based on the TVARC criteria (ventricular STR n=134, atrial STR n=58). STR severity was categorized using STR effective regurgitant orifice area according to current guidelines. We assessed RV function by measuring the tricuspid annular plane systolic excursion (TAPSE) by M-mode echocardiography and RV ejection fraction (EF) by 3D echocardiography. In addition, we imported the 3D RV meshes into the ReVISION software package (Argus Cognitive, Inc, Lebanon, USA) to quantify the relative contribution of the longitudinal (LEFi), radial (REFi), and anteroposterior motion components (AEFi) to total RV EF. Results ASTR and VSTR patients had comparable TAPSE (17±5 mm vs. 18±5 mm, p=0.10), while RV EF was significantly higher in ASTR (54±7% vs. 47±10% p<0.001). Although LEFi (0.37±0.08 vs. 0.38±0.10, p=0.95) and AEFi (0.45±0.08 vs. 0.44±0.11, p=0.53) were comparable between ASTR and VSTR, REFi was significantly lower in VSTR (0.52±0.09 vs. 0.47±0.12, p<0.01). RF EF was comparable among STR severity grades (mild vs. moderate vs. severe: 50±11 vs. 49±9 vs. 50±10%, respectively, p=0.85). Conversely, LEFi was significantly higher in mild and moderate STR vs severe STR (0.39±0.08 vs. 0.39±0.09 vs. 0.35±0.10, respectively, p=0.04). Using multivariable Cox regression based on variables significant in the univariate analysis, REFi was a significant independent predictor of outcome in the entire cohort (hazard ratio: 0.978 [CI, 0.959-0.999], p= 0.037). Conclusions Using 3D echocardiographic assessment, ASTR and VSTR patients demonstrated significant differences in the RV mechanical pattern, with a lower contribution of the radial contraction in the case of ventricular STR etiology. While RV EF was comparable between STR severity grades, the relative importance of the longitudinal motion significantly differed. Notably, the relative contribution of radial motion to RV function demonstrated independent prognostic value in patients with STR.RV mechanics in STR severity stages

Does public pension promote or inhibit enterprise total factor productivity? Evidence from China

The relationship between pension contribution rates and productivity remains a significant topic of discussion. This study utilizes micro-level data to examine the interaction between statutory pension contribution rates, actual contribution rates, and the total factor productivity (TFP) of enterprises. The findings indicate that the reduction in the Basic Old-age Insurance contribution rate resulted in a 0.985 percentage point decline in actual contribution rates and 4.3 percentage point decline in TFP. Pension insurance contribution collection by tax authorities results in the highest collection intensity and lowest elasticity coefficient, while agency collection exhibits greater variability. Additionally, actual pension contribution rates and TFP exhibit an inverted U-shaped relationship. When the public pension contribution rate is either too high or too low, it may hinder improvements in enterprise production efficiency. Instead, there exists an optimal range of contribution rates where public pensions can foster a positive interaction between R&D investment, capital-skill substitution, and employee incentives. State-owned, labor-intensive, and low-wage firms experience sharper productivity declines beyond a lower optimal contribution rate, indicating that these firms reach peak productivity at lower contribution levels.

Effect of alternative oxidase (AOX) expression on mouse cerebral mitochondria bioenergetics

Alternative oxidase (AOX) is an enzyme that transfers electrons from reduced quinone directly to oxygen without proton translocation. When AOX from Ciona intestinalis is xenotopically expressed in mice, it can substitute the combined electron-transferring activity of mitochondrial complexes III/IV. Here, we used brain mitochondria from AOX-expressing mice with such a chimeric respiratory chain to study respiratory control bioenergetic mechanisms.AOX expression did not compromise the function of the mammalian respiratory chain at physiological conditions, however the complex IV inhibitor cyanide only partially blocked respiration by AOX-containing mitochondria. The relative fraction of cyanide-insensitive respiration increased at lower temperatures, indicative of a temperature-controlled attenuation of mammalian respiratory enzyme activity.As AOX does not translocate protons, the mitochondrial transmembrane potential in AOX-containing mitochondria was more sensitive to cyanide during succinate oxidation than during malate/pyruvate-supported respiration. High concentrations of cyanide fully collapsed membrane potential during oxidation of either succinate or glycerol 3-phosphate, but not during malate/pyruvate-supported respiration. This confirms AOX's electroneutral redox activity and indicates differences in the proton-translocating capacity of dehydrogenases upstream of the ubiquinone pool. Our respiration data refutes previous proposals for quinone partitioning within the supercomplexes of the respiratory chain, instead supporting the concept of a single homogeneous, freely diffusing quinone pool.Respiration with either succinate or glycerol 3-phosphate promotes reverse electron transfer (RET) towards complex I. AOX expression significantly decreased RET-induced ROS generation, with the effect more pronounced at low temperatures. Inhibitor-sensitivity analysis showed that the AOX-induced decrease in H2O2 release is due to the lower contribution of complex I to net ROS production during RET.Overall, our findings provide new insights into the role of temperature as a mechanism to control respiration and highlight the utility of AOX as a genetic tool to characterize both the distinct pathways of oxygen reduction and the role of redox control in RET.

Environmental changes in the Fleuve Manche paleoriver drainage system (Western Europe) linked to North Atlantic sub-millennial climate variability across Heinrich Stadial 1: Palynological evidence from the Bay of Biscay

Marine microfossils (dinoflagellate cysts and planktonic foraminifera) and geochemical (XRF-Ti/Ca)-based climatic records from a core (MD13–3438) located off the Fleuve Manche (FM) paleo-mouth have revealed that sustained warm summer sea surface temperatures (SSTs) during sub-millennial climate changes within HS1 (∼18–14.7 ka) may have played a key role in the FM regime related to the European Ice Sheet (EIS) melting rate. In this study, we have analyzed the MD13–3438 pollen content over the HS1 at a mean resolution of ∼50 years to test whether vegetation-based air temperatures were coupled to SSTs face to this rapid climate variability. First, our results highlight two major phases of pollen sources at site MD13–3438, preventing the pollen record to be interpreted as a continuous record of the evolution of vegetation and climate occupying a single watershed across HS1. The first phase, i.e. the HS1-a interval (∼18–16.8 ka), is marked by strong occurrences of boreal pollen taxa (especially Picea-Abies). Considering their spatial distribution and the coalescence of the British and Scandinavian ice sheets into the North Sea during the Last Glacial Maximum, these taxa probably originated from the North European Plain, i.e., eastern FM tributaries (east of the Rhine River), where cool-humid conditions generally prevailed. Then, the second phase, i.e. the HS1-b interval (∼16.8–14.7 ka BP), is characterized by a deceleration of the EIS retreat and the drop of boreal pollen values at site MD13–3438 further signing a less influence of the upstream FM drainage system and thus a better characterization of pollen sources related with western FM tributaries. Superimposed to these two HS1 main phases, pollen fluctuations are concomitant with sub-millennial variability in the EIS deglaciation intensity. During the early HS1 (HS1-a), we discuss two short-term increases in the ratio between deciduous trees (Quercus-Corylus-Alnus) and herbaceous plants (Plantago-Amaranthaceae-Artemisia). These events are coeval with phases of increasing dinocyst-based SST seasonality (i.e. through summer SST amplification). We associate these events with lower contribution of the upstream FM catchment as well as, possibly, atmospheric warming and regional sea-level positive oscillations. The HS1-b is composed of three main phases that appear more influenced by the downstream FM drainage system. HS1-b1 (16.8–16.3 ka BP) corresponds to the driest and coldest conditions west of the Rhine River. HS1-b2 (16.3–15.5 ka BP) is coeval with large arrivals of iceberg from the Hudson strait in the Bay of Biscay and thus likely to a major sea-level positive oscillation associated with a phase of FM valley reworking. HS1-b3 (15.5–14.7 ka BP) corresponds to persistent arid conditions that preceded the subsequent more humid conditions recorded from 14.7 ka BP at the start of the Bölling-Alleröd.

Pollution Characterization and Source Apportionment of Volatile Organic Compounds and Their Odor-causing Species in Industrial Parks

To improve the phenomenon of the volatile organic compounds （VOCs） odor pollution nuisance in industrial parks and to promote the synergistic control of atmospheric VOCs and their odor-causing substances, based on the field observation of atmospheric VOCs in residential living areas and five different types of industrial clusters in industrial parks, we analyzed the pollution characteristics of atmospheric VOCs and their odor-causing volatile organic compounds （O-VOCs） in the residential living areas and each industrial cluster, evaluated the characteristics of the odor activity of the O-VOCs in the industrial parks, and identified the key odor-causing species and their main sources. The results showed that the mean values of atmospheric φ （TVOCs） and φ（O-VOCs） in the residential living area of the industrial park were 102.57×10-9 and 72.33×10-9, respectively. φ（TVOCs） and φ（O-VOCs） were significantly higher in the industrial clusters of basic chemical industry and pharmaceutics than in the other industrial clusters, and the sum （OAVsum） and maximum （OAVmax） of the odor activity values of these two clusters were relatively high, with a potential risk of odor nuisance. Overall, the O-VOCs species with higher odor intensity were similar in residential living areas and the five industrial clusters, and effective control of O-VOCs species such as acrolein, p-diethylbenzene, p-xylene, and 1,3-diethylbenzene is essential to mitigate or eliminate organic odor pollution. The results of the source apportionment of O-VOCs in the residential area showed that the sources of O-VOCs in the residential area were mainly influenced by natural gas chemical and pharmaceutics, and the coefficients of divergence （CDO-VOCs） between the O-VOC chemical profiles from residential areas and those from natural gas chemical and pharmaceutics were 0.31 and 0.38, respectively. Principal component analysis （PCA） also confirmed this result, with residential O-VOCs mainly originating from natural gas chemicals and pharmaceutics, followed by iron and steel manufacturing and automobile manufacturing, with the lowest contribution from the basic chemicals.

Does foreign direct investment affect domestic firms’ social security contributions?

Foreign direct investments (FDI) in developing countries are found to affect local domestic firms by introducing competition and spillover effects. This study investigates the effect of FDI on domestic firms’ social security contributions. It exploits China’s 2002 FDI liberalization and applies the difference-in-differences strategy for a causal identification. Using a Chinese firm-level dataset of the manufacturing industry, the estimates show that foreign investments have a positive effect on domestic firms’ social security contributions as a share of the wage base. The estimated effects are more pronounced in private firms, higher-wage firms, and firms facing lower contribution costs. Evidence also indicates that the increase in firms’ propensity to contribute plays an important role in explaining the overall increase in social security contribution rates. The promotion of social security compliance among domestic firms by FDI inflow suggests that market competition could be an attractive and effective approach to combating non-compliance with social insurance regulations.

Investigating the biological diversity and ecological dynamics of oceanic fishery resources in the Andaman Sea, Indian Ocean

This research paper investigates the oceanic fishery resources of the Andaman archipelago. The primary objective of this study is to gain a comprehensive understanding of the fishery and its dynamics including the environmental linkage surrounding these oceanic resources and to develop an effective strategy for sustainable exploration. Data were collected during an exploratory tuna long-line survey conducted between July 2022 and February 2023. The study documented a total of 13 species of fishes belonging to 11 genera, with tuna being the most abundant. Additionally, the study observed a significant increase in the population of pelagic stingrays, which nearly matched the number of hooked sharks (32). However, the hooking rates of sharks and bill fishes were observed to be gradually declining, resulting in a lower contribution to the overall species composition. One notable finding of the study was that site 11oN; 93oE (S4) exhibited the highest species diversity and potential. Furthermore, the aggregate hooking rates of fishes were particularly high between latitudes 11oN and 12oN. The study also analysed the seasonal distribution of each fish species and explored the correlation between environmental factors such as depth and temperature with species abundance and distribution. Statistical analysis indicates that there is no significant variation (p value = 0.20) between the environmental factors and the frequency of the species occurrence. Specifically, depth shows the highest correlation (r = 0.57) with the species distribution. In light of the diminishing hooking rate of oceanic fishery resources, the study puts forth several possible reasons and emphasizes the urgent need to implement conservation measures.

High-resolution epidemiological landscape from ~290,000 SARS-CoV-2 genomes from Denmark

Vast amounts of pathogen genomic, demographic and spatial data are transforming our understanding of SARS-CoV-2 emergence and spread. We examined the drivers of molecular evolution and spread of 291,791 SARS-CoV-2 genomes from Denmark in 2021. With a sequencing rate consistently exceeding 60%, and up to 80% of PCR-positive samples between March and November, the viral genome set is broadly whole-epidemic representative. We identify a consistent rise in viral diversity over time, with notable spikes upon the importation of novel variants (e.g., Delta and Omicron). By linking genomic data with rich individual-level demographic data from national registers, we find that individuals aged < 15 and > 75 years had a lower contribution to molecular change (i.e., branch lengths) compared to other age groups, but similar molecular evolutionary rates, suggesting a lower likelihood of introducing novel variants. Similarly, we find greater molecular change among vaccinated individuals, suggestive of immune evasion. We also observe evidence of transmission in rural areas to follow predictable diffusion processes. Conversely, urban areas are expectedly more complex due to their high mobility, emphasising the role of population structure in driving virus spread. Our analyses highlight the added value of integrating genomic data with detailed demographic and spatial information, particularly in the absence of structured infection surveys.

Saturated hydraulic conductivity (Ksat) and topographic controls on baseflow contribution in high-altitude aquifers with complex geology

Mountains in general are important sources of water resources and correspondingly, the Upper Indus Basin (UIB) in the Himalayas provides water for hundreds of millions of users. During low-flow periods, streamflow is fed by a combination of groundwater (baseflow), snow/glacier melt and recent precipitation. However, the proportion of stream baseflow generated by different sources and the factors that control these contributions remain poorly understood. In this paper, we focus on the Western Himalayan Liddar watershed (1243 km2) in the UIB and use a multi-method approach to characterize aquifers and baseflow generation in three nested catchments which represent varying geology and topography. Our multi-method approach includes geophysical surveys, slug tests, stable isotope compositions, young water fraction (Fyw) estimation and a Bayesian end member mixing model. Specifically, we hypothesize that Ksat of the subsurface plays a critical role in the contribution of groundwater to baseflow. The watershed is subdivided into three nested catchments (Limestone, hardrock and alluvium). Our results indicate that the upstream, steep, high-permeability limestone catchment has the relatively largest groundwater contribution to streamflow (63–78 %) and a low Fyw (38 %) than the other two sites. The mid-elevation hard rock catchment has a lower permeability on average but is highly variable due to fracture networks and geologic contacts, allowing a substantial groundwater contribution to streamflow (38–66 %) and a similar Fyw (36 %) to the limestone catchment. The downstream, low-slope catchment underlain by alluvium has a highly variable hydraulic conductivity and a substantially lower groundwater contribution to streamflow (26–45 %) and a higher Fyw (55 %). We find that both hydraulic conductivity and topography exert control on the magnitude of baseflow contribution to the stream. However, Ksat acts as a key control in groundwater contribution to baseflow as observed in headwaters and downstream region of the watershed. While unconsolidated deposits are often thought of as important high-porosity mountain aquifers, our results point to the importance of fractured and karstified bedrock in baseflow generation in high mountains. As climate change alters the snow- and ice-melt regimes of UIB rivers, our study underscores the critical importance of improving our understanding of baseflow sources.

Phonon modal analysis of thermal transport in ThO2 with point defects using equilibrium molecular dynamics

Defects can significantly degrade the thermal conductivity of ThO2, an advanced nuclear fuel material as well as a surrogate for other fluorite-structured materials. We investigate how point defects in ThO2 impact phonon mode-resolved thermal transport. By incorporating phonon modes from lattice dynamics, we decompose the trajectory and heat flux to phonon normal mode space and extract key phonon properties, including phonon relaxation times and their contributions to thermal conductivity. We implement two methods. The first method is based on the Green Kubo formalism to resolve the contribution of each phonon mode to thermal conductivity. The second resolves the lifetime of individual phonon modes and the thermal conductivity is calculated using the Boltzmann transport equation within relaxation time approximation. Notably, a lower contribution of acoustic modes is revealed compared to perturbative approaches considering only three-phonon scattering processes. The effects of four types of point defects are evaluated. The strongest impact on a reduction in thermal conductivity is from Th interstitials, followed by Th vacancies. O interstitials/vacancies have a similar impact, albeit smaller than defects on the thorium sublattice. These observations are consistent with previous studies.

Examining the Workability, Mechanical, and Thermal Characteristics of Eco-Friendly, Structural Self-Compacting Lightweight Concrete Enhanced with Fly Ash and Silica Fume.

This study compares the workability, mechanical, and thermal characteristics of structural self-compacting lightweight concrete (SCLWC) formulations using pumice aggregate (PA), expanded perlite aggregate (EPA), fly ash (FA), and silica fume (SF). FA and SF were used as partial substitutes for cement at a 10% ratio in various mixes, impacting different aspects: According to the obtained results, FA enhanced the workability but SF reduced it, while SF improved the compressive and splitting tensile strengths more than FA. EPA, used as a fine aggregate alongside PA, decreased the workability, compressive strength, and splitting tensile strength compared to the control mix (K0). The thermal properties were altered by FA and SF similarly, while EPA notably reduced the thermal conductivity coefficients. The thermal conductivity coefficients (TCCs) of the K0-K4 SCLWC mixtures ranged from 0.275 to 0.364 W/mK. K0 had a TCC of 0.364 W/mK. With 10% FA, K1 achieved 0.305 W/mK; K2 with 10% SF reached 0.325 W/mK. K3 and K4, using EPA instead of PA, showed significantly lower TCC values: 0.275 W/mK and 0.289 W/mK, respectively. FA and SF improved the thermal conductivity compared to K0, while EPA further reduced the TCC values in K3 and K4 compared to K1 and K2. The compressive strength (CS) values of the K0-K4 SCLWC mixtures at 7 and 28 days reveal notable trends. Using 10% FA in K1 decreased the CS at both 7 days (12.16 MPa) and 28 days (22.36 MPa), attributed to FA's gradual pozzolanic activity. Conversely, K2 with SF showed increased CS at 7 days (17.88 MPa) and 28 days (29.89 MPa) due to SF's rapid pozzolanic activity. Incorporating EPA into K3 and K4 reduced the CS values compared to PA, indicating EPA's lower strength contribution due to its porous structure.

Mass distributions in 12C + 232Th fission: role of shell effects and excitation energy

This article reports the measurement of cross sections of charge and mass identified fission products and the mass distributions in 232Th(12C,f) reaction at 62.5, 70.7 and 102.9 MeV beam energies to investigate the role of single particle effects. The study was carried out using the recoil catcher technique followed by off-line γ-ray spectrometry. Cross sections of 32, 54 and 64 fission products were measured for 62.5, 70.7 and 102.9 MeV beam energies, respectively. The mass distributions obtained at 62.5 and 70.7 MeV show a flat-top nature indicating significant asymmetric fission contribution (heavy mass peak corresponding to Z range of 54–56), whereas, a nearly Gaussian behaviour was observed at 102.9 MeV indicating dominant contribution from symmetric fission. The experimental mass distributions were in gross agreement with the “GEF, 2021/1.1” calculations which predicted significant asymmetric fission contribution dominated by Z ≈ 55 (‘Standard 2’ mode) at 62.5 and 70.7 MeV. The present study shows the significant role of charge polarization resulting in the deviation of the most probable charge (ZP) values from those obtained using UCD hypothesis. “GEF, 2023/2.1” calculations were unable to explain the observed mass distributions with significant asymmetric fission contribution due to comparatively lower contribution from higher chance fission resulting from the lower saddle point energies. An attempt has been made to estimate the mass distributions arising from the complete fusion fission and α-transfer induced fission. The trend shows an increase in the α-transfer induced fission contribution with increasing beam energy which is in qualitative agreement with the sum-rule model calculations.

Molten salt defect engineering regulation of Bi4TaO8Cl perovskite structure for boosting photo-Fenton degradation of antibiotics

Defect engineering offers a feasible avenue to ameliorate the photocatalytic activities of semiconductors, but the traditional preparation processes for introducing the defects would destroy the pristine morphology of the materials. Herein, a controllable defect engineering on CeO2 nanodots loaded Bi4TaO8Cl perovskite nanosheets was approached to synthesize well-defined CeO2/Bi4TaO8Cl (CE-BTC) heterojunction with stable oxygen vacancies (OVs) via a molten-salt-mediated strategy. Due to the coexistence of OVs and Ce4+/Ce3+ redox couple, the photo-Fenton degradation rate of ofloxacin by optimal CE-BTC heterojunction (0.09610 min−1) was 7.78 and 4.98 times higher than that by individual Bi4TaO8Cl and CeO2, respectively. Moreover, the CE-BTC also exhibited excellent degradation performance towards other antibiotics including norfloxacin, ciprofloxacin, tetracycline, and sulfamethoxazole, while maintaining good recyclability and stability. The high efficiency of CE-BTC was also attributed to its enhanced light-harvesting capability, low photogenerated carrier recombination, and minimal electron transfer resistance. Mechanism study indicated that ⋅OH and ⋅O2– were the dominant reactive species, whereas h+ also participated in the removal of ofloxacin with a lower contribution. This study demonstrated the enormous potential of CE-BTC heterojunction in the degradation and risk control of antibiotics, providing a promising strategy for designing highly dispersed heterojunction catalysts with surface defects.

Molecular modeling analysis for functionalized graphene/sodium alginate composite

This study examined the functionalization of graphene with easily ionizable elements, such as lithium, and subsequently its interaction with the biopolymer sodium alginate (SA), to highlight its potential for biomedical applications. Utilizing Density Functional Theory (DFT), the research comprehensively investigated the structural, electronic, and spectroscopic properties of these graphene-based composites. The electronic properties of functionalized graphene were investigated using DFT at the B3LYP/6-31G(d,p) level. Among the various configurations studied, graphene exhibited weak interaction with two lithium atoms, displaying the highest reactivity in terms of total dipole moment (TDM) at 5.967 Debye and a HOMO/LUMO energy gap (ΔE) of 0.748 eV. Electrostatic potential mapping revealed that graphene when enhanced with lithium and three units of SA, exhibited an augmented potential density on its surface, a finding corroborated by other investigated physical properties. Notably, the configuration of graphene/3SA/Li, with weak interaction occurring at two side carbons, demonstrated the highest reactivity with a TDM of 15.509 Debye and ΔE of 0.280 eV. Additionally, a shift in the spectral characteristics of graphene towards lower wavenumbers was observed as lithium and SA interacted with the graphene substrate. The PDOS plot for Graphene/3SA/Li, showed the highest contribution in the HOMO orbitals was equally from lithium, sodium, hydrogen, and oxygen, while the lowest contribution was from carbon. This computational analysis provides comprehensive insights into the functionalized graphene systems, aiding in their further development and optimization for practical biomedical use.

Sources of dissolved carbon in large rivers: Insights from coupled 13C-14C in the upper Changjiang (Yangtze) River

Export of dissolved carbon from rivers connects terrestrial and oceanic carbon cycling, and represents a key component of global carbon budgets. In this study, we measured the concentrations of major ions, the sulfur isotopic composition of sulfate, and the stable (δ13CDIC) and radioactive (Δ14CDIC) isotopic composition of the dissolved inorganic carbon (DIC) in the upper Changjiang (Yangtze) River, China. Their spatio-temporal variabilities give constrains on carbon cycling across catchments with diverse physiographic conditions (e.g. climate, hydrology, geology, land-use change). Daily DIC fluxes were modeled using a hydro-chemical approach and showed significant temporal variations agreeing with the measured data, and supporting a conservative mixing behavior in river channel, similar to variations in anions and cations concentrations. However, the modeled (δ13CDIC) were always higher (up to 3.1‰, and 0.8‰ on average) than the measured values. In addition, Δ14CDIC would suggest a much lower carbonate contribution (8 to 33%) than concentration mixing relationship (40 to 64%). From the chemical weathering reaction front to the riverine transport, DIC can be processed with little net change in concentration but isotopic exchange and it can also exchange with the soil and/or atmospheric CO2 as an open system. The openness parameter (ψ) uses the Δ14CDIC to estimate the extent of such exchange, ranging from 0 (fully closed system) to 1 (fully open system) and varied from 0.26±0.10 to 0.86±0.06. ψ showed a strong relationship with drainage mean elevation, likely to represent the elevation-induced climate variation (i.e. precipitation and temperature) but also the proportion of cropland in the drainage area. All of these parameters are correlated and point toward a biological impact on ψ. In addition, modern DIC yield, estimated from Δ14CDIC, is positively correlated to ψ. This study demonstrates that Δ14CDIC measurements can greatly underestimate the contribution of carbonate-derived carbon because of exchange (estimated by ψ) especially in high biological-productivity areas.

Анализ влияния отклонений на нелинейность в гибридном RC-ЦАП

This paper is dedicated to the analysis of the effect of elements mismatch on the nonlinearity of N-bit hybrid segmented RC-digital-to-analog converter. In the structure of the hybrid digital-to-analog converter under consideration, a binary capacitive segment processes the most significant bits, whereas a unary resistive segment processes the least significant bits. Since the consi¬dered digital-to-analog converter is heterogenous, the elements of both segments differ by the type (resistors or capacitors) and area. This causes an optimal ratio of segments resolutions to shift in respect to the total DAC area minimization. Therefore, the goal of the current research is to obtain an expression for optimal segments resolutions in dependance on the ratio of unit capacitor and resistor areas. For this purpose, a parametric mathematical model of the considered converter has been developed in MATLAB. The elements arrays of both segments are influenced by random errors. The simulation of differential and integral nonlinearities has been carried out, which demonstrated a lower contribution of the resistive segment on nonlinearity, in contrast to the capacitive one. Besides, the increment of a capacitive segment resolution improves the yield of both nonlinearities.

The impacts of photochemical loss on the source apportionment of ambient volatile organic compounds: A case study in Northern China

Volatile organic compounds (VOCs) play a crucial role as precursors in the formation of ozone (O3) and secondary PM2.5. It is well-established that some VOC species exhibit high photochemical reactivity, leading to deviations between measured and initial concentrations. Therefore, precise source apportionment must consider these photochemical reaction which called photochemical losses. The study was conducted in Langfang, which located in an important site for pollution transferring to Beijing, with August to October as the sampling period. The initial concentrations of the VOC species were estimated using a photochemical age-based parameterization method. The effects of photochemical losses on source apportionment were compared by the positive matrix factorization (PMF) results, based on observed and initial concentration data. The results showed that neglecting photochemical losses would result in an underestimation of VOCs concentration by 6.7% compared to the measured values obtained in this study. Furthermore, olefins and aromatic hydrocarbons were found to be the key components involved in photochemical reactions, with a photochemical loss rate of 28.3% and 23.7%, respectively. VOCs source apportionment revealed that the impact of photochemical loss on source apportionment was significant. Results indicated that biogenic sources (−6.8%) and solvent usage (−5.9%) made a higher contribution based on initial VOCs compared to measured VOCs, while gasoline vehicular emissions showed a lower contribution (+7.9%) than that observed from measured VOCs data. Analysis results also demonstrated that the combustion sources accounted for 14.2% based on measured concentrations and that accounted for 9.5% based on initial concentrations.

No Top-heavy Stellar Initial Mass Function Needed: The Ionizing Radiation of GS9422 Can Be Powered by a Mixture of an Active Galactic Nucleus and Stars

JWST is producing high-quality rest-frame optical and UV spectra of faint galaxies at z > 4 for the first time, challenging models of galaxy and stellar populations. One galaxy recently observed at z = 5.943, GS9422, has nebular line and UV continuum emission that appears to require a high ionizing photon production efficiency. This has been explained with an exotic stellar initial mass function (IMF; Cameron et al. 2023a), 10–30x more top-heavy than a Salpeter IMF. Here we suggest an alternate explanation to this exotic IMF. We use a new flexible neural net emulator for CLOUDY, Cue, to infer the shape of the ionizing spectrum directly from the observed emission line fluxes. By describing the ionizing spectrum with a piecewise power law, Cue is agnostic to the source of the ionizing photons. Cue finds that the ionizing radiation from GS9422 can be approximated by a double power law characterized by QHeIIQH=−1.5 , which can be interpreted as a combination of young, metal-poor stars and a low-luminosity active galactic nucleus with F ν ∝ λ 2 in a 65%/35% ratio. This suggests a significantly lower nebular continuum contribution to the observed UV flux (24%) than a top-heavy IMF (≳80%), and hence, necessitates a damped Lyα absorber to explain the continuum turnover bluewards of ∼1400 Å. While current data cannot rule out either scenario, given the immense impact the proposed top-heavy IMF would have on models of galaxy formation, it is important to propose viable alternative explanations and to further investigate the nature of peculiar high-z nebular emitters.