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1.
Sci Rep ; 14(1): 3920, 2024 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-38365984

RESUMO

This study aims to analyze time-series measurements encompassing rainstorm events with over a century of datasets to identify rainstorm evolution and dimensional transitions in non-stationarity. Rainstorm events are identified using partial duration series (PDS) to extract changes in rainstorm characteristics, namely maximum intensity (MAXI), duration (D), total rainfall (TR), and average rainfall intensity (ARI), in response to climate change. Ensemble empirical mode decomposition is used for trend filtering and non-stationary identification to explore spatiotemporal insight patterns. Trend models for the first-second-order moments of rainstorm characteristics are used to formulate the identified mean-variance trends using combined multi-dimensional linear-parabolic regression. Best-fitting combinations of various distributions (probability density functions) and trend models for multiple characteristic series are identified based on the Akaike information criterion. We analyze the dimensional transition in rainfall non-stationarity based on sensitivity analysis using PDS to determine its natural geophysical causes. The integrated methodology was applied to the data retrieved from nine weather stations in Taiwan. Our findings reveal rainstorm characteristics of "short D but high rainfall intensity" or "lower MAXI but high TR" across multiple stations. The parabolic trend of the first-order moment (i.e., mean) of ARI, D, and TR appears at the endpoint of the mountain ranges. Areas receiving monsoons and those on the windward plain show a rising parabolic trend in the first- and second-order moments (i.e., mean-variance) characterizing MAXI, implying that the occurrence frequency and magnitude of extreme MAXI increases. Non-stationary transitions in MAXI appear for mountain ranges exposed to the monsoon co-movement effect on both windward and leeward sides. Stations in the plains and rift valleys show upgraded and downgraded transitions in the non-stationary dimensions for D, respectively.

2.
Heliyon ; 9(11): e20478, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38034720

RESUMO

To precisely identify multi-dimensional spatiotemporal rain-making parameters, generate an approximate Hessian matrix, and solve the nonlinear ill-posed problem, this study uses composite logical tangent hyperbolic functions to construct the rain-generating simulation model as nonlinear algebraic equations with designed key-lock quasi-Newton optimization for deriving multi-order objective functional derivatives for rainstorm causal decomposition into advanced functional, analytical solution (lock) and Newton's conditional constraints. Specifically, the rank-two approximate structure of the Levenberg-Marquardt and Broyden-Fletcher-Goldfarb-Shanno quasi-Newton algorithms are modified as the symmetric rank-four structure to efficiently calculate a positive definite stable Hessian and solve the constrained nonlinear rain-making threshold. The model projects various rain-making factors into multi-rank loading scores, characterizing rain-generating mechanisms and causal components as associated DNAs. To accelerate/modify directional convergence, avoid local minimum, and detect global optimum, the devised vectorized limited switchable step sizes are optimized using advanced double-bracketing approaches combined with candidate parameters' correction vectors (key) and referenced step-size distributions solved by Newton's constrained analytical solution to reduce heterogeneous differences and eliminate the conventional overestimated Hessian. The identified rain-making DNAs reveal that typhoons with similar DNAs move in similar directions. Specifically, rain-making DNAs in Taipei Category 1 were correlated with wind force/direction and cloud height along PCs 1, 3, 4, and 7, and those in Category 2 were correlated with cloud-cover distribution along PCs 1, 2, and 5. The identified rain-making thresholds of typhoons with constant direction/structure showed a weaker steady state, whereas the unsteady rest produced multi-peak rainfall hydrographs. Rain evolution analysis reveals that cloudy rainbands, carried by the wind field, move along the Tamsui River valley when traveling between northeast and south-southeast of Taipei; converge with gradient and geostrophic winds when traveling between east-northeast and southwest; merge with southwest monsoon when traveling between west-southwest and northeast of Kaohsiung.

4.
Polymers (Basel) ; 13(23)2021 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-34883754

RESUMO

In this study, polycaprolactone (PCL)- and poly(acrylic acid) (PAA)-based electrospun nanofibers were prepared for the carriers of antimicrobials and designed composite nanofiber mats for chronic wound care. The PCL- and PAA-based electrospun nanofibers were prepared through in situ polymerization starting from PCL and acrylic acid (AA). Different amounts of AA were introduced to improve the hydrophilicity of the PCL electrospun nanofibers. A compatibilizer and a photoinitiator were then added to the electrospinning solution to form a grafted structure composed of PCL and PAA (PCL-g-PAA). The grafted PAA was mainly located on the surface of a PCL nanofiber. The optimization of the composition of PCL, AA, compatibilizer, and photoinitiator was studied, and the PCL-g-PAA electrospun nanofibers were characterized through scanning electron microscopy and 1H-NMR spectroscopy. Results showed that the addition of AA to PCL improved the hydrophilicity of the electrospun PCL nanofibers, and a PCL/AA ratio of 80/20 presented the best composition and had smooth nanofiber morphology. Moreover, poly[2 -(tert-butylaminoethyl) methacrylate]-grafted graphene oxide nanosheets (GO-g-PTA) functioned as an antimicrobial agent and was used as filler for PCL-g-PAA nanofibers in the preparation of composite nanofiber mats, which exerted synergistic effects promoted by the antibacterial properties of GO-g-PTA and the hydrophilicity of PCL-g-PAA electrospun nanofibers. Thus, the composite nanofiber mats had antibacterial properties and absorbed body fluids in the wound healing process, thereby promoting cell proliferation. The biodegradation of the PCL-g-PAA electrospun nanofibers also demonstrated an encouraging result of three-fold weight reduction compared to the neat PCL nanofiber. Our findings may serve as guidelines for the fabrication of electrospun nanofiber composites that can be used mats for chronic wound care.

5.
Ann Vasc Surg ; 69: 453.e1-453.e4, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32653614

RESUMO

A 16-year-old male was brought to our hospital presenting with acute onset of a painful protruding left neck mass within a day, associated with left upper-arm tenderness. Chest computed tomography revealed high attenuation masses at the left supraclavicular and mediastinal regions, suspected of being venous vascular tumors. Surgery was arranged and then ruptured venous tumor was noted, with pathology results determining a venous malformation.


Assuntos
Implante de Prótese Vascular , Veias Braquiocefálicas/cirurgia , Neoplasias de Cabeça e Pescoço/cirurgia , Hemangioma/cirurgia , Veias Jugulares/cirurgia , Cervicalgia/etiologia , Adolescente , Veias Braquiocefálicas/diagnóstico por imagem , Veias Braquiocefálicas/patologia , Neoplasias de Cabeça e Pescoço/complicações , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/patologia , Hemangioma/complicações , Hemangioma/diagnóstico por imagem , Hemangioma/patologia , Humanos , Veias Jugulares/diagnóstico por imagem , Veias Jugulares/patologia , Ligadura , Masculino , Cervicalgia/diagnóstico , Ruptura Espontânea , Resultado do Tratamento
6.
Polymers (Basel) ; 12(7)2020 Jun 28.
Artigo em Inglês | MEDLINE | ID: mdl-32605222

RESUMO

A novel cationic polymer, poly[2-(tert-butylaminoethyl) methacrylate] (PTA), effectively kills various strains of bacteria with low toxicity to tissue cells. Graphene-based materials demonstrate exceptional electron transport capability, antibacterial activity, favorable nontoxicity, and versatile applicability. PTA can be grafted onto the graphene oxide (GO) surface (GO-g-PTA) to enhance the antimicrobial efficiency of the latter against Staphylococcus aureus (S. aureus). In this study, GO-g-PTA powders were successfully synthesized via free radical polymerization (GO-g-PTA-F) and atom transfer radical polymerization (GO-g-PTA-A). The antimicrobial efficiencies of graphene nanosheets (GNSs), GO-g-PTA-F, and GO-g-PTA-A were then investigated. Addition of GNS, GO-g-PTA-F, and GO-g-PTA-A to the PVA nanofibers was carried out elucidate the effects of filler amount and physical treatment on the morphology, microstructure, crystallization behaviors, antimicrobial efficiency, and cytotoxicity of the composite fibers. Finally, the potential applications of electrospun PVA/GNS, PVA/GO-g-PTA-F, and PVA/GO-g-PTA-A composite nanofiber mats to chronic wound care were evaluated. The resulting PVA/GO-g-PTA-A composite nanofiber mats showed enhanced antimicrobial ability against S. aureus compared with the PVA/GNS and PVA/GO-g-PTA-F composite nanofiber mats at the same filler volume percentage.

7.
Thorac Cancer ; 11(3): 785-788, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31925930

RESUMO

This report describes the case of a 17-year-old man who developed mediastinal growing teratoma syndrome following two cycles of chemotherapy, after an initial diagnosis of primary mediastinal nonseminomatous germ cell tumor. The large, rapidly-growing mediastinal tumor was completely resected in conjunction with right pneumonectomy, using simultaneous clamshell thoracotomy and median sternotomy. The salvage surgery with perioperative management involved in mediastinal growing teratoma syndrome is presented here. KEY POINTS: Significant findings of the study The diagnosis and surgical management are challenging for patients with mediastinal growing teratoma syndrome. Nevertheless, with proper operative planning, favorable outcomes can be attained with complete resection despite the characteristic rapid growth and massive size of these neoplasms. What this study adds In spite of postoperative sternal dehiscence, we believe that a simultaneous clamshell thoracotomy with median sternotomy approach remains a viable option for an extremely large mediastinal growing teratoma, when tumor size prevents safe resection using other approaches due to limited visualization.


Assuntos
Neoplasias do Mediastino/cirurgia , Neoplasias Embrionárias de Células Germinativas/cirurgia , Terapia de Salvação , Esternotomia/métodos , Teratoma/cirurgia , Neoplasias Testiculares/cirurgia , Toracotomia/métodos , Adolescente , Humanos , Masculino , Neoplasias do Mediastino/patologia , Neoplasias Embrionárias de Células Germinativas/patologia , Prognóstico , Teratoma/patologia , Neoplasias Testiculares/patologia
8.
Radiol Case Rep ; 15(4): 334-338, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31993095

RESUMO

Nail gun injuries usually occur at the extremities due to working accidents. Intracranial or intrathoracic injuries are relatively rare, and cases combined with both injuries are even rarer. Such situations pose challenges for surgeons due to their uniqueness during operation. Radiologic imaging findings in our case were significant in indicating surgical findings. Herein, we report a patient who shot himself using a nail gun, damaging his brain and heart.

9.
Polymers (Basel) ; 11(1)2019 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-30960148

RESUMO

In this study the effects of increased graphene nanosheet (GNS) concentration on variations in the structure and properties of electrospun GNS-filled poly(trimethylene terephthalate) (PTT/GNS) composite fiber, such as its morphologies, crystallization behavior, mechanical properties, and electrical conductivity, were investigated. The effects of GNS addition on solution rheology and conductivity were also investigated. GNSs were embedded in the fibers and formed protrusions. The PTT cold crystallization rate of PTT/GNS composite fibers increased with the gradual addition of GNSs. A PTT mesomorphic phase was formed during electrospinning, and GNSs could induce the PTT mesomorphic phase significantly during PTT/GNS composite fiber electrospinning. The PTT/GNS composite fiber mats (CFMs) became ductile with the addition of GNSs. The elastic recoveries of the PTT/GNS CFMs with 170 °C annealing were better than those of the as-spun PTT/GNS CFMs. Percolation scaling laws were applied to the magnitude of conductivity to reveal the percolation network of electrospun PTT/GNS CFMs. The electrical conductivity mechanism of the PTT/GNS CFMs differed from that of the PTT/GNS composite films. Results showed that the porous structure of the PTT CFMs influenced the performance of the mats in terms of electrical conductivity.

10.
Vasc Endovascular Surg ; 52(2): 131-134, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29187071

RESUMO

INTRODUCTION: Spontaneous iliac vein rupture is a rare but lethal disease. Most patients suffer from shock status in the emergency department. Until now, open laparotomy combined with primary suture is the most common treatment of iliac vein rupture. However, there is high mortality and morbidity in the patients who underwent open laparotomy. CASE PRESENTATION: A 71-year-old woman denied trauma history and sustained hypovolemic shock. The abdominal computed tomography showed one huge retroperitoneal hematoma. The emergency angiography revealed one obvious rupture point on the left external iliac vein. We repaired the lesion with endovascular stent and open laparotomy for abdominal decompression. The patient progressed well and was discharged. CONCLUSION: Endovascular repair is an effective and safe treatment. Compared with open laparotomy and primary suture, stent leads to fewer complications and a lower mortality rate.


Assuntos
Procedimentos Endovasculares/instrumentação , Veia Ilíaca , Doenças Vasculares Periféricas/terapia , Stents , Idoso , Angiografia por Tomografia Computadorizada , Feminino , Humanos , Veia Ilíaca/diagnóstico por imagem , Doenças Vasculares Periféricas/diagnóstico por imagem , Flebografia/métodos , Desenho de Prótese , Fatores de Risco , Ruptura Espontânea , Resultado do Tratamento
11.
Aesthetic Plast Surg ; 41(6): 1375-1381, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28842754

RESUMO

BACKGROUND: Double eyelidplasty can enhance the eye size and facial attractiveness of Asian individuals with single eyelids. The authors hypothesize that a supratarsal fold can induce an eye size assimilation illusion to enhance eye dimensions and aesthetics, and seek to define the optimum vertical proportion between a supratarsal fold and the eye fissure associated with maximal induction of the size assimilation illusion. METHODS: A photometric study of the replicated photographs of ten female Taiwanese patients after double eyelidplasty was designed. Each photograph was edited by shifting the supratarsal folds vertically at a regular fold/eye ratio increment of 0.1. The perceived attractiveness of edited photographs of each patient was rated by 100 adult observers using a score of 1-5. The palpebral parameters were measured and analyzed. RESULTS: The mean rating score increased gradually when a supratarsal fold was added and peaked when the fold/eye ratio was 0.3 and the mean Chen's double eyelid fold ratio was 0.631 ± 0.023. After the peak, the mean score decreased gradually and was lower than the photograph without a fold when the fold/eye ratio exceeded 0.5 and the mean Chen's ratio exceeded 0.729 ± 0.027. CONCLUSION: Within the optimal ranges of the fold/eye ratio and Chen's double eyelid fold ratio, eyes are perceived as larger and more attractive due to a hybrid presentation of two interdependent eye size assimilation illusions induced by a supratarsal fold in the brow-eye unit. "Chen's double eyelid fold illusion" is proposed to describe this complex visual phenomenon. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to Table of Contents or the online Instructions to Authors www.springer.com/00266 .


Assuntos
Povo Asiático/etnologia , Beleza , Blefaroplastia/métodos , Pálpebras/anatomia & histologia , Adulto , Estudos de Coortes , Pálpebras/cirurgia , Feminino , Humanos , Ilusões , Processamento de Imagem Assistida por Computador , Satisfação do Paciente , Fotografação , Estudos Retrospectivos , Adulto Jovem
12.
Mater Sci Eng C Mater Biol Appl ; 79: 481-490, 2017 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-28629044

RESUMO

This study prepares biodegradable bone scaffolds helping the recovery of damaged tibias of rats. Polyvinyl alcohol (PVA) plied yarns are fabricated into hollow braids. The braids are combined with hydroxyapatite (HA)/gelatin/PVA mixtures and processed using freeze-thawing and freeze-drying processes in order to form bone scaffolds. These bone scaffolds are observed by scanning electron scope (SEM) and tested for compression strength. Afterwards, recovery of damaged bone, the morphology of the bone, and the histological observation are evaluated. Results indicate a small amount of HA helps in enhancing the compressive strength of bone scaffolds. Results of in vivo assay indicate the damaged tibias of rats recover and function well eight weeks after the implantation, and exhibit a normal morphology. Histological observation confirms the bone scaffolds gradually decompose, allowing tissue infiltration and facilitating ossification. This study successfully produces bone scaffolds with satisfactory mechanical properties helping in the recovery of damaged tibias of rats.


Assuntos
Tíbia , Animais , Osso e Ossos , Durapatita , Congelamento , Porosidade , Ratos , Engenharia Tecidual , Alicerces Teciduais
13.
Plast Reconstr Surg Glob Open ; 4(4): e681, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27200243

RESUMO

BACKGROUND: Double eyelidplasty can construct palpebral folds and enhance beauty perception for Asians with single eyelids. A new palpebral parameter for the quantitative interpretation of surgical outcomes is proposed on the basis of a photometric study of the altered proportions of Asian eyes after double eyelid operation. METHODS: A total of 100 Asian adults with single upper eyelids who were satisfied with the enlarged eyes by operation were included in the study. A retrospective measurement of palpebral parameters in the frontal profile both preoperatively and 6 months postoperatively was performed. The proportions of various parameters in the eyebrow-eye aesthetic unit were calculated and analyzed. RESULTS: Double eyelidplasty can augment the vertical dimension of palpebral fissure by 27.9% increase on average. The vertical ratio of palpebral fissure to the eyebrow-eye unit is augmented by 34.4% increase. The vertical ratio of the subunit below double eyelid fold peak to the unit is augmented by 82.6% increase. CONCLUSIONS: Double eyelidplasty can substantially enlarge the vertical dimensions of the eyes of Asians with single eyelids. The eyes are perceived to be larger because of the visually assimilated illusion of the superimposed eyelid fold and the relative proportions of the eyebrow-eye unit. The authors propose using a vertical ratio of the subunit below double eyelid fold peak in the eyebrow-eye unit to measure the visually perceived proportion of the eye in the unit. This ratio can be applied clinically for a quantitative evaluation of the surgical outcome after double eyelidplasty.

14.
Materials (Basel) ; 9(12)2016 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-28774119

RESUMO

Factories today are equipped with diverse mechanical equipment in response to rapid technological and industrial developments. Industrial areas located near residential neighborhoods cause massive environmental problems. In particular, noise pollution results in physical and psychological discomfort, and is a seen as invisible and inevitable problem. Thus, noise reduction is a critical and urgent matter. In this study, rigid polyurethane (PU) foam plates undergo perforation using a tapping machine. The mechanical and acoustic properties of these perforated plates as related to perforation rate and perforation depth are evaluated in terms of compression strength, drop-weight impact strength, and sound absorption coefficient. Experimental results indicate that applying the perforation process endows the rigid PU foaming plates with greater load absorption and better sound absorption at medium and high frequencies.

15.
Aesthet Surg J ; 35(4): 359-66, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25804503

RESUMO

BACKGROUND: Double-eyelid procedure to construct a supratarsal fold is the most common aesthetic surgery in young Asian adults. More complex surgical procedures, such as fat grafting or filler injection, are often indicated during traditional, long-incision, double-eyelid procedures to achieve better aesthetic results for patients with hollowness of the upper eyelids. OBJECTIVES: The authors sought to determine the efficacy of minimally-invasive double-eyelid procedures with concurrent repositioning of the orbital fat pads to correct sunken upper eyelids in young Asian adults. METHODS: The study included 250 patients treated between June 2008 and July 2103. Preoperatively, all patients complained of upper-eyelid hollowness and had positive findings on a lower-eyelid compression test. All patients underwent a minimally-invasive double-eyelid procedure plus repositioning of orbital fat. RESULTS: After the minimum follow-up period of 1 year, the overall patient satisfaction rate was 76%. The relapse rate was 10% within the first year, and the complication rate was 8%. CONCLUSIONS: This minimally-invasive combination procedure may be an option for young Asian adults who have single upper eyelids and sunken eyes. The surgery resulted in a natural double eyelid and more youthful orbital appearance in the majority of patients in this study. Proper patient selection and evaluation, including lower eyelid compression testing, are essential to achieve long-term correction.


Assuntos
Tecido Adiposo/transplante , Blefaroplastia/métodos , Pálpebras/cirurgia , Órbita/cirurgia , Adulto , Povo Asiático , Pálpebras/anormalidades , Feminino , Seguimentos , Humanos , Masculino , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Satisfação do Paciente , Seleção de Pacientes , Complicações Pós-Operatórias/epidemiologia , Recidiva , Adulto Jovem
16.
Materials (Basel) ; 8(12): 8279-8291, 2015 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-28793710

RESUMO

This study uses the melt compounding method to produce polypropylene (PP)/short glass fibers (SGF) composites. PP serves as matrix while SGF serves as reinforcement. Two coupling agents, maleic anhydride grafted polypropylene, (PP-g-MA) and maleic anhydride grafted styrene-ethylene-butylene-styrene block copolymer (SEBS-g-MA) are incorporated in the PP/SGF composites during the compounding process, in order to improve the interfacial adhesion and create diverse desired properties of the composites. According to the mechanical property evaluations, increasing PP-g-MA as a coupling agent provides the composites with higher tensile, flexural, and impact properties. In contrast, increasing SEBS-g-MA as a coupling agent provides the composites with decreasing tensile and flexural strengths, but also increasing impact strength. The DSC results indicate that using either PP-g-MA or SEBS-g-MA as the coupling agent increases the crystallization temperature. However, the melting temperature of PP barely changes. The spherulitic morphology results show that PP has a smaller spherulite size when it is processed with PP-g-MA or SEBS-g-MA as the coupling agent. The SEM results indicate that SGF is evenly distributed in PP matrices, but there are distinct voids between these two materials, indicating a poor interfacial adhesion. After PP-g-MA or SEBS-g-MA is incorporated, SGF can be encapsulated by PP, and the voids between them are fewer and indistinctive. This indicates that the coupling agents can effectively improve the interfacial compatibility between PP and SGF, and as a result improves the diverse properties of PP/SGF composites.

17.
Materials (Basel) ; 8(12): 8768-8779, 2015 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-28793744

RESUMO

In order to solve the incompatibility between high porosity and mechanical properties, this study fabricates bone scaffolds by combining braids and sodium alginate (SA) membranes. Polyethylene terephthalate (PET) plied yarns are braided into hollow, porous three dimensional (3D) PET braids, which are then immersed in SA solution, followed by cross-linking with calcium chloride (CaCl2) and drying, to form PET bone scaffolds. Next, SA membranes are rolled and then inserted into the braids to form the spiral and porous PET/SA bone scaffolds. Samples are finally evaluated for surface observation, porosity, water contact angle, compressive strength, and MTT assay. The test results show that the PET bone scaffolds and PET/SA bone scaffolds both have good hydrophilicity. An increasing number of layers and an increasing CaCl2 concentration cause the messy, loose surface structure to become neat and compact, which, in turn, decreases the porosity and increases the compressive strength. The MTT assay results show that the cell viability of differing SA membranes is beyond 100%, indicating that the PET/SA bone scaffolds containing SA membranes are biocompatible for cell attachment and proliferation.

18.
Materials (Basel) ; 8(12): 8850-8859, 2015 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-28793750

RESUMO

This study proposes melt-blending polypropylene (PP) and high density polyethylene (HDPE) that have a similar melt flow index (MFI) to form PP/HDPE polyblends. The influence of the content of HDPE on the properties and compatibility of polyblends is examined by using a tensile test, flexural test, Izod impact test, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and X-ray diffraction (XRD). The SEM results show that PP and HDPE are incompatible polymers with PP being a continuous phase and HDPE being a dispersed phase. The FTIR results show that the combination of HDPE does not influence the chemical structure of PP, indicating that the polyblends are made of a physical blending. The DSC and XRD results show that PP and HDPE are not compatible, and the combination of HDPE is not correlated with the crystalline structure and stability of PP. The PLM results show that the combination of HDPE causes stacking and incompatibility between HDPE and PP spherulites, and PP thus has incomplete spherulite morphology and a smaller spherulite size. However, according to mechanical property test results, the combination of HDPE improves the impact strength of PP.

19.
Mater Sci Eng C Mater Biol Appl ; 45: 359-68, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25491840

RESUMO

The mineralizing capabilities of surface-modified dicalcium phosphate anhydrous (DCPA), reinforced and treated with nanocrystals and capped with silane, in composite resins were analyzed via thermal cycling. We compared two light-curable composites that were mixed at filler-to-resin mass ratios of 30/70 and 50/50. The strengths, elastic moduli, and topographical structures of the samples were determined after thermal cycling between 5 and 55°C in deionized water for 600 and 2400 cycles. Silane-capped particles decreased the strength but enhanced the mineralizing capability of the composites. Nanocrystal-treated filler surfaces significantly increased the strength and moduli of the composites after 600 thermal cycles. However, these values declined after 2400 thermal cycles. The nanocrystal-treated filler surfaces prevented the reduction in strength before and after 2400 thermal cycles. Prior to silane capping, the nanocrystal-treated DCPA filler surfaces exhibited good mineralization capability without compromising strength. The potential for barrier generation through mineralization yielded positive effects and prevented micro-leakages.


Assuntos
Fosfatos de Cálcio/química , Resinas Sintéticas/química , Fenômenos Químicos , Resinas Compostas/química , Teste de Materiais , Nanopartículas/química , Silanos/química , Propriedades de Superfície , Temperatura
20.
J Nanosci Nanotechnol ; 7(9): 3268-76, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-18019160

RESUMO

We describe a synthetic pathway to the formation of stable pyridine-functionalized octanethiolate mixed monolayer-protected Au clusters (MPCs). The spectroscopic characterization data of MPCs using NMR, UV-Vis, TEM, XPS, and thermal-analysis-mass techniques are discussed. TEM analysis showed that spherical nanoclusters of 3-5 nm were produced. Furthermore, the particle sizes are uniform with a narrow size distribution. The pyridine-functionalized MPCs formed 2D superlattices with hexagonal packing covering on the carbon-coated copper grids during the toluene evaporation. For all samples, the S 2p(3/2) and 2p(1/2) components that appeared at approximately 162 and approximately 163 eV, respectively, in the XPS spectra compare very well with the typical value of chemisorbed S species. Thermal analysis mass spectrometer was used to analyze desorption behavior of octanethiolated MPCs or pyridine-functionalized mixed MPCs. The TA-mass spectra have revealed that MCPs exist monomer and dimer desorption behavior from monomeric thiolate adsorbed on the surface.


Assuntos
Ouro/química , Espectrometria de Massas/métodos , Nanopartículas Metálicas/química , Nanotecnologia/métodos , Octanos/química , Piridinas/química , Compostos de Sulfidrila/química , Carbono/química , Cinética , Espectroscopia de Ressonância Magnética , Microscopia Eletrônica de Transmissão , Modelos Químicos , Espectrofotometria/métodos , Propriedades de Superfície , Temperatura
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