Multisystemic Resilience and Anxious-Depressed Symptoms in Black Youth Exposed to Maternal Syndemics: A Mixed-Method Study.

We explored associations between multisystemic resilience and anxious-depressed symptoms in Black families experiencing maternal syndemics (i.e., co-occurring epidemics of substance abuse, violence, HIV/AIDS), using a sequential explanatory study design. Hierarchical regression was used to analyze data from 171 Black youth (57% girls; Mage=12.13, SD = 2.90). Girls (ß=-0.17, p = .02) with higher inter/intrapersonal skills (ß = - 0.28, p = .004) and more open familial communication (ß = - 0.40, p < .001) reported fewer anxious-depressed symptoms, F(12, 147) = 5.68; p < .001, Adj R2 = 26.1%. Qualitative results from a subsample of 10 Black youth-mother dyads explored inter/intrapersonal factors (i.e., emotion regulation strategies, goal setting, persistence and perseverance, problem-solving skills) and open communication factors (i.e., comfortable environment to talk, solving problems, processing feelings, showing affection, benefiting from open communication) that support Black youth resilience. Findings highlight key resilience factors that could be bolstered in future interventions to reduce anxious-depressed symptoms among Black youth exposed to maternal syndemics.

Endoparasitism and risk factors in horses from ethnic communities in Andean areas of southern Chile.

Parasitic infections are among the most important causes of morbidity and mortality in horses worldwide. In the Andean mountainous regions of Chile, horses are a highly valued specie, playing a key role as working animals also providing support in cattle transhumance grazing into high mountainous areas during dry season. The breeding and maintenance of horses in the mountainous region of La Araucanía in Chile is a key issue allowing to the subsistence economy of communities with a strong ethnic component represented by Mapuche-Pehuenche origin families. However, the health status of these animals is unknown. Therefore, the objective of this study was to determine endoparasitic infections in horses from this area and the main factors that may influence parasitism. Thus, a cross-sectional study performed in 126 working horses from Andean region was achieved by using different coproparasitologycal analyses, resulting in a 97,6% of prevalence of endoparasitism with the strongyle eggs showing the highest prevalence of infection in analysed horses (96%) followed by Oxyuris equi (27%), Parascaris equorum (17,5%) and protozoans including ciliates (11,1%), Blastocystis spp (5,6%), Giardia spp (2,4%) and Cryptosporidium spp (1,6%) highlighting zoonotic relevance of some of these species. Concerning risk factors, the high prevalence suggests that exposure was high regardless of age or sex. The higher proportion of infected horses were grazing compared to those stabled, likewise drinking non-potable water, being these the main risks factors linked to the high prevalence of horse infections in Andean communities here studied.

Heavy metal pollution index calculation in geochemistry assessment: a case study on Playa Las Petroleras.

This work is aimed to assess potential risk associated with the presence of metals and metalloids in soil at "Playa Las Petroleras" sector, located in Antofagasta (Chile). The zone under study has been affected by four oil spill events. This sector is located in an urban area by the sea. So, it has a great social and environmental relevance. The concentrations of 15 elements in soil samples were assessed, four of them presenting potential ecological risk: As, Co, Cu, and Pb. Nine pollution indices were applied to data: four single pollution indices and five integrated pollution indices to assess soil pollution. The single pollution indices show that the site bears potential ecological and environmental risk due to the presence of Cu, the site being classified as highly contaminated owing to a severe enrichment of this metal. For Co, all the indices allow classifying the site as little or uncontaminated, while the level of As and Pb pollution could be considered as ranging from uncontaminated to moderately contaminated. The integrated pollution indices show that average concentrations are highly contaminated mainly owing to the presence of Cu.

Task-modulated Sensitivity to Vocal Pitch in the Dorsal Premotor Cortex during Multitalker Speech Recognition.

It has long been known that listening to speech activates inferior frontal (pre-)motor regions in addition to a more dorsal premotor site (dPM). Recent work shows that dPM, located adjacent to laryngeal motor cortex, responds to low-level acoustic speech cues including vocal pitch, and the speech envelope, in addition to higher-level cues such as phoneme categories. An emerging hypothesis is that dPM is part of a general auditory-guided laryngeal control circuit that plays a role in producing speech and other voluntary auditory-vocal behaviors. We recently reported a study in which dPM responded to vocal pitch during a degraded speech recognition task, but only when speech was rated as unintelligible; dPM was more robustly modulated by the categorical difference between intelligible and unintelligible speech. Contrary to the general auditory-vocal hypothesis, this suggests intelligible speech is the primary driver of dPM. However, the same pattern of results was observed in pitch-sensitive auditory cortex. Crucially, vocal pitch was not relevant to the intelligibility judgment task, which may have facilitated processing of phonetic information at the expense of vocal pitch cues. The present fMRI study (n = 25) tests the hypothesis that, for a multitalker task that emphasizes pitch for talker segregation, left dPM and pitch-sensitive auditory regions will respond to vocal pitch regardless of overall speech intelligibility. This would suggest that pitch processing is indeed a primary concern of this circuit, apparent during perception only when the task demands it. Spectrotemporal modulation distortion was used to independently modulate vocal pitch and phonetic content in two-talker (male/female) utterances across two conditions (Competing, Unison), only one of which required pitch-based segregation (Competing). A Bayesian hierarchical drift-diffusion model was used to predict speech recognition performance from patterns of spectrotemporal distortion imposed on each trial. The model's drift rate parameter, a d'-like measure of performance, was strongly associated with vocal pitch for Competing but not Unison. Using a second Bayesian hierarchical model, we identified regions where behaviorally relevant acoustic features were related to fMRI activation in dPM. We regressed the hierarchical drift-diffusion model's posterior predictions of trial-wise drift rate, reflecting the relative presence or absence of behaviorally relevant acoustic features from trial to trial, against trial-wise activation amplitude. A significant positive association with overall drift rate, reflecting vocal pitch and phonetic cues related to overall intelligibility, was observed in left dPM and bilateral auditory cortex in both conditions. A significant positive association with "pitch-restricted" drift rate, reflecting only the relative presence or absence of behaviorally relevant pitch cues, regardless of the presence or absence of phonetic content (intelligibility), was observed in left dPM, but only in the Competing condition. Interestingly, the same effect was observed in bilateral auditory cortex but in both conditions. A post hoc mediation analysis ruled out the possibility that decision load was responsible for the observed pitch effects. These findings suggest that processing of vocal pitch is a primary concern of the auditory-cortex-dPM circuit, although during perception core pitch, processing is carried out by auditory cortex with a potential modulatory influence from dPM.

Evaluation of the geochemical background of soil in a hyper-arid zone using a multivariate statistical methodology: The case of the city of Antofagasta in the Atacama Desert.

This study investigates the geochemical background and factors influencing the variability of 19 environmentally relevant elements in the soils of Antofagasta, Chile, a region known for its extensive mining activities. Employing robust multivariate statistical techniques on a dataset of 94 soil samples, we identified four main factors explaining 70% of the total variance in elemental concentrations. These four factors reflect the influence of Jurassic volcanic rocks, intrusive rocks, marine sediments, and mafic to intermediate intrusive rocks. Cluster analysis revealed three distinct geochemical populations, each reflecting a unique combination of natural and anthropogenic influences. We established background concentrations for each element within these clusters using robust statistical methods. Geostatistical analysis, employing inverse distance weighted interpolation, produced factor distribution maps that, when integrated with geological data, provided insights into lithological and anthropogenic influences on soil geochemistry. Our findings highlight the complex interplay between natural geological processes, the region's unique arid climate, and anthropogenic activities in shaping the geochemical landscape of Antofagasta. This study contributes to the understanding of geochemical backgrounds in mining-intensive, arid regions and provides a methodological framework applicable to similar environments worldwide.

Additive effects of mild head trauma, blast exposure, and aging within white matter tracts: A novel Diffusion Tensor Imaging analysis approach.

Existing diffusion tensor imaging (DTI) studies of neurological injury following high-level blast exposure (hlBE) in military personnel have produced widely variable results. This is potentially due to prior studies often not considering the quantity and/or recency of hlBE, as well as co-morbidity with non-blast head trauma (nbHT). Herein, we compare commonly used DTI metrics: fractional anisotropy and mean, axial, and radial diffusivity, in Veterans with and without history of hlBE and/or nbHT. We use both the traditional method of dividing participants into 2 equally weighted groups and an alternative method wherein each participant is weighted by quantity and recency of hlBE and/or nbHT. While no differences were detected using the traditional method, the alternative method revealed diffuse and extensive changes in all DTI metrics. These effects were quantified within 43 anatomically defined white matter tracts, which identified the forceps minor, middle corpus callosum, acoustic and optic radiations, fornix, uncinate, inferior fronto-occipital and inferior longitudinal fasciculi, and cingulum, as the pathways most affected by hlBE and nbHT. Moreover, additive effects of aging were present in many of the same tracts suggesting that these neuroanatomical effects may compound with age.

A Learning Assessment to Increase Diversity in Academic Health Sciences.

Importance: Strategies and innovations to advance racial and ethnic equity in recruitment, promotion, and retention at academic health science institutions are needed. Objective: This learning assessment aims to isolate evidence-based strategies to advance racial equity in the academic health sciences, which have implications for policy and institution-level interventions. Evidence Review: This learning assessment used a mixed-methods approach, including a quantitative survey, qualitative in-depth interviews, and a scoping literature review. Survey respondents were recruited from outreach lists that included researchers working with racial and ethnic minoritized populations. In-depth interviews were conducted among 60 university administrators, faculty/staff, scholars, students, and individuals affiliated with governmental, nongovernmental, and identity-based professional associations. A search of the literature in PsycINFO, MEDLINE, ERIC, Education Source, Academic Search Ultimate, and CINAHL was conducted for the scoping review. The scoping review included 366 primary articles of studies evaluating strategies to advance racial and ethnic equity at academic health science institutions. Findings: The survey yielded analyzable results from 328 individuals, including faculty, students, administrators, or staff, and individuals not currently employed at or enrolled full time at a university or college. The interviews included 60 participants with a mean (SD) age of 49.3 (16.5) years, and 39 (65%) were female. The scoping review included 366 primary research articles that met inclusion criteria for analysis. Data were analyzed individually across the survey, interviews, and scoping review, and findings were triangulated. While each of the 3 assessments yielded unique findings, 13 common themes emerged across all project components. Results revealed strategies implemented and evaluated successfully, as well as challenges and barriers to advancing equity in the academic health sciences. Conclusions and Relevance: In this study, 13 meaningful strategies emerged across the survey, in-depth interviews, and scoping review. Through triangulation of findings, recommendations of actionable steps were made.

Trauma center rehabilitation systems in Latin America.

Trauma is a leading cause of mortality and morbidity worldwide with high rates of disability in survivors. With improvements in care, rehabilitation of the trauma patient is a cornerstone to reducing sequelae. A lack of well-established hospital rehabilitation units and standardized protocols for managing posttraumatic injuries is a common problem in Latin American countries. Future studies should seek to understand the barriers and gaps in care so that consensus and ultimately best practice guidelines can be developed and included in rehabilitation programs throughout trauma centers in Latin America.

Promoting health equity in HIV prevention and treatment research: a practical guide to establishing, implementing, and sustaining community advisory boards.

Over the last 25 years, community-based participatory research (CBPR) has emerged as an innovative methodological approach to break down the barriers toward health equity in biopsychosocial research. Although there are several methods one can use to conduct CBPR research, one widely used established tool that has shown to be effective for engaging community meaningfully in research is community advisory boards (CABs). CABs are formalized collaborative bodies consisting of community and research stakeholders and have been integral in engaging underserved groups experiencing HIV-related health inequities at the early stages of the AIDS crisis. Even though evidence suggests that CABs are an effective tool for conducting high-quality, rigorous, and community-centered HIV-related research, there are minimal guidelines summarizing the steps needed for developing and maintaining a CAB. Therefore, to fill this gap in the literature, this article offers a practical guide to help researchers with minimal experience, particularly graduate students and early-stage investigators, feel more comfortable with establishing a CAB for equity-focused HIV-related research. This article synthesizes already established guidelines and frameworks for CAB development while specifically outlining unique steps related to the three main stages of CAB formation - establishment, implementation, and sustainment. Throughout this article, the authors offer tension points, generated from the literature and with consultation from a CAB working alongside the authors, that researchers and community partners may need to navigate during each of these three stages. In addition, best practices from the literature are identified for each step in the guidelines so that readers can see firsthand how research groups have carried out these steps in their own practice.

Cortical networks for recognition of speech with simultaneous talkers.

The relative contributions of superior temporal vs. inferior frontal and parietal networks to recognition of speech in a background of competing speech remain unclear, although the contributions themselves are well established. Here, we use fMRI with spectrotemporal modulation transfer function (ST-MTF) modeling to examine the speech information represented in temporal vs. frontoparietal networks for two speech recognition tasks with and without a competing talker. Specifically, 31 listeners completed two versions of a three-alternative forced choice competing speech task: "Unison" and "Competing", in which a female (target) and a male (competing) talker uttered identical or different phrases, respectively. Spectrotemporal modulation filtering (i.e., acoustic distortion) was applied to the two-talker mixtures and ST-MTF models were generated to predict brain activation from differences in spectrotemporal-modulation distortion on each trial. Three cortical networks were identified based on differential patterns of ST-MTF predictions and the resultant ST-MTF weights across conditions (Unison, Competing): a bilateral superior temporal (S-T) network, a frontoparietal (F-P) network, and a network distributed across cortical midline regions and the angular gyrus (M-AG). The S-T network and the M-AG network responded primarily to spectrotemporal cues associated with speech intelligibility, regardless of condition, but the S-T network responded to a greater range of temporal modulations suggesting a more acoustically driven response. The F-P network responded to the absence of intelligibility-related cues in both conditions, but also to the absence (presence) of target-talker (competing-talker) vocal pitch in the Competing condition, suggesting a generalized response to signal degradation. Task performance was best predicted by activation in the S-T and F-P networks, but in opposite directions (S-T: more activation = better performance; F-P: vice versa). Moreover, S-T network predictions were entirely ST-MTF mediated while F-P network predictions were ST-MTF mediated only in the Unison condition, suggesting an influence from non-acoustic sources (e.g., informational masking) in the Competing condition. Activation in the M-AG network was weakly positively correlated with performance and this relation was entirely superseded by those in the S-T and F-P networks. Regarding contributions to speech recognition, we conclude: (a) superior temporal regions play a bottom-up, perceptual role that is not qualitatively dependent on the presence of competing speech; (b) frontoparietal regions play a top-down role that is modulated by competing speech and scales with listening effort; and (c) performance ultimately relies on dynamic interactions between these networks, with ancillary contributions from networks not involved in speech processing per se (e.g., the M-AG network).

Evaluation of the impact of the intensive exploitation of groundwater and the mega-drought based on the hydrochemical and isotopic composition of the waters of the Chacabuco-Polpaico basin in central Chile.

A hydrogeochemical and isotopic study has been carried out to understand the hydrogeological functioning of a small alluvial aquifer in central Chile in a context of mega-drought and intensive exploitation of its waters. Additionally, two mine tailings dams from porphyry copper mining are situated in the area. The prolonged mega-drought, which has lasted for over thirteen years, has resulted in a significant decrease in rainfall recharge and a drop of up to 50 m in piezometric levels, although no serious groundwater contamination problems have yet been detected, except for a rise in nitrate contents (ranging between 23 and 45 mg/L NO3) attributed to return irrigation. Groundwaters are calcium-bicarbonate and calcium-sodium-bicarbonate in composition. The values of δ18O and δ2H of the alluvial aquifer indicate fractionation by evaporation that would be explained by the recirculation of water that occurs in the agricultural areas of the basin, where the excess irrigation water that go back to the aquifer presents fractionation by evaporation. The δ34S and δ18O of dissolved sulfate point to pyrite oxidation, which could be related to the pyrite present in the copper porphyry and recognized in the Andes Cordillera. The 87Sr/86Sr isotopic values of the alluvial aquifer waters are close to the isotopic fingerprint of the volcanic rocks of the Abanico Formation. However, the water from the wells located further downstream in the basin and close to the tailing dams show δ34S and δ18O of dissolved sulfate and 87Sr/86Sr consistent with Miocene intrusive mineralogies of the copper porphyry type. The groundwater chemistry does not show water seepage from the tailings dam. Therefore, a minor contribution of minerals related to the intrusive rocks is proposed, which would originate from the movement of fine particles by the wind from the dams to the valley floor. The 14C activities indicate that groundwater is recent.

Characterization of precipitation and recharge in the peripheral aquifer of the Salar de Atacama.

To reduce uncertainty in the identification of the recharge areas in the Peripheral Aquifer of the Salar de Atacama (SdA), a few studies have investigated the isotopic characteristics and moisture sources of precipitation in the SdA basin. In the present study, the seasonal cycle of meteorological parameters and the relationships of this cycle with sea surface temperature anomalies are shown, the sources of humidity are identified, and the types of clouds producing precipitation are defined. Finally, the isotopic compositions of precipitation, surface water and groundwater in the SdA basin and the Altiplano-Puna Plateau basins are analysed to identify the area recharging the northern, eastern and southern subbasins of the SdA. In summer, when the highest temperature, relative humidity and precipitation values of the year are recorded, the precipitation is due to deep convection. The trajectories of the arriving air masses can be classified into three groups: from the North Atlantic Ocean across the Amazon basin, from the South Atlantic Ocean across the La Plata River basin and the Gran Chaco, and from the Pacific Ocean. In winter, when the temperature, relative humidity and precipitation are lower, the moisture masses come from the Pacific Ocean. Winter precipitation is more depleted in heavy isotopes than summer precipitation. The isotopic analysis of precipitation, surface water and groundwater shows that recharge of the eastern subbasins of the SdA occurs by diffuse infiltration of precipitation and concentrated infiltration of surface water, both within the hydrographic basin of the SdA. The meteoric source of the waters in the Altiplano-Puna Plateau basins is isotopically lighter than the waters found in the side basins of the SdA, so there is no significant water quantity transfer to the peripheral aquifers of the SdA from outside the hydrographic basin.

Vitamin Supplements as a Nutritional Strategy against Chronic Alcohol Consumption? An Updated Review.

Several studies have shown that blood vitamin levels are low in alcoholic patients. In effect, alcohol use abuse is considered a chronic disease that promotes the pathogenesis of many fatal diseases, such as cancer and liver cirrhosis. The alcohol effects in the liver can be prevented by antioxidant mechanisms, which induces enzymatic as well as other nonenzymatic pathways. The effectiveness of several antioxidants has been evaluated. However, these studies have been accompanied by uncertainty as mixed results were reported. Thus, the aim of the present review article was to examine the current knowledge on vitamin deficiency and its role in chronic liver disease. Our review found that deficiencies in nutritional vitamins could develop rapidly during chronic liver disease due to diminished hepatic storage and that inadequate vitamins intake and alcohol consumption may interact to deplete vitamin levels. Numerous studies have described that vitamin supplementation could reduce hepatotoxicity. However, further studies with reference to the changes in vitamin status and the nutritional management of chronic liver disease are in demand.

Processes explaining the origin and evolution of groundwater composition in the Andean Precordillera and Altiplano of the Tarapacá Region of northern Chile.

In the arid area of northern Chile, groundwater resources in the Andean formations are essential for native populations, ecological services, mining, and other human activities. Validated conceptual hydrogeological models are required for current and future water and land management. This work aims to explain the processes controlling the origin and distribution of recharge and groundwater composition in the Andean Precordillera and Altiplano of the Tarapacá Region of northern Chile, using major solutes in spring, river, and well water, and the stable and radioactive isotopes of water oxygen, hydrogen, and dissolved inorganic carbon. The waters are mainly of the Na-Ca-SO4 type. Processes controlling the chemical evolution of waters are atmospheric dust contribution, evapo-concentration, and enhanced volcanic rock weathering, as well as halite dissolution in some locations. The isotopic composition of Precordillera eastern flank water samples follows an evaporation line, while those in the western flank, in the Altiplano, follow a line that is parallel to the local meteoric line, suggesting unsaturated zone evaporation processes of infiltrated rainfall. δ13CDIC contents (-2 to -27‰) indicate mixing processes, volcanic CO2 in the Altiplano, and calcite dissolution in some sectors. In the western depression, the only recharge is due to water infiltration in creek channels. In the highland areas, 5-25% of precipitation produces recharge. The estimated groundwater renewal time in the Precordillera was 3-14 kyr. The piezometric elevation in the Precordillera due to low-permeability intrusive rocks and local recharge prevents the east-west groundwater transfer from the Altiplano to the western depression and explains why the volcanic CO2 in the Altiplano basins is not observed on the western flank. These results provide new insights for the evolution of water quality in volcanic aquifers in arid environments and provide considerations for estimating groundwater residence times using radiocarbon in areas influenced by volcanic CO2.

Assessment of Tacrolimus Neurotoxicity Measured by Retinal OCT.

BACKGROUND: Neurotoxicity secondary to anticalcineurinics is a prevalent side effect in transplant recipients. Optical coherence tomography (OCT) scans the central nervous system by direct access to the retina. OCT assesses central nervous system involvement by measuring the thickness of the retinal layers, especially the ganglion cell layer (GCL). The retinal scan divides the scanned area into affected and unaffected segments, which can be quantified for each eye. The aim of this study was to determine retinal GCL thickness by means of OCT, analyzing the proportion of affected segments in individuals exposed to tacrolimus compared with a control group. MATERIALS AND METHODS: We evaluated 20 renal transplant recipients exposed to tacrolimus for ≥6 months. The number of affected segments in the GCL of the retina was quantified by OCT. The control group was drawn from the general population attending routine ophthalmologic checkups. RESULTS: Patients exposed to tacrolimus had a pathologic examination in 50% of cases compared with 20% in the control group (P < .044). Furthermore, among patients with an exposure time to tacrolimus >5 years, the examination was pathologic in 80% (P < .005). Linear regression analysis showed the presence of GCL segments with decreased thickness to be associated with the duration of exposure to tacrolimus (P = .036) and the time in dialysis before kidney transplant (P = .030). CONCLUSION: Although this is a preliminary study, OCT scanning could serve to detect the neurotoxic effect of tacrolimus on the retinal GCL and central nervous system in renal transplant recipients.

[CRF-BP and SLC6A4 gene polymorphisms among restrained eaters]. / Asociación de polimorfismos de los genes CRF-BP, SLC6A4 y restricción alimentaria crónica: un estudio preliminar.

BACKGROUND: Restrained eaters (RE) are a group of individuals who constantly restrict their eating. However, they usually alternate restriction with periods of overeating. AIM: To evaluate the possible association of CRF-BP and SLC6A4 gene polymorphisms with chronic alimentary restriction. MATERIAL AND METHODS: The Spanish version of the Revised Restraint Scale was applied to 132 women aged 18 to 25 years. They were divided in a group classified as restrained eaters (RE) and a group of unrestrained eaters. The 5-HTTLPR and CRF-BPs11 polymorphisms of the SLC6A4 and CRF-BP genes were evaluated by polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism (RFLP), respectively. RESULTS: There was a significant association between the s/s homozygous genotype for the 5-HTTLPR polymorphism of SLC6A4 gene and RE condition (p = 0.033). However, this association was not observed for the CRF-BPs11 polymorphism. CONCLUSIONS: The presence of s/s genotype is associated with the RE condition, being the presence of a s allele, a risk factor for this condition.

Prevalence of Short Root Anomaly in a Group of Puerto Ricans.

OBJECTIVE: To estimate the prevalence of short root anomaly (SRA) in a group of Puerto Ricans at the Advanced Education Program in Orthodontics of the University of Puerto Rico. METHODS: A cross-sectional study was conducted with digital panoramic x-rays of 203 patients (112 females and 91 males; mean age: 17 years) in Puerto Rico. Utilizing the modified Lind's method, 406 maxillary right and left central incisors (1) were measured and evaluated for SRA. Root and crown length and R/C ratio were compared by sex and side. Linear regression was used to evaluate the associations between the R/C ratio and age, sex, and side (right/left). All the statistical analyses were evaluated using significance level of .05 (2). RESULTS: The prevalence of SRA was 0.49%. The average root and crown lengths for the maxillary right and left central incisors were 19.47 and 10.28 mm, respectively. Sex was associated with root and crown length, not with the R/C ratio. No differences were observed in the R/C ratio by the side. There were no significant associations between age, sex, and side and R/C ratio in the multivariate analysis. CONCLUSION: The prevalence of SRA in our population is lower than any reported in the literature. The R/C ratio in our Hispanic population was the highest compared with those of other ethnicities. Neither the sex nor the side of the incisor was associated with the R/C ratio. These findings are contrary to those of prior reports stating that males have higher R/C ratios than females.

An experimental and theoretical approach on stability towards hydrolysis of triethyl phosphate and its effects on the microstructure of sol-gel-derived bioactive silicate glass.

The sol-gel method is versatile and one of the well-established synthetic approaches for preparing bioactive glass with improved microstructure. In a successful approach, alkoxide precursors undergo rapid hydrolysis, followed by immediate condensation leading to the formation of three-dimensional gels. On the other hand, a slow kinetics rate for hydrolysis of one or more alkoxide precursors generates a mismatch in the progression of the consecutive reactions of the sol-gel process, which makes it difficult to form homogeneous multicomponent glass products. The amorphous phase separation (APS) into the gel is thermodynamically unstable and tends to transform into a crystalline form during the calcination step of xerogel. In the present study, we report a combined experimental and theoretical method to investigate the stability towards hydrolysis of triethyl phosphate (TEP) and its effects on the mechanism leading to phase separation in 58S bioactive glass obtained via sol-gel route. A multitechnical approach for the experimental characterization combined with calculations of functional density theory (DFT) suggest that TEP should not undergo hydrolysis by water under acidic conditions during the formation of the sol or even in the gel phase. The activation energy barrier (ΔG‡) showed a height of about 20 kcal·mol-1 for the three stages of hydrolysis and the reaction rates calculated for each stage of TEP hydrolysis were kFHR = 7.0 × 10-3s-1, kSHR = 6.8 × 10-3s-1 and kTHR = 3.5 × 10-3s-1. These results show that TEP remains in the non-hydrolyzed form segregated within the xerogel matrix until its thermal decomposition in the calcination step, when P species preferentially associate with calcium ions (labile species) and other phosphate groups present nearby, forming crystalline domains of calcium pyrophosphates permeated by the silica-rich glass matrix. Together, our data expand the knowledge about the synthesis by the sol-gel method of bioactive glass and establishes a mechanism that explains the role played by the precursor source of phosphorus (TEP) in the phase separation, an event commonly observed for these biomaterials.

Recharge and residence times of groundwater in hyper arid areas: The confined aquifer of Calama, Loa River Basin, Atacama Desert, Chile.

Groundwater recharge in hyper arid areas often depends on surface water infiltration and diffuse recharge of highly evaporated precipitation only contribute under favorable conditions. This happens in the Calama basin two-aquifer system, in the Central Andean area of northern Chile. A conceptual model of the groundwater system and its relationship with the Loa River is defined. We focus on the confined aquifer of the Calama basin, combining hydrodynamic, hydrogeochemical and isotopic methods. Radiocarbon (14C) activity data of dissolved inorganic carbon (DIC), in conjunction with chemical data, are applied to evaluate groundwater residence time within the confined aquifer. The Loa River recharges the Calama basin aquifers in its northeastern part, with water that has chemical and isotopic characteristics inherited from the arid environment and volcanic rocks in its upper basin. In the central and northeastern part of the confined aquifer, minor variations in chloride concentration suggest that the deep aquifer is well confined. The δ18O and δ2H values in groundwater of the confined aquifer show an increasing isotopic fractionation from the recharge area (around -10‰ δ18O) to those in the discharge area (between -8.5‰ and -8‰) in the southwestern part of the aquifer. The 14C activity continuously decreases down flow from the recharge by the Loa River. Adjusted DIC radiocarbon ages indicate a groundwater travel time between 1500 and 4000 years in the confined aquifer of Calama. Despite the limitations and uncertainties of radiocarbon in DIC to estimate groundwater transit times for the confined aquifer and considering complementary chemical and isotopic constraints, the DIC 14C provides acceptable values. The approach may be applicable in other confined aquifers in hyper-arid climates in which the formation of aquifer systems linked to river damming by geological action took place. This information is needed for sound management of the scarce groundwater resources.

A Meta-Analysis of the Effect of Bacillus Calmette-Guérin Vaccination Against Bovine Tuberculosis: Is Perfect the Enemy of Good?

More than 50 million cattle are likely exposed to bovine tuberculosis (bTB) worldwide, highlighting an urgent need for bTB control strategies in low- and middle-income countries (LMICs) and other regions where the disease remains endemic and test-and-slaughter approaches are unfeasible. While Bacillus Calmette-Guérin (BCG) was first developed as a vaccine for use in cattle even before its widespread use in humans, its efficacy against bTB remains poorly understood. To address this important knowledge gap, we conducted a systematic review and meta-analysis to determine the direct efficacy of BCG against bTB challenge in cattle, and performed scenario analyses with transmission dynamic models incorporating direct and indirect vaccinal effects ("herd-immunity") to assess potential impact on herd level disease control. The analysis shows a relative risk of infection of 0.75 (95% CI: 0.68, 0.82) in 1,902 vaccinates as compared with 1,667 controls, corresponding to a direct vaccine efficacy of 25% (95% CI: 18, 32). Importantly, scenario analyses considering both direct and indirect effects suggest that disease prevalence could be driven down close to Officially TB-Free (OTF) status (<0.1%), if BCG were introduced in the next 10-year time period in low to moderate (<15%) prevalence settings, and that 50-95% of cumulative cases may be averted over the next 50 years even in high (20-40%) disease burden settings with immediate implementation of BCG vaccination. Taken together, the analyses suggest that BCG vaccination may help accelerate control of bTB in endemic settings, particularly with early implementation in the face of dairy intensification in regions that currently lack effective bTB control programs.