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1.
ACS Appl Mater Interfaces ; 13(13): 15925-15938, 2021 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-33755427

RESUMO

Evaporation is a ubiquitous and complex phenomenon of importance to many natural and industrial systems. Evaporation occurs when molecules near the free interface overcome intermolecular attractions with the bulk liquid. As molecules escape the liquid phase, heat is removed, causing evaporative cooling. The influence of evaporative cooling on inducing a temperature difference with the surrounding atmosphere as well as within the liquid is poorly understood. Here, we develop a technique to overcome past difficulties encountered during the study of heterogeneous droplet evaporation by coupling a piezo-driven droplet generation mechanism to a controlled micro-thermocouple to probe microdroplet evaporation. The technique allowed us to probe the gas-phase temperature distribution using a micro-thermocouple (50 µm) in the vicinity of the liquid-vapor interface with high spatial (±10 µm) and temporal (±100 ms) resolution. We experimentally map the temperature gradient formed surrounding sessile water droplets having varying curvature dictated by the apparent advancing contact angle (100° ≲ θ ≲ 165°). The experiments were carried out at temperatures below and above ambient for a range of fixed droplet radii (130 µm ≲ R ≲ 330 µm). Our results provide a primary validation of the centuries-old theoretical framework underpinning heterogeneous droplet evaporation mediated by the working fluid, substrate, and gas thermophysical properties, droplet apparent contact angle, and droplet size. We show that microscale droplets residing on low-thermal-conductivity substrates such as glass absorb up to 8× more heat from the surrounding gas compared to droplets residing on high-thermal-conductivity substrates such as copper. Our work not only develops an experimental understanding of the heat transfer mechanisms governing droplet evaporation but also presents a powerful platform for the study and characterization of liquid-vapor transport at curved interfaces wetting and nonwetting advanced functional surfaces.

2.
Turk J Med Sci ; 50(1): 248-257, 2020 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-31769639

RESUMO

Background/aim: Caffeic acid phenethyl ester (CAPE) and Ankaferd Blood Stopper (ABS) are considered to contribute to wound healing. The purpose of this study was to investigate the effect of ABS and CAPE on secondary wound healing of oral mucosal tissue. Materials and methods: In total, 63 male Sprague-Dawley rats were used in this study. The animals were randomly divided into three groups and anaesthetized with ketamine (8 mg/100 g, intraperitoneally): a control group, CAPE group, and ABS group. A full-thickness excisional wound was created using a 4 mm punch biopsy tool. Topical ABS and CAPE were then applied in each group for 7, 14, and 21 days (n = 7 in each group). The animals in each group were sacrificed after 7, 14, and 21 days. Palatal specimens were stained with haematoxylin-eosin. Vascular endothelial growth factor (VEGF) and tumour necrosis factor-inducible gene 6 (TSG-6) protein expressions were determined using the Western blot method. Results: Inflammation, vessel dilatation, and haemorrhages were significantly lower in the CAPE group as compared with these parameters in the other groups (P < 0.05). Fibrosis was significantly higher in the ABS group as compared with that in the other groups (P < 0.05). VEGF protein levels were elevated in the 21-day CAPE group and 7-day ABS group. The expression of TSG-6 increased in the 7-day CAPE group and 21-day ABS group. Conclusion: Based on our findings, ABS and CAPE had positive effects on the oral wound healing process.


Assuntos
Ácidos Cafeicos/farmacologia , Mucosa Bucal/efeitos dos fármacos , Mucosa Bucal/lesões , Álcool Feniletílico/análogos & derivados , Extratos Vegetais/farmacologia , Cicatrização/efeitos dos fármacos , Animais , Esquema de Medicação , Expressão Gênica/efeitos dos fármacos , Masculino , Álcool Feniletílico/farmacologia , Ratos , Ratos Sprague-Dawley , Fator A de Crescimento do Endotélio Vascular/genética
3.
J Appl Oral Sci ; 26: e20170004, 2018 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-29364337

RESUMO

Among the many graft materials that have been used for the treatment of bone defects in oral and maxillofacial regions is xenograft. To improve osteoconductive effects of xenografts, they have been combined with various biocompatible materials, such as hyaluronic acid and bone morphogenetic protein. To determine bone-healing capacity of high molecular weight hyaluronic acid (HA) combined with xenograft in rabbit calvarial bone defects. Ten adult male New Zealand rabbits (mean weight 3 kg) were included in the study. Three 6-mm-diameter bicortical cranial defects were created on calvarial bone of all rabbits. These defects were filled as follows: a) xenograft; b) HA+xenograft; c) autograft. One month after the first operation, rabbits were sacrificed. Specimens were evaluated histomorphometrically. Considering multiple comparisons, differences regarding new bone were statistically significant between all groups (p<0.05). The volume of residual graft was significantly decreased in HA group compared to xenograft group (p=0.035). Marrow space, trabecular thickness (TbTh), trabecular width (TbWi), trabecular separation (TbSp), and number of node: number of terminus (NNd:NTm) in the autograft group were significantly better than xenograft and HA groups (p<0.05). However, regarding marrow space, TbTh, TbWi, TbSp, and NNd:NTm values, xenograft and HA groups showed similar results and the difference were not significant (p>0.05). These results support that high molecular weight hyaluronic acid could contribute to the healing of xenograft by improving the percentage of new bone formation and reducing the percentage of residual graft. However, HA did not significantly affect the quality of newly formed bone assessed by microarchitectural parameters.


Assuntos
Regeneração Óssea/efeitos dos fármacos , Xenoenxertos/efeitos dos fármacos , Ácido Hialurônico/farmacologia , Crânio/transplante , Cicatrização/efeitos dos fármacos , Animais , Autoenxertos/efeitos dos fármacos , Materiais Biocompatíveis/farmacologia , Transplante Ósseo/métodos , Osso Esponjoso/efeitos dos fármacos , Modelos Animais de Doenças , Humanos , Ácido Hialurônico/química , Masculino , Peso Molecular , Coelhos , Reprodutibilidade dos Testes , Crânio/efeitos dos fármacos , Resultado do Tratamento
4.
J. appl. oral sci ; 26: e20170004, 2018. tab, graf
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-893706

RESUMO

ABSTRACT Among the many graft materials that have been used for the treatment of bone defects in oral and maxillofacial regions is xenograft. To improve osteoconductive effects of xenografts, they have been combined with various biocompatible materials, such as hyaluronic acid and bone morphogenetic protein. Objective: To determine bone-healing capacity of high molecular weight hyaluronic acid (HA) combined with xenograft in rabbit calvarial bone defects. Material and methods: Ten adult male New Zealand rabbits (mean weight 3 kg) were included in the study. Three 6-mm-diameter bicortical cranial defects were created on calvarial bone of all rabbits. These defects were filled as follows: a) xenograft; b) HA+xenograft; c) autograft. One month after the first operation, rabbits were sacrificed. Specimens were evaluated histomorphometrically. Results: Considering multiple comparisons, differences regarding new bone were statistically significant between all groups (p<0.05). The volume of residual graft was significantly decreased in HA group compared to xenograft group (p=0.035). Marrow space, trabecular thickness (TbTh), trabecular width (TbWi), trabecular separation (TbSp), and number of node: number of terminus (NNd:NTm) in the autograft group were significantly better than xenograft and HA groups (p<0.05). However, regarding marrow space, TbTh, TbWi, TbSp, and NNd:NTm values, xenograft and HA groups showed similar results and the difference were not significant (p>0.05). Conclusion: These results support that high molecular weight hyaluronic acid could contribute to the healing of xenograft by improving the percentage of new bone formation and reducing the percentage of residual graft. However, HA did not significantly affect the quality of newly formed bone assessed by microarchitectural parameters.


Assuntos
Humanos , Animais , Masculino , Crânio/transplante , Cicatrização/efeitos dos fármacos , Regeneração Óssea/efeitos dos fármacos , Xenoenxertos/efeitos dos fármacos , Ácido Hialurônico/farmacologia , Coelhos , Crânio/efeitos dos fármacos , Materiais Biocompatíveis/farmacologia , Reprodutibilidade dos Testes , Transplante Ósseo/métodos , Resultado do Tratamento , Modelos Animais de Doenças , Autoenxertos/efeitos dos fármacos , Osso Esponjoso/efeitos dos fármacos , Ácido Hialurônico/química , Peso Molecular
5.
Med. oral patol. oral cir. bucal (Internet) ; 20(3): 340-346, mayo 2015. ilus, tab
Artigo em Inglês | IBECS | ID: ibc-139050

RESUMO

BACKGROUND: This study aimed to review the results related to head and jaw disorders in cases of ectodermal dysplasia. The evaluation of ectodermal dysplasia cases was made by clinical examination and examination of the jaw and facial areas radiologically and on cone-beam 3-dimensional dental tomography (CBCT) images. MATERIAL AND METHODS: In the 36 cases evaluated in the study, typical clinical findings of pure hypohidrotic ectodermal displasia (HED) were seen, such as missing teeth, dry skin, hair and nail disorders. CBCT images were obtained from 12 of the 36 cases, aged 1.5- 45 years, and orthodontic analyses were made on these images. RESULTS: The clinical and radiological evaluations determined, hypodontia or oligodontia, breathing problems, sweating problems, a history of fever, sparse hair, saddle nose, skin peeling, hypopigmentation, hyperpigmentation, finger and nail deformities, conical teeth anomalies, abnormal tooth root formation, tooth resorption in the root, gingivitis, history of epilepsy, absent lachrymal canals and vision problems in the cases which included to the study. CONCLUSIONS: Ectodermal dysplasia cases have a particular place in dentistry and require a professional, multi-disciplinary approach in respect of the chewing function, orthognathic problems, growth, oral and dental health. It has been understood that with data obtained from modern technologies such as three-dimensional dental tomography and the treatments applied, the quality of life of these cases can be improved (AU)


Assuntos
Humanos , Displasia Ectodérmica , Anormalidades da Boca , Imageamento Tridimensional , Tomografia Computadorizada por Raios X/métodos , Processo Alveolar/anormalidades , Diagnóstico Precoce , Estudos Retrospectivos
6.
Med Oral Patol Oral Cir Bucal ; 20(3): e340-6, 2015 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-25662550

RESUMO

BACKGROUND: This study aimed to review the results related to head and jaw disorders in cases of ectodermal dysplasia. The evaluation of ectodermal dysplasia cases was made by clinical examination and examination of the jaw and facial areas radiologically and on cone-beam 3-dimensional dental tomography (CBCT) images. MATERIAL AND METHODS: In the 36 cases evaluated in the study, typical clinical findings of pure hypohidrotic ectodermal displasia (HED) were seen, such as missing teeth, dry skin, hair and nail disorders. CBCT images were obtained from 12 of the 36 cases, aged 1.5- 45 years, and orthodontic analyses were made on these images. RESULTS: The clinical and radiological evaluations determined, hypodontia or oligodontia, breathing problems, sweating problems, a history of fever, sparse hair, saddle nose, skin peeling, hypopigmentation, hyperpigmentation, finger and nail deformities, conical teeth anomalies, abnormal tooth root formation, tooth resorption in the root, gingivitis, history of epilepsy, absent lachrymal canals and vision problems in the cases which included to the study. CONCLUSIONS: Ectodermal dysplasia cases have a particular place in dentistry and require a professional, multi-disciplinary approach in respect of the chewing function, orthognathic problems, growth, oral and dental health. It has been understood that with data obtained from modern technologies such as three-dimensional dental tomography and the treatments applied, the quality of life of these cases can be improved.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Displasia Ectodérmica/complicações , Imageamento Tridimensional , Doenças Estomatognáticas/diagnóstico por imagem , Doenças Estomatognáticas/etiologia , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto Jovem
7.
Drug Des Devel Ther ; 8: 2069-74, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25364232

RESUMO

AIM: The purpose of this study was to evaluate the effects of caffeic acid phenethyl ester (CAPE) on palatal mucosal defects and tooth extraction sockets in an experimental model. MATERIALS AND METHODS: Forty-two male Sprague-Dawley rats with a mean age of 7 weeks and weighing 280-490 g were used in this study. The rats were randomly divided into two groups: group A (the control group, n=21) and group B (the experimental group, n=21). Under anesthesia with ketamine (8 mg/100 g, intraperitoneally), palatal mucosal defects were created and tooth extraction was performed in the rats in groups A and B. Group A received no treatment, whereas group B received CAPE. CAPE was injected daily (10 µmol/kg, intraperitoneally). The rats were killed on days 7, 14, and 30 after the procedures. Palatal mucosa healing and changes in bone tissue and fibrous tissue were evaluated histopathologically. RESULT: Pairwise comparisons showed no statistically significant difference between days 7 and 14 in either group (P>0.05). At day 30, bone healing was significantly better in group B (CAPE) than in group A (control) (P<0.05). Fibrinogen levels at day 30 were significantly higher in group A (control) than in group B (CAPE) (P<0.05). Pairwise comparisons showed no statistically significant difference in palatal mucosa healing levels between days 7 and 14 in both groups (P>0.05). CONCLUSION: In conclusion, the findings of this study suggest that CAPE can significantly improve tooth socket healing.


Assuntos
Ácidos Cafeicos/farmacologia , Mucosa Bucal/efeitos dos fármacos , Álcool Feniletílico/análogos & derivados , Extração Dentária , Alvéolo Dental/efeitos dos fármacos , Cicatrização/efeitos dos fármacos , Animais , Ácidos Cafeicos/administração & dosagem , Masculino , Mucosa Bucal/patologia , Álcool Feniletílico/administração & dosagem , Álcool Feniletílico/farmacologia , Ratos , Ratos Sprague-Dawley , Alvéolo Dental/patologia
8.
J Oral Pathol Med ; 43(2): 103-10, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23952682

RESUMO

OBJECTIVE: The biostimulation effects of low-level laser therapy (LLLT) have been demonstrated recently. This study investigated the effects of LLLT on palatal mucoperiosteal wound healing and oxidative stress status in rats. MATERIAL AND METHOD: Forty-two male Wistar rats weighing 250-300 g were used in this study. A standardized full-thickness wound was created in the mucoperiosteum of the hard palates of the rats using a 3-mm-diameter biopsy punch. Treatment using a GaAlAs laser at a wavelength of 940 nm and a dose of 10 J/cm(2) was initiated after surgery and repeated on the 2nd, 4th, and 6th days post-surgery. Seven animals from each group were sacrificed on the 7th, 14th, and 21st days after surgery. Total antioxidant status and total oxidative status were measured in serum. RESULTS: The histopathological findings revealed reduced numbers of inflammatory cells on the 7th day, increased mitotic activity of fibroblasts on the 14th and 21st day, and the same degree of collagen synthesis and vascularization on the days 7, 14, and 21 in the LLLT group compared with the control group. No significant differences in total oxidative status and total antioxidant status were observed between the groups. CONCLUSION: LLLT using a GaAlAs laser at a wavelength of 940 nm and a dose of 10 J/cm(2) elicited a positive healing effect on palatal mucoperiosteal wounds likely via the induction of fibroblasts. The oxidative stress status was not affected by LLLT.


Assuntos
Terapia com Luz de Baixa Intensidade/métodos , Mucosa Bucal/efeitos da radiação , Estresse Oxidativo/efeitos da radiação , Palato Duro/efeitos da radiação , Animais , Antioxidantes/análise , Benzotiazóis , Biópsia por Agulha/instrumentação , Colágeno/efeitos da radiação , Epitélio/patologia , Epitélio/efeitos da radiação , Fibroblastos/patologia , Fibroblastos/efeitos da radiação , Indicadores e Reagentes , Queratinócitos/patologia , Queratinócitos/efeitos da radiação , Lasers Semicondutores/uso terapêutico , Masculino , Mitose/efeitos da radiação , Mucosa Bucal/lesões , Mucosa Bucal/patologia , Neovascularização Fisiológica/efeitos da radiação , Neutrófilos/patologia , Neutrófilos/efeitos da radiação , Palato Duro/lesões , Palato Duro/patologia , Dosagem Radioterapêutica , Ratos , Ratos Wistar , Ácidos Sulfônicos , Fatores de Tempo , Cicatrização/efeitos da radiação
9.
Photomed Laser Surg ; 31(7): 315-21, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23789588

RESUMO

OBJECTIVE: The biostimulation effects of low-level laser therapy (LLLT) have recently been demonstrated. In this study, we aimed to investigate the effects of LLLT on palatal mucoperiostal wound healing and oxidative stress status in experimental diabetic rats. MATERIALS AND METHODS: Forty-two male Wistar rats that weighed 250-300 g were used in this study. Experimental diabetes was induced in all of the rats using streptozotocin. A standardized full thickness wound was made in the mucoperiosteum of the hard palates of the rats using a 3 mm biopsy punch. The rats were divided into groups: 1 (control group, non- irradiated), and 2 (experimental group, irradiated). Treatment using a GaAlAs laser at a wavelength of 940 nm and at dose of 10 J/cm(2) began after surgery, and was repeated on the 2nd, 4th, and 6th days post-surgery. Seven animals from each group were killed on the 7th, 14th, and 21st day after surgery. Biopsies were performed for the histological analysis and blood samples were collected by cardiac puncture for biochemical analysis. RESULTS: The histopathological findings revealed reduced numbers of inflammatory cells, and increased mitotic activity of fibroblasts, collagen synthesis, and vascularization in rats in group 2. The total oxidative status was significantly decreased in the laser-treated group on the 21st day. CONCLUSIONS: LLLT elicits a positive healing effect on palatal mucoperiostal wounds, and modulates the oxidative status in experimental diabetic rats.


Assuntos
Diabetes Mellitus Experimental/fisiopatologia , Terapia com Luz de Baixa Intensidade , Mucosa Bucal/lesões , Estresse Oxidativo/efeitos da radiação , Palato/lesões , Periósteo/lesões , Cicatrização/efeitos da radiação , Animais , Masculino , Mucosa Bucal/efeitos da radiação , Palato/efeitos da radiação , Periósteo/efeitos da radiação , Ratos , Ratos Wistar
10.
Int J Oral Maxillofac Implants ; 27(6): 1443-7, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23189295

RESUMO

PURPOSE: It is unknown whether zoledronic acid (ZA) interferes with initial bone healing at implant sites. The goal of this study was to examine the effects of systemic zoledronic acid administration on osseointegration of hydroxyapatite (HA)-coated and resorbable blast material surface (RBM) implants in rabbit models. MATERIALS AND METHODS: Twenty-eight male New Zealand rabbits (aged 6 to 12 months) were used in this study. Rabbits were randomly assigned to four groups. In group A, HA-coated implants were placed in the right tibia of seven rabbits. In group B, RBM-surface implants were placed in the right tibia of seven rabbits. In group C, HA-coated implants were placed in seven rabbits with intravenous (IV) administration of ZA. Finally, in group D, RBM-surface implants were placed in seven rabbits with IV administration of ZA. For groups C and D, IV zoledronic acid (0.1 mg/kg) was performed monthly during the entire osseointegration period. All of the rabbits were sacrificed 12 weeks after the implantation, and tibial specimens were harvested. Histomorphometric bone-to-implant contact (BIC) analysis and the data were statistically analyzed. RESULTS: The highest BIC percentage was detected in group D, with a mean value of 56.73%±1.85%, as compared with 45.80%±3.77% in group C, 35.11%±0.76% in group B, and 31.14%±1.04% in group A. CONCLUSIONS: Histomorphometric analyses showed significant improvement in the osseointegration of implants in the RBM-surface ZA group compared with the HA-coated ZA group. The results of this study suggest that systemic ZA administration may improve osseointegration of titanium implants in bone.


Assuntos
Conservadores da Densidade Óssea/farmacologia , Materiais Revestidos Biocompatíveis/uso terapêutico , Implantes Dentários , Difosfonatos/farmacologia , Durapatita/uso terapêutico , Imidazóis/farmacologia , Osseointegração/efeitos dos fármacos , Titânio , Animais , Conservadores da Densidade Óssea/administração & dosagem , Difosfonatos/administração & dosagem , Imidazóis/administração & dosagem , Masculino , Coelhos , Distribuição Aleatória , Propriedades de Superfície , Tíbia , Ácido Zoledrônico
11.
Mol Cell Biochem ; 365(1-2): 165-73, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22350756

RESUMO

Currently, obesity is an important health problem in all countries, both developed and developing. Dietary habits and neurohormonal imbalances play a critical role in obesity. Circulating amounts of ghrelin, which is a neurohormonal hormone, decrease with obesity and increase with weight loss. Although it is known that both mRNA and peptide version of the ghrelin hormone are expressed in almost all tissues of both humans and animals, it is not known how obesity changes the expression of this hormone in the tissues, with the exception of the gastrointestinal system tissues. Therefore, the objective of the present study is to show how diet-induced obesity in rats changes ghrelin expression in all system tissues, and thus, to shed light on the etiopathology of obesity. The study included 12 male and 12 female 2-month-old Wistar albino species rats. The animals in the control group were fed on standard rat pellet, while those in the experiment group were fed ad libitum on a cafeteria-style diet for 2 months. When their body mass index reached 1 g/cm(2), diet-induced obese (DIO) rats were sacrificed in a sterile environment after one night fasting. Ghrelin localizations in the tissues were studied immunohistochemically using avidin-biotin-peroxidase complex (ABC) method, while tissue ghrelin amounts were analyzed using radioimmunoassay (RIA) method. When the ghrelin amounts in the urogenital system (with the exception of kidney tissues), sensory organs, respiratory system, immune system, skeletal muscle system, cardiovascular system, nervous system, and adipose tissue of rats analyzed by RIA method were compared to those in the control group, tissue ghrelin amounts in the DIO group were found lower. Immunohistochemical findings which showed a similar fall in ghrelin concentrations in the tissues were parallel to RIA results. In addition, ghrelin was shown to be synthesized in the cardiovascular system, heart muscle cells, tails of the sperms, hair follicles, lacrimal glands, tongue, and teeth of rats for the first time in this study and ghrelin syntheses in these tissues were found to decrease in obesity. Nutritional obesity is among the most common causes of obesity and the findings we have obtained through diet-induced obesity will contribute to the illumination of the etiopathology of obesity.


Assuntos
Dieta/efeitos adversos , Grelina/metabolismo , Obesidade/metabolismo , Animais , Feminino , Imuno-Histoquímica , Masculino , Obesidade/etiologia , Obesidade/patologia , Especificidade de Órgãos , Radioimunoensaio , Ratos , Ratos Wistar
12.
Chem Rev ; 110(2): 1060-81, 2010 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-20143877
13.
J Hazard Mater ; 156(1-3): 619-23, 2008 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-18243541

RESUMO

Using magnesit (MgCO(3)) as a low cost source of magnesium ions in the struvite precipitation for the removal of high ammonium content of leachate was evaluated. Optimum molar concentration and pH conditions were analyzed to minimize the struvite solubility. Since solubility of magnesit in water is low, HCl was used to obtain soluble Mg. Maximum soluble Mg was obtained for the addition of 2 M HCl to the 1 M MgCO(3). Struvite precipitation with magnesit was effective for the removal of ammonium, suspended solid, phosphate and turbidity. Economical evaluation was made comparing the costs of two magnesium sources, MgCl(2) and MgCO(3). The economical analysis has shown that operation cost of struvite precipitation can be reduced about 18% by using MgCO(3) instead of MgCl(2). High salt concentration after struvite precipitation has no inhibitory effect on the anaerobic reactor performance.


Assuntos
Poluentes Ambientais/isolamento & purificação , Magnésio/química , Compostos de Amônio Quaternário/isolamento & purificação , Precipitação Química , Solubilidade
14.
Acta Crystallogr Sect E Struct Rep Online ; 64(Pt 3): m454, 2008 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-21201850

RESUMO

The title complex, [PtCl(2)(C(18)H(40)P(2))], contains a Pt(II) center in an approximately square-planar geometry [cis angle range = 88.09 (3)-91.39 (3)°; twist angle = 1.19 (5)°]. The Pt-P bond lengths of 2.2536 (8) and 2.2513 (8) Šand the Pt-Cl bond lengths of 2.3750 (8) and 2.3588 (8) Šare normal. This crystal form is a polymorph of a structure reported previously [Harada, Kai, Yasuoka & Kasai (1976 ▶). Bull. Chem. Soc. Jpn, 49, 3472-3477].

15.
J Am Chem Soc ; 129(28): 8729-35, 2007 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-17580867

RESUMO

Carbon-carbon bond activation of diphenylacetylene and several substituted derivatives has been achieved via photolysis and studied. Pt0-acetylene complexes with eta2-coordination of the alkyne, along with the corresponding PtII C-C activated photolysis products, have been synthesized and characterized, including X-ray crystal structural analysis. While the C-C cleavage reaction occurs readily under photochemical conditions, thermal activation of the C-C bonds or formation of PtII complexes was not observed. However, the reverse reaction, C-C reductive coupling (PtII --> Pt0), did occur under thermal conditions, allowing the determination of the energy barriers for C-C bond formation from the different PtII complexes. For the reaction (dtbpe)Pt(-Ph)(-CCPh) (2) --> (dtbpe)Pt(eta2-PhCCPh) (1), DeltaG was 32.03(3) kcal/mol. In comparison, the energy barrier for the C-C bond formation in an electron-deficient system, that is, (dtbpe)Pt(C6F5)(CCC6F5) (6) --> (dtbpe)Pt(eta2-bis(pentafluorophenyl)acetylene) (5), was found to be 47.30 kcal/mol. The energy barrier for C-C bond formation was able to be tuned by electronically modifying the substrate with electron-withdrawing or electron-donating groups. Upon cleavage of the C-C bond in (dtbpe)Pt(eta2-(p-fluorophenyl-p-tolylacetylene) (9), both (dtbpe)Pt(p-fluorophenyl)(p-tolylacetylide) (10) and (dtbpe)Pt(p-tolyl)(p-fluorophenylacetylide) (11) were obtained. Kinetic studies of the reverse reaction confirmed that 10 was more stable toward the reductive coupling [the term "reductive coupling" is defined as the formation of (dtbpe)Pt(eta2-acetylene) complex from the PtII complex] than 11 by 1.22 kcal/mol, under the assumption that the transition-state energies are the same for the two pathways. The product ratio for 10 and 11 was 55:45, showing that the electron-deficient C-C bond is only slightly preferentially cleaved.

16.
J Hazard Mater ; 148(3): 708-13, 2007 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-17445983

RESUMO

The experimental data of ammonium exchange by natural Bigadiç clinoptilolite was evaluated using nonlinear regression analysis. Three two-parameters isotherm models (Langmuir, Freundlich and Temkin) and three three-parameters isotherm models (Redlich-Peterson, Sips and Khan) were used to analyse the equilibrium data. Fitting of isotherm models was determined using values of standard normalization error procedure (SNE) and coefficient of determination (R(2)). HYBRID error function provided lowest sum of normalized error and Khan model had better performance for modeling the equilibrium data. Thermodynamic investigation indicated that ammonium removal by clinoptilolite was favorable at lower temperatures and exothermic in nature.


Assuntos
Compostos de Amônio Quaternário/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Zeolitas/química , Análise de Regressão , Termodinâmica , Turquia
17.
J Hazard Mater ; 146(1-2): 362-71, 2007 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-17261347

RESUMO

Adsorption of Pb(II) ions from aqueous solution onto clinoptilolite has been investigated to evaluate the effects of contact time, initial concentration and pretreatment of clinoptilolite on the removal of Pb(II). Experimental data obtained from batch equilibrium tests have been analyzed by four two-parameter (Freundlich, Langmuir, Temkin and Dubinin-Radushkevich), four three-parameter (Redlich-Peterson, Sips, Toth and Khan) isotherm models, and kinetic models including the pseudo-first order, the pseudo-second order and Elovich equations using nonlinear regression technique. Of the two-parameter isotherms, Temkin isotherm was the best to describe the experimental data. Three-parameter isotherms have higher regression coefficients (>0.99) and lower relative errors (<5%) than two-parameter isotherms. The best fitting isotherm was the Sips followed by Toth and Redlich-Peterson isotherm equations. Maximum experimental adsorption capacity was found to be 80.933 and 122.400 mg/g for raw and pretreated clinoptilolite, respectively, for the initial concentration of 400 mg/L. Kinetic parameters; rate constants, equilibrium adsorption capacities and related coefficients for each kinetic model were evaluated according to relative errors and correlation coefficients. Results of the kinetic studies show that best fitted kinetic models are obtained to be in the order: the pseudo-first order, the pseudo-second order and Elovich equations. Using the thermodynamic equilibrium coefficients, Gibbs free energy of the Pb(II)-clinoptilolite system was evaluated. The negative value of change in Gibbs free energy (DeltaG degrees ) indicates that adsorption of Pb(II) on clinoptilolite is spontaneous.


Assuntos
Chumbo/química , Poluentes Químicos da Água/química , Zeolitas/química , Adsorção , Troca Iônica , Cinética , Cloreto de Sódio/química , Soluções , Purificação da Água/métodos
18.
Inorg Chem ; 45(18): 7197-209, 2006 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-16933920

RESUMO

Iridium complexes containing the large bite angle bisphosphine ligand xantphos have been synthesized and their reactivity studied. Several of these complexes are the first reported Ir(xantphos) systems to be characterized by X-ray diffraction. Variable-temperature NMR spectroscopic studies of IrI(CO)2(xantphos) (1-I) and Ir(COEt)(CO)2(xantphos) (8) show two separate dynamic processes in which the phosphorus donors and the backbone methyl groups of the xantphos ligand are exchanged. The addition of parahydrogen (p-H2) to 1-I leads to the formation of two dihydride isomers including one in which both hydride ligands are trans to the phosphorus donors, suggestive of an Ir(I) xantphos intermediate with the ligand chelated in a trans-spanning fashion (2b). The bromide and chloride Ir(I) analogues (1-Br and 1-Cl) also form this isomer upon reaction with parahydrogen, with 1-Cl yielding only this dihydride species. The trihydride complex IrH3(CO)(xantphos) (7) has been prepared, and its exchange with free hydrogen at elevated temperature is confirmed by reaction with p-H2. The hydride complexes IrH(CO)2(xantphos) (6) and IrH3(CO)(xantphos) (7), as well as the propionyl complex 8, are modest catalysts for the hydroformylation of 1-hexene and styrene under mild conditions. The addition of p-H2 to 8 permits direct observation of the propionyl dihydride species IrH2(COEt)(CO)(xantphos) (9) under both thermal and photolytic conditions, as well as unusual but weak polarization of the aldehydic proton of the propanal product that forms upon reductive elimination from 9.


Assuntos
Hidrogênio/química , Irídio/química , Modelos Moleculares , Compostos Organometálicos/química , Fosfinas/química , Xantenos/química , Alquilação , Catálise , Cristalografia por Raios X , Ligantes , Estrutura Molecular , Estereoisomerismo
19.
Artigo em Inglês | MEDLINE | ID: mdl-15137708

RESUMO

In the study, anaerobic digestion of residues from rose oil industry was investigated by using a laboratory scale completely mixed batch reactor in volume of 10 L and 4 small reactors in volume of 400 mL. Ten liters reactor isolated with a water jacket and 0.4 L reactors settled into a water bath were operated at 35 +/- 1 degrees C. The study supplies biochemical methane potential of hydrolyzed and original residues. Experimental results showed that hydrolyzed rose residue produced a bit more methane than original residue. Methane production results were analyzed with first-order and Chen&Hashimoto's models, and Chen&-Hashimoto's model was found to be more suitable than first-order kinetic model.


Assuntos
Bactérias Anaeróbias/fisiologia , Fontes de Energia Bioelétrica , Reatores Biológicos , Metano/análise , Óleos de Plantas/metabolismo , Eliminação de Resíduos/métodos , Conservação de Recursos Energéticos , Gases , Hidrólise , Cinética , Rosa
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