Modification of poly(ethylene terephthalate) fibres with bactericides with the craze formation mechanism

The possibility of immobilizing bactericides on PET fibres by the craze formation mechanism was demonstrated. Of the bactericides investigated, Al (althosan) was a more active modifier of the fibres than Ct (catamine). The resistance of the bactericidal fibres to “wet” treatments simulating laundering conditions was demonstrated, and this allows using fabric articles made from them for a long time. __________ Translated from Khimicheskie Volokna, No. 5, pp. 34–38, September–October, 2006.     

Enzyme Induction as a Possible Mechanism for Latex-Mediated Insect Resistance in Romaine Lettuce

Plant latex is a known storehouse of various secondary metabolites with demonstrated negative impact on insect fitness. A romaine lettuce cultivar, “Valmaine”, possesses a high level of latex-mediated resistance against the banded cucumber beetle, Diabrotica balteata LeConte (Coleoptera: Chrysomelidae), compared to a closely related cultivar “Tall Guzmaine”. Latex from damaged Valmaine plants was much more deterrent to adult D. balteata feeding than latex from undamaged plants when applied to the surface of artificial diet under choice conditions; no such difference was found in choice tests with latex from damaged and undamaged Tall Guzmaine plants. The intensities of whiteness and browning were significantly higher in Valmaine latex than in Tall Guzmaine latex. The activities of three enzymes (phenylalanine ammonia lyase, polyphenol oxidase, and peroxidase) significantly increased over time in latex from damaged Valmaine plants (i.e., 1, 3, and 6 days after feeding initiation), but they remained the same in Tall Guzmaine latex. The constitutive levels of phenylalanine ammonia lyase and polyphenol oxidase also were significantly higher in Valmaine latex than in Tall Guzmaine latex. These studies suggest that Valmaine latex chemistry may change after plant damage due to increased activity of inducible enzymes and that inducible resistance appears to act synergistically with constitutive resistance against D. balteata.     

Performance characteristics of heater elements made of carbon fibres

The optimum concentration of a solution of adhesive required for impregnating CF is 35±5%, which corresponds to a 45±5% content in the fibre. An electric current is transmitted in CF due to the relatively low resistance of the fibre filaments and according to a “chain” scheme. The change in the strength of CF under the effect of cyclic double bending and preliminary loading was determined. The characteristics of the increase in the electrical resistance as a function of the number of double bending cycles, correlated with breaking of the CF filaments and a decrease in the contacts between them, were established. __________ Translated from Khimicheskie Volokna, No. 3, pp. 33–35, May–June, 2006.     

Isolation and characterization of two nonaflatoxigenic classes of morphological variants ofaspergillus parasiticus

Serial transfer of mycelial macerates of aflatoxigenic strains ofAspergillus parasiticus produced 2 morphological variants. The “fan” variant type showed flat growth, a gradient of sporulation density, absence of mycelial pigmentation and deep furrows on the back of the colony. The “fluff” variants displayed abundant aerial mycelium, sparse sporulation, absence of mycelial pigmentation and furrows on the reverse of the colony. Neither “fan” nor “fluff” produced detectable aflatoxin. In a marked mutant strain, the appearance of “fan” and “fluff” and their concomitant loss of aflatoxin production occurred whereas spore color and auxotrophic markers were retained. A parasexual diploid synthesized from the mutant strain with the “fan” phenotype produced high levels of aflatoxin whereas a parasexual diploid containing the “fluff” pheno-type produced low levels of aflatoxin. The unusual mode of isolation, the differential retention of aflatoxin and other genetic markers in a mutant strain, and the different levels of aflatoxin production in parasexual diploids with “fan” and “fluff” imply an unusual genetic mechanism for the control of the aflatoxin pathway.     

Water-resistant lime-magnesian clinker

A technological scheme has been developed for producing water-resistant lime-magnesian clinker and powders based on high-purity dolomites, dolomitized magnesite, lime, chalk, calcium carbonate, and magnesium without additives impairing the physicochemical properties of refractory materials. The hydration resistance of clinkers and granular materials containing free CaO is determined by their high density, which is equal to 95–98% of the theoretical density. The properties of such clinkers and powders give reason to expect the production of functional lime-magnesian refractories whose properties in some cases are not inferior to periclase-based analogs. __________ Translated from Novye Ogneupory, No. 9, pp. 38–40, September, 2006.     

Intraspecific Variation in Plant Defense Alters Effects of Root Herbivores on Leaf Chemistry and Aboveground Herbivore Damage

Root herbivores can indirectly affect aboveground herbivores by altering the food quality of the plant. However, it is largely unknown whether plant genotypes differ in their response to root herbivores, leading to variable defensive phenotypes. In this study, we investigated whether root-feeding insect larvae (Agriotes sp. larvae, wireworms) induce different responses in Plantago lanceolata plants from lines selected for low and high levels of iridoid glycosides (IG). In the absence of wireworms, plants of the “high-IG line” contained approximately twofold higher levels of total IG and threefold higher levels of catalpol (one of the IG) in leaves than plants from the “low-IG line,” whereas both lines had similar levels of IG in roots. In response to wireworms, roots of plants from both lines showed increased concentrations of catalpol. Leaves of “low-IG line” plants increased catalpol concentrations in response to wireworms, whereas catalpol concentrations of leaves of “high-IG line” plants decreased. In contrast, glucose concentrations in roots of “low-IG” plants decreased, while they increased in “high-IG” plants after feeding by wireworms. The leaf volatile profile differed between the lines, but was not affected by root herbivores. In the field, leaf damage by herbivores was higher in wireworm-induced compared to noninduced “low-IG” plants and lower in wireworm-induced compared to noninduced “high-IG” plants, despite induction of catalpol in leaves of the “low-IG” plants and reduction in “high-IG” plants. This pattern might arise if damage is caused mainly by specialist herbivores for which catalpol may act as feeding stimulant rather than as deterrent. The present study documents for the first time that intraspecific variation in plant defense affects the outcome of plant-mediated interactions between root and shoot herbivores.     

13C nuclear magnetic resonance spectroscopic analysis of the triacylglycerol composition of some margarines

The triacylglycerol fraction of three samples of margarine, namely “Flora” (Holland), “Kaliakra” (Bulgaria), and “Corona” (Holland), were studied by¹³C nuclear magnetic resonance spectroscopy. By examining the various carbon chemical shifts of the saturated and unsaturated carbon nuclei, “Flora” margarine was shown to contain a mixture of hydrogenated and unhydrogenated vegetable oils. This technique allowed all major acyl groups (saturated, oleate, linoleate, and linolenate) and minor acyl components [different positional isomers of long-chain (E)- and (Z)-monoenoic moieties, arising as by-products during catalytic hydrogenation] to be identified. The amount of each fatty acid present in the margarine was also estimated from the relative intensities of the corresponding signals. “Kaliakra” margarine consisted of a blend of unhydrogenated natural fats and oils that contained saturated fatty acids, oleate, and linoleate. There were no signs in the spectrum of “Kaliakra” of any (E)-isomers, nor signals associated with positional unsaturated acyl groups (other than oleate and linoleate). The sample of “Corona” margarine consisted of a mixture of hydrogenated and unhydrogenated vegetable oils and butter (1.3%). The presence of butter in this sample was identified by the characteristic carbon shifts of the C-1 to C-4 carbon atoms of butyrate. The distribution of the fatty acids on the glycerol “backbone” also was estimated by this technique.     

Heat Treatment Improves Olive Oil Extraction

To determine the effect of hot water pre-treatment on olive oil extraction, six cultivars of olive fruit (Olea europaea L. cvs. “Arbequina”, “Hojiblanca”, “Lechín”, “Manzanilla”, “Picual”, and “Verdial”) were heated at 50, 55, and 60 °C prior to laboratory scale oil extraction. Heat treatment resulted in higher oil extraction than unheated control samples. Quality parameters of the oils were not significantly (P < 0.05) affected by these treatments; however, oil stability and bitterness intensity were reduced and pigment content was increased through pre-heat treatment. This process may be incorporated economically into olive oil processing.     

Kinetic characteristics of extraction of the polymer component from a porous composite material

In a polychronic model of washing of LDPE out of a synthetic leather (SL) base with a selective solvent, the “kinetic nonequivalence” parameter of the polymer gel particles is the reflection of the characteristics of the material's pore structure and is not a function of the thermodynamic quality of the extractant. A decrease in the thermodynamic quality of the extractant is accompanied by an increase in the “strength” of the LDPE gel formed in the pores of the SL base. In extraction of LDPE from a SL base according to the mechanism of “capillary flow of gel,” the gel should be moved over the pores of the material in a sufficiently efficient regime of “hydrodynamic entrainment” by the stream of extractant. Translated fromKhimicheskie Volokna, No. 2, pp. 36–39, March–April, 2000.     

Lysine,gossypol, and nitrogen solubility in chemically treated cottonseed meals

The effects of treatment of commercial prepress-solvent extracted and direct-solvent extracted cottonseed mares with several chemical agents and solvents were studied. The analytical results for “free” and “total” gossypol of the finished meals show that treatment with aliphatic amines, followed by extraction with a suitable solvent, removed large proportions of the “free” as well as “bound” gossypol. This reduction of “free” and “bound” gossypol was accompanied, in some experiments, by an increase in the nitrogen solubility and available lysine, as compared with the results obtained with the untreated air-dried marcs. The available lysine contents of the treated mares was significnatly correlated with the nitrogen solubility in 0.02N aqueous NaOH. One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

Features of the structure of carbon fibres used as filler for carbon-fibre-reinforced plastics

The structure of carbon fibres and filaments in carbon fabrics used as fillers for carbon-fibre-reinforced plastics was investigated. The basic characteristics of the pore structure of the carbon fillers were determined. It was found that the carbon fibres Uglen-9R “b”, Uglen-9R “c”, and Uglen-9R have sorption properties that can negatively affect the quality of carbon-fibre-reinforced plastic articles.     

Pressure drop through in-bulk flax seeds

The airflow resistance of in-bulk flax seeds (Linum usitatissimum) and the effect of airflow rate, bed depth, type of packing, and presence of foreign material (“fines” and “chaff”) were studied. A good fit of the experimental data (R > 0.993) was obtained through the model DPL = cQ + dQ ² (where DPL is pressure drop per unit of bed depth, Pa/m; Q is airflow rate, m³/s-m²; c and d are constants; and airflow range is 0.011–0.141 m³/s-m²). The airflow resistance increases when bulk density and bed depth increase. In dense packing the pressure drop is 1.3 to 1.5 times the pressure drop in loose packing. The resistance increases with the increase of fines and decreases with the increase of chaff.     

In situ Control of Si/Ge Growth on Stripe-Patterned Substrates Using Reflection High-Energy Electron Diffraction and Scanning Tunneling Microscopy

Si and Ge growth on the stripe-patterned Si (001) substrates is studied using in situ reflection high-energy electron diffraction (RHEED) and scanning tunneling microscopy (STM). During Si buffer growth, the evolution of RHEED patterns reveals a rapid change of the stripe morphology from a multifaceted “U” to a single-faceted “V” geometry with {119} sidewall facets. This allows to control the pattern morphology and to stop Si buffer growth once a well-defined stripe geometry is formed. Subsequent Ge growth on “V”-shaped stripes was performed at two different temperatures of 520 and 600°C. At low temperature of 520°C, pronounced sidewall ripples are formed at a critical coverage of 4.1 monolayers as revealed by the appearance of splitted diffraction streaks in RHEED. At 600°C, the ripple onset is shifted toward higher coverages, and at 5.2 monolayers dome islands are formed at the bottom of the stripes. These observations are in excellent agreement with STM images recorded at different Ge coverages. Therefore, RHEED is an efficient tool for in situ control of the growth process on stripe-patterned substrate templates. The comparison of the results obtained at different temperature reveals the importance of kinetics on the island formation process on patterned substrates.     

Dependent light scattering in white paint films: clarification and application of the theoretical concepts

Among the numerous publications analyzing the causes and consequences of titanium dioxide crowding on the optical properties of white paint films, one notes some inconsistencies. First, a significant number of studies are inclined to describe “dependent” and “multiple” scattering of light as distinct phenomena. Second, the transition from independent to dependent light-scattering is often associated with an ill-defined “threshold” concentration. The aim of this study is to clarify the intricate connections between these two scattering regimes and in particular to show that for white paint films loaded with rutile titanium dioxide pigments, “dependent” light scattering is merely a particular manifestation of multiple scattering processes. We also clarify that the transition from independent to dependent scattering is a continuous process that cannot be formally related to a specific threshold in the pigment volume concentration. Finally, we propose a simple method based on the dependent scattering amplitude to assist paint formulators facing the task of improving the hiding power of a white paint either by increasing the quantity of pigments or by improving their spatial state of dispersion.     

Polymorphism of cocoa butter

Largely by x-ray diffraction six crystalline states, I–VI, in order of increasing melting point, have been identified for cocoa butter. Of these states II, IV, V and VI are pure and identifiable with previously (or presently) identified polymorphs of 2-oleoylpalmitoyl stearin (POS), namelyα-2,β′-2,β-3 (“V”) andβ-3 (“VI”); V and VI representing distinct but very closely related crystalline structures. State I is a definite but fleeting and not readily characterized subα state and may be a phase mixture, as state III may be also. Melting points, heats of fusion and dilatometric data are reported for all states to the extent that their stability permits. The normal state of cocoa butter in chocolate is apparently V, certainlyβ-3. While it is true that “bloom” has not been observed for pure V nor observed to exist in the absence of VI, it is premature to say that VI is specifically the phase of chocolate “bloom”.     

Formation of microstructure in bauxite ceramics

The effect of TiO₂ additives on the formation of the microstructure of bauxite ceramics is considered. It is shown that the thialite phase formed in the roasting process “cleans” the corundum phase and the glass phase from impurities. The thialite grains reinforce the corundum matrix, hamper the growth of corundum grains in roasting, and improve the resistance of the material to crack propagation when it fractures. Playing the role of bridges connecting the “banks” of a crack, thialite grains enhance the crack resistance of the material. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 3, pp. 2–6, March, 2000.     

Surface functionalization and biomolecule immobilization using plasma-generated free radicals on polypropylene

In this study are presented evidences for the functionalization of polypropylene surfaces accomplished in a sequential process: argon- or oxygen-plasma enhanced generation of free radical sites on polypropylene surfaces was followed by “in situ” gas phase derivatization in the absence of plasma using ethylene diamine, or propylene diamine; and an “in situ”, gas phase derivatization using oxallyl chloride or “ex situ” derivatization in the presence of glutaraldehyde. The free radicals’ presence on the plasma-exposed polypropylene surfaces was confirmed using “in situ” sulfur dioxide or nitric oxide labeling techniques. It was shown that the free radical sites readily react under “in situ” conditions with the stable chain-precursor components and generate the desired spacer-chain molecules revealed by ESCA analysis. Functionalized polypropylene substrates were used for immobilization of α-chymotrypsin in the presence of spacer-chain molecules. The activity of the immobilized α-chymotrypsin was found to be comparable to the activity of the free enzyme when the spacer molecules have been used.     

Biokinetics of dietaryRRR-α-tocopherol in the male guinea pig at three dietary levels of vitamin C and two levels of vitamin E. Evidence that vitamin C does not “spare” vitamin Ein vivo

The net rates of uptake of “new” and loss of “old”2R,4′ R,8′ R-α-tocopherol (RRR-α-TOH, which is natural vitamin E) have been measured in the blood and in nine tissues of male guinea pigs over an eight week period by feeding diets containing deuterium-labelled α-tocopheryl acetate (d ₆-RRR-α-TOAc). There was an initial two week “lead-in” period during which 24 animals [the “high” vitamin E (HE) group] received diets containing 36 mg of unlabelled (d ₀)RRR-α-TOAc and 250 mg of ascorbic acid per kg diet, while another 24 animals [the “low” vitamin E (LE) group] received diets containing 5 mgd ₀-RRR-α-TOAc and 250 mg ascorbic acid per kg diet. The HE group was then tivided into three equal subgroups, which were fed diets containing 36 mgd ₆-RRR-α-TOAc and 5000 mg [the “high” vitamin C (HEHC) subgroup], 250 mg [the “normal” vitamin C (HENC) subgroup] and 50 mg [the “low” vitamin C (HELC) subgroup] ascorbic acid per kg diet. One animal from each group was sacrificed each week and the blood and tissues were analyzed ford ₀- andd ₆-RRR-α-TOH by gas chromatography-mass spectrometry. The LE group was similarly divided into three equal subgroups with animals receiving diets containing 5 mgd ₆-RRR-α-TOAc and 5,000 mg (LEHC), 250 mg (LENC) and 50 mg (LELC) ascorbic acid per kg diet with a similar protocol being followed for sacrifice and analyses. In the HE group the totald ₀-+d ₆-)RRR-α-TOH concentrations in blood and tissues remained essentially constant over the eight week experiment, whereas in the LE group the totalRRR-α-TOH concentrations declined noticeably (except in the brain, an organ with a particularly slow turnover of vitamin E). There were no significant differences in the concentrations of “old”d ₀-RRR-α-TOH nor in the concentrations of “new”d ₆-RRR-α-TOH found in any tissue at a particular time between the HEHC, HENC and HELC subgroups, nor between the LEHC, LENC and LELC subgroups. We conclude that the long-postulated “spring” action of vitamin C on vitamin E, which is well documentedin vitro, is of negligible importancein vivo in guinea pigs that are not oxidatively stressed in comparison with the normal metabolic processes which consume vitamin E (e.g., by oxidizing it irreversibly) or elminate it from the body. This is true both for guinea pigs with an adequate, well-maintained vitamin E status and for guinea pigs which are receiving insufficient vitamin E to maintain their body stores. The biokinetics of vitamin E uptake and loss in the HE guinea pigs are compared with analogous data for rats reported previously (Lipids 22, 163–172, 1987). For most guinea pig tissues the uptake of vitamin E under “steadystate” conditions was faster than for the comparable rat tissues. However, the brain was an exception with the turnover of vitamin E occurring at only one-third of the rate for the rat. NRCC Publication No. 30775.     

Buffered electrochemical polishing of niobium

The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a “damaged” surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor at high surface magnetic field, a phenomenon referred to as “Q-drop”. In some cases, the Q-drop can be significantly reduced by a low-temperature (~120 °C) “in situ” baking of the cavity. As part of the effort to understand this phenomenon, the effect of introducing a polarization potential during BCP, creating a process which is between the standard BCP and EP, was investigated. The focus of this contribution is on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, and electrochemical impedance. In particular, it is shown that the anodic potential of Nb during BCP has a plateau region in the polarization curve and the impedance diagrams on the plateau can be described with a “surface charge” model found in the literature. By applying an anodic potential to Nb, a lower etching rate and better the surface finish than by standard BCP process have been obtained.     

Efficiency of a new method for making ceramic articles with a fused-drop pattern

A new method for making ceramic articles with a fused-drop pattern is offered. The technological process of producing facing tiles with a “lunar surface” pattern created by fused drops is considered. The technological process is simplified, and the production cost of the tiles reduced. Translated from Steklo i Keramika, No. 4, pp. 28 – 29, April, 2000.