bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionic Liquids—An Overview
Authors: Forsyth Stewart A. , Pringle Jennifer M. , MacFarlane Douglas R.
Published: February 2004

Ionic liquids have become an increasingly popular class of solvent in the last decade as the potential applications of these materials become more diverse. Rather than being viewed simply as replacement for conventional organic solvent media, research into ionic liquids has progressed to the deliberate choice and design of these materials for reasons of improved rate, specificity, and yield. Design of ionic liquids centres on the development of novel cations and anions to impart the specific physical properties required for each application. Therefore, the materials being synthesized and studied are also becoming increasingly complex and diverse. Here we provide an overview of ionic liquids generally, and some of their current applications, as well as an introduction to some of the new cations and anions that have been developed for specific properties.
Charge Transfer Polymerization in Ionic Liquids
Authors: Vijayaraghavan Ranganathan , MacFarlane Douglas R.
Published: February 2004

Charge transfer (CT) polymerization of methyl methacrylate has been successfully carried out by employing n-butyl amine and carbon tetrachloride as CT initiators and hydroquinone as promoter in room-temperature ionic liquids (ILs) as solvents. The reaction rate and polymer yields at short reaction times are enhanced in the IL solvent compared to conventional solvents. The effect of various reaction conditions including concentration of amine, IL, and temperature have been studied. The polymers were characterized for thermal and molecular weight properties and compared with the conventional CT reaction.
An Evaluation of Some Hindered Diamines as Chiral Modifiers of Metal-Promoted Reactions
Authors: Illesinghe Jayamini , Ebeling Richard , Ferguson Brett , Patel Jim , Campi Eva M. , Jackson W. Roy , Robinson Andrea J.
Published: February 2004

Diamino analogues of the C2-symmetric chiral diphosphine ligands DuPHOS and BPE have been prepared and evaluated as chiral modifiers of the osmium tetraoxide dihydroxylation of stilbene. NMR experiments showed that these ligands were too bulky to coordinate to osmium. Less hindered analogues of these ligands were prepared and some were shown to act as ligands in dihydroxylation reactions but with poor enantioselectivity (e.e. < 10%). The diamines have also been briefly evaluated as ligands in rhodium-catalyzed hydroformylation and copper-catalyzed phenolic coupling reactions. Once again, only low enantioselectivity was obtained.
Metal-Ion Recognition—Selective Bulk Membrane Transport of Silver(I) Using Thioether Donor Macrocycles as Ionophores, and X-Ray Structure of the Silver Complex of an S4-Donor Ring
Authors: Fainerman-Melnikova Marina , Lindoy Leonard F. , Liou Show-Yee , McMurtrie John C. , Green Noel P. , Nezhadali Azizollah , Rounaghi Gholamhossin , Setzer William N.
Published: February 2004

Competitive metal-ion transport experiments, each involving transport from an aqueous source phase containing equimolar concentrations of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(i), and lead(II) across a chloroform membrane phase to an aqueous receiving phase have been carried out. The membrane phase incorporated an ionophore chosen from a series of thioether-containing macrocycles. For those systems that displayed transport behaviour, sole selectivity for silver(I) was observed under the conditions employed. The effect of variation in the macrocyclic sulfur atom donor set and the presence of hydrophilic ring substituents on transport efficiency is presented. An X-ray structure of the 1 : 1 silver(I) nitrate complex of a 16-membered, S4-donor macrocycle shows the presence of four crystallographically independent macrocycles displaying conformational isomerism. Each silver(I) has an approximate tetrahedral geometry, being bound to three sulfur atoms from three different macrocycles and to one nitrato ligand to yield a three-dimensional network.
Design of Ionic Liquids for Electrochemical Applications
Authors: Yoshizawa Masahiro , Narita Asako , Ohno Hiroyuki
Published: February 2004

Zwitterionic liquids composed of a tethered cation and anion were synthesized and their thermal properties and ionic conductivity were investigated as novel ionic liquids especially for electrochemical applications. We prepared nine zwitterions in this study. In addition, this paper includes 36 kinds of zwitterions already reported in order to discuss the relationship between the zwitterion structure and their properties. Most zwitterions melt above 100°C; their melting points are generally higher than that of simple ionic liquids. When an equimolar amount of lithium salt (LiTFSI, LiBETI, LiCF3SO3, LiBF4, or LiClO4) was added to the zwitterion, the mixture showed only a glass transition temperature Tg. The Tg values of the zwitterionic liquid/salt mixture showed the lowest value of –37°C when mixed with LiTFSI. This mixture also showed the highest ionic conductivity of 8.9 × 10–4 S cm–1 at 100°C. There is a good relationship between Tg and the ionic conductivity of the zwitterionic liquid/lithium salt mixtures.
Ionic Liquids Based on Imidazolium and Pyrrolidinium Salts of the Tricyanomethanide Anion
Authors: Forsyth Stewart A. , Batten Stuart R. , Dai Qing , MacFarlane Douglas R.
Published: February 2004

A novel series of tricyanomethanide ionic liquids have been prepared and characterized for potential use as ionic liquid solvents. Full thermal analyses of all salts at ambient and sub-ambient temperatures are reported (melting points –17° to 160°C). The thermal stability and decomposition temperatures are also presented (Tdecomp ≈ 300°C). An electrochemical window of ~3 V has been established and the conductivity measured over a range of temperatures (20 mS cm–1 at 25°C).
Manganese Dioxide Allylic and Benzylic Oxidation Reactions in Ionic Liquids
Authors: Hemeon Ivan , Barnett Neil W. , Gathergood Nicholas , Scammells Peter J. , Singer Robert D.
Published: February 2004

Ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate [bmIm][BF4] and 1-butyl-3-methylimidazolium hexafluorophosphate [bmIm][PF6] were evaluated as reaction media for allylic and benzylic oxidation reactions using manganese dioxide. The use of ionic liquids as an extractant in the reaction work-up was also investigated. Procedures for recycling of the [bmIm][PF6] ionic liquids used in these MnO2 oxidation reactions were also developed.
Keto - Enol Tautomerism as a Polarity Indicator in Ionic Liquids
Authors: Earle Martyn J. , Engel Brian S. , Seddon Kenneth R.
Published: February 2004

The keto–enol tautomeric equilibrium for pentane-2,4-dione has been explored in several ionic liquids and these data have been used to give an indication of their polarities in the ground state. The results suggest higher apparent polarities than have been previously indicated by the use of solvatochromatic dyes.
A Long-Chain Phosphine Designed as a Metallomesogen Generator—Synthesis and Coordination Properties
Authors: Soulivong Daravong , Matt Dominique , Harrowfield Jack , Toupet Loïc
Published: February 2004

The long-chain phosphine Me2PC≡C(p-C6H4CHNR C8) [L; RC8 = p-C6H4OC(O)(p-C6H4OC8H17)] has been prepared in two steps starting from 4-ethynylbenzaldehyde (1): (a) condensation of 1 with H2NRC8 (2) afforded the corresponding imine 3 (yield 86%) which displays liquid-crystalline behaviour; (b) deprotonation of 3 with LiNPri2 and subsequent reaction with Me2PCl gave a mixture of the phosphine–alkyne L and the precursor 3 (L : 3 = 60 : 40). Reaction of this mixture with [PtCl2(PhCN)2] produced cis-[PtCl2L2] (4) and provided an efficient means of separating the phosphine from 3. The crystal structure of imine 3 has been determined by single-crystal X-ray diffraction and analysis of this structure provides a basis for understanding both the mesogenic character of 3 and its absence in the complex 4.
Krox-20 inhibits Jun-NH2-terminal kinase/c-Jun to control Schwann cell proliferation and death
Authors: Parkinson David B. , Bhaskaran Ambily , Droggiti Anna , Dickinson Sarah , D'Antonio Maurizio , Mirsky Rhona , Jessen Kristjan R.
Published: February 2004

The transcription factor Krox-20 controls Schwann cell myelination. Schwann cells in Krox-20 null mice fail to myelinate, and unlike myelinating Schwann cells, continue to proliferate and are susceptible to death. We find that enforced Krox-20 expression in Schwann cells cell-autonomously inactivates the proliferative response of Schwann cells to the major axonal mitogen β–neuregulin-1 and the death response to TGFβ or serum deprivation. Even in 3T3 fibroblasts, Krox-20 not only blocks proliferation and death but also activates the myelin genes periaxin and protein zero, showing properties in common with master regulatory genes in other cell types. Significantly, a major function of Krox-20 is to suppress the c-Jun NH2-terminal protein kinase (JNK)–c-Jun pathway, activation of which is required for both proliferation and death. Thus, Krox-20 can coordinately control suppression of mitogenic and death responses. Krox-20 also up-regulates the scaffold protein JNK-interacting protein 1 (JIP-1). We propose this as a possible component of the mechanism by which Krox-20 regulates JNK activity during Schwann cell development.
Spectral dynamics in the B800 band of LH2 from Rhodospirillum molischianum: a single-molecule study
Authors: Hofmann Clemens , Aartsma Thijs J , Michel Hartmut , Köhler Jürgen
Published: January 2004

The BChlaabsorptions in the B800 spectrum of individual LH2 complexes fromRhodospirillum molischianumshow sudden, reversible spectral jumps between a finite number of spectral positions. From our data, we conclude that these fluctuations result from conformational changes of the protein backbone in close vicinity of the chromophores which provides a sensitive tool to monitor local modulations of the pigment–protein interaction.
A Propensity Score Reweighting Approach to Estimating the Partisan Effects of Full Turnout in American Presidential Elections
Authors: Brunell Thomas L. , DiNardo John
Published: February 2004

Borrowing an approach from the literature on the economics of discrimination, we estimate the impact of nonvoters on the outcome of presidential elections from 1952–2000 using data from the National Election Study (NES). Our estimates indicate that nonvoters are, on average, slightly more likely to support the Democratic Party. Of the 13 presidential elections between 1952 and 2000 we find no change in the eventual outcome of the election with two possible exceptions: 1980 and 2000. Thus our results are not all that dissimilar from other research on participation. Higher turnout in the form of compulsory voting would not radically change the partisan distribution of the vote. When elections are sufficiently close, however, a two percentage point increase may suffice to affect the outcome. Limitations of the NES data we use suggest that our estimates underestimate the impact of nonparticipation. We also compare our method with other econometric techniques. Finally, using our findings we speculate as to why the Democratic Party fails to undertake widespread “get out the vote” or registration drives.
Characterising and profiling health Web user and site types: going beyond “hits”
Authors: Huntington Paul , Nicholas David , Williams Peter
Published: February 2004

Identifies Internet health user types according to three factors: site attributes most favoured, health topics most sought, and the health sites they visited. Knowing what type of consumer uses a site is important, as this should inform menu structure and provide an understanding of why certain kinds of people visit certain sites. Web sites even in the same field will not appeal to all users. Much of this differentiation will come down to design and feel of the site, although site attributes and information needs also impact here. Data were obtained from an online questionnaire placed on the SurgeryDoor Web site, a site which provides consumer health information. In all a total of 1,068 responses were received. Shows that useful groupings can indeed be constructed. Users were also classified according to additional health sites visited, also a preference metric, and this additionally is related to site attribute preferences, information needs and user characteristics.
Seeking alcohol information on the Internet
Authors: Joinson Adam N. , Banyard Phil
Published: February 2004

It has been argued that people may be more willing to seek potentially threatening information on the Internet than they would in “real life”. For alcohol drinkers, potentially threatening information includes diagnostic information on the amount they drink, and information about the negative effects of alcohol consumption. In the present study, participants with varying levels of alcohol intake and plans for change chose four alcohol‐related articles to read (from 12), using either the World Wide Web (WWW) or pen and paper. Results showed that drinkers not currently reducing their drinking were more likely to seek diagnostic, potentially threatening anti‐drinking information via the WWW compared with when seeking paper‐based information. Drinkers either contemplating or engaging in efforts to reduce their drinking sought pro‐drinking information on the WWW and anti‐drinking information when using pen and paper. The potential role of the Internet, and perceived anonymity, in health promotion are discussed.
Manipulators help out with plaster panels in construction
Authors: Gonzalez de Santos Pablo , Estremera Joaquin , Jimenez Maria A. , Garcia E. , Armada M.
Published: February 2004

Building construction is a great area for automation, but the incorporation of robots in the construction industry is a very slow affair because of the intrinsic difficulties. New requirements, however, now call for material‐handling manipulators to be used to help operators move and position heavy payloads without accidents. Builders are also being encouraged to provide automatic tools by the EU labour legislation, which limits the maximum payload that operators are allowed to carry. This paper introduces a manipulator to assist the operators in handling and installing pre‐manufactured plaster panels for indoor‐wall construction. This six degrees of freedom manipulator is fixed between floor and ceiling so that it can carry heavy payloads without tumbling. The whole system is easily assembled and disassembled to facilitate transportation between construction sites. The system's main features and its functions are presented.
“Business wargaming”: simulations guide crucial strategy decisions
Authors: Kurtz Jay
Published: February 2004

“Business wargaming” is a role‐playing simulation of a dynamic business situation that involves a series of teams, each assigned to assume the identity of an entity with a stake in the situation. The process steps for wargaming, important lessons to follow, and a case study are all presented in this article. Wargames offer unique benefits at two points in an organization’s strategic planning process: (1) at its outset, wargames are helpful to convert data and information (about markets, channels, competitors, etc.) into actionable intelligence for subsequent planning; (2) after a basic plan is developed, a wargame can test the plan to ensure it is robust enough to succeed in any realistic combination of events or actions. Attributes of a business wargame: (1) it involves intense competition among five to ten teams, each representing a distinct stakeholder (such as the market, key customers, suppliers, partners, competitors, channels, regulators); (2) the team interact based both on quantitative and qualitative information. Through the use of role playing, cultural issues, rivalries and other subjective factors guide development and assessment of strategies; (3) the wargame process forces a rigorous exam of a situation from multiple perspectives. The various points of view (some hostile) allow the company to recognize opportunities and threats otherwise not noticed using just an “inside‐out” approach; and (4) the gaming allows a broad range of ideas to be developed while the teams aggressively compete to outsmart each other. The time, cost, and effort in preparing a major wargame are spelled out. The case illustrates the potential pay‐off in situations where the wargame makes strategic choices apparent.
The RICS valuation and appraisal standards
Authors: French Nick
Published: February 2004

The Royal Institution of Chartered Surveyors (RICS) has, over a period of more than 25 years, provided guidance and mandatory advice to valuers providing valuations in the UK in the form of a series of appraisal and valuation manuals. In May 2003, the latest edition of these manuals was published: The RICS Valuation and Appraisal Standards. One of the principal aims of the new (fifth) edition was to reflect the increasing international status of the RICS. As a result the new “standards” will clarify the distinction between standards, which are of relevance to members worldwide, and those that are specific to practice in the UK. Effectively, the new book is implementing the RICS policy of adopting and supporting international valuation standards.
The Efficiency of State Child Support Enforcement Programs
Authors: Good David H. , Pirog‐Good Maureen A.
Published: February 2004

The success of the Child Support Enforcement Program has been questionable since its inception in 1975. This paper attempts to measure the success of the state CSE programs through the development of several performance measures.
Treatment of postpartum thrombotic microangiopathy with plasma exchange using cryosupernatant as replacement
Authors: Lampinen Katja , Peltonen Seija , Pettilä Ville , Kaaja Risto
Published: February 2004

Hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP) are rare but acknowledged problems of pregnancy and the postpartum period. These diseases together with thrombotic angiopathy are associated with high maternal and fetal mortality and severe long‐term morbidity. We describe four women with postpartum HUS/TTP treated with plasma exchange cryosupernatant fraction of plasma (CFP) as replacement fluid. Anuria or oliguria at the beginning of treatment and thrombocytopenia [thromb‐ (29–68) × 109/L] were common features. Two of the patients developed a prolonged and more difficult clinical condition affecting the central nervous system and the liver and their platelet counts remained low despite the plasma exchange. The renal and hepatic function of all of the patients recovered fully. This small analysis lends weight to early plasma exchange with cryosupernatant as part of the treatment of postpartum HUS/TTP and suggests that persistent thrombocytopenia is a signal of more serious disease.
Reduced amount of cytochrome c oxidase subunit I messenger RNA in placentas from pregnancies complicated by preeclampsia
Authors: He Liping , Wang Zehua , Sun Yongyu
Published: February 2004

Background.  Cytochrome c oxidase is a marker enzyme of the mitochondrial inner membrane. A change in the structure and activity of cytochrome c oxidase may alter the electron transport in the inner membrane, leading to insufficient adenosine triphosphate (ATP) production. ATP is essential for maintaining the function of cells. The aim of this study was to compare the expression of cytochrome c oxidase subunit I mRNA in placentas from normal and preeclamptic pregnancies.

Methods.  By means of in situ hybridization, frozen sections of placentas from 23 women with preeclampsia and 29 women with uneventful pregnancies were examined. Digoxigenin (DIG)‐labeled probes were used to detect the expression of cytochrome c oxidase subunit I mRNA in the placentas. The expression density was assessed by using an image disposal and analysis system.

Results.  Positive expression of cytochrome c oxidase subunit I mRNA was found in the cytoplasm of villous syncytiotrophoblasts. The mean light density of cytochrome c oxidase subunit I mRNA in placental villi of normal pregnant women was 0.2638, and 0.1763 in women with preeclampsia, a statistically significant difference (P < 0.05). The number density of cytochrome c oxidase subunit I mRNA in placental villi was also significantly reduced in preeclamptic women compared with the control group (P < 0.05).

Conclusions.  Our study demonstrates a reduced amount of cytochrome c oxidase subunit I mRNA in preeclamptic placentas compared to control placentas. We hypothesize that a reduced expression may play a role in the pathophysiology of preeclampsia.
Rethinking the concept of community of practice in relation to schoolteachers’ workplace learning
Authors: Hodkinson Heather , Hodkinson Phil
Published: February 2004

This paper explores two different ways of understanding communities of practice in relation to workplace learning. This is based upon a case study of secondary school teachers working and learning in four subject departments in two English schools. In spite of institutional similarities, the cultures and working practices of the departments were different, and influenced the learning of the workers significantly. In such contexts, a tight conceptualisation of community of practice can form a valuable intermediate scale of analysis, between the individual learner and wider organisational influences on learning. However, communities of practice can also have a valuable meaning in relation to the wider influences and in situations where close‐knit groupings do not exist.
K‐ras and B‐raf gene mutations are not associated with gastrin‐ and CCK2‐receptor mRNA expression in human colorectal tumour tissues
Authors: Monstein H.‐J. , Fransén K. , Dimberg J. , Söderkvist P.
Published: February 2004

Background  Colorectal cancer is a multistep process caused by genetic alterations in cell growth regulatory genes such as K‐ras and B‐raf. It has been assumed that mutations in the K‐ras gene induce gastrin gene expression and that gastrin stimulates the growth of colorectal cancer in an autocrine fashion by coexpressing gastrin and cholecystokinin (CCK)2 receptors. The aim of this study was to examine a possible association of K‐ras and B‐raf gene mutations with gastrin and CCK2 receptor mRNA expression in human colon and rectum tumour biopsy specimens.

Methods  K‐ras and B‐raf gene mutations as well as gastrin and CCK2 receptor mRNA expression in 50 colon and 46 rectum biopsies, respectively, were determined using molecular biology methods.

Results  K‐ras mutations occurred in 44% colon and 30% rectum and B‐raf mutations in 16% colon and 4% rectum tumours, respectively. Gastrin mRNA was expressed in 64% colon and 61% rectum tumours, whereas CCK2 receptor mRNAs was expressed in 32% colon and 13% rectum tumours. K‐ras or B‐raf gene mutations and simultaneous gastrin mRNA expression was observed in 40% colon and 17% rectum tumours, respectively. Co‐expression of gastrin and CCK2 receptor mRNA occurred in 20% colon and 9% rectal tumours.

Conclusions  The results do not support the hypothesis that K‐ras and B‐raf gene mutations have an impact on gastrin‐ and CCK‐receptor mRNA expression in colorectal tumour tissues.
Endoglin (CD105) expression in the development of haemorrhoids
Authors: Chung Y.‐C. , Hou Y.‐C. , Pan A. C.‐H.
Published: February 2004

Background  Conventional pathogenesis of haemorrhoid emphasized the anchoring connective tissue system, whereas the vascular changes were ignored. The aim of this study was to clarify vascular changes of haemorrhoid disease.

Materials and methods  Forty‐six samples of grade III and grade IV haemorrhoid tissue were selected for an in vitro study. We assessed the expressions in endoglin (CD105), an accessory protein in transforming growth factor‐β receptor complex, in CD34 and in vascular endothelial growth factor by using an immunohistochemical method. Microvascular density was calculated to correlate the expression of endoglin.

Results  Microvascular density was higher in haemorrhoid tissue than in normal anal and lower rectal tissues. CD34 was demonstrated in whole vessels in the haemorrhoids. However, endoglin, a proliferative marker of neovascularization, was present in only 25 of 46 (54%) haemorrhoidal vessels, and its immunoactivity was prominent in venules larger than 100 µm. Thrombosis formation and stromal vascular endothelial growth factor was significantly associated with the presence of endoglin immunoactivity.

Conclusion  The results of this study suggest that neovascularization is one important phenomenon of haemorrhoid disease, along with conventional venous dilatation and arteriovenous communication. In addition, thrombosis and stromal vascular endothelial growth factor might be important factors in promoting vascular proliferation.
The Dynamics of the Hypothalamic‐Pituitary‐Adrenal Axis During Maternal Deprivation
Authors: Schmidt M. , Enthoven L. , Van Woezik J. H. G. , Levine S. , De Kloet E. R. , Oitzl M. S.
Published: February 2004

A close contact between the dam and the litter is essential for the normal development of the hypothalamic‐pituitary‐adrenal (HPA) axis in rats and mice. Maternal signals, as licking and feeding, have been shown to sustain the HPA axis of the pups in a hypo‐responsive state. Disruption of this mother–pup interaction by 24 h of maternal deprivation activates the otherwise quiescent stress system of the neonates, resulting in an enhanced adrenal sensitivity to adrenocorticotropic hormone (ACTH) and a decreased expression of central HPA markers, such as corticotropin‐releasing hormone (CRH). However, the dynamics of these central and peripheral changes over the 24h period are largely unknown. In this study, we examined the time course of some of the central and peripheral indices of HPA activity during 24 h of maternal deprivation. We measured corticosterone and ACTH in the blood as well as CRH, mineralocorticoid and glucocorticoid receptor expression in the brain. Our results demonstrate that each of the components of the HPA axis responds to maternal deprivation at different time points following removal of the mother and with a very specific time course. The main activation of the HPA axis occurred between 4 h and 8 h of maternal absence. By contrast, during the second half of the deprivation period, negativefeedback mechanisms restrained the further increase in ACTH and corticosterone release. We conclude that maternal deprivation triggers a cascade of sequential changes at the various levels of the stress system, and that measuring only one aspect of the system at one time point does not accurately reflect the dynamic alterations of the HPA axis.
Differing involvement of sulfoquinovosyl diacylglycerol in photosystem II in two species of unicellular cyanobacteria
Authors: Aoki Motohide , Sato Norihiro , Meguro Ayano , Tsuzuki Mikio
Published: February 2004

Sulfoquinovosyl diacylglycerol (SQDG) is involved in the maintenance of photosystem II (PSII) activity in Chlamydomonas reinhardtii[Minoda, A., Sato, N., Nozaki, H., Okada, K., Takahashi, H., Sonoike, K. & Tsuzuki, M. et al. (2002) Eur. J. Biochem.269, 2353–2358]. To understand the spread of the taxa in which PSII interacts with SQDG, especially in cyanobacteria, we produced a mutant defective in the putative sqdB gene responsible for SQDG synthesis from two cyanobacteria, Synechocystis sp. PCC6803 and Synechococcus sp. PCC7942. The mutant of PCC6803, designated SD1, lacked SQDG synthetic ability and required SQDG supplementation for its growth. After transfer from SQDG‐supplemented to SQDG‐free conditions, SD1 showed decreased net photosynthetic and PSII activities on a chlorophyll (Chl) basis with a decrease in the SQDG content. Moreover, the sensitivity of PSII activity to 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea and atrazine was increased in SD1. However, SD1 maintained normal amounts of cytochrome b559 and D1 protein (the subunits comprising the PSII complex) on a Chl basis, indicating that the PSII complex content changed little, irrespective of a decrease in the SQDG content. These results suggest that the role of SQDG is the conservation of the PSII properties in PCC6803, consistent with the results obtained with C. reinhardtii. In contrast, the SQDG‐null mutant of PCC7942 showed the normal level of PSII activity with little effect on its sensitivity to PSII herbicides. Therefore, the difference in the SQDG requirement for PSII is species‐specific in cyanobacteria; this could be of use when investigating the molecular evolution of the PSII complex.
The unusual methanogenic seryl‐tRNA synthetase recognizes tRNASer species from all three kingdoms of life
Authors: Bilokapic Silvija , Korencic Dragana , Söll Dieter , Weygand‐Durasevic Ivana
Published: February 2004

The methanogenic archaea Methanococcus jannaschii and M. maripaludis contain an atypical seryl‐tRNA synthetase (SerRS), which recognizes eukaryotic and bacterial tRNAsSer, in addition to the homologous tRNASer and tRNASec species. The relative flexibility in tRNA recognition displayed by methanogenic SerRSs, shown by aminoacylation and gel mobility shift assays, indicates the conservation of some serine determinants in all three domains. The complex of M. maripaludis SerRS with the homologues tRNASer was isolated by gel filtration chromatography. Complex formation strongly depends on the conformation of tRNA. Therefore, the renaturation conditions for in vitro transcribed isoacceptor were studied carefully. This tRNA, unlike many other tRNAs, is prone to dimerization, possibly due to several stretches of complementary oligonucleotides within its sequence. Dimerization is facilitated by increased tRNA concentration and can be diminished by fast renaturation in the presence of 5 mm magnesium chloride.
Characterization of the products of the genes SNO1 and SNZ1 involved in pyridoxine synthesis in Saccharomyces cerevisiae
Authors: Dong Yi‐Xin , Sueda Shinji , Nikawa Jun‐Ichi , Kondo Hiroki
Published: February 2004

Genes SNO1 and SNZ1 are Saccharomyces cerevisiae homologues of PDX2 and PDX1 which participate in pyridoxine synthesis in the fungus Cercospora nicotianae. In order to clarify their function, the two genes SNO1 and SNZ1 were expressed in Escherichia coli either individually or simultaneously and with or without a His‐tag. When expressed simultaneously, the two protein products formed a complex and showed glutaminase activity. When purified to homogeneity, the complex exhibited a specific activity of 480 nmol·mg−1·min−1 as glutaminase, with a Km of 3.4 mm for glutamine. These values are comparable to those for other glutamine amidotransferases. In addition, the glutaminase activity was impaired by 6‐diazo‐5‐oxo‐l‐norleucine in a time‐ and dose‐dependent manner and the enzyme was protected from deactivation by glutamine. These data suggest strongly that the complex of Sno1p and Snz1p is a glutamine amidotransferase with the former serving as the glutaminase, although the activity was barely detectable with Sno1p alone. The function of Snz1p and the amido acceptor for ammonia remain to be identified.
Identification of residues controlling transport through the yeast aquaglyceroporin Fps1 using a genetic screen
Authors: Karlgren Sara , Filipsson Caroline , Mullins Jonathan G. L. , Bill Roslyn M. , Tamás Markus J. , Hohmann Stefan
Published: February 2004

Aquaporins and aquaglyceroporins mediate the transport of water and solutes across biological membranes. Saccharomyces cerevisiae Fps1 is an aquaglyceroporin that mediates controlled glycerol export during osmoregulation. The transport function of Fps1 is rapidly regulated by osmotic changes in an apparently unique way and distinct regions within the long N‐ and C‐terminal extensions are needed for this regulation. In order to learn more about the mechanisms that control Fps1 we have set up a genetic screen for hyperactive Fps1 and isolated mutations in 14 distinct residues, all facing the inside of the cell. Five of the residues lie within the previously characterized N‐terminal regulatory domain and two mutations are located within the approach to the first transmembrane domain. Three mutations cause truncation of the C‐terminus, confirming previous studies on the importance of this region for channel control. Furthermore, the novel mutations identify two conserved residues in the channel‐forming B‐loop as critical for channel control. Structural modelling‐based rationalization of the observed mutations supports the notion that the N‐terminal regulatory domain and the B‐loop could interact in channel control. Our findings provide a framework for further genetic and structural analysis to better understand the mechanism that controls Fps1 function by osmotic changes.
A case of unilateral renal cystic disease
Authors: LEE SIK , PARK SUNG K , KANG SUNG K , KIM WON
Published: February 2004

SUMMARY:  Unilateral renal cystic disease (URCD) is a distinct entity that is one of the renal cystic diseases. The clinical importance of URCD is to make a differential diagnosis from autosomal dominant polycystic kidney disease (ADPKD), multicystic dysplastic kidney, multilocular cystic renal neoplasm, and simple cysts. To confirm the diagnosis and to rule out asynchronous ADPKD requires long‐term follow up, especially in younger patients.
Fas‐induced apoptosis is a feature of progressive diabetic nephropathy in transgenic (mRen‐2)27 rats: Attenuation with renin‐angiotensin blockade
Authors: KELLY DARREN J , STEIN‐OAKLEY ALICIA , ZHANG YUAN , WASSEF LESLEY , MAGUIRE JULIE , KOJI TAKEHIKO , THOMSON NAPIER , WILKINSON‐BERKA JENNIFER L , GILBERT RICHARD E
Published: February 2004

Background and Aim:  Tubular atrophy is a major feature of most renal diseases and is closely associated with the loss of renal function. The present study sought to investigate whether Fas/FasL‐induced tubular epithelial cell apoptosis was a feature of experimental diabetic nephropathy. The effects of renoprotective therapy with blockade of the renin‐angiotensin (RAS) system were also examined.

Method:  Six‐week‐old female Ren‐2 rats were injected with streptozotocin and maintained diabetic for 12 weeks. Further groups of diabetic rats were treated with the angiotensin‐converting enzyme inhibitor, perindopril, for 12 weeks.

Results:  Widespread apoptosis, identified by using mediated Terminal dUTP nick‐end labelling (TUNEL) staining was noted in the tubules of diabetic Ren‐2 rats. These changes were associated with an increase in both Fas mRNA and Fas L (ligand) within the tubules (P < 0.01). Treatment of diabetic Ren‐2 rats with perindopril (6 mg/kg per day) reduced the apoptosis to control levels and was associated with a reduction in Fas mRNA and Fas L protein (P < 0.05).

Conclusion:  In conclusion, Fas/Fas L‐induced tubular apoptosis is a feature of diabetic Ren‐2 rats and is attenuated by the blockade of the RAS.
Seasonal changes in the germination responses of buried seeds of three native eastern North American winter annuals
Authors: BASKIN CAROL C. , BASKIN JERRY M. , CHESTER EDWARD W.
Published: February 2004

Long‐term studies of seasonal changes in temperature and light : dark requirements for germination were conducted on seeds of Plantago virginica (87 months), Silene antirrhina (32.5 months) and Triodanis perfoliata (36.5 months), buried under natural temperature regimes in central Kentucky, USA. Seeds of P. virginica exhibited an annual conditional dormancy/non‐dormancy cycle; thus, the species has the potential to behave as a facultative winter annual. Seeds of T. perfoliata and S. antirrhina had an annual dormancy/non‐dormancy cycle, but dormancy induction was not completed until April or May. Thus, depending on the year, 3–21% and 1–97% of the S. antirrhina and T. perfoliata seeds, respectively, germinated in March and these species also have the potential to behave as facultative winter annuals. Data from long‐term buried seeds studies in central Kentucky are now available for 16 native (including the three species reported in this paper) and nine non‐native winter annuals of eastern North America. Buried seeds of non‐natives, as well as those of natives whose geographic range extends beyond eastern North America, tend to have a conditional dormancy/non‐dormancy cycle, while those of natives with a range restricted to eastern North America tend to have a dormancy/non‐dormancy cycle. However, testing of this hypothesis will have to await data for more winter annuals so that a phylogenetically independent analysis can be conducted.
Segmentation Versus Integration: The Case of Non‐Homogeneous Groups
Authors: Spiegel U. , Templeman J.
Published: February 2004

The paper adds another dimension to the literature on bundling as a profit‐maximizing strategy. We compare policies of joint consumption and segmentation of a profit maximizer. In the case of positive social influences between two population groups ‘bundling’ is preferred to segmentation, while under negative symmetric inter‐group effects (based perhaps on race, religion, status etc.) segmentation is preferred. Our contribution lies in the examination of joint consumption versus segmentation under asymmetric inter‐group effects, with and without price discrimination. This can occur when non‐homogeneous groups share the same residency, school or other local public institutions.
Teaching repetition as a communicative and cognitive tool: evidence from a Spanish conversation class
Authors: Roebuck Regina F. , Wagner Lisa C.
Published: February 2004

The development of conversational abilities in the second language depends upon the appropriation of both cognitive and communicative skills, in addition to overall linguistic improvement. In terms of needed skills, speaking is often considered at the expense of listening, which has long been thought of as a passive exercise. However, listening and speaking must be developed together as active discursive practice, that is, in the same way in which they are used in conversation. The focus of the present project is to investigate whether or not students can be taught to use a specific linguistic tool, a feature of private speech known as repetition, as a cognitive and communicative resource in order to facilitate their interactions with other learners. Analysis of students’ production in several different classroom tasks suggests that learners are able to use repetition for a number of communicative and cognitive functions, in response to instruction and extended practice.
Influence of low temperature preanneals on dopant and defect behavior for low energy Ge preamorphized silicon
Authors: Camillo-Castillo R. A. , Law M. E. , Jones K. S. , Rubin L. M.
Published: February 2004

The hold temperature of an anneal plays a crucial role in controlling the final activation and diffusion of dopants. A study on the influence of a variety of low temperature preanneals on the behavior of dopants and defects for low energy germanium preamorphization is conducted. Si wafers are preamorphized with 1×1015 cm−2 Ge+ at energies of 10, 12, 15, 20, and 30 keV and implanted with 1×1015 cm−2, 1 keV B+. Furnace preanneals are performed at 450, 550, 650, and 750 °C; the samples are subsequently subjected to a spike RTA at 950 °C. Defect analyses indicate an energy threshold above which the preanneal has an effect on the defect density. Further experiments are conducted on the 10 keV Ge+ preamorphizing implant in which the second anneal step is conducted at 750 °C for various times. An analysis of the defect evolution with time reveals that the evolution does not follow previously reported Ostwald ripening-type behavior. The microstructure is populated with very small dot-like defects, which simply dissolve with time, suggesting that the boron may play some role in the defect evolution.
Two-dimensional ultrashallow junction characterization of metal-oxide-semiconductor field effect transistors with strained silicon
Authors: Wang Xiang-Dong , Liu Chun-li , Thean Aaron , Duda Erika , Liu Ran , Xie Qianghua , Lu Shifeng , Barr Alex , White Ted , Nguyen Bich-yen , Orlowski Marius
Published: February 2004

Strained Si has been realized as one of the most promising candidates of next generation complementary metal-oxide-semiconductor technology. Since the carrier mobility can be significantly increased with strained Si lattice, the device speed can be further increased without reducing the critical dimensions. However, ultrashallow junction engineering becomes more challenging due to much complicated dopant diffusion behavior. We have used scanning capacitance microscopy and dopant selective etching to characterize such differences by comparing the devices fabricated with strained Si channel and with conventional unstrained Si. The devices we used are p-type channel complementary metal-oxide-semiconductor field effect transistors fabricated with 130 nm technology, with strained Si channel built on SiGe pseudosubstrate. Significant differences were observed in the formation of source/drain (S/D) extensions. The junction profile shows abrupt transition from S/D extension to S/D comparing with unstrained Si. Meanwhile, halo implant was much suppressed. These differences can be explained with retarded B diffusion and enhanced As diffusion in tensile strained Si and relaxed SiGe lattices, which is consistent with the calculation using lattice expansion theory.
Towards reproducible scanning capacitance microscope image interpretation
Authors: Kopanski J. J. , Marchiando J. F. , Rennex B. G. , Simons D. , Chau Q.
Published: February 2004

Scanning capacitance microscope (SCM) images, and the two-dimensional (2D) dopant profiles extracted from them, show poor reproducibility from laboratory to laboratory. Major factors contributing to SCM image variability include: poor sample surface and oxide quality, excess carrier generation from stray light, reduced sensor dynamic range from stray capacitance, and use of nonoptimal SCM operating voltages. This article discusses the sources of SCM image variability, how they affect the measured SCM images, and possible approaches for mitigating their effects. Recommended procedures for extracting quantitative 2D are discussed. Finally, a set of informal research materials is introduced consisting of a complementary metal-oxide-semiconductor transistor pair, an identical pair without metallization, and a pair of transistor-like structures with the conductivity type of the source/drains reversed. These structures are intended for use with the FASTC2D software to help improve laboratory-to-laboratory dopant profile reproducibility.
Metal film characterization with qualified spreading resistance
Authors: Clarysse T. , Hoflijk I. , Zhang W. , Maex K. , Vandervorst W.
Published: February 2004

The spreading resistance probe (SRP) tool is widely used for obtaining the electrically active dopant profile in silicon. In this work, the capabilities of SRP for thin metal film (Cu/Al/TaN) characterization are investigated. It is well known that quite large correction factors (∼500) are involved in sub-100 nm silicon SRP profiling to extract the underlying carrier depth profiles from the measured raw resistances. These large correction factors also allow, in principle, for the characterization of sub-100 nm metal layers, as their measured resistances will fall in the 1–100 ohm range. Structures consisting of Cu or Al metal layers, respectively, with different thicknesses (25–400 nm) on a Ta/TaN barrier layer (∼20 nm) on SiO2 have been characterized with SRP. For calibration, the characteristics of the probe imprints have been measured with atomic force microscopy. Present results indicate that for the thinnest Cu films, it is possible to obtain a resistivity depth profile in good agreement with available theoretical predictions, based on the impact of an electron mean-free-path length of 39 nm.
High-resolution scanning spreading resistance microscopy of surrounding-gate transistors
Authors: Álvarez D. , Schömann S. , Goebel B. , Manger D. , Schlösser T. , Slesazeck S. , Hartwich J. , Kretz J. , Eyben P. , Fouchier M. , Vandervorst W.
Published: February 2004

Scanning spreading resistance microscopy (SSRM) was performed in surrounding-gate transistors for 70 nm dynamic random access memories. Sub-10 nm features were resolved using full diamond tips and different processing schemes were correlated with the electrical characteristics of the devices and the SSRM measurements. SSRM was found to be a powerful tool for the characterization and failure analysis determination of this device concept in the very small scale.
Electrical test structures for mapping nanometer-scale pattern placement errors
Authors: Wang Fu-Min , Pease R. Fabian W.
Published: February 2004

Mapping, with nanometer-scale precision, overlay errors, and other pattern errors, is obviously needed in the development of any patterning technology, and the electrical test structures for this purpose have been commercially available for some time. In prior work [M. W. Cresswell, M. Gaitan, R. A. Allen, and L. W. Linholm, Proc. IEEE 4, 129 (1991)], it was pointed out that the nonzero width of the voltage taps introduced errors but that these could be compensated using a modified structure. We have designed, built and evaluated simple voltage dividing potentiometers with narrower taps to minimize the earlier errors and the mapping pattern errors are within a few nanometers. Our preliminary devices have tap widths of 200 nm. The test structures are implemented in 80 nm Au on 5 nm Ti on an oxidized silicon wafer and the measurements of displacement between −100 and 100 nm were made with a precision better than 10 nm.
Nanoimprint using three-dimensional microlens mold made by focused-ion-beam chemical vapor deposition
Authors: Watanabe K. , Morita T. , Kometani R. , Hoshino T. , Kondo K. , Kanda K. , Haruyama Y. , Kaito T. , Fujita J. , Ishida M. , Ochiai Y. , Tajima T. , Matsui S.
Published: February 2004

Three-dimensional diamond-like carbon mold fabricated by focused-ion-beam chemical vapor deposition (FIB–CVD) using a precursor of phenanthrene has been applied to a nanoimprint lithography (NIL) process. The mold has a very smooth surface, which is one of the advantages for the fabrication of optical devices. FIB–CVD uses a Ga+ beam control system which convert three-dimensional computer aided design data into the scanning signal and is capable of fabricating any shape of optical device mold surface such as a microlens. The microlens molds have been replicated onto poly(methylmethacrylate) (PMMA) and hydrogen silsequioxane using NIL. A microlens of polydimenthyl siloxane has been fabricated by replication using the PMMA reversal mold fabricated by NIL using the FIB–CVD mold.
Vertically aligned carbon nanofiber-based field emission electron sources with an integrated focusing electrode
Authors: Guillorn M. A. , Yang X. , Melechko A. V. , Hensley D. K. , Hale M. D. , Merkulov V. I. , Simpson M. L. , Baylor L. R. , Gardner W. L. , Lowndes D. H.
Published: February 2004

We report on the design, fabrication, and initial characterization of vertically aligned carbon nanofiber-based microfabricated field emission devices with an integrated out-of-plane electrostatic focusing electrode. The potential placed on this electrode was found to have a profound impact on the diameter of the beam emitted from the device as observed on a phosphor screen. Aspects of the device fabrication process and device operation are discussed. The experimental results obtained are compared to a numerical simulation of device performance and found to be within good agreement.