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1.
Burns Trauma ; 10: tkac043, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36439706

RESUMO

Background: Sepsis-induced cardiomyopathy (SIC) is an identified serious complication of sepsis that is associated with adverse outcomes and high mortality. Heat shock proteins (HSPs) have been implicated in suppressing septic inflammation. The aim of this study was to investigate whether HSP70 can attenuate cellular mitochondrial dysfunction, exuberated inflammation and inflammasome-mediated pyroptosis for SIC intervention. Methods: Mice with cecal ligation plus perforation (CLP) and lipopolysaccharide (LPS)-treated H9C2 cardiomyocytes were used as models of SIC. The mouse survival rate, gross profile, cardiac function, pathological changes and mitochondrial function were observed by photography, echocardiography, hematoxylin-eosin staining and transmission electron microscopy. In addition, cell proliferation and the levels of cardiac troponin I (cTnI), interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) were determined by Cell Counting Kit-8, crystal violet staining and enzyme-linked immunosorbent assay. Moreover, mitochondrial membrane potential was assessed by immunofluorescence staining, and dynamin-related protein 1 and pyroptosis-related molecules [nucleotide-binding domain, leucine-rich-repeat containing family pyrin domain-containing 3 (NLRP3), caspase-1, gasdermin-D (GSDMD), gasdermin-D N-terminal (GSDMD-N)] were measured by western blotting, immunoprecipitation and immunoblotting. Finally, hsp70.1 knockout mice with CLP were used to verify the effects of HSP70 on SIC and the underlying mechanism. Results: Models of SIC were successfully established, as reduced consciousness and activity with liparotrichia in CLP mice were observed, and the survival rate and cardiac ejection fraction (EF) were decreased; conversely, the levels of cTnI, TNF-α and IL-1ß and myocardial tissue damage were increased in CLP mice. In addition, LPS stimulation resulted in a reduction in cell viability, mitochondrial destabilization and activation of NLRP3-mediated pyroptosis molecules in vitro. HSP70 treatment improved myocardial tissue damage, survival rate and cardiac dysfunction caused by CLP. Additionally, HSP70 intervention reversed LPS-induced mitochondrial destabilization, inhibited activation of the NLRP3 inflammasome, caspase-1, GSDMD and GSDMD-N, and decreased pyroptosis. Finally, knockout of hsp70.1 mice with CLP aggravated cardiac dysfunction and upregulated NLRP3 inflammasome activity, and exogenous HSP70 significantly rescued these changes. It was further confirmed that HSP70 plays a protective role in SIC by attenuating mitochondrial dysfunction and inactivating pyroptotic molecules. Conclusions: Our study demonstrated that mitochondrial destabilization and NLRP3 inflammasome activation-mediated pyroptosis are attributed to SIC. Interestingly, HSP70 ameliorates sepsis-induced myocardial dysfunction by improving mitochondrial dysfunction and inhibiting the activation of NLRP3 inflammasome-mediated pyroptosis, and such a result may provide approaches for novel therapies for SIC.

2.
JAMA Health Forum ; 3(3): e220276, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-35977291

RESUMO

Importance: Current disease risk-adjustment formulas in the US rely on diagnostic classification frameworks that predate the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM). Objective: To develop an ICD-10-CM-based classification framework for predicting diverse health care payment, quality, and performance outcomes. Design Setting and Participants: Physician teams mapped all ICD-10-CM diagnoses into 3 types of diagnostic items (DXIs): main effect DXIs that specify diseases; modifiers, such as laterality, timing, and acuity; and scaled variables, such as body mass index, gestational age, and birth weight. Every diagnosis was mapped to at least 1 DXI. Stepwise and weighted least-squares estimation predicted cost and utilization outcomes, and their performance was compared with models built on (1) the Agency for Healthcare Research and Quality Clinical Classifications Software Refined (CCSR) categories, and (2) the Health and Human Services Hierarchical Condition Categories (HHS-HCC) used in the Affordable Care Act Marketplace. Each model's performance was validated using R 2, mean absolute error, the Cumming prediction measure, and comparisons of actual to predicted outcomes by spending percentiles and by diagnostic frequency. The IBM MarketScan Commercial Claims and Encounters Database, 2016 to 2018, was used, which included privately insured, full- or partial-year eligible enrollees aged 0 to 64 years in plans with medical, drug, and mental health/substance use coverage. Main Outcomes and Measures: Fourteen concurrent outcomes were predicted: overall and plan-paid health care spending (top-coded and not top-coded); enrollee out-of-pocket spending; hospital days and admissions; emergency department visits; and spending for 6 types of services. The primary outcome was annual health care spending top-coded at $250 000. Results: A total of 65 901 460 person-years were split into 90% estimation/10% validation samples (n = 6 604 259). In all, 3223 DXIs were created: 2435 main effects, 772 modifiers, and 16 scaled items. Stepwise regressions predicting annual health care spending (mean [SD], $5821 [$17 653]) selected 76% of the main effect DXIs with no evidence of overfitting. Validated R 2 was 0.589 in the DXI model, 0.539 for CCSR, and 0.428 for HHS-HCC. Use of DXIs reduced underpayment for enrollees with rare (1-in-a-million) diagnoses by 83% relative to HHS-HCCs. Conclusions: In this diagnostic modeling study, the new DXI classification system showed improved predictions over existing diagnostic classification systems for all spending and utilization outcomes considered.


Assuntos
Patient Protection and Affordable Care Act , Risco Ajustado , Atenção à Saúde , Gastos em Saúde , Humanos , Classificação Internacional de Doenças , Estados Unidos/epidemiologia
3.
J Inflamm Res ; 15: 2213-2228, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35411167

RESUMO

Purpose: Acute kidney injury (AKI) is one of the most severe complications of sepsis, the pathological features of which are excessive inflammation and programmed cell death of resident renal cells. Heat shock protein 70 (HSP70) is a critical stress protein for repressing inflammation, however, its role in AKI is not fully understood. The current study aimed to determine the protective effect of HSP70 on septic AKI and its underlying mechanisms. Methods: Hsp70.1 knockout and wildtype mice were used for creating sepsis model by cecal ligation and puncture (CLP). Renal function, histological changes, pro-inflammatory cytokines, and apoptosis were analyzed with H&E, PAS, ELISA, western-blot, and immunofluorescence. Moreover, the effects of HSP70 on renal proximal tubular epithelial (HK-2) cells with LPS were assessed by measuring the levels of nuclear factor kappa B (NF-κB) signaling and downstream cytokines, viability, and apoptosis using western-blot, qRT-PCR, flow-cytometry, and immunofluorescence. Immunoprecipitate and immunoblotting were used for determining the interaction of HSP70 with tumor necrosis factor receptor-associated factor 6 (TRAF6). Exogenous HSP70 was applied to further identify its biological significance at the cellular and animal level. Results: Hsp70.1 deficiency significantly aggravated renal dysfunction with increasing serum levels of BUN, SCr, kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL), and shortened survival in CLP mice. Furthermore, hsp70.1 knockout caused renal-tissue structural damage, especially proximal tubular, and inflammatory cascade and increased apoptotic cells, along with elevated Bax, caspase 3 and cleaved caspase 3, as well as decreased Bcl2 in vivo and vitro. Significantly, HSP70 directly interacted with TRAF6 in HK-2 cells, leading to suppression of inflammatory response and apoptosis. Moreover, exogenous HSP70 alleviated renal damage, decreased apoptosis and elevated survival rate in septic AKI in vivo and vitro. Conclusion: Our findings demonstrated that HSP70 played a critical role in sepsis-induced AKI via interaction with TRAF6 and inhibiting inflammation and apoptosis.

4.
J Invest Dermatol ; 141(1): 48-58.e3, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-32533962

RESUMO

Thermoresistance is a physiological phenomenon relevant to noninvasive laser treatments for skin esthetics and tumor removal, although the underlying mechanism remains elusive. We hypothesized that HSPA1A may regulate autophagy by reducing ESCRT-0 and/or STAM2 levels, which could lead to thermal protection from cell death. In this study, we showed that thermoresistance was induced in mouse epidermal tissue and HaCaT cells by heating at 45 °C for 10 minutes. Moreover, HSPA1A levels were increased in thermoresistant mouse epidermis and HaCaT cells. HSPA1A was highly involved in protecting cells from thermal cytotoxicity, as evidenced by the knockdown or overexpression assays of the HSPA1A gene. In addition, ESCRT-0 and STAM2 levels were dramatically decreased in thermoresistant cells, which was mediated by HSPA1A binding to STAM2, particularly through HSPA1A amino acids 395‒509. Furthermore, the loss of ESCRT-0 and/or STAM2 in response to HSPA1A-STAM2 binding regulated autophagy by impeding autophagosome‒lysosome fusion and abolishing autophagic flux in cellular thermoresistance, significantly reducing thermal cytotoxicity and promoting cell survival. To our knowledge, it is previously unreported that HSPA1A-ESCRT-0 and/or STAM2 modulates heat-induced resistance by inhibiting autophagic flux. In summary, the results of this study demonstrate that the mechanisms of thermoresistance may have clinical relevance for noninvasive or minimally invasive thermal therapeutics.


Assuntos
Proteínas de Choque Térmico HSP70/metabolismo , Temperatura Alta/efeitos adversos , Estresse Mecânico , Animais , Autofagia , Morte Celular , Sobrevivência Celular , Células Cultivadas , Humanos
5.
BMC Vet Res ; 16(1): 308, 2020 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-32843036

RESUMO

BACKGROUND: Portal hypertension is a severe complication caused by various chronic liver diseases. The standard methods for detecting portal hypertension (hepatic venous pressure gradient and free portal pressure) are available in only a few hospitals due to their technical difficulty and invasiveness; thus, non-invasive measuring methods are needed. This study aimed to establish and assess a novel model to calculate free portal pressure based on biofluid mechanics. RESULT: Comparison of each dog's virtual and actual free portal pressure showed that a biofluid mechanics-based model could accurately predict free portal pressure (mean difference: -0.220, 95% CI: - 0.738 to 0.298; upper limit of agreement: 2.24, 95% CI: 1.34 to 3.14; lower limit of agreement: -2.68, 95% CI: - 3.58 to - 1.78; intraclass correlation coefficient: 0.98, 95% CI: 0.96 to 0.99; concordance correlation coefficient: 0.97, 95% CI: 0.93 to 0.99) and had a high AUC (0.984, 95% CI: 0.834 to 1.000), sensitivity (92.3, 95% CI: 64.0 to 99.8), specificity (91.7, 95% CI: 61.5 to 99.8), positive likelihood ratio (11.1, 95% CI: 1.7 to 72.8), and low negative likelihood ratio (0.08, 95% CI: 0.01 to 0.6) for detecting portal hypertension. CONCLUSIONS: Our study suggests that the biofluid mechanics-based model was able to accurately predict free portal pressure and detect portal hypertension in canines. With further research and validation, this model might be applicable for calculating human portal pressure, detecting portal hypertensive patients, and evaluating disease progression and treatment efficacy.


Assuntos
Doenças do Cão/diagnóstico , Hipertensão Portal/veterinária , Pressão na Veia Porta , Veia Porta/diagnóstico por imagem , Animais , Fenômenos Biomecânicos , Velocidade do Fluxo Sanguíneo , Tetracloreto de Carbono/administração & dosagem , Doenças do Cão/diagnóstico por imagem , Cães , Hipertensão Portal/induzido quimicamente , Hipertensão Portal/diagnóstico , Hipertensão Portal/diagnóstico por imagem , Masculino , Modelos Teóricos , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios X/veterinária , Ultrassonografia Doppler/veterinária
6.
JAMA Netw Open ; 3(4): e202280, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32267514

RESUMO

Importance: On October 1, 2015, the US transitioned to the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) for recording diagnoses, symptoms, and procedures. It is unknown whether this transition was associated with changes in diagnostic category prevalence based on diagnosis classification systems commonly used for payment and quality reporting. Objective: To assess changes in diagnostic category prevalence associated with the ICD-10-CM transition. Design, Setting, and Participants: This interrupted time series analysis and cross-sectional study examined level and trend changes in diagnostic category prevalence associated with the ICD-10-CM transition and clinically reviewed a subset of diagnostic categories with changes of 20% or more. Data included insurance claim diagnoses from the IBM MarketScan Commercial Database from January 1, 2010, to December 31, 2017, for more than 18 million people aged 0 to 64 years with private insurance. Diagnoses were mapped using 3 common diagnostic classification systems: World Health Organization (WHO) disease chapters, Department of Health and Human Services Hierarchical Condition Categories (HHS-HCCs), and Agency for Healthcare Research and Quality Clinical Classification System (AHRQ-CCS). Data were analyzed from December 1, 2018, to January 21, 2020. Exposures: US implementation of ICD-10-CM. Main Outcomes and Measures: Monthly rates of individuals with at least 1 diagnosis in a diagnostic classification category per 10 000 eligible members. Results: The analytic sample contained information on 2.1 billion enrollee person-months with 3.4 billion clinically assigned diagnoses; the mean (range) monthly sample size was 22.1 (18.4 to 27.1 ) million individuals. While diagnostic category prevalence changed minimally for WHO disease chapters, the ICD-10-CM transition was associated with level changes of 20% or more among 20 of 127 HHS-HCCs (15.7%) and 46 of 282 AHRQ-CCS categories (16.3%) and with trend changes of 20% or more among 12 of 127 of HHS-HCCs (9.4%) and 27 of 282 of AHRQ-CCS categories (9.6%). For HHS-HCCs, monthly rates of individuals with any acute myocardial infarction diagnosis increased 131.5% (95% CI, 124.1% to 138.8%), primarily because HHS added non-ST-segment-elevation myocardial infarction diagnoses to this category. The HHS-HCC for diabetes with chronic complications increased by 92.4% (95% CI, 84.2% to 100.5%), primarily from including new diabetes-related hypoglycemia and hyperglycemia codes, and the rate for completed pregnancy with complications decreased by 54.5% (95% CI, -58.7% to -50.2%) partly due to removing vaginal birth after cesarean delivery as a complication. Conclusions and Relevance: These findings suggest that the ICD-10-CM transition was associated with large prevalence changes for many diagnostic categories. Diagnostic classification systems developed using ICD-9-CM may need to be refined using ICD-10-CM data to avoid unintended consequences for disease surveillance, performance assessment, and risk-adjusted payments.


Assuntos
Classificação Internacional de Doenças , Adolescente , Adulto , Criança , Pré-Escolar , Codificação Clínica/estatística & dados numéricos , Estudos Transversais , Bases de Dados Factuais , Humanos , Lactente , Recém-Nascido , Análise de Séries Temporais Interrompida , Pessoa de Meia-Idade , Prevalência , Estados Unidos , Adulto Jovem
7.
Front Oncol ; 10: 399, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32296638

RESUMO

Background: This study aims to compare survival outcome after receiving radiofrequency ablation (RFA) and surgical resection (SR) for solitary hepatocellular carcinoma (HCC) with size large as 5 cm. Methods: The SEER database was queried for patients with HCC tumors who were treated with RFA or SR between 2004 and 2015. Univariate and multivariate Cox analysis was used to assess the influence of potential variables on the patients' outcome. Additionally, propensity score matching (PSM) and multiple imputations (MI) were used as sensitivity analyses. Results: Of 1,985 cases, 934 patients received RFA treatment, while the rest underwent surgical resection. The patients in the RFA group had poorer overall survival (OS) and cancer-specific survival (CSS) than those in the SR group regardless of the tumor size before matching and MI. By using PSM analysis at a 1:1 ratio, 1,302 cases were paired and we have found that SR had a positive impact on OS and CSS of patients with tumors measuring from 3.1 to 5 cm. However, when the tumor size was <3 cm, patients undergoing SR had similar survival benefit with those after RFA. The above results were confirmed after performing PSM analysis at a 1:2 and 1:3 ratio. Conclusion: By applying several effective sensitivity analyses, we demonstrated that OS and CSS were similar between the patients with tumors smaller than 3 cm receiving RFA and SR. But SR may be a superior treatment option with better long-term outcome than RFA in patients with tumor measuring 3.1-5 cm.

8.
Sci Rep ; 7(1): 5292, 2017 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-28706273

RESUMO

Based on TiO2 as a model system, the sol-gel one step facile method is established to fabricate the macro-porous morphology films on the basis of Marangoni effect. In this proposed mechanism, the binary mixture of hydrophilic CuCl2 and lipophilic Ti-O network is used in sol to produce phase separation. A suitable evaporation rate in the gel film process leads to the macro-porous film due to Marangoni effect. It is observed that the macro-porous morphology of the film sustains during the annealing process, which suggests the creation of porous surface morphology in gel film stage rather than due to annealing. To analyze the preparation mechanism, the sol-gel process and microstructure of films are examined using TG-DTA, SEM, TEM, XRD, Raman, UV-Vis, XPS and FTIR. Furthermore, the optical-thermal properties are studied for the potential applications of such porous surface films as solar selective absorber.

9.
Int J Nanomedicine ; 12: 295-304, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28115847

RESUMO

Silver nanoparticles (AgNPs) are being widely applied as topical wound materials; however, accumulated deposition of silver in the liver, spleen, and other main organs may lead to organ damage and dysfunction. We report here that low molecular weight chitosan-coated silver nanoparticles (LMWC-AgNPs) are effective against methicillin-resistant Staphylococcus aureus (MRSA), have better biocompatibility, and have lower body absorption characteristics when compared with polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) and silver nanoparticles without surface stabilizer (uncoated-AgNPs) in a dorsal MRSA wound infection mouse model. LMWC-AgNPs were synthesized by reducing silver nitrate with low molecular weight chitosan as a stabilizer and reducing agent, while PVP-AgNPs were synthesized using polyvinylpyrrolidone as a stabilizer and ethanol as a reducing agent. AgNPs with different surface stabilizers were identified by UV-visible absorption spectrometry, and particle size was determined by transmission electron microscopy. UV-visible absorption spectra of LMWC-AgNPs, PVP-AgNPs and uncoated-AgNPs were similar and their sizes were in the range of 10-30 nm. In vitro experiments showed that the three types of AgNPs had similar MRSA-killing effects, with obvious effect at 4 µg/mL and 100% effect at 8 µg/mL. Bacteriostatic annulus experiments also showed that all the three types of AgNPs had similar antibacterial inhibitory effect at 10 µg/mL. Cell counting kit-8 assay and Hoechst/propidium iodide (PI) staining showed that LMWC-AgNPs were significantly less toxic to human fibroblasts than PVP-AgNPs and uncoated-AgNPs. Treatment of mice with MRSA wound infection demonstrated that the three types of AgNPs effectively controlled MRSA wound infection and promoted wound healing. After continuous application for 14 days, LMWC-AgNPs-treated mice showed significantly reduced liver dysfunction as demonstrated by the reduced alanine aminotransferase and aspartate aminotransferase levels and liver deposition of silver, in comparison to mice treated with uncoated-AgNPs or PVP-AgNPs. Our results demonstrated that LMWC-AgNPs had good anti-MRSA effects, while harboring a better biocompatibility and lowering the body's absorption characteristics.


Assuntos
Quitosana/farmacologia , Nanopartículas Metálicas/química , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Prata/uso terapêutico , Infecções Estafilocócicas/tratamento farmacológico , Ferimentos e Lesões/tratamento farmacológico , Ferimentos e Lesões/microbiologia , Animais , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Morte Celular/efeitos dos fármacos , Quitosana/química , Quitosana/uso terapêutico , Fibroblastos/efeitos dos fármacos , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Nanopartículas Metálicas/ultraestrutura , Camundongos Endogâmicos BALB C , Peso Molecular , Tamanho da Partícula , Povidona/química , Prata/farmacologia , Prata/toxicidade , Espectrofotometria Ultravioleta , Infecções Estafilocócicas/microbiologia , Cicatrização/efeitos dos fármacos
10.
Nanoscale Res Lett ; 6: 477, 2011 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-21794165

RESUMO

In this study, controllable ZnO nanorod arrays were successfully synthesized on Si substrate at room temperature (approx. 25°C). The formation of controllable ZnO nanorod arrays has been investigated using growth media with different concentrations and molar ratios of Zn(NO3)2 to NaOH. Under such a nonequilibrium growth condition, the density and dimension of ZnO nanorod arrays were successfully adjusted through controlling the supersaturation degree, i.e., volume of growth medium. It was found that the wettability and electrowetting behaviors of ZnO nanorod arrays could be tuned through variations of nanorods density and length. Moreover, its field emission property was also optimized by changing the nanorods density and dimension.

11.
Nanotechnology ; 20(21): 215605, 2009 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-19423936

RESUMO

This work presents a facile way, i.e. phase-separation-induced self-assembly, to prepare TiO(2) nanodots on a substrate. This method induces convective flow in a spin-coated titanium tetrabutoxide (TBOT)/polyvinyl pyrrolidone (PVP)/ethanol liquid film through the Marangoni effect and turns TBOT into crystalline TiO(2) nanodots on a substrate after calcination. The size and density of the TiO(2) nanodots can be finely tailored by controlling the concentrations of TBOT and PVP in the precursor sol. The TiO(2) nanodot-deposited surface showed a hydrophilic characteristic and the wettability was obviously improved by increasing nanodot size.


Assuntos
Cristalização/métodos , Nanoestruturas/química , Nanoestruturas/ultraestrutura , Nanotecnologia/métodos , Titânio/química , Substâncias Macromoleculares/química , Teste de Materiais , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
12.
Nanoscale Res Lett ; 4(8): 809-13, 2009 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-20596343

RESUMO

Monodisperse and spherical Eu-doped TiO2nanodots were prepared on substrate by phase-separation-induced self-assembly. The average diameters of the nanodots can be 50 and 70 nm by changing the preparation condition. The calcined nanodots consist of an amorphous TiO2matrix with Eu3+ions highly dispersed in it. The Eu-doped TiO2nanodots exhibit intense luminescence due to effective energy transfer from amorphous TiO2matrix to Eu3+ions. The luminescence intensity is about 12.5 times of that of Eu-doped TiO2film and the luminescence lifetime can be as long as 960 µs.

13.
J Phys Condens Matter ; 21(27): 275901, 2009 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-21828502

RESUMO

First-principles pseudopotential calculations by means of the local density approximation (LDA) within density-functional theory (DFT) are carried out to investigate the negative pressure induced ferroelectric phase transition in rutile TiO(2) in the range of -25 to 25 GPa. The softening behavior of the A(2u)(TO) modes at the Γ point following the decreasing pressure leads to a ferroelectric phase transition from P4(2)/mnm (rutile) space group to P42nm (ferro) space group. The calculated pressure dependence of the phonon frequencies, A(1)(TO), E(TO), and B(2) modes of the ferro TiO(2) relative to A(2u)(TO), E(u)(TO), and B(1u) modes of rutile TiO(2), indicates that the phase transition occurs at around -10 GPa, consistent with the total energy results. The dramatic increase of the c-axial dielectric tensor in the vicinity of the phase transition indicates it to be a typical ferroelectric phase transition. The character of the phase transition is generally identified in terms of the calculated order parameters, displaying a second order.

14.
J Mater Sci Mater Med ; 20(1): 359-63, 2009 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18807264

RESUMO

Biphasic alpha-tricalcium phosphate/beta-tricalcium phosphate (alpha/beta-TCP) with a designed phase ratio is thought to have controllable dissolution-reprecipitation behavior that is significant in the repair and regeneration of bone. Amorphous calcium phosphate (ACP) was selected as a precursor to prepare biphasic alpha/beta-TCP. The influence of polyethylene glycol (PEG) content in ACP on its crystallization, or on the phase ratio of the resulting biphasic TCP, was investigated. ACP was synthesized by the reaction of Ca(NO(3))(2) with (NH(4))(2)HPO(4) using PEG as an additive. Depending on the amount of PEG addition, resulting ACP could be crystallized to alpha-TCP, beta-TCP or biphasic alpha/beta-TCP after heat-treatment at 800 degrees C, showing that PEG addition is a critical factor to tailor the phase ratio of biphasic alpha/beta-TCP. One reason for the influence of PEG is that ACP with different PEG content could have two types of unit structures that tend to form alpha-TCP and beta-TCP after crystallization.


Assuntos
Substitutos Ósseos/química , Fosfatos de Cálcio/química , Polietilenoglicóis/química , Cristalização , Teste de Materiais , Microscopia Eletrônica de Transmissão , Termodinâmica , Difração de Raios X
15.
J Zhejiang Univ Sci B ; 7(4): 299-303, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16532532

RESUMO

This study on the band structures and charge densities of nitrogen (N)-, carbon (C)- and boron (B)-doped titanium dioxide (TiO(2)) by first-principles simulation with the CASTEP code (Segall et al., 2002) showed that the three 2p bands of impurity atom are located above the valence-band maximum and below the Ti 3d bands, and that along with the decreasing of impurity atomic number, the fluctuations become more intensive. We cannot observe obvious band-gap narrowing in our result. Therefore, the cause of absorption in visible light might be the isolated impurity atom 2p states in band-gap rather than the band-gap narrowing.

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