Identification of Critical Amino Acids of Coxsackievirus A10 Associated with Cell Tropism and Viral RNA Release during Uncoating.

Coxsackievirus A10 (CV-A10) is a prevailing causative agent of hand-foot-mouth disease, necessitating the isolation and adaptation of appropriate strains in cells allowed for human vaccine development. In this study, amino acid sequences of CV-A10 strains with different cell tropism on RD and Vero cells were compared. Various amino acids on the structural and non-structural proteins related to cell tropism were identified. The reverse genetic systems of several CV-A10 strains with RD+/Vero- and RD+/Vero+ cell tropism were developed, and a set of CV-A10 recombinants were produced. The binding, entry, uncoating, and proliferation steps in the life cycle of these viruses were evaluated. P1 replacement of CV-A10 strains with different cell tropism revealed the pivotal role of the structural proteins in cell tropism. Further, seven amino acid substitutions in VP2 and VP1 were introduced to further investigate their roles played in cell tropism. These mutations cooperated in the growth of CV-A10 in Vero cells. Particularly, the valine to isoleucine mutation at the position VP1-236 (V1236I) was found to significantly restrict viral uncoating in Vero cells. Co-immunoprecipitation assays showed that the release of viral RNA from the KREMEN1 receptor-binding virions was restricted in r0195-V1236I compared with the parental strain r0195 (a RD+/Vero+ strain). Overall, this study highlights the dominant effect of structural proteins in CV-A10 adaption in Vero cells and the importance of V1236 in viral uncoating, providing a foundation for the mechanism study of CV-A10 cell tropism, and facilitating the development of vaccine candidates.

Identification of a Conserved, Linear Epitope on VP3 of Enterovirus A Species Recognized by a Broad-Spectrum Monoclonal Antibody.

Outbreaks of hand, foot and mouth disease (HFMD) have occurred frequently in the Asian-Pacific region over the last two decades, caused mainly by the serotypes in Enterovirus A species. High-quality monoclonal antibodies (mAbs) are needed to improve the accuracy and efficiency of the diagnosis of enteroviruses associated HFMD. In this study, a mAb 1A11 was generated using full particles of CV-A5 as an immunogen. In indirect immunofluorescence and Western blotting assays, 1A11 bound to the viral proteins of CV-A2, CV-A4, CV-A5, CV-A6, CV-A10, CV-A16, and EV-A71 of the Enterovirus A and targeted VP3. It has no cross-reactivity to strains of Enterovirus B and C. By mapping with over-lapped and truncated peptides, a minimal and linear epitope 23PILPGF28 was identified, located at the N-terminus of the VP3. A BLAST sequence search of the epitope in the NCBI genus Enterovirus (taxid: 12059) protein database indicates that the epitope sequence is highly conserved among the Enterovirus A species, but not among the other enterovirus species, first reported by us. By mutagenesis analysis, critical residues for 1A11 binding were identified for most serotypes of Enterovirus A. It may be useful for the development of a cost-effective and pan-Enterovirus A antigen detection for surveillance, early diagnosis and differentiation of infections caused by the Enterovirus A species.

Humoral and cellular immunogenicity and efficacy of a coxsackievirus A10 vaccine in mice.

Coxsackievirus A10 (CV-A10) has become one of the major pathogens of hand, foot and mouth disease (HFMD), and studies on the vaccine and animal model of CV-A10 are still far from complete. Our study used a mouse-adapted CV-A10 strain, which was lethal for 14-day-old mice, to develop an infected mouse model. Then this model was employed to establish an actively immunized-challenged mouse model to evaluate the efficacy of a formaldehyde-inactivated CV-A10 vaccine, which was prepared from a Vero cell-adapted strain. CV-A10 vaccine at a dose of 0.5 or 2.0 µg was inoculated intraperitoneally in neonatal Kunming mice on the third and ninth day. Then the mice were challenged on day 14. The survival rate of mice immunized with 0.5 or 2.0 µg vaccine were 90% and 100%, respectively, while all Alum-inoculated mice died. Compared to those in the two vaccinated groups, the Alum-inoculated mice showed severe pathological damage, strong viral protein expression and high viral loads. The antisera from vaccinated mice showed high level of neutralizing antibodies against CV-A10. Meanwhile, three potential T cell epitopes located at the carboxyl-terminal regions of the VP1 and VP3 were identified and exhibited CV-A10 serotype-specific. The humoral and cellular immunogenicity analysis showed that immunization with two doses of the vaccine elicited CV-A10 specific neutralizing antibody and T cell response in BALB/c mice. Collectively, these findings indicated that this actively immunized-challenged mouse model will be invaluable in future studies on CV-A10 pathogenesis and evaluation of vaccine candidates.

Efficacy of a coxsackievirus A6 vaccine candidate in an actively immunized mouse model.

Coxsackievirus A6 (CV-A6) has been emerging as a major pathogen of hand, foot and mouth disease (HFMD). Study on the pathogenesis of CV-A6 infection and development of vaccines is hindered by a lack of appropriate animal models. Here, we report an actively immunized-challenged mouse model to evaluate the efficacy of a Vero-cell-based, inactivated CV-A6 vaccine candidate. The neonatal Kunming mice were inoculated with a purified, formaldehyde-inactivated CV-A6 vaccine on days 3 and 9, followed by challenging on day 14 with a naturally selected virulent strain at a lethal dose. Within 14 days postchallenge, all mice in the immunized groups survived, while 100% of the Alum-only inoculated mice died. Neutralizing antibodies (NtAbs) were detected in the serum of immunized suckling mice, and the NtAb levels correlated with the survival rate of the challenged mice. The virus loads in organs were reduced, and pathological changes and viral protein expression were weak in the immunized mice compared with those in Alum-only inoculated control mice. Elevated levels of interleukin-4, 6, interferon γ and tumour necrosis factor α were also observed in Alum-only control mice compared with immunized mice. Importantly, the virulent CV-A6 challenge strain was selected quickly and conveniently from a RD cell virus stock characterized with the natural multi-genotypes. The virulent determinants were mapped to V124M and I242 V at VP1. Together, our results indicated that this actively immunized mouse model is invaluable for future studies to develop multivalent vaccines containing the major component of CV-A6 against HFMD.

Efficacy of Coxsackievirus A5 Vaccine Candidates in an Actively Immunized Mouse Model.

Coxsackievirus A5 (CV-A5) has recently emerged as a main hand, foot, and mouth disease (HFMD) pathogen. Following a large-scale vaccination campaign against enterovirus 71 (EV-71) in China, the number of HFMD-associated cases with EV-71 was reduced, especially severe and fatal cases. However, the total number of HFMD cases remains high, as HFMD is also caused by other enterovirus serotypes. A multivalent HFMD vaccine containing 4 or 6 antigens of enterovirus serotypes is urgently needed. A formaldehyde-inactivated CV-A5 vaccine derived from Vero cells was used to inoculate newborn Kunming mice on days 3 and 10. The mice were challenged on day 14 with a mouse-adapted CV-A5 strain at a dose that was lethal for 14-day-old suckling mice. Within 14 days postchallenge, groups of mice immunized with three formulations, empty particles (EPs), full particles (FPs), and a mixture of the EP and FP vaccine candidates, all survived, while 100% of the mock-immunized mice died. Neutralizing antibodies (NtAbs) were detected in the sera of immunized mice, and the NtAb levels were correlated with the survival rate of the challenged mice. The virus loads in organs were reduced, and pathological changes and viral protein expression were weak or not observed in the immunized mice compared with those in alum-inoculated control mice. Another interesting finding was the identification of CV-A5 dense particles (DPs), facilitating morphogenesis study. These results demonstrated that the Vero cell-adapted CV-A5 strain is a promising vaccine candidate and could be used as a multivalent HFMD vaccine component in the future.IMPORTANCE The vaccine candidate strain CV-A5 was produced with a high infectivity titer and a high viral particle yield. Three particle forms, empty particles (EPs), full particles (FPs), and dense particles (DPs), were obtained and characterized after purification. The immunogenicities of EP, FP, and the EP and FP mixture were evaluated in mice. Mouse-adapted CV-A5 was generated as a challenge strain to infect 14-day-old mice. An active immunization challenge mouse model was established to evaluate the efficacy of the inactivated vaccine candidate. This animal model mimics vaccination, similar to immune responses of the vaccinated. The animal model also tests protective efficacy in response to the vaccine against the disease. This work is important for the preparation of multivalent vaccines against HFMD caused by different emerging strains.

Analysis of the current situation and related factors of beverage consumption in college sports specialty / 中国学校卫生

Objective@#To study the consumption status of sports drinks in colleges and universitiesand its influencing factors,so as to provide the scientific basis for conducting nutrition education and making interventional measures.@*Methods@#2 610 college students from arts school, PE school and Chemistry and Environmental Science Institute of a university in Shangrao city, Jiangxi Province were randomly selected by random cluster sampling method to investigate the frequency and types of drinking beverages.@*Results@#In terms of gender, apart from lactic acid drinks, there was significant statistical significance in whether men and women regularly consumed beverages (fruit and vegetable juice drinks, χ2=24.20;Tea beverage, χ2=45.58;Carbonated beverage, χ2=57.27;Energy drink χ2=86.68, P<0.01).In addition to lactic acid drinks, there was statistically significant difference in whether the college regularly consumed beverages (fruit and vegetable juice drinks, χ2=54.72;Tea beverage, χ2=25.97;Carbonated beverages, χ2=46.64;Energy drinks χ2=74.81, P<0.01).In terms of family residence, only tea beverage (χ2=25.97) and carbonated beverage (χ2=46.64) had statistical significance（P<0.01）. In terms of monthly living expenses, all beverage types had statistical significance (milk beverage, χ2=11.69;Fruit and vegetable juice beverage, χ2=18.92;Tea beverage, χ2=20.09;Carbonated beverages,χ2=29.98;Energy drink χ2=17.71, P<0.01). Logistic regression analysis showed that apart from lactic beverages, male students were more likely to consume fruit and vegetable juice, tea beverage, carbonated drinks and functional drinks than female students(OR=1.60, 2.38, 2.50, 4.95, P<0.01); The students in PE school were more likely to consume lactic beverages and functional drinks than those in Arts school, while the students in Chemistry and environmental science institute were less likely to consume fruit and vegetable juice, tea beverage, carbonated drinks and functional drinks than those in Art school (OR=1.29, 2.19, 0.43, 0.50, 0.42, 0.42, P<0.05); The students who spent >1 500 yuan monthly were more likely to consume lactic beverages, fruit and vegetable juice, tea beverage, carbonated drinks than those spent <1000 yuan monthly, and they consumed more functional than those spent<1 000 yuan monthly(OR=1.68, 1.75, 1.73, 2.15, 1.69, P<0.05).@*Conclusion@#The students of different characters have different kinds of beverages. Therefore, health education should focus on male students who spend <1 500 monthly, and targeted measures should be taken to help college students build up a reasonable concept of beverage consumption so as to promote the formation of a scientific behavior of beverage consumption.

[Preconcentration of Trace Cu(II) in Water Samples with Nano-Sized ZnO and Determination by GFAAS].

The content of copper in natural water is very low, and direct determination is difficult. Therefore, it is very meaningful for the combination of efficient separation-enrichment technology and highly sensitive detection. Based on the high adsorption capacity of Cu(II) onto nano-sized ZnO, a novel method by using nano-sized ZnO as adsorbent and graphite furnace atomic absorption spectrometry as determination means was in this work. The adsorption behaviors of Cu(II) on nano-sized ZnO was studied. Effects of acidity, adsorption equilibrium time, adsorbent dosage and coexisting ions on adsorption rates were investigated. The results showed that the adsorption efficiency was above 95% in a pH range from 3.0 to 7.0. Compared with other adsorbents for trace element enrichment such as activated carbon, nano-sized TiO2 powder, the most prominent advantage is nano-sized ZnO precipitate with the concentrated element can directly dissolved in HCl solution without any filtration and desorption process can directly analyzed by graphite furnace atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry. Compared with colloid nano materials, nano-sized ZnO is the true solution after dissolving have small matrix effect and viscosity more suitable for graphite furnace atomic absorption spectrometry or inductively coupled plasma atomic emission spectrometry detection. The proposed method possesses low detection limit (0.13 µg · L(-1)) and good precision (RSD=2.2%). The recoveries for the analysis of environmental samples were in a rang of 91.6%~92.6% and the analysis results of certified materials were compellent by using the proposed method.

Association between macroscopic-factors and identified HIV/AIDS cases among injecting drug users: an analysis using geographically weighted regression model.

Drug use (DU), particularly injecting drug use (IDU) has been the main route of transmission and spread of Human Immunodeficiency Virus (HIV)/Acquired Immune Deficiency Syndrome (AIDS) among injecting drug users (IDUs). Previous studies have proven that needles or cottons sharing during drug injection were major risk factors for HIV/AIDS transmission at the personal level. Being a social behavioral issue, HIV/AIDS related risk factors should be far beyond the personal level. Therefore, studies on HIV/AIDS related risk factors should focus not only on the individual factors, but also on the association between HIV/AIDS cases and macroscopic-factors, such as economic status, transportation, health care services, etc. The impact of the macroscopic-factors on HIV/AIDS status might be either positive or negative, which are potentially reflected in promoting, delaying or detecting HIV/AIDS epidemics.

[Association study on the microRNA-1 target gene polymorphism and the risk of premature coronary artery disease].

OBJECTIVE: To investigate the association between the genetic variant of miRNA-1 target gene COG6 rs9548934 C→T and the risk of premature coronary artery disease (pCAD). METHODS: This study included 226 pACD patients and 275 gender and age matched pCAD-free controls hospitalized in our hospital, diagnosis was made based on coronary angiography (CAG) results. The genotypes of miRNA-1 target gene COG6 rs9548934 C→T were detected by PCR-RFLP. RESULTS: Compared with the wide genotype CC, subjects with the variant genotypes CT of rs9548934 C→T was associated with a 45% lower risk of pACD (adjusted OR = 0.55, 95%CI = 0.36 - 0.82, P = 0.003), and the subjects with CT/TT genotypes were also associated with a significantly lower risk of pACD (adjusted OR = 0.64, 95%CI = 0.44 - 0.92, P = 0.015). Using the median serum TG level (1.20 mmol/L) in control group as the cutoff value, subjects with higher serum TG levels were associated with increased risk of pACD after adjustment for age, gender and BMI (adjusted OR = 2.32, 95%CI = 1.57 - 3.41, P < 0.001). In addition, subjects with higher HDL-C levels were associated with significantly lower risk of pACD (adjusted OR = 0.48, 95%CI = 0.31 - 0.75, P = 0.001). Stratified analyses showed that the risk reduction for pCAD in CT/TT genotypes carriers was more significant in the female subjects (adjusted OR = 0.54, 95%CI = 0.30 - 0.97, P = 0.040), and in subjects with lower TG, TC, HDL-C and LDL-C levels (adjusted OR = 0.62, 95%CI = 0.39 - 0.98, P = 0.040; adjusted OR = 0.55, 95%CI = 0.35 - 0.85, P = 0.008; adjusted OR = 0.43, 95%CI = 0.22 - 0.87, P = 0.018; adjusted OR = 0.49, 95%CI = 0.32 - 0.75, P = 0.001, respectively). CONCLUSION: The polymorphism of miRNA-1 target gene COG6 rs9548934C→T is associated with lower risk of pCAD, especially in female subjects and subjects with lower serum lipid levels.

[Preconcentration of ultra-trace germanium in water samples with nano-sized TiO2 colloid and determination by HGAFS with colloid sampling].

A novel method for preconcentration of ultra-trace germanium and determination by hydride generation atomic fluorescence spectrometry (HGAFS) was presented in this work. When the pH values of solution were 6.0-8.0, the adsorption efficiency of nano-sized TiO2 colloid for germanium was 97.0%-99.0% in a short time. Nano-sized TiO2 colloid was used to concentrate the ultra-trace germanium in water sample due to its high absorption capacity. After centrifugation, the supernatant fluid was removed. The sediment which contained the concentrated Ge(IV) was inverted to colloid by adding HCl of certain concentration. Ge(IV) in colloid was directly determined by HGAFS. The proposed method possesses low detection limit (3sigma) (0.060 microg x L(-1)) and good precision (the relative standard deviation (RSD) is 2.0%, n=6). The method is was also quite simple and time saving (without any filtration and desorption process). Satisfactory results were obtained when applying this method to the determination of ultra-trace germanium in water samples.

Expresstion of the TOLL-like receptor 4 in rat retina with chronic ocular hypertention / 中华实验眼科杂志

Background TLR-4 is a natural immunity receptors in immunity,and it plays an important role in the repair of central nervous system damage.But its effect in glaucoma optic nerve injury is unclear.Objective This study was to investigate the expression of TLR-4 in retina with high intraocular pressure(IOP)in genetic and Drotein level and therefore explore the mechanism of TLR-4 on retinal ganglion cells(RGCs)injury. Methods Chronic ocular hypertension models were established in the right eyes of 150 clean purebred Sprague-Dawley rats by cauterizing the 3 sallow sclera veins.IOP was measured before and after 2 h,1 day,3,7,14,28,56 days after operation by PEN Ⅱ TONO-type pen tonometer.The expression of TLR-4 protein in rat retina was detected by immunohistochemistry and Western blot,and expression of TLR-4 mRNA was assayed by real time-PCR.This experimental procedure foliowed the Statement of Association for Research in Vision and Ophthalmology. Results The IOP was elevated in various time points after operation in experimental group,showing significant differences in comparison with control group(P<0.01).The immunohistochemistry revealed that the expression of TLR-4 protein in rat retina with chronic hypertension in 2 h,1 day,3,7,14,28,56 days after operation with the high A298 values in comparison with control eyes(P<0.05-0.01).Increased levels of TLR-4 mRNA in rat retinas were detected by RTPCR in high IOP eyes compared with control eyes in all time points after operation,presenting statistically significant differences between two groups(P<0.05-0.01).Western blot detection displayed the high expression of TLR-4 in retina in high IOP eyes early after operation with statistically significant results between model group and control group (P<0.05-0. 01). Conclusion TLR-4 is up-regulated in rat retina with chronic high IOP,suggesting that TLR-4 plays an immunoregulatory effect in glaucomatous eye.

Long-term effects of biological amnion combined with glaucoma valve implantation for neovascular glaucoma / 中华实验眼科杂志

Background Neovascular glaucoma is a type of refractory glaucoma.Biological amnion combined with glaucoma valve implantation is a primary therapy and its long-term effectiveness is noticeable. Objective The goal of this Survey was to evaluate the effectiveness of biological amnion combined with glaucoma valve implantation for neovascular glaucoma and compare the clinical outcome with simple glaucoma valve implantation. Methods This was a retrospective observational case series.The clinical data of 44 eyes of 44 patients received biological amnion combined with glaucoma valve implantation for neovascular glaucoma and 43 eyes of 43 patients received simple glaucoma valve implantation for neovascular glaucoma were retrospectively analyzed and compared.The age,sex and disease-cause were matched between these two groups.Patients were followed-up for 24 months after operation.Surgery success was identified as the intraocular pressure(IOP)<21 mmHg after operation.Written informed consent was obtained from each patient prior to the operation.Results The IOP was<21 mmHg throughout the follow-up duration in both groups.No significant difierence was found in the IOP value in 1 week after operation between two groups(t=-5.34,P=0.60).However,IOP values were lower in biological amnion combined with glaucoma valve implantation group in 3,12 and 24 months after operation than those of simple glaucoma valve implantation(t=6.64,t=5.00,t=7.81,P<0.01).Operation successful rates in biological amnion combined with glaucoma valve implantation group were 97.73％.93.18％。90.24％and 82.05％in 1 week,3 months,12 months and 24 months respectively after operation.and those in simple glaucoma valve implantation were 95.35％,71.43％,65.00％and 60.53％in corresponding time points,showing considerably significant differences between two groups (χ2=7.06,χ2=7.47,χ2=4.37,P<0.05).There was no significant difference in Ihe number of eyes with complication between the two groups(P>0.05). Conclusion The biological amnion combined with glaucoma valve implantation surgery may be more effective and safe for the treatment of neovascular glaucoma than with glaucoma va]ve only.

Influence of geranylgeranylacetone on the expression of HSP70 in retina of rats with chronic IOP elevation / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To study the effects of geranylgeranylacetone(GGA) on the expression of heat shock protein70(HSP70) on retinal ganglion cells(RGC) in rats with chronic intraocular pressure(IOP) elevation.METHODS: Seventy Wistars were divided into blank control group(10 rats), chronic hypertension group(30 rats) and GGA group(30 rats). Chronic hypertension was created by cauterizing the superficial scleral veins. 800mg/(kg·d)GGA was given by oral daily after cauterization. Immunohistochemistry was used respectively to observe the changes of expression of HSP70 in the model rats and GGA interference rats at different time points during the course of chronic IOP elevation.RESULTS: The successful model was identified as the IOP over 40% of normal rats. The retinal thickness was significantly reduced in model group and model+ GGA group compared with normal rats from 21 days through 28 days after cauterization(P<0.05), and that of model rats was obviously decreased in comparison with model+ GGA rats(P<0.05). The number of ganglion cells was significantly decreased in model rats and model+ GGA rats compared with normal rats from 21 days and 28 days. The stronger expression intensity(IOD) value was seen for HSP70 in the model+ GGA rats by immunochemistry(P<0.01).CONCLUSION: Systemic administration of GGA protects retina from chronic IOP elevation by regulating the expression of HSP70.

Expression of Nogo-A on the retina in rat model with chronic ocular hypertension / 国际眼科杂志(Guoji Yanke Zazhi)

·AIM: To study the expressive variation of Nogo-A on rat retina in the process of chronic ocular hypertension. · METHODS: Thirty-six healthy adult male Wistars were randomly divided into control group (6 rats) and chronic hypertension group (30 rats). Chronic hypertension was created by cauterizing the superficial scleral veins. Immunohistochemistry technique was used to evaluate the expressive varieties of Nogo-A at different time points during the course of chronic ocular hypertension. · RESULTS: The success of the model was indicated by over 40% of increase in the IOP as compared with normal rats. Compared with control group, as time passed chronic hypertension group gradually had detectable morphology changes in the retina. At the 21st day of chronic ocular hypertension, retinas became thinner and the quantity of retinal ganglion cell (RGC) decreased (P<0.05). Assoicated with the morphological changes, the expression of Nogo-A was strongly increased (P<0.05).CONCLUSION: Myelin associated protein Nogo-A plays a part in the process of chronic ocular hypertension.

Expression of caspase-9 affected by AG on retina of rats with chronic IOP elevation / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To study caspase-9 expression on rat retina in the process of chronic elevation of IOP and the changes with the application of amino guanidine (AG), thus to investigate potential protective function of AG to rat retina with chronic elevation of IOP.METHODS: Immunohistochemistry, RT-PCR and Western blot were used to observe retinal morphology and expression of caspase-9 at different time points of rat with chronic IOP elevation, both affected or not affected by the application of AG.RESULTS: Compared with control group, as time passed retina of experimental group gradually had detectable morphological changes. On 21st day of chronic IOP elevation, retinas became thinner and the quantity of retinal ganglion cells (RGCs) decreased; caspase-9 expression increased, consistent with the morphological changes. The group using AG presented relatively smaller morphology changes and less expression of caspase-9.CONCLUSION: Apoptosis-related gene caspase-9 played a part in the process of chronic IOP elevation; AG protects retina by down-regulating expression of caspase-9.

[Preconcentration of trace Pd (II) on crosslinked chitosan and determination by graphite furnace atomic absorption spectrometry].

A novel crosslinked chitosan(CCTS) not dissolved in acidic or alkaline solutions was synthesized by the crosslinking reaction of chitosan (CTS) with crosslinking agent (3-chloro-1,2-epoxypropane). The adsorption capability of Pd(II ) by CCTS was studied at different pH value. The results showed that the adsorption efficiency was above 98% after preconcentration for 20 minutes when pH values were 1-4. The effects of preconcentration time, dosage of CCTS, adsorption capacity of CCTS, sample volume, coexistent elements, and elution of Pd(II) were investigated. The mechanism of adsorption of CCTS for Pd(II) was discussed. A novel method for the preconcentration and separation of trace Pd(II) with crosslinked chitosan (CCTS) and its determination in water by graphite furnace atomic absorption spectrometry has been developed. The detection limit (3sigma, n=8) was 0.143 microg x L(-1), the relative standard deviation(RSD) was less than 5.47%, and this preconcentration method was used to detect Pd(II) in lake water and sea water with recoveries of 92%-96%. It also can be used to recycle Pd(II).

Speciation of antimony by preconcentration of Sb(III) and Sb(V) in water samples onto nanometer-size titanium dioxide and selective determination by flow injection-hydride generation-atomic absorption spectrometry.

A novel method for prevention of the oxidation of Sb(III) during sample pretreatment, preconcentration of Sb(III) and Sb(V) with nanometer size titanium dioxide (rutile) and speciation analysis of antimony, has been developed. Antimony(III) could be selectively determined by flow injection-hydride generation-atomic absorption spectrometry, coexisting with Sb(V). Trace Sb(III) and Sb(V) were all adsorbed onto 50 m g TiO2 from 500 ml solution at pH 3.0 within 15 min, then eluted by 10 ml of 5 mol/l HCl solution. One eluent was directly used for the analysis of Sb(III); to the other eluent was added 0.5 g KI and 0.2 g thiourea to reduce Sb(V) to Sb(III), then the mixture was used for the determination of total antimony. The antimony(V) content is the mathematical difference of the two concentrations. Detection limits (based on 3sigma of the blank determinations, n=11) of 0.05 ng/ml for Sb(III) and 0.06 ng/ml for Sb(V), were obtained.

[Adsorption of p-nitrophenol by nanosized titanium dioxide surface modified with 3,5-dinitrosalicylic acid].

Nanometer size titanium dioxide modified with 3,5-dinitrosalicylic acid (3,5-DA) was prepared using chemical adsorption method. The influences of surface modification on the adsorption of p-nitrophenol (PNP) and the dispersion in solvent such as water, benzene and ethanol were studied. The 3,5-dinitrosalicylic acid is bonded to the surface hydroxyl from TiO2 nanoparticles, results in the formation of a stable, six-ring complex which color is buff. The 3, 5-DA-modified TiO2 nanoparticles have good dispersive capacity in water, benzene and ethanol. Under the optimum conditions such as pH value 3, adsorption time 10 min, the adsorption ratio of PNP by TiO2 is improved from 43% to 99.9% through surface modification. A new method could be used to remove directly 3 approximately 10mg/L PNP, and the residual concentrations is below the integrated wastewater discharge standard (GB 8978-1996).