bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneity in Glacier response from 1973 to 2011 in the Shyok valley, Karakoram, India
Authors: Bhambri R. , Bolch T. , Kawishwar P. , Dobhal D. P. , Srivastava D. , Pratap B.
Published: July 2012

Abstract. A glacier inventory for the Shyok and Chang Chenmo basins was generated for the year 2002 using semi-automated methods based on Landsat ETM+ and SRTM3 DEM data. Glacier change analysis was carried out for 134 glaciers based on Hexagon KH-9 (years 1973, 1974) and Landsat TM/ETM+ (1989, 2002 and 2011) images. The 2002 inventory contains 2123 glaciers with an area of 2977.9±92.2 km2 in the entire study area including Shyok (1605 glaciers; area 2499±77.4 km2) and Chang Chenmo basins (518 glaciers; area 478.7±14.8 km2). Out of 2123 glaciers, only eight glaciers have higher elevation ranges than 2000 m. On average, the glacier area in Chang Chenmo basin exhibited no changes during the study period. However, individual absolute glacier area changes varied from −0.7±0.03 km2 to +0.2±0.01 km2 between 1973 and 2011. 10 glaciers exhibited an area increase of 1.7±0.07 km2 in total while 36 glaciers lost about total 1.8±0.07 km2. The glacier area decreased by 11±0.47 km2 from 1973 to 1989 in the Shyok basin whereas an increase in area of 8.2±0.33 km2 was observed during 1989–2002. The area has further increased by 5.6±0.21 km2 from 2002 to 2011 in the respective basin. This individual glacier response heterogeneity can be attributed to surging and possibly due to decreased temperature in last decades. However, further detailed studies are needed to understand glacier surge mechanism and the possible mass gain.
Radioactive Potential of Zirconium-dioxide Used for Dental Applications
Authors: Bavbek Andac Barkin , Özcan Mutlu , Eskitascioglu Gürcan
Published: July 2012

Purpose

The purpose of this study was to investigate the possible radioactive potential of zirconium dioxide (ZrO2) dental ceramics. Such information is necessary since they became an integral part of routine prosthetic rehabilitations and devoid of scientific information about their radioactivity creates some concern in the dental community.

Methods

Four different types of commercial ZrO2 ceramics, namely Lava, Cercon, ICE Zirkon, and Everest Bio ZS were investigated before and after the sintering process. Sintering temperatures were applied according to each manufacturer's instructions. The compositions of the presintered and sintered specimens were analyzed using x-ray fluorescence spectrometer (XRF). Concentrations of the elements and compounds were also measured by this method. Determination of radioactivity continued with gamma-spectrometry measurements and gross alpha/beta analyses.

Results

The activity of gamma and gross alpha/beta was below minimum detection limits (MDL) for presintered and sintered ZrO2. The MDLs of gross alpha/beta counting system were 0.02 Bq/g and 0.01 Bq/g for alpha and beta radioactivity, respectively. The sintering process played only a minor role in the composition of the compounds.

Conclusions

Radioactivity of the ZrO2 ceramics studied showed negligible radionuclide activity that can be considered lower than many hazardous radioactive appliances in our environment.
A prognostic score based on clinical factors and biomarkers for advanced non-small cell lung cancer
Authors: Trapé Jaume , Montesinos Jesus , Catot Sílvia , Buxó Josep , Franquesa Josefina , Sala Maria , Domenech Montserrat , Sant Francesc , Badal Josep M , Arnau Anna
Published: July 2012

Aims

The objective of the present study is to determine the prognostic value of clinical variables and biomarkers in patients with advanced stages of NSCLC and establish a prognostic classification of these patients.

Methods

For 135 patients with advanced NSCLC we determined their clinical variables and their levels of CEA, CA 125, CYFRA 21–1, albumin, LDH, erythrosedimentation and leukocytes.

Results

Multivariate analysis identified PS (ECOG) >1, metastases, no anti-neoplastic treatment, CA 125 >35 U/mL, CYFRA 21–1 >3.3 ng/mL and leukocytes >10'000/μL, as independent prognostic factors for survival. Patients were classified into 3 groups according to the number of adverse prognostic factors (APF). One point was assigned for each APF, except for chemotherapy treatment. Patients with 0–1 APF represented our reference group: patients with 2–3 APF had HR=2.7 (95% CI: 1.5–4.6), while patients with 4–5 APF had HR=8.8 (95% CI: 4.6–16.8). This “score” maintained the differences between risk groups both in patients who received antineoplastic treatment and in those who did not.

Conclusion

The application of a score that includes clinical data and biomarkers may improve the prognostic classification of NSCLC patients.
Evaluation of Association between Vaginal Infections and High-Risk Human Papillomavirus Types in Female Sex Workers in Spain
Authors: Rodriguez-Cerdeira C. , Sanchez-Blanco E. , Alba A.
Published: July 2012

Background. Infection with and persistence of high-risk human papillomavirus (HR-HPV) are the strongest risk factors for cervical cancer. In addition, other genital microorganisms may also be involved in the progression of HPV-associated lesions. Objetive. To evaluate the association of the vaginal microbiota (Candida spp., Trichomonas vaginalis, and bacterial vaginosis) with HR-HPV infection in Spanish female sex workers (FSWs). Methods. This cross-sectional study involved 208 (FSWs; age, 18–49 years) who visited a sexually transmitted infection (STI) information and prevention center (SERGAS) between January 2010 and December 2011. Face-to-face interviews were carried out. Cervical and vaginal samples were examined for human papillomavirus (HPV), Trichomonas vaginalis, Candida spp., and microorganisms related to bacterial vaginosis (BV). Results. HR-HPV was found to be significantly associated with BV in FSWs with positive results for HPV16-related types (31, 33, 35, and 52). T. vaginalis was isolated in FSWs with the following HR-HPVs: 18, 45, 66, and 68. Candida spp. were isolated only in FSWs with HPV 18-positive infection. Conclusion. We demonstrate a significant prevalence of HR-HPVs in FSWs with disturbances in the vaginal microbiota.
miR-320 Regulates Glucose-Induced Gene Expression in Diabetes
Authors: Feng Biao , Chakrabarti Subrata
Published: July 2012

miRNAs play an important role in several biological processes. Here, we investigated miR-320 in glucose-induced augmented production of vasoactive factors and extracellular matrix (ECM) proteins. High glucose exposure decreased the expression of microRNA 320 (miR-320) but increased the expression of endothelin 1 (ET-1), vascular endothelial growth factor (VEGF), and fibronectin (FN) in human umbilical vein endothelial cells (HUVECs). Transfection of miR-320 mimics restored ET-1, VEGF and FN mRNA, and protein expression in HUVECs treated with high glucose. Furthermore, miR-320 mimic transfection reduced glucose-induced augmented production of ERK1/2. Data from this study indicates that miR-320 negatively regulates expression of ET-1, VEGF, and FN through ERK 1/2. Identification of such novel glucose-induced mechanism regulating gene expression may offer a new strategy for the treatment of diabetic complications.
Diffuse Malignant Mesothelioma
Authors: Oviedo Sergio Pina , Cagle Philip T.
Published: July 2012

Diffuse malignant mesothelioma (DMM) is an uncommon cancer with great clinical significance because it currently remains an incurable disease, and most patients die within months after diagnosis. Although DMM incidence is leveling off or decreasing in developed countries because of the strict control of asbestos use, it is increasing in countries without adequate asbestos control. In some settings, benign, reactive mesothelial hyperplasias and organizing pleuritis can be difficult to differentiate from DMM and vice versa, and the variety of DMM's histopathologic features generates an extensive list of differential diagnoses with other malignancies, particularly, metastatic malignancies, which are more frequent in the pleura than are primary malignancies. These two issues are the topic of discussion in this review, along with a brief presentation of a case of DMM that presented in a 66-year-old man with recurrent, right pleural effusions, and in whom, diagnosis of DMM had not been suspected clinically, radiographically, surgically, grossly, or initially, on frozen section. It was not until focal invasion into the skeletal muscle was discovered on permanent sections that a diagnosis of DMM could be established.
Metaplastic Carcinomas of the Breast: Diagnostic Challenges and New Translational Insights
Authors: Rungta Shilpa , Kleer Celina G.
Published: July 2012

Comprising less than 1% of invasive carcinomas of the breast, metaplastic carcinomas are a heterogeneous group of malignant tumors in which part or all of the carcinomatous epithelium is transformed into a nonglandular (metaplastic) growth process. Metaplastic carcinomas with a low-grade spindle cell component resembling fibromatosis, as in our present case, are worthy of particular note because they are infrequent, difficult to recognize, and have a high risk of local recurrence. The differential diagnosis of metaplastic carcinomas depends on the degree of atypia observed in the tumor and includes exuberant scars, fibromatosis, nodular fasciitis, myofibroblastomas, pseudoangiomatous stromal hyperplasia, acute and chronic abscess with fat necrosis, malignant phyllodes tumor, and primary or metastatic sarcoma. Limited studies done on the molecular pathology of metaplastic carcinomas show that activation of the Wnt signaling pathway is common in these tumors and that approximately 70% of metaplastic carcinomas show EGFR gene amplification and overexpression. This may have treatment implications because they may lead to targeted treatment for patients with metaplastic carcinomas.
High-Grade Carcinomas Involving the Renal Sinus: Report of a Case and Review of the Differential Diagnosis and Immunohistochemical Expression
Authors: Young Allison , Kunju Lakshmi P.
Published: July 2012

We report the case of a high-grade carcinoma involving the kidney in a young male with renal vein thrombosis and review the differential diagnosis and immunohistochemical workup. High-grade neoplasms involving the renal sinus include collecting duct carcinomas (CDCs), renal medullary carcinomas (RMCs), invasive high-grade urothelial carcinoma (UC) of the upper urinary tract, clear cell renal cell carcinoma, and type 2 papillary renal cell carcinoma. Distinguishing UC from CDC and RMC is problematic in small biopsy samples. The diagnosis of CDC (a rare, aggressive subtype of renal cell carcinoma) is challenging and requires the exclusion of UC. Renal medullary carcinoma is characterized by an appropriate clinical setting and consistent loss of nuclear expression of integrase interactor 1 (INI-1). A panel consisting of p63, paired box gene 8 (PAX8), and INI-1 is most optimal in distinguishing UC from CDC and RMC. A subset of urothelial carcinoma of upper urinary tract may be positive with PAX8.
External and Internal Influences on Muscle Pathology
Authors: McKeever Paul E. , Camelo-Piragua Sandra , Dowling James
Published: July 2012

Three cases of different types of neuromuscular diseases demonstrate different muscle responses to external stress or intrinsic muscle abnormalities. The first muscle biopsy shows stenosis of its vessels causing acute muscle ischemia, stress from an external vascular disease. The muscle response is similar to the cellular necrosis seen in primary muscle diseases (myopathies), but the histologic pattern is more focal than most myopathies. The second muscle biopsy demonstrates the effects of external motor nerve injury or disease causing groups of muscle fibers to atrophy. If a nerve reinnervates the muscle, it changes the fiber types in distinct patterns. The third muscle biopsy shows an intrinsic muscle abnormality causes chronic failure of the muscle fibers to thrive and repeated attempts by the fibers to regenerate, stimulating other tissue repair processes, like fibrosis, to change the muscle. Depending on the etiologic factor, muscle will respond to internal and external influences in different manners.
Difficulties in teaching electromagnetism: an eight year experience at Pierre and Marie Curie University
Authors: Roussel H. , Hélier M.
Published: July 2012

We will begin by outlining the details of how electromagnetics are taught in the  electrical engineering program offered at Pierre and Marie Curie University (a French example) from the undergraduate to the Masters degree levels.  We will also discuss how our methods are and should be adapted to teach waves propagation without discouraging students.
Ice‐Templated Scaffolds with Microridged Pores Direct DRG Neurite Growth
Authors: Riblett Benjamin W. , Francis Nicola L. , Wheatley Margaret A. , Wegst Ulrike G. K.
Published: July 2012

Successful spinal cord repair is thought to be promoted with hierarchically structured scaffolds. These should combine aligned porosity with additional linear features on the micrometer scale to guide axons across multiple length scales. Such scaffolds are generated through the carefully controlled directional solidification of an aqueous biopolymer solution, followed by lyophilization. Under specific freezing conditions this yields a highly regular and aligned lamellar architecture. This architecture exhibits uniform ridges of controlled height and width on the lamellar surface. These ridges run parallel to the pore axis, serving as secondary guidance features. The ridges are capable of linearly aligning 62.4% of chick dorsal root ganglia neurites to within ±10° of the ridge direction. Notably, neurites sprouting perpendicular to the ridge are guided into alignment with these microridged features.
Dietary acculturation and body composition predict American Mmong children's blood pressure
Authors: Smith Chery , Franzen‐Castle Lisa
Published: July 2012

Objectives:

Determine how dietary acculturation, anthropometric measures (height, weight, circumferences, and skinfolds), body mass index (BMI), and waist hip ratios (WHRs) are associated with blood pressure (BP) measures in Hmong children living in Minnesota.

Methods:

Acculturation was measured using responses to questions regarding language usage, social connections, and diet. Dietary assessment was completed using the multiple‐pass 24‐h dietary recall method on two different days. Anthropometric and BP measurement were taken using standard procedures, and BMI and WHR were calculated. Data analyses included descriptive statistics, ANOVA, and stepwise regression analyses.

Results:

Using stepwise regression analysis, hip circumference (HC) predicted boys' systolic (S)BP (R2= 0.55). For girls' SBP, mid‐upper arm circumference, WHR, low calcium consumption, and height percentile jointly explained 41% of the total variation. Mid upper arm circumference (MAC) and carbohydrate consumption predicted 35% of the variance for boys' diastolic (D)BP, and HC, dairy consumption, and calcium intake predicted 31% of the total variance for girls' DBP. Responses to dietary acculturation questions revealed between group differences for breakfast with half of the younger Born‐Thailand/Laos (Born‐T/L) consuming mostly Hmong food, while at dinner Born‐US consumed a mixed diet and Born‐T/L were more likely to consume Hmong food.

Conclusion:

Dietary acculturation and body composition predict Hmong children's BP. Am. J. Hum. Biol. 2012. © 2012 Wiley Periodicals, Inc.
An investigation of cure and thermal stability of poly(amide‐amidic acid) modified tetraglycidyl 4,4′‐diaminodiphenylmethane/4,4′‐diaminodiphenylsulfone
Authors: Chen Haiming , Lv Renguo , Liu Pei , Wang Hongyan , Huang Zhongyuan , Huang Ting , Li Tongsheng
Published: July 2012

In this work, poly(amide‐amidic acid) (PAA) was used to modify tetraglycidyl 4,4′‐diaminodiphenylmethane (TGDDM)/4,4′‐diaminodiphenylsulfone (DDS) system. Results of non‐isothermal differential scanning calorimetry analysis indicated that PAA played a role of catalyst during the process of the curing reaction. The curing mechanism was studied by Fourier transform infrared spectroscopy, showing that the PAA acted as a co‐curing agent in the system. The glass transition temperature decreased firstly and then increased with the increase of the PAA content. PAA equally rendered TGDDM more fire resistant with higher char yield. On examining the fracture surface morphology using scanning electron microscopy, it was observed that there was no obvious phase separation when the content of PAA was less than 20 phr (per hundred weight of TGDDM/DDS resin), however, phase separation was observed when the content of PAA was 25 and 30 phr. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
The effect of morphology on the corrosion inhibition and mechanical properties of hybrid polymer coatings
Authors: Singh‐Beemat Jaspreet , Iroh Jude O.
Published: July 2012

The durability and mechanical properties of epoxy ester coatings and films has been improved by blending with rigid aromatic polyurea (PU). The interaction of PU and epoxy ester was enhanced by coupling the polymers with polymethylhydrosiloxane. The reactions between various entities are analyzed by Fourier transform infrared spectroscopy and the change in physical and mechanical properties are studied by a dynamic mechanical analyzer. The corrosion resistance of the hybrid coatings was measured by direct current polarization method, direct current polarization (DCP). The addition of polymethylhydrosiloxane enhances the corrosion properties in the hybrid coatings. The surface morphology was analyzed by scanning electron microscopy. The glass transition temperature of the films increases with increasing PU concentration and a wide glass rubber transition range for hybrid coatings was achieved which confirms the higher impact strength of the hybrid coatings and films. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Dielectric and electrical properties of an organic device containing benzotriazole and fluorene bearing copolymer
Authors: Yildiz Dilber Esra , Apaydın Dogukan Hazar , Toppare Levent , Cirpan Ali
Published: July 2012

Dielectric and electrical properties of a benzotriazole and fluorene copolymer were investigated using current‐voltage (I–V), capacitance‐voltage (C–V), and conductance–voltage (G/w–V) measurements at room temperature. The electrical parameters, barrier height (φBo), and ideality factor (n) obtained from the forward bias LnI‐V plot were found as 0.453 eV and 2.08, respectively. The Rs values were found as 2.20,  2.12,  1.90 Ω using dV/dLnI versus I, H(I) versus I and F(V)‐V plots, respectively. The dielectric constant (ε′), the dielectric loss (ε″), and the ac electrical conductivity ( σac) are a strong function of voltage and frequency. Decrease in ε′ and ε″ values with increasing frequency was observed. On the other hand, the increase of σac with increasing frequency was observed. Experimental results show that the conjugated copolymer plays an important role in the values of barrier height, ideality factor, series resistance, and dielectric parameters. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effects of novel thermotropic liquid crystalline polyester with aryl‐ether linkages on the processability and properties of poly(ether ether ketone)s fibers
Authors: Wu Ting , Liu Pengqing , Wang Xiao , Zeng Luxian , Ye Guangdou , Xu Jianjun
Published: July 2012

A series of composite fibers based on poly(ether ether ketone)s (PEEK) and a novel thermotropic liquid crystalline polyetherarylates (PEAR) with the aryl‐ether linkages, have been prepared by melt spinning. The impact of PEAR on PEEK is investigated by rheological measurements, differential scanning calorimetry, thermal gravimetric analysis, wide angle X‐ray diffraction and scanning electron microscope, orientation degree test and mechanical properties test, etc. The results show that the flowing curves of the blends can be divided into three regions: the first shear thinning region, the shear thickening region, and the second shear thinning region; meanwhile, the PEAR can function as a processing aid by reducing the viscosity of PEEK, thus the processing can be carried out at relatively low temperatures. Although, they are partially compatible, the mechanical properties of the post‐treatment fibers have been improved by 14% after adding 2% PEAR to PEEK. The crystallinity of the as‐spun fibers increases from 22.47 to 42.10%, suggesting that PEAR can act as nucleating agent. Regretfully, both of the initial degradation temperatures and the maximal degradation temperatures decrease with the increase of the PEAR content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis and Pharmacological Investigation of 2‐(4‐Dimethylaminophenyl)‐3,5‐disubstituted thiazolidin‐4‐ones as Anticonvulsants
Authors: Senthilraja Manavalan , Alagarsamy Veerachamy
Published: July 2012

A new series of 2‐(4‐dimethylaminophenyl)‐3‐substituted thiazolidin‐4‐one‐5‐yl‐acetyl acetamides/benzamides were synthesized by the nucleophilic substitution of 3‐substituted‐2‐(4‐dimethylaminophenyl)‐thiazolidin‐4‐one‐5‐yl‐acetylchloride with acetamide and benzamide. The starting material 3‐substituted‐2‐(4‐dimethylaminophenyl)‐thiazolidin‐4‐one‐5‐yl‐acetylchloride was synthesized from 3‐substituted‐2‐(4‐dimethylaminophenyl)‐thiazolidin‐4‐one‐5‐yl‐acetic acid, which in turn was prepared by one‐pot reaction of amino component, p‐dimethylamino benzaldehyde and mercapto succinic acid. The title compounds were investigated for their anticonvulsant activities; among the test compounds, compound 2‐(4‐dimethylaminophenyl)‐3‐phenylamino‐thiazolidine‐4‐one‐5‐yl‐acetylbenzamide (14) emerged as the most active compound of the series and as moderately more potent than the reference standard diazepam.
Synthesis and Discovery of Novel Pyrazole Carboxamide Derivatives as Potential Osteogenesis Inducers
Authors: Lv Hong‐Shui , Han Qian‐Qian , Ding Xiao‐Ling , Zhou Ji‐Liang , Yang Pi‐Shan , Miao Jun‐Ying , Zhao Bao‐Xiang
Published: July 2012

A series of novel N‐aryl‐3‐aryl‐1‐arylmethyl‐1H‐pyrazole‐5‐carboxamide derivatives 4a–l was synthesized by the reaction of 3‐aryl‐1‐arylmethyl‐1H‐pyrazole‐5‐carbonyl chloride with substituted aniline in good to excellent yields. Structures of the compounds were determined by IR, 1H NMR, and HR‐MS spectroscopy. The molecular structure was confirmed by the X‐ray crystal analysis of one compound (4j) that was prone to crystallization. These compounds were used to induce mouse osteoblast precursors MC3T3‐E1 into osteoblasts and the induction was assessed by alkaline phosphatase (ALP) activity and the gene expression of bone sialoprotein (BSP). The results showed that the compounds 4a–d, 4g, 4h, and 4k could increase the ALP activity in comparison with the negative control group and compound 4h was the most effective one which could induce osteogenesis. Furthermore, mRNA expression of BSP which is a marker of osteogenesis was up‐regulated by the compound 4h.
Evaluation of the willingness for cadaveric donation in Greece: A population‐based study
Authors: Halou Heidi , Chalkias Athanasios , Mystrioti Dimitra , Iacovidou Nicoletta , Vasileiou Panagiotis V.S. , Xanthos Theodoros
Published: July 2012

Despite the importance of body donation for medical education and the advancement of medical science, cadaveric donation remains suboptimal worldwide. The purpose of this study was to evaluate the willingness of body donation in Greece and determine the characteristics of donors. This cross‐sectional questionnaire survey was conducted from January to June 2011. A specially designed questionnaire was distributed to 1,700 individuals who were randomly selected from five major Greek cities. It was found that higher educational levels (P = 0.002), annual family income below 30,000 Euros (P = 0.001), guaranteed employment status (P = 0.02), and the presence of comorbid conditions (P = 0.004) seemed to affect potential donors' willingness for cadaveric donation. Those with strong religious beliefs were found to be unwilling to donate their bodies to medical science. Interestingly, the majority of participants who believed that hospitalized patients are deceived or are used for harmful experiments were willing to become whole body donors (P = 0.043). In Greece, the rate of body donation to medical science remains low, and most Greek citizens are not willing to become body donors. Efforts to encourage discussions about whole body donation should be implemented in order to improve current low levels of donation. Anat Sci Educ. © 2012 American Association of Anatomists.
Sliding Mode Control for Swing‐Up and Stabilization of the Cart‐Pole Underactuated System
Authors: Yih Chih‐Chen
Published: July 2012

This paper uses sliding mode control to accomplish the objectives of swing‐up and stabilization of the cart‐pole underactuated system. The features of underactuated systems prohibit direct application of conventional sliding mode control for fully‐actuated systems. In this paper, we design a novel sliding mode control for the cart‐pole underactuated system so that the control goals can be achieved. In addition, by simply changing the parameters of the sliding surface, we use only one sliding mode control scheme to swing up and to stabilize the cart‐pole system. Using the sliding mode dynamics and the internal dynamics, we show that the proposed sliding mode control can swing up the cart‐pole system from the stable equilibrium and can stabilize the system to the unstable equilibrium. Our simulation results on a cart‐pole system demonstrate the feasibility of the proposed sliding mode control. The proposed control schemes, the stability analysis, and the numerical simulation provide a useful guideline for designing the sliding mode control for the cart‐pole underactuated system.
Descriptor Fractional Linear Systems with Regular Pencils
Authors: Kaczorek Tadeusz
Published: July 2012

New classes of descriptor fractional continuous‐time and discrete‐time linear systems with regular pencils are introduced. Electrical circuits are an example of descriptor fractional continuous‐time systems. Using the Caputo definition of the fractional derivative, the Weierstrass regular pencil decomposition and Laplace transformation the solution to the state equation of descriptor fractional linear systems is derived. It is shown that every electrical circuit is a descriptor fractional systems if it contains at least one mesh consisting of branches with only ideal supercondensators and voltage sources, or at least one node with branches containing supercoils. Using the Weierstrass regular pencil decomposition the solution to the state equation of descriptor fractional discrete‐time linear systems is derived. A method for decomposition of the descriptor fractional linear systems with regular pencils into dynamic and static parts is proposed. The considerations are illustrated by numerical examples.
Mikroparakristalle, die Welt zwischen Kristallinem und Amorphen
Authors: Hosemann R. , Baltá‐Calleja F. J.
Published: July 2012

Ein neuartiger Gitterkomplex, mathematisch definiert durch ein dreidimensionales Faltungspolynom, kombiniert mit dem empirisch gefundenen α*‐Gesetz, erschließt die Struktur der kondensierten Materie jenseits der Kristalle bis herab zu den Gasen. An Beispielen aus Biophysik, Polymerphysik, Kolloidphysik und an Metallschmelzen wird kurz skizziert, wie einheitlich sich das Erscheinungsbild der Atom‐und Kolloidstrukturen mit einigen neuen statistischen Parametern darstellen läßt.
Theoretical Study of Inhomogeneous Radical Reactions. Application to the Pulse Radiolysis of Arenediazonium Salt Solutions
Authors: Naumann W. , Brede O. , Mehnert R. , Becker H. G. O.
Published: July 2012

A rate equation for reactions of transient radicals in radiation chemistry is presented where the radical recombination is a second‐order process with a rate coefficient depending on the structure of the initially inhomogeneous distribution of the reactants. For a Gaussian distribution in spurs this rate coefficient can be reduced to the well‐known rate coefficient of a „homogeneous”︁ diffusion‐controlled reaction corrected by the ratio of the local concentration in the spurs to the average concentration. The derived formalism is used for interpreting the reactive behaviour of transient arenediazo radicals observed in the pulse radiolysis of arene diazonium salts in a mixture of tert.‐butanol/water. Evidence for the inhomogeneous kinetics of the arenediazo radicals was obtained from the unusual behaviour of the half‐life times of radical recombination in dependence on pulse dose and salt concentration.
Electrostatic Focusing in Micellar and Microelectrode Kinetic Processes
Authors: Dung Mei Hsu , Knox Donald G. , Kozak John J.
Published: July 2012

In this paper we present a detailed characterization of the electrostatic environment of a charged organizate in order to determine the importance of field effects in influencing micellar and microelectrode kinetic processes. The electrostatic potential and associated ion distributions in the vicinity of a charged organizate are determined using a potential approach and, in particular, one based on a (previously reported) generalization of Poisson‐Boltzmann theory. The role of organizate size and geometry, and the importance of dielectric saturation, ionic strength and different assumptions on the behavior of the surface potential (boundary conditions) in influencing the potentials and ion distributions are studied. These calculations and the trends observed cast light on the general problem of micellar/micro‐electrode catalysis and, as well, lead to a number of specific results: we are able to place a lower bound on the effective size of a „microelectrode”︁ particle, colloidal dispersions of which have been used in the recent hydrogen evolution studies of Grätzel and coworkers, and Henglein.
Proton Conductivity of Simple Ionic Hydroxides Part II: In Situ Formation of Water Molecules Prior to Dehydration
Authors: Wengeler H. , Martens R. , Freund F.
Published: July 2012

The formation of transitory HOH species in hydroxide lattices prior to dehydration was studied by thermally stimulated depolarisation, TSDp, and by high temperature infrared spectroscopy. Adsorbed H2O give regular TSDp maxima. Protonic space charge clouds, assigned to excess protons H* and defect protons H1, give inverted TSDp effects. At the temperature of the maximum of the proton conductivity the charge carrier concentration is of the order of 1013 mol−1 which corresponds to the expected Boltzmann occupancy in the conduction band. Excess protons H* temporarily trapped from the space charge clouds on lattice OH− sites form H2O molecules, visible in the IR spectrum, which redissociate at room temperature.
Effect of molecular shape on the excess volumetric properties of cycloalkane + n‐alkane mixtures
Authors: Siddiqi M. A. , Kohler Friedrich
Published: July 2012

Excess volumes vE are reported for mixtures of cis‐ and trans‐1,4‐dimethylcyclohexane + n‐heptane, n‐decane, and n‐tetradecane at 293.15 and 313.15 K. The measurements were performed using a vibrating tube densimeter. As expected from previous measurements on methylcycloalkanes, mixtures of the more planar trans‐1,4‐dimethylcyclohexane exhibit a more negative vE than those of the cis‐compound. This effect increases with the chain length of the alkane.
Zur Dynamik des Aggregationsverhaltens zweikettiger ionogener Tenside
Authors: Bauernschmitt D. , Hoffmann H. , Platz G.
Published: July 2012

The micelle formation in aqueous solutions of p‐(6′‐Dodecyl)‐benzenesulfonate (LBS) with the counterions Na+, H2N(CH3)2+, H2N(CH2CH3)3+ and H2N(CH2CH2CH3)2+ was investigated with the aid of relaxation measurements. The existence of small and probably spherical micelles in a concentration range above a first critical micelle concentration could be shown. At higher concentrations the association leads to larger aggregates or mesophases. In the system H2N(CH2CH2CH3)2‐LBS the second cmc approaches to the value of the first cmc. — The small micelles have a narrow distribution variance σ. The reaction volumes are positive but much smaller than the values which were found on surfactant systems with a single alkyl chain. With the exception of the system H2N(CH2CH2CH3)2‐LBS negative reaction volumes are found in the oligomer region. The values for the relative distribution variance σ2/n were obtained from the concentration dependence of the short relaxation time and from the analysis of the amplitudes of the slow process. The results from both methods are in a good agreement.
The thermal conductivity of binary mixtures of helium and methane at 27.5 °C and pressures up to 13 MPa
Authors: Fleeter R. , Kestin J. , Paul R. , Wakeham W. A.
Published: July 2012

The paper reports new, accurate measurements of the thermal conductivity of mixtures of helium and methane in the pressure range 1–13 MPa at 27.5 °C. The measurements have been carried out in a transient hot‐wire instrument and have an estimated uncertainty of ± 0.2%. — The experimental data as a function of density have been extrapolated to yield reliable values of the zero‐density thermal conductivity of the mixtures. It is found that these experimental data cannot be satisfactorily represented by the existing first‐order kinetic theory formulae using independently determined collision numbers for rotational energy relaxation, unless empirical adjustments are made to certain collision integral ratios occurring in the equations. A recently proposed scheme for the prediction of the density dependence of the thermal conductivity of the mixtures is found to correlate the observed density dependence satisfactorily.
Viskoelastische Tensidlösungen
Authors: Hoffmann H. , Platz G. , Rehage H. , Schorr W. , Ulbricht W.
Published: July 2012

Classical and dynamic light scattering, electric birefringence, kinetic, surface tension, conductivity and rheological measurements were carried out on so called viscoelastic detergent solutions of Cetylpyridiniumsalicylate (CPySal). The results indicate that spherical micelles are formed in these solutions above the critical micelle concentration (cmc) = 1.5 · 10−4 M. From the cmc on the concentration of the micelles increases linearly with the total detergent concentration up to a second critical concentration (cmc11 = 4.5 · 10−4 M). Upon further increase of the total concentration, the concentration of the micelles remains constant and the globular micelles grow to rodlike micelles. The length of the rods increases linearly with the total concentration. The residence time of a detergent molecule in the rod is longer than in the globular micelle. The surface charge density of the rods is smaller than for the spherical micelles. In unstirred solutions the rods are randomly oriented but their center of masses are ordered. As a consequence the rods can rotate freely as long as their main axis is shorter than the mean distance between the aggregates but their translational diffusion is hindered by the existence of lattice like ordering. Shearing of the solution leads to large areas of a new metastable nematic type phase in which the rods are oriented with respect to each other. These oriented domains are the source for the apparent elasticity of the solutions. When the shearing of the solution is stopped, the elasticity decays with rather long time constants that can amount to several minutes. — The complete equilibration of the solution after the system was perturbed by dilution or a change in temperature takes up to several hours.
Relaxation Phenomena in Raman Spectroscopy
Authors: Versmold H.
Published: July 2012

The line shape of Raman bands and its relation to rotational and vibrational relaxation is the topic of the present contribution. First, rotational and vibrational correlation functions are introduced. Depending on the vibrational mode under study the rotational correlation functions contain information on rotations about different molecular axes. The discussion will be restricted to linear and symmetric top molecules, for the first of which “tumbling” and the latter “tumbling” and “spinning” reorientational motions are of importance. Experimental correlation functions for CO2, CH3J, and CH3CN of totally symmetric and degenerate bands are discussed. A comparison of the experimental correlation functions with those obtained from the rotational J‐diffusion model will be given. — Next, vibrational relaxation (dephasing) is considered. Several mechanisms may contribute to vibrational dephasing. The popular Kubo‐model for vibrational relaxation is introduced and the relaxation of the v2‐band of CH3J is discussed in terms of this model. — The paper closes with a brief discussion of interaction induced scattering. Interaction induced scattering contributes to the wings of depolarised Rayleigh (pure rotational Raman) and Raman scattering and therefore is a severe source of error for the short time behaviour of rotational and vibrational correlation functions. Different approaches to correct experimental spectra are considered.
Anomaler Verlauf der Lösungsenthalpien von CF3H und CF3Cl in aromatischen Kohlenwasserstoffen bei Molenbrüchen x < 0,001
Authors: Braun G. , Becker F. , Steiger A.
Published: July 2012

Comparative microcalorimetric measurements of the molar enthalpies of solution ΔHs (298 K, 0.1 MPa) of gaseous CF3H and CF3Cl in benzene, toluene, p‐xylene, and mesitylene have revealed an unexpected strong dependence of ΔHs on the mole fraction x of the solute at very low concentrations. In the range 10−5 ≤ x ≤ 10−3 an increase of ΔHs by 8 to 10 kJ mol−1 was observed. A detailed analysis of the experimental procedure which was adopted using a Wadsö differential heat flow microcalorimeter and dissolving the gases at very small flow rates in the unstirred liquids is given. The additional exothermic contribution to ΔHs at x < 10−3 is attributed to structure formation in the aromatic liquids induced by the dissolved gas molecules.
NMR Relaxation in Solutions of Six Fluorinated Benzenes Containing a Free Radical
Authors: Darges G. , Müller‐Warmuth W.
Published: July 2012

1H and 19F NMR spin‐lattice relaxation times and dynamic nuclear polarization (DNP) enhancements have been measured at various temperatures in a magnetic field of 17 mT for solutions of six polyfluorinated benzenes containing free radicals. From the radical induced relaxation rates and DNP coupling factors, dipolar and scalar hyperfine coupling contributions have been separated. As a result, the dipolar fluorine and the total proton relaxation rates are more or less the same, and they are only controlled by the molecular motion. The scalar relaxation rates depend upon the chemical structure, but their temperature dependence is also given by the process of translational diffusion. The activation energies for molecular translation, and the scalar contact coupling intensity both increase as one goes from mono‐ to hexafluorobenzene. Coupling mechanisms and comparison with viscous flow and diffusion are discussed.
Molekulardynamische Rechnungen an fluiden Mischungen: Paarverteilungsfunktionen und lokaler Molenbruch für Komponenten sehr unterschiedlichen Volumens
Authors: Hoheisel Claus
Published: July 2012

Molecular dynamics calculations (MDC) were performed for binary model‐mixtures on the basis of Lennard‐Jones potentials. The σ‐parameters of the components differed by a factor of two.—Pair‐correlation functions and local molefractions were obtained as function of the compositon.‐The MDC results show appreciably altered pair‐correlation functions compared to the those of mixtures with similar σ‐parameters. The local mole fractions vary distinctly in the short‐range distance of the particles and exhibit relatively large departures from the composition of the mixture for the wider neighborhood of the particles.
Collision‐Induced Spectra of Simple Liquids
Authors: Arning H.‐J. , Tibulski K. , Dorfmüller Th.
Published: July 2012

The far infrared spectra (20–200 cm−1) of nine liquids (CH4, C2H4, C2H6, C3H8, C6H12, CCl4, C2Cl4, CH2C12, CHC13) have been measured and the corresponding induced dipole autocorrelation functions have been calculated. Using the Kubo‐Mori‐Zwanzig formalism we calculated the characteristic relaxation times of the correlation functions and of the first and second order memory functions. A comparison of these relaxation times with the free rotator reorientation times leads to the conclusion that the spectra reflect both rotational and translational components. The higher order memory functions appear to be less sensitive to the details of molecular dynamics of the liquid. The relaxation between the dynamics of the two polar molecules CH2Cl2 and CHCl3 and that of the non polar molecules is shortly discussed.
Catalytic Oxidation of Carbon Monoxide over Ag0.35V2O5
Authors: Van Berg J. Den , Brans‐Brabant J. H. L. M. , van Dillen A. J. , Flach J. C. , Geus J. W.
Published: July 2012

The oxidation of CO over the silver‐vanadium bronze ß‐Ag0.35V2O5 was studied between 150 and 550 °C in a continuous flow reactor. Results show that the catalytic activity of Ag0.35V2O5 is strongly influenced by its pretreatment; partial surface reduction leads to a high oxidation activity. Evaluation of the kinetic parameters leads to the conclusion that at temperatures above 450°C the activity of Ag0.35V2O5 can be described with a defect V2O5‐like structure.—Furthermore, carbon is deposited on the catalyst near 375 °C in excess oxygen atmosphere due to disproportionation of CO which leads to a low activity. A model is proposed for the reoxidation of carbon by adsorbed water to CO and H2 near 200 °C. This reaction results in an enhancement of the low‐temperature oxidation activity of the bronze.
Untersuchungen zur Reaktion OH + HO2 → H2O + O2 mit Hilfe eines Laser‐Magnetischen Resonanz‐Spektrometers
Authors: Temps F. , Gg. Wagner H.
Published: July 2012

The reaction OH + HO2 → H2O + O2 (1) was studied at room temperature in several isothermal discharge‐flow reactors. OH‐ and HO2‐radicals and O‐atoms were monitored with an optically pumped lmr‐spectrometer. The radicals were produced by the reaction F + H2O → OH + HF and OH + HO2 H2O, F + H2O2 → HO2 + HF or H + O2 + M → HO2 + M, respectively. The influence of side reactions due to the presence of H2O2 or the possible presence of O‐ or H‐atoms with small concentrations was investigated and eliminated or taken into account by using suitable reaction conditions. The rate constant at room temperature was found to be k1 (296 K) = (4.0 ± 1.4) · 1013 cm3/mol s.

In the range 2 mbar ≤ p ≤ 14 mbar k1 is invariant with pressure.
Transport Properties of Liquids, III. Viscosity of Athermal Liquid Mixtures
Authors: Vogel Herbert , Weiss Alarich
Published: July 2012

The mass density ρ and the dynamic viscosity ρ of eleven binary liquid mixtures were measured as a function of concentration and temperature, in order to study the influence of the entropy of mixing on the viscosity of athermal liquid mixtures.—ζ was determined via an Ubbelohde micro‐viscosimeter and ρ via a vibrating densimeter.—The species of the mixtures differ to a large extent in size and in mass only (Si‐, Sn‐, and Ti‐Tetraalkyl and Tetraalkoxy compounds).—With the Grunberg‐Nissan equation the experimental data can be described in good approximation. As a measure for the non‐ideal behaviour of the mixtures, the Grunberg‐Nissan Parameter ρ is correlated with the difference of the molecular diameter of the components, and with the entropy of mixing.
The First Excited Singlet State of Trans‐Thioindigo
Authors: Karstens T.
Published: July 2012

The first excited singlet state S1 of trans‐thioindigo has been investigated mainly by fluorescence emission, excitation and lifetime measurements in various solvents over a wide temperature range. The experimental results are interpreted in terms of a dual luminescence model, which arises from the flexibility of the thioindigo central bond in the excited singlet state. It is shown that the population density of planar and twisted configurations depends on temperature, viscosity and solvent properties as well as on the excitation wavelength.—As only planar trans‐molecules have been shown to undergo efficient intersystem crossing to the trans triplet and subsequent decay to the cis ground state (trans‐cis isomerization), it is quite important to understand the influence of the above parameters on population of twisted transoid configurations.
Dissociative Attachment and Ion Pair Formation in CF4, CHF3, CH2F2, and CH3F under Low Energy (0 – 20 eV) Electron Impact
Authors: Scheunemann H.‐U. , Heni M. , Illenberger E. , Baumgärtel H.
Published: July 2012

Resonance dissociative electron attachment and ion pair formation following electron impact have been studied in the energy range from 0 – 20 eV. The translational excess energies of the negative ion fragments have been determined using a time‐of‐flight technique in combination with mass analysis in a quadrupole mass filter. Compared with other halogenated methanes, the resonances in CHF3, CH2F2, and CH3F leading to negative fragments appear at considerable higher energies. The experimental results indicate that those resonances are associated with multiple fragmentation reactions.
The Independent Molecular Interaction Sites Model II. The Structure of the Reference Fluid for Homonuclear Hard Dumbbell Systems
Authors: Naumann Karl‐Heinz
Published: July 2012

The structural properties of the Independent‐Molecular‐Interaction‐Sites (IMIS) reference fluid for homonuclear hard dumbbell systems are investigated in the Percus‐Yevick and in the Hypernetted‐Chain approximation, respectively. The interaction‐site pair distribution functions obtained from the IMIS model are compared with the “exact” results from a Monte‐Carlo study and with predictions from the RISM theory. The calculations presented in this publication are suggesting, that the IMIS model represents a close approximation to the site‐site pair correlations of the real system.
An Equation for the Ideal‐Gas Heat Capacity of Molecular Oxygen for Temperatures from 30 K to 3000 K
Authors: Wagner Wolfgang , Ewers Johannes , Schmidt Robert
Published: July 2012

A semi‐empirical equation has been established to calculate very accurately the ideal‐gas heat capacity cp0 of molecular oxygen in the temperature range from 30 K to 3000 K. The new equation contains special terms derived from statistical‐thermodynamic considerations in order to represent that part of cp0 resulting from the vibration energy of the molecule and the energy of electronic excitation. The cp0‐values calculated with the new equation have been compared with values directly calculated by evaluation of the partition functions for fixed temperatures listed in known tabulations. Because of the “physical” background of the equation extrapolations beyond 3000 K are possible. Corresponding expressions for the ideal‐gas enthalpy and entropy of oxygen are also given.
High Resolution Spectroscopy of High Temperature Molecules
Authors: Törring T.
Published: July 2012

This paper reviews recent developments in ground state high resolution spectroscopy of high temperature radicals. The methods discussed include microwave absorption spectroscopy and microwave‐optical double resonance techniques. These methods have been used to study rotational spectra and hyperfine structure of earth alkaline monohalides.
Some Properties of Small Gas Molecules Determined by Refractive Index Measurements
Authors: Kerl K.
Published: July 2012

The dispersion of the refractive index of the gases He, Ne, Ar, H2, N2, O2, CH4, and C(CH3)4 at low densities is determined in the visible wave length range 400 nm ≦ λ ≦ 700 nm by means of scanning‐wavelength interferometry. The measurements are fitted by one‐term Kramers‐Heisenberg dispersion relations and used to calculate some macroscopic and molecular properties like mean polarizabilities, effective eigenenergies and oscillator strengths, oscillator strength sums, Verdet and related constants, Rayleigh scattering cross sections and dispersion force constants. The theoretical background as well as the significance of the different relations between refractive index and these properties is presented and discussed briefly.