bluuebunny/crossref_metadata_2025 huggingface dataset:
How realistic are air quality hindcasts driven by forcings from climate model simulations?
Authors: Lacressonnière G. , Peuch V.-H. , Arteta J. , Josse B. , Joly M. , Marécal V. , Saint Martin D. , Déqué M. , Watson L.
Published: July 2012

Abstract. Predicting how European air quality could evolve over the next decades in the context of changing climate requires the use of climate models to produce results that can be averaged in a climatologically and statistically sound manner. This is a very different approach from the one that is generally used for air quality hindcasts for the present period: analysed meteorological fields are used to represent specifically each date and hour. Differences arise both from the fact that a climate model run is a pure model output, with no influence from observations (which are useful to correct for a range of errors), and that in a "climate" set-up, simulations on a given day, month or even season cannot be related to any specific period of time (but can just be interpreted in a climatological sense). Hence, although an air quality model can be thoroughly validated in a "realistic" set-up using analysed meteorological fields, the question remains of how far its outputs can be interpreted in a "climate" set-up. For this purpose, we focus on Europe and on the current decade using three 6-yr simulations performed with the multiscale chemistry-transport model MOCAGE and use meteorological forcings either from operational meteorological analyses or from climate simulations. We investigate how statistical skill indicators compare in the different simulations, discriminating also the effects of meteorology on atmospheric fields (winds, temperature, humidity, pressure \\ldots) and on the dependent emissions and deposition processes (volatile organic compound emissions, deposition velocities . . .). Our results show in particular how differing boundary layer heights and deposition velocities affect horizontal and vertical distributions of species. When the model is driven by operational analyses, the simulation accurately reproduces the observed values of O3, NOx, SO2 and, with some bias that can be explained by the set-up, PM10. We study how the simulations driven by climate forcings differ, both due to the realism of the forcings (lack of data assimilated and lower resolution) and due to the lack of representation of the actual chronology of events. We conclude that the indicators such as mean bias, mean normalized bias, RMSE and deviation standards can be used to interpret the results with some confidence as well as the health-related indicators such as SOMO35 and the number of days of exceedance of regulatory thresholds. These metrics are thus considered to be suitable for the interpretation of simulations of the future evolution of European air quality.
A method to characterize the different extreme waves for islands exposed to various wave regimes: a case study devoted to Reunion Island
Authors: Lecacheux S. , Pedreros R. , Le Cozannet G. , Thiébot J. , De La Torre Y. , Bulteau T.
Published: July 2012

Abstract. This paper outlines a new approach devoted to the analysis of extreme waves in presence of several wave regimes. It entails discriminating the different wave regimes from offshore wave data using classification algorithms, before conducting the extreme wave analysis for each regime separately. The concept is applied to the pilot site of Reunion Island which is affected by three main wave regimes: southern waves, trade-wind waves and cyclonic waves. Several extreme wave scenarios are determined for each regime, based on real historical cases (for cyclonic waves) and extreme value analysis (for non-cyclonic waves). For each scenario, the nearshore wave characteristics are modelled all around Reunion Island and the linear theory equations are used to back calculate the equivalent deep-water wave characteristics for each portion of the coast. The relative exposure of the coastline to the extreme waves of each regime is determined by comparing the equivalent deep-water wave characteristics. This method provides a practical framework to perform an analysis of extremes within a complex environment presenting several sources of extreme waves. First, at a particular coastal location, it allows for inter-comparison between various kinds of extreme waves that are generated by different processes and that may occur at different periods of the year. Then, it enables us to analyse the alongshore variability in wave exposition, which is a good indicator of potential runup extreme values. For the case of Reunion Island, cyclonic waves are dominant offshore around the island, with equivalent deep-water wave heights up to 18 m for the northern part. Nevertheless, due to nearshore wave refraction, southern waves may become as energetic as cyclonic waves on the western part of the island and induce similar impacts in terms of runup and submersion. This method can be easily transposed to other case studies and can be adapted, depending on the data availability.
Comparative Study of Collagen Hydrogels Modified in Two Ways Using the Model of Ectopic Cartilage Construction with Diffusion-chamber in Immunocompetent Host
Authors: Zheng Li , Sun Jin , Li Bo , Zhou Wen , Fan Hongsong , Zhang Xingdong
Published: July 2012

Purpose

For scaffolds in cartilage tissue engineering, it is the principle to design the materials with both favorable mechanical and biological property.

Methods

In this article, collagen hydrogels modified by two ways to improve mechanical strength were applied for in vivo cartilage reconstruction: one is collagen-alginate hydrogel (CAH) representative of mixture, the other is collagen hydrogel crosslinked by genipin (CGH). To investigate the biological activities of the two materials, it was designed as: scaffolds loaded with allogenous chondrocytes were encased in diffusion chamber, and then implanted subcutaneously in SD rats for 8 weeks.

Results

Histologic, immunohistochemical, and RT-PCR results showed that collagen type II and GAG, indicator of cartilage extracellular matrix (ECM) was highly expressed in constructs of chondrocyte-CAH. Significantly lower cell density and expression of cartilage specific protein were shown in constructs of chondrocyte-CGH than that in chondrocyte-CAH. This demonstrated that CAH may provide a more favorable environment for cartilage reconstruction. In addition, the model with diffusion chamber technique was viable for evaluation of scaffolds for in vivo cartilage engineering in immunocompetent host. Instead, directly reconstruction of ectopic cartilage without diffusion chamber suffered from damaged tissue and less neo-cartilage matrix formed.

Conclusions

In conclusion, CAH is realistic as scaffold for in vivo cartilage tissue engineering with both satisfactory mechanical properties and biomimetic activity. Also, the model with diffusion chamber to reconstruct ectopic cartilage in immunocompetent animals is promising for evaluation of scaffolds. This study provided a new insight for in vivo cartilage tissue engineering.
Overall evaluation of an immunological latex agglutination system for fecal occult blood testing in the colorectal cancer screening program of Florence
Authors: Rubeca Tiziana , Peruzzi Benedetta , Confortini Massimo , Rapi Stefano
Published: July 2012

Several immunological fecal occult blood tests (FOBT) are currently available for colorectal cancer (CRC) screening. We compared the HM Jack (Jack) (Kiowa, Japan), with the OC-Hemodia (OC) (Eiken, Japan) in use in the Florence screening program. Aims of the study were: (i) to investigate the diagnostic performance and the best cutoff value for Jack; (ii) to evaluate the handiness of sampling tubes; (iii) to compare costs. A total of 5,044 subjects were screened with both tests. Sampling tube investigation was performed running each sample on both instruments. A number of 352 subjects positive for at least one test (175 OC, 310 Jack) were selected for further investigations, while 46 subjects refused further assessments. Analysis of costs related to the assessment phase was performed on the basis of Tuscany region's fares. Amongst the 306 subjects investigated, 9 CRC and 67 advanced adenomas (AdA) were detected. Detection rates (DR) were 1.4‰ for CRC and 9.6‰ for AdA. After Jack cutoff optimization, DR for CRC+AdA resulted in 11.1‰ for OC and 13.3‰ for Jack (p=0.041). Sensitivity of the methods was 73.7 for OC and 88.2 for Jack; specificity was 97.6 for OC and 96.0 for Jack, resulting in an increase of the required assessments from 3.5% to 5.1%. No differences were observed between sampling methods. Despite the lower specificity of Jack, its greater sensitivity makes the method attractive for screening programs. An increase of the costs of 30% for every subject investigated for pathological lesion (CRC+AdA) may be thus foreseen.
Importance of chemokine (CC-motif) ligand 2 in breast cancer
Authors: Steiner Jennifer L. , Murphy E. Angela
Published: July 2012

Breast cancer is the leading cause of cancer-related death in women in the United States. Chemokine (CC-motif) ligand 2 (CCL2), an inflammatory cytokine and chemokine, is highly expressed within the tumor and stromal cell populations and has been associated with enhanced tumorigenesis. In breast cancer patients, CCL2 has been correlated with high tumor grade and has been shown to have significant prognostic value for relapse-free survival. CCL2 likely exerts its pro-tumorigenic effects through recruitment of tumor-associated macrophages (TAMs); TAMs promote a tumorigenic microenvironment through the induction of growth enhancers, angiogenic factors and inflammatory mediators. CCL2 may also stimulate angiogenesis independently of TAM recruitment as it is closely associated with several endothelial cell growth factors. Additionally, CCL2 has been implicated in several processes leading to metastatic establishment including the development of bone metastasis. It has also been reported to directly upregulate pro-tumorigenic inflammatory mediators, including regulated upon activation, normal T cell expressed and secreted (RANTES) and tumor necrosis factor-alpha (TNF-α). While there is emerging support for a tumor promoting role of CCL2 in breast cancer, additional research is required before CCL2 can be decisively established as a prognostic factor and/or treatment target in breast cancer.
Preoperative CA-125 predicts extra-uterine disease and survival in uterine papillary serous carcinoma patients
Authors: Roelofsen Thijs , Mingels Marjanka , Hendriks Jan C.M. , Samlal Rahul A. , Snijders Marc P. , Aalders Anette L. , Bulten Johan , Van Ham Maaike A.P.C. , Massuger Leon F.A.G.
Published: July 2012

Objective

We determined the clinical utility of preoperative serum CA-125 as predictor of extra-uterine disease and as prognosticator for survival in patients with uterine papillary serous carcinoma (UPSC).

Methods

Patients diagnosed with UPSC, identified between 1992 and 2009, and with preoperative CA-125 measurement were included. A receiver operator characteristic (ROC) curve was used to quantify marker performance. Overall and progression free survival were analyzed using the Kaplan-Meier method. Regression analyses were used to investigate the association of preoperative CA-125 levels and other clinicopathological variables with the presence of extra-uterine disease and the effects on survival.

Results

Sixty-six patients met the study criteria. Using ROC, the CA-125 concentration of 45 U/mL as cutoff level provided the best sensitivity (75%) and specificity (74%) for extra-uterine disease, with a positive predictive value of 86%. Survival was significantly longer in patients with preoperative CA-125 =45 U/mL (p<0.001). Only preoperative CA-125 >45 U/mL remained significantly associated with extra-uterine disease (OR=6.30, 95% CI 1.93–20.62). Furthermore, advanced FIGO stage (HR=4.53, 95% CI 1.50–13.62) and preoperative CA-125 >45 U/mL (HR=3.12, 95% CI 1.13–8.73) were associated with decreased survival.

Conclusion

Preoperative elevated serum CA-125 is an independent predictor for the presence of extra-uterine disease and an independent risk factor for survival in UPSC patients.
Role of the hematopoietic cytokines SCF, IL-3, GM-CSF and M-CSF in the diagnosis of pancreatic and ampullary cancer
Authors: Vasiliades George , Kopanakis Nikolaos , Vasiloglou Michalis , Zografos George , Margaris Helias , Masselou Kyriaki , Kokosi Evniki , Liakakos Theodore
Published: July 2012

Background

Previous studies have demonstrated altered levels of hematopoietic cytokines in the serum of patients with different types of cancer.

Methods

We measured the serum levels of the hematopoietic cytokines stem cell factor (SCF), interleukin 3 (IL-3), macrophage-colony stimulating factor (M-CSF) and granulocyte-macrophage-colony stimulating factor (GM-CSF) in 40 pancreatic and ampullary cancer patients and 40 healthy volunteers, using ELISA. We also assessed the most widely used pancreatic tumor markers, carbohydrate antigen 19–9 (CA 19–9) and carcinoembryonic antigen (CEA), in both groups. We then correlated the concentrations of the cytokines and the tumor markers in the patients’ serum and we estimated their diagnostic ability by calculating diagnostic sensitivity and specificity, positive and negative predictive values and the receiver operating characteristic (ROC) curve.

Results

The SCF and IL-3 levels were significantly lower and the M-CSF levels significantly higher in pancreatic cancer patients than in controls. There were significant positive correlations between the serum levels of CEA and M-CSF, GM-CSF and SCF, and between GM-CSF and IL-3. The area under the ROC curve and diagnostic sensitivity of M-CSF were greater than those of SCF and IL-3. The diagnostic sensitivity of the combined use of SCF and M-CSF reached 97.5%.

Conclusion

The diagnostic ability of M-CSF and SCF in pancreatic and ampullary cancer should stimulate further studies evaluating their clinical usefulness as tumor markers.
Spray Pyrolysis Deposition of Nanostructured Tin Oxide Thin Films
Authors: Patil G. E. , Kajale D. D. , Gaikwad V. B. , Jain G. H.
Published: July 2012

Nanostructured SnO2 thin films were grown by the chemical spray pyrolysis (CSP) method. Homemade spray pyrolysis technique is employed to prepare thin films. SnO2 is wide bandgap semiconductor material whose film is deposited on glass substrate using aqueous solution of SnCl4·5H2O as a precursor. XRD (X-ray diffraction), UV (ultraviolet visible spectroscopy), FESEM (field emission scanning electron microscopy), and EDS (energy dispersive spectroscopy) analysis are done for structural, optical, surface morphological, and compositional analysis. XRD analysis shows polycrystalline nature of samples with pure phase formation. Crystallite size calculated from diffraction peaks is 29.92 nm showing nanostructured thin films. FESEM analysis shows that SnO2 thin film contains voids with nanoparticles. EDS analysis confirms the composition of deposited thin film on glass substrate. UV-visible absorption spectra show that the bandgap of SnO2 thin film is 3.54 eV. Bandgap of SnO2 thin film can be tuned that it can be used in optical devices.
Perilymph Fistula: Fifty Years of Controversy
Authors: Hornibrook Jeremy
Published: July 2012

Perilymph fistula (PLF) is defined as a leak of perilymph at the oval or round window. It excludes other conditions with “fistula” tests due to a dehiscent semi circular canal from cholesteatoma and the superior canal dehiscence syndrome. It was first recognized in the early days of stapedectomy as causing disequilibrium and balance problems before sealing of the stapedectomy with natural tissue became routine. It then became apparent that head trauma and barotraumatic trauma from flying or diving could be a cause of PLF. Descriptions of “spontaneous” PLF with no trauma history followed. A large literature on PLF from all causes accumulated. It became an almost emotional issue in Otolaryngology with “believers” and “nonbelievers.” The main criticisms are a lack of reliable symptoms and diagnostic tests and operative traps in reliably distinguishing a perilymph leak from local anaesthetic. There are extensive reviews on the whole topic, invariably conveying the authors' own experiences and their confirmed views on various aspects. However, a close examination reveals a disparity of definitions and assumptions on symptoms, particularly, vestibular. This is an intentionally provocative paper with suggestions on where some progress might be made.
Cerebellar Liponeurocytoma
Authors: Nishimoto Todd , Kaya Brock
Published: July 2012

Cerebellar liponeurocytoma is a rare neoplasm with distinctive morphologic features. It typically involves the cerebellar hemispheres of middle-aged to older adults. The tumor is composed of a uniform population of neurocytic cells possessing round to oval nuclei and pale to clear cytoplasm. A variable degree of lipidization of the tumor cells is present, lending a resemblance to mature adipose tissue. Immunohistochemistry serves to confirm the neurocytic differentiation of the tumor cells. In the 2007 revision of the World Health Organization classification of central nervous system tumors, cerebellar liponeurocytoma was reclassified as a grade II neoplasm to reflect a higher recurrence rate than was previously appreciated.
Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type: Diagnostic Considerations
Authors: Hristov Alexandra C.
Published: July 2012

Context.—Primary cutaneous diffuse large B-cell lymphoma, leg type, may show features that overlap with other lymphomas. However, timely recognition of this entity can have important clinical and therapeutic implications.

Objective.—To review the clinical, morphologic, and immunophenotypic characteristics of primary cutaneous diffuse large B-cell lymphoma, leg type, and juxtapose these features with other diagnostic considerations. In particular, other variants of primary cutaneous diffuse large B-cell lymphoma, as well as primary cutaneous follicle center lymphoma, will be reviewed. Additionally, systemic/extracutaneous lymphomas will be discussed, including diffuse large B-cell lymphoma, not otherwise specified, Epstein-Barr virus–positive diffuse large B-cell lymphoma of the elderly, and lymphomatoid granulomatosis.

Data Sources.—Relevant literature will be reviewed and key differentiating findings will be highlighted.

Conclusions.—Although primary cutaneous diffuse large B-cell lymphoma, leg type, may show aspects that overlap with other lymphomas, it can be distinguished from other entities in the differential diagnosis.
Hypersensitivity Pneumonia: Role of Surgical Lung Biopsy
Authors: Herbst Jonathon B. , Myers Jeffrey L.
Published: July 2012

Lung biopsy often plays a key role in identifying patients with hypersensitivity pneumonia, especially in the absence of a typical history. A 69-year-old woman with a 2-year history of unexplained dyspnea on exertion underwent surgical lung biopsy for diagnosis of diffuse lung disease thought to represent idiopathic pulmonary fibrosis. Her biopsy showed honeycomb change and fibroblast foci suggestive of usual interstitial pneumonia, but also showed areas of cellular interstitial pneumonia with chronic bronchiolitis and a pattern of granulomatous inflammation typical of hypersensitivity pneumonia. The classic features of hypersensitivity pneumonia in surgical lung biopsy are emphasized, including a bronchiolocentric cellular interstitial pneumonia, chronic bronchiolitis, and poorly formed nonnecrotizing granulomas. As illustrated in our patient, sometimes subtle histologic clues are key in separating hypersensitivity pneumonia from usual interstitial pneumonia and other forms of idiopathic interstitial pneumonia. Making the distinction is important given differences in treatment strategies and natural history.
Life-Long Learning and Self-Assessment
Authors: Myers Jeffrey L. , Greenson Joel K.
Published: July 2012

New Frontiers in Pathology is a unique educational event intended to meet the ongoing educational needs of practicing pathologists. Continuous medical education (CME) is required for maintenance of licensure by virtually all state licensing bodies. Satisfying CME requirements hinges on earning a minimum number of American Medical Association Physician Recognition Award category 1 credits through various activities, including courses like New Frontiers in Pathology that are accredited by the Accreditation Council for Continuing Medical Education. Self-assessment modules (SAMs) are a key component of the American Board of Pathology expectations for maintenance of board certification. Beginning in 2006, the American Board of Pathology granted only time-limited certificates as part of an American Board of Medical Specialties–wide process for maintenance of board certification. Maintenance of board certification has requirements in 4 categories: professional standing, life-long learning and self-assessment, cognitive expertise, and evaluation of performance in practice. Life-long learning and self-assessment includes not only the traditional elements of CME but also the SAMs that are defined as educational products comprising self-administered examinations with a predetermined minimum performance level and a mechanism for receiving feedback. New Frontiers in Pathology will offer SAMs, in addition to the American Medical Association Physician Recognition Award category 1 credits, which it has been accredited to do since its inception, at its 2012 conference scheduled for August 3 through August 5 at The Homestead Resort, Michigan's largest waterfront resort on beautiful Lake Michigan.
Epitaxial Magnetic Oxide Nanocrystals Via Phase Decomposition of Bismuth Perovskite Precursors
Authors: Bogle Kashinath A. , Cheung Jeffrey , Chen Yong‐Lun , Liao Sheng‐Chieh , Lai Chih‐Hung , Chu Ying‐Hao , Gregg John M. , Ogale Satishchandra B. , Valanoor Nagarajan
Published: July 2012

The phase instability of bismuth perovskite (BiMO3), where M is a ferromagnetic cation, is exploited to create self‐assembled magnetic oxide nanocrystal arrays on oxide supports. Conditions during pulsed laser deposition are tuned so as to induce complete breakdown of the perovskite precursor into bismuth oxide (Bi2O3) and metal oxide (M‐Ox) pockets. Subsequent cooling in vacuum volatizes the Bi2O3 leaving behind an array of monodisperse nanocrystals. In situ reflective high energy electron diffraction beam is exploited to monitor the synthesis in real‐time. Analysis of the patterns confirms the phase separation and volatization process. Successful synthesis of M‐Ox, where M = Mn, Fe, Co, and Cr, is shown using this template‐free facile approach. Detailed magnetic characterization of nanocrystals is carried out to reveal the functionalities such as magnetic anisotropy as well as larger than bulk moments, as expected in these oxide nanostructures.
Thermal Conductivity of Mixtures of Hydrogen and Helium at 27.5°C and Pressures up to 14 MPa
Authors: Clifford A. A. , Fleeter R. D. , Kestin J. , Wakeham W. A.
Published: July 2012

The paper reports new, absolute measurements of the thermal conductivity of three binary gaseous mixtures of hydrogen and helium at 27.5°C and at pressures up to 14 MPa. The measurements were performed in a transient hot‐wire instrument and have an estimated accuracy of ±0.3%.  The experimental results for each mixture have been extrapolated so as to yield reliable values of the zero‐density thermal conductivity. These data are described, within their experimental uncertainty, by the Hirschfelder‐Eucken formula provided that an empirical adjustment is made to one of the parameters characteristic of the unlike molecular interaction. With the aid of the same formula the data are shown to be consistent with earlier viscosity data on the same system. The ab initio intermolecular potential for the H2  He interaction calculated by Tsapline and Kutzelnigg predicts the experimental data to within ±1%.
Dynamics of Hydrogen and Water Adsorbed on Nickel Catalysts
Authors: Stockmeyer R. , Stortnik H. , Natkaniec I. , Mayer J.
Published: July 2012

Frequency distributions of chemisorbed H atoms on Ni determined by neutron spectroscopy on different types of Ni catalysts at 300 K and 80 K confirm earlier data from Raney‐nickel [1]. A lattice dynamical interpretation of the data taken at small hydrogen loading of the Ni catalysts leads for the force constant characterising the H – Ni interaction to a value fHN = 8 · 103 dyn/cm, and fHH = 4 · 103 dyn/cm for the H  H interaction on Ni(100) planes with one H bonded to 4 Ni surface atoms. At large H2 loading of the Ni catalysts (7 bar H2 pressure) the frequency distribution of the chemisorbed hydrogen indicates a weaker H  Ni coupling. As concluded from the elastic peaks H2 and H2O are dissociatively adsorbed in presence of each other. The frequency distributions measured in [(Ni + H2O) + H2] and [(Ni + H2) + H2O] systems are similar to those from hydrogen on Ni at medium surface coverage.
The Influence of Viscosity on Fluorescence‐Quantum‐Yields of a Polymethine‐Dye Dichinolyl‐Cyano‐Methane
Authors: Griebel R.
Published: July 2012

Among a series of heteroannular polymethines, Dichinolyl‐Cyano‐Methane excells by its large dynamic range of fluorescence‐quantum‐yield in response to solvent fluidity. The excited‐state‐dynamics of this probe and the influences of various solvents on it are studied and compared with expectations from current models of the subject. A pronounced viscosity(temperature)‐dependent D‐effect on fluorescence‐quantum‐yield in fluid solution was found and explained by coupling of the dominant and viscosity‐dependent relaxationmode to a intramolecular H/D‐bridge‐potential. The observations presented indicate, that Dichinolyl‐Cyano‐Methane may serve as a diagnostic tool in future studies on fluid‐dynamics.
Thermodynamic Study on Compound‐Forming Molten Alloys: The Tin‐Tellurium System
Authors: Nakamura Yoshio , Himuro Sinya , Shimoji Mitsuo
Published: July 2012

The thermodynamic properties of molten Sn  Te alloys have been determined by means of the EMF method. It has been found that the enthalpy and entropy of mixing show marked minima around the stoichiometric composition SnTe, where the electrical properties show also anomalies. The results obtained have been discussed in terms of the pseudobinary alloy model and the quasi‐chemical model.
Absorption of the C  H Stretching Fundamentals in Pure Ethylene to High Pressures and Temperatures
Authors: Buback M. , Heym I.
Published: July 2012

The infrared absorption of thev9andv11stretching fundamentals in pure ethylene was measured at supercritical temperatures between 26°C and 200°C to a maximum pressure of 2000 bar. The density and temperature dependence of the absorption intensity and of the wave‐numbers of maximum absorption are reported. The decrease of thev9molar integrated absorptivity toward the highest densities is interpreted as being due to the importance of repulsive interactions in dense pure ethylene. The position of thev11band maximum provides a measure for the extent of rotational freedom in the fluid state.
Colloidal Silver Catalyzed Multi‐Electron Transfer Processes in Aqueous Solution
Authors: Henglein A.
Published: July 2012

(CH3)2COH radicals were γ‐radiolytically produced in aqueous solutions of colloidal silver (2.5 · 10−4 mol/l, acetone (0.1 – 0.2 M) and propanol‐2(0.2 – 0.4 M). The radicals were able to reduce Cd2+, N2O, and NO−3 with yields of practically 100%. In the absence of colloidal silver, Cd2+ was not reduced, but N2O or NO−3 were reduced with yields of the order of 1%. The reduction processes in the presence of silver occurred in competition with the reduction of water by the organic radicals. The catalytic action of colloidal silver is explained by electron transfer from the organic radicals to the silver particles that become a pool of electrons and adsorbed hydrogen atoms. The stored electrons are then used to carry out the reduction of water or of dissolved substances. Relative rate constants for a number of multi‐electron transfer processes at the colloidal silver pool are given and details of the reaction mechanism including the action of adsorbed Hδ‐ atoms are discussed. — Radiolytically produced Cd+ ions were also reduced at the colloidal silver pool. However, Zn+, Ni+, and Co+ were found to transfer an electron to the pool. The homogeneous reaction between NO−3 and (CH3)2COH was also investigated. A rate constant of 28 M−1 s−1 was found for this reaction.
Optical Studies of Soot‐Formation Processes in Premixed Flames
Authors: Haynes B. S. , Jander H. , Wagner H. Gg.
Published: July 2012

Soot formation in flat, premixed flames of ethylene, benzene, and pyridine with air is investigated using laser light scattering and fluorescence and extinction measurements. — In the earliest stages of the soot formation process in all of the flames examined, a fluorescent emission is excited by the laser (extending from 450 nm to beyond 700 nm when excited at 488 nm). In pyridine and ethylene flames their intensity increases downstream or remains constant. In benzene flames, it passes through a sharp maximum just as the first particles are detected by light scattering. Measurements of optical extinction by soot particles are complicated by broad‐spectrum gas‐phase absorption which may dominate the soot absorption early in the flame. This absorption is stronger at shorter wavelengths and appears to be related to the molecules responsible for the fluorescence observed in these flames. The continuum fluorescence is also responsible for the apparently high degree of depolarization of the elastically scattered light early in the flame. The actual depolarization of the light scattered from the soot particles is of the order of 1% for ethylene and pyridine, 0.2% for benzene flames. — Combination of the corrected particle extinction and scatter measurements yields values for the particle size and number density. Soot particles grow by surface growth which depends on the nature of the parent fuel, the mixture C/O ratio, and the temperature and by coagulation. The measured coagulation rated are largely independent of these parameters and in agreement with the rates predicted from kinetic theory.
A New Estimate of the H+ Ion Concentration in Pure Water. Part 2. Numerical Results and a New Interpretation of the Limiting Equivalent Conductance of HCI
Authors: Hertz H. G.
Published: July 2012

Linear response theory is applied to calculate the specific conductance of pure water. Comparison of velocity cross‐correlation coefficients with self‐diffusion coefficients yields a velocity correlation defect δH+ = 5.7 · 10−9. This figure is reformulated to give a H+ concentration of 3.18 · 10−7 mol/l in pure H2O at 25°C. A new interpretation of the limiting equivalent conductances of HCl and KOH involving the collective motion of all ions in the bulk of the solution is given. Then a new mode of understanding the transport numbers tp and tOH in aqueous HCl and KOH solutions is presented. Finally, the Grotthus mechanism is considered under the aspects of the present theory.
Photoelectrochemical Reactions and Formation of Inversion Layers at n‐Type MoS2‐, MoSe2‐, and WSe2‐Electrodes in Aprotic Solvents
Authors: Kautek W. , Gerischer H.
Published: July 2012

Capacity measurements and cyclic voltammetry have been used to conduct a systematic investigation of the potential distribution at the semiconductor‐organic electrolyte interface in the dark and under illumination with the n‐type synthetic layered compounds MoS2, MoS2, and WSe2. From the obtained flat band potentials it could be concluded that the valence band edges vs. Ag/Ag+ are located in acetonitrile at ca. 1.0 V (MoS2), 0.7 V (MoSe2), and 0.4 V (WSe2). As theoretically expected, the oxidized component of redox systems with Fermi levels near or below the valence band edge can inject holes thus inducing an inverted region and generating a p‐n junction in the solid. The cathodic current in the cyclic voltammograms of such redox systems occurs via hole injection with consecutive recombination of the injected holes while less oxidizing redox systems can only be reduced via the conduction band. — Since the semiconductors used in these experiments do not corrode in presence of a high surface concentration of holes, such a contact with an oxidizing redox electrolyte offers most favourable conditions for the application in a photoelectrochemical solar cell. The inversion layer has a maximal band bending and promises to obtain the highest possible photovoltage, which is however limited by the width of the band gap.
Die zweiten Virialkoeffizienten verschiedener Gasmischungen im Temperaturbereich von 213 bis 475 K
Authors: Schmiedel H. , Gehrmann R. , Schramm B.
Published: July 2012

Es wurden die zweiten VirialkoeffizientenBm(T,x1) der binären Gasmischungen NeAr, NeKr, NeXe, ArN2, ArCO und ArCO2im Temperaturbereich von 213 bis 475 K bei verschiedenen Molenbrüchen gemessen und aus diesen Werten der molenbruchunabhängige MischvirialkoeffizientB12(T) bestimmt. Die Meßdaten werden mit Virialkoeffizienten verglichen, die aus Potentialvorschlägen anderer Autoren berechnet worden sind.
Atomization Enthalpies of the Molecules Cu3, Ag3, and Au3
Authors: Hilpert K. , Gingerich K. A.
Published: July 2012

The gaseous species in equilibrium with Cu(l), Ag(l), and Au(l) were investigated by vaporization studies according to the method of high temperature mass spectrometry with a Knudsen cell. From the observed ion intensity ratios of dimer to monomer and of trimer to monomer the dissociation enthalpies of Cu2, Ag2, and Au2 were redetermined. The following atomization and sublimation enthalpies for the trimer in kJ mol−1 could be additionally determined by assuming a linear structure for these molecules: D00(Cu3) = 294 ± 13, D00(Ag3) = 253 ± 13, D00(Au3) = 367 ± 13, δsubH00(Cu3) = 714 ± 13, δsubH00(Ag3) = 598 ± 12, and δsubH00(Au3) = 737 ± 13. At the mean temperature of the measurements of 1849 K (Cu), 1500 K (Ag), and 1883 K (Au) the vapour pressures of the trimers are by a factor of 2.4 · 107 (Cu3), 2.9 · 107 (Ag3), and 1.7 · 107 (Au3) smaller than those of the corresponding monomers.
Ostwald Ripening of Precipitates. II. The Irreversible Thermodynamics
Authors: Chan Sai‐Kit
Published: July 2012

It is shown that the Lagrangian in the path integral solution of I to the differential equation of Ostwald ripening is the sum of the dissipation potentials in the flux and force representations minus the rate of entropy production. Minimization of the Lagrangian leads to the conclusion that the size distribution evolves with time in accordance with Onsager's principle of least dissipation. The stability criterion for evolution of Glansdorff and Prigogine is also examined in the context of the Ostwald ripening process and is found to be satisfied by all particles during the growing phase of their life spans.
Determination of Diffusion Coefficients by Electrochemical Current‐Time Measurements
Authors: Heinze Jürgen
Published: July 2012

A considerably improved method has been developed for the absolute determination of diffusion coefficients from current‐time measurements. It is based on the use of stationary finite disk electrodes. Until recently, the current functions for these could be only approximately determined; they have now been calculated exactly by numerically solving the two‐dimensional diffusion equation. The same simple experimental conditions for apparatus and measuring apply as are usual for routine electroanalytical measurements. The experimental results are in close agreement with the classical data of Stackelberg et al. [8]. To facilitate evaluation and interpretation various working curves are presented.
Photochemische Zersetzung von gasförmigem Schwefelkohlenstoff als Störeffekt bei Gas‐Lasern
Authors: Steidl H. , Mikenda W. , Derkosch J. , Heresch F.
Published: July 2012

Es wird über eine photochemische Reaktion von gasförmigem CS2 berichtet, die erstmals im Inneren eines Laserresonators beobachtet wurde. Die Reaktion führt bereits bei extrem geringen CS2‐Konzentrationen (< 10 ppm), die durch Diffusion in das Innere des Resonators gelangen, zum Auftreten kleinster Aerosolteilchen, die infolge starker Lichtstreuung die Laseremission beeinträchtigen und sogar zum Erliegen bringen können. Die Reaktion wird durch den UV‐Anteil des Plasmalichtes (λ < 380 nm) bewirkt und kann auch durch andere Lichtquellen, die in diesem Bereich genügend Leistung aufweisen, initiiert werden. Die streuenden Teilchen wurden als Schwefel identifiziert, doch konnte auch das Entstehen von COS und H2S nachgewiesen werden.
Excess Enthalpies of Liquid Alkane Mixtures at Pressures up to 500 bar. II. Extension and Application of a Molecular Theory
Authors: Heintz A. , Lichtenthaler R. N.
Published: July 2012

The Prigogine‐Flory‐Patterson‐Theory and its applicability in predicting thermodynamic excess properties is tested. In particular the experimentally determined dependence of the excess enthalpyHEon pressure of some binary alkane mixtures is used in this investigation. A consistent description of the experimental results is only possible using a modified form of this theory, which accounts for the short range order observed for n‐alkanes. The development of the extended theory is presented and the new insight possible into the molecular structure of the liquids and their mixtures under investigation is discussed.
ESR Studies on the Reduction Process of Silver Zeolites
Authors: Hermerschmidt D. , Haul R.
Published: July 2012

It is shown by in situ ESR studies that H2 reduction of dehydrated AgA‐ and AgX‐zeolites proceeds via intermediate formation of Agn+6 (n < 6) clusters, located inside the cubooctahedral sodalite cages. On further reduction, submicroscopic Ag crystals (<5 nm) are formed, resulting in a conduction electron spin resonance signal. At higher temperatures (T > 200°C) crystal growth leads to larger crystallites (10–50 nm) as indicated by x‐ray line broadening.
Eine neue Potentialfunktion — das n‐exp‐6‐8‐Potential
Authors: Leicht D. , Lucas K.
Published: July 2012

Four potential functions with small number of parameters are tested in a systematic way with respect to their abilities to correlate and extrapolate data as well as to the physical significance of their parameters. Since none of these functions was satisfying as a whole, a new, more flexible function was introduced and investigated. Although the new function is only slightly better in terms of correlation and extrapolation, it can be shown, that it offers improvements in the values of the potential parameter and in the sensitivity of these parameters to data fitting.
The dual fluorescence of p‐substituted dialkylanilines: The twist mechanism occurs even in inert solvents
Authors: Wermuth G. , Rettig W. , Lippert E.
Published: July 2012

In nonpolar solvents p‐diethylaminobenzoic acid ethyl ester presents multiple fluorescence. The considerable temperature and viscosity dependence of the fluorescence quantum yields as well as solvatochromic effects on the long wavelength fluorescence FA make evident that the multiple fluorescence is to be traced back to the formation of a highly polar TICT (Twisted Intramolecular Charge Transfer) state.
Quantum rate theory of relaxation in symmetrical microscopic systems II: Preparation of initial states
Authors: Brickmann J.
Published: July 2012

The preparation process of initial quantum states for the relaxation in symmetrical molecular complexes is studied theoretically. It is shown that the possibility of preparing a definite quasistable molecular complex is drastically dependent on the magnitude of the minimal experimental error to detect this complex in real measurements. Consequences of the theory on the existence of classical and non classical structures of the 2‐norbornyl cation as intermediate complex in chemical reactions are discussed.
Das binäre System H2SO4—H2O;p,v, T‐Daten und Dampfdruckkurven in weiten Konzentrationsbereichen bei erhöhtem Druck
Authors: Giazitzoglou Z. , Wüster G.
Published: July 2012

The binary system H2SO4 — H2O has been investigated. p,v, T‐data of the pure vapour phase including five concentrations (y) 19.94, 39.72, 61.07, 77.04, and 98.92 Mol‐% H2SO4, a density range (1/v) from 1.1 to 38.3 g/1, pressures (p) up to about 50 bar, temperatures (T) up to 823 K, have been determined experimentally. Beside p,T,x‐data of the liquid phase were measured in a range of concentration (x) between 30.0 and 98.39 Mol‐% H2SO4 with pressures up to 50 bar and temperatures up to about 723 K. All experimental results are correlated using suitable equations.
Molecular interactions of hydrocarbon alkyl groups with carbon tetrachloride observed in the 13C NMR chemical shifts
Authors: Jackowski Karol , Kçki Zbigniew
Published: July 2012

The 13C NMR chemical shifts of n‐hexane, 2,3‐dimethylbutane, and 2,2,3,3‐tetramethylbutane solutions in cyclohexane and carbon tetrachloride were measured. The significant changes of chemical shifts were interpreted in terms of collision interactions, the nature of which was proposed to be the quantum mechanical exchange repulsion.
Shock tube measurements of the reaction behaviour of acetylene with O‐atoms
Authors: Löhr R. , Roth P.
Published: July 2012

By the direct measurement of the time dependent concentrations of H‐ and O‐atoms in the reaction zone behind shock waves using the ARAS‐technique, the reaction behaviour of acetylene with O‐atoms in the temperature range 1500 K ≤ T ≤ 2570 K at pressures of about 2 bars was investigated. The gas mixtures used consisted of argon with small initial concentrations of N2O (10 ppm to 100 ppm) and C2H2 (10 ppm to 25 ppm). Under the present conditions the results indicate a dominant influence of the reaction channels magnified image Which can be directly followed by the experiment. A good interpretation of the measurements is possible using the reaction rate coefficients

Extensive computer simulations with different models of secondary reactions show the dominant influence of the two given reaction channels for the present conditions and yield a practically perfect fit of the experimental values.
Partial information about the Mn2+‐CI−, Mn2+‐Br2+, and Mn2+‐BF4−pair distribution function together with the exchange dynamics from nuclear magnetic relaxation studies
Authors: Helm L. , Hertz H. G.
Published: July 2012

We report experimental results for the longitudinal and transverse relaxation rates of the35Cl and81Br nuclear magnetizations in aqueous electrolyte solutions containing the paramagnetic ion Mn2+as a function of the temperature and frequency.19F longitudinal relaxation rates are also reported for aqueous solutions of NaBF4+ MnBr2as a function of temperature and frequency. Using standard procedure the first coordination number of Mn2+with respect to the three anions mentioned are determined. Furthermore, residence times of these anions in the first coordination sphere are derived from the experimental data. Other auxiliary data like quadrupolar relaxation rates, electron spin relaxation times and scalar coupling constants are also reported and discussed.
Radiation‐electrochemistry of the colloidal gold micro‐electrode: Hydrogen formation by organic free radicals
Authors: Westerhausen J. , Henglein A. , Lilie J.
Published: July 2012

Various organic free radicals as well as Ni+ ions produce hydrogen in the presence of some 10−4 M of colloidal gold. The gold catalyst was prepared via the reduction of HAuCl4 either thermally by citrate or by y‐irradiation. The organic radicals were radiolytically produced. The mechanism of H2 formation includes electron transfer from the organic radicals to the gold particles, storage of a large number of electrons per gold particle, conversion of the electrons into adsorbed H‐atoms and desorption of the latter to form H2. — The rates of some of these steps were measured using the method of pulse radiolysis. 1‐Hydroxy‐1‐methyl ethyl radicals, (CH3)2COH, react with colloidal gold particles almost diffusion controlled provided that the gold particles are not charged with excess electrons. Charged gold particles react at a substantially lower rate. The stored electrons live seconds or even minutes depending on their number per gold particle. In the stationary state, up to 0.38 Coulomb of electrons could be stored per liter of a 2.9 · 10−4 molar gold solution, each gold particle carrying about 39 electrons. A comparison is also made between the catalytic activities of colloidal gold and silver. Due to the relative fast conversion of electrons into adsorbed H‐atoms, colloidal gold has less capacity for the storage of electrons than colloidal silver. — The dependence of the hydrogen yield on the pH of the solution, the concentration of gold, the size of the gold particles, the concentration of the polyvinyl alcohol stabilizer, and the intensity of radiation was also investigated. At high intensities, some of the radicals are destroyed in a gold catalysed disproportionation.
Electronic structure and transport in expanded mercury and in mercury‐xenon mixtures
Authors: Cheshnovsky O. , Even U. , Jortner Joshua , Hensel F.
Published: July 2012

We have compared the D.C. conductivity and the low‐concentration optical absorption coefficients of the two‐component Hg/Xe metal rare‐gas mixtures (MRGSM) and the one‐component expanded Mercury, the properties of both materials being expressed on a common density scale. For the density range corresponding to the strong scattering regime the transport properties of both materials are surprisingly similar. At high Xe concentration the polarization effects of the Xe atoms are of considerable importance, resulting in marked deviations between the transport properties of those two types of materials.
Cis→trans‐photoisomerization of thioindigo
Authors: Memming R. , Kobs K.
Published: July 2012

The mechanism of the cis→trans‐photoisomerization was investigated. Quantum yields of nearly unity were observed at temperatures around 180 K indicating that a twisting of the molecule excited into its S1‐state occurs. A detailed analysis has shown that both, an isomerization via the singlet as well as via the triplet state is possible. A kinetic model has been proposed which describes quantitatively the experimental results.
Über Beiträge einzelner Elektrodenprozesse zur Impedanz
Authors: Göhr Hermann
Published: July 2012

An electrode process is directly contributing to the impedance only in the case of its flux and its generalized force being connected with a charge transport and a voltage resp. (“electric process”). E. g. conduction and transfer reactions cause resistances, charging processes in the simplest case cause capacitances. Complications by gradients (e. g. of conductivity) within the dielectric are discussed. — A contribution to the impedance by another process appears provided that such a concentration is altered by it, the rate of an “electric process” depends on, too. Especially this is the case with common reactants. The kind of coupling is effecting a dependence of the contribution to the impedance on data of both processes. — The elements of impedance are determined by parameters independent of frequency, the meaning of which is discussed. In case of elements depending only on one parameter, it is a resistance, a capacity, a Warburg‐parameter, or an inductivity. Additional parameters have the meaning of rate or time constants or a geometrical meaning. From all parameters kinetic data of the electrode processes occurring are available. Therefore, the task of evaluation of impedance spectra may be understood as estimation of the values of these parameters.
Decomposition of carbon monoxide and its reaction with hydrogen on iron films under static conditions at pressures between 2 and 25 mbar and at temperatures between 373 and 573 K
Authors: Wedler G. , Körner H.
Published: July 2012

When carbon monoxide is adsorbed on iron films at temperaturesT≥ 373 K carbon dioxide and carbon are formed. The Boudouard equilibrium is, however, not established at the chosen reaction conditions. In the presence of hydrogen the carbon monoxide adsorption leads to the formation of methane, carbon dioxide, and water. There is no correlation between the formation of water and of methane. The methane formation increases with both the increase in the total pressure and the increase in the partial pressure ratiopH2:pco. The ratio of the partial pressures of CO, H2, CO2, and H2Opoint to the establishment of the water gas equilibrium at medium temperatures.