Single-photon Transistors Based on the Interaction of an Emitter and Surface Plasmons

A symmetrical approach is suggested (Chang DE et al. Nat Phys 3:807, 2007) to realize a single-photon transistor, where the presence (or absence) of a single incident photon in a ‘gate’ field is sufficient to allow (prevent) the propagation of a subsequent ‘signal’ photon along the nanowire, on condition that the ‘gate’ field is symmetrically incident from both sides of an emitter simultaneously. We present a scheme for single-photon transistors based on the strong emitter-surface-plasmon interaction. In this scheme, coherent absorption of an incoming ‘gate’ photon incident along a nanotip by an emitter located near the tip of the nanotip results in a state flip in the emitter, which controls the subsequent propagation of a ‘signal’ photon in a nanowire perpendicular to the axis of the nanotip.     

Effect of female and male genotypes and environment on wax composition in jojoba

The objective of this study was to determine the effects of genotype and environment on wax composition in jojoba seed, and thus be able to control it. Production of waxes with different compositions—and hence changed wax properties such as viscosity, boiling point, and thermal stability—may be of importance for future requirements of the jojoba industry. Wax composition of 23 female clones was determined for two growing seasons. The ratio of FA elongated to the sum of those reduced and esterified differed among genotypes, resulting in differences in the percentage of wax esters longer than 40 or 42 carbons. The clones ‘Yarden,’ ‘Gvati’, ‘Hazerim,’ ‘BGU,’ and ‘Negev’ had higher percentages of long-chain wax moieties than the clones ‘879–154’, ‘MS 55–4’, and ‘Forti.’ The contribution of the male genotype to wax composition was tested by pollinating bagged female flowers of four female clones with pollen from three male plants. Both male and female genotypes additively influenced the composition of the wax esters. Wax composition varied between growing seasons and locations, but differences between genotypes were consistent. Salinity of the irrigation water did affect wax composition in some clones. Under high salinity, the salt-sensitive clone ‘64’ produced a smaller percentage of long-chain wax esters, whereas in clone ‘Q-106’ wax composition did not change. In clone ‘874–154’ the chain lengths of the wax moieties in the seeds increased under medium salinity. We conclude that jojoba wax composition is influenced by both female and male genotypes and by environmental factors such as climate and salinity.     

Study on the mechanism of hindered sedimentation by ‘unified theory on solid-liquid separation’

The entire procedure of hindered sedimentation has been calculated by the introduction of new boundary conditions to the ‘unified theory on solid-liquid separation.’ During this study, the hindered sedimentation was defined as ‘a process of sedimentation with transmission of the gravitational force between the particles due to contact.’ The lower concentration limit, on which the ‘unified theory on solid-liquid separation’ is based, could not be applied. To understand the mechanism of hindered sedimentation, variations in the porosity during sedimentation were calculated by using our theory.     

The implications of future EC food contact legislation for lacquer coated food and beverage cans

Conclusions  The European Commission’s programme of work to harmonize the laws and regulations on food contact materials and articles is expected to produce a specific Directive on ‘polymeric coatings’ within the next few years. The ‘regulations’ in this ‘coatings’ Directive will cover food and beverage cans with internal lacquer coatings. The ‘coatings’ Directive will probably follow the same format as that of the ‘plastics’ Directive 90/128/EEC, with permitted lists of substances, some with restrictions mainly in the form of specific migration limits, and an overall migration limit. Experience in performing migration tests on plastics for compliance with the limits and restrictions in Directive 90/128/EEC has identified various problems and difficulties. Similar problems and difficulties have been found to occur when migration testing lacquer coated food and beverage cans, and their are some additional problems. Project work investigating these problems and difficulties have resulted in changes to the migration test procedures and protocols, which should ensure that in future migration testing on food and beverage cans reliable and valid test results are obtained.     

Tocopherol Content and Profile of Soybean: Genotypic Variability and Correlation Studies

Plant seed oils, including soybean seed oil, represent the major source of naturally derived tocopherols, the antioxidant molecules that act as free radical quenchers preventing lipid peroxidation in biological systems and vegetable oil products. All four isomers of tocopherols, i.e. α, β, γ, δ tocopherols that exist in nature are found in soybean seeds. The biological activity and the contribution of these isomers in improving the oxidative stability of vegetable oil are in reverse order. Because of the nutritive value and the importance for oil stability, enhancement of tocopherol content, through breeding programs, in soybean seeds has become a new and an important objective. Genotypic variability, which is the basis of every breeding program, is scarcely reported for tocopherol content and profile in soybean seeds. In the present investigation, the tocopherol content and profile in seed samples of 66 genotypes of Indian soybean were determined. The ratios observed between the lowest and the highest values for α, β, γ, δ, total tocopherol content were 1:13.6, 1:10.4, 1:7.5, 1:9.1, 1:7.9, respectively. The mean contents for α, β, γ, δ and total tocopherols were 269, 40, 855, 241 and 1,405 μg/g of oil, respectively. Total tocopherol content was the highest in ‘Co Soya2’ followed by ‘Ankur’. Concentration of α-tocopherol was the highest (27%) in ‘Ankur’ followed by ‘MACS124’ (26%) whereas gamma tocopherol concentration was the highest (69%) in ‘VLS1’ and ‘PK327’ followed by ‘MACS13’ (67%). In view of the fact that levels of unsaturated fatty acids, apart from tocopherols, also determine the oxidative stability of vegetable oils, the relationship of four isomers of tocopherols with each other as well as with different unsaturated fatty acids and oil content was also investigated in the present study. All the four isomers of tocopherols exhibited highly significant correlations with each other (p < 0.001) whereas γ-tocopherol and total tocopherol content showed a significant relationship with linoleic acid (p < 0.05).     

An alternative approach to the evaluation of the slow crack growth resistance of polyethylene resins used for water pipe extrusion

High-density polyethylene (HDPE) pipes have been largely employed in water and gas distribution systems. In spite of offering significative advantages over other materials, HDPE pipes suffer from premature failures due to creep fracture. The current industrial criterium for design and sizing of HDPE pipes is discussed. The concept of ‘regression curve,’ i.e. of a time-to-failure criterium based in long-term-hydrostatic strength (LTHS) tests, is criticised and concluded to be unsatisfactory for this purpose. An alternative approach is suggested, which is based on shorter-term tests. This is illustrated by testing five HDPE resins designed for pipe extrusion and comparing with their standard ‘regression curves’. The obtained results are consistent with the ‘regression curve’-based analysis, justifying the use of the alternative approach in the industry.     

The effects of original and randomized rapeseed oils containing high or very low levels of erucic acid on cardiac lipids and myocardial lesions in rats

The nutritional status of the very lowerucate rapeseed oil,Brassica napus var. ‘Tower,’ was compared with that of the high-erucate oil,Brassica napus var. ‘Target’, as well as with corn oil. The effect of randomization on the nutritional qualities of rapeseed oil was investigated as well. The feeding of diets containing the original and randomized ‘Tower” oil or the original ‘Target’ oil, at the 20% level by weight, gave growth rates which were not significantly different from that for corn oil. However, the randomized ‘Target’ oil gave growth rates which were significantly less than all other groups. The growth results could not be explained simply on the basis of food consumption. The level of triglycerides in the hearts of rats fed the very low-erucate oils was not significantly different from the corn oil group. Triglyceride concentrations in the hearts of animals given the high-erucate oils were 7–12 times greater than all other groups. The level of total fatty acids in tissue phospholipids was the same regardless of dietary treatment. Fatty acid compositions of the tissue lipids were the same in animals fed either the original or randomized rapeseed oils. A much higher incidence of focal myocardial necrosis was found in animals receiving high-erucate rapeseed oil relative to animals given the corn oil. The incidence in rats fed diets containing very low-erucate rapeseed oil was intermediate between these latter two extremes.     

Phase behavior of gelatin in the presence of pectin in water-acid medium

Summary Phase separation of alkaline gelatin in water-acid solutions in the presence of low etherified pectin (ED 38%) were investigated. The effects of the pectin weight fraction in pectin/gelatin mixture (q_o) as well as two conditions of complex formation, namely, mixing of the binary biopolymer-solvent systems at pH 3.5 (‘mixing conditions’), or preparation of the ternary gelatin-pectin-water systems at pH 7.5 and their subsequent acidification up to pH 3.5 (‘titration conditions’), on phase equilibrium and macrostructure of the concentrated complex phase were established using phase analysis, and optical microscopy. At q_o<0.5 the aggregative phase separation was observed in both conditions of complex formation leading to the almost complete concentration of both biopolymers in the bottom phase at q_o=0.3 (‘mixing conditions’) and at q_o=0.5 (‘titration conditions’). At q_o>0.5 unusual three phase separation took place in the ‘mixing conditions’, leading to formation of supernatant (phase 1), complex coacervate (phase 2) and concentrated pectin solution (phase 3). Possible mechanism of such phenomenon was discussed in term of segregative and aggregative phase separations.     

Simulation studies of nearest-neighbor distribution functions and related structural properties for hard-sphere systems

Molecular dynamics simulations have been carried out to investigate nearest-neighbor distribution functions and closely related quantities for the system of hard-spheres. The nearest-neighbor distribution function and the exclusion probability function were computed to examine the density dependence on the structural ‘void’ and ‘particle’ properties. Simulation results were used to access the applicabilities of various theoretical predictions based on the scaled-particle theory, the Percus-Yevick equation, and the Carnahan-Starling approximation. For lower density systems the three different approximations give the nearest-neighbor distribution functions which are very close to one another and also to the resulting simulation data. Among those theoretical predictions, the Carnahan-Starling approximation gives remarkably good agreement with the simulation data even for higher density systems. Also calculated is the nth moment of the nearest-neighbor distribution functions, in which the corresponding length scale is directly related to the measurement of the characteristic pore-size distribution.     

Frederic Stanley Kipping—Pioneer in Silicon Chemistry: His Life &; Legacy

Frederic Stanley Kipping FRS is regarded as one of the founding fathers of silicon chemistry. In 57 research papers published between 1899 and 1944 he reported the first use of Grignard reagents to make alkylsilanes and arylsilanes and the prepartion of silicone oligomers and polymers. He coined the term ‘silicone’ in relation to these materials in 1904. His research formed the foundation for James Franklyn Hyde’s development of the first silicon based insulation materials at Corning Glass Works and then Dow Corning Corp., as well as inspiring Eugene G. Rochow’s work at General Electric Company in the development of the ‘direct method’ of silicone synthesis using silicon hydrides. Kipping was the first Sir Jesse Boot Professor of Chemistry at Nottingham University College and was married to Lily Holland whose sisters, Mina and Kathleen were married to two other prominent early 20th century British Chemists, William H. Perkin Jr. FRS and Arthur Lapworth FRS. This paper provides an insight into Professor Kipping’s life, personality and career.     

Enantio-differentiating hydrogenation of methyl acetoacetate over modified Raney nickel catalysts prepared by two-step modifications

Two-step modifications of the Raney nickel were examined for the enantio-differentiating hydrogenation of methyl acetoacetate. Among the two-step modifications attempted in this study, the combination of ‘pre-modification with disodium tartrate and NaBr in water’ and ‘in-situ modification with tartaric acid’ resulted in the highest optical yield (84%). This modification process is a greener process than the conventional one carried out under weakly acidic conditions, because this process generated almost no Ni²⁺ ions. The pre-modification with the tartrate and NaBr preferentially eliminated Al³⁺ from the Raney nickel surface.     

Controlled Polymerization of N-trimethylsilyl Methacrylamide: A New Polymethacrylamide Precursor

N-trimethylsilyl methacrylamide (TMS-MAm), a new methacrylamide precursor, has been synthesized and characterized. 2,2’-Azoisobutyronitrile (AIBN) initiated radical polymerization of TMS-MAm was carried out in N,N-dimethylformamide (DMF) and toluene using the triazolinyl radical (T•) as additive. The mechanism of ‘‘self regulation’’ that triazolinyl offers is found to work well in the solution polymerization process over a reasonably wide range of temperature up to 79% conversion. Molecular weight distributions below or close to the theoretical limit of 1.5 and high degree of end functionalization could be achieved. The polymers obtained could be easily converted to polymethacrylamide under mild conditions.     

Isolation and Identification of Host Cues from Mango, <Emphasis Type="Italic">Mangifera indica</Emphasis>, That Attract Gravid Female Oriental Fruit fly, <Emphasis Type="Italic">Bactrocera dorsalis</Emphasis>

The oriental fruit fly, Bactrocera dorsalis, is an economically damaging, polyphagous pest of fruit crops in South-East Asia and Hawaii, and a quarantine pest in other parts of the world. The objective of our study was to identify new attractants for B. dorsalis from overripe mango fruits. Headspace samples of volatiles were collected from two cultivars of mango, ‘Alphonso’ and ‘Chausa’, and a strong positive behavioral response was observed when female B. dorsalis were exposed to these volatiles in olfactometer bioassays. Coupled GC-EAG with female B. dorsalis revealed 7 compounds from ‘Alphonso’ headspace and 15 compounds from ‘Chausa’ headspace that elicited an EAG response. The EAG-active compounds, from ‘Alphonso’, were identified, using GC-MS, as heptane, myrcene, (Z)-ocimene, (E)-ocimene, allo-ocimene, (Z)-myroxide, and γ-octalactone, with the two ocimene isomers being the dominant compounds. The EAG-active compounds from ‘Chausa’ were 3-hydroxy-2-butanone, 3-methyl-1-butanol, ethyl butanoate, ethyl methacrylate, ethyl crotonate, ethyl tiglate, 1-octen-3-ol, ethyl hexanoate, 3-carene, p-cymene, ethyl sorbate, α-terpinolene, phenyl ethyl alcohol, ethyl octanoate, and benzothiazole. Individual compounds were significantly attractive when a standard dose (1 μg on filter paper) was tested in the olfactometer. Furthermore, synthetic blends with the same concentration and ratio of compounds as in the natural headspace samples were highly attractive (P < 0.001), and in a choice test, fruit flies did not show any preference for the natural samples over the synthetic blends. Results are discussed in relation to developing a lure for female B. dorsalis to bait traps with.     

Nitrous oxide emissions from fertilized and unfertilized grasslands on peat soil

Emissions of nitrous oxide (N₂O) from managed and grazed grasslands on peat soils are amongst the highest emissions in the world per unit of surface of agriculturally managed soil. According to the IPCC methodology, the direct N₂O emissions from managed organic soils is the sum of N₂O emissions derived from N input, including fertilizers, urine and dung of grazing cattle, and a constant ‘background’ N₂O emission from decomposition of organic matter that depends on agro-climatic zone. In this paper we questioned the constant nature of this background emission from peat soils by monitoring N₂O emissions, groundwater levels, N inputs and soil NO₃ ⁻–N contents from 4 grazed and fertilized grassland fields on managed organic peat soil. Two fields had a relatively low groundwater level (‘dry’ fields) and two fields had a relatively high groundwater level (‘wet’ fields). To measure the background N₂O emission, unfertilized sub-plots were installed in each field. Measurements were performed monthly and after selected management events for 2 years (2008–2009). On the managed fields average cumulative emission equaled 21 ± 2 kg N ha⁻¹y⁻¹ for the ‘dry’ fields and 14 ± 3 kg N ha⁻¹y⁻¹ for the ‘wet’ fields. On the unfertilized sub-plots emissions equaled 4 ± 0.6 kg N ha⁻¹y⁻¹ for the ‘dry’ fields and 1 ± 0.7 kg N ha⁻¹y⁻¹ for the ‘wet’ fields, which is below the currently used estimates. Background emissions were closely correlated with groundwater level (R ² = 0.73) and accounted for approximately 22% of the cumulative N₂O emission for the dry fields and for approximately 10% of the cumulative N₂O emissions from the wet fields. The results of this study demonstrate that the accuracy of estimating direct N₂O emissions from peat soils can be improved by approximately 20% by applying a background emission of N₂O that depends on annual average groundwater level rather than applying a constant value.     

Synthesis of deuterobutadiene-butadiene AB2 and AB3 miktoarm star copolymers

The synthesis of well-defined, monodisperse AB₂ and AB₃ miktoarm star copolymers, in which A is polydeuterobutadiene and B is polybutadiene, is described. The synthetic procedure involved reacting living polydeuterobutadiene with a large excess of either methyltrichlorosilane or tetrachlorosilane to yield a ‘one-arm star’. SEC traces of this ‘one-arm star’ are indistinguishable from that of the uncoupled polydeuterobutadiene indicating no further coupling to form multi-arm stars occurs. Unreacted chlorosilane was removed by distillation and the introduction of an excess of living polybutadiene generates the star. The star polymer was isolated from the precursor polybutadiene by fractionation. Received: 27 April 1998/Revised version: 15 June 1998/Accepted: 16 June 1998     

CO Oxidation Studied Using ‘Fast’ XPS and a Molecular Beam Reactor

We have combined the use of a molecular beam reactor with ‘fast’ XPS in order to correlate changes in the rate of CO oxidation with the coverages of the adsorbates and intermediates on the surface. In the reactor CO oxidation exhibits an isothermal ‘light-off’ phenomenon in which the rate autocatalytically increases with time. This is due to the desorption of CO which releases extra sites for O₂ dissociation which, in turn, removes more CO, and hence the self-acceleration. In effect the reaction can be written as 2CO_a + O_2g + 2S → 2CO_2g + 4S, the acceleration coming from the release of extra adsorption sites, S, which are involved in the reaction itself. ‘Fast XPS’, carried out in-situ during the course of the reaction, shows domination of the surface by CO_a below 390 K and by O_a above that temperature, with a rapid change in surface coverage over a very narrow temperature window. This is an advance on earlier work, since our measurements are made in a single, continuous experiment, due to the high brightness of the synchrotron source. This also allows the data to be obtained at high energy resolution, in the presence of both gases, and without contamination. On high surface area samples this acceleration is further reinforced due to a rapid temperature increase because of the highly exothermic nature of the overall reaction.     

Flooding and floating in latex paint

Flooding and floating are problems in many paint applications. If pigment concentration is uniform on the surface but not through the thickness of the film, one refers to ‘flooding’ (horizontal separation). If, however, concentration differences are visible across the surface of the paint film, one refers to ‘floating’ (vertical separation). In this article, the influence of pigment, filler, additives, and processing conditions on the flooding and floating of colored latex paint were investigated. It was discovered that too broad a distribution of pigment and filler particle size can lead to flooding and floating. Different levels of pigment (TiO₂) or filler (kaolin) loading cause diverse degrees of flooding and floating. Waterborne coatings that do not exhibit flooding or floating may show these conditions when diluted. Using dispersants or thickeners with hydrophobic constituents, increasing viscosity, reducing surface tension, etc., all help to prevent or reduce flooding and floating. Comparison tests revealed little influence of processing conditions on flooding or floating.     

Consideration of the methods for evaluating the Cr(VI)-removing capacity of biomaterial

Over the last few decades, many researchers have tested various biomaterials for the removal of toxic Cr(VI) from aquatic systems. It is now widely accepted that the mechanism of Cr(VI) biosorption is not ‘anionic adsorption’ but ‘adsorption-coupled reduction’. Unfortunately, however, many researchers have still used common equilibrium isotherm models, such as Langmuir and Freundlich ones, based on ‘anionic adsorption’ mechanism in order to evaluate the Cr(VI)-removing capacity of biomaterial tested. In this study, a fermentation waste of Corynebacterium glutamicum, capable of removing Cr(VI) efficiently, was used as a model biomaterial to show why equilibrium isotherm models cannot be used to evaluate the Cr(VI)-removing capacity of biomaterial. Meanwhile, some alternative methods considering the mechanism of Cr(VI) biosorption were suggested; the maximum Cr(VI)-removing capacity of the biomaterial could be evaluated by a Cr(VI)-biosorption experiment under biomaterial-limited condition as well as by a simplified kinetic model based on the reduction mechanism of Cr(VI).     

Effects of Cyanogenic Plants on Fitness in Two Host Strains of the Fall Armyworm (<Emphasis Type="Italic">Spodoptera frugiperda</Emphasis>)

The generalist moth, Spodoptera frugiperda (J. E. Smith) consists of two genetic subgroups (host strains) that differ in their distribution among host plant species. The corn strain prefers crop plants such as corn, sorghum, and cotton, while the rice strain is found in small grasses such as Cynodon spp. and rice. Little is known about the physiological factors that drive this host preference. Here, we report a feeding study with natural host plants and an artificial diet containing cyanide. We found that corn, two Cynodon spp. (bermudagrass C. dactylon (L.) Persoon, ‘NuMex Sahara’, and stargrass C. nlemfuensis var. nlemfuensis Vanderyst, ‘Florona’), and a hybrid between bermudagrass and stargrass, ‘Tifton 85’, exhibited differences in the concentration of the cyanogenic precursors or cyanogenic potential (HCNp) and the release of hydrogen cyanide per unit time or cyanogenic capacity (HCNc). Corn plants released low levels of hydrogen cyanide, while stargrass had greater HCNp/HCNc than bermudagrass and ‘Tifton 85’. Feeding studies showed that corn strain larvae experienced higher mortality than the rice strain when fed stargrass or artificial diet supplemented with cyanide. Also, corn strain larvae excreted higher levels of cyanogenic compounds than the rice strain when fed Cynodon spp. These differences in excretion suggest potential disparities in cyanide metabolism between the two strains. We hypothesize that differences in the susceptibility to cyanide levels in various host plants could play a role in driving strain divergence and what appears to be the incipient speciation of this moth.     

Effect of interaction of operation parameters on elutriation behavior in a vortexing fluidized bed

A systematic investigation on elutriation behavior conducted in a vortexing fluidized bed (VFB) cold model is studied. The effects of various parameters on the elutriation are investigated from the data obtained by using ‘response surface methodology’ (RSM) to determine the relationship between elutriation rate and operating conditions. The results show that all the interactions among primary air flow rate, secondary air flow rate, fine particle size, secondary air inlet diameter, and imaginary circle diameter had significant influences on elutriation behavior in the VFB. The modified regression models of the ‘specific elutriation rate constant’ (K*) were also submitted in this study.