bluuebunny/crossref_metadata_2025 huggingface dataset:
Sustainability of Biobased and Biodegradable Plastics
Authors: Sudesh Kumar , Iwata Tadahisa
Published: June 2008

Advances in science and technology have resulted in the rapid development of modern society, which is clearly unsustainable because of the strain it places on current resources. The energy and materials needed to sustain the present society are derived primarily from non‐renewable fossil resources, which will be depleted at some point. Plastics are one example of an important commodity in the modern lifestyle. While plastics are undoubtedly superior materials in terms of their costs, processability and functional properties, they are currently derived from fossil resources and they are not readily assimilated by the various ecosystems upon disposal. The search for biodegradable plastics that are derived from renewable resources has been ongoing since the 1970s. Two of the most promising biobased plastics, i. e., polylactic acid and polyhydroxyalkanoates, have received much attention as potential alternatives to existing processes. This article will discuss the current status and sustainability of these two next generation biobased plastics by taking into consideration the raw materials required, as well as the post‐consumption effects of these materials on the environment. In addition, important issues surrounding the development and sustainability of biobased and biodegradable plastics will be highlighted.
Study on Ammonia‐Nitrogen and Humic Acid Removal Using Aluminum Oxide Molecular Sieve and Modified Clinoptilolite
Authors: Liu Chen , Wu Xin‐Wu , Bao Zhi‐Yu , Dong Yan‐Mao
Published: June 2008

The removal of ammonia‐nitrogen (NH4+–N) and humic acid (HA) in water by aluminum oxide molecular sieve (AOMS)/modified clinoptilolite (MC) was investigated using a flow system. The study focuses on the effect of AOMS on the removal of NH4+–N and HA. The dependence of ion‐exchange of MC on the organic contaminants was also investigated. The results show that the NH4+–N is difficult to remove by AOMS only. However, the effective removal of HA by AOMS brings about a higher efficiency of NH4+–N removal by AOMS‐MC, so that the NH4+–N and HA are removed simultaneously.
Environmental Conflicts and Activism with Industrialization in South Korea
Authors: Kim Jung Wk
Published: June 2008

When South Korea launched the first 5‐year economic development plan in 1962 to industrialize Korea, little attention was given to the environment. The industrialization process has been successful and as a result, the quality of the environment has been continually deteriorating in South Korea resulting in numerous environmental conflicts. The earliest environmental activism that arose was the struggles of the inhabitants in industrial complexes for survival. The government removed inhabitants from the affected areas instead of solving the root causes of the environmental problems. The activism began to disperse into areas surrounding metropolitan cities and industrial areas and even into rural areas as environmentally‐susceptible facilities such as nuclear waste repositories and landfills, which often resulted in violent riots. The environmental conflicts have been aggravated since numerous construction projects have boomed in the country. In particular, the so‐called National Policy Projects such as large‐scale reclamation as well as dam and road construction brought forth nationwide environmental conflicts and activism. Such conflicts often resulted in the breakdown of communities as well as serious economic loss to their inhabitants. Most of these conflicts share common causes, i. e., undemocratic processes in decision making, lack of fair impact assessment procedures, and severe economic loss to the local inhabitants. All of the processes used to resolve the conflicts, e. g., negotiation, mediation, arbitration, and ultimately lawsuits have been painful and costly. Transparency and democracy in the decision‐making process and the fairness in impact assessment are essential to prevent such conflicts or to resolve them. In addition, the voice of the minority victims should not be ignored. In order to ensure this, sustainable governance building is necessary incorporating the government, corporations and citizens. Sustainable development is the key issue to help prevent environmental conflicts arising. There have been positive aspects of the environmental activism, e. g., through the activism, the communities have been strengthened, environmental awareness has risen and social capital has built up.
Air Pollution and Urban Air Quality Management in Indonesia
Authors: Santosa Sri Juari , Okuda Tomoaki , Tanaka Shigeru
Published: June 2008

The trade‐led industry and economic development after the Asian financial crisis a decade ago has been accelerated in Indonesia to improve the quality of life of its population. This rapid development of Indonesia was in fact heavily fueled by fossil fuels, especially oil, followed by natural gas and coal. The exploitation of fossil fuel in fueling the development resulted in significant environmental quality degradation. Air pollution is perhaps Indonesia's most severe environmental problem. Industry and transportation were the typical main sources of urban air pollutants. Moreover, Indonesia also failed to reach its original 2005 target for a complete phase‐out of leaded gasoline. As a result, the level of Pb together with other pollutants such as CO, NOx, SO2, and total suspended particulates has exceeded or at least approached the designated ambient air quality standards. The urban air pollution will not be lesser in extent, but surely will be more severe in the future. Unfortunately, the capability of the Indonesian authorities to manage the urban air quality is still very limited and the portion of the budget allocated to the improvement of urban air quality is still remarkably low, typically 1% of total. This is why the efforts to enhance the capability to manage the urban air quality could not be handled by the environmental authorities in Indonesia's cities themselves, but outside stimulation in the form of man power, consultant and equipment assistance along with financial support has been very important.
Palm Oil Boom in Indonesia: From Plantation to Downstream Products and Biodiesel
Authors: Santosa Sri Juari
Published: June 2008

Indonesia has been the biggest producer of palm oil (PO) in the world since 2005. The total production in 2007 was 17.0 and 1.9 million tons of crude palm oil (CPO) and crude palm kernel oil (CPKO), respectively. More than 70% of the CPO was exported and 87% of the domestic consumption was used for food. The production and subsequent refining and fractionation of CPO and CPKO generated biomass by‐products that consists of trunk, frond, empty fruit bunch (EFB), fiber, shell, and palm kernel meal (PKM), and discharged wastes of palm oil mill effluent (POME) as well as palm fatty acid distillate (PFAD). The amount of by‐products and wastes produced has been growing very rapidly and efforts to diversify and improve their utilization are a great challenge. As claimed in many research reports, the by‐products and wastes could be potentially utilized as sources of energy, animal feed, chemicals, paper pulp, advanced materials, medicines and food ingredients. A more important role may be played by PO as the Indonesian Government took further steps in 2006 to become the world's largest producer of biodiesel. As a starting point, Presidential Instruction No. 1/2006 for the Production and Use of Biofuel as Alternative Fuel was issued in January 2006. Responding to this Presidential Instruction, at least 15 companies are planning to establish new larger biodiesel refineries to enhance the currently produced 82.5 million L of biodiesel. It is planned to start production in 2008/2009 with two new refineries that have a total capacity of ca. 1,600 million L/year.
Electrogenerative Processes for Environmental Applications
Authors: Yap Chin Yean , Mohamed Norita
Published: June 2008

The applications of electrogenerative processes which could be an alternative to current environmental treatment technologies are briefly reviewed. This process does not require an external supply of energy due to the spontaneous chemical reaction that takes place in the reactor and generates an external flow of current as a by‐product. The operation is attractive in reducing operational costs, especially when dealing with solutions of low ion concentrations. Electrogenerative reactors which can be operated in various configurations and their designs are described. The rate and selectivity for particular reactions can be controlled by varying electrode potentials and with suitable choices of electrodes. This review paper aims to invoke the interest of industries to consider the merits of electrogenerative processes as a replacement for the current processes and practices. The applications of electrogenerative processes to the removal and recovery of metal ions, electrosynthesis of organic chemicals and leaching of sulfide minerals are discussed.
Fabrication of Pt/TiO2 Nanocomposites in Alginate and Their Applications to the Degradation of Phenol and Methylene Blue in Aqueous Solutions
Authors: Chen Peng , Zhang Xiaogang
Published: June 2008

New Pt‐containing titania composites have been produced by a conducting sol‐gel method within Pt/alginate hydrogels. The alginate gel was used as a template to prevent the conglomeration of the inorganic materials. During the calcination process, the Pt nanoparticles, which had been loaded in the alginate porous networks were transferred to the titania system, and formed the Pt/TiO2 composites. The amount of Pt embedded was studied from 0 to 0.74 mol.‐% (where mol.‐% refers to the Pt/TiO2 molar ratio), and the morphology and structure of the Pt/TiO2 composites were characterized by SEM, TEM, HAADF‐STEM, XPS, XRD, in addition to a study of the photocatalytic efficiency of these composites in aqueous methylene blue and phenol. Higher photocatalytic activity was observed at higher levels of Pt added to the titania system. The 0.37 mol.‐% sample was found to present the highest photocatalytic activity for the photodecomposition of aqueous methylene blue and phenol.
Enhancement of Methanol Tolerance in DMFC Cathode: Addition of Chloride Ions
Authors: Uhm Sunghyun , Noh Taegeun , Kim Yong Dok , Lee Jaeyoung
Published: June 2008

In the operation of a direct methanol fuel cell, the modification by chloride ions on the surface of a Pt cathode can facilitate the extraordinary increase of power performance and long‐term stability. Analyzing the results of cyclic voltammograms and electrochemical impedance spectroscopy, the positive shift of Pt oxidation onset potential and the depression of oxidation current are observed, which results from the role of chloride as surface inhibitor. In addition, O2 temperature‐programmed desorption and X‐ray photoelectron spectroscopy also reveal that the suppression of Pt surface oxide can be best understood in terms of lower binding of oxygen species by the alteration of electronic state of Pt atoms. Such a reduced surface oxide formation not only provides more efficient proton adsorption sites with high selectivity but also decreases the mixed potential by crossover methanol, resulting in higher performance and stability even under high voltage long‐term operation.
Fabrication of Stable Polyaniline Foams and Their Photoelectric Conversion Behaviors
Authors: Heng Liping , Wang Xinyi , Zhai Jin , Sun Zhongwei , Jiang Lei
Published: June 2008

We report a foaming‐polymerization method to prepare stable polyaniline (PANI)/polyvinyl alcohol (PVA) foams. The formation mechanism of the foam materials is investigated and the photoelectric conversion properties of PANI/PVA foams are studied in detail. The enhancement of photoelectric conversion behavior in foams is achieved, which has potential application in solar cells and nano‐electronics devices.
Effect of the Solvent on the Conformation of Isolated MEH‐PPV Chains Intercalated Into SnS2
Authors: Aharon Eyal , Breuer Steffen , Jaiser Frank , Köhler Anna , Frey Gitti L.
Published: June 2008

Photophysical processes in conjugated polymers are influenced by two competing effects: the extent of excited state delocalization along a chain, and the electronic interaction between chains. Experimentally, it is often difficult to separate the two because both are controlled by chain conformation. Here we demonstrate that it is possible to modify intra‐chain delocalization without inducing inter‐chain interactions by intercalating polymer monolayers between the sheets of an inorganic layered matrix. The red‐emitting conjugated polymer, MEH‐PPV, is confined to the interlayer space of layered SnS2. The formation of isolated polymer monolayers between the SnS2 sheets is confirmed by X‐ray diffraction measurements. Photoluminescence excitation (PLE) and photoluminescence (PL) spectra of the incorporated MEH‐PPV chains reveal that the morphology of the incorporated chains can be varied through the choice of solvent used for chain intercalation. Incorporation from chloroform results in more extended conformations compared to intercalation from xylene. Even highly twisted conformations can be achieved when the incorporation occurs from a methanol:chloroform mixture. The PL spectra of the MEH‐PPV incorporated SnS2 nanocomposites using the different solvents are in good agreement with the PL spectra of the same solutions, indicating that the conformation of the polymer chains in the solutions is retained upon intercalation into the inorganic host. Therefore, intercalation of conjugated polymer chains into layered hosts enables the study of intra‐chain photophysical processes as a function of chain conformation.
Comparison of the Electrochemical and Luminescence Properties of Two Carbazole‐Based Phosphine Oxide EuIII Complexes: Effect of Different Bipolar Ligand Structures
Authors: Xu Hui , Yin Kun , Huang Wei
Published: June 2008

The photoluminescence (PL), electrochemical, and electroluminescence (EL) properties of EuIII complexes, [Eu(cppo)2(tta)3] (1) and [Eu(cpo)2(tta)3] (2; TTA=2‐thenoyltrifluoroacetonate) with two carbazole‐based phosphine oxide ligands, 9‐[4‐(diphenylphosphinoyl)phenyl]‐9H‐carbazole (CPPO) and 9‐(diphenylphosphoryl)‐9H‐carbazole (CPO), which have different bipolar structures, donor–π‐spacer–acceptor (D–π–A) or donor–acceptor (D–A) systems respectively, are investigated. The CPPO with D–π–A architecture has improved PL properties, such as higher PL efficiency and more efficient intramolecular energy transfer, than CPO with the D–A architecture. Gaussian simulation proved the bipolar structures and the double‐carrier injection ability of the ligands. The carrier injection abilities of triphenylphosphine oxide, CPO, and CPPO are gradually improved. Notably, the Gaussian and electrochemical investigations indicate that before and after coordination, the carrier injection ability of the ligands show remarkable changes because of the particularity of the D‐π–A and D–A systems. The electrochemical studies demonstrate that coordination induces the electron cloud to migrate from electron‐rich carbazole to electron‐poor diphenylphosphine oxide, and consequently increases the electron‐cloud density on diphenylphosphine oxide, which weakens its ability for electron affinity and induces the elevation of LUMO energy levels of the complexes. Significantly, the π‐spacer in the D–π–A system exhibits a distinct buffer effect on the variation of the electron‐cloud density distribution of the ligand, which is absent in the D–A system. It is demonstrated that the adaptability of the D–π–A systems, especially for coordination, is stronger than that of D–A systems, which facilitates the modification of the complexes by designing multifunctional ligands purposefully. 1 seems favorable as the most efficient electroluminescent EuIII complex with greater brightness, higher efficiencies, and more stable EL spectra than 2. These investigations demonstrate that the phosphine oxide ligands with D–π–A architecture are more appropriate than those with D–A architecture to achieve multifunctional electroluminescent EuIII complexes.
First and Second Proton Affinities of Carbon Bases
Authors: Tonner Ralf , Heydenrych Greta , Frenking Gernot
Published: June 2008

Quantum chemical calculations at the MP2/TZVPP//BP86/SVP level are reported for the first and second proton affinities (PAs) of divalent carbon‐donor molecules. The molecules investigated are imidazol‐2‐ylidenes (“normal” NHCs) and the tautomeric imidazol‐4/5‐ylidenes (“abnormal” NHCs). PAs are also calculated for acyclic and cyclic carbodiphosphoranes, carbophosphoranesulfide, unsaturated and saturated carbodicarbenes, tetraaminoallenes and carbon suboxide. The results are discussed in terms of divalent carbon(II) compounds (carbenes) CR2, which have one lone electron pair at carbon, and carbon(0) compounds CL2, which have two lone pairs at carbon and two C←L donor–acceptor bonds. Divalent C(0) compounds (carbones) not only have very high first PAs, but the second PA is also large and strong enough to isolate doubly protonated C(0) species as salts in a condensed phase. The first PA of divalent carbon(II) compounds (carbenes) are also large. However, they have much smaller second PAs than the divalent carbon(0) compounds. The divalent C(0) character of a compound is not always obvious when the bonding situation in the equilibrium geometry is considered. This is the case, for example, for tetraaminoallenes (TAAs). Protonation of TAAs changes the bonding situation of the central moiety from doubly bonded (R2N)2CCC(NR2)2 to a donor–acceptor description (R2N)2C→C(H+)n←C(NR2) [n=1, 2]. The atomic partial charge at the carbon donor atom does not correlate with the PA and the trend of the second PA may be quite different from the trend of the first. The trends of the first and second PA correlates quite well with the eigenvalues of the highest‐lying carbon lone‐pair orbitals.
Chemical Engineering Challenges and Investment Opportunities in Sustainable Energy
Authors: Heller Adam
Published: June 2008

The chemical and energy industries are transforming as they adjust to the new era of high‐priced petroleum and severe global warming. As a result of the transformation, engineering challenges and investment opportunities abound. Rapid evolution and fast growth are expected in cathode and anode materials as well as polymeric electrolytes for vehicular batteries and in high‐performance polymer–ceramic composites for wind turbines, fuel‐efficient aircraft, and lighter and safer cars. Unique process‐engineering opportunities exist in sand‐oil, coal, and possibly also shale liquefaction to produce transportation fuel; and also in genetic engineering of photosynthesizing plants and other organisms for their processing into high‐performance biodegradable polymers and high‐value‐added environmentally friendly chemicals. Also, research on the feasibility of mitigation of global warming through enhancement of CO2 uptake by the southern oceans by fertilization with trace amounts of iron is progressing. Because chemical engineers are uniquely well trained in mathematical modeling of mass transport, flow, and mixing, and also in cost analysis, they are likely to join the oceanographers and marine biologists in this important endeavor.
Toward an autonomous platform for spatio‐temporal EEG‐signal analysis based on cellular nonlinear networks
Authors: Gollas Frank , Niederhöfer Christian , Tetzlaff Ronald
Published: June 2008

Although in the field of epileptic seizure prediction many spatio‐temporal approaches have been carried out, the precursor detection problem remains unsolved up to now. It can be observed that an increasing number of algorithms are developed based on cellular nonlinear networks (CNNs). They are dealing with the extraction of signal features using intracranial EEG recordings in order to detect possible preseizure states. In general, reliable precursor detections cannot be obtained for all treated cases. The performance of these algorithms can be enhanced by adapting them to specific patients. Combining different features in a feature vector in a future seizure anticipation platform may lead to a reliably working seizure prediction system.

In this contribution we focus on two different CNN‐based algorithms—a nonlinear identification approach and a prediction algorithm. They will be discussed in detail and recently obtained results will be given. Copyright © 2008 John Wiley & Sons, Ltd.
Performance evaluation of CSMA/ID MAC protocol for IP over WDM ring networks
Authors: Ho Jih‐Hsin , Chen Wen‐Ping , Hwang Wen‐Shyang , Shieh Ce‐Kuen
Published: June 2008

In this paper, a packet pre‐classification media access control protocol based on a carrier sense multiple access with idle detection (CSMA/ID) scheme is investigated for supporting IP packets over all‐optical WDM ring networks. The purpose of the protocol is to increase throughput and to decrease the packet transmission delay of IP packets over optical networks in a metropolitan area network. This protocol avoids both packet collision and packet fragmentation. In order to improve the utilization of the network, the packets transmitted from a local area network are first pre‐classified into various class queues of an access point (AP) according to their length. After checking the available space based on the wavelength received by the receivers of the AP, the packets in the queues are transmitted. An analytical model is developed to evaluate the performance of the protocol, with simulation results showing good network efficiency. The proposed network has short‐term variations that introduce unfairness conditions. This problem could be overcome by assigning a quota on individual queues to allow all queues fair access. Copyright © 2008 John Wiley & Sons, Ltd.
Low complexity bit allocation algorithm for OFDM systems
Authors: Lee Changwook , Jeon Gi J.
Published: June 2008

A bit allocation algorithm is presented for orthogonal frequency division multiplexing (OFDM) systems. The proposed algorithm is derived from the geometric progression of the additional transmission power required by the subcarriers and the arithmetic–geometric means inequality. Consequently, this algorithm has a simple procedure and low computational complexity. Copyright © 2008 John Wiley & Sons, Ltd.
Apoptotic cell death, long‐term persistence, and neuronal differentiation of aneuploid cells generated in the adult brain of teleost fish
Authors: Rajendran R. Samuel , Wellbrock Ursula M. , Zupanc Günther K.H.
Published: June 2008

Aneuploidy, caused by segregation defects during mitosis, has previously been identified in adult‐born cells of mammals and teleosts. In the present study, we have examined the fate of these cells in the brain of the teleost fish Apteronotus leptorhynchus. By immunostaining against active caspase‐3, we have shown that both cells with normal nuclear morphology and cells with mitotic segregation defects undergo apoptosis, but the relative number of apoptotic cells is higher among cells of the latter category. Long‐term survival of cells with mitotic segregation defects could be demonstrated by incorporation of 5‐bromo‐2′‐deoxyuridine into newly synthesized DNA during the S‐phase of mitosis, and by employment of postadministration survival times of up to 860 days. Moreover, by combining 5‐bromo‐2′‐deoxyuridine immunolabeling with immunostaining against the neuron‐specific marker protein Hu, we have shown that among the long‐term persistent cells with mitotic segregation defects a similar portion develops into neurons as does among the long‐term persistent cells without such defects. It is possible that aneuploid cells play a role in the regulation of gene expression by somatic genomic alterations during postnatal development. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
A subset of signal transduction pathways is required for hippocampal growth cone collapse induced by ephrin‐A5
Authors: Yue Xin , Dreyfus Cheryl , Kong Tony Ah‐Ng , Zhou Renping
Published: June 2008

The Eph family tyrosine kinase receptors and their ligands, ephrins, play key roles in a wide variety of physiological and pathological processes including tissue patterning, angiogenesis, bone development, carcinogenesis, axon guidance, and neural plasticity. However, the signaling mechanisms underlying these diverse functions of Eph receptors have not been well understood. In this study, effects of Eph receptor activation on several important signal transduction pathways are examined. In addition, the roles of these pathways in ephrin‐A5‐induced growth cone collapse were assessed with a combination of biochemical analyses, pharmacological inhibition, and overexpression of dominant‐negative and constitutively active mutants. These analyses showed that ephrin‐A5 inhibits Erk activity but activates c‐Jun N‐terminal kinase. However, regulation of these two pathways is not required for ephrin‐A5‐induced growth cone collapse in hippocampal neurons. Artificial Erk activation by expression of constitutively active Mek1 and B‐Raf failed to block ephrin‐A5 effects on growth cones, and inhibitors of the Erk pathway also failed to inhibit collapse by ephrin‐A5. Inhibition of JNK had no effects on ephrin‐A5‐induced growth cone collapse either. In addition, inhibitors to PKA and PI3‐K showed no effects on ephrin‐A5‐induced growth cone collapse. However, pharmacological blockade of phosphotyrosine phosphatase activity, the Src family kinases, cGMP‐dependent protein kinase, and myosin light chain kinase significantly inhibited ephrin‐A5‐induced growth cone collapse. These observations indicate that only a subset of signal transduction pathways is required for ephrin‐A5‐induced growth cone collapse. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
The role of cell death in sexually dimorphic muscle development: Male‐specific muscles are retained in female bax/bak knockout mice
Authors: Jacob Dena A. , Ray Theresa , Bengston C. Lynn , Lindsten Tullia , Wu Junmin , Thompson Craig B. , Forger Nancy G.
Published: June 2008

The bulbocavernosus (BC) and levator ani (LA) muscles are present in males but absent or severely reduced in females, and the fate of these muscles controls the survival of motoneurons in the sexually dimorphic spinal nucleus of the bulbocavernosus. However, the mechanism underlying the sex difference in BC and LA development has been controversial. We examined the role of cell death in sexual differentiation of the bulbocavernosus BC/LA muscles in mice. Muscle development was mapped from embryonic day 16 (E16) to postnatal day 5 (P5). A sex difference (male > female) first arose on E17 (BC) or E18 (LA), and increased in magnitude postnatally. TUNEL labeling revealed dying cells in the BC and LA muscles of both sexes perinatally. However, females had a significantly higher density of TUNEL‐positive cells than did males. A role for the proapoptotic factors, Bax and Bak, in BC/LA development was tested by examining mice lacking one or both of these proteins. In females lacking either Bax or Bak, the BC was absent and the LA rudimentary. Deletion of both bax and bak genes, however, rescued the BC, increased LA size ∼20‐fold relative to controls, and virtually eliminated TUNEL‐positive cells in both muscles. We conclude that cell death plays an essential role in sexual differentiation of the BC/LA muscles. The presence of either Bax or Bak is sufficient for cell death in the BC/LA, whereas the absence of both prevents sexually dimorphic muscle cell death. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008.
Organometallic Access to Intermetallic θ‐CuE2 (E = Al, Ga) and Cu1–xAlx Phases
Authors: Cokoja Mirza , Jagirdar Balaji R. , Parala Harish , Birkner Alexander , Fischer Roland A.
Published: June 2008

In this work, we compare different precursor approaches for the mild decomposition to copper–aluminum and –gallium powder materials in nonaqueous solution. Referring to previous work on the preparation of Cu–Al alloy materials from [(AlCp*)4] and [CpCu(PMe3)], the amine‐stabilized metal trihydrides [(Me3N)AlH3] and [(quinuclidine)GaH3] were used as alternative sources for Al and Ga. In a comparative study, [(Me3N)AlH3] and [(AlCp*)4] were treated with the Cu precursors [CpCu(PMe3)] and [{Cu(mesityl)}5] in mesitylene solution in various molar ratios at 150 °C and 3 bar H2 to give metallic precipitates of the composition Cu1–xAlx (x = 0.67, 0.50, 0.31). Whereas the combination [(AlCp*)4] with [{Cu(mesityl)}5] did not yield an intermetallic phase, all other Cu/Al precursor combinations led to alloyed Cu–Al materials. For x = 0.67, the θ‐CuAl2 phase formed, as shown by X‐ray powder diffraction (XRD) and solid‐state magic‐angle‐spinning (MAS)NMR spectroscopic studies. Similarly, the reaction of [{Cu(mesityl)}5] with [(quinuclidine)GaH3] immediately led to the precipitation of a gray powder, without the addition of hydrogen. The powder was identified by means of XRD as θ‐CuGa2. At x = 0.50 and below, the reactions were less phase selective depending on the precursor combination. [CpCu(PMe3)] combined with both Al precursors afforded a mixture of several Cu–Al phases, whereas [{Cu(mesityl)}5] was treated with [(Me3N)AlH3] to yield a material whose X‐ray signature was assigned to the monoclinic Cu0.51Al0.49 phase. The γ‐Cu9Al4 phase could not be obtained from [CpCu(PMe3)]; instead, solid solutions of α‐Cu were obtained. The treatment of [{Cu(mesityl)}5] with [(Me3N)AlH3] in the Cu/Al molar ratio of 9:4 (x = 0.31) gave a gray powder, which could be identified by XRD as γ‐Cu9Al4.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Anion‐Directed Template Synthesis and Hydrolysis of Mono‐Condensed Schiff Base of 1,3‐Pentanediamine and o‐Hydroxyacetophenone in NiII and CuII Complexes
Authors: Mukherjee Pampa , Drew Michael G. B. , Ghosh Ashutosh
Published: June 2008

Bis(o‐hydroxyacetophenone)nickel(II) dihydrate, on reaction with 1,3‐pentanediamine, yields a bis‐chelate complex [NiL2]·2H2O (1) of mono‐condensed tridentate Schiff baseligand HL {2‐[1‐(3‐aminopentylimino)ethyl]phenol}. The Schiff base has been freed from the complex by precipitating the NiII as a dimethylglyoximato complex. HL reacts smoothly with Ni(SCN)2·4H2O furnishing the complex [NiL(NCS)] (2) and with CuCl2·2H2O in the presence of NaN3 or NH4SCN producing [CuL(N3)]2 (3) or [CuL(NCS)] (4). On the other hand, upon reaction with Cu(ClO4)2·6H2O and Cu(NO3)2·3H2O, the Schiff base undergoes hydrolysis to yield ternary complexes [Cu(hap)(pn)(H2O)]ClO4 (5) and [Cu(hap)(pn)(H2O)]NO3 (6), respectively (Hhap = o‐hydroxyacetophenone and pn = 1,3‐pentanediamine). The ligand HL undergoes hydrolysis also on reaction with Ni(ClO4)2·6H2O or Ni(NO3)2·6H2O to yield [Ni(hap)2] (7). The structures of the complexes 2, 3, 5, 6, and 7 have been confirmed by single‐crystal X‐ray analysis. In complex 2, NiII possesses square‐planar geometry, being coordinated by the tridentate mono‐negative Schiff base, L and the isothiocyanate group. The coordination environment around CuII in complex 3 is very similar to that in complex 2 but here two units are joined together by end‐on, axial‐equatorial azide bridges to result in a dimer in which the geometry around CuII is square pyramidal. In both 5 and 6, the CuII atoms display the square‐pyramidal environment; the equatorial sites being coordinated by the two amine groups of 1,3‐pentanediamine and two oxygen atoms of o‐hydroxyacetophenone. The axial site is coordinated by a water molecule. Complex 7 is a square‐planar complex with the Ni atom bonded to four oxygen atoms from two hap moieties. The mononuclear units of 2 and dinuclear units of 3 are linked by strong hydrogen bonds to form a one‐dimensional network. The mononuclear units of 5 and 6 are joined together to form a dimer by very strong hydrogen bonds through the coordinated water molecule. These dimers are further involved in hydrogen bonding with the respective counteranions to form 2‐D net‐like open frameworks. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Lanthanide Complexes and Quantum Dots: A Bright Wedding for Resonance Energy Transfer
Authors: Charbonnière Loïc J. , Hildebrandt Niko
Published: June 2008

In this microreview we describe the principle of Förster resonance energy transfer (FRET) occurring between closely spaced energy‐donor and ‐acceptor molecules. The theoretical treatment is depicted in relation with the data extractable from spectroscopic measurements. We present the specific case of semiconductor nanocrystals (or quantum dots – QDs) as energy donors in FRET experiments and a particular emphasis is put on the specific advantages of these fluorophores with regard to both their exceptional photophysical properties and their nanoscopic morphology. In a following section, the special attributes of luminescent lanthanide complexes (LLCs) are outlined with illustrations of properties such as their characteristic emission spectra, long‐lived luminescence, and large “Stokes shift”. Finally, the successful combination of LLCs and QDs in FRET experiments is demonstrated, showing the unrivaled benefits of this singular marriage, opening doors for energy transfer at very large distances and excellent sensitivity of detection within the frame of time‐resolved fluoroimmunoassays.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
The Synthesis of Ruthenium and Rhodium Complexes with Functionalized N‐Heterocyclic Carbenes and Their Use in Solid Phase Peptide Synthesis
Authors: Lemke Jessica , Metzler‐Nolte Nils
Published: June 2008

While N‐heterocyclic carbenes (NHCs) are ubiquitous ligands in catalysts for organic or industrial synthesis, their potential to form stable transition metal complexes has hardly been exploited in metal bioconjugates. In this work, we describe a straightforward synthesis of carboxylato‐functionalized imidazolium salts for covalent binding to peptides. Carbene complexes of Ru and Rh were prepared from these imidazolium salts using Ag2O, followed by transmetallation. The neuropeptide [Leu5]‐enkephalin (Tyr‐Gly‐Gly‐Phe‐Leu) was chosen as a model peptide. Exploratory NMR experiments identified the Ru(p‐cymene)Cl2 complex of the asymmetrically substituted imidazol‐2‐ylidene 3b as the most suitable metal carbene precursor for solid phase peptide synthesis (SPPS). After optimization of the conditions for SPPS, a ruthenium‐NHC pseudoenkephalin (dichloro(η6‐p‐cymene)[1‐methyl‐3‐(methyl‐p‐benzoyl‐Gly‐Gly‐Phe‐Leu‐OH)imidazol‐2‐ylidene]ruthenium(II), 12) was synthesized from 3b on solid phase using the 2‐Cl‐Trt resin and cleavage by 2 % TFA to yield the free carboxylic acid. Peptide 12 was fully characterized by HPLC, 1H and 13C NMR and ESI‐MS. Characteristic NMR signals, as well as the isotope pattern of Ru in the ESI‐MS, unequivocally confirm the formation of this metal‐carbene peptide bioconjugate.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Five‐ and Four‐Coordinate 1,3‐Diaza‐2‐yttria‐ and 1,3‐Diaza‐2‐scandia‐[3]ferrocenophanes
Authors: Wrackmeyer Bernd , Klimkina Elena V. , Milius Wolfgang
Published: June 2008

2‐Chloro‐1,3‐bis(trimethylsilyl)‐1,3‐diaza‐2‐metalla‐[3]ferrocenophanes with M = Y (3) and Sc (4) have been prepared as the dipyridine adducts, starting from YCl3 and ScCl3, respectively, and N,N′‐dilithio‐N,N′‐bis(trimethylsilyl)‐1,1′‐diaminoferrocene (2). The reaction of 3 with sodium pentamethylcyclopentadienide (NaCp*) gave the complex 5, in which the yttrium atom is four‐coordinate, bearing the diamido ligand, Cp* and one pyridine ligand. An ate complex of four‐coordinate yttrium (6) was obtained, when YCl3 was treated with 2 equiv. of 2. In 6a, the lithium atom is threefold coordinated by two of the four amido nitrogen atoms and by pyridine, and addition of an excess of pyridine gave the separated ion pairs (6b) in solution. The molecular structures of 3, 5 and 6a were determined by X‐ray structural analysis, and the solution‐state structures were deduced from consistent NMR spectroscopic data sets (1H, 13C, 29Si, 89Y NMR). The 89Y nuclear magnetic shielding of amido complexes appears to increase with the coordination number (3, 4, 5) of yttrium.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Stereoselective Synthesis of the First Chatt‐Type Bis(dinitrogen)‐Molybdenum(0) Complex with a Tetraphosphane Ligand
Authors: Römer René , Stephan Gerald , Habeck Carsten , Hoberg Christian , Peters Gerhard , Näther Christian , Tuczek Felix
Published: June 2008

The first Chatt‐type Mo0 dinitrogen complex with a tetraphosphane ligand has been prepared and characterized by NMR as well as infrared and Raman spectroscopy. Importantly, the employed reaction route allows the stereospecific synthesis of this complex as trans‐[Mo(N2)2(meso‐prP4)] (prP4 = a tetraphos ligand with a central propylene bridge). The stereoselectivity in the reaction course is induced by the oxido‐iodido‐molybdenum(IV) precursor [Mo(O)I(prP4)]+ which directs both phenyl groups of the bridging P atoms of prP4 into a meso configuration. The paper establishes a general strategy to synthesize mononuclear Mo0 dinitrogen and related molybdenum complexes with multidentate phosphane ligands which has not been possible to date. Moreover, the obtained molybdenum tetraphos N2 complex should exhibit a higher thermodynamic stability in the reactions of the Chatt cycle of synthetic nitrogen fixation than the conventional bis(diphos) complexes, due to the linkage of the two diphosphane units by an alkyl bridge. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
A Dual‐Channel Fluorescence‐Enhanced Sensor for Aluminum Ions Based on Photoinduced Electron Transfer and Excimer Formation
Authors: Lin Weiying , Yuan Lin , Feng Jianbo
Published: June 2008

Sensor 1 was developed as the first example of a fluorescence‐enhanced Al3+ sensor with unique dual‐channel emissions. The addition of Al3+ to 1 elicits a large fluorescence enhancement by inhibition of a quenching Photoinduced electron‐transfer (PET) channel and also a dramatic fluorescence enhancement due to promotion of an emissive excimer channel formation. The dual‐channel fluorescence‐enhanced response of the sensor contributes to its high sensitivity and selectivity.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Sequential Double Olefination of 2‐(Arylmethylidene)‐2‐phosphonoacetonitrile with Dimsyl Lithium and Aldehydes: A Domino Route to Densely Substituted 1,3‐Butadienes
Authors: Chowdhury Raghunath , Ghosh Sunil K.
Published: June 2008

An efficient and highly stereoselective synthesis of densely substituted 1,3‐dienes has been achieved which entails a sequential double olefination of 2‐(arylmethylidene)‐2‐phosphonoacetonitriles by a one‐pot domino process involving Michael addition of dimsyllithium to 2‐(arylmethylidene)‐2‐phosphonoacetonitrile, Horner–Wadsworth–Emmons reaction of the resulting phosphonate ylide with the added aldehyde followed by base induced methylsulfenoxy elimination. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Oxidative Amidation of Aldehydes and Alcohols with Primary Amines Catalyzed by KI‐TBHP
Authors: Reddy K. Rajender , Maheswari C. Uma , Venkateshwar M. , Kantam M. Lakshmi
Published: June 2008

Oxidative amidation of aldehydes and alcohols with amines to afford the corresponding amides in excellent yields and ee values over 98 % is achieved by using a catalytic amount of KI in combination with TBHP as the external oxidant. This method avoids the use of expensive and/or air‐sensitive reagents. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Electrocatalytic Oxidation of Sulfite on a Nickel Aquapentacyanoferrate Modified Electrode: Application for Simple and Selective Determination
Authors: Kumar S. Senthil , Narayanan S. Sriman
Published: June 2008

An electroactive metal cyanometallate complex, nickel aquapentacyanoferrate (NAPCF) was synthesized and characterized using XRD and UV‐vis spectral studies. The solid complex was then mechanically immobilized on the surface of a paraffin impregnated graphite electrode (PIGE) and the NAPCF modified electrode was characterized using cyclic voltammetry. The dependence of the modified electrode was tested in terms of supporting electrolyte, scan rate and pH of the medium. The electrocatalytic oxidation of sulfite at the modified electrode was investigated by cyclic voltammetry, hydrodynamic voltammetry and chronoamperometry techniques. It was found that the NAPCF modified electrode efficiently exhibited electrocatalytic activity for the oxidation of sulfite with relatively high sensitivity, selectivity and long life of activity. Based on the electrocatalytic oxidation, the NAPCF modified electrode was used as a sensor for the determination of sulfite. The linear working range for the determination of sulfite was 2.78×10−6 M to 3.00×10−3 M with a detection limit of 9.26×10−7 M. The electrode was applied for the determination of sulfite in real samples satisfactorily.
Selective Electrochemical Determination of Uric Acid in the Presence of Ascorbic Acid Using a Carbon Paste Electrode Modified with β‐Cyclodextrin
Authors: Ramírez‐Berriozabal Minerva , Galicia Laura , Gutiérrez‐Granados Silvia , Cortes José Sandoval , Herrasti Pilar
Published: June 2008

Uric acid (UA) was determined in the presence of ascorbic acid (AA) by using a carbon paste electrode modified superficially by a β‐cyclodextrin film (CPE/β‐CD). The surface carbon paste electrode was prepared applying a 30 cycles potential program and using a 1 M HClO4+0.01 M β‐CD electrolytic solution. The UA and AA solutions were used to evaluate the electrode selectivity and sensitivity by cyclic voltammetric and amperometric methods. In these experiments the detection limit for UA was (4.6±0.01)×10−6 M and the RSD calculated from the amperometric curves was 10%. From the data obtained it was possible to quantify UA in the urine and saliva samples. Selective detection of UA was improved by formation of an inclusion complex between β‐CD and UA. The results show that the CPE/β‐CD is a good candidate due to its selectivity and sensitivity in the UA determination in complex samples like the biological fluids.
Electrochemical Study on DNA Damage Based on the Direct Oxidation of 8‐Hydroxydeoxyguanosine at an Electrochemically Modified Glassy Carbon Electrode
Authors: Zhang Jing‐Jing , Wang Bin , Li Yan‐Fen , Jia Wen‐Li , Cui Hui , Wang Huai‐Sheng
Published: June 2008

The study of DNA damage induced by Fenton reaction (Fe2+/H2O2) in vitro was performed based on the direct electrochemical oxidation of 8‐hydroxydeoxyguanosine (8‐OH‐dG), the biomarker of DNA oxidative damage, at an electrochemically modified glassy carbon electrode (GCE). The effects of antioxidants, such as ascorbic acid, and hydroxyl‐radical scavenger (mannitol) on the DNA damage were also investigated. 8‐OH‐dG, the oxidation product of guanine residues in DNA, has shown significantly oxidative peak on the electrochemically modified GCE. The oxidative peak current of 8‐OH‐dG was linear with the damaged DNA concentration in the range of 10–200 mg/L. The experimental results demonstrate that ascorbic acid has ambivalent effect on DNA oxidative stress. It can promote DNA oxidative damage when ascorbic acid concentration is below 1.5 mM and protect DNA from damage in the range of 1.5–2.5 mM. As a hydroxyl‐radical scavenger, mannitol inhibits significantly DNA oxidative damage. The influence of Fe2+, as reactant, and EDTA as iron chelator in the system were also studied. The proposed electrochemical method can be used for the estimation of DNA oxidative damage from new point of view.
Surface Modification of Gold by Quercetin Monolayer for the Electrochemical Determination of Copper(II)
Authors: Xu Guang‐Ri , Yuan Yong , Kim Sunghyun , Lee Jae‐Joon
Published: June 2008

A quercetin monolayer has been prepared on top of the self‐assembled 3‐mercaptopropionic acid (MPA) layer for the copper ion determination. Cu2+ ions are readily accumulated on this modified electrode through the complex formation and electrochemically detected. With a quercetin layer, the redox process of Cu2+ became more reversible than at the MPA‐modified electrode. Complexation sites in MPA and quercetin were occupied within five min when the electrode was immersed in 10 μM Cu2+ solution. The MPA and quercetin layers were stable enough to allow repeated EDTA treatment to remove adsorbed Cu2+ for the surface regeneration. Only 7% decrease was found after ten times regeneration and use. Linear current response was found over the concentration range of 1 nM and 10 μM with detection limit of 0.1 nM. Common interfering ions such as Cd2+, Zn2+, and Fe2+/3+ did not show any electrochemical response in the potential range of Cu2+ determination.
Synthesis of Carbon Nanofibers for Mediatorless Sensitive Detection of NADH
Authors: Liu Yang , Hou Haoqing , You Tianyan
Published: June 2008

Highly sensitive amperometric detection of dihydronicotinamide adenine dinucleotide (NADH) by using novel synthesized carbon nanofibers (CNFs) without addition of any mediator has been proposed. The CNFs were prepared by combination of electrospinning technique with thermal treatment method and were applied without any oxidation pretreatment to construct the electrochemical sensor. In amperometric detection of NADH, a linear range up to 11.45 μM with a low detection limit of 20 nM was obtained with the CNF‐modified carbon paste electrode (CNF‐CPE). Good selectivity was exhibited for the simultaneous detection of NADH and its common interferent of ascorbic acid (AA) by differential pulse voltammogram. The attractive electrochemical performance and the versatile preparation process of the CNF‐CPE made it a promising candidate for designing effective NADH sensor.
Adsorptive Stripping Voltammetric Determination of 4‐Hexylresorcinol in Pharmaceutical Products Using Multiwalled Carbon Nanotube Based Electrodes
Authors: Kachoosangi Roohollah Torabi , Wildgoose Gregory G. , Compton Richard G.
Published: June 2008

A sensitive electroanalytical method is presented for the determination of 4‐hexylresorcinol using adsorptive stripping voltammetry (AdsSV) at a multiwalled carbon nanotube modified basal plane pyrolytic graphite electrode (MWCNT‐BPPGE). This method is also extended to the use of a MWCNT modified screen‐printed electrode (MWCNT‐SPE), thereby demonstrating that this approach can easily be incorporated into a facile and inexpensive electrochemical sensor.
Searching the genome for our adaptations
Authors: Harris Eugene E.
Published: June 2008

The current genomic revolution represents a turning point in our understanding of human evolution. For the first time, we are able to begin to investigate human evolutionary adaptations by comparing our entire genome with the genomes of other animal species with which we are related by descent. We are also able to begin fully investigating the genetic differences within and among human populations to understand exactly how human populations have evolved and adapted over time.
On the Chebyshev collocation spectral approach to stability of fluid flow in a porous medium
Authors: Makinde O. D.
Published: June 2008

In this paper, the temporal development of small disturbances in a pressure‐driven fluid flow through a channel filled with a saturated porous medium is investigated. The Brinkman flow model is employed in order to obtain the basic flow velocity distribution. Under normal mode assumption, the linearized governing equations for disturbances yield a fourth‐order eigenvalue problem, which reduces to the well‐known Orr–Sommerfeld equation in some limiting cases solved numerically by a spectral collocation technique with expansions in Chebyshev polynomials. The critical Reynolds number Rec, the critical wave number αc, and the critical wave speed cc are obtained for a wide range of the porous medium shape factor parameter S. It is found that a decrease in porous medium permeability has a stabilizing effect on the fluid flow. Copyright © 2008 John Wiley & Sons, Ltd.