In vitro photoinactivation of bovine mastitis related pathogens.

Background: Bovine mastitis is considered the most important disease of worldwide dairy industry. Treatment of this disease is based on the application intramammary antibiotic, which favors an increase in the number of resistant bacteria in the last decade. Photodynamic inactivation (PDI) has been investigated in different areas of Health Sciences, and has shown great potential for inactivating different pathogens, without any selection of resistant microorganisms.

Labeling polyamidoamine (PAMAM) dendrimers with technetium-99m via hydrazinonicotinamide (HYNIC).

Dendrimers are branched nanomolecules, with a three dimensional structure, very low polydispersity and high functionality. Poly(amidoamine) (PAMAM) dendrimers are the most investigated class of dendrimers. In this study, PAMAM G4 dendrimer conjugated with HYNIC (hydrazinonicotinamide), an efficient bifunctional chelator, was characterized.

Na, K, Ca, Mg, and U-series in fossil bone and the proposal of a radial diffusion-adsorption model of uranium uptake.

Fossil bones are often the only materials available for chronological reconstruction of important archeological sites. However, since bone is an open system for uranium, it cannot be dated directly and therefore it is necessary to develop models for the U uptake. Hence, a radial diffusion-adsorption (RDA) model is described.

Comparative analysis of root surface smear layer removal by different etching modalities or erbium:yttrium-aluminum-garnet laser irradiation. A scanning electron microscopy study.

The purpose of this study was to evaluate the effect of erbium:yttrium-aluminum-garnet (Er:YAG) laser (2.94 mum) irradiation on the removal of root surface smear layer of extracted human teeth and to compare its efficacy with that of citric acid, ethylenediamine tetra-acetic acid (EDTA), or a gel containing a mixture of tetracycline hydrochloride (HCl) and citric acid, using scanning electron microscopy (SEM). Thirty human dentin specimens were randomly divided into six groups: G1 (control group), irrigated with 10 ml of physiologic saline solution; G2, conditioned with 24% citric acid gel; G3, conditioned with 24% EDTA gel; G4, conditioned with a 50% citric acid and tetracycline gel; G5, irradiated with Er:YAG laser (47 mJ/10 Hz/5.

Optical properties of metacycline, oxytetracycline and chlortetracycline europium complexes in the presence of hydrogen peroxide.

Tetracycline possesses a great tendency to form complexes with a number of chemical species, particularly with Eu3+ ions. In this work we investigate the europium optical properties of three tetracyclines europium complexes: Metacycline (MTc), Oxytetracycline (OTc), and Chlortetracycline (CTc), in the presence and absence of hydrogen peroxide (HP). The results show that the emission band of EuOTc have enhancement in the presence of hydrogen peroxide.

Diagonal scan measurement of Cr:LiSAF 20 ps ablation threshold.

We report the measurement of the 20 ps ablation threshold of pure and Cr(3+) doped LiSAF samples using a simple method that employs a single scan of the sample across a focused laser beam waist. During the scan, a profile is etched in the sample surface, and the measurement of the maximum transversal size of the profile and the pulse peak power determine the ablation threshold, without any further knowledge of the beam geometry. Also, it was possible to measure the depth of the ablation profile, to calculate its effective volume, and to identify that the maximum material removal rate per pulse does not occur at the beam waist, which is not intuitively expected.

Distinct human prolactin (hPRL) and growth hormone (hGH) behavior under bacteriophage lambda PL promoter control: temperature plays a major role in protein yields.

When producing recombinant protein for therapy, it is desirable not only to obtain substantial amounts of the protein, but also to make sure that potential contaminants such as inducing agents are not present in the final product. To prevent this, one can use expression systems in which the promoter (lambdaP(L)) is activated by a temperature shift that denatures a repressor (e.g.

Investigation of the radiation risk due to environmental contamination by 241Am from lightning rods disposed at uncontrolled garbage dumps.

Radioactive lightning rods were manufactured in Brazil until 1989, when the licenses for using radioactive sources in these products were lifted by the national nuclear authority. Since then, these rods have been replaced by the Franklin type and collected as radioactive waste. However, only 20% of the estimated total number of installed rods has been delivered to the Brazilian Nuclear Commission.

Optimization of radioactive waste storage.

In several countries, low-level radioactive wastes are treated and stored awaiting construction and operation of a final repository. In some cases, interim storage may be extended for decades requiring special attention regarding security issues. The International Atomic Energy Agency (IAEA) recommends segregation of wastes that may be exempted from interim storage or ultimate disposal.

Partitioning of radionuclides and trace elements in phosphogypsum and its source materials based on sequential extraction methods.

Phosphogypsum is a waste produced by the phosphate fertilizer industry. Although phosphogypsum is mainly calcium sulphate dihydrate, it contains elevated levels of impurities, which originate from the source phosphate rock used in the phosphoric acid production. Among these impurities, radionuclides from 238U and 232Th decay series are of most concern due to their radiotoxicity.

Changes in chemical composition and collagen structure of dentine tissue after erbium laser irradiation.

Erbium laser radiation has a great affinity for the water molecule, which is present in quantity in biological hard tissues. The objective of this work is to identify chemical changes by infrared spectroscopy of irradiated dentine by an Er:YAG-2.94 microm laser.

Crystalline structure of dental enamel after Ho:YLF laser irradiation.

Irradiation of teeth with lasers using specific wavelengths and energy densities produces surface melting. This effect has been already applied to different procedures such as caries prevention and hypersensitivity reduction. The aim of this study is to characterize the crystalline structure of bovine enamel after holmium laser irradiation.

Evaluation of indoor gamma radiation dose in dwellings.

The use of materials containing naturally occurring radionuclides for house construction may enhance the natural radiation background to which some population groups are exposed. External exposure results from gamma emitter radionuclides existing in the walls, floor and ceiling. Mathematical models can be used to predict external dose rates inside a room, provided the compartment geometry and the radionuclide concentration activities are known.

Management of spent sealed radiation sources.

Spent or disused sealed radiation sources--no longer needed sources--may represent a risk of radiological accident or may be a target for criminal acts in countries where final disposal options are unavailable and where an increasing number of sources are being kept in extended storage. In developing countries, thousands of radium needles, teletherapy sources, oil well logging neutron sources, and miscellaneous industrial radioactive gauges are annually collected as waste and stored in research institutes. The objectives of the study described in this paper are to inventory such sources in Brazil, including those presently in use and those already collected as waste, and to design a dedicated repository where spent sources could be disposed of properly.

Dental discolouration after thermal treatment.

Enamel and dentin discolouration have extrinsic and intrinsic origins. Possible causes include pigmented food or drink, caries, clinical chemical treatments, trauma and, high temperature. In the oral cavity, dental hard tissues can be heated when irradiated with high-intensity lasers.

Reconnaissance of submarine groundwater discharge at Ubatuba coast, Brazil, using 222Rn as a natural tracer.

Submarine groundwater discharge (SGD), which includes fresh groundwater and recycled seawater, has been recognized as a widespread phenomenon that can provide important chemical elements to the ocean. Several studies have demonstrated that SGD may approach or even exceed freshwater sources in supplying nutrients to coastal zones. This work reports preliminary results of a study carried out in a series of small embayments of Ubatuba, São Paulo State, Brazil, covering latitudes between 23 degrees 26'S and 23 degrees 46'S and longitudes between 45 degrees 02'W and 45 degrees 11'W.

Retrospective study of the iodine-131 contamination of workers in the radiopharmaceutical industry.

A dose reconstruction study was performed for personnel occupationally exposed to 131I in radiopharmaceutical production, during the years 1981 to 1994, with the objective of estimating committed effective doses and critically reviewing the main causes of their exposures. The workers were selected from a group responsible for the production, labelling and distribution of all radiopharmaceutical material in Brazil. Best estimates of intakes and doses were derived from the examination of the individual monitoring records and the reports from the radiation protection supervisor, complemented by interviews with the workers and with radiation protection officers.