Development of environmentally friendly flexible medical X-ray shielding materials and analysis and optimization of their protective performance / 中华放射医学与防护杂志

Objective:To develope and analyze and optimize the performance of some kinds of environmentally friendly flexible X-ray protective materials in attempt to tackle the various environmental and high energy consumption problems in the development of traditional medical X-ray protective clothing.Methods:The Monte Carlo program was used to establish a simplified model of medical X-ray tube. The aim was to carry out numerical simulation and prediction of the shielding materials′ performance against X-ray, prepare the flexible X-ray shielding materials through experiments and test and verify the their shielding performances The development and optimization path was also obtained by comparing the result between simulation and experiment.Results:Bi was the preferred alternative to toxic Pb elements, while W was able to compensate for weak X-ray absorption zone of Bi. The shielding efficiency of the composite material doped with 25% Bi+ 25% W was able to reach 77.8% and 66.3% at 80 and 120 kV p tube voltages, respectively. Conclusions:With both the selection of elements and the optimization of functional particles, the combination of W and Bi is an economical, environmentally friendly, and efficient shielding way within the energy range of medical diagnostic X-rays. The numerical simulation helps reduce experimental costs, shorten the research period, and improve the design efficiency of X-ray shielding materials.

Ecological and growth patterns of the longsnout seahorse Hippocampus reidi inferred by mark-recapture techniques in a tropical estuary / Padrões ecológicos e de crescimento do cavalo-marinho Hippocampus reidi inferidos por técnicas de recaptura em um estuário tropical

Abstract: The population structure of the longsnout seahorse Hippocampus reidi (Ginsburg 1933) was evaluated in an estuarine system in northeastern Brazil. A total of 425 captures were performed in the Vaza-Barris estuary and 232 individuals were marked with Visible Implant Fluorescent Elastomers. The population was estimated to be composed of 428 fish. The von Bertalanffy growth curve shows a steeper growth during the first months of life, up to about 17 months, and stabilization after 16 cm and 27 months of age. The hereby study indicates that the Vaza-Barris estuary is home to resident populations of longsnout seahorses. Moreover, these populations use mangrove roots as the main substrate for attachment and present well-defined ecological characteristics, such as habitat fidelity and highly structured social organization.

Resumo: A estrutura populacional do cavalo-marinho Hippocampus reidi (Ginsburg 1933) foi avaliada em um sistema estuarino no nordeste do Brasil. Um total de 425 capturas foram realizadas no estuário de Vaza-Barris e 232 indivíduos foram marcados com Elastômeros Fluorescentes de Implante Visível. A população foi estimada em 428 peixes. A curva de crescimento de von Bertalanffy mostra um crescimento mais acentuado durante os primeiros meses de vida, até cerca de 17 meses, e estabilização após os 16 cm e 27 meses de idade. O presente estudo indica que o estuário Vaza-Barris é o lar de populações residentes de cavalos-marinhos de focinho comprido. Além disso, essas populações utilizam raízes de mangue como principal substrato de fixação e apresentam características ecológicas bem definidas, como fidelidade de habitat e organização social altamente estruturada.

Polyisobutylene and its thermoplastic elastomers: How to transform from industry to medical treatment / 中国组织工程研究

BACKGROUND: Polyisobutylene and block copolymer and its crosslinked product are a kind of novel thermoplastic elastomer. They have unique properties and excellent biocompatibility, which is a promising medical biomaterial and applied extensively. OBJECTIVE: To review the research progress and applications of polyisobutylene and its thermoplastic elastomers, and to discuss the application prospect of polyisobutylene-based polymers as medical implant materials. METHODS: A computer-based retrieval of PubMed, Web of Science, CNKI and WanFang databases was conducted for the articles about polyisobutylene published from 1958 to 2019. The key words were “polyisobutylene and block copolymer, polyisobutylene and thermoplastic elastomer, polyisobutylene and biomaterials, polyisobutylene and modification, polyisobutylene and medical application” in English and Chinese, respectively. In accordance with the inclusion and exclusion criteria, 65 eligible articles were included for review. RESULTS AND CONCLUSION: Polyisobutylene and block copolymer and its crosslinked products have favorable biocompatibility and stability. By making full use of polyisobutylene-based materials’ advantages, with the combination of other biomaterials and usage of new technology for surface modification, the copolymer will be more competitive in the field of medical implant in the future, including eye implant materials, soft biomaterials and drug delivery systems.

Effect of chemical disinfectants and accelerated aging on maxillofacial silicone elastomers: An In vitro Study

Maxillofacial prostheses need frequent refabrication due to degradation of color and deterioration of physical properties of the elastomer. Aims: This study attempted to evaluate the change in color stability, Shore A hardness, and surface roughness of two maxillofacial silicones, A-2186 and Cosmesil M511, when submitted to chemical disinfection and accelerated aging. Settings and Design: This was a comparative in vitro study. Subjects and Methods: The materials included two silicone elastomers – A-2186 and Cosmesil M511 (Factor II Incorporated) – functional intrinsic red pigment and three disinfectants – Fittydent tablet, chlorhexidine gluconate 4%, and neutral soap. The specimens in each group of elastomer were evaluated initially for color, hardness, and surface roughness, which were further divided into subgroups and subjected to disinfection and accelerated aging. The evaluation of color was performed with the help of an ultraviolet reflectance spectrophotometer. Shore A hardness was evaluated using a durometer and surface roughness, with a digital roughness tester followed by scanning electron microscopy analysis. Statistical Analysis Used: Analysis of variance and Tukey's multiple comparison test were used for statistical analysis. Results: Accelerated aging caused a significant decrease in color, increase in Shore A hardness, and variation in surface roughness in both silicone elastomer groups. Chemical disinfection presented significant changes in color and surface roughness whereas no significant effect on Shore hardness, irrespective of the disinfectant used. Conclusions: The maxillofacial silicone elastomers presented deterioration in color, hardening, and significant variations in surface roughness when subjected to chemical disinfection and accelerated aging, which provides a valid baseline for future research.

Analysis in vitro of strength degradation comparing latex and non-latex elastics

Aim: This study was conducted in order to evaluate and compare the behavior of latex and non-latex elastics, as the loss of strength over time in vitro. Methods: The study evaluated 15 of each elastic material for the pre-selected times: 0, 1, 3, 12 and 24 hours. The rubber bands were transferred to the testing machine (EMIC DL-500 MF). The force values were recorded after stretching the elastic to a length of 25mm. Independent t-test was applied. Analysis of variance (ANOVA) was used to check the variation of the forces generated between those determined times. To identify between which times the difference was present, Tukey post-hoc test was accomplished. Results: As regards the initial forces (zero time), the values of force for non-latex elastic were slightly higher than the latex elastic. In subsequent times, the forces generated by the latex elastic showed higher values. Regarding the material degradation, at the end of 24 hours the highest percentage was observed for non-latex elastic. Conclusion: The latex elastic had a more stable behavior during the studied period compared with non-latex. Thus, it is suggested that the non-latex elastics should be changed more frequently and that larger initial forces must be applied than the látex elastics

Inferior Canaliculi Punctal Granuloma of the Lacrimal System: A Case Report

Pyogenic granuloma of the eyes usually occurs after ocular surgery or inflammation related to the eyes, itself. This lesion is commonly related to procedures associated with chalazia, strabismus, or even enucleation. However, the incidence of pyogenic granuloma that arises directly from the lower canaliculi of the nasolacrimal system is rare and not being extensively reported. We report a case of an elderly lady who presented with pyogenic granuloma post EDCR with silicone stenting for left nasolacrimal duct obstruction. She presented with persistent left eye epiphora following procedure. The unusual site for pyogenic granuloma and it occurrence after EDCR raise the possibility that the condition is related to previous procedure and the material being used.

Enhancing retention of partial dentures using elastomeric retention rings.

This report presents an alternative method for the retention of partial dentures that relies on the engagement of tooth undercuts by a lining material. The lab procedures are also presented. A new maxillary and mandibular acrylic partial dentures were fabricated using elastomeric retention technique for a partially dentate patient. A partially dentate man reported difficulty in retaining his upper removable partial denture (RPD). The maxillary RPD was designed utilizing elastomeric retention technique. During follow‑up, it was necessary to replace the retention rings due to wear. The replacement of the retention rings, in this case, was done through a chairside reline technique. Elastomeric retention technique provides exceptionally good retention can be indicated to stabilize, cushion, splint periodontally involved teeth, no enough undercut for clasps, eliminate extractions, single or isolated teeth.

Effect of Different Primers on the Peel Bond Strength between Silicone Elastomer and Acrylic Resins.

Introduction: Implant-supported extra-oral prostheses often require a retentive matrix to hold gold alloy clips and magnets, which act as retentive means. Silicone elastomers have a different structure to acrylic resins. Hence, primers are used to increase the bonding between silicone and acrylic resin. Aim of Study: To investigate the effect of new platinum primers on the peel bond strength of silicone elastomer to acrylic resins. Materials and Methods: Peel bond strength of Cosmesil 2004 to two acrylic resins was assessed using two primers (MED6-161 and MED160) and no primer (control group). Sixty samples were prepared and divided into six groups according to the combination of acrylic resin, silicone, primer and no primer. All samples were then exposed to load in a universal testing machine with a cross head speed of 25 mm/min until failure. Data was analysed using STATA 12.1 software. Values of mean peel force between light and auto-polymerising acrylic resins were compared using two-way ANOVA and tukey HSD test. Results: The interaction between primers and acrylic resins had a significant effect on peel bond strength between Cosmesil 2004 and acrylic resins. MED6-161 primer significantly improved peel bond strength of Cosmesil 2004 to light-polymerising acrylic resin. However, MED-160 primer enhanced peel bond strength between Cosmesil 2004 and auto-polymerising acrylic resin. Conclusion: The combination of primer and acrylic is important in improving the bond strength. However, further investigation of different primers, silicones and different surface treatments to achieve the optimum bonding is need.

Evaluation of bonding efficiency between facial silicone and acrylic resin using different bonding agents and surface alterations

PURPOSE: The aim of the study was to evaluate the effect of 3 silicone primers and 3 surface characterization of acrylic resin surface on bond strength between silicone elastomer and acrylic resin. MATERIALS AND METHODS: 96 Cosmesil silicones bonded to heat-curing acrylic resin were fabricated with the dimension of 75 x 10 x 3 mm. The 3 primers used in this study were G611 platinum primer, A-330 Gold platinum primer, and cyanoacrylates resin. Specimens without primer were used as control. The 3 types of surface characterization done were retentive holes with 1.5 mm in diameter and 0.5 mm deep, retentive beads of 0.6 mm diameter and the third type which was plain without any characterization. The specimens were then checked for bond strength by subjecting them to 180degrees peel test on a universal testing machine. The obtained results were then subjected to statistical analysis using 2-way ANOVA and Scheffe multiple post hoc procedures. The statistical significance was set at 5% level of significance. RESULTS: The maximum bond strength was seen for samples in which A-330G primer was used followed by G611 primer. The control group showed the minimum bond strength. Surface characterization of retentive holes increased the bond strength considerably as compared to retentive beads and samples without any surface characterization. CONCLUSION: Within the limitations of the study, A-330G primer was more compatible with Cosmesil M511 silicone and has better bonding of Cosmesil to acrylic resin. Retentive holes made on acrylic surface increased the bond strength considerably than those without any surface characterization.

Buttock Augmentation with Elastomer Implants

PURPOSE: The buttocks region has been associated with allure and sex appeal for centuries. Gluteal implants enable buttocks remodeling in a way that is not possible in other methods. One of the reasons that render gluteal implant surgeries unpopular is the fear of complications, the main problems being seroma, wound dehiscence, extrusion, and a visible or palpable implant. The authors present the XYZ technique, which provides anatomical reference points to guide the intramuscular dissection procedure in a feasible and safe way, resulting in a lower complication rate. METHODS: The XYZ procedure was done for buttock augmentation on 8 patients from December 2009 to June 2010. Patient's ages ranged from 27 to 44 with a mean age of 36. Seven patients were applied the 250cc sized Elastomer implants with one patient 290cc sized implant. Preoperative marking was done with the patients in the standing position. Bisection of the gluteus maximus muscle was done at the midpoint thickness to create a plane for implant insertion, which is called the sandwich plane. RESULTS: The 8 cases were performed safely without major complications. However one patient had minor wound dehiscence, and was managed with conservative treatment. Another patient had a discomfort on the buttocks for a long time. The patients were followed up for average 6 months. All patients were satisfied with the aesthetic results. CONCLUSION: In performing the XYZ technique for gluteal augmentation, the surgeon must split the muscle into two equal halves with anatomical reference points to guide the muscle detachment in a symmetrical way at an adequate depth. This method provides a guideline for the surgeon in determining the ideal plane during intramuscular dissection and gives predictable results with low complication rates. Intramuscular gluteoplasty with gluteal implants offers predictable, aesthetically pleasing results without contour irregularities and only a low incidence of major complications.

Force degradation in orthodontic elastic chains / Degradação de forças em correntes elásticas ortodônticas

Purpose: This in vitro study aimed to analyze the force degradation of four commercial brands of orthodontic elastics chain (Morelli, Ormco, TP, and Unitek) over 21 days. Methods: The elastics chains were stretched and maintained at a standardized distance equivalent to a force of 150 g. The amount of force generated by the elastics chains were measured by using a dynamometer (ZEUZAN 300 g) at intervals of 30 minutes, 7, 14, and 21 days. Data were analyzed by ANOVA and Tukey's test at the 5% level of significance. Results: There was a reduction of 5% to 15% in the amount of force generated by the elastic chains after 30 minutes and of 22% to 47% after 21 days of elastic activation. Conclusion: Unitek chains displayed the highest percentage of force degradation, while TP exhibited the smallest percentage of force degradation and showed the greatest stability at all intervals tested.

Objetivo: Este estudo teve por objetivo analisar a degradação da força gerada por quatro marcas comerciais de elásticos ortodônticos em cadeia (Morelli, Ormco, TP e Unitek) em função do tempo. Metodologia: Os elásticos foram mantidos continuamente estirados a uma distância equivalente à força de 150 g. A leitura da quantidade de força gerada pelas correntes elásticas foi mensurada utilizando-se um dinamômetro da marca ZEUZAN 300 g, nos intervalos: 30 minutos, 7, 14, 21 dias. Os resultados foram analisados por ANOVA e teste de Tukey ao nível de significância de 0,05. Resultados: Verificou-se uma redução na quantidade de força gerada pelos elásticos de 5% a 15% em 30 minutos de teste e de 22% a 47% em 21 dias de estiramento constante. Conclusão: A marca Unitek obteve um maior percentual de degradação de força, enquanto a marca TP um menor percentual de degradação de força mostrando comportamento mais estável em todos os intervalos de tempo testados.

Comportamento dimensional de gessos dos tipos IV e V na confecção de modelos obtidos de moldes em duas diferentes temperaturas: 22 e 35ºC / Dimensional behavior of types IV and V gypsum when building models obtained form molds in two different temperatures: 22 and 35º C

O experimento foi idealizado com objetivo de comparar os procedimentos do reaquecimento de moldagens ao vazamento de moldes resfriados com gesso dos tipos IV e V. Os materiais utilizados foram Adsil Vigodent, Express e Impregum 3M Espe, Zeta Plus e Oranwash Zhermack. Os moldes passaram, sem exceção, por uma temperatura de 35ºC onde foram obtidos, para 22ºC onde foram armazenados. O delineamento dos experimentos seguiu a divisão dos seguintes grupos quanto ao tratamento térmico: Alguns grupos receberam vazamento dos gessos IV e V após o reaquecimento dos moldes para 35ºC, enquanto outros receberam os mesmos gessos à 22ºC. A técnica de moldagem selecionada para o primeiro experimento foi de dupla mistura...

The experiments It was conceived with the objective of to compare the procedures of reheating moldings with the leaking of cooled molds with types IV and V gypsum.The materials used were Adsil Vigodent, Express e Impregum 3M Espe, Zeta Plus and Oranwash Zhermack. The molds passed without exception, from a temperature of 35ºC where they were obtained, to 22ºC, where they were stored. The delimitation of all experiments followed the division of the following groups as of the thermic treating: Some groups received gypsum type IV and V leaking after the reheating of the molds to 35ºC, whilst others received the same gypsums at 22ºC temperature. The selected molding technique for the first experiment was of a double-mix. The used elastomers were Impregum 3M Espe, Express 3M Espe and Adsil Vigodent, and the impressions materials were the gypsum Vel-Mix Kerrande Exadur Polidental. The statistical analysis showed a significance in the cooled impressions and leaked with type V gypsum, and that the reheating of the impressions produced adequate models when these are leaked whth type IV gypsum. On the second experiment, the used molding technique was the double molding.The molding materials were Zeta Plus and Oranwash Zhermak, Adsil Vigodent and Express 3M Espe this technique is known as double molding. The...

Silicone elastomers for maxillofacial prosthesis / 上海第二医科大学学报

Current materials used for maxillofacial prostheses are far from ideal,and how to develop a final prosthetics material is a significant topic in the research of maxillofacial prostheses.In this paper,some pertinent research of silicone elastomeric materials,such as mechanical properties and colorant are reviewed.

Hepatic Vascular Cast Using Elastomeric Nanocomposites and Their Clinical Applications

PURPOSE: For a successful partial liver resection, familiarity with the many anatomical variations of the biliary and vascular components in the liver is important. The aim of this study was to fabricate a precisely reproduced model of a human hepatic vascular cast with a very fine structure using elastomeric nanocomposites. METHODS: A model of the vascular structure of the human liver was prepared by injecting elastomeric nanocomposites latex into that of a human liver obtained from a cadaver dissection, followed by cross-linking of the elastomeric nanocomposites, and then leaching out the human tissues using a strong acid solution. RESULTS: A produced new version of human vascular casts, with further improved performances in both the stability and mechanical property, was successfully produced by application of new elastomer nanocomposites techniques based on clay nano particles. The cast showed a much finer vascular structure and lasted longer. This new technique is expected to provide a useful protocol for the investigating of the real vascular structure of the human liver. CONCLUSION: A precisely reproduced vascular cast of the human liver will significantly help to solve surgical complications, such as hepatic congestion-induced vascular injury and bile leakage, and give a more precise simulation for anatomical hepatic resection.

Growth and/or acid production ability of Candida albicans on silicon elastomer incorporated with antifungal agents / 实用口腔医学杂志

Objective:Through monitoring the pH of the growth medium,to evaluate the growth and/or acid production ability of Candida albicans on silicon elastomer incorporated with two different antifungal agents.Methods:Antifungal agents(AntimTM-AM and Conval pag-40)were added at concentrations from 0% to 2%,and antibacterial effect of the material in saliva and serum groups were examined.The third group added nothing was served as the control.Results:Each group with 2% antifungal agents showed great inhibitory effects on the acid production and /or the growth of C.albicans.These inhibitory effects consisted of a delay in the onset of rapid pH decline,decreased with the rate of pH change and increased in minimum pH.As a result,Conval pag-40 showed a significantly greater antimicrobial effect than AntimTM-AM.Conclusion:Silicone elastomer material incorporated with antifungal agents have strong antibacterial ability and can satisfy the requirements of clinical application.

The effects of primers on the bonding of an silicone elastomer to acrylic resin / 实用口腔医学杂志

Objective:To evaluate the effects of primers on the bonding of an silicone elastomer to acrylic resin.Methods:Acrylic resin specimens were divided into eight groups.Six new primers and Cosmesil G611 primer were applied to the acrylic resin surfaces respectively.Untreated group was used as control.The shear bond strengths between silicone elastomer and acrylic resin were determined.D primer were measured by Forier transform infrared spectroscopy,and the bands were analyzed using spectrum method.Results:The experiment group with different concentration of ?-MPS showed different shear bond strengths between silicone elastomer and acrylic resin.Type D primer showed 2.20 MPa shear bond strength,which was significantly higher than that of other groups.While 1.44 MPa for Cosmesil G611 primer was found,there was no bond strength for untreated group.Conclusion:The concentration of ?-MPS is relative to the shear bond strength and type D primer can give the highest shear bond strength.

The color changes of SY-1 silicone elastomer before and after polymerization / 实用口腔医学杂志

Objactive:To study the color changes of SY-1 silicone elastomer before and after polymerization.Methods:L*a*b*color parameters of 10 samples of SY-1 silicone elastomer were measured with Minolta chroma-ticity instrument(CS-321) before and after polymerization.The color difference(△E) between precure and post-cure was calculated as△E =[(△L)2+(△a)2+(△b)2]1/2.Results:After polymerization L*and a*valueswere increased(P

Effects of pigment concentration on spectral reflectance of pigmented silicone elastomer / 实用口腔医学杂志

Objective:To evaluate the effects of pigment concentration on spectral reflectance of pigmented silicone elastomer.Methods: Six kinds of pigment at different concentrations was respectively added into MDX-4-4210 silicone elastomer to prepare six series of single-chroma-samples, including red, yellow, blue, brown, white and black.The pigment concentrations to base elastomer were set at 0.1, 0.2 , 0.3, 0.4, 0.5, 0.6,0.7, 0.8, 0.9 and 1.0C, respectively while other conditions were kept the same. C is the maximum pigment concentration in practical use. The target samples were also prepared. By spectrophotometer, the spectral data of the single-chroma-samples and target samples were measured.Results:With the increase of pigment concentration, the spectral reflectance of the six series of single-chroma-samples and target samples decreased.Conclusion:Increase of pigment concentration may result in decrease of spectral reflectance of single-chroma-samples and taget samples.

Adherence of Candida albicans on the surface of silicone elastomer / 实用口腔医学杂志

砄bjective:To compare the adherent ability of Candida albicans on the surface of two kinds of silicone elastomer used as prosthodontic materials and to study the factors affecting the adherence.Methods: Candida albicans were cultured on the surface of SY 1 and MDXA 4210 with or without saliva acquired pellicle for 10 min, then the number of the bacteria was counted.Results:With or without saliva acquired pellicle,the number (1?10 3/mm 2) of C.albicans on SY 1 was 24.5?0.88 and 2.0?0.47 respectively( P 0.05 ).Conclusion:There is little difference between the adherent ability of C.albicans on the two kind of silicone elastomer.Saliva acquired pellicle can decrease the adherence.

Study on the mechanical properties of surface-lubricated catheter made of PVA hydrogel / 中国康复理论与实践

@#Two types of catheter made of polymeric hydrogel were prepared and their mechanical properties were studied. The results showed PVA hydrogel catheter was prepared by repeated freezing-thawing cycles of PVA solution in mould. Another type of catheter (PVA-DMSO - hydrogel ) was prepared by cooling the PVA solution containing 10%wt DMSO in mould. The tensile strength (30～40MPa)and elongation(380 %～400%) of these two types of catheter were comparable with those of commercial PVC catheter and silicone rubber catheter. But the elastic modulus of PVA-DMSO hydrogel catheter was 10MPa,near to silicone rubber catheter and that of PVA hydrogel catheter was only 4MPa. γ-ray irradiation for sterile made 40%～50% loss of tensile strength for both catheter. Dipping in hibitane aqueous solution didn\'t affect mechanical properties.The obvious difference in mechanical properties was due to the difference in the orientation of PVA molecule chain and crystalline structure.