RAC Values Research Articles

Use of sequential extraction methods to evaluate the environmental impact of trace metal in the Iraqi coastlines

The geochemical distribution of several trace metals (lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), nickel (Ni), chrome (Cr), cobalt (Co) and iron (Fe)) was investigated using five sequential extraction procedures to provide information on their distribution and environmental impacts on the Iraqi coastal sediments. Sediment samples were collected from 16 sites along the coast to determine the concentrations of the above metals. The concentration and ratios of these metals were estimated in the sediment extract (concentration on the exchange surfaces, carbonates, manganese oxides and iron oxides, organic matter and those associated with the remainder) using extraction methods (magnesium chloride, 1 molar of sodium acetate, 0.5 molar of hydroxylamine hydrochloride, 0.2 molar of ammonium oxalate, concentrated nitric acid and 25% of hydrofluoric acid) to extract and separate the above fractions in order. The results indicated that the total sediment content of Pb and Cd were higher than their rate of occurrence in the crust, while copper, zinc, nickel, chrome, cobalt and iron were within those limits. According to the I-geo the metals Cr, Cu and Zn are considered at unpolluted class while Ni and Pb were ranged from moderately to strongly level. On the other had Cd was found at extremely level as its I-geo exceeded the highest-class value. These metals are bonded to different power bonds. Pb, Cr and Co have dominant in exchangeable and carbonates fraction. Iraqi tidal flats is characterized by very high risk considering Cr, Pb, Co and Cu which represented by RAC values, so they can move to the solution to become available for living.

Enantioselective Toxic Effects of Prothioconazole toward Scenedesmus obliquus.

Prothioconazole (PTC) is a broad-spectrum triazole fungicide with one asymmetric center and consists of two enantiomers, R-(-)-PTC and S-(+)-PTC. To address the concern of its environmental safety, the enantioselective toxic effects of PTC on Scendesmus obliquus (S. obliquus) were investigated. PTC racemates (Rac-PTC) and enantiomers exhibited dose-dependent acute toxicity effects against S. obliquus at a concentration from 1 to 10 mg·L-1. The 72 h-EC50 value of Rac-, R-(-)-, and S-(+)-PTC is 8.15, 16.53, and 7.85 mg·L-1, respectively. The growth ratios and photosynthetic pigment contents of the R-(-)-PTC treatment groups were higher than the Rac- and S-(+)-PTC treatment groups. Both catalase (CAT) activities and esterase activities were inhibited in the Rac- and S-(+)-PTC treatment groups at high concentrations of 5 and 10 mg·L-1, and the levels of malondialdehyde (MDA) were elevated, which exceeded the levels in algal cells for the R-(-)-PTC treatment groups. PTC could disrupt the cell morphology of S. obliquus and induce cell membrane damage, following the order of S-(+)-PTC ≈ Rac-PTC > R-(-)-PTC. The enantioselective toxic effects of PTC on S. obliquus provide essential information for its ecological risk assessment.

Reflexões Epistemológicas e Sobre o Fazer Científico na Administração Contemporânea

ABSTRACT RAC has prioritized studies that advance the scientific debate in the field of contemporary administration, favoring original and interdisciplinary studies with epistemological approaches expanding conceptual boundaries and innovatively connecting theory and practice. RAC values responsible knowledge production that contributes in and out of academia. Given this, it is vital to reinforce a research agenda for administration, broadening the horizons of epistemological and metatheoretical discussions on the content of the knowledge produced and on how this knowledge is produced. Such a research agenda must focus on the field’s scientific practices, the scope and limits, and the consequences of these practices in academia and beyond. This editorial presents some reflections and contributions to thinking about new epistemological paths and supporting the use of new praxeological avenues in the field. The intention is to help consolidate a research agenda on epistemology and practices in the scientific work of administration oriented toward the most prominent societal challenges.

Association between regular arrangement of collecting venules and Helicobacter pylori status in routine endoscopy

BackgroundThe sensitivity of regular arrangement of collecting venules (RAC)-positive pattern for predicting Helicobacter pylori (H. pylori)-negative status greatly altered from 93.8 to 48.0% in recent two decades of various studies, while the reason behind it remained obscure. The aim of this study was to investigate the value of RAC as an endoscopic feature for judging H. pylori status in routine endoscopy and reviewed the underlying mechanism.MethodsA prospective study with high-definition non-magnifying endoscopy was performed. RAC-positive and RAC-negative patients were classified according to the collecting venules morphology of the lesser curvature in gastric corpus. Gastric biopsy specimens were obtained from the lesser and greater curvature of corpus with normal RAC-positive or abnormal RAC-negative mucosal patterns. Helicobacter pylori status was established by hematoxylin and eosin staining and immunohistochemistry.Results41 RAC-positive and 124 RAC-negative patients were enrolled from June 2020 to September 2020. The prevalence of H. pylori infection in patients with RAC-positive pattern and RAC-negative pattern was 7.3% (3/41) and 71.0% (88/124), respectively. Among all 124 RAC-negative patients, 36 (29.0%) patients were H. pylori-negative status. Ten patients (32.3%) demonstrated RAC-positive pattern in 31 H. pylori-eradicated cases. The sensitivity, specificity, positive predictive value, and negative predictive value of RAC-positive pattern for predicting H. pylori-negative status were 51.4% (95% CI, 0.395–0.630), 96.7% (95% CI, 0.900–0.991), 92.7% (95% CI, 0.790–0.981), and 71.0% (95% CI, 0.620–0.786), respectively.ConclusionsRAC presence can accurately rule out H. pylori infection of gastric corpus, and H. pylori-positive status cannot be predicted only by RAC absence in routine endoscopy.Trial registration The present study is a non-interventional trial.

Integrated ecological risk assessment of heavy metals in an oil shale mining area after restoration

Although the mining area has been restored, the environmental problems caused by years of large-scale oil shale mining are still continuing, coupled with the intensive distribution of the surrounding petrochemical industry, posing a serious threat to the local ecological environment. In this study, we investigated eight heavy metals (Cu, Ni, Pb, Cd, As, Cr, Mn and Zn) contamination and distribution around mining area, evaluated the potential risks of environment, identified the main sources of metal pollution and performed source apportionment. The results showed that the original north and south dumps were seriously polluted, and the CF values were significantly higher than other sampling sites. Ni, Zn and Mn have high coefficients of variation, which may be greatly affected by human factors and especially the waste slag piled up. The concentration of heavy metals in the water was lower than in the soil; soil particles, pH, Eh and acid mine drainage influence the variation of heavy metal concentrations. As and Cd have very high RAC values, and accordingly they were mainly present in the exchangeable and reduced fractions. Mn was exposed to higher ecological risks, followed by Pb, although there were high loads on carbonate bound and oxidizable fractions. APCS-MLL receptor model was used to identify and apportionment three main sources of contamination. The mean contribution rates of industrial activity, atmospheric deposition and mixed sources accounted for 39.77%, 22.24% and 37.99%, respectively. Cluster analysis further classified the metal pollution sources according to the spatial distance of sampling points.

Association of Outcomes with Model-Based Indices of Cerebral Autoregulation After Pediatric Traumatic Brain Injury.

We investigated whether model-based indices of cerebral autoregulation (CA) are associated with outcomes after pediatric traumatic brain injury. This was a retrospective analysis of a prospective clinical database of 56 pediatric patients with traumatic brain injury undergoing intracranial pressure monitoring. CA indices were calculated, including pressure reactivity index (PRx), wavelet pressure reactivity index (wPRx), pulse amplitude index (PAx), and correlation coefficient between intracranial pressure pulse amplitude and cerebral perfusion pressure (RAC). Each CA index was used to compute optimal cerebral perfusion pressure (CPP). Time of CPP below lower limit of autoregulation (LLA) or above upper limit of autoregulation (ULA) were computed for each index. Demographic, physiologic, and neuroimaging data were collected. Primary outcome was determined using Pediatric Glasgow Outcome Scale Extended (GOSE-Peds) at 12months, with higher scores being suggestive of unfavorable outcome. Univariate and multiple linear regression with guided stepwise variable selection was used to find combinations of risk factors that can best explain the variability of GOSE-Peds scores, and the best fit model was applied to the age strata. We hypothesized that higher GOSE-Peds scores were associated with higher CA values and more time below LLA or above ULA for each index. At the univariate level, CPP, dose of intracranial hypertension, PRx, PAx, wPRx, RAC, percent time more than ULA derived for PAx, and percent time less than LLA derived for PRx, PAx, wPRx, and RAC were all associated with GOSE-Peds scores. The best subset model selection on all pediatric patients identified that when accounting for CPP, increased dose of intracranial hypertension and percent time less than LLA derived for wPRx were independently associated with higher GOSE-Peds scores. Age stratification of the best fit model identified that in children less than 2years of age or 8years of ageor more, percent time less than LLA derived for wPRx represented the sole independent predictor of higher GOSE-Peds scores when accounting for CPP and dose of intracranial hypertension. For children 2years or younger to less than 8years of age, dose of intracranial hypertension was identified as the sole independent predictor of higher GOSE-Peds scores when accounting for CPP and percent time less than LLA derived for wPRx. Increased dose of intracranial hypertension, PRx, wPRx, PAx, and RAC values and increased percentage time less than LLA based on PRx, wPRx, PAx, and RAC are associated with higher GOSE-Peds scores, suggestive of unfavorable outcome. Reducing intracranial hypertension and maintaining CPP more than LLA based on wPRx may improve outcomes and warrants prospective investigation.

On rainbow antimagic coloring of graphs

A rainbow antimagic coloring is one of new topics in graph theory. This topic is an expansion of rainbow coloring that is combined with antimagic labeling. The graphs are labeled with an antimagic labeling, and then the sum of vertex label have to obtain a rainbow coloring. The aim of the rainbow antimagic coloring research is to find the minimum number of color, called rainbow antimagic connection number, denoted by rac(G). In this research, we studied some simple graphs to be colored with rainbow antimagic coloring. The graphs we used are lollipop, stacked book, Dutch windmill, flowerpot and dragonfly. In this research, we aimed to develop new theorem. Based on the results, we got some theorems about rac(G) for the rainbow antimagic coloring. In addition, on some graphs that we use, we get rac(G) equal to rc(G), rainbow connection number. Instead, on the others, the value of rac(G) cannot reach the rc(G).

THE VARIABLE GRAVITY FIELD AND VISCOUS DISSIPATION EFFECTS ON THE CONVECTIVE INSTABILITY IN A POROUS LAYER WITH THROUGHFLOW: BRINKMAN MODEL

The present investigation aims to study the combined effect of viscous dissipation, vertical throughflow, and variable gravity field on the onset convective instability in a horizontal porous layer of finite thickness restricted between two permeable boundaries. The Brinkman extended Darcy model is accounted into the momentum equation of the governing flow through the porous layer. Also, linear, quadratic, and exponential gravity variation has been considered to study the present problem. The linear stability of the basic state is studied for the normal mode perturbations, and the corresponding eigenvalue problem is solved numerically using the bvp4c routine in MATLAB. The influence of throughflow parameter (Q), viscous dissipation (Ge), Darcy number (Da), and gravity variation parameter (λ) on the instability mechanism is discussed for the above three gravity field variations. The results indicate that the beginning of convection is postponed in the presence of Darcy number, throughflow, and gravity field parameter, while it is advanced in the presence of a significant viscous dissipation. Rac elevates to maximum at around 299% for linear variations of the gravity field, while it was 74% and 868% for quadratic and exponential varying gravity fields, respectively, when λ increases from 0 to 1.5. The value of Rac increased 6.5%, 5.4%, and 10.6%, respectively, for the linear, quadratic, and exponential gravity field variables, respectively, on changing the values of throughflow parameter from 0 to 1 and the increase in Rac is more for enhancing the value of the throughflow parameter from 1 to 2. Further, the system becomes more stable in the presence of an exponential gravity field.

Autophagy inducer activates Nrf2-ARE pathway to attenuate aberrant alveolarization in neonatal rats with bronchopulmonary dysplasia

AimsBronchopulmonary dysplasia (BPD) is a severe respiratory complication in preterm infants. This study reveals the molecular mechanism of autophagic agonists regulating the Nrf2-ARE pathway via p62 to improve alveolar development in BPD rats. Main methodsNewborn Sprague-Dawley rats were randomly exposed to a hyperoxic environment (FiO2 = 0.85) for 14 days and rapamycin (RAPA) was intraperitoneally injected on alternate days into hyperoxia-exposed mice. Alveolar development was assessed using HE and RAC values. Markers associated with the p62-Keap1-Nrf2-ARE pathway were detected by western blot, immunohistochemistry, and RT-PCR. Co-localization of proteins was determined using double immunofluorescence staining. Key findingsAt the levels of lung tissue and primary type II alveolar epithelial cells, the enhanced binding between phosphorylated p62 and Keap1 disrupted the nuclear transport of Nrf2. The activated Nrf2 was insufficient to reverse alveolar simplification. The autophagy agonist was able to inhibit p62 phosphorylation, promote Keap1 degradation, increase Nrf2 nuclear transport, augment downstream antioxidant enzyme expression, and enhance antioxidant capacity, thereby improving the simplification of alveolar structure in BPD rats. SignificanceThe use of autophagy agonists to enhance the Nrf2-ARE pathway activity and promote alveolar development could be a novel target in antioxidant therapy for BPD.

Association between a regular arrangement of collecting venules and absence of Helicobacter pylori infection in a European population

Helicobacter pylori is the major cause of gastritis and gastritis-associated diseases. Detection of a regular arrangement of collecting venules (RAC) in the lesser gastric curvature correlates with negative H pylori status with a sensitivity and negative predictive value (NPV) higher than 90% in Asian countries. The aim of the study was to evaluate the value of RAC as a diagnostic method of H pylori infection in a European population. A prospective study with high-definition endoscopes without magnification was performed by 3 endoscopists. The presence of starfish-like minute points regularly distributed throughout the lesser curvature of the gastric body was considered RAC positive (RAC+). Gastric biopsies were performed during the procedure for H pylori diagnosis. One hundred forty patients were included from February 2017 to May 2018. The prevalence of H pyloriinfection was 31% and 47 of 140 patients (34%) were RAC+; 13 of 23 patients in whom H pylori was eradicated were RAC+. The mean age of RAC+ patients was lower (44.4 vs 52.4 years, P= .004) and they had less- significant endoscopic findings (9; 19.1% vs 38; 80.9%; P= .017). Gender, use of nonsteroidal anti-inflammatory drugs, antithrombotic or anticoagulants treatments, and a history of H pylori eradication did not show differences in the RAC pattern. The absence of RAC was associated with H pylori infection in 47.3% (44/93) of cases. In contrast, all RAC+ patients were free of H pylori infection, with sensitivity and NPV of 100% for the exclusion of H pylori infection. The presence of RAC+ in the lesser curvature evaluated with high-definition endoscopy can accurately identify patients without H pylori.

Immobilization of heavy metals in ceramsite produced from sewage sludge biochar

Ceramsite was prepared from sewage sludge biochar (SSB). The migration, speciation evolution, leaching toxicity, and potential environmental risk of heavy metals (HMs) in sludge biochar ceramsite (SBC) were investigated. The characteristics of the SBC met the requirements for Chinese lightweight aggregate standards (GB/T 1743.1-2010 and JT/T 770-2009) and the heavy metals (HMs: Cu, Zn, Cr, Pb, and Cd) were well immobilized in the SBC. The leaching percentages of the HMs in SBC were remarkably reduced, in particular after preheating at 400°C and sintering at 1100°C. The leaching percentages of Cu, Zn, Cr, Cd, and Pb decreased from (19.099, 18.009, 0.010, 3.952, and 0.379) % to (2.122, 4.102, 0.002, 1.738, and 0.323) %, respectively. The RAC values of the HMs in SBC were all lower than 1%, and the risk index (RI) suggested that the SBC had no HMs contamination and very low potential ecological risk when used in the environment. Furthermore, the HM-immobilization mechanisms were mainly related to the formation of new crystal phases (silicate and phosphate minerals) by incorporation of HMs, and to vitrification and encapsulation with low concentration of HMs on the surface. This work provides a useful method for large-scale reuse of SSB with very low leaching toxicity and low potential ecological risk of HMs.

Thermal fluids along the East Anatolian Fault Zone (EAFZ): Geochemical features and relationships with the tectonic setting

A geochemical investigation has been carried out on the gas phase associated to thermal fluids discharged along three different segments of the East Anatolian Fault Zone (EAFZ, Turkey) running from Malatya to the Triple Junction area (Karlıova) where the East and North Anatolian Faults cross each other. CO2 is always the major gaseous component in both bubbling and dissolved gases with variable amounts of nitrogen helium and CH4. The isotopic ratios of helium range from 0.44 to 4.41Rac (values corrected for the atmospheric contamination) and cover a range spanning from crustal to magmatic-type values. The isotopic composition of carbon (CO2) shows values in the range from −5.6 to −0.2‰ vs PDB for the bubbling gases in contrast with the positive values (from 0.3 to 3.4‰ vs PDB) detected for the Total Dissolved Inorganic Carbon (TDIC). Coupling the information from the isotopic and chemical compositions, it results that mantle-derived fluids are driven to the surface by lithospheric structures. Despite the absence of outcropping volcanic products, the tectonic setting of the different segments plays a major role in releasing mantle-type fluids. The mantle derived fluids interact at shallower levels with circulating waters and originate geothermal systems which equilibration temperatures are estimated to be up to 360°C. The collected thermal fluids show different geochemical features consistent with processes occurring at two different levels: a deep level where mantle-originated fluids are taken either from the upper mantle or from intruded magma batches, and a shallower level, in the upper crust, where Gas Water Interactions (GWI), secondary CO2 production, and fractionation processes induced chemical and isotopic modifications of the pristine gas composition.

Noxa1 as a moderate activator of Nox2-based NADPH oxidase

Noxa1 was discovered as an activating factor for Nox1, an O2--generating enzyme. Subsequent studies have shown that Noxa1 is colocalized with Nox2 in several cell types, including vascular cells. Nox2 activation by Noxa1 has been examined in reconstituted model cells. However, little is known about the kinetic properties of Noxa1 in Nox2 activation. In the present study, we used purified cyt.b558 (Nox2 plus p22phox), Rac(Q61L), and Noxo1 to examine the ability of Noxa1 to activate Nox2. In the pure reconstitution system, Noxa1 activated Nox2 with lower efficiency than p67phox, a canonical activator of Nox2. The EC50 value of Noxa1 was considerably higher than that of p67phox. The Vmax value with Noxa1 and Noxo1 was one-third of that with p67phox and p47phox. The EC50 value of Noxo1 or Rac(Q61L) was also higher when Noxa1 was used. The affinity of FAD for the oxidase and the stability of the active complex were remarkably low when Noxa1 and Noxo1 were used compared with p67phox and p47phox. The stability was not improved by fusion of Noxa1 with Rac(Q61L). These findings show that Noxa1 has quite different kinetic properties from p67phox and suggest that Noxa1 may function as a moderate activator of Nox2.

Speciation of heavy metals by modified BCR sequential extraction procedure in different depths of sediments from Sungai Buloh, Selangor, Malaysia

The sequential extraction procedure proposed by the European Standard, Measurements and Testing (SM&T) program, formerly the Community Bureau of Reference (BCR), was applied for partitioning of heavy metals (HMs) in river sediments collected along the course of Sungai Buloh and the Straits of Malacca in Selangor, Malaysia. Eight elements (V, Pb, Cd, Cr, Co, Ni, Cu and Zn) from seven stations (S1–S7) and at different depths were analyzed using the modified BCR Sequential Extraction Procedure (SEP) in combination with ICP-MS to obtain the metal distribution patterns in this region. The results showed that heavy metal contaminations at S2 and S3 was more severe than at other sampling sites, especially for Zn, Cu, Ni and Pb. Nevertheless, the element concentrations from top to bottom layers decreased predominantly. The samples from the Straits of Malacca (S4–S7) the highest contamination factors obtained were for Co, Zn and Pb while the lowest were found for V and Cr, similar to Sungai Buloh sediments. The sediments showed a low risk for V, Cr, Cu and Pb with RAC values of less than 10%, but medium risk for Co, Zn (except S3), Cd at S1 and S2 and Ni at S1, S3 and S5. Zn at S3 and Cd at S3–S7 showed high risk to our sediment samples. There is not any element of very high risk conditions in the selected samples.

Regular arrangement of collecting venules: Does patient age affect its accuracy?

To address the diagnostic value of the regular arrangement of collecting venules (RAC) among old age patients. A total of 390 consecutive patients whose Helicobacter pylori (H. pylori) status was known and who received upper gastrointestinal endoscopy, were retrospectively studied for the presence or absence of RAC as well as gastric mucosal atrophy. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of RAC to detect normal gastric mucosa were assessed and were compared among two different age groups of patients. The mean age ± standard deviation (SD) of included patients (n = 390), was 62.9 ± 13 years. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of RAC to detect normal gastric mucosa were 91.7%, 66.1%, 18.8%, 99% and 68.1% respectively. Although the sensitivity, specificity, positive predictive value, negative predictive value and accuracy of RAC among patients < 60 years (n = 139) was 94.7%, 71.2%, 46.2%, 98.1%and 76.1%, respectively, it was 80%, 64.3%, 5.1%, 93% and 64.6%, respectively, among patients ≥ 60 years (n = 251). Younger Patients (< 60 years), have highly significant rates of RAC sensitivity, positive predictive value, and accuracy (P ≤ 0.001, ≤ 0.001 and ≤ 0.02, respectively). Older patients had highly significant rates of H. pylori infection and gastric mucosal atrophy (P ≤ 0.01). Although RAC is a valuable sign for real-time identification of normal gastric mucosa, its accuracy seems to be affected by the patient's age.

Changes in cropland topsoil organic carbon with different fertilizations under long-term agro-ecosystem experiments across mainland China

Topsoil soil organic carbon (SOC) data were collected from long-term Chinese agro-ecosystem experiments presented in 76 reports with measurements over 1977 and 2006. The data set comprised 481 observations (135 rice paddies and 346 dry croplands) of SOC under different fertilization schemes at 70 experimental sites (28 rice paddies and 42 dry croplands). The data set covered 16 dominant soil types found in croplands across 23 provinces of mainland China. The fertilization schemes were grouped into six categories: N (inorganic nitrogen fertilizer only), NP (compound inorganic nitrogen and phosphorus fertilizers), NPK (compound inorganic nitrogen, phosphorus and potassium fertilizers), O (organic fertilizers only), OF (combined inorganic/organic fertilization) and Others (other unbalanced fertilizations such as P only, K only, P plus K and N plus K). Relative change in SOC content was analyzed, and rice paddies and dry croplands soils were compared. There was an overall temporal increase in topsoil SOC content, and relative annual change (RAC, g kg(-1) yr(-1)) ranged -0.14-0.60 (0.13 on average) for dry cropland soils and -0.12-0.70 (0.19 on average) for rice paddies. SOC content increase was higher in rice paddies than in dry croplands. SOC increased across experimental sites, but was higher under organic fertilization and combined organic/inorganic fertilizations than chemical fertilizations. SOC increase was higher under balanced chemical fertilizations with compound N, P and K fertilizers than unbalanced fertilizations such as N only, N plus P, and N plus K. The effects of specific rational fertilizations on SOC increase persisted for 15 years in dry croplands and 20 years in rice paddies, although RAC values decreased generally as the experiment duration increased. Therefore, the extension of rational fertilization in China's croplands may offer a technical option to enhance C sequestration potential and to sustain long-term crop productivity.

An increase in topsoil SOC stock of China's croplands between 1985 and 2006 revealed by soil monitoring

Soil C sequestration in cropland could play an important role in mitigating the rapidly increasing CO 2 emissions in China. Many efforts had been dedicated to estimating the potential for C sequestration in croplands. Potential increases in SOC in China's croplands had been recently evaluated using inventory-up-scaling simulation and crop-soil C process-based modeling. In this study, data of SOC change at monitoring sites from croplands across mainland China were collected from publications available from 1985 to 2006 to perform a statistical analysis. The data set comprises 1081 observations (404 from rice paddies, RPs and 677 from dry croplands, DCs). Frequency analysis indicates that over 70% of observations show an increase in SOC, which is higher among RPs than DCs. To quantify SOC dynamics, a Relative Annual Change Index in g kg −1 year −1 (RAC, g kg −1 year −1) is defined and calculated using the initial and final SOC values for the duration of monitored observations. RAC values ranged from −0.806 to 0.963 g kg −1 year −1 for DCs and from −0.597 to 0.959 g kg −1 year −1 for RPs, respectively. From this data, the average is estimated to be 0.056 ± 0.200 g kg −1 year −1 for DCs, and 0.110 ± 0.244 g kg −1 year −1 for RPs, with an overall estimate for China's croplands, with RPs and DCs combined, of 0.076 ± 0.219 g kg −1 year −1. A mean increase in topsoil C (0–20 cm) stock of China's croplands was estimated to be 25.5 Tg C year −1 (8 Tg C year −1 in RPs and 17.5 Tg C year −1 in DCs) between 1985 and 2006, with a total topsoil C stock increase of 0.64 Pg C over the whole period. The annual stock increase may offset ∼20%, on average, of the total CO 2 emissions of China for 1994. This study suggests an important role of China's croplands, especially rice paddies, for C sequestration to mitigate climate change.

Hypothalamic involvement in Huntington's disease: an in vivo PET study

Recent studies have shown alterations in metabolism, sleep and circadian rhythms as well as in several neuropeptides derived from the hypothalamic-pituitary axis in Huntington's disease patients; however, the pathology underlying these abnormalities is not known. Our aim was to assess in vivo D(2) receptor's loss/dysfunction and increases in microglial activation in the hypothalamus of symptomatic Huntington's disease patients and premanifest Huntington's disease gene carriers using PET with (11)C-raclopride (RAC), a specific D(2) receptor ligand and (11)C-(R)-PK11195 (PK), a marker of microglial activation. We have studied 9 symptomatic Huntington's disease patients (age = 46.8 +/- 4.7 years; mean +/- SD) and 10 premanifest Huntington's disease gene carriers (age = 41.9 +/- 8.2 years; mean +/- SD). RAC and PK findings for these subjects were compared with those of a group of normal controls (RAC, n = 9; PK, n = 10). In the symptomatic Huntington's disease group, we found a significant decrease (P = 0.0012) in mean hypothalamic RAC binding potential (BP) and a significant increase in mean hypothalamic PK BP (P = 0.0008). Similarly, a significant decrease (P = 0.0143) in mean hypothalamic RAC BP and a significant increase in mean hypothalamic PK BP (P = 0.0057) were observed in the premanifest Huntington's disease group. Hypothalamic RAC and PK BP values correlated with each other in combined Huntington's disease groups (r = -0.6180, P = 0.0048) but not with striatal RAC and PK BP values. Our data demonstrate, for the first time, significant D(2) receptor loss and microglia activation in the hypothalamus of Huntington's disease. These pathological changes occur very early in the course of the disease and may partly explain the development of commonly reported symptoms in Huntington's disease including progressive weight loss, alterations in sexual behaviour and disturbances in the wake-sleep cycle.

Critical Rayleigh Number of Natural Convection in an Anisotropic Horizontal Porous Layer with High Porosity

Linear stability analysis was applied to obtain the critical Rayleigh number Rac at the onset of natural convection for horizontal anisotropic porous fluid layers with vertical thin circular cylinders inserted by variational method with the consideration of non-Darcy viscous flow assumption. The permeability ratio of x-direction to z-direction is 0.5 and the effective thermal diffusivity ratio ξ of x-direction to z-direction for the anisotropic porous fluid layer is less than unity for any circular cylinders with high or low thermal conductivity. The analytical results show that Rac is the highest for the case of ξ=1 and decreases with the decrease in ξ. It decreases with the increase in Darcy number Da and asymptotically approaches to a constant value for Da→∞. The constant value of Rac for Da→∞ is the smallest to be 690.8 for ξ→0. The analytical results were compared with experimental results performed with silicon oil and plastic resin as a working fluid and circular cylinders respectively for ξ=1. The experiment agreed well with the analysis based on non-Darcy viscous flow assumption. The analysis showed that Darcy flow assumption is applied for small Da dependent on ξ.

Slow cooling conditions for texturing ferromagnetic materials by solidification in a magnetic field

Solidification of giant magnetostrictive materials TbFe1.9, DyFe1.9, and Tb0.3Dy0.7Fe1.9 in a magnetic field has been investigated. Suppressing the turbulence in the melt is a key factor in texturing the magnetic materials. Those factors which influence convective flow during the course of solidification are discussed, and a critical Rayleigh number Rac can be used to reflect the state of turbulence at various cooling rates. Once the value of Rac in a magnetic field is larger than that of the practical Rayleigh number Ra in the melt, the temperature oscillations will be restrained, and the texture along the easy magnetic axis for those ferromagnetic materials will be dominant in the sample.