bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic bidirectional reflectance distribution functions: Measurement and representation
Authors: Bailey Albert W. , Early Edward A. , Keppler Kenneth S. , Villavicencio Victor I. , Kennedy Paul , Thomas Robert J. , Zohner Justin J. , Megaloudis George
Published: February 2008

With high-energy lasers, not only the direct laser beam can pose significant eye and skin hazards, but also light reflecting off material illuminated by the beam. Proper hazard analysis for a material irradiated by a laser relies upon the reflecting properties of the material surface, as these properties determine the magnitude and direction of the reflected laser energy commonly characterized by the bidirectional reflectance distribution function (BRDF). However, a high-energy laser heating and possibly melting a material can change the reflecting properties of that material, so these changes must be included in the hazard analysis. Traditional methods for measuring the BRDFs of materials are not practical for measurement of materials with rapidly-changing surface properties. However, BRDF measurement by imagery of a witness screen allows for practical measurements of the dynamically-changing BRDFs of materials under high-energy laser irradiation. Using this technique, the dynamic BRDFs of stainless steel and copper were measured under high irradiance. The BRDF of the materials was observed to change in magnitude, width, and the specular direction. In some instances, this would result in an increase in exposure to the laser radiation for some observers over that which would be predicted using static BRDF measurements where the reflective characteristics of the material are assumed to be constant. For effective use in safety calculations, the dynamic BRDFs need to be represented in a form suitable for use in safety analysis codes. Construction of a dynamic BRDF representation is complicated by the fact that data cannot be practically obtained over the entire range of incident and reflected angles or for all points in time. Therefore, a technique is required for interpolating through regions of missing data. A BRDF representation form has been developed based on expansions in spherical harmonics in a transformed coordinate space. The efficacy of this representation is examined using experimental data on stainless steel and copper samples exposed to high-energy laser irradiation. The representation technique is found to be capable of robust predictions at all incident and reflected angles and at interpolated material states. Simplified “envelope” models based on these representations are suitable for inclusion in laser safety codes for predicting reflection hazards from high-energy lasers.
Practical and theoretical investigations into inert gas cutting of 304 stainless steel using a high brightness fiber laser
Authors: Sparkes Martin , Gross Markus , Celotto Steven , Zhang Tao , O’Neill William
Published: February 2008

A 2.2 kW fiber laser was used in a series of inert cutting trials on stainless steels of section thicknesses in the range of 6–10 mm. Variations in the cutting performance with changing gas pressure, focal position, and nozzle diameter were investigated. Results showed the difficulties associated in cutting with high brightness lasers, specifically in obtaining full melt eject through narrow kerfs; two distinct melt eject failure mechanisms were observed: (I) Failure of melt removal in the upper region resulted in melt ejecting out of the top surface and (II) poor base ejection giving recast and dross problems on the base of the cut. Detailed scanning electron microscope images of these phenomena are presented. A computational fluid dynamic model is used to show distinct differences in the theoretical gas performance at the center of the cut, displayed by most models, and at the edges where the melt eject is taking place. Melt eject is also shown both experimentally and theoretically to be improved for these experiments by the use of smaller nozzles for our experimental range. With a change in focal position strong correlations between the theoretical laser path, and the cut edge with variation in focal position were observed. The performance of the melt eject is shown with respect to speed, pressure, and kerf width. Improved quality of the cut edges was achieved with higher speeds, higher pressures, smaller nozzles, and wider kerfs. Even though the processing parameters were not optimized to utilize the benefits of high brightness, cutting speeds were 1.5 times higher than those of the CO2 with similar powers and processing parameters.
Visualizing transcription in real-time
Authors: Brody Yehuda , Shav-Tal Yaron
Published: February 2008

The transcriptional process is at the center of the gene expression pathway. In eukaryotes, the transcription of protein-coding genes into messenger RNAs is performed by RNA polymerase II. This enzyme is directed to bind at upstream gene sequences by the aid of transcription factors that assemble transcription-competent complexes. A series of biochemical and structural modifications render the polymerase transcriptionally active so that it can proceed from an initiation state into a functional elongating phase. Recent experimental efforts have attempted to visualize these processes as they take place on genes in living cells and to quantify the kinetics of in vivo transcription.
Comparison of pathogenic properties of the murid gammaherpesvirus (MuHV 4) strains: a role for immunomodulatory proteins encoded by the left (5′-)end of the genome
Authors: Mistríková Jela , Rajčáni Július
Published: February 2008

The murid herpesvirus 4 (MuHV 4) species encompasses 7 isolates, out of which at least two (MHV-68, MHV-72) became in vitro propagated laboratory strains. Following intranasal inoculation, MuHV 4 induces an acute infectious mononucleosis-like syndrome with elevated levels of peripheral blood leukocytes, shifts in the relative proportion of lymphocytes along with the appearance of atypical mononuclear cells. At least two isolates exhibited spontaneous deletions at the left hand (5′-end) of their genome, resulting in the absence of M1, M2, M3 genes (strain MHV-72) and also of the M4 gene (strain MHV-76). Based on DNA sequence amplifications only, another two isolates (MHV-Šum and MHV-60) were shown to possess similar deletions of varying length. During latency (until 24 months post-infection), the mice infected with any MuHV 4 isolate (except MHV-76) developed lymphoproliferative disorders. The lack of tumor formation in MHV-76 infected mice was associated with persistent virus production at late post-infection intervals. In addition to careful analysis of spontaneously occurring 5′-end genome defects, our knowledge of the function of 5′-end genes relies on the behaviour of mutants with corresponding deletions and/or insertions. While M2 and M3 genes encode immune evasion proteins, M4 codes for a soluble glycopeptide acting as immunomodulator and/or immunostimulator.
Prenatal testosterone improves the spatial learning and memory by protein synthesis in different lobes of the brain in the male and female rat
Authors: Gurzu Cristian , Artenie Vlad , Hritcu Lucian , Ciobica Alin
Published: February 2008

The high density of the steroid hormone receptors in the structures of temporal lobe involved in learning and memory, such as the hippocampus, perirhinal cortex, entorhinal cortex and amigdaloid complex, shows that there must be a direct relationship between gonadal hormones and organizational effects of steroid hormones in those structures during development of the nervous system. The present study was undertaken in order to investigate the effect of testosterone administration during the third week of gestation on the spatial memory formation of the offspring rats and the level of soluble proteins in the temporal lobe and frontal lobe of brain, as evidence of important organizational effects of androgens during prenatal development in brain sexual dimorphism. Animals have received testosterone undecanoate on days 14, 15, 16 and 19, 20, 21 of gestation. Learning and memory tests were started 100 days after the testosterone treatment. At the end of the experiments, the temporal and frontal lobes of brain were removed for assessing the level of soluble proteins. Testosterone treatment significantly improved spontaneous alternations percentage of male offspring in Y-maze task comparative with female offspring and reference memory in radial 8 arm-maze task (decreasing in number of reference memory errors in both male and female offspring groups), suggesting effects of both short and long-term memory. Also, testosterone significantly increased the brain soluble protein level of treated female rats in 14–16 prenatal days compared with the control group as well as the brain soluble protein level of treated male rats. These results suggest that steroid hormones play an important role in the spatial learning and memory formation by means of protein synthesis in different lobes of the brain.
Rhinolithiasis: Clinical, Radiological, and Mineralogical Features
Authors: Yildirim Nadir , Arslanoglu Atilla , Sahan Murat , Yildirim Altan
Published: February 2008

Background

Rhinolithiasis is a rare and under-diagnosed clinical entity whose etiology and pathogenesis is poorly understood.

Objective

The objective of the study is to review the clinical and radiologic features of rhinolithiasis and mineralogical–chemical composition of the rhinoliths with the aim of shedding light on its etiology and pathogenesis.

Methods

Our subjects consisted of 8 rhinolithiasis cases. Clinical presentations, signs, and symptoms of the patients with radiologic findings are presented, and X-ray diffraction analyses of the stones were carried out to assess their mineralogical composition.

Results

Nasal obstruction appeared to be the chief symptom, followed by nasal discharge and facial pain. Neither exogenous nor endogenous nidi were identified in any of the cases. Mineralogical analyses of the rhinoliths revealed Whitlockite [(Ca, Mg)3 (PO4)2] in one and Dahllite [Ca5 (PO4, CO3)3OH] in 7 cases.

Conclusion

We hypothesized that some substances or organic objects form the nidi of the rhinoliths and are disintegrated over the course of mineral precipitation. This hypothesis was supported by radiologic and microscopic findings.
Inhalation Challenge Test in the Diagnosis of Occupational Rhinitis
Authors: Airaksinen Liisa K. , Tuomi Timo O. , Tuppurainen Matti O. , Lauerma Antti I. , Toskala Elina M.
Published: February 2008

Background

Evaluations of rhinitis reactions in inhalation challenges (ICs) are sparse compared with research on nasal challenges. This study evaluates the outcome of IC tests in assessing occupational rhinitis (OR). It presents the largest rhinologic IC data in the literature, analyzing the exposure method of various agents causing OR and their relation to asthma.

Methods

Challenge tests performed on 829 individuals with suspected cases of OR were reviewed. Results from both exposures with occupational agents (n = 1229) and placebo (n = 838) were evaluated.

Results

A total of 10% of the occupational ICs (n = 123) were positive, suggesting OR, and 13% (n = 161) showed asthmatic reaction in the same challenge. In control challenges 2% showed rhinitis and 6% showed asthma symptoms. The most common agents tested were molds (160 tests), flours, and animal fodders (115 tests) and formaldehyde (122 tests). Obeche wood dust and latex produced positive nasal reactions the most frequently, followed by acid anhydrides.

Conclusion

Although IC is a resource-intensive methodology, the evaluation of nasal symptoms and signs together with bronchial reactions saves time and expense compared with the organization of multiple individual challenges. We encourage the simultaneous evaluation of both nasal and bronchial reactions in IC tests.
The Silent Sinus Syndrome is a form of Chronic Maxillary Atelectasis: A Systematic Review of all Reported Cases
Authors: Brandt Michael G. , Wright Erin D.
Published: February 2008

Background

The terms chronic maxillary atelectasis (CMA) and silent sinus syndrome (SSS) have been used to describe spontaneous enophthalmos in association with a contracted ipsilateral maxillary sinus. Despite the use of differing taxonomy, it appears that these two terms describe the same clinical entity. Nevertheless, many reports still discuss CMA and SSS in isolation or as distinct conditions.

Methods

A systematic review of all reported cases of CMA and SSS was performed (1964-2006). Case reports were excluded if they involved facial trauma, diagnosis of mucocele, or previous surgery. Eligible cases were reviewed and entered into a database. Data were evaluated based on literature of publication, reported diagnosis, demographics, ophthalmologic examination, results of imaging, and operative findings. Only complete data sets were included in an additional analysis whereby the diagnostic criteria for CMA and SSS were applied and the data sets were compared.

Results

Of the 105 cases reviewed, 55 contained complete data sets. Twenty-seven of these cases met the diagnostic criteria for SSS, and 48 could be diagnosed as CMA, with 23 meeting the criteria for both conditions. Comparing the cases across diagnoses, the only difference observed was that of the presence of sinus-related symptoms, which by definition distinguishes CMA III from SSS.

Conclusion

The entity termed SSS fits within the staging classification of CMA. We propose abandoning the term SSS and recommend universal adoption of the CMA staging system, which uses nomenclature that more accurately portrays the pathophysiology and natural history of this condition.
Orbital Exenteration: A Dilemma in Mucormycosis Presented with Orbital Apex Syndrome
Authors: Songu Murat , Unlu H. Halis , Gunhan Kivanc , Ilker S. Sami , Nese Nalan
Published: February 2008

Background

Mucormycosis is an uncommon, rapidly progressive, commonly fatal, opportunistic, fungal paranasal sinus infection. The most critical decision in the management of rhino-orbital mucormycosis is whether the orbit should be exenterated. The literature fails to provide a broad base of information of how physicians determine the need for exenteration in daily practice. The decision for exenteration often depends on the judgment of the treating otolaryngologist. The authors report their experience and outline that orbital exenteration may not be mandatory in all cases of rhino-orbital mucormycosis.

Methods

The medical records from Celal Bayar University Medical Faculty Department of Otorhinolaryngology/Head and Neck Surgery were retrospectively searched from 1995 to 2007 for three cases with rhino-orbital mucormycosis, treated without orbital exenteration.

Results

All patients with rhino-orbital mucormycosis who were treated without exenteration survived.

Conclusion

The favorable outcome was attributable to rapid correction of the underlying medical condition; wide local excision and debridement of all involved and devitalized sinonasal and periorbital tissue, while establishing adequate sinus and orbital drainage; daily endoscopic assessment with multiple sinus debridement when necessary; daily irrigation of the involved areas; and high-dose i.v. amphotericin B.
Botulinum Toxin a Therapy for Medial Rectus Injury during Endoscopic Sinus Surgery
Authors: Hong Jenny E. , Goldberg Andrew N. , Cockerham Kimberly P.
Published: February 2008

Background

Although the use of endoscopes and image guidance provide some safeguards, motility complications from orbital injury during endoscopic sinus surgery still pose a significant concern and can provide a therapeutic challenge.

Methods

We present the case of a 40-year-old woman with strabismus secondary to an iatrogenic injury to the medial rectus muscle during endoscopic sinus surgery.

Results

Permanent resolution of diplopia was achieved with botulinum toxin A injection into the lateral rectus muscle without the need for surgical intervention.

Conclusion

Botulinum toxin A should be considered as a first-line early therapeutic option for cases of iatrogenically induced strabismus after endoscopic sinus surgery when complete transection or entrapment is not present.
Use of an Electronic Nose for Detection of Biofilms
Authors: Thaler Erica R. , Huang Dan , Giebeig Lisa , Palmer James , Lee Dan , Hanson C. William , Cohen Noam
Published: February 2008

Background

Prior work has indicated that electronic nose (enose) technology can distinguish among bacteria samples and identify patients with ventilator-associated pneumonia and rhinosinusitis. This study was performed to test the hypothesis that an enose can distinguish between biofilm-producing and non-biofilm-producing bacteria of the same species.

Methods

Biofilm-producing and non–biofilm-producing mutant strains of Pseudomonas (PA01 and Sad36) and Staphylococcus (Staph WT and Staph SrtA-B-) were incubated and then sampled by the enose. Data were evaluated by logistic regression to perform binary classification of the bacteria. Training sets and testing sets were developed in two ways: by cross-validation with a leave-1-day-out method, and then by testing the last 4 days versus the first 18 days.

Results

By the leave-1-day-out method, logistic regression analysis of 198 samples of each bacterium determined that the training accuracy of the enose for both Pseudomonas species was 100% and the testing accuracy was 91.4% for PA01 and 88.4% for Sad36. The training accuracy of the enose for Staphylococcus species was 87.1% for Staph SrtA-B- and 88.2% for Staph WT and the testing accuracy was, respectively, 75.3 and 76.8%. By separating the first 18 days from the last 4 days, logistic regression analysis determined that the training accuracy of the enose for both Pseudomonas species was 100% and the testing accuracy was 100% for PA01 and 80.6% for Sad36. The training accuracy of the enose for Staphylococcus species was 87.7% for Staph SrtA-B- and 86.4% for Staph WT and the testing accuracy was respectively, 72.2 and 91.7%.

Conclusion

The enose was able to identify correctly biofilm- versus non-biofilm-producing Pseudomonas and Staphylococcus species with accuracy ranging from 72.2 to 100%, depending on the particular organism and the data analysis methodology. These results suggest that biofilms may be an in vivo marker, which the enose can use to identify patients with particularly virulent and medically recalcitrant forms of chronic rhinosinusitis.
Evaluation of Nasal Capacity before and after Rapid Maxillary Expansion
Authors: Cappellette Mario , Cruz Oswaldo L.M. , Carlini Daniela , Weckx Luc L. , Pignatari Shirley S.N.
Published: February 2008

Background

This study analyzed the effects of orthodontic maxillary expansion on the nasal cavity dimensions measured by acoustic rhinometry.

Methods

A prospective study was performed. Fifty patients (27 male and 23 female patients) who had maxillary hypoplasia in relation to the mandible were studied. Patients presented either deciduous or mixed dentition, with age ranging from 4 to 14 years old. Twenty patients (11 male and 9 female patients) between the ages of 4 and 11 years, who also had deciduous or mixed dentition but without maxillary hypoplasia, served as a control group. A modified Biederman appliance was used for ∼20 days to achieve the maxillary expansion in the treatment group. Acoustic rhinometry, with measurements of the right and the left nasal cavity, was performed before starting the maxillary expansion (T1) and at its conclusion (T2). This procedure was conducted also at a comparable time interval in the control group.

Results

The treated group showed a significant increase in the majority of the values of transversal areas and nasal volumes when compared with the nontreated group.

Conclusion

In children with maxillary hypoplasia, rapid maxillary expansion can not only move the maxilla and alveolar arches laterally but it can also increase the size of the nasal cavities.
Influence of Different Footwear on Force of Landing During Running
Authors: Cheung Roy TH , Ng Gabriel YF
Published: February 2008

Background and Purpose

Previous studies have demonstrated an increase in foot pronation with mileage in runners. Motion control footwear was designed to check excessive foot motions, but its clinical efficacy, especially in terms of pedographic analysis, has not been well reported. The purposes of this study were to investigate the changes in plantar force in people when running with motion control shoes and to compare pedographic measurements obtained in 2 footwear testing conditions (wearing motion control shoes and wearing neutral shoes) at the beginning and end of a 1.5-km running session.

Subjects

Twenty-five recreational runners who had ≥6 degrees of foot pronation participated in the study.

Methods

An insole sensor was used to register the plantar force of the subjects before and after running 1.5 km in different shoe conditions.

Results

There was no change in the magnitude and distribution pattern of plantar force with the motion control shoes after the 1.5-km run. With the neutral shoes, however, there was an increase in mean peak force under the medial midfoot (364–418 N, 15% increase) and first metatarsal head (524–565 N, 8% increase) toward the end of the running bout.

Discussion and Conclusion

The plantar force on the medial foot structures increased with mileage of running with neutral shoes but not with motion control shoes. This finding has implications for injury prevention with footwear selection for recreational runners who have more than 6 degrees of foot pronation.
Endoscopic harvesting of the radial artery for neurovascular bypass
Authors: Gonzalez L. Fernando , Patterson Dixie L. , Lekovic Gregory P. , Nakaji Peter , Spetzler Robert F.
Published: February 2008

Object

The radial artery is a common conduit used for high-flow bypasses. Until now the radial artery has been harvested using a long incision in the forearm that follows the course of the artery. The authors present an endoscopic technique that has been used during coronary bypass surgery but is not yet widespread in the neurosurgical arena.

Methods

From October 2006 to October 2007, the authors used the radial artery as a graft in 6 patients during the treatment of complex cerebral aneurysms. The artery was harvested via an endoscopic technique.

The radial artery was exposed distally at the wrist. Using the VasoView vessel harvesting system, the endoscope was inserted into the arm. The radial artery was dissected from its surrounding tissues endoscopically. With direct current energy via the HemoPro device, the side branches were coagulated and cut. The artery was transected at the wrist, then retrieved through a counterincision at the proximal forearm.

Results

There were no neurological or bleeding complications in the hand or forearm.

Conclusions

Endoscopic harvesting of the radial artery is feasible, faster, and produces a more aesthetically pleasing result than standard open harvesting. The learning curve associated with the endoscope can be overcome by practice on cadavers and by collaboration with a cardiac surgical team.
Cerebral bypass surgery for skull base lesions: technical notes incorporating lessons learned over two decades
Authors: Bulsara Ketan R. , Patel Toral , Fukushima Takanori
Published: February 2008

Object

Despite advancements in endovascular neurosurgery, there remains an important role for cerebral bypass surgery in the treatment of skull base lesions. The authors describe their replacement cerebral bypass surgery techniques incorporating lessons learned over 2 decades.

Methods

The authors performed a retrospective review of cerebral bypass surgery performed by the senior author for skull base lesions between 1986 and 2006. One hundred patients had adjunct bypass surgery for skull base lesions.

Results

The bypass surgeries performed are conceptually divided into Skull Base Bypass I, II, and III. The majority of lesions requiring bypass surgery were giant cavernous carotid artery aneurysms or skull base meningiomas. There were no deaths in this case series. There was a 7% morbidity rate.

Conclusions

The ability to perform this surgery is an important adjunct in the armamentarium of skull base/cerebrovascular neurosurgeons.
Iatrogenic vasospasm in carotid artery stent angioplasty with distal protection devices
Authors: Schirmer Clemens M. , Hoit Daniel A. , Malek Adel M.
Published: February 2008

Object

Distal protection devices (DPDs) have decreased the risk of embolic stroke among patients with carotid artery (CA) disease undergoing CA stent placement. The FilterWire EX is a first-generation fixed-basket DPD with a filter rigidly attached to a guidewire. Second-generation mobile-basket DPDs (RX Accunet or SpiderFX) allow movement of the filter relative to the guidewire and can thus reduce the potential for vessel irritation, vasospasm, or intimal injury during CA stent placement.

Methods

Stent angioplasty was attempted in 40 CAs (37 patients) using the fixed-basket FilterWire DPD, a second-generation mobile-basket DPD, or no protection in 12, 6, and 22 arteries, respectively. Clinical presentation, angiographic details relating to the incidence of vasospasm or dissection, and clinical outcome data were recorded and analyzed.

Results

Vasospasm was associated with use of the fixed-basket FilterWire device (8 [67%] of 12 cases) compared with the bare unfiltered guidewire group (3 [14%] of 22) and the second-generation mobile-basket DPD group (1 [17%] of 6, p < 0.004). Secondary angioplasty was also associated with intraprocedural vasospasm. In a multivariate analysis, FilterWire use was an independent risk factor for vasospasm (p < 0.0003).

Conclusions

A high incidence of vasospasm was observed following CA stent placement procedures in which the fixed-basket FilterWire EX DPD was used but not in unprotected CA stent placement or procedures in which a second-generation mobile-basket DPD was used. Although this phenomenon was self-limited in all instances, vasospasm should be considered a risk of these devices and may predispose to more serious vascular injury. Coronary artery stent placement should be performed with a second-generation mobile-basket DPD to minimize the risks of embolic complications and iatrogenic vascular injury.
Techniques in carotid artery surgery
Authors: Curtis Jonathan Andrew , Johansen Kaj
Published: February 2008

✓The major objective in carotid endarterectomy is to achieve safe and complete removal of intimal plaque and provide lasting, nonstenotic closure. Controversy exists as to which technical variation best achieves this. In this paper, the authors review the operative nuances and outcomes with conventional and eversion endarterectomy, with a focus on the latter. The views expressed reflect specific neurosurgical and vascular perspectives in the context of a multi-disciplinary stroke unit, where carotid stenosis is managed with all available open and endovascular means. The neurosurgical approach was almost entirely conventional endarterectomy with primary repair, while the vascular surgeons used the eversion method with few exceptions.
Superficial temporal artery to middle cerebral artery bypass: past, present, and future
Authors: Vilela Marcelo D. , Newell David W.
Published: February 2008

Object

The aim of this study was to review the historical developments and current status of superficial temporal artery (STA) to middle cerebral artery (MCA) bypass.

Method

A literature review was performed to review the origins and current uses of the STA bypass procedure in neurosurgery.

Results

The idea of providing additional blood supply to the brain to prevent stroke and maintain neurological function has been present in the mind of neurosurgeons for many decades. In 1967 the first STA–MCA bypass was done by M. G. Yaşargil, and an enormous step was made into the field of microneurosurgery and cerebral revascularization. During the decades that followed, this technique was used as an adjuvant or a definitive surgical treatment for occlusive disease of the extracranial and intracranial cerebral vessels, skull base tumors, aneurysms, carotid–cavernous fistulas, cerebral vasospasm, acute cerebral ischemia, and moyamoya disease. With the results of the first randomized extracranial–intracranial (EC–IC) bypass trial and the development of endovascular techniques such as angioplasty for intracranial atherosclerotic disease and cerebral vasospasm, the indications for STA–MCA bypass became limited. Neurosurgeons continued to perform EC–IC bypasses as an adjuvant to clipping of aneurysms and in the treatment of skull base tumors and moyamoya disease; the procedure is less commonly used for atherosclerotic carotid artery occlusion (CAO) with definite evidence of hemodynamic insufficiency. The evidence that patients with symptomatic CAO and “misery perfusion” have an increased stroke risk has prompted a second trial for evaluating EC–IC bypass for stroke prevention. The Carotid Occlusion Surgery Study is a new trial designed to determine whether STA–MCA bypass can reduce the incidence of stroke in these patients. New trials will also reveal the role of the STA–MCA bypass in the prevention of hemorrhages in moyamoya disease.

Conclusions

The role of STA–MCA bypass in the management of cerebrovascular disease continues to be refined and evaluated using advanced imaging techniques and by performing randomized trials for specific purposes, including symptomatic CAO.
Evolution of cerebral revascularization techniques
Authors: Crowley R. Webster , Medel Ricky , Dumont Aaron S.
Published: February 2008

✓As a leading cause of death and disability in patients across the world, stroke is a problem that plagues both neurosurgeons and neurologists alike. Whether a result of atherosclerosis, moyamoya disease, or a complication in the treatment of a complex intracranial aneurysm, cerebrovascular occlusion can have devastating effects on patients. For nearly half a century neurosurgeons have searched for safer, more effective ways to increase the amount of blood flow to ischemic brain tissue. From the first extracranial–intracranial bypasses to the recent technological advancements seen with endovascular therapy, cerebral revascularization techniques have been constantly evolving. Over the years cerebral ischemia has gone from a condition that was previously considered surgically untreatable, to a condition with several viable options for prevention and treatment. In this paper the authors discuss the historical evolution of treatment for cerebrovascular occlusive disease.
The Extracranial–Intracranial Bypass Trial: implications for future investigations
Authors: Garrett Matthew C. , Komotar Ricardo J. , Merkow Maxwell B. , Starke Robert M. , Otten Marc L. , Connolly E. Sander
Published: February 2008

✓The 1985 International Extracranial–Intracranial (EC-IC) Bypass Trial failed to show a surgical benefit of EC-IC bypass in patients with varying degrees of angiographic stenosis. This study was limited by the technology available at the time it was conducted. In the 20 years since, there has been considerable progress in imaging techniques that now enable the identification of a subset of stroke patients with hemodynamic ischemia. In the present study, the authors review the relevant literature and propose a reevaluation of the benefits of the EC-IC bypass procedure using these new imaging techniques.

The authors reviewed the admission criteria for the EC-IC Bypass Trial in the light of more recently discovered neurovascular physiology and showed that the imaging criteria used in that trial are not physiologically adequate. A MED-LINE (1985–2007) database search for EC-IC case studies was conducted, and additional studies were identified manually by scrutinizing references from identified manuscripts, major neurosurgical journals and texts, and personal files.
Use of radial artery grafts in extracranial–intracranial revascularization procedures
Authors: Kocaeli Hasan , Andaluz Norberto , Choutka Ondrej , Zuccarello Mario
Published: February 2008

✓Cerebral revascularization procedures have been used in the clinical management of actual or threatened cerebral ischemic states and unclippable cerebral aneurysms. An alternative to a low-flow bypass graft (for example, with the superficial temporal artery) is the use of high-flow grafts created using the saphenous vein (SV) or radial artery (RA). These high-flow grafts are particularly useful when otherwise adequate collateral flow is insufficient to enable sacrifice of the parent vessel without the risk of cerebral ischemia. In their clinical series of 13 patients who underwent high-flow bypass with an RA graft, the authors describe 8 women and 5 men whose ages ranged from 44 to 69 years (mean 57.84 ± 9.05 years). Indications for RA graft bypass were unclippable aneurysms in 10 patients and occlusive cerebrovascular disease in 3 patients. The authors review the properties of the 2 most common conduits, the SV and RA grafts. They present the technique of high-flow extracranial–intracranial bypass produced using RA grafts in the management of occlusive atherosclerotic disease and complex intracranial aneurysms that are not otherwise amenable to either clip ligation or coil occlusion.
Excimer laser–assisted nonocclusive anastomosis
Authors: Langer David J. , Van Der Zwan Albert , Vajkoczy Peter , Kivipelto Leena , Van Doormaal Tristan P. , Tulleken Cornelis A. F.
Published: February 2008

Excimer laser–assisted nonocclusive anastomosis (ELANA) has been developed over the past 14 years for assistance in the creation of intracranial bypasses. The ELANA technique allows the creation of intracranial–intracranial and extracranial–intracranial bypasses without the need for temporary occlusion of the recipient artery, avoiding the inherent risk associated with occlusion time. In this review the authors discuss the technique and its indications, while reviewing the clinical results of the procedure. The technique itself is explained using cartoon drawings and intraoperative photographs. Advantages and disadvantages of the technique are also discussed.
Alternative vascular graft for extracranial–intracranial bypass surgery: descending branch of the lateral circumflex femoral artery
Authors: Başkaya Mustafa K. , Kiehn Mark W. , Ahmed Azam S. , Ateş Özkan , Niemann David B.
Published: February 2008

Object

Arterial bypass is an important method of treating intracranial disease requiring sacrifice of the parent vessel. The conduits for extracranial–intracranial (EC–IC) bypass surgery include the superficial temporal artery, occipital artery, superior thyroid artery, radial artery, and saphenous vein (long or short). In an aging population with an increased prevalence of vascular disease, conduits for EC–IC bypass may be in short supply in some patients. Herein, the authors describe a case in which the descending branch of the lateral circumflex femoral artery (DLCFA) was utilized as a high-flow conduit for an EC–IC bypass.

Methods

This 22-year-old woman presented with irregular menstrual periods, secondary amenorrhea, and hypothyroidism. A giant intrasellar and suprasellar mass was found. Angiography confirmed a 3.5 × 2.1–cm fusiform aneurysm involving the cavernous and supraclinoid segments of the right internal carotid artery. A suitable radial artery conduit was not available. The DLCFA was harvested and anastomosed between the M2 segment of the middle cerebral artery and the external carotid artery.

Results

Durable clinical and angiographic results were apparent at the 2-month follow-up.

Conclusions

The DLCFA's diameter and length were used successfully in a high-flow EC–IC bypass surgery. The DLCFA may be a good alternative to radial artery and saphenous vein grafts for an EC–IC bypass requiring high flow.
The occipital artery for posterior circulation bypass: microsurgical anatomy
Authors: Ateş Özkan , Ahmed Azam S. , Niemann David , Başkaya Mustafa K.
Published: February 2008

Object

The microsurgical anatomy of the occipital artery (OA) was studied to describe the diameter, length, and course of this vessel as it pertains to revascularization procedures of the posterior cerebral circulation.

Methods

The authors studied 12 OAs in 6 cadaveric heads that had been injected with colored latex. They evaluated the OA's ability to serve as a conduit for extracranial–intracranial (EC–IC) bypass in the posterior circulation. They measured the length of the OA and its diameter at common sites of anastomosis and compared these values with the diameters of the recipient vessels (V3 and V4 segments of the vertebral artery, caudal loop of the posterior inferior cerebellar artery [PICA], and anterior inferior cerebellar artery [AICA]).

Results

The mean thickness of the suboccipital segment of the OA was found to be 1.9 mm. The mean distance of the OA from the external occipital protuberance was found to be 45 mm. The mean length of the suboccipital segment of the OA was 79.3 mm. The mean thickness of the largest trunk of the V3 segment, the V4 segment, the caudal loop of the PICA, and the AICA were 3.3 mm, 3.1 mm, 1.2 mm, and 1 mm, respectively.

Conclusions

The length, diameter, and flow accomodated by the OA make it an ideal choice as a conduit for posterior circulation bypass. The bypass from the OA to the caudal loop of the PICA demonstrates the least difference in vessel diameter, and is therefore best suited for EC–IC bypass procedures in the posterior circulation.
Effect of Hydrogen on the Mechanical Properties of Stainless Steels
Authors: Borchers C. , Michler T. , Pundt A.
Published: February 2008

Fuel cell vehicles running on hydrogen are seen as the long term solution to enable sustainable mobility. Compressed hydrogen gas storage systems are a promising route for storing hydrogen on board of vehicles, provided that a reliable and cheap material capable of withstanding hydrogen embrittlement is found. In this paper, the physicochemical behaviour of stainless steel in the presence of hydrogen with special focus on a ductility minimum near room temperature is reviewed.
Heterogeneous and Architectured Materials: A Possible Strategy for Design of Structural Materials
Authors: Bouaziz O. , Bréchet Y. , Embury J. D.
Published: February 2008

Facing increasing demands for multifunctional solutions, the classical strategy of the metallurgist to improve properties, using microstructural refinement, reaches its limits: very often the function is not provided by the property only, but by the interplay between the shape, the properties, and possible association of materials. The purpose of the present paper is to outline new strategies for structural materials development offered by new degrees of freedom and by their combination: not only playing with the microstructure or with the macroscopic shape, but allowing a new scale for materials organization, the “architecture”, and controlling a new degree of freedom, the “spatial heterogeneity”. For these ideas to be effective, the question of processing such “heterogeneous architectured materials” in an affordable manner has to be kept in mind. Very often the development of architectured materials will require new processing methods.
Hybrid Solar Cells from a Blend of Poly(3‐hexylthiophene) and Ligand‐Capped TiO2 Nanorods
Authors: Bouclé Johann , Chyla Sabina , Shaffer Milo S. P. , Durrant James R. , Bradley Donal D. C. , Nelson Jenny
Published: February 2008

Hybrid bulk heterojunction solar cells based on nanocrystalline TiO2 (nc‐TiO2) nanorods capped with trioctylphosphine oxide (TOPO) and regioregular poly(3‐hexylthiophene) (P3HT) are processed from solution and characterized in order to relate the device function (optical absorption, charge separation, and transport and photovoltaic properties) to active‐layer properties and device parameters. Annealing the blend films is found to greatly improve the polymer–metal oxide interaction at the nc‐TiO2/P3HT interface, resulting in a six‐fold increase of the charge separation yield and improved photovoltaic device performance under simulated solar illumination. In addition, the influence of the organic ligand at the nc‐TiO2 particle surface is found to be crucial for charge separation. Ligand‐exchange procedures applied on the TOPO‐capped nc‐TiO2 nanorods with an amphiphilic ruthenium‐based dye are found to further improve the charge‐separation yield at the polymer–nanocrystal interface. However, the poor photocurrents generated in the hybrid blend devices, before and after ligand exchange, suggest that transport within or between nanoparticles limits performance. By comparison with other donor–acceptor bulk heterojunction systems, we conclude that charge transport in the nc‐TiO2:P3HT blend films is limited by the presence of an intrinsic trap distribution mainly associated with the nc‐TiO2 particles.
Ultrasensitive Specific Stimulant Assay Based on Molecularly Imprinted Photonic Hydrogels
Authors: Hu Xiaobin , Li Guangtao , Li Mohan , Huang Jing , Li Yan , Gao Yongbin , Zhang Yihe
Published: February 2008

Taking theophylline and (1R,2S)‐(−)‐ephedrine as template molecules, two imprinted photonic‐hydrogel films are prepared by a combination of colloidal‐crystal and molecular‐imprinting techniques. This paper shows a new approach for rapid and handy stimulant detection with high sensitivity and specificity. One film is proposed for analogous molecule assay, another one for chiral recognition. The key point of this approach is that the imprinted photonic polymer (IPP) consists of a three‐dimensional (3D), highly‐ordered and interconnected macroporous array with a thin hydrogel wall, where nanocavities complementary to analytes in shape and binding sites are distributed. This special, bicontinuous, hierarchical structure enables this polymer to report quickly, easily, sensitively and directly a molecular recognition event without any transducers and treatments for analytes (label‐free). The inherent affinity of the nanocavities, deriving from molecular imprinting, makes these sensors highly specific to analytes, even if in a competitive environment. Their sensitive and specific responses to stimulants in buffer are determined by Bragg diffractive shifts due to the lattice change of their 3D ordered macroporous arrays resulting from their preferential rebinding to the target molecules. The measurements show that the prepared hydrogel films exhibit high sensitivity in such a 0.1 fM concentration of analytes and specificity even in a competitive urinous buffer. The reported method provides a rapid and handy approach for stimulant assay and drug analysis in athletic sports.
Manipulating Charge‐Transfer Character with Electron‐Withdrawing Main‐Group Moieties for the Color Tuning of Iridium Electrophosphors
Authors: Zhou Guijiang , Ho Cheuk‐Lam , Wong Wai‐Yeung , Wang Qi , Ma Dongge , Wang Lixiang , Lin Zhenyang , Marder Todd B. , Beeby Andrew
Published: February 2008

A new and synthetically versatile strategy has been developed for the phosphorescence color tuning of cyclometalated iridium phosphors by simple tailoring of the phenyl ring of ppy (Hppy = 2‐phenylpyridine) with various main‐group moieties in [Ir(ppy‐X)2(acac)] (X = B(Mes)2, SiPh3, GePh3, NPh2, POPh2, OPh, SPh, SO2Ph). This can be achieved by shifting the charge‐transfer character from the pyridyl groups in some traditional iridium ppy‐type complexes to the electron‐withdrawing main‐group moieties and these assignments were supported by theoretical calculations. This new color tuning strategy in IrIII‐based triplet emitters using electron‐withdrawing main‐group moieties provides access to IrIII phosphors with improved electron injection/electron transporting features essential for highly efficient, color‐switchable organic light‐emitting diodes (OLEDs). The present work furnished OLED colors spanning from bluish‐green to red (505–609 nm) with high electroluminescence efficiencies which have great potential for application in multicolor displays. The maximum external quantum efficiency of 9.4%, luminance efficiency of 10.3 cd A−1 and power efficiency of 5.0 lm W−1 for the red OLED (X = B(Mes)2), 11.1%, 35.0 cd A−1, and 26.8 lm W−1 for the bluish‐green device (X = OPh), 10.3%, 36.9 cd A−1, and 28.6 lm W−1 for the bright green device (X = NPh2) as well as 10.7%, 35.1 cd A−1, and 23.1 lm W−1 for the yellow‐emitting device (X = SO2Ph) can be obtained.
Spin‐Coated Highly Efficient Phosphorescent Organic Light‐Emitting Diodes Based on Bipolar Triphenylamine‐Benzimidazole Derivatives
Authors: Ge Ziyi , Hayakawa Teruaki , Ando Shinji , Ueda Mitsuru , Akiike Toshiyuki , Miyamoto Hidetoshi , Kajita Toru , Kakimoto Masa‐aki
Published: February 2008

A new series of star‐shaped bipolar host molecules, tris(4′‐(1‐phenyl‐1H‐benzimidazol‐2‐yl)biphen‐yl‐4‐yl) amine (TIBN), tris(2′‐methyl‐4′‐(1‐phenyl‐1H‐benzimida zol‐2‐yl)biphenyl‐4‐yl)amine (Me‐TIBN), and tris(2,2′‐dimethyl‐4′‐(1‐phenyl‐1H‐benzimidazol‐2‐yl)biphenyl‐4‐yl)amine (DM‐TIBN), that contain hole‐transporting triphenylamine and electron‐transporting benzimidazole moieties are designed based on calculations using density functional theory and successfully prepared. The theoretical calculation of energy levels of TIBN derivatives affords helpful ideas to design molecules with a favorable localization of highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO) levels and a predefined enhancement of the triplet energy gap. The TIBN derivatives are employed as hosts to fabricate phosphorescent organic light‐emitting diodes (OLEDs) by the two methods of spin‐coating and vacuum deposition. Notably, the spin‐coated Me‐TIBN and DM‐TIBN devices exhibit a much better performance than the vacuum‐deposited ones, in which the spin‐coated DM‐TIBN device (47 500 cd m−2, 27.3 cd A−1, 7.3 lm W−1) is outstanding with respect to other seminal work for solution‐processed OLEDs. More importantly, the new concept of localizing HOMO and LUMO levels for bipolar molecules is illustrated, and a facile strategy to tailor the energy levels by breaking the conjugation of hole‐ and electron‐transporting moieties is demonstrated.