Kinetic and toxicological effects of synthesized palladium(II) complex on snake venom (Bungarus sindanus) acetylcholinesterase

The venom of the krait (Bungarus sindanus), an Elapidae snake, is highly toxic to humans and contains a great amount of acetylcholinesterase (AChE). The enzyme AChE provokes the hydrolysis of substrate acetylcholine (ACh) in the nervous system and terminates nerve impulse. Different inhibitors inactivate AChE and lead to ACh accumulation and disrupted neurotransmission. Methods: The present study was designed to evaluate the effect of palladium(II) complex as antivenom against krait venom AChE using kinetics methods. Results: Statistical analysis showed that krait venom AChE inhibition decreases with the increase of Pd(II) complex (0.025-0.05 µM) and exerted 61% inhibition against the AChE at a fixed concentration (0.5 mM) of ACh. Kinetic analysis using the Lineweaver Burk plot showed that Pd(II) caused a competitive inhibition. The compound Pd(II) complex binds at the active site of the enzyme. It was observed that K m (Michaelis-Menten constant of AChE-ACh into AChE and product) increased from 0.108 to 0.310 mM (45.74 to 318.35%) and V max remained constant with an increase of Pd(II) complex concentrations. In AChE K Iapp was found to increase from 0.0912 to 0.025 µM (29.82-72.58%) and did not affect the V maxapp with an increase of ACh from (0.05-1 mM). K i (inhibitory constant) was estimated to be 0.029µM for snake venom; while the K m was estimated to be 0.4 mM. The calculated IC50 for Pd(II) complex was found to be 0.043 µM at constant ACh concentration (0.5 mM). Conclusions: The results show that the Pd(II) complex can be deliberated as an inhibitor of AChE.(AU)

Preparación, caracterización y aplicación de sensores de Pd-SnO como nariz electrónica en la clasificación de vinos peruanos y su comparación con técnicas cromatográficas / Preparation, characterization, and application of Pd-SnO sensors as an electronic nose in Peruvian wine classification and its comparison with chromatographic techniques / Preparação, caracterização e aplicação de sensores de Pd-SnO como nariz eletrônico na classificação dos vinhos peruanos e sua comparação com técnicas cromatográficas

Resumen Se prepararon sensores basados en SnO dopados con paladio (0, 1, 3, 5 y 7%) mediante el método de impregnación húmeda. Para caracterizarlos, se usaron las técnicas de espectroscopia infrarroja con transformada de Fourier (FTIR), adsorción y desorción de N2 (BET), difracción de rayos X (XRD), microscopía electrónica de barrido (SEM) y espectroscopia de energía dispersiva de rayos X (EDX). Los sensores se evaluaron con etanol para que conformaran, junto a dos sensores comerciales, una nariz electrónica (E-nose) que lograse detectar componentes volátiles del aroma en vinos peruanos. Los resultados fueron interpretados a través del análisis de componentes principales (PCA) con la finalidad de buscar una técnica que complementase la información recolectada por la cromatografía de gases (GC) y la cromatografía líquida (HPLC), y justamente comparando los PCAs obtenidos del GC y el HPLC con los resultantes de la E-nose se encontró que estos últimos clasificaban mejor las muestras. Fue posible diferenciar tanto vinos de la misma uva como de distinta cepa. Además, se logró detectar vinos adulterados, lo cual contribuye a la industria vitivinícola en el control de su producción con la finalidad de mejorar la calidad de esta bebida para el consumidor.

Abstract SnO-based sensors doped with palladium (0, 1, 3, 5 and 7%) were prepared by the wet impregnation method. To characterize them, the techniques ofinfrared spectroscopy with Fourier transform (FTIR), adsorption and desorption of N2 (BET), XRD, scanning electron microscopy (SEM), and X-ray dispersive energy (EDX) spectroscopy were used. The sensors were evaluated with ethanol to form, together with two commercial sensors, an electronic nose (E-nose) that could detect volatile aroma components in Peruvian wines. The results were interpreted through principal component analysis (PCA) to find a technique that complemented the information collected by gas chromatography (GC) and liquid chromatography (HPLC), and by comparing the PCAs obtained from GC, and HPLC with those resulting from E-nose. It was found that the latter classified the samples better. It was possible to differentiate both wines from the same grape and from a different strain, and to detect adulterated wines, which contributes to the wine industry in controlling its production to improve the quality of this drink for the consumer.

Resumo Os sensores baseados em SnO dopados com paládio (0, 1, 3, 5 e 7%) foram preparados pelo método de impregnação por via húmida. Para caracterizá-los, as técnicas de espectroscopia infravermelha com transformação de Fourier (FTIR), adsorção e dessorção de N2 (BET), XRD, microscopia eletrônica de varredura SEM) e espectroscopia de energia dispersiva de raios-X (EDX). Os sensores foram avaliados com etanol para formar, junto com dois sensores comerciais, um nariz eletrônico (E-nose) que poderia detectar componentes de aroma volátil em vinhos peruanos. Os resultados foram interpretados através da análise de componentes principais (PCA) para encontrar uma técnica que complementasse a informação coletada por cromatografia gasosa (GC) e cromatografia líquida (HPLC) e comparando os PCA obtidos de GC e HPLC com os resultantes do E-nose, descobriu-se que este classificou melhor as amostras. Foi possível diferenciar os vinhos da mesma uva e de uma variedade diferente. Além disso, foi possível detectar vinhos adulterados, o que contribui para a indústria do vinho no controle de sua produção, a fim de melhorar a qualidade desta bebida para o consumidor.

Selective Determination of Hydrazine Hydrate on Palladium Hydrogels-modified Electrochemical Sensor / 分析化学

Palladium hydrogel capped by β-cyclodextrins (Pdβ-CD) was prepared by a facile method with β-cyclodextrins and palladium(II) chloride,which were then modified onto the surface of gold electrode. The morphology and structure of the as-prepared palladium hydrogel were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), while the electrochemistry behaviors of gold electrode modified by Pdβ-CDwere investigated by cyclic voltammetry (CV) and differential pulse voltammetry(DPV). The results indicated the sensor had high electrochemistry response to hydrazine hydrate in the presence of K+,Na+,Mg2+,NH+4,Ni+2,Mn2+,Cl-,NO-3,SO2-4,PO3-4,HCOO-, C6H5O-3. Under the optimized conditions, the oxidized peak current showed linear relationship with the concentration of hydrazine hydrate in the concentration range of 25-950 μmol/L and the limit of detection (LOD) of 1.6 μmol/L(S/N=3).Owing to the facile preparation,high sensitivity and selectivity,the sensor has potential applications in determination of hydrazine hydrate in real water samples

Nanopartículas de paladio soportadas en hidroxisales laminares: uso potencial en reacciones de Sonogashira / Palladium nanoparticles supported in laminar hydroxide salts: potential use in Sonogashira reactions / Nanopartículas de paládio suportadas em hidroxisais laminares: uso potencial em reacções de Sonogashira

Resumen En este artículo se reporta la síntesis de nanopartículas de paladio soportadas en hidroxisales de acetato de zinc y modificadas con un surfactante (LHS-Zn-Ac/Pd0 y LHS-Zn-Suf/Pd0 respectivamente), mediante inserción de [PdCl4]2- y su posterior reducción con etanol en reflujo. Con la inserción de surfactante, la distancia interlaminar de la hidroxisal de partida (LHS-Zn-Ac) se incrementó de 13,8 Å a 29,8 Å, mientras que los materiales finales, que contenían paladio metálico registraron distancias interlaminares de 22,4 Å y 29,4 Å para LHS-Zn-Ac/Pd0 y LHS-Zn-Suf/Pd0 respectivamente. Las hidroxisales de acetato de zinc y de surfactante con nanopartículas metálicas de paladio incorporadas fueron ensayadas como potenciales catalizadores en la reacción de Sonogashira partiendo de fenilacetileno y yoduros de arilo, particularmente yodobenceno o 2-yodofenol, dando lugar a difenilacetileno (32% de rendimiento de producto aislado y purificado) o 2-fenilbenzofurano (18%). Todos los materiales inorgánicos fueron caracterizados mediante las siguientes técnicas: difracción de rayos X (XRD), microscopia electrónica de barrido (SEM y SEM-EDS), microscopia electrónica de transmisión (TEM) y espectroscopía de Infrarrojo con Transformada de Fourier (FT-IR). Por su parte los compuestos orgánicos se caracterizaron por resonancia magnética nuclear (1H-NMR y 13C-NMR) y cromatografía de gases acoplada a espectrometría de masas (GC-MS).

Abstract This article reports the synthesis of palladium nanoparticles supported on zinc acetate hydroxysalts and modified with a surfactant (LHS-Zn-Ac/Pd0 and LHS-Zn-Suf/Pd0 respectively), by insertion of [PdCl4]2- and its subsequent reduction with ethanol at reflux. With the surfactant insertion, the interlaminar distance of the starting hydroxysalt (LHS-Zn-Ac) increased from 13.8 Å to 29.8 Å, while the final materials containing palladium metal registered interlaminar distances of 22.4 Å and 29.4 Å for LHS-Zn-Ac/Pd0 and LHS-Zn-Suf/Pd0 respectively. Zinc acetate hydroxysalt and surfactant with incorporated palladium metal nanoparticles were tested as potential catalysts in the Sonogashira reaction starting from phenylacetylene and aryl iodides, particularly iodobenzene or 2-iodophenol, giving diphenylacetylene (32% yield of isolated and purified product) or 2-phenylbenzofuran (18%). All inorganic materials were characterized by the following techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM and SEM-EDS), transmission electron microscopy (TEM) and Fourier transformed infrared spectroscopy (FT-IR). The organic compounds were characterized by nuclear magnetic resonance (1H-NTMR and 13C-NMR) and gas chromatography coupled to mass spectrometry (GC-MS).

Resumo Neste artigo se reporta a síntese de nanopartículas de paládio suportadas em hidroxisais de acetato de zinco e modificadas com um surfactante (LHS-Zn-Ac/Pd0 e LHS-Zn-Suf/Pd0 respectivamente), mediante inserção de [PdCl4]2- para depois fazer uma redução com etanol em refluxo. Com a inserção do surfactante, a distância interlaminar da hidroxisal inicial (LHS-Zn-Ac) aumentou de 13,8 Å até 29,8 Å, enquanto que os materiais finais que continham paládio metálico registraram distâncias interlaminares de 22,4 Å até 29,4 Å para LHS-Zn-Ac/Pd0 e LHS-Zn-Suf/Pd0 respectivamente. As hidroxisais do acetato de zinco e do surfactante com nanopartículas metálicas de paládio incorporadas foram testados como potenciais catalisadores na reação de Sonogashira a partir de fenilacetileno e iodetos de arilo, particularmente iodobenzeno ou 2-iodofenol, levando respectivamente difenilacetileno (32% de rendimento de produto isolado e purificado) ou 2-fenilbenzofurano (18%). Todos os materiais inorgânicos foram caracterizados pelas seguintes técnicas: difração de raios X (XRD), microscopia eletrônica de varredura (SEM e SEM-EDS), Microscopia Eletrônica de Transmissão (TEM) e espectroscopia de infravermelho com transformada de Fourier (FT-IR). Por outro lado, os compostos orgânicos foram caracterizados por ressonância magnética nuclear (1H-NMR y 13C-NMR) e cromatografia gasosa acoplada à massa (GC-MS).

Influence of different heat treatments on the corrosion behavior of a new type of high palladium dental alloy / 口腔疾病防治

Objective@#To evaluate the influence of different heat treatments on the corrosion behavior of a new Pd-Ag-In-Ga alloy. @*Methods @#The corrosion of a new Pd-Ag-In-Ga alloy was tested according to ISO 10271：2001/cor.1:2005(E). Taken as comparison, a commercial high-palladium alloy (Spartan® Plus) was also employed in the study. For electrochemical corrosion test, the open-circuit potential (Eocp) and potentiodynamic polarization curve were recorded and then the electrochemical parameters, namely corrosion potential (Ecorr) and corrosion current density (Icorr) calculated. The surfaces of the specimens that before and after corrosion test were observed by scanning electron microscopy (SEM). @* Results @#Both of the high-palladium alloys had lower corrosion tendency and higher corrosion resistance by heat treatment in the ISO 10271 electrochemical corrosion test. For both alloys, heat treatment at 500 ℃ was found to be effective in improving the corrosion resistance as the best datas of electrochemical parameters (Eocp, Ecorr, Icorr) were detected among the four temperature groups. However, no evidence showed that there was significant difference in corrosion resistance between the two alloys. Comparison of surface morphology of the specimens before and after electrochemical experiments by SEM demonstrated that all groups of the two alloys were visible of pitting corrosion and crevice corrosion phenomenon that gradually became less with increasing heat treatment temperature. Horizontal comparing among the groups of the two alloys, no apparent differences in the distribution of pitting and crevice corrosion was found. @*Conclusin @#The variation in compositions of high-palladium alloys did not cause significant difference in corrosion behavior due to the identical palladium matrix. The similarity in corrosion behavior among the two high-palladium alloys might be attributed to the predominant palladium content.

Preparation and Recognition Properties of Trimethoprim Sensor Based on Palladium Nanoparticles-modified Molecularly Imprinted Polymer / 分析化学

To improve the sensitivity of molecularly imprinted electrochemical sensors, a Pd nanoparticles-modified molecularly imprinted polymer (MIP) film for the determination of trimethoprim (TMP) was developed by thermal polymerization with N, N′-methylene diacrylamide as a functional monomer, Pd nanoparticle as a dopant and ethylene glycol maleic rosinate acrylate as a crosslinking agent.The morphologies and chemical structures of the Pd nano-materials and the imprinted films were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy, respectively.The electrochemical properties of the nano-doped and undoped MIP sensors were investigated by cyclic voltammetry and electrochemical impedance spectroscopy.Results showed that the morphologies and chemical structures and the electrochemical properties of the doped molecularly imprinted sensor were remarkably different from those of the undoped imprinted sensor.Linear responses of the imprinted sensor to TMP were observed for concentrations ranging from 5.0×10-7 mol/L to 4.0×10-3 mol/L (R=0.9995), with a detection limit of 3.2×10-8 mol/L (S/N=3).The Pd nanoparticle doped MIP sensors exhibited high selectivity.The chronoamperometry showed that no interference from potential interfering species such as sulfamethoxazole, sulfadiazine, glucose, and urea were noted.The proposed electrochemical sensor was used to determine TMP in actual samples, with average recoveries of 96.8%-102.0%.

Efecto citotóxico de los compuestos de inclusión de paladio (II) en la beta-ciclodextrina / Cytotoxic effect of palladium (II) inclusion compounds in beta-cyclodextrin

Resumen Introducción. Las tiosemicarbazonas y sus complejos de paladio (II) poseen actividad antineoplásica con pocos efectos secundarios, por lo cual se las considera como una nueva alternativa terapéutica. Sin embargo, existen diferencias en los rangos de la concentración inhibitoria media (CI50) asociada a la divergencia estructural y la solubilidad de los complejos, así como a la sensibilidad de los blancos celulares. La inclusión de fármacos en la beta-ciclodextrina con fines terapéuticos ha mejorado su solubilidad y estabilidad, pero los efectos de su combinación con los complejos de paladio (II) y las tiosemicarbazonas no se han comprobado aún. Objetivo. Estudiar el efecto citotóxico de los complejos de paladio en la beta-ciclodextrina. Materiales y métodos. La actividad citotóxica de los complejos de paladio en la beta-ciclodextrina se evaluó en la línea celular de cáncer de mama (MCF-7), empleando el método de la sulforodamina B. Resultados. Los ligandos MePhPzTSC y Ph2PzTSC, sus complejos de paladio (II) libres e incluidos en la beta-ciclodextrina y el cisplatino mostraron actividad citotóxica en la línea celular MCF-7; sin embargo, la citotoxicidad fue mayor con la inclusión en la beta-ciclodextrina ([Pd(MePhPzTSC)2]•ß-CD y [Pd(Ph2PzTSC)2]•ß-CD). La concentración inhibitoria media (CI50) para estos complejos se obtuvo en concentraciones de 0,14 y 0,49 μM, y con dosis hasta cinco veces inferiores comparadas con las concentraciones de los ligandos libres (1,4 y 2,9 μM), de los complejos de paladio (II) libres (0,57 y 1,24 μM) y del cisplatino (6,87 μM). Conclusiones. El uso de la beta-ciclodextrina mejoró significativamente la actividad citotóxica de las tiosemicarbazonas y sus complejos de paladio (II), lo cual probablemente está asociado al incremento de la solubilidad y biodisponibilidad del compuesto, estrategia que se puede sugerir para el diseño de futuros fármacos antineoplásicos.

Abstract Introduction: Thiosemicarbazones and palladium (II) complexes have antineoplastic activities with mild side effects, for which they are considered new alternative antineoplastic drugs. However, the IC50 ranges of these complexes vary due to differences in their structure and solubility and their sensitivities for various cellular targets. Beta-cyclodextrin is an additive used to improve the solubility and stability of various drugs for therapeutic use, but the combination of beta-cyclodextrin with palladium (II) complexes and thiosemicarbazones has not been tested yet. Objective: To study the cytotoxic effect of palladium (II) inclusion complexes in beta-cyclodextrin. Materials and methods: We tested the cytotoxic activity of palladium complexes combined with betacyclodextrin in the breast cancer cell line MCF-7 using a sulforhodamine B assay. Results: We tested the antiproliferative activity of palladium (II) complexes with and without the ligands MePhPzTSC and Ph2PzTSC and with and without beta-cyclodextrin in MCF-7 cells and compared them to that of cisplatin. All combinations showed antiproliferative activity; however, the activity was greater for the combinations that included beta-cyclodextrin: ([Pd (MePhPzTSC) 2] • ß-CD and [Pd (Ph2PzTSC) 2] • ß-CD), at concentrations of 0.14 and 0.49 μM, respectively. The IC50 for this complex was 5-fold lower than that of the ligand-free combinations (1.4 and 2.9 μM, respectively). The IC50 for free palladium (II) complex was 0.571.24 μM and that for cisplatin was 6.87 μM. Conclusions: Beta-cyclodextrin significantly enhanced the cytotoxic activities of palladium (II) complexes and thiosemicarbazones probably by improving their solubility and bioavailability. The addition of betacyclodextrin is a possible strategy for designing new anticancer drugs.

Study on the application of colloidal palladium in the determination of lead,cadmium and manganese in blood by atomic absorption spectrometry / 中国职业医学

OBJECTIVE: To study the application of colloidal palladium as a matrix modifier in the determination of lead,cadmium and manganese in whole blood by graphite furnace atomic absorption spectrometry( GFAAS). METHODS: The whole blood samples were diluted 10 times by blood diluents,and then the colloidal palladium was applied as a chemical modifier to improve the ashing and atomizing temperature. The levels of lead,cadmium and manganese in whole blood were determined by GFAAS. The effects of palladium chloride as a conventional matrix modifier were compared. RESULTS: The optimal quantity of colloidal palladium as a matrix modifier was 5. 00 μL. It can raise the ashing temperatures of lead,cadmium and manganese to 900,800 and 1 400 ℃,respectively; and raised their atomizing temperatures to 1 900,1 800,and 2 000 ℃,respectively. Compared to the palladium chloride,the colloidal palladium can provide wider ashing temperature and atomizing temperature of the above 3 elements. The good linearity ranges of lead,cadmium and manganese were 0. 12-100. 00,0. 05-4. 00 and 0. 02-10. 00 μg / L,respectively. All the correlation coefficients were greater than0. 999. The minimum detectable concentrations were 1. 20,0. 50 and 0. 20 μg / L,respectively( samples were diluted 10times). The recovery rates were 99. 2%-104. 0%,102. 8%-105. 5% and 98. 3%-103. 2%,respectively. The relative standard deviations( RSDs) of within-run precision were 1. 2%-2. 6%,2. 7%-5. 3% and 2. 3%-2. 8%,respectively,and the RSDs of between-run precision were 1. 6%-3. 9%,4. 0%-6. 1% and 3. 2%-4. 4%,respectively. CONCLUSION: Colloidal palladium was an excellent matrix modifier in determining the levels of lead,cadmium and manganese in whole blood. It has low background interference and can improve the accuracy and precision of detection.

Determination of Residual Palladium in Bendamustine Hydrochloride by GFAAS / 中国药师

Objective:To develop a method for the determination of palladium in bendamustine hydrochloride by GFAAS. Meth-ods:The sample was destroyed by heat, and the content of palladium was determined by GFAAS with the detection wavelength of 247. 6 nm. Results:The absorbance and the content of palladium showed a good linear relationship within the range of 20-60 ng· ml-1(r=0. 998 4). The average recovery of palladium was 102. 9%(RSD=1. 7%, n=9). Conclusion: The method is sensitive and simple, which can be used for the determination of palladium in bendamustine hydrochloride.

A Hydrogen Peroxide Sensor Based on Palladium Nanoparticles Loading to Poly(amidoamine) Dendrimers Functionalized Carbon Nanotubes / 分析化学

The fourth generation poly( amidoamine) dendrimers ( G4. 0 PAMAM) functionalized multiwalled carbon nanotube ( G4 . 0-MWCNTs ) was prepared by amidation between carboxylated multiwalled carbon nanotube (MWCNTs) and G4. 0 PAMAM. Then a novel hydrogen peroxide (H2O2) sensor was fabricated by electrodepositing Pd nanoparticles (NPs) on a glassy carbon electrode (GCE) modified with G4. 0-MWCNTs composites. The modified electrode was characterized by field emission scanning electron microscopy ( FESEM) , cyclic voltammetry ( CV) and electrochemical impedance spectroscopy ( EIS) . A large amounts of highly dispersion PdNPs could be well loaded on the surface of the G4. 0-MWCNTs, and the modified electrode exhibited excellent electrocatalytic activity towards the reduction of H2 O2 . Under the optimized conditions, the reduction peak currents of H2 O2 were linear to their concentrations in the range from 1. 0 × 10-9 mol/L to 1. 0×10-3 mol/L and the limit of detection of 2. 3×10-8 mol/L was obtained. The recovery of standard addition for human serum samples was 96 . 7%-103 . 1%.

Seroprevalence of Syphilis Infection in Individuals at Cape Coast Metropolis, Ghana.

Background: Syphilis is a sexually transmitted infection caused by Treponema pallidum. The disease becomes very common among individuals with multiple sexual partners without protection. Aim: This research aimed at assessing the prevalence of syphilis infection in Cape Coast Metropolis and the factors associated with the transmission of the disease Methodology: 200 participants from Cape Coast were sampled and assessed for syphilis infection using Venereal Disease Research Laboratory syphilis test strips (a nontreponemal test) and positive samples were confirmed with Treponema palladium haemagglutination (TPHA) test. Questionnaires, reflecting the participant’s sociodemographic data were also administered. The results were analysed, to assess the relationship between various risk factors and syphilis infection. Results: The prevalence of syphilis infection in Cape Coast was found to be 8.5%, mainly associated with participants having multiple sexual partners and having unprotected and indiscriminate sex. Other factors found to be indirectly affecting the rate of infection were illiteracy, lack of knowledge and information concerning the disease. Conclusion: The seroprevalence of syphilis infection in the Cape Coast Metropolis is an indication that the disease is endemic.

Analysis of Reaction Products of (Ethylenediamine) palladium(Ⅱ) Chloride and 5′-Deoxyguanylic Acid in Aqueous Solution by Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry and Electrospray Ionization Mass Spectrometry / 分析化学

A method based on HPLC-ICP-MS was established to separate the reaction products of ( ethylenediamine) palladium(Ⅱ) chloride([Pd ( en ) Cl2])and 5’-deoxyguanylic acid ( 5’-dGMP). Two reaction products were detected at pH 8. 0 with 25 mmol/L phosphate buffer solution as chromatography eluent. One was the main product with HPLC retention time of 2. 8 min, the other product’s retention time was 3.2 min. According to ESI-MS(MS/MS) study, m/z=510, 511, 512, 514, 516[M+1]+ parent ions ( abundances same to palladium isotopes) were detected. Further analysis showed that the main product was[Pd( en) ( N1-5’-dGMP) ]. However the other product was hardly to be detected by ESI-MS. By using HPLC-DAD and HPLC-ICP-MS, we found that the two reaction products had the same UV absorption spectra and palladium percentage content. Combined with other groups’research, the other reaction product was deduced as dimmer, trimer or tetramer form of[Pd( en) ( N1-5’-dGMP) ]. Further study revealed that[Pd( en) ( N1-5’-dGMP) ] was easily formed in acid solution while its polymer form was generated in alkaline solution. At pH 6. 0, [Pd(en)(N1-5’-dGMP)] was formed within 12 hours with good stability. Research also revealed that the total amount of two reaction products declined as reaction pH climbed.

Influence of shape and finishing on the corrosion of palladium-based dental alloys

PURPOSE: The purpose of this study was to evaluate the effects of the surface treatment and shape of the dental alloy on the composition of the prosthetic work and its metallic ion release in a corrosive medium after casting. MATERIALS AND METHODS: Orion Argos (Pd-Ag) and Orion Vesta (Pd-Cu) were used to cast two crowns and two disks. One of each was polished while the other was not. Two as-received alloys were also studied making a total of 5 specimens per alloy type. The specimens were submersed for 7 days in a lactic acid/sodium chloride solution (ISO standard 10271) and evaluated for surface structure characterization using SEM/EDAX. The solutions were quantitatively analysed for the presence of metal ions using ICP-MS and the results were statistically analysed with one-way ANOVA and a Tukey post-hoc test. RESULTS: Palladium is released from all specimens studied (range 0.06-7.08 microg.cm(-2).week(-1)), with the Pd-Cu alloy releasing the highest amounts. For both types of alloys, ion release of both disk and crown pairs were statistically different from the as-received alloy except for the Pd-Ag polished crown (P>.05). For both alloy type, disk-shaped pairs and unpolished specimens released the highest amounts of Pd ions (range 0.34-7.08 microg.cm(-2).week(-1)). Interestingly, in solutions submerged with cast alloys trace amounts of unexpected elements were measured. CONCLUSION: Shape and surface treatment influence ion release from dental alloys; polishing is a determinant factor. The release rate of cast and polished Pd alloys is between 0.06-0.69 microg.cm(-2).week(-1), which is close to or exceeding the EU Nickel Directive 94/27/EC compensated for the molecular mass of Pd (0.4 microg.cm(-2).week(-1)). The composition of the alloy does not represent the element release, therefore we recommend manufacturers to report element release after ISO standard corrosion tests beside the original composition.

A comparative study on the bond strength of porcelain to the millingable Pd-Ag alloy

PURPOSE: The porcelain fused to gold has been widely used as a restoration both with the natural esthetics of the porcelain and durability and marginal fit of metal casting. However, recently, due to the continuous rise in the price of gold, an interest towards materials to replace gold alloy is getting higher. This study compared the bond strength of porcelain to millingable palladium-silver (Pd-Ag) alloy, with that of 3 conventionally used metal-ceramic alloys. MATERIALS AND METHODS: Four types of metal-ceramic alloys, castable nonprecious nickel-chrome alloy, castable precious metal alloys containing 83% and 32% of gold, and millingable Pd-Ag alloy were used to make metal specimens (n=40). And porcelain was applied on the center area of metal specimen. Three-point bending test was performed with universal testing machine. The bond strength data were analyzed with a one-way ANOVA and post hoc Scheffe's tests (alpha=.05). RESULTS: The 3-point bending test showed the strongest (40.42 +/- 5.72 MPa) metal-ceramic bond in the nonprecious Ni-Cr alloy, followed by millingable Pd-Ag alloy (37.71 +/- 2.46 MPa), precious metal alloy containing 83% of gold (35.89 +/- 1.93 MPa), and precious metal alloy containing 32% of gold (34.59 +/- 2.63 MPa). Nonprecious Ni-Cr alloy and precious metal alloy containing 32% of gold showed significant difference (P<.05). CONCLUSION: The type of metal-ceramic alloys affects the bond strength of porcelain. Every metal-ceramic alloy used in this study showed clinically applicable bond strength with porcelain (25 MPa).

Preparation of Label-free Thrombin Aptasensor Based on Pd-Au Nanoparticles / 分析化学

Pd nanoparticles (Pd NPs) were electrodeposited on the glassy carbon electrode (GCE). Then, Pd NPs/GCE was further inserted into H2 SO4 solution to polarize for 5 min to absorb a certain amount of active hydrogen. Then, the electrode was quickly inserted to HAuCl4 solution for 15 min. AuNPs were deposited spontaneously on the surface of Pd NPs due to the reduction of active hydrogen. As a result, Pd-AuNPs were modified on the surface of GCE. Next, aptamer I of thrombin was immobilized on Pd-Au nanoparticles. In the presence of thrombin, it bound with the aptamer immobilized on Pd-Au nanoparticles and thus the formed complex obstructed the catalysis of Pd-Au nanoparticles to H2 O2 . Hence, the reduction current of H2 O2 decreased with the increase of thrombin concentration. The aptamer sensor had a good linear relationship with the concentration of thrombin in the range of 2. 98-297 nmol/L with a detection limit of 0. 98 nmol/L.

Analysis of HBV,HCV and TP infection status in 238 907 voluntary blood donors / 国际检验医学杂志

Objective To investigate pathogens of hepatitis B virus (HBV) ,hepatitis C virus(HCV) and treponema palladium (TP) current infection situation and trend among voluntary blood donors in Pingdingshan city .Methods The testing results of HB-sAg ,anti-HCV and anti-TP among voluntary blood donors were investigated and analyzed .Results Six-year total positive rates of HBsAg ,anti-HCV and anti-TP were 1 .24% ,0 .55% and 0 .48% ,respectively .Positive rates of HBsAg ,anti-HCV and anti-TP were going downward year after year ,in recent three years especially .Conclusion The initial effects of establishing a safe and fixed voluntary blood donor group have been shown .

Analysis of methyl parathion in biological samples using thin layer chromatography.

Pesticides are major contaminating chemicals in agriculture environment and a hazard to exposed population. The pesticides form a strong class of environment pollutants, as they are sometimes nonbiodegradable, damaged not only the environment and agriculture but also have entered into the food chain thereby affecting health and development. Methyl parathion is a broad-spectrum organophosphorus insecticide generally used to control a variety of insects. The present study was planned to develop a new method for analysis of Methyl parathion in human blood samples using thin layer chromatography technique, which is simple and quick. Methyl Parathion was extracted from blood using solvent extraction methods and then identified on the TLC plates. For chromatographic separation, various binary and tertiary solvent systems were used and for detection on developed plates, palladium chloride reagent was used which successfully increased the sensitivity without dispensing with the simplicity of the method. Statistical analysis was performed on four solvent systems namely benzene: chloroform (80:20), hexane: carbontetrachloride (50:50), hexane: carbontetrachloride (20:80), hexane: propanol (20:80) which included the calculation of mean Rf value, value of standard deviation and coefficient of variance. It is evident from the statistical data that hexane: carbontetrachloride (50:50), hexane: carbon tetrachloride (20:80) is preferably good solvent systems for parathion identification by thin layer chromatography.

Direct and derivative spectrophotometric determination of palladium (ii) in presence of micellar medium in hydrogination catalyst samples, synthetic alloy samples and in water samples using 4-hdroxy 3, 5 dimethoxy benzaldehyde-4-hydroxy benzoylhydrazone (HDMBHBH).

A rapid, simple, sensitive and selective spectrophotometric method has been developed for the determination of Palladium (II) using newly synthesized reagent 4-Hdroxy3,5dimethoxybenzaldehyde-4- hydroxybenzoylhydrazone (HDMBHBH) in neutral surfactant of TritonX-100-5% (micellar medium). Palladium (II) forms a brown coluored water-soluble complex with 4-Hdroxy 3, 5dimethoxybenzaldehyde-4- hydroxybenzoylhydrazone in the pH range 1.0-6.0. The complex shows maximum absorbance at lmax 373 nm and in the pH range 3.0-4.0. However, at this wavelength, the reagent shows considerable absorbance. At lmax 373 nm, the complex shows maximum absorbance while the reagent blank shows negligible absorbance. Hence, analytical studies are carried out at lmax 373 nm and at pH 3.0 (Phosphate buffer) against reagent blank. Beer's law is obeyed in the range 0.106-1.064 μg ml-1 and the optimum concentration range from ringbom plot is 0.212-0.957 mg/ml of Palladium (II). The molar absorptivity and Sandell's sensitivity for the coloured solution are found to be 7.5 x 104L mol-1 cm-1 and 0.0015-μg. cm-2 respectively. The interference effect of various diverse ions has been studied. The complex shows 1:1 [Pd (II): HDMBHBH] stoichiometry with stability constant 7.29 x 106. The standard deviation of the method in the determination of 0.638 - μg ml-1 of Palladium (II) is 0.003 and the Relative standard deviation is 0.71%. First and second order derivative spectroscopic method is developed at lmax 422 nm and lmax 444 nm respectively for the determination of Palladium (II), which is more sensitive than the zero order method. The developed method has been employed for the determination of Palladium (II) in hydrogenation catalyst samples and in synthetic alloy samples. The results are in good agreement with the certified values.

Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

The science of catalysis and surface science have developed, independently, key information for understanding catalytic processes. One might argue: is there anything fundamental to be discovered through the interplay between catalysis and surface science? Real catalysts of monometallic and bimetallic Co/Nb2O5 and Pd-Co/Nb2O5 catalysts showed interesting selectivity results on the Fischer-Tropsch synthesis (Noronha et al. 1996, Rosenir et al. 1993). The presence of a noble metal increased the C+5 selectivity and decreased the methane formation depending of the reduction temperature. Model catalyst of Co-Pd supported on niobia and alumina were prepared and characterized at the atomic level, thus forming the basis for a comparison with "real" support materials. Growth, morphology and structure of both pure metal and alloy particles were studied. It is possible to support the strong metal support interaction suggested by studies on real catalysts via the investigation of model systems for niobia in comparison to alumina support in which this effect does not occur. Formation of Co2+ penetration into the niobia lattice was suggested on the basis of powder studies and can be fully supported on the basis of model studies. It is shown for both real catalysts and model systems that oxidation state of Co plays a key role in controlling the reactivity in Fischer-Tropsch reactions systems and that the addition of Pd is a determining factor for the stability of the catalyst. It is demonstrated that the interaction with unsaturated hydrocarbons depends strongly on the state of oxidation.

As ciências da catálise e da superfície têm desenvolvido independentemente temas básicos para o entendimento de processos catalíticos. Pode-se até questionar se há ainda algo fundamental para ser descoberto através da interface entre catálise eciência da superfície? Catalisadores mono e bimetálicos de Co/Nb2O5 e Pd-Co/ Nb2O5 apresentaram resultados interessantes de seletividade na síntese de Fischer-Tropsch (Noronha et al. 1996, Roseniret al. 1993). A presença de metal nobre aumentou a seletividade de C+5 e diminuiu a formação de metano dependendo da temperatura de redução. Catalisadores modelo de Co-Pdsuportados em nióbia e alumina foram preparados e caracterizados a nível atômico, servindo de base para comparação do catalisador "real". Foram estudados o crescimento de partículas, bem como a morfologia e a estrutura de partículas de ambos, metal puro e ligas. É possível suportar as propostas que sugerem uma forte interação metal suporte em catalisadores reais através das pesquisas em sistemas modelos para nióbia quando comparadas com suportes de alumina onde estes efeitos não aparecem. A formação de Co2+ penetrando na rededa nióbia, sugerida para catalisadores em forma de pó, foi totalmente confirmada pelos estudos em catalisadores modelo. Mostrou-se ainda que para ambos os sistemas reais e modelos, que o estado oxidado do Co tem papel fundamental na reatividade das reações de Fischer-Tropsch e que a adição de Pd é um fator determinante para a estabilidade do catalisador. Demonstrou-se que a interação com hidrocarbonetos insaturados depende fortemente do estado oxidado do metal.

Simultaneous Determination of Catechol and Hydroquinone at Electrospun Palladium Nanoparticle/Carbon Nanofibers Modified Electrode / 分析化学

Palladium nanoparticle/carbon nanofibers(Pd/CNFs) were prepared by electrospinning technique with subsequent thermal treatments and were employed to modify glassy carbon electrode (Pd/CNF-GCE/ CME). Pd/CNF-GCE/CME exhibited excellent electrocatalytic activities towards catechol and hydroquinone,and the reversibility of catechol and hydroquinone were significantly improved. The effects of pH value on the oxidation peak current and potential of catechol and hydroquinone were studied by differential pulse voltamme-try(DPV),and 0. 1 mol/L PBS(pH 8.0) was selected as the supporting electrolyte. Under the optimized conditions,the oxidation peak current of catechol was linearly with the concentration of catechol in the range of 1-90μmol/L in the presence of 50 μmol/L hydroquinone with the detection limit of 0.3μmol/L(S/V =3) and the oxidation peak current of hydroquinone was linearly with the concentration of hydroquinone in the range of 2 - 100μmol/L in the presence of 50 μmol/L catechol with the detection limit of 1. 0μmol/L. Furthermore,the modified electrode exhibited good reproducibility and selectivity. The modified electrode has been used for the determination of catechol and hydroquinone in imitative water samples with satisfactory results.