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OBJECTIVE: Our study aimed to evaluate the effect of soft tissue regeneration in nude mice using grafts made from the combination of adipocytes from fat tissue mesenchymal stem cells and fibrin gel from peripheral blood. MATERIALS AND METHODS: Mesenchymal stem cells were isolated from adipose tissue and identified according to ISCT criteria. The scaffold used was fibrin obtained from peripheral blood. The grafts in this study were generated by transferring mesenchymal stem cells onto a fibrin scaffold. Two types of grafts, the research sample (fibrin scaffold containing adipocytes differentiated from mesenchymal stem cells) and the control sample (fibrin scaffold only), were grafted under the dorsal skin of the same mouse. After each research period, samples were collected and evaluated by histological methods to observe the existence and growth of cells inside the grafts. RESULTS: The results showed that the study group's graft integrated better within the tissue when compared with the control group. In addition, the grafts in the study group showed the presence of cells with characteristic morphology of adipocytes one week after transplantation. In contrast, control samples showed dimorphous shapes and features mainly composed of non-homogenous fragments. CONCLUSIONS: These initial conclusions might be considered a first step in generating safe bio-compatible engineered grafts specifically usable in post-traumatic tissue regeneration procedures.
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Células Madre Mesenquimatosas , Ratones , Animales , Ratones Desnudos , Tejido Adiposo , Fibrina/farmacología , Modelos AnimalesRESUMEN
It is well known that water inside hydrophobic nano-channels diffuses faster than bulk water. Recent theoretical studies have shown that this enhancement depends on the size of the hydrophobic nanochannels. However, experimental evidence of this dependence is lacking. Here, by combining two-dimensional nuclear magnetic resonance diffusion-relaxation ( D - T 2 e f f ) spectroscopy in the stray field of a superconducting magnet and molecular dynamics simulations, we analyze the size dependence of water dynamics inside Carbon Nanotubes (CNTs) of different diameters ( 1.1 - 6.0 nm), in the temperature range of 265 - 305 K. Depending on the CNT diameter, the nanotube water is shown to resolve in two or more tubular components acquiring different self-diffusion coefficients. Most notably, a favorable CNT diameter range ( 3.0 - 4.5 nm) is experimentally verified for the first time, in which water molecule dynamics at the center of the CNTs exhibits distinctly non-Arrhenius behavior, characterized by ultrafast diffusion and extraordinary fragility, a result of significant importance in the efforts to understand water behavior in hydrophobic nanochannels.
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This pilot study aimed at investigating if implants without primary stability may osseointegrate and support functional prosthesis. Patients received one Trabecular Metal implant each in posterior sockets two months after tooth extraction, combined with xenograft and a resorbable membrane. Implants were divided in three groups, based on the primary stability assessed by resonance frequency analysis. Implant stability quotient (ISQ) was measured at placement, and re-assessed five months later (at uncovering), and after 6 months of function. Marginal bone loss was radiographically evaluated. After checking normality of the distributions, Student's t-test was used for statistical comparisons. Twenty-five consecutive patients were included. At placement, mean ISQ significantly differed among groups, being undetectable (n=8 implants), 65.00±4.25 (standard deviation, n=6) and 77.95±3.13 (n=11) in the very low, medium and good primary stability groups, respectively. After five months of healing, mean ISQ had increased to >70 in all groups. All implants successfully osseointegrated and were restored as planned. Six months after loading, no significant difference in mean ISQ (range 79.19-81.92), and in mean marginal bone level change (range 0.21 to 0.28 mm) was observed among the three groups. Rehabilitation of wide postextraction defects may achieve successful outcomes even in the absence of primary stability.
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Implantes Dentales , Oseointegración , Extracción Dental , Humanos , Proyectos Piloto , Cicatrización de HeridasRESUMEN
AIMS: To evaluate the real-time bone temperature changes during the preparation of the implant bed with a single-drill protocol with different drill designs and different slow drilling speeds in artificial type IV bone. MATERIALS AND METHODS: For this experimental in vitro study, 600 implant bed preparations were performed in 10 bovine bone disks using three test slow drilling speeds (50/150/300 rpm) and a control drilling speed (1200 rpm). The temperature at crestal and apical areas and time variations produced during drilling with three different drill designs with similar diameter and length but different geometry were recorded with real-life thermographic analysis. Statistical analysis was performed by two-way analysis of variance. Multiple comparisons of temperatures and time with the different drill designs and speeds were performed with the Tukey's test. RESULTS: T Max values for the control drilling speed with all the drill designs (D1 + 1200; D2 + 1200; D3 + 1200) were higher compared to those for the controls for 11 ± 1.32 °C (p < 0.05). The comparison of T Max within the test groups showed that drilling at 50 rpm resulted in the lowest temperature increment (22.11 ± 0.8 °C) compared to the other slow drilling speeds of 150 (24.752 ± 1.1 °C) and 300 rpm (25.977 ± 1.2 °C) (p < 0.042). Temperature behavior at crestal and apical areas was similar being lower for slow drilling speeds compared to that for the control drilling speed. Slow drilling speeds required significantly more time to finish the preparation of the implant bed shown as follows: 50 rpm > 150 rpm > 300 rpm > control (p < 0.05). CONCLUSIONS: A single-drill protocol with slow drilling speeds (50, 150, and 300 rpm) without irrigation in type IV bone increases the temperature at the coronal and apical levels but is below the critical threshold of 47 °C. The drill design in single-drill protocols using slow speeds (50, 150, and 300 rpm) does not have an influence on the thermal variations. The time to accomplish the implant bed preparation with a single-drill protocol in type IV bone is influenced by the drilling speed and not by the drill design. As the speed decreases, then more time is required.
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Implantación Dental Endoósea/instrumentación , Implantación Dental Endoósea/métodos , Instrumentos Dentales , Animales , Bovinos , Diseño de Equipo , Calor , Técnicas In Vitro , Propiedades de Superficie , Termografía/métodosRESUMEN
There are no studies that have systematically reviewed the influence of involuntary cigarette smoke inhalation (ICSI) on the stability of implants. The aim of the present study was to perform a systematic review and meta-analysis of preclinical studies that assessed the influence of involuntary cigarette smoke inhalation ICSI on osseointegration. Indexed databases (PubMed, Google-Scholar, Scopus, EMBASE, and Web of Knowledge) were searched till September 2017. Titles and abstracts of studies identified using the above-described protocol were independently screened by 2 authors. Full-texts of studies judged by title and abstract to be relevant were independently evaluated for the stated eligibility criteria. Nine studies were included. Six studies showed that ICSI compromised bone area contact around implants. In 4 studies, peri-implant bone mineral density was significantly higher in the control group than among subjects exposed to ICSI. For the effects of ICSI on the osseointegration of dental implants, significant differences could be observed for bone-to-implant contact for test subjects in cancellous (Z=-4.08, p<0.001) and cortical bone (Z=-4.31, p<0.001) respectively. ICSI may negatively influence osseointegration of dental implants. It is imperative to educate patients about the negative effects of passive smoking on dental and systemic health.
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Implantes Dentales , Oseointegración/fisiología , Contaminación por Humo de Tabaco/efectos adversos , Animales , Densidad Ósea , Implantes Experimentales , RatasRESUMEN
The objective of this study was to assess the oral Candida carriage and species prevalence in denture stomatitis (DS) patients with and without diabetes mellitus (DM). To address the focused question "In patients receiving dentures, how does having diabetes compared to no diabetes influences the carriage and species prevalence of oral Candida?" Indexed databases were explored without time or language restrictions up to and including February 2017. Nine studies were included. In these studies, the number of diabetics ranged between 14 patients and 405 individuals with mean ages ranging between 33 years and 66.4 years. In five studies, the percentage of hyperglycemic patients in the diabetic group ranged from 14.3% to 100%. In one study, all diabetic patients were normoglycemic. Seven studies reported Candida-associated DS to be significantly higher among diabetics than non-diabetics. Candida albicans was the most prevalent species isolated among diabetics and non-diabetics with DS. Denture-wearers with DM are more susceptible to Candida-associated DS as compared to non-diabetics.
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Candida albicans , Candidiasis/microbiología , Diabetes Mellitus/microbiología , Estomatitis Subprotética/microbiología , HumanosRESUMEN
There is controversy regarding whether locally delivered alendronate enhances osseointegration. The aim of this systematic review was to assess the role of local alendronate delivery (topical, or as a coating on implant surfaces) in the osseointegration of implants. The focused question was, "Does the local delivery of alendronate affect osseointegration around implants?". To address this question, indexed databases were searched, without time or language restriction, up to and including January 2017. Various combinations of the following key words were used: "alendronate", "bisphosphonates", "osseointegration", and "topical administration". letters to the editor, historic reviews, commentaries, case series, and case reports were excluded. In total, 18 experimental studies were included: alendronate-coated implants were used in 13 of these studies and local delivery in five studies. The results of 11 of the studies showed that alendronate coating increased new bone formation, the bone volume fraction, or bone-to-implant contact (BIC) and biomechanical properties. Results from two studies in which alendronate was administered topically indicated impaired BIC and/or biomechanical fixation around implants. On experimental grounds, local alendronate delivery seems to promote osseointegration. From a clinical perspective, the results in animal models support phase 1 studies in healthy humans (without co-morbidities other than edentulism).
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Alendronato/administración & dosificación , Implantación Dental Endoósea , Implantes Dentales , Difosfonatos/administración & dosificación , Oseointegración/efectos de los fármacos , Administración Tópica , HumanosRESUMEN
The purpose of the present study was to review systematically the association between periodontal diseases (PDs) and polycystic ovary syndrome (PCOS). To address the focused question, 'Is there a relationship between PD and PCOS?' indexed databases were searched up to October 2016 without time or language restrictions using different combinations of the following key words: PCOS, ovarian cysts, PD, periodontitis, gingival diseases and gingivitis. Letters to the Editor, commentaries, historic reviews, case-report, unpublished articles and animal/experimental studies were excluded. Seven case-control studies were included. The number of study participants ranged between 52 and 196 females aged between 15 and 45 years. In three and three studies, proinflammatory cytokines were assessed in gingival crevicular fluid and saliva samples, respectively. In one study, salivary microbes were investigated. All studies reported that a positive association exists between PD and PCOS. In conclusion, there is a positive association between PD and PCOS; however, further well-designed longitudinal controlled clinical trials are needed in this regard. It is recommended that physicians should refer patients with PCOS to oral health-care providers for comprehensive oral evaluation and treatment.
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Enfermedades Periodontales/complicaciones , Síndrome del Ovario Poliquístico/complicaciones , Femenino , Humanos , Enfermedades Periodontales/inmunología , Enfermedades Periodontales/microbiología , Síndrome del Ovario Poliquístico/inmunología , Síndrome del Ovario Poliquístico/microbiologíaRESUMEN
With the increasing use of low level laser therapy (LLLT) in clinical dentistry, the aim of the present study was to assess the effectiveness of diode lasers in the management of orofacial pain. Indexed databases were searched without language and time restrictions up to and including July 2016 using different combinations of the following key words: oral, low level laser therapy, dental, pain, diode lasers, discomfort and analgesia. From the literature reviewed it is evident that LLLT is effective compared to traditional procedures in the management of oro-facial pain associated to soft tissue and hard tissue conditions such as premalignant lesions, gingival conditions and dental extractions. However, it remains to be determined which particular wavelength will produce the more favorable and predictable outcome in terms of pain reduction. It is highly recommended that further randomized control trials with well-defined control groups should be performed to determine the precise wavelengths of the diode lasers for the management of oro-facial pain. Within the limits of the present review, it is concluded that diode lasers therapy is more effective in the management of oro-facial pain compared to traditional procedures.
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Dolor Facial/radioterapia , Láseres de Semiconductores/uso terapéutico , Terapia por Luz de Baja Intensidad/instrumentación , Manejo del Dolor/métodos , Dolor Facial/etiología , Dolor Facial/fisiopatología , Humanos , Terapia por Luz de Baja Intensidad/métodos , Procedimientos Quirúrgicos Orales/efectos adversos , Manejo del Dolor/instrumentaciónRESUMEN
E-cigarette-derived inhaled nicotine may contribute to the pathogenesis of periodontal and pulmonary diseases in particular via lung inflammation, injurious, and dysregulated repair responses. Nicotine is shown to have antiproliferative properties and affects fibroblasts in vitro, which may interfere in tissue myofibroblast differentiation in e-cig users. This will affect the ability to heal wounds by decreasing wound contraction. In periodontics, direct exposure to e-vapor has been shown to produce harmful effects in periodontal ligament and gingival fibroblasts in culture. This is due to the generation of reactive oxygen species/aldehydes/carbonyls from e-cig aerosol, leading to protein carbonylation of extracellular matrix and DNA adducts/damage. A limited number of studies regarding the effects of e-cig in oral and lung health are available. However, no reports are available to directly link the deleterious effects on e-cigs, inhaled nicotine, and flavorings aerosol on periodontal and pulmonary health in particular to identify the risk of oral diseases by e-cigarettes and nicotine aerosols. This mini-review summarizes the recent perspectives on e-cigarettes including inhaled nicotine effects on several pathophysiological events, such as oxidative stress, DNA damage, innate host response, inflammation, cellular senescence, profibrogenic and dysregulated repair, leading to lung remodeling, oral submucous fibrosis, and periodontal diseases.
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Aerosoles/farmacología , Nicotina/farmacología , Sistema Respiratorio/efectos de los fármacos , Administración por Inhalación , Aerosoles/efectos adversos , Remodelación de las Vías Aéreas (Respiratorias)/efectos de los fármacos , Animales , Senescencia Celular/efectos de los fármacos , Daño del ADN/efectos de los fármacos , Sistemas Electrónicos de Liberación de Nicotina , Humanos , Nicotina/efectos adversos , Fibrosis de la Submucosa Bucal/inducido químicamente , Estrés Oxidativo/efectos de los fármacos , Enfermedades Periodontales/inducido químicamenteRESUMEN
OBJECTIVE: To assess self-perceived oral health and whole salivary immunoglobulin G (IgG) levels among habitual gutka-chewers and nonchewers (controls). MATERIALS AND METHODS: Fifty gutka-chewers and fifty controls were included. Demographic data and self-perceived oral health status (pain in teeth, pain on chewing, bleeding gums (BG), bad breath, loose teeth and daily oral hygiene protocols) were collected using a questionnaire. Unstimulated whole saliva (UWS) was collected and unstimulated whole salivary flow rate (UWSFR) was determined. Whole salivary IgG levels were determined using standard techniques. Odds ratios were calculated for oral symptoms and group differences in protein levels were compared using one-way analysis of variance (α± <5%). RESULTS: BG was more often reported by gutka-chewers than controls (P < 0.05). There was no significant difference in UWSFR and self-perceived pain in teeth, pain on chewing, bad breath and loose teeth among gutka-chewers and controls. IgG levels were significantly higher among gutka-chewers than controls (P < 0.01). Among gutka-chewers, whole salivary IgG levels were comparable individuals with and without self-perceived oral symptoms. Among controls, IgG levels in UWS were significantly higher among individuals who had BG than those who did not (P < 0.05). CONCLUSIONS: Self-perceived oral health is worse and whole salivary IgG levels are higher in gutka-chewers compared to controls.
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Areca/efectos adversos , Inmunoglobulina G/metabolismo , Salud Bucal , Saliva/inmunología , Tabaco sin Humo/efectos adversos , Adulto , Pérdida de Hueso Alveolar/complicaciones , Estudios de Casos y Controles , Femenino , Humanos , Masculino , Masticación , Saliva/metabolismo , Encuestas y CuestionariosRESUMEN
AIM: The aim of this experimental in vitro study was to evaluate the effects of the piezoelectric device in temperature and time variations in standardized osteotomies performed with similar tip inserts in bovine bone blocks. METHODS: Two different piezosurgical devices were used the OE-F15(®) (Osada Inc., Los Angeles, California, USA) and the Surgybone(®) (Silfradent Inc., Sofia, Forli Cesena, Italy). Serrated inserts with similar geometry were coupled with each device (ST94 insert/test A and P0700 insert/test B). Osteotomies 10 mm long and 3 mm deep were performed in bone blocks resembling type II (dense) and type IV (soft) bone densities with and without irrigation. Thermal changes and time variations were recorded. The effects of bone density, irrigation, and device on temperature changes and time necessary to accomplish the osteotomies were analyzed. RESULTS: Thermal analysis showed significant higher temperatures during piezosurgery osteotomies in hard bone without irrigation (P < 0.05). The type of piezosurgical device did not influence thermal variations (P > 0.05). Time analysis showed that the mean time values necessary to perform osteotomies were shorter in soft bone than in dense bone (P < 0.05). CONCLUSIONS: Within the limitations of this in vitro study, it may be concluded that the temperature increases more in piezosurgery osteotomies in dense bone without irrigation; the time to perform the osteotomy with piezosurgery is shorter in soft bone compared to hard bone; and the piezosurgical device have a minimal influence in the temperature and time variations when a similar tip design is used during piezosurgery osteotomies.
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Osteotomía/métodos , Piezocirugía/métodos , Animales , Huesos/cirugía , Bovinos , Técnicas In Vitro , Tempo Operativo , Osteotomía/instrumentación , Piezocirugía/instrumentación , Temperatura , Factores de TiempoRESUMEN
OBJECTIVE: The aim was to compare the periodontal inflammatory conditions among habitual gutka chewers and betel quid (BQ) chewers. MATERIAL AND METHODS: Forty-five gutka chewers, 45 BQ chewers and 50 non-chewers (controls) were included. Demographic data regarding age, gender, duration, and frequency of gutka- and BQ-chewing habits and gingival bleeding were collected using a questionnaire. Clinical periodontal parameters [plaque index (PI), bleeding on probing (BOP), probing depth (PD) and clinical attachment loss (AL)] were recorded. Marginal bone loss (MBL) was measured on digital panoramic radiographs. Group differences in periodontal inflammatory parameters were tested using univariate and multivariable analyses (α < 5%). RESULTS: Periodontal inflammatory parameters [PI, BOP, PD (4-6 and >6 mm), clinical AL and MBL] were significantly high in gutka and BQ chewers than controls. There was no significant difference in periodontal inflammatory parameters among gutka and BQ chewers. The odds for gingival bleeding were six times and 13 times higher in gutka and BQ chewers, respectively, compared to controls. Comparison of gutka and BQ chewers did not significantly increase the odds of gingival bleeding. CONCLUSION: Periodontal inflammatory conditions were comparable among habitual gutka and BQ chewers; which suggests that gutka chewers and BQ chewers are equally susceptible to periodontal disease.
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Areca/efectos adversos , Enfermedades de las Encías/etiología , Enfermedades Periodontales/etiología , Uso de Tabaco/efectos adversos , Tabaco sin Humo/efectos adversos , Adulto , Femenino , Enfermedades de las Encías/patología , Humanos , Masculino , Masticación , Enfermedades Periodontales/patologíaRESUMEN
We report the rational design and synthesis of DAB poly(propylene imine) dendrimer (DAB) intercalated graphite oxide (GO) hybrids with tailorable interlayer distances. The amine groups originating from the intercalated dendrimer molecules cross-link adjacent GO sheets and strongly favour CO2 adsorption under wet flue gas conditions.
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The aim was to assess the role of platform switching (PS) in minimising crestal bone loss around dental implants through a systematic review of the currently available clinical evidence. To address the focused question 'Does PS minimise crestal bone loss compared with non-platform-switched (NPS) implants?', PubMed/Medline and Google Scholar databases were explored from 1986 up to and including December 2013 using the following key words in different combinations: 'bone loss', 'dental implant', 'diameter', 'mandible', 'maxilla' and 'platform switching'. Letters to the Editor, unpublished data, historical reviews, case reports and articles published in languages other than English were excluded. Fifteen clinical studies were included. In seven studies, PS and NPS implants were placed in both the maxilla and mandible. In 13 studies, implants were placed at crestal bone levels whereas in one study, implants were placed supracrestally. Three studies reported the bucco-lingual (or transversal) width of the alveolar ridge which ranged between 7-8 mm. Seven studies reported that implants placed according to the PS concept did not minimise crestal bone loss as compared with NPS implants. 3D-Implant positioning, width of alveolar ridge and control of micromotion at the implant-abutment interface are the more critical factors that influence crestal bone levels than PS.
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Pérdida de Hueso Alveolar/etiología , Pilares Dentales/efectos adversos , Implantación Dental Endoósea/efectos adversos , Implantes Dentales/efectos adversos , Diseño de Prótesis Dental/efectos adversos , Proceso Alveolar/cirugía , Implantación Dental Endoósea/métodos , Fracaso de la Restauración Dental , Humanos , Mandíbula/cirugía , Maxilar/cirugía , Resultado del TratamientoRESUMEN
Oestrogen is mainly responsible for alterations in blood vessels and progesterone stimulates the production of inflammatory mediators. In females, during puberty, ovulation and pregnancy, there is an increase in the production of sex steroid hormones, which results in increased gingival inflammation, characterized by gingival enlargement, increased bleeding and crevicular fluid flow. This article presents a case of a patient who presented with a complaint of gingival swelling and spontaneous bleeding that persisted for more than two months. Her health history documented the recently diagnosed presence of polycystic ovarian syndrome. Clinical examination revealed enlarged painful gingival tissues, which bled when touched. After completion of Phase I therapy, the enlargement did not subside and a biopsy sample was taken. This was compared with another patient who had the same health condition but did not show any gingival enlargement. Testing of tissue samples for oestrogen and progesterone receptors showed the first patient to be positive for oestrogen receptors but negative for progesterone, whereas the control was negative for both. Positive oestrogen receptors suggest that polycystic ovarian syndrome has some effect on the periodontium. The dental consequences of this condition, highly prevalent among young females, are typically ignored. Further studies warrant establishment of a clinical association and future diagnosis.
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Encía/química , Síndrome del Ovario Poliquístico/metabolismo , Receptores de Estrógenos/análisis , Receptores de Progesterona/análisis , Estudios de Casos y Controles , Femenino , Hemorragia Gingival/etiología , Sobrecrecimiento Gingival/etiología , Gingivitis/etiología , Humanos , Adulto JovenRESUMEN
Ca alginate polymer fibers were developed to effectively disperse and stabilize an efficient photocatalyst such as AEROXIDE(®) TiO(2) P25 in their matrix. The biopolymer/TiO(2) fibers were prepared and tested either in the hydrogel non-porous form or in the highly porous aerogel form prepared by sc-CO(2) drying. Batch photocatalytic experiments showed that the porous, Ca alginate/TiO(2) fibers, exhibited high efficiency for the removal of methyl orange (MO) from polluted water. In addition, their high porosity and surface area led to high MO degradation rate which was faster than that observed not only for their non-porous analogs but also of the bulk P25 TiO(2) powder. Specifically, 90% removal for 20 µM MO was achieved within 220 min for the porous sc-CO(2) dried fibers while for their non-porous analogs at 325 min. The corresponding value (at 60 µM MO) for the porous sc-CO(2) dried fibers was 140 min over 240 min for the AEROXIDE(®) TiO(2) P25 as documented in the literature. Furthermore the composite alginate/photocatalyst porous fibers were combined with TiO(2) membranes in a continuous flow, hybrid photocatalytic/ultrafiltration water treatment process that led to a three fold enhancement of the MO removal efficiency at 400 ml of 20 µM MO total treated volume and to dilution rather than condensation in the membrane retentate as commonly observed in filtration processes. Furthermore the permeability of the photocatalytic membrane was enhanced in the presence of the fibers by almost 20%. This performance is achieved with 26 cm(2) and 31 cm(2) of membrane and stabilized photocatalyst surfaces respectively and in this context there is plenty of room for the up-scaling of both membranes and fibers and the achievement of much higher water yields since the methods applied for the development of the involved materials (CVD and dry-wet phase inversion in a spinning set-up) are easily up-scalable and are not expected to add significant cost to the proposed water treatment process.
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Alginatos/química , Fotoquímica/métodos , Ultrafiltración/métodos , Purificación del Agua/métodos , Adsorción/efectos de la radiación , Compuestos Azo/química , Carbono/análisis , Catálisis/efectos de la radiación , Gases/análisis , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Cinética , Membranas Artificiales , Nanopartículas del Metal/ultraestructura , Permeabilidad/efectos de la radiación , Porosidad/efectos de la radiación , Espectrometría Raman , Propiedades de Superficie/efectos de la radiación , Temperatura , Titanio/química , Rayos Ultravioleta , Agua/química , Contaminantes Químicos del Agua/aislamiento & purificaciónRESUMEN
A chemical vapour deposition (CVD) based innovative approach was applied with the purpose to develop composite TiO(2) photocatalytic nanofiltration (NF) membranes. The method involved pyrolytic decomposition of titanium tetraisopropoxide (TTIP) vapor and formation of TiO(2) nanoparticles through homogeneous gas phase reactions and aggregation of the produced intermediate species. The grown nanoparticles diffused and deposited on the surface of γ-alumina NF membrane tubes. The CVD reactor allowed for online monitoring of the carrier gas permeability during the treatment, providing a first insight on the pore efficiency and thickness of the formed photocatalytic layers. In addition, the thin TiO(2) deposits were developed on both membrane sides without sacrificing the high yield rates. Important innovation was also introduced in what concerns the photocatalytic performance evaluation. The membrane efficiency to photo degrade typical water pollutants, was evaluated in a continuous flow water purification device, applying UV irradiation on both membrane sides. The developed composite NF membranes were highly efficient in the decomposition of methyl orange exhibiting low adsorption-fouling tendency and high water permeability.
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Filtración/instrumentación , Membranas Artificiales , Titanio/química , Contaminantes Químicos del Agua/química , Purificación del Agua/instrumentación , Óxido de Aluminio/química , Compuestos Azo/química , Compuestos Azo/efectos de la radiación , Catálisis , Colorantes/química , Colorantes/efectos de la radiación , Fotólisis , Rayos Ultravioleta , Contaminantes Químicos del Agua/efectos de la radiación , Purificación del Agua/métodosRESUMEN
Palladium is usually supported on porous materials in the form of nanoparticles. The hydrogen storage capacity of such a system is usually much higher than the separated capacity of the metal (approximately 0.7 H/Pd) and the support. Pd nanoparticles provide a source of hydrogen atoms by dissociation. The atomic hydrogen spills over from the Pd structure to the support via surface diffusion and this phenomenon is known as hydrogen spillover. In this study commercial SWNTs were dispersed in PEG 200 solution. Then the precursor PdCl2 in PEG 200 was added and the whole left to react under stirring with reflux at 200 degrees C for 1 h. Succeeding washings with ethanol and centrifugation followed for several times and finally the sample was dried at 60 degrees C. Through this procedure a 3 wt% Pd loading was achieved whereas the TEM derived nanoparticle size distribution indicated a 50% percentage of Pd nanoparticles with diameter less than 8 nm. Hydrogen isotherms up to 2 MPa were carried out with the gravimetric method. The defined storage capacity of 1.2 wt% at 0.2 MPa was quite satisfactory. However, a 0.2 wt% portion of this storage capacity was attributed to the formation of water molecules through reaction of H atoms with the dissociatively adsorbed oxygen atoms on the Pd nanoparticles. This conclusion was educed from a series of thermal desorption experiments following the H2 adsorption/desorption cycles and regeneration. Through this set of experiments several other important parameters were defined as the temperature for complete hydrogen desorption and the optimum conditions for PEG removal.
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The mechanism of heavy metal ion removal in processes involving multi-layered tubular ultrafiltration and nanofiltration (UF/NF) membranes was investigated by conducting retention experiments in both flow-through and cross-flow modes. The prospect of the regeneration of the membranes through an acidic process was also examined and discussed. The UF/NF membranes were functionalised with alginates to develop hybrid inorganic/organic materials for continuous, single pass, wastewater treatment applications. The challenge laid in the induction of additional metal adsorption and improved regeneration capacity. This was accomplished by stabilizing alginates either into the pores or on the top-separating layer of the membrane. The preservation of efficient water fluxes at moderate trans-membrane pressures introduced an additional parameter that was pursued in parallel to the membrane modification process. The deposition and stabilization of alginates was carried out via physical (filtration/cross-linking) and chemical (grafting) procedures. The materials developed by means of the filtration process exhibited a 25-60% enhancement of their Cd(2+) binding capacity, depending on the amount of the filtered alginate solution. The grafting process led to the development of alginate layers with adequate stability under acidic regeneration conditions and metal retention enhancement of 25-180%, depending on the silane involved as grafting agent and the solvent of silanisation.