A 3-year follow-up analysis of renal function in elderly patients with type 2 diabetes mellitus and an estimated glomerular filtration rate <90 mL/min/1.73m2: A retrospective cohort study.

Type 2 diabetes mellitus (T2DM) is a risk factor for patients with impaired renal function. The onset of T2DM-induced diabetic kidney disease (DKD) is frequently sub-clinical, potentially culminating in end-stage renal disease. In the current study the factors influencing DKD in elderly patients diagnosed with T2DM were determined. A retrospective cohort study was conducted involving patients ≥60 years of age with T2DM from June 2019 to December 2022. The Cockcroft-Gault formula was used to estimate the glomerular filtration rate. The clinical information and biochemical indicators of patients with an estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73m2 were collected. Patients were grouped based on a 3-year eGFR decline < 15% and ≥ 15%. The differences between the two groups were compared and the factors influencing the 3-year eGFR decline ≥ 15% were analyzed. A total of 242 patients were included, including 154 in the group with a 3-year eGFR decline < 15% and 88 in the group with a three-year eGFR decline ≥ 15%. Univariate logistic regression analysis showed that smoking cigarettes, and triglycerides (TG) and high-density lipoprotein levels were related to a 3-year eGFR decline ≥ 15% (P = .039, P < .001, and P = .011, respectively). Multivariate logistic regression analysis showed that the TG level was independently related to a 3-year eGFR decline ≥ 15% (P = .004; OR = 2.316). There was a significant linear relationship between the eGFR decline and TG level (P = .002). Patients with a TG concentration > 1.7 mmol/L had a more apparent decrease in the eGFR (P < .05). For elderly patients with T2DM and an eGFR < 90 mL/min/1.73m2, the TG level may be an important risk factor for deteriorating renal function that warrants actively intervention.

Wound infection and healing in minimally invasive plate osteosynthesis compared with intramedullary nail for distal tibial fractures: A meta-analysis.

To systematically explore the effects of minimally invasive plate osteosynthesis (MIPO) versus intramedullary nail (IMN) on wound infection and wound healing in patients with distal tibia fractures. A computerised search of PubMed, Web of Science, Cochrane Library, Embase, Wanfang, China Biomedical Literature Database (CBM) and China National Knowledge Infrastructure databases was performed, from their inception to October 2023, to identify relevant studies on the application of MIPO and IMN in patients with distal tibial fractures. The quality of the included literature was evaluated by two researchers based on inclusion and exclusion criteria, and basic information of the literature was collected, with wound infection, postoperative complications and wound healing time as the main indicators for analysis. Stata 17.0 software was applied for analysis. Overall, 23 papers and 2099 patients were included, including 1026 patients in the MIPO group and 1073 patients in the IMN group. The results revealed, when compared with IMN treatment, patients with distal tibia fractures who underwent MIPO treatment had a lower incidence of postoperative complications (OR = 0.33, 95% CI: 0.25-0.42, p < 0.001) and a shorter wound healing time (SMD = -1.00, 95% CI: -1.51 to -0.49, p < 0.001), but the incidence of postoperative wound infection was higher (OR = 2.01, 95% CI: 1.35-3.01, p = 0.001). Both MIPO and IMN are excellent treatments for distal tibia fractures. MIPO is effective in reducing the incidence of complications as well as shortening the time of wound healing time but increases the risk of wound infection. In clinical practice, surgeons can make individual choices based on the patient's wishes and proficiency in both techniques.

Flagellar brake protein YcgR interacts with motor proteins MotA and FliG to regulate the flagellar rotation speed and direction.

In E. coli and related species, flagellar brake protein YcgR responds to the elevated intracellular c-di-GMP, decreases the flagellar rotation speed, causes a CCW rotation bias, and regulates bacterial swimming. Boehm et al. suggested that c-di-GMP-activated YcgR directly interacted with the motor protein MotA to curb flagellar motor output. Paul et al. proposed that YcgR disrupted the organization of the FliG C-terminal domain to bias the flagellar rotation. The target proteins are controversial, and the role of motor proteins remains unclear in flagellar rotation speed and direction regulation by YcgR. Here we assayed the motor proteins' affinity via a modified FRET biosensor and accessed the role of those key residue via bead assays. We found that YcgR could interact with both MotA and FliG, and the affinities could be enhanced upon c-di-GMP binding. Furthermore, residue D54 of YcgR-N was needed for FliG binding. The mutation of the FliG binding residue D54 or the MotA binding ones, F117 and E232, restored flagellar rotation speed in wild-type cells and cells lacking chemotaxis response regulator CheY that switched the flagellar rotation direction and decreased the CCW ratio in wild-type cells. We propose that c-di-GMP-activated YcgR regulated the flagellar rotation speed and direction via its interaction with motor proteins MotA and FliG. Our work suggest the role of YcgR-motor proteins interaction in bacterial swimming regulation.

Transcriptional regulation of host insulin signaling pathway genes controlling larval development by Microplitis manilae parasitization.

Idiobiont parasitoids using other insects as hosts sabotage the host growth and development to ensure their offspring survival. Numerous studies have discovered that insect development is subtly regulated by the conserved insulin signaling pathway. However, little is known about how wasp parasitization disrupts host development controlled by the insulin signaling pathway. Here we address this study to determine the effect of wasp parasitism on host Spodoptera frugiperda development using the idiobiont parasitoid Microplitis manilae as a model. Upon M. manilae parasitization, the body weight, body length, and food consumption of host insect were dramatically reduced compared to the unparasitized S. frugiperda. We next identified the core genes involved in host insulin signaling pathway and further analyzed the domain organizations of these genes. Phylogenetic reconstruction based on the insulin receptors clustered S. frugiperda together with other noctuidae insects. In the latter study, we profiled the expression patterns of host insulin signaling pathway genes in response to M. manilae parasitization at 2, 24, and 48 h, significant decreases in mRNA levels were recorded in S. frugiperda larvae upon 24 and 48 h parasitization. These current findings substantially add to our understanding of the physiological interaction between parasitoid and host insects, thus contributing to revealing the molecular mechanism of parasitic wasps regulating host development.

Onodera's Prognostic Nutritional Index is a novel and useful prognostic marker for gastrointestinal stromal tumors.

BACKGROUND: Immunoinflammatory markers such as the peripheral blood neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) have gained considerable attention as prognostic markers in gastrointestinal stromal tumors (GISTs). AIM: To assess the prognostic value of Onodera's Prognostic Nutritional Index (OPNI) for GISTs. METHODS: All patients who had undergone surgical resection for a primary, localized GIST from 2009 to 2016 at our cancer center were initially and retrospectively identified. Recurrence-free survival (RFS) was calculated by the Kaplan-Meier method and compared by the log-rank test. We used multivariate Cox proportional hazard regression models to identify associations with outcome variables. RESULTS: A total of 235 GISTs were identified and included for analysis under our inclusion criteria. Univariate and multivariate analyses both identified the OPNI as an independent prognostic marker, and the OPNI was associated with the primary site, tumor size, mitotic index, tumor rupture, necrosis, and modified NIH risk classification. Low OPNI (< 51.30; hazard ratio = 5.852; 95% confidence interval: 1.072-31.964; P = 0.0414) was associated with worse RFS. The 2- and 5-year RFS rates of the patients with a low OPNI were 92.83% and 76.22%, respectively, whereas 100% and 98.41% were achieved by the patients with a high OPNI. CONCLUSION: The preoperative OPNI is a novel and useful prognostic marker for GISTs.

Digestive solubilization of Cd in highly-contaminated sediment by marine deposit feeders: The roles of intestinal surfactants in Cd mobilization and Re-Adsorption processes.

Marine deposit feeders are of ecological significance in transferring sedimentary Cd along aquatic food chains. A key process for this transfer is these organisms' dietary uptake of Cd via solubilization of Cd present in ingested contaminated sediment. To better understand the bioavailability of sedimentary Cd to deposit feeders, the present study used in vitro extraction experiments to explore the contribution of different digestive agents (proteins, amino acids and surfactants) to the solubilization of Cd from sediment collected in a highly-contaminated Chinese bay. This was done for various commercially-available mimetic digestive agents (the protein BSA, a mixture of amino acids, and the surfactants rhamnolipid and SDS), and for proteins and surfactants collected from the gut juice of a sipunculan worm. The Cd mobilization capacity of BSA was significantly higher than that of the amino acids and the commercial surfactants. In the presence of BSA, > 70% of the released Cd became associated with this protein. In contrast, the digestive proteins from the sipunculan had a lower Cd mobilization capacity than was the case for the other digestive agents and the majority of the released Cd (∼80%) was associated with small molecular weight fractions. The differences in Cd mobilization between the BSA and the digestive proteins were attributed to differences in their sediment-adsorption tendencies and their Cd-complexing capacities. While the digestive surfactants had minor effects on the release of sedimentary Cd, they significantly enhanced Cd mobilization by the digestive proteins when both were present simultaneously. Our results suggest that the characteristics of proteins should be considered when using commercially-available mimetic digestive agents to explore Cd bioavailability in sediments. Furthermore, digestive surfactants seem to have important effects on the solubilization of Cd during gut passage by reducing the adsorption of the digestive proteins to the sediments.

Visible-Light Photoredox-Catalyzed Iminyl Radical Formation by N-H Cleavage with Hydrogen Release and Its Application in Synthesis of Isoquinolines.

An unprecedented visible-light photoredox-catalyzed iminyl radical formation by N-H cleavage with H2 release has been developed. Its application in the synthesis of various isoquinolines and related polyaromatics in high atom economy at ambient temperature by applying a photosensitizer, Acr+-Mes ClO4-, and a new cobalt catalyst, Co(dmgH)2(4-CONMe2Py)Cl is reported. Mechanistic investigations indicated that the generated iminyl radical initiates the cascade C-N/C-C bonds formation and the catalytic cycle occurs by a simultaneous oxidative as well as reductive quenching pathway.

Efficient Aryl Migration from an Aryl Ether to a Carboxylic Acid Group To Form an Ester by Visible-Light Photoredox Catalysis.

We have developed a highly efficient aryl migration from an aryl ether to a carboxylic acid group through retro-Smiles rearrangement by visible-light photoredox catalysis at ambient temperature. Transition metals and a stoichiometric oxidant and base are avoided in the transformation. Inspired by the high efficiency of this transformation and the fundamental importance of C-O bond cleavage, we developed a novel approach to the C-O cleavage of a biaryl ether to form two phenolic compounds, as demonstrated by a one-pot, two-step gram-scale reaction under mild conditions. The aryl migration exhibits broad scope and can be applied to the synthesis of pharmaceutical compounds, such as guacetisal. Primary mechanistic studies indicate that the catalytic cycle occurs by a reductive quenching pathway.

Improved autophagic flux is correlated with mTOR activation in the later recovery stage of experimental acute pancreatitis.

BACKGROUND/OBJECTIVES: Lysosomal/autophagic pathway plays important role in the early onset of acute pancreatitis (AP). However, its role in the later recovery phase of AP is unknown. This study aims to investigate the role of lysosomal/autophagic pathway in the self-limited program of AP and elucidate the underlying mechanisms. METHODS: AP was induced in the rat by 3% sodium taurocholate injection in the pancreaticobiliary duct. Serum amylase activity assay, histological examination, and cell death detection were used to assess the time course of AP severity. Meanwhile, the expression of LC3-II, p62 and Lamp-2 was measured to evaluate the status of autophagic flux. S6RP phosphorylation was detected to determine the time course of mTOR activation. Rapamycin was administered to block mTOR activity. RESULTS: AP developed in the rats to the most severe at 24 h but tended to self-restore at 36 and 48 h. The impairment of autophagic flux characterized by the accumulation of LC3-II and p62 and the depletion of Lamp-2 occurred at 24 h after AP induction followed by the restoration over the following 24 h. Furthermore, the phosphorylation of S6RP was increased at 36 and 48 h after AP induction despite the initial inhibition. Rapamycin treatment reduced the level of phospho-S6RP and inhibited the restoration of autophagic homeostasis and pancreatic tissue injury. CONCLUSIONS: Activation of mTOR is correlated with the improvement of autophagic flux and pancreatic injury, suggesting that mTOR activation plays a potential protective role in the later recovery of AP.

[XAS Analysis upon Dissolved Species of Orpiment in Anoxic Environment].

The orpiment[As2S3(s)] is an important secondary mineral in the geochemical process of arsenic in the environment. The study upon orpiment dissolution is important to investigate the migration and transformation of arsenic in the environment. The environmental pH and sulfur content have vital influence on species changing and stability of arsenic species in orpiment. Here we analyzed the stable arsenic species of anoxic orpiment dissolution in sulfidic and the absence of sulfide solutions at neutral condition with simulation test via X-ray absorption near edge spectroscopy(XANES) and extended X-ray absorption fine structure(EXAFS). The results showed that orpiment dissolution contained a mixture of arsenite and thioarsenite species at neutral condition, and arsenic species in sulfidic solutions is mainly thioarsenic, while arsenic species in the absence of sulfide solutions is oxythioarsenic. The results of Linear Combination of Fits showed that arsenic species were arsenite (88. 2%) and thioarsenite(11. 8%) in sulfidic solutions, and there were arsenite (56. 3%) and thioarsenite(43. 7%) in the absence of sulfide solutions. Our results confirmed that the formation of arsenite was related to the total sulfur to total arsenic ratios, and the form of thioarsenite species could be enriched by increasing of the total sulfur to total arsenic ratio.

Direct and short construction of the ACDE ring system of daphenylline.

Daphenylline, a novel daphniphyllum alkaloid, boasts a fused and bridging ring system coupled with six stereogenic centers. Here we present a direct and short construction of the ACDE ring system of daphenylline from the known 3-(2-bromophenyl)propanal in 10 steps and 17 % overall yield. The synthesis features an iron(III)-catalyzed aza-Cope-Mannich reaction, a self-terminating 6-exo-trig aryl radical-alkene cyclization and an intramolecular Friedel-Crafts acylation.

Reduction of fibrosis in dibutyltin dichloride-induced chronic pancreatitis using rat umbilical mesenchymal stem cells from Wharton's jelly.

OBJECTIVES: The objective of this study was to investigate the effects of rat umbilical cord mesenchymal stem cells (UCMSCs) from Wharton's jelly on dibutyltin dichloride (DBTC)-induced chronic pancreatitis (CP) and subsequent pancreatic fibrosis in rats. METHODS: A rat model of CP induced by DBTC was used. Male Sprague-Dawley rats were randomly divided into 4 groups: the control, DBTC, DBTC + UCMSCs, and control + UCMSC groups. Umbilical cord mesenchymal stem cells were administered intravenously on day 5 after the administration of DBTC. On days 14 and 28, the rats were evaluated morphologically and biochemically. The expression levels of inflammatory cytokines and chemokines in the pancreatic tissues of different groups were evaluated using quantitative real-time polymerase chain reaction. The activation of pancreatic stellate cells was estimated by immunochemistry and Western blot analysis of α-smooth muscle actin. RESULTS: Umbilical cord mesenchymal stem cells were detected in inflamed pancreatic tissues. Umbilical cord mesenchymal stem cell treatment improved the histological scores and alleviated the fibrosis of pancreas samples, The expression of cytokines in the DBTC + UCMSC group was significantly lower than that in the DBTC group. Also, pancreatic stellate cell activation was inhibited by UCMSC treatment. CONCLUSIONS: Xenogeneic transplantation of UCMSCs is a novel approach for the treatment of CP and subsequent fibrosis. Umbilical cord mesenchymal stem cells may be a promising therapeutic intervention for human CP in the future.

Protective effects of edaravone on experimental chronic pancreatitis induced by dibutyltin dichloride in rats.

BACKGROUND/AIMS: To investigate the effects of edaravone, a potent free radical scavenger, on dibutyltin dichloride (DBTC)-induced chronic pancreatitis (CP) and pancreatic fibrosis. METHODS: Male Sprague-Dawley rats were randomly divided into four groups (n = 16 each): control, DBTC, DBTC + edaravone, and control + edaravone. Edaravone or normal saline at a daily dose of 6 mg/kg body weight was given intraperitoneally from day 5 to day 28 after DBTC administration. On days 14 and 28, the rats were evaluated morphologically and biochemically. The expression of cytokines in pancreas TGF-ß, IL-6 and TNF was detected using RT-PCR. The activation of nuclear factor (NF)-κB in pancreatic tissue was evaluated by immunostaining and western-blot for NF-κB p65. α-smooth muscle actin (α-SMA) expression was also evaluated by immunostaining and western-blot to investigate the activation of pancreatic stellate cells (PSCs). RESULT: Edaravone treatment improved the rats' body weight (p < 0.01) and feed intake levels (p < 0.05), improved the histological scores and alleviated the fibrosis of pancreas samples (p < 0.05), as well as markedly increased superoxide dismutase (SOD) activity and decreased malondialdehyde (MDA) concentrations in pancreatic tissue (p < 0.01 for both). The expression of cytokines TGF-ß, IL-6 and TNF in pancreas of DBTC group was also down-regulated by edaravone after treatment. Edaravone inhibited the activation of NF-κB and PSCs and exhibited protective effects on pancreatic tissue damage in CP. CONCLUSIONS: This antioxidant may be a promising therapeutic intervention for human CP.

[Chemical extraction of arsenic co-precipitated with amorphous Fe (OH)3 and Fe3O4].

The mobility and bioavailability of As combining with amorphous Fe oxides is vulnerable to the environment. In order to figure out the specific effects of ageing time, Fe/As molar ratio and extractant-to-solid ratio on As extraction procedure, we chose 1 mol x L(-1) hydrochloride acid and 0.2 mol x L(-1) ammonium oxalate/oxalic acid as extractants to extract synthetic Fe (OH)3-As and Fe3O4-As co-precipitates. The results showed that: (1) During the extraction of Fe(OH) 3-As and Fe3O4-As co-precipitates by 1 mol x L(-1) hydrochloride acid, extractant-to-solid ratio should be 50 and 200, respectively; while extracted by 0.2 mol x L(-1) ammonium oxalate/oxalic acid, the molar ratio of C2O4(2-) to Fe in Fe(OH)3 and Fe3O4 solid phases should be 4 and 2.5, (2) The extraction time conducted by hydrochloride acid and ammonium oxalate/oxalic acid should be within 2 hours. (3) The Fe-to-As molar ratio and ageing at room temperature had a little influence on the extraction of Fe(OH)3-As co-precipitation, but significantly influenced on Fe3O4-As co-precipitation. With increase of the Fe/As molar ratio and extension of the ageing time, the Fe3O4-As co-precipitate became more difficult to be dissolved. (4) It was worth noting that, As would be re-adsorpted by the insoluble solid phase during the extraction by hydrochloride acid and ammonium oxalate/oxalic acid. So the inaccurate measurement would emerge during the extraction of As combining with amorphous Fe oxides.

[Antitumor effect of sphingosine kinase 1 inhibitor in combination with chemotherapy on SGC7901 gastric cancer cells in vitro].

OBJECTIVE: To study the effect of the sphingosine kinase 1 (SphK1) inhibitor N,N-dimethylsphingosine (DMS) in combination with chemotherapeutic drugs (DDP, 5-Fu, MMC) on the proliferation of gastric cancer cells (SGC7901) in vitro, and to evaluate whether SphK1 inhibitors could be used as synergetic agents in chemotherapy. METHODS: SGC7901 cells were incubated in vitro with DMS (1 micromol/L) and 5-Fu, DDP, MMC at different concentrations in combination or separately for 24 h. The effects on the growth and survival of SGC7901 cells were determined by MTT assay. The inhibition rates were assessed by response surface analysis and the interactive relationships between the combined drugs were evaluated on the basis of positive/negative values of the cross product coefficients in the response surface equation. RESULTS: The growth inhibition rate of the gastric cancer cells by treatment with DMS (1 micromol/L) was (10.23 +/- 0.74)%. The growth inhibition rates of the gastric cancer cells treated with 5-Fu (1, 5 and 25 microg/ml) for 24 h were (9.95 +/- 3.24)%, (21.04 +/- 2.19)%, and (45.49 +/- 3.60)%, respectively. The growth inhibition rates of the gastric cancer cells treated with DDP (0.5, 2.5 and 12.5 microg/ml) for 24 h were (9.38 +/- 0.79)%, (19.61 +/- 0.90)%, and (29.83 +/- 0.54)%, respectively. The growth inhibition rates of the gastric cancer cells treated with MMC (0.1, 0.5 and 2.5 microg/ml) for 24 h were (15.35 +/- 0.77)%, (24.72 +/- 0.83)%, and (30.68 +/- 0.28)%, respectively. There were significant differences among the inhibition rates caused by different concentrations of the drugs (P < 0.05). When 1 micromol/L DMS was used in combination with 5-Fu (1, 5, and 25 microg/ml) for 24 h, the growth inhibition rates of the cancer cells were (16.76 +/- 0.41)%, (27.28 +/- 0.29)% and (52.56 +/- 3.60)%, respectively. When 1 micromol/L DMS was used in combination with DDP (0.5, 2.5, and 12.5 microg/ml) for 24 h, the growth inhibition rates of the cancer cells were (15.35 +/- 0.86)%, (25.57 +/- 0.27)%, (36.37 +/- 0.51)%, respectively. When 1 micromol/L DMS was used in combination with MMC (0.1, 0.5, and 2.5 microg/ml) for 24 h, the growth inhibition rates of the cancer cells were (21.02 +/- 0.28)%, (32.10 +/- 0.27)%, (36.36 +/- 0.28)%, respectively. There were also significant differences among the growth inhibition rates caused by different concentrations of the drugs alone and in combination groups (P < 0.05). CONCLUSIONS: DMS can suppress the proliferation of SGC7901 cells in vitro, and there are evident synergetic effects when it is used in combination with chemotherapeutic drugs. The results of this study indicate that SphK1 inhibitors may become novel and promising chemotherapeutic sensitizers.

[Protective effects and possible mechanism of lipoxin A(4) analogue in rats with acute pancreatitis].

OBJECTIVE: To explore the protective effects and possible mechanism of lipoxin A(4)-methyl ester (LXA(4)-ME) in rats with acute pancreatitis (AP). METHODS: A total of 120 male SD rats were randomly divided into 3 groups: Sham operation (n = 40), AP (n = 40) and LXA(4)-ME (n = 40). Sham operation group received normal saline after sham operation. AP was induced by a retrograde infusion of 5% sodium taurocholate into pancreatobiliary duct. AP group received normal saline after modeling. In the LXA(4)-ME group, LXA(4)-ME was administered (87.5 µg/kg) intravenously after the onset of AP. The rats were sacrificed at 12 h and 24 h post-induction. Their serum levels of amylase were detected. The amount of ascites was calculated and histological changes of pancreas were observed. The activities of myeloperoxidase (MPO) and levels of malonaldehyde (MDA) in pancreas were determined. The mRNA levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-10, intercellular adhesion molecule (ICAM-1), E-selectin and nuclear factor (NF)-κB p65 in pancreas were measured by reverse transcription-polymerase chain reaction (RT-PCR). The expression of NF-κB p65 protein was also measured by immunohistochemistry. RESULTS: Compared with the AP group, the pathological scores of the LXA(4)-ME group improved (12 h: 8.7 ± 1.3 vs 11.3 ± 1.5, 24 h: 7.8 ± 1.1 vs 11.7 ± 0.8) and the amount of ascites was lower(12 h: (6.88 ± 1.23) ml vs (12.32 ± 1.94) ml, 24 h: (6.53 ± 0.91) ml vs (14.15 ± 1.68) ml, all P < 0.01). The serum levels of amylase in the LXA(4)-ME group were significantly lower than those in the AP group respectively at 12 h and 24 h post-operation (all P < 0.01). The activity of MPO and the level of MDA in pancreas in the LXA(4)-ME group were significantly lower than those in the AP group (all P < 0.01). The pancreatic expressions of TNF-α mRNA, IL-1ß mRNA, ICAM-1 mRNA, E-selectin mRNA and NF-κB p65 mRNA at 12 h and 24 h decreased in the LXA(4)-ME group versus the AP group at the corresponding time points (all P < 0.01)while the expression of IL-10 mRNA increased versus the AP group at the corresponding time points (all P < 0.01). Compared with that in the AP group, the pancreatic expression of NF-κB p65 protein decreased in the LXA(4)-ME group (12 h: 24.8% ± 3.0% vs 45.3% ± 3.4%, 24 h: 31.6% ± 3.0% vs 48.1% ± 4.6%, both P < 0.01). CONCLUSION: LXA(4)-ME exerts protective effects in AP rats. And its mechanism may be due to the suppression of NF-κB activation.

[Influence of different NaCl concentration on passive behavior of Cr alloy in vitro].

OBJECTIVE: To investigate the properties of passive film of three Cr alloys and to analyze their corrosion resistance in the artificial saliva with different NaCl mass fraction in vitro. METHODS: Artificial saliva with 1%, 2% and 3% NaCl mass fraction was prepared. Cobalt-chromium alloy, nickel-chromium alloy and Ti-Ni-Cr alloy were employed as the working electrode in the artificial saliva. Semi-conductor properties of passive film on Cr alloy was analyzed by Mott-Schottky plots. In addition, the factors which affect the semi-conductive compact characteristic of the passive film was also discussed. RESULTS: The passive film exhibits n-type semi-conductive characters. With the increasing of NaCl mass fraction, the carrier density of the Cr alloys also increased. The carrier density of the cobalt-chromium alloy, nickel-chromium alloy and Ti-Ni-Cr alloy are 3.71 x 108, 2.34 x 109, and 7.66 x 109/cm³ respectively. This decreases its donor density and its film stability. CONCLUSIONS: When exposed to saliva environment with high concentration of chlorine ion, corrosion resistance of the three types of Cr alloys decrease. This will reduce the service life of Cr alloy prosthesis.

[Residue of PCBs and OCPs in the paddy soil from Hongfeng reservoir area, Guizhou, China].

Distributions of seven PCBs (polychlorinated biphenyls) congeners and 13 OCPs (organochlorinated pesticides) were investigated in paddy soil section in Hongfeng reservoir area. The results showed that DDTs and its metabolized compounds, isomer of HCHs, Endrin, heptachlor, PCB 28 and PCB 52 were detected in all soil samples. Compared to the polluted area, the concentrations of PCBs were lower in study area, while the compositions of organic pollutants in soil samples were similar. The dominant compositions of PCBs and OCPs were tri-, tetra-, and penta-chlorinated PCB congeners and DDTs respectively. The proportion of tri-, tetra-and penta-CB was 89 percent. The contents of DDTs were between 4.7 ng/g and 42.6 ng/g and p, p'-DDE, p, p'-DDT were the major isomers. The ratios of DDT/ (DDD + DDE) showed that the rate of DDTs degradation and environment status were different. The range of alpha-HCH/gamma-HCH was 0.28 - 0.90, indicating that HCHs had stayed for long time in environment. By photolysis and microbial, the proportion of the HCHs isomers had changed in Hongfeng reservoir area. SigmaTEQ of PCB118 and PCB180 were 0.06 - 0.51 pg/g.

[Mercury exchange fluxes between air and soil interface over different type of land in Wanshan Hg mine area].

Air/soil Hg exchange fluxes were measured using field chamber-automated air mercury analyzer method over different land in Wanshan Hg mine area in two seasons. The results showed that the air/soil Hg exchange fluxes were very strong. The highest Hg emission flux from soil was 27 827 ng/(m2 x h), the highest Hg deposition flux from the atmosphere was 9 434 ng/(m2 x h). Because of Hg emission from anthropogenic activities and natural lands, the Hg concentrations in air in Wanshan Hg mine area are 1 - 3 orders of magnitude greater than background area. The highest average Hg concentration in air reached 1 101.8 ng/m3, and the lowest average Hg concentration in air still reached 17.8 ng/m3. These indicated that the atmosphere was polluted seriously in Wanshan Hg mine area. The Hg exchange fluxes are influenced by solar irradiation and the Hg concentrations in air. The solar irradiation accelerates the Hg emission from soil. Conversely, the Hg concentration in air restrained the Hg emission from soil, and even leads the Hg concentration depositing to soil surface. The Hg emission fluxes from uncovered soil are higher than that from covered soil by vegetations significantly. And the slag becomes net atmospheric Hg source.