Due to the more disordered structure of vitreous oxide systems in comparison with that of crystalline species, the alkali ions present have different coordination numbers. The coordination of the alkali cations with the oxygen ions can be estimated using various structural analysis methods, such as x-ray diffraction (XRD), Raman and IR spectroscopy. This paper presents a method for measuring the coordination number of alkali cations using basicity measurements. The basicity of oxide glasses is experimentally determined from spectroscopic measurements, on the basis of the percentage basicity, pB. The cases presented herein refer to the Li(+) cations in Li(2)O.2SiO(2) (LS(2)) system and to Na(+) cations in synthesized Na(2)O-Al(2)O(3)-P(2)O(5) glasses. The results are compared to the literature data obtained using different approaches.

Knowledge of various types of solid structure presents both a theoretical interest, fundamental and practical. If current experimental methods can characterize the structure of crystalline solids, the information is limited to more simple system in case of vitreous solids. The explanation lies in the lack of order at distance characteristic for glasses. In the last two or three decades, the method of molecular dynamic was remarked among the theoretical simulation method of some oxide glasses. In the present paper the structure of lithium disilicate glass obtained by the method of molecular dynamic is presented. Complementary, the method of radial distribution for internuclear distances of different component atom pairs is used. The obtained results are compared to reference data.

Knowledge of various types of solid structure presents both a theoretical interest, fundamental and practical. If current experimental methods can characterize the structure of crystalline solids, the information is limited to more simple system in case of vitreous solids. The explanation lies in the lack of order at distance characteristic for glasses. In the last two or three decades, the method of molecular dynamic was remarked among the theoretical simulation method of some oxide glasses. In the present paper the structure of lithium disilicate glass obtained by the method of molecular dynamic is presented. Complementary, the method of radial distribution for internuclear distances of different component atom pairs is used. The obtained results are compared to reference data.

Undoped and neodymium doped quartz glasses were obtained by the hybrid sol-gel method. The vitrification was performed in He atmosphere. The Nd(3+) characteristic absorption bands in the UV and VIS were put into evidence. Investigations in the NIR range revealed a small amount (86 ppm) of OH(-) in the vitreous matrix. FTIR and Raman spectra exhibit the SiO(2) glass characteristic vibrations and also the characteristic vibrations of Si-OH and Si-Cl bonds. The photoluminescence peaks at 640, 920 and 1080 nm belonging to the Nd(3+) doped quartz glass were evidenced.

In contrast with transitional metals whose spectra and color depends a lot of the ligands strength field, the sensitivity of the rare earth spectra is significantly weaker. This is the reason why the color of these ions is the same whatever the basic vitreous matrix. These properties permit to establish a relation for the determination of the concentration of these ions in vitreous matrix directly from the optical transmission spectra. The paper presents some samples of silica and phosphate glasses with lanthanides content for nonlinear optical applications synthesized at a laboratory scale. VIS-NIR transmission curves are presented, for several compositions. For the correlation of the lanthanides content with the specific optical absorption peak one used a method starting from the Lambert – Beer law. For the Nd2O3 concentration determination, it was used a method proposed by D.M. Dood and D.B. Fraser for the OH groups content, with an error of +4%. For specific peaks, expressions for lanthanides concentration in ppm, related to the optical transmission were found. A possibility appears to directly find the lanthanides concentration from the absorption coefficient at specific wavelengths for each vitreous matrix. The influence of matrix is discussed.

The paper presents a study of the industrial waste incorporating in glass in order to obtain decorative colored glasses. The influence of iron and chromium oxides from waste amount is discussed. The samples properties such as density, thermal expansion coefficient and viscosity are investigated. Including different oxides of heavy metals (obtained from sludge that contains chromium and iron) into the vitreous system leads to the obtaining of several decorative glasses. Their colour varies widely, to the added quantity and the atmosphere of the work place.

The paper follows both the national preservation and durable managing policy, as well as the European laws for the area of environmental protection (UE’s Directive 1999/31/EC – „landfill of waste” an the Council’s Directive no. 94/62/CE regarding the packaging and the packaging waste, amended by the Council’s Directive no. 2004/12/CE). The proposed technologies lead to reducing the need of both raw materials and energy in the process of obtaining various types of glass. The study proposes new ways of retrieving and eliminating waste that contains heavy metals alongside borosilicate shards. This paper also aims to increase the responsibility of the waste generating companies and to make the potential users more sensible.

Alkaline earth metal silicates as well as many polyvalent metals silicates can be obtained through aqueous solutions reactions between an alkaline silicate solution and the solutions of metal salts. The vitrifiation of the oxide compositions, established by the necessary molar ratios for the projected glass, is realised by calculating the concentration of chemical precursors, through their reaction directly on the substrate. The sodium silicate viscosity in aqueous solution and the viscosity of nitrogenated compounds or oxalates necessary in the silicates synthesis is compatible with the necessary viscosity for ink-jet cartridges. The necessary silicates forming reactions were studied directly on the deposition support, so that the functional characteristics of the multicompartment ink-jet cartridges were used. Compositions were realised, in which the colouring effect was obtained with ionic colorants. The vitrifiation and the quality of the obtained thin films were studied through Optical Microscopy and Scanning Electron Microscopy.

The adsorption phenomenon of organic molecules in micro and nanoporous solids has been known for a long time but it has raised a considerable interest in the last years when different types of porous materials that are used in enzymatic catalysis, chemical biosensors, chromatographic columns or drug support, have been investigated. Because of the advantages that porous glass presents compared to other types of organic or inorganic porous materials, high mechanical resistance, thermal stability, rigid structure immune to biological and chemical degradation, etc., the glasses with a better controlled porosity are researched and used more and more. In this paper, we report on the preparation of a nanoporous glass with the pores' diameter between 10-300 nm, with interconnected pores, fabricated on the base of microphase separation in an alkaline borosilicate glass. The glass composition was chosen in the Na 2 O-B 2 O 3 -SiO 2 system. The obtained materials have been characterized physico-chemically (chemical and thermal analysis, X-ray diffraction), microstructurally (atomic force microscopy) and from the point of view of the bioproperties that present interest (pH dynamics, noncitotoxicity, cellular proliferation, adsorption and enzymatic activity).

Cement quality, expressed as strength, depends on granulometric uniformity degree. For this reason there is a practical interest in corelating mechanical strength of cement and granulometric uniformity degree. Correlations between mechanical strength and granulometric uniformity degree are obtained using literature data and also the analysis romanian marks of Portland cement.

the overall heat consumption. Nowadays, as a result of years of innovative constructive-type improvements, it was attained a limit of energy savings related to clinker burning plants. A further progress can be achieved, in authors' opinion, only by a more accurate estimation of the heat of reaction. Due to that reason, it was considered that it is essentially needed to review existing heat of reaction evaluation methods - which are still considering the equilibrium conditions at clinker cooling - and to develop improved calculation and optimization procedures, dealing with real conditions encountered in industry. Several mathematical Models will be employed to attain these goals. It is conferred, in that manner, a real scientific basis in order to optimize thermal balances of the industrial equipment.

Lately, the lithium disilicate glass (LS2) is back in the researchers attention because of its newly found practical application, mostly in the special glass-ceramic fields. Because of this, it is necessary to point out the influence of some parameters, which are associated to the processing route, over the point out the in structural characteristics and the properties. In this paper, the influence of some thermic treatments applied to the lithium disilicate glass over the UV absorbtion spectra, is considered. The lithium disilicate glass (LS2), obtained by classical method, was thermicaly treated for different periods of time, resulting in different cristalization percentages. These samples were structurally investigated using the X-ray diffraction. Also, by using the methodology described in literature, the influence of the structural modifications, that take place in the lithium disilicate glass with different percentages of crystalization was pointed out by optical spectroscopy methods. At the same time, lithium disilicate samples with different thermic histories and the corresponding optical spectroscopy determination.

The ternary oxydic system Na2O-B2O3-SiO2 is well known, especially because of its practical interest glasses (Vycor and Pyrex). The paper aims to Put into light the basicity percentage (pB) calculating modality taking into account the tetracoordinated borfraction (N), for a series of oxydic compositions from this system, as well as the variation of corresponding temperatures foil certain given viscosities with the basicity percentage (pB) of these glasses. Also, for four sodium borosilicatic glasses experimentally obtained, the viscosity was determined at three different temperatures and they were mathematically deduced the A, B and To coefficients associated to the viscosity-temperature relation (type Vogel-Fulcher-Tainmann), for each ternary obtained glasses.

It is well known that newborns and infants respond poorly to immunization with influenza virus vaccines. The poor response of neonates may be related to restricted B cell repertoire and high susceptibility of neonates to high dose tolerance. Protective antibody response against hemagglutinin (HA) of influenza virus is a T-dependent response. While the immunization of neonates with live virus caused a long lasting unresponsiveness, the immunization with a plasmid containing influenza virus HA circumvents the neonatal unresponsiveness. Genetic immunization primes efficiently neonatal HA-specific B cells, and induces memory cell enabling the animals to develop a strong secondary response and to survive to challenge with a lethal dose. The most striking effect of neonatal immunization consists of a shift of neonatal HA-specific B cell repertoire to adult-type as assessed by analysis of reactivity pattern of HA-specific clonotypes. The diversification is associated with the induction of germinal centers, increased number of B220+GL-7+ cells and with the re-expression of RAG genes. This suggests that the receptor revision may contribute to the diversification of HA-specific neonatal B repertoire.

The structure of the oxide vitreous systems is characterized at a first structural level, by the type and the proportions of the constitutive ions, by the coordination number of the cations in relation with the oxygen, by the internuclear distances and the angles between the formed chemical bonds. Concrete structural information can be gathered by utilizing different experimental techniques (x-rays or neutrons diffraction, XPS, MAS-NRM, 3Q-MAS NRM, etc.). For the alkali-silicate glasses generally exists a series of data reported in literature, but in fact there are fewer results referring to the Li + ion coordination in glasses from the Li2O-SiO2 system. In this work, an attempt of determining the coordination number of the Li + ion in the lithium disilicate glass (LS2) is presented by using a globalizing structural characteristic - the basicity percentage (pB). This is experimentally determined from spectroscopic measurements. The e xperimental data processing shows a c oordination nu mber for Li + in LS2 glass equal to 2, value found in other literature reports too.

Somatic mutation of immunoglobulin (Ig) genes plays an important role in generating antibody diversity. The frequency of somatic mutation appears to vary throughout life. However, this process has been difficult to study in vivo because the DNA in and around rearranged V genes undergoes random mutation, causing silent or replacement mutations. Therefore, we have developed a transgenic mouse model for studying the frequency of B cells exhibiting mutation in young and old mice. The system is based on a reporter transgene (HuG-X) that encodes a chimeric Ig heavy chain composed of a murine VDJ segment and a human IgG1 constant region. The VDJ has been mutated to contain a TAG stop codon in the D segment. Therefore, the transgene is transcribed but not translated. Point mutation of the stop codon results in expression of the chimeric H chain, which is readily detected as human IgG1 expression. In vivo, we found that the transgene undergoes spontaneous reverse somatic mutation at a low frequency. Treatment of HuG-X mice with anti-IgD greatly increases the frequency of somatic mutation. The observed mutation frequency in anti-IgD-treated mice increases with age until adulthood, then plateaux and finally declines in aged mice. The mutations in the stop codon were associated with increased double-stranded DNA breaks (DSB) within and around the TAG site. Our results demonstrate that the rate of frequency of spontaneous reverse mutation is very low in vivo, yet it is significantly increased after stimulation with anti-IgD antibodies. The frequency of point mutation is age dependent and correlates with increased DSB.

Most of the properties for vitreous oxide systems can be calculated depending on their chemical composition. Basicity is one of them. Generally, those types of relations do not take into account some factors on which obtaining glass depends. In this paper it is pointed out the dependence of basicity to some specific characteristics of vitreous systems which influence in different ways some properties of glasses (e.g. chemical reactivity, optical properties etc.).

The distribution of SiO4 species in alkali silicate glasses has been calculated thermodynamically by applying the principles of the acid-base theory. The equilibrium constants for the various structural entities involved in the neutralisation of silica have been calculated by a new method. The influence of melting temperature on the distribution of SiO4 was also studied.

The temperature distribution within the glass melt in tank furnaces is one of the parameters that influence the productivity of the tank. It is difficult enough to determine the thermal regime within a tank by direct measurement and it is greatly affected by the depth of the tank and the materials used for its construction. That is why the depth of the tank has to be governed by the type of glass, the surface temperature of the molten glass, and the characteristics o the melting zone walls.The present work describes the results obtained for several situations of practical interest, taking into acount heat transfer through the glass melt.

As is known, using different kinds of markers it has been shown that a batch portion, introduced in a glass melting tank furnace, leaves it gradually, after times varying between 7 and 130 h, depending on its construction and working conditions. A mean duration may be assessed, having, for different furnaces, values between 25 and 60 h, called retention time (trm). On the other hand, the available data concerning the melting time, the refining time and the conditioning time, resulted in a total of about 8 h. This minimum time required to obtain glass of a given quality from a certain batch was named technologically necessary time (ttn). Obviously this time is much smaller than the retention time. The ratio trmttn has, for the majority of continuous glass melting tank furnaces, values greater than 3, for some glass portions even exceeding 10.