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1.
Braz. arch. biol. technol ; 63: e20180513, 2020. graf
Article in English | LILACS | ID: biblio-1132208

ABSTRACT

Abstract Silicon accumulation is known to improve tolerance of plants under both biotic and abiotic stress. Salinity stress is an inevitable crisis causing wide spread damage to rice leading to food insecurity. The influence of Si (1mM) on two rice cultivars cv. Ghanteswari (high accumulator) and cv.Badami (low accumulator) which differs in Si uptake potential under saline (10ds/m EC) and non- saline conditions were studied in nutrient culture. The Si transporter genes were isolated and characterized to determine their function in salinity tolerance. Under stress, there was an increase in Si accumulation, Na+/K+ ratio, electrolyte leakage, lipid peroxidation and antioxidant activities. On addition of silicon, the K+ uptake increased, membrane damage reduced and osmolytes balance improve under salinity. But, the level of resurgence was varied in both cultivars, due to their differential Si-accumulation. Molecular characterizations of Lsi1 protein revealed its involvement in the movement of ion and water and therefore prevent osmotic stress. The Lsi2 is responsible for removal of Na+, reducing salt toxicity. Silicon accumulation is responsible for maintenance of cell water status, osmotic balance and Na+ ion exclusion during high salinity. The variable relative expression of Lsi2 provides a possible explanation for differential genotypic uptake of silicon.


Subject(s)
Membrane Transport Proteins/genetics , Oryza/genetics , Silicon/metabolism , Gene Expression Regulation , Salinity , Salt Stress , Genotype
2.
Article in Korean | WPRIM | ID: wpr-811303

ABSTRACT

PURPOSE: To report a case of retinal toxicity after an intravitreal ganciclovir injection to treat acute retinal necrosis in an eye filled with silicone oil.CASE SUMMARY: A 56-year-old male presented with ocular pain and visual loss in his right eye. His best-corrected visual acuity was 20/25, inflammatory cells in the anterior chamber, multiple retinitis lesions and retinal vessel occlusions in the peripheral retina and vitreous opacity were showed. Acute retinal necrosis was suspected, anterior chamber polymerase chain reaction (PCR) test was done. Aciclovir 2,400 mg/day intravenously and ganciclovir 2.0 mg were administered by intravitreal injection. After 4 days, retinitis was worsened and PCR test was positive for varicella zoster virus. Ganciclovir intravitreal injections were increased twice a week. After 16 days, retinal detachment occurred, so scleral encircling, vitrectomy, laser photocoagulation, and silicone oil tamponade were conducted. Ganciclovir 1.0 mg was injected at the end of surgery. The patient's visual acuity decreased to hand motion, and multiple crystal deposits with multiple retinal hemorrhages were observed in the right eye the next day. Visual acuity did not recover and optical coherent tomography showed that the macula was thinned.CONCLUSIONS: Visual loss seemed to be related with the retinal toxicity of ganciclovir. The increased local concentration due to the silicone oil tamponade is thought to have caused the toxicity.


Subject(s)
Acyclovir , Anterior Chamber , Ganciclovir , Hand , Herpesvirus 3, Human , Humans , Intravitreal Injections , Light Coagulation , Male , Middle Aged , Polymerase Chain Reaction , Retina , Retinal Detachment , Retinal Hemorrhage , Retinal Necrosis Syndrome, Acute , Retinal Vessels , Retinaldehyde , Retinitis , Silicon , Silicones , Visual Acuity , Vitrectomy
3.
Int. braz. j. urol ; 45(5): 1013-1019, Sept.-Dec. 2019. tab, graf
Article in English | LILACS | ID: biblio-1040073

ABSTRACT

ABSTRACT Objectives To validate an experimental non-animal model for training of vasectomy reversal. Materials and Methods The model consisted of two artificial vas deferens, made with silicon tubes, covered by a white resin, measuring 10 cm (length) and internal and external diameters of 0.5 and 1.5 mm, respectively. The holder of the ducts is made by a small box developed with polylactic acid, using a 3D print. The objective of the invention is to simulate the surgical field of vasovasostomy, when the vas deferens are isolated from other cord structures. For validation, it was verified the acquisition of microsurgical skills during its use, in a capacitation course with 5 urology residents from a Hospital of the region. Along the training sessions, it was analyzed the time (speed) of microsurgical sutures, and quantification of the performance using a checklist. Collected data were analyzed using de BioEstat®5.4 software. Results Medium time for the completion of microsurgical sutures improved considerably during the course, and reached a plateau after the third day of training (p=0.0365). In relation to the checklist, it was verified that during capacitation, there was significant improvement of the scores of each participant, that reached a plateau after the fourth day of training with the model (p=0.0035). Conclusion The developed model was able to allow the students that attended the course to gain skills in microsurgery, being considered appropriate for training vasectomy reversal.


Subject(s)
Humans , Male , Vasovasostomy/education , Models, Anatomic , Silicon , Time Factors , Vas Deferens/surgery , Reproducibility of Results , Analysis of Variance , Clinical Competence , Statistics, Nonparametric , Checklist , Printing, Three-Dimensional , Microsurgery/education
4.
Biosci. j. (Online) ; 35(2): 527-539, mar./apr. 2019. tab, graf
Article in English | LILACS | ID: biblio-1048608

ABSTRACT

Silicon (Si) plays specific functions in agriculture. Si is a beneficial element, as it accumulates at high amounts in plant tissue. Si accumulation in cell walls reduces water loss by transpiration and may be an adaptation factor to water stress. This study evaluated the efficiency of different corn crops using calcium silicate as a reducer of hydric stress. The experiment was organized in a factorial scheme, completely randomized, with two doses of calcium silicate (0 and 100 % according to soil liming) with two irrigation depths: (30 and 100 % of necessary water reposition in the soil) and two corn cultivars: (cv. BRS-1010) considered sensitive to hydric stress and (cv. DKB-390) tolerant to hydric stress. The study comprised four repetitions. We studied dry matter production on leaves and stem, weight of 1000 seeds and crop yield. We measured efficiency of gas exchange and water use to compare the different treatments. The results for stem and leaves dry matter were better in both cultivars when using calcium silicate, regardless of irrigation depth. Both corn cultivars cv. BRS-1010, sensitive to hydric stress, and cv. DKB-390, tolerant to hydric stress, had greater yield in the presence of calcium silicate, when at the smallest irrigation dose was applied. The treatment with calcium silicate was the most efficient in water use, using 30% of irrigation depth. Cv. DKB 390 was the most productive, with greater tolerance to water stress.


O silício (Si) desempenha funções específicas na agricultura, sendo considerado um elemento benéfico, pois se acumula em quantidades elevadas no tecido da planta. O acúmulo de Si nas paredes celulares reduz a perda de água pela transpiração e pode ser um fator de adaptação ao estresse hídrico. Este estudo avaliou a eficiência de diferentes cultivares de milho utilizando o silicato de cálcio como amenizador do estresse hídrico. O experimento foi organizado em esquema fatorial, inteiramente casualizado, com duas doses de silicato de cálcio (0 e 100% de acordo com a calagem do solo), com duas lâminas de irrigação (30 e 100% de reposição de água necessária no solo) e duas cultivares de milho: a (cv. BRS-1010) considerada sensível ao estresse hídrico e a (cv. DKB-390) tolerante ao estresse hídrico, com quatro repetições. Estudamos a produção de matéria seca em folhas e caule, o peso de 1000 sementes e o rendimento da cultura. Medimos a eficiência das trocas gasosas e do uso da água para comparar os diferentes tratamentos. Os resultados para matéria seca do caule e das folhas foram melhores em ambas as cultivares, quando utilizadas o silicato de cálcio, independente da lâmina de irrigação. As duas cultivares de milho estudadas, cv. BRS-1010 tolerante ao estresse hídrico e o DKB-390 tolerante ao estresse hídrico apresentaram maior produção na presença de silicato de cálcio, quando a menor lâmina de água foi aplicada. A maior eficiência no uso da água foi obtida no tratamento com silicato de cálcio, utilizando 30% de irrigação. A cv. DKB 390 foi a mais produtiva, com maior tolerância ao déficit hídrico.


Subject(s)
Silicon , Calcarea Silicata , Zea mays , Agricultural Irrigation , Dehydration
5.
Arq. Inst. Biol ; 86: e0512018, 2019. tab, graf
Article in English | ID: biblio-1045995

ABSTRACT

In Brazil, there are few records of insects associated with the cultivation of lima beans; among them, there is the black aphid Aphis craccivora Koch, 1854. The objective of this study was to evaluate the effects of silicon application on the resistance induction of lima bean plants, Phaseolus lunatus, to the black aphid A. craccivora. The experiment was conducted in the Entomology Laboratory of the Phytosanitary Sector of Centro de Ciências Agrárias, Universidade Federal do Piauí (UFPI), Brazil. The effects of the following treatments on biological aspects of the insect were evaluated: silicon applied to soil; silicon applied to soil + leaf; silicon applied to leaf; and control, without silicon application. The following biological variables were evaluated: generation period, reproductive period, and the fertility and daily average of produced nymphs per female. Plant silicon and lignin content were also evaluated. A 1% solution of silicic acid (2.0 g of product diluted in 200 mL of water) was applied around the plant stem (on soil), 15 days after emergence. Leaf application was performed with a 1-L spray, 5 days after the soil application. The non-preference of A. craccivora on lima beans was also evaluated. The evaluations were performed after 48 and 72 hours of infestation by counting nymphs and adults at each leaf section. Silicon application reduces nymph production, thereby interfering in the biological aspects of A. craccivora. Therefore, it can be used in cowpea pest management programs.(AU)


São poucos os registros no Brasil de insetos associados à cultura da fava; entre eles, destaca-se o pulgão preto Aphis craccivora Koch, 1854. O objetivo deste estudo foi avaliar os efeitos da aplicação de silício na indução de resistência de plantas de feijão-fava Phaseolus lunatus a esse inseto. O experimento foi conduzido no Laboratório de Entomologia do setor de Fitossanidade do Centro de Ciências Agrárias da Universidade Federal do Piauí (UFPI). Os efeitos da aplicação do silício sobre os aspectos biológicos do inseto foram avaliados utilizando os tratamentos: silício aplicado no solo, silício aplicado no solo + folha, silício aplicado à folha; e controle, sem aplicação de silício. Foram avaliadas as variáveis biológicas: duração do período pré-reprodutivo, período reprodutivo e fertilidade, e média diárias de ninfas produzidas por fêmea. Os teores de silício e de lignina nas plantas também foram avaliados. O ácido silícico foi aplicado em uma solução a 1% ao redor do caule das plantas (no solo), 15 dias após a emergência, diluindo-se 2,0 g do produto em 200 mL de água. Já a aplicação foliar foi realizada com um pulverizador de 1 L, 5 dias após a aplicação em solo. A não preferência de A. craccivora em feijão também foi avaliada. As avaliações foram realizadas após 48 e 72 horas da infestação, por meio da contagem de ninfas e adultos em cada secção foliar. A aplicação de silício promove a redução da produção de ninfas, interferindo nos aspectos biológicos de A. craccivora, podendo ser utilizado em programas de manejo de pragas do feijão-fava.(AU)


Subject(s)
Silicon , Phaseolus , Antibiosis , Pest Control , Insecta
7.
Article in English | WPRIM | ID: wpr-739166

ABSTRACT

Temporal hollowing is a contour deformity that results in a concavity or hollowing of the temporal region, causing significant cosmetic problems that affect patients both physically and psychologically. For these patients, cranioplasty is needed for protective coverage of the brain and to restore a pleasing aesthetic contour to the cranium. We report a case in which titanium mesh was used as a customized craniofacial implant for a bony defect and a silicone implant was used for soft tissue augmentation of muscle and to address temporal fat pad atrophy. The procedure resulted in high patient satisfaction from an aesthetic standpoint and, importantly, restored a functional barrier resistant to trauma.


Subject(s)
Adipose Tissue , Atrophy , Brain , Congenital Abnormalities , Humans , Patient Satisfaction , Silicon , Silicones , Skull , Temporal Bone , Temporal Lobe , Titanium
8.
Article in Korean | WPRIM | ID: wpr-738597

ABSTRACT

PURPOSE: Congenital double puncta are usually unilateral, and the accessory punctum exists on the medial side in a slit configuration that is distinct from the shape of the normal punctum. We report a case of an unusual case of double lacrimal puncta which the lateral, rather than the medial, punctum was judged to be the accessory punctum. CASE SUMMARY: A 39-year-old male patient with no underlying disease and no ophthalmologic history visited our clinic with right eye epiphora of 2 weeks duration. On slit lamp examination, double puncta were observed in the right lower eyelid and the remaining puncta were normal. On lacrimal syringing test and dacryocystography were performed and revealed incomplete obstruction with partial narrowing of the nasolacrimal duct. Silicone tube intubation was performed through the right lower medial punctum and symptoms improved postoperatively. CONCLUSIONS: The present case is an unusual case of double lacrimal puncta which has not been reported in Korea. Unlike the previous literature, the lateral, rather than the medial, punctum was judged to be the accessory punctum. Because accessory punctm can be present on the lateral side, it is necessary to distinguish between the accessory punctm and the main punctum through the accurate dacryocystography and lacrimal syringing test for the treatment of the patient.


Subject(s)
Adult , Eyelids , Humans , Intubation , Korea , Lacrimal Apparatus , Lacrimal Apparatus Diseases , Male , Nasolacrimal Duct , Silicon , Silicones , Slit Lamp
9.
Article in Korean | WPRIM | ID: wpr-766887

ABSTRACT

PURPOSE: To investigate the efficacy and factors affecting the success rates of nasolacrimal probing and silicone intubation (SI) in patients with congenital nasolacrimal duct obstruction (CNLDO). METHODS: We retrospectively reviewed the medical records of patients including 69 eyes of 59 patients who received probing and 61 eyes of 49 patients who received SI. In patients with probing, the age, sex, and history of conservative treatment were analyzed in the success and failure groups, and a success rate comparison was conducted by dividing these values into postnatal group 1 ( 12 months, the success rate of probing was lower than in patients 12 months.


Subject(s)
Humans , Intubation , Lacrimal Duct Obstruction , Logistic Models , Medical Records , Nasolacrimal Duct , Retrospective Studies , Silicon , Silicones
10.
Article in Korean | WPRIM | ID: wpr-766876

ABSTRACT

PURPOSE: We report a case of utilizing a previous silicone band track in the reoperation of scleral encircling. CASE SUMMARY: An 8-year-old male presented with rhegmatogenous retinal detachment in the right eye. Five days after this diagnosis, he received scleral buckling surgery and cryopexy to seal the retinal tear. One month after surgery, a fundus examination showed subretinal fluid at the inferior site of the scleral buckle. He underwent scleral encircling surgery and a cryopexy procedure. The patient has had an uneventful postoperative course, and the retina has remained attached over a follow-up period of 9 months. However, exotropia and hypotropia developed in the right eye. Diagnosis of restrictive strabismus due to tissue adhesion around the silicone band was made. The encircling band was therefore removed and laser photocoagulation was performed 360° around the retina. Twenty-four hours after surgery, a fundus examination showed subretinal fluid. He received 360° scleral encircling surgery not using the 360° conjunctival peritomy. After confirming a previous encircling tract using #0-0 polydioxanone as a guide, #5-0 Nylon was tied to the end of the guide and inserted through the encircling tract with the end sutured with the silicone band. The silicone band was inserted into the encircling tract by pulling the #5-0 Nylon as a guide. Ophthalmoscopy revealed an attached retina with indentation of the scleral buckle at 360°. CONCLUSIONS: For reoperation in patients who previously underwent scleral encircling surgery, using the previous scleral encircling tract may be effective in cases with conjunctival and tissue adhesion.


Subject(s)
Child , Diagnosis , Exotropia , Follow-Up Studies , Humans , Light Coagulation , Male , Nylons , Ophthalmoscopy , Polydioxanone , Reoperation , Retina , Retinal Detachment , Retinal Perforations , Retinaldehyde , Scleral Buckling , Silicon , Silicones , Strabismus , Subretinal Fluid , Tissue Adhesions
11.
Article in English | WPRIM | ID: wpr-765965

ABSTRACT

BACKGROUND/AIMS: Interstitial cells play important roles in gastrointestinal (GI) neuro-smooth muscle transmission. The underlying mechanisms of colonic dysmotility have not been well illustrated. We established a partial colon obstruction (PCO) mouse model to investigate the changes of interstitial cells and the correlation with colonic motility. METHODS: Western blot technique was employed to observe the protein expressions of Kit, platelet-derived growth factor receptor-α (Pdgfra), Ca²⁺-activated Cl⁻ (Ano1) channels, and small conductance Ca²⁺- activated K⁺ (SK) channels. Colonic migrating motor complexes (CMMCs) and isometric force measurements were employed in control mice and PCO mice. RESULTS: PCO mice showed distended abdomen and feces excretion was significantly reduced. Anatomically, the colon above the obstructive silicone ring was obviously dilated. Kit and Ano1 proteins in the colonic smooth muscle layer of the PCO colons were significantly decreased, while the expression of Pdgfra and SK3 proteins were significantly increased. The effects of a nitric oxide synthase inhibitor (L-NAME) and an Ano1 channel inhibitor (NPPB) on CMMC and colonic spontaneous contractions were decreased in the proximal and distal colons of PCO mice. The SK agonist, CyPPA and antagonist, apamin in PCO mice showed more effect to the CMMCs and colonic smooth muscle contractions. CONCLUSIONS: Colonic transit disorder may be due to the downregulation of the Kit and Ano1 channels and the upregulation of SK3 channels in platelet-derived growth factor receptor-α positive (PDGFRα⁺) cells. The imbalance between interstitial cells of Cajal-Ano1 and PDGFRα-SK3 distribution might be a potential reason for the colonic dysmotility.


Subject(s)
Abdomen , Animals , Apamin , Blotting, Western , Chloride Channels , Colon , Down-Regulation , Feces , Interstitial Cells of Cajal , Mice , Muscle, Smooth , Myoelectric Complex, Migrating , Nitric Oxide Synthase , Platelet-Derived Growth Factor , Silicon , Silicones , Small-Conductance Calcium-Activated Potassium Channels , Up-Regulation
12.
Article in English | WPRIM | ID: wpr-762866

ABSTRACT

BACKGROUND: The endoscopic transnasal approach is widely used for reconstructing the medial orbital wall by filling it with a silicone sheet or Merocel, but this technique has the disadvantage of retaining the packing for a long time. To overcome this drawback, a method of positioning an absorbable plate in the orbit has been introduced, but there is a risk of defect recurrence after the plate is absorbed. Here, the authors report the results of a novel surgical technique of placing a nonabsorbable titanium mesh with porous polyethylene into the orbit through the endoscopic transnasal approach. METHODS: Fourteen patients underwent surgery using the endoscopic transnasal approach. Preoperative computed tomography (CT) was used to calculate the size of the bone defect due to the fracture, and the titanium mesh was designed to be shorter than the anteroposterior length of the defect and longer than its height. The titanium mesh was inserted into the orbit under an endoscopic view. The authors then confirmed that the titanium mesh supported the orbital contents by pressing the eyeball and finished the operation. Immediately after surgery, CT results were evaluated. RESULTS: Postoperative CT scans confirmed that the titanium mesh was well-inserted and in the correct position. All patients were discharged without any complications. CONCLUSIONS: We obtained satisfactory results by inserting a titanium mesh with porous polyethylene into the orbit via the transnasal approach endoscopically.


Subject(s)
Endoscopy , Humans , Methods , Orbit , Polyethylene , Recurrence , Silicon , Silicones , Titanium , Tomography, X-Ray Computed
13.
Article in English | WPRIM | ID: wpr-762806

ABSTRACT

BACKGROUND: Implant-related deformities in aesthetic rhinoplasty are a major problem for rhinoplasty surgeons. Capsular contracture is believed to be the pathological cause of delayed contour deformities, comparable to breast implant-related contracture. This study investigated the prevalence of bacterial biofilms and other epidemiological factors related to capsular contracture in cases of silicone augmentation rhinoplasty. METHODS: Thirty-three patients who underwent corrective rhinoplasty due to a delayed contour deformity or aesthetic revision after implant rhinoplasty were studied from December 2014 to December 2016. All recruited patients received surgical correction by the authors. The patients were categorized by clinical severity into four grades. Demographic data and related confounding factors were recorded. Samples of capsular tissue and silicone removed from each patient were analyzed for the presence of a biofilm by ultrasonication with bacterial culture and scanning electron microscopy. RESULTS: Thirty-three paired samples of capsular tissue and silicone implants from the study group were analyzed. Biofilms were detected in one of 10 subjects (10%) with grade 1 contracture, two of four (50%) with grade 2 contracture, 10 of 14 (71.40%) with grade 3 contracture, and four of five (80%) with grade 4 contracture (P<0.05). The organisms found were Staphylococcus epidermidis (47.10%), coagulase-negative staphylococci (35.30%), and Staphylococcus aureus (17.60%). CONCLUSIONS: As with breast implant-related capsular contracture, silicone nasal augmentation deformities likely result from bacterial biofilms. We demonstrated the prevalence of biofilms in patients with various degrees of contracture. Implant type and operative technique seemed to have only vague correlations with biofilm presence.


Subject(s)
Asymptomatic Infections , Biofilms , Breast , Congenital Abnormalities , Contracture , Humans , Microscopy, Electron, Scanning , Prevalence , Rhinoplasty , Silicon , Silicones , Staphylococcus aureus , Staphylococcus epidermidis , Surgeons
14.
Article in English | WPRIM | ID: wpr-742110

ABSTRACT

PURPOSE: The aim of this study is to evaluate the effects of various primers on the microtensile bond strength (µTBS) of resin cements to cobalt-chromium (Co-Cr) dental casting alloy. MATERIALS AND METHODS: Four adhesive primers (Universal primer, Metal primer II, Alloy primer, and Metal/Zirconia primer) and two resin cements (Panavia F2.0, G-CEM LinkAce) were tested. One hundred fifty Co-Cr beams were prepared from Co-Cr ingots via casting (6 mm length × 1 mm width × 1 mm thick). The metal beams were randomly divided into ten groups according to the adhesive primers and resin cements used; the no-primer groups served as the control (n = 15). After sandblasting with aluminum oxide (125 µm grain), the metal and resin cements were bonded together using a silicone mold. Prior to testing, all metal-resin beams were examined under stereomicroscope, and subjected to the µTBS test. The mean value of each group was analyzed via one-way ANOVA with Tukey's test as post hoc (α = .05) using SPSS software. RESULTS: The mean µTBS of all groups was ranged from 20 to 28 MPa. There is no statistically significant difference between groups (P > .05). Mixed failure, which is the combination of adhesive and cohesive failures, is the most prevalent failure mode in both the Panavia F2.0 and G-Cem LinkAce groups. CONCLUSION: The µTBS of all tested groups are relatively high; however, the primers used in this study result in no favorable effect in the µTBS of Panavia F2.0 and G-Cem LinkAce resin cement to Co-Cr alloy.


Subject(s)
Adhesives , Alloys , Aluminum Oxide , Fungi , Resin Cements , Silicon , Silicones
15.
Article in English | WPRIM | ID: wpr-742077

ABSTRACT

PURPOSE: The aim of this study was to compare the effect of different finishing and polishing techniques on water absorption, water solubility, and microhardness of ceramic or glass-polymer based computer-aided design and computer-aided manufacturing (CAD/CAM) materials following thermocycling. MATERIALS AND METHODS: 150 disc-shaped specimens were prepared from three different hybrid materials and divided into five subgroups according to the applied surface polishing techniques. All specimens were subjected up to #4000 grit SiC paper grinding. No additional polishing has been done to the control group (Group I). Other polishing procedures were as follows: Group II: two-stage diamond impregnated polishing discs; Group III: yellow colored rubber based silicone discs; Group IV: diamond polishing paste; and Group V: Aluminum oxide polishing discs. Subsequently, 5000-cycles of thermocycling were applied. The analyses were conducted after 24 hours, 7 days, and 30 days of water immersion. Water absorption and water solubility results were analyzed by two-way ANOVA and Tukey post-hoc tests. Besides, microhardness data were compared by Kruskal-Wallis and Mann-Whitney U tests (P.05). CONCLUSION: Surface finishing and polishing procedures might negatively affect physical properties of hybrid ceramic materials. Nevertheless, immersion periods do not affect the microhardness of the materials. Final polishing by using diamond polishing paste can be recommended for all CAD/CAM materials.


Subject(s)
Absorption , Aluminum Oxide , Ceramics , Computer-Aided Design , Dental Polishing , Diamond , Immersion , Rubber , Silicon , Silicones , Solubility , Water
16.
Article in English | WPRIM | ID: wpr-742070

ABSTRACT

PURPOSE: Surface finishing of a zirconia restoration is essential after clinical adjustment. Herein, we investigated the effects of a surface finishing protocol for monolithic zirconia on final roughness and bacterial adherence. MATERIALS AND METHODS: Forty-eight disk-shaped monolithic zirconia specimens were fabricated and divided into four groups (n = 12) based on initial surface treatment, finishing, and polishing protocols: diamond bur+polishing bur (DP group), diamond bur+stone grinding bur+polishing bur (DSP group), no diamond bur+polishing bur (NP group), and no diamond bur+stone grinding bur+polishing bur (NSP group). Initial and final surface roughness was measured with a profilometer, and shown using scanning electron microscope. Bacterial adhesion was evaluated by quantifying Streptococcus mutans in the biofilm. Kruskal-Wallis and Mann-Whitney U tests were used to compare results among groups, and two-way analysis of variance was used to evaluate the effects of grinding burs on final roughness (α=.05). RESULTS: The DP group had the highest final Ra value, followed by the DSP, NP, and NSP groups. Use of the stone grinding bur as a coarse-finishing step significantly decreased final Ra values when a diamond bur was used (P < .001). Omission of the stone grinding bur increased biofilm formation on specimen surfaces. Combining a stone grinding bur with silicone polishing burs produced the smallest final biofilm values, regardless of the use of a diamond bur in initial surface treatment. CONCLUSION: Coarse finishing of monolithic zirconia with a stone grinding bur significantly decreased final Ra values and bacterial biofilm formation when surfaces had been roughened by a diamond bur.


Subject(s)
Bacterial Adhesion , Biofilms , Dental Instruments , Dental Polishing , Diamond , Silicon , Silicones , Streptococcus mutans
17.
Article in English | WPRIM | ID: wpr-760039

ABSTRACT

PURPOSE: To investigate the outflow characteristics of silicone tubes with intraluminal stents used in membrane-tube (MT) type glaucoma shunt devices. METHODS: The silicone tubes used in MicroMT (internal diameter of 100 µm with a 7-0 nylon intraluminal stent) and Finetube MT (internal diameter of 200 µm with a 5-0 nylon intraluminal stent) were connected to a syringe-pump that delivered a continuous flow of distilled water at flow rates of 2, 5, 10, and 25 µL/min. The pressures and resistances of tubes were measured at a steady flow rate with full-length, half-length, and absence of intraluminal stents. RESULTS: The mean outflow resistance of the two types of tubes ranged from 3.0 ± 1.9 to 3.8 ± 1.7 mmHg/µL/min with a full-length intraluminal stent, 1.8 ± 1.1 to 2.2 ± 1.1 mmHg/µL/min with a half-length intraluminal stent, and 0.1 ± 0.0 to 0.2 ± 0.0 mmHg/µL/min without an intraluminal stent. Theoretically, for a physiologic state with a flow rate of 2 µL/min and episcleral venous pressure of 6 mmHg, the mean pressures of tubes were expected to be 13.2 ± 3.0, 10.5 ± 2.4, and 6.4 ± 0.2 mmHg in MicroMT with full-length, half-length, and absence of intraluminal stents, respectively, and 12.5 ± 3.9, 9.6 ± 2.4, and 6.2 ± 0.2 mmHg in Finetube MT with full-length, half-length, and absence of intraluminal stents, respectively. The pressure variance also decreased with intraluminal stent retraction (p < 0.01). CONCLUSIONS: The small diameter tubes of 100 and 200 µm internal diameters, with 7-0 and 5-0 nylon intraluminal stents, respectively, used in the MT-type glaucoma shunt device showed safe and effective outflow characteristics.


Subject(s)
Glaucoma , Hydrodynamics , Intraocular Pressure , Nylons , Silicon , Silicones , Stents , Venous Pressure , Water
18.
São José dos Campos; s.n; 2019. 54 p. il., tab., graf..
Thesis in Portuguese | LILACS, BBO | ID: biblio-970414

ABSTRACT

O objetivo deste estudo foi avaliar a Deposição Química na Fase Vapor Assistido por Plasma (PECVD) com hidreto de silício (SiH4) em zircônia VITA YZ HT em diferentes tempos, bem como os seus efeitos nas características superficiais do material e na união ao cimento resinoso antes e após a termociclagem. Blocos de zircônia Vita YZ HT foram obtidos, polidos, sinterizados e divididos em 5 grupos, de acordo com o tempo de PECVD (n = 31): Zr-30 (30s), Zr-60 (60s), Zr-120 (120s) e Zr-300 (300s). O grupo controle (Zr-0) não recebeu deposição. Análises de DRX, FTIR, EDS, FE-SEM, XPS, goniometria e perfilometria foram utilizadas para caracterização química e topográfica. O silano Monobond N foi aplicado na superfície e um cilindro de cimento resinoso (Variolink N) foi confeccionado (3 × 3 mm). Metade dos espécimes de cada grupo foi armazenada por 24 h ou submetida à termociclagem (6 × 10³ ciclos). Teste de resistência ao cisalhamento (SBS) foi realizado. Os resultados foram submetidos aos testes one-way Anova e Tukey (α = 0,05). Para os grupos experimentais, o XPS mostrou que a formação de ligações Si-O contribuiu para o aumento da Energia Livre de Superfície (ELS). MEV-FEG e EDS mostraram que quanto maior o tempo de deposição, maior a quantidade de silício na superfície, apresentando apenas fase tetragonal. Zr-60 e Zr-300 apresentaram maior e menor rugosidade superficial, respectivamente. O silício penetrou na microestrutura, causando maior concentração de tensão. A resistência de união ao cimento resinoso foi melhorada após todos os tempos de deposição da PECVD. Portanto, a técnica de PECVD com o composto químico SiH4 associada ao tratamento químico com primer universal baseado em metacrilato de silano é uma alternativa promissora para a manutenção da ligação entre cimento resinoso e zircônia HT(AU)


The aim of this study was to evaluate the effect of Plasma-enhanced Chemical Vapor Deposition (PECVD) with silicon hydride (SiH4) on VITA YZ HT zirconia at different times, as well as its effects on material surface characteristics and bonding to resin cement before and after thermocycling. Blocks of VITA YZ HT zirconia were obtained, polished, sintered, and divided into five groups, according to PECVD time (n = 31): Zr-30 (30 s), Zr-60 (60 s), Zr-120 (120 s), and Zr-300 (300 s). The control group (Zr-0) did not receive deposition. XRD, FTIR, EDS, FE-SEM, XPS, goniometry, and profilometry analyses were used for chemical and topographic characterization. Monobond N silane was applied to the surface, and a cylinder of resin cement (Variolink N) was made (3 × 3 mm). Half of the specimens of each group were stored for 24 h or subjected to thermocycling (6 × 10³ cycles). A shear bond strength (SBS) test was performed. Results were subjected to one-way ANOVA and Tukey's tests (α = 0.05). For experimental groups, XPS showed that formation of Si-O bonds contributed to increased Surface Free Energy (SFE). FE-SEM and EDS showed that the longer the deposition time, the greater the amount of silicon on the surface, presenting only a tetragonal phase. Zr-60 and Zr-300 presented higher and lower surface roughnesses, respectively. The silicon penetrated the microstructure, causing higher stress concentrations. The bond strength to resin cement was improved after all PECVD deposition times. Thus, the PECVD technique with the chemical compound SiH4, associated with chemical treatment with universal primer based on silane methacrylate, is a promising alternative for maintaining bonding between resin cement and HT zirconia(AU)


Subject(s)
Humans , Silicon/administration & dosage , Aging , Shear Strength , Dental Materials
19.
Article in Korean | WPRIM | ID: wpr-759677

ABSTRACT

In this study, marginal and internal discrepancies of zirconia crowns fabricated with the CAD/CAM (computer aided design


Subject(s)
Crowns , Methods , Molar , Replica Techniques , Shoulder , Silicon , Silicones , Tomography, X-Ray Computed , Tooth
20.
Article in English | WPRIM | ID: wpr-759502

ABSTRACT

BACKGROUND: Compared to an equivalent sized polyvinyl chloride (PVC) double-lumen tube (DLT), a silicone DLT has a shorter endobronchial segment. The aim of this study was to compare the incidence of clinically significant displacement of left-sided PVC and silicone DLTs after a positional change to a lateral position from a supine position and determine its effect on the need for DLT repositioning for successful lung separation in patients undergoing thoracic surgery. METHODS: One hundred eight adult patients requiring one-lung ventilation were randomly divided into group P (PVC DLT, n = 54) and group S (Silicone DLT, n = 54). The position of the DLT was observed before and after lateral positioning to assess the effect of the position change. The incidence of clinically significant displacement (>10 mm) of DLT was compared between the groups. RESULTS: DLTs were clinically significantly displaced in group P (17/48, 35.4%) and group S (18/52, 34.6%) after lateral positioning (p = 0.933). A proximal displacement (31.3% [group P] and 25.0% [group S]) was more common than distal displacement (4.2% [group P] and 9.6% [group S]), with no significant intergroup difference (p = 0.494). After lateral positioning, critical malposition of DLT with bronchial herniation to the right main bronchus was 8.3% (group P) and 7.9% (group S, p = 0.906). CONCLUSION: Left-sided PVC and silicone DLTs produced comparable incidences of clinically significant displacement and, consequently, required similar rates of repositioning for successful lung separation after lateral positioning.


Subject(s)
Adult , Bronchi , Bronchoscopy , Humans , Incidence , Intubation, Intratracheal , Lung , One-Lung Ventilation , Polyvinyl Chloride , Polyvinyls , Posture , Silicon , Silicones , Supine Position , Thoracic Surgery , Thoracic Surgical Procedures
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