bluuebunny/crossref_metadata_2025_split huggingface dataset:
Constrained Curriculum in High Schools: The Changing Math Standards and Student Achievement, High School Graduation and College Continuation
Authors: Daun-Barnett Nathan , St. John Edward P. 
Published: March 2015

Mathematics education is a critical public policy issue in the U.S. and the pressures facing students and schools are compounded by increasing expectations for college attendance after high school. In this study, we examine whether policy efforts to constrain the high school curriculum in terms of course requirements and mandatory exit exams affects three educational outcomes – test scores on SAT math, high school completion, and college continuation rates. We employ two complementary analytic methods – fixed effects and difference in differences (DID) – on panel data for all 50 states from 1990 to 2008. Our findings suggest that within states both policies may prevent some students from completing high school, particularly in the near term, but both policies appear to increase the proportion of students who continue on to college if they do graduate from high school. The DID analyses provide more support for math course requirement policies than mandatory exit exams, but the effects are modest. Both the DID and fixed effects analyses confirm the importance of school funding in the improvement of high school graduation rates and test scores.
Numerical Analysis of Electromagnetic Levitation Employing Meshless Method Based on Weighted Least Square Method
Authors: Matsuzawa Shuhei , Mitsufuji Kenta , Miyake Yurika , Hirata Katsuhiro , Miyasaka Fumikazu 
Published: March 2015

AbstractElectromagnetic levitation is a kind of magnetohydrodynamic phenomena which is useful to measure the thermo-physical properties of pure metals under high temperature. However, this phenomenon is complicated and detailed mechanisms of this phenomenon have not been clarified yet. This study proposes the meshless method based on weighted least square method for the analysis of electromagnetic levitation. In this study, the fluid motion equation and the magnetic field equation are coupled by this method. The behavior of a molten metal under high-frequency magnetic field is calculated by this method.
Lengthwise Measurement of Chromatic Dispersion along an Optical Fiber Transmission Link with Enhanced Correction Factor
Authors: Baig Mirza Imran , Nahhas Ahmed M. 
Published: March 2015

AbstractIn recent years optical time domain reflectometer (OTDR)-based techniques have become a known practice for measuring chromatic dispersion (CD) distribution along an optical fiber transmission link. In this paper, a measurement technique which uses a four-wavelength bidirectional OTDR to evaluate the CD distribution along the length of an optical fiber transmission system has been presented. A novel formulation has been developed for this nondestructive technique to improve the correction factor, which leads to an improvement in the CD and mode field diameter (MFD) measurement. The obtained experimental outcomes are in good agreement with those obtained by the interferometric technique.
Osteocalcin is inversely associated with adiposity and leptin in adolescent boys
Authors: Jürimäe Jaak , Lätt Evelin , Mäestu Jarek , Saar Meeli , Purge Priit , Maasalu Katre , Jürimäe Toivo 
Published: March 2015

AbstractRecently, osteocalcin (OC), an osteoblast-derived hormone, has been found to correlate with adiposity, adipocytokines and insulin resistance in adults, but few studies have investigated this in children. The aim of this study was to investigate these associations in adolescent boys, for whom it is a time of significant bone mineral accrual, taking into account possible confounders related to adipose and bone tissues.Participants were 141 adolescent boys (mean age 13.9±0.7 years), who were divided into tertiles according to OC levels. Across these groups, differences in total body fat mass (FM), body fat distribution, adiponectin, leptin and insulin resistance values were examined with relation to age, pubertal stage, daily energy and calcium intakes, and physical activity.Mean body mass index (BMI), FM, body fat% and leptin differed significantly between subjects in the three OC tertiles after adjustment for age, pubertal stage, energy and calcium intakes, and physical activity. There were no differences in fat free mass (FFM), bone mineral content, energy and calcium intakes, physical activity, adiponectin and insulin resistance values between study groups. For the entire cohort, mean serum OC was 130.2±45.2 ng/mL and was related to body mass, BMI, FM, body fat distribution and leptin. Circulating OC was not associated with FFM, daily energy and calcium intakes, physical activity, adiponectin or insulin resistance (insulin, glucose, homeostasis model assessment-insulin resistance) values.In male adolescents, OC is inversely related to body adiposity and leptin values, even after consideration of several factors that may affect bone and adipose tissues.
Exploring Libraries’ Efforts in Inclusion and Outreach Activities Using Social Media
Authors: Abdullah Noorhidawati , Chu Samuel , Rajagopal Sandhya , Tung Abigail , Kwong-Man Yeung 
Published: March 2015

AbstractThe main purpose of this study was to investigate the use of social media tools to enhance inclusion and outreach activities in libraries. The study also examined the existence of policies that encouraged the use of social media and the challenges that libraries face when integrating social media into their services. Invitations to participate in a survey were sent to 110 libraries in Greater China, Switzerland, United States of America, United Kingdom, Australia and New Zealand to investigate the use of social media tools in their inclusion/outreach programmes and librarians’ perceptions of their usefulness. Libraries were selected on the basis of indicating on their websites that they used social media. From the 110 libraries that were invited to participate in the survey, 28 responses were received and analysed. Among these, academic libraries made up 68% of the respondents, and the remaining 32% were from public libraries. The findings indicated that the libraries had already incorporated social media tools into their services, and, to some extent, for inclusion/outreach activities. In general, participants in this study indicated an acknowledgement of the benefits of using social media and an inclination to apply social media in the future, although the libraries and librarians faced the challenge of equipping themselves well in order to keep abreast of these technologies. The study highlighted the lack of specific policies that clarified the responsibilities of libraries in promoting social inclusion. Institutionalizing specific policies on the use of social media tools in libraries could be done either using a top-down and/or a bottom-up approach.
Synthese und Struktur des Trifluoracetyldicyanomethanids
Authors: Roesky Herbert W. , Noltemeyer Mathias , Sheldrick George M. 
Published: March 2015

Abstract
A suspension of NaCN in CH3CN was treated with excess of C2F4. The resulting red solution was evaporated to dryness and a red amorphous solid remained. One part of this solid was dissolved in water and a solution of Ph4AsCl was added. During the work-up procedure two salts were isolated, yellow [Ph4As+][CF3C(O)C(CN)2
-] 1a and red [Ph4As+][(NC)2CC(CN)C(F)NC(CN)2
-] 2a. The products were characterized on the basis of field desorption mass spectroscopy for positive and negative ions, 1a was further characterized by an X-ray single crystal investigation.
1-Thiooxamat, NH2C(O)C(S)O , und 2-Thiooxamat, NH2C(S)CO2 als Liganden in Übergangsmetall-Komplexen. Die Strukturen von [Fe(2-thiox)2(H2O)2], [Zn(2-thiox)2(H2O)] und [Zn(1-thiox)2(H2O)]·H2O/ 1-Thiooxamate, NH2C (O)C(S)O– , and 2-Thiooxamate, NH2C(S)CO2
–, as Ligands in Transition Metal Complexes. Crystal Structures of [Fe(2-thiox)2(H2O)2], [Zn(2-thiox)2(H2O)] and [Zn(1-thiox)2(H2O)]·H2O
Authors: Bertels Johannes , Mattes Rainer 
Published: March 2015

Abstract
Transition metal complexes of the ligands 1-thiooxamate and 2-thiooxam ate have been prepared. According to crystal structure analysis of Fe(2-thiox)2(H2O)2, Zn(2-thiox)2(H2O) and Zn(1-thiox)2(H2O)2 these ligands act as O .S-donors and form pentaatomic chelaterings. Both Zn-complexes are trigonal-bipyramidally coordinated.
Solid State and Solution Conformation of Di-2-thienyl Telluride: X-Ray Structure and Dipole Moment Studies
Authors: Bandoli Giuliano , Bergman Jan , Irgolic Kurt J. , Grassi Antonio , Pappalardo Giuseppe C. 
Published: March 2015

The crystal and molecular structure of di-2-thienyl telluride was determined by X-ray analysis. Crystal (monoclinic) data were: a = 9.526(4), b = 6.252(4), c - 16.302(5) Å; β = 97.29(3)°, Z = 4, space group P21/c. Hydrogen bonds are absent and only van der Waals forces are determining crystal packing. The Cring-Te bond distances suggest little conjugation of Te atom with the rings. Comparisons with published structures for Car-X-Car (X = chalcogen) type molecules revealed that the C (l)-Te-C(5) angle takes the lowest value (95.6°) in the molecule understudy. The remaining bond lengths and angles are close to standard values. The molecular conformation found in the crystal is “butterfly-like” , with thienyl ring planes nearly perpendicular to the C(l)-Te-C(5) plane and the S atoms distal to each other.
Dipole moment was measured for di-2-thienyl telluride in benzene solution (μ = 1.18 D at 30°). This value, which was interpreted via classical vector addition method in terms of rotation angles about C(l)-Te and C(5)-Te bonds, showed that the molecular conformation found in the crystalline state is retained in solution.
Synthesen und Kristallstrukturen von PPh4[RuCl4(NO)(NSCl)] und (PPh4)2[RuCl4(NS)]2·4C H2Cl2 / Syntheses and Crystal Structures of PPh4[RuCl4(NO)(NSCl)] and (PPh4)2[RuCl4(NS)]2·4C H2Cl2
Authors: Willing Wolfgang , Müller Ulrich , Demant Udo , Dehnicke Kurt 
Published: March 2015

Abstract
By reaction of trithiazylchloride, (NSCl)3, with PPh4[RuCl4(NO)]2 in dichloromethane the thiazylchloridenitrosyl complex PPh4[RuCl4(NO)(NSCl)] is obtained; its vacuum pyrolysis at 200-220 °C yields the thionitrosyl com plex (PPh4)2[RuCl4(NS)]2 which crystallizes from CH2Cl2 solution with four molecules of CH2Cl2. Both com pounds were charaterized by their IR spectra and by X-ray crystal structure determinations. Crystal data: PPh4[RuCl4(NO)(NSCl)], mono­clinic, space group P 21/n, Z = 4, a = 982.6, b = 1700.0, c = 1772.3 pm , β = 104.79° (2548 observed reflexions, R = 0.046); (PPh4)2[RuCl4(NS)]2·4CH2Cl2, triclinic, P1̄ , Z = 1, a = 952.9, b = 1380.0, c = 1458.5 pm , α = 112.91, β = 106.67, γ = 92.61° (3760 observed reflexions, R = 0.053). In the [RuCl4(NO)(NSCl)]⊖ ion the nitrosyl and thiazyl chloride ligands occupy ex ­ positions; bond lengths indicate double bonds in the linear Ru=N=O group, while the NSCl molecule is attached by a donor-acceptor interaction Ru-N≡S̲-Cl , although with a rather short Ru-N bond of 198 pm (N≡S 144 pm, S-Cl 213 pm). The centrosymmetric [RuCl4(NS)]2
2⊖ ions have chloro bridges and NS ligands in axial positions; the nearly linear Ru=N=S group has bond lengths Ru=N 175 pm and N=S 147 pm.
Zur Struktur von Tris(1,3-dimethyl-2-indolyl)-methan: Ein chiraler C3-Propeller aus der Trishetarylmethan-Reihe / The Structure of Tris(1,3-dim ethyl-2-indolyl)m ethane: a Chiral C3-Propeller in the Trishetarylmethane Series
Authors: Massa Werner , Kämpchen Thomas , Müller Johann , Pindur Ulf 
Published: March 2015

Abstract
The structure of tris(1,3-dim ethyl-2-indolyl)methane (1) as a model compound for C3-skeleton symmetric trishetaryl-methanes is elucidated by X-ray diffraction and temperature dependant 1H NMR spectroscopy. The results demonstrate, that 1 adopts a chiral C3-propeller conformation (P/M-helix) as well in crystal as in solution.
Kristallstrukturen von NaMg2OH(SO3)2 · H2O, NaMn2OH(SO3)2 · H2O , NaFe2OH(SO3)2 · H2O, NaCo2OH (SO3)2 H2O und NaZn2OH(SO3)2H2O/ Crystal Structures of NaMg2OH(SO3)2-H2O, NaMn2OH(SO3)2 · H2O,NaFe2OH(SO3)2H2O, NaCo2OH(SO3)2 · H2O, and NaZn2OH(SO3)2 · H2O
Authors: Buchmeier Willi , Engelen Bernward , Lutz Heinz Dieter 
Published: March 2015

Abstract
The crystal structures of the isotypic hydroxosulfitometalates NaM2OH(SO3)2 ·1H2O with M = Mg, Mn, Fe, Co, and Zn were determined by means of X-ray single crystal data (triclinic space group P1̄ - Qi
1, Z = 2). The final R for the 2223, 2496, 2440, 1461, and 3433 observed reflections are 0.043, 0.068, 0.025, 0.055, and 0.028, respectively. The bivalent metal ions (three types) are octahedrally coordinated by the oxygen atoms of adjacent SO3
2- ions (two types, both monodentate), OH- groups, and water molecules. The arrangement of the two OH- groups is trans, and of OH- and H2O cis with respect to the octahedral coordination. The mean metal oxygen distances are in the order M - OH2 > M -OSO2
2-> M - OH . The MO6 -octahedra are both vertex and edge sharing, forming two-dimensional networks parallel to (010), which are connected via hydrogen bonds. The water molecules form strong, linear, nearly symmetric (mm 2) hydrogen bonds to SO3
2- ions, the hydroxide ions weak bonds to water molecules.
Darstellung und Eigenschaften von und Reaktionen mit metallhaltigen Heterocyclen, LII. Bindungs- und Strukturverhältnisse von Phosphidocobaltaten in Lösung und im festen Zustand/ Preparation and Properties of, and Reactions with, Metal-Containing Heterocycles, LII. Bonding and Structural Conditions of Phosphidocobaltates in Solution and in Solid State
Authors: Lindner Ekkehard , Neese Petra 
Published: March 2015

Abstract
Reduction of [(OC)3CoPPh2]n (1a ) with excess sodium granules affords [(OC)3CoPPh2]Na2 (3a) in solution as well as in solid state. However, in analogous reactions of [(OC)3CoPR2H]2 (1b : R = C6H11; 1c : R = t-Bu) with excess sodium granules the monovalent anionic complexes [(OC)3CoPR2H]Na (2b, c) are obtained in THF solution. 2b, c cannot be isolated in solid state. After removal of THF from their solutions the purified residues were identified by elemental analyses as [(OC)3CoPR2]Na2 (3b, c). Addition of buthyllithium to THF solutions of 3a, 2b, c gives rise to differently solvated complexes 3a*-c* which are transformed to [(OC)3CoPR2]M2 (M = N a, Li; 3 a′-c′). The course of the reactions and the products are controlled IR and 31PNMR spectroscopically. 2b, c and 3a, b′, c′ were trapped with (H3CO)2SO2 and CH2X2(X = Cl, I) yielding H3CCo(CO)3PR2H(6b, c), H3CCo(CO)3PR2CH3 (4a - c ) and [xxx] (5a, b), respectively.
Darstellung und Kristallstruktur von TI3AgTe2 / Preparation and Crystal Structure of TI3AgTe2
Authors: Klepp Kurt O. 
Published: March 2015

Abstract The new compound Tl3AgTe2 was prepared by the reaction of Tl5Te3, Ag and Te at 550 °C, followed by slow cooling of the melt. It forms black crystals of metallic lustre which decompose by the influence of humidity. Tl3AgTe2 is monoclinic, space group P21/c, with a = 11.020(5), b = 7.427(2), c = 9.888(3) Å , β = 116.62(4)°, Z = 4. The crystal structure was determined from four-circle diffractometer data and refined to a conventional R of 0.083 for 1015 observed reflections.
Tl3AgTe2 crystallizes with a new structure type, characterized by infinite layers, 2
∞[AgTe2], running along (100), which are separated from each other by thallium atoms. The layers are built up by pairs of edge sharing AgTe4-tetrahedra linked together by common Te atoms according to 2
∞[Ag (Te)Te3/3].
The crystal structure is based on an arrangement of distorted c.p. tellurium layers, stacked along [010] (stacking sequence h2). All octahedral voids are occupied by Tl-atoms, Ag-and Tl-atoms are regularly distributed over the tetrahedral sites.
Kristallographisches und spektroskopisches Verhalten einiger gemischter Phosphat/Vanadat-Fluoroapatite / Crystallographic and Spectroscopic Behaviour of Some Mixed Phosphate/Vanadate Fluoroapatites
Authors: Lavat A. E. , Etcheverry S. B. , Baran E. J. 
Published: March 2015

Abstract
Crystallographic data for mixed phosphate/vanadate fluoroapatites of the type M10(PO4)6−x(VO4)xF2 (with M = Ca, Sr, Ba and x = 1-3) have been obtained from X-ray powder data. The only structural effect observed is a continuous increase of unit cell dimensions with increased vanadate incorporation. The IR and Raman spectra show that the VO4
3− incorporation has a negligible effect on the strength of the P - O bonds, although a small bond weakening for both tetrahedral oxoanions is observed as the unit cell volume increases. The results are comparable to those reported earlier for similar mixed hydroxyapatites and suggest that the fluoroapatite lattice can be considered as a good “model” for the vertebrate hard tissues.
Synthesis of Au2S and Au2S3 Using H2S, Short-Chain and Ring-Structured Sulfur as Sulfur Sources
Authors: Senftle F. E. , Wright D. B. 
Published: March 2015

Abstract
To determine which of the two known gold sulfides (containing either mono- or trivalent gold) are formed by reacting trivalent gold with differnt allotropes of sulfur, experiments were made using three different sources of sulfur. When trivalent gold in the form of Au2(SO4)3 in concentrated acid is reacted with electrolytically formed short-chain sulfur, monovalent gold sulfide (Au2S) is formed. If hydrogen sulfide gas reacts with the same solution, trivalent gold sulfide (Au2S3) is produced. Alternatively, if ordinary a-sulfur (ring structure) is used, a 50/50 mixture of Au2S and Au2S3 is formed. The synthesis procedure for the two gold sulfides is substantially simpler than previously reported methods of preparation
Sila-Pharmaka, 35. Mitt. [1] Sila-Substitution des Akarizids Fenbutatinoxid und einiger seiner Derivate: Synthese und Eigenschaften von Hexakis[(dimethylphenylsilyl)methyl]distannoxan und Tris[(dimethylphenylsilyl)methyl](1,2,4-triazoI-l-yl)stannan / Sila-Pharmaca, 35th Communication [1] Sila-Substitution of the Acaricide Fenbutatinoxide and Some of its Derivatives: Synthesis and Properties of Hexakis[(dimethylphenylsilyl)methyl]distannoxane and Tris[(dimethylphenylsilyl)methyl]1,2,4-triazol-l-yl)stannane
Authors: Tacke Reinhold , Link Matthias , Joppien Hartmut , Ernst Ludger 
Published: March 2015

Abstract
Starting from SnCl4. hexasila-fenbutatinoxide (2b) [a silicon analogue of the acaricide fenbutatinoxide (2b)] and its derivatives lb and 3b were prepared (SnCl4 → 1b → 2b -> 3b). The distannoxanes 2a and 2b were found to react very easily with H2O to give the corresponding stannols 4a and 4b, respectively. In solution (C6D6 or CDCl3) the equilibria 2a/2b + H2O ⇄ 2 4a/4b were observed (1H NMR). With regard to the system 2a/4a/H2O, this observation is at variance with an earlier report in which the sterically bulky neophyl substituents [C6H5(CH3)2CCH2] are said to prevent the condensation of 4a to give 2a. - 1b -3b were found to be potent acaricides showing activities similar to those of their carbon analogues 1a -3a (test organisms: adult females of Tetranychus urticae Koch)
Elementorganische Verbindungen mit ö-Phenylenresten, XI [1] 3:l-Komplexe von Hexachlor-dibenzo-p-dioxin-2,3-chinon mit 2,3,7,8-Tetramethoxythianthren und -selenanthren / Organometallic Compounds with o-Phenylene Substituents, Part XI [1] 3:1 Complexes of Hexachloro-dibenzo-p-dioxin-2,3-quinone with 2,3,7,8-Tetram ethoxythianthrene and Selenanthrene
Authors: Hinrichs Winfried , Berges Peer , Klar Günter 
Published: March 2015

Abstract
The title com pounds can be isolated from concentrated solutions of 2,3,7,8-tetramethoxy thianthrene or selenanthrene and tetrachloro-o-benzoquinone as dark blue crystals. Bond distances and bond and folding angles of the components indicate these com pounds to be charge transfer complexes in which the tetramethoxy thianthrene or selenanthrene molecules act as donors (D), the hexachloro-dibenzo-p-dioxin-2,3-quinone molecules as acceptors (A). In the asymmetric units of the two isostructural complexes an acceptor, a donor and another acceptor molecule are arranged parallel to each other. A third acceptor molecule is placed at the front side of the A1 ,D ,A2-arrangement. In the crystal the A1, D, A2,(A3) units are connected by centres of symmetry leading to A1 ,D ,A2 , A1',D',A2', . . . stacks in which the aryl rings of the halves of the molecules are equidistant and parallel to each other. The mean distances between the rings are 340 and 345 pm, respectively
Über Erdalkalimetallverbindungen des 1,1-Dicyanoethylen-2,2-dithiolats, III+ Die Kristallstruktur von SrS2C4N2 · 5 H2O / On Alkaline-Earth Metal Compounds of 1 ,1-Dicyanoethylene-2 ,2 -dithiolate, III+ Crystal Structure of SrS2C4N2 · 5 H2O
Authors: Hummel Hans-U. , Wolf C. 
Published: March 2015

Abstract
By reaction of CS2 with maleonitrile in presence of sodiumethanolate in ethanol, Na2S2C4N2 is obtained. SrS2C4N2 · 5 H2O was synthesized by reaction of Sr(NCS)2 with Na2S2C4N2 in ethanol. It crystallizes monoclinically, space group P21/c, with a = 9.201(2), b = 9.990(6), c = 14.605(5) Å, β = 122.3(3)°, Z = 4. The compound is isotypical with CaS2C4N2 · 5 H2O. A structural model based on equivalent metal positions was refined to R = 0.057. The crystal structure contains layers of nearly planar [S2C = C(CN)2]2- anions held together by interspersed Sr2+ cations in a tricapped trigonal prismatic surrounding of 6O and 3N atoms. The S atoms of the ligand are not included in the coordination sphere of Sr2+ but are involved in several O - H···S hydrogen bonds.
Kubische Cyanomercurate NR4MHg(CN)4 (R = Et, Pr; M = Li, Na, K, Cu) mit Alumosilikatstruktur/On Cubic Cyanomercurates NR4MHg(CN)4 (R = Et, Pr; M = Li, Na, K, Cu) with Alumosilicate Type Structure
Authors: Thiele Gerhard , Großmann Joachim , Pürzer Albert Wolfgang 
Published: March 2015

Abstract
Quaternary Cyanomercurates NR4
+[MHg(CN)4]- with R = Et, Pr; M = Li, Na, K, Cu, obtained by reactions of NR4CN . MCN and Hg(CN)2 in polar solvents, are dimorphous. The low temperature modifications are tetragonal with a space group I4̄, the high temperature forms are cubic with the space group F4̄3m . Reversible phase transitions were studied by DSC, Raman spectroscopy and X-ray diffraction. They are of first order and of displacive character. The X-ray structure determinations of the cubic forms of NEt4MHg(CN)4 with M = Na, Li showed tetra­hedral M (NC)4- and Hg(CN)4- groups connected by linear M -NC -Hg bridges to give three-dimensional frameworks o f a cristobalite type structure and with cavaties, in which the NEt4
+ cations are located.
Tribromide Salts of the Organic Donor Tetra(methylthio)tetrathiafulvalene, [TTM-TTF]+(Br3
-) and [TTM-TTF]2+(Br3
-)2
Authors: Endres Helmut 
Published: March 2015

Abstract
The 1:1 and 1:2 phases (TTM -TTF)Br3 and (TTM -TTF)(Br3)2, TTM -TTF = tetra(methylthio)tetrathiafulvalene, C10H12S8, have been crystallized by diffusion of bromine vapour into solutions of the donor. The 1:1 salt is monoclinic, P 21/n, a = 7.587(2), b = 11.424(3), c = 23.145(8) Å , β = 95.80(3)°, V = 1997 Å3, Z = 4, Mr = 628.45, dc = 2.09 g cm-3, final Rw = 0.028 for 912 reflections. The 1:2 salt is monoclinic, C2/m, a = 11.510(3), b = 17.039(4), c = 9.770(3), β = 141.62(1)°, V = 1190 Å3, Z = 2, Mr = 868.16, dc = 2.42 g cm-3, final Rw = 0.029 for 899 reflections. Diadic stacks of the monopositive donor cations are found in the 1:1 salt, whereas the dipositive cations in the 1:2 salt form sheets via short intermolecular S···S contacts. A relation between bond lengths and charge is indicated.