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1.
J Environ Manage ; 269: 110758, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32560988

RESUMO

Membrane separation technology is recognized as a competitive approach to remove Pb2+ from water system due to its high efficiency and low operating cost. In present study, a simple and facile approach was developed to fabricate covalent organic framework (COF) modified PVDF ultrafiltration membranes with comprehensive antifouling property and superior Pb2+ removal ability. Herein, COF was synthesised in a homogenous PVDF/DMAc solution to fabricate hydrophilic COF modified PVDF ultrafiltration membranes with the Pb2+ removal property. The filtration test demonstrated that the COF modified PVDF ultrafiltration membranes exhibited excellent antifouling property and high water flux. Moreover, the membranes showed remarkable potential for treating Pb2+-containing water. The removal efficiency was determined at 92.4%, and its removal efficiency was 87.5% at the fourth treatment cycle with Pb2+-containing water. The present work provides a valuable platform for further development of efficient composite membranes for the treatment of Pb2+-containing water.


Assuntos
Estruturas Metalorgânicas , Ultrafiltração , Chumbo , Membranas Artificiais , Polivinil
2.
Water Res ; 181: 115952, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32497754

RESUMO

Tetrabromobisphenol-A (TBBPA) is one of the most important brominated flame retardants (BFRs), accounting for 60% of the total commercial BFR market. Increasing amounts of TBBPA and byproducts are released to the aquatic environment due to their extensive utilization in various sectors. However, research on the treatment of TBBPA contaminated wastewater using membrane filtration is still lacked. Herein, a PVDF10-PAA-ZrO2 membrane was successfully developed and applied for the treatment of high-concentration TBBPA wastewater with super-high water recovery. The membrane was obtained through surface functionalization with nano-ZrO2 from commercial PVDF ultrafiltration (UF) membrane. Compared to the commercial PVDF membrane, the developed membrane exhibited 4 times of permeate flux which was up to 200 L/m2 min with comparable TBBPA rejection rate. Furthermore, the mechanisms of membrane development and TBBPA rejection were explored through synchrotron-based ATR-FTIR and X-ray analyses. It was revealed that ZrO2 NPs were immobilized into membrane surface through binding with PAA layer, where the O of the carboxyl group combined with the Zr4+ on the ZrO2 NP surface to form C-O-Zr bond through monodentate and bridging-bidentate modes. The sieving function of membrane could be the main mechanism of TBBPA removal. This research demonstrated a practical route and solid insight toward the development of highly efficient membrane for TBBPA removal. The proposed PVDF10-PAA-ZrO2 membrane can also be promising for other industrial separation and purification applications.


Assuntos
Retardadores de Chama , Bifenil Polibromatos , Polivinil , Ultrafiltração , Água
3.
Vasc Health Risk Manag ; 16: 181-191, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32547045

RESUMO

Objective: Treatment of brain arteriovenous malformations (AVMs) aims to abolish any risk for intracranial hemorrhage with the preservation of the patient's functional status. We present the technique of pre-surgical endovascular devascularization through proximal feeder artery occlusion for the treatment of cranial AVMs rather than nidus occlusion. Also, we highlight the advantages and the possible clinical indications. Patients and Methods: Two patients with brain AVM and one patient with scalp AVM were treated by pre-surgical endovascular devascularization followed by surgical resection. Endovascular devascularization was performed by occlusion of the AVM feeders only with Liquid Embolic System Agent (Onyx®) 18 without entering and filling the nidus. During surgery, feeding arteries colored with the black color of the Liquid Embolic System Agent were clearly identified and cut. Dissection of the AVM was performed, and resection of the nidus was achieved. Results: Total resection of the AVM was achieved in all cases confirmed with follow-up angiographies, with no neurologic or systemic complications. Also, no major bleeding was detected. In addition, the surgical clips were avoided during surgery. Brain AVMs were safely resected in piecemeal fashion. Conclusion: Pre-surgical endovascular proximal feeder artery devascularization technique shows to be a safe, simple and effective technique for the management of cranial arteriovenous malformations. This technique simplifies both the endovascular and surgical approaches to complicated cranial AVM cases.


Assuntos
Encéfalo/irrigação sanguínea , Embolização Terapêutica , Malformações Arteriovenosas Intracranianas/terapia , Polivinil/administração & dosagem , Couro Cabeludo/irrigação sanguínea , Tantálio/administração & dosagem , Procedimentos Cirúrgicos Vasculares , Adolescente , Adulto , Circulação Cerebrovascular , Pré-Escolar , Combinação de Medicamentos , Feminino , Humanos , Malformações Arteriovenosas Intracranianas/diagnóstico por imagem , Malformações Arteriovenosas Intracranianas/fisiopatologia , Masculino , Resultado do Tratamento
4.
J Contemp Dent Pract ; 21(2): 190-196, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32381826

RESUMO

AIM: The aim of the study was to evaluate the dimensional accuracy of three combinations of polyvinyl siloxane impression material by double-mix single-step impression technique. MATERIALS AND METHODS: Metal master model was made according to the ADA specification no. 19; ISO 4823:2000/AMD 2007. Impressions were made using perforated custom-made metallic trays of 2 mm and 4 mm spacing, the impression materials used were putty, heavy body, regular body and light body. A total of 30 impressions were made by single-step technique and poured in die stone to obtain resultant cast. Ten impressions were made of each combination of polyvinyl siloxane (PVS). Three dimensions (interabutment distance, height and diameter) on resultant cast were measured and compared with metal master model. The results were statistically analyzed and tabulated. RESULTS: Diameter of abutment, the height of abutment and interabutment distance in each group were larger in dimensions as compared with metal master model. The dimensional discrepancies of group I, group II and group III casts when compared with the master model were significantly different from each other. The least difference was found in group I. CONCLUSION: The one-step putty-light body combination (group I) produced the most accurate stone casts compared with one-step heavy body-light body and regular body-light body combinations. CLINICAL SIGNIFICANCE: In everyday dental practice, impression making is imperative. Hence, by doing this study, we tried to find out which material combination is suitable to give us predictable and accurate results.


Assuntos
Técnica de Moldagem Odontológica , Modelos Dentários , Polivinil , Siloxanas
5.
Chemosphere ; 257: 127144, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32473409

RESUMO

Polyvinylidene fluoride (PVDF) membrane was coated with polyvinyl alcohol (PVA)/titanium dioxide (TiO2) solution using dip-coating method. The effect of PVA loading (0-12 wt%) at a fixed TiO2 concentration (1 wt%) was investigated through physical and morphological characterization of the membranes. The experimental results showed that increasing the PVA content from 0 to 12 wt% in the coating solution increased the hydrophilicity and tensile strength as well as the young's modulus of the coated membranes. It also increased the thickness of the thin film coating which enhanced the removal of dyes but affected the permeate flux adversely. Larger the molecular weight of the dye, higher the rejection and lower the permeate flux obtained. The antifouling performance of the membrane was studied using Bovine Serum Albumin (BSA) solution and the fouling was measured using the irreversible fouling factor. The results indicated that the PVA/TiO2 coated PVDF membrane had lower irreversible fouling factors compared to plain PVDF membrane. The PVDF membrane with a thin film coating containing 3 wt% of PVA and 1 wt% of TiO2 showed high photocatalytic degradation for the three dyes studied under UV irradiation due to uniform dispersion of TiO2 nanoparticles over the membrane surface. Further, smaller the molecular weight of the dye, larger the photodegradation that was observed.


Assuntos
Corantes/química , Álcool de Polivinil/química , Polivinil/química , Eliminação de Resíduos Líquidos/métodos , Interações Hidrofóbicas e Hidrofílicas , Membranas Artificiais , Nanopartículas , Fotólise , Soroalbumina Bovina , Têxteis , Titânio , Raios Ultravioleta
6.
Chemosphere ; 253: 126649, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32268250

RESUMO

The novel highly hydrophilic composite additive, graphene oxide-polyethylene glycol (GO-PEG, further abbreviated as P-GO), was synthesized from GO and PEG by the esterification reaction. Then, P-GO was blended into a polyvinylidene fluoride (PVDF) casting solution as an additive, and the effects of P-GO on the performance of the PVDF ultrafiltration (UF) membrane were researched. When amount of added P-GO was 0.5 wt%, the flux of the resultant modified membrane (denoted as P/0.5P-GO) reached as high as 93 L m-2·h-1, that is twice than that of the pure PVDF membrane (45 L m-2·h-1). Furthermore, water contact angle results confirmed significantly improved hydrophilicity of the P/0.5P-GO membrane. Results of antifouling tests revealed that the P/0.5P-GO membrane showed the lowest total resistance and irreversible resistance among all the membranes prepared in this study, and after physical cleaning, its flux recovery ratio was the highest-78%. These results demonstrated improved antifouling performance of the P/0.5P-GO membrane. Therefore, it can be concluded that P-GO as an additive material for the PVDF membrane has satisfactory performance in improving the membrane hydrophilicity, permeability, and antifouling performance in practical applications.


Assuntos
Nanocompostos/química , Polietilenoglicóis/química , Polivinil/química , Purificação da Água/métodos , Grafite , Interações Hidrofóbicas e Hidrofílicas , Membranas Artificiais , Permeabilidade , Ultrafiltração/métodos
7.
Water Res ; 176: 115749, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32247996

RESUMO

Biofouling remains to be one of major obstacles in membrane bioreactors (MBRs), calling for the development of antibiofouling membranes. Silver nanoparticles (AgNPs), being a kind of broad spectrum bactericidal agent, have been widely used for modifying membrane; however, uncontrollable release of AgNPs and thus a short lifetime of modified membranes are thorny issues for the AgNPs-modified membranes. In this study, silica nanopollens were used as AgNPs nanocarriers for membrane modification (ASNP-M), which could improve silver delivery efficacy, avoid agglomeration and control Ag+ release towards bacteria. At a silver loading of 107.7 ± 10.9 µg Ag/cm2, ASNP-M effectively inhibited growth of Escherichia coli and Staphylococcus aureus, with an Ag+ release rate of 0.5 µg/(cm2 d). Long-term MBR tests showed that ASNP-M exhibited a significantly reduced transmembrane pressure increase rate of 0.88 ± 0.34 kPa/d which was much lower than that of two control membranes, i.e., pristine membrane (M0) (2.32 ± 0.86 kPa/d) and Ag@silica nanospheres (without spikes) modified membrane (ASNS-M) (2.25 ± 1.28 kPa/d). No significant adverse influences on the pollutant removal were also observed in the reactor. Foulants analysis revealed that biofilm of ASNP-M was thinner and comprised of mainly dead cells, and only organic matter with strong adhesion properties was allowed to attach onto the membrane surface. Bacterial community analysis suggested that the incorporation of Ag@silica nanopollens inhibited colonization of bacteria which are capable of causing membrane biofouling (e.g., Proteobacteria and Actinobacteria). These findings highlight the potential of the antibiofouling membrane to be used in MBRs for wastewater treatment and reclamation.


Assuntos
Incrustação Biológica , Nanopartículas Metálicas , Reatores Biológicos , Membranas Artificiais , Polivinil , Dióxido de Silício , Prata , Águas Residuárias
8.
Gene ; 740: 144534, 2020 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-32145328

RESUMO

The function of tissue cells is strongly depends on the extracellular matrix (ECM) that can guide and support cell structure. This support plays a crucial role in the process of cell proliferation and differentiation. Herein, three different nanofibrous scaffolds that are highly attractive for tissue engineering were selected and then osteogenic related genes and protein expression patterns of human adipose-derived mesenchymal stem cells (AT-MSCs) were investigated when grown on substrates. Polycaprolactone, Poly (L-lactic acid) and Polyvinylidene-fluoride nanofibrous scaffolds were fabricated using Electrospinning method and then AT-MSCs viability and osteogenic differentiation were evaluated while cultured on them. The highest AT-MSCs survival rate when grown on the scaffolds was detected when grown on Polyvinylidene-fluoride. In addition, the highest ALP activity and mineralization were also observed in differentiated AT-MSCs has grown on Polyvinylidene-fluoride. The expression levels of Runx2, osteonectin and osteocalcin genes and osteocalcin protein in the AT-MSCs has grown on the Polyvinylidene-fluoride were also significantly higher than the rest of the scaffolds. Based on the results, it seems that since the studied substrate have a similar structural characteristics, their nature may have an important role in the stem cell's osteogenesis process, where the Polyvinylidene-fluoride piezoelectricity was a most distinguished characteristic.


Assuntos
Células-Tronco Mesenquimais , Nanofibras , Osteogênese , Engenharia Tecidual/métodos , Subunidade alfa 1 de Fator de Ligação ao Core/metabolismo , Humanos , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/fisiologia , Nanofibras/química , Osteocalcina/metabolismo , Osteogênese/efeitos dos fármacos , Osteogênese/fisiologia , Osteonectina/metabolismo , Poliésteres , Polivinil
9.
Chemosphere ; 250: 126304, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32120150

RESUMO

Cyclic volatile methylsiloxanes (cVMS) are widely used in consumer products and commonly detected in the environment. There are challenges in the analysis of cVMS because of their ubiquitous use which can introduce high background contamination. The current study introduces a sample preparation method based on headspace of solid-phase microextraction (SPME) for monitoring the cVMS in waters. Efforts were made to reduce the background contamination during sample preparation and instrument analysis. A laboratory prepared MIL-101 coating was prepared using polysulfone instead of polydimethylsiloxane as adhesive to avoid the contamination. The extraction performance of the MIL-101 fiber was optimized and evaluated. The optimized extraction time and temperature were 60 min and 40 °C, respectively. The method quantification limits of the MIL-101 fiber for octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecylcyclohexasiloxane (D6) in water were 0.15 ng mL-1, 0.14 ng mL-1, and 0.27 ng mL-1, respectively. The extraction efficiency of the proposed MIL-101 fiber was comparable to the commercial polydimethylsiloxane/divinylbenzene fiber. The developed method was applied to analyze the cVMS in wastewater treatment plant and the concentrations in the barscreen and in the aeration tank ranged from 0.73 to 3.3 ng mL-1 and 7.74-85.1 ng mL-1, respectively. The MIL-101 fiber was also applied to study the photodegradation of the cVMS in water under simulated sunlight. Approximately 25%, 20%, and 45% of D4, D5, and D6, respectively, were degraded after 10 h exposure.


Assuntos
Siloxanas/química , Microextração em Fase Sólida/métodos , Poluentes Químicos da Água/química , Dimetilpolisiloxanos , Polivinil , Águas Residuárias/análise , Poluentes Químicos da Água/análise
10.
Chemosphere ; 250: 126236, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32088617

RESUMO

While polyphenol-based coating has been regarded as a promising alternative to functionalize membrane surface, it usually suffers from problems of low-efficient procedure and low utilization rate of the polyphenolic compounds, hindering its large-scale implementations. To solve these problems, this study provided a first report on inkjet printing of polyphenols (catechol (CA) or tannic acid (TA)) and sodium periodate (SP) on a polyvinylidene fluoride (PVDF) membrane to improve membrane performance. A series of analyses showed the efficient formation of homogenous films on the PVDF membrane surface and the improvement of hydrophilicity by the inkjet printing technique. The PVDF membranes decorated with the optimized polyphenolic coating exhibited a promising oil/water separation efficiency (higher than 99%) with a high average water permeation flux of 5.2 times higher than that of the pristine membrane. Meanwhile, the modified membranes illustrated a good stability under acidic conditions (pH = 2-7). The novel method proposed in this study is facile, cost-saving and environment-friendly. The advantages of the proposed method and the modified membranes demonstrated the great significance of the proposed method in practical applications.


Assuntos
Membranas Artificiais , Polifenóis/química , Interações Hidrofóbicas e Hidrofílicas , Polivinil , Impressão Tridimensional , Purificação da Água/métodos
11.
Environ Sci Pollut Res Int ; 27(13): 15057-15067, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32065365

RESUMO

The water-sediment interface of lakes is an important and unique area of the water environment; the geochemical behavior of nutrients in this area has a significant impact on the quality of the water environment and ecosystems, especially in shallow lakes. However, most studies do not provide direct in situ evidence for this in shallow lakes in arid regions; in order to explore the coupling relationship between phosphorus (P) and iron (Fe) in a sediment profile, we conducted a high-resolution analysis of liable Fe and P in sediments taken from the Chaiwopu Lake using ZrO-Chelex thin film diffusion gradient technology (ZrO-Chelex DGT). The results show that (1) the vertical spatial distribution trend of the liable P and Fe in the sediments from each sampling site is essentially similar. The contents of the liable P and Fe ranged from 0.004-0.125 mg/L and 0.050-0.190 mg/L, respectively, and the synchronous distribution of the micro-interface concentration reflects the coupling relationship between them. (2) The correlation analysis of the liable P and Fe concentrations showed that there were significant linear correlations between them (P < 0.05, bilateral). (3) The diffusion fluxes of P and Fe were - 51.76~65.12 µg (m2 d)-1 and - 451.27~457.06 µg (m2 d)-1, respectively, and were shown to be negative at the sediment-water interface for most of the samples, which showed that P and Fe were released from the overlying water into the sediments. (4) This research showed that the diffusive fluxes at the different sites are quite different, which indicates that the phosphorus and iron pollution in the sediments of the Chaiwopu Lake is affected by exogenous inputs. There was no significant correlation between P release flux and pH, ORP, conductivity (EC), the TDS of the overlying water, or the pH, salinity (Ca2+, Mg2+), and nutrient (organic matter) content of the sediment. The release flux of Fe is affected by the pH of the sediment. The results of this study provide references for the research of elements in the water-sediment interface of shallow lakes in arid regions, as well as other areas.


Assuntos
Lagos , Poluentes Químicos da Água/análise , China , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos , Ferro/análise , Fósforo/análise , Poliestirenos , Polivinil
12.
Environ Sci Pollut Res Int ; 27(9): 9503-9519, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31919824

RESUMO

The influence of ultrasonication on membrane performance was investigated by two ultrasonication modes, direct and indirect ultrasonication as pretreatment, and simply improved PVDF-TiO2 membranes' performance was systematically compared. Ultrasound intensity of 100% and ultrasonication time ranged from 1 to 2 h positively affect membrane permeability. Characterization results manifested that membrane structure was eventually optimized with an even nano-TiO2 dispersion by direct ultrasonication. Analysis of surface roughness reflected that PVDF-TiO2 (MS-U2) surface morphological pattern was peak-valley structure that resisted fouling greatly. A good fitting of experimental result and Tansel's simulation illustrated that anti-fouling ability was realized direct ultrasonication modified membrane. PVDF-TiO2 (MS-U2) membrane showing the lowest |τ| reflecting the time required to reach a certain level of the fouling degree was the lowest. Relying upon modified Hermia's model analysis, protein blockage within the membrane pore was one major fouling mechanism; surface blockage degree of PVDF-TiO2 (MS-U2) was relative slight. Fouling mechanism analyzed by two models reflected that PVDF-TiO2 (MS-U2) membrane exhibited a higher anti-protein fouling ability during cross-flow filtration process.


Assuntos
Membranas Artificiais , Ultrafiltração , Interações Hidrofóbicas e Hidrofílicas , Polivinil , Titânio
13.
Carbohydr Polym ; 231: 115730, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31888809

RESUMO

Low-cost and highly sensitive piezoelectric sensors were fabricated from bacterial cellulose (BC)/MnFe2O4 nanocomposite films via a co-precipitation method, followed by hot-pressing. MnFe2O4 nanoparticles were homogeneously distributed in the BC structure. The piezoelectric sensitivity measurements in the normal mode showed that the pristine BC film exhibited a sensitivity of ∼5 pC/N, whereas this value was increased to 23 pC/N for the composite film, which is comparable to the PVDF reference film. In the bending mode, the piezoelectric response increased to 25 pC/N and 57 pC/N for the BC film and the composite film, respectively. Moreover, the piezoelectric sensitivity was significantly enhanced using carbon tape electrodes attached directly to the films instead of sandwiched electrodes. This produced a sensitivity of greater than 50 pC/N for the MBC nanocomposite film in the normal mode measurement. Our work demonstrates the potential of using MBC composite films as inexpensive and highly sensitive flexible piezoelectric sensors.


Assuntos
Celulose/química , Nanocompostos/química , Nanopartículas/química , Bactérias/química , Carbono/química , Eletrodos , Compostos Férricos/química , Compostos de Manganês/química , Polivinil/química
14.
Talanta ; 209: 120581, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31892020

RESUMO

Conjugated polyelectrolytes (CPEs) have been widely used as reporters in colorimetric assays targeting nucleic acids. CPEs provide naked eye detection possibility by their superior optical properties however, as concentration of target analytes decrease, trace amounts of nucleic acid typically yield colorimetric responses that are not readily perceivable by naked eye. Herein, we report a pixelated analysis approach for correlating colorimetric responses of CPE with nucleic acid concentrations down to 1 nM, in plasma samples, utilizing a smart phone with an algorithm that can perform analytical testing and data processing. The detection strategy employed relies on conformational transitions between single stranded nucleic acid-cationic CPE duplexes and double stranded nucleic acid-CPE triplexes that yield distinct colorimetric responses for enabling naked eye detection of nucleic acids. Cationic poly[N,N,N-triethyl-3-((4-methylthiophen-3-yl)oxy)propan-1-aminium bromide] is utilized as the CPE reporter deposited on a polyvinylidene fluoride (PVDF) membrane for nucleic acid assay. A smart phone application is developed to capture and digitize the colorimetric response of the individual pixels of the digital images of CPE on the PVDF membrane, followed by an analysis using the algorithm. The proposed pixelated approach enables precise quantification of nucleic acid assay concentrations, thereby eliminating the margin of error involved in conventional methodologies adopted for interpretation of colorimetric responses, for instance, RGB analysis. The obtained results illustrate that a ubiquitous smart phone could be utilized for point of care colorimetric nucleic acids assays in complex matrices without requiring sophisticated software or instrumentation.


Assuntos
Colorimetria/métodos , Ácidos Nucleicos/sangue , Polieletrólitos/química , Técnicas Biossensoriais/instrumentação , Técnicas Biossensoriais/métodos , Cátions/química , Colorimetria/instrumentação , Desenho de Equipamento , Humanos , Ácidos Nucleicos/análise , Papel , Sistemas Automatizados de Assistência Junto ao Leito , Polímeros/química , Polivinil/química , Smartphone , Tiofenos/química
15.
Macromol Rapid Commun ; 41(4): e1900613, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31958201

RESUMO

In the present work, poly(methyl methacrylate) (PMMA) is successfully grafted onto poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) side chains via directly activated CF bonds using Cu(0)/2,2'-bipyridine as catalyst. The reaction mechanism and the initiating sites can be confirmed by the structure of the graft copolymer. The graft copolymerization exhibits first-order kinetics, and reaction conditions can affect the chemical composition of the graft copolymer, including reaction time, reaction temperature, solvents, the amount of catalyst, and monomer. The introduction of rigid PMMA side chains onto P(VDF-TrFE) can effectively tune the displacement-electric field hysteresis behaviors of P(VDF-TrFE) from normal ferroelectric to anti-ferroelectric, even linear-like dielectric, under high electric field, resulting in dramatically reduced energy loss while maintaining the discharged energy density. This work may provide an effective strategy to introduce functional groups into P(VDF-TrFE) copolymer via activation of CF bonds.


Assuntos
Polimetil Metacrilato/química , Polivinil/química , Catálise , Cinética , Polimerização
16.
Carbohydr Polym ; 230: 115606, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31887878

RESUMO

In this research, biocomposite films containing chitosan (CS), polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP), with different ratios, have been provided. The effects of adding hexamethylene 1, 6-di(aminocarboxysulfonate) (HMDACS) as cross-linking agent and the formation of urethane linkage on mechanical properties such as tensile strength, elongation and dynamic-mechanical properties such as storage modulus and tan δ were studied. Also, the antibacterial properties of the composites were investigated by viable bacterial cell counting and compared in reducing the bacterial growth. The final results showed the composite containing CS (50 wt%), PVA (30 wt%), PVP (20 wt%) and HMDACS (2 wt%) had the highest mechanical properties. Scanning electron microscopy (SEM) micrographs confirmed uniform distribution of components in the polymer matrix. In general, low contact angle values revealed the hydrophilicity of the prepared films. It was found that the composites made by combining CS, PVA and PVP at concentration of 50, 25, 25 wt% (A3) and 60, 20, 20 wt% (B4), cross-linked with 2 wt% HMDACS, had the best antibacterial activity against Escherichia coli and Staphylococcus aureus, hence they can be used as promising materials for the preparation of wound dressings.


Assuntos
Curativos Hidrocoloides , Quitosana/análogos & derivados , Nanocompostos/química , Uretana/química , Antibacterianos/química , Antibacterianos/farmacologia , Reagentes para Ligações Cruzadas/química , Escherichia coli/efeitos dos fármacos , Interações Hidrofóbicas e Hidrofílicas , Polivinil/química , Staphylococcus aureus/efeitos dos fármacos
17.
Pharm Res ; 37(2): 28, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31912250

RESUMO

PURPOSE: This study aims to conduct an impact investigation in the hydrophobic-hydrophilic balance as an important factor for dissolution improvement of a hydrophilic carrier-based solid dispersion system. METHODS: Polymeric carriers with different hydrophobic to hydrophilic ratios were used to prepare several electrospun solid dispersion formulations. Physicochemical properties and surface morphology of the samples were assessed using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), polarized light microscopy, Differential Scanning Calorimetry (DSC), X-ray Powder Diffraction (XRPD) and Scanning Electron Microscopy (SEM). Dissolution study was conducted in a non-sink condition to assess the drug release. RESULTS: Incorporation of a higher amount of hydrophilic component showed an improvement in formulating a fully amorphous system based on XRPD, yet the dissolution rate increment showed no significant difference from the lower. Hence, the degree of crystallinity is proven not to be the crucial factor contributing to dissolution rate improvement. The presence of a concomitant hydrophobic component, however, showed ability in resisting precipitation and sustaining supersaturation. CONCLUSION: Hydrophobicity in a binary carrier system plays an important role in achieving and maintaining the supersaturated state particularly for an amorphous solid dispersion. Graphical Abstract.


Assuntos
Antimaláricos/química , Atovaquona/química , Portadores de Fármacos/química , Polivinil/química , Povidona/química , Cristalização , Composição de Medicamentos , Liberação Controlada de Fármacos , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Cinética , Solubilidade , Solventes/química
18.
World Neurosurg ; 134: 6-9, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31622681

RESUMO

BACKGROUND: Recurrent acute subdural hematomas (ASDHs) are a common complication of neurosurgical operations. However, ASDHs associated with middle meningeal artery (MMA) injury are extremely rare. We encountered a rare case of recurrent ASDH due to MMA bleeding after craniotomy for a nontraumatic ASDH and successfully performed MMA embolization for treatment of it. CASE DESCRIPTION: A 56-year-old woman was admitted to our department with progressively worsening headache and vomiting approximately 1 week. She had no history of head trauma and illness. A head computed tomography (CT) scan revealed an ASDH on the right hemisphere. The patient underwent a right-sided craniotomy for evacuation of the hematoma. Two days later, she exhibited impaired consciousness and a repeat CT scan showed a recurrent ASDH. To clarify the cause, we performed cerebral digital subtraction angiography for the patient. Obvious contrast extravasation from the anterior branch of the right MMA was noticed. It was considered to be related to the recurrent ASDH. Embolization of the MMA was performed using Onyx 18 (Micro Therapeutics, Inc., Irvine, California, USA). Follow-up CT scans showed progressive resolution of the ASDH and no recurrence. The patient was discharged without any neurologic deficits. CONCLUSIONS: In our case, the relationship between the recurrent ASDH and MMA was observed via angiography and MMA embolization was successfully performed to avoid surgery for reevacuation, suggesting that active bleeding of MMA may be a cause of recurrent ASDH after neurosurgical operations and endovascular exploration, and possible treatment is necessary for an unexplained ASDH.


Assuntos
Embolização Terapêutica/métodos , Hematoma Subdural Agudo/terapia , Artérias Meníngeas/diagnóstico por imagem , Complicações Pós-Operatórias/terapia , Angiografia Digital , Angiografia Cerebral , Craniotomia , Drenagem , Combinação de Medicamentos , Feminino , Hematoma Subdural Agudo/diagnóstico por imagem , Humanos , Pessoa de Meia-Idade , Polivinil/uso terapêutico , Complicações Pós-Operatórias/diagnóstico por imagem , Recidiva , Tantálio/uso terapêutico , Tomografia Computadorizada por Raios X
19.
World Neurosurg ; 134: 62-66, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31669689

RESUMO

BACKGROUND: Spinal arteriovenous fistulas (AVFs) are a rare entity that can have devastating neurologic outcomes. Currently, these lesions are treated via open microsurgical resection or transarterial embolization with good success. However, some patients cannot be treated with a minimally invasive endovascular technique secondary to difficulty catheterizing their vascular anatomy. Our aim is to present a case of balloon-assisted Onyx embolization of a spinal AVF. CASE DESCRIPTION: We present the case of a 59-year-old male with progressive lower back pain with lower-extremity weakness. We performed a spinal angiogram where an AVF was identified with very torturous anatomy. The patient was originally treated with open microsurgical resection; however, ≈6 weeks later the fistula and symptoms returned. At that time, we were able to treat the lesion with the Scepter-C balloon. CONCLUSIONS: We present a challenging case in which normal embolization microcatheters were unable to navigate difficult anatomy, but we were able to gain access and obliterate the fistula by using a balloon catheter.


Assuntos
Oclusão com Balão/métodos , Malformações Vasculares do Sistema Nervoso Central/terapia , Dimetil Sulfóxido/uso terapêutico , Embolização Terapêutica/métodos , Polivinil/uso terapêutico , Humanos , Masculino , Pessoa de Meia-Idade
20.
Prostate ; 80(3): 241-246, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31825529

RESUMO

BACKGROUND: There are limited studies describing the detailed nonhistologic anatomy of the prostatic urethra. We studied radical prostatectomy specimens to describe the ex vivo anatomical details of its shape and size. METHODS: We conducted an observational study examining the prostatic urethra anatomy. Prostatic urethra casts (molds) were made using vinyl polysiloxane immediately after fresh specimens had been retrieved following prostatectomy for organ-confined prostate cancer. The following measurements were taken from the casts: anterior length, posterior length, maximal diameter, bladder neck to verumontanum, verumontanum to apex length, and prostate urethral angle (PUA). Prostate volume was calculated using the ellipsoid formula: ((p/6) × transverse × length × height). RESULTS: Thirty-three prostatic urethral casts were obtained. The mean prostate volume was 38.59 cc. The mean PUA was 127.6°. The mean transverse, apex, and length of the prostate were 4.65, 4.06, and 3.63 cm, respectively. The mean distance from the verumontanum to sphincter was 1.2 cm. The ratio between the anterior and posterior length of the prostatic urethra was 0.82 cm and did not correlate with prostatic size (Figure 8). CONCLUSION: The distance from the verumontanum to the apex does not change with prostate size; it is uniform with a mean length of 1.2 cm. The anterior length, posterior length, and maximum diameter of the prostatic urethra increase with prostate size. The mean difference between the anterior and posterior length is 0.8 cm and did not correlate with prostate size. Urethral angulation decreased with prostate size but was not significant. Information obtained from this study is of value designing prostatic stents and devices for benign prostatic hyperplasia.


Assuntos
Modelos Anatômicos , Polivinil , Próstata/anatomia & histologia , Siloxanas , Uretra/anatomia & histologia , Fatores Etários , Estudos de Coortes , Humanos , Masculino , Pessoa de Meia-Idade , Próstata/cirurgia , Prostatectomia
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