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1.
Magn Reson Imaging ; 111: 103-112, 2024 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-38685362

RESUMEN

BACKGROUND: For patients with complete breast resection, conventional contrast-enhanced T1-weighted imaging (CE-T1WI) with frequency-selective spectral attenuated inversion recovery (SPAIR) provides limited fat suppression on the postoperative side due to the uneven skin surface, inhomogeneous tissue environment, and frequency-selective feature of the SPAIR scheme, leading to difficulties in precise diagnosis. This study aimed to investigate the image quality and performance of the Dixon method compared with SPAIR in breast high-resolution CE-T1WI for mastectomy patients. MATERIALS AND METHODS: Sixty female patients who had not performed any breast surgeries were randomly selected retrospectively as the control group. Postmastectomy female patients were enrolled to undergone high-resolution CE-T1WI with SPAIR and Dixon breast scans. Subjective scores were rated using a 5-point scale. Objective parameters, including contrast-to-noise ratio (CNR), edge sharpness, and signal uniformity were measured and calculated. The Wilcoxon rank-sum test and Kappa statistic were used. RESULTS: A total of 114 consecutive postmastectomy patients were included. Subjective scores of T1WI-SPAIR in the control group were all significantly better than those with SPAIR on the postoperative side of mastectomy patients (P < 0.01). Dixon outperformed SPAIR with significantly better subjective scores in regards to uniformity and degree of fat-suppression, anatomical structures depiction, lesion conspicuity, and axillary visibility (p < 0.05) in both post- and non-operative sides and bilateral axillary areas through the paired comparison. The objective parameters of Dixon were significantly better than those of SPAIR. CONCLUSION: The Dixon method provided better image uniformity and higher fat suppression efficiency, and showed significant advantages in delineating the anatomical structures, with better axillary and lesion visibilities, especially on the completely removed breast side.

2.
Adv Mater ; 35(35): e2301901, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37079477

RESUMEN

Photothermal therapy (PTT) has received increasing interest in cancer therapeutics owing to its excellent efficacy and controllability. However, there are two major limitations in PTT applications, which are the tissue penetration depth of lasers within the absorption range of photothermal agents and the unavoidable tissue empyrosis induced by high-energy lasers. Herein, a gas/phototheranostic nanocomposite (NA1020-NO@PLX) is engineered that integrates the second near-infrared-peak (NIR-II-peak) absorbing aza-boron-dipyrromethenes (aza-BODIPY,NA1020) with the thermal-sensitive nitric oxide (NO) donor (S-nitroso-N-acetylpenicillamine, SNAP). An enhanced intramolecular charge transfer mechanism is proposed to achieve the NIR-II-peak absorbance (λmax = 1020 nm) on NA1020, thereby obtaining its deep tissue penetration depth. The NA1020 exhibits a remarkable photothermal conversion, making it feasible for the deep-tissue orthotopic osteosarcoma therapy and providing favorable NIR-II emission to precisely pinpoint the tumor for a visible PTT process. The simultaneously investigated atraumatic therapeutic process with an enhanced cell apoptosis mechanism indicates the feasibility of the synergistic NO/low-temperature PTT for osteosarcoma. Herein, this gas/phototheranostic strategy optimizes the existing PTT to present a repeatable and atraumatic photothermal therapeutic process for deep-tissue tumors, validating its potential clinical applications.


Asunto(s)
Neoplasias Óseas , Nanocompuestos , Nanopartículas , Neoplasias , Osteosarcoma , Humanos , Donantes de Óxido Nítrico , Fototerapia , Nanocompuestos/uso terapéutico , Línea Celular Tumoral
3.
Adv Healthc Mater ; 12(15): e2203054, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-36745877

RESUMEN

Pathogenic bacterial infection is the most frequent wound complication, which has become a major clinical and healthcare challenge in wound management worldwide, leading to impaired healing processes, the risk of amputation, and even death. Here, collagen-based nanocomposite dressings (APZC) with broad-spectrum antibacterial activity are developed to promote the infected full-thickness wound healing. Short rod-like shaped ZnO NPs are synthesized and then coated with polydopamine (PDA) to obtain PDA coated ZnO NPs (PDA@ZnO NPs). Afterward, PDA@ZnO NPs are conjugated on the backbone of a collagen chain, and the obtained collagen-PDA@ZnO NPs conjugate is crosslinked by dialdehyde sodium alginate to fabricate APZC dressings. PDA@ZnO NPs show well dispersibility and are uniformly incorporated into the collagen matrix. APZC dressings have interconnected microporous structure and great physicochemical properties, besides good blood coagulation performance and well cytocompatibility. APZC dressings demonstrate long-lasting and excellently broad-spectrum antimicrobial activity, which can relieve the inflammatory reaction by killing pathogenic bacteria and induce the generation of blood vessels and the orderly deposition of collagen in the wound site, thus promoting infected full-thickness wound healing without obvious scar formation. Overall, the functionalized collagen-based nanocomposite dressings have great potential in the clinical treatment against bacteria-associated wound infection.


Asunto(s)
Nanocompuestos , Infección de Heridas , Óxido de Zinc , Humanos , Óxido de Zinc/química , Cicatrización de Heridas , Colágeno/farmacología , Bacterias , Nanocompuestos/uso terapéutico , Vendajes , Antibacterianos/farmacología , Antibacterianos/química , Infección de Heridas/patología
4.
ACS Appl Bio Mater ; 5(11): 5418-5431, 2022 11 21.
Artículo en Inglés | MEDLINE | ID: mdl-36326507

RESUMEN

Nanoparticle drug delivery systems have drawn considerable attention worldwide due to their unique characteristics and advantages in anticancer drug delivery. Herein, the curcumin (Cur) loaded nanomicelles with two-stage drug release behavior were developed. ß-Cyclodextrin (ß-CD) and cholesterol were conjugated onto both ends of the poly(ethylene glycol) (PEG) chain to obtain an amphiphilic ß-CD-PEG-Chol. The Cur was loaded into the cavities of ß-CD and nanomicelle when the ß-CD-PEG-Chol self-assembled to the Cur@ß-CD-PEG-Chol nanomicelles (Cur@CPC NMs). These Cur@CPC NMs are spherical particles with a particle size of 120.9 nm. The Cur drug loading capacity of Cur@CPC NMs are 61.6 ± 6.9 mg/g. The release behavior of Cur from Cur@CPC NMs conformed to a two-stage mode of "burst-release followed by sustained-release". The prepared Cur@CPC NMs possess high storage stability and excellent hemocompatibility. Moreover, these Cur@CPC NMs exhibit satisfactory antioxidant activity and anticancer activity, resulting in significant reduction in intracellular H2O2-induced ROS and a nearly 50% lethality rate of HepG-2 cells. Meanwhile, the Cur@CPC NMs show good anti-inflammatory activity, by which the secretion of inflammatory factors of IL-6 and TNF-α are inhibited. Overall, the developed Cur@CPC NMs show application prospects in anticancer drug delivery systems.


Asunto(s)
Antineoplásicos , Curcumina , beta-Ciclodextrinas , Peróxido de Hidrógeno , Polietilenglicoles , Sistemas de Liberación de Medicamentos , Colesterol , Curcumina/farmacología , Antineoplásicos/farmacología
5.
Carbohydr Polym ; 277: 118827, 2022 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-34893244

RESUMEN

pH-Responsive nanoparticles (NPs) have emerged as an effective antitumor drug delivery system, promoting the drugs accumulation in the tumor and selectively releasing drugs in tumoral acidic microenvironment. Herein, we developed a new amphiphilic modified hydroxyethyl starch (HES) based pH-sensitive nanocarrier of antitumor drug delivery. HES was first modified by hydrophilic imidazole and hydrophobic cholesterol to obtain an amphiphilic polymer (IHC). Then IHC can self-assemble to encapsulate doxorubicin (DOX) and form doxorubicin-loaded nanoparticles (DOX/IHC NPs), which displayed good stability for one week storage and acidic sensitive long-term sustained release of DOX. As a result, cancer cell endocytosed DOX/IHC NPs could continuously release doxorubicin into cytoplasm and nucleus to effectively kill cancer cells. Additionally, DOX/IHC NPs could be effectively enriched in the tumor tissue, showing enhanced tumor growth inhibition effect compared to free doxorubicin. Overall, our amphiphilic modified HES-based NPs possess a great potential as drug delivery system for cancer chemotherapy.


Asunto(s)
Antibióticos Antineoplásicos/farmacología , Colesterol/química , Doxorrubicina/farmacología , Derivados de Hidroxietil Almidón/química , Imidazoles/química , Nanopartículas/química , Tensoactivos/química , Animales , Antibióticos Antineoplásicos/química , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Doxorrubicina/química , Portadores de Fármacos/química , Liberación de Fármacos , Ensayos de Selección de Medicamentos Antitumorales , Células Hep G2 , Humanos , Concentración de Iones de Hidrógeno , Neoplasias Hepáticas Experimentales/tratamiento farmacológico , Neoplasias Hepáticas Experimentales/metabolismo , Neoplasias Hepáticas Experimentales/patología , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Tamaño de la Partícula , Células Tumorales Cultivadas
6.
Integr Cancer Ther ; 20: 15347354211058464, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34781754

RESUMEN

OBJECTIVE: To evaluate the therapeutic effect of Traditional Chinese Medicine (TCM), specifically Fuzheng Qingdu (FZQD) therapy, on the survival time of metastatic GC patients. PATIENTS AND METHODS: Databases of medical records of 6 hospitals showed that 432 patients with stage IV GC were enrolled from March 1, 2012 to October 31, 2020. Propensity score matching (PSM) was used to reduce the bias caused by confounding factors in the comparison between the TCM and the non-TCM users. We used a Cox multivariate regression model to compare the hazard ratio (HR) value for mortality risk, and Kaplan-Meier survival curve for the survival time of GC patients. RESULTS: The same number of subjects from the non-TCM group were matched with 122 TCM-treated patients after PSM to evaluate their overall survival (OS) and progression-free survival (PFS). Median time of OS of TCM and non-TCM users were 16.53 and 9.10 months, respectively. TCM and non-TCM groups demonstrated a 1-year survival rate of 68.5% and 34.5%, 2-year survival rate of 28.6% and 3.5%, and 3-year survival rate of 17.8% and 0.0%, respectively. A statistical difference exists in OS between the 2 groups (χ2 = 33.39 and P < .0001). The PFS of TCM users was also longer than that of non-TCM users (χ2 = 4.95 and P = 0.026). Notably, Chinese herbal decoction, Shenmai and compound Kushen injections were commonly used for FZQD therapy. CONCLUSION: This propensity-matched study showed that FZQD therapy could improve the survival of metastatic GC patients.


Asunto(s)
Antineoplásicos , Neoplasias Gástricas , Antineoplásicos/uso terapéutico , Medicamentos Herbarios Chinos , Humanos , Estimación de Kaplan-Meier , Medicina Tradicional China , Neoplasias Gástricas/tratamiento farmacológico
7.
Environ Sci Technol ; 54(21): 14000-14006, 2020 11 03.
Artículo en Inglés | MEDLINE | ID: mdl-33084306

RESUMEN

Acid mine drainage (AMD) is the most significant environmental pollution problem associated with the mining industry. Case-specific testing is widely applied and established in the mining and consulting businesses for AMD prediction, and any improvements in its efficiency, while reducing its environmental impact, are of utmost societal importance. In this study, we develop a microfluidic screening method as a useful tool in the prediction and, potentially, prevention and remediation of AMD. The new approach offers key advantages including high throughput screening of reaction conditions, better spatiotemporal control over the process, and ability to conduct field-based measurements, which will account for specific interactions between mineral ores and their environment. Reagent and sample consumptions are greatly reduced to mL and mg levels, compared with those in conventional bulk-scale screening. Parallel (multichip) screening of ferric ion concentration gradients (0-40 mM) and temperature (23-75 °C) is demonstrated here, showing that the dissolution rate of pyrite significantly changes with the pH, temperature, and the ferric ion concentration, consistent with previous bulk-scale studies. To verify the robustness of the method, a mine waste rock was also tested in the microchip with natural waters. This study demonstrates the application of microfluidic screening to the challenging issue of AMD and, more generally, forecasting and optimization of mineral leaching in industry.


Asunto(s)
Microfluídica , Contaminantes Químicos del Agua , Ácidos , Concentración de Iones de Hidrógeno , Minerales , Minería , Contaminantes Químicos del Agua/análisis
8.
Iran J Kidney Dis ; 14(4): 256-266, 2020 07.
Artículo en Inglés | MEDLINE | ID: mdl-32655020

RESUMEN

Carvedilol, the third generation of vasodilators; serves as the blocker of non-selective beta-adrenergic receptor and alpha1 adrenergic receptor. It could protect the cardiovascular system of patients receiving dialysis treatment. However, current clinical trials discussing the therapeutic benefit of carvedilol on patients receiving dialysis treatment remain inconsistent. Consequently, we decided to perform a meta-analysis to evaluate the clinical efficacy of carvedilol on patients receiving dialysis treatment. A search was conducted using EMBASE, Pubmed, Cochrane Central Register of Controlled Trials, Wanfang database, Chinese National Knowledge Infrastructure (CNKI), and VIP information database up to February 2020. We research publications (include English and Chinese language) that discuss the effects of carvedilol on cardiovascular events, all-cause mortality, hospitalizations or left ventricular ejection fraction (LVEF) in dialysis population. Our analysis included 4 randomized control trials and 2 observational studies. We discussed the therapeutical effects of carvedilol on all-cause mortality, cardiovascular events, hospitalizations, and LVEF of patients receiving dialysis treatment. Totally, this analysis reported 2998 hemodialysis (HD) patients. We found a significant association between carvedilol and reduced incidence of all-cause mortality, cardiovascular events and hospitalizations in HD patients. In addition, carvedilol significantly improves LVEF (n = 241; WMD = 6.95; 95% CI, 0.54 to 13.36; I2 = 90%) in HD population. Our systematic review and meta-analysis demonstrates that carvedilol is associated with a reduced incidence of cardiovascular events, all-cause mortality and hospitalizations in patients on HD. Besides; carvedilol significantly improves LVEF in HD population. Nevertheless, high-quality and well-powered evidence is still needed, so as to further confirm the impacts of carvedilol on HD patients.


Asunto(s)
Enfermedades Cardiovasculares , Carvedilol/uso terapéutico , Diálisis Renal , Humanos , Estudios Observacionales como Asunto , Volumen Sistólico , Función Ventricular Izquierda
9.
Anal Chem ; 91(2): 1557-1562, 2019 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-30525486

RESUMEN

This paper reports on an ore-on-a-chip that enables efficient investigations of mineral leaching using real ore samples. Here, chalcopyrite (CuFeS2) ore samples are cut, polished flat, and sealed against a polydimethylsiloxane microchannel. The leach solution is collected for analysis, and the ore sample is then recovered for surface analysis. Compared to conventional bulk-scale leach tests, the ore-on-a-chip allows for faster, more efficient screening of leach parameters using real ore samples obtained from mine sites. Insight and optimization of leach conditions is demonstrated here for chalcopyrite, which has been extensively studied, yet leach performance is still strongly dependent on the origin of the ore. Two grades of chalcopyrite were chosen for this study (moderate and high purity), and the effect of ferric ion concentration and pH was studied in moderate and high purity chalcopyrite ores, respectively. The leach rate of Cu was faster in the presence of ore impurities (moderate grade) compared to the higher purity ore under the same conditions. The results also suggest that Fe is preferentially leached in the early stages to form an iron-deficient sulfide, according to X-ray photoelectron spectroscopy. Longer leach studies (48 h) reported no measurable surface passivation for the conditions studied. The ore-on-a-chip offers a new approach of case specific leach studies, which will enable rapid and tailored optimization of leach strategies for mineral processing.

10.
Anal Chem ; 90(14): 8517-8522, 2018 07 17.
Artículo en Inglés | MEDLINE | ID: mdl-29923704

RESUMEN

We demonstrate a microfluidic screening platform for studying thiosulfate leaching of Au in a transparent microchannel. The approach permits in situ (optical) monitoring of Au thickness, reduced reagent use, rapid optimization of reagent chemistry, screening of temperature, and determination of the activation energy. The results demonstrate the critical importance of the (1) preparation and storage of the leach solution, (2) deposition and annealing of the Au film, and (3) lixiviant chemistry. The density of sputter-deposited Au films decreased with depth resulting in accelerating leach rates during experiments. Atomic leach rates were determined and were constant throughout each experiment. Annealing above 270 °C was found to prevent leaching, which can be attributed to diffusion of the chromium adhesion layer into the Au film. The microfluidic analysis revealed leach rates that are sensitive to the stoichiometric ratio of thiosulfate, ammonia, and copper in the leach solution and optimized for 10 mM CuSO4, 1 M Na2S2O3, and 1 M NH4OH. The temperature dependence of the leach rate gave an apparent activation energy of ∼40 kJ mol-1, based on Arrhenius's relationship.

11.
Sci Total Environ ; 562: 526-532, 2016 08 15.
Artículo en Inglés | MEDLINE | ID: mdl-27110966

RESUMEN

This paper reports the detailed composition and morphology of one-step green synthesized bimetallic Fe/Pd nanoparticles (NPs) using grape leaf aqueous extract and identification of active biomolecules involved in the synthesis employing various techniques. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) revealed that Fe/Pd NPs were polydispersed and quasi-spherical with a diameter ranging from 2 to 20nm. X-ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X-ray Spectroscopy (EDS) provided evidence for the composition of Fe and Pd and for their species existing on the surface of Fe/Pd NPs. In addition, biomolecules in the grape leaf aqueous extract were identified but their functions are still unclear. Biomolecules in the aqueous extract such as methoxy-phenyl-oxime, N-benzoyl-2-cyano-histamine, 2-ethyl-phenol, 1,2-benzenediol, ß-hydroxyquebracamine, hydroquinone, 2-methoxy-4-vinylphenol, 5-methyl-2-furancarboxaldehyde, 4-(3-hydroxybutyl)-3,5,5-trimethyl-2-cyclohexen and some polyphenolic compounds were identified as reducing and capping agents, which were studied by Chromatography-Mass Spectroscopy (GC-MS), XPS and Fourier Transform Infrared Spectroscopy (FTIR). Our finding suggests a new insight into cost-effective, simple, and environmentally benign production of bimetallic Fe/Pd NPs.


Asunto(s)
Nanopartículas del Metal/química , Modelos Químicos , Extractos Vegetales/química , Hierro/química , Paladio/química , Hojas de la Planta/química , Vitis/química
12.
J Hazard Mater ; 303: 145-53, 2016 Feb 13.
Artículo en Inglés | MEDLINE | ID: mdl-26530891

RESUMEN

To reduce cost and enhance reactivity, bimetallic Fe/Pd nanoparticles (NPs) were firstly synthesized using grape leaf aqueous extract to remove Orange II. Green synthesized bimetallic Fe/Pd NPs (98.0%) demonstrated a far higher ability to remove Orange II in 12h compared to Fe NPs (16.0%). Meanwhile, all precursors, e.g., grape leaf extract, Fe(2+) and Pd(2+), had no obvious effect on removing Orange II since less than 2.0% was removed. Kinetics study revealed that the removal rate fitted well to the pseudo-first-order reduction and pseudo-second-order adsorption model, meaning that removing Orange II via Fe/Pd NPs involved both adsorption and catalytic reduction. The remarkable stability of Fe/Pd NPs showed the potential application for removing azo dyes. Furthermore, Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) confirmed the changes in Fe/Pd NPs before and after reaction with Orange II. High Performance Liquid Chromatography-Mass Spectrum (HPLC-MS) identified the degraded products in the removal of Orange II, and finally a removal mechanism was proposed. This one-step strategy using grape leaf aqueous extract to synthesize Fe/Pd NPs is simple, cost-effective and environmentally benign, making possible the large-scale production of Fe/Pd NPs for field remediation.


Asunto(s)
Compuestos Azo/química , Bencenosulfonatos/química , Colorantes/química , Hierro/química , Plomo/química , Nanopartículas/química , Adsorción , Catálisis , Restauración y Remediación Ambiental , Concentración de Iones de Hidrógeno , Cinética , Extractos Vegetales/química , Hojas de la Planta/química , Temperatura , Vitis/química
13.
J Hazard Mater ; 296: 37-45, 2015 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-25910458

RESUMEN

Biomolecules taken from plant extracts have often been used in the single-step synthesis of iron-based nanoparticles (Fe NPs) due to their low cost, environmental safety and sustainable properties. However, the composition of Fe NPs and the degradation mechanism of organic contaminants by them are limited because these are linked to the reactivity of Fe NPs. In this study, Fe NPs synthesized by grape leaf extract served to remove Orange II. Batch experiments showed that more than 92% of Orange II was removed by Fe NPs at high temperature based on adsorption and reduction and confirmed by kinetic studies. To understand the role of Fe NPs in the removal process of azo dye, surface analysis via X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) were employed, showing that the Fe NPs were composed of biomolecules, hydrous iron oxides and Fe(0), thus providing evidence for the adsorption of Orange II onto hydrous iron oxides and its reduction by Fe(0). Degraded products such as 2-naphthol were identified using LC-MS analysis. A degradation mechanism based on asymmetrical azo bond cleavage for the removal of Orange II was proposed.


Asunto(s)
Compuestos Azo/aislamiento & purificación , Bencenosulfonatos/aislamiento & purificación , Contaminantes Ambientales/aislamiento & purificación , Restauración y Remediación Ambiental/métodos , Nanopartículas/química , Extractos Vegetales/química , Vitis/química , Adsorción , Tecnología Química Verde , Modelos Teóricos , Hojas de la Planta/química
14.
Talanta ; 131: 395-403, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25281120

RESUMEN

Sodium potassium absorption ratio (SPAR) is an important measure of agricultural water quality, wherein four exchangeable cations (K(+), Na(+), Ca(2+) and Mg(2+)) should be simultaneously determined. An ISE-array is suitable for this application because its simplicity, rapid response characteristics and lower cost. However, cross-interferences caused by the poor selectivity of ISEs need to be overcome using multivariate chemometric methods. In this paper, a solid contact ISE array, based on a Prussian blue modified glassy carbon electrode (PB-GCE), was applied with a novel chemometric strategy. One of the most popular independent component analysis (ICA) methods, the fast fixed-point algorithm for ICA (fastICA), was implemented by the genetic algorithm (geneticICA) to avoid the local maxima problem commonly observed with fastICA. This geneticICA can be implemented as a data preprocessing method to improve the prediction accuracy of the Back-propagation neural network (BPNN). The ISE array system was validated using 20 real irrigation water samples from South Australia, and acceptable prediction accuracies were obtained.


Asunto(s)
Algoritmos , Carbono/química , Electrodos , Ferrocianuros/química , Vidrio/química , Redes Neurales de la Computación , Contaminantes Químicos del Agua/análisis , Riego Agrícola , Técnicas Biosensibles , Calibración , Colorantes/química , Técnicas Electroquímicas , Impresión Molecular , Análisis de Componente Principal
15.
J Chromatogr A ; 1368: 217-21, 2014 Nov 14.
Artículo en Inglés | MEDLINE | ID: mdl-25441356

RESUMEN

Inductively coupled plasma-mass spectrometry (ICP-MS) and electrospray mass spectrometry (ESI-MS) were used as complementary methods to identify Sn-pentaacetic acid (DTPA) complex formation. ESI-MS was used to initially confirm the formation of [Sn(DTPA)](3-) and [Sn(DTPA)](1-) and their MS spectra suggest these tin complexes were stable in solution. On-column complexation of tin with DTPA and the separation of [Sn(DTPA)](3-) and [Sn(DTPA)](1-) was performed on anion-exchange chromatography with an mobile phase containing 20mM NH4NO3 and 3mM DTPA at pH 6.0, and the subsequent detection of [Sn(DTPA)](3-) and [Sn(DTPA)](1-) was achieved by ICP-MS. Linear plots were obtained in a concentration range of 1.0-1000 µg L(-1) with detection limits ranging from 0.1 to 0.3 µg L(-1). The developed procedure allows the simultaneous determination of [Sn(DTPA)](3-) and [Sn(DTPA)](1-) in less than 5 min with a RSD between 2.1 and 2.7%. The recoveries of [Sn(DTPA)](3-) and [Sn(DTPA)](1-) were found to be 96.8 and 99.4%, respectively, when the sample was spiked with 20 µg L(-1) standard. Finally, the proposed procedure was used for the determination of tin species in contaminated water.


Asunto(s)
Espectrometría de Masas/métodos , Estaño/química , Aniones , Cromatografía/métodos , Límite de Detección
16.
Phys Chem Chem Phys ; 12(41): 13724-9, 2010 Nov 07.
Artículo en Inglés | MEDLINE | ID: mdl-20844783

RESUMEN

We report on the influence of heat treatment on the surface chemistry of an α-alumina crystal. We compare its electrical double layer behaviour with that of 150 nm diameter α-Al(2)O(3) particles. Surface spectroscopy and zeta potential studies are used to understand the changes in surface chemistry. The pH(pzc) of an α-Al(2)O(3) (0001) single crystal (∼4) is more acidic than that of α-Al(2)O(3) particles (8.5), a difference explained by the dominance of [triple bond, length as m-dash]Al(2)OH surface groups on the single crystals and their charging behaviour. Heat treatment of the alumina surface causes a substantial decrease in the number of surface OH groups. Heating at 500 °C decreases the surface density of hydroxyl groups. Heating at 1050 °C also affects surface morphology and surface chemistry. The increased magnitude of the zeta potential and the pH(pzc) shift to lower pH suggest a surface reconstruction and the appearance of more acidic aluminium sites.

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