bluuebunny/crossref_metadata_2025 huggingface dataset:
Mixed micelles of some metal dodecyl sulfates and triton X‐100 in aqueous media
Authors: Gandhi Hetal , Modi Snehal , Jain Nirmesh , Bahadur Pratap
Published: November 2006

Tensiometric studies on several binary surfactant mixtures containing anionic surfactants, viz., metal (lithium, sodium, potassium, copper, cobalt, and magnesium) dodecyl sulfates and a nonionic surfactant (Triton X‐100) in water at different mole fractions (0–1) provide critical micelle concentration (CMC) values. The composition of mixed micelles and the interaction parameter, β, evaluated from the CMC data for different systems using Rubingh's theory, are discussed. Marked interaction is observed with monovalent dodecyl sulfates. The influence of counter‐ion valence on the formation of mixed micelles was investigated for anionic‐nonionic systems, and results indicated that mixed systems with bivalent counter‐ions in metal dodecyl sulfate resembled nonionic‐nonionic systems where weak/negligible interaction has been reported. Salt addition revealed the weakening of interaction in the mixed systems, which is attributed to the head group charge neutralization and the dehydration of the ethylene oxide units of the nonionic surfactants. A few cloud point and viscosity data are also reported.
Deinking of water‐based ink printing from plastic film using nonionic surfactants
Authors: Gecol Hatice , Scamehorn John F. , Christian Sherril D. , Grady Brian P. , Riddell Fred E.
Published: November 2006

When plastic film packaging is processed for reuse, residual ink colors the polymer and makes the polymer less stiff, weaker, and denser than the original material. These problems can be avoided if the printing is removed from the plastic film surface. In this study, a commercial polyethylene film with water‐based ink printing was deinked (the ink was removed) using nonionic surfactants under a variety of conditions, and the effect of some parameters related to the deinking process were quantified and optimized. Nonylphenol polyethoxylate, ethoxylated alcohol at a pH of 10, and ethoxylated amine at either acidic, neutral, or basic pH level were identified to be effective at deinking. The hydrophiliclipophilic balance (HLB) value and the cloud point are useful parameters for characterizing the effectiveness of nonionic surfactants. For optimal deinking, the HLB of the nonionic surfactants should be as small as possible or the cloud point as low as possible without the deinking temperature substantially exceeding the cloud point. Information related to scaleup of the process was also developed. Soaking plastic film in surfactant solution prior to mechanical agitation significantly decreased the needed agitation time to achieve a given level of deinking. Deinking decreases as the plastic/solution ratio (consistency) increases, and cutting plastic film into smaller pieces improves the deinking at moderate consistency. Increasing agitation speed also enhances the deinking. Experiments performed with pilot‐sized paper deinking apparatuses demonstrated that deinking of plastic film using surfactants is technically feasible.
Effect of additives on the adsorption of sodium bis(2‐ethyl hexyl sulfosuccinate) at the air‐water interface studied by equilibrium and dynamic surface tension measurements
Authors: Pedrosa Ana Belén , Briz José I. , Velázquez M. Mercedes
Published: November 2006

Using equilibrium and dynamic surface tension measurements, we have studied the effect of the addition of poly(sodium 4‐styrenesulfonate) (PSS), sodium chloride, and 1,4,7,10,13,16‐hexaoxyacyclooctadecane (18‐crown‐6) on the surface properties of sodium bis(2‐ethyl hexyl sulfosuccinate) (AOT). The addition of PSS or NaCl weakly increases the maximum packing of AOT, whereas the presence of 18‐crown‐6 slightly decreases the maximum surface coverage. The surfactant adsorption kinetics on the interface is a diffusion‐controlled process. The two asymptotic solutions at long times and at short times to the classic Ward Tordai equation were used to fit dynamic results. At long times there is evidence of the existence of an electrostatic barrier at high surfactant concentration when using pure AOT and AOT mixed with PSS. In binary mixtures of AOT with sodium chloride or 18‐crown‐6, the electrostatic barrier is not observed over the surfactant concentration range studied.
Dishwashing performance of mixed palm stearin sulfonated methyl esters—Nonylphenol ethoxylate alcohol
Authors: Lim Wen Huei , Salmiah Ahmad
Published: November 2006

The dishwashing performance of sodium salts of α‐sulfonated methyl esters derived from palm stearin (α‐SMEPS) and nonylphenol ethoxylate alcohol (NPEO) in mixed micelle systems was evaluated as a function of weight ratio at different water hardness values (5.12, 51.2, and 512.0 ppm CaCO3) and temperatures (20, 30, and 45°C). Manipulating several parameters, such as weight ratios in α‐SMEPS and NPEO mixtures, washing temperature, and water hardness, can enhance detergency performance. In comparison, detergency efficiency of the mixtures increased as follows: α‐SMEPS/NPEO 400<α‐SMEPS/NPEO 120<α‐SMEPS/NPEO 95.
Quaternary salts as solubilization site modifiers of organic compounds in anionic micellar solutions
Authors: Kumar Sanjeev , Sharma Daksha , Kabir‐ud‐Din
Published: November 2006

The effects of the addition of different salts (quaternary bromides or NaBr) on the viscosity (measured under Newtonian flow conditions) of sodium dodecylbenzenesulfonate (SDBS) micellar solutions were studied at 30°C. Tetra‐n‐butylammonium bromide (Bu4NBr) was found most effective in increasing the viscosity (due to possible change in micellar shape) at fairly low SDBS concentration (50 mM). The effectiveness of Bu4NBr may be due to the presence of four butyl chains and to the positive charge on its counterion (Bu4N+) which can subsequently interact with anionic SDBS micelles electrostatically as well as hydrophobically; owing to solubility/steric problems, other salts were ineffective. Organic additives such as cyclohexylamine and cyclohexanol had marginal effects on viscosity when added to 50 mM SDBS solutions having no Bu4NBr. However, in the presence of Bu4NBr, the effect was dependent on salt concentration and the nature of the additive. The overall effect is discussed on the basis of change in the solubilization site of the additive in the presence of Bu4NBr.
Lauryl alcohol and amine oxide as foam stabilizers in the presence of hardness and oily soil
Authors: Zhang Hui , Miller Clarence A. , Garrett Peter R. , Raney Kirk H.
Published: November 2006

The effects of two potential foam boosters, n‐dodecanol (or lauryl alcohol: LA) and tetradecyldimethylamine oxide (C14DMAO), were investigated for two situations in which foam made from a 0.01 wt% solution of a common alkylethoxy sulfate surfactant was highly unstable in the presence of oil drops consisting of an n‐hexadecane/oleic acid mixture. In one case in which dissolved CaCl2 was present at alkaline pH, insoluble calcium oleate particles formed in situ and facilitated foam breakage. In the other, a much higher concentration of calcium was present at neutral pH, and drops of a microemulsion phase formed but no calcium oleate. In both cases, 0.005 wt% LA reduced the entry coefficient, E, of the oil to the air‐water surface sufficiently to prevent drop entry and stabilized the foam. In contrast, 0.005 wt% C14DMAO caused smaller reductions in E and was ineffective as a foam booster. LA was more effective because it was able to form a more compact monolayer with the surfactant than C14DMAO at the air‐water surface, which led to lower surface tensions and hence lower values of E.
Enzymatic preparation of polyethylene glycol esters of castor oil fatty acids and their surface‐active properties
Authors: Ghosh M. , Bhattacharyya D. K.
Published: November 2006

This study concerns the preparation and evaluation of nonionic surfactants prepared from polyethylene glycol (PEG) esters of castor oil fatty acid, a source of hydroxy fatty acid. A lipase‐catalyzed esterification reaction has been employed to prepare PEG esters of hydroxy acid to overcome problems associated with chemical processes. Castor oil fatty acid (85% ricinoleic acid) was mixed with PEG of different molecular weight. Rhizomucor miehei lipase was added as catalyst (10% level) and the reaction was continued at 60°C under 2 mm Hg pressure for 360 min. Conversion of PEG to esters was in the range of 86–94%, depending on the molecular size of PEG. The products were isolated and examined for surface activity by surface tension measurement. Surface tension values measured at 25°C were about 36–37 dynes/cm.
Newer synthetic approaches to surfactants, lipids, and related compounds based on C‐3 building blocks: Recent advances related to fatty chemistry
Authors: Urata Kouichi , Takaishi Noatake
Published: November 2006

Many lipids derived from natural sources are based on the glycerin molecule. Synthetically alkyl glycidyl ether can be used as a C‐3 building block for lipid molecules as well as alkyl glyceryl ether. Several glycidyl and glyceryl ethers have been studied as C‐3 synthetic building blocks for lipids used in surfactants/emulsifiers, cosmetics, or toiletries. From an environmental viewpoint, several surfactants and detergents have been modified by using epichlorohydrin or glycerides as C‐3 building blocks to have higher performance or biodegradability. Recently, complex lipid molecules having special bioactivities have attracted attention among chemists. Glycidyl ether would be expected to be one of the synthetic building blocks for such complex lipids.
Low‐water laundering
Authors: Jacobsen Ronald L.
Published: November 2006

High‐efficiency clothes washers, or front‐loading tumbler washers, use much less water and energy for a complete wash cycle than agitator washers. Washing comparably sized loads in less water creates challenges for laundry detergents. This paper reviews federal government efforts to increase washer efficiency, operating dynamics of the tumbler vs. the current agitator washer, the impact on detergent formulation, and the current status of high‐efficiency washer adoption by U.S. consumers.
Plasma cholesteryl ester transfer protein and lipoprotein levels during treatment of growth hormone‐deficient adult humans
Authors: Carrilho Alexandre J. F. , Cunha‐Neto Malebranche B. , Nunes Valéria S. , Lottenberg Ana M. P. , Medina Wilson L. , Nakandakare Edna R. , Musolino Nina R. , Bronstein Marcello D. , Quintão Eder C. R.
Published: November 2006

The incidence of atherosclerosis is increased in growth hormone (GH) deficient‐individuals. Nonetheless, the antiatherogenic benefits of GH replacement therapy remain uncertain. In this study the effect of human recombinant growth hormone (hrGH) replacement therapy administered to GH‐deficient adults on the plasma cholesteryl ester transfer protein (CETP) concentration and activity was analyzed. These findings were related to changes in the concentrations of the plasma lipoproteins. The hrGH was administered for 12 mon to human GH‐deficient patients (n=13; 8 men, 5 women). During the study plasma lipoproteins were separated by ultracentrifugation, and plasma cholesterol esterification rate (CER), endogenous CETP activity, and CETP concentration were measured. GH replacement therapy transiently (at 3 mon) lowered plasma concentration of CETP and low density lipoprotein‐cholesterol (LDL‐C) and raised total triglycerides. Furthermore, hrGH permanently increased both the plasma lipoprotein(a) [Lp(a)] concentration, which is known as atherogenic, and the proportion of cholesteryl ester in the high density lipoprotein2 (HDL2) particles, which is potentially atheroprotective. The simultaneous decrease of the plasma CETP and LDL‐C concentrations elicited by hrGH indicated a close relationship between LDL metabolism and the regulation of the CETP gene expression. Endogenous CETP activity and the CER were not modified because these parameters are regulated in opposite ways by plasma levels of triglycerides; that is, CER increased and CETP decreased.
Effect of dietary restriction on age‐related increase of liver susceptibility to peroxidation in rats
Authors: Jeon Tae Il , Lim Beong Ou , Yu Byung Pal , Lim Yoongho , Jeon Eun Ja , Park Dong Ki
Published: November 2006

Dietary restriction (DR) increases life span and decreases age‐related diseases in experimental animals. It has received a great deal of attention in connection with the relationship between aging, nutrition, and oxidative stress because oxidative injury in several organ systems is a prominent feature in aging. We investigated the possibility that DR can protect vulnerable liver lipids against age‐related increases of peroxidation. Male Fischer 344 rats fed ad libitum (AL) or dietarily restricted (maintained on 60% of AL food intake) were killed by decapitation at 4 (young) or 12 mon (adult) of age. Phosphatidylcholine hydroperoxide (PCOOH) concentration of liver was determined using a chemiluminescent high‐performance liquid chromatographic method. Liver PCOOH increased with age in adult rats, but less of an increase of PCOOH was seen in DR rats, which is consistent with results on production of thiobarbituric acid‐reactive substances and oxygen‐derived free radicals. No significant differences were found in liver superoxide dismutase and catalase activity between AL and DR groups of young and adult rats. Liver triglyceride and cholesterol contents were lower in DR than AL rats at 12 mon. Fatty acid compositions of phosphatidylcholine and phosphatidylethanolamine indicated that the ratio of (20∶3n−6+20∶4n−6)/18∶2n−6, an index of linoleic acid (18∶2n−6) desaturation, was lower in DR than in AL rats. We concluded that DR suppresses age‐related oxidative damage in liver by modulating the amount of lipid as well as fatty acid composition.
Oleate acutely stimulates the secretion of triacylglycerol by cultured rat hepatocytes by accelerating the emptying of the secretory compartment
Authors: Zammit Victor A. , Lankester David L.
Published: November 2006

The acute effects of addition of oleate on the rate of triacylglycerol (TAG) secretion by cultured rat hepatocytes were studied by monitoring the use of endogenous (14C‐prelabeled) acyl moieties and exogenous (3H‐labeled) oleate for the synthesis of secreted TAG simultaneously. Inclusion of exogenous oleate in the medium stimulated the secretion of the endogenous 14C‐labeled acyl moieties by 55–100%. To find out whether the stimulation was due to increased endogenous TAG mobilization or an increased rate of processing of TAG within the endoplasmic reticulum (ER) secretory machinery, use was made of the inhibition of apolipoprotein B (apoB) synthesis (but not degradation) by Ca2+ mobilization from the ER. Inhibition of apoB synthesis stopped entry of acyl moieties (from endogenous and exogenous sources) into the secretory pathway. However, even when entry of acyl moieties into the secretory pathway was totally inhibited, exogenous oleate was still able to stimulate (twofold) the secretion [14C]TAG, indicating that oleate stimulates the emptying of prelabeled TAG from the secretory compartment at a point distal to apoB synthesis and nascent particle formation. These data indicate that exogenous oleate, besides providing additional acyl moieties for incorporation into secreted TAG, stimulates the secretion of endogenous TAG in a manner (i) that is independent of effects on apoB synthesis and/or degradation and (ii) that involves the enhanced processing of TAG resident within the ER secretory pathway.
Vinyl sulfide derivatives of truncated oxidosqualene as selective inhibitors of oxidosqualene and squalene‐hopene cyclases
Authors: Ceruti Maurizio , Balliano Gianni , Rocco Flavio , Milla Paola , Arpicco Silvia , Cattel Luigi , Viola Franca
Published: November 2006

Various vinyl sulfide and ketene dithioacetal derivatives of truncated 2,3‐oxidosqualene were developed. These compounds, having the reactive functions at positions C‐2, C‐15 and C‐19 of the squalene skeleton, were studied as inhibitors of pig liver and Saccharomyces cerevisiae oxidosqualene cyclases (OSC) (EC 5.4.99.7) and of Alicyclobacillus acidocaldarius squalene hopene cyclase (SHC) (EC 5.4.99.‐). They contain one or two sulfur atoms in α‐skeletal position to carbons considered to be cationic during enzymatic cyclization of the substrate and should strongly interact with enzyme nucleophiles of the active site. Most of the new compounds are inhibitors of the OSC and of SHC, with various degrees of selectivity. The methylthiovinyl derivative, having the reactive group at position 19, was the most potent and selective inhibitor of the series toward S. cerevisiae OSC, with a concentration inhibiting 50% of the activity of 50 nM, while toward the animal enzyme it was 20 times less potent. These results could offer new insight for the design of antifungal drugs.
Influence of temperature and high dietary linoleic acid content on esterification, elongation, and desaturation of PUFA in atlantic salmon hepatocytes
Authors: Ruyter B. , Røjø C. , Grisdale‐Helland B. , Rosenlund G. , Obach A. , Thomassen M. S.
Published: November 2006

The esterification, desaturation, and elongation of [1‐14C]18∶3n−3, [1‐14C]18∶2n−6, and [1‐14C]20∶5n−3 at 5 and at 12°C were studied using cultivated hepatocytes from Atlantic salmon. The salmon were fed diets, in which 0, 50, or 100% of the supplementary fish oil had been replaced by soybean oil, for 950 day‐degrees at 5 and 12°C. The endogenous percentage of 18∶2n−6 in hepatocyte lipids was 2% in cells from fish fed a diet with 100% of the supplemental lipid from fish oil, and it was slightly less than 25% in cells from fish fed the diet with 100% of the supplemental lipid from soybean oil. Furthermore, the percentages of 20∶3n−6 and 20∶4n−6 were significantly higher in hepatocytes from fish fed on soybean oil than they were in those of fish fed on fish oil. The percentages of 20∶5n−3 and 22∶6n−3, on the other hand, were lower. The endogenous levels of n−6 FA were not significantly correlated with the total amounts of radiolabeled FA esterified in hepatocyte lipids. The main radiolabeled products formed from 18∶2n−6 were 20∶2n−6 and 20∶3n−6. The level of the important eicosanoid precursor 20∶4n−6 was twice as high in hepatocyte phospholipids from fish fed the 100% soybean oil diet as it was in hepatocytes from fish fed the diet with 100% of supplemental lipid from fish oil. The main products formed from 18∶3n−3 were 20∶4n−3, 20∶5n−3, and 22∶6n−3. High levels of dietary 18∶2n−6 do allow, or even seem to increase, the production of 22∶6n−3 from 18∶3n−3 in hepatocytes. The main products formed from 20∶5n−3 were 22∶5n−3 and 22∶6n−3. The production of 22∶6n−3 from 20∶5n−3 was higher at 5°C than at 12°C. The percentage of 24∶5n−3 was higher at 5°C than it was at 12°C, as was the ratio of 24∶5 to 22∶5. These results suggest that the elongation rate of 22∶5n−3 to 24∶5n−3 is higher at the lower temperature.
Chemical and enzymatic transacylation of amide‐linked FA of buttermilk gangliosides
Authors: Beermann Christopher , Röhrig Anne‐Katrin , Boehm Günther
Published: November 2006

The goal of this work was to alter the composition of amide‐linked FA of bovine buttermilk gangliosides, particularly the disialoganglioside GD3, to adjust lipid sources to special food specifications and pharamacological or cosmetic applications. The chemical transacylation of amide‐linked FA of buttermilk gangliosides with free arachidic acid (20∶0) by a combination of basic hydrolysis and diethylphosphorylcyanide/triethylamine‐catalyzed reacylation was compared to an enzymatic sphingolipid ceramide N‐deacylase (EC 3.5.1.23)‐catalyzed FA exchange by GC analysis and nano electrospray ionization‐MS. The buttermilk predominantly contained the disialoganlioside GD3 and the monosialoganglioside GM3. The heterogeneity of FA that are incorporated into gangliosides, mainly palmitic acid (29.4 wt%), stearic acid (16.9 wt%), oleic acid (17.8 wt%), and myristic acid (8.5 wt%), was effectively altered by both transes‐terification techniques. Arachidic acid, which was not integrated into the initial buttermilk gangliosides, was transacylated to total gangliosides with 23.2 wt% (GD3, 6.7 wt%) by the chemical process and with 8.7 wt% (GD3, 13.8 wt%) when catalyzed enzymatically. Mainly behenic acid and lignoceric acid of GD3 were exchanged chemically, and stearic acid was exchanged by the enzymatic process. This observation might depend on hydrolytic sensitivities of amide‐linked very long chain saturated FA or specific enzyme subtrate affinities, respectively. Results of chemical hydrolysis indicated there was a risk of sialic acid decomposition and unspecific degradations. Regarding specificity and avoidance of critical agents, the enzymatic transesterification is recommended for industrial‐scale production of consumer goods.
Unusual minor nonmethylene‐interrupted di‐, tri‐, and tetraenoic fatty acids in limpet gonads
Authors: Kawashima Hideki
Published: November 2006

Unusual minor nonmethylene‐interrupted (NMI) FA have been identified in the lipids of gonads from the limpets Cellana grata and Collisella dorsuosa by using GC‐MS of the combination of their 4,4‐dimethyloxazoline derivatives and picolinyl esters. Among 23 NMI unsaturated FA from C18 to C22 and C24 identified in this study, 5,11‐nonadecadienoic (5,11‐19∶2), 7,16‐heneicosadienoic (7,16–21∶2), 9,15‐tetracosadienoic (9,15–24∶2), 5,9,15‐docosatrienoic (5,9,15–22∶3), and 5,9,15‐tetracosatrienoic (5,9,15–24∶3) acids may not have been reported previously from living organisms. The presence of 5,11,14,17‐eicosatetraenonoic (5,11,14,17–20∶4) and 7,13,16,19‐docosatetraenenoic (7,13,16,19–22∶4) acids as FA components in marine mollusks may be reported here for the first time. In this study, the male and female gonads of both species showed distinct differences in both their composition and proportions of NMI FA. Most NMI FA identified were mainly present in the female gonads of both species, especially in TAG that contained 21 NMI FA.
Gas chromatography‐chemical ionization‐mass spectrometric fatty acid analysis of a commercial supercritical carbon dioxide lipid extract from New Zealand green‐lipped mussel (Perna canaliculus)
Authors: Wolyniak Christopher J. , Brenna J. Thomas , Murphy Karen J. , Sinclair Andrew J.
Published: November 2006

Supercritical fluid extracts of New Zealand green‐lipped mussels (NZGLM) have been suggested to have therapeutic properties related to their oil components. The large number of minor FA in NZGLM extract was characterized by a GC‐CIMS/MS method that excels at identification of double‐bond positions in FAME. The extract contained five major lipid classes: sterol esters, TAG, FFA, sterols, and polar lipids. The total FA content of the lipid extract was 0.664 g/mL. Fifty‐three unsaturated FA (UFA) were fully identified, of which 37 were PUFA, and a further 21 UFA were detected for which concentrations were too low for assignment of double‐bond positions. There were 17 saturated FA, with 14∶0, 16∶0, and 18∶0 present in the greatest concentration. The 10 n−3 PUFA detected included 20∶5n−3 and 22∶6n−3, the two main n−3 FA; n−3 PUFA at low concentrations were 18∶3, 18∶4, 20∶3, 20∶4, 21∶5, 22∶5, 24∶6, and 28∶8. There were 43 UFA from the n−4, n−5, n−6, n−7, n−8, n−9, n−10, n−11 families, with 16∶2n−4, 16∶1n−5, 18∶1n−5, 18∶2n−6, 20∶4n−6, 16∶1n−7, 20∶1n−7, 16∶1n−9, 18∶1n−9, and 20∶1n−9 being the most abundant. In general, we estimated that FAME concentrations greater than 0.05% (w/w) were sufficient to assign double‐bond positions. In total, 91 FA were detected in an extract of the NZGLM, whereas previous studies of fresh flesh from the NZGLM had reported identification of 42 FA. These data demonstrate a remarkable diversity of NZGLM FA.
A deep‐sea coral record of North Atlantic radiocarbon through the Younger Dryas: Evidence for intermediate water/deepwater reorganization
Authors: Eltgroth Selene F. , Adkins Jess F. , Robinson Laura F. , Southon John , Kashgarian Michaele
Published: November 2006

Our record of Younger Dryas intermediate‐depth seawater Δ14C from North Atlantic deep‐sea corals supports a link between abrupt climate change and intermediate ocean variability. Our data show that northern source intermediate water (∼1700 m) was partially replaced by 14C‐depleted southern source water at the onset of the event, consistent with a reduction in the rate of North Atlantic Deep Water formation. This transition requires the existence of large, mobile gradients of Δ14C in the ocean during the Younger Dryas. The Δ14C water column profile from Keigwin (2004) provides direct evidence for the presence of one such gradient at the beginning of the Younger Dryas (∼12.9 ka), with a 100‰ offset between shallow (<∼2400 m) and deep water. Our early Younger Dryas data are consistent with this profile and also show a Δ14C inversion, with 35‰ more enriched water at ∼2400 m than at ∼1700 m. This feature is probably the result of mixing between relatively well 14C ventilated northern source water and more poorly 14C ventilated southern source intermediate water, which is slightly shallower. Over the rest of the Younger Dryas our intermediate water/deepwater coral Δ14C data gradually increase, while the atmosphere Δ14C drops. For a very brief interval at ∼12.0 ka and at the end of the Younger Dryas (11.5 ka), intermediate water Δ14C (∼1200 m) approached atmospheric Δ14C. These enriched Δ14C results suggest an enhanced initial Δ14C content of the water and demonstrate the presence of large lateral Δ14C gradients in the intermediate/deep ocean in addition to the sharp vertical shift at ∼2500 m. The transient Δ14C enrichment at ∼12.0 ka occurred in the middle of the Younger Dryas and demonstrates that there is at least one time when the intermediate/deep ocean underwent dramatic change but with much smaller effects in other paleoclimatic records.
Diagnosing atmosphere‐ocean general circulation model errors relevant to the terrestrial biosphere using the Köppen climate classification
Authors: Gnanadesikan Anand , Stouffer Ronald J.
Published: November 2006

Coupled atmosphere‐ocean‐land‐sea ice climate models (AOGCMs) are often tuned using physical variables like temperature and precipitation with the goal of minimizing properties such as the root‐mean‐square error. As the community moves towards modeling the earth system, it is important to note that not all biases have equivalent impacts on biology. Bioclimatic classification systems provide means of filtering model errors so as to bring out those impacts that may be particularly important for the terrestrial biosphere. We examine one such diagnostic, the classic system of Köppen, and show that it can provide an “early warning” of which model biases are likely to produce serious biases in the land biosphere. Moreover, it provides a rough evaluation criterion for the performance of dynamic vegetation models. State‐of‐the art AOGCMs fail to capture the correct Köppen zone in about 20–30% of the land area excluding Antarctica, and misassign a similar fraction to the wrong subzone.
Semiempirically derived heating function of the corona heliosphere during the Whole Sun Month
Authors: Guhathakurta M. , Sittler E. C. , Ofman L.
Published: November 2006

In spite of many recent developments in observations and models of the solar corona, the exact form of the heating function of the solar wind plasma is unknown. Here we attempt to make some progress on that problem by applying a previously developed simplified magnetohydrodynamic model to a unique synthesis of remote sensing coronal observations from SOHO and Spartan 201, and in‐situ data from Ulysses spacecraft during the quiescent phase of solar cycle 23 (1995–1997) which also included the Whole Sun Month (August/September 1996) study period. Our analysis provides for the first time an empirically derived estimate of the heat flux and temperature profile of the corona and interplanetary medium over the solar polar regions as a function of latitude and radial distance for this data set. The latitudinal and radial variation is extended to include the equatorial regions but with less fidelity given the significant structure associated with the streamer belt. Our results suggest that both thermal and nonthermal heating terms contribute to the temperature and heat flux in the low corona, particularly above the poles, with the non‐thermal component possibly providing as much as half of the total heat input.
Fermi level pinning in heavily neutron-irradiated GaN
Authors: Polyakov A. Y. , Smirnov N. B. , Govorkov A. V. , Markov A. V. , Kolin N. G. , Merkurisov D. I. , Boiko V. M. , Shcherbatchev K. D. , Bublik V. T. , Voronova M. I. , Lee I-H. , Lee C. R. , Pearton S. J. , Dabirian A. , Osinsky A. V.
Published: November 2006

Undoped n-GaN grown by two different metallorganic chemical vapor deposition (MOCVD) techniques, standard MOCVD and epitaxial lateral overgrowth, and Mg-doped p-GaN prepared by hydride vapor phase epitaxy and molecular beam epitaxy were irradiated with fast reactor neutrons to the high fluence of 1018 cm−2. In such heavily irradiated samples the Fermi level is shown to be pinned in a narrow interval of Ec−(0.8−0.95) eV, irrespective of the starting sample properties. The Fermi level pinning position correlates with the measured Schottky barrier height in n-type GaN. The results are interpreted from the standpoint of the existence of the charge neutrality level in heavily disordered material. Based on published theoretical calculations and on deep level transient spectroscopy (measurements and lattice parameter measurements in irradiated material), it is proposed that the Fermi level could be pinned between the gallium-interstitial-related deep donors near Ec−0.8 eV and nitrogen-interstitial-related acceptors near Ec−0.9 eV
Localization effects in a periodic quantum graph with magnetic field and spin-orbit interaction
Authors: Pankrashkin Konstantin
Published: November 2006

A general technique for the study of magnetic Rashba Hamiltonians in quantum graphs is presented. We use this technique to show how manipulating the magnetic and spin parameters can be used to create localized states in a certain periodic graph (T3 lattice).
Chaotic dynamics of the nuclear magnetization on account of resonator effects
Authors: Ugulava A. I. , Chotorlishvili L. L. , Toklikishvili Z. Z. , Sagaradze A. V.
Published: November 2006

The nonlinear system of Bloch equations describing the dynamics of the magnetization is investigated in the cases of weak and strong nonlinearity. Nonlinearity appears as a consequence of the influence of the oscillator circuit. It is shown that in the case of weak nonlinearity one can use perturbation theory to obtain an analytical solution that agrees well with the results of numerical calculations. In the case of strong nonlinearity the motion of the magnetization can have a stochastic character, similar to a strange attractor. The fractal dimension of the stochastic attractor is estimated.
Detection of an anomalous resistivity peak in the UFe4Al8 single crystal in the temperature region 160–100K and negative magnetoresistance at fields to 400Oe
Authors: Dmitriev V. M. , Terekhov A. V. , Suski V.
Published: November 2006

An anomalous peak of the resistivity of single crystals of the uranium compound UFe4Al8 in the temperature interval 160–100K is observed experimentally. The peak is suppressed by weak magnetic fields of 1–400Oe (negative magnetoresistance). The maximum lowering of the resistivity in a magnetic field H=400Oe is observed at the maximum of the anomaly and reaches 25%. Possible mechanisms of anomalous behavior of the electric transport in the temperature interval 160–100K are discussed.
Study of the mobility of small copper clusters on a xenon buffer layer at temperatures of 30–70K
Authors: Marchenko I. G. , Neklyudov I. M.
Published: November 2006

The migration of small copper clusters over the (111) surface of solid xenon is investigated by computer simulation. The diffusion coefficients of stable clusters are obtained for temperatures of 30–70K. It is found that copper clusters of four, six, and seven atoms are embedded in the substrate, displacing an Xe atom, in less than 3ns. The data permit a new interpretation of the results of experiments done previously.
Lowering lasing threshold in ferroelectric liquid crystal sandwiched between dielectric multilayers
Authors: Matsuhisa Yuko , Haase Wolfgang , Fujii Akihiko , Ozaki Masanori
Published: November 2006

The authors have investigated laser action in ferroelectric liquid crystal (FLC) sandwiched between dielectric multilayers composed of SiO2 and TiO2. The single-mode laser action was observed at the band edge of FLC. The lasing threshold was much lower than that of simple FLC because of the double optical confinement caused by the sandwich structure. They have also demonstrated the tuning of lasing wavelength by applying an electric field.
Heterophase fluctuations in solid helium near the hcp–bcc phase transformation line and melting curve
Authors: Karasevskiĭ A. I.
Published: November 2006

It is shown that in crystals whose melting curve lies close to a line of structural transitions on the PT phase diagram, heterophase fluctuations can have a crystal–liquid structure and consist of crystallites of the nonequilibrium phase surrounded by a layer of liquid. It is shown that such crystal–liquid inclusions can form in the bcc phase of the He4 crystal, which provides an explanation for the features of the kinetic, thermodynamic, and structural properties of the He4 crystal in the bcc region.
Ab initio thermodynamics and phase diagram of solid magnesium: A comparison of the LDA and GGA
Authors: Mehta S. , Price G. D. , Alfè D.
Published: November 2006

The finite temperature density functional theory and quasiharmonic lattice dynamics have been used to compute numerous thermodynamic properties of hexagonal close packed magnesium using both the local density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange-correlation potential. Generally, it is found that there exist only minor differences between the LDA and GGA computed properties, with both giving good agreement with experiment. The hcp-bcc phase boundary has also been computed and is found to be in agreement with experimental observation. Again, only slight differences are found between the LDA and GGA.
Gradients of the polarization energy in the effective fragment potential method
Authors: Li Hui , Netzloff Heather M. , Gordon Mark S.
Published: November 2006

The effective fragment potential (EFP) method is an ab initio based polarizable classical method in which the intermolecular interaction parameters are obtained from preparative ab initio calculations on isolated molecules. The polarization energy in the EFP method is modeled with asymmetric anisotropic dipole polarizability tensors located at the centroids of localized bond and lone pair orbitals of the molecules. Analytic expressions for the translational and rotational gradients (forces and torques) of the EFP polarization energy have been derived and implemented. Periodic boundary conditions (the minimum image convention) and switching functions have also been implemented for the polarization energy, as well as for other EFP interaction terms. With these improvements, molecular dynamics simulations can be performed with the EFP method for various chemical systems.
Photoluminescence and photoconductivity in CdTe crystals doped with Bi
Authors: Saucedo E. , Ruiz C. M. , Bermúdez V. , Dieguez E. , Gombia E. , Zappettini A. , Baraldi A. , Sochinskii N. V.
Published: November 2006

Defect levels in CdTe doped with Bi are studied by low temperature photoluminescence, photoinduced current transient spectroscopy, photoconductivity measurements, and optical absorption. Two centers associated with the doping with Bi are reported. The first one, a deep level located at Ev+0.71eV, only present at low dopant concentrations, has donor character and hole-trap properties, and is mainly responsible for the high resistivity and very high photoconductivity of the samples. The second one, an acceptor center located at Ev+0.30eV, assigned to BiTe species, is only present at high dopant concentrations and is mainly responsible for the low resistivity and poor photoconductivity of these samples.
The electron affinity of phenanthrene
Authors: Tschurl Martin , Boesl Ulrich , Gilb Stefan
Published: November 2006

Phenanthrene is studied by photodetachment-photoelectron spectroscopy. Due to the absence of a parent ion peak in the anion mass spectrum the electron affinity could not be determined directly. However, this absence is the first indication that this molecule has a negative electron affinity. The first three water complexes of phenanthrene were studied, supplying insights into its microsolvation property. Moreover, the electron affinity of the bare molecule could be determined to be −0.01±0.04eV by an extrapolation method using the water cluster data. The experimental work is supported by ab initio calculations for determining the structure of the water complexes. Finally a correlation between the electron affinity and the reduction potential of polycyclic aromatic hydrocarbons is investigated.
Role of rotational temperature in adiabatic molecular alignment
Authors: Kumarappan Vinod , Bisgaard Christer Z. , Viftrup Simon S. , Holmegaard Lotte , Stapelfeldt Henrik
Published: November 2006

One-dimensional alignment of molecules in the adiabatic limit, where the pulse duration greatly exceeds the molecular rotational periods, is studied experimentally. Four different asymmetric top molecules (iodobenzene, p-diiodobenzene, 3,4-dibromothiophene, and 4,4′-dibromobiphenyl), rotationally cooled through a high pressure supersonic pulsed valve, are aligned by a 9-ns-long pulse. Their orientations are measured through Coulomb explosion, induced by a 130-fs-long pulse, and by recording the direction of the recoiling ions. The paper focuses on the crucial role of the initial rotational temperature for the degree of alignment. In particular, we show that at molecular temperatures in the 1K range very strong alignment is obtained already at intensities of a few times 1011W∕cm2 for all four molecules. At the highest intensities (∼1012W∕cm2) the molecules can tolerate without ionizing ⟨cos2θ⟩⩾0.92 in the case of iodobenzene. This is the strongest degree of alignment ever reported for any molecule.
Hot carrier type exchange in inorganic electroluminescent thin films
Authors: Tanaka Katsu , Okamoto Shinji
Published: November 2006

The authors have observed the hot carrier type (holes or electrons) exchange in rare-earth-ion-activated strontium thiogallate (SrGa2S4) thin films by measuring the transient electroluminescent wave forms of the devices having a single insulating thin film. Measured wave forms revealed that the green electroluminescence of europium activated SrGa2S4 thin film occurs due to hot hole excitation. In contrast, the blue electroluminescence of cerium activated SrGa2S4 thin film occurs due to hot electron excitation. Hence, the hot carrier type is exchanged by the different rare-earth-ion doping.
Magneto-optical study of magnetization reversal asymmetry in exchange bias
Authors: Tillmanns A. , Oertker S. , Beschoten B. , Güntherodt G. , Leighton C. , Schuller Ivan K. , Nogués J.
Published: November 2006

The asymmetric magnetization reversal in exchange biased Fe∕MnF2 involves coherent (Stoner-Wohlfarth) magnetization rotation into an intermediate, stable state perpendicular to the applied field. We provide here the experimentally tested analytical conditions for the unambiguous observation of both longitudinal and transverse magnetization components using the magneto-optical Kerr effect. This provides a fast and powerful probe of coherent magnetization reversal as well as its chirality. Surprisingly, the sign and asymmetry of the transverse magnetization component of exchange biased, low-anisotropy MnF2 and high-anisotropy FeF2 change with the angle between cooling and measurement fields.
Factors Affecting Reaction of 1,6-Anhydrohexos-2-ulose Derivatives
Authors: Kawai T , Isobe M , Peters SC
Published: November 2006

1,6-Anhydrohexos-2-ulose derivatives undergo reaction with ( trimethylsilyl )diazomethane in the presence of boron trifluoride etherate to afford structurally isomeric products. Ion-dipole interactions involving the 1,6-anhydro bridge and C4 substituents control reactivity.
A,B-Diheteropentalenes by a Tandem Intramolecular Diels-Alder/Reverse Diels-Alder Reaction Sequence. Application to the Synthesis of Thieno[3,4-b]furan
Authors: Buttery JH , Moursounidis J , Wege D
Published: November 2006

Alkylation of 2-furylmethanethiol (28) with propargyl chloride gave the thioether (22) which on methoxycarbonylation afforded the acetylenic ester (30). On heating, this material underwent an intramolecular Diels -Alder reaction to give the tricyclic compound (32). In the presence of 3,6- di (pyridin-2′-yl)-s- tetrazine , (32) afforded methyl 4,6-dihydrothieno[3,4-b]furan-3-carboxylate (38) by a sequence involving a further Diels -Alder reaction followed by two reverse Diels-Alder reactions. The ester (38) could be dehydrogenated to give methyl thieno [3,4-b]furan-3-carboxylate (40) while hydrolysis of (38), followed by decarboxylation and dehydrogenation delivered the parent thieno [3,4-b]furan (5). 3-Methyl-4,6-dihydrothieno[3,4-b]furan (46) and 3-methylthieno[3,4-b]furan (47) were prepared; a comparison of the 4JMe-C=C-H coupling constants in the 1H n.m.r . spectra of (46) and (47) suggests that an increase in the C2-C3 furyl bond order accompanies the (46) → (47) conversion. Methyl 4,6-dihydrofuro[3,4-b]furan-3-carboxylate (39), 4,6-dihydrofuro[3,4-b]furan (27) and methyl 4,6-dihydro-6-phenylfuro[3,4-b]furan-3-carboxylate (53) were prepared by an analogous tandem reaction sequence. These compounds could not be dehydrogenated to the fully conjugated furo [3,4-b]furan ring system.
Raymond L. Martin
Authors: Masters T , Masters T
Published: November 2006

No Abstract Available.
The Influence of the Axial Ligands of a Series of Platinum(IV) Anti-Cancer Complexes on Their Reduction to Platinum(II) and Reaction With DNA
Authors: Ellis LT , Er HM , Hambley TW
Published: November 2006

The electrochemical reduction and DNA binding have been studied for a series of platinum(IV) complexes with Cl-, OH-, and carboxylate anions as the axial ligands ; [Pt(en)Cl4], [Pt(en)Cl2(OH)2], and [Pt(en)Cl2(OC(O)R)2], R = CH3, CH2CH3, CH2CH2CH3. Cathodic reduction potentials vary by more than 650 mV with the tetrachloro complex reduced most readily and the dihydroxo least readily. The binding of the complexes correlates with the reduction potentials with the more readily reduced complexes binding more readily to DNA. The influence of the reducing agent glutathione on platinum binding to DNA was found to depend on whether it was added before or after Pt/DNA incubation. The results are consistent with octahedral platinum(IV) binding monofunctionally to DNA, and molecular modelling studies have been used to confirm that this is sterically feasible. The crystal structure of [Pt(en)Cl2(OC(O)CH3)2] has been determined by X-ray diffraction methods and refined to R = 0.028 (977 F). The crystals are monoclinic, space group C2/c, a 15.569(6), b 8.104(1), c 13.188(1) Ǻ, β 136.38(2)°.
Totarol: a Non-Conventional Diterpenoid
Authors: Bendall JG , Cambie RC
Published: November 2006

The chemistry of totarol, a naturally occurring diterpenoid phenol which does not obey the isoprene rule, is reviewed. Unexpected transformations of the compound are described as well as attempts to utilize the compound for synthesis.
Novel Cationic Surfactants Derived From Metal Ion Cage Complexes: Potential Antiparasitic Agents
Authors: Behm CA , Boreham PFL , Creaser II , Korybutdaszkiewicz B , Maddalena DJ , Sargeson AM , Snowdon GM
Published: November 2006

The paper describes the synthesis and properties of a series of macrobicyclic cage cobalt(III) complexes which have lipophilic substituents . Those with paraffin tails, C8 or larger, have detergent-like characteristics and are able to penetrate biological membranes. A selection of the reagents was tested in vitro against parasitic nematodes, cestodes, trematodes and protozoa. Compounds with tails longer than C8 effectively killed the organisms at concentrations ≤10-3 M. In vivo against cestodes, that activity was also evident and biodistribution following oral administration showed that the compounds were confined to the gastrointestinal tract, unlike organic detergents such as cetylpyridinium chloride which are absorbed systemically. It is argued that the high charge and size of the head group of the complex detergents destabilize the exterior membrane of the organism. This new class of detergents, appropriately formulated, may be an effective new method of treating gastrointestinal parasites via this novel mode of action.
Synthesis of 4-[ω-(3-Thienyl)alkyl]pyridines and 4-[ω-(3-Thienyl)alkyl]-2,2'-bipyridines
Authors: Wang JX , Pappalardo M , Keene FR
Published: November 2006

The synthesis is reported of 4-[ω-(3-thienyl)alkyl]pyridine (2), 4-[ω-(3-thienyl)alkyl]-2,2′- bipyridine (3) and 4-methyl-4'-[ω-(3-thienyl)alkyl]-2,2′-bipyridine (4), where the length of the alkyl chain is varied (n = 2, 5, 7, 9, 11). The synthetic methodology involved the reaction of the 3-(ω- bromoalkyl ) thiophen with the anions derived from 4-methylpyridine, 4-methyl-2,2′-bipyridine or 4,4′-dimethyl-2,2′-bipyridine by lithiation . The n.m.r. (1H and 13C) and electronic spectral characteristics of the compounds are discussed.
The Chemistry of Pyrrolic Compounds. LXX. The Synthesis of Model Porphyrins as an Aid to the Recognition of Chlorobium-Derived Petroporphyrins in the Julia Creek Oil Shale Deposit
Authors: Atkinson EJ , Clezy PS , Leung CWF , Ramadan S , Salek A , Zhuo MX
Published: November 2006

In order to obtain evidence for the presence of Chlorobium -derived petroporphyrins in the Julia Creek oil shales a range of simple porphyrins (10d-i) carrying the type of side chain characteristic of Chlorobium chlorophylls has been prepared for study by mass spectroscopic techniques. One approach to the preparation of a Chlorobium-type petroporphyrin by ring synthesis has met with very limited success.
Cyclopentadienyl-Ruthenium and -Osmium Chemistry. XL. X-Ray Crystal Structures of MBr (PPh3)2(η-C5H5).CH2Cl2 (M = Ru, Os)
Authors: Bruce MI , Low PJ , Skelton BW , Tiekink ERT , Werth A , White AH
Published: November 2006

The crystal and molecular structures of MBr (PPh3)2(η-C5H5).CH2Cl2 (M = Ru and Os) have been determined. A revised synthesis of the bromo osmium complex is given. The coordination geometry about the metal atom is based on a distorted octahedron with one face being occupied by the cyclopentadienyl group [average Ru -C(Cp) 2.214(3), Os-C(Cp) 2.177(3)Ǻ] and the other by the bromide [ Ru -Br 2.5683(8), Os-Br 2.5438(9)Ǻ] and the two phosphorus atoms [ Ru -P 2.323(2), 2.329(1); Os-P 2.290(2), 2.297(2)Ǻ]. Structural parameters are compared with those of the corresponding chloro complexes and differ only minimally. Crystals of MBr (PPh3)2(η-C5H5).CH2Cl2 are triclinic, space group Pī , with unit cell dimensions ( Ru [Os]): a 14.374(5) [14.276(4)], b 14.057(4) [13.959(3)], c 10.012(5) [9.903(3)]Ǻ, α 99.43(3) [99.79(2)], β 105.60(3) [105.74(2)], γ 100.42(3) [100.39(2)]°, V 1868(1) [1817.7(9)] Ǻ3, Z 2. The structures were refined by a full-matrix least-squares procedure to R 0.050 [0.036] for 7365 [5108] reflections with I ≥ 3σ(I).