Citric Acid-sodium Citrate Research Articles

Ultrasonic-Assisted Synthesis of Lead Citrate as Precursor for Preparation of Lead Oxide from Lead Sulfate

ABSTRACT In this study, an efficient method of lead recovery from lead sulfate in spent lead-acid batteries assisted by ultrasonic is developed using the citric acid–sodium citrate solution. Ultrasonic-assisted technology is employed to enhance the kinetics of lead sulfate leaching. Initially, the predominance area of the lead citrate complexes was analyzed. The study was conducted to evaluate the effect of ultrasonic-assisted technology on the kinetic behavior of lead sulfate within the citric acid–sodium citrate solution, thereby unveiling the differences between ultrasonic-assisted leaching and the non-ultrasonic-assisted leaching. Kinetic study indicated that the employment of ultrasonic-assisted technology could effectively reduce the apparent activation energy during the desulfurization process, decreasing the energy initially required from 43.27 kJ/mol to 35.15 kJ/mol. Furthermore, the ultrasonic-assisted leaching led to successful preparation of lead citrate precursor, characterized by a smaller particle size and larger specific surface area. Systematic investigations were performed on the thermal decomposition process of these precursors and the effects of calcination temperature and holding time on the properties of calcination products. It was revealed that pure porous lead oxide powder with a purity of 99.9% could be produced successfully under the conditions of calcination temperature at 350°C and holding time of 1 h. The research provides an innovative process for the efficient recovery of lead from spent lead acid batteries.

Dapagliflozin Improves Angiogenesis after Hindlimb Ischemia through the PI3K-Akt-eNOS Pathway.

Recently, the vascular protective effect of anti-diabetic agents has been receiving much attention. Sodium glucose cotransporter 2 (SGLT2) inhibitors had demonstrated reductions in cardiovascular (CV) events. However, the therapeutic effect of dapagliflozin on angiogenesis in peripheral arterial disease was unclear. This study aimed to explore the effect and mechanism of dapagliflozin on angiogenesis after hindlimb ischemia. We first evaluated the effect of dapagliflozin on post-ischemic angiogenesis in the hindlimbs of rats. Laser doppler imaging was used to detect the hindlimb blood perfusion. In addition, we used immunohistochemistry to detect the density of new capillaries after ischemia. The relevant signaling pathways of dapagliflozin affecting post-ischemic angiogenesis were screened through phosphoproteomic detection, and then the mechanism of dapagliflozin affecting post-ischemic angiogenesis was verified at the level of human umbilical vein endothelial cells (HUVECs). After subjection to excision of the left femoral artery, all rats were randomly distributed into two groups: the dapagliflozin group (left femoral artery resection, receiving intragastric feeding with dapagliflozin (1 mg/kg/d), for 21 consecutive days) and the model group, that is, the positive control group (left femoral artery resection, receiving intragastric feeding with citric acid-sodium citrate buffer solution (1 mg/kg/d), for 21 consecutive days). In addition, the control group, that is the negative control group (without left femoral artery resection, receiving intragastric feeding with citric acid-sodium citrate buffer solution (1 mg/kg/d), for 21 consecutive days) was added. At day 21 post-surgery, the dapagliflozin-treatment group had the greatest blood perfusion, accompanied by elevated capillary density. The results showed that dapagliflozin could promote angiogenesis after hindlimb ischemia. Then, the ischemic hindlimb adductor-muscle tissue samples from three rats of model group and dapagliflozin group were taken for phosphoproteomic testing. The results showed that the PI3K-Akt-eNOS signaling pathway was closely related to the effect of dapagliflozin on post-ischemic angiogenesis. Our study intended to verify this mechanism from the perspective of endothelial cells. In vitro, dapagliflozin enhanced the tube formation, migration, and proliferation of HUVECs under ischemic and hypoxic conditions. Additionally, the dapagliflozin administration upregulated the expression of angiogenic factors phosphorylated Akt (p-Akt) and phosphorylated endothelial nitric oxide synthase (p-eNOS), as well as vascular endothelial growth factor A (VEGFA), both in vivo and in vitro. These benefits could be blocked by either phosphoinositide 3-kinase (PI3K) or eNOS inhibitor. dapagliflozin could promote angiogenesis after ischemia. This effect might be achieved by promoting the activation of the PI3K-Akt-eNOS signaling pathway. This study provided a new perspective, new ideas, and a theoretical basis for the treatment of peripheral arterial disease.

Enrichment of Flavonoids in Short-Germinated Black Soybeans (Glycine max L.) Induced by Slight Acid Treatment.

Exogenous abiotic stimulant treatments are a straightforward and effective method for enhancing secondary metabolites in plants. In this study, the response surface optimization method was used to optimize the conditions for enriching flavonoids in short-germinated black soybeans under a slight acid treatment, and the mechanism of flavonoid accumulation during black soybean germination was explored. The results show that the use of a 126.2 mM citric acid-sodium citrate buffer (pH 5.10) as a slight acid treatment resulted in the highest flavonoid content when the black soybeans were germinated for 24 h. Under these conditions, the isoflavonoid (glycitin, daidzein, and genistein) increased significantly, and the flavonoid content reached 2.32 mg/g FW. The microacidified germination treatment significantly increased the activities and relative gene expression levels of key enzymes involved in flavonoid metabolism (4-coumarate-CoA ligase and cinnamic acid 4-hydroxylase, etc.). However, the slight acid treatment inhibited the growth of the black soybeans and caused damage to their cells. This was evidenced by significantly higher levels of malondialdehyde, superoxide anion, and hydrogen peroxide compared to the control group. Furthermore, the antioxidant system in the short-germinated soybeans was activated by the slight acid treatment, leading to a significant increase in the activities and relative gene expression levels of catalase and peroxidase. The results above show that a slight acid treatment was beneficial in inducing the accumulation of flavonoids during the growth of black soybean sprouts. This lays a technical foundation for producing black soybean products that are rich in flavonoids.

Diclofenac\u2013hyaluronate conjugate (diclofenac etalhyaluronate) intra-articular injection for hip, ankle, shoulder, and elbow osteoarthritis: a randomized controlled trial

BackgroundTo evaluate the efficacy and safety of intra-articular injection of diclofenac etalhyaluronate (DF-HA) in patients with osteoarthritis (OA) of the hip, ankle, shoulder, or elbow.MethodsIn this randomized, placebo-controlled, double-blind study in Japan, Japanese patients aged ≥20 years diagnosed with OA of the hip, ankle, shoulder, or elbow were randomly assigned 1:1 to DF-HA 30 mg or placebo (citric acid-sodium citrate buffered solution). Subjects received three injections of the study drug in each joint cavity every 4 weeks and were assessed for 12 weeks after the first injection. The primary endpoint was the mean change from baseline in a diary-based 11-point numerical rating scale (NRS) for pain over 12 weeks, analyzed for each joint. Treatment-emergent adverse events were recorded, and morphological changes in each joint were evaluated radiographically.ResultsThe study drug (DF-HA vs placebo) was injected into 90, 60, 90, or 50 subjects with OA of the hip, ankle, shoulder, or elbow (46 vs 44, 30 vs 30, 45 vs 45, and 25 vs 25, respectively). The group differences in the mean change from baseline in the pain NRS over 12 weeks were − 0.81 (95% confidence interval: − 1.48 to − 0.13), − 0.07 (− 1.03 to 0.89), 0.15 (− 0.48 to 0.78), and 0.61 (− 0.41 to 1.62) for the hip, ankle, shoulder, and elbow joints, respectively, with statistically significant differences observed only in the hip joint. The change from baseline in the hip joint was greater with DF-HA than placebo at all time points from Weeks 1–12. No clinically significant adverse events or radiographic changes were observed.ConclusionsIntra-articularly administered DF-HA for hip OA produced a rapid response and was safe, with analgesia maintained for 12 weeks when administered every 4 weeks.Trial registrationJapicCTI-173,678 (First registered date: 21 August 2017).

Transient Chemical Activation of Covalent Bonds for Healing of Kinetically Stable and Multifunctional Organohydrogels

Transient Chemical Activation of Covalent Bonds for Healing of Kinetically Stable and Multifunctional Organohydrogels

Mechanism study of the protective effects of selective cyclooxygenase-2 enzyme inhibitors on the liver of rats with type 2 diabetes mellitus combined with nonalcoholic steatohepatitis via Rho/ROCK pathway

Objective: To investigate whether the selective cyclooxygenase-2 enzyme inhibitors celecoxib has protective effect on the liver of rats with type 2 diabetes mellitus (T2DM) combined with nonalcoholic steatohepatitis (NASH) via inhibiting the expression of Rho/ROCK pathway. Methods: Forty male SD rats were randomly divided into four groups: type 2 diabetes mellitus combined with nonalcoholic steatohepatitis (T2DM-NASH) group, T2DM-NASH + celecoxib group, control group, and control+celecoxib group. The T2DM-NASH and T2DM-NASH + celecoxib groups were fed with high-sugar and fat diet, and the control group and control + celecoxib group were fed with basal diet (25 kJ/kg). Four weeks later, streptozotocin (STZ, 30 mg/kg) was intraperitoneally injected into the NASH group and T2DM-NASH + celecoxib group to induce T2DM model, and the control group and control + celecoxib group were intraperitoneally injected with isovolumic citric acid-sodium citrate buffer. Four weeks after STZ injection, the T2DM-NASH + celecoxib group and the control + celecoxib group were gavaged with celecoxib (10 mg·kg·d) dissolved in normal saline for 4 weeks, and the remaining two groups of rats were gavaged with isovolumic normal saline for 4 weeks. Animals were sacrificed at the end of the 12- weeks, and the liver tissue was collected. Liver pathological changes were observed by HE staining. The expressions of RhoA, RhoA, ROCK1 and ROCK2 proteins in liver were detected by immunohistochemistry and western blot. The expressional condition of RhoA, ROCK1 and ROCK2 mRNA in liver were detected by real-time quantitative PCR. The differences were compared between protein and mRNA expression among the groups by analysis of variance and t-test. Results: Compared with the control group and the control + celecoxib group, the liver tissue of the T2DM-NASH group and the T2DM-NASH + celecoxib group had severe steatosis, and there was partial inflammatory cell infiltration under the light microscope. The expression levels of RhoA, ROCK1 and ROCK2 protein and mRNA were significantly increased (P < 0.05) in each liver tissue, while liver steatosis was reduced to certain extent in T2DM-NASH + celecoxib group than T2DM-NASH group, and the expression levels of RhoA, ROCK1 and ROCK2 protein and mRNA were decreased in each liver tissue of T2DM-NASH group (P < 0.05). Conclusion: The selective cyclooxygenase-2 enzyme inhibitors celecoxib has a protective effect on the liver of rats with T2DM-NASH, and its effect may be achieved by inhibiting the expression of Rho/ROCK pathway.

Electrokinetic remediation of Pb near the e-waste dismantle site with Fe(NO3)3 as cathode electrolyte

ABSTRACT In this study, Pb-contaminated soil in the e-waste dismantle site was remediated by activated carbon fiber (ACF) enhanced electrokinetic remediation. Experiments were conducted using Fe(NO3)3 as catholyte and citric acid-sodium citrate as anolyte with different conditions: pH value of anolyte, voltage and the electrode gap. At the same time, we set up a group of contrast test without ACF to investigate the adsorption performance of ACF for Pb. Results showed that the highest removal rate of Pb after the remediation was 80.53% at 4 cm from the anode when the electrode gap was 31 cm, pH value was 3 and the voltage was 28 V, and the total removal rate increased significantly with the decrease of the pH value of anolyte and the increase of voltage. Characterization of ACF after reaction showed that ACF effectively adsorbed heavy metal Pb, and the adsorption amount was 1.42 mg/g. Sequential extraction analysis revealed that Pb mainly existed in the forms of organic matter bound and residual in the soil after remediation. These forms are relatively stable and low toxicity, indicating that the remediation has significantly reduced the harm of Pb to the environment.

The value of diffusion kurtosis imaging in early diagnosis of diabetic nephropathy model in Guangxi Bama mini pig

Objective To investigate the value of diffusion kurtosis imaging (DKI) in diagnosing early diabetic nephropathy. Methods Twelve pigs were divided into the experimental group (7 pigs) and the control group (5 pigs), used the random number table method. The experimental group was fed with high-fat high-sugar diet,and then repeatedly injected small doses (50 mg/kg) of Streptozotocin (STZ) through the ear vein. Meanwhile,the control group was fed with normal diet and injected with the same dose of citric acid-sodium citrate buffer solution.After the type 2 diabetes was established successfully, T1WI, T2WI and DKI sequence imaging were performed every month for 2 pigs from the experimental group and the control group,respectively.Mean kurtosis(MK), axial kurtosis (K∥), radial kurtosis (K⊥), fractional anisotropy (FA) and mean diffusivity(MD) were measured on the pseudo-color map of the post-processing workstation. fasting blood glucose(GLU),insulin (INS),renal function, urine routines and random albumin creatinine ratio(RACR) were measured before MRI scan. Specimens from bilateral kidneys were taken for pathological examination after MRI scan. The paired t test was used to compare the parameter values of the cortex and medulla.Independent sample t test was used tocompare the parameter values of the experimental group and the control group. Results In the experimental group,the MK, FA values of medulla were 0.66±0.07 and 0.19±0.04, the MK, FA values of cortex were 0.60±0.06 and 0.16±0.03.In the control group,the MK, FA values of medulla were 0.59±0.03 and 0.20±0.04, the MK, FA values of cortex were 0.53±0.03 and 0.17±0.04.The MK and FA values of medulla were increased compared with the cortex and the difference were statistically significant (P 0.05). Conclusion DKI sequencehas certain value in the diagnosis of early diabetic nephropathy,and to some extent reveals the pathological change in early diabetic nephropathy. Key words: Diabetic nephropathies; Magnetic resonance imaging; Disease models, animal

A simplified and miniaturized glucometer-based assay for the detection of β-glucosidase activity.

β-Glucosidase activity assays constitute an important indicator for the early diagnosis of neonatal necrotizing enterocolitis and qualitative changes in medicinal plants. The drawbacks of the existing methods are high consumption of both time and reagents, complexity in operation, and requirement of expensive instruments and highly trained personnel. The present study provides a simplified, highly selective, and miniaturized glucometer-based strategy for the detection of β-glucosidase activity. Single-factor experiments showed that optimum β-glucosidase activity was exhibited at 50 °C and pH 5.0 in a citric acid-sodium citrate buffer when reacting with 0.03 g/mL salicin for 30 min. The procedure for detection was simplified without the need of a chromogenic reaction. Validation of the analytical method demonstrated that the accuracy, precision, repeatability, stability, and durability were good. The linear ranges of β-glucosidase in a buffer solution and rat serum were 0.0873-1.5498 U/mL and 0.4076-2.9019 U/mL, respectively. The proposed method was free from interference from β-dextranase, snailase, β-galactosidase, hemicellulase, and glucuronic acid released by baicalin. This demonstrated that the proposed assay had a higher selectivity than the conventional dinitrosalicylic acid (DNS) assay because of the specificity for salicin and unique recognition of glucose by a personal glucose meter. Miniaturization of the method resulted in a microassay for β-glucosidase activity. The easy-to-operate method was successfully used to detect a series of β-glucosidases extracted from bitter almonds and cultured by Aspergillus niger. In addition, the simplified and miniaturized glucometer-based assay has potential application in the point-of-care testing of β-glucosidase in many fields, including medical diagnostics, food safety, and environmental monitoring.

Effect of Delta-like ligand 4 on pathological structure of retina in early diabetic rats and its relationship with vascular endothelial growth factor receptor-2

Objective To observe the effect of Delta-like ligand 4 (Dll-4) on the pathological structure of retina in early diabetic rats (DM) and its relationship with vascular endothelial growth receptor-2 (VEGFR-2). Methods A total of 70 male Sprague-Dawley rats were randomly divided into normal group and DM group, with 10 and 60 rats in each group, respectively. The rats of DM group was induced by intraperitoneal injection of streptozotocin to established DM model. The rats with blood glucose recovery and death were excluded, and the final 60 rats were included in the statistics. Rats in the normal group were injected with an equal volume of citric acid-sodium citrate buffer. Rats in the DM group were divided into DM 1 month (DM 1m) group, DM 2 months(DM 2m) group, DM 3 months (DM 3m) group and DM 3m + Anti group, DM 3m + phosphate buffer solution(PBS) group by random number table method, and 10 rats in each group. In the DM 3m+Anti group, 4 μl of anti- Dll-4 polyclonal antibody was injected into the vitreous cavity, and the antibody concentration was 0.25 mg/ml. The DM 3m+PBS group was intravitreally injected with an equal volume of PBS. Five days after the injection, the rats were sacrificed. Rats in the DM 3m group and the normal group were not treated, and were sacrificed 3 months after the model was established. The structure and microvascular changes of the retina were observed by hematoxylin-eosin staining, and the total thickness of the retina was measured. The expression of Dll-4 and VEGFR-2 in the retina was detected by immunohistochemistry and fluorescence quantitative polymerase chain reaction (PCR). One-way analysis of variance was used to compare the expression of Dll-4 and VEGFR-2 in the retina of each group. The least significant difference t test was used to compare the two groups. Results Light microscopy showed that the retinal ganglion cells layer in the DM 3m group were obviously edematous, the inner and outer nuclear layers were thinner, the number of cells was reduced, the arrangement was disordered, the edema of outer plexiform layer was obvious, and the microvessels were abnormally dilated. In the DM 3m+Anti group, the edema of outer plexiform layer was lessened than that of the DM 3m group, and the other layers were not significantly different from the DM 3m group. Compared with the normal group, the total retinal thickness of the DM 3m group, the DM 3m+Anti group and the DM 3m+PBS group increased (t=5.596, 3.290, 4.286; P=0.000, 0.008, 0.002). Immunohistochemical staining showed that a small amount of Dll4 was positively expressed in the retinal ganglion cell layer of the normal group; a small amount of VEGFR-2 was positively expressed in the ganglion cell layer and the inner and outer nuclear layers. The positive expression of Dll-4 and VEGFR-2 in retinal vascular endothelial cells of DM 3m group increased significantly. The expression of Dll-4 was significantly decreased in the retinal layers and vascular endothelial cells of DM 3m+Anti group, while the expression of VEGFR-2 was significantly increased. There was no significant difference between the positive expression of Dll4 and VEGFR-2 in the DM 3m+PBS group and the DM 3m group. The results of real-time PCR showed that the relative expression of Dll-4 and VEGFR-2 mRNA in the DM 3m group was significantly higher than that in the normal group (t=6.705, 20.871; P<0.05). Compared with DM 3m group, the relative expression of Dll-4 mRNA in DM 3m+Anti group decreased, and the relative expression of VEGFR-2 mRNA increased(t=2.681, 3.639;P<0.05). The relative expressions of Dll-4 and VEGFR-2 mRNA in the DM 3m+PBS group and DM 3m group were not statistically significant (t=0.513, 0.657; P<0.05). Conclusions The expression of Dll-4 in retinal vascular endothelial cells is gradually increased during the early retinopathy of DM rats. The expression of Dll-4 is inhibited, the expression of VEGFR-2 is up-regulated, and the plexus edema is alleviated. Key words: Diabetic retinopathy; Detal like 4; Vascular endothelial growth factor receptor 2

Effect of point-moxibustion on ghrelin and GHSR-1a expressions in lateral septal nucleus of rats with diabetic gastroparesis

To observe the effect of point-moxibustion on gastrointestinal motility, mRNA and protein expressions of ghrelin and growth hormone secretagogue receptor 1a (GHSR-1a) in lateral septal nucleus of rats with diabetic gastroparesis (DGP), and to investigate the central regulatory mechanism of DGP treatment with point-moxibustion. Forty SPF-grade Sprague-Dawley (SD) rats were randomly divided into a blank group, a model group, an electroacupuncture (EA) group and a point-moxibustion group, with 10 rats in each group. A DGP rat model was established by intraperitoneal injection of 2% streptozotocin (STZ) with 8-week irregular high-sugar and high-fat diet in the model group, the EA group and the point-moxibustion group; and rats in the blank group were injected intraperitoneally with 0.1 mmoL/L (pH 4.5) citric acid-sodium citrate buffer with 8-week normal diet. Eight weeks later, rats in the EA group were treated by EA at Zusanli (ST 36), Liangmen (ST 21) and Sanyinjiao (SP 6); while rats in the point-moxibustion group were treated by point-moxibustion at Zusanli (ST 36), Liangmen (ST 21) and Sanyinjiao (SP 6) for successive 15 d. Rats in the blank group and the model group were fixed as the control without intervention. After treatment, intestinal propulsion rate and gastric emptying rate were measured. The mRNA and protein expressions of ghrelin and GHSR-1a in the lateral septal nucleus were detected by real-time polymerase chain reaction (RT-PCR) and Western blot (WB). Compared with the blank group, the intestinal propulsion rate and gastric emptying rate of the model group were significantly lower (both P 0.05). Point-moxibustion at Zusanli (ST 36), Liangmen (ST 21) and Sanyinjiao (SP 6) can increase the intestinal propulsion rate and gastric emptying rate of DGP rats, and promote the mRNA and protein expressions of ghrelin and GHSR-1a in the central nervous system. The mechanism may be related to the activation of ghrelin pathway in hypothalamic arcuate nucleus-lateral septal nucleus.

PbSO4 Leaching in Citric Acid/Sodium Citrate Solution and Subsequent Yielding Lead Citrate via Controlled Crystallization

Lead citrate is a key precursor for the green recycling of spent lead acid battery paste in a citric acid/sodium citrate (CA/SC) solution. In this study, the main paste component, PbSO4, was leached and crystallized to yield lead citrate. Results showed that the leaching of PbSO4 in citric acid/sodium citrate solution was remarkably enhanced by an increase in temperature from 35 °C to 95 °C and an increase in sodium citrate (SC) concentration from 50 to 650 g/L. In comparison, increasing the citric acid/sodium citrate molar ratio inhibited this leaching. Controlled crystallization through cooling the solution or adjusting the pH of the solution can effectively produce lead citrate crystals. The X-ray diffraction patterns of four products obtained in a comparison test were all consistent with Pb3(C6H5O7)2. However, the scanning electron microscopy analysis suggested that the morphology was distinct from rods to sheets, which were mainly affected by the temperature variation.

&lt;i&gt;In Vitro&lt;/i&gt; Evaluation of Biomimetic Incorporation and Release Kinetics of BMP2 on Functionalized Bio-Oss&lt;sup&gt;®&lt;/sup&gt; Block

Objective: To functionalize the Bio-Oss® Block with biomimetic coating incorporating BMP2 and evaluate the release kinetics of the incorporated BMP2 In Vitro.Materials and methods: Bio-Oss® Blocks were prepared with the size of 7mm x 10mm x 4mm. Each block was immersed and suspended in 300ml 5-fold-concentrated modified Tyrode solution for 24 hours to form a seeding substratum. BMP2 at the concentration of 10ug/ml was added into 120ml supersaturated calcium phosphate solution and co-precipitated within the growing layer for 48 hours. The loading amount of incorporated BMP2 was determined using enzyme-linked immunosorbent assay . The surface characterization of the coating was evaluated by scanning electron microscopy. The distribution of coating-incorporated protein was mapped by a confocal laser-scanning microscope. BMP2 release profiles from the functionalized blocks under different circumstances were monitored. Results: The total loading of BMP2 in a BMP2-incorporated-block is 50.35 ± 6.41μg. The crystalline coating layer deposited on both the superficial surfaces and internal surfaces of the blocks. The BMP2 was distributed homogeneously in the whole block. The coating-incorporated depot of BMP2 barely released in Tris-HCl buffered solution (pH of 7.4). However, when the functionalized blocks were immersed in Citric acid-Sodium citrate buffered solution (pH of 5), or were co-cultured with osteoclasts, the coating-incorporated BMP2 depot showed a sustained release.Conclusions: BMP2 were successfully incorporated onto and into the Bio-Oss® Blocks. A sustained delivery of a lower concentration of BMP2 (μg-BMP2) from Bio-Oss® Block was achieved in acidic solution or with the mediation of osteoclasts.

Dissipation kinetics of oxytetracycline, tetracycline, and chlortetracycline residues in soil.

The dissipation of different residual states of tetracycline antibiotics (TCs) including oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) laboratory microcosm systems was investigated in this study. The residues were fractionated by stepwise extractions into aqueous state (KCl solution extracts), organic state (MeOH extracts), residual state I (citric acid-sodium citrate buffer and ethyl acetate extracts) and residual state II (acetonitrile-EDTA-McIlvaine buffer extracts) for accurate evaluation of TCs pollution. The antibiotics in the aqueous state were hardly detected, whereas the antibiotics in the organic state dissipated relatively fast (not detectable within 15days after application) and followed simple first-order kinetics (SFOK) (R (2) from 0.929 to 0.990). While first-order double-exponential decay model (FODED) (R (2) from 0.840 to 0.999) and availability-adjusted first-order model (AAFO) (R (2) from 0.939 to 0.999) had a better fit on the dissipation of both residue state I and II than SFOK. TCs in these states were likely sequestered into a dormant undegradable phase since no degradation product was detected during the entire experiment. In addition, the overall 50% dissipation values (i.e., stability) of the three TCs were OTC > TC > CTC. The TCs tend to dissipate faster in the high water content and organic matter soil.

A simple, ultrasensitive sensor for gallic acid and uric acid based on gold microclusters/sulfonate functionalized graphene modified glassy carbon electrode

A facile and ultrasensitive sensor based on gold microclusters (AuMCs) electrodeposited on sulfonate functionalized graphene (SF-GR) was fabricated, and applied for the simultaneous determination of gallic acid (GA) and uric acid (UA). Taking advantage of the unique plane structure of the functionalized graphene (GR), the AuMCs were successfully electrodeposited on functionalized GR immobilized on the surface of a GCE. The results of scanning electron microscope (SEM) and energy spectrum analysis illustrated that AuMCs were deposited on the functionalized GR film. In comparison with the bare GCE, the pristine AuMCs and the pristine SF-GR modified electrode, AuMCs/SF-GR/GCE exhibited excellent electrochemical oxidation toward GA and UA. In addition, the two compounds were separated completely in 0.10M citric acid-sodium citrate buffer (pH 4.0) by differential pulse voltammetry (DPV) under optimum conditions. The anodic current was linearly related with 0.05–8.0μM GA and 0.2–50.0μM UA, with the detection limit of 10.7nM and 0.12μM, respectively. Furthermore, AuMCs/SF-GR/GCE was successfully applied to the independent determination of GA in black tea and Cortex moutan as well as the simultaneous determination of GA and UA in urine samples.

Chemical and electrochemical study of the inhibition of calcium carbonate precipitation using citric acid and sodium citrate

This work investigated the inhibitive effect of citric acid (CA), sodium citrate (SC), and their mixture (CA–SC) on the CaCO3 scale. The study was carried out using chronoamperometry, impedancemetry, and fast-controlled precipitation methods. The electrochemical study showed that CA provides a slight inhibition of CaCO3 deposit at a concentration of 70 ppm on stainless steel surface. The use of SC alone inhibits very little the formation of scale. The use of the mixture (50% of CA and 50% of SC) with small concentration led to significant inhibition of the CaCO3 formation. The deposits formed were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The XRD showed that the intensity of the preferential orientation (1 0 4) corresponding to crystallographic plans of calcite decreases and the SEM demonstrated a decrease in calcite crystal size from 10 to about 2 μm.

Simultaneous detection of metronidazole and chloramphenicol by differential pulse stripping voltammetry using a silver nanoparticles/sulfonate functionalized graphene modified glassy carbon electrode

A novel silver nanoparticles/sulfonated functionalized graphene modified glassy carbon electrode (AgNPs/SF-GR/GCE) was fabricated to determine chloramphenicol and metronidazole simultaneously. Taking advantage of sulfonic group, AgNPs were successfully electrodeposited on functionalized GR immobilized on the surface of a GCE. Scanning electron microscopy and energy spectrum analysis results confirmed that AgNPs were deposited on the functionalized GR film. Compared to the bare GCE or the pristine SF-GR modified electrode, AgNPs/SF-GR/GCE exhibited excellent electroreduction towards chloramphenicol and metronidazole. In addition, the two antibacterial drugs were separated completely in 0.10M citric acid-sodium citrate buffer (pH 4.0) by differential pulse stripping voltammetry under optimum conditions. The cathodic current was linearly related with 0.02∼20.0μM chloramphenicol and 0.10∼20.0μM metronidazole, with the detection limits of 0.01μM and 0.05μM respectively. Furthermore, AgNPs/SF-GR/GCE was applied to the simultaneous determination of chloramphenicol and metronidazole in an aquatic product.

Determination of total arsenic and arsenic(III) in phosphate fertilizers by hydride generation atomic absorption spectrometry after ultrasound-assisted extraction based on a control acid media.

An ultrasound-assisted extraction procedure was developed for determination of inorganic arsenic (As) in phosphate fertilizer by hydride generation atomic absorption spectrometry. The variables that affect the hydride generation step were optimized, including the reducer, acid, sample flow rate, and concentrations of the acid and reducer. The determination of As(lll) was performed through the simple control of solution pH with a 0.5 M citric acid-sodium citrate buffer solution at pH 4.5, and total As was determined after a pre-reduction reaction with 1.0% (w/v) thiourea. Ultrasound-assisted acid extraction was performed, and the parameters sonication time and acid and Triton X-114 concentrations were optimized using a 23 factorial design and central composite design. LODs for As(lll) and total As were 0.029 and 0.022 microg/L, respectively. The accuracy of the method was confirmed with certified reference materials. The method was successfully applied in the determination of inorganic As in phosphate fertilizer samples.

Study on Enzymatic Degradation of Cornstalk in Ionic Liquid

The influence of reaction conditions on the enzymatic degradation of cornstalk in the system of 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) was investigated. The optimum condition was as follows: 5 g 4 wt% cornstalk in ionic liquid solution, 3.64 mL pH 5 citric acid–sodium citrate buffer solution, the concentration of cornstalk 55 mg/mL, the ratio of enzyme and cornstalk 0.5 mL/g, reaction temperature 55 °C and reaction time 30 h. Under the optimum condition, the rate of enzymatic degradation was 96.6 %, and was 2.1 times quicker than under the conventional condition. The changes of the molecular structure of cornstalk dissolved in [EMIM]OAc were detected by FT-IR and SEM. It was also found that ionic liquid [EMIM]OAc had good reusability.

Role of mTOR in spinal cord in development of diabetic neuropathic pain in rats

Objective To evaluate the role of mTOR in spinal cord in the development of diabetic neuropathic pain in rats.Methods Sixty adult male Sprague-Dawley rats,aged 2 months,weighing 180-220 g,were used in the study.Forty-five rats among them were chosen randomly and diabetes mellitus was induced by intraperitoneal streptozotocin (STZ) 60 mg/kg and confirmed by blood glucose ＞ 16.7 mmol/L on day 3 after STZ injection.The left 15 rats received intraperitoneal injection of the equal volume of citric acid-sodium citrate buffer and served as normal control group (group C).Paw withdrawal threshold to von Frey filament stimulation was measured in the right hind paw before STZ injection and on 3,6,9,12,15,18,and 21 days after STZ injection.The diabetic rats with mechanical pain threshold decreasing by more than 50％ of the baseline were allocated to diabetic neuropathic pain group (group DP),and by less than 25 ％ of the baseline were allocated to diabetic non-neuropathic pain group (group NP).The rats were sacrificed at 21 days after STZ injection,and their lumbar enlargements of the spinal cord were removed for determination of the expression of mTOR and phosphorylated mTOR (p-mTOR) by Western blot.Results The expression of mTOR was significantly up-regulated in DP and NP groups when compared with group C (P ＜ 0.05),the expression of p-mTOR was up-regulated in DP group,and no significant change was found in the expression of p-mTOR in group NP (P ＞ 0.05).Compared with group NP,the expression of p-mTOR was significantly up-regulated (P ＜ 0.05),and no significant change was found in the expression of mTOR in group DP (P ＞ 0.05).Conclusion Activation of mTOR in the spinal cord is involved in the development of diabetic neuropathic pain in rats. Key words: Receptor-interacting protein serine-threonine kinases; Diabetic neuropathies