bluuebunny/crossref_metadata_2025 huggingface dataset:
Beobachtungen Kleiner Planeten. XI
Authors: Börngen F. , Schmadel L. D.
Published: July 2007

Es wird eine Übersicht gegeben über die im Jahr 1990 auf Tautenburger Schmidtplatten gefundenen Kleinen Planeten. Es wurden 561 Objekte beobachtet und für diese 2104 Positionen gerechnet. Es handelt sich um 430 Planetoiden mit provisorischer Bezeichnung, unter denen 364 neu vergebene Bezeichnungen sind, sowie um 131 numerierte Objekte. Für 160 Tautenburger Objekte wurden erste Bahnen gerechnet. Für 49 im Berichtszeitraum numerierte Planeten haben Tautenburger Positionen einen Beitrag geleistet. Darunter sind sechs in Tautenburg entdeckte Planetoiden (Tab. 3).
Density profiles and luminosity functions of the globular clusters M3 and M92
Authors: Scholz R.‐D. , Schmidt K.‐H.
Published: July 2007

Tautenburg Schmidt plates with the globular clusters M3 and M92 were measured on the APM facility in Cambridge, mainly for astrometric purposes. The data were used to derive the radial density profiles and the luminosity functions of these clusters. There is a good agreement of our results with formerly ones derived by other authors. In both clusters effects of mass segregation are observed.
Orbits of galactic globular clusters
Authors: Odenkirchen M. , Brosche P.
Published: July 2007

New absolute proper motions of the two globular clusters NGC 4147 and NGC 6218 and a specific model of galactic mass distribution are used to integrate their orbits numerically. The resulting values of orbital parameters and their variation due to the uncertainty of the initial values are discussed. Furthermore, the deviations from the time average of the virial theorem are determined.
Orbits of the visual double stars W.D.S. 03537N5317, 11468N4839 and 14138N3100
Authors: Ling J. F.
Published: July 2007

New orbital elements are presented for the visual double stars W.D.S. 03537N5317, 11468N4839, and 14138N3100. The observations, residuals, ephemerides, dynamical parallaxes, and total masses of each system are also given.
On a two‐body problem with periodically changing equivalent gravitational parameter
Authors: Şaru D. , Cucu‐Dumitrescu C. , Mioc V.
Published: July 2007

Assigning to the equivalent gravitational parameter of a two‐body dynamic system, a periodic change of a small amplitude B and arbitrary frequency and phase, the behaviour of an elliptic‐type orbit is studied. The first order (in B) perturbations of the orbital elements are determined by using Delaunay's canonical variables. According to the value of the ratio between oscillation frequency and dynamic frequency, three cases (non‐resonant (NR), quasi‐resonant (QR), and resonant (R) ones) are pointed out. The solution of motion equations shows that only in the QR and R cases there are elements (argument of pericentre and mean anomaly) affected by secular perturbations. The solutions are valid over prediction times of order of pericentre and mean anomaly) affected by secular perturbations. The solutions are valid over prediction times of order B−1 in the NR case and B−1/2 in the QR and R cases.
Beobachtungen Kleiner Planeten. XII
Authors: Börngen F. , Schmadel L. D.
Published: July 2007

Es wird eine Übersicht gegeben über die im Jahr 1991 auf Tautenburger Schmidtplatten gefundenen Kleinen Planeten. Es wurden 533 Objekte beobachtet und für diese 2066 Positionen gerechnet. Es handelt sich um 456 Planetoiden mit provisorischer Bezeichnung, unter denen 324 neu vergebene Bezeichnungen sind, sowie um 77 numerierte Objekte. Für Tautenburger Objekte wurden 250 Bahnen aus einer Opposition gerechnet. Für 54 im Berichtszeitraum numerierte Planeten, darunter befinden sich auch (4999) MPC und (5000) IAU, haben Tautenburger Positionen einen Beitrag geleistet. Neun Tautenburger Planetoiden wurden numeriert (Tab. 3).

A summary is given about the Minor Planet survey performed in 1991 on Tautenburg Schmidt plates. 533 asteroids were observed and 2066 positions are calculated for them. These are 456 asteroids with provisional designations (324 of them have new designations) and 77 numbered objects. One‐opposition orbits have been computed for 250 Teutenburg asteroids. Tautenburg observations could give a tribute to 54 planets numbered in the period of this report, among them are (4999) MPC and (5000) IAU, too. Nine Tautenburg asteroids have been numbered (Tab. 3).
Nearby galaxies. II. Luminosity function and spatial distribution
Authors: Schmidt K.‐H. , Boller T.
Published: July 2007

A sample of nearby galaxies (Schmidt and Boller 1992, paper I) has been analysed with regard to the luminosity function and the spatial distribution. The main results are as follows: (i) a relation between the slope of the luminosity function of the members of a group of galaxies and the earliest morphological type in this group has been detected which possibly is a new kind of environmental effects; (ii) the virial masses of the groups of galaxies are, on the average, by a factor 3 to 4 greater, only, than the luminous masses derived from the individual galaxy masses; (iii) the nearby galaxies are concentrated in a thin disk‐like layer around the supergalactic plane the thickness of which is a few hundred kiloparsecs, only; (iv) a population of field galaxies with nearly constant density (about 3 per cent of the number density in the supergalactic plane) is extended into the voids on both the supergalactic hemispheres.
Determination of the optical or physical nature of wird visual binaries by means of two‐dimensional conditional probabilities
Authors: Brosche P. , Denis‐Karafistan A. , Denis C.
Published: July 2007

A sample consisting of 888 wide visual double stars with known relative proper motions has been processed for the HIPPARCOS input catalogue. Brosche et al. (1992) applied two separate criteria on this list to discriminate statistically between physical and optical pairs. The first of these criteria uses the number density constrast, the second the ratio of the tangential velocity to an estimate of the orbital velocity, assuming the pair to be physical. Here we combine these two separate criteria into a single criterion based on a probability depending on two arguments, i.e. on a conditional probability. Statistically, we are thus led to the conclusion that the sample comprises 545 physical and 343 optical pairs.
The spectrum of Pleione during 1990
Authors: Menchenkova E. V.
Published: July 2007

The results of the observations of Pleione obtained during 1990 with the 6‐m‐telescope SAO (Zelenchukskaja) and the 2.6‐m‐telescope of the Crimean Astronomical Observatory are presented. The spectral type of the star was B8. Variations of the equivalent widths and profiles of the hydrogen lines in the spectrum of Pleione during 1990 were detected. Lines of a secondary component in the spectrum of Pleione were not discovered.
Vilnius photometry of the red horizontal branch stars in the Galactic thick disk
Authors: Tautvaiśienė G.
Published: July 2007

The photometric observations and three‐dimensional classification in the Vilnius system have been carried out for 13 of the red horizontal branch (RHB) stars in the Galactic thick disk identified by Rose (1985). The photometric spectral types, metallicities [Fe/H], effective temperatures, surface gravities and absolute magnitudes are determined. The age of about 10–12 Gyr is evaluated for this group of stars from comparison with model isochrones, indicating that the age of the thick disk is intermediate between the disk globular and the oldest open clusters.
A new family of non‐linear filters for background subtraction of wide‐field surveys
Authors: Shergin V. S. , Kniazev A. Yu. , Lipovetsky V. A.
Published: July 2007

In this paper the definitions and properties of a newly dedicated set of high‐frequency filters based on smoothing‐and‐clipping are briefly described. New applications for the reduction of wide‐field 2048x2048 CCD spectral and direct images of a new deep survey KISS are also presented.
Catalogue of Shakhbazian compact groups of galaxies. VI.
Authors: Stoll D. , Tiersch H. , Braun M.
Published: July 2007

The sixth part of the catalogue of Shakhbazian compact groups of galaxies contains the positions and references of all the galaxies of the following 48 groups (north of δ > +2°30''): Shkh 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107. For the estimation of the coordinates the Digitized Sky Survey was used.
Some ideas concerning the problem of anomalous polar E region heating due to Farley‐Buneman turbulence
Authors: Liperovsky V. A. , Kustov A. V. , Meister C.‐V.
Published: July 2007

The energetics of the excitation of the Farley‐Buneman instability is considered, which is recently observed in the auroral and equatorial E regions of the Earth's ionosphere at altitudes between 100 km and 120 km. In the magnetic field of the Earth the Farley‐Buneman instability is excited under the condition of a strong enough external electric field in the case of ion‐neutral collisions with frequencies much larger than the ion gyrofrequency and electron‐neutral collisions with frequencies much below the electron gyrofrequency. It is shown that the linear increase of the wave amplitudes is caused by a small disbalance between the processes of nonlinear energy pumping into the wave from an external electric field and the energy loss because of the collisions of the electrons and ions with the neutral particles. During the nonlinear energy pumping energy of the external electric field is transferred into a nonlinear current of second order, which is connected with the oscillating motion of the electrons in the wave. The oscillating electron motion takes place perpendicular to wave propagation. From the estimations follows that the energy pumped into a Farley‐Buneman wave during one period of pulsation is much larger than the wave energy itself. A new and simply to understand derivation of the anomalous diffusion coefficient is presented, related to the study of the behaviour of a test wave with frequency much above the frequencies of the Farley‐Buneman turbulence in developed stage can cause an additional macroscopic nonlinear Pedersen current directed along the external electric field. It is found that the nonlinear Pedersen current can reach the order of the usual Pedersen current and should contribute to the effective heating of the ionospheric plasma.
The most resonant pulsation frequency of δ Scuti stars
Authors: Kotov S. V. , Kotov V. A.
Published: July 2007

Pulsation of the Sun with a period of P0 ≈ 160 min discovered about two decades ago, is still waiting explanation. In view of the hypothesis about its cosmological origin, and attempting to find signature of this P0 periodicity among other (short‐period variable) stars, the pulsation frequencies of δ Sct stars are subjected to specific analysis. With a confidence level ≈ 3.8σ it is found that the frequency v0 = P0−1 ≈ 104 m̈Hz, within the error limits, appears indeed to be the most “resonant” one for the total sample of 318 pulsating stars of δ Sct type (the most commensurable, or “synchronizing”, period for all these stars occurs to be 162 ± 4 min). We conjecture that a) the P0 oscillation might be connected with periodic fluctuations of gravity field (metrics), and b) the primary excitation mechanism of pulsations of δ Sct stars, reffected by this “ubiquitous” P0 resonance, must be attributed perhaps to superfast rotation of their inner cores (their rates tend to be in near‐resonance with the “universal” v0 frequency). The arguments are given favouring a cosmoogical nature of the P0 oscillation.
UBV photometry of the WR binary CQ Cephei
Authors: Demircan O. , Ak H. , Özdemir S. , Tanriver M. , Albayrak B.
Published: July 2007

Photoelectric observations of the WR binary CQ Cephei (WN6+O9) are presented. the depths of the eclipses in the light curves are best represented by an inclination of the orbit i = (68°.8±0.6) and the width of the very asymmetric eclipse curves can be represented by only an overcontact configuration (Ω1 = Ω2 = 3.65 ± 0.05, and f = 27%). Simultaneous solution of the light and radial velocity curves strongly supports CQ Cep's membership of the Cep OB1 association. By considering this membership we obtained absolute dimensions of the system, which lead to a consistent physical model for CQ Cephei. The more luminous WR primary turns out to be the hotter but slightly less massive component: MWR = 20.8 M⊙, RWR = 8.2R⊙, Teff(WR) = 43600 K, and Mo = 21.4 M⊙, Ro = 8.3 R⊙, Teff(O) = 37000 K.
The slender solar tachocline: a magnetic model
Authors: Rüdiger G. , Kitchatinov L. L.
Published: July 2007

A model for the sharp transition from differential rotation in the solar convection zone to rigid rotation in the radiative interior is presented. Differential rotation in the radiative zone is shown to be quenched efficiently by an internal magnetic field. The poloidal field amplitude, B0, is the input parameter for our model which determines the transition layer thickness and the toroidal field strength. It is illustrated analytically and confirmed numerically that a rather small field, B0 = 10−4 Gauss, suffices to satisfy the helioseismological restrictions on the depth of the differential rotation penetration below the convection zone. The transition layer thickness decreases further with increasing B0. The toroidal field amplitude B ≃ 200 Gauss is almost independent of B0.
The AGN content of ROSAT and ASCA deep surveys
Authors: Griffiths R. E. , Boyle B. J. , Georgantopoulos I. , Shanks T. , Gunn K. , Stewart G. C. , Blair A. , Almaini O.
Published: July 2007

The results of ROSAT deep surveys were well established during the first few years of ROSAT operation (Papers I ‐ XV in this collaboration, and other papers in this Volume). They have allowed us to measure the AGN Luminosity Function and its evolution in soft X‐rays, both for AGN of Type I and for objects classified as AGN Type II/Narrow‐Line X‐ray Galaxy (NXLG). More recently, we have performep surveys with ASCA of some of these same ROSAT fields. Based on coincidences with ROSAT deep survey sources, and further optical spectroscopic identification, we discuss the optical identification content of five of our ASCA deep survey fields. Perhaps not surprisingly, we have observed significant cosmological evolution for Type I AGN in the 2–10 keV energy range, with an evolutionary rate which is consistent with that measured in other passbands. The predicted contribution of Type I AGN to the 2–10 keV X‐ray background (XRB) is about 60%, and the combined contribution from AGN of Types I & II is consistent with 100%.
Sky surveys with ASCA — Large Sky Survey
Authors: Ueda Y. , Takahashi T. , Inoue H. , Tsuru T. , Sakano M. , Ohta K. , Akiyama M. , Ishisaki Y. , Ogasaka Y. , Makishima K. , Yamada T.
Published: July 2007

We have carried out the first systematic wide‐area survey around a Galactic pole region with the ASCA satellite in the 0.7–10 keV energy band (Large Sky Survey; LSS). The observed area amounts to 7 deg2. To make the best use of ASCA capability, we have developed a new source‐detection method where the complicated detector responses are fully taken into account. Applying this method to the entire LSS data independently in three energy bands (0.7–2 keV, 2–10 keV, and 0.7‐7 keV), we detected 104 sources in total (4.5 σ detection). The Log N ‐ Log S relation and spectral properties of faint sources are presented.
The UK ROSAT Deep Survey
Authors: McHardy I. M. , Merrified M. R. , Newsam A. M. , Jones L. R. , Allan D. J. , Ponman T. J. , Mason K. O. , Smith P. J. , Branduardi‐Raymont G. , Carrera F. , Abraham R. G. , Dalton G. B. , Efstathiou G. , Rowan‐Robinson M. , Quenby J. J. , Wegner G. A. , Lehto H. J. , Luppino G. A.
Published: July 2007

We present a summary of the identification content of the UK ROSAT Deep Survey. The survey is based on a 115ksec PSPC observation and comprises a sample of 70 sources to a flux limit of 2 × 10−15 ergs cm−2 s−1 (0.5–2 keV). At bright fluxes the survey is dominated by broad line QSOs, at intermediate fluxes it contains a number of groups and clusters of galaxies, but at faint fluxes the survey contains many galaxies with narrow optical emission lines (NELGs). The average X‐ray spectrum of the NELGs is harder than that of the QSOs and similar to that of the X‐ray background. The NELGs have optical spectra similar to the majority of the field galaxy population in the same redshift range and may simply be the more luminous members of the emission line field galaxy population. Based on optical line ratios and X‐ray/optical ratios, the NELGs, both as a sample and within individual galaxies, appear to be a mixture of starburst galaxies and true AGN.
Results from the ROSAT Deep Cluster Survey
Authors: Rosati P.
Published: July 2007

Deep X‐ray surveys of galaxy clusters covering large solid angles offer ideal samples for studying the evolution of the large scale structure in the Universe. I review here some recent results from the ROSAT Deep Cluster Survey (RDCS), particularly, on the study of the evolution of the abundance of galaxy clusters over a large redshift range. The optical identification of RDCS sources have revealed a significant fraction of clusters at >z > 0.5. The observed X‐ray Luminosity Function out to z ⋍ 0.8 and the faint cluster number counts from the RDCS, when combined with previous results of the Einstein Extended Medium Sensitivity Survey, provide a much improved observational picture of the evolution of clusters in the X‐ray band, revealing a slowly evolving population of galaxy clusters since at least z ⋍ 0.8. The theoretical interpretation of these findings in the framework of theories of structure formation will still be subject of much debate in the years to come. The construction of large samples of clusters out to z ∽ 1 and beyond appears to be a challenging task even with the next generation of X‐ray satellites (AXAF, XMM).
ABRIXAS — A BRoad‐band Imaging X‐ray All‐sky Survey
Authors: Trümper J. E. , Hasinger G. , Staubert R.
Published: July 2007

ABRIXAS is an X‐ray satellite with seven 27‐fold nested Wolter‐1 telescopes, sharing one pn‐CCD detector in the focus. It will be launched in spring of 1999. ABRIXAS will perform the first imaging all‐sky survey above 2 keV. During a three‐year scanning mission it is expected to detect at least 10.000 new hard X‐ray sources obscured by gas and dust clouds. It will also study large diffuse X‐ray sources and the time variability of bright X‐ray sources.
Operational capabilities of AXAF for surveys
Authors: Schwartz D. A.
Published: July 2007

The Advanced X‐ray Astrophysics Facility (AXAF) will offer us all great opportunities for surveys. The exceptional resolution of the AXAF mirrors, will yield unsurpassed deep surveys, and the energy resolution of the ACIS will allow unique contributions to the AXAF version of previous “medium sensitivity” and “slew” surveys. At this workshop we presented some preliminary results of the calibration of the AXAF flight mirrors. Off‐axis imaging, chromatic effects of vignetting, and the asymmetry of the off‐axis response will be important for planning and analyzing surveys.
Present Epoch Plus — an X‐ray survey for cosmology
Authors: Jahoda K.
Published: July 2007

This paper summarizes some cosmologically interesting measurements which are uniquely possible in the hard X‐ray band and presents a mission concept capable of achieving them. The Present Epoch Plus mission will achieve a surface brightness sensitivity of better than 1% per square degree in the 2–10 keV band, and create a catalog of ∽ 106 sources. About 160,000 extragalactic sources are expected to be detected in the 2–10 keV band, providing an all sky survey with nearly uniform selection effects 10 times deeper than existing or planned surveys. The PEP concept can be achieved within the size and budgetary constrraints of a NASA Medium Explorer (MIDEX) mission.
Surveying the hard X‐ray sky: imaging in space and time
Authors: Grindlay J. E.
Published: July 2007

One of the few remaining astronomical bands (factor of ∽ 10 in energy range) still without an all‐sky imaging survey is the hard x‐ray band (10–600 keV). This is in spite of sensitive imaging all‐ sky surveys already conducted at soft x‐ray (0.2‐2 keV; ROSAT) and soft/hard γ‐ray (∽750 keV ‐ 10 GeV; COMPTEL/EGRET) energies and imminent for medium x‐ray energies (2–10 keV; ABRIXAS). A hard x‐ray imaging survey conducted with wide‐field coded aperture telescopes allows both hight sensitivity (and spatial/spectral resolution) and broad temporal coverage. We derive a generalized survey sensitivity/temporal parameter, Q, and compare previous and planned hard x‐ray surveys with the proposed EXIST mission. Key scientific objectives that could be addressed with the enhanced capability of EXIST are outlined.
An AllNAG8–1212sky Survey for Tens of keV
Authors: Gruber D. E. , Matteson J. , Coburn W. , Heindl W. , Pelling M. , Peterson L. E. , Rothschild R. E. , Skelton T. , Hink P.
Published: July 2007

The HEXIS (High Energy X‐Ray Imaging Spectrometer) is a MIDEX‐class mission concept to perform a deep survey and continuous monitoring of nearly the entire sky in the 5–200 keV band. It uses arrays of position‐sensitive Cadmium‐Zinc Telluride (CZT) detectors and coded masks to achieve 26′ resolution and a 5 sigma sensitivity (> 20 keV) of 4 milliCrab in one day and 0.2 milliCrab in one year. With these capabilities it is estimated that ∽5000 sources can be discovered and localized and have their spectra and variability characterized. Hundreds of gamma‐ray bursts would be detected each year and localized to < 20′. HEXIS also contains a narrow field, 5°, coded mask imager for detailed studies of selected regions. This has three arc minute resolution and is seven times more sensitive than the all‐sky system. The HEXIS detector concept uses crossed strip readout to achieve 0.5 mm resolution pixels for large area arrays, ∽ 400 cm2. This technique is under development at UCSD and Washington University. Detectors have been studied with tuneable monochromatic x‐ray beams and mapped with finely collimated 30 micron beams. These results show that the crossed strip readout has the necessary spatial and spectral characteristics. The HEXIS concept is described and results are presented on the detectors' spatial and spectral properties.
A new X‐ray mission to measure the power spectrum of fluctuations in the Universe
Authors: Barcons X. , Fabian A. C.
Published: July 2007

We propose a new, simple, dedicated X‐ray mission to measure the power spectrum of density fluctuations in the Universe, by accurately mapping the X‐ray background on the whole sky on scales of ∽ 1 deg2. Since the method relies on the detection of excess fluctuations produced by the clustering of X‐ray sources at intermediate redshifts above the confusion noise produced by bright foreground sources, counting noise and systematic noise need to be kept to a minimum. We propose a proportional counter with collimated fields of view of various sizes as the optimal instrument for this mission.
Achievements and prospects for X‐ray astronomy
Authors: Giacconi R.
Published: July 2007

I have been asked to speak at this meeting on the past and future of X‐Ray Astronomy. In a brief summary I would like to recall only a few salient steps in the early developments of the field and engage in a few speculations on future trends.
Identification of new low‐mass members of the Alpha Persei open cluster by ROSAT. II
Authors: Prosser C. F. , Randich S. , Simon T.
Published: July 2007

The present investigation examines possible optical counterparts to 130 X‐ray sources in the region of the α Persei open cluster (d ∽ 170pc, age ∽ 50 Myr) resulting from the analysis of three 22–25 ksec ROSAT PSPC pointings. In the same manner as for 73 X‐ray sources from a raster survey in α Per (Prosser & Randich 1998), CCD photometry is employed to obtain magnitudes and colors for stars/objects close to the X‐ray positions, with additional echelle and low‐dispersion Hα spectra provided for some stars. For almost 60 X‐ray sources, an optical counterpart with photometry acceptable for cluster membership is identified, some of which can be excluded from membership on the basis of discrepant radial velocity or X‐ray characteristics. On the order of 30 new members or likely members associated with X‐ray sources have been identified based on available data. A photometric rotation period has been obtained for one rapid rotator identified in X‐rays.
The G‐dwarf problem in the solar neighbourhood: a Lagrangian picture. II
Authors: Caimmi R.
Published: July 2007

The current paper investigates how the empirical, G‐dwarf metallicity distribution constrains simple, comoving models of chemical evolution. In doing this, the application of the models to a data sample, performed in a previous paper, is refined and extended. The key idea is that (i) different star formation rates with different mass spectra take place in different phases of evolution, i.e. contraction and equilibrium, and (ii) disk formation begins at a time t = Td and ends at t = Tc, which marks the transition from contraction to equilibrium. In this view, the lowest‐metallicity point of the empirical, differential distribution, consistent with a linear fit, is related to the beginning of disk formation, and an apparent discontinuity point to the transition from contraction to equilibrium. In addition, different linear fits hold on the left (early distribution) and on the right (late distribution) of the discontinuity point. Models consistent with the empirical, G‐dwarf metallicity distribution are related to linear fits on the early and late side. Homologous solutions during the equilibrium phase are analysed in detail with respect to changes in Tc and Ta, the age of the Galaxy. Then we are left with a single free parameter which is relevant to the chemical evolution, i.e. the mass spectrum exponent during the equilibrium phase. The allowed values for the other parameters, thought as a function of the above mentioned one, are plotted for each case. A Salpeter mass spectrum exponent, p = −2.35, is ruled out by the theoretical, lower stellar mass limit, contrary to a Scalo mass spectrum exponent, p = −2.90, in contrast with previous literature. The reasons for this discrepancy are discussed. Our results are marginally consistent with a same initial mass function during the contraction and equilibrium phase, but in this case the disk mass fraction is of the is same order, or less, than the halo mass fraction. It is also investigated how the empirical age‐metallicity relation constrains the duration of the contraction phase, for a reasonable upper limit of Ta. Keeping in mind that the empirical, G‐dwarf metallicity distribution has not been corrected for the large cosmic scatter shown by the empirical, age‐metallicity relation, we find a duration of disk formation, Tc — Td = 1.07–1.5 Gyr, by a factor 3–5 less than it is found by use of simple infall models. The reasons of this difference are explained. The idea of a massive, white dwarf halo, which seems to be indicated by microlensing experiments, is ruled out by the empirical, G‐dwarf metallicity distribution, in the light of the current model and provided the solar neighbourhood is a typical region of the Galaxy. More refined models involving e.g., the relax of instantaneous recycling would change our results, but the trend is expected to be only slightly altered.
Further improvement of phosphite dehydrogenase thermostability by saturation mutagenesis
Authors: McLachlan Michael J. , Johannes Tyler W. , Zhao Huimin
Published: July 2007

Phosphite dehydrogenase represents a new enzymatic system for regenerating reduced nicotinamide cofactors for industrial biocatalysis. We previously engineered a variant of phosphite dehydrogenase with relaxed cofactor specificity and significantly increased activity and stability. Here we performed one round of random mutagenesis followed by comprehensive saturation mutagenesis to further improve the enzyme thermostability while maintaining its activity. Two new thermostabilizing mutations were identified. These, along with the 12 mutations previously identified, were subjected to saturation mutagenesis using the parent enzyme or the engineered thermostable variant 12× as a template, followed by screening of variants with increased thermostability. Of the 12 previously identified sites, 6 yielded new variants with improved stability over the parent enzyme. Several mutations were found to be context‐dependent. On the basis of molecular modeling and biochemical analysis, various mechanisms of thermostabilization were identified. Combining the most thermostabilizing mutation at each site resulted in a variant that showed a 100‐fold increase in half‐life at 62°C over the 12× mutant. The final mutant has improved the half‐life of thermal inactivation at 45°C by 23,000‐fold over the parent enzyme. The engineered phosphite dehydrogenase will be useful in NAD(P)H regeneration. Biotechnol. Bioeng. 2008;99: 268–274. © 2007 Wiley Periodicals, Inc.
Modeling of ferrous iron oxidation by a Leptospirillum ferrooxidans‐dominated chemostat culture
Authors: Sundkvist Jan‐Eric , Gahan Chandra Sekhar , Sandström Åke
Published: July 2007

The objective of this study was to evaluate a direct classical bioengineering approach to model data generated from continuous bio‐oxidation of Fe2+ by a Leptospirillum ferrooxidans‐dominated culture fed with either 9 g or 18 g Fe2+ L−1 under chemostat conditions (dilution rates were between 0.051 and 0.094 h−1). The basic Monod and Pirt equations have successfully been integrated in an overall mass balance procedure, which has not been previously presented in this detail for Fe2+ oxidation. To ensure chemostat conditions, it was found that the range of the dilution rates had to be limited. A too long retention time might cause starvation or non‐negligible death rate whereas, a too short retention time may cause a significant alteration in solution chemistry and culture composition. Modeling of the experimental data suggested that the kinetic‐ and yield parameters changed with the overall solution composition. However, for respective feed solutions only minor changes of ionic strength and chemical speciation can be expected within the studied range of dilution rates, which was confirmed by thermodynamic calculations and conductivity measurements. The presented model also suggests that the apparent Fe3+ inhibition on specific Fe2+ utilization rate was a direct consequence of the declining biomass yield on Fe2+ due to growth uncoupled Fe2+ oxidation when the dilution rate was decreased. The model suggested that the maintenance activities contributed up to 90% of the maximum specific Fe2+ utilization rate, which appears close to the critical dilution rate. Biotechnol. Bioeng. 2008;99: 378–389. © 2007 Wiley Periodicals, Inc.
Development of a minimal defined medium for recombinant human interleukin‐3 production by Streptomyces lividans 66
Authors: Nowruzi Keyvan , Elkamel Ali , Scharer Jeno M. , Cossar Doug , Moo‐Young Murray
Published: July 2007

A systematic approach was developed to identify and optimize the essential amino acids in defined minimal medium for the production of recombinant human interleukin 3 (rHuIL‐3) by Streptomyces lividans. Starvation trials were carried out initially to narrow down the number of probable essential amino acids from an initial number of 20 to 8. Then a screening mixture experiment was designed and performed with the eight identified amino acids and distance‐based multivariate analysis was employed to rank the probable essential amino acids regarding both growth and product formation. Following this procedure, the search was narrowed to four amino acids (Asp, Leu, Met, and Phe). Finally, a mixture design experiment known as the simplex lattice design was carried out and the composition of the optimum minimal medium was found (Asp 53%, Met 5%, and Phe 42%). Biotechnol. Bioeng. 2008;99: 214–222. © 2007 Wiley Periodicals, Inc.
Vibrational Study on the Local Structure of Post‐Synthesis and Hybrid Mesoporous Materials: Are There Fundamental Distinctions?
Authors: Vaz Pedro D. , Nunes Carla D. , Vasconcellos‐Dias Maria , Nolasco Mariela M. , Ribeiro‐Claro Paulo J. A. , Calhorda Maria José
Published: July 2007

Organic–inorganic mesoporous materials of the MCM‐41 type are important materials that can be prepared by either post‐synthesis or one‐pot synthesis procedures. A complete control of the characteristics at a local level is of the utmost importance in view of the applications of such materials. However, there are not many studies relating such features with synthetic approaches. In this work, we prepared samples by post‐synthesis derivatization of materials from Si‐based MCM‐41, with bidentate nitrogen ligands bearing one or two silylated arms, and by one‐pot synthesis of organic–inorganic hybrid materials. The bulk properties of the two kinds of materials were comparable. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and Raman spectroscopy were used to investigate the local environment, namely, the number of OH groups and distribution of SiO4 units (large and small ring units). Hydrophilicity correlates with both the type of organic moiety used (mono‐ or disilylated), as well as with the synthetic procedure. The same vibrational studies showed how the structure in the channels changes as a function of pressure, reflecting the low mechanical stability of the mesoporous materials.
Rare Earth‐Rich Magnesium Compounds Ln4RhMg (Ln: Y, La—Nd, Sm, Gd—Tm, Lu).
Authors: Tuncel Selcan , Rodewald Ute Ch. , Chevalier Bernard , Poettgen Rainer
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Au3SnP7@Black Phosphorus: An Easy Access to Black Phosphorus.
Authors: Lange Stefan , Schmidt Peer , Nilges Tom
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Wide Compositional and Structural Diversity in the System Tl/Bi/P/Q (Q: S, Se) and Observation of Vicinal P—Tl J Coupling in the Solid State.
Authors: Gave Matthew A. , Malliakas Christos D. , Weliky David P. , Kanatzidis Mercouri G.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
General Asymmetric Hydrogenation of α‐Branched Aromatic Ketones Catalyzed by TolBINAP/DMAPEN—Ruthenium(II) Complex.
Authors: Arai Noriyoshi , Ooka Hirohito , Azuma Keita , Yabuuchi Toshio , Kurono Nobuhito , Inoue Tsutomu , Ohkuma Takeshi
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
An Environmentally Benign System for Synthesis of β‐Hydroxylketones: L‐Histidine Asymmetrically Catalyzed Direct Aldol Reactions in Aqueous Micelle and Water‐Like Media.
Authors: Peng Yi‐Yuan , Peng Shu‐Jun , Ding Qiu‐Ping , Wang Qi , Cheng Jin‐Pei
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Ytterbium Triflate Catalyzed Synthesis of β‐Enaminones.
Authors: Epifano Francesco , Genovese Salvatore , Curini Massimo
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Environmentally Benign N‐Boc Protection under Solvent‐ and Catalyst‐Free Conditions.
Authors: Jia Xueshun , Huang Qing , Li Jian , Li Shaoyu , Yang Qiushi
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A Fast and Convenient Heck Reaction in Water under Microwave Irradiation.
Authors: Zhu Min , Song Yunlong , Cao Yan
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis of γ‐Amino Acid Esters by 1,4‐Addition of Deprotonated α‐Aminonitriles and α‐(Alkylideneamino)nitriles to α,β‐Unsaturated Esters.
Authors: Bergner Ines , Opatz Till
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Diastereoselective Synthesis of Spiro‐β‐lactams via Staudinger Reaction.
Authors: Rojas‐Lima Susana , Santillan‐Sid Lidia , Lopez‐Ruiz Heraclio , Alvarez‐Hernandez Alejandro
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis of Alkylidenephthalans Through Fluoride‐Induced Cyclization of Electron‐Deficient 2‐Siloxymethylphenylacetylene Derivatives.
Authors: Duan Shaofeng , Cress Karen , Waynant Kris , Ramos‐Miranda Elias , Herndon James W.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Chemoselective One‐Pot Conversion of Primary Alcohols to Their Bis(indolyl)methanes Promoted by Bi(NO3)3×5H2O.
Authors: Khosropour Ahmad R. , Mohammadpoor‐Baltork Iraj , Khodaei Mohammad M. , Ghanbary Parvin
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
1,2,3‐Thiadiazole Substituted Pyrazolones as Potent KDR/VEGFR‐2 Kinase Inhibitors.
Authors: Tripathy Rabindranath , Ghose Arup , Singh Jasbir , Bacon Edward R. , Angeles Thelma S. , Yang Shi X. , Albom Mark S. , Aimone Lisa D. , Herman Joseph L. , Mallamo John P.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis of Lactams by Radical Substitution Reaction of α,β‐Unsaturated Acyl Radicals at Amine Nitrogen.
Authors: Uenoyama Yoshitaka , Fukuyama Takahide , Ryu Ilhyong
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis of Novel Functionalized Derivatives of 5‐Nitro‐3,4‐dihydropyrimidin‐2(1H)‐one by the Cyclocondensation of 1‐Chlorobenzyl Isocyanates with N,S‐ and N,N‐Nitroketeneacetals.
Authors: Sukach Volodymyr A. , Bol'but Andriy V. , Petin Alexander Yu. , Vovk Mykhaylo V.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Orally Active 4‐Amino‐5‐diarylurea‐furo[2,3‐d]pyrimidine Derivatives as Antiangiogenic Agent Inhibiting VEGFR2 and Tie‐2.
Authors: Miyazaki Yasushi , et al. et al.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis of Novel Heterocyclic System — Imidazo[5,1‐b][1,3]benzoxazine.
Authors: Osyanin V. A. , Sidorina N. E.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
New Thermal Rearrangement of 2,4,6‐Triarylthio(seleno)pyrylium Salts.
Authors: Drevko B. I. , Suchkova E. V. , Baranchikova G. A. , Mandych V. G.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A New Antifeedant Withanolide from Jaborosa lanigera.
Authors: Tettamanzi M. Cristina , Biurrun Fernando N. , Cirigliano Adriana M.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Sulfone‐Mediated Total Synthesis of (.+‐.)‐Lepadiformine (I).
Authors: Caldwell John J. , Craig Donald
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Daphlongeramine A, Novel Daphniphyllum Alkaloid from Daphniphyllum longeracemosum.
Authors: Li Chunshun , He Hongping , Di Yingtong , Wang Yuehu , Mu Shuzhen , Li Shunlin , Gao Suo , Gao Zhulin , Hao Xiaojiang
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis of a 9‐Aza Analogue of Eleutherol
Authors: Townsend Norman O. , Jackson Yvette A.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Monohydrocalcite and Its Relationship to Hydrated Amorphous Calcium Carbonate in Biominerals.
Authors: Neumann Markus , Epple Matthias
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Self‐Assembled Growth of PbTiO3 Nanoparticles into Microspheres and Bur‐like Structures.
Authors: Wang Guozhong , Saeterli Ragnhild , Roervik Per Martin , van Helvoort Antonius T. J. , Holmestad Randi , Grande Tor , Einarsrud Mari‐Ann
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Robust and Efficient Molecular Catalysts with a M‐O‐M′ Framework
Authors: Singh Sanjay , Roesky Herbert W.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthetic Routes to N‐Heterocyclic Carbene Complexes: Pyridine—Carbene Tautomerizations
Authors: Kunz Doris
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
o‐Aminomethyl Derivatives of Phenols. Part 1. Benzylamines: Properties, Structure, Synthesis and Purification
Authors: Bujnowski Krzysztof , Adamczyk Agnieszka , Synoradzki Ludwik
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Chromium(VI) Oxidants Having Quaternary Ammonium Ions: Studies on Synthetic Applications and Oxidation Kinetics
Authors: Patel Sabita , Mishra B. K.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Synthesis of Immunosuppressant FR901483 and Biogenetically Related TAN1251 Alkaloids
Authors: Bonjoch Josep , Diaba Faiza
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Supramolecular Chirality of Hydrogen‐Bonded Rosette Assemblies
Authors: Vazquez‐Campos Socorro , Crego‐Calama Mercedes , Reinhoudt David N.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
2′‐Deoxy‐4′‐C‐ethynyl‐2‐fluoroadenosine, a Nucleoside Reverse Transcriptase Inhibitor
Authors: Ohrui Hiroshi
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Phosphonium Salts and Phosphine Chalcogenides
Authors: Allen D. W.
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Ferrate(VI) Oxidation of Nitrogenous Compounds
Authors: Johnson Michael D. , Hornstein Brooks J. , Wischnewsky Jacob
Published: July 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Polymeric Actuators for Biological Applications
Authors: Pelah Avishay , Jovin Thomas M.
Published: July 2007

To shed light on the role of cell rheology and mechanotransduction in various physiological and disease states, different techniques of force application, such as optical tweezers and deformable substrates, are employed. In this present paper we describe a new approach for the deformation of cells based on the temperature‐sensitive polymer poly(N‐isopropylacrylamide), PNIPAM. In response to temperature changes, PNIPAM gels undergo extensive and reversible changes in volume that allow them to be used as actuators for stretching and compressing cells and tissues. Herein we focus mainly on our experience with the deformation of red blood cells as proof of principle, and demonstrate the wealth of possibilities such stimuli‐responsive materials may offer as actuators.
Spontaneous crystallization of sodium chloride from aqueous‐ethanol solutions; Part 3: Examination of a model of the crystallization process
Authors: Linnikov Oleg D.
Published: July 2007

In the present work the examination of the proposed earlier model of spontaneous crystallization process was done. The model describes kinetics of the crystallization process after the end of the induction period. To test the model the published data on crystallization and aggregation kinetics of sodium chloride at its spontaneous crystallization from supersaturated aqueous‐ethanol solutions were used. It was found an excellent coincidence of the experimental and theoretical data on concentration of the salt and the total number of crystals in solution at crystallization. The model allows predicting with satisfactory accuracy kinetics of crystallization using such general parameters of sodium chloride as the specific surface energy and the height of the nucleus‐bridges between crystals at coalescence. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)