bluuebunny/crossref_metadata_2025 huggingface dataset:
Endoscopic Endonasal Transsphenoidal Surgery
Authors: Cappabianca Paolo , Cavallo Luigi Maria , de Divitiis Enrico
Published: October 2004

THE ENDOSCOPIC ENDONASAL TRANSSPHENOIDAL approach is a minimally invasive surgical technique for the removal of sellar and parasellar lesions. The procedure is performed via an anterior sphenoidotomy. The two main characteristics of the endoscopic approach, when compared with the standard microsurgical operation, arise from the use of the endoscope as a unique optical device and from the absence of a transsphenoidal retractor. More convenient straight surgical instruments are employed, whereas bayonet-shaped tools are used in the microsurgical procedure, to avoid any interference with the light beam generated by the microscope. The standard surgical technique is composed of three main time phases: the nasal, sphenoid, and sellar phase. During the nasal phase, the scope is introduced through the chosen nostril and advanced up to the sphenoethmoid recess, where the sphenoidotomy is performed. The sphenoid phase consists of the detachment of the nasal septum from the sphenoid rostrum, the anterior sphenoidotomy, removal of the sphenoid septum or septa, and identification of the landmarks inside the sphenoid sinus. In the sellar phase, an opening of the sellar floor is performed for removal of the lesion. A wide view of the sellar environment is obtained through angled scopes to detect eventual tumor remnants. The procedure ends with the reconstruction of the sella and removal of the endoscope from the nostril, without any postoperative nasal packing.
Functional Magnetic Resonance Imaging-integrated Neuronavigation: Correlation between Lesion-to-Motor Cortex Distance and Outcome
Authors: Krishnan René , Raabe Andreas , Hattingen Elke , Szelényi Andrea , Yahya Hilal , Hermann Elvis , Zimmermann Michael , Seifert Volker
Published: October 2004

OBJECTIVE:

The integration of functional magnetic resonance imaging (fMRI) data into neuronavigation is a new concept for surgery adjacent to the motor cortex. However, the clinical value remains to be defined. In this study, we investigated the correlation between the lesion-to-fMRI activation distance and the occurrence of a new postoperative deficit.

METHODS:

fMRI-integrated “functional” neuronavigation was used for surgery around the motor strip in 54 patients. During standardized paradigms for hand, foot, and tongue movements, echo-planar imaging T2* blood oxygen level-dependent sequences were acquired and processed with BrainVoyager 2000 software (Brain Innovation, Maastricht, The Netherlands). Neuronavigation was performed with the VectorVision2 system (BrainLAB, Heimstetten, Germany). For outcome analysis, patient age, histological findings, size of lesion, distance to the fMRI areas, preoperative and postoperative Karnofsky index, postoperative motor deficit, and type of resection were analyzed.

RESULTS:

In 45 patients, a gross total resection (>95%) was performed, and for 9 lesions (low-grade glioma, 4; glioblastoma, 5), a subtotal resection (80–95%) was achieved. The neurological outcome improved in 16 patients (29.6%), was unchanged in 29 patients (53.7%), and deteriorated in 9 patients (16.7%). Significant predictors of a new neurological deficit were a lesion-to-activation distance of less than 5 mm (P < 0.01) and incomplete resection (P < 0.05).

CONCLUSION:

fMRI-integrated neuronavigation is a useful concept to assess the risk of a new motor deficit after surgery. Our data suggest that a lesion-to-activation distance of less than 5 mm is associated with a higher risk of neurological deterioration. Within a 10-mm range, cortical stimulation should be performed. For a lesion-to-activation distance of more than 10 mm, a complete resection can be achieved safely. The visualization of fiber tracks is desirable to complete the representation of the motor system.
Feasibility of Radiosurgery for Malignant Brain Tumors in Infants by Use of Image-guided Robotic Radiosurgery: Preliminary Report
Authors: Giller Cole A. , Berger Brian D. , Gilio Joseph P. , Delp Janice L. , Gall Kenneth P. , Weprin Bradley , Bowers Daniel
Published: October 2004

OBJECTIVE:

The benefits of radiation therapy are generally denied to infants with malignant brain tumors because of the risk of devastating cognitive decline. Efforts to limit this morbidity with radiosurgical techniques have not been feasible for infants because of the dual requirements of rigid head fixation and high precision. We report the radiosurgical treatment of five infants by use of a robotically controlled system without rigid head fixation.

METHODS:

Five infants with malignant brain tumors received radiosurgical treatment with a robotically driven linear accelerator. Immobilization was aided by general anesthesia, form-fitting head supports, face masks, and body molds. The average marginal dose was 17 ± 2 Gy, and the average treatment volume was 18 ± 22 ml.

RESULTS:

X-rays obtained during treatment revealed acceptable agreement with preoperative computed tomographic scans in all patients. In one patient, the lesion did not progress, but a distant recurrence occurred 15 months after radiosurgery and also was treated with radiosurgery. In another patient, tumor in the treated region did not progress, but recurrence elsewhere led to death 7 months after treatment. Tumor enlargement occurred in Patient 3 at 3 months posttreatment, leading to death 2 months later. Tumor size was smaller in the remaining two patients at 9 and 11 months after treatment. There has been no toxicity attributed to treatment.

CONCLUSION:

Radiosurgery with minimal toxicity can be delivered to infants by use of a robotically controlled system that does not require rigid fixation. A formal dose-escalation trial is under way to address dose and toxicity for infants more thoroughly.
Thoracic Outlet Syndrome
Authors: Huang Jason H. , Zager Eric L.
Published: October 2004

OBJECTIVE:

Thoracic outlet syndrome (TOS) is one of the most controversial clinical entities in medicine. We provide a review of this difficult-to-treat disorder, including a brief overview, clinical presentations, surgical anatomy, treatment options, and outcomes.

METHODS:

TOS represents a spectrum of disorders encompassing three related syndromes: compression of the brachial plexus (neurogenic TOS), compression of the subclavian artery or vein (vascular TOS), and the nonspecific or disputed type of TOS. Neurovascular compression may be observed most commonly in the interscalene triangle, but it also has been described in the costoclavicular space and in the subcoracoid space. Patients present with symptoms and signs of arterial insufficiency, venous obstruction, painless wasting of intrinsic hand muscles, paresthesia, and pain. A careful and detailed medical history and physical examination are the most important diagnostic tools for proper identification of TOS. Electromyography, nerve conduction studies, and imaging of the cervical spine and the chest also can provide helpful information regarding diagnosis. Clinical management usually starts with conservative treatment including exercise programs and physical therapy; when these therapies fail, patients are considered for surgery. Two of the most commonly used surgical approaches are the supraclavicular exposure and the transaxillary approach with first rib resection. On occasion, these approaches may be combined or, alternatively, posterior subscapular exposure may be used in selected patients.

CONCLUSION:

TOS is perhaps the most difficult entrapment neuropathy encountered by neurosurgeons. Surgical intervention is indicated for vascular and true neurogenic TOS and for some patients with the common or nonspecific type of TOS in whom nonoperative therapies fail. With careful patient selection, operative intervention usually yields satisfactory results.
Relationship of Local Infarctions to Cognitive and Psychosocial Impairments after Aneurysmal Subarachnoid Hemorrhage
Authors: Vilkki Juhani S. , Juvela Seppo , Siironen Jari , Ilvonen Titta , Varis Joona , Porras Matti
Published: October 2004

OBJECTIVE:

Previous studies suggest that cognitive and psychosocial impairments after subarachnoid hemorrhage (SAH) result from diffuse brain damage caused by the initial bleeding rather than from focal lesions. We describe the relationship of local infarctions to these impairments and explore how well test and questionnaire results explain psychosocial outcome.

METHODS:

A total of 170 patients, selected from a consecutive series of patients with aneurysmal SAH, underwent neurological and neuroradiological examinations, and 138 of them were assessed with neuropsychological tests and questionnaires 1 year after SAH.

RESULTS:

Patients with left and bilateral infarctions performed worse on verbal memory tests than the other patients, and patients with left infarctions had more impaired working capacity than those with no infarction. The indices of the severity of SAH were related to reductions in both working capacity and social activity but less clearly to poor test performances. Whereas the modified Rankin scale was the most important correlate of working capacity, performance on cognitive tests was associated with return to work, and questionnaire ratings of mental impairments correlated with reduced working capacity and decreased social activity.

CONCLUSION:

Left-hemisphere infarctions cause deficits in verbal memory and working capacity. The severity of SAH is associated with impairments in working capacity and social activity rather than with specific cognitive deficits. Patients' and partners' opinions on patients' mental impairments could provide complementary information to clinical grades and cognitive tests in the evaluation of outcome after SAH.
Spinal Dural Arteriovenous Fistulae: Analysis of Outcome in Relation to Pretreatment Indicators
Authors: Cenzato Marco , Versari Pietro , Righi Claudio , Simionato Franco , Casali Cecilia , Giovanelli Massimo
Published: October 2004

OBJECTIVE:

The outcome of treatment for a spinal dural arteriovenous fistula is unpredictable. In this study, we reviewed the outcome of patients treated for this condition, in relation to pretreatment indicators.

METHODS:

We reviewed the records of 37 consecutive patients treated either surgically or endovascularly in our department between 1989 and 2002.

RESULTS:

At follow-up, 78% of the patients reported improvement. Those with motor symptoms had the best outcome: improvement was achieved in more than 60% of the patients, amounting to 1 or 2 points on the Aminoff scale. Sensory disorders improved in 43% of cases, pain in 61%, and sphincter impairment in only 37%. Patients with a fistula in the lower thoracic region did better than those with fistulae in other locations.

CONCLUSION:

The clinical state before treatment is certainly relevant in predicting outcome. Age and duration of the symptoms before treatment have no direct relation to the chances of improvement with treatment, particularly when motor improvement is considered. The modality of onset of symptoms and location of the fistula play significant roles, also: a fistula in the lower thoracic segment was associated with more severe symptoms but tended to improve more (83%, P = 0.04) after treatment. Midthoracic and lumbar fistulae showed a lower incidence of improvement (<50%).
Relationship between Valve Opening Pressure, Body Position, and Intracranial Pressure in Normal Pressure Hydrocephalus: Paradigm for Selection of Programmable Valve Pressure Setting
Authors: Bergsneider Marvin , Yang Isaac , Hu Xiao , McArthur David L. , Cook Shon W. , Boscardin W J.
Published: October 2004

OBJECTIVE:

There is little scientific basis for guidance in selecting the optimal valve for the treatment of normal pressure hydrocephalus. The aim of this study was to determine the programmable valve opening pressure setting that would result in a slight reduction in intracranial pressure (ICP) after a ventriculoperitoneal shunt is implanted. We also assessed whether shunt-induced ICP could be predicted on the basis of a simple hydrodynamic equation.

METHODS:

In this prospective study of 11 patients with normal pressure hydrocephalus, ICP was measured before and after implantation of a shunt incorporating a programmable valve without an antisiphon device. Pressure measurements, including intraperitoneal pressure, were recorded at body angles ranging from 0 to 55 degrees and at valve settings ranging from 30 to 200 mm H2O. Measured ICP values were compared with values computed using a simple hydrodynamic equation.

RESULTS:

Even at a valve setting greater than the mean baseline ICP (200 mm H2O), the supine ICP was significantly lower than the baseline value (baseline ICP, 164 ± 64 mm H2O; postoperative ICP, 125 ± 69 mm H2O, P = 0.04). Valve pressure did not equate 1:1 with the measured postoperative ICP. Comprehensive ICP measurements at upright body positions demonstrated a stepwise reduction in ICP rather than a precipitous decline as a result of so-called siphoning.

CONCLUSION:

This study indicates that very high valve opening pressure settings may be optimal for the initial treatment of normal pressure hydrocephalus. The relationship between ICP and opening pressure valves is linear but not predicted by simple hydrodynamics.
Treatment of Unruptured Cerebral Aneurysms by Embolization with Guglielmi Detachable Coils: Case-fatality, Morbidity, and Effectiveness in Preventing Bleeding—A Systematic Review of the Literature
Authors: Lanterna Luigi A. , Tredici Giovanni , Dimitrov Borislav D. , Biroli Francesco
Published: October 2004

OBJECTIVE:

Guglielmi detachable coils (GDCs) increasingly are being used to treat unruptured cerebral aneurysms (UCAs). We systematically reviewed the literature to assess the case-fatality and permanent morbidity rates of GDC embolization of UCAs and the postembolization bleeding rate.

METHODS:

Through a MEDLINE search of the English, Italian, and French literature from January 1990 through December 2002, we retrieved studies on GDC embolization of aneurysms and extracted data on UCAs. Inclusion criteria were: 1) attempted GDC embolization of at least five consecutive patients with UCAs, 2) reported percentage of at least either case-fatality or permanent morbidity rate or crude data allowing an independent calculation. When data on UCAs could not be characterized with certainty among data on other, different lesions, the study was rejected.

RESULTS:

We included 30 studies. One thousand three hundred seventy-nine patients were available for the calculation of the case-fatality rate, 794 for the permanent morbidity rate, and 703 for the bleeding rate. The case-fatality rate was 0.6% (95% confidence interval, 0.2–1%), the permanent morbidity rate was 7% (95% confidence interval, 5.3–8.7%), and the bleeding rate was 0.9% per year (95% confidence interval, 0.41–1.4%). Only incompletely coiled UCAs of 10 mm or more accounted for the bleeding events. Morbidity decreased from 8.6% to 4.5% (P < 0.05) when the midyear of study (average calendar year of treatment) was 1995 or later.

CONCLUSION:

GDC embolization of UCAs is relatively safe, and the outcome is progressively improving. Partial embolization of UCAs of 10 mm or more is unlikely to provide an acceptable protection. Most of the source publications suffer from methodological weaknesses. Prospective studies with longer follow-up periods are needed to definitively assess the effectiveness of GDCs on UCAs.
Functional Magnetic Resonance Imaging and Optical Imaging for Dominant-hemisphere Perisylvian Arteriovenous Malformations
Authors: Cannestra Andrew F. , Pouratian Nader , Forage James , Bookheimer Susan Y. , Martin Neil A. , Toga Arthur W.
Published: October 2004

OBJECTIVE:

In this study, we developed an a priori system to stratify surgical intervention of perisylvian arteriovenous malformations (AVMs) in 20 patients. We stratified the patients into three categories based on preoperative functional magnetic resonance imaging (fMRI) language activation pattern and relative location of the AVM.

METHODS:

In Group I (minimal risk), the AVM was at least one gyrus removed from language activation, and patients subsequently underwent asleep resection. In Group II (high risk), the AVM and language activation were intimately associated. Because the risk of postoperative language deficit was high, these patients were then referred to radiosurgery. In Group III (indeterminate risk), the AVM and language were adjacent to each other. The risk of language deficit could not be predicted on the basis of the fMRI alone. These patients underwent awake craniotomy with electrocortical stimulation mapping and optical imaging of intrinsic signals for language mapping.

RESULTS:

All patients from Group I (minimal risk) underwent asleep resection without deficit. All Group II (high-risk) patients tolerated radiosurgery without complication. In Group III (indeterminate risk), three patients underwent successful resection, whereas two underwent aborted resection after intracranial mapping.

CONCLUSION:

We advocate the use of fMRI to assist in the preoperative determination of operability by asleep versus awake craniotomy versus radiosurgery referral. In addition, we advocate the use of all three functional mapping (fMRI, electrocortical stimulation mapping, and optical imaging of intrinsic signals) techniques to clarify the eloquence score of the Spetzler-Martin system before definitive treatment (anesthetized resection versus radiosurgery versus intraoperative resection versus intraoperative closure and radiosurgery referral).
Taurine Detection by Proton Magnetic Resonance Spectroscopy in Medulloblastoma: Contribution to Noninvasive Differential Diagnosis with Cerebellar Astrocytoma
Authors: Moreno-Torres Ángel , Martínez-Pérez Irene , Baquero Miguel , Campistol Jaume , Capdevila Antoni , Arús Carles , Pujol Jesus
Published: October 2004

OBJECTIVE:

We sought to evaluate whether taurine detection in short-echo (20 ms) proton magnetic resonance spectroscopy contributes to the noninvasive differential diagnosis between medulloblastoma and cerebellar astrocytoma in children and young adults. These two types of tumor have very different prognoses and may be difficult to differentiate by neuroradiological or clinical means.

METHODS:

Single-voxel proton magnetic resonance spectra of tumors were acquired at 1.5 T in 14 patients with biopsy-proven primary cerebellar tumors (six medulloblastomas, seven astrocytomas, and one mixed astroependymoma) using short-echo time (20 ms) and long-echo time (135 ms). For taurine assignment, qualitative analysis was performed on short-echo time spectra and results were compared in vitro with spectra of model solutions. Perchloric acid extracts of postsurgical tumor biopsies were performed in two medulloblastoma cases.

RESULTS:

Taurine detection was demonstrated in all patients with medulloblastoma and in none of those with astrocytoma. We were unable to ascertain any relationship between taurine and metastatic spread within the medulloblastoma group.

CONCLUSION:

Medulloblastomas characteristically seem to show taurine detectable in vivo by short-echo proton magnetic resonance spectroscopy, which may help to discriminate medulloblastoma from cerebellar astrocytoma.
Operative Findings and Outcomes of Microvascular Decompression for Trigeminal Neuralgia in 35 Patients Affected by Multiple Sclerosis
Authors: Broggi Giovanni , Ferroli Paolo , Franzini Angelo , Nazzi Vittoria , Farina Laura , La Mantia Loredana , Milanese Clara
Published: October 2004

OBJECTIVE:

The concept of vascular compression of the trigeminal root as the main etiological factor in idiopathic trigeminal neuralgia has achieved widespread acceptance, and microvascular decompression (MVD) is a well-established surgical procedure for its treatment. Multiple sclerosis (MS) has long been considered to be an absolute contraindication to MVD because of the supposed exclusive causative role of a demyelinating lesion affecting the trigeminal root entry zone. Magnetic resonance imaging preoperative identification of suspicious vessels along the cisternal course of the trigeminal nerve in MS patients raises the question of a possible causative role of vascular compression in MS patients.

METHODS:

We describe magnetic resonance imaging findings, surgical findings, and outcomes in 35 MS patients who underwent MVD for medically intractable trigeminal neuralgia. Results were assessed by clinical follow-up and periodic phone surveys. The mean follow-up was 44 months (range, 6–108 mo).

RESULTS:

Magnetic resonance imaging revealed the presence of demyelinating lesions affecting the brainstem trigeminal pathways of the painful side in 26 (74%) of 35 patients. During surgery, severe neurovascular compression at the trigeminal root entry zone was found in 16 (46%) of 35 patients. The long-term outcome was excellent in 39%, good in 14%, fair in 8%, and poor in 39% of patients. No statistically significant prognostic factor predicting good outcome could be found. There was no mortality, with a 2.5% long-term morbidity rate (facial nerve palsy in one patient).

CONCLUSION:

Results of MVD in trigeminal neuralgia MS patients are much less satisfactory than in the idiopathic group, indicating that central mechanisms play a major role in pain genesis.
Microvascular Decompression for Trigeminal Neuralgia in the Elderly: A Review of the Safety and Efficacy
Authors: Ashkan Keyoumars , Marsh Henry
Published: October 2004

OBJECTIVE:

To critically examine the efficacy and safety of microvascular decompression (MVD) for trigeminal neuralgia (TN) in elderly patients.

METHODS:

We performed a retrospective review of medical records, followed by prospective follow-up. The outcome data from 44 MVD operations for TN performed in 40 consecutive patients with a mean age of 65 years (range, 60–75 yr) in the period 1991 to 2001 were compared with those from 40 younger control subjects (mean age, 46 yr; range, 20–59 yr) operated on during the same period.

RESULTS:

The median time from diagnosis of TN to MVD in the older patients was 7 years (range, 1–22 yr), compared with 3 years (range, 3 mo to 20 yr) in the younger group (P = 0.02). With the exception of one, all patients in this study were classified as American Society of Anesthesiologist Grade 1 or 2. Initial pain relief was achieved in 98 and 100% of the patients in the study and control groups, respectively. There were no operative mortalities or life-threatening morbidities. Transient facial numbness and diplopia occurred in both groups. Headaches, nausea, and vomiting were more frequent in the younger patients, whereas wound infection and confusion were more common in the older patients. The mean length of hospital stay was 5.4 days (range, 3–10 d) for the older patients, compared with 5.3 days (range, 3–9 d) for the control group (P = 0.4). After average follow-ups of 30 and 33 months, the pain recurred in 24 and 27% of the patients in the elderly and control groups, respectively.

CONCLUSION:

MVD is underused in the elderly despite being both safe and effective. Fitness and not age should be the key in deciding the treatment options. It is proposed that any patient with medically refractory TN who is fit for general anesthesia should be given the opportunity to choose MVD.
Gilliatt-Sumner Hand Revisited: A 25-year Experience
Authors: Tender Gabriel C. , Thomas Ajith J. , Thomas Najeeb , Kline David G.
Published: October 2004

OBJECTIVE:

Thirty-three patients with true neurogenic thoracic outlet syndrome, or Gilliatt-Sumner hand, underwent surgical treatment at Louisiana State University during a 25-year period. This study retrospectively evaluated the outcome referable to pain and motor function in these patients.

METHODS:

All patients had the typical Gilliatt-Sumner hand, secondary to compression of C8, T1, and/or lower trunk. Nineteen patients underwent an anterior supraclavicular approach, and 15 patients underwent a posterior subscapular approach to the brachial plexus. Nerve action potential recordings showed plexus involvement close to the spine, at the level of the junction of the spinal nerves to the lower trunk.

RESULTS:

Pain, present in 22 patients, improved in 21. Mild motor deficit improved in 12 of 14 patients. Severe motor deficit improved partially in 14 of 20 patients.

CONCLUSION:

The diagnosis of true neurogenic thoracic outlet syndrome provides a clear operative indication. Surgical decompression needs to involve the medial portion of the plexus, and especially the spinal nerves. An anterior supraclavicular approach is preferred in most cases. If there is a large cervical rib or there has been a prior anterior operation, then a posterior subscapular approach is indicated.
Development of Hybrid Integrated Endoscope-holder System for Endoscopic Microneurosurgery
Authors: Morita Akio , Okada Yoshikazu , Kitano Masahiko , Hori Tomokatsu , Taneda Mamoru , Kirino Takaaki
Published: October 2004

OBJECTIVE:

Endoscopic techniques in the field of neurosurgery are under development. To perform sophisticated bimanual procedures in the delicate surgical fields of neurosurgery, rigid endoscope fixation devices with accurate locking and a safe releasing system are required. Here, we report the development of a new hybrid integrated endoscope-holder system.

INSTRUMENTATION:

The basic concepts of the holding device were as follows: 1) it should combine both video system and holding device; 2) it should have easy maneuverability and accurate fixation and be equipped with a safe releasing mechanism; and 3) it should be able to be used universally either in a primary or an assisting endoscopic procedure. A negatively actuated air-locking system and a bayonet-shaped endoscope were newly developed. Clinical trials of 25 patients were performed, and each prototype was tested and modified until the functional requirements were fulfilled. The final version was tested for accuracy and security in fixation and releasing mechanism.

RESULTS:

Eight problems were encountered in the clinical trials and improved. Accuracy in fixation of the final version was superior to the most advanced endoscope-holder on the market. No dangerous events were observed during repetitive insertion, fixation, and release in the simulated deep surgical field in the cadaveric skull. No apparent complications were noted in the clinical application.

CONCLUSION:

We have developed a highly reliable, accurately fixable, and easily maneuverable hybrid endoscope-holder system. To achieve a safer, more accurate, and less invasive surgery in the current socioeconomic demands, commercial manufacturers and surgeons in multiple centers need to combine their efforts to create useful techniques.
Multi-Stage Amphoteric Redox Hydrocarbons Based on a Phenalenyl Radical
Authors: Nakasuji Kazuhiro , Kubo Takashi
Published: October 2004

Molecular design and properties of amphoteric redox hydrocarbons are reviewed. Our molecular design is based on a phenalenyl radical, which has a non-bonding molecular orbital with an occupation number of one and is known to behave as a two-stage amphoteric redox system. We have prepared eight amphoteric redox compounds containing two or three phenalenyl units. Cyclic voltammetry showing small E1sum values confirms the high amphotericity of these compounds. The properties of ionic redox species generated are also investigated. At the last part of this account, we show some aspects of a singlet biradicaloid character that originates from a small HOMO–LUMO gap.
A New Application of High-Viscosity Kinetics. An Attempt to Identify a Site of Solvent Reorganizations around a Reactant
Authors: Sugita Keijiro , Goto Yoshitaka , Ono Mikiko , Yamashita Kazumi , Hayase Kayoko , Takahashi Toru , Ohga Yasushi , Asano Tsutomu
Published: October 2004

Thermal fading of a colored species photochemically generated from so-called chromenes was kinetically studied in highly viscous media. The reaction was retarded by an increase in viscosity at viscosities higher than 102 Pa s. We propose to use substituent dependence of this retarding effect as a tool to identify the main site of solvent reorganizations around the reactant molecule in the activation step.
Experimental Evidence of Differences in the Hydrogen-Bonded Structure of Concentrated Aqueous Solutions Involving Dl- and l-Alanine Molecules
Authors: Kameda Yasuo , Sasaki Motoya , Yaegashi Masahiro , Amo Yuko , Usuki Takeshi
Published: October 2004

Time-of-Flight (TOF) and steady state reactor neutron diffraction measurements have been carried out for aqueous 2.5 mol% Dl- and l-alanine solutions in order to investigate the differences in intermolecular hydrogen-bonded structure between solutions involving amino acid molecules with different optical activities. The observed difference functions, Δi(Q) and Δiinter(Q), between observed scattering cross sections for Dl- and l-alanine solutions with a D content of 96.1% exhibit the first peak located at Q = 2 Å−1 followed by oscillatory features extending up to the higher-Q region. The difference distribution function, Δg(r), obtained from the Fourier transform of Δi(Q), clearly indicates negative peaks at r = 2 and 2.5 Å and a positive one at r = 3.5 Å. Partial structure factors, aHH(Q), aXH(Q), and aXX(Q) (X: O, N, C, HM, and HM′, where HM and HM′ denote methyl and methine hydrogen atoms within the alanine molecule, respectively) for 2.5 mol% Dl-alanine solutions are successfully determined from combined analyses of intermolecular interference terms observed for solutions with 96.1, 66.0, and 35.9% exchangeable deuterium content. The nearest neighbor O···Hex and Hex···Hex (Hex: exchangeable hydrogen atom) distances are determined from the least squares fit of the observed partial structure factors, 1.90(1) and 2.48(1) Å, respectively. These values correspond to the positions of negative peaks observed in the present Δg(r) function. The least squares fitting analysis of the observed Δi(Q) revealed that the difference in the coordination number of the nearest neighbor O···Hex and Hex···Hex interactions between the Dl- and l-alanine solutions are −0.031(5) and −0.072(5), respectively. It is concluded that the intermolecular hydrogen bonds among solvent water molecules in the Dl-alanine solution are ca. 2% weaker than those in the l-alanine solution.
Metal Valence Structures and Magnetic Interactions in Halogen-Bridged 1-D Ni–Pd Mixed-Metal Complexes Studied by 13C and 1H Solid State NMR
Authors: Kimura Noriyoshi , Josako Aki , Kano Masataka , Kisoda Kenji , Manabe Toshio , Yamashita Masahiro , Ikeda Ryuichi
Published: October 2004

13C NMR spectra at room temperature and the temperature dependences of 1H T1 in the solid state were measured in [Ni1−xPdxX(chxn)2]X2 (X: Cl, Br; chxn: 1R,2R-cyclohexanediamine; 0.0 ≤ x ≤ 1.0), where antiferromagnetically coupled paramagnetic –X–Ni3+–X–Ni3+–X– chains were formed at x = 0.00, while the mixed-valence –X–Pd2+–X–Pd4+–X– state was made at x = 1.00. 13C signals at α-carbons in chxn coordinating to Pd atoms showed a doublet assignable to Pd2+ and Pd4+ in x = 1.00, while, with a slight decrease of x from 1.00, a clear broadening and a shift to low-field of signals, indicating conversion into the averaged Pd3+ state, were observed. This can be explained by the fluctuation of the Pd valency caused by neighboring paramagnetic Ni3+ sites introduced in small amounts in the 1-D chain. The x dependences of the chemical shifts of β- and γ-carbons are also attributable to the effect from a partial mixing of the paramagnetic Pd3+ sites. The values of 1H T1 and its temperature dependence observed in the ranges of 100–300 K and x ≤ 0.13 for [Ni1−xPdxBr(chxn)2]Br2 could be explained by a model of strong exchange interactions between Ni3+ and Pd3+ as well as Ni3+ sites. Gradual changes in the T1 value and slope with increasing x from 0.00 to 0.93 are attributable to the variation of the exchange interaction value, which depends upon the number of Ni–Ni pairs.
Analysis of Vibrational–Rotational Spectra with Optimal Fitting Parameters for Born–Oppenheimer Corrections to Dunham’s Yij: An Application to Spectral Data of HCl
Authors: Uehara Hiromichi , Horiai Koui , Akiyama Kazufumi
Published: October 2004

Analytic expressions for Born–Oppenheimer corrections to Dunham’s Yij with optimal fitting parameters, i.e., determinable clusters of expansion coefficients, are applied in analysis of data of reported vibrational–rotational and rotational transitions of HCl. In this method of analysis the choices of a set of fitting parameters and also a corresponding set of Yij that connects the fitting parameters with the term values are unique. A layered structure for empirical parameters Δij is revealed. All spectral lines of four isotopomers of HCl are simultaneously fitted to a single set of molecular constants well within the experimental errors. The approach thus provides a better fit of smaller standard deviations with fewer number of adjustable parameters than from other methods of analysis. The determined values for the coefficients of adiabatic effects s1H and s1Cl reveal the wobble-stretch term to be unimportant in the adiabatic correction for HCl.
Ion-Exchange Reaction of Cs+ Selective Layered γ-Titanium and γ-Zirconium Phosphates
Authors: Suzuki Noriko , Igarashi Megumi , Suzuki Hiromi , Itoh Mami , Komatsu Yu , Kanzaki Yasushi
Published: October 2004

The H+/MA+ ion-exchange reaction of layered γ-titanium and γ-zirconium phosphates, MT(HPO4)2·nH2O, was examined, where MA is an alkali metal and MT is Ti or Zr. They showed remarkably high ion-exchange selectivity for Cs+ and Rb+ in acidic media. The selectivity for Na+ was rather low, and Li+ exchange hardly occurred. The H+ ion exchange of both γ-phosphates with Cs+ and Rb+ apparently occurred in two steps. These ion-exchange reactions occurred first at a pH value of around 2.0 to form a monobasic structure, MTMAH(PO4)2·nH2O, accompanied by dehydration of the water of crystallization. The second step occurred at a pH around 8.0 to form a dibasic structure, MT(MAPO4)2·nH2O, the interlayer space of both γ-phosphates swelled again. The lattice of crystals gradually collapsed corresponding to further progress of the ion-exchange reaction with Cs+ and Rb+, and the amorphous phase finally appeared. According to 133Cs NMR study, Cs+ was found to be rather restricted. The results were compared with those of layered synthetic mica. The high Cs+ and Rb+ selectivity was ascribed to the dehydration property and strong interactions of these ions with the host lamella layers. The high selectivity of two γ-phosphates for Cs+ in acidic media suggested a potentiality as promising materials for the recovery from radioactive waste. The interfering effect of coexisting Fe2+ was scarcely observed upon Cs+ exchange, and was even positive due to the prevention of lattice coagulation.
Gadolinium Anomaly in the Distributions of Rare Earth Elements Observed for Coastal Seawater and River Waters around Nagoya City
Authors: Zhu Yanbei , Hoshino Masuki , Yamada Hiroshi , Itoh Akihide , Haraguchi Hiroki
Published: October 2004

Coastal seawater and river water samples were collected near Nagoya port, located in the coastal area of the Ise Bay, and in six rivers around Nagoya City. The rare earth elements (REEs) in these samples were determined by inductively coupled plasma mass spectrometry (ICP-MS) with chelating resin preconcentration. The concentrations of all REEs except for Pm in coastal seawater and river water samples could be determined at the concentration level from sub-ng L−1 to 10 ng L−1. In order to examine the relative concentration variations, the REE patterns were estimated by normalizing the concentrations of REEs in the water samples to those in Post Archean Average Australian Shale (PAAS). Significantly positive Gd anomalies in the REE patterns were observed for river waters down from the urban areas as well as for coastal seawater. Such Gd anomalies were especially remarkable for river water collected near sewage treatment facilities in the Tenpaku river. It was, thus, concluded that the Gd anomalies in the REE patterns were artificially caused by anthropogenic sources mainly due to recent use of a gadolinium compound as a contrast reagent for magnetic resonance imaging (MRI) in medical diagnosis.
Electro- and Spectroscopic Studies of 2(3H)-Thiazolone Azine as Precursors to Air-Stable Radical Cations
Authors: Cavalié-Kosheiry Hicham , Hammami Amer , Garcia Béatrice , Abu-Lebdeh Yaser , Alarco Pierre-Jean , Abouimrane Ali , Armand Michel
Published: October 2004

The electrochemical and spectroscopic properties of a new family of stable radical cations based on 2(3H)-thiazolone azine were investigated. All of the studied compounds display two redox processes, leading to a radical cation, and then to a dication, the radical mono-cation being intensely blue-colored. These properties suggest that this new family of dyes provides excellent candidates for electrochromic devices, such as electrochromic windows, or as redox indicators or mediators.
Synthesis and Electrochemical Properties of Oxovanadium Complexes with a Pentadentate Schiff Base Ligand
Authors: Tsuchimoto Masanobu , Ishii Toshio , Imaoka Takane , Yamamoto Kimihisa
Published: October 2004

Oxovanadium(IV) and (V) complexes with a pentadentate Schiff base ligand, [VIVO(HL)]·H2O {H3L: N,N′-bis(3-ethoxysalicylidene)-2-hydroxy-1,3-propanediamine} and [VVO(L)]·CH3CN, were prepared by the reaction of the Schiff base ligand with [VIVO(acac)2] (H2acac: acetylacetone) in CH3CN under an argon atmosphere and in air, respectively. IR data of the complexes indicate that [VIVO(HL)] and [VVO(L)] have polymeric (···V=O···V=O···) and monomeric structures, respectively, in the solid state. An X-ray crystal structure analysis of [VVO(L)]·CH3CN was carried out. The complex has a distorted octahedral structure with one of the imine nitrogen atoms trans to the oxo atom. The cyclic voltammogram of [VVO(L)] in CH2Cl2 shows a quasi-reversible V(V)/V(IV) redox couple with E1/2 = −0.74 V vs Ag/Ag+. On the other hand, the cyclic voltammogram of [VIVO(HL)] in CH2Cl2 shows two irreversible oxidation waves at +0.23 and +0.33 V with a scan rate 100 mV/s. The cyclic voltammogram of [VIVO(HL)] in DMSO shows a quasi-reversible V(V)/V(IV) redox couple with E1/2 = −0.05 V. Electrochemcal data indicate that [VIVO(HL)] form dimeric species in a weakly Lewis basic solvent by coodination of the alcohol group to the vanadium atom of the adjacent molecule.
Effect of Catalytic and Electrochemical Acetone Hydrogenation on the I–V Characteristics of an Acetone/Hydrogen-Based Thermally Regenerative Fuel Cell
Authors: Ando Yuji , Aoyama Yukihiro , Sasaki Tomokazu , Saito Yasukazu , Hatori Hiroaki , Tanaka Tadayoshi
Published: October 2004

A thermally regenerative fuel cell, converting low-quality heat at around 100 °C directly into electric power, is composed of a redox reaction pair of acetone hydrogenation and 2-propanol dehydrogenation. The magnitude of its open-circuit voltage (VOC) was determined by the Gibbs energy change of acetone hydrogenation, without exhibiting activation polarization. Its short-circuit current (ISC) was insensitive to the extents of catalyst loading at the anode, in contrast to the cathode, because acetone hydrogenation proceeded more slowly than hydrogen dissociation. The ISC characteristics were improved with increasing sulfuric acid concentrations at the cathode, which would have resulted from the rate enhancement of acetone reduction due to more abundant protons usable at the catalyst sites. Both VOC and ISC of the fuel cell were increased along with increasing the acetone/2-propanol ratio in the catholyte, suggesting favorable effects of the thermodynamical acetone activity and the coverage increment of acetone at the same cathode catalyst sites.
Comparison of the Dissolution Behavior in Ethanol with the Dissolution Behavior in Water for Tris(amino acidato)cobalt(III)
Authors: Yoshimura Yasuki
Published: October 2004

The free energy (ΔdisG°), enthalpy (ΔdisH°), and entropy of dissolution (ΔdisS°) for tris(amino acidato)cobalt(III) were estimated from the temperature dependence of the solubilities in water, aqueous Bu4NBr solutions, and ethanol. For mer-tris(β-alaninato)cobalt(III) (mer-[Co(β-ala)3]), mer-(+)-tris(l-threoninato)cobalt(III) (mer-(+)-[Co(l-thr)3]), and fac-(−)-tris(l-prolinato)cobalt(III) (fac-(−)-[Co(l-pro)3]), ΔtrH° and ΔtrS° of the transfer process from water to Bu4NBr solutions indicate that these chelates have rather a hydrophilic character. In addition to these chelates, for mer-(−)-tris(l-alaninato)cobalt(III) (mer-(−)-[Co(l-ala)3]), mer-(−)- and fac-(−)-tris(l-valinato)cobalt(III) (mer-(−)- and fac-(−)-[Co(l-val)3]), mer-(+)-tris(l-leucinato)cobalt(III) (mer-(+)-[Co(l-leu)3]), and so on, the dissolution behavior in ethanol was compared with that in water by using ΔdisG°, ΔdisH°, and ΔdisS° in both solvents. The dissolution behavior of these chelates may be divided into two groups, that is, a group composed of hydrophilic chelates and another group composed of hydrophobic chelates. In the former, the solubilities in water are larger than those in ethanol owing to both smaller ΔdisH° and larger ΔdisS° in water. In the latter, the solubilities in ethanol are larger than those in water owing to larger ΔdisS° in ethanol.
Crystal and Molecular Structures of Bis[8-(diphenylphosphino)quinoline]palladium(II) Complexes: Pd(Ph2Pqn)2XY (XY = Cl2, Br2 or ClBF4)
Authors: Suzuki Takayoshi
Published: October 2004

The complex chloride, Pd(Ph2Pqn)2Cl2 (Ph2Pqn = 8-(diphenylphosphino)quinoline), crystallized either in yellow plates (1a: from CH2Cl2/Et2O) or in orange needles (1b: from MeOH/Et2O). The corresponding bromide, Pd(Ph2Pqn)2Br2, initially deposited as yellow block crystals (2a) from MeOH/Et2O, turned to orange prisms (2b) on standing in the mother liquor. The X-ray crystallographic analyses of 1a and 2a revealed that two Cl− and Br− anions, respectively, were located above and below the square-planar PdII coordination plane of cis(P)-[Pd(Ph2Pqn)2]2+. Although the distances of Pd···Cl (3.262(3) and 3.386(3) Å) and Pd···Br (3.432(2) and 3.505(2) Å) in 1a and 2a, respectively, were too long for a bonding interaction between PdII and X−, weak PdII···X− charge-transfer interactions seem to be responsible for the yellow colors of these crystals. In contrast, in 2b, the PdII formed an elongated square-pyramidal five-coordinate complex, [Pd(Ph2Pqn)2Br]+, with a somewhat long Pd–Br bond (3.0136(8) Å) at the apical position. The crystal structure of Pd(Ph2Pqn)2ClBF4 (4) revealed that the PdII center in 4 took an extremely distorted square-planar coordination geometry with the Pd–Cl bond of 2.375(2) Å, while one of the Ph2Pqn ligands coordinated through only P; cis(P)-[PdCl(Ph2Pqn-κP,N)(Ph2Pqn-κP)]BF4.
Preparation and Oxidation of Pt(II) Complexes Containing Both C-Deprotonated 2-Phenylpyridine (ppy−) and a Sulfur-Rich Dithiolate Ligand and X-ray Crystal Structure of [NBun4][Pt(ppy)(C8H4S8)]
Authors: Suga Yusuke , Nakano Motohiro , Tamura Hatsue , Matsubayashi Gen-etsu
Published: October 2004

[NEt4][Pt(ppy)(C3S5)] (ppy− = C-deprotonated 2-phenylpyridine(−); C3S52− = 4,5-disulfanyl-1,3-dithiole-2-thionate(2−)), [NEt4]-, [NBun4][Pt(ppy)(C8H4S8)] (C8H4S82− = 2-{(4,5-ethylenedithio)-1,3-dithiole-2-ylidene}-1,3-dithiole-4,5-dithiolate(2−)) and [NEt4][Pt(ppy)(C10–C6S8)] (C10–C6S82− = 2-{bis(decylthio)-1,3-dithiole-2-ylidene}-1,3-dithiole-4,5-dithiolate(2−)) were prepared. They showed an intense electronic absorption band due to an intramolecular mixed metal/dithiolate ligand-to-ppy ligand charge transfer transition, which is somewhat sensitive to the solvent. The complexes exhibited first oxidation potentials of −0.27 to +0.02 V (vs Ag/Ag+) due to the dithiolate ligand-centered oxidation. They were oxidized by TCNQ and iodine to afford [Pt(ppy)(L)] and [Pt(ppy)(L)](I1.0–4.2) (L = C3S52−, C8H4S82−, and C10–C6S82−). Electrical conductivities of the oxidized C8H4S8- and C10–C6S8-species measured for compacted pellets at room temperature were 6.2 × 10−6–7.8 × 10−3 S cm−1, while those of the oxidized C3S5-species were very low [(3.8–6.2) × 10−9 S cm−1]. The X-ray crystal structure of [NBun4][Pt(ppy)(C8H4S8)] was clarified.
Selective Conversion of Epoxides to vic-Halo Alcohols and Symmetrical or Unsymmetrical Dihalides by Triphenylphosphine/2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) in the Presence of Quaternary Ammonium Halides
Authors: Iranpoor Nasser , Firouzabadi Habib , Aghapour Ghasem , Nahid Azarmidokht
Published: October 2004

A new method is described for the efficient and selective conversion of epoxides to vic-halo alcohols or symmetrical and unsymmetrical dihalides using PPh3/DDQ/R4NX (X = Cl, Br, I) as a mixed-reagent system.
Friedel–Crafts Benzoylation of Alkylbenzenes with Benzoic Anhydride Catalyzed by Solid Superacids
Authors: Nakamura Hideo , Arata Kazushi
Published: October 2004

The liquid–solid phase benzoylation of mono-alkylbenzenes with methyl, ethyl, propyl, and butyl groups and xylenes was carried out with benzoic anhydride at 100–110 °C over solid superacids: SO4/ZrO2, WO3/ZrO2, and SO4/HfO2. The reactivity ratio obtained by the competitive method of reaction over WO3/ZrO2 was 1 to 4.6 for toluene to p-xylene and 1.1:10:1 among o-, m-, and p-xylenes, respectively. Although the SO4/ZrO2 catalyst gave high yields of 92 and 97% for toluene and ethylbenzene in a 3:7 distribution of o- and p-isomers, respectively, low yields were observed with propyl and butylbenzenes over the catalyst: that is, 5 and 2% for propylbenzene and isopropylbenzene, 14% for isobutylbenzene, and trace yields for butylbenzene, s-butylbenzene, and t-butylbenzene, respectively. The usual Friedel–Crafts benzoylation using AlCl3 was examined in the present alkylbenzenes in order to confirm the low reactivity of both propyl and butylbenzenes. The results were similar to those with the SO4/ZrO2 catalyst; that is, the yields at 0 °C for 1 h were 37, 21, 6, 1, 0, 3, and 2% for toluene, ethylbenzene, propylbenzene, isopropylbenzene, butylbenzene, s-butylbenzene, and t-butylbenzene, respectively, showing an unexpected result where there was no distinction between homogeneous and heterogeneous conditions.
Novel Synthesis of α-Amino Carboxamides and Their Related Compounds via α-Oxo Sulfones Starting from 2,2-Disulfonyloxiranes
Authors: Matsumoto Shoji , Ishii Michiko , Kimura Kazuto , Ogura Katsuyuki
Published: October 2004

2-(Methylsulfonyl)-2-(p-tolylsulfonyl)oxiranes 1 are easily prepared by the condensation of methylthiomethyl p-tolyl sulfone (MT-sulfone) with aldehydes and the subsequent oxidation with MCPBA. They smoothly reacted with 2 molar amounts of primary or secondary amines to give α-amino carboxamides in high yield. This reaction can be suitably extended to the reaction with one molar amount of 1,n-diaminoalkanes (n = 2, 3, or 4) to form the corresponding 2,5-diazacyclohexanone, 2,6-diazacycloheptanone, or 2,7-diazacyclooctanone, respectively. The reaction of 1 with some related compounds having two nucleophilic sites are also described.
Nitrous Oxide Oxidation Catalyzed by Ruthenium Porphyrin Complex
Authors: Tanaka Hirotaka , Hashimoto Kentaro , Suzuki Kyosuke , Kitaichi Yasunori , Sato Mitsuo , Ikeno Taketo , Yamada Tohru
Published: October 2004

Dinitrogen oxide was employed as a clean oxidant for various oxidations in the presence of a catalytic amount of dioxoruthenium tetramesitylporphyrin complex (Ru(tmp)(O)2). A variety of olefins, secondary alcohols, and benzyl alcohols were smoothly oxidized to the corresponding epoxides, ketones, and aldehydes in high yields. In the oxidation of 9,10-dihydroanthracene derivatives, the competitive reactions affording anthraquinones and anthracenes could be regulated by the reaction conditions. At a high temperature (200 °C), anthraquinones were selectively produced, while the anthracenes were selectively produced by the addition of sulfuric acid.