Preparation and evaluation of an experimental luting glass ionomer cement to be used in dentistry

The aim of this paper is to compare the fluoride-releasing and mechanical properties of an experimental luting glass ionomer cement, which has a modified composition and a commercial luting cement. The experimental powder was obtained by sol–gel process and then, it was used to prepare the experimental cements. The properties of cement pastes, such as setting time and working time, microhardness and diametral tensile strength were determined. Fluoride release from GICs was evaluated at time intervals of 1, 7, 14, 21 and 28 days in deionized water. Atomic force microscopy (AFM) analyses showed that the surface of the experimental cements is more homogeneous than commercial GICs. The mechanical properties and the measure of liberation of fluoride of the two cements were influenced by ratio powder:liquid and chemical composition of the precursor powders. Experimental cements released less fluoride than commercial cements. However, this liberation was more constant during the analyzed period. Thus, the results obtained in this study indicated that the composition of the experimental powder modified by the niobium can lead the formation of the polysalt matrix with good mechanical properties. In other words, we can say that experimental powder offered considerable promise for exploitation in dental field.     

Mercury contamination in fish from gold mining areas in Indonesia and human health risk assessment

This study investigates the effects on fish and assesses human health hazards from mercury released in two gold mining areas in Indonesia: Tatelu (North Sulawesi Province) and Galangan (Katingan District, Central Kalimatan Province). In Tatelu, 154 fish specimens of 10 freshwater species were collected, as well as five marine species from the fish market. The mean concentration of total mercury in muscles of freshwater fish from this area was 0.58+/-0.44 microg/g, with more than 45% of fish having Hg levels above the WHO guideline for human consumption of 0.5 microg/g. In Galangan, where 263 fish specimens of 25 species were collected, the total mercury in muscles averaged 0.25+/-0.69 microg/g. Excluding data from flooded open pits in sub-area P4, mean Hg levels in fish from Galangan were 2 to 4 times lower than 0.5 microg/g, while fewer than 10% of fish from Galangan exceeded WHO guidelines. The Hazard Quotient (HQ) was applied to both areas to determine the threat of MeHg exposure for communities in both areas. The HQ is a risk assessment indicator which defines the ratio of exposure level to a single substance in relation to a reference dose. Samples from Tatelu (excluding marine species) had an HQ above one, while those from Galangan resulted in values of 2.4 for the whole area and 9.9 for sub-area P4, pointing to potentially harmful fish consumption for the local population. By using the single-compartment model to estimate mercury levels in blood and hair from daily intake dose, sub-area P4 showed the highest levels, higher than the upper limit guideline for pregnant women, but still lower than threshold levels associated with observed clinical effects.     

Water and Gallium at Absolute Negative Pressures. Loci of Maximum Density and of Melting

Several physical properties of liquids as well as those of the coexistence between liquid and solid can be determined at absolute negative pressures. Examples for this include thermal pressure coefficients, loci of temperature of maximum density, melting lines, speed of propagation of low-intensity sound waves, and (p, T, x) conditions of occurrence of liquid/liquid phase separation. Three model temperature-pressure cycles, which allow for the measurement of temperature-pressure conditions of the occurrence of maxima of liquid density, negatively sloped fusion lines, and the upper critical solution temperature (UCST) of liquid solutions in these metastable regimes are described. A new apparatus for measuring negative pressures was developed. The temperature and pressure are determined within an uncertainty of ±0.05°C and ±5 bar, respectively. Water and heavy water have been used as testing systems with respect to the location of their temperatures of maximum density (TMD) loci. Empirical equations of state whose parameters have been fitted to experimental data located in the normal positive pressure region have proven to extrapolate well to the negative pressure regime. Furthermore, an attempt was made to use SAFT in order to provide a more theoretically founded framework. Preliminary results for gallium have shown that a TMD exists 45 K inside the supercooled regime, and that the continuation of its melting line down to –80 bar evolves with a slope of –515±25 bar·K^–1.     

A hybrid linear-neural model for time series forecasting

This paper considers a linear model with time varying parameters controlled by a neural network to analyze and forecast nonlinear time series. We show that this formulation, called neural coefficient smooth transition autoregressive model, is in close relation to the threshold autoregressive model and the smooth transition autoregressive model with the advantage of naturally incorporating linear multivariate thresholds and smooth transitions between regimes. In our proposal, the neural-network output is used to induce a partition of the input space, with smooth and multivariate thresholds. This also allows the choice of good initial values for the training algorithm.     

Shrinkage of digested sludge from gelatin production

This study evaluated the influence of temperature on the apparent density, porosity and shrinkage of sludge during drying experiments conducted in a drying oven, under three different temperatures. Also, the apparent density behavior and porosity during the drying were evaluated. The influence of temperature was evident in all evaluated parameters. However, the behaviors are distinct for each temperature range due the case hardening phenomenon. The volumetric shrinkage of the dimensions was correlated linearly by Perez and Calvelo modified model. During drying, the apparent density and porosity exhibited variations in behavior, related to drying rates and critical moisture content.     

Post-translational modifications of alpha5beta1 integrin by glycosaminoglycan chains. The alpha5beta1 integrin is a facultative proteoglycan

Cell-fibronectin interactions, mediated through several different receptors, have been implicated in a wide variety of cellular properties. Among the cell surface receptors for fibronectin, integrins are the best characterized, particularly the prototype alpha5beta1 integrin. Using [125I]iodine cell surface labeling or metabolic radiolabeling with sodium [35S]sulfate, we identified alpha5beta1 integrin as the only sulfated integrin among beta1 integrin heterodimers expressed by the human melanoma cell line Mel-85. This facultative sulfation was confirmed not only by immunoprecipitation reactions using specific monoclonal antibodies but also by fibronectin affinity chromatography, two-dimensional electrophoresis, and chemical reduction. The covalent nature of alpha5beta1 integrin sulfation was evidenced by its resistance to treatments with high ionic, chaotrophic, and denaturing agents such as 4 M NaCl, 4 M MgCl2, 8 M urea, and 6 M guanidine HCl. Based on deglycosylation procedures as chemical beta-elimination, proteinase K digestion, and susceptibility to glycosaminoglycan lyases (chondroitinase ABC and heparitinases I and II), it was demonstrated that the alpha5beta1 heterodimer and alpha5 and beta1 integrin subunits were proteoglycans. The importance of alpha5beta1 sulfation was strengthened by the finding that this molecule is also sulfated in MG-63 (human osteosarcoma) and HCT-8 (human colon adenocarcinoma) cells.     

Squamous cell carcinoma of the prostate. Presentation of a case and review of the literature

The authors report the case of a young patient with an aneurysm of the ascending aorta and moderate aortic incompetence, who underwent a conservative operation at our institution. Dilatation of the sinotubular junction, particularly at the level of the non-coronary sinus of the aortic valve with loss of coaptation between the corresponding leaflet and the two coronary leaflets, was identified at the time of surgery as major cause of valve insufficiency. During surgery, the dilated ascending aorta and pathologic aortic sinus were replaced with a 26 Hemashield prosthesis tailored according to the David guidelines. An intraoperative post-repair transesophageal echo exam showed that the aortic valve appeared to be working competently. The post-operative course was uneventful and at one year, an echographic check of the aortic valve showed that it was fully competent, with normal leaflet motion. Conservative surgery can be a good option in selected patients with ascending aortic aneurysm and aortic valve insufficiency.     

Characterization and Dissolution Study of Oxodipine from Solid Binary Systems

Thennomicroscopy and differential scanning calorimetry were employed to characterize solid binary systems prepared with oxodipine and PEG 6000, 2-hydroxypropyl-β-cyclodextrin or mannitol. DSC curves did not allow to diferentiate physical mixtures from solid dispersions. Thennomicroscopy revealed the interactions that can be produced between drug and each carrier, due to heat contribution, when the physical mixtures were observed; also this thermal technique permited us to ascertain the composition of particles that constitute the solid dispersions. Dissolution studies showed that the amelioration obtained in oxodipine dissolution from physical mixtures was due to the dessagregant action of the carriers, which obtained an increase of the drug surface in contact with the dissolution medium. The proportions and carrier nature influence the oxodipine dissolution, fundamentally from solid dispersions, where the interaction drug/carrier is stronger than in physical mixtures.     

An Information Security Governance Framework

ABSTRACT

Information security culture develops in an organization due to certain actions taken by the organization. Management implements information security components, such as policies and technical security measures with which employees interact and that they include in their working procedures. Employees develop certain perceptions and exhibit behavior, such as the reporting of security incidents or sharing of passwords, which could either contribute or be a threat to the securing of information assets. To inculcate an acceptable level of information security culture, the organization must govern information security effectively by implementing all the required information security components. This article evaluates four approaches towards information security governance frameworks in order to arrive at a complete list of information security components. The information security components are used to compile a new comprehensive Information Security Governance framework. The proposed governance framework can be used by organizations to ensure they are governing information security from a holistic perspective, thereby minimising risk and cultivating an acceptable level of information security culture.