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Degenerately doped metal-oxide nanocrystals (NCs) show localized surface plasmon resonances (LSPRs) that are tunable via their tunable excess charge-carrier densities. Modulation of excess charge carriers has also been used to control magnetism in colloidal doped metal-oxide NCs. The addition of excess delocalized conduction-band (CB) electrons can be achieved through aliovalent doping or by postsynthetic techniques such as electrochemistry or photodoping. Here, we examine the influence of charge-compensating aliovalent dopants on the potentials of excess CB electrons in free-standing colloidal degenerately doped oxide NCs, both experimentally and through modeling. Taking Sn4+:In2O3 (ITO) NCs as a model system, we use spectroelectrochemical techniques to examine differences between aliovalent doping and photodoping. We demonstrate that whereas photodoping introduces excess CB electrons by raising the Fermi level relative to the CB edge, aliovalent impurity substitution introduces excess CB electrons by stabilizing the CB edge relative to an externally defined Fermi level. Significant differences are thus observed electrochemically between spectroscopically similar delocalized CB electrons compensated by aliovalent dopants and those compensated by surface cations (e.g., protons) during photodoping. Theoretical modeling illustrates the very different potentials that arise from charge compensation via aliovalent substitution and surface charge compensation. Spectroelectrochemical titrations allow the ITO NC band-edge stabilization as a function of Sn4+ doping to be quantified. Extremely large capacitances are observed in both In2O3 and ITO NCs, making these NCs attractive for reversible charge-storage applications.

Fish waste was studied as a raw material for the simultaneous production of protein hydrolysates, collagen and fish oil. Enzymatic hydrolysis was selected for recovering these by-products with high value-added. Alcalase 2.4 L was used to hydrolyze fish waste in a batch reactor under controlled conditions (180 min, 50 °C and pH 8). The influence of hydrolysis degree on by-products recovery was analyzed for different enzyme and substrate concentrations. Results suggested that the enzyme/substrate ratio was the main factor controlling the hydrolysis rate. Linear relationships were found between the degree of hydrolysis and the amount of each of the obtained by-products. From these relationships, the amounts of by-products with high added value can be predicted by only knowing the degree of hydrolysis reached. In optimal conditions (DH = 25%), 430 g of protein hydrolysate, 10 g of collagen and 350 g of oil could be obtained from 1000 g of fish waste. The use of fish waste as raw material for by-product fabrication resulted in a 79% reduction of waste disposed to landfill. Therefore, this study shows the enzymatic hydrolysis of fish waste as a feasible solution to obtain high value-added products and an alternative to landfilling disposal.

In this work, the anodization of grade 2 titanium was performed using a HCl-based electrolyte in order to obtain Titania nanostructures. Different glycerol concentrations were added to the HCl electrolyte to study the effect it has on the shape and density of the nanostructures, additionally, anodization time and voltage was also varied. The anodized samples were observed by SEM microscopy and studied by Raman spectroscopy and X-ray diffraction. Raman spectroscopy and XRD showed the formation of the anatase phase of the TiO2. By SEM it was possible to observe several changes in the shape of the structures, by adding glycerol ball-like structures were visible, anodization time did not change the shape of the nanostructures. However, the voltage variation showed a clear control on the shape of the structures, forming nanotubes at higher voltages. It was concluded that a better control of the shape and density of the nanostructures is achieved by adding glycerol, however, in order to overcome the resistance that the electrolyte brings, higher voltages are required.

Leveraging recent advances in electron energy monochromation and aberration correction, we record the spatially resolved infrared plasmon spectrum of individual tin-doped indium oxide nanocrystals using electron energy-loss spectroscopy (EELS). Both surface and bulk plasmon responses are measured as a function of tin doping concentration from 1-10 atomic percent. These results are compared to theoretical models, which elucidate the spectral detuning of the same surface plasmon resonance feature when measured from aloof and penetrating probe geometries. We additionally demonstrate a unique approach to retrieving the fundamental dielectric parameters of individual semiconductor nanocrystals via EELS. This method, devoid from ensemble averaging, illustrates the potential for electron-beam ellipsometry measurements on materials that cannot be prepared in bulk form or as thin films.

In the present investigation, nanostructured ceramic HfN coatings were deposited onto silicon (100) wafer by magnetron sputtering DC method, from a metallic Hf target. The deposition process followed by a similar pattern as the multilayer film deposition, using cycles with the nitrogen gas turned on for 90 s and turned off for 15 s; four sets of samples were obtained using 5, 10, 15 and 20 cycles. The X ray diffraction (XRD) identified the presence of two different cubic crystalline phases of HfN, corroborated by Rietveld analysis. The Vickers hardness test showed that the hardness values increases with more cycles, due to a higher compressive stress evaluated by Stoney formula. All samples were investigated with no visible fracture until 10 grf for the 5 cycles sample; however, no fractures were visible at all for the 15 and 20 cycle samples for that given load, instead fractures started to appear at 25grf for the 10 and 15 cycles coating. Eventually it is distinguished that, the thickness and morphology of the coatings were measured by field emission scanning electron microscopy FE-SEM. As well as, the thickness increased from 0.4 µm to almost 1.33 µm as the number of cycles also increased, where we can observe the formation of columnar growth, moreover it is possible to distinguish the formation of two different clusters which might be related to different phases.

Understanding neutrophil heterogeneity and its relationship to disease progression has become a recent focus of cancer research. Indeed, several studies have identified neutrophil subpopulations associated with pro- or anti-tumoral functions. However, this work has been hindered by the lack of widely-accepted markers with which to define neutrophil subpopulations. To identify markers of neutrophil heterogeneity in cancer, we utilized single-cell cytometry by time-of-flight (CyTOF) coupled with high-dimensional analysis on blood samples from treatment-naïve, melanoma patients. Our efforts allowed us to identify 7 blood-neutrophil clusters, including 2 previously identified individual populations. Interrogation of these neutrophil subpopulations revealed a positive trend between specific clusters and disease stage. Finally, we recapitulated these 7 blood-neutrophil populations via flow cytometry and found that they exhibit diverse capacities for phagocytosis and reactive oxygen species (ROS) production in vitro. In summary, our data provide a refined consensus on neutrophil-heterogeneity markers, enabling a prospective functional evaluation in patients with solid tumors.KEY POINTSCyTOF analysis reveals 7 blood neutrophil clusters correlating with melanoma stage in treatment-naïve patients.Neutrophil clusters by unbiased-calling are recapitulated by flow cytometry and harbor diverse phagocytic and ROS-producing capacities.

Titanium-Silicon Oxynitride (TiSiNO) coatings were synthetized by reactive co-sputtering technique on stainless steel 304 substrates varying the substrate temperature during the deposition. Two targets were used simultaneously, the first one of Ti on a DC source at 100 W and the second was a Ti-Si-O target on a pulsing RF source at 180 W. X-ray diffraction identified three crystalline phases: titanium nitride (TiN), titanium oxide (TiO) and silicon oxide (SiO2), where the SiO2 phase presented compressive stresses at low temperatures and tension stresses at higher temperatures, along with a change in the preferential orientation. The coating obtained at 200 °C showed the higher hardness value of 14.8 GPa, attributed to a lower grain size and high compressive stress. Finally, all coatings presented high fracture toughness, since the was a lack of any type of crack for all applied load values.

The thermodynamic state of a glass is often described in terms of a number of order parameters, each of which evolves toward its equilibrium value during glass relaxation. The problem comes in identifying these order parameters and determining their physical significance. The authors argue that the order parameters in a glass can be defined in terms of a set of configurational temperatures, each corresponding to a particular mode of energy storage. The evolution of glass properties can then be calculated using a coupled set of rate equations describing the relaxation of the configurational temperatures toward their equilibrium values, viz., the reservoir temperature. The authors illustrate the concept of configurational temperatures by considering the free energy of mixing in alkali borate and silicate glasses.

A theoretical study on the static linear (α) and nonlinear (β and γ) optical properties in gas phase of Photofrin and Foscan molecules is reported. These compounds are known as porphyrin derivatives which act as photosensibilizers in photo dynamic therapy for cancer treatment. The geometric parameters of Photofrin and Foscan were fully optimized using ab initio and Density Functional Theory levels, at Hartree-Fock and B3LYP hybrid functional approach, respectively. The STO-3G, 3-21G* and the 3-21+G standard basis sets were employed for the calculations. The 3-21+G basis set is augmented with one s and three p diffuse functions for carbon, nitrogen, oxygen and sodium atoms. The bond distances and the bond angles of the two optimized molecules obtained with different method/basis set combinations show only minor variation. The Hartree-Fock and B3LYP methods provide a suitable evaluation of the geometrical and optical properties of Photofrin and Foscan molecules, since the calculated α$_{ave}$, β$_{v}$ and γ$_{ave}$ results are in good agreement with previous reports for similar porphyrin derivatives. The optical properties of Foscan and Photofrin molecules have the same tendencies: the α$_{ave}$ results have an almost linear relationship with the conjugated bond number, the β$_{v}$ results are mainly determined by the nature and symmetry of the susbstituent groups to the porphyrin centre and the γ$_{ave}$ results are extremely depending on the calculation strategies.

The simultaneous electrodeposition of the system Cu–In–Se was investigated. The study was carried out at pH 8.5 using diethylentriamine as complexing agent for the Cu+2 ion. The synthesis of CuInSe2 semiconductor thin films was carried out by electrodeposition on different substrates [indium–tin oxide (ITO) on glass, aluminum and type 304 steel]. The simultaneous codeposition of the Cu, In, and Se was achieved by constant potential electrolysis technique in aqueous solutions containing the elements that conform this material. The deposits of CuInSe2 were about 4 μm thick, which is thick enough for the photovoltaic effect to take place. The as-deposited films were characterized by atomic emission spectroscopy with inductive coupling plasm (AES-ICP) and scanning electronic microscopy (SEM). Annealed films were characterized X-ray diffraction, optical NIR spectroscopy, and photoelectrochemical studies The films were obtained with a well-defined composition, very close to the expected one. Homogeneous deposit with chalcopyrite structure was produced. A In2O3 phase was also observed. Annealing of the film improved the crystallinity of the films. Good photo response, an appropriate absorption coefficient, and a band gap of 1.09 eV were obtained.

Thermodynamics determines the boundary conditions for the diffusion process in an ion exchange process. It also determines the driving force for the diffusion. A simple one-dimensional model of nearest neighbor interactions is shown to be adequate to describe the boundary conditions. The likelihood that it can also describe the driving force for diffusion is discussed.

It is shown that interaction between the ions undergoing ion exchange leads to a sigmoidal equilibrium curve. A negative interaction in the glass causes the ratio of concentration of the two ions to be more nearly equal to unity in the glass than it is in the molten salt. It is further shown that the Rothmund–Kornfeld parameter is a measure of the non-ideality of the system. A value of the parameter greater than unity indicates a negative interaction energy.

A series of organosilylboranes has been investigated by IR spectroscopy and semiempirical calculations (MNDO/d force field methods). Computational studies afforded Si–B stretching wavenumbers in good agreement with the experimental IR bands observed in the range of 480–650 cm −1 . It was shown that these characteristic Si–B bond vibrations depend on the structure of molecules and on the size of substituting groups. Thus, compounds possessing small and medium substituting groups (H, Me) and those having a symmetry element give pure Si–B stretching bands. In the case of silylboranes bearing bulky groups, assignments of bands involving Si–B vibrators were achieved via comparison of experimental and theoretical IR spectra with those of reference molecules containing the parent organosilyl- or organoboryl moieties. An experimental absorption band near 600 cm −1 could reasonably be assigned to ν (Si–B).

Glasses containing cuprous ions and halides are heated. In some of the glasses, the precipitation of cuprous halides gives rise to excitonic absorption. Electron micrographs and leaching studies fail to show a correlation between the precipitation of the cuprous halides and phase separation of the matrix glass into silica rich and boron rich regions. Correlation with previously discussed models of the dependence of halogen solubility on the bonding of boron atoms is evident.

The relationship between properties and glass structure is, perhaps, more clearly evident in borate and in borosilicates than it is in any other family of glasses. Nuclear magnetic resonance measurements have shown that, at room temperature, the manner in which oxygen bonds to boron depends on the ratio of alkali to boron. A statistical mechanical model indicated that the bonding is influenced by temperature and it was used to calculate the relative numbers of various structural units for the glass as a function of composition and temperature. The results exhibit a reasonably good correlation with the measured strain point and softening point. A model for the halogen solubility as a function of temperature and of matrix composition was also developed. The predictions of the model were fairly well correlated with the intensity of the exciton absorption in glasses in which cuprous halide had precipitated.

The trinuclear cluster [Ru3O(Ac)6(py)2(acpy)]PF6 (py: pyridine;acpy: 4-acetylpyridine) has been synthesized and anchored on functionalized silica. Five successive redox couples exhibitingE°=−1.4, −0.98, 0.21, 1.23, and 2.2 Vvs. SHE have been characterized in acetonitrile solutions based on cyclic voltammetry and spectroelectrochemical measurements. The redox and spectroscopic properties are maintained in the immobilized species, allowing its use in optodes and in electron transfer processes.

The excited states of many organic molecules are sufficiently long lived so that excitation gives rise to a change in the absorption spectrum that persists for seconds or even longer. The author is...

Alkali transport between a glass substrate and an oxide over layer occurs by a mechanism of ion exchange between the alkali and protons. Thermodynamics requires that the difference in chemical potential of the alkali and the proton be the same in both phases at equilibrium. The influence of chemical composition of the glass on the chemical potential of alkali ions is discussed. Good agreement between predictions of the direction of alkali transport and observed transport is obtained.

A statistical mechanical technique with no adjustable parameters is used to calculate the density of oxygen vacancies in pure germania glasses. The calculated values are in fair agreement with the experimental values obtained by Schurman. A slightly different technique utilizing one adjustable parameter is used to calculate the density of oxygen vacancies in binary germano-silicate glasses. The results are also in fair agreement with experimental values.

The flux of one of the components in a system of two interdiffusing materials was taken to be proportional to the gradient of the chemical potential of that component. The chemical potential was derived from the free energy of mixing in a one-dimensional system. When a negative interaction energy was assumed, the interdiffusion coefficient exhibited a maximum. The height and the sharpness of the minimum decreased with increasing temperature. Because of reasons discussed in the paper, for either positive or negative interactions the influence of composition and temperature on the electrical conductivity is expected to be qualitatively similar to the influence exerted by positive interactions on the interdiffusion coefficient.

Introduction of silver into a silicate glass often leads to reduction and coloration. The electron required for silver reduction is extracted from a nonbridging oxygen atom. The use of high-field-strength ions limits the number of nonbridging oxygens and silver reduction.

Glasses containing small particles of silver halide are caused to darken by the action of uv light. Fading occurs when the exciting light source is removed and is often enhanced by irradiation with visible light. It is shown that simultaneous optical and thermal bleaching can be separated mathematically and that optical bleaching is a first order process. A model for thermal bleaching based on diffusion is consistent with rate studies and qualitatively explains the dependence of the fading rate on the darkening conditions.

The anaerobic treatment of wastewater from the household and personal products industry was studied using a 16.3 L hybrid reactor (UASB and biofilter). The top of the UASB reactor was filled with coconut shells to act as the support material for the biofilter. The wastewater was characterized in terms of pH (1.0 – 12.0), COD (1,000 – 5,000 mg/L), BOD 5 (700 – 1,500 mg/L), chloride (55 – 850 mg/L), ammonia nitrogen (0.4 – 0.9 mg/L), total Kjeldahl nitrogen (22.1 – 34.0 mg/L), phosphorus (2.0 – 2.5 mg/L), anionic surfactants (100 – 600 mg/L), turbidity (115 – 300 NTU) and total suspended solids (450 – 1,440 mg/L). The bioreactor was operated continuously for 120 days at room temperature (26 ± 5 o C) with hydraulic retention times of 50, 40 and 60 h. COD and BOD removals and biogas production were evaluated in order to analyze process efficiency. The average removal efficiencies for COD (77%, 72% and 80%) and BOD 5 (approximately 90%) were obtained with HRTs of 50, 40 and 60 h, respectively. The average specific biogas production was 0.32 L/g COD (at standard temperature and pressure) for the three experimental runs. These data indicate good reactor efficiency and suggest the possibility of using this system to treat wastewater generated by the household and personal products industry.

The record of O3 total column and NO2 obtained by visible spectroscopy at Ushuaia (55° S), Marambio (64° S) and Belgrano (78° S) and vertical ozone profiles from the latter station provide insight into the unprecedented major warming observed above Antarctica in the last week of September 2002. From 18 September to 25 September the temperature increased 54°C at the isentropic level of 700 K. The temperature anomaly was observed down to the level of 300 K in which a well-defined tropopause was established. From comparison of the ozone profiles before and during the event, it can be seen that a fast increase in O3 took place basically above 500 K, but the layer where the ozone hole occurs was barely affected. Low potential vorticity values above Belgrano occurred only at levels above 500 K, confirming that the vortex split was confined to heights above the layer of the Antarctic spring depletion. The signature of poleward-transported air is clearly visible from the NO2 column departure from the envelope of the previous years in all three stations. NO2 columns larger than typical for ozone hole conditions by 400% were observed at Belgrano. Diurnal variations provide evidence of non-denitrified extra-vortex air. Fil: Yela, M.. Instituto Nacional de Técnica Aeroespacial; España Fil: Parrondo, C.. Instituto Nacional de Técnica Aeroespacial; España Fil: Gil, M.. Instituto Nacional de Técnica Aeroespacial; España Fil: Rodríguez, S.. Instituto Nacional de Técnica Aeroespacial; España Fil: Araujo, J.. Dirección Nacional del Antártico; Argentina Fil: Ochoa, H.. Dirección Nacional del Antártico; Argentina Fil: Deferrari, Guillermo Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina Fil: Diaz, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina

Particles of cuprous oxide with 20 nm sizes have been precipitated from borosilicate glasses. The absorption spectra show distinct changes in glasses given different heat treatments. Only very weak nonlinear effects are observed.

Silica glass exposed to pulsed UV excimer laser irradiation undergoes optical changes that can include either an optical path increase or a decrease. During a given exposure the sign of the induced optical path change can reverse as a function of pulse count. The reduced optical path and sign reversal are only observed in H 2 -containing glasses, and at high exposure fluence only optical path increase is observed. In past work we proposed an induced density change model invoking a dynamic equilibrium density to explain the high fluence experiments. Here we present a model that extends the density model to the low fluence regime by allowing the equilibrium density to be a function of the time-dependent break-up of the silica network during exposure. The network break-up is tracked by calculation of the induced SiH concentration in the glass. The agreement of optical path change obtained from experimental data with that deduced from the kinetic approach covers a wide range of exposure fluence and molecular hydrogen concentration. Using the model one can predict the change in optical path that arises from the excimer laser exposure.

The use of silica lenses in a photolithographic system employing a 193 nm excimer laser has been proposed. It is desirable to determine if, at the low intensity to be used in the system (approximately equals 0.1 mJ/cm2), the glass will withstand about ten years of use without objectionable induced absorption. At a pulse frequency of 1 Khz, this length of time corresponds to about 1011 pulses. Because of the long time involved, an accelerated test is needed to determine the susceptibility of silica to induced absorption. The mechanism of darkening must be understood in order that the behavior of the glass under use conditions be predicted with confidence from the results of the accelerated test. The most important processes in the mechanism of induced absorption are: (1) Two photon absorption creating an exciton; (2) Trapping of the exciton by a localized state; (3) Dissociation of the trapped exciton to form an E' center and a NBOHC; (4) Reaction of these centers with hydrogen to form SiH and SiOH bonds; and (5) Photolysis of the SiH bonds to produce more E' centers. The mechanism will be discussed in detail and the agreement with experimental results over a range of intensities and hydrogen levels will be presented.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Exciton absorption bands near 400 nm indicate the precipitation of cuprous halides in certain alkali borosilicate glasses. The precise shape of the absorption can be altered by varying the ratio of bromide to chloride or by varying the heat treatment. The influence of the matrix glass composition on the strength of the exciton bands is discussed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Spectral changes induced by UV irradiation were studied in a variety of glasses. These include photosensitive glasses in which colloidal silver is formed, glasses in which the formation of V+ ions produces violet color, and glasses in which irradiation within a charge transfer band leads to the formation of Fe+2 ions and holes in the valence band. In all of these glasses, hole trapping by non-bridging oxygen atoms is required for the occurence of spectral changes.

Oxidized 1-palmitoyl-2-arachidonyl-sn-3-glycero-phosphorylcholine (Ox-PAPC) and its component phospholipid, 1-palmitoyl-2-(5,6 epoxyisoprostanoyl)-sn-glycero-3-phosphocholine (PEIPC), which are present in atherosclerotic lesions, activate endothelial cells (EC) to induce a complex inflammatory response. Previously, we demonstrated induction of genes regulating chemotaxis, sterol biosynthesis, the unfolded protein response, and redox homeostasis by Ox-PAPC in human aortic EC (HAEC). Activation of the c-Src kinase/STAT3 pathway and the endothelial nitric oxide synthase (eNOS)/sterol regulatory element binding protein (SREBP) pathway were shown to regulate several of these inflammatory effects of Ox-PAPC in HAEC. High-density lipoprotein (HDL) has anti-inflammatory and antioxidant properties. The goal of the current studies was to determine the role of HDL in regulating Ox-PAPC signaling in HAEC. Using quantitative real-time PCR and Western analysis, we demonstrated that pretreatment of HAEC with HDL for 1 hour, followed by cotreatment, reduced the induction of chemotactic, sterol biosynthetic and UPR genes, by Ox-PAPC and PEIPC. Furthermore, treatment with HDL inhibited the activation of c-Src kinase, STAT3, and SREBP and reversed the uncoupling of eNOS triggered by Ox-PAPC. Finally, we demonstrated that treatment with HDL did not inhibit Ox-PAPC and PEIPC activation of redox pathways, which protect the cell from the effects of oxidative stress. Taken together, these studies demonstrated that HDL inhibits the proinflammatory effects of Ox-PAPC and PEIPC while maintaining the antioxidant activities of these oxidized lipids.

The transient absorption produced in high-purity fused silica by exposure to a 193-nm excimer laser is investigated as a function of exposure, dissolved molecular hydrogen content, and hydrogen-related processing. Long-term recovery of transmittance was found to correlate with the dissolved molecular hydrogen concentration, whereas short-term fade was due to geminate recombination of an E′ center with an H radical. The redarkening process was shown to be the result of photolysis of SiH, which regenerates color centers. When the silica was processed in a hydrogen atmosphere at high temperature and subsequently exposed at 193 nm, the glass was found to produce an absorption spike, a fast, recoverable decrease in transmittance. The origin of the spike was linked to the creation of a precursor produced in the thermal reaction of silica with hydrogen. The precursor can be identified by its signal in the Raman spectrum. It is suggested that the precursor has absorption at 193 nm.

The density of silicon-silicon bonds and of peroxyl bonds in silica was calculated for a simple model. The calculated density of peroxyl bonds was much lower than the value extracted from a hydrogenation experiment. Explanations of the discrepancy are discussed.

Replacement of two cations of silica by two cations of alumina and one of baria in barium silicate glasses raises the strain, annealing and softening points even though the number of non-bridging oxygen atoms is unchanged. This observation is difficult to explain unless one postulates that a large moiety such as the S8 unit (described herein) moves as a whole during any flow process in this temperature range. The dependence of the strain point on the excess baria in a series of glasses having a constant number of non-bridging oxygens and constant alumina suggests that the negative charges of the alumina sites are balanced preferentially by barium ions rather than alkali ions.

Nuclear magnetic resonance results directly verify the predicted dependence of the boron coordination on composition and temperature. The strong color of the copper-titania couple is diminished when the number of boron atoms bonded to non-bridging oxygen atoms is sufficiently high. This state is attained either by quenching the glass from a sufficiently high temperatyre or by choosing a sufficiently high ratio of alkali to boron.

Photochromic glasses doped with thallium, iodide and cadmium have been found not to show the superlinear relationship between equilibrium darkening and excitation intensity which was reported previously for undoped photochromic glasses.

The present model provides a formalism for studying the effects of chemical disorder in a system of interacting atoms in which the number of neighbors of each kind of atom need not be the same. When they are the same, this model reduces to the quasi-chemical approximation. It is applied to a model for phase separation in alkali silicates and alkaline earth silicates which involves a mixture of fourfold and sixfold coordinated species. The sixfold coordinated species represents a pseudo-atom comprised of two silicon atoms each bonded to non-bridging oxygen atoms which are strongly associated. A miscibility dome similar to that observed in sodium silicates and barium silicates is predicted. The suppression of phase separation by alumina is predicted.

Photolysis of certain glasses containing minute silver halide droplets leads to visible absorption. The temperature dependence of the induced absorption is strongly correlated with the rate at which the glass reverts to its clear state upon the cessation of radiation. The factors which influence the compromises in fade rates and temperature dependence will be discussed.

An improvement on the formalism suggested by Araujo for studying chemical disorder is discussed. The formalism is used to calculate the fraction of boron atoms which are in tetrahedral coordination in alkali-borate glasses as a function of composition and temperature.

It has previously been shown that the fading rate of photoehromic glasses depends on darkening conditions. A trapped-hole diffusion model was proposed to explain this effect (Araujo 1968, 1971). In this paper a temperature-dependent recombination term which decreases exponentially with electron-hole separation is included in the diffusion model. Peculiar low-temperature effects are predicted and these are observed in some photochromic glasses.

The effect of 60 min of exercise at two intensities (50 and 60% $$\dot V_{O_2 \max }$$ ) and temperatures (0 and 22° C) on changes (A) in plasma lipids {triglycerides (TG), glycerol (GLY), total cholesterol (TC), and HDL-cholesterol (HDL-C)} was examined. Subjects were 10 men aged 27±7 years ( $$\dot V_{O_2 \max } = 3.81 \pm 0.451\min$$ , % fat=12.2%±7.1%). $$\dot V_{O_2 }$$ and respiratory exchange ratio results indicated that total energy and fat energy use were similar at the two temperatures. Changes in plasma volume (%ΔPV) were different (P

It is shown, from a consideration of its definition, that the Fermi level must vary as a photochromic glass darkens and fades. This phenomenon is shown to be responsible for the large effect that the concentration of copper exerts on the fading rate. It is postulated that the interaction of the emptied copper levels and the silver speck give rise to an image potential. It is further postulated that hole trapping is not probable unless the image potential of the copper lies above the Fermi level. This phenomenon coupled with the varying Fermi level explains why increased copper concentrations cause photochromic glasses to become darker at low temperatures but lighter at high temperature. It also explains why the level of darkening at steady state varies in a superlinear manner with the intensity of ultraviolet excitation.

A statistical mechanical model is used for calculating the fraction of boron atoms in tetrahedral coordination in alkali aluminoborosilicate glasses. The results are compared with nuclear magnetic resonance measurements. The calculated structure of certain glasses as a function of temperature is correlated with physical properties. A model for the calculation of halogen solubility is also proposed. The calculated changes of halogen solubility accompanying changes of temperature are correlated with observed changes in nickel color and certain characteristics of photochromic glasses. Phase separation in alkali borates is predicted at low temperatures but not at high ones.