bluuebunny/crossref_metadata_2025 huggingface dataset:
Kollineare Zentralkonfigurationen des n‐Körperproblems
Authors: D′Ambly Carl‐Günter
Published: June 2010

In der vorliegenden Arbeit wird untersucht, inwieweit sich zu vorgegebener Lage von n Massenpunkten auf einer Geraden die Größe der Massen so bestimmen läßt, daß eine Zentralkonfiguration entsteht. Dieses Problem wird auf die Lösung eines in den Massen linearen Gleichungssystems reduziert. Aus diesem System ergeben sich einerseits in Gestalt notwendiger Bedingungen für die Positivität der Massen gewisse Ordnungsrelationen für die gegenseitigen Abstände der Massenpunkte. Andererseits liefert die notwendige und hinreichende Lösbarkeitsbedingung des linearen Gleichungssystems eine algebraische Gleichung, der die Punktabstände genügen müssen. Tatsächlich liegt jedoch nur für die Fälle mit geradzahligem n eine Bedingung vor. Schließlich werden die Fälle n = 3 und n = 4 vollständig diskutiert.
Das interstellare Strahlungsfeld an verschiedenen Stellen im Milchstraßensystem
Authors: Zimmermann H.
Published: June 2010

Das interstellare Strahlungsfeld wird für drei verschiedene Stellen im Milchstraßensystem mit unterschiedlichem Abstand von der galaktischen Ebene bestimmt und mit dem für den Ort der Sonne neu berechneten Strahlungsfeld verglichen. Für die Sterne frühen Spektraltyps werden dabei neue Werte des Strahlungsstromes benutzt. Zur Herleitung werden neuere Sternatmosphärenmodelle und außerirdische Beobachtungen im kurzwelligen Spektralbereich verwendet.

Das neue Strahlungsfeld für den Ort der Sonne unterscheidet sich sowohl in der Gesamtenergiedichte als auch in deren spektraler Verteilung wesentlich von früheren Berechnungen und Abschätzungen. Dies ist auf die Verwendung anderer Werte für den stellaren Strahlungsstrom zurückzuführen.
Complex Segregation Analysis on Sib‐Pairs Data
Authors: Tai J. J. , Gross Alan J.
Published: June 2010

Using sib‐pairs and parent‐pairs data, a quantitative trait can be tested for the existence of a major locus under the mixed model of Morton and MacLean (1974). The basic idea is to obtain the two conditional likelihoods for sib‐pair differences and parent‐pair differences provided that it is known which sib‐pairs or parent‐pairs have the same effect at the major locus. Two conditions are introduced to obtain two recursive computer algorithms that distinguish the sib‐pairs or parent‐pairs having the same effect at the major locus. This method has the advantage of reducing complicated computations involving maximum likelihood estimates from nuclear families. A simulation experiment is performed to illustrate the method and its results are discussed.
A Comment on Maximum Likelihood Estimation for Finite Mixtures of Distributions
Authors: Burnham K. P.
Published: June 2010

Iterative numerical methods are necessary to find the maximum likelihood estimates for finite mixture distributions. This paper shows that it will often be possible to analytically reduce the number of equations that must ultimately be solved numerically. Such a reduction in dimensionality has not generally been used, or sought after, for mixture distributions. Yet such results are easily derived when each mixture component is assumed to be from the same parametric model within the exponential family.
Application of Multiple Test Procedures to the Combination of Multivariate and Univariate Tests with Varying Variable Sets
Authors: Kropf S.
Published: June 2010

The positive ascertainment of location differences in a multivariate comparison of two or more groups gives rise to the question for the contribution of the single variables or of subsets of variables to the multivariate difference. In this paper two methods are proposed to accomplish the original multivariate test by tests in variable subsets or in single variables using a closed test procedure and Holm's procedure, respectively. Both control the multiple level of the whole procedure.
Nonparametric Evaluations of Familial Aggregation
Authors: Chakraborty R.
Published: June 2010

Limitations of detection of familial aggregation, examined by nonparametric aggregate measures (e.g., SMR), or by parametric methods (e.g., segregation analysis) may involve: (1) heterogeneity of risk patterns in different kindreds, or (2) restricted choice of parametric models. Nonparametric approaches dealing with individual kindreds, on the contrary, involve sparce data for which large sample theory may not apply. When the expected risk schedules of individuals are known, some optimal test procedures may be developed. Nevertheless, the optimality criteria are shown to be satisfied for only restricted choice of alternatives, and large sample approximation are not warranted in analysis of individual kindreds. Truncations of points of entry and exit of individuals in the study are needed to avoid complications due to loss of followup, in presence of which expected risk calculations are not reliable.

Covariances of components of a goodness‐of‐fit test criterion detect specific modes of aggregation. It is illustrated that this test statistic is not always less powerful than the aggregate measures in detecting aggregation, and the covariances of its components partitioned by relative classes are in conformity with the results of segregation analysis.
Applications and Tabulations of the Multivariate t Distribution with ρ = 0
Authors: Rausch W. , Horn M.
Published: June 2010

Quantiles of the multivariate t distribution with ρ = 0 are tabulated. Some applications are discussed.
Parameter Estimation for the Compartmental Model
Authors: Sen P. , Srivastava R. C.
Published: June 2010

An estimation procedure is obtained for a stochastic compartmental model. Compartmental analysis assumes that a system may be divided into homogeneous components, or compartments. The main theory for the compartmental system was studied by Matis and Hartley (1971) with a discrete population in a steady state. All the transitions among the particles are considered to be stochastic in nature. An estimation procedure, Regular Best Asymptotic Normal (RBAN), discussed by Chiang (1956) is investigated for a stochastic m‐compartmental system. The detailed proof of the procedure is provided here. Asymptotic properties for the estimator has been studied and computation has been carried out on our proposed nonlinear model. The downhill simplex search method, originally developed by Nelder and Mead (1965), and applied to minimize our quadratic form is inherently nonlinear in nature, thus avoiding the need to evaluate any derivative for point estimation of the parameters. The procedure applied to an experimental situation involving two compartments gives very encouraging results.
Nonparametric Location Tests Based on the Empirical Distribution
Authors: Huesler Juerg , Riedwyl Hans
Published: June 2010

We present a unified approach to the nonparametric comparison of locations in the one‐ and two sample case using the empirical distribution functions. This approach reveals how to define a simple test statistic for this comparison in the case of large sample sizes which is equivalent to the known Wilcoxon‐Mann‐Whitney statistics and is based on the grouping of the data. In the particular case of equal group sizes we find an extremely simple form for this location test.
Recurrence Relations Among Moments of Order Statistics from Two Related Outlier Models
Authors: Balakrishnan N.
Published: June 2010

It is shown that the moments of order statistics in samples drawn from a continuous population withpdf f(x)symmetric about zero comprising a single outlier withpdf g(x)symmetric about zero can be expressed in terms of the moments of order statistics in samples drawn from the population obtained by folding thepdf f(x)at zero and the moments of order statistics in samples drawn from the population obtained by folding thepdf f(x)at zero comprising a single outlier withpdfobtained by foldingg(x)at zero. The cumulative round off error involved in numerical evaluation of the moments of order statistics from the symmetric‐outlier model, using a table of the moments of order statistics from the folded population and the moments of order statistics from the folded‐outlier model, is not serious.
Note on Confidence Regions in Multiple Assays
Authors: Bennett B. M.
Published: June 2010

This note is in continuation of the author's results on ’classical‘ confidence regions for relative potencies in multiple assays (Bennett, 1987). It is shown by the use of a Bonferroni inequality (e.g. Miller, ch. 2, 1980) that approximate confidence regions for the relative potencies {Mi} i = 1, …, p may also be obtained directly. A comparison with the classical regions is made for the case: p = 2 using Finney's example (1978, ch. 2).
The Power of the Anderson‐Hauck Test and the Double T‐Test
Authors: Müller‐Cohrs J.
Published: June 2010

When the object of an experiment is to demonstrate equivalence of two treatments then, under normal theory, there are two competing methods: The double t‐test and the test of Anderson and Hauck. Viewing the operating characteristic as a function of the noncentrality parameter the double t‐test has slightly more power, especially for few degrees of freedom, in the upper range of the curve (power ≥0.6). In contrast, the test of Anderson‐Hauck is considerably more powerful towards the lower end of the power curve.
Internal Covariance Structure of Some Coronary Heart Disease Risk Variables Investigated in Two Groups of Data
Authors: Bartkowiak Anna , Lukasik S. , Chwistecki K. , Mrukowicz M. , Morgenstern W.
Published: June 2010

In a former paper BARTKOWIAK (1987) has shown some aspects of simultaneous diagonalization of two covariance matrices in the context of a medical data set in which the considered variables were strongly dependent.

In this paper we show a real example (considering some coronary disease risk factors) when the considered variables are nearly independent and for which the problem of equal covariance structure is relevant both from statistical and medical point of view.

In Section 1 we present the medical problem and the motivation for performing this study.

In Section 2 we recall the problem of seeking for common principal components coordinate system by a simultaneous diagonalization of two covariance matrices by use of one common rotation matrix.

In Section 3 we show the effects of a simultaneous diagonalization applied to two groups of individuals (“Alive” and “CHD death”) It comes out with P = 0.68 that these groups can have a common principal component coordinate system.

In Section 4 we gather more close at the correlations between the considered variables looking for some peculiarities occurring in the recorded data.
On a Problem of Increasing the Efficiency of Second‐order Rotatable Designs
Authors: Huda Shahariar
Published: June 2010

The problem considered is that of supplementing any given second‐order rotatable design DO with additional design points in order to gain maximal increase in efficiency when the experimenter is allowed to double the number of design points subject to the condition that the composite design, consisting of DO plus the additional points, should also be rotatable. Using generalized variance as a measure of efficiency some interesting results are derived.
On the Equivalence of the Johnson‐Neyman Technique and Fieller's Theorem
Authors: Schwenke James R.
Published: June 2010

It is shown that for the one‐way analysis of covariance model with one covariate, when the hypothesis of a common slope parameter has been rejected, the Johnson‐Neyman procedure results in a confidence interval equivalent to that obtained using Fieller's theorem. It is noted in Fieller's paper that the theory behind this technique was first introduced by Bliss, but not specifically applied to the analysis of covariance problem. Credit for this procedure should be shared by Bliss, Fieller, and Johnson and Neyman.
Estimation of Epidemiologic Interaction of Etiologic Factors in Biomedical Studies
Authors: Rao B. Raja
Published: June 2010

In the present paper, a multiple logistic model has been proposed to estimate the exposure‐specific incidence rates of several dichotomous etiologic factors from case‐control data. The relative probability of falling in a given exposure level with respect to the unexposed population for cases is expressed as a logistic function of the exposure levels (1 if exposed, 0 if not) of these factors. The odds ratio of the exposure category of cases relative to the controls comes out to be an exponential function of the exposure levels. It is shown how the maximum likelihood estimates of the logistic parameters can be obtained. The term ‘marginal effect’ of a factor is introduced. This is the effect of a factorAin the presence of one or more of other factors. The differenceSAbetween the marginal effect and the individual effect of a factorAis the increase in the effect ofAwhen it interacts with other factors. A simple relationship has been established between the Hogan et al. measure and the increasesSA,SB, … of two or more factors. Several numerical examples illustrate the results.
Robust Estimation of Relative Potency in Dilution Assays
Authors: Hill N. J. , Padmanabhan A. R.
Published: June 2010

For inference regarding relative potency in dilution assays with possible latent effects, a robust procedure is proposed. Monte Carlo studies show that this procedure compares favourably with known procedures. The theory is illustrated by an application to the tolerances of cats for tinctures of strophanthus.
Evaluation of the Noncentral t Distribution with S‐Systems
Authors: Voit E. O. , Rust P. F.
Published: June 2010

Densities, cumulatives, and quantiles of the noncentral distributions are notoriously difficult to calculate. It is shown how the noncentral t distribution is represented in the canonical S‐system form, i.e., as a set of first‐order nonlinear differential equations in which the derivative of each variable equals a difference of two products of power‐law functions. By solving the S‐system numerically one rapidly obtains densities, cumulatives, quantiles, and moments of the central and noncentral t distributions, as well as power functions for the t‐test.
A Test for Bivariate Symmetry of Dependent Competing Risks
Authors: Deshpande J. V.
Published: June 2010

In the competing risks set up with two dependent competing risks letF(x, y)be the joint probability distribution of(X, Y), the notional times to failure under the two risks. Actual independent observations are (Ti,δi),i= 1, 2,…,nwhereTi= min (Xi, Yi) and δi=I (Xi≦ Yi). To testH0: F(x, y) = F(y, x) for allx, y, againstH1:S1(t) ≦S2(t) whereS1(t) =P(T≦t, δ = 1) andS2(t) =P(T≦t, δ = 0), it is proposed to use the Wilcoxon signed rank type statistic Jc= ∑δi(n+ 1 —Ri) whereRi= Rank (Ti) among (T1,T2, …,Tn). TheJctest is seen to be generally more efficient than the sign test except in case of alternatives under whichTand δ are independent, in which case the opposite is true.
Linearized Dentition Plot
Authors: Masuyama M.
Published: June 2010

The dentition is a fundamental process in life. Then the almost‐one parameter hypothesis suggests us that the individual difference would be represented by one parameter. In fact, the logarithmically transformed chronological ages Yαi at the eruption of deciduous teeth Dα are represented by a linear equation of its mean Yα.(4), where two coefficients ai, and bi are highly negatively correlated. It implies the existence of a quasi‐fixed point close to this line. See Fig. 1 and Fig. 2, where this point is denoted by a cross. This point is utilized to forecast the age at the subsequent eruption.
Comparing the Means of Two Independent Groups
Authors: Wilcox Rand R.
Published: June 2010

Recently, CRESSIE and WHITFORD (1986) showed that Welch's test of H0 :μ1 = μ2 can be biased, under nonnormality, where μ1 and μ2 are the means of two independent treatment groups. They suggested, therefore, that a two‐sample analog of Johnson's test be used instead. One goal in this paper is to examine the extent to which a two‐sample analog of Johnson's test improves upon Welch's technique in terms of Type I errors and power when sample sizes are small or moderately large. Several alternative procedures are also considered including an additional modification of Johnson's procedure, a procedure suggested by DUNNETT (1982) that uses Tiku's modified maximum likelihood estimate with 10% trimming, two versions of Efron's bootstrap, and a test recently proposed by WILCOX (1989). The paper also describes situations where Welch's procedure is not robust in terms of Type I errors. This is important because based on results currently available, Welch's procedure is thought to be nonrobust in terms of power, but robust in terms of Type I errors.
Bias Adjustment with Polychotomous Logistic Regression in Matched Case‐Control Studies with Two Control Groups
Authors: Becher K.‐H. , Jöckel K.‐H.
Published: June 2010

Relative risk estimation in case‐control studies is based on the premise that the control group represents the underlying population. Often more than one control group is collected in order to minimize the possibility of accepting a false result.

In this paper it is assumed that a case is matched individually to two different controls and that one control group may lack representativeness with respect to some risk factors. It is discussed whether this group may be used for relative risk estimation and a polychotomous logistic regression model is suggested in which these differences between the control groups are taken into account. A practical method for model search is given.

Data of two case‐control studies are used to demonstrate the method. In a simulation study its efficiency is investigated. Some computations illustrate the effect of ignoring a bias in one control group.
Estimation of Distances and Variances in Bookstein's Landmark Model
Authors: Stoyan D.
Published: June 2010

Planar random figures can be described by series of landmarks. Bookstein's model assumes that the landmarks result from independent individual fluctuations around fixed fictive landmark centres. The aim of this paper is to estimate the distances between the centers and the variances of fluctuations around them. Furthermore, two new shape variable estimators are suggested and compared with an estimator of Bookstein.
On the Estimation of the Nearest Neighbour Distribution, G(t), for Point Processes
Authors: Doguwa S. I. , Upton G. J. G.
Published: June 2010

A new method is proposed for estimatingG(t), the distribution function of the distance from an object to its nearest neighbour in a spatial point process. The new method makes more complete use of the information available and has a smaller mean squared error than that of the existing alternatives. The method appears equally effective with random, clustered and regular patterns.
Estimation of the Size Distribution of Spherical Grains in the Boolean Model
Authors: Molohanov Ilya S.
Published: June 2010

A method of strong consistent estimation of the radius' distribution of spherical grains in the Boolean model inRd,d≦3, is proposed. It is based on the evaluation of the empirical capacity functional and application of the Glivenko‐Cantelli theorem for random closed sets.
Robust Discriminant Functions in Assisting Medical Diagnosis. Application to the Chronic Obturative Lung Disease Data
Authors: Krusińska Ewa , Liebhart Jerzy
Published: June 2010

The results of assisting medical diagnosis in bronchial asthma and chronic bronchitis via robust discriminant functions are presented in the paper. The robust discriminant functions are obtained by replacing classical estimates of mean vectors and covariance matrices by their robust equivalents. The new methods were compared with classical ones. These methods resulted in the improvement of automatic diagnosis especially when the “new” data set was classified on the basis of individuals collected earlier.
A Generalized Logistic Model for Quantal Response Bioassay
Authors: El‐Saidi M. A. , George E. O.
Published: June 2010

In bioassay, where different levels of the stimulus may represent different doses of a drug, the binary response is the death or survival of an individual receiving a specified dose. In such applications, it is common to model the probability of a positive response P at the stimulus level x by P = F(x′β), where F is a cumulative distribution function and β is a vector of unknown parameters which characterize the response function. The two most popular models used for modelling binary response bioassay involve the probit model [BLISS (1935), FINNEY (1978)], and the logistic model [BERKSON (1944), BROWN (1982)]. However, these models have some limitations. The use of the probit model involves the inverse of the standard normal distribution function, making it rather intractable. The logistic model has a simple form and a closed expression for the inverse distribution function, however, neither the logistic nor the probit can provide a good fit to response functions which are not symmetric or are symmetric but have a steeper or gentler incline in the central probability region. In this paper we introduce a more realistic model for the analysis of quantal response bioassay. The proposed model, which we refer to it as the generalized logistic model, is a family of response curves indexed by shape parameters m1 and m2. This family is rich enough to include the probit and logistic models as well as many others as special cases or limiting distributions.

In particular, we consider the generalized logistic three parameter model where we assume that m1 = m, m is a positive real number, and m2 = 1. We apply this model to various sets of data, comparing the fit results to those obtained previously by other dose‐response curves such as the logistic and probit, and showing that the fit can be improved by using the generalized logistic.
P‐Values as Measures of Predictive Validity
Authors: Whitmore G. A. , Xekalaki E.
Published: June 2010

A predictive P‐value is proposed to measure the difference between an actual and predicted outcome in assessing the validity of an hypothesized prediction model. The concept is illustrated by applications to multiple regression prediction and to the validation of forecast models.
Anticancer and chemosensitizing abilities of cycloviolacin O2 from Viola odorata and psyle cyclotides from Psychotria leptothyrsa
Authors: Gerlach Samantha L. , Rathinakumar Ramesh , Chakravarty Geetika , Göransson Ulf , Wimley William C. , Darwin Steven P. , Mondal Debasis
Published: June 2010

Cycloviolacin O2 (CyO2), a cyclotide from Viola odorata (Violaceae) has antitumor effects and causes cell death by membrane permeabilization. In the breast cancer line, MCF‐7 and its drug resistant subline MCF‐7/ADR, the cytotoxic effects of CyO2 (0.2–10 μM) were monitored in the presence and absence of doxorubicin (0.1–5 μM) using cell proliferation assays to establish its chemosensitizing abilities. SYTOX Green assays were performed to verify membrane permeabilization and showed cellular disruption correlates with cyclotide chemosensitization. Fluorescence microscopy studies demonstrated increased cellular internalization of doxorubicin in drug resistant cells when coexposed to CyO2. Interestingly, CyO2 did not produce significant membrane disruption in primary human brain endothelial cells, which suggested cyclotide specificity toward induced pore formation in highly proliferating tumor cells. Furthermore, three novel cyclotides (psyle A, C and E) from Psychotria leptothyrsa (Rubiaceae) were also monitored for cytotoxic activity. The cyclotides displayed potent cytotoxicity (IC50 = 0.64–>10 μM), and coexposure to cyclotides significantly enhanced doxorubicin induced toxicity (IC50 = 0.39–0.76 μM). This study documents several cyclotides with robust cytotoxicity that may be promising chemosensitizing agents against drug resistant breast cancer. © 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 94: 617–625, 2010.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Optimized Fmoc solid‐phase synthesis of the cysteine‐rich peptide linaclotide
Authors: Góngora‐Benítez Miriam , Tulla‐Puche Judit , Paradís‐Bas Marta , Werbitzky Oleg , Giraud Matthieu , Albericio Fernando
Published: June 2010

Linaclotide, a small 14‐mer peptide highly rich in cysteines, is currently in phase III clinical trials for the treatment of gastrointestinal disorders. The challenge in the assembly of linaclotide consists of achieving the correct and clean folding of its three disulfide bridges. For this purpose, a number of regioselective, semiregioselective, and random strategies have been studied. In addition to selecting distinct protecting groups for the thiol function, their position in the sequence, the influence of the neighboring protecting groups, as well as the order in which the disulfides fold were studied. Here we describe an optimized solid‐phase synthesis of linaclotide that should allow the production of this peptide in multigram amounts. © 2010 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 96: 69–80, 2011.
When emotionality trumps reason: A study of individual processing style and juror bias
Authors: Gunnell Justin J. , Ceci Stephen J
Published: June 2010

“Cognitive Experiential Self Theory” (CEST) postulates that information‐processing proceeds through two pathways, a rational one and an experiential one. The former is characterized by an emphasis on analysis, fact, and logical argument, whereas the latter is characterized by emotional and personal experience. We examined whether individuals influenced by the experiential system (E‐processors) are more susceptible to extralegal biases (e.g. defendant attractiveness) than those influenced by the rational system (R‐processors). Participants reviewed a criminal trial transcript and defendant profile and determined verdict, sentencing, and extralegal susceptibility. Although E‐processors and R‐processors convicted attractive defendants at similar rates, E‐processors were more likely to convict less attractive defendants. Whereas R‐processors did not sentence attractive and less attractive defendants differently, E‐processors gave more lenient sentences to attractive defendants and harsher sentences to less attractive defendants. E‐processors were also more likely to report that extralegal factors would change their verdicts. Further, the degree to which emotionality trumped rationality within an individual, as measured by a novel scoring method, linearly correlated with harsher sentences and extralegal influence. In sum, the results support an “unattractive harshness” effect during guilt determination, an attraction leniency effect during sentencing and increased susceptibility to extralegal factors within E‐processors. Copyright © 2010 John Wiley & Sons, Ltd.
A Novel Indirect Wollastonite Carbonation Route for CO2 Sequestration
Authors: Zhang J. , Zhang R. , Geerlings H. , Bi J.
Published: June 2010

A new CO2 sequestration approach through indirect wollastonite carbonation is proposed to mitigate anthropogenic CO2 emissions from fossil fuel combustion. The wollastonite carbonation process includes three steps: (1) dissolution of wollastonite in hydrochloric acid to leach Ca2+ from mineral matrix; (2) reaction of the resulting CaCl2 solution with CO2 in triisooctylamine (TIOA) at low temperature, producing CaCO3 and an amino acid complex; (3) regeneration of the extractant and acid by backextraction through a temperature swing process and recycling to the dissolution and carbonation steps. It was found that the wollastonite dissolution rate was accelerated by hydrochloric acid and a maximum Ca2+ dissolution extent of 95 % was obtained.
Particle‐by‐Particle Reconstruction of Ultrafiltration Cakes in 3D from Binarized TEM Images
Authors: Bourgeois F. , Courteille F.
Published: June 2010

Transmission electron microscopy (TEM) imaging is one of the few techniques available for direct observation of the microstructure of ultrafiltration cakes. TEM images yield local microstructural information in the form of two‐dimensional grayscale images of slices a few particle diameters in thickness. This work presents an innovative particle‐by‐particle reconstruction scheme for simulating ultrafiltration cake microstructure in three dimensions from TEM images. The scheme uses binarized TEM images, thereby permitting use of lesser‐quality images. It is able to account for short‐ and long‐range order within ultrafiltration cake structure by matching the morphology of simulated and measured microstructures at a number of resolutions and scales identifiable within the observed microstructure. In the end, simulated microstructures are intended for improving our understanding of the relationships between cake morphology, ultrafiltration performance, and operating conditions.
Identifying the Bond Responsible for the Fluorescence Modulation in an Amyloid Fibril Sensor
Authors: Srivastava Anvita , Singh Prabhat K. , Kumbhakar Manoj , Mukherjee Tulsi , Chattopadyay Subrata , Pal Haridas , Nath Sukhendu
Published: June 2010

An ultrafast intramolecular bond twisting process is known to be the responsible mechanism for the sensing activity of the extensively used amyloid fibril sensor thioflavin T (ThT). However, it is not yet known which one of the two possible single bonds in ThT is actually involved in the twisting process. To resolve this fundamental issue, two derivatives of ThT have been designed and synthesized and subsequently their photophysical properties have been studied in different solvents. It is understood from the present study that the rotation around the central CC single bond, and not that around the CN single bond, is primarily responsible for the sensor activity of ThT. Detailed viscosity‐dependent fluorescence studies revealed that the ThT derivative with restricted CN bond rotation acts as a better sensor than the derivative with free CN bond rotation. The better sensory activity is directly correlated with a shorter excited‐state lifetime. Results obtained from the photophysical studies of the ThT derivatives have also been supported by the results obtained from quantum chemical calculations.
Magnetic Coupling in Enantiomerically Pure Trinuclear Helicate‐Type Complexes Formed by Hierarchical Self‐Assembly
Authors: Albrecht Markus , Fiege Marcel , Kögerler Paul , Speldrich Manfred , Fröhlich Roland , Engeser Marianne
Published: June 2010

Based on chiral, enantiomerically pure 7‐[(S)‐phenylethylurea]‐8‐hydroxyquinoline (1‐H), trinuclear helicate‐type complexes 2–5 are formed with divalent transition‐metal cations. X‐ray structural analyses reveal the connection of two monomeric complex units [M(1)3]− (M=Zn, Mn, Co, Ni) by a central metal ion to form a “dimer”. Due to the enantiopurity of the ligand, the complexes are obtained as pure enantiomers, resulting in pronounced circular dichroism (CD) spectra. Single‐ion effects and intra‐ and intermolecular coupling are observed with dominating ferromagnetic coupling in the case of the cobalt(II) and nickel(II) and dominating antiferromagnetic coupling in the case of the manganese(II) complex.
Cavity‐Shaped Ligands: Calix[4]arene‐Based Monophosphanes for Fast Suzuki–Miyaura Cross‐Coupling
Authors: Monnereau Laure , Sémeril David , Matt Dominique , Toupet Loïc
Published: June 2010

Five conical calix[4]arenes that have a PPh2 group as the sole functional group anchored at their upper rim were assessed in palladium‐catalysed cross‐coupling reactions of phenylboronic acid with aryl halides (dioxane, 100 °C, NaH). With arylbromides, remarkably high activities were obtained with the catalytic systems remaining stable for several days. The performance of the ligands is comparable to a Buchwald‐type triarylphosphane, namely, (2′‐methyl[1,1′‐biphenyl]‐2‐yl)diphenylphosphane, which in contrast to the calixarenyl phosphanes tested may display chelating behaviour in solution. With the fastest ligand, 5‐diphenylphosphanyl‐25,26,27,28‐tetra(p‐methoxy)benzyloxy‐calix[4]arene (8), the reaction turnover frequency for the arylation of 4‐bromotoluene was 321 000 versus 214 000 mol(ArBr).mol(Pd)−1. h−1 for the reference ligand. The calixarene ligands were also efficient in Suzuki cross‐coupling reactions with aryl chlorides. Thus, by using 1 mol % of [Pd(OAc)2] associated with one of the phosphanes, full conversion of the deactivated arenes 4‐chloroanisole and 4‐chlorotoluene was observed after 16 h. The high performance of the calixarenyl–phosphanes in Suzuki–Miyaura coupling of aryl bromides possibly relies on their ability to stabilise a monoligand [Pd0L(ArBr)] species through supramolecular binding of the Pd‐bound arene inside the calixarene cavity.
Towards Molecular Design Rationalization in Branched Multi‐Thiophene Semiconductors: The 2‐Thienyl‐Persubstituted α‐Oligothiophenes
Authors: Benincori Tiziana , Bonometti Valentina , De Angelis Filippo , Falciola Luigi , Muccini Michele , Mussini Patrizia R. , Pilati Tullio , Rampinini Giovanni , Rizzo Simona , Toffanin Stefano , Sannicolò Francesco
Published: June 2010

The introduction of branching in multi‐thiophene semiconductors, although granting the required solubility for processing, results in an increased molecular fluxionality and a higher level of distortion, thus hampering π conjugation. Accordingly, branched oligothiophenes require rationalization of their structure–reactivity relationships for target‐oriented design and optimization of the synthetic effort. Our current research on spiderlike oligothiophenes affords deep insight into the subject, and introduces new, easily accessible molecules with attractive functional properties. In particular, a regular series, T′XY, of five new multi‐thiophene systems, T′53, T′84, T′115, T′146, and T′177, constituted by five, eight, 11, 14, and 17 thiophene units, respectively, their longest α‐conjugated chain consisting of tri‐, tetra‐, penta‐, hexa‐, and heptathiophene moieties, respectively, has been synthesized and fully characterized from the structural, spectroscopic, and electrochemical point of view. The electronic properties of the monomers and their electropolymerization ability are discussed and rationalized as a function of their molecular structure, particularly in comparison with the series of 5‐(2,2′‐dithiophene)yl‐persubstituted α‐oligothiophenes (TXY) previously reported by us. These oligothiophenes are easily accessible materials, with promising properties for applications as active layers in multifunctional organic devices including solar cells.
Seed‐Mediated Synthesis of Au Nanocages and Their Electrocatalytic Activity towards Glucose Oxidation
Authors: Zhang Yue , Xu Fugang , Sun Yujing , Guo Cunlan , Cui Kang , Shi Yan , Wen Zhiwei , Li Zhuang
Published: June 2010

We report a modified seed‐mediated approach for the synthesis of uniform Au nanocages (AuNCs). HAuCl4 was reduced in an aqueous mixture of hexamethylenetetramine (HMT), poly(N‐vinyl‐2‐pyrrolidone) (PVP), and AgNO3. The nanocages were (54.6±13.3) nm in outer‐edge length and about 12 nm in wall thickness. The structure of the AuNCs was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray energy dispersive spectroscopy (EDS), X‐ray diffraction (XRD), Fourier‐transform infrared (FTIR) spectroscopy, and X‐ray photoelectron spectroscopy (XPS). Morphological changes associated with the seed‐mediated growth of Au nanoparticles (AuNPs) in the absence of HMT or PVP were examined. The results demonstrate that both PVP and HMT play important roles in the formation of the nanocage structure. The function of AgNO3 was also studied. A possible formation mechanism for the AuNCs was investigated by monitoring TEM images of the Au nanostructures formed at various reaction times. The electrocatalytic activity of the AuNCs towards the oxidation of glucose was explored, and a nonenzymatic glucose sensor with high sensitivity and good stability was further fabricated. To the best of our knowledge, this is the first report of the preparation of AuNCs by a seed‐mediated strategy and of the application of AuNCs in the electrocatalytic oxidation of glucose. Our results should facilitate the creation of novel nanomaterials with various morphologies and the exploration of their applications in nanotechnological, optical, catalytic, and materials science fields.
Planar Chiral Organoborane Lewis Acids Derived from Naphthylferrocene
Authors: Chen Jiawei , Venkatasubbaiah Krishnan , Pakkirisamy Thilagar , Doshi Ami , Yusupov Andrej , Patel Yesha , Lalancette Roger A. , Jäkle Frieder
Published: June 2010

Enantiomerically pure metalated 2‐(1‐naphthyl)ferrocene (NpFc) derivatives NpFcM (M=SnMe3, HgCl) were prepared and characterized by multinuclear NMR and UV/Vis spectroscopy, cyclic voltammetry, and elemental analysis. Optical rotation measurements were performed and the absolute configuration of the new planar chiral ferrocene species was confirmed by single‐crystal X‐ray diffraction analysis. The mercuriated species NpFcHgCl proved suitable as a reagent for the preparation of the chiral organoborane Lewis acid NpFcBCl2, which can in turn be converted to other ferrocenylboranes by replacement of Cl with nucleophiles. The highly Lewis acidic perfluoroarylborane derivatives NpFcB(C6F5)Cl and NpFcB(C6F5)2 were successfully prepared by treatment with CuC6F5. The structures were studied by single‐crystal X‐ray diffraction and variable‐temperature 19F NMR spectroscopy, which suggested that π stacking of a C6F5 group on boron with the adjacent naphthyl group is energetically favorable. UV/Vis absorption spectroscopy and cyclic voltammetry measurements were performed to examine the electronic properties of these novel redox‐active chiral Lewis acids.
Dumbbell‐Shaped Dinuclear Iridium Complexes and Their Application to Light‐Emitting Electrochemical Cells
Authors: Costa Rubén D. , Fernández Gustavo , Sánchez Luis , Martín Nazario , Ortí Enrique , Bolink Henk J.
Published: June 2010

A novel family of dumbbell‐shaped dinuclear complexes in which an oligophenyleneethynylene spacer is linked to two heteroleptic iridium(III) complexes is presented. The synthesis, as well as the electrochemical and photophysical characterization of the new complexes, is reported. The experimental results are interpreted with the help of density functional theory calculations. From these studies we conclude that the lowest triplet excited state corresponds to a 3π–π* state located on the conjugated spacer. The presence of this state below the 3MLCT/3LLCT emitting states of the end‐capping IrIII complexes explains the low quantum yields observed for the dinuclear complexes (one order‐of‐magnitude less) with respect to the mononuclear complexes. The potential application of the novel dinuclear complexes in optoelectronic devices has been tested by using them as the primary active component in double‐layer light‐emitting electrochemical cells (LECs). Although the luminance levels are low, the external quantum efficiency suggests that a near‐quantitative internal electron‐to‐photon conversion occurs in the device. This indicates that the emission inside the device is highly optimized and that the self‐quenching associated with the high concentration of the complex in the active layer is minimized.
Formation and Rearrangement of SnII Phosphanediide Cages
Authors: McPartlin Mary , Melen Rebecca L. , Naseri Vesal , Wright Dominic S.
Published: June 2010

The room‐temperature reactions of Sn(NMe2)2 with less sterically demanding primary phosphines (RPH2) give the homoleptic phosphanediide compounds [SnPR]n in high yields (R=tBu (1 a), cyclohexyl (1 b), 1‐adamantyl (1 c)). However, the room‐temperature reaction of Mes*PH2 (Mes*=2,4,6‐tBu3C6H2) with Sn(NMe2)2 gives the model intermediate [{SnPMes*}2(μ‐NMe2)SnP(H)Mes*] (3), together with the product of complete deprotonation [SnPMes*]3 (4). Phosphorusphosphorus bonded products are produced in these reactions at elevated temperatures. If the reaction producing 1 a is heated to reflux then [tBuP(H)P(H)tBu] is produced as the major product (together with tin metal). The novel octanuclear cage [{SnPtBu}7Sn(PtBu)3] (2) can also be isolated in low yield, resulting from formal addition of the heterocyclic stannylene [(tBuP)3Sn] to a SnP single bond of the intact structure of 1 a. Prolonged heating of the reaction producing 3 and 4 leads to the formation of the diphosphene [PMes*]2 (5) and tin metal. The X‐ray structures of the heptamer 1 a (n=7), octanuclear 2 and trinuclear 3 are reported.
Al3Li4(BH4)13: A Complex Double‐Cation Borohydride with a New Structure
Authors: Lindemann Inge , Domènech Ferrer Roger , Dunsch Lothar , Filinchuk Yaroslav , Černý Radovan , Hagemann Hans , D'Anna Vincenza , Lawson Daku Latévi Max , Schultz Ludwig , Gutfleisch Oliver
Published: June 2010

The new double‐cation Al–Li–borohydride is an attractive candidate material for hydrogen storage due to a very low hydrogen desorption temperature (∼70 °C) combined with a high hydrogen density (17.2 wt %). It was synthesised by high‐energy ball milling of AlCl3 and LiBH4. The structure of the compound was determined from image‐plate synchrotron powder diffraction supported by DFT calculations. The material shows a unique 3D framework structure within the borohydrides (space group=P‐43n, a=11.3640(3) Å). The unexpected composition Al3Li4(BH4)13 can be rationalized on the basis of a complex cation [(BH4)Li4]3+ and a complex anion [Al(BH4)4]−. The refinements from synchrotron powder diffraction of different samples revealed the presence of limited amounts of chloride ions replacing the borohydride on one site. In situ Raman spectroscopy, differential scanning calorimetry (DSC), thermogravimetry (TG) and thermal desorption measurements were used to study the decomposition pathway of the compound. Al–Li–borohydride decomposes at ∼70 °C, forming LiBH4. The high mass loss of about 20 % during the decomposition indicates the release of not only hydrogen but also diborane.
ChemInform Abstract: Structures of arachno‐ and hypho‐B10 Clusters and Stability of Their Possible Lewis Base Adducts ([B10H12]2‐, [B10H12×L]2‐, [B10H12×2L]2‐, [B10H13]‐, [B10H13×L]‐, [B10H12×2L]). An ab initio/IGLO/NMR Investigation.
Authors: HOFMANN M. , VON RAGUE SCHLEYER P.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Antiferromagnetic Ordering in the Novel Ho3Ge5 and HoGe1.85 Compounds Studied by X‐Ray and Neutron Diffraction.
Authors: ZAHARKO O. , SCHOBINGER‐PAPAMANTELLOS P. , RITTER C.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Novel Crystal Structure in the Chevrel‐Phase Compound EuMo6Se8. Transport and Magnetic Properties.
Authors: LE BERRE F. , PENA O. , PERRIN C. , PADIOU J. , HORYN R. , WOJAKOWSKI A.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Superconducting Epitaxial (TlBi)0.9Sr1.6Ba0.4Ca2 Cu3Ag0.2Ox Film from an Electrodeposited Precursor.
Authors: BHATTACHARYA R. N. , BLAUGHER R. D. , REN Z. F. , LI W. , WANG J. H. , PARANTHAMAN M. , VEREBELYI D. T. , CHRISTEN D. K.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Structural and Magnetic Properties of Fe2O3 Nanoparticles Dispersed over a Silica Matrix.
Authors: CANNAS C. , GATTESCHI D. , MUSINU A. , PICCALUGA G. , SANGREGORIO C.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Growth Kinetics of Nanocrystalline ZnO Particles from Colloidal Suspensions.
Authors: WONG E. M. , BONEVICH J. E. , SEARSON P. C.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Synthesis of Heteropolyoxometalate‐Pillared Mg/Al, Mg/Ga, and Zn/Al Layered Double Hydroxides via LDH—Hydroxide Precursors.
Authors: WEIR M. R. , KYDD R. A.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Ruthenium Carbonyl Clusters in Faujasite Cages: Synthesis and Characterization.
Authors: SHEN G.‐C. , LIU A. M. , ICHIKAWA M.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: An Unusual Cyanide Bridging Lanthanide—Transition Metal Complex that Contains the One‐Dimensional Cationic Array {[(DMF)16Yb6(μ6‐O) (μ3‐OH)8(μ‐NC)Pd(μ‐CN)(CN)2] 6+}∞.
Authors: LIU J. , MEYERS E. A. , SHORE S. G.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Matrix Isolation Infrared and Density Functional Theoretical Studies of Organic Silanones, (CH3O)2Si=O and (C6H5)2Si=O.
Authors: KHABASHESKU V. N. , KERZINA Z. A. , KUDIN K. N. , NEFEDOV O. M.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Amidines. Part 39. Formation of N1,N1‐Dialkylamidines in the Reaction Between Amide Acetals and Substituted Anilines in Pyridine. Reaction Mechanisms.
Authors: OSZCZAPOWICZ J. , OSEK J.
Published: June 2010

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.