Order Of Magnitude For Samples Research Articles

Optoelectrical Properties of Treated CdSe Thin Films with Variations in Indium Chloride Concentration.

The effect of a nontoxic chloride treatment on the crystallinity and optoelectrical characteristics of a CdSe thin film was studied. A detailed comparative analysis was conducted utilizing four molarities (0.01 M, 0.10 M, 0.15 M, and 0.20 M) of indium (III) chloride (InCl3), where the results showed a notable improvement in CdSe properties. The crystallite size of treated CdSe samples increased from 31.845 nm to 38.819 nm, and the strain in treated films dropped from 4.9 × 10-3 to 4.0 × 10-3, according to XRD measurements. The highest crystallinity resulted from the 0.10 M InCl3-treated CdSe films. The In contents in the prepared samples were verified by compositional analysis, and FESEM images from treated CdSe thin films demonstrated compact and optimal grain arrangements with passivated grain boundaries, which are required for the development of a robust operational solar cell. The UV-Vis plot, similarly, showed that the samples were darkened after treatment and the band gap of 1.7 eV for the as-grown samples fell to roughly 1.5 eV. Furthermore, the Hall effect results suggested that the carrier concentration increased by one order of magnitude for samples treated with 0.10 M of InCl3, but the resistivity remained in the order of 103 ohm/cm2, suggesting that the indium treatment had no considerable effect on resistivity. Hence, despite the deficit in the optical results, samples treated at 0.10 M InCl3 showed promising characteristics as well as the viability of treatment with 0.10 M InCl3 as an alternative to standard CdCl2 treatment.

Conservation of cholera vibrios in complex microcosm containing green microalgae

BACKGROUND: In the summer-autumn period, the peak of phytoplankton reproduction and flowering occurs and results in the deterioration of the quality of river water is noted. At the same time, cases of gastrointestinal diseases in humans are recorded, and epidemic complications of cholera may occur in endemic areas. V. cholerae form biofilm on the surface of chitinous hydrobionts and plastic components can lead to the spread of V. cholerae, possibly explaining the autochthonous mechanism of their existence in water bodies.
 AIM: This study determines the duration of Vibrio cholerae preservation on biotic (chitin) and abiotic (plastic) substrates in the presence of green unicellular algae with a change in cultivation temperature under experimental conditions.
 MATERIALS AND METHODS: This study used bacteriological and molecular genetic methods to achieve its goal.
 RESULTS: The preservation of toxigenic and non-toxigenic strains of V. cholerae O1 El Tor and V. cholerae O139 (ctxАВ+tcpА+csh1 and ctxАtcpАcsh1+) for six months, including three months at a low temperature simulating the autumn-winter period, as part of biofilms in microcosms, where one component is green microalgae. We noted an excess of the concentration of V. cholerae O1 and O139 serogroups by two orders of magnitude in samples where one of the components is chitin and the reproduction of green microalgae in the presence of a chitin substrate. This is probably one stage in the food chain in the ecology of water bodies and, accordingly, can be a reservoir for biofilm forms of cholera vibrios. Preservation of V. cholerae O1 El Tor non-toxigenic strain in a viable state in biofilm samples on plastic at decreased temperatures 82C for three months is possibly due to the presence of a cold shock gene in its genome.
 CONCLUSION: Without a substrate for adhesion, colonization, and biofilm formation, vibrios are incapable of long-term persistence at low temperatures.

QUALITY AND AEROBIC STABILITY OF FERMENTED ROLLED CORN GRAIN IN UNDER COMBINED INTRODUCTION OF PROBIOTIC STRAINS OF LACTIC ACID BACTERIA AND REPRESENTATIVES OF BACILLUS SUBTILIS

Objective. To find out the effect of combined introduction of probiotic strains of lactic acid bac-teria and Bacillus subtilis on the quality and aerobic stability of fermented rolled corn grain. Methods. Microbiological, zootechnical. Results. According to the results of organoleptic analysis, preserved rolled corn grain of the experimental and control variants had a preserved texture with a pleasant fruity odour. Preservation of crude fibre in the raw material of the experimental variants treated with Bacillus subtilis ВРT-B1 and under the combined use of lactic acid bacteria with aero-bic bacilli was higher by 10.0 % and 3.3 %, respectively, as compared to positive control parame-ters (Subtikon grain processing). The protein content in the experimental variants and the positive control was higher by 2.4–7.2 % than in the control variant of the feed (without the use of microor-ganisms). After aerobic exposure of feed for 14 days, preservation of crude fibre in all variants be-gan to decrease, however, the greatest losses (20 %) were noted in the control variant (without in-troduction of bacteria). The highest protein losses were observed in the control variant (3.8 %).After aerobic exposure, acidity in all variants of the experiment remained in the optimal range of pH 3.9–4.2. At day 70 of feed preservation, an increase in the number of lactic acid bacteria by 2–3 orders of magnitude in samples of experimental variants and positive control in comparison with this parameter in the raw material was noted. After air access to preserved rolled corn grain for 14 days, the lowest number of lactic acid bacteria was observed in absolute control, the high-est — in the variant with the combined inoculation by strains of Lactobacillus plantarum КT-L18/1 and Bacillus subtilis ВРT-B1. No pathogenic and butyric acid bacteria were detected. Conclusi-on. The combined use of probiotic strains of lactic acid bacteria and Bacillus subtilis to preserve corn grain contributes to the preservation of nutrients, the establishment and maintenance of an op-timal level of acidity, prevents aerobic food spoilage.

Effect of high temperature LiPON electrolyte in all solid state batteries

Thin film solid state Li4Ti5O12-based batteries are developed by using amorphous Lithium Phosphorus Oxynitride (LiPON) electrolyte deposited by reactive sputtering at different substrate temperatures (Tdep). Such layers maintain their amorphous character even at higher Tdep. The stoichiometry, ionic conductivity, thermal stability and overall effect on full battery stacks were investigated. The ionic conductivity falls down by nearly three orders of magnitude for samples deposited at higher temperatures while no significant compositional variations are found, in contrast with previous reports. This is interpreted as the creation of a highly thermally stable LiPON glass with a closed-packed structure which inhibits Li-ion diffusion. The onset of the glass transition (Tg) and the crystallization temperature (Tc) of LiPON shifts to higher temperatures as Tdep increases. Galvanostatic (dis)charge measurements on fully operational thin film batteries show a decrease in capacity and a worsened C-rate performance as LiPON Tdep increases. Despite the lower ionic conduction, the improved thermal stability reported here using LiPON whose properties can be properly tuned could open interesting scenarios in future advances in solid-state battery systems and new possibilities in high temperature applications.

Effect of hydrogen charging on dislocation multiplication in pre-strained super duplex stainless steel

The effect of hydrogen charging on dislocation multiplication in super duplex stainless steel was investigated. Steel samples were pre-strained and charged with hydrogen for 10days. Dislocation density was then measured using neutron diffraction. It is found that dislocation density multiplies by about one order of magnitude in samples with less than 5% pre-strain, but remains the same level in samples with pre-strain level of 10% and above.

Dependence of minority carrier lifetime of Be-doped InAs/InAsSb type-II infrared superlattices on temperature and doping density

We investigate the minority carrier lifetime of Be-doped InAs/InAsSb type-II superlattices as a function of doping density and temperature using time-resolved photoluminescence (TRPL) to determine if switching the superlattice type from the typical n-type residual carrier concentration to p-type may improve device performance by improving the lifetime–mobility product. The introduction of the Be dopant to the superlattice reduces the carrier lifetime, first by a factor of ∼3 for doping densities near or below the n-type residual carrier concentration, then by an order of magnitude for samples doped well above the residual carrier concentration. Further, the higher-doped p-type samples demonstrate two distinct TRPL decay regimes and two peaks in the PL spectra, suggesting the formation of an additional acceptor-related recombination pathway leading to the observed shorter carrier lifetime.

Low-resistance titanium/n-type silicon (1 0 0) contacts by monolayer selenium passivation

Low-resistance Ohmic contacts fabricated by selenium passivation between titanium and n-type silicon (1 0 0) substrates have been characterized by the four-point probe and circular transmission line method. Selenium passivation terminates dangling bonds on the Si(1 0 0) surface and reduces the Schottky barrier height between Ti and n-type Si(1 0 0) substrates. Sheet resistance of the Ti–Si contacts on Se-passivated 1019 cm−3 doped Si substrates shows a ∼30% reduction as compared with control samples. Accordingly, the extracted contact resistance is reduced by about an order of magnitude for samples with different Ti thicknesses and different annealing temperatures. A 29-times reduction in contact resistivity is achieved by Se passivation on highly-doped Si-on-insulator substrates with a 500 Å un-doped Si buffer layer.

Low-resistance Ti/n-type Si(100) Contacts by Monolayer Se Passivation

Low-resistance contacts fabricated by selenium passivation between Ti and n-type Si(100) substrates have been characterized by low-temperature I-V, four-point probe and circular transmission line methods. The Ti-Si contacts on Se- passivated samples demonstrate a significant reduction in Schottky barrier height over control samples in low- temperature I-V. Sheet resistance of the contacts on Se- passivated 1019 cm-3 doped n-type Si(100) substrates shows a 30% reduction as compared with control samples. Accordingly, the extracted contact resistance decreases by about one order of magnitude for samples with different Ti thicknesses and different annealing temperatures. A 125%-2900% reduction in contact resistivity is achieved by Se passivation on highly- doped n-type SOI substrates with 500 Aå un-doped Si buffer layer. The reduction in contact resistance is attributed to the minimization of interface states between Ti and Si(100) surface.

Study of electrodeposited polypyrrole coatings for the corrosion protection of stainless steel bipolar plates for the PEM fuel cell

Polypyrrole coatings were prepared on stainless steel SS304 in order to study the corrosion protection provided by the conductive polymer in a simulated PEM fuel cell environment. The polypyrrole was deposited by electrochemical polymerization with 0.04, 0.07 and 0.14 g cm −2 onto SS304 electrodes. Polarization curves, taken after immersion for 1, 3 or 24 h in 0.1 M sulphuric acid at either room temperature or 60 °C were used as an accelerated test. For short immersion times, it was found that corrosion current densities (at free corrosion potentials), diminished up to 2 orders of magnitude for samples tested at room temperature and up to 4 orders of magnitude for samples tested at 60 °C. Furthermore, at potentials in the range of the PEM fuel cell anode potential, corrosion rates also decreased up to several orders of magnitude. However, these protective properties were lost at longer times of immersion. The addition of DBSA to the polypyrrole coatings did lead to improved corrosion current densities at the free corrosion potential, however due to the loss of passivity of these samples, the corrosion rates in the potential range applicable to PEM fuel cells were either similar to or larger than bare metal. SEM was used to determine the morphology of the coatings and showed that the most homogeneous coating was obtained for 0.07 g cm −2 polypyrrole, without the incorporation of DBSA.

Thermal stability of p-type doped amorphous silicon suboxides

We investigate the effects of thermal annealing on the optical and electrical properties of p-type doped amorphous silicon suboxide (a-SiO x :H) samples prepared by plasma enhanced chemical vapour deposition (PECVD). Changes in the microscopic structure of the amorphous network upon thermal annealing at low temperatures (<550 K) cause a dopant activation of the p-type samples. The resulting increase of the dark conductivity becomes smaller with increasing oxygen content, but still comprises almost 2 orders of magnitude for samples with 9 at.% oxygen. Thermal annealing at higher temperatures (>550 K) leads to an effusion of hydrogen, thereby reducing the optical bandgap, E 04, of the samples. The dependence of E 04 on the hydrogen content for amorphous suboxides with different oxygen content is found to be similar to that of amorphous silicon.

Optical and electrical properties of doped amorphous silicon suboxides

In this work we investigate the effects of thermal annealing on the optical and electrical properties of doped amorphous silicon suboxide $(a\ensuremath{-}{\mathrm{SiO}}_{x}:\mathrm{H})$ samples prepared by plasma-enhanced chemical-vapor deposition. Efficient p- and n-type doping is possible up to a concentration of 10 at. % oxygen. Structural properties of the films are deduced from hydrogen evolution measurements and infrared spectroscopy. Changes in the microscopic structure of the amorphous network upon thermal annealing at low annealing temperatures cause a dopant activation of the p-type samples. The resulting increase of the dark conductivity becomes less pronounced for increasing oxygen content of the films, but still comprises almost two orders of magnitude for samples with 9 at. % oxygen. N-type suboxides do not show such doping activation upon thermal annealing. Thermal annealing at higher temperatures leads to an effusion of hydrogen, reducing the optical band gap ${E}_{04}$ of the samples. The dependence of ${E}_{04}$ on the hydrogen content for amorphous suboxides with different oxygen content is investigated and found to be similar to that of amorphous silicon.

Mechanical properties of oriented emeraldine base polyaniline

The mechanical properties of high molecular weight (~ 130 000 Daltons) emeraldine base have been investigated as a function of elongation. The tensile strength is found to increase by almost one order of magnitude for samples stretched to 500% elongation compared to as-cast samples. The behaviour of breaking strain and Young modulus is essentially independent of elongation above ~300%. This behaviour has been interpreted in terms of crystalline fraction, as evaluated from X-ray diffraction measurements.

Formation of shallow donor in fluorine-implanted silicon

A shallow fluorine-related donor is reported. The donor has been revealed by capacitance–voltage profiling applied to furnace-annealed, fluorine-implanted silicon samples. The implantations were carried out at high energy, in the range 5–7 MeV. The assignment of the donor structure to fluorine results from a detailed examination of the effective space-charge distribution around the implantation range (≊4 μm) in comparison with data obtained for similar oxygen-implanted samples. The depth-integrated density of the donors formed after annealing at 700 °C is ≊3×1010 cm−2 corresponding to ≊1% of the implantation dose. The density increases by more than one order of magnitude for samples annealed only at 600 °C. In addition to the shallow donor level (or levels) a fluorine-specific level at Ec−Et≊0.15 eV has been assigned by application of deep-level transient spectroscopy.

Physiology, morphology, and biochemical composition of Riftia pachyptila at Rose Garden in 1985

Abstract Riftia pachyptila from the central clumps of tubeworms at the “Rose Garden” site on the Galapagos Rift were characterized morphologically, biochemically, isotopically, and to some extent physiologically. There was a large amount of variation between individuals with respect to each of the parameters measured. For example, the heterogeneity in the gross morphology of the individuals is documented by the variation in the relation between body weight and total length of the animals as well as in the variation in the relative proportions of the different body regions among the animals collected. Activities of enzymes involved in sulfur oxidation pathways varied by almost an order of magnitude in samples of trophosome from different individuals. Similarly, the amount of elemental sulfur and extractable lipid varied by over an order of magnitude in the trophosome samples, with elemental sulfur levels as high as 10% of the wet weight reported. Additionally, there was substantial variation in the characteristics of trophosome tissue within individuals. This variation within individuals was often as high as 50% of the total variation found in the population as a whole. There were significant differences in the levels of ATP sulfurylase and sulfide oxidase as well as elemental sulfur, water and extractable lipid contents of trophosome samples removed from the anterior and posterior ends of the worms. The stable nitrogen isotopic composition of Riftia indicate that nitrate and not molecular nitrogen is the most likely source of nitrogen for the intact symbioses, and comparisons between Riftia tissues indicate that the organic nitrogen compounds in the animal tissues are probably synthesized in the trophosome.

Influence of Al2S3 on the electrical conductivity of the Li2S−SiS2 glass system

Glasses belonging to the Li2S−Al2S3−SiS2 system have been prepared by conventional and roller quenching techniques. The region of glass formation can be extended by using twin roller quenching. The decrease in conductivity with addition of Al2S3 is less than half an order of magnitude for samples prepared by twin rollers. This is due to a decrease in fNBS2. The incorporation of Al2S3 enhances T8 significantly which could be used for high temperature applications.

Evidence for large lattice relaxation at the DX center in Si-doped AlxGa

New measurements of the energy dependence of the photoionization cross section of the DX center in Si-doped ${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$As are reported. With the use of a tunable infrared laser which provides sufficient light intensity in a very narrow wavelength range, the photoionization cross section has been measured over 6--8 orders of magnitude in samples with a variety of alloy compositions and doping concentrations. No measurable signal was observed for photon energies less than 0.8 eV. Data are analyzed in terms of a simple model which gives a value of 1.4--1.8 eV for the photoionization threshold energy. This energy is much larger than the DX-center binding energy, confirming that there is a large relaxation of the lattice when charge is captured at the DX center. The phonon mode involved in the lattice relaxation is found to be 5.5 meV.

Radiation-sensitivity enhancement and annealing variation in densified, amorphous SiO2.

The influence of $^{60}\mathrm{Co}$ \ensuremath{\gamma} radiation on densified samples of wet and dry amorphous silica has been studied through the creation and annealing of three intrinsic defects. Radiation sensitivity for oxygen-vacancy creation is enhanced by nearly 2 orders of magnitude in samples densified by only 3%. In general, defect creation efficiency is three to four times larger in wet silica than in dry both in the densified and undensified forms. Diffusion or thermal detrapping models for oxygen-vacancy annealing both suggest the activation energy for annealing increases by 0.6 to 1.0 eV when samples are densified by \ensuremath{\sim}16%. Creation of the peroxy radical through transformation of oxygen-vacancy centers is discussed.

Reduction of iron solubility in silicon with oxygen precipitates

The solubilities of iron in samples treated with various oxygen precipitation treatments were compared. The solubility of iron was reduced by almost two orders of magnitude in samples containing low-temperature oxygen precipitates. It is suggested that a new phase forms, probably an oxygen-metal rich compound that is more stable than the FeSi2 silicide. This study suggests dramatic improvements for the efficiency of gettering processes.

Electron mobility in compensated GaAs and AlxGa1−xAs

The dependence of electron mobility μ on temperature T in GaAs and AlxGa1−xAs indicates that for compensated material a term having μ∝T−1/2 causes a significant reduction in the mobility measured at high temperatures. The magnitude of the T−1/2 term in mobility, denoted μCA, is found to be linearly proportional to the compensating acceptor concentration over a range of more than two orders of magnitude in samples with no intentional doping where carbon is the major compensating acceptor. Intentional compensation using Ge and Zn is found to have no effect on μCA. Illumination (hν≳EG) has no effect on μCA. Such illumination is demonstrated to significantly reduce the size of space-charge layers at the n-i interface. Thus, the T−1/2 mobility is not due to scattering by space-charge regions as has been previously assumed. The acceptor C, or an associate involving C, is concluded to be the scattering center responsible for μCA. The effect may be due to the short-range central-cell potential resulting from the large electronegativity difference between C and the As for which it substitutes in the lattice.

The Radiation Chemistry of Aqueous Solutions of Hydrogen Cyanide in the Megarad Dose Range

at their natural pH and at pH 2.4. The solutions were exposed to high doses of 6Co gamma rays (up to 16 Mrad) causing large decompositions (up to 90%). The decomposition yield, G(-HCN), and the radiation-chemical yields of formation of NH3, HCHO, H2, CO2, and of seven amino acids were determined. Also, the total yields of nitrogen in nitrogen-containing nonvolatile compounds, G(N), were measured. The irradiated solutions exhibited positive biuret reaction and the absorbancies depend on both the dose and the initial pH. Histidine, aspartic acid, threonine, serine, glutamic acid, alanine, and glycine were found in irradiated samples. Glycine was found to be the most abundant among the radiolytically produced amino acids; strong acid hydrolysis increases its yield by one or two orders of magnitude in samples irradiated initially at pH 2.4 as well as at their natural pH. The release of amino acids on hydrolysis and the positive biuret reaction suggest the presence of peptidic material in irradiated samples both at acid and neutral pH's. To account for these findings the formation of polymers (or their segments) having a peptidic structure was taken into consideration. The polymerization reactions were assumed to be initiated by the free radicals which were produced by HCN reactions with H, OH, and ej,- species. It has been concluded that the radiolysis of dilute aqueous