Handgrip strength is associated with 12-month survival in male patients suffering with advanced chronic liver disease.

BACKGROUND: Advanced chronic liver disease (ACLD) patients are usually malnourished, and both conditions in combination increase the likelihood of unfavourable clinical outcomes. Handgrip strength (HGS) has been suggested as a relevant parameter for nutritional assessment and predictor of adverse clinical outcomes in ACLD. However, the HGS cut-off values for ACLD patients have not yet been reliably established. The aims of this study were to preliminarily identify HGS reference values in a sample population of ACLD male patients and to assess their association with survival over a 12-month follow-up period. METHODS: This was a prospective observational study with preliminary analysis of outpatients and inpatients. A total of 185 male patients with a medical diagnosis of ACLD met the inclusion criteria and were invited to participate in the study. The physiological variation in muscle strength related to the age of the individuals included in the study was considered to obtain cut-off values. RESULTS: After categorising HGS by age group (adults: 18-60 years; elderly: ≥60 years), the reference values obtained were 32.5 kg for the adults and 16.5 kg for the elderly. During the 12-month follow-up, 20.5% of the patients died, and 76.3% of those had been identified with reduced HGS. CONCLUSIONS: Patients with adequate HGS showed significantly higher 12-month survival than those with reduced HGS within the same period. Our findings show that HGS is an important predictive parameter for clinical and nutritional follow-up in ACLD male patients.

RISK FACTORS FOR HEPATOCELLULAR CARCINOMA IN PATIENTS WITH NON-ALCOHOLIC FATTY LIVER DISEASE.

Non-alcoholic fatty liver disease is growing in worldwide prevalence and thus, is expected to have a higher number of NAFLD-related hepatocellular carcinoma (HCC) in the following years. This review describes the risk factors associated with HCC in NAFLD-patients. The presence of liver cirrhosis is the preponderant one. Male gender, PNPLA3 variants, diabetes, and obesity also appear to predispose to the development of HCC, even in non-cirrhotic subjects. Thus far, intensive lifestyle modifications, including glycemic control, and obesity treatment, are effective therapies for NAFLD/ non-alcoholic steatohepatitis and, therefore, probably, also for HCC. Some drugs that aimed at decreasing inflammatory activity and fibrosis, as well as obesity, were studied. Other data have suggested the possibility of HCC chemoprevention. So far, however, there is no definitive evidence for the routine utilization of these drugs. We hope, in the future, to be able to profile patients at higher risk of NAFLD-HCC and outline strategies for early diagnosis and prevention.

Fatores de risco para carcinoma hepatocelular em pacientes com doença gordurosa não alcóolica do fígado / Risk factors for hepatocellular carcinoma in patients with non-alcoholic fatty liver disease

ABSTRACT Non-alcoholic fatty liver disease is growing in worldwide prevalence and thus, is expected to have a higher number of NAFLD-related hepatocellular carcinoma (HCC) in the following years. This review describes the risk factors associated with HCC in NAFLD-patients. The presence of liver cirrhosis is the preponderant one. Male gender, PNPLA3 variants, diabetes, and obesity also appear to predispose to the development of HCC, even in non-cirrhotic subjects. Thus far, intensive lifestyle modifications, including glycemic control, and obesity treatment, are effective therapies for NAFLD/ non-alcoholic steatohepatitis and, therefore, probably, also for HCC. Some drugs that aimed at decreasing inflammatory activity and fibrosis, as well as obesity, were studied. Other data have suggested the possibility of HCC chemoprevention. So far, however, there is no definitive evidence for the routine utilization of these drugs. We hope, in the future, to be able to profile patients at higher risk of NAFLD-HCC and outline strategies for early diagnosis and prevention.

RESUMO A doença metabólica e doença hepática gordurosa metabólica estão aumentando a prevalência mundial e, portanto, espera-se um número maior de carcinoma hepatocelular (CHC) relacionado à doença hepática gordurosa não alcóolica (DHGNA) nos próximos anos. Esta revisão descreve os fatores de risco associados ao CHC em pacientes com DHGNA. A presença de cirrose hepática é a preponderante. Sexo masculino, variantes do gene PNPLA3, diabetes e obesidade também parecem predispor ao desenvolvimento de CHC, mesmo em indivíduos não cirróticos. Até agora, modificações significativas no estilo de vida, incluindo controle glicêmico e tratamento da obesidade, são terapias eficazes para DHGNA/ Esteatohepatite não-alcoolica e, portanto, provavelmente, também para CHC. Alguns medicamentos que propunham-se diminuir a atividade inflamatória e fibrose, bem como a obesidade, foram estudados. Outros dados sugeriram a possibilidade de quimioprevenção do CHC. Até o momento, no entanto, não há evidências definitivas para o uso rotineiro desses medicamentos. Esperamos, no futuro, poder traçar o perfil de pacientes com maior risco de DHGNA-CHC e traçar estratégias para diagnóstico precoce e prevenção.

BETTER LIVING DONOR LIVER TRANSPLANTATION PATIENT SURVIVAL COMPARED TO DECEASED DONOR - A SYSTEMATIC REVIEW AND META-ANALYSIS.

BACKGROUND: Deceased donor liver transplantation (DDLT) is the first choice, but living donor transplantation (LDLT) is an alternative to be considered in special situations, such as lack of donated organs and emergencies. So far, there is no consensus on which transplantation method provides better survival and fewer complications, which is still an open point for discussion. METHODS: This meta-analysis compared the 1, 3, and 5-year patient and graft survival rates of LDLT and DDLT. We included studies published from April-2009 to June-2021 and adopted the generic model of the inverse of variance for the random effect of hazard ratios. The adequacy of the studies was determined using the Newcastle-Ottawa Scale - NOS (WELLS). RESULTS: For patient survival analysis, we included a total of 32,258 subjects. We found a statistically significant better survival for the LDLT group at 1, 3 and 5 years, respectively: 1.35 HR (95%CI 1.10-1.66, P=0.005), 1.26 HR (95%CI 1.09-1.46, P=0.002) and 1.27 HR (95%CI 1.09-1.48, P=0.002). Our meta-analysis evaluated a total of 21,276 grafts. In the overall analysis, the 1-year survival was improved in favor of the LDLT group (1.36 HR, 95%CI 1.16-1.60, P<0.0001), while the 3-year survival (1.13 HR, 95%CI 0.96-1.33, P<0.13), and 5 (0.99 HR, 95%CI 0.74-1.33, P<0.96), did not differ significantly. CONCLUSION: This metanalysis detected a statistically significant greater 1-, 3- and 5-years patient survival favoring LDLT compared to DDLT as well as a statistically significant difference better 1-year graft survival favoring the LDLT group.

Sobrevida de pacientes submetidos ao transplante hepático com enxerto de doador vivo é melhor em comparação com doador falecido — uma revisão sistemática e meta-análise / Better living donor liver transplantation patient survival compared to deceased donor — a systematic review and meta-analysis

ABSTRACT Background Deceased donor liver transplantation (DDLT) is the first choice, but living donor transplantation (LDLT) is an alternative to be considered in special situations, such as lack of donated organs and emergencies. So far, there is no consensus on which transplantation method provides better survival and fewer complications, which is still an open point for discussion. Methods This meta-analysis compared the 1, 3, and 5-year patient and graft survival rates of LDLT and DDLT. We included studies published from April-2009 to June-2021 and adopted the generic model of the inverse of variance for the random effect of hazard ratios. The adequacy of the studies was determined using the Newcastle-Ottawa Scale — NOS (WELLS). Results For patient survival analysis, we included a total of 32,258 subjects. We found a statistically significant better survival for the LDLT group at 1, 3 and 5 years, respectively: 1.35 HR (95%CI 1.10—1.66, P=0.005), 1.26 HR (95%CI 1.09—1.46, P=0.002) and 1.27 HR (95%CI 1.09—1.48, P=0.002). Our meta-analysis evaluated a total of 21,276 grafts. In the overall analysis, the 1-year survival was improved in favor of the LDLT group (1.36 HR, 95%CI 1.16—1.60, P<0.0001), while the 3-year survival (1.13 HR, 95%CI 0.96—1.33, P<0.13), and 5 (0.99 HR, 95%CI 0.74—1.33, P<0.96), did not differ significantly. Conclusion This metanalysis detected a statistically significant greater 1-, 3- and 5-years patient survival favoring LDLT compared to DDLT as well as a statistically significant difference better 1-year graft survival favoring the LDLT group.

RESUMO Contexto O transplante de fígado com doador falecido é a primeira escolha, mas o transplante de doador vivo é uma alternativa a ser considerada em situações especiais, como falta de órgãos doados e emergências. Até o momento, não há consenso sobre qual método de transplante proporciona melhor sobrevida e menos complicações, sendo, ainda, um ponto em aberto para discussão. Métodos Esta meta-análise comparou as taxas de sobrevida de pacientes e enxertos de 1, 3 e 5 anos de transplante de doador vivo e transplante de fígado com doador falecido. Incluímos estudos publicados de abril de 2009 a junho de 2021 e adotamos o modelo genérico do inverso da variância para o efeito aleatório das razões de risco. A adequação dos estudos foi determinada por meio da Escala de Newcastle-Ottawa — NOS (WELLS). Resultados Para análise de sobrevida do paciente, incluímos um total de 32.258 indivíduos. Encontramos uma melhor sobrevida estatisticamente significativa para o grupo de transplante de fígado de doador vivo em 1, 3 e 5 anos, respectivamente: 1,35 HR (IC95% 1,10—1,66, P=0,005), 1,26 HR (IC95% 1,09—1,46, P=0,002) e 1,27 HR (IC95% 1,09—1,48, P=0,002). Nossa meta-análise avaliou um total de 21.276 enxertos. Na análise geral, a sobrevida em 1 ano foi melhorada em favor do grupo de transplante de doador vivo (1,36 HR, IC95% 1,16—1,60, P<0,0001), enquanto a sobrevida em 3 anos (1,13 HR, IC95% 0,96—1,33, P<0,13) e 5 (0,99 HR, IC95% 0,74—1,33, P<0,96), não diferiram significativamente. Conclusão Esta meta-análise detectou uma sobrevida estatisticamente significativa maior do paciente em 1, 3 e 5 anos favorecendo o transplante de doador vivo em comparação com o transplante de fígado com doador falecido, bem como uma diferença estatisticamente significativa melhor na sobrevida do enxerto em 1 ano favorecendo o grupo de transplante de doador vivo.

How Does Cognitive Effort Influence the Tactical Behavior of Soccer Players?

In the present study, we aimed to investigate the association between soccer players' cognitive effort and their tactical behavior. We assessed 52 young male soccer players from a first division Brazilian club, using FUT-SAT to evaluate tactical behavior efficiency and Mobile Eye Tracking-XG software and a video test protocol to measure pupillary behavior and cognitive effort. Following data collection, statistical analyses were performed using the Kolmogorov-Smirnov normality test, and linear regression. We found a high inverse association between cognitive effort and tactical behavior efficiency; players with less cognitive effort during the task displayed higher values of tactical behavior efficiency on the field. We concluded that sustaining less cognitive effort in game situations helped players realize better tactical behavior and enabled better performance.

Plant water uptake from soil through a vapor pathway.

Water uptake from the soil via a vapor pathway was tested. Viburnum suspensum L. plants were divided into: (1) irrigated, (2) drought with vapor and (3) drought without vapor treatments. Each plant was placed into a larger bucket containing deuterium-labeled water as a vapor source (vapor treatment) or no water (drought and irrigation treatments). We also tested whether uptake via a vapor pathway could mitigate drought effects. Net CO2 assimilation (A), transpiration (E) and stomatal conductance (gs) were measured daily until the first visible signs of stress. Soil water content, stem water potential (Ψ) and the stable hydrogen isotope ratio (δ2 H) of soil and plant xylem water were then measured in all treatments. We show that water is taken up by plants through the vapor phase in dry soils. The δ2 H values of the soil water in the vapor treatment were highly enriched compared to the background isotope ratios of the non-vapor exposed irrigated and drought treatments. Stem water δ2 H values for the vapor treatment were significantly greater than those for irrigation and drought treatments not exposed to isotopically enriched vapor. In this experiment, movement of water to the plant via the vapor phase did not mitigate drought effects. A, E, plant Ψ and gs significantly decreased in the drought and vapor treatments relative to the controls, with no significant differences between vapor and drought treatments.

Oral health-related quality of life in caregivers of individuals with Cerebral Palsy: a case-control study.

AIM: The object of this study is to evaluate the oral health-related quality of life (OHRQoL) of caregivers of individuals with Cerebral Palsy (CP). METHODS: Ninety-eight caregivers of individuals with CP (SG) and 196 caregivers of individuals without special needs (CG) completed the reduced version of the Oral Health Impact Profile (OHIP-14). In addition, a questionnaire with demographic and socioeconomic questions was used. Groups were matched according to gender, schooling and family income. Fisher's exact tests, Chi square and Mann-Whitney, and bi/multivariate logistic regression were used (p < 0.05). RESULTS: The impact on OHRQoL was similar for SG and CG (OHIP-14 total score). For SG, the high negative impact was in the following OHIP domains: "Functional limitation", "Physical disability", "Psychological incapacity" and "Disadvantages". For SG, a higher number of caregivers was single, unemployed, received government financial aid. There was a statistically significant association between the number of children a caregiver has and a negative impact on OHRQoL. CONCLUSIONS: Being a caregiver of children with or without CP had a negative impact of similar magnitude on ORHQoL. The negative impact on OHRQoL of caregivers of children with CP was associated with having a high number of children; the higher the number of children, the greater the negative impact on their OHRQoL.

Young Soccer Players With Higher Tactical Knowledge Display Lower Cognitive Effort.

The present study aimed to investigate whether the form and amount of declarative tactical knowledge (DTK) and procedural tactical knowledge (PTK) influence cognitive effort during soccer performance among young players. We assessed 36 male players from a Brazilian first-division soccer club; participants averaged 14.89 ( SD = 1.42) years of age. We evaluated DTK from video simulation tests and PTK through the System of Tactical Assessment in Soccer. We assessed cognitive effort by measures of pupil diameter using Mobile Eye Tracking-XG while players viewed soccer video scenes and made game-related play decisions. After the assessment of tactical knowledge, we categorized the sample according to players' tactical knowledge into participants with higher and lower PTK and higher and lower DTK. Subsequently, we examined the both PTK and DTK groups on cognitive effort. Our results suggest that tactical knowledge influences cognitive effort in that players with higher PTK and DTK displayed less cognitive effort during soccer performance tasks. In conclusion, we observed that PTK and DTK influenced the cognitive effort younger soccer players expended while viewing soccer scenes and making soccer performance decisions.

Water uptake of Alaskan tundra evergreens during the winter-spring transition.

PREMISE OF THE STUDY: The cold season in the Arctic extends over 8 to 9 mo, yet little is known about vascular plant physiology during this period. Evergreen species photosynthesize under the snow, implying that they are exchanging water with the atmosphere. However, liquid water available for plant uptake may be limited at this time. The study objective was to determine whether evergreen plants are actively taking up water while under snow and/or immediately following snowmelt during spring thaw. METHODS: In two in situ experiments, one at the plot level and another at the individual species level, (2)H-labeled water was used as a tracer injected beneath the snow, after which plant stems and leaves were tested for the presence of the label. In separate experiments, excised shoots of evergreen species were exposed to (2)H-labeled water for ∼5 s or 60 min and tested for foliar uptake of the label. KEY RESULTS: In both the plot-level and the species-level experiments, some (2)H-labeled water was found in leaves and stems. Additionally, excised individual plant shoots exposed to labeled water for 60 min took up significantly more (2)H-label than shoots exposed ∼5 s. CONCLUSIONS: Evergreen tundra plants take up water under snow cover, some via roots, but also likely by foliar uptake. The ability to take up water in the subnivean environment allows evergreen tundra plants to take advantage of mild spring conditions under the snow and replenish carbon lost by winter respiration.

Are leaf physiological traits related to leaf water isotopic enrichment in restinga woody species?

During plant-transpiration, water molecules having the lighter stable isotopes of oxygen and hydrogen evaporate and diffuse at a faster rate through the stomata than molecules having the heavier isotopes, which cause isotopic enrichment of leaf water. Although previous models have assumed that leaf water is well-mixed and isotopically uniform, non-uniform stomatal closure, promoting different enrichments between cells, and different pools of water within leaves, due to morpho-physiological traits, might lead to inaccuracies in isotopic models predicting leaf water enrichment. We evaluate the role of leaf morpho-physiological traits on leaf water isotopic enrichment in woody species occurring in a coastal vegetation of Brazil known as restinga. Hydrogen and oxygen stable isotope values of soil, plant stem and leaf water and leaf traits were measured in six species from restinga vegetation during a drought and a wet period. Leaf water isotopic enrichment relative to stem water was more homogeneous among species during the drought in contrast to the wet period suggesting convergent responses to deal to temporal heterogeneity in water availability. Average leaf water isotopic enrichment relative to stem water during the drought period was highly correlated with relative apoplastic water content. We discuss this observation in the context of current models of leaf water isotopic enrichment as a function of the Péclet effect. We suggest that future studies should include relative apoplastic water content in isotopic models.

Aphids alter host-plant nitrogen isotope fractionation.

Plant sap-feeding insects and blood-feeding parasites are frequently depleted in (15)N relative to their diet. Unfortunately, most fluid-feeder/host nitrogen stable-isotope studies simply report stable-isotope signatures, but few attempt to elucidate the mechanism of isotopic trophic depletion. Here we address this deficit by investigating the nitrogen stable-isotope dynamics of a fluid-feeding herbivore-host plant system: the green peach aphid, Myzus persicae, feeding on multiple brassicaceous host plants. M. persicae was consistently more than 6‰ depleted in (15)N relative to their hosts, although aphid colonized plants were 1.5‰ to 2.0‰ enriched in (15)N relative to uncolonized control plants. Isotopic depletion of aphids relative to hosts was strongly related to host nitrogen content. We tested whether the concomitant aphid (15)N depletion and host (15)N enrichment was coupled by isotopic mass balance and determined that aphid (15)N depletion and host (15)N enrichment are uncoupled processes. We hypothesized that colonized plants would have higher nitrate reductase activity than uncolonized plants because previous studies had demonstrated that high nitrate reductase activity under substrate-limiting conditions can result in increased plant δ(15)N values. Consistent with our hypothesis, nitrate reductase activity in colonized plants was twice that of uncolonized plants. This study offers two important insights that are likely applicable to understanding nitrogen dynamics in fluid-feeder/host systems. First, isotopic separation of aphid and host depends on nitrogen availability. Second, aphid colonization alters host nitrogen metabolism and subsequently host nitrogen stable-isotope signature. Notably, this work establishes a metabolic framework for future hypothesis-driven studies focused on aphid manipulation of host nitrogen metabolism.

Lake and watershed characteristics rather than climate influence nutrient limitation in shallow lakes.

Both nitrogen (N) and phosphorus (P) can limit primary production in shallow lakes, but it is still debated how the importance of N and P varies in time and space. We sampled 83 shallow lakes along a latitudinal gradient (5 degrees 55 degrees S) in South America and assessed the potential nutrient limitation using different methods including nutrient ratios in sediment, water, and seston, dissolved nutrient concentrations, and occurrence of N-fixing cyanobacteria. We found that local characteristics such as soil type and associated land use in the catchment, hydrology, and also the presence of abundant submerged macrophyte growth influenced N and P limitation. We found neither a consistent variation in nutrient limitation nor indications for a steady change in denitrification along the latitudinal gradient. Contrary to findings in other regions, we did not find a relationship between the occurrence of (N-fixing and non-N-fixing) cyanobacteria and the TN:TP ratio. We found N-fixing cyanobacteria (those with heterocysts) exclusively in lakes with dissolved inorganic nitrogen (DIN) concentrations of < 100 microg/L, but notably they were also often absent in lakes with low DIN concentrations. We argue that local factors such as land use and hydrology have a stronger influence on which nutrient is limiting than climate. Furthermore, our data show that in a wide range of climates N limitation does not necessarily lead to cyanobacterial dominance.

Ephemeral clonal integration in Calathea marantifolia (Marantaceae): Evidence of diminished integration over time.

A major advantage of clonal growth forms is the intergenerational transfer of resources through vascular connections (clonal integration). Connections linking ramets can be persistent or ephemeral. For species with ephemeral connections, whether the extent of clonal integration changes over time is unclear. To address this issue, we tracked water movement using an isotopic label and assessed the demographic performance of parent and offspring ramets over time in a severing experiment. Our study system was the understory herb Calathea marantifolia, which has parent ramets that produce vegetative bulbils (clonal offspring) that pass through distinct pre- and post-rooting stages. Little water was transported between parents and offspring, and the direction of movement was primarily from parent to pre-rooting offspring. Anatomical observations of inter-ramet connections showed that vascular bundles were twice as abundant in parent stems compared to inter-ramet connections. Severing inter-ramet connections reduced the growth of offspring ramets but not parents. Survival of pre-rooting offspring was reduced by 10% due to severing, but post-rooting offspring were not affected. Our results suggest that offspring ramets of C. marantifolia are weaned from their parent as they progress from pre- to post-rooting stages.

Seasonal plant water uptake patterns in the saline southeast Everglades ecotone.

The purpose of this study was to determine the seasonal water use patterns of dominant macrophytes coexisting in the coastal Everglades ecotone. We measured the stable isotope signatures in plant xylem water of Rhizophora mangle, Cladium jamaicense, and Sesuvium portulacastrum during the dry (DS) and wet (WS) seasons in the estuarine ecotone along Taylor River in Everglades National Park, FL, USA. Shallow soilwater and deeper groundwater salinity was also measured to extrapolate the salinity encountered by plants at their rooting zone. Average soil water oxygen isotope ratios (delta(18)O) was enriched (4.8 +/- 0.2 per thousand) in the DS relative to the WS (0.0 +/- 0.1 per thousand), but groundwater delta(18)O remained constant between seasons (DS: 2.2 +/- 0.4 per thousand; WS: 2.1 +/- 0.1 per thousand). There was an inversion in interstitial salinity patterns across the soil profile between seasons. In the DS, shallow water was euhaline [i.e., 43 practical salinity units (PSU)] while groundwater was less saline (18 PSU). In the WS, however, shallow water was fresh (i.e., 0 PSU) but groundwater remained brackish (14 PSU). All plants utilized 100% (shallow) freshwater during the WS, but in the DS R. mangle switched to a soil-groundwater mix (delta 55% groundwater) while C. jamaicense and S. portulacastrum continued to use euhaline shallow water. In the DS, based on delta(18)O data, the roots of R. mangle roots were exposed to salinities of 25.4 +/- 1.4 PSU, less saline than either C. jamaicense (39.1 +/- 2.2 PSU) or S. portulacastrum (38.6 +/- 2.5 PSU). Although the salinity tolerance of C. jamaicense is not known, it is unlikely that long-term exposure to high salinity is conducive to the persistence of this freshwater marsh sedge. This study increases our ecological understanding of how water uptake patterns of individual plants can contribute to ecosystem levels changes, not only in the southeast saline Everglades, but also in estuaries in general in response to global sea level rise and human-induced changes in freshwater flows.

Plants use macronutrients accumulated in leaf-cutting ant nests.

Leaf-cutting ants (Atta spp.) are known for their extensive defoliation in neo-tropical forests and savannahs. Debate about the costs and benefits of their activities has been largely dominated by their detrimental effects on agriculture and agroforestry. However, the large accumulation of nutrients and changes in soil properties near their nests might benefit plants growing near them. Here, we test whether trees use nutrients that accumulate in debris piles near, or refuse chambers within, leaf-cutting ant nests. At two tropical sites (a moist tropical forest site in Panama and a savannah site in Brazil), we fed leaves labelled with the stable isotope 15N to two species of leaf-cutting ants (Atta colombica and Atta laevigata) and traced the stable isotope label in plants surrounding the two nests. Thus, we show that plants in both sites access resources associated with Atta nests. In addition, leaf tissue of trees near the nests labelled with 15N had significantly higher calcium concentrations than those of distal, unlabelled conspecifics. It has been documented that calcium is a limiting macronutrient in tropical forests and savannahs. Atta may thus play an important ecological role through their long-distance transport, redistribution and concentration of critical macronutrients.

A faster plant stem-water extraction method.

Oxygen and hydrogen isotope ratios of stem water have been used by several studies which relate the ecophysiology of plants to their water source. Undoubtedly, there are several other applications and research areas which could use this type of analysis. However, the most often used methods of extracting stem water are slow, limiting the rate of sampling and consequently preventing a deeper understanding of spatial and temporal plant water source use. We have developed a faster batch method of stem-water extraction and compare it with the most commonly used online method of stem-water extraction. Samples are sealed in 18 cm long ampoules having their extremities placed sample end in a heating block and the condensing end in a cooling block, and allowed to distill overnight. Up to 72 samples can be distilled overnight and sealed the next morning. The isotope ratios of water distilled by the batch method introduced here compared with those from the online method were in excellent agreement. In addition to being faster, this method does not need the monitoring of hot water baths and liquid nitrogen traps during distillation and does not require a complex vacuum system.

Rainfall exclusion in an eastern Amazonian forest alters soil water movement and depth of water uptake.

Deuterium-labeled water was used to study the effect of the Tapajós Throughfall Exclusion Experiment (TTEE) on soil moisture movement and on depth of water uptake by trees of Coussarea racemosa, Sclerolobium chrysophyllum, and Eschweilera pedicellata. The TTEE simulates an extended dry season in an eastern Amazonian rainforest, a plausible scenario if the El Niño phenomenon changes with climate change. The TTEE excludes 60% of the wet season throughfall from a 1-ha plot (treatment), while the control 1-ha plot receives precipitation year-round. Mean percolation rate of the label peak in the control plot was greater than in the treatment plot during the wet season (0.75 vs. 0.07 m/mo). The rate was similar for both plots during the dry season (ca. 0.15 m/mo), indicative that both plots have similar topsoil structure. Interestingly, the label peak in the control plot during the dry season migrated upward an average distance of 64 cm. We show that water probably moved upward through soil pores-i.e., it did not involve roots (hydraulic lift)-most likely because of a favorable gradient of total (matric + gravitational) potential coupled with sufficient unsaturated hydraulic conductivity. Water probably also moved upward in the treatment plot, but was not detectable; the label in this plot did not percolate below 1 m or beyond the depth of plant water uptake. During the dry season, trees in the rainfall exclusion plot, regardless of species, consistently absorbed water significantly deeper, but never below 1.5-2 m, than trees in the control plot, and therefore may represent expected root function of this understory/subcanopy tree community during extended dry periods.

Preparation and evaluation of zirconia-coated silica monolith for capillary electrochromatography.

Silica monoliths were fabricated inside fused-silica capillaries. Then the monolithic columns were coated with membrane-like zirconia. The zirconia-coated silica monoliths exhibited different EOF behavior comparing with that of bare silica monoliths. The magnitude and direction could be manipulated by changing the running buffers. Due to the amphoteric characteristic of zirconia, the silica monoliths with zirconia surface facilitate the separation of basic compounds. Aromatic amines and alkaloids were separated without obvious peak tailing. The zirconia surface was easily modified with octadecylphosphonic acid for the separation of neutral compounds. Column efficiency as high as 90,000 and 80,000m(-1) was obtained for beberine and naphthalene, respectively. Furthermore, the zirconia coating increased the stability of the monolithic columns. Even after being exposed to severe condition, there was no apparently efficiency decrease for the test samples.

[Advances in solid phase microextraction coupled with high performance liquid chromatography].

Solid phase microextraction (SPME) is a solvent-free technique with high extraction efficiency and easy to perform automatically. It can be coupled with high performance liquid chromatography to perform efficient analysis of compounds with high polarity. The advances in solid phase microextraction coupled with high performance liquid chromatography, including its theory, interfaces, coating materials and applications, are reviewed with 36 references.