bluuebunny/crossref_metadata_2025 huggingface dataset:
A BRIEF OPPORTUNITY TO RUN DOES NOT FUNCTION AS A REINFORCER FOR MICE SELECTED FOR HIGH DAILY WHEEL‐RUNNING RATES
Authors: Belke Terry W. , Garland Theodore
Published: March 2008

Mice from replicate lines, selectively bred based on high daily wheel‐running rates, run more total revolutions and at higher average speeds than do mice from nonselected control lines. Based on this difference it was assumed that selected mice would find the opportunity to run in a wheel a more efficacious consequence. To assess this assumption within an operant paradigm, mice must be trained to make a response to produce the opportunity to run as a consequence. In the present study an autoshaping procedure was used to compare the acquisition of lever pressing reinforced by the opportunity to run for a brief opportunity (i.e., 90 s) between selected and control mice and then, using an operant procedure, the effect of the duration of the opportunity to run on lever pressing was assessed by varying reinforcer duration over values of 90 s, 30 min, and 90 s. The reinforcement schedule was a ratio schedule (FR 1 or VR 3). Results from the autoshaping phase showed that more control mice met a criterion of responses on 50% of trials. During the operant phase, when reinforcer duration was 90 s, almost all control, but few selected mice completed a session of 20 reinforcers; however, when reinforcer duration was increased to 30 min almost all selected and control mice completed a session of 20 reinforcers. Taken together, these results suggest that selective breeding based on wheel‐running rates over 24 hr may have altered the motivational system in a way that reduces the reinforcing value of shorter running durations. The implications of this finding for these mice as a model for attention deficit hyperactivity disorder(ADHD) are discussed. It also is proposed that there may be an inherent trade‐off in the motivational system for activities of short versus long duration.
Efficacy of motor cortex stimulation in the treatment of neuropathic pain: a randomized double-blind trial
Authors: Velasco Francisco , Argüelles Carlos , Carrillo-Ruiz José D. , Castro Guillermo , Velasco Ana Luisa , Jiménez Fiacro , Velasco Marcos
Published: March 2008

Object

In this study the authors used a double-blind protocol to assess the efficacy of motor cortex stimulation (MCS) for treating neuropathic pain.

Methods

Eleven patients with unilateral neuropathic pain (visual analog scale [VAS] score 8–10) of different origins and topography were selected for MCS. A 20-contact grid was implanted through a craniotomy centered over the motor cortex contralateral to the painful area. The motor cortex strip was identified using neuroimages, somatosensory evoked potentials, acute electrical stimulation, and corticocortical evoked potentials. Subacute therapeutic stimulation trials allowed the authors to determine the most efficient pair of contacts to use for long-term MCS. The grid was replaced with a 4-contact electrode connected to an internalized stimulator. Bipolar stimulation at a 40-Hz frequency, 90-μsec pulse width, amplitude 2–7 V, and 1 hour in “ON” and 4 hours in “OFF” mode was used. Pain was evaluated using the VAS, Bourhis, and McGill pain scales applied each month for 1 year. At Day 60 or 90, the stimulators were turned to OFF mode for 30 days in a randomized, double-blind fashion. The statistical tool used was the Wilcoxon test.

Results

Three patients did not report improvement in the subacute trial and were excluded from long-term MCS; the remaining patients underwent long-term stimulation. Significant improvement of pain was induced by MCS (p < 0.01); this persisted during the follow-up period. Turning stimulation to OFF mode increased pain significantly (p < 0.05). Improvement at 1 year was ≥ 40% (40–86%) in all cases.

Conclusions

Motor cortex stimulation is an efficient treatment for neuropathic pain, according to an evaluation facilitated by a double-blind maneuver. Subacute stimulation trials are recommended to determine the optimum motor cortex area to be stimulated and to identify nonresponders.
Intraoperative acquisition of three-dimensional imaging for frameless stereotactic guidance during transsphenoidal pituitary surgery using the Arcadis Orbic System
Authors: Fox W. Christopher , Wawrzyniak Scott , Chandler William F.
Published: March 2008

Object

Intraoperative fluoroscopy has long been used for anatomical localization in transsphenoidal pituitary surgery. More recently, frameless stereotaxy has been used to supplement 2D sagittal radiographs with 3D multiplanar reconstructions. Use of Arcadis Orbic allows both conventional fluoroscopic views and multiplanar reconstructions to be acquired intraoperatively without need for preoperative planning studies. The authors report their initial experience using Arcadis Orbic during transsphenoidal pituitary surgery.

Methods

To test the system, the authors placed a dehydrated human skull in a radiolucent head holder, and obtained standard 2D fluoroscopic images of the skull base and sella turcica. Arcadis Orbic was then used with frameless stereotaxy to register 3D multiplanar reconstructed images of skull base anatomy. The authors then used Arcadis Orbic in 26 transsphenoidal pituitary tumor resections and compared image quality, accuracy, and ease-of-use to standard techniques.

Results

Arcadis Orbic 2D fluoroscopic images matched or exceeded the quality of images acquired by standard C-arm machines. Arcadis Orbic multiplanar reconstructions provided excellent images of the skull base when compared with preoperative Stealth computed tomography (CT) studies. Intraoperative frameless stereotactic navigation using Arcadis Orbic was highly accurate and more reliable than registering preoperative CT images.

Conclusions

Arcadis Orbic provides excellent quality 2- and 3D images during transsphenoidal pituitary surgery, and intraoperative frameless navigation using these images is highly accurate. Arcadis Orbic is easy to use, even in patients with large body habitus, and image acquisition takes no longer than registration during a frameless stereotactic case. Based upon our preliminary experience, Arcadis Orbic precludes the need for preoperative CT studies in patients with pituitary lesions requiring frameless stereotactic navigation.
Selective denervation of the levator scapulae muscle: an amendment to the Bertrand procedure for the treatment of spasmodic torticollis
Authors: Anderson William S. , Lawson Herman Christopher , Belzberg Allan J. , Lenz Frederick A.
Published: March 2008

Object

The purpose of this cadaveric study was to explore a modification to the Bertrand procedure for the treatment of spasmodic torticollis, namely the denervation of the levator scapulae (LS) muscle for laterocollis.

Methods

The authors performed a series of 9 cadaveric dissections. Five were done to identify the anterior innervation of the LS, and the remaining 4 were to identify the tendinous insertions of the LS onto the lateral masses of the cervical spine via a posterior approach. The nerve supply to the LS from the anterior divisions of the C-3 and C-4 nerve roots and the contribution from the dorsal scapular nerve were identified over the anterior surface of the muscle.

Results

The C-3 and C-4 nerve root branches were situated within 2 cm of each other and inferior to the punctum nervosum. The dorsal scapular contribution was clearly identified in 2 cadavers. Selective denervation of this muscle is possible through the same posterior triangle incision used for denervating the sternocleidomastoid muscle of its accessory nerve branches. This approach will be helpful in patients with laterocollis contralateral to the direction of chin turning. The authors compare this approach to the posterior approach for sectioning the insertions of the LS muscle onto the C1–4 posterior tubercles. The latter approach is appropriate for ipsilateral laterocollis.

Conclusions

The posterior triangle approach for denervating the LS muscle is a safe and easy addition to the Bertrand procedure and can be helpful in selected cases of torticollis with a laterocollis component.
Diffusion tensor tractography of the temporal stem on the inferior limiting sulcus
Authors: Wang Feng , Sun Tao , Li Xing-Gang , Liu Na-Jia
Published: March 2008

Object

The aim of this study was to use diffusion tensor tractography (DTT) to define the 3D relationships of the uncinate fasciculus, anterior commissure, inferior occipitofrontal fasciculus, inferior thalamic peduncle, and optic radiation and to determine the positioning landmarks of these white matter tracts.

Methods

The anatomy was studied in 10 adult human brain specimens. Brain DTT was performed in 10 healthy volunteers. Diffusion tensor tractography images of the white matter tracts in the temporal stem were obtained using the simple single region of interest (ROI) and multi-ROIs based on the anatomical knowledge.

Results

The posteroinferior insular point is the anterior extremity of intersection of the Heschl gyrus and the inferior limiting sulcus. On the inferior limiting sulcus, this point is the posterior limit of the optic radiation, and the temporal stem begins at the limen insulae and ends at the posteroinferior insular point. The distance from the limen insulae to the tip of the temporal horn is just one third the length of the temporal stem. The uncinate fasciculus comprises the core of the anterior temporal stem, behind which the anterior commissure and the inferior thalamic peduncle are located, and they occupy the anterior third of the temporal stem. The inferior occipitofrontal fasciculus passes through the entire temporal stem. The most anterior extent of the Meyer loop is located between the anterior tip of the temporal horn and the limen insulae. Most of the optic radiation crosses the postmedian two thirds of the temporal stem.

Conclusions

On the inferior limiting sulcus, the posteroinferior insular point is a reliable landmark of the posterior limit of the optic radiations. The limen insulae, anterior tip of the temporal horn, and posteroinferior insular point may be used to localize the white matter fibers of the temporal stem in analyzing magnetic resonance imaging or during surgery.
A distinct phenotypic change in gliomas at the time of magnetic resonance imaging detection
Authors: Jang Taichang , Sathy Binulal , Hsu Yi-Hua , Merchant Milton , Recht Benjamin , Chang Chen , Recht Lawrence
Published: March 2008

Object

Although gliomas remain refractory to treatment, it is not clear whether this characteristic is fixed at the time of its origin or develops later. The authors have been using a model of neurocarcinogenesis to determine whether a time exists during a glioma's evolution during which it is detectable but still curable, thus providing a justification for exploring the clinical merits of an early detection and treatment strategy. The authors recently reported the presence of 2 distinct cellular subsets, 1 expressing nestin and the other both glial fibrillary acidic protein (GFAP) and osteopontin (OPN), within all examined gliomas that developed after in utero exposure to ethylnitrosourea.

Methods

In this study, the authors used magnetic resonance (MR) imaging to assess when these 2 subpopulations appeared during glioma evolution.

Results

Using T2-weighted and diffusion-weighted MR imaging, the authors observed that gliomas grew exponentially once detected at rates that were location-dependent. Despite large differences in growth rates, however, they determined by correlating histochemistry with imaging in a second series of animals, that all lesions initially detected on T2-weighted images contained both subsets of cells. In contrast, lesions containing only nestin-positive cells, which appeared on average 40 days before detection on MR images, were not detected.

Conclusions

The sequential appearance of first the nestin-positive cells followed several weeks later by those expressing GFAP/OPN suggests that all gliomas arise through common early steps in this model. Furthermore, the authors hypothesize that the expression of OPN, a molecule associated with cancer aggressiveness, at the time of T2-weighted detection signals a time during glioma development when the lesion becomes refractory to treatment.
Effective suppression of hippocampal seizures in rats by direct hippocampal cooling with a Peltier chip
Authors: Tanaka Nobuhiro , Fujii Masami , Imoto Hirochika , Uchiyama Joji , Nakano Kimihiko , Nomura Sadahiro , Fujisawa Hirosuke , Kunitsugu Ichiro , Saito Takashi , Suzuki Michiyasu
Published: March 2008

Object

The use of focal brain cooling to eliminate epileptic discharges (EDs) has attracted increasing attention in the scientific community. In this study, the inhibitory effect of selective hippocampal cooling on experimental hippocampal seizures was investigated using a newly devised cooling system with a thermoelectric (Peltier) chip.

Methods

A copper needle coated with silicone and attached to the Peltier chip was used for the cooling device. The experiments were performed first in a phantom model with thermography and second in adult male Sprague–Dawley rats in a state of halothane anesthesia. The cooling needle, a thermocouple, and a needle electrode for electroencephalography recording were inserted into the right hippocampus. Kainic acid (KA) was injected into the right hippocampus to provoke the EDs. The animals were divided into hippocampal cooling (10 rats) and noncooling (control, 10 rats) groups.

Results

In the phantom study, the cooling effects (9°C) occurred in the spherical areas around the needle tip. In the rats the temperature of the cooled hippocampus decreased below 20°C within a 1.6-mm radius and below 25°C within a 2.4-mm radius from the cooling center. The temperature at the needle tip decreased below 20°C within 1 minute and was maintained at the same level until the end of the cooling process. The amplitude of the EDs was suppressed to 68.1 ± 4.8% of the precooling value and remained low thereafter. No histological damage due to cooling was observed in the rat hippocampus.

Conclusions

Selective hippocampal cooling effectively suppresses the KA-induced hippocampal EDs. Direct hippocampal cooling with a permanently implantable system is potentially useful as a minimally invasive therapy for temporal lobe epilepsy and therefore could be an alternative to the temporal lobectomy.
Guglielmi detachable coil embolization of acute intracranial aneurysm: perioperative anatomical and clinical outcome in 403 patients
Authors: Viñuela Fernando , Duckwiler Gary , Mawad Michel
Published: March 2008

✓From December 1990 to July 1995, the investigators participated in a prospective clinical study to evaluate the safety of the Guglielmi detachable coil (GDC) system for the treatment of aneurysms. This report summarizes the perioperative results from eight initial interventional neuroradiology centers in the United States. The report focuses on 403 patients who presented with acute subarachnoid hemorrhage from a ruptured intracranial aneurysm. These patients were treated within 15 days of the primary intracranial hemorrhage and were followed until they were discharged from the hospital or died.

Seventy percent of the patients were female and 30% were male. The patients' mean age was 58 years old. Aneurysm size was categorized as small (60.8%), large (34.7%), and giant (4.5%); and neck size was categorized as small (53.6%), wide (36.2%), fusiform (6%), and undetermined (4.2%). Fifty-seven percent of the aueurysms were located in the posterior circulation and 43% in the anterior circulation.

Eighty-two patients were classified as Hunt and Hess Grade I (20.3%), 105 Grade II (26.1%), 121 Grade III (30%), 69 Grade IV (17.1%), and 26 Grade V (6.5%). All patients in this study were excluded from surgical treatment either because of anticipated surgical difficulty (69.2%), attempted and failed surgery (12.7%), the patient's poor neurological (12.2%) or medical (4.7%) status, and/or refusal of surgery (1.2%).

The GDC embolization was performed within 48 hours of primary hemorrhage in 147 patients (36.5%), within 3 to 6 days in 156 patients (38.7%), 7 to 10 days in 71 patients (17.6%), and 11 to 15 days in 29 patients (7.2%). Complete aneurysm occlusion was observed in 70.8% of small aneurysms with a small neck, 35% of large aneurysms, and 50% of giant aneurysms. A small neck remnant was observed in 21.4% of small aneurysms with a small neck, 57.1% of large aneurysms, and 50% of giant aneurysms. Technical complications included aneurysm perforation (2.7%), unintentional parent artery occlusion (3%), and untoward cerebral embolization (2.48%). There was a 8.9% immediate morbidity rate related to the GDC technique. Seven deaths were related lo technical complications (1.74%) and 18 (4.47%) to the severity of the primary hemorrhage.

The findings of this study demonstrate the safety of the GDC system for the treatment of ruptured intracranial aneurysms in anterior and posterior circulations. The authors believe additional randomized studies will further identify the role of this technique in the management of acutely ruptured incranial aneurysms.
Characterization of abnormal diffusion properties of supratentorial brain tumors: a preliminary diffusion tensor imaging study
Authors: Yuan Weihong , Holland Scott K. , Jones Blaise V. , Crone Kerry , Mangano Francesco T.
Published: March 2008

Object

Diffusion tensor (DT) imaging was used in children with supratentorial tumors to evaluate the anisotropic diffusion properties between different tumor grades and between tumors and adjacent and contralateral white matter.

Methods

In this retrospective review, the authors review the cases of 16 children (age range 1–18 years) who presented to their institution with supratentorial tumors and were treated between 2004 and 2007. Eleven patients had low-grade and 5 had high-grade tumors. Fractional anisotropy (FA), mean diffusivity, and axial (λ∥) and radial (λ⊥) eigenvalues within selected regions were studied. Mitotic index, necrosis, and vascularity of the tumors were compared with DT imaging parameters.

Results

The mean diffusivity was significantly higher in low-grade than in high-grade tumors (p = 0.04); the 2 tumor grades also significantly differed for both λ∥ (p < 0.05) and λ⊥ (p < 0.05). Mean diffusivity values in low-grade tumors were significantly higher than in adjacent normal-appearing white matter (NAWM; p = 0.0004) and contralateral NAWM (p = 0.0001). In both low- and high-grade tumors, the FA was significantly lower than in NAWM (p < 0.0001 and p < 0.03, respectively) and contralateral NAWM (p < 0.0001 and p < 0.003, respectively). Tumor cellularity highly correlated with mean diffusivity and λ∥and λ⊥.

Conclusions

Diffusion tensor imaging is a useful tool in the evaluation of supratentorial tumors in children. The mean diffusivity appears to be a significant marker in differentiating tumors grades. Findings related to λ∥ and λ⊥ within tumor groups and between tumors and NAWM may be an indirect manifestation of the combined effects of axonal injury, demyelination, and tumor mass within the cranial compartment.
Gamma Knife surgery for cerebral arteriovenous malformations in children: a 13-year experience
Authors: Pan David Hung-Chi , Kuo Yu-Hung , Guo Wan-Yuo , Chung Wen-Yuh , Wu Hsiu-Mei , Liu Kang-Du , Chang Yue-Cune , Wang Ling-Wei , Wong Tai-Tong
Published: March 2008

Object

Studies on the efficacy of arteriovenous malformation (AVM) radiosurgery have largely been conducted in the adult population. Clinically, the results may not always be applicable to pediatric patients. Moreover, studies involving the pediatric population have largely comprised small- (< 3 cm3) and medium-sized (3–10 cm3) AVMs. For large (> 10 cm3) AVMs in children, sparse radiosurgical results are available. The current study was conducted to further clarify the role of radiosurgery in the treatment of pediatric AVMs.

Methods

A retrospective analysis was performed of data obtained in 105 pediatric patients (< 18 years of age) with cerebral AVMs treated by Gamma Knife surgery (GKS) between 1993 and 2006. For statistical comparison the authors studied data acquired in 458 adult patients with AVMs treated during the same period. The patients underwent follow-up magnetic resonance imaging at 6-month intervals. Cerebral angiography was used to confirm the obliteration of the AVM.

Results

In pediatric patients, the AVM obliteration rate at 48 months after a primary GKS was 65%. Repeated GKS in those in whom primary treatments failed further ablated some AVMs, for an overall obliteration rate of 81%. The efficacy of GKS correlated with the size of the AVM: 91% for small, 86% for medium, and 64% for large AVMs. The treatments were associated with an 8% morbidity rate and < 1% mortality rate. Posttreatment hemorrhage occurred in 4 (4%) of 105 patients. Obliteration rates at 48 months of small and extremely large (> 20 cm3) AVMs were similar in the pediatric and adult groups, whereas AVMs between 3 and 10 cm3 responded less efficaciously in children (p = 0.042). The AVMs with volumes ranging from 10 to 20 cm3 were also associated with a lower obliteration rate in children at 48 months, but statistical significance was not reached (p = 0.279).

Conclusions

Gamma Knife surgery is an effective and safe treatment alternative for pediatric AVMs. The medium (3–10-cm3) and large (10–20-cm3) AVMs tend to respond less efficaciously than those of comparable size in adults.
Pollen and anther ontogeny in Cabomba caroliniana (Cabombaceae, Nymphaeales)
Authors: Taylor Mackenzie L. , Gutman Benjamin L. , Melrose Natalie A. , Ingraham Angela M. , Schwartz Julie A. , Osborn Jeffrey M.
Published: March 2008

Cabomba is a small water lily genus that is native to the New World. Studies of pollen development and associated changes in the anther yield valuable characters for considering the evolution of reproductive biology in seed plants. Here we characterized the complete ontogenetic sequence for pollen in Cabomba caroliniana. Anthers at the microspore mother cell, tetrad, free microspore, and mature pollen grain stages were studied using scanning electron, transmission electron, and light microscopy. Tetragonal and decussate tetrads both occur in C. caroliniana, indicating successive microsporogenesis. The exine is tectate‐columellate, and the infratectal columellae are the first exine elements to form, followed by a continuous tectum and a thin foot layer. A lamellate endexine initiates in the early free microspore stage, but becomes compressed in mature grains. Tectal microchannels and sculptural rods also initiate during the early free microspore stage, and significant pollenkitt deposition follows, supporting the hypothesis that these elements function in entomophily. The tapetum is morphologically amoeboid, with migratory tapetal cells directly contacting developing free microspores within the anther locule. Results from this study illustrate the importance of including ontogenetic data in analyzing pollen characters and in developing evolutionary and ecological hypotheses. The new palynological data also emphasize the character plasticity that occurs in basal angiosperms.
Growth, development, and systematics of ferns: Does Botrychium s.l. (Ophioglossales) really produce secondary xylem?1
Authors: Rothwell Gar W. , Karrfalt Eric E.
Published: March 2008

Developmental morphology and anatomy of Botrychium s.l. were studied to clarify rhizome ontogeny and patterns of tissue maturation that can be used to test the hypothesis that ferns of the Ophioglossales may represent living progymnosperms. Serial anatomical sections of the rhizomes of B. virginianum and B. dissectum reveal that apical meristematic activity and vascular tissue maturation occur over an extended period of several years and then stop. Most of the xylem consists of radial rows of tracheids and interspersed ray‐like xylem parenchyma cells that are similar in these respects to secondary xylem, but pits occur on all tracheid walls as is characteristic of primary xylem. No vascular cambium is initiated in mature primary tissues, nor is there secondary phloem. Radial rows of xylem cells are produced by the direct continuation of divisions that begin at the shoot apical meristem, forming a cylinder of radially aligned procambial cells before the differentiation of protoxylem. Continuing divisions over a period of several years increase the number of thin‐walled cells and tracheids in each radial row back to about one internode behind where the current year's frond trace diverges from the rhizome stele. At more proximal levels of the rhizome, procambial cell divisions cease and there is no additional tracheid differentiation. These data reveal that the rhizome matures over an exceedingly long period of several years, but that growth is ultimately determinate, thus supporting hypotheses that the Ophioglossales is more closely related to other groups of living ferns than to progymnosperms and seed plants.
Seed ferns survived the end‐Cretaceous mass extinction in Tasmania
Authors: McLoughlin Stephen , Carpenter Raymond J. , Jordan Gregory J. , Hill Robert S.
Published: March 2008

Seed ferns, dominant elements of the vegetation in many parts of the world from the Triassic to Cretaceous, were considered to have disappeared at the end of the Cretaceous together with several other groups that had occupied key positions in terrestrial and marine ecosystems such as dinosaurs, plesiosaurs, and ammonoids. Seed‐fern demise is generally correlated with competition from diversifying flowering plants through the Cretaceous and the global environmental crisis related to the Chicxulub impact event in the paleotropics at the end of the period. New fossils from Tasmania show that one seed‐fern lineage survived into the Cenozoic by at least 13 million years. These fossils are described here as a new species,Komlopteris cenozoicus.Komlopterisis a genus of seed ferns attributed to Corystospermaceae and until now was not known from sediments younger than the Early Cretaceous. Discovery of this “Lazarus taxon,” together with the presence of a range of other relictual fossil and extant organisms in Tasmania, other southern Gondwanan provinces, and some regions of northern North America and Asia, underscores high‐latitude regions as biodiversity refugia during global environmental crises and highlights their importance as sources of postextinction radiations.
Undoped p‐Type ZnO Nanorods Synthesized by a Hydrothermal Method
Authors: Hsu Yuk Fan , Xi Yan Yan , Tam Kai Hang , Djurišić Aleksandra B. , Luo Jiaming , Ling Chi Chung , Cheung Chor Keung , Ng Alan Man Ching , Chan Wai Kin , Deng Xin , Beling Christopher D. , Fung Stevenson , Cheah Kok Wai , Fong Patrick Wai Keung , Surya Charles C.
Published: March 2008

Zinc oxide is a very promising material for short‐wavelength light‐emitting devices due to its large band gap and high exciton binding energy. Although great progress has been made in recent years, p‐type doping and control over native defects introduced during or after material growth are still significant problems that hinder the development of efficient ZnO based optoelectronic devices. Here we demonstrate a versatile method for the growth or p‐type or n‐type ZnO nanorods from the same growth solution at temperature as low as 90 °C, where the conductivity type is controlled by the preparation of the seed layer for nanorod growth. The differences in the conductivity type can be attributed to dependency of native defect concentrations and hydrogen incorporation on the seed layer preparation method. Room temperature electroluminescence has been demonstrated from homojunction and heterojunction light emitting diodes containing p‐ZnO nanorods.
High Energy Density All‐Solid‐State Batteries: A Challenging Concept Towards 3D Integration
Authors: Baggetto Loıc , Niessen Rogier A. H. , Roozeboom Fred , Notten Peter H. L.
Published: March 2008

Rechargeable all‐solid‐state batteries will play a key role in many autonomous devices. Planar solid‐state thin film batteries are rapidly emerging but reveal several drawbacks, such as a relatively low energy density and the use of highly reactive metallic lithium. In order to overcome these limitations a new 3D‐integrated all‐solid‐state battery concept with significantly increased surface area is presented. By depositing the active battery materials into high‐aspect ratio structures etched in, for example silicon, 3D‐integrated all‐solid‐state batteries are calculated to reach a much higher energy density. Additionally, by adopting novel high‐energy dense Li‐intercalation materials the use of metallic Lithium can be avoided. Sputtered Ta, TaN and TiN films have been investigated as potential Li‐diffusion barrier materials. TiN combines a very low response towards ionic Lithium and a high electronic conductivity. Additionally, thin film poly‐Si anodes have been electrochemically characterized with respect to their thermodynamic and kinetic Li‐intercalation properties and cycle life. The Butler‐Vollmer relationship was successfully applied, indicating favorable electrochemical charge transfer kinetics and solid‐state diffusion. Advantageously, these new Li‐intercalation anode materials were found to combine an extremely high energy density with fast rate capability, enabling future 3D‐integrated all‐solid‐state batteries.
Efficient Conjugated‐Polymer Optoelectronic Devices Fabricated by Thin‐Film Transfer‐Printing Technique
Authors: Yim Keng‐Hoong , Zheng Zijian , Liang Ziqi , Friend Richard H. , Huck Wilhelm T. S. , Kim Ji‐Seon
Published: March 2008

The fabrication of functional multilayered conjugated‐polymer structures with well‐defined organic‐organic interfaces for optoelectronic‐device applications is constrained by the common solubility of many polymers in most organic solvents. Here, we report a simple, low‐cost, large‐area transfer‐printing technique for the deposition and patterning of conjugated‐polymer thin films. This method utilises a planar poly(dimethylsiloxane) (PDMS) stamp, along with a water‐soluble sacrificial layer, to pick up an organic thin film (∼20 nm to 1 µm) from a substrate and subsequently deliver this film to a target substrate. We demonstrate the versatility of this transfer‐printing technique and its applicability to optoelectronic devices by fabricating bilayer structures of poly(9,9‐di‐n‐octylfluorene‐alt‐(1,4‐phenylene‐((4‐sec‐butylphenyl)imino)‐1,4‐phenylene))/poly(9,9‐di‐n‐octylfluorene‐alt‐benzothiadiazole) (TFB/F8BT) and poly(3‐hexylthiophene)/methanofullerene([6,6]‐phenyl C61 butyric acid methyl ester) (P3HT/PCBM), and incorporating them into light‐emitting diodes (LEDs) and photovoltaic (PV) cells, respectively. For both types of device, bilayer devices fabricated with this transfer‐printing technique show equal, if not superior, performance to either blend devices or bilayer devices fabricated by other techniques. This indicates well‐controlled organic‐organic interfaces achieved by the transfer‐printing technique. Furthermore, this transfer‐printing technique allows us to study the nature of the excited states and the transport of charge carriers across well‐defined organic interfaces, which are of great importance to organic electronics.
Epitaxial Growth of Aligned Semiconductor Nanowire Metamaterials for Photonic Applications
Authors: Muskens Otto L. , Diedenhofen Silke L. , van Weert Maarten H. M. , Borgström Magnus T. , Bakkers Erik P. A. M. , Rivas Jaime Gómez
Published: March 2008

A novel class of optical metamaterials is presented consisting of high densities of aligned gallium phosphide (GaP) nanowires fabricated using metal‐organic vapor phase‐epitaxy. Starting from a gold island film as a catalyst for nanowire growth, a sequential combination of vapor–liquid–solid and lateral growth modes is employed to obtain a continuous tunability of the nanowire volume fraction from 7% to over 35%. By choosing different crystallographic orientations of the GaP substrate, metamaterials are designed with different nanowire orientations. The anisotropy of the nanowire building blocks results in strong optical birefringence. Polarization interferometry demonstrates a very large polarization extinction contrast of 4 × 103 combined with a sharp angular resonance which holds promise for optical sensing. Nanowire metamaterials may find applications in photonics, optoelectronics, non‐linear and quantum optics, microfluidics, bio‐, and gas sensing.
Continuous Application of Polyglycerol‐Supported Salen in a Membrane Reactor: Asymmetric Epoxidation of 6‐Cyano‐2,2‐dimethylchromene
Authors: Beigi Maryam , Haag Rainer , Liese Andreas
Published: March 2008

In the current work, suitability of hyperbranched polyglycerol as a high loading catalyst support is demonstrated. A polyglycerol‐supported manganese‐salen complex (chemzyme) is applied as a homogeneous catalyst in the epoxidation of 6‐cyano‐2,2‐dimethylchromene. The recyclability of the corresponding catalyst was investigated in repetitive batch experiments as well as a continuous operation of the reaction in an ultrafiltration membrane reactor. An enhanced stability of the catalyst in repetitive batches was observed as a result of immobilization whereby the total turnover number increased from 23 in a single batch to 80 in four repetitive batches. To enable continuous operation, a continuously operated, stirred tanked reactor (CSTR) was equipped with an ultrafiltration membrane (MPF‐50) and a retention of 98% was determined. The continuous chemzyme membrane reactor was operated over the course of 20 residence times. After approximately 12 residence times, the steady state was reached yielding 70% conversion as well as an enantiomeric excess up to 92%. A space‐time yield (sty) of 458 g L−1 d−1 and a turnover frequency (TOFreaction) of up to 18 h−1 was reached in the steady state. It was determined that the total turnover number (TTN) was enhanced by a factor of 10 from 24 (batch) up to 240 for 20 residence times in CSTR operation.
Highly Efficient Brønsted Acid‐Catalyzed Cycloisomerizations of Alkynes Bearing Bis(acetoxy) Groups to Indenyl Ketones
Authors: Liu Yuanhong , Zhou Shaolin , Li Guijie , Yan Bin , Guo Shenghai , Zhou Yebing , Zhang Hao , Wang Peng George
Published: March 2008

A Brønsted acid‐catalyzed cycloisomerization of functionalized alkynes is described, which is assumed to be initiated through the formation of a benzylic cation intermediate. The reaction offers a highly efficient and straightforward route to indenyl ketones with a wide range of substituents under mild conditions.
Designing man‐portable power generation systems for varying power demand
Authors: Yunt Mehmet , Chachuat Benoît , Mitsos Alexander , Barton Paul I.
Published: March 2008

Portable electronic devices operate at varying power demand levels. This variability of power demand must be considered explicitly in the design of man‐portable power generation systems for acceptable performance and portability. In this regard, a mathematical programming based design method is proposed. The method transcribes optimal operation of the system at a given power demand into a mathematical program. The power demand specific programs are incorporated into another upper level mathematical program encoding design requirements to form a final two‐stage formulation. The design and operational parameters of the power generation system comprise a solution of the formulation. Unlike designs, based on a nominal power demand, the design guarantees that each power demand and all operational requirements can be satisfied. A detailed study of a microfabricated fuel‐cell based system is performed. The proposed method produces smaller designs with significantly better performances than nominal power demand based approaches. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Selective acetylene hydrogenation over core–shell magnetic Pd‐supported catalysts in a magnetically stabilized bed
Authors: Dong Minghui , Pan Zhiyong , Peng Ying , Meng Xiangkun , Mu Xuhong , Zong Baoning , Zhang Jinli
Published: March 2008

A novel magnetic microspherical catalyst support with enough mechanical strength was prepared through coating Al2O3on a magnetic core of NiFe2O4spinel ferrite using the oil drop method to synthesize magnetic Pd‐supported catalyst for acetylene hydrogenation reaction. The synthesized core–shell composite Pd/Al2O3catalyst shows high surface area and pore volume as well as sufficient saturated magnetization property, characterized by powder X‐ray diffraction, low‐temperature N2adsorption–desorption analysis, and magnetic measurements. Catalytic performance of this magnetic Pd/Al2O3catalyst was measured for acetylene hydrogenation reaction in a magnetically stabilized bed (MSB) reactor under different operation conditions. Under the optimal conditions of 353 K, 1.5 MPa and a gas hourly space velocity of 12,000 h−1, C2H2conversion and C2H4selectivity approximated 100% and 84%, respectively, over this magnetic Pd/Al2O3catalyst in the MSB reactor, as a control over the commercial catalyst for hydrogenation reaction C2H2conversion and C2H4selectivity was near 37 and 64% under the similar conditions. Significant improvement of acetylene hydrogenation processes over this novel magnetic catalyst enlightens us a promising route to explore process intensification techniques through MSB. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Kinetic characterization of biomass dilute sulfuric acid hydrolysis: Mixtures of hardwoods, softwood, and switchgrass
Authors: Jensen Jill , Morinelly Juan , Aglan Anwar , Mix Adam , Shonnard David R.
Published: March 2008

The effects of woody biomass mixtures were investigated on the rates of hemicellulose hydrolysis by dilute acid. Very good agreement between the model predictions and single species acid hydrolysis data confirmed the validity of a pseudo first‐order model approach. This model was then utilized to predict monomer sugar concentrations for mixtures of hardwood (aspen, basswood, and red maple), a softwood (balsam), and the energy crop switchgrass, with very good agreement. The results of this study show that there are not significant synergistic or antagonistic effects by mixtures of woody biomass species on the kinetics of hemicellulose hydrolysis by dilute acid. Kinetic parameters were developed for each woody biomass species with xylose formation activation energies ranging from 76.19–171.20 kJ/mol, and pre‐exponential factors ranging from 2.19 × 108–7.73 × 1019 min−1. Overall xylose yields for pure biomass species ranged from approximately 66–88% with balsam having the lowest yield and switchgrass producing the highest yield. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Gelatin multilayers assembled on poly(L‐lactic acid) surface for better cytocompatibility
Authors: Lin Yuan , Chen Xuesi , Jing Xiabin , Jiang Yinshan , Su Zhaohui
Published: March 2008

Gelatin multilayers were assembled on PLLA substrate at pH 3, 5, and 7, which was below, around, and above the isoelectric point of the amphoteric polymer, using the layer‐by‐layer assembly technique. The multilayer deposition on the PLLA substrate was monitored by X‐ray photoelectron spectroscopy (XPS) and water contact angle measurement. The XPS, water contact angle, and atomic force microscopy data indicated that the layer thickness, surface hydrophilicity, and surface morphology of the gelatin multilayers assembled strongly depended on the pH at which the layers were deposited. Chondrocyte culture was used to test the cell attachment, cell morphology, and cell viability on the PLLAs modified with gelatin multilayers. All these modified PLLAs exhibited dramatically improved cytocompatibility compared with the virgin PLLA, and even better performance than that of tissue culture polystyrene (TCPS). The best cell compatibility was observed for the gelatin multilayers assembled at pH = 5. These results indicate that the cell compatibility of biodegradable polyesters can be effectively and facilely improved by assembly of gelatin multilayers, and the performance can be controlled by adjusting the solution pH at which the multilayers are deposited. This may help the design and fabrication of better scaffolds for tissue engineering. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Beliefs about what types of mechanisms produce random sequences
Authors: Blinder Deborah S. , Oppenheimer Daniel M.
Published: March 2008

Although many researchers use Wagenaar's framework for understanding the factors that people use to determine whether a process is random, the framework has never undergone empirical scrutiny. This paper uses Wagenaar's framework as a starting point and examines the three properties of his framework—independence of events, fixed alternatives, and equiprobability. We find strong evidence to suggest that independence of events is indeed used as a cue toward randomness. Equiprobability has an effect on randomness judgments. However, it appears to work only in a limited role. Fixedness of alternatives is a complex construct that consists of multiple sub‐concepts. We find that each of these sub‐concepts influences randomness judgments, but that they exert forces in different directions. Stability of outcome ratios increases randomness judgments, while knowledge of outcome ratios decreases randomness judgments. Future directions for development of a functional framework for understanding perceptions of randomness are suggested. Copyright © 2008 John Wiley & Sons, Ltd.
SAR and efficiency evaluation of a 900 MHz waveguide chamber for cell exposure
Authors: De Prisco Giuseppe , d'Ambrosio Guglielmo , Calabrese Maria Lucia , Massa Rita , Juutilainen Jukka
Published: March 2008

In this work we present the results of numerical and experimental dosimetry carried out for an in vitro exposure device to irradiate sample groups at 900 MHz. The cells are kept in 8 and 15 ml cell cultures, contained, respectively in T25 and T75 rectangular flasks. The dosimetric assessment of the distribution of the specific absorption rate (SAR) is performed for both the bottom of the flask and the whole volume of the sample to provide results for experiments on either the cell layer or the cell suspension. The irradiating chamber is a rectangular waveguide (WG). Different configurations are considered to assess the optimum orientation and positioning of the cell cultures inside the WG. The system performance is optimal when the electric field is parallel to the sample and the WG is terminated by a matched load. In this condition two 15 or four 8 ml cells cultures can be exposed. The efficiency (ratio between the power absorbed by the sample and the incident power) and the non‐uniformity degree (ratio between the standard deviation of SAR values and the average SAR over the sample) are calculated and successfully verified through measurements of the scattering parameters and local temperature increases. In the chosen exposure configuration, the efficiency is 0.40 and the non‐uniformity degree is 39% for the 15 ml samples. For the 8 ml samples, the efficiency is 0.19 and a low non‐uniformity degree (15%) is found. Bioelectromagnetics 29:429–438, 2008. © 2008 Wiley‐Liss, Inc.
The mechanical transduction of physiological strength electric fields
Authors: Hart Francis X.
Published: March 2008

In this article it is proposed that electric fields of physiological strength (∼100 V/m) are transduced by the mechanical torque they exert on glycoproteins. The resulting mechanical signal is then transmitted to the cytoskeleton and propagated throughout the cell interior. This mechanical coupling is analyzed for transmembrane glycoproteins, such as integrins and the glycocalyx, and for glycoproteins in the extracellular matrix of cartilage. The applied torque is opposed by viscous fluid drag and restoring forces exerted by adjacent molecules in the membrane or cartilage. The resulting system represents a damped, driven harmonic oscillator. The amplitude of oscillation is constant at low frequencies, but falls off rapidly in the range 1–1000 Hz. The transition frequency depends on parameters such as the viscosity of the surrounding fluid and the restoring force exerted by the surrounding structure. The amplitude increases as the fourth power of the length of the transmembrane glycoproteins and as the square of the applied field. This process may operate in concert with other transduction mechanisms, such as the opening of voltage‐gated channels and electrodiffusion/osmosis for DC fields. Bioelectromagnetics 29:447–455, 2008. © 2008 Wiley‐Liss, Inc.
In vivo MR imaging of magnetically labeled mesenchymal stem cells transplanted into rat liver through hepatic arterial injection
Authors: Cai Jinhua , Zhang Xuemei , Wang Xin , Li Chuan , Liu Guanxin
Published: March 2008

Objective

The aim of this study was to evaluate in vivo magnetic resonance imaging (MRI) for tracking the magnetically labeled mesenchymal stem cells (MSCs) transplanted into rat liver through hepatic arterial injection.

Materials and Methods

MSCs, harvested from the bone marrow of Wistar rats and expanded by the adhesion method, were labeled with both Feridex and 4′,6‐diamidino‐2‐phenylindole (DAPI). Cell transplantation was performed by injection of 1 × 106 labeled cells (n = 20) or unlabeled cells (n = 10) via hepatic artery into rat livers treated with 2% carbon tetrachloride to induce acute liver necrosis. MR imaging was performed on a clinical 1.5 T MR scanner with a T2*‐weighted gradient‐echo sequence immediately before and at 1 h, 3 days, 7 days and 14 days after transplantation, and the signal‐to‐noise ratios (SNRs) were measured in liver, spleen, kidney and muscle. After MR examination, the animals were sacrificed, and the liver, kidney, lung and muscle were prepared for fluorescence observation and Prussian Blue staining.

Results

In the group treated with labeled cells, the SNR of the liver after cell transplantation was 3.12 ± 0.43 at 1 h, 7.98 ± 1.05 at 3 days and 11.46 ± 1.41 at 7 days. These values were significantly lower than the pre‐transplantation SNR (14.40 ± 0.37). In the group treated with unlabeled cells, no significant difference could be found between after and before transplantation liver SNRs. Prussian Blue staining showed iron particles, contained within the cytoplasm and distributed in the liver parenchyma, which corresponded to the DAPI‐stained fluorescent nuclei under the fluorescence microscope.

Conclusion

The magnetically labeled MSCs transplanted into rat liver through hepatic arterial injection can be detected and monitored in vivo with a 1.5 T clinical MR scanner for up to 7 days after cell transplantation. Copyright © 2008 John Wiley & Sons, Ltd.
Coexpression of the mu‐opioid receptor splice variant MOR1C and the vesicular glutamate transporter 2 (VGLUT2) in rat central nervous system
Authors: Schnell Stephen A. , Wessendorf Martin W.
Published: March 2008

It has been reported that mu‐opioid agonists depress glutamate release in some neurons but the specific receptor subtype mediating this effect is unclear. The purpose of the present study was to examine whether a particular mu‐opioid receptor (MOR) splice‐variant, MOR1C, is expressed in rat central nervous system (CNS) by terminals expressing the vesicular glutamate transporter2 (VGLUT2), a marker of glutamatergic neurons. Several MOR splice variants have been identified in mice and MOR1C appears mainly to be localized to fibers and terminals, from which most neurotransmitter release would be expected. In addition, VGLUT2 has been found in the CNS and antibodies to it are reliable markers for glutamatergic terminals. Using fluorescence immunohistochemistry and confocal microscopy to examine spatial relationships between MOR1C and VGLUT2, we found that MOR1C and VGLUT2 puncta were widely distributed throughout the rat CNS; moreover, many regions contained terminals that expressed both. Thus, it appears that coexpression of MOR1C and VGLUT2 is common in the rat CNS. We hypothesize that activation of MOR1C by mu‐opioid agonists at some glutamatergic terminals may be a mechanism by which glutamate release is inhibited. J. Comp. Neurol. 508:542–564, 2008. © 2008 Wiley‐Liss, Inc.