bluuebunny/crossref_metadata_2025_split huggingface dataset:
Methanofullerenes from Macrocyclic Malonates
Authors: Carano Maurizio , Corvaja Carlo , Garlaschelli Luigi , Maggini Michele , Marcaccio Massimo , Paolucci Francesco , Pasini Dario , Righetti Pier Paolo , Sartori Elena , Toffoletti Antonio 
Published: December 2002

AbstractIn this paper we describe the synthesis and intercomparison of several new methanofullerenes, each bearing a macrocyclic crown ether containing a malonate moiety directly attached to the C60‐fullerene core. Their complexing abilities with primary alkylammonium ions were investigated by NMR and mass spectrometry, and also by transport experiments through a liquid membrane. We also report on their electrochemical behaviour, together with EPR analysis of their supramolecular complexes with alkyl ammonium molecules labelled with a stable nitroxide radical. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
A Straightforward Synthesis of N‐Functionalized β‐Diimines
Authors: Maraval Alexandrine , Igau Alain , Donnadieu Bruno , Majoral Jean‐Pierre 
Published: December 2002

AbstractReaction of Schwartz’s reagent [Cp2ZrHCl]n (1) (one or two equivalents) with gem‐dinitrile compounds of the type X(CN)2 [X = CMe2, CBenz2, P(NiPr2)2] gives the corresponding mono‐ and di‐N‐zirconated imino complexes selectively. Substitution reactions of the zirconocene metal fragment with electrophiles such as, for example, chlorophosphanes of the type R2PCl, acid chlorides RC(O)Cl or the iminium salt [CH2NMe2]Cl allowed the preparation of a large variety of stable N‐functionalized mono‐ and β‐diimine derivatives. The nature of the X group is of particular importance for the success of the substitution reaction step. The X‐ray crystal structures obtained for the N‐functionalized gem‐aldimino‐nitrile compounds 9, 10b, the N‐phosphorylated β‐diimine 32, and the gem‐formyl nitrile derivative 12b are presented. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Effects of prenyl pyrophosphates on the binding of PKCγ with RACK1
Authors: Chen Yu‐Hsun , Wang Han‐Chung , Lin Ching‐Yu , Chuang Nin‐Nin 
Published: December 2002

AbstractReceptors for activated C kinase (RACKs) are a group of PKC binding proteins that have been shown to mediate isoform‐selective functions of PKC and to be crucial in the translocation and subsequent functioning of the PKC isoenzymes on activation. RACK1 cDNA from the shrimp Penaeus japonicus was isolated by homology cloning. The hepatopancreas cDNA from this shrimp was found to encode a 318‐residue polypeptide whose predicted amino acid sequence shared 91% homology with human Gβ2‐like proteins. Expression of the cDNA of shrimp RACK1 in vitro yielded a 45‐kDa polypeptide with positive reactivity toward the monoclonal antibodies against RACK1 of mammals. The shrimp RACK1 was biotinylated and used to compare the effects of geranylgeranyl pyrophosphate and farnesyl pyrophosphate on its binding with PKCγ in anti‐biotin‐IgG precipitates. PKCγs were isolated from shrimp eyes and mouse brains. Both enzyme preparations were able to inhibit taxol‐induced tubulin polymerization. Interestingly, when either geranylgeranyl pyrophosphate or farnesyl pyrophosphate was reduced to the submicrogram level, the recruitment activity of RACK1 with purified PKCγ was found to increase dramatically. The activation is especially significant for RACK1 and PKCγ from different species. The observation implies that the deprivation of prenyl pyrophosphate might function as a signal for RACK1 to switch the binding from the conventional isoenzymes of PKC (cPKC) to the novel isoenzymes of PKC (nPKC). A hydrophobic binding pocket for geranylgeranyl pyrophosphate in RACK1 is further revealed via prenylation with protein geranylgeranyl transferase I of shrimp P. japonicus. J. Exp. Zool. 295A:71–82, 2003. © 2003 Wiley‐Liss, Inc.
Monoclonal antibody G3 epitope location on Guinea pig sperm membrane protein, sperad
Authors: Ilayperuma Isurani 
Published: December 2002

AbstractA protein isolated from guinea pig testes was purified, characterized as having a molecular weight of 34 kDa, and subjected to amino acid sequencing. A monoclonal antibody to the protein (G11) was found to cross‐react with a second monoclonal antibody (G3). Two peptide sequences derived from the purified protein, labeled as 34 kDa G11, show sequence homology with sperad. Sperad is a transmembrane protein present in the peri‐acrosomal plasma membrane of guinea pig spermatozoa. Both G11 and G3 monoclonal antibodies recognise antigens on the equatorial segment plasma membrane of guinea pig spermatozoa following the acrosome‐reaction. Therefore, experiments were designed to check whether monoclonal antibody G3 epitope is present on the sperad. The intra‐cytoplasmic domain and the extra‐cytoplasmic domain of sperad was amplified from a guinea pig testes cDNA expression library by polymerase chain reaction and cloned into pGEM T‐Easy vector. The recombinant pGEM T‐Easy plasmids were subjected to in vitro transcription and translation by rabbit reticulocyte lysate system. The resulting translated products were immunoprecipitated with monoclonal antibody G3. The results obtained from this study confirmed that monoclonal antibody G3 epitope is located on the extra‐cytoplasmic domain but not on the intra‐cytoplasmic domain of sperad. J. Exp. Zool. 295A:92–98, 2003. © 2003 Wiley‐Liss, Inc.
The Statistical Regression Calculation in Plastics Processing – Process Analysis, Optimization and Monitoring
Authors: Heim Hans‐Peter 
Published: December 2002

AbstractPlastics processing companies can only meet up to present‐day quality requirements if they adopt systematic methods. This holds particularly true for the extremely stringent demands that are now placed on injection molding technology. Working on from a sound experimental basis, it is possible to define cause/effect correlations for two sets of empirical data (the current process conditions and the molded part attributes) for each quality variable by using a statistical process model. The process model enables the processor to calculate the effect of each individual combination of parameters in the experimental area and to perform an optimization. If it proves possible to describe the cause/effect correlation between the fluctuations in the molded part attributes and those in the process parameters by means of a statistical process model, then this can be used for the continuous monitoring of production. The statistical experimentation method and continuous process monitoring are grouped together to form the so‐called CPC concept, permitting traceable, gap‐free documentation of the quality data for a production chain. Three examples are set out to illustrate the possibilities for use of the CPC concept; these are then assessed on the basis of the benefit observed.
Engine‐cooling fan.magnified imageEngine‐cooling fan.
Flexible Use of Single‐Screw Extruders through Multiple‐Process Optimization
Authors: Potente Helmut , Pape Jens 
Published: December 2002

AbstractUsing general‐purpose screws to process different types of material offers considerable cost advantages over special‐purpose screws. Designing screws of this type is generally a difficult task, since modifications to different aspects of the geometry can run counter to each other in some cases. Optimization software is thus of particular benefit here. For this reason, a program was developed for the optimization of general‐purpose screws. A central feature of this program is an appraisal system for the computer‐aided evaluation of single‐screw simulations. The performance of the software was verified on the basis of actual extrusion experiments.
Temperature measuring cross for measuring thermal homogeneity.magnified imageTemperature measuring cross for measuring thermal homogeneity.
Extruder Concept for the Direct Plastification of Cereal Materials
Authors: Potente Helmut , Reckert Frank 
Published: December 2002

AbstractIn the wake of a growing environmental awareness, the substitution of conventional plastics by biologically degradable materials is assuming ever‐greater importance. The displacement of conventional plastics made from fossil raw materials by materials that are manufactured either fully or in part from agriculturally‐produced, harvested goods constitutes one of the technically feasible uses of renewable raw materials. The successful market introduction of alternative products, however, requires not only consideration of the qualitative aspect but also an eye to the economic factors. It is for this reason that an extruder concept is presented here that can be used for directly plastificating cereal materials in the form of coarsely ground grain, for example. This then opens up the way to a low‐price basic material which also holds a high potential when viewed in economic terms. After giving a short overview of the possibilities that exist for the plastification of materials containing starch, this paper takes a look at the differences between this alternative extruder concept and the conventional single‐screw extrusion process for thermoplastics. Further details are given of the solids conveyance and plastification processes to this end.
Schematic diagram of the arrangement of the functional sections.magnified imageSchematic diagram of the arrangement of the functional sections.
Calcium fluxes in human trophoblast (BeWo) cells: Calcium channels, calcium‐ATPase, and sodium‐calcium exchanger expression
Authors: Moreau Robert , Simoneau Lucie , Lafond Julie 
Published: December 2002

AbstractAlthough placental transfer of maternal calcium (Ca2+) is a crucial process for fetal development, the biochemical mechanisms are poorly understood. In the current study, we have investigated the characteristics of Ca2+ fluxes in relation with cell Ca2+ homeostasis in the human placental trophoblast cell line BeWo. Time‐courses of Ca2+ uptake by BeWo cells displayed rapid initial entry (initial velocity (Vi) of 3.42 ± 0.35 nmol/mg protein/min) and subsequent establishment of a plateau. Ca2+ efflux studies with 45Ca2+‐loaded cells also showed rapid declined of cell‐associated 45Ca2+ with a Vi of efflux (Vei) of 3.30 ± 0.08 nmol/mg protein/min. Further identification of membrane gates for Ca2+ entry in BeWo cells was carried out. Expression of Ca2+ transporter/channel CaT1 and L‐type α1S subunit was showed by RT‐PCR. However, mRNA for CaT2 channel and L‐type α1C and α1D subunits were not revealed. Membrane systems responsible for intracellular Ca2+ extrusion from BeWo cells were also investigated. Plasma membrane Ca2+‐ATPases (PMCA) and Na/Ca exchangers (NCX) were detected by Western blot in BeWo cells. Expression of specific isoforms of PMCA and NCX was further investigated by RT‐PCR. Messenger RNAs of four isoforms of PMCA (PMCA 1–4) were detected. The presence of messenger RNAs of two NCX isoforms (NCX1 and NCX3) was observed. Ca2+ flux studies in Na‐free incubation medium indicated that NCX played a minimal role in the cell Ca2+ fluxes. Inorganic ions such as cadmium and manganese did not modify the Ca2+ fluxes, however, barium increased cell‐associated 45Ca2+ by, in part, by reducing radiolabel exit. Mol. Reprod. Dev. 64: 189–198, 2003. © 2003 Wiley‐Liss, Inc.
Detection of DNA damage in bovine metaphase II oocytes resulting from cryopreservation
Authors: Men H. , Monson R.L. , Parrish J.J. , Rutledge J.J. 
Published: December 2002

AbstractDevelopmental competence of mammalian oocytes is compromised by currently available oocyte cryopreservation protocols. Experiments were designed to examine the effect of three cryopreservation protocols on the integrity of bovine oocyte DNA. In vitro matured bovine oocytes were cryopreserved either by slow cooling, vitrification in 0.25 ml straws, or in open pulled straws. After thawing/warming, recovered oocytes were immediately subjected to morphological evaluation. Morphologically intact oocytes underwent comet assay to detect cryoinjury at DNA level. All cryopreservation protocols resulted in significant morphological damage as well as DNA damage compared to unfrozen control. Among the morphologically intact oocytes, there was no difference among protocols in the number of oocytes displaying DNA damage. However, oocytes that had been cryopreserved by slow cooling or by vitrification in open pulled straws exhibited more damage than those vitrified in 0.25 ml straws in the extent of DNA damage. If we combine the number of oocytes with morphological damage and oocytes with DNA damage, oocytes cooled by slow cooling resulted in the most damage. This experiment demonstrated that oocyte DNA is a target of cryoinjury and different protocols result in different degrees of damage. Mol. Reprod. Dev. 64: 245–250, 2003. © 2003 Wiley‐Liss, Inc.
Intrathecal methylprednisolone does not improve outcome after severe spinal cord injury in the rat
Authors: Vanický Ivo , Urdzíková Lucia , Saganová Kamila , Mars̆ala Martin 
Published: December 2002

AbstractIn a rat model of spinal cord compression‐induced injury, we have tested the hypothesis that intrathecally administered methylprednisolone will improve long‐term recovery of the injured rats. The effect of the treatment was evaluated quantitatively as 1, behavioral testing of spontaneous locomotion and 2, morphometric measurement of the tissue loss in the white matter and grey matter, respectively. Intrathecal methylprednisolone elicited remarkable motor reactions in the paraplegic animals immediately after administration. However, during 4 weeks' survival, no significant differences were observed in the parameters of recovery between the methylprednisolone‐treated and placebo‐treated group. We conclude that intrathecal administration of methylprednisolone had no effect on the outcome after compressive spinal cord injury in the rat at the doses and timing used in the present study.
Stimulation of Ca2+/Mg2+‐ATPase activity in adult rat cerebrocortical synaptosomes by 3‐5‐3′‐L‐triiodothyronine
Authors: Chakrabarti Nilkanta , Ray Arun K. 
Published: December 2002

AbstractStimulation of the calcium‐stimulated and magnesium‐dependent adenosine triphosphatase (Ca2+/Mg2+‐ATPase) activity by 3‐5‐3′‐L‐triiodothyronine (T3) in synaptosomes prepared from adult rat cerebral cortex was demonstrated both in vitro and in vivo. T3 stimulated the Ca2+/Mg2+‐ATPase activity in time dependent and dose dependent manner to depolarization‐induced synaptosomes suspended in Ca2+‐loaded choline‐chloride buffer, represented involvement of the recovery phase of the changes in intrasynaptosomal Ca2+ level in this activation. T3 (100nM) also stimulated the enzyme activity in nondepolarized intact synaptosomes suspended in choline‐chloride buffer. T3 had direct and dose‐dependent stimulatory effect on the Ca2+/Mg2+‐ATPase activity of the lysed synaptosomal suspension. The effect of T3 on the lysed synaptosomes was higher than that found on the nondepolarized intact synaptosomes. The condition probably represents the direct and/or indirect interaction of T3 with the enzyme through plasmamembrane related phenomenon that needs further investigation. After T3 treatment, a dose‐dependent activation of the enzyme was found in vivo. It appears that T3 plays a role on adult brain neuronal Ca2+‐mobilization through stimulation of the Ca2+/Mg2+‐ATPase activity in nerve terminals.
In‐Situ Determination of the Charging of Nanometer and Submicron Particles at High Temperatures
Authors: Schiel Annette , Weber Alfred P. , Kasper Gerhard , Schmid Hans‐Joachim 
Published: December 2002

AbstractThermal charging of submicron and nanometer particles has been studied for model aerosols of TiO2 and SiO2 as well as Al‐Si (aluminosilicate) at 1 000 °C with a new quasi in‐situ technique. The size dependence of the particle separation efficiency for electrostatic precipitation was determined. The charging state of the particles was obtained from evaluating the global Deutsch number for precipitation in an electric field applied to a laminar flow based on particle trajectory considerations.
2,2‐Dinitro‐1,3‐Bis‐Nitrooxy‐Propane (NPN): A New Energetic Plasticizer
Authors: Wingborg Niklas , Eldsäter Carina 
Published: December 2002

AbstractA new energetic plasticizer, 2,2‐dinitro‐1,3‐bis‐nitrooxy‐propane (NPN), has been characterized. Its high oxygen balance, +12.5%, and low glass transition temperature, −81.5 °C (midpoint), makes it very attractive as an energetic plasticizer in solid propellants. The ability of NPN to lower the glass transition temperature and viscosity of uncured PolyNIMMO has been studied and compared to other energetic plasticizers, such as BDNPA/F and butyl‐NENA. NPN has a similar plasticizing effect as butyl‐NENA, both on depressing the glass transition temperature and lowering the viscosity. To increase the poor thermal stability of NPN, several conventional nitrocellulose/nitroglycerine stabilizers were evaluated. Further work is however needed to find a more effective stabilizer.
The Incompatibility of RDX and Lead
Authors: Bellamy Anthony J. , Dearing Susannah L. 
Published: December 2002

AbstractAccelerated ageing at 100 °C of mixtures of RHA (RDX + 6% HMX) and lead has demonstrated that these components are incompatible. The rate of reaction to give N2O, hexamine and triazine was shown to be dependent upon the particle size of the lead, and pressing pressure for discs of these mixtures. In some cases there was more hexamine than RDX after 320 h at 100 °C. It is suggested that the preparation of the sample for the standard vacuum stability test (compatibility test) should be modified, using particles of explosive and nonexplosive of comparable size, and possibly even pressing, in order to simulate the conditions present in operating systems.
Optical properties of Si‐, Ge‐ and Sn‐doped GaN
Authors: Shikanaia A. , Fukahori H. , Kawakami Y. , Hazu K. , Sota T. , Mitani T. , Mukai T. , Fujita Sg. 
Published: December 2002

AbstractPhotoluminescence and reflectance spectra of Si‐, Ge‐ and Sn‐doped GaN epilayers grown on sapphire substrates at 10 K have been investigated, by which ionization energies on the Ga site were determined as 29, 30 and 33 meV, respectively. To investigate the coherent properties of excitons, the dephasing times of excitons in undoped and Si‐doped GaN on sapphire substrates and freestanding GaN were measured using the degenerate four‐wave mixing technique. The resulting homogeneous broadenings in undoped and Si‐doped GaN on sapphire substrates were about twice as large as that in freestanding GaN, which indicates that defect‐induced scattering is stronger in the former than in the latter.
Picosecond time‐resolved studies of excited state lifetime of Be acceptor in GaAs/AlAs multiple quantum wells
Authors: Zheng W.‐M. , Halsall M. P. , Harrison P. , Wells J.‐P. R. , Bradley I. V. , Steer M. J. 
Published: December 2002

AbstractThe influence of the quantum well potential on the carrier dynamics of holes bound to the acceptors in Be δ‐doped AlAs/GaAs multiple quantum wells is investigated by far‐infrared time‐resolved spectroscopy using the Free‐Electron Laser for Infrared eXperiments (FELIX). The lifetime of the 2p excited state of acceptors was measured as a function of the width of the quantum well and the temperature. It is found that the lifetime decreases monotonically with decreasing well width and is independent of temperature. We suggest that the relaxation process of the 2p → 1s is non‐radiative and mediated via confined acoustic phonon modes, in particular, zone‐folded acoustic phonon modes which arise from the periodic nature of the multiple quantum well samples. For one particular well width the lifetime was measured across the inhomogeneously broadened D‐line as 30, 30, 70, and 105 ps for 43, 44, 46, and 47 μm wavelengths, respectively. We believe the latter is due to diffusion of the Be δ‐doped atomic layer in the quantum wells.
Conductivity via impurities in low‐doped uncompensated silicon
Authors: Melnikov A. P. 
Published: December 2002

AbstractIt was found that in low‐doped silicon crystals (2 × 1016 < N < 1017 cm–3) with compensation rate decrease (10–5 < K < 10–2) the experimental results differ from the theoretical ones. At low electric fields (E) this concerns the values of the activation energy (ε3) and the dependence of ε3 on N and K. The results are explained by the influence of neutral impurity interaction on the density of states. With increasing E a previously unknown conductivity (σM) appears. The dependence of σM on N, K, E, magnetic field (H), and temperature (T) is quite different from the dependence that is usual for σ3 conductivity. The results are explained by the appearance of conductivity via H?‐like states of impurities, which are concentrated in the vicinity of edge dislocations.
Far‐infrared spectroscopy of shallow acceptors in semi‐insulating GaAs: evidence for defect interactions with EL2
Authors: Alt H. Ch. , Gomeniuk Y. , Kretzer U. 
Published: December 2002

AbstractFar‐infrared FTIR absorption measurements are carried out at 10 K in order to assess the uncompensated fraction of shallow acceptors in semi‐insulating GaAs after optical bleaching of EL2. In carbon‐doped material a linear correlation of the G line at 122.3 cm–1 with the CAs concentration is found in the whole concentration range between 1 × 1014 and 2 × 1016 cm–3. In samples co‐doped with zinc in the range around 1 × 1016 cm–3 and 1 to 2 × 1015 cm–3 carbon, both, ZnGa‐ and CAs‐related far‐infrared absorption lines are observed. Taking into consideration the Fermi level position after bleaching of EL2, it can be concluded that no other donors than EL2 are present above a total concentration of 1 × 1015 cm–3. In addition to the far‐infrared measurements, the intracentre transition of EL2 (A1 → T2) at 1.0389 eV is studied. The results are compatible only with an increase of the total EL2 concentration with the shallow acceptor concentration. Possible mechanisms for the interaction between shallow‐ and deep‐level defects are discussed.
Study of IR absorption and photoconductivity spectra of thermal double donors in silicon
Authors: Andreev B. A. , Emtsev V. V. , Kryzhkov D. I. , Kuritsyn D. I. , Shmagin V. B. 
Published: December 2002

AbstractThe IR absorption and photoconductivity spectra of a double donor (TDD) family with ionization energies less than 70 meV in silicon were investigated using Fourier transform spectroscopy with a resolution down to 0.25 cm–1. The values of line frequencies, widths, splitting and absorption cross sections for transitions from the ground to p‐states (including high‐excited states) were obtained. Determination of absorption cross sections was made using Hall data and concerted changes of boron and TDDi concentrations caused by neutralization of impurities under band gap illumination.
N‐type (P, Sb) and p‐type (B) doping of hydrogenated amorphous Si by reactive rf co‐sputtering
Authors: Ohmura Y. , Takahashi M. , Suzuki M. , Emura A. , Sakamoto N. , Meguro T. , Yamamoto Y. 
Published: December 2002

AbstractB, P or Sb were doped into amorphous silicon films by the reactive radio‐frequency co‐sputtering method. The targets used were composed of silicon wafers and small about 1 mm thick chips of the respective impurity element, which were attached to the silicon wafers with silver powder cement and epoxy resins. Argon and hydrogen partial pressures used were 5 × 10–3 and 5 × 10–4 torr, respectively. The impurity concentration in the film was determined by secondary ion mass spectroscopy for B and P and by He backscattering spectroscopy for Sb. The substrates were kept at 200–250 °C during deposition. Raman spectra revealed that films prepared even at 250 °C were amorphous. Heterostructures, where P‐, Sb‐ or B‐doped films were deposited on p‐ or n‐type Si, exhibited good rectification characteristics of n diodes. It has been shown that the co‐sputtering method can produce low‐resistivity p‐type (B) and n‐type (P) a‐SH films for relatively low concentrations of B and P, respectively.