Comparison of hydric and thermal physiology in an environmentally diverse clade of Caribbean anoles.

As the world becomes warmer and precipitation patterns less predictable, organisms will experience greater heat and water stress. It is crucial to understand the factors that predict variation in thermal and hydric physiology among species. This study focuses on investigating the relationships between thermal and hydric diversity, and their environmental predictors, in a clade of Hispaniolan anole lizards, which are part of a broader Caribbean adaptive radiation. This clade, the 'cybotoid' anoles, occupies a wide range of thermal habitats (from sea level to several kilometers above it) and hydric habitats (such as xeric scrub, broadleaf forest, and pine forest), setting up the possibility for ecophysiological specialization among species. Among the thermal traits only cold tolerance is correlated with environmental temperature, and none of our climate variables were correlated with hydric physiology. Nevertheless, we found a negative relationship between heat tolerance (critical thermal maximum) and evaporative water loss at higher temperatures such that more heat tolerant lizards are also more desiccation tolerant at higher temperatures. This finding hints at shared thermal and hydric specialization at higher temperatures, underscoring the importance of considering the interactive effects of temperature and water balance in ecophysiological studies. While ecophysiological differentiation is a core feature of the anole adaptive radiation, our results suggest that close relatives in this lineage do not diverge in hydric physiology and only diverge partially in thermal physiology.

Effectiveness of decentralizing outpatient acute malnutrition treatment with community health workers and a simplified combined protocol: a cluster randomized controlled trial in emergency settings of Mali.

Background: Outpatient treatment of acute malnutrition is usually centralized in health centers and separated into different programs according to case severity. This complicates case detection, care delivery, and supply chain management, making it difficult for families to access treatment. This study assessed the impact of treating severe and moderate cases in the same program using a simplified protocol and decentralizing treatment outside health centers through community health workers (CHWs). Methods: A three-armed cluster randomized controlled trial under a non-inferiority hypothesis was conducted in the Gao region of Mali involving 2,038 children between 6 and 59 months of age with non-complicated acute malnutrition. The control arm consisted of 549 children receiving standard treatment in health centers from nursing staff. The first intervention arm consisted of 800 children treated using the standard protocol with CHWs added as treatment providers. The second intervention arm consisted of 689 children treated by nurses and CHWs under the ComPAS simplified protocol, considering mid-upper arm circumference as the sole anthropometric criterion for admission and discharge and providing a fixed dose of therapeutic food for severe and moderate cases. Coverage was assessed through cross-sectional surveys using the sampling evaluation of access and coverage (SLEAC) methodology for a wide area involving several service delivery units. Results: The recovery rates were 76.3% in the control group, 81.8% in the group that included CHWs with the standard protocol, and 92.9% in the group that applied the simplified protocol, confirming non-inferiority and revealing a significant risk difference among the groups. No significant differences were found in the time to recovery (6 weeks) or in anthropometric gain, whereas the therapeutic food expenditure was significantly lower with the simplified combined program in severe cases (43 sachets fewer than the control). In moderate cases, an average of 35 sachets of therapeutic food were used. With the simplified protocol, the CHWs had 6% discharge errors compared with 19% with the standard protocol. The treatment coverage increased significantly with the simplified combined program (SAM +42.5%, MAM +13.8%). Implications: Implementing a simplified combined treatment program and adding CHWs as treatment providers can improve coverage while maintaining non-inferior effectiveness, reducing the expenditure on nutritional intrants, and ensuring the continuum of care for the most vulnerable children.

Silver refining in the New World: A singularity in the history of useful knowledge.

Historians have thoroughly documented the development of mercury-based silver refining in Spanish America in the late sixteenth century, and its use for over 300 years on an industrial scale unknown in Europe. However, we currently lack any consensus about the significance of this technology in the global history of knowledge. This article critically reassesses the invention and improvement of this refining method with the aim of addressing two interrelated issues. Firstly, how experiential knowledge and practical skills in silver refining were deliberately harnessed to solve a specific technical problem. Secondly, how economic incentives and patronage set the stage for empirical practices and a collaborative culture that facilitated the widespread use of this novel technique. In so doing, this article places silver refining within the theoretical constructs and historiography of useful knowledge, and bridges narratives that have remained largely isolated.

The global roots of pre-1900 legacy mercury.

During the nineteenth century, a major change took place in the trade, production, and use of mercury that altered its nearly exclusive link to silver refining in the Hispanic New World. We track the global expansion of mercury markets in chronological detail from 1511 to 1900 using historical archives on production and trade, a detailed country-by-country accounting of the pool of anthropogenic mercury from which legacy mercury was ultimately generated. The nature and profile of pre-1900 legacy mercury extends beyond silver refining, mercury production, and gold extraction, and includes alternate sources (vermilion, felt, mercury fulminate) and new regions that were not major silver or gold producers (China, India, United Kingdom, France, among others), that accounted for approximately 50% of total mercury consumed in the nineteenth century. The nature of the pre-1900 mercury market requires a quantitative distinction between legacy mercury and historic anthropogenic mercury production and use, since the chemistry of its end-uses determines the pathways and timelines for its incorporation into the global biogeochemical cycle. We thus introduce the concept of a mercury source pool to account for total historic anthropogenic mercury within and outside this cycle. Together with a critical review of previous assumptions used to reconstruct the historical use and loss of mercury, a much lower level of emissions of pre-1900 legacy mercury is proposed. A coordinated effort across disciplines is needed, to complete a historically accurate scenario that can guide the multilateral policies adopted under the United Nations Minamata Convention to control mercury in the environment.

Effectiveness and Coverage of Severe Acute Malnutrition Treatment with a Simplified Protocol in a Humanitarian Context in Diffa, Niger.

BACKGROUND: the aim of this study is to evaluate the effectiveness and coverage of a simplified protocol that is implemented in health centers (HCs) and health posts (HPs) for children who are suffering from severe acute malnutrition (SAM) in the humanitarian context of Diffa. METHODS: We conducted a non-randomized community-controlled trial. The control group received outpatient treatment for SAM, without medical complications, at HCs and HPs with the standard protocol of community management of acute malnutrition (CMAM). Meanwhile, with respect to the intervention group, the children with SAM received treatment at the HCs and HPs through a simplified protocol wherein the mid-upper arm circumference (MUAC) and the presence of edema were used as the admission criteria, and the children with SAM were administered doses of fixed ready-to-use therapeutic food (RUTF). RESULTS: A total of 508 children, who were all under 5 years and had SAM, were admitted into the study. The cured proportion was 87.4% in the control group versus 96.6% in the intervention group (p value = 0.001). There was no difference between the groups in the length of stay, which was 35 days, but the intervention group used a lower quantity of RUTF-70 sachets versus 90 sachets, per child cured. Coverage increases were observed in both groups. DISCUSSION: the simplified protocol used at the HCs and HPs did not result in worse recovery and resulted in fewer discharge errors compared to the standard protocol.

A synthesis of mercury research in the Southern Hemisphere, part 2: Anthropogenic perturbations.

Environmental mercury (Hg) contamination is a global concern requiring action at national scales. Scientific understanding and regulatory policies are underpinned by global extrapolation of Northern Hemisphere Hg data, despite historical, political, and socioeconomic differences between the hemispheres that impact Hg sources and sinks. In this paper, we explore the primary anthropogenic perturbations to Hg emission and mobilization processes that differ between hemispheres and synthesize current understanding of the implications for Hg cycling. In the Southern Hemisphere (SH), lower historical production of Hg and other metals implies lower present-day legacy emissions, but the extent of the difference remains uncertain. More use of fire and higher deforestation rates drive re-mobilization of terrestrial Hg, while also removing vegetation that would otherwise provide a sink for atmospheric Hg. Prevalent Hg use in artisanal and small-scale gold mining is a dominant source of Hg inputs to the environment in tropical regions. Meanwhile, coal-fired power stations continue to be a significant Hg emission source and industrial production of non-ferrous metals is a large and growing contributor. Major uncertainties remain, hindering scientific understanding and effective policy formulation, and we argue for an urgent need to prioritize research activities in under-sampled regions of the SH.

Anthropometric deficits and the associated risk of death by age and sex in children aged 6-59 months: A meta-analysis.

Risk of death from undernutrition is thought to be higher in younger than in older children, but evidence is mixed. Research also demonstrates sex differences whereby boys have a higher prevalence of undernutrition than girls. This analysis described mortality risk associated with anthropometric deficits (wasting, underweight and stunting) in children 6-59 months by age and sex. We categorised children into younger (6-23 months) and older (24-59 months) age groups. Age and sex variations in near-term (within 6 months) mortality risk, associated with individual anthropometric deficits were assessed in a secondary analysis of multi-country cohort data. A random effects meta-analysis was performed. Data from seven low-or-middle-income-countries collected between 1977 and 2013 were analysed. One thousand twenty deaths were recorded for children with anthropometric deficits. Pooled meta-analysis estimates showed no differences by age in absolute mortality risk for wasting (RR 1.08, p = 0.826 for MUAC < 125 mm; RR 1.35, p = 0.272 for WHZ < -2). For underweight and stunting, absolute risk of death was higher in younger (RR 2.57, p < 0.001) compared with older children (RR 2.83, p < 0.001). For all deficits, there were no differences in mortality risk for girls compared with boys. There were no differences in the risk of mortality between younger and older wasted children, supporting continued inclusion of all children under-five in wasting treatment programmes. The risk of mortality associated with underweight and stunting was higher among younger children, suggesting that prevention programmes might be justified in focusing on younger children where resources are limited. There were no sex differences by age in mortality risk for all deficits.

Widespread elevated concentrations of gaseous elemental mercury in Guanajuato, Mexico, centuries after historical silver refining by mercury amalgamation.

Silver (Ag) production in Hispanic America between the 16th and 19th centuries is thought to be one of the largest sources of anthropogenic mercury (Hg) emissions in history. Recent reviews of the chemistry behind the patio process, which used Hg amalgamation to extract Ag from ore, reveal that a large amount of the Hg may not have been immediately released to the atmosphere; instead, it may have been captured in the form of calomel (Hg2Cl2, in which Hg exists as monovalent HgI) and remained in the local environment. Here we show that Hg used in the patio process centuries ago in the Guanajuato Mining District of Mexico continues to elevate present-day concentrations of gaseous elemental mercury (GEM) throughout the region. In the ground-level air, GEM ranged from 8 to 454 ng m-3, exceeding the Northern Hemispheric average (~1.4 ng m-3) by up to two orders of magnitude. Much higher concentrations, up to 44,700 ng m-3, were found in the interstitial air of reprocessed mineral wastes, sediment, and soil. These highly elevated present-day GEM values are due, at least in part, to the disproportionation of legacy calomel, as supported by the presence of HgI in the reprocessed wastes and by the GEM release pattern from calomel disproportionation. Our results imply that the contribution of historical Ag refining to atmospheric Hg emissions must be re-evaluated to account for calomel and its subsequent disproportionation and releases of GEM to the present-day.

Exceptional parallelisms characterize the evolutionary transition to live birth in phrynosomatid lizards.

Viviparity, an innovation enhancing maternal control over developing embryos, has evolved >150 times in vertebrates, and has been proposed as an adaptation to inhabit cold habitats. Yet, the behavioral, physiological, morphological, and life history features associated with live-bearing remain unclear. Here, we capitalize on repeated origins of viviparity in phrynosomatid lizards to tease apart the phenotypic patterns associated with this innovation. Using data from 125 species and phylogenetic approaches, we find that viviparous phrynosomatids repeatedly evolved a more cool-adjusted thermal physiology than their oviparous relatives. Through precise thermoregulatory behavior viviparous phrynosomatids are cool-adjusted even in warm environments, and oviparous phrynosomatids warm-adjusted even in cool environments. Convergent behavioral shifts in viviparous species reduce energetic demand during activity, which may help offset the costs of protracted gestation. Whereas dam and offspring body size are similar among both parity modes, annual fecundity repeatedly decreases in viviparous lineages. Thus, viviparity is associated with a lower energetic allocation into production. Together, our results indicate that oviparity and viviparity are on opposing ends of the fast-slow life history continuum in both warm and cool environments. In this sense, the 'cold climate hypothesis' fits into a broader range of energetic/life history trade-offs that influence transitions to viviparity.

Child wasting before and after age two years: A cross-sectional study of 94 countries.

Background: Wasting reflects infections and poor nutrition and affects almost 50 million children at any given time. Wasting comes with immediate risk of mortality and increased risks for long-term negative consequences for development. Children under two are particularly sensitive to undernutrition and infections. We estimated the age patterning in wasting prevalence. Methods: We calculated wasting prevalence and used Poisson regression models to estimate prevalence ratios comparing prevalence in children under and over two years using data from Demographic and Health Surveys and Multiple Indicator Cluster Surveys from 94 mostly low- and middle-income countries, including 804,172 children under five, born to a nationally representative sample of women 15-49 years old. Wasting prevalence was defined as the percentage of children with weight-for-height below -2 z-score from the median of the WHO 2006 growth standard. Findings: Wasting prevalence for children under two was 14% (95% CI: 13, 14) while it was 9% (95% CI: 9, 9) for children 2-4 years old-leading to a prevalence ratio of 0·66 (95% CI: 0·64, 0·67) in our pooled sample. Prevalence ratios were less than one, indicating lower prevalence in children over two, in 87 countries and statistically significantly lower than one at a 5% level (non-adjusted) in 68 countries. Wasting prevalence was generally lower in children under two for males and females and the wealthiest and poorest households. Interpretation: Since wasting prevalence was observed to be greater among children 0-2 years, and adverse exposure to undernutrition and infections are particularly harmful and interventions are more effective during the 1000 days from conception until age two, nutrition interventions should ensure coverage of children under two through programmatic measures to increase detection and enrollment in wasting programs. Funding: UNICEF, Nutrition Section, Programme Division in New York.

A mathematical model to estimate the incidence of child wasting in Yemen.

INTRODUCTION: The ongoing civil war in Yemen has severely restricted imports of food and fuel, disrupted livelihoods and displaced millions, worsening already high pre-war levels of food insecurity. Paired with frequent outbreaks of disease and a collapsed health system, this has brought rates of wasting in children under five to the country's highest recorded levels, which continue to increase as the crisis worsens and aid becomes increasingly limited. In their planning of services to treat and prevent wasting in children, humanitarian agencies rely on a standard calculation to estimate the expected number of cases for the coming year, where incidence is estimated from prevalence and the average duration of an episode of wasting. The average duration of an episode of moderate and severe wasting is currently estimated at 7.5 months-a globally-used value derived from historical cohort studies. Given that incidence varies considerably by context-where food production and availability, treatment coverage and disease rates all vary-a single estimate cannot be applied to all contexts, and especially not a highly unstable crisis setting such as Yemen. While recent studies have aimed to derive context-specific incidence estimates in several countries, little has been done to estimate the incidence of both moderate and severe wasting in Yemen. METHODS: In order to provide context-specific estimates of the average duration of an episode, and resultingly, incidence correction factors for moderate and severe wasting, we have developed a Markov model. Model inputs were estimated using a combination of treatment admission and outcome records compiled by the Yemen Nutrition Cluster, 2018 and 2019 SMART surveys, and other estimates from the literature. The model derived estimates for the governorate of Lahj, Yemen; it was initialized using August 2018 SMART survey prevalence data and run until October 2019-the date of the subsequent SMART survey. Using a process of repeated model calibration, the incidence correction factors for severe wasting and moderate wasting were found, validating the resulting prevalence against the recorded value from the 2019 SMART survey. RESULTS: The average durations of an episode of moderate and severe wasting were estimated at 4.86 months, for an incidence correction factor k of 2.59, and 3.86 months, for an incidence correction factor k of 3.11, respectively. It was found that the annual caseload of moderate wasting was 36% higher and the annual caseload of severe wasting 58% higher than the originally-assumed values, estimated with k = 1.6. CONCLUSION: The model-derived incidence rates, consistent with findings from other contexts that a global incidence correction factor cannot be sufficient, allow for improved, context-specific estimates of the burden of wasting in Yemen. In crisis settings such as Yemen where funding and resources are extremely limited, the model's outputs holistically capture the burden of wasting in a way that may guide effective decision-making and may help ensure that limited resources are allocated most effectively.

Thermoregulatory strategies of three reclusive lizards (genus Xantusia) from the Baja California peninsula, Mexico, under current and future microenvironmental temperatures.

The thermal quality of the habitat is key for the regulation of body temperature in terrestrial ectotherms and, therefore, permits them to carry out their fundamental biological activities. In thermally heterogeneous environments, ectotherms might follow different behavioral or physiological strategies to maintain their body temperature within biologically adequate boundaries, for which they depend on microhabitat selection. These aspects are, thus, relevant in the context of habitat degradation and land-use change. In this study, we characterized the thermal ecology of three lizard species (genus Xantusia) that differ in microhabitat use along the Baja California peninsula, Mexico. We made three predictions: (1) the three species will follow different thermoregulatory strategies according to habitat thermal quality; (2) the thermal requirements and tolerances of these species will match the environmental or microenvironmental thermal conditions; and (3) due to their habitat and range restriction, the species studied will be highly vulnerable to climate change. Our results indicate the existence of thermoregulatory mechanisms in Xantusia to face thermal heterogeneity, including behavioral thermoregulation by choosing different microhabitats, shifts in activity periods, and adaptation to particular high thermal quality microhabitats. Furthermore, despite their association to specific microhabitats and specialized physiology, the studied species will not be adversely affected by climate change, as the increased microenvironmental temperatures will lead to a higher habitat thermal quality and lower costs of thermoregulation. However, we do not discard other indirect adverse effects of climate change not considered in this study.

Effectiveness of management of severe acute malnutrition (SAM) through community health workers as compared to a traditional facility-based model: a cluster randomized controlled trial.

PURPOSE: We compared the impact of management of severe acute malnutrition (SAM) by lady health workers (LHWs) at a community level with the standard CMAM program provided at the health facility. METHODS: A two-arm cluster randomised controlled trial was conducted in a rural district in sindh Pakistan. The primary outcome was recovery from SAM and secondary outcomes were relapse, defaulter and mortality rate. RESULTS: A total of 829 children were recruited in the trial (430 in intervention and 399 in control groups). No significant difference was noted in recovery rate between the intervention and control groups (79.2% vs 85.6%, p = 0.276). Similarly, no significant differences were noted in relapse (p = 0.757), weight gain (p = 0.609), deaths (p = 0.775) and defaulter rate (p = 0.324) across the groups. Compliance of RUTF was significantly higher in the control group (93%) than in the intervention group (87%), p < 0.000. CONCLUSION: Our results showed no impact of SAM treatment on performance indicators of CMAM (recovery, relapse, death and default) between the standard CMAM programme performed at the health facility by the government and NGO staff and the programme performed at health house level by the LHWs in Pakistan. We recommend further robust trials in other settings to confirm our results.

Improving estimates of the burden of severe wasting: analysis of secondary prevalence and incidence data from 352 sites.

INTRODUCTION: Estimates of incident cases of severe wasting among young children are not available for most settings but are needed for optimal planning of treatment programmes and burden estimation. To improve programme planning, global guidance recommends a single 'incidence correction factor' of 1.6 be applied to available prevalence estimates to account for incident cases. This study aimed to update estimates of the incidence correction factor to improve programme planning and inform the approach to burden estimation for severe wasting. METHODS: A global call was issued for secondary data from severe wasting treatment programmes including prevalence, population size, programme admission and programme coverage through a UNICEF-led effort. Site-specific incidence correction factors were calculated as the number of incident cases (annual programme admissions/programme coverage) divided by the number of prevalent cases (prevalence*population size). Estimates were aggregated by country, region and overall using inverse-variance weighted random-effects meta-analysis. RESULTS: We estimated incidence correction factors from 352 sites in 20 countries. Estimates aggregated by country ranged from 1.3 (Nigeria) to 30.1 (Burundi). Excluding implausible values, the overall incidence correction factor was 3.6 (95% CI 3.4 to 3.9). CONCLUSION: Our results suggest that incidence correction factors vary between sites and that the burden of severe wasting will often be underestimated using the currently recommended incidence correction factor of 1.6. Application of updated incidence correction factors represents a simple way to improve programme planning when incidence data are not available and could inform the approach to burden estimation.

A new species of Lepidophyma (Squamata: Xantusiidae) from San Luis Potosí, México, with notes on its physiological ecology.

In recent years, there has been an increase in the descriptions of members of the lizard genus Lepidophyma. Herein, we describe a new species of Lepidophyma from the Huasteca Potosina region of Mexico, previously confused with L. gaigeae, from which it differs in lacking parietal spot, among other characteristics. We inferred its phylogenetic position and provide information on its thermal and hydric physiology, as well as on some other aspects of natural history. Molecular and morphological data supported the independent taxonomic status of the new species, indicating its placement as the sister taxon of L. gaigeae and a wide morphological separation between these species. Lepidophyma lusca sp. nov. has a diurnal-crepuscular activity period and occurs at lower elevations than L. gaigeae. Also, the new species differ from its sister taxon in its physiology, as reflected by its tendency toward higher thermal parameters and water loss rates. With the description of L. lusca sp. nov., the number of species in the genus Lepidophyma rises to 21.

Thermal physiology responds to interannual temperature shifts in a montane horned lizard, Phrynosoma orbiculare.

As climate change marches on, rapidly rising temperatures shatter records every year, presenting ever-growing physiological challenges to organisms worldwide. Ectotherms rely on behavioral and physiological plasticity to contend with environmental fluctuations. Nonetheless, our understanding of thermal plasticity has been largely limited to laboratory settings. Here, we test whether aspects of thermal physiology respond to interannual shifts in thermal environment in a natural population of Phrynosoma orbiculare, a montane horned lizard, from Hidalgo, Mexico. At our field site, 2019 was markedly warmer than the year that preceded it. We detected population-level increases in three key thermal physiological traits: preferred temperature, the critical thermal minimum, and the critical thermal maximum. Thus, thermal phenotypes appear to shift in tandem in response to environmental fluctuations. A subset of individuals were resampled across years, allowing insight into plastic shifts within an organism's lifetime. We detected parallel increases in these lizards for the preferred temperature and the critical thermal minimum, but not for the critical thermal maximum. Our results support a growing body of literature indicating that preferred conditions and cold tolerance can be highly labile over the course of an organism's lifetime, whereas hardening over shorter time periods is more common for heat tolerance. Given that heat tolerance increased at the population-level, but not in resampled individuals, it is possible that rapid evolution occurred due to temperature increases. In short, physiological shifts can be observed in natural populations over relatively short timespans, and these shifts might reflect a combination of evolutionary and acclimatory responses.

Bringing severe acute malnutrition treatment close to households through community health workers can lead to early admissions and improved discharge outcomes.

Severe acute malnutrition (SAM) affects over 16.6 million children worldwide. The integrated Community Case Management (iCCM) strategy seeks to improve essential health by means of nonmedical community health workers (CHWs) who treat the deadliest infectious diseases in remote rural areas where there is no nearby health center. The objective of this study was to assess whether SAM treatment delivered by CHWs close to families' locations may improve the early identification of cases compared to outpatient treatment at health facilities (HFs), with a decreased number complicated cases referred to stabilization centers, increased anthropometric measurements at admission (closer to the admission threshold) and similarity in clinical outcomes (cure, death, and default). The study included 930 children aged 6 to 59 months suffering from SAM in the Kita district of the Kayes Region in Mali; 552 children were treated by trained CHWs. Anthropometric measurements, the presence of edema, and other medical signs were recorded at admission, and the length of stay and clinical outcomes were recorded at discharge. The results showed fewer children with edema at admission in the CHW group than in the HF group (0.4% vs. 3.7%; OR = 10.585 [2.222-50.416], p = 0.003). Anthropometric measurements at admission were higher in the CHW group, with fewer children falling into the lowest quartiles of both weight-for-height z-scores (20.2% vs. 31.5%; p = 0.002) and mid-upper arm circumference (18.0% vs. 32.4%; p<0.001), than in the HF group. There was no difference in the length of stay. More children in the CHW group were cured (95.9% vs. 88.7%; RR = 3.311 [1.772-6.185]; p<0.001), and there were fewer defaulters (3.7% vs. 9.8%; RR = 3.345 [1.702-6.577]; p<0.001) than in the HF group. Regression analyses demonstrated that less severe anthropometric measurements at admission resulted in an increased probability of cure at discharge. The study results also showed that CHWs provided more integrated care, as they diagnosed and treated significantly more cases of infectious diseases than HFs (diarrhea: 36.0% vs. 18.3%, p<0.001; malaria: 41.7% vs. 19.8%, p<0.001; acute respiratory infection: 34.8% vs. 25.2%, p = 0.007). The addition of SAM treatment in the curative tasks that the CHWs provided to the families resulted in earlier admission and more integrated care for children than those associated with HFs. CHW treatment also achieved better discharge outcomes than standard community treatment.

Influence of Al Alloying on the Electrochemical Behavior of Zn Electrodes for Zn-Air Batteries With Neutral Sodium Chloride Electrolyte.

Zn alloy electrodes containing 10 wt. % Al were prepared to examine the applicability as anodes in primary Zn-air batteries with neutral 2M NaCl electrolyte. These electrodes were investigated by electrochemical measurements and microscopic techniques (SEM, LSM, AFM). Based on the cyclic voltammetry and intermediate term (24 h) discharge experiments, the only active element in the as-prepared alloy was found to be Zn. It was further confirmed by LSM that Zn rich areas dissolved while Al remained passive during discharge. The passive state of Al was also demonstrated by conductive AFM investigations on the as-cast alloy surfaces. The results on potentiodynamic polarization and weight loss measurements indicated that the alloy electrode was less prone to corrosion than pure Zn electrode. The electrochemical behavior of the electrodes was modified under certain cathodic polarization previous to measurements. Accordingly, originating from Al activation due to application of cathodic potentials, potentiodynamic polarization studies showed a clear shift on the corrosion potentials of the alloy toward more negative values. On the basis of these results, with the precondition of Al activation prior to discharge experiments, the effect of Al alloying on the Zn electrodes was revealed as temporarily enhanced potentials on the discharge profiles in comparison to pure Zn electrodes.

Interactions between thermoregulatory behavior and physiological acclimatization in a wild lizard population.

Although the importance of thermoregulation and plasticity as compensatory mechanisms for climate change has long been recognized, they have largely been studied independently. Thus, we know comparatively little about how they interact to shape physiological variation in natural populations. Here, we test the hypothesis that behavioral thermoregulation and thermal acclimatization interact to shape physiological phenotypes in a natural population of the diurnal lizard, Sceloporus torquatus. Every month for one year we examined thermoregulatory effectiveness and changes in the population mean in three physiological parameters: cold tolerance (Ctmin), heat tolerance (Ctmax), and the preferred body temperature (Tpref), to indirectly assess thermal acclimatization in population means. We discovered that S. torquatus is an active thermoregulator throughout the year, with body temperature varying little despite strong seasonal temperature shifts. Although we did not observe a strong signal of acclimatization in Ctmax, we did find that Ctmin shifts in parallel with nighttime temperatures throughout the year. This likely occurs, at least in part, because thermoregulation is substantially less effective at buffering organisms from selection on lower physiological limits than upper physiological limits. Active thermoregulation is effective at limiting exposure to extreme temperatures during the day, but is less effective at night, potentially contributing to greater plasticity in Ctmin than Ctmax. Importantly, however, Tpref tracked seasonal changes in temperature, which is one the factors contributing to highly effective thermoregulation throughout the year. Thus, behavior and physiological plasticity do not always operate independently, which could impact how organisms can respond to rising temperatures.