bluuebunny/crossref_metadata_2025_split huggingface dataset:
Efficacy of lamina terminalis fenestration in reducing shunt-dependent hydrocephalus following aneurysmal subarachnoid hemorrhage: a systematic review
Authors: Komotar Ricardo J. , Hahn David K. , Kim Grace H. , Starke Robert M. , Garrett Matthew C. , Merkow Maxwell B. , Otten Marc L. , Sciacca Robert R. , Connolly E. Sander 
Published: March 2009

Object
Chronic hydrocephalus requiring shunt placement is a common complication following aneurysmal subarachnoid hemorrhage (SAH). Controversy exists over whether microsurgical fenestration of the lamina terminalis during aneurysm surgery affords a reduction in the development of shunt-dependent hydrocephalus. To resolve this debate, the authors performed a systematic review and quantitative analysis of the literature to determine the efficacy of lamina terminalis fenestration in reducing aneurysmal SAH–associated shunt-dependent hydrocephalus.

Methods
A MEDLINE (1950–2007) database search was performed using the following keywords, singly and in combination: “ventriculoperitoneal shunt,” “hydrocephalus,” “subarachnoid hemorrhage,” “aneurysm,” “fenestration,” and “lamina terminalis.” Additional studies were manually singled out by scrutinizing references from identified manuscripts, major neurosurgical journals and texts, and personal files. A recent study from the authors' institution was also incorporated into the review. Data from included studies were analyzed using the chi-square analysis and Student t-test. The Cochran-Mantel-Haenszel test was used to compare overall incidence of shunt-dependent hydrocephalus.

Results
The literature search revealed 19 studies, but only 11 were included in this review, involving 1973 patients. The fenestrated and nonfenestrated cohorts (combined from the various studies) differed significantly with regard to patient sex, age, and clinical grade as well as aneurysm location (p = 0.0065, 0.0028, 0.0003, and 0.017, respectively). The overall incidence of shunt-dependent hydrocephalus in the fenestrated cohort was 10%, as compared with 14% in the nonfenestrated cohort (p = 0.089). The relative risk of shunt-dependent hydrocephalus in the fenestrated cohort was 0.88 (95% CI 0.62–1.24).

Conclusions
This systematic review revealed no significant association between lamina terminalis fenestration and a reduced incidence of shunt-dependent hydrocephalus. The interpretation of these results, however, is restricted by unmatched cohort differences as well as other inherent study limitations. Although the overall literature supports lamina terminalis fenestration, a number of authors have questioned the technique's benefits, thus rendering its efficacy in reducing shunt-dependent hydrocephalus unclear. A well-designed, multicenter, randomized controlled trial is needed to definitively address the efficacy of this microsurgical technique.
Minimal-access technique for distal catheter insertion during ventricular peritoneal shunt procedures: a review of 100 cases
Authors: Ochalski Pawel G. , Horowitz Michael B. , Mintz Arlan H. , Hughes Steven J. , Okonkwo David O. , Kassam Amin B. , Watson Andrew R. 
Published: March 2009

The authors report the safety and efficacy of using a percutaneous minimal-access insertion technique for distal shunt catheter placement in 100 cases.
From June 2007 to March 2008, they attempted 100 minimal-access insertions of distal shunt catheters in 91 patients who required ventriculoperitoneal shunting. Using the minimal-access approach, they avoided utilizing laparoscopic assistance or a mini-laparotomy in 91% of the cases. There were no bowel injuries or misplaced distal catheters. Additional outcomes in terms of operative times, cases that required conversion to open or laparoscopically assisted implantation, and infection rates are presented.
They conclude that intraperitoneal shunt catheter placement can be safely and effectively accomplished using a simplified percutaneous minimal-access insertion method that does not require direct laparoscopic visualization.
The Selective Heating of Iron Nanoparticles in a Single‐Mode Microwave for the Patterned Growths of Carbon Nanofibers and Nanotubes
Authors: Druzhinina Tamara , Weltjens Wim , Hoeppener Stephanie , Schubert Ulrich S. 
Published: March 2009

AbstractThe fast and cheap synthesis of carbon nanotubes is addressed in a large number of recent publications. At the same time, microwave‐assisted synthesis has also gained interest. Besides the fact that reaction kinetics can be positively influenced by the use of microwave irradiation and advanced reaction conditions can be applied, absorption of microwave radiation depends on the material properties, thus resulting in a selective heating mechanism. The selective heating process allows for locally created temperatures high enough to promote the growth of carbon nanofibers and nanotubes on patterned iron catalyst layers. The resulting fibers are micrometers long, and can be synthesized in short time scales of a few minutes, yielding dense films of carbon fibers with uniform height. Here, the selective heating of surface bound iron nanoparticles is investigated in more detail, and experimental evidence for this effect is provided by utilizing a self‐assembled monolayer of n‐octadecyltrichlorosilane, which acts as a sensitive indicator for locally elevated temperatures. Special emphasis is placed on the development of an improved and controllable experimental setup that permits the safe and fast fabrication of the desired carbon objects.
Respiratory symptoms and lung function in foundry workers exposed to low molecular weight isocyanates
Authors: Löfstedt Håkan , Westberg Håkan , Seldén Anders I. , Lundholm Cecilia , Svartengren Magnus 
Published: March 2009

AbstractBackgroundThis study investigated the prevalence of ocular and respiratory symptoms and lung function in foundry workers exposed to isocyanic acid (ICA) and methyl isocyanate (MIC).MethodsFoundry workers (n = 64) using the Hot Box binder technique and referents (n = 134) completed two questionnaires and a spirometry before and after a day shift. Findings were analyzed relating to exposure measurements of ICA, MIC, and formaldehyde.ResultsExposed workers reported more frequently ocular irritation and coughing. Pre‐shift lung function was lower than predicted in both groups of workers, and was not associated with exposure duration. Decrease in lung function over shift was more pronounced in exposed workers, but this was not associated with quantitative measures of the exposures.ConclusionsAn increased prevalence of ocular and respiratory symptoms, as well as a small decrease in lung function over shift, was observed among exposed workers. No associations with exposure to monoisocyanates and formaldehyde were seen, thus suggesting that other irritants in the foundry environment might be the cause. The effects seemed to be small and not clinically relevant on an individual level. Further studies using a follow‐up design may be warranted. Am. J. Ind. Med. 52:455–463, 2009. © 2009 Wiley‐Liss, Inc.
5‐(Pyrrolidin‐2‐yl)tetrazol‐katalysierte Aldol‐ und Mannich‐Reaktionen: schnellere Reaktionen und niedrigere Katalysatorbeladung in einem Durchflussreaktor
Authors: Odedra Arjan , Seeberger Peter H. 
Published: March 2009

AbstractKontinuierliche Organokatalyse: Schnelle Aldol‐ und Mannich‐Reaktionen benötigen geringere Mengen an Katalysator, wenn sie in einem Mikroreaktor durchgeführt werden. Ein Prolintetrazol‐Derivat (5–10 Mol‐%) katalysiert asymmetrische Aldolreaktionen von aromatischen Aldehyden mit Ketonen in einem Mikroreaktor bei einer Reaktionstemperatur von 60 °C in Reaktionszeiten von 10–30 min (siehe Bild).magnified image
A Preferred Disrotatory 4n Electron Möbius Aromatic Transition State for a Thermal Electrocyclic Reaction
Authors: Mauksch Michael , Tsogoeva Svetlana B. 
Published: March 2009

AbstractNicht verboten: Thermische 4n‐Elektronen‐Elektrocyclisierungen von Hückel‐Strukturen verlaufen über „erlaubte“ konrotatorische Pfade. Bei einer Möbius‐Topologie können dagegen die Woodward‐Hoffmann‐Regeln außer Kraft treten, sodass ein „verbotener“ disrotatorischer Pfad bevorzugt wird – dies zeigen theoretische Studien am Dodecahexaen 1, das über eine aromatische Heilbronner‐Möbius‐Übergangsstruktur 2 in das cyclische Polyen 3 übergeht.magnified image
A General Approach to the Synthesis of Gold–Metal Sulfide Core–Shell and Heterostructures
Authors: Sun Zhenhua , Yang Zhi , Zhou Jianhua , Yeung Man Hau , Ni Weihai , Wu Hongkai , Wang Jianfang 
Published: March 2009

AbstractHerz aus Gold: In Wasser dispergierbare Kern‐Schale‐Strukturen und ‐Heterostrukturen aus Goldnanokristallen verschiedener Form (Polyeder, Würfel und Stäbe) und vielfältigen Metallsulfid‐Halbleitern (ZnS, CdS, NiS, Ag2S und CuS) wurden ausgehend von Cetyltrimethylammoniumbromid‐beschichteten Goldnanokristallen und Metallthiobenzoaten hergestellt.magnified image
Carbanion oder Amid? Elektronendichteuntersuchung am 2‐Picolyllithium‐Stammsystem
Authors: Ott Holger , Pieper Ursula , Leusser Dirk , Flierler Ulrike , Henn Julian , Stalke Dietmar 
Published: March 2009

AbstractDie negative Ladungals Resultat der Deprotonierung der Methylgruppe wird über den 2‐Picolylring verteilt. Die aus der Elektronendichteverteilung abgeleiteten Bindungseigenschaften zeigen den Enamidcharakter von Picolyllithium (PicLi; Bild: Deformationsdichte von [2‐PicLi⋅PicH]2), wenn auch ein elektrophiler Angriff immer am deprotonierten C‐Atom erfolgt. Dies ist durch das elektrostatische Potential erklärbar, das ein Elektrophil zum nucleophilen Kohlenstoffatom dirigiert.magnified image
Iron‐Catalyzed Oxidative Heterocoupling Between Aliphatic and Aromatic Organozinc Reagents: A Novel Pathway for Functionalized Aryl–Alkyl Cross‐Coupling Reactions
Authors: Cahiez Gérard , Foulgoc Laura , Moyeux Alban 
Published: March 2009

AbstractAryl‐Alkyl‐Kupplungsprodukte sind durch die eisenkatalysierte oxidative Heterokupplung von Organozinkreagentien unter milden Bedingungen zugänglich. Diese neuartige Reaktion erlaubt die Verwendung primärer wie sekundärer aliphatischer Diorganozinkreagentien als Kupplungspartner und toleriert funktionalisierte Aryl‐ und Alkylzinkreagentien.magnified image
Supramolecular ABC Triblock Copolymers
Authors: Ambade Ashootosh V. , Yang Si Kyung , Weck Marcus 
Published: March 2009

AbstractJust add it! Ruthenium initiators functionalized with hydrogen‐bonding sites were utilized in ring‐opening metathesis polymerization to prepare heterotelechelic polymers with hydrogen‐bonding and metal‐coordination units in a single step. Supramolecular ABC triblock copolymers were then self‐assembled in one pot by simply adding complementary telechelic polymers to a solution of the heterotelechelic polymer (see picture).magnified image
Incorporation of Fe3O4 Nanoparticles into Organometallic Coordination Polymers by Nanoparticle Surface Modification
Authors: Kim Sang Bok , Cai Chen , Sun Shouheng , Sweigart Dwight A. 
Published: March 2009

AbstractSurface‐modified Fe3O4 nanoparticles (NPs) can be obtained by substituting [(η5‐semiquinone)Mn(CO)3] for oleylamine surface protecting groups. The resulting NP can function as a nucleus or template to generate crystalline coordination polymers that contain superparamagnetic Fe3O4 NPs. Hybridized magnetic properties can be obtained by introducing paramagnetic metal nodes, such as Mn2+, into the polymers (see picture).magnified image
A General Approach to the Synthesis of Gold–Metal Sulfide Core–Shell and Heterostructures
Authors: Sun Zhenhua , Yang Zhi , Zhou Jianhua , Yeung Man Hau , Ni Weihai , Wu Hongkai , Wang Jianfang 
Published: March 2009

AbstractCores and effect: Water‐dispersible core–shell structures and heterostructures incorporating gold nanocrystals of different shapes (polyhedra, cubes, and rods) and a variety of transition metal sulfide semiconductors (ZnS, CdS, NiS, Ag2S, and CuS) are synthesized using cetyltrimethylammonium bromide‐encapsulated gold nanocrystals and metal thiobenzoates as starting materials.magnified image
Carbanion or Amide? First Charge Density Study of Parent 2‐Picolyllithium
Authors: Ott Holger , Pieper Ursula , Leusser Dirk , Flierler Ulrike , Henn Julian , Stalke Dietmar 
Published: March 2009

AbstractThe negative chargeoriginating from deprotonation of the methyl group is distributed over the 2‐picolyl ring. Bonding properties derived from the electron density distribution support the enamide character of picolyllithium (PicLi; the picture shows the deformation density of [2‐PicLi⋅PicH]2), but electrophilic attack occurs at the deprotonated C atom. This reactivity is rationalized by the electrostatic potential, which guides electrophiles towards the nucleophilic C atom.magnified image
Iron‐Catalyzed Oxidative Heterocoupling Between Aliphatic and Aromatic Organozinc Reagents: A Novel Pathway for Functionalized Aryl–Alkyl Cross‐Coupling Reactions
Authors: Cahiez Gérard , Foulgoc Laura , Moyeux Alban 
Published: March 2009

AbstractAryl–alkyl cross‐coupling products are obtained by the iron‐catalyzed oxidative heterocoupling of organozinc reagents under mild conditions. This novel reaction pathway is versatile, allowing for the use of primary and secondary aliphatic diorganozinc reagents as coupling partners as well as tolerating functionalized aryl‐ and alkylzinc reagents.magnified image
Exploring the Limits of Förster Theory for Energy Transfer at a Separation of 20 Å
Authors: Ziessel Raymond , Alamiry Mohammed A. H. , Elliott Kristopher J. , Harriman Anthony 
Published: March 2009

AbstractCutting the corner: An excellent agreement has been obtained between experimental and computed coulombic coupling matrix elements for donor–spacer–acceptor systems, which consist of a boron dipyrromethane donor and acceptor in various stages of protonation. This correlation occurs in spite of reservations about the validity of Förster theory being applied to intramolecular electronic energy transfer (ET) over short (e.g., 20 Å) distances (see picture).magnified image
Metagenomics: Concept, methodology, ecological inference and recent advances
Authors: Singh Jagtar , Behal Arvind , Singla Neha , Joshi Amit , Birbian Niti , Singh Sukhdeep , Bali Vandana , Batra Navneet 
Published: March 2009

AbstractMicroorganisms constitute two third of the Earth's biological diversity. As many as 99% of the microorganisms present in certain environments cannot be cultured by standard techniques. Culture‐independent methods are required to understand the genetic diversity, population structure and ecological roles of the majority of organisms. Metagenomics is the genomic analysis of microorganisms by direct extraction and cloning of DNA from their natural environment. Protocols have been developed to capture unexplored microbial diversity to overcome the existing barriers in estimation of diversity. New screening methods have been designed to select specific functional genes within metagenomic libraries to detect novel biocatalysts as well as bioactive molecules applicable to mankind. To study the complete gene or operon clusters, various vectors including cosmid, fosmid or bacterial artificial chromosomes are being developed. Bioinformatics tools and databases have added much to the study of microbial diversity. This review describes the various methodologies and tools developed to understand the biology of uncultured microbes including bacteria, archaea and viruses through metagenomic analysis.
High‐throughput system for determining dissolution kinetics of inclusion bodies
Authors: Dürauer Astrid , Mayer Sabrina , Sprinzl Wolfgang , Jungbauer Alois , Hahn Rainer 
Published: March 2009

AbstractEfficient solubilization is a crucial step during inclusion body processing and dissolving conditions were usually empirically established. Here we describe a new methodology for rapid screening of solubilization conditions and evaluation of dissolution kinetics in microtiter plates. Increase of protein in solution over time was directly related to decrease of turbidity measured by absorbance at 600 nm. Dissolution kinetics of inclusion bodies were described by a first‐order reaction kinetics, which was used for drug dissolution modeling. Reaction constants were in the range of 0.01–0.03 s–1 for buffer conditions providing sufficient solubilization power. This method is not limited to the screening of optimal buffer conditions for solubilization and can be applied for studying other parameters involved in the solubility of IBs, such as pI of the protein, influence of fermentation conditions, influence of initial protein concentration, and more.
SCL‐LCL‐PHA copolymer production by a local isolate,Pseudomonas aeruginosaMTCC 7925
Authors: Singh Akhilesh Kumar , Mallick Nirupama 
Published: March 2009

AbstractA five‐level‐four‐factor central composite rotary design (CCRD) was employed in combination with response surface methodology (RSM) to optimize the process variables for the production of a novel copolymer consisting of short‐chain‐length (SCL) and long‐chain‐length (LCL) PHA units,i.e., P(3HB‐3HV‐3HHD‐3HOD) copolymer inPseudomonas aeruginosaMTCC 7925. The four variables involved in this study were ethanol, glucose, ammonium nitrate (NH4NO3), and potassium dihydrogen phosphate (KH2PO4). A second‐order polynomial equation was obtained by multiple regression analysis using RSM. The statistical analyses of the results showed that all the four variables had significant impact on the copolymer yield. The model predicted a maximum yield of 81.1% of dry cell weight (dcw) on setting the concentrations of ethanol and glucose at 1.5 and 1.1%, and KH2PO4and NH4NO3at 2.79 and 1.86 g/L, respectively. Verification of the predicted value resulted into a yield of 77.6% (dcw). This novel copolymer exhibited comparable material properties with polypropylene (PP) and low density polyethylene (LDPE), thus advocating its potential applications in various fields.
Identification of a Highly Efficient Alkylated Pincer Thioimido–Palladium(II) Complex as the Active Catalyst in Negishi Coupling
Authors: Liu Jing , Wang Haibo , Zhang Heng , Wu Xiaojun , Zhang Hua , Deng Yi , Yang Zhen , Lei Aiwen 
Published: March 2009

AbstractPdII ate complex: A novel alkylated pincer thioimido–Pd complex generated from a catalyst precursor and basic organometallic reagents (RM) was observed by in situ IR, 1H NMR, and 13C NMR spectroscopies for the first time and proved to be the active catalyst in stoichiometric and catalytic reactions of aryl iodides with RM (see scheme). The catalyst, as an electron‐rich PdII species, promoted the Negishi coupling of aryl iodides and alkylzinc reagents with high efficiency, even at low temperatures (0 or −20 °C).magnified imageThe induction period of Negishi coupling catalyzed by pincer thioamide–palladium complex 1 was investigated. A heterogeneous mechanism was excluded by kinetic studies and comparison with Negishi coupling reactions promoted by Pd(OAc)2/Bu4NBr (a palladium–nanoparticle system). Tetramer 2 was isolated from the reaction of 1 and organozinc reagents. Dissociation of complex 2 by PPh3 was achieved, and the structure of resultant complex 8 was confirmed by X‐ray diffraction analysis. A novel alkylated pincer thioimido–PdII complex, 7, generated from catalyst precursor 1 and basic organometallic reagents (RM), was observed by in situ IR, 1H NMR, and 13C NMR spectroscopy for the first time. The reaction of 7 with methyl 2‐iodobenzoate afforded 74 % of the cross‐coupled product, methyl 2‐methylbenzoate, together with 60 % of PdII complex 2. Furthermore, the catalyst, as an electron‐rich PdII species, efficiently promoted the Negishi coupling of aryl iodides and alkylzinc reagents without an induction period, even at low temperatures (0 °C or −20 °C). To evaluate the influence of the catalyst structure upon the induction period, complex 9 was prepared, in which the nBu groups of 1 were displaced by more bulky 1,3,5‐trimethylphenyl groups. Trimer 10 was isolated from the reaction of complex 9 and basic organometallic reagents such as CyZnCl or CyMgCl (Cy: cyclohexyl); this is consistent with the result obtained with complex 1. The rate in the induction period of the model reaction catalyzed by 9 was faster than that with 1. Plausible catalytic cycles for the reaction, based upon the experimental results, are discussed.
Determination of the Catalytic Pathway of a Manganese Arginase Enzyme Through Density Functional Investigation
Authors: Leopoldini Monica , Russo Nino , Toscano Marirosa 
Published: March 2009

AbstractThe catalytic mechanism of dimanganese‐containing arginase enzyme has been investigated by DFT calculations. Two exchange‐correlation functionals, B3 LYP and MPWB1 K, have been used to construct the potential energy profiles for the hydrolysis of an arginine substrate performed by an arginase active site model system. Two reaction mechanisms have been investigated, one involving a water molecule (mechanism 1) and the other involving a hydroxide ion (mechanism 2) as nucleophilic agent. Results obtained in the gas phase and in the protein environment have indicated that mechanism 1 involving a water molecule entails structural features as well as an activation energy for the rate‐determining step that are inconsistent with experimental data available for the arginase enzyme. On the other hand, when a hydroxide ion is present at the Mn2 site, a lower activation energy and a structural arrangement closer to the experimental indication are obtained.
Well‐Defined Silica‐Supported Calcium Reagents: Control of Schlenk Equilibrium by Grafting
Authors: Gauvin Régis M. , Buch Frank , Delevoye Laurent , Harder Sjoerd 
Published: March 2009

AbstractBound to stay heteroleptic: Grafting of homoleptic benzyl and amide calcium reagents onto silica affords well‐defined supported heteroleptic species, catalytically active in hydrosilylation, hydroamination, and styrene polymerization. The fact that attempts to generate a molecular model were thwarted by the Schlenk equilibrium affording the homoleptic compound (see scheme) emphasizes the importance of immobilization as an approach for the syntheses of heteroleptic calcium complexes.magnified imageCalcium reagents Ca(α‐Me3Si‐2‐Me2N‐benzyl)2⋅2 thf (1) and Ca[N(SiMe3)2]2⋅2 thf (2) reacted with silica partially dehydroxylated at 700 °C to afford materials that bear (SiO)Ca(α‐Me3Si‐2‐Me2N‐benzyl)⋅1.6 thf (SiO2‐1) and (SiO)Ca [N(SiMe3)2]⋅1.3 thf (SiO2‐2) fragments, respectively. Due to the bulk of the supported complexes, the silanol groups are only partially metalated: 50 % in SiO2‐1 and 70 % in SiO2‐2. In the case of SiO2‐2, a parallel SiMe3‐capping side reaction affords in fine a silanol‐free surface. The materials were characterized by IR spectroscopy, 1D and 2D solid‐state high‐field NMR spectroscopy, and elemental analysis. Reaction of 2 with one equivalent of the bulky silanol (tBuO)3SiOH, a silica‐surface mimic, afforded the homoleptic bis‐silyloxide calcium derivative through ligand exchange (Schlenk equilibrium), and a derivative was isolated and structurally characterized. Preliminary studies have shown that both grafted benzyl and amide derivatives are active in olefin hydrosilylation, intramolecular hydroamination, and styrene polymerization, with evidence showing that catalysis occurs through supported species. In styrene polymerization, a marked influence of the surface acting as a ligand on the stereoselectivity of the reaction was observed, as syndiotactic‐rich polystyrene (88 % of r diads) was obtained. These results illustrate that grafting of calcium benzyl or amide compounds on a silica surface is a new concept to prevent ligand exchange through the Schlenk equilibrium. Heteroleptic calcium complexes that cannot be synthesized as stable molecular species in solution can be obtained as silica‐supported species which have been shown to be catalytically active.