bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunosuppressive Activity of the Ethanol Extract of Siegesbeckia orientalis on the Immune Responses to Ovalbumin in Mice
Authors: Sun Hong‐Xiang , Wang Hua 
Published: July 2006

AbstractThe in vitro and in vivo immunosuppressive activity of the ethanol extract of Siegesbeckia orientalis (EESO) was studied on the immune responses in mice. EESO significantly suppressed concanavalin A (Con A)‐ and lipopolysaccharide (LPS)‐stimulated splenocyte proliferation in vitro in a concentration‐dependent manner. ICR Mice were immunized subcutaneously with ovalbumin (OVA) on days 0 and 14. Beginning on the day of immunization, the mice were administered intraperitoneally with EESO at a single dose of 0.25, 0.5, and 1.0 mg at intervals of 7 days. On day 28, OVA‐specific antibodies in serum, and mitogen‐ and OVA‐induced splenocyte proliferation were measured. EESO significantly suppressed Con A‐, LPS‐ and OVA‐induced splenocyte proliferation in the OVA‐immunized mice in a dose‐dependent manner. The OVA‐specific serum IgG, IgG1, and IgG2b levels in the OVA‐immunized mice were also significantly reduced by EESO. Moreover, reducing effect on the IgG1 antibody of EESO at the dose of 1.0 mg was more significant than that of cyclosporin A (CsA; positive drug). The results suggest that EESO could suppress the cellular and humoral response to ovalbumin in mice, and deserve further investigations to be developed as immunosuppressant.
Synthesis of dl‐Alanine Hollow Tubes and Core‐Shell Mesostructures
Authors: Ma Yurong , Börner Hans G. , Hartmann Jürgen , Cölfen Helmut 
Published: July 2006

AbstractThree double hydrophilic block copolymers were used as crystal‐growth modifiers of dl‐alanine to generate amorphous precursor nanoparticles that undergo subsequent mesoscopic transformation to core‐shell mesostructures and hollow tubes with quadratic cross‐sections. The growth sequence can be stopped at various stages so that a series of intermediates between amorphous core‐ and crystalline‐shell particles and tubes can be obtained. Time‐dependent conductivity, TEM, SEM, and environmental scanning electron microscopy (ESEM) measurements were used to obtain a better understanding of the crystallization process, and a formation mechanism for the generation of the tubes is proposed. Na2SO4, NaCl, and NaNO3 as salts differ in their influence on the crystallization behavior of alanine by changing the solubility of alanine and by decreasing the stability of the intermediate particles. Core‐shell mesostructures that formed in the dissolution–recrystallization process were captured as the transformation rate was decreased by the addition of copolymers or salts. Hollow tubes with quadratic cross‐sections are the final product of the transformation process.
High Structural Control in Metal‐Mediated Synthesis of New Functionalized Diphosphines Using Diphosphinoketenimines as Precursors
Authors: Mosquera Marta E. G. , Ruiz Javier , García Gabriel , Marquínez Fernando 
Published: July 2006

AbstractThe diphosphinoketenimine ligand in the neutral complexes fac‐[MnI(CO)3{(PPh2)2CCNR}] (1 a: R = Ph; 1 b: R = p‐tolyl) undergoes nucleophilic attack by MeLi and nBuMgCl yielding, after hydrolysis, the diphosphinoenamine‐containing complexes fac‐[MnI(CO)3{(PPh2)2CC(R′)NHR}] (3 a,b: R′ = Me; 4 a,b: R′ = nBu). Complex 1 a reacts under the same conditions with H2CCCHMgBr to afford fac‐[MnI(CO)3{(PPh2)2CC(CH2CCCH)NHR}] (5 a), which contains a terminal alkyne group on the α‐carbon atom of the diphosphinoenamine ligand. The cationic complexes fac‐[Mn(CO)4{(PPh2)2CCNR}]+ (6) react with H2CCCHMgBr to afford diphosphinomethanide derivatives bearing three different types of functional groups, depending upon the substituent on the nitrogen atom of the ketenimine: cumulene in fac‐[Mn(CO)4{(PPh2)2CC(CHCCH2)N‐xylyl}] (7 d), internal alkyne in fac‐[Mn(CO)4{(PPh2)2CC(CCCH3)NtBu}] (8), and quinoline in 9 (R = Ph), whose formation implies an unusual cyclization process. Protonation of 7 d, 8, and 9 with HBF4 occurs at the nitrogen atom to give the cationic derivatives 10 d, 11, and 12, respectively, which contain the corresponding functionalized diphosphine ligands. Irradiation of 3 a,b and 4 a,b with Vis/UV light makes it possible to isolate the free ligands (PPh2)2CC(R′)NHR (13 a,b and 14 a,b), completing the metal‐assisted synthesis of these novel functionalized diphosphines. Irradiation of 12 with Vis/UV light generates free phosphinoquinoline ligand 15, which readily affords a complex 16 containing 15 as a P,N‐chelating ligand when treated with [PdCl2(NCMe)2], thus demonstrating its coordination capability.
Substitution of Hydrogen by Deuterium Changes the Regioselectivity of Ethylbenzene Hydroxylation by an Oxo–Iron–Porphyrin Catalyst
Authors: de Visser Sam P. 
Published: July 2006

AbstractHeme oxo–iron complexes are powerful oxygenation catalysts of environmentally benign hydroxylation processes. We have performed density functional theoretic calculations on a model system, that is, an oxo–iron–porphyrin (Por) complex [(FeO)Cl(Por)], and studied its reactivity toward a realistic substrate, namely, ethylbenzene. The calculations showed that the dominant reaction process in the gas phase is benzyl hydroxylation leading to 1‐phenylethanol, with an energetic barrier of 9.1 kcal mol−1, while the competing para‐phenyl hydroxylation has a barrier 3.0 kcal mol−1 higher in energy. This benzyl hydroxylation barrier is the lowest CH hydroxylation barrier we have obtained so far for oxo–iron–porphyrin complexes. Due to electronic differences between the intermediates in the phenyl and benzyl hydroxylation processes, the phenyl hydroxylation process is considerably stabilised over the benzyl hydroxylation mechanism in environments with a large dielectric constant. In addition, we calculated kinetic isotope effects of the substitution of one or more hydrogen atoms of ethylbenzene by deuterium atoms and studied its effect on the reaction barriers. Thus, in a medium with a large dielectric constant, a regioselectivity change occurs between [H10]ethylbenzene and [D10]ethylbenzene whereby the deuterated species gives phenol products whereas the hydrogenated species gives mainly 1‐phenylethanol products. This remarkable metabolic switching was analysed and found to occur due to 1) differences in strength between a CH versus a CD bond and 2) stabilisation of cationic intermediates in a medium with a large dielectric constant. We have compared our calculations with experimental work on synthetic oxo–iron–porphyrin catalysts as well as with enzyme‐reactivity studies.
Non‐racemic atropisomeric (thio)ureas as neutral enantioselective anion receptors for amino‐acid derivatives: Origin of smaller Kass with thiourea than urea derivatives
Authors: Roussel Christian , Roman Mihaela , Andreoli Federico , Rio Alberto Del , Faure Robert , Vanthuyne Nicolas 
Published: July 2006

AbstractThe synthesis of a limited series of non‐racemic atropisomeric 1‐(2‐(4‐methyl‐2‐thioxothiazol‐3(2H)‐yl)phenyl)‐3‐(hetero)aryl‐(thio)ureas is described. Using NMR titration experiments monitoring the shift of the two NH of the (thio)urea and the C‐5 hydrogen of the heterocycle, the binding constants for some optically pure (thio)‐ureas with the enantiomers of N‐protected amino acid tetrabutylammonium salts were determined in CD3CN. The obtained enantioselectivities were modest. Contrary to what was expected on the basis of the NH acidity in thiourea versus urea group, the association constants were smaller with the thiourea than with the corresponding urea. X‐ray data, DFT calculations, and NMR provided the explanation of that unexpected behavior: the urea presents a pre‐organized (Z,Z) conformation suitable for a double hydrogen bond with the carboxylate anion, the thiourea presents a (Z,E) conformation, which must be reorganized in a constrained (Z,Z) conformation in the complex. An intramolecular hydrogen bond between one NH and the thiocarbonyl group of the heterocycle, which is present in the thiourea and absent in the urea, might also contribute to the smaller Kass for the thiourea. The possible implication of these observations in the field of bifunctional organocatalysis is briefly discussed. Chirality, 2006. © 2006 Wiley‐Liss, Inc.
Selective distribution and function of primary afferent nociceptive inputs from deep muscle tissue to the brainstem trigeminal transition zone
Authors: Wang Hu , Wei Feng , Dubner Ronald , Ren Ke 
Published: July 2006

AbstractOrofacial injury activates two distinct regions in the spinal trigeminal complex, the subnuclei interpolaris/caudalis (Vi/Vc) transition zone and the laminated Vc, or medullary dorsal horn (MDH). Studies suggest that the Vi/Vc transition zone plays an important role in processing orofacial deep input. To test this hypothesis, we employed a double‐tracing strategy to compare central projections of primary afferent neurons that innervate the masseter muscle and the overlying skin. Different tracers were injected either centrally (Fluoro‐Gold: ventral Vi/Vc, or MDH) or peripherally (wheat germ agglutinin‐conjugated horseradish peroxidase or cholera toxin B: masseter or overlying skin) in the same rat. Trigeminal ganglion tissue sections were processed for single or double immunohistochemistry. The double labeling of ganglion neurons indicates their site of peripheral and central innervations. A population of small to medium‐sized neurons was doubly labeled after injections of the tracers into the masseter‐Vi/Vc, masseter‐MDH, or the skin‐MDH. However, only a few double‐labeled neurons were occasionally observed after injections of the tracers into the skin‐Vi/Vc. Injection of an N‐methyl‐D‐aspartate receptor antagonist, AP‐5, into the Vi/Vc and MDH attenuated masseter inflammatory hyperalgesia. In contrast, hyperalgesia after inflammation of the skin overlying the masseter was attenuated by injection of AP‐5 into the MDH but not Vi/Vc. These results indicate that while both masseter and cutaneous inputs project to the MDH, masseter afferents provide an additional input to the Vi/Vc. These findings provide further evidence to support a role of the trigeminal transition zone in response to orofacial deep injury. J. Comp. Neurol. 498:390–402, 2006. © 2006 Wiley‐Liss, Inc.
The Xfeb gene is directly upregulated by Zic1 during early neural development
Authors: Li Shuzhao , Shin Yongchol , Cho Ken W.Y. , Merzdorf Christa S. 
Published: July 2006

AbstractThe transcription factor Zic1 plays important roles in patterning the neural plate in early vertebrate development. However, few genes that are regulated by Zic1 are known. We have identified a new direct downstream target gene of Zic1 that we have named Xfeb. Xfeb is a member of the pathogenesis‐related (PR) protein superfamily and contains five tandem SCP domains. The sequence of Xfeb suggests that it may possess serine protease activity. Xfeb is expressed in the presumptive hindbrain region during neurula stages and in somite tissues later in development. Xfeb represses the hindbrain gene hoxB1 and the anterior neural gene otx2, suggesting that Xfeb is involved in regionalizing the neural plate, possibly by ensuring a posterior expression limit for otx2. Developmental Dynamics 235:2817–2827, 2006. © 2006 Wiley‐Liss, Inc.
Xenopus Zic4: Conservation and diversification of expression profiles and protein function among the Xenopus Zic family
Authors: Fujimi Takahiko J. , Mikoshiba Katsuhiko , Aruga Jun 
Published: July 2006

AbstractWe compared the expression and function of Xenopus Zic4 with those of the other four Xenopus laevis Zic family members (Zic1, Zic2, Zic3, and Zic5). Zic4 expression was detected mainly in the neural plate border, dorsal neural tube, and somites, and was similar to that of Zic1, which is adjacent to Zic4 on the same chromosome. Injection of wild‐type or mutant Zic4 RNA caused the induction of neural crest marker gene expression, hyperplastic neural tissue, and ectopic pigment cell formation, indicating that Zic4 can induce neural and neural crest tissue, as can other Xenopus Zic genes. Deletion analysis showed that the zinc‐finger domain is critical for many Zic4 functions, but the C‐terminal region is differently involved in induction of two neural crest markers, Slug and Sox10. The protein function as determined by the animal cap explant assay was similar to that of Zic5, but different from those of Zic1, Zic2, and Zic3, suggesting that Xenopus Zic genes can be divided into two groups based on function. These results indicate that the five Xenopus Zic genes cooperatively regulate both neural and neural crest development, despite significantly diverged expression profiles and functions. Developmental Dynamics 235:3379–3386, 2006. © 2006 Wiley‐Liss, Inc.
Bioindication and Functional Response in Floodplain Systems: Where to from Here?
Authors: Henle Klaus , Scholz Mathias , Dziock Frank , Stab Sabine , Foeckler Francis 
Published: July 2006

AbstractWe synthesise the results of the papers in this Special Issue, place them within the context of current trends in floodplain research, and outline promising new avenues that emerge from the contributions. The indication system presented complements existing approaches by focussing on a quantitative indication of environmental parameters. A promising research line that emerges is an extension of the systematic comparison of taxonomic groups with contrasting traits in terms of their performance as quantitative indicators for different environmental parameters. The studies show similarities and dissimilarities in the traits explaining the functional response of plants, molluscs, carabids, and syrphids to site conditions but trait databases and studies on additional taxa are required before broad generalisations can be made. The rigorous study design developed for the RIVA project, of which all contributions in this Special Issue are a part, not only was essential for an improvement of the understanding of species environment relationships and the role biological traits play for it, it also provides a baseline for assessing future change as part of long‐term ecological monitoring of floodplains. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characteristics of synthetic lubricating greases
Authors: Coffin P. S. 
Published: July 2006

AbstractA fundamental characteristic of syntbetic lubricating greases is their price; all cost significantly more, sometimes by several orders of magnitude, than conventional mineral oil based greases. This fact is likely to remain true for the foreseeable future, given a stable supply situation for petroleum feed stocks. In consequence commercially, synthetic greases will only find use where improved performance characteristics over conventional greases justify their extra cost. There is a wide range of synthetic greases and each provides an individual performance profile. For specific applications with demanding performance requirements, one or more synthetic greases may offer considerable benefit over conventional greases. Thus synthetic greases are today being used in significant quantities, but only in those specific applications where the nature of the application places one or more demands on the lubricant that mineral oil based lubricants would find difficult to meet.
Oxidation and inhibition of pentaerythritol esters
Authors: Jensen R. K. , Korcek S. , Zinbo M. 
Published: July 2006

AbstractAutoxidation and inhibited oxidation of pentaerythrityl tetraalkanoates, PETA, at elevated temperatures of 180 to 220°C have been investigated using a representative ester, pentaerytbrityl tetra heptanoate, PETH.1 In order to better understand reactions occurring in alkyl chains of PETA, similar studies were carried out with n‐bexadecane (HD), at 120 to 190°C.2,3 Based on the results of these studies, a general reaction scheme describing liquid phase autoxidation of organic compounds at temperatures of 120 to 220°C has been proposed.4 In this paper, kinetic and mechanistic information applicable to autoxidation of PETA is summarised and our recent contributions in the area of inhibition at elevated temperatures are reviewed.
Aliphatic dicarboxylic acid esters for synthetic lubricants
Authors: Debuan F. , Hänssle P. 
Published: July 2006

AbstractSynthetic base oil components include mainly polyalphaolefins (PAO), dicarboxylic acid esters and polyol esters. In 1977, the world‐wide share of synthetic oils was about 0.5% of lubricant sales; today this is about 2%, and further annual growth rates of between 10 and 20%—relative to present consumption levels—are expected. The motor vehicle share of the synthetic oil market is about 30%, with the trend rising. In recent years, the literature has contained numerous reports on the general advantages and disadvantages of carboxylic acid esters. This standard knowledge is not repeated here. A few special and relatively new aspects are discussed, based on work carried out at VEBA Öl AG and Chemische Werke Hüls AG.
Synthetic lubricating greases for the food industry
Authors: Vámos E. , Neumann E. 
Published: July 2006

AbstractThe requirements of lubricating greases in the deep‐freezing industries, that lubricants do not undergo degradation of their lubricating properties, and the need for non‐aromatic and non‐toxic/non‐carcinogenic lubricants in food production, are discussed. Experimental data on the applicability of synthetic oils as bases for synthetic greases, are presented.
Air entrainment and foaming properties of synthetic lubricants at extreme temperatures
Authors: Hubman A. , Lanik A. 
Published: July 2006

AbstractThis paper examines the relationship between air retention (both by air entrainment and foaming) and lubricant characteristics. Laboratory research found that foaming is related to temperature; it may also be affected by other factors such as impurities. Data is presented on foaming properties and air separation for both mineral and synthetic oils. Foaming is also examined in relation to viscosity.
Recent developments in the performance properties of water based cutting and hydraulic fluids
Authors: Rudston S. G. , Whitby R. D. 
Published: July 2006

AbstractLubricants and functional fluids may be grouped into those based on natural oils and those having man‐made (‘synthetic’) base stocks. This paper is concerned with the ‘dilute synthetic lubricant’ in which the man‐made component is blended with a major proportion of water. The developments covered include hydraulic and metal‐cutting fluids, with examples drawn from experience with solutions and dispersions. The performance required from these fluids in service is discussed with particular attention to improvements in corrosion protection, antiwear performance, extreme‐pressure properties, foam inhibition, air release, rolling bearing fatigue and resistance to erosion pitting. Water quality can have a significant impact on the performance properties of the fluids already listed. The service properties of aqueous lubricants may be classified according to their response to chemical additives. Examples are given of properties which respond well to additives and of those which are governed largely by the bulk physical properties of water. Manufacturers of equipment are continuing to develop new machinery. Fluid formulators are seeking to extend the current operating limitations of aqueous fluids. Future development relies on close co‐operation between users, equipment suppliers and lubricant formulators.
Lubrication and cooling in electricity generating plant
Authors: Goodwin M. J. 
Published: July 2006

AbstractThis paper describes the lubrication and cooling systems of modern electricity generating plant, particularly those of the generator. The paper discusses the development of the power plant manufacturing industry and shows how critical the selection of lubricants and coolants is on the efficiency of the plant. The operation and layout of plant of up to 1,200 MW power rating are described and the various lubrication and cooling systems which are incorporated are identified. The cooling media discussed include non‐synthetic, semi‐synthetic, and synthetic fluids, and in each case the reasons for its selection are examined. Basic design calculations relating to lubrication and cooling systems are included. The paper concludes by examining trends in plant design and how they may affect future selection of lubricants and coolants.
Synthetic lubricants for turbocharged passenger cars
Authors: Neadle D. J. 
Published: July 2006

AbstractThis paper discusses the lubrication requirements of turbocharged passenger car engines and describes some of the experience obtained with petroleum based oils. Features of ester and polyalphaolefin synthetic lubricants are discussed in relation to the requirements of turbocharged engines. An attempt is made to review the present situation with regard to the lubricant types accepted by motor manufacturers and the implications of equipment design changes.
Catalysts for the synthesis of alphaolefin oligomer
Authors: Isa Hiroshi 
Published: July 2006

AbstractThe polymerisation method in the production of alphaolefin oligomer rests on the catalyst selected, and certain conditions are given that the method should fulfil. After a brief examination of the results of three kinds of catalyst, the Friedels‐Craft catalyst type is discussed in terms of production of medium, high and low viscosity alphaolefin oligomers.
Aviation turbine lubricant development
Authors: Bishop G. J. 
Published: July 2006

AbstractThis paper reviews the development of aviation turbine lubricants from the early days of jet propulsion and projects it through to the end of this century. Up to the present period, ester‐based synthetic oils have predominated, and largely fulfilled service requirements. However, ester‐based ‘Type 2’ lubricants are now perceived to be close to their optimum performance level and a new lubricant type will be required for the next generation of engines. The development of a ‘Type 3’ oil presents a great challenge to the aviation industry and could signal a departure from traditional routes of lubricant development.
Helicopter manufacturers' requirements for lubricating oils
Authors: Hartmann Joachim , Jonda Wolfgang 
Published: July 2006

AbstractExperience with existing oils used in helicopters for transmissions, engines, hydraulics and brakes has shown that three main characteristics could drastically improve the performance of the aircraft.These characteristics are: (1) the same type of oil should be usable for all the above mentioned systems; (2) the oil brands, produced to a common specification, but by different manufacturers, should be mixable without restrictions; (3) some features of the oil, which are specially important for helicopter operations, should be improved. Tests on mixed oils are reported, and recommendations made for future specifications.