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Reversible amorphous to crystalline phase transition introduces high contrast in the optical and electrical properties of chalcogenide glasses. This effect can be utilized by a designated temperature sensor based on optical power measurement as a function of temperature for temperature monitoring. For this purpose, crystallization kinetics and crystal structures of Ge–Se binary chalcogenide glasses were studied with Differential Scanning Calorimetry, Raman spectroscopy, and X-ray diffraction spectroscopy. The refractive index as a function of temperature was also measured to correlate the effect of structural rearrangement at the phase transition point with optical properties. Based on these data, the crystallization process is interpreted as being homogeneous for the stoichiometric composition and heterogeneous for either chalcogenide- or germanium-rich compositions. This specifically affects the optical performance of the films as a function of temperature and suggests the application of chalcogen- or germanium-rich compositions for building the sensor.

Silver photodiffusion is one of the attractive photo-induced changes observed in amorphous chalcogenides. In this research, we focus on amorphous S-rich germanium sulphide and study the kinetics of the silver photodiffusion by neutron reflectivity, as well as optical reflectivity. It was found from the neutron reflectivity profiles with 30 s time resolution that silver dissolved into the germanium sulphide layer, forming a metastable reaction layer between the Ag and the germanium sulphide layers, within 2 min of light exposure. Subsequently, silver slowly diffused from the metastable reaction layer to the germanium sulphide host layer until the Ag concentration in both layers became identical, effectively forming one uniform layer; this took approximately 20 min. Optical reflectivity reveals the electronic band structure of the sample, complementary to neutron reflectivity. It was found from the optical reflectivity measurement that the metastable reaction layer was a metallic product. The product could be Ag8GeS6-like form, which is regarded as the combination of GeS2 and Ag2S, and whose backbone is composed of the GeS4 tetrahedral units and the S atoms. We attribute the first quick diffusion to the capture of Ag ions by the latter S atoms, which is realised by the S–S bond in amorphous S-rich germanium sulphide, while we attribute the second slow diffusion to the formation of the Ag–Ge–S network, in which Ag ions are captured by the former GeS4 tetrahedral units.

CBRAM nano-ionic devices are emerging as a competitive technology solution for transistor free memory, offering low power consumption, fast switching, and non-volatility. However, due to the process by which switching is achieved in these devices, namely stochastic growth of a conductive filament bridging the two electrodes within the amorphous material between the electrodes, they suffer from reliability problems. In this work we present devices built with a nanotube structure of chalcogenide glasses to confine the growing conductive bridge. This structure is found to greatly improve device reliability and switching speed. Furthermore, the technology does not involve additional steps, is cost-effective, and is fully compatible with conventional CMOS technology. We have verified the process of conductive bridge growth with scanning electron microscopy and atom force microscopy and characterized the devices in terms of their current–voltage characteristics, memory window, endurance, and retention, all of which show excellent parameters. Their performance stability is also demonstrated at 130 °C, while multilevel switching is established by application of a variety of compliance currents.

Nanotube structures, formed in thin films of chalcogenide glasses open avenues for new applications, since they offer directional options for many effects in these otherwise completely disordered systems. One way to grow nanotubes is through formation of nano-columnar structures by confining them. In this work nano-columnar growth of thermally evaporated GexSe100−x (x = 20, 30, 40) films is achieved through oblique films deposition. The columnar structural organization of the films and its dependence upon the deposition angle and films composition are established by imaging the cross-sectional areas of the films through scanning electron microscopy. Atomic force microscopy, energy dispersive X-ray spectroscopy and Raman Spectroscopy studies reveal respectively variation in the surface porosity, composition changes and structural reorganizations occurring in the films as a function of obliqueness angles and material’s composition. These results are discussed in respect to the structural organization of films deposited under normal flux incidence and deformations and other structural effects caused by films' deposition under variable angles. Based on the experimental results an empirical formula for the tangent rule is suggested which links the incident flux angle α, and the nanotube inclination angle β.

Chalcogenide glasses are one of the most versatile materials that have been widely researched because of their flexible optical, chemical, electronic, and phase change properties. Their application is usually in the form of thin films, which work as active layers in sensors and memory devices. In this work, we investigate the formulation of nanoparticle ink of Ge–Se chalcogenide glasses and its potential applications. The process steps reported in this work describe nanoparticle ink formulation from chalcogenide glasses, its application via inkjet printing and dip-coating methods and sintering to manufacture phase change devices. We report data regarding nanoparticle production by ball milling and ultrasonication along with the essential characteristics of the formed inks, like contact angle and viscosity. The printed chalcogenide glass films were characterized by Raman spectroscopy, X-ray diffraction, energy dispersive spectroscopy and atomic force microscopy. The printed films exhibited similar compositional, structural, electronic and optical properties as the thermally evaporated thin films. The crystallization processes of the printed films are discussed compared to those obtained by vacuum thermal deposition. We demonstrate the formation of printed thin films using nanoparticle inks, low-temperature sintering and proof for the first time, their application in electronic and photonic temperature sensors utilizing their phase change property. This work adds chalcogenide glasses to the list of inkjet printable materials, thus offering an easy way to form arbitrary device structures for optical and electronic applications.

IntroductionDiabetes monitoring systems (DMS) are a possible approach for regular control of glucose levels in patients with Type 1 or 2 diabetes in order to improve therapeutic outcomes or to identify and modify inappropriate patient behaviors in a timely manner. Despite the significant number of studies observing the DMS, no collective evidence is available about the effect of all devices.GoalTo review and consolidate evidences from multiple systematic reviews on the diabetes monitoring systems and the outcomes achieved.Materials and methodsInternet-based search in PubMed, EMBASE, and Cochrane was performed to identify all studies relevant to the research question. The data regarding type of intervention, type of diabetes mellitus, type of study, change in clinical parameter(s), or another relevant outcome were extracted and summarized.ResultsThirty-three out of 1,495 initially identified studies, involving more than 44,100 patients with Type 1, Type 2, or gestational diabetes for real-time or retrospective Continuous Glucose Monitoring (CGMS), Sensor Augmented Pump Therapy (SAPT), Self-monitoring Blood Glucose (SMBG), Continuous subcutaneous insulin infusion (CSII), Flash Glucose Monitoring (FGM), Closed-loop systems and telemonitoring, were included. Most of the studies observed small nominal effectiveness of DMS. In total 11 systematic reviews and 15 meta-analyses, with most focusing on patients with Type 1 diabetes (10 and 6, respectively), reported a reduction in glycated hemoglobin (HbA1c) levels from 0.17 to 0.70% after use of DMS.ConclusionCurrent systematic review of already published systematic reviews and meta-analyses suggests that no statistically significant difference exists between the values of HbA1c as a result of application of any type of DMS. The changes in HbA1c values, number and frequency of hypoglycemic episodes, and time in glucose range are the most valuable for assessing the appropriateness and effectiveness of DMS. Future more comprehensive studies assessing the effectiveness, cost-effectiveness, and comparative effectiveness of DMS are needed to stratify them for the most suitable diabetes patients’ subgroups.

Understanding sugar-membrane interactions is of fundamental and technological relevance considering the role of sugars in drought-protection mechanisms of plants as well as the cryo- and bio-preserving effect of carbohydrates in many industrial and medical applications. In this work, we investigated the effect of sucrose on the electrical properties of membranes. In particular, we measured the specific capacitance of palmitoyl-oleoyl phosphatidylcholine membranes in aqueous solutions of sodium chloride. Different concentrations of sucrose were examined. The capacitance was assessed from the frequency-dependent deformation of giant unilamellar lipid vesicles in alternating electric field. Our measurements on giant vesicles in sugar-free aqueous solutions yield lower specific capacitance compared to values obtained for suspended and supported bilayers. This might be a result of the higher membrane tension in the latter systems, which is coupled to smaller thickness of the bilayer. We also report an increase of the bilayer capacitance upon increasing the sugar content in water. This finding is consistent with the sugar-induced thinning of membranes reported in the literature. However, the thinning is not sufficient to explain the observed capacitance increase with rising sugar concentration. We interpret the trend as resulting from an increase in the membrane dielectric permittivity.

The thermal stability and decomposition kinetics of the ionic liquid pyridinium nitrate was investigated by non-isothermal thermogravimetric analysis in an inert atmosphere (nitrogen). For the kinetic experiments, the thermal behavior of the sample was studied in the temperature interval from 360 up to 600 K at different heating rates (5, 10, 15 and 20 K/min). The kinetic parameters of decomposition including activation energy and pre-exponential factor under nitrogen atmosphere were evaluated by menace of two model-free methods – Friedman and Kissinger-Akahira-Sunose. Depending on the used calculation model, the obtained activation energy and pre-exponential factor values with respect to the degree of sample conversion during the kinetic experiment for method ranged in the intervals of 76.36–112.56 kJ/mol and 1.72×105–1.42×1010 min–1, respectively. Based on the attained kinetic parameter values it was established that the process of pyridinium nitrate decomposition occurred as a first-order reaction. Considering the calculated kinetic parameters, a decomposition mechanism for pyridinium nitrate was proposed.

The catalytic behavior of three Brønsted acidic ionic liquids: pyridinium hydrogen sulfate ([H–Pyr]+[HSO4]−), pyridinium dihydrogen phosphate ([H–Pyr]+[H2PO4]−) and pyridinium nitrate ([H–Pyr]+[NO3]−) in the esterification of acetic acid with n-butanol was compared in the current paper. The alteration in the values of acetic acid conversion and esterification rate were investigated as a function of the process parameters: catalyst nature, catalyst loading, initial molar ratio n-butanol:acetic acid and reaction temperature. The anion variety modified the acidity of the obtained samples and effected their catalytic activity as follows: [H–Pyr]+[NO3]− < [H–Pyr]+[H2PO4]− < [H–Pyr]+[HSO4]−. The increasing of both catalyst loading and reaction temperature led to higher values of acetic acid conversion and esterification rate. The existence of a positive linear relationship between the esterification rate and acetic acid concentration was observed. The increasing of the n-butanol concentration negatively affected the rate of esterification. The acetic acid conversion was improved as the initial molar ratio n-butanol-to-acetic acid was raised.

The gasoline blending prediction models available in the open literature: Linear method, Ethyl method, Stewart method, Zahed method, and Twu method were tested on 25 gasoline blends prepared from 14 components used by LUKOIL Neftohim Burgas (LNB) refinery to produce commercial gasoline grades. The performed tests with these models showed prediction accuracy outside of the acceptable ASTM D 2699 and ASTM D 2700 reproducibility limits. However, the LNB-modified regression model of Zahed method turned out to predict RON and MON of studied gasoline blends with accuracy equivalent to the reproducibility of the standard methods for measurement of RON and MON.

H-Oil vacuum gas oils obtained during hydrocracking of vacuum residual oils originated from the crudes Russian Export Blend, Basrah light, and Heavy Kazakh were cracked in a mixture with a hydrotreated vacuum gas oil in the LUKOIL Neftohim Burgas commercial fluid catalytic cracking (FCC) unit. Some of the H-Oil vacuum gas oils were also cracked in a laboratory FCC (ACE) unit. The results from the commercial and the laboratory tests showed that the laboratory FCC experiments in an ACE unit can be used to evaluate the effect of feed quality on the commercial FCC unit performance. The assumption that the conversion of a vacuum gas oil (VGO) blend in the fluid catalytic cracking could be considered as a linear combination of the conversion of the individual components made by other researchers was also confirmed in this study. The higher the hydrogen content in the vacuum residual oil of a crude is the higher the FCC conversion of the H-Oil VGO, obtained during hydrocracking of that high saturate vacuum residual oil, will be expected.

The bending elasticity is the mechanical property that characterizes the deformability of lipid bilayers. In the present study the bending elasticity of phosphatidylcholine lipid membranes is reported in aqueous media with various chemical composition and pH. The bending modulus is obtained from analysis of the thermal shape fluctuations, performed on nearly spherical giant lipid vesicles. Lower bending rigidity of phosphatidylcholine bilayers is measured in aqueous media, containing potassium or sodium chlorides, compared to its value in water without salts. The results reported here for the membrane bending elasticity at three acidic values of pH are compared with the literature data from micromanipulation measurements of giant unilamellar vesicles from the same lipid. In accordance with previous results, further evidences are provided for the softening of lipid bilayers in the presence of sucrose in the aqueous surroundings.

Aim Incretins [dipeptidyl peptidase-4 inhibitors (DPP-4i) and glucagon-like peptide 1 RA (GLP-1 RA)] and sodium-glucose cotransporter-2 inhibitors (SGLT-2i) groups are now routinely used for type 2 diabetes therapy and comprise a large number of medicinal products. The long term therapeutic and economic effect of the incretins' and SGLT-2i in real life setting is not well documented. The goal of the current study is to analyze the cost and results of incretins and SGLT-2i based therapy for type 2 diabetes in Bulgaria. Methods The study uses information about the changes in glycated hemoglobin (HbA1c) level from the National diabetes register for 6122 patients and cost paid by the National Health Insurance Fund (NHIF) for diabetes complications, and medicine prices. Results The results show that after the therapy patients achieved excellent diabetes control. There were no HbA1c values less than 6% before treatment. After the therapy, 3356 people showed values less than 7% HbA1c. It is considered very good diabetic control. The number of people with HbA1c above 8% is decreasing significantly. The number of people with values above 9% is decreasing by almost four times. HbA1c level decreases with the highest percentage for the patients treated with GLP-1 RA, followed by those treated with DPP-4i and SGLT-2i. For a year NHIF reimbursed 5.25 million BGN for incretins and SGLT-2i therapy. NHIF can save between 306 and 510 thousand BGN from incidents that have not occurred as a result of 5 years of therapy. Conclusion Incretins [dipeptidyl peptidase-4 inhibitors (DPP-4i) and glucagon-like peptide 1 receptor agonists (GLP-1 RA)] and sodium-glucose linked transporter-2 inhibitors (SGLT-2i) therapy steadily decreases the HbA1c level, and risk of developing diabetic incidents is reduced to between 333 and 465 cases among 6122 treated patients. Avoided cost for therapy of diabetes incidents account for between 305 and 510 thousand BGN.

This work summarizes the results of multiple experiments performed in the LUKOIL Neftohim Burgas Research Laboratory related to the issue of high values of hot filtration test (HFT) of the residue H-Oil hydrocracking residual oil products. After the start-up of the new residue H-Oil hydrocracker in the LUKOIL Neftohim Burgas refinery during the second half of 2015 the values of the HFT of the vacuum tower bottom product varied between 0.01 and 8.7%. It was found that the vacuum residual oil feed source has a profound effect on the processes of sedimentation in the H-Oil hydrocracker. The processing of vacuum residual oils from Arab medium, Arab heavy, and Basrah light crudes reduced the sedimentation and allowed achievement of a higher conversion. The H/C ratios of asphaltenes from all studied feeds decreased after hydrocracking. However, the decrease of the H/C ratio was the least pronounced with the Basra light asphaltenes, while the H/C ratios of asphaltenes from the vacuum residual oils originating fr...

Data from assays of 244 crude oils (condensates, extra light, light, intermediate, and heavy crudes) were processed by the InterCriteria Analysis with the aim to investigate the relationships between bulk properties and fraction properties of the crude oils and the degree of similarity between them. It was found that except the crude bulk properties sulfur, Conradson carbon, and metals content all other studied crude bulk properties exhibited lack of statistically meaningful relations or presence of weak statistically meaningful relations with the crude fraction properties. The use of the InterCriteria Analysis showed that crudes with very similar properties could be identified when a large crude database is available. In this way based on a previous experience in oil refining a selection of potentially beneficial new crudes for processing in a refinery could be made.

Chalcogenide glasses are the advanced materials of choice for the emerging nanoionic memory devices – conductive bridge random access memory (CBRAM). To understand the nature of the effects occurring in these devices under influence of electron-beam radiation, the interaction of blanked chalcogenide films and nanostructured films containing chalcogenide glass and silver (Ag) source are studied. Raman spectroscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction are used for establishing the structural and compositional effects occurring under radiation. They have strong compositional dependence with the stoichiometric compositions being most stable showing less structural changes after radiation. These effects are associated with the availability of lone-pair electrons, their participation in the bonding configurations and the coupling of electron states in the bandgap. They are further enhanced in the bilayers by silver diffusion in the chalcogenide matrix, as a result of interaction with electrons. These effects are used to interpret the electrical performance of CBRAM devices after radiation. The devices are characterized by their resistance states, threshold voltage and endurance. Those based on selenium-rich and stoichiometric composition undergo continuous parameters changes with increase in the radiation dose while in the devices based on germanium-rich composition a counter play of the structural changes and expulsion of silver occur.

Five empirical methods toestimate the content of aromatic, naphthenic, and paraffinic carbon and hydrogen content and the bulk properties were tested for prediction of aromatic structures content of 95 vacuum gas oils. The density demonstrated the highest correlation with the aromatic structures content among all other studied bulk properties and empirical parameters. The aromatic structures content could be predicted by a second order power law dependence on density with accuracy commensurable with the reproducibility of SARA analysis. The poly-nuclear aromatic structures content was also found to depend on the density and can be expressed by a linear function.

36 vacuum residual oils, obtained from all available groups of crude oils in the world along with their deasphalted oils and their asphaltene fractions have been investigated in this work. Correlations were derived which show that the vacuum residual oil bulk properties density, Conradson carbon content, and viscosity correlate with residual oil hydrogen content, H/C atomic ratio, the fraction of aromatic carbon, saturate, and asphaltene content. It was found that the VRO metal (Ni + V) content was almost evenly distributed between the maltene and the asphaltene fractions. The data in this work presented contradictory facts about the molecular weight of the VRO asphaltene fractions. The simulation distillation data (ASTM D-7169) and Goosens’ correlation support the statement of Mullins et al. that the asphaltene fractions may have molecular weight of about 750 g/mole. The atmospheric residue physical distillation data (ASTM D-5236) and Riazi’s boiling point distribution model, however support the statement that the asphaltenes are concentrated in the higher boiling point, higher molecular weight VRO fractions. The higher the aromaticity of a heavy oil, the higher its viscosity is. Since the asphaltenes are the most aromatic compounds in a heavy oil their influence on the heavy oil viscosity is the biggest among all other heavy oil constituents. The converted vacuum residual oils (from visbreaking and residue ebullated bed H-Oil hydrocracking) demonstrated lower dependence of viscosity on the asphaltene content. This could be a result from decreasing of the dimensions of the macro-structure of the converted asphaltene molecule.

A rapid and simple method for the determination of benzene and oxygenates in petroleum by heart-cutting gas chromatography is reported. Experimental design was used to optimize the chromatographic resolution with a short analysis time by improving the injection volume, split ratio, oven temperature, and oven ramps, with seven Deans’ switching heart-cutting applications. The analyses were performed by internal standardization and seven oxygenates and benzene were determined within 20 min. The calibration curves were linear across the tested ranges. The developed method was validated; the precision and accuracy were lower than 2.0 and 2.8%, respectively. The uncertainty was between ±0.012 and ±0.04%.

Liquid products produced from two different types of waste pyrolysismunicipal wastes and spent tyre wastes are investigated using gas chromatography—mass spectrometry. This method has been applied for detailed identification of composition of the samples. The components were characterized in terms of their Kovats retention indices on a PONA capillary column. The obtained analytical data were successfully used for the characterization of the samples. More than three hundred compounds were detected. The liquid products were complex mixtures, composed mainly of C4—C12 compounds. The examination of the selected m/z values very clearly indicates the existence of the different groups of compounds. With a lot of olefins content (31.9%), followed by aromatics (20.0%), paraffins (17.3%), and naphthenes (7.5%), it is described as the liquid product from pyrolysis of municipal solid wastes. The aromatic compounds in liquid product from pyrolysis of spent tyre wastes have the highest concentration (33.5%), and they a...

Archaeal single-cell microorganisms are characterised by particularly strong resistance to harsh environments at extreme temperature ranges, pH values, high pressure and salinity. The recognition of molecules rendering the archaeal membranes stable in such conditions represents an important step towards understanding the molecular mechanisms, which underlie the cellular survival, in order to effectively exploit them in biomedicine and bionanotechnology. Here we report on the bending elasticity and phase behaviour of model lipid membranes containing tetraether archaeal lipids. The bending elasticity modulus of membranes composed of palmitoyl-oleoyl phosphatidylcholine and glycerol dialkyl glycerol tetraether extract from the archaeon Thermoplasma acidophilum’s plasma membrane is measured by analysis of the thermal shape fluctuations of nearly spherical giant unilamellar vesicles (tens of micrometers in size). The bending rigidity is reported to non-monotonically depend on the archaeal lipids’ concentration in the bilayer. At 50 wt% of tetraether lipids in the membrane we measure around 20% decrease of the bending modulus compared to the studied single-component phosphocholine bilayer. The membrane resistance to bending increases at archaeal lipids’ content higher than 70 wt%. These findings support the hypothesis about a probable looping conformation at very low amounts of bipolar lipids in the membrane and prevailing spanning tetraether molecules at higher concentrations. Fluorescence microscopy reveals structural phase coexistence at low temperatures (6 °C) for 75 wt% of bolalipids in the bilayer. Laurdan spectroscopy measurements of large unilamellar vesicles (hundreds of nanometers in size) provide evidences for increased lipid ordering at the glycerol level induced by the presence of up to 90 wt% of bolalipid in the bilayer. At this archaeal lipid content we measure increased bending rigidity of the membrane. The fatty acyl chain mobility probed by DPH fluorescence spectroscopy is significantly reduced in the presence of bolalipids. The lipid ordering decreases with increasing the temperature to an extent depending on the bolalipid content in the membrane. The presence of bipolar lipids in the bilayer affects the lipid packing more strongly at the glycerol level compared to the hydrophobic core of the membrane. By elucidating the effect of tetraether lipids on the structural and mechanical properties of the bilayer, the reported results are expected to help in advancing on liposome-based pharmaceuticals and biomedical applications as well as for developments in sensorics and nanotechnology.

Silver photodiffusion into amorphous chalcogenides involves the movement of ions controlled by a UV-visible light illumination, and has potential application to memory devices. Understanding the kinetics of this phenomenon will expand the range of possible applications. Herein, we report the excitation photon energy dependence of the silver photodiffusion kinetics in Ag/amorphous Ge20S80/Si substrate stacks, probed by neutron reflectivity using four light-emitting diodes with different peak wavelengths. Time-dependent changes were clearly observed in all three of the Ag/Ag-doped reaction/chalcogenide host layers, in terms of layer thickness, scattering length density, and roughness. Silver photodiffusion effectively occurred when the excitation photon energy was greater than the optical gap of the chalcogenide host material. Excitation of lone-pair electrons to anti-bonding states at the chalcogenide layer therefore appears to play a crucial role in triggering silver photodiffusion.

Conductive bridge resistance change (CBRAM) memory devices are one of the premier emerging technologies for non-volatile memory. The application of these devices could overlap possible situations where they are expected to perform in environments containing X-ray radiation. This poses the question, how X-ray radiation affects the materials comprised within these devices, as well as the performance of the CBRAM devices. In this work, we studied the structural changes caused by a wide range X-ray radiation over thin Ge–Se films with composition ranging from Se rich to Ge rich, as well as X-ray induced Ag diffusion within these films. The results show that after the cessation of radiation, the Ge rich films undergo considerable structural modification while the other compositions did not exhibit substantial changes. X-ray stimulated Ag diffusion with formation of Ag–Se by-products occurred predominantly in the Se and Ge rich films. These effects influence the performance of the CBRAM devices, based on these films and their I–V characteristics, threshold voltage and endurance are presented and discussed in the context of the materials characterization findings of this work, performed by Raman spectroscopy, Energy dispersion spectroscopy and X-ray diffraction.

Nine vacuum residual oils were characterized and eight blends of them were processed in the LUKOIL Neftohim Burgas commercial visbreaker unit. It was found that at constant content of about 8 vol.% of the fraction boiling up to 360 °C (diesel cut) in the visbroken residue the visbroken residue viscosity correlated with the vacuum residual oil visbreaker feed viscosity with a squared correlation coefficient R 2 > 0.98. By application of correlation analysis and intercriteria analysis the vacuum residual oil feedstock parameters which have statistically meaningful impact on conversion to product boiling below 360 °C were found to be vacuum residual oil sulfur and hydrogen content, and solubility power of maltenes. The results obtained in this work are consistent with those obtained from other groups, even for other types of vacuum residue processing like ebullated bed hydrocracking. The vacuum residual oils which contained more resinous-asphaltenic materials formed more asphaltenes in the process of thermal conversion. The vacuum residual oil viscosity increment with increasing of asphaltene content for the straight run vacuum residual oils can be described by a second order polynomial. The secondary vacuum residual oils — the visbroken vacuum residual oils exhibited a lower than straight run residual oil dependence of the residue viscosity increment on increasing of the asphaltene content.

Programmable metallization cell (PMC) devices work by growing and dissolving a conducting metallic bridge across a chalcogenide glass (ChG) solid electrolyte, which changes the resistance of the cell. PMC operation relies on the incorporation of metal ions in the ChG films via photo-doping to lower the off-state resistance and stabilize resistive switching, and subsequent transport of these ions by electric fields induced from an externally applied bias. In this paper, the static on- and off-state resistance of a PMC device composed of a layered (Ag-rich/Ag-poor) Ge30Se70 ChG film with active Ag and inert Ni electrodes is characterized and modeled using three dimensional simulation code. Calibrating the model to experimental data enables the extraction of device parameters such as material bandgaps, workfunctions, density of states, carrier mobilities, dielectric constants, and affinities.

Kinetic data for hydroperoxide formation in a commercial biodiesel, produced from 50% sunflower oil and 50% rapeseed oil were obtained by using rapid, higher than standard temperature procedure with sufficient oxygen solubility in the samples. Three different mathematical methods for processing the data and shelf life determination of the studied biodiesel are compared. The applicable methodologies are hydroperoxide concentration abrupt increase graphical determination and Q rule. The calculation shows that shelf life of the studied stabilized Bulgarian biodiesel amounts between 1.17 and 1.27 years. It was also found that peroxide value for induction period at 15 °C is 71.8 meq O 2 /kg biodiesel.

In this paper, previous work on chalcogenide-glass (ChG)-based radiation sensors is extended to include the effects of mechanical strain and temperature stress on sensors formed on a flexible polymer substrate. We demonstrate the feasibility of producing inexpensive flexible radiation sensors, which utilize radiation-induced migration of ${\rm Ag}^{+}$ ions in germanium selenide ( ${\rm Ge}_{20}{\rm Se}_{80}$ ) films to produce a decrease in resistance of several orders of magnitude between surface electrodes. This change in resistance can be related to total ionizing dose to give an instantaneous readout of radiation exposure. The ChG films are inherently flexible and this, along with an extremely simple device fabrication process at or near room temperature, allows inexpensive sensor structures to be fabricated on lightweight pliable polymeric substrates such as polyethylene napthalate (PEN). Test samples were irradiated with ionizing radiation (UV light and $^{60}$ Cobalt gamma rays). Irradiated samples were subjected to both tensile and compressive stress, and elevated operating temperatures. Stress and exposure to increased ambient temperature had little effect on device resistance. Analysis of the experimental data is supported by the results of COMSOL simulations that model radiation-induced lateral Ag diffusion in ChG.

The thermal conversion of fifteen vacuum residual oils (VROs) having different properties was investigated in a modified high-temperature–high-pressure batch autoclave reactor. It was found that the sediment level (toluene insoluble) in the unconverted residual oil demonstrated a behavior typical for presence of induction period. The sediment level at the end of the induction period was mostly influenced by feedstock colloidal stability. The rate of sediment formation after the induction period was mostly influenced by VRO resin content. The results in this study do not support the assumption that the more aromatic VROs generate more coke-like sediments during thermal conversion. The higher density and aromatic VROs generated less sediment. The addition of high aromatic fluid catalytic cracking (FCC) slurry oil to a VRO decreased the thermal reactor surface deposit. The effect of this coke-like reactor sediment reduction is attributed to improvement in VRO asphaltene solubility by the high aromatic FCC slurry oil and a possible hydrogen donating properties of this gas oil. The use of a synthetic dispersant was found to improve the asphaltene solubility limit and extend the period of conversion without forming coke-like deposit in the thermal cracking reactor. The FCC slurry demonstrated a stronger inhibition effect on sediment formation than the synthetic dispersant probably because it is a stronger solvent and/or because it possesses hydrogen donating properties.

The paper presents results from the research of the influence of the parent material on the mechanical compo-sition of calcomelanosols, calcocambisols and terra rossa. The contents of the fine soil separates in the calcomelano-sols vary depending on the subtype. The physical sand fraction (coarse sand + fine sand) in the Amo horizon amounts 44.81% in the organomineral calcomelanosols, 40.13% in the organogenic and brownised calcomelanosols 36.52%. In the (B)rz horizon in the brownised calcomelanosols it amounts 32.64%. The content of clay + silt or physical clay in the Amo horizon amounts 55.19% in the organomineral calcomelanosols, 59.87% in the organogenic and the high-est content is in the brownised calcomelanosols 63.48%. The average value of this fraction in the horizon (B)rz in the brownised calcomelanosols amounts 67.36%. In the calcocambisols the average content of the fraction physical sand in the Amo horizon amounts 33.43%, and in the cambic horizon (B)rz 22.50%. In the terra rossa the fraction physical clay is represented with a greater percentage related to the physical sand fraction. In the Amo horizon, in the physical clay fraction, the clay fraction is predominant, average 43.08%, and 52.13% in the cambic horizon, and 24.90% in the Amo horizon and 19.37% in the (B)rz horizon for the silt fraction. From a research soils 36% of the soils are formed on massive limestone, 13% are formed on dolomitic limestone and bituminous marbles, 16% on plate (flat) limestone, 10% on dolomitic marbles and 12% on laminated (plate) dolomite and calcite.

The geometry, electronic structure and chemical reactivity of a pyridinium-based ionic liquid, pyridinium hydrogen sulfate ([H–Pyr] + [HSO 4 ] − ), have been discussed on the basis of quantum chemical density functional theory calculations using B3LYP/6-311+G(d,p) and B3LYP/6-311++G(2d,2p) approaches. The calculations indicated that [H–Pyr] + [HSO 4 ] − exists in the form of an ion pair. A large electropositive potential was found on the pyridinium ring, while the regions of a negative electrostatic potential is linked with the lone pair of electronegative oxygen atoms in hydrogen sulfate anion ([HSO 4 ] − ). Electron transfer both within the anion, and between the anion and cation of an ion pair were described using natural bond orbital theory. The energy values of −7.1375 and −2.8801 eV were related to HOMO and LUMO orbitals, respectively.

The elastic properties of anion lipid-containing bilayers were studied in aqueous solutions with fixed ionic strength at pH ≤5. Giant vesicles from stearoyl-oleoyl-phosphatidylcholine (SOPC) with various contents of dioleoyl-phosphatidylserine (DOPS) were obtained via electroformation and observed in phase contrast and fluorescence. Two structural phases were found to coexist in vesicle membranes. Thermal fluctuation spectroscopy of quasispherical vesicles with homogeneous liquid membranes was applied for the quantification of their bending rigidity. The white-noise contribution, significantly influencing the calculated value of the bending modulus, was taken into account in the analysis of the thermal shape fluctuations of vesicles. Electrokinetic measurements with SOPC/DOPS liposomes provided information about their surface potential dependence on pH and also as a function of the DOPS molar content in bilayers. The experimentally obtained values for the bending rigidity of SOPC bilayers containing various amounts of DOPS are reported and discussed in the light of the existing theory for the electrostatic contribution to the bending modulus of charged lipid membranes.

We report on the effect of lyso- and polyunsaturated fatty acid (PUFA)-containing lipids on the bending elastic properties of lipid membranes. The bending stiffness of monounsaturated phosphatidylcholine (POPC) bilayers with various molar fractions of an omega-3-containing phosphatidylcholine (PDPC) and/or a lysophosphatidylcholine (lyso-PC) was measured by thermal shape fluctuation analysis (TSFA) performed on quasispherical giant unilamellar vesicles (GUV). Strong evidences of their softening effect on lipid bilayers are provided together with data suggesting different degree of influence of the two molecules on the membrane bending elasticity. The effect of lyso-PC on the bending stiffness of POPC membranes was shown to be stronger than the PDPC. We conclude that the PDPC and lyso-PC are most likely controlling the membrane deformations by modulating its elastic properties.

To better understand the dynamics of silver photodiffusion into amorphous chalcogenide (Ch) films, it is informative to probe the time-dependent distribution of silver in the films while they are simultaneously exposed to visible light. Time-resolved neutron reflectometry is particularly well-suited to this purpose because it can follow time-dependent changes in the multilayer structure (Ag/Ag–Ch/Ch) while excluding the possibility of probe beam induced changes. This paper reports the results of time-resolved neutron reflectivity measurements of two Ag/GexS1−x(x = 0.2 and 0.4) films as they are exposed to a visible light source. Analysis showed that silver diffusion occurs via two distinct processes: a fast diffusion that takes place during the first 2 and 10 min of sample illumination for the x = 0.2 and 0.4 films, respectively; and a subsequent slower change that is observed over the next 18 min (x = 0.2 film) and 107 min (x = 0.4 film). These results suggest the formation of a relatively stable Ag-rich phase in the reaction layer followed by slower diffusion at the interface between Ag-rich and Ag-poor layers. Fourier transform analysis shows that the position of the interface is essentially fixed — a conclusion that contradicts the “diffusion front” model that has been previously postulated.

The focus of this work is on the formation of a lithography-free redox conductive bridge memristor array, comprised of different compositions of GexSe1−x chalcogenide glasses with the aim of selecting the chalcogenide material that provides the best performance. Various memristive arrays were fabricated on a metal–chalcogenide–metal stack. This structure offers high device density with the simplest configuration and allows access to each nano redox conductive bridge device. It was found that the device stability and threshold voltage were a function of the chalcogenide glass composition, with the Ge-rich film contributing to the best device performance, which is attributed to the formation of rigid structure and the availability of Ge–Ge bonds. Additionally, these parameters were dependent on the thickness and the surface roughness of the chalcogenide glass. Application of a nonlithography method for fabricating the array structure offered excellent yield, stable ON–OFF states and good uniformity. This demonstration, along with success achieved at the single cell level, suggests that the redox conductive bridge memristor is well positioned for ultrahigh performance memory and logic applications.

Thirteen vacuum residual oils originating from Russia, Middle East, Asia, and South America were thermally cracked in a modified high-temperature–high-pressure batch autoclave reactor. It was found that the colloidal stability of the vacuum residual oils expressed by S-value was the dominant factor that affected the residue thermal reactivity. SARA analysis data of the residual oils were confirmed to contain insufficient information about residue thermal reactivity and colloidal stability. It was found that the higher the colloidal stability of a residual oil the lower residue thermal reactivity and the steeper colloidal stability reduction during thermal conversion. The asphaltene solubility was found to linearly decrease with the increase of the thermal conversion, while the maltene solubility power did not always decrease with the increase of the thermal conversion for the studied residual oils. Having in mind that the ebullated bed residue hydrocraking H-Oil process is also based on thermal conversion the properties of commercial straight run Urals vacuum residue (UVR), visbreaker residue obtained by thermal cracking of UVR (UVBR), and ebullated bed hydrocracking (H-Oil) unconverted residue were investigated. It was found that asphaltene solubility lowered linearly with increasing of conversion regardless of the process: visbreaking or ebullated bed hydrocracking. The maltene fraction average molecular weight seems to decrease with the increase of the residue thermal conversion processes visbreaking and ebullated hydrocracking as the asphaltene average molecular weight does for the same processes. It was found that the atmospheric gas oil fraction from visbreaker has no negative effect on residual oil colloidal stability while the vacuum gas oil fraction has negative impact on residue stability in both visbreaker and H-Oil unconverted residual oils. The data generated in this work study suggest that the asphaltene solubility has a bigger impact on the residual oil colloidal stability than the maltene solubility power.

This work focuses on the study of Ge rich phases in the Ge–Se chalcogenide glass system. Radiation induced effects particularly related to Ag diffusion in the glasses under the influence of different doses of γ radiation are investigated and documented. Raman spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, and atom force microscopy confirmed the occurrence of radiation-induced Ag diffusion and oxidation of the hosting chalcogenide thin films. This causes Ag surface deposition and structural reorganization of the hosting backbone, and affects the electrical performance of the films. It is suggested that the sensing ability of the thin films can be substantially influenced by the encapsulating the sensing elements to avoid the oxidation of the chalcogenide film.

Programmable metallization cells (PMCs) are emerging ReRAM devices exhibiting resistance switching due to cation transport in a solid-state electrolyte and redox reactions at the electrodes. Their non-volatility and low power requirements have led to increased interest in their development for non-volatile memory applications. Investigation of the total dose response of PMCs will contribute to our understanding of radiation induced effects in these novel memory devices as well as assess their suitability for use in ionizing radiation environments. This work investigates the impact of total ionizing dose on the switching characteristic of silver doped Ge30Se70 PMC memory devices. The results obtained show that the resistance switching characteristic of these cells which use a solid state electrolyte based on Ge30Se70 is not affected by a total dose exposure of up to 10 Mrad( Ge30Se70).

In this study we demonstrate the potential radiation sensing capabilities of a metal-chalcogenide glass (ChG) device. The lateral device senses radiation-induced migration of Ag+ ions in germanium selenide glasses by measuring changes in electrical resistance between electrodes. These devices exhibit a high-resistance `OFF-state' (~ 1012 Ω) before irradiation, but following irradiation with either 60Co gamma-rays or UV light, their resistance drops to a low-resistance `ON-state' (~ 103 Ω). The devices have exhibited cyclical recovery with room temperature annealing of Ag doped ChG, which suggests potential use in reusable radiation sensor applications. Furthermore, the mechanisms of radiation-induced Ag/Ag+ transport and reactions in ChG are modeled using a finite element device simulator. The essential reactions captured by the simulator are radiation-induced carrier generation, combined with reduction/oxidation for both ionic and neutral Ag species in the chalcogenide film. The results provide strong qualitative evidence that finite element codes can simulate ionic transport reactions in the ChG and reveal plausible mechanisms for radiation-induced metal doping.

We present data on radiation-induced effects in chalcogenide glasses that also trigger radiation induced structural reorganization contributing to silver (Ag) diffusion. To study these effects and silver diffusion, depending on the radiation dose, films were prepared and analyzed using Raman spectroscopy, X-ray diffraction and Energy Dispersion X-ray Spectroscopy. The results show a structural development occurring in films containing 45.4 at.% Ge with increasing radiation dose defined by increase in the edge-sharing/corner-sharing ratio, higher ethane-like unit values and rise of the amount of Ag diffused within the system. Utilizing these effects, a resistance based radiation sensing device has been created. The I–V curves characterizing the sensor operation demonstrate decreased device resistance as a result of the radiation.

Solid state electrolytes fabricated with chalcogenide glass (ChG) are considered viable candidates for the next generation of non-volatile memory technologies. These glasses, which are composed of group IV and/or group V elements with those of group VI chalcogens (S, Se, and Te), are excellent metal ion conductors. Because of this property, the resistance across structures composed of ChG films sandwiched between active metal (e.g., Ag) and inert metal (e.g., Ni) electrodes can be switched upon the application of sufficient bias, thereby enabling memristive action. In this paper, the effects of 60Co gamma-ray irradiations on Ag/Ge30Se70 test structures are investigated. The results show that exposure to high-energy photons can trigger the transport of Ag+ & ions from an active Ag top layer into an underlying Ge30Se70 ChG film. Post-irradiation annealing experiments also indicate that this “photo-doping” process is reversible once the radiation stress is removed. Numerical simulations which model the mechanisms of radiation-induced photo-doping and recovery are shown to agree well with the data. The results and analysis presented in this paper suggest the ChG-based memristors may be more susceptible to transient radiation effects than cumulative radiation damage.

We report the results of our study on the impact of variable atomic ratio of Ge x Se 1-x on the total ionization dose (TID) influenced lateral diffusion of Ag into chalcogenide glasses (ChG) in flexible radiation detection sensors.

In this work we present data about electronic devices based on a planar structure; inert electrode/nanophase chalcogenide glass/inert electrode in close proximity with a source of silver (Ag) oriented laterally over the chalcogenide glass film. The conductivity of the devices changes with radiation and it can be measured by contacting the two inert electrodes. Spacing of the electrodes was chosen after an in-depth investigation into the electric field (E-field) and E-field energy displacement simulations with the aid of COMSOL multi-physics software. Simulations have been used to enlighten a specific device structure to perform in situ measurements. Bias voltages, inert electrode material and thickness of the films were used as standards for all different types of simulations while only varying the spacing and the geometries to affect the E-fields. It has been established from the experimental results that a 1 V bias is the most appropriate for the device performance and this is the voltage used in the simulations. The key motivation for this research is to find appropriate dimensions and geometry, which do not cause a change in conduction as a direct result of the applied E-field, but rather effectively contribute to the establishment of only the radiation induced change of the device conductivity. The process flow for the device fabrication is described and data from the device performance are presented as well. The radiation induced Ag doping is mapped in the device volume using electron dispersion X-ray spectroscopy (EDS) (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In the present study we have made a review of the relevant literature on pathogenesis and modern diagnostic methods for macular edema (ME) in uveitis. Macular edema is a typical non-specific complication of uveitis, one of the common causes of visual impairment. ME can be found in all types of uveitis. In 85% of cases of intermediate uveitis, the visual impairment is due to the development of cystoid macular edema. The macula is more rarely affected in panuveitis (35%), anterior (20-26%) and posterior (20%) uveitis. The etiological agent is of great importance for the course and treatment of inflammatory diseases. Among the imaging diagnostic methods that are capable of detecting macular edema with fluid accumulation in the retina (either diffuse or distributed in cysts) are the fl uorescein angiography (FA) and the optical coherence tomography (ОСТ). OCT allows a quantitative assessment of retinal thickening and how it changes throughout therapy. FA can be used to determine very precisely the site of a vascular leakage and assess how badly the vascular wall has been affected by the inflammatory process. CONCLUSION: Macular edema occurring during an inflammatory process is one of the causes for visual acuity loss in uveitis. OCT and FA are useful complementary imaging methods for investigation of structural changes in retinal architecture in uveitis patients.

This work presents a comprehensive investigation on the effect of small amounts of copper or manganese on the catalytic and photocatalytic activities of ZnO powders. The observed effects are interpreted based on the theory of chemisorption, the physics of semiconductors and the chemistry of non-stoichiometric oxides. It turns out that the nature of the investigated processes is determined mainly by both, the influence of admixtures on the electronic band structure parameters and the alteration of the sorption ability of the semiconductor surface.