KIT-5-Assisted Synthesis of Mesoporous SnO2 for High-Performance Humidity Sensors with a Swift Response/Recovery Speed.

Developing highly efficient semiconductor metal oxide (SMOX) sensors capable of accurate and fast responses to environmental humidity is still a challenging task. In addition to a not so pronounced sensitivity to relative humidity change, most of the SMOXs cannot meet the criteria of real-time humidity sensing due to their long response/recovery time. The way to tackle this problem is to control adsorption/desorption processes, i.e., water-vapor molecular dynamics, over the sensor's active layer through the powder and pore morphology design. With this in mind, a KIT-5-mediated synthesis was used to achieve mesoporous tin (IV) oxide replica (SnO2-R) with controlled pore size and ordering through template inversion and compared with a sol-gel synthesized powder (SnO2-SG). Unlike SnO2-SG, SnO2-R possessed a high specific surface area and quite an open pore structure, similar to the KIT-5, as observed by TEM, BET and SWAXS analyses. According to TEM, SnO2-R consisted of fine-grained globular particles and some percent of exaggerated, grown twinned crystals. The distinctive morphology of the SnO2-R-based sensor, with its specific pore structure and an increased number of oxygen-related defects associated with the powder preparation process and detected at the sensor surface by XPS analysis, contributed to excellent humidity sensing performances at room temperature, comprised of a low hysteresis error (3.7%), sensitivity of 406.8 kΩ/RH% and swift response/recovery speed (4 s/6 s).

Microstructural, Thermoelectric and Mechanical Properties of Cu Substituted NaCo2O4.

Polycrystalline samples of NaCo2-xCuxO4 (x = 0, 0.01, 0.03, 0.05) were obtained from powder precursors synthesized by a mechanochemically assisted solid-state reaction method (MASSR) and a citric acid complex method (CAC). Ceramic samples were prepared by pressing into disc-shaped pellets and subsequently sintering at 880 °C in an argon atmosphere. Effects of low concentrations of Cu doping and the above-mentioned synthesis procedures on the thermoelectric and mechanical properties were observed. The electrical resistivity (ρ), the thermal conductivity (κ) and the Seebeck coefficient (S) were measured simultaneously in the temperature gradient (ΔT) between the hot and cold side of the sample, and the figure of merit (ZT) was subsequently calculated. The ZT of the CAC samples was higher compared with the MASSR samples. The highest ZT value of 0.061 at ΔT = 473 K was obtained for the sample with 5 mol% of Cu prepared by the CAC method. The CAC samples showed better mechanical properties compared to the MASSR samples due to the higher hardness of the CAC samples which is a consequence of homogeneous microstructure and higher density obtained during sintering of these samples. The results confirmed that, besides the concentration of Cu, the synthesis procedure considerably affected the thermoelectric and mechanical properties of NaCo2O4 (NCO) ceramics.

Biocompatibility of mesoporous SBA-16/hydroxyapatite nanocomposite and dentin demineralized particles on human dental pulp stem cells.

In the present work, a biomaterial (SBA-16/HA) based on the growth of hydroxyapatite (HA) particles within an organized silica structure SBA-16 (Santa Barbara Amorphous-16) was developed to evaluate its application to act as a porous microenvironment promoting attachment and viability of human dental pulp stem cells of healthy deciduous teeth (SHED). First, SHED were isolated and their phenotypes were evaluated by flow cytometry. The samples of SBA-16/HA were characterized by X-ray diffraction (XRD), small and wide angle X-ray scattering (SWAXS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) equipped with energy dispersive spectra detector (EDS). Afterward, cells were cultured in the eluates of the above-mentioned biomaterial aged for 24 hr, 7. and 14 days. Bio-Oss® and dentin particles are involved for comparison and cells are cultured in the eluates of these two materials also. Thiazolyl Blue Tetrazolium bromide assay-MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide assay) was used for the determination of cell viability. The results obtained by all aforementioned characterization methods of SBA-16/HA, revealed a uniform spherical mesoporous structure, an intrinsic characteristic of this material. This material displayed excellent biocompatibility on SHEDs, and even proliferative potential, indicating that SBA-16/HA could potentially serve as a suitable substrate for bone regeneration. Contrary to SBA-16/HA, dentin particles showed low cytotoxicity at all time points, compared to control and Bio-Oss®groups. Our results substantiate the idea that SBA-16/HA has a beneficial effect on SHEDs, thus paving the way toward developing new material for bone replacement.

Comparative genomic analysis of genogroup 1 and genogroup 2 rotaviruses circulating in seven US cities, 2014-2016.

For over a decade, the New Vaccine Surveillance Network (NVSN) has conducted active rotavirus (RVA) strain surveillance in the USA. The evolution of RVA in the post-vaccine introduction era and the possible effects of vaccine pressure on contemporary circulating strains in the USA are still under investigation. Here, we report the whole-gene characterization (eleven ORFs) for 157 RVA strains collected at seven NVSN sites during the 2014 through 2016 seasons. The sequenced strains included 52 G1P[8], 47 G12P[8], 18 G9P[8], 24 G2P[4], 5 G3P[6], as well as 7 vaccine strains, a single mixed strain (G9G12P[8]), and 3 less common strains. The majority of the single and mixed strains possessed a Wa-like backbone with consensus genotype constellation of G1/G3/G9/G12-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1, while the G2P[4], G3P[6], and G2P[8] strains displayed a DS-1-like genetic backbone with consensus constellation of G2/G3-P[4]/P[6]/P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Two intergenogroup reassortant G1P[8] strains were detected that appear to be progenies of reassortment events between Wa-like G1P[8] and DS-1-like G2P[4] strains. Two Rotarix® vaccine (RV1) and two RV5 derived (vd) reassortant strains were detected. Phylogenetic and similarity matrices analysis revealed 2-11 sub-genotypic allelic clusters among the genes of Wa- and DS-1-like strains. Most study strains clustered into previously defined alleles. Amino acid (AA) substitutions occurring in the neutralization epitopes of the VP7 and VP4 proteins characterized in this study were mostly neutral in nature, suggesting that these RVA proteins were possibly under strong negative or purifying selection in order to maintain competent and actual functionality, but fourteen radical (AA changes that occur between groups) AA substitutions were noted that may allow RVA strains to gain a selective advantage through immune escape. The tracking of RVA strains at the sub-genotypic allele constellation level will enhance our understanding of RVA evolution under vaccine pressure, help identify possible mechanisms of immune escape, and provide valuable information for formulation of future RVA vaccines.

Rotavirus Genotype Trends and Gastrointestinal Pathogen Detection in the United States, 2014-2016: Results From the New Vaccine Surveillance Network.

BACKGROUND: Following the implementation of rotavirus vaccination in 2006, severe acute gastroenteritis (AGE) due to group A rotavirus (RVA) has substantially declined in US children. We report the RVA genotype prevalence as well as coinfection data from 7 US New Vaccine Surveillance Network sites during 3 consecutive RVA seasons, 2014-2016. METHODS: A total of 1041 stool samples that tested positive for RVA by Rotaclone enzyme immunoassay were submitted to the Centers for Disease Control and Prevention (CDC) for RVA genotyping and multipathogen testing. RESULTS: A total of 795 (76%) samples contained detectable RVA when tested at the CDC. Rotavirus disease was highest in children < 3 years of age. Four G types (G1, G2, G9, and G12) accounted for 94.6% of strains while 2 P types (P[4] and P[8]) accounted for 94.7% of the strains. Overall, G12P[8] was the most common genotype detected in all 3 seasons. Stepwise conditional logistic analysis found year and study site were significant predictors of genotype. Twenty-four percent of RVA-positive specimens contained other AGE pathogens. CONCLUSIONS: G12P[8] predominated over 3 seasons, but strain predominance varied by year and study site. Ongoing surveillance provides continuous tracking and monitoring of US genotypes during the postvaccine era.

Ultrastructural changes in the cemento-enamel junction caused by acidic beverages: An in vitro study.

The present in vitro study was aimed at evaluating the morphological changes in the cemento-enamel junction (CEJ) after exposure to acidic beverages using the scanning electron microscopy (SEM). The initial pH and titratable acidity (TA) was analyzed from follow groups: (I) Coca cola, (II) orange juice, (III) Cedevita, (IV) Red Bull, (V) Somersby cider, and (VI) white wine. The CEJ samples (n = 64), obtained from unerupted third molars, were allocated to one control (artificial saliva, n = 16) and six experimental groups (n = 8). The experimental samples were immersed in beverages (50 ml) for 15 min, three times daily, 10 days, and in artificial saliva between immersions. SEM analysis was performed in a blind manner, according to scoring scale. One-way ANOVA and Tukey's post hoc tests, as well as Kruskal-Wallis and Mann-Whitney U test used for statistical analysis. The pH values of the acidic beverages ranged from 2.65 (Coca cola) to 3.73 (orange juice), and TA ranged from 1.90 ml (Coca cola) to 5.70 ml (orange juice) of NaOH to reach pH 7.0. The SEM analysis indicated statistically significant differences between the control samples and those immersed in acidic beverages. The Groups IV, I, and II, showed the highest CEJ damage grade while those of the Group VI were the lowest. All the tested acidic beverages caused morphological changes in the CEJ with a smaller or larger exposure of dentine surface, and were not always related to the pH or TA of acidic beverages.

UV-C light irradiation enhances toxic effects of chlorpyrifos and its formulations.

UV-C irradiation is widely used in the food industry. However, the health effects from dietary exposure to the irradiated pesticide residues retained in foodstuffs are underestimated. In this study, technical chlorpyrifos (TCPF) and its oil in water (EW) and emulsifiable concentrate (EC) formulations were irradiated by UV-C, and their photodegradation products were subjected to toxicity assessment, including determination of acetylcholinesterase (AChE) activity, genotoxicity and oxidative stress using human blood cells as a model system. Toxicity studies were performed using the chlorpyrifos concentrations in the range of those proposed as the maximum residue levels in plant commodities. TCPF, EW and EC photodegradation products induced DNA damage and oxidative stress, and their genotoxicity did not decrease as a function of irradiation time. Irradiated TCPF and EC are more potent AChE inhibitors than irradiated EW. Accordingly, the application of UV-C irradiation must be considered when processing the plants previously treated with chlorpyrifos formulations.

IL-33/ST2 Pathway and Galectin-3 as a New Analytes in Pathogenesis and Cardiometabolic Risk Evaluation in Psychosis.

Schizophrenia and treatment of this disorder are often accompanied with metabolic syndrome and cardiovascular issues. Alterations in the serum level of innate immune mediators, such as interleukin-33 (IL-33) and its receptor IL-33R (ST2) and Galectin-3 (Gal-3) were observed in these conditions. Moreover, these parameters are potential prognostic and therapeutic markers. There is also accumulating evidence that these molecules play a role in neuroinflammation. Therefore, in this study we have investigated the serum level of Gal-3, IL-33 and soluble ST2 (sST2) in different stages of schizophrenia. Gal-3 levels were elevated in remission and lower in schizophrenia exacerbation in comparison with controls. Levels of IL-33 and sST2 are higher in schizophrenia exacerbation in comparison with controls and patients in remission. This initial analysis of new markers of neuroinflammation suggested their involvement in schizophrenia pathophysiology and/or cardiometabolic comorbidity.

In vitro and in vivo antimelanoma effect of ethyl ester cyclohexyl analog of ethylenediamine dipropanoic acid.

Melanoma, an aggressive skin tumor with high metastatic potential, is associated with high mortality and increasing morbidity. Multiple available chemotherapeutic and immunotherapeutic modalities failed to improve survival in advanced disease, and the search for new agents is ongoing. The aim of this study was to investigate antimelanoma effects of O,O-diethyl-(S,S)-ethylenediamine-N,N'di-2-(3-cyclohexyl) propanoate dihydrochloride (EE), a previously synthesized and characterized organic compound. Mouse melanoma B16 cell viability was assessed using acid phosphatase, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, sulforhodamine B, and lactate dehydrogenase assays. Apoptosis and autophagy were investigated using flow cytometry, fluorescence and electron microscopy, and western blotting. In vivo antitumor potential was assessed in subcutaneous mouse melanoma model after 14 days of treatment with EE. Tumor mass and volume were measured, and RT-PCR was used for investigating the expression of autophagy-related, proapoptotic, and antiapoptotic molecules in tumor tissue. Investigated organic compound exerts significant cytotoxic effect against B16 cells. EE induced apoptosis, as confirmed by phosphatidyl serine externalisation, caspase activation, and ultrastructural features typical for apoptosis seen on fluorescence and electron microscopes. The apoptotic mechanism included prompt disruption of mitochondrial membrane potential and oxidative stress. No autophagy was observed. Antimelanoma action and apoptosis induction were confirmed in vivo, as EE decreased mass and volume of tumors, and increased expression of several proapoptotic genes. EE possesses significant antimelanoma action and causes caspase-dependent apoptosis mediated by mitochondrial damage and reactive oxygen species production. Decrease in tumor growth and increase in expression of proapoptotic genes in tumor tissue suggest that EE warrants further investigation as a candidate agent in treating melanoma.

Antioxidant and antimicrobial activity of Kitaibelia vitifolia extract as alternative to the added nitrite in fermented dry sausage.

Fermented dry sausages (FDS) without nitrite added, fortified with bioactive phenol and flavonoid compounds originating from the ethanol extract of Kitaibelia vitifolia were food matrix for investigation of its antioxidant and antimicrobial potency. These activities were researched in order to improve the sausages' shelf-life, safety, and provide health benefits to consumers as well. The oxidative stability of the FDS, containing two different levels of natural preservative, was evaluated using five different contemporary methods for antioxidative activity. The activity was tested on the 20th day of the refrigerated storage. Minimum inhibitory concentrations of the sausage extract were determined against six microorganisms, using a micro dilution method. Determined optimal effective concentration of dissolved K. vitifolia extract (12.5 g/kg of meat dough) revealed strong antioxidant activity, and moderate antimicrobial activity against Escherichia coli (minimum inhibitory concentrations=15.625 µg/mL). The modified sausages had typical chemical-physical characteristics of FDS, controlled on 0, 13, 26 d of ripening and 20, 40 and 60 d of storage.

HPLC method development for determination of doxycycline in human seminal fluid.

The present paper reports the development and validation of an analytical method for doxycycline quantification in human seminal fluid by HPLC with UV detection. The separation of doxycycline was achieved at 40°C on a reversed-phase C18 column using isocratic elution. The mobile phase consisted of acetonitrile (A) and water buffered at pH 2.5 with a concentrated orthophosphoric acid (B) in the volume ratio of 20:80 (v/v), respectively. The detection was performed at 350nm. As an internal standard (IS), tetracycline was used. The proposed method involves the extraction of doxycycline from seminal fluid based on acidic precipitation of the proteins using perchloric acid. The method showed good intra- and inter-day precisions (RSD<7.0%), good accuracy (recovery for doxycycline>80%), and high correlation coefficient (r=0.998) for standards subjected to the entire procedure. The detection and quantification limits were 0.087µg/ml and 0.264µg/ml. The developed method was used to analyze doxycycline in the seminal fluids obtained from male subjects who were treated with doxycycline-hyclate. The mean doxycycline concentrations of 0.89±0.07µg/ml and 0.45±0.26µg/ml were detected in seminal fluid after 6h and 12h, respectively. This is the first study reporting extraction and HPLC determination of doxycycline in this complex sample and can be very useful in support of clinical and pharmacokinetic studies on this antibiotic.

RP-HPLC assay of doxycycline in human saliva and gingival crevicular fluid in patients with chronic periodontal disease.

A reversed-phased HPLC method with fluorescence detection was optimized and validated for determination of DOXY in human saliva and gingival crevicular fluid (GCF) with tetracycline as internal standard. Single step extraction with acetonitrile for both types of samples was performed. The separation was achieved at Zorbax Extend-C18 analytical column at 30°C. Mobile phase was consisted of an aqueous phase containing magnesium acetate, ammonium acetate, Na2EDTA, triethyl-ammonium acetate buffered to pH 7.5 with ammonium hydroxide solution and acetonitrile. The volume ratio of the buffered water mixture of salts and acetonitrile was 86:14. Fluorescence detector was set at λex=380 nm and λem=520 nm. Under the optimized experimental conditions, good linearity was found in the range of 5.0-250.0 ng/mL for GCF with LOD of 1.63 ng/mL and LOQ of 4.93 ng/mL and 20.0-500.0 ng/mL for saliva with LOD of 6.36 ng/mL and LOQ of 19.28 ng/mL. This method was successfully applied for determination of DOXY in saliva and GCF obtained from patients with chronic periodontal disease.

Preliminary evaluation of the in vitro release and in vivo absorption in rabbits of the modified-release dosage forms.

OBJECTIVE: The suitability of the rabbit as an animal model for the primary screening and selection of the pilot scale batches during the early stages of the formulation development was studied. MATERIALS AND METHODS: Three modified-release formulations of aminophylline consisted of Carbopol® 971P/HPMC K4M (F-I), and HPMC K100M (F-II) or HPMC K4M (F-III) were used. Commercial products were Aminofilin retard 350 mg tablets, Srbolek, Serbia (R-I) and Phyllocontin(®) 350, tablets Purdue Frederic, Canada (R-II). RESULTS: Calculated release rate constants and the ƒ2 values between R-I/F-I (84.1) and R-II/F-III (83.4) indicated similar in vitro release while the coefficient n showed presence of different mechanisms of release from Anomalous transport, Fickian diffusion to Case-II transport. Higher Tmax, was found in the rabbits, dosed with F-II (12.00 h), F-III (10.50 h), and R-II (15.00 h) formulation. The highest Cmax (9.22 mg/L) was obtained with F-II, similar lower values was seen for F-I and F-III, while commercial products showed the lowest values R-I (5.58 mg/L) and R-II (4.18 mg/L). Higher AUC values were detected for all three formulations (from 115.90 to 204.06 mgh/L) in relation to commercial products (105.33 and 113.25 mgh/L). DISCUSSION AND CONCLUSION: The results demonstrated a good correlation of Level A (r(2) = 0.97) for the two formulations (F-I, F-III) and commercial product (R-I) indicates that there is a reasonable assumption that the rabbit might be use as a model for the preliminary comparison of scale up formulations in the early stages of the product development.

Headspace solid phase microextraction method for determination of triazine and organophosphorus pesticides in soil.

A headspace solid phase microextraction method (HS-SPME) for simultaneous determination of five pesticides belonging to triazine and organophosphorus pesticide groups in soil samples was developed. Microextraction conditions, such as temperature, extraction time and sodium chloride (NaCl) content were investigated and optimized using 100 microm polydimethyl-siloxane (PDMS) fiber. Detection and quantification were done by gas chromatography-mass spectrometry (GC-MS). Relative standard deviation (RSD) and recovery values for multiple analysis of soil samples fortified at 30 microg kg(- 1) of each pesticide were below 13 % and higher than 70 %, respectively. Limits of detection (LOD) for all the compounds studied were less than 3.2 microg kg(- 1). The proposed method was applied in the analysis of some agricultural soil samples.

Effectiveness of clozapine, haloperidol and chlorpromazine in schizophrenia during a five-year period.

OBJECTIVE: The aim of our study was to evaluate the effects of low doses of clozapine in flexible regime in comparison with haloperidol and chlorpromazine in long term. METHOD: The naturalistic study was prospective, active-controlled with 325 adult outpatients of both genders (140 females), with mean year age of 34.8 (range 21-57), suffering from chronic schizophrenia. The first onset of illness was at the mean of 27.9 years (range 17-38), and subjects had the mean year age of 4.1+/-0.5 previous relapses. The patients were allocated to receive haloperidol (105 subjects, dose range 2-15 mg), chlorpromazine (n=105, 100-400 mg) or clozapine (n=115, 75-600 mg). The scores of psychometric instruments (GWB, PANSS, CGI) were regularly assessed during 5 year period. RESULTS: The sixty-six responders were included in per-protocol analysis: 12, 10 and 16 with positive and 7, 6 and 15 with negative schizophrenic syndrome in haloperidol, chlorpromazine and clozapine group, respectively. The statistically significant differences in all psychometric scores was found, for both schizophrenic syndromes, favoring clozapine. The distribution of eighteen different types of adverse events, which we noted, were significantly different among treatment groups ( chi2=315.7, df=34, p<0.001). Clozapine was safer and had fewer adverse effects (average of 0.9 adverse events per patient) than haloperidol (2.7) and chlorpromazine (3.2). CONCLUSIONS: Clozapine, in low doses of flexible regime, in long term (five years) showed better effectiveness in chronic schizophrenics with positive and negative symptoms than typical antipsychotics.

Effectiveness of clozapine, haloperidol and chlorpromazine in schizophrenia during a five-year period / Eficácia da clozapina, haloperidol e clorpromazina na esquizofrenia em um período de cinco anos

OBJECTIVE: The aim of our study was to evaluate the effects of low doses of clozapine in flexible regime in comparison with haloperidol and chlorpromazine in long term. METHOD: The naturalistic study was prospective, active-controlled with 325 adult outpatients of both genders (140 females), with mean year age of 34.8 (range 21-57), suffering from chronic schizophrenia. The first onset of illness was at the mean of 27.9 years (range 17-38), and subjects had the mean year age of 4.1±0.5 previous relapses. The patients were allocated to receive haloperidol (105 subjects, dose range 2-15 mg), chlorpromazine (n=105, 100-400 mg) or clozapine (n=115, 75-600 mg). The scores of psychometric instruments (GWB, PANSS, CGI) were regularly assessed during 5 year period. RESULTS: The sixty-six responders were included in per-protocol analysis: 12, 10 and 16 with positive and 7, 6 and 15 with negative schizophrenic syndrome in haloperidol, chlorpromazine and clozapine group, respectively. The statistically significant differences in all psychometric scores was found, for both schizophrenic syndromes, favoring clozapine. The distribution of eighteen different types of adverse events, which we noted, were significantly different among treatment groups ( ÷2=315.7, df=34, p<0.001). Clozapine was safer and had fewer adverse effects (average of 0.9 adverse events per patient) than haloperidol (2.7) and chlorpromazine (3.2). CONCLUSIONS: Clozapine, in low doses of flexible regime, in long term (five years) showed better effectiveness in chronic schizophrenics with positive and negative symptoms than typical antipsychotics.

OBJETIVO: O propósito deste estudo foi avaliar os efeitos de baixas doses de clozapina em regime flexível comparando com o uso de haloperidol e clorpromazina por período de 5 anos. MÉTODO: Um estudo prospectivo naturalístico, ativo-controlado foi realizado com 325 pacientes com idade média de 34,8 (variância 21-57). Todos com diagnóstico de esquizofrenia. No primeiro surto da doença os pacientes apresentavam idade média de 27,9 anos (variância 17-38) e os surtos subsequentes apareceram em média 4,1±0,5 anos após. Os pacientes foram orientados a receberem haloperidol (105 pacientes com dose entre 2 e 15 mg), clorpromazina (105 pacientes com dose entre 100 e 400 mg) e clozapina (115 pacientes com dose entre 75 e 600 mg). Os instrumentos psicométricos utilizados (GWB, PANSS e CGI) foram regularmente empregados durante os 5 anos do estudo. RESULTADOS: Os 66 pacientes respondedores ao tratamento foram incluídos no protocolo de análise: 12, 10 e 16 apresentavam síndrome esquizofrênica positiva e 7, 6 e 15 síndrome negativa esquizofrênica com haloperidol, clorpromazina e clozapina, respectivamente. Diferenças estatísticas significantes foram observadas em todas as avaliações psicométricas em ambas síndromes esquizofrênicas favorecendo a clozapina. A distribuição de 18 tipos de efeitos colaterais observados foi diferente de modo significativo entre os 3 grupos estudados. A clozapina foi a droga que apresentou menos efeitos colaterais. CONCLUSÃO: A clozapina administrada por longo termo em pequenas doses em regime flexível apresenta melhor eficácia nas síndromes esquizofrênicas quando comparada a outras drogas antipsicóticas.

Evaluation and validation of two different chromatographic methods (HPLC and LC-MS/MS) for the determination and confirmation of ochratoxin A in pig tissues.

This study was undertaken to compare two different analytical methods for the determination and confirmation of ochratoxin A (OTA) in blood serum, kidney and liver of pigs. Sample clean-up was based on liquid-liquid phase extraction. The detection of OTA was accomplished with high-performance liquid chromatography (HPLC) combined either with fluorescence detection (FL) or electro spray ionization (ESI+) tandem mass spectrometry (MS-MS). Comparative method evaluation was based on the investigation of 90 samples of blood serum, kidney and liver per animal originating from different regions of Serbia. The analytical results are discussed in view of the respective method validation data and the corresponding experimental protocols. In general, analytical data obtained with (LC-MS-MS) liquid chromatography electro spray tandem mass spectro metry detection offered comparable good results at the sub-ppb concentration level. The results indicate that the liquid chromatography electro spray tandem mass spectrometric (LC-MS/MS) method was more specific and sensitive for the analysis and confirmation of ochratoxin A in pig tissues then high pressure liquid chromatography (HPLC) method after methylation of OTA.

Malonic acid concentration as a control parameter in the kinetic analysis of the Belousov-Zhabotinsky reaction under batch conditions.

The influence of the initial malonic acid concentration [MA]0 (8.00 x 10(-3) < or = [MA]0 < or = 4.30 x 10(-2) mol dm(-3)) in the presence of bromate (6.20 x 10(-2) mol dm(-3)), bromide (1.50 x 10(-5) mol dm(-3)), sulfuric acid (1.00 mol dm(-3)) and cerium sulfate (2.50 x 10(-3) mol dm(-3)) on the dynamics and the kinetics of the Belousov-Zhabotinsky (BZ) reactions was examined under batch conditions at 30.0 degrees C. The kinetics of the BZ reaction was analyzed by the earlier proposed method convenient for the examinations of the oscillatory reactions. In the defined region of parameters where oscillograms with only large-amplitude relaxation oscillations appeared, the pseudo-first order of the overall malonic acid decomposition with a corresponding rate constant of 2.14 x 10(-2) min(-1) was established. The numerical results on the dynamics and kinetics of the BZ reaction, carried out by the known skeleton model including the Br2O species, were in good agreement with the experimental ones. The already found saddle node infinite period (SNIPER) bifurcation point in transition from a stable quasi-steady state to periodic orbits and vice versa is confirmed by both experimental and numerical investigations of the system under consideration. Namely, the large-amplitude relaxation oscillations with increasing periods between oscillations in approaching the bifurcation points at the beginning and the end of the oscillatory domain, together with excitability of the stable quasi-steady states in their vicinity are obtained.

Carbofuran in water: Subchronic toxicity to rats.

Carbofuran toxicity on rats was studied during subchronic exposure. Female and male rats were administered carbofuran in drinking water in concentrations of 25, 100 and 400ppm for a period of 90 days. Clinical symptoms, water consumption, body weight gain, organ weight, pathological and histopathological changes in the liver and kidneys were observed and biochemical and haematological examinations were carried out. The results obtained show that carbofuran administered to rats caused a significant decrease in water consumption as well as in brain, serum and erythrocyte cholinesterase activities. Statistically significant increases in relation to the control were found in the serum enzyme activities. The haematological data showed that carbofuran had no significant effect on Hb concentration and total RBC, but total WBC showed a significant statistical decrease. The histopathological changes in liver and kidneys were observed. However, cell regeneration in the liver and kidneys was found in all test groups.

Kinetic determination of morphine by means of Bray-Liebhafsky oscillatory reaction system using analyte pulse perturbation technique.

A novel kinetic method for micro-quantitative determinations of morphine (MH) is proposed and validated. The method is based on the potentiometric monitoring of the concentration perturbations of the oscillatory reaction system being in a stable non-equilibrium stationary state close to the bifurcation point between stable and oscillatory state. The response of the Bray-Liebhafsky (BL) oscillatory reaction as a matrix system, to the perturbations by different concentrations of morphine, is followed by a Pt-electrode. The proposed method relies on the linear relationship between maximal potential shift, DeltaE(m), and the logarithm of the added morphine amounts in the range of 0.004-0.18 micromol. Under optimum conditions, the sensitivity of the proposed method (as the limit of detection) is 0.001 micromol and the method is featured by good precision (R.S.D.=1.6%) as well as the excellent sample throughput (45 samples h(-1)). In addition to standard solution analysis, this approach was successfully applied for quantitative determination of morphine in a typical pharmaceutical dosage form. Some aspects of the possible mechanism of morphine action on the BL oscillating chemical system are discussed in detail.