bluuebunny/crossref_metadata_2025_split huggingface dataset:
Applying the Discrete Element Method in Process Engineering
Authors: Theuerkauf J. , Dhodapkar S. , Manjunath K. , Jacob K. , Steinmetz T. 
Published: February 2003

AbstractThis paper provides insight into the application of discrete element modeling in the field of bulk solids handling. This is shown with examples starting with the calibration of a virtual numerical material used in the simulation to mimic the actual material’s behavior. Based on the calibration of the material, solid handling problems such as the flow patterns and the stress distribution in silos are discussed.
Uniaxial Testing and the Performance of a Pallet Press
Authors: Enstad G.G. , Ose S. 
Published: February 2003

AbstractIt is a common problem that powders become aerated during filling into sacks, causing increased volumes, low mechanical stability, bursting of sacks, dusting as air escapes, difficulties in palletizing, and stacking of the pallets. In order to overcome such problems, a pallet press was developed several years ago. The press is used to obtain a more uniform geometry and to get rid of excess air from palletized sacks by simply pressing the pallets into a rectangular shape. How a powder will behave during filling into sacks will depend on its properties. By testing the powders to be stored in this way, one can predict what advantages can be obtained by using the pallet press for specific powders. The applicability of a uniaxial tester, developed for testing flow properties of powders, has been investigated for this purpose by Tel‐Tek, POSTEC dept.
A Stressing Model for the Description and Optimization of Grinding Processes
Authors: Kwade A. 
Published: February 2003

AbstractThe comminution behavior of a mill is characterized by the frequency of stress events, and the stress energy, acting at each stress event. Based on this, a comminution result is determined by the number of stress events, and the stress intensity. The product of stress number and stress energy is proportional to the specific energy input. The proportionality factor is the energy transfer factor, which describes the percentage of energy that is used for stressing the product particles. Using the characteriztic numbers based on a few tests, the operating parameters can be optimized and different mills can be compared. The application of the stressing model is shown for stirred media mills.
Investigation and Modeling of Growth, Structure and Oxygen Penetration in Particle Supported Biofilms
Authors: Boessmann M. , Staudt C. , Neu T.R. , Horn H. , Hempel D.C. 
Published: February 2003

AbstractParticle supported biofilms have been investigated with respect to biofilm formation, substrate transport and utilization. The investigated autotrophic and heterotrophic biofilms were cultivated in airlift suspension reactors. CLSM was used to describe the biofilm structure by recording volumes of bacteria and EPS glycoconjugates. Additionally, the microelectrode technique was used to measure transport and substrate utilization in the biofilm system. The experimental results on the microscopic scale were used to improve a mathematical model for biofilm growth. The oxygen profiles measured in the particle supported biofilms and the data from CLSM were used to optimize the model parameters.
X‐ray Diffraction Studies on Mesophases of Cetyl‐ and Dodecyltrimethylammoniumbromide in Liquid Ammonia
Authors: Bzik Stefan , Jansen Martin 
Published: February 2003

AbstractWe have studied solutions of the surfactants cetyltrimethylammoniumbromide (CTAB) and dodecyltrimethylammoniumbromide (DTAB) in liquid ammonia with respect to the formation of lyotropic phases. For this purpose, a set‐up for performing X‐ray scattering experiments at temperatures up to 120 °C on samples containing liquid ammonia has been developed. Both systems form hexagonal and monoclinic lyotropic phases above the dissolving temperature of the surfactant, thus representing the first examples for lyotropic phases in liquid ammonia, and for monoclinic phases in nonaqueous solvents. The phase diagrams of CTAB/liquid NH3 and DTAB/liquid NH3 show similarities to their respective aqueous systems. However, the regions of existence of monoclinic phases are much larger in the ammonia system, while the cubic phases, as observed in the water based systems, do not seem to exist. The liquid‐crystalline phases found provide potentiality for preparing mesoporous, nitride‐based solids.
Determining the Strengths of Hydrogen Bonds in Solid‐State Ammonia and Urea: Insight from Periodic DFT Calculations
Authors: Morrison Carole A. , Siddick Muhammad M. 
Published: February 2003

AbstractPlane‐wave density functional theory has been applied to determine the strengths of hydrogen bonds in the phase I crystal structures of ammonia and urea. For ammonia, each component of the trifurcated hydrogen bond has been found to be almost as strong as a standard N‐H⋅⋅⋅N interaction, and for urea the strengths of the two different N‐H⋅⋅⋅O interactions have been determined by a quantum mechanical technique for the first time.
Cover Picture: Chem. Eur. J. 3/2003
Authors: Klapötke Thomas M. , Krumm Burkhard , Piotrowski Holger , Polborn Kurt , Holl Gerhard 
Published: February 2003

AbstractThe cover picture shows the molecular structure of an azido‐substituted hexabenzylhexaazaisowurtzitane (carbon: red, nitrogen: blue). The hexaazaisowurtzitane cage system, a 2,4,6,8,10,12‐hexaazatetracyclo[5.5.0.05,9.03,11]dodecane, consists, just as this shown derivative, entirely of carbon, nitrogen and hydrogen (omitted in this image). The synthesis of hexaazaisowurtzitanes is limited solely to the condensation of certain benzylamines with glyoxal. Further derived hexaazaisowurtzitanes exhibit properties that are useful for the possible application as energetic materials and/or propellants (see background). An investigation of the influence of azido‐ and fluoro‐substituted benzyl amines on the formation of this cage system is described by T. M. Klapötke, B. Krumm et al. on p. 687 ff.
Early–Late Heterobimetallic Alkoxides as Model Systems for Late‐Transition‐Metal Catalysts Supported on Titania
Authors: Fandos Rosa , Hernández Carolina , Otero Antonio , Rodríguez Ana , Ruiz María José , Terreros Pilar 
Published: February 2003

AbstractTitanium complexes with chelating alkoxide ligands [TiCp*(O2Bz)(OBzOH)] (1) and [TiCp*(Me){(OCH2)2Py}] (2) were synthesised by reaction of [TiCp*Me3] (Cp*=η5‐C5Me5) with 2‐hydroxybenzyl alcohol ((HO)2Bz) and 2,6‐pyridinedimethanol ((HOCH2)2Py), respectively. Complex 1 reacts with [{M(μ‐OH)(cod)}2] (M=Rh, Ir) to yield the early–late heterobimetallic complexes [TiCp*(O2Bz)2M(cod)] [M=Rh (3), Ir (4)]. Carbon monoxide readily replaces the COD ligand in 3 to give the rhodium dicarbonyl derivative [TiCp*(O2Bz)2Rh(CO)2] (5). Compound 2 reacts with [{M(μ‐OH)(cod)}2] (M=Rh, Ir) with protonolysis of a TiMe bond to give [TiCp*{(OCH2)2Py}(μ‐O)M(cod)] [M=Rh (6), Ir (7)]. The molecular structures of complexes 3, 5 and 7 were established by single‐crystal X‐ray diffraction studies.
New Mechanistic Insight into the Coupling Reactions of CO2 and Epoxides in the Presence of Zinc Complexes
Authors: Kim Hoon Sik , Kim Jai Jun , Lee Sang Deuk , Lah Myoung Soo , Moon Dohyun , Jang Ho Gyeom 
Published: February 2003

AbstractCoupling reactions of CO2 and epoxide to produce cyclic carbonates were performed in the presence of a catalyst [L2ZnX2] (L=pyridine or substituted pyridine; X=Cl, Br, I), and the effects of pyridine and halide ligands on the catalytic activity were investigated. The catalysts with electron‐donating substituents on pyridine ligands exhibit higher activity than those with unsubstituted pyridine ligands. On the other hand, the catalysts with electron‐withdrawing substituents at the 2‐position of the pyridine ligands show no activity; this demonstrates the importance of the basicity of the pyridine ligands. The catalytic activity of [L2ZnX2] was found to decrease with increasing electronegativity of the halide ligands. A series of highly active zinc complexes bridged by pyridinium alkoxy ions of the general formula [{(μ‐OCHRCH2L)ZnBr2}n] (n=2 for R=CH3; n=3 for R=H; L=pyridine or substituted pyridine) were synthesized and characterized by X‐ray crystallography. The dinuclear zinc complexes obtained from propylene oxide adopt a square‐planar geometry for the Zn2O2 core with two bridging pyridinium propoxy ion ligands. Trinuclear zinc complexes prepared from ethylene oxide adopt a boat geometry for the Zn3O3 core, in which three zinc and three oxygen atoms are arranged in an alternate fashion. These zinc complexes bridged by pyridinium alkoxy ions were also isolated from the coupling reactions of CO2 and epoxides performed in the presence of [L2ZnBr2]. Rapid CO2 insertion into the zincoxygen bond of the zinc complexes bridged by pyridinium alkoxy ions leads to the formation of zinc carbonate species; these which yield cyclic carbonates and zinc complexes bridged by pyridinium alkoxy ions upon interaction with epoxides. The mechanistic pathways for the formation of active species and cyclic carbonates are discussed on the basis of results from structural and spectroscopic analyses.
Synthesis and Structures of Trifluoromethyl‐, Fluoro‐, and Azido‐Substituted Hexabenzylhexaazaisowurtzitanes and Isolation of a Novel Hexaazaisowurtzitane‐Based Polycycle
Authors: Klapötke Thomas M. , Krumm Burkhard , Piotrowski Holger , Polborn Kurt , Holl Gerhard 
Published: February 2003

AbstractThe first hexabenzylhexaazaisowurtzitane cage compounds with trifluoromethyl and azide groups, as well as those with fluorine atoms in the 3‐ and 4‐positions, have been prepared and fully characterized. A study of the substituent influence on the benzene ring regarding the formation of the hexaazaisowurtzitane polycycle in either the 2‐ or 4‐position with CF3, F, and N3 revealed an interesting difference. In all cases with CF3, F, and N3 substituents in the 4‐position, the corresponding hexabenzylhexaazaisowurtzitanes were isolated. The corresponding hexabenzylhexaazaisowurtzitanes were also formed when these substituents were in the 2‐position; however, in addition with azide in 2‐position a novel type of polycycle was isolated and identified. 15N NMR data and crystal structures of hexabenzylhexaazaisowurtzitane derivatives were obtained and are discussed in detail.
Competitive Reactions of Interstrand and Intrastrand DNA‐Pt Adducts: A Dinuclear‐Platinum Complex Preferentially Forms a 1,4‐Interstrand Cross‐Link Rather than a 1,2 Intrastrand Cross‐link on Binding to a GG 14‐Mer Duplex
Authors: Berners‐Price Susan J. , Davies Murray S. , Cox John W. , Thomas Donald S. , Farrell Nicholas 
Published: February 2003

AbstractA study of the kinetics and mechanism of the reaction between the dinuclear Pt complex [{trans‐PtCl(NH3)2}2(μ‐NH2(CH2)6NH2)]2+ (1) and the 14‐mer duplex 5′‐d(ATACATG(7)G(8)TACATA)‐3′⋅5′‐d(TATG(25)TACCATG(18)TAT)‐3′ is reported. [1H,15N]‐HSQC NMR was used to follow the reaction at 298 K, pH 5.4. The product is primarily the 5′–5′ 1,4‐interstrand cross‐link between G(8) and G(18) bases and exists in two conformational forms. No evidence for the possible 1,2‐intrastrand G(7)G(8) adduct was seen, confirming the preferential formation of interstrand cross‐links by these dinuclear complexes. An initial electrostatic association of 15N‐1 with the duplex is indicated by changes in its 1H/15N chemical shifts, followed by aquation of 1 to form the monoaqua monochloro species 2, with a rate constant of 4.00±0.03×10−5 s−1. Monofunctional binding to the duplex occurs primarily at G(8), the 3′ base of the nucleophilic GG grouping, with a rate constant of 1.5±0.7 M−1 s−1. Changes in the 1H/15N shifts indicate there is an electrostatic interaction between the unbound {PtN3Cl} group of the monofunctional adduct and the duplex. No peaks for a transient aquated monofunctional species are seen and closure of 3 to form the 1,4‐G(8)G(18) interstrand cross‐link (5) was treated as direct, with a rate constant of 4.47±0.06×10−5 s−1. The G(8)G(18) cross‐link was confirmed from analysis of the NOESY NMR spectrum of the final product. Structural perturbations for the 1,4‐interstrand cross‐link extend over approximately four base‐pairs and are similar to those found for a 1,4‐interstrand cross‐link with a shorter 8‐mer ‐GTAC‐ sequence. A major distortion was evident for the 5′T (T(17)) adjacent to the platinated G(18), consistent with the findings from the use of chemical probes to investigate the conformation of 1,4‐interstrand cross‐links.
Dynamic Chemical Devices: Generation of Reversible Extension/Contraction Molecular Motion by Ion‐Triggered Single/Double Helix Interconversion
Authors: Barboiu Mihail , Vaughan Gavin , Kyritsakas Nathalie , Lehn Jean‐Marie 
Published: February 2003

AbstractThe polyheterocyclic strands 1‐H and 2‐H adopt a helical shape enforced by the pyridine–pyrimidine helicity codon. The crystal structure of 2‐H shows the formation of stacks of dimers of right‐ and left‐handed individual helices. Treatment of 1‐H and 2‐H with silver triflate results in the generation of double‐helical entities 1‐DH and 2‐DH, containing two strands and two silver ions. NMR studies and determination of the crystal structure of 2‐DH indicate that the duplex is stabilized by coordination of each Ag+ ion to two terminal bipyridine units, one from each strand, and by pronounced π–π stacking interactions between the internal heterocycles of the strands, yielding a very robust double helical structure. Reversible interconversion of the single and double helix may be achieved by addition of a cryptand capable of sequestering Ag+ and releasing it by protonation. Thus, successive addition of acid and base leads to reversible interconversion between the shorter (∼3.6 Å) single helix and the longer (∼10.3 Å) double helix, resulting in the generation of pronounced extension/contraction motion. The system 1,2‐H/1,2‐DH represents a dynamic chemical device undergoing ionic modulation of reversible molecular mechanical motion fueled by acid/base neutralization.
Synthesis and Solid‐State NMR Studies of P‐Vinylbenzylphosphonic Acid
Authors: Frantz Richard , Durand Jean‐Olivier , Carré Francis , Lanneau Gérard F. , Bideau Jean Le , Alonso Bruno , Massiot Dominique 
Published: February 2003

AbstractP‐Vinylbenzylphosphonic acid (2) was synthesized and crystallized in two phases A and B. The latter phase was easily converted into the former. Both phases were investigated by IR and solid‐state 31P and 1H NMR spectroscopy, and X‐ray crystallography. The use of recently developed NMR methods has enabled us to increase the usually poor resolution of solid‐state 1H spectra. This gave additional insights on the proton environments. In particular, two dimensional 2D 1H‐31P heteronuclear correlation (HETCOR) experiments, incorporating a Lee–Golburg homonuclear decoupling scheme, allowed description of the mixture of phase A and B.
Detection of tumor specific gene expression in bone marrow and peripheral blood from patients with small cell lung carcinoma
Authors: Shingyoji Masato , Takiguchi Yuichi , Watanabe Reiko , Hiroshima Kenzo , Motoori Ken , Kurosu Katsushi , Kasahara Yasunori , Tanabe Nobuhiro , Tatsumi Koichiro , Kuriyama Takayuki 
Published: February 2003

AbstractBACKGROUNDSmall cell lung carcinoma (SCLC) has the propensity to grow rapidly and metastasize extensively. Detection of micro‐dissemination of SCLC may have clinical relevance. For its detection, tumor‐specific gene expressions were examined in peripheral blood and bone marrow aspirate from patients with SCLC.METHODSExpression of prepro‐gastrin‐releasing peptide (preproGRP), neuromedin B receptor (NMB‐R) and gastrin‐releasing peptide receptor (GRP‐R) were examined by reverse transcriptase polymerase chain reaction (RT‐PCR) in peripheral blood and bone marrow aspirate from 40 untreated patients with SCLC. Control samples consisted of peripheral blood samples from 5 patients with nonsmall cell lung cancer (NSCLC) and 20 healthy volunteers.RESULTSPositive rates of preproGRP, NMB‐R, and GRP‐R in bone marrow aspirate of patients with SCLC were 23% (9/40), 8% (3/40), and 10% (4/40), respectively. Those rates in peripheral blood were 11% (4/38), 5% (2/38), and 29% (11/38), respectively. Although GRP‐R expression was detected in patients with NSCLC and in healthy volunteers, preproGRP and NMB‐R expressions were not detected in patients with NSCLC and in healthy volunteers. All three gene expressions in bone marrow were more frequently observed in patients with bone marrow metastasis, accessed by biopsy, than in patients without. PreproGRP gene expression in bone marrow was also more frequent in patients with bone metastasis, accessed by bone scintigram, than in patients without, and was related to poorer survival.CONCLUSIONSMicro‐dissemination of SCLC was detectable by RT‐PCR of preproGRP and NMB‐R, both specific for SCLC. These gene expressions in bone marrow may be related to disease extent and prognosis. Cancer 2003;97:1057–62. © 2003 American Cancer Society.DOI 10.1002/cncr.11108
Evaluation of responses to chemoembolization in patients with unresectable hepatocellular carcinoma
Authors: Ebied Osama M. , Federle Michael P. , Carr Brian I. , Pealer Karen M. , Li Wei , Amesur Nikhil , Zajko Albert 
Published: February 2003

AbstractBACKGROUNDThe authors used computed tomography (CT) scans to correlate the changes in tumor vascularity, necrosis, and size with response and survival after transcatheter arterial chemoembolization (TACE) in patients with advanced, unresectable, hepatocellular carcinoma (HCC).METHODSThe authors studied 72 patients with biopsy‐proven, unresectable HCC and focused on 186 individual tumor masses. A baseline, multiphase, helical CT was performed and at least three follow‐up CT scans were performed after treatment by TACE. Tumors were classified as hypervascular or hypovascular and patients were classified as responders or nonresponders based on CT evidence of altered tumor size, tumor necrosis, and the appearance of new tumors. A new scoring system was used to monitor patient response to TACE.RESULTSThirty‐eight patients were responders and 34 were nonresponders. Patient survival was significantly increased (P = 0.009) in patients who were hypervascular responders. Survival also was increased in hypervascular nonresponders compared with hypovascular nonresponders (P = 0.008) and in hypovascular responders compared with hypovascular nonresponders (P = 0.002). Response to chemoembolization was found to be significantly (P = 0.02) and inversely proportional to tumor size, but the number of tumor foci in an individual patient was not predictive.CONCLUSIONSTACE appears to result in improved survival among HCC patients with hypervascular tumors who responded to therapy. However, even patients classified by CT as hypervascular nonresponders and hypovascular responders have improved survival. Cancer 2003;97:1042–50. © 2003 American Cancer Society.DOI 10.1002/cncr.11111
Stereotactic linear accelerater‐based radiosurgery for the treatment of patients with glomus jugulare tumors
Authors: Maarouf Mohammad , Voges Jürgen , Landwehr Peter , Bramer Rainer , Treuer Harald , Kocher Martin , Müller Rolf‐Peter , Sturm Volker 
Published: February 2003

AbstractBACKGROUNDThe optimal treatment for patients with glomus jugulare tumor (GJT) of the skull base remains controversial. Surgical excision is associated with a high incidence of cranial nerve injury, decreased quality of life, and high mortality. Fractionated radiotherapy is used to control the majority of these tumors, but disadvantages are a prolonged therapy interval and exposition of adjacent brain tissue to irradiation. The authors present the results of a study on 12 of 14 consecutively admitted patients who were treated using linear accelerator‐based radiosurgery (LINAC‐RS), an innovative method for the treatment of GJT.METHODSFrom May 1991 to March 2001, 14 patients with GJT were treated with stereotactic LINAC‐RS for continued growth of tumor or of remaining tumor after surgery. Twelve patients (9 women and 3 men; age range, 28–71 years; median age, 59 years) with a median follow‐up of 4 years (range, 0.8–9,0 years), were selected for retrospective analysis. A median single dose of 15 grays (Gy; range, 11–20 Gy) was applied to the surface of the tumor.RESULTSAfter undergoing LINAC‐RS, 8 of 12 patients (67%) reported partial or complete subjective improvement, whereas complaints remained unchanged in 4 patients (33%). Neurologic status improved in 3 patients (25%) and remained unchanged in 8 patients (67%). Magnetic resonance images showed tumor shrinkage in 8 patients (67%) and no further progression in 4 patients (33%).CONCLUSIONSLINAC‐RS is an effective and safe therapy for patients with GJT and may be used as an alternative to surgical resection. Compared with fractionated radiotherapy, LINAC‐RS has some advantages. However, to clarify the question of long‐term tumor control, longer observation times are required. Cancer 2003;97:1093–98. © 2003 American Cancer Society.DOI 10.1002/cncr.11118
Does local recurrence affect the rate of distant metastases and survival in patients with early‐stage breast carcinoma treated with breast‐conserving therapy?
Authors: Vicini Frank A. , Kestin Larry , Huang Raywin , Martinez Alvaro 
Published: February 2003

AbstractBACKGROUNDThe purpose of the current analysis was to evaluate the impact of local recurrence (LR) on the development of distant metastases (DM), overall survival (OS), and cause specific survival (CSS) in patients with early‐stage breast carcinoma who underwent conservative surgery (CS) and received postoperative radiotherapy (RT).METHODSBetween 1980 and 1995, 1169 patients underwent CS and received RT. All patients were followed for > 1 year and had ≤ 4 lymph nodes involved with disease. The median duration of follow‐up was 7.7 years. A Cox proportional hazards model was performed to evaluate the effect of LR on the development of DM and CSS. A matched‐pair analysis that controlled for multiple prognostic factors also was performed comparing the outcomes of patients with and without LR.RESULTSThe LR rate was 11% at 12 years. For the entire population, LR led to poorer OS and CSS rates at 12 years compared with local control (LC) (71% vs. 81% [P = 0.001] and 69% vs. 88% [P < 0.001], respectively). In a Cox multiple regression model, LR was a significant predictor of disease specific mortality. The hazard ratio (HR) associated with LR was 2.69 for mortality and 2.67 for DM (P < 0.001 and P < 0.001, respectively). The median time from surgery to the development of DM was 3.8 years for patients without LR compared with 4.7 years for patients with LR. Patients who developed LR also had two peaks in the rate of DM (at 2.5 years and at 6.5 years) compared to only one peak (at 1.5 years) for patients who did not develop LR. The impact of LR on DM still was evident in patients with small tumors (≤ 2.0 cm; P < 0.001), negative lymph nodes (P = 0.004), or both (P < 0.001). Recurrent disease that developed outside of the surgical bed region had no negative effect on survival. In the matched‐pair analysis (controlling for age, tumor size, grade, number of positive lymph nodes, and estrogen receptor status), LR remained the most significant predictor of mortality (HR: mortality, 5.86; DM, 6.43).CONCLUSIONSThe current results suggest that LR may be responsible for an increase in DM and disease specific mortality in patients who undergo CS and receive RT. This suggestion is reinforced by the distinct difference seen in the time distribution of DM after LR developed and by the fact that recurrent disease that originated outside of the surgical bed did not affect OS. These data reinforce the necessity to insure optimal LC in patients who are treated with breast‐conserving therapy. Cancer 2003;97:910–9. © 2003 American Cancer Society.DOI 10.1002/cncr.11143