Analysis of diametrical wear of grinding wheel and roundness errors in the machining of steel VC 131

Due to the high industrial competitiveness, the rigorous laws of environmental protection, the necessary reduction of costs, the mechanical industry sees itself forced to worry more and more with the refinement of your processes and products. In this context, can be mentioned the need to eliminate the roundness errors that appear after the grinding process. This work has the objective of verifying if optimized nozzles for the application of cutting fluid in the grinding process can minimize the formation of the roundness errors and the diametrical wear of grinding wheel in the machining of the steel VC 131 with 60 HRc, when compared to the conventional nozzles. These nozzles were analyzed using two types of grinding wheels and two different cutting fluids. Was verified that the nozzle of 3mm of diameter, integral oil and the CBN grinding wheel, were the best options to obtain smaller roundness errors and the lowest diametrical wears of grinding wheels.

Histomorphometric analysis of homogenous demineralized dentin matrix as osteopromotive material in rabbit mandibles

Purpose: The aim of this work was to evaluate the effectiveness of homogenous demineralized dentin matrix (HDDM) slices in surgical bone defects created in the mandibles of rabbits and occluded with a polytetrafluoroethylene (PTFE) membrane in the promotion of bone growth. Materials and Methods: Surgical bone defects were created in 36 adult rabbits and divided into 4 groups: bone defect (control), bone defect with PTFE membrane, bone defect with HDDM, and bone defect with both HDDM and a PTFE membrane (HDDM + PTFE). The rabbits were sacrificed after 30, 60, and 90 days, and the bone defects were examined histologically and by histomorphometric analysis (analysis of variance and the Tukey test). Results: The volume of newly formed bone matrix was significantly greater in the HDDM and HDDM + PTFE groups than in the control and PTFE groups. The discrete inflammatory reaction found in the HDDM and HDDM + PTFE groups did not prevent the osteopromotive activity of the dentin matrix. Discussion: HDDM slices were biocompatible and were resorbed during the bone remodeling process. They stimulated the newly formed bone until 30 days after implantation. Conclusion: Bone repair was accelerated in the bone defects treated with HDDM in comparison to the control group.

A preliminary report on the effect of laser therapy on the healing of cutaneous surgical wounds as a consequence of an inversely proportional relationship between wavelength and intensity: Histological study in rats

Objective: The objective of the present investigation was to assess the histological effects of different wavelengths and intensities on the healing process of cutaneous wounds. Background Data: Tissue repair is a dynamic interactive process which involves mediators, cells and extra-cellular matrix. Several reports on the use of laser therapy have shown that the healing process is positively affected when the correct parameters are used. Methods: Eighteen standardized wounds were surgically created on the dorsum of male and female Wistar rats, which were subsequently divided into two experimental groups according to wavelength used λ.670 or λ685 nm) for lasertherapy (LLLT). Each group was divided into three subgroups of three animals according to the intensity of the applied irradiation (2,15, or 25 mW). Twelve animals were used as entreated controls and were not irradiated. The irradiation was carried out during seven consecutive days. The animals were sacrificed eight days after surgery. The specimens were removed, kept in 4% formaldehyde for 24 h, routinely prepared to wax, stained with H&E, and analyzed under light microscopy. Results: For both groups, light microscopy showed a substitution repair process; however, when LLLT was used, a positive biomodulatory effect was detectable, chiefly associated with shorter wavelength and low intensity. Conclusions: The results of the present study indicate that LLLT improved cutaneous wound repair and that the effect is a result of an inversely proportional relationship between wavelength and intensity, with treatment more effective when combining higher intensity with short wavelength or lower intensity with higher wavelength.

The effect of low intensity laser therapy on wound healing in Streptozotocin-induced diabetic rats

Diabetes Mellitus is a condition that results in a delay of the wound healing process, that is associated with an insufficient production of collagen, a decrease of the amount of collagen fibrils and deficient blood flow in the wound area. It is suggested that Low Intensity Laser Therapy acts by improving wound healing in normal organisms, accelerating tissue regeneration. The aim of this work was to investigate the biostimulatory effect of the HeNe laser irradiation, at 632.8 nm, on wound healing in 15 male rats suffering from diabetes induced by Streptozotocin, compared to 15 control diabetic animals. Irradiation parameters were: laser power of 15mW, exposition time of 17 s., irradiated area of 0.025 cm 2 and laser energy density of 10 J/cm 2. Full-thickness skin squared samples, with 5 mm of non-injured tissue around the wound, were obtained at 4, 7 and 15 days after wounding procedure (5 treated and 5 control animals each time). The histopathologic analysis performed by haematoxylin-eosin staining. Results suggested that the irradiation of diabetic rats was efficient for wound healing. Treated group presented better quality of the wound tissues by the macroscopic observation than control group and the microscopic analysis demonstrated that treated animals had better histopathologic evaluation than non treated.

Porous polyethylene for tissue engineering applications in diabetic rats treated with calcitonin: Histomorphometric analysis

Purpose: The purpose of this work was to study the bone tissue reaction after porous polyethylene (Polipore) implantation into surgical defects in the parietal bones of rats with streptozotocin-induced diabetes, treated with salmon calcitonin. Materials and Methods: Porous polyethylene implants were placed in bone defects created in 36 adult female rats. The rats were divided into 3 equal groups: diabetic treated with calcitonin (DCa), diabetic (D), and control (C). The animals of the DCa group received applications of salmon calcitonin on alternating days immediately after the surgery until sacrifice. The rats were sacrificed after 15, 30, 60, and 90 days, and the defects were examined histologically and statistically through histomorphometric analysis. Results: Histomorphometric analysis showed that there was no statistically significant difference in the mean quantity of inflammatory cells among all study groups after 15 and 90 days. At 30 days, a statistically significant difference was observed between the D and C groups and the D and DCa groups. At 60 days, there was no statistically significant difference between the D and DCa groups. Discussion: Porous polyethylene can be considered an option for implant material when there are investigations that prove its biocompatibility and stability in the host tissues. Salmon calcitonin positively aided the bone repair and attenuated the inflammatory response until 30 days after the surgery. Conclusion: Porous polyethylene was tolerated by the host tissues in all groups, and moderate chronic inflammatory reaction was observed up to the 90-day period. Salmon calcitonin attenuated the inflammatory response up until 30 days.

Development and validation of an UV spectrophotometric method for determination of gatifloxacin in tablets

A simple, sensitive and accurate spectrophotometric method was developed for the assay of gatifloxacin in raw material and tablets. Validation of the method yielded good results concerning range, linearity, precision and accuracy. The absorbance was measured at 287 nm for gatifloxacin tablet solutions. The linearity range was found to be 4.0-14.0 μg/mL for gatifloxacin. It was also found that the excipients in the commercial tablets did not interfere with the method.

Determination of flutamide in tablets by high-performance liquid chromatography

Flutamide is a potent antiandrogen used for the treatment of prostatic cancer. A simple, sensitive and accurate high-performance liquid Chromatographic (HPLC) method is presented for quantitative determination of flutamide in tablets, using a reversed-phase technique and UV detection at 240 nm. The isocratic elution was used to quantify the analyte. The samples were chromatographed on Luna-C18 column and the mobile phase was 0.05 M phosphate buffer pH 4.0 - acetonitrile (50:50, v/v). The method was linear between 2.9 - 11.6 mg L -1. Over the tested concentration range the intra-day relative standard deviation for replicate analysis in tablets ranged from 0.44 to 0.78%. It was also found that the excipients in the commercial tablets did not interfere with the method.

Microbiological assay for the determination of azithromycin in ophthalmic solutions

The validation of a simple, sensitive and specific agar diffusion bioassay, applying cylinder-plate method, for the determination of the antibiotic azithromycin in ophthalmic solutions is described. Using a strain of Bacillus subtilis ATCC 9372 as the test organism, azithromycin at concentrations ranging from 50.0 to 200.0 μg·mL-1 could be measured in 1.666 7 mg·mL-1 ophthalmic solutions. A prospective validation of the method showed that the method was linear (r = 0.999 9) and precise (RSD = 0.70) and accurate (it measured the added quantities). The results obtained by bioassay method could be statistically calculated by linear parallel model and by means of regression analysis and verified using analysis of variance (ANOVA). We conclude that the microbiological assay is satisfactory for quantification of azithromycin in ophthalmic solutions.

Validation of UV spectrophotometric method for determination of lomefloxacin in pharmaceutical dosage form

A simple and reproducible method was developed for the assay of lomefloxacin in tablets. The excipients in the commercial tablet preparation did not interfere with the assay. Beer's law is obeyed in the range 2.0-9.0 μg.mL-1 at λmax 280 nm. The molar absorptivity was calculated. Six triplicate analyses of solutions containing six different concentrations of the examined drug were carried out and gave a mean correlation coefficient 0.9997. The proposed method was applied to the determination of the examined drug in coated tablet and the results demonstrated that the method is equally accurate, precise and reproducible as the official methods.

Photodegradation of sparfloxacin and isolation of its degradation products by preparative HPLC

Sparfloxacin, a third generation fluoroquinolone derivative, is a potent antibacterial agent active against a wide range of Gram-positive and Gram-negative organisms including Streptococcus pneuinoniae, Staphylococcus aureus, methicillin resistant S. aureus, Legionella spp., Mycoplasina spp., Chlamydia spp. and Mycobacterium spp. A drawback of fluoroquinolones is their photoreactivity. Sparfloxacin has been studied in terms of therapeutic activities. However, there are few published of analytical methods being applied to sparfloxacin. The aim in this study was to determine the photodegradation products of sparfloxacin, when submitted to UV light, and to characterize two of these products, designated SPAX-PDP1 and SPAX-PDP2. An accelerated study of stability in methanol solution was carried out by exposing a solution of sparfloxacin to UV light (peak wavelength 290 nm) for 36 hours at room temperature. The products were analyzed by NMR spectrophotometry, IR spectrometry and mass spectrophotometry. The results suggest that the products isolated here could be used to estimate the degradation of sparfloxacin in a stability study. However, the low activity exhibited by UV-irradiated sparfloxacin is a source of concern that demands further investigation of the mechanism of its photodegradation mechanism.

Byrsonima crassa Niedenzu (IK): Antimicrobial activity and chemical study

The methanolic extract of leaves from Byrsonima crassa, a Brazilian medicinal plant, was analyzed by CC and HPLC. Four constituents were isolated and identified as quercetin, methyl gallate, (-)-epigallocatechin gallate and quercetin-3-O-(2″-galloyl)-α-L-arabinopyranoside. The methanolic and hydromethanolic extract, as well as fractions, were evaluated regarding their possible antimicrobial activity using in vitro methods. Results showed that both extracts and fractions exhibited significant antimicrobial activity against all tested strains.

Análise térmica de esparfloxacino

Sparfloxacin, a third-generation fluoroquinolone, is a potent antibacterial agent against a wide range of Gram-positive and Gram-negative organisms, for example Streptococcus pneumonias, Staphylococcus aureus (including methicillin-resistant strains), Legionella spp., Mycoplasma spp., Chlamydia spp. and Mycobacterium spp. This compound has been submitted to thermal analysis and the results are presented here. The DSC curve of sparfloxacin has an endothermic peak that indicates a melting point at 276.5 °C. The DTA curve of the sample in synthetic air shows two exothermic peaks, at 341.6 and 579.2 °C, attributed to compound decomposition. In the TG curve, the loss of mass can be seen to occur in two steps between 285.5 and 645.3 °C. The DTA curve obtained in a nitrogen atmosphere shows an exothermic peak, with decomposition of sparfloxacin at 340.0 °C; from the corresponding TG plot, the loss of mass starts at 254.4 °C.

Ação farmacológica de Syzygium cumini (L.) skeels

Natural products have received new interest recently, maybe in men's attempt to turn into the nature for the prevention and the relief of diseases, mainly because of those untreated by the traditional medicine. Syzygium cumini (L.) Skeels, popularly known as 'jambolão, is a well-known plant by several pharmacological actions so much in the popular use as in the scientific literature. In this search antidiabetic, anti-diarrhoeal, anti-inflammatory, antioxidant and antimicrobial activities of 'jambolão' were described, among other actions.

Evaluation of antidiarrhoeal effects of Psidium guajava L. (Myrtaceae) aqueous leaf extract in mice

A crude aqueous extract of the leaves of the guava tree, Psidium guajava L. (Myrtaceae), were studied for antidiarrhoeal effects, to place one of its traditional medical uses. The extract induced a decrease in the propulsive movements of the intestinal contents in mice. These findings suggested that an aqueous extract of guava leaves may be used as an effective treatment for non-specific diarrhoea in folk medicine.

Inactivation of vesicular stomatitis virus through inhibition of membrane fusion by chemical modification of the viral glycoprotein

Membrane fusion is an essential step in the entry of enveloped viruses into their host cells triggered by conformational changes in viral glycoproteins. We have demonstrated previously that modification of vesicular stomatitis virus (VSV) with diethylpyrocarbonate (DEPC) abolished conformational changes on VSV glycoprotein and the fusion reaction catalyzed by the virus. In the present study, we evaluated whether treatment with DEPC was able to inactivate the virus. Infectivity and viral replication were abolished by viral treatment with 0.5 mM DEPC. Mortality profile and inflammatory response in the central nervous system indicated that G protein modification with DEPC eliminates the ability of the virus to cause disease. In addition, DEPC treatment did not alter the conformational integrity of surface proteins of inactivated VSV as demonstrated by transmission electron microscopy and competitive ELISA. Taken together, our results suggest a potential use of histidine (His) modification to the development of a new process of viral inactivation based on fusion inhibition. © 2006 Elsevier B.V. All rights reserved.