bluuebunny/crossref_metadata_2025 huggingface dataset:
Iridium‐Catalyzed Dehydrogenative Decarbonylation of Primary Alcohols with the Liberation of Syngas
Authors: Olsen Esben P. K. , Madsen Robert
Published: October 2012

A new iridium‐catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe=cyclooctene) and racemic 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (rac‐BINAP) in a mesitylene solution saturated with water. A catalytic amount of lithium chloride was also added to improve the catalyst turnover. The reaction has been applied to a variety of primary alcohols and gives rise to products in good to excellent yields. Ethers, esters, imides, and aryl halides are stable under the reaction conditions, whereas olefins are partially saturated. The reaction is believed to proceed by two consecutive organometallic transformations that are catalyzed by the same iridium(I)–BINAP species. First, dehydrogenation of the primary alcohol to the corresponding aldehyde takes place, which is then followed by decarbonylation to the product with one less carbon atom.
Enzyme–Substrate Complementarity Governs Access to a Cationic Reaction Manifold in the P450BM3‐Catalysed Oxidation of Cyclopropyl Fatty Acids
Authors: Cryle Max J. , Hayes Patricia Y. , De Voss James J.
Published: October 2012

The products of cytochrome P450BM3‐catalysed oxidation of cyclopropyl‐containing dodecanoic acids are consistent with the presence of a cationic reaction intermediate, which results in efficient dehydrogenation of the rearranged probes by the enzyme. These results highlight the importance of enzyme–substrate complementarity, with a cationic intermediate occurring only when the probes used begin to diverge from ideal substrates for this enzyme. This also aids in reconciling literature reports supporting the presence of cationic intermediates with certain cytochrome P450 enzyme/substrate pairs.
Characterization of Telmisartan‐Derived PPARγ Agonists: Importance of Moiety Shift from Position 6 to 5 on Potency, Efficacy and Cofactor Recruitment
Authors: Herbst Lena , Goebel Matthias , Bandholtz Sebastian , Gust Ronald , Kintscher Ulrich
Published: October 2012

Selective modulation of the peroxisome proliferator‐activated receptor gamma (PPARγ) by direct binding of small molecules demonstrates a promising tool for treatment of insulin resistance and type 2 diabetes mellitus. Besides its blood pressure‐lowering properties, the AT1‐receptor blocker telmisartan has been shown to be a partial agonist of PPARγ with beneficial metabolic effects in vitro and in mice. In our previous work, comprehensive structure–activity relationship (SAR) studies discussed the different parts of the telmisartan structure and various moieties. Based on these findings, we designed and synthesized new PPARγ ligands with a benzimidazole (agonists 4‐5 and 4‐6), benzothiophene (agonists 5‐5 and 5‐6) or benzofuran (agonists 6‐5 and 6‐6) moiety either at position 5 or 6 of the benzimidazole core structure. Lipophilicity and EC50 values were improved for all new compounds compared with telmisartan. Regarding PPARγ activation, the compounds were characterized by a differentiation assay using 3T3‐L1 cells and a luciferase assay with COS‐7 cells transiently transfected with pGal4‐hPPARgDEF, pGal5‐TK‐pGL3 and pRL‐CMV. A decrease in both potency and efficacy was observed after the shift of either the benzothiophene or the benzofuran moiety from position 6 to position 5. Selective recruitment of the coactivators TRAP220, SRC‐1 and PGC‐1α, and release of corepressor NCoR1 determined by time‐resolved fluorescence resonance energy transfer (TR‐FRET) was detected depending on residues in position 5 or 6.
Regulating cell morphogenesis: The drosophila jun N‐terminal kinase pathway
Authors: Ríos‐Barrera Luis Daniel , Riesgo‐Escovar Juan Rafael
Published: October 2012

The Jun‐N‐terminal Kinase pathway (JNK), known also as stress activated protein kinase pathway (SAPK), is an eukaryotic evolutionarily conserved signaling pathway. From a purported evolutionarily “ancient” function as stress mediator, it evolved in multicellular eukaryotes to permanent roles in development, without leaving its original function. In Drosophila melanogaster, it is required for follicle cell morphogenesis, embryonic dorsal closure, pupal thoracic closure and genital disc rotation closure, all processes with requisite cell shape changes. Besides, it is activated during wound healing and in response to stress (UV irradiation, oxidative stress) where it may signal cell death or proliferation. Despite these varied roles, it has a conserved core of molecules that follow the MAPKKK/MAPKK/MAPK logic of mitogen activated protein kinases pathways. Regulation of the JNK pathway appears majorly negative, with phosphatases, transcription factors and proteins of novel structure “holding back” on JNK activation in different tissues. This particular mode of regulation may hark back to the pathway's origin as stress detector and responder, implying readiness to respond, from which the developmental roles may have evolved as conditions demanding obligate and predicted stress responses (i.e., embryonic dorsal closure viewed as a “wound of development”). genesis 51:147–162, 2013. © 2012 Wiley Periodicals, Inc.
3D Coordination Polymer of [HW7O24]5– Stabilized by a Copper(II) Complex and Sodium Cations: Structure, Solid‐State Stability, and Aqueous Solution Behavior
Authors: Wang Xin‐Fang , Cao Jie , Huang Kun‐Lin , Xu Yan‐Qing , Chi Ying‐Nan , Hu Chang‐Wen
Published: October 2012

Compound Na[Cu(en)2]2[HW7O24]·5H2O (1, en = ethanediamine), as the first example of a heptatungstate polymer, has been synthesized in H2O/dmso and characterized by single‐crystal X‐ray diffraction, IR, UV/Vis, and ESI‐MS. The [HW7O24]5– cluster in 1, as an inorganic hexadentate ligand, coordinates to two Na+ and four [Cu(en)2]2+ cations to construct a 3D extended structure. The solid‐state stability of 1 at room temperature was proven by X‐ray powder diffraction and digital camera techniques. The electrospray mass spectra suggest that most of the [HW7O24]5– dissociates into relatively more stable [W6O19]2– species in aqueous solution because the coordination bonds around the [HW7O24]5– anions are broken by the solvation effect of water on the the copper cation. These results demonstrate that a transition‐metal‐complex cation plays an important role in the isolation and stabilization of a highly charged polyoxometalate anion.
Interactions between Keggin Anions in Water: The Higher Their Charge, the Higher Their Condensation? A Simulation Study
Authors: Chaumont Alain , Wipff Georges
Published: October 2012

We report molecular dynamics (MD) simulations of aqueous solutions of Keggin heteropolyacids XWn– nH3O+ (XWn– = [PW12O40]3–, [SiW12O40]4–, and [AlW12O40]5–), the aim of which was to investigate whether the anions increasingly repulse each other in water when their charge increases from –3 to –5. The MD and PMF (potential of mean force) results indicate that this is not the case. All three anions are found to display short XWn–···XWn– contacts (“dimers”), the amount of which increases at increasing concentrations. However, the proportion of dimers follows the sequence SiW4– < PW3– < AlW5–, which is unexpected from interanionic Coulomb forces. The least‐charged anions are mainly attracted by hydrophobic forces, whereas the most charged AlW5– anions afford the highest proportion of dimers through specific interactions with H3O+ counterions. Similar features are observed in two series of fictitious analogues of XWn– (n = 3 to 5): the Sn– spherical anions, and the XWn+ cations (with all atomic charges of XWn– inverted and “H3O–” as counterions). The key role of counterion condensation on the stabilization of the most negatively charged dimers is further demonstrated by comparing Li+ salts to Na+ and Cs+ salts of the different XWn– anions: anion–anion dimerization is found to be highest between AlW5– anions and in the presence of the “hardest” counterions (Li+). Likewise, with Eu3+ multivalent AlW5– counterions condense into a concentrated ionic domain in water. Finally, all three types of XWn– anions are found to adsorb at the aqueous interface with graphite. These findings are important for understanding processes like dimerization, condensation, third phase formation, and the assembly of polyoxometalates and macroions in water or at aqueous interfaces.
Various radical polymerizations of glycerol‐based monomers
Authors: Pham Phuoc Dien , Monge Sophie , Lapinte Vincent , Raoul Yann , Robin Jean Jacques
Published: October 2012

This paper aims at making the state of the art of the radical polymerizations of glycerol‐based monomers, especially (meth)acrylate and vinylic/allylic derivatives. Acrylate and methacrylate derivatives bearing numerous secondary groups like ester, cyclocarbonate, acetal, and urethane were involved in free radical polymerization and radical controlled polymerizations as well as in the photopolymerization. Glycerol‐based monomers bearing a vinylic or an allylic polymerizable group polymerize by acceptor–donor process and produce alternating copolymers. From all these monomers, the synthesis of functionalized polymers was possible, leading to various valuable applications.
Configurational Assignment of Cyclic Bisbibenzyls by HPLC‐CD and Quantum‐Chemical CD Calculations
Authors: Schaumlöffel Anu , Groh Matthias , Knauer Michael , Speicher Andreas , Bringmann Gerhard
Published: October 2012

Macrocyclic bisbibenzyls are intriguing natural products that are obtained from liverworts. Recently, they have received growing interest due to the discovery of novel representatives and because of their antitumoral and antifungal activities. Depending on the individual coupling type, these structures can possess one or two biaryl axes, which, with larger ortho substituents or increased ring strain within the macrocycle, leads to the occurrence of configurationally stable atropisomers. Within this work, representatives of the plagiochin and riccardin types, both containing one biaryl unit and one biaryl ether moiety, have been investigated for their stereochemical stabilities and electronic circular dichroism (ECD) by means of HPLC‐UV and HPLC‐CD in combination with quantum‐chemical DFT and ab initio RICC2 calculations. We demonstrate that the computation of the chiroptical properties of such macrocycles is a nontrivial task, because of the presence of charge‐transfer (CT) excitations especially in the riccardin‐type structures, which leads to a failure of DFT methods in the excited‐states calculations, thus necessitating the use of the coupled‐cluster approach for a reliable attribution of the absolute configurations of the enantiomers. In the course of this study, the previous assignments of the absolute configurations of the atropisomers of plagiochin E and riccardin D are revised.
Construction of Chiral Multi‐Functionalized Polyheterocyclic Benzopyran Derivatives by Using an Asymmetric Organocatalytic Domino Reaction
Authors: Guo Zhi‐Wei , Li Xin‐Sheng , Zhu Wei‐Dong , Xie Jian‐Wu
Published: October 2012

The asymmetric domino reaction of various α,α‐dicyano olefins to 3‐nitro‐2H‐chromenes was studied employing readily available cinchona‐derived bifunctional thioureas as organocatalysts. These new transformations were highly regio‐, chemo‐, diastereo‐, and enantioselective simultaneously giving chiral multi‐functionalized polyheterocyclic benzopyran derivatives with multi‐chiral carbon centers.
Mechanism and Scope of the MnIII‐Initiated Oxidation of β‐Ketocarbonyl Compounds: Furan Synthesis
Authors: Wang Chao , Li Zhilong , Ju Yeming , Koo Sangho
Published: October 2012

Unless the MnIII‐produced carbon‐radical from β‐ketocarbonyl compounds undergoes smooth intramolecular addition to alkenes, it traps molecular oxygen in the reaction medium to produce a peroxy radical, which reacts with the neighbouring carbonyl group to form 1,2‐dioxetane. Thermal decomposition of 1,2‐dioxetane completes the oxidation to produce α‐oxo ester. This oxidation seems to be general at 50 °C under aerobic conditions, and can be catalytic for MnIII in AcOH with ultrasonic irradiation. Thus, the development of a new synthetic method for diversely substituted furans has been accomplished based on a couple of the MnIII‐initiated domino oxidation of β‐ketocarbonyl compounds with a suitable α‐allylic substitution.
Impact of channel estimation error on fixed‐gain two‐way relay network with user/antenna selection
Authors: Fan Lisheng , Lei Xianfu , Chen Hongbin , Zhou Wen
Published: October 2012

This letter considers a multiuser two‐way relay network with a single fixed‐gain amplify‐and‐forward relay, where there areMantennas at the base station (BS) andNmobile stations. Depending on the channel conditions, one best antenna from BS and one best user are selected to communicate with each other. We study the impact of channel estimation error to the system over Rayleigh fading environments. In particular, a closed‐form expression is obtained for system outage probability. It is found that an error floor appears in the outage probability as long as the channel estimation is imperfect. We further study the power allocation (PA) among the network nodes to minimise the outage probability. Numerical results are presented to evaluate the effects of both channel estimation error and PA on the system performance. Copyright © 2012 John Wiley & Sons, Ltd.
The human sulfatase 2 inhibitor 2,4‐disulfonylphenyl‐tert‐butylnitrone (OKN‐007) has an antitumor effect in hepatocellular carcinoma mediated via suppression of TGFB1/SMAD2 and Hedgehog/GLI1 signaling
Authors: Zheng Xin , Gai Xiaohong , Han Shaoshan , Moser Catherine D. , Hu Chunling , Shire Abdirashid M. , Floyd Robert A. , Roberts Lewis R.
Published: October 2012

Human sulfatase 2 (SULF2) functions as an oncoprotein in hepatocellular carcinoma (HCC) development by promoting tumor growth and metastasis via enhancement of fibroblast growth factor‐2/extracellular signal‐regulated kinase and WNT/β‐catenin signaling. Recent results implicate that SULF2 activates the transforming growth factor beta (TGFB) and Hedgehog/GLI1 pathways in HCC. OKN‐007 is a novel phenyl–sulfonyl compound that inhibits the enzymatic activity of SULF2. To investigate the antitumor effect of OKN‐007 in HCC, we treated Huh7 cells, which express high levels of SULF2, with OKN‐007 and found that it significantly promoted tumor cell apoptosis and inhibited cell proliferation, viability, and migration. To understand the action of OKN‐007 on SULF2, we used Huh7 cells which normally express SULF2 and Hep3B cells that do not normally express SULF2. Utilizing Huh7 cells transfected with short hairpin RNA targeting SULF2 and transfection of Hep3B cells with a SULF2 plasmid to enhance SULF2 expression, we showed that the antitumor activity of OKN‐007 was more pronounced in cells expressing SULF2. Furthermore, in vivo experiments verified that OKN‐007 repressed tumor growth significantly. These results identify SULF2 as an important target of the antitumor effect of OKN‐007. To determine the molecular mechanism of the antitumor effect of OKN‐007, both TGFB1/SMAD and Hedgehog/GLI1 signaling pathway activity were measured by Western blot and SMAD‐ or GLI‐reporter luciferase assays. We found that both signaling pathways were inhibited by OKN‐007. Together, these results show that OKN‐007 can suppress TGFB1/SMAD and Hedgehog/GLI1 signaling via its inhibition of SULF2 enzymatic activity. We conclude that OKN‐007 or more potent derivatives may be promising agents for the treatment of HCC. © 2012 Wiley‐Periodicals, Inc.
PARENTAL INCOME AND THE DYNAMICS OF HEALTH INEQUALITY IN EARLY CHILDHOOD—EVIDENCE FROM THE UK
Authors: Kruk Kai Eberhard
Published: October 2012

Recent research documents that socioeconomic health inequality has its origins in early childhood, that is, children from high‐income families have better health than their peers from low‐income families. In this article, we investigate the determinants of the evolution of socioeconomic health inequality in the UK. We analyze the relation between household income and both the prevalence and the consequences of adverse health conditions by following up infants throughout early childhood. We find evidence for the hypothesis that parental income operates through two different channels: it reduces the likelihood of incurring certain illnesses and it cushions the consequences of health conditions. Our results also indicate that a higher household income increases the probability that children fully recover from some diseases within a given period. Copyright © 2012 John Wiley & Sons, Ltd.
Direct effect of dasatinib on proliferation and cytotoxicity of natural killer cells in in vitro study
Authors: Uchiyama Takayoshi , Sato Naoya , Narita Miwako , Yamahira Akie , Iwabuchi Minami , Furukawa Tatsuo , Sone Hirohito , Takahashi Masuhiro
Published: October 2012

Lymphocytosis predominantly due to natural killer (NK) cells has been reported in nearly a half of chronic myelogenous leukemia (CML) patients who were being treated with dasatinib. Besides, dasatinib‐treated patients with lymphocytosis have a better prognosis than patients without lymphocytosis. In order to elucidate the effects of dasatinib on the proliferation of lymphocyte subset, dasatinib was added to the culture of peripheral blood mononuclear cells with IL‐2 (lymphokine‐activated killer culture) or a low dose of IL‐2 with zoledronate (γδ T‐cell culture). In both culture conditions, NK cells were increased in both percentage and absolute number in the culture with dasatinib compared with control culture without dasatinib. The increase of NK cells was dose dependent of dasatinib in the range of 2–25 nM. NK cell cytotoxicity of cultured cells with dasatinib was demonstrated to be superior to control cells without dasatinib in cytotoxicity assay using EGFP‐transfected K562 cells as target cells. The present study suggested that lymphocytosis in dasatinib‐treated CML patients is at least partly associated with a direct effect of dasatinib to stimulate the proliferation of NK cells. Favourable prognosis in patients with dasatinib‐induced lymphocytosis might be associated with the effects of dasatinib to potentiate NK cytotoxicity in vivo. Copyright © 2012 John Wiley & Sons, Ltd.
A mixed‐methods assessment of sexual and gender‐based violence in eastern Democratic Republic of Congo to inform national and international strategy implementation
Authors: Scott Jennifer , Polak Suzanne , Kisielewski Michael , McGraw‐Gross Mary , Johnson Kirsten , Hendrickson Miel , Lawry Lynn
Published: October 2012

Context

National and international strategies were implemented in eastern Democratic Republic of Congo (DRC) to address sexual and gender‐based violence (SGBV).

Objectives

The objective was to assess community attitudes of SGBV and health facility capacity to address SGBV in eastern DRC.

Design and setting

The design and setting are as follows: a cross‐sectional, population‐based cluster survey of 998 adults in eastern DRC territories, a convenience sample of 27 adults using semi‐structured directed interviews, qualitative data from 37 focus groups conducted in three health zones, assessment of 64 health facilities and a comparative analysis of SGBV strategies.

Main outcome measures

The main outcome measures opinions regarding SGBV prevention and justice and health facility capacity to address SGBV.

Results

The majority of respondents favored the legal system over community mediation to obtain justice for SGBV. However, 61.1% (95% CI, 51.8–70.5%) of SGBV survivors reported being forced to accept community mediation. Among SGBV survivors, 81.2% (95% CI, 74.5–87.8%) reported no available mental health care. Less than half of all respondents reported access to a hospital, clinic or pharmacy. The analyses and facility assessment reinforce the need to improve SGBV care.

Conclusions

Mixed methodologies point to the complexities of addressing SGBV, assess key elements of SGBV prevention, justice and response, and may ultimately inform national and international strategies. Copyright © 2012 John Wiley & Sons, Ltd.
Biodistribution of intact fluorescent CdSe/CdS/ZnS quantum dots coated by mercaptopropionic acid after intravenous injection into mice
Authors: Loginova Yana F. , Kazachkina Natalia I. , Zherdeva Victoria V. , Rusanov Alexander L. , Shirmanova Marina V. , Zagaynova Elena V. , Sergeeva Ekaterina A. , Dezhurov Sergey V. , Wakstein Maxim S. , Savitsky Alexander P.
Published: October 2012

Semiconductor quantum dots (QD) have been widely used for fluorescent bioimaging. However their biosafety has attracted increasing attention, since the data about their in vivo behavior in biological systems are still limited. In this paper we have investigated the short‐ and long‐term biodistribution of intact fluorescent CdSe/CdS/ZnS QD coated by 3‐mercaptopropionic acid in mice. The results showed that intravenously injected QD accumulated mainly in the lungs, liver and spleen and were retained in these tissues for over 22 days. QD caused signs of acute toxicity in mice including death. The investigated QD possibly caused vascular thrombosis. The results of a toxicological assay indicated that some histopathological changes occurred in the lung tissue after the injection of QD. Our study highlights the need for careful evaluation of QD safety before their use in biological applications. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Discontinuation of denosumab and associated fracture incidence: Analysis from the Fracture Reduction Evaluation of Denosumab in Osteoporosis Every 6 Months (FREEDOM) Trial
Authors: Brown Jacques P , Roux Christian , Törring Ove , Ho Pei-Ran , Beck Jensen Jens-Erik , Gilchrist Nigel , Recknor Christopher , Austin Matt , Wang Andrea , Grauer Andreas , Wagman Rachel B
Published: October 2012

Osteoporosis is a chronic disease and requires long-term treatment with pharmacologic therapy to ensure sustained antifracture benefit. Denosumab reduced the risk for new vertebral, nonvertebral, and hip fractures over 36 months in the Fracture Reduction Evaluation of Denosumab in Osteoporosis Every 6 Months (FREEDOM) trial. Whereas discontinuation of denosumab has been associated with transient increases in bone remodeling and declines in bone mineral density (BMD), the effect on fracture risk during treatment cessation is not as well characterized. To understand the fracture incidence between treatment groups after cessation of investigational product, we evaluated subjects in FREEDOM who discontinued treatment after receiving two to five doses of denosumab or placebo, and continued study participation for ≥7 months. The off-treatment observation period for each individual subject began 7 months after the last dose and lasted until the end of the study. This subgroup of 797 subjects (470 placebo, 327 denosumab), who were evaluable during the off-treatment period, showed similar baseline characteristics for age, prevalent fracture, and lumbar spine and total hip BMD T-scores. During treatment, more placebo-treated subjects as compared with denosumab-treated subjects sustained a fracture and had significant decreases in BMD. During the off-treatment period (median 0.8 years per subject), 42% versus 28% of placebo- and denosumab-treated subjects, respectively, initiated other therapy. Following discontinuation, similar percentages of subjects in both groups sustained a new fracture (9% placebo, 7% denosumab), resulting in a fracture rate per 100 subject-years of 13.5 for placebo and 9.7 for denosumab (hazard ratio [HR] 0.82; 95% confidence interval [CI], 0.49–1.38), adjusted for age and total hip BMD T-score at baseline. There was no apparent difference in fracture occurrence pattern between the groups during the off-treatment period. In summary, there does not appear to be an excess in fracture risk after treatment cessation with denosumab compared with placebo during the off-treatment period for up to 24 months. © 2013 American Society for Bone and Mineral Research.
Binding structures of tri‐N‐acetyl‐β‐glucosamine in hen egg white lysozyme using molecular dynamics with a polarizable force field
Authors: Zhong Yang , Patel Sandeep
Published: October 2012

Lysozyme is a well‐studied enzyme that hydrolyzes the β‐(1,4)‐glycosidic linkage of N‐acetyl‐β‐glucosamine (NAG)n oligomers. The active site of hen egg‐white lysozyme (HEWL) is believed to consist of six subsites, A‐F that can accommodate six sugar residues. We present studies exploring the use of polarizable force fields in conjunction with all‐atom molecular dynamics (MD) simulations to analyze binding structures of complexes of lysozyme and NAG trisaccharide, (NAG)3. MD trajectories are applied to analyze structures and conformation of the complex as well as protein–ligand interactions, including the hydrogen‐bonding network in the binding pocket. Two binding modes (ABC and BCD) of (NAG)3 are investigated independently based on a fixed‐charge model and a polarizable model. We also apply molecular mechanics with generalized born and surface area (MM‐GBSA) methods based on MD using both nonpolarizable and polarizable force fields to compute binding free energies. We also study the correlation between root‐mean‐squared deviation and binding free energies of the wildtype and W62Y mutant; we find that for this prototypical system, approaches using the MD trajectories coupled with implicit solvent models are equivalent for polarizable and fixed‐charge models. © 2012 Wiley Periodicals, Inc.
Solvent‐driven symmetry of self‐assembled nanocrystal superlattices—A computational study
Authors: Kaushik Ananth P. , Clancy Paulette
Published: October 2012

The preference of experimentally realistic sized 4‐nm facetted nanocrystals (NCs), emulating Pb chalcogenide quantum dots, to spontaneously choose a crystal habit for NC superlattices (Face Centered Cubic (FCC) vs. Body Centered Cubic (BCC)) is investigated using molecular simulation approaches. Molecular dynamics simulations, using united atom force fields, are conducted to simulate systems comprised of cube‐octahedral‐shaped NCs covered by alkyl ligands, in the absence and presence of experimentally used solvents, toluene and hexane. System sizes in the 400,000–500,000‐atom scale followed for nanoseconds are required for this computationally intensive study. The key questions addressed here concern the thermodynamic stability of the superlattice and its preference of symmetry, as we vary the ligand length of the chains, from 9 to 24 CH2 groups, and the choice of solvent. We find that hexane and toluene are “good” solvents for the NCs, which penetrate the ligand corona all the way to the NC surfaces. We determine the free energy difference between FCC and BCC NC superlattice symmetries to determine the system's preference for either geometry, as the ratio of the length of the ligand to the diameter of the NC is varied. We explain these preferences in terms of different mechanisms in play, whose relative strength determines the overall choice of geometry. © 2012 Wiley Periodicals, Inc.
A detailed investigation on the global minimum structures of mixed rare‐gas clusters: Geometry, energetics, and site occupancy
Authors: Marques Jorge M. C. , Pereira Francisco B.
Published: October 2012

We performed a global minimum search of mixed rare‐gas clusters by applying an evolutionary algorithm (EA), which was recently proposed for binary atomic systems (Marques and Pereira, Chem. Phys. Lett. 2010, 485, 211). Before being applied to the potentials used in this work, the EA was further tested against results previously reported for the ArNXe38−N clusters and several new putative global minima were discovered. We employed either simple Lennard‐Jones (LJ) potentials or more realistic functions to describe pair interactions in ArNKr38−N, ArNXe38−N, and KrNXe38−N clusters. The long‐range tail of the pair‐potentials shows some influence on the energetic features and shape of the structure of clusters. In turn, core–shell type structures are mostly observed for global minima of the binary rare‐gas clusters, for both accurate and LJ potentials. However, the long‐range tail of the potential may have influence on the type of atoms that segregate on the surface or form the core of the cluster. While relevant differences for the preferential site occupancy occur between the two potentials for ArNKr38−N (for N > 21), the type of atoms that segregate on the surface for ArNXe38−N and KrNXe38−N clusters is unaffected by the accuracy of the long‐range part of the interaction in almost all cases. Moreover, the global minimum search for model‐potentials in binary systems reveals that the surface‐site occupancy is mainly determined by the combination of two parameters: the size ratio of the two types of particles forming the cluster and the minimum‐energy ratio corresponding to the pair‐interactions between unlike atoms. © 2012 Wiley Periodicals, Inc.
Insights into the dynamics of evaporation and proton migration in protonated water clusters from Large‐scale Born–Oppenheimer direct dynamics
Authors: Rybkin Vladimir V. , Simakov Anton O. , Bakken Vebjørn , Reine Simen , Kjærgaard Thomas , Helgaker Trygve , Uggerud Einar
Published: October 2012

Large‐scale on‐the‐fly Born–Oppenheimer molecular dynamics simulations using recent advances in linear scaling electronic structure theory and trajectory integration techniques have been performed for protonated water clusters around the magic number (H2O)nH+, for n = 20 and 21. Besides demonstrating the feasibility and efficiency of the computational approach, the calculations reveal interesting dynamical details. Elimination of water molecules is found to be fast for both cluster sizes but rather insensitive to the initial geometry. The water molecules released acquire velocities compatible with thermal energies. The proton solvation shell changes between the well‐known Eigen and Zundel motifs and is characterized by specific low‐frequency vibrational modes, which have been quantified. The proton transfer mechanism largely resembles that of bulk water but one interesting variation was observed. © 2012 Wiley Periodicals, Inc.
Determination of Hg(II) in Environmental Water Samples by Dispersive Liquid Phase Microextraction Combined with Flame Atomic Absorption Spectrometry
Authors: Bahar Soleiman , Zakerian Razieh
Published: October 2012

In this study, a method of dispersive liquid phase microextraction combined with the flame atomic absorption spectrometry was proposed for the determination of trace Hg using diphenylthiocarbazone as chelating reagent. Several factors which have effect on the microextraction efficiency of Hg, such as pH, extraction and dispersive solvent type and their volume, concentration of the chelating agent, extraction time were investigated, and the optimized experimental conditions were established. After extraction, the enrichment factor was 68. The detection limit of the method was 45 ng mL−1, and the relative standard deviation for eight determinations of 2 μg mL−1 Hg was 1.7%. The results for the determination of Hg in environmental water samples (tap water, well water, mineral water and Caspian sea water) have demonstrated the applicability of the proposed method.
Preparation and Evaluation of Melamine Molecularly Imprinted Polymers by Thermal‐ and Photo‐initiation Methods
Authors: Zhang Yuping , Na Qi , Chen Na , Chen Jun , Zhou Xiaomao , Bai Lianyang
Published: October 2012

Melamine imprinted polymers (MIPs) have been prepared using identical polymer formulation by both thermal‐ and photo‐initiation method, respectively. Physical characterization of the polymers revealed that the different polymerization methods led to the slight differences in both polymer structures and performance by scanning electron microscope (SEM), infrared absorption (IR), and mercury analyzer (MA). Both MIPs were used as selective sorbents for the solid phase extraction (SPE) of melamine in milk powders, followed by the determination coupled to HPLC. The recoveries of melamine in spiked milk powders were obtained in the range of 92.4‐97.7% and 94.6‐99.7%, for both MIPthermal and MIPphoto, respectively.
Study of the acid pretreatment and biodiesel production from olive pomace oil
Authors: Ouachab Natasa , Tsoutsos Theocharis
Published: October 2012

The objective of this work was to study the two‐step acid base homogenous catalyzed transesterification of olive pomace oil, with the ultimate purpose of producing biodiesel under mild reaction conditions by optimizing the process. Optimization of the experimental procedure was conducted by a factorial design of 23 under the acidic pretreatment step and during the basic transesterification.

The optimal production of methyl esters (97.8%) was achieved for the experimental conditions H2SO4 = 20 wt%/CH3OH = 35:1/T = 40°C and KOH = 0.6+ fatty acid value /CH3OH = 9:1/ T = 60°C, in the acidic and basic stage of the process, respectively. Finally, to properly assess the quality of the biofuel produced, it was tested for all the European Standard properties.
Non‐isothermal self‐sustained one pot dissolution of metal values from manganese nodules using NH3OHCl as a novel reductant in sulfuric acid medium
Authors: Hariprasad D. , Mohapatra M. , Anand S.
Published: October 2012

Background

In view of depleting grades of land based ores, deep sea manganese nodules have become an important future resource of Cu, Ni, Co and Mn. A number of studies have been reported for the dissolution of metal values but till now no process has been commercialized and efforts are continuing to develop a process using an environmentally acceptable reductant. In the present study a novel reductant NH3OHCl has been used to develop a process.

Results

Dissolution studies were carried out by varying a number of experimental parameters. The optimum conditions established for >98% extraction of Cu(II), Ni(II), Co(II) and Mn(II) are: pulp density 20% (wt/v), time 20 min, reductant 8 g per 20 g of nodule and H2SO4 5% (v/v). The heat of mixing the reagents and fast instantaneous reactions automatically raised the slurry temperature and within a period of 20 min, it was possible to dissolve quantitatively the above said metal values. The leach solution was purified following (i) Fe(II) oxidation to Fe(III) by KMnO4 solution, (ii) iron removal by pH adjustment and (iii) precipitation of bulk sulfide by Na2S. A simplified flow‐sheet has been presented.

Conclusions

The deep sea nodules were leached under non‐isothermal conditions using a novel reductant, i.e. hydroxyl ammonium chloride in sulfuric acid medium. No external heat was needed for quantitative dissolution of Mn, Cu, Ni and Co values. A simple process has been presented for the treatment of Mn nodules.
Histochemical characterization of the sialic acid residues in mouse colon mucins
Authors: Mastrodonato Maria , Mentino Donatella , Liquori Giuseppa Esterina , Ferri Domenico
Published: October 2012

The mucins of colonic murine mucus are highly O‐glycosilated sulfosialoglycoproteins. We have characterized the sialylation pattern of oligosaccharide chains of colonic murine mucins by conventional histochemical methods and by lectin histochemistry combined with chemical pretreatments and sialidase digestion. Oligosaccharide chains are strongly sulphated, with an increase of sulfation from the proximal toward the distal colon and a decrease of sialic acid expression and acetylation toward the distal colon. In the goblet cells of proximal colon, sialic acid bound α2,3 to Galβ1,3GalNAc subterminal dimers is diacetylated at C7,C8;C7,C9;C8,C9 or triacetylated at C7,8,9. In the distal colon, sialic acid‐linked α2,3 to Galβ1,3GalNAc subterminal dimers shows reduced O‐acetylation at C7 and/or C8, while acetyl substituents at C9 and at C4 are almost absent. Sialic acid is involved in different essential physiological functions; thus, alterations of its expression and acetylation in oligosaccharide chains of intestinal mucins are generally associated with diseases, such as ulcerative colitis and cancer. Mice may represent a suitable animal model to study alterations of oligosaccharidic chains in colonic mucins and lectin histochemistry combined with chemical pretreatments, and enzyme digestion may be a valuable tool for this study. Our present work may represent a landmark for further lectin histochemical studies to evaluate alterations of mouse colon mucins under different physiological, pathological, or experimental conditions, with possible translational value in humans. Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.
Gape size, its morphological basis, and the validity of gape indices in western diamond‐backed rattlesnakes (crotalus atrox)
Authors: Hampton Paul M. , Moon Brad R.
Published: October 2012

Maximum gape is important to the ecology and evolution of many vertebrates, particularly gape‐limited predators, because it can restrict the sizes and shapes of prey that can be eaten. Although many cranial elements probably contribute to gape, it is typically estimated from jaw length or jaw width, or occasionally from a combination of these two measures. We measured maximum gape directly for 18 individuals of the western diamond‐backed rattlesnake, Crotalus atrox. We measured each individual's body length, several external cranial dimensions, several cranial osteological dimensions from cleaned skeletons, and we calculated gape index values from two published gape indices (GI). Cranial bone lengths and gape circumference showed negative allometry with snout–vent length (SVL), indicating that small individuals have relatively larger heads and gapes than their larger conspecifics. We then used Akaike's Information Criterion to determine which external and osteological measurements were the best predictors of gape. Body size (SVL) was the best predictor of maximum gape overall; however, when SVL was excluded from the analysis, quadrate (QL) and mandible lengths (MdLs) were the best predictors of maximum gape using both external and osteological measurements. Quadrate length probably contributes directly to gape; however, the importance of MdL to gape is less clear and may be due largely to its allometric relationships with head length and SVL. The two published GI did not prove to be better indicators of actual gape than the jaw and QLs in this study, and the gape values they produced differed significantly from our empirically determined gapes. For these reasons, we urge caution with the use and interpretation of computed GI in future studies. The extensive variation in quadrate and mandible morphology among lineages suggest that these bones are more important to variation in gape among species and lineages than within a single species. J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.
Comparative morphology of serotonergic‐like immunoreactive elements in the central nervous system of kinorhynchs (kinorhyncha, cyclorhagida)
Authors: Herranz María , Pardos Fernando , Boyle Michael J.
Published: October 2012

Cycloneuralian taxa exhibit similar organ system architectures, providing informative characters of metazoan evolution, yet very few modern comparative descriptions of cellular and molecular homologies within and among those taxa are available. We immunolabeled and characterized elements of the serotonergic nervous system in the kinorhynchs Echinoderes spinifurca, Antygomonas paulae, and Zelinkaderes brightae using confocal laser scanning microscopy. Fluorescent markers targeting DNA were combined with observations of auto‐fluorescent structures to guide interpretations of the internal and external anatomy in each species. Results show a common pattern of the central nervous system with a circumenteric brain divided into ring‐shaped anterior and posterior neuronal somata and a central neuropil connected to a multi‐stringed, longitudinal ventral nerve cord. Structural similarities and differences in the nervous systems of these species were observed and described, stressing the incomplete ring nature of the anterior region of the kinorhynch brain, the functional relationship between the brain and the movable introvert, and the number and arrangement of nerve strings and somata of the ventral nerve cord. The ventral cord ends in two ventrolateral cell bodies in E. spinifurca, and forms a terminal loop associated with a midterminal spine in A. paulae and Z. brightae. The possible functional and phylogenetic significance of these features and arrangements are discussed. J. Morphol., 2013. © 2012 Wiley Periodicals, Inc.
Engineering Candida albicans glucosamine‐6‐phosphate synthase for efficient enzyme purification
Authors: Czarnecka Justyna , Kwiatkowska Karolina , Gabriel Iwona , Wojciechowski Marek , Milewski Sławomir
Published: October 2012

Rationally designed muteins of Candida albicans glucosamine‐6‐phosphate synthase, an enzyme known as a promising target for antifungal chemotherapy, were constructed, overexpressed in Escherichia coli and purified to near homogeneity. To facilitate and to optimize the purification of the enzyme, three recombinant versions containing internal oligoHis fragments were constructed: (i) by substituting residues 343–348 of the interdomain undecapeptide linker with hexaHis, (ii) by replacing solvent‐exposed residues 655–660 of the isomerase domain with hexaHis, and (iii) by replacing amino acids at positions 568 and 569 with His residues to generate the three‐dimensional hexaHis microdomain in the enzyme quaternary structure. The resulting constructs were effectively purified to near homogeneity by rapid, one‐step immobilized metal‐ion affinity chromatography and demonstrated activity and catalytic properties comparable with that of the wild‐type enzyme. The construct containing the 655–660 hexaHis insert was found to be a homodimeric protein, which is the first reported example of such quaternary structure of glucosamine‐6‐phosphate synthase of eukaryotic origin. Copyright © 2012 John Wiley & Sons, Ltd.
Indirect ELISA‐based approach for comparative measurement of high‐affinity cohesin–dockerin interactions
Authors: Slutzki Michal , Barak Yoav , Reshef Dan , Schueler‐Furman Ora , Lamed Raphael , Bayer Edward A.
Published: October 2012

The interaction between the cohesin and dockerin modules serves to attach cellulolytic enzymes (carrying dockerins) to non‐catalytic scaffoldin units (carrying multiple cohesins) in cellulosome, a multienzyme plant cell‐wall degrading complex. This interaction is species‐specific, for example, the enzyme‐borne dockerin from Clostridium thermocellum bacteria binds to scaffoldin cohesins from the same bacteria but not to cohesins from Clostridium cellulolyticum and vice versa. We studied the role of interface residues, contributing either to affinity or specificity, by mutating these residues on the cohesin counterpart from C. thermocellum. The high affinity of the cognate interactions makes it difficult to evaluate the effect of these mutations by common methods used for measuring protein–protein interactions, especially when subtle discrimination between the mutants is needed. We described in this article an approach based on indirect enzyme‐linked immunosorbent assay (ELISA) that is able to detect differences in binding between the various cohesin mutants, whereas surface plasmon resonance and standard ELISA failed to distinguish between high‐affinity interactions. To be able to calculate changes in energy of binding (ΔΔG) and dissociation constants (Kd) of mutants relative to wild type, a pre‐equilibrium step was added to the standard indirect ELISA procedure. Thus, the cohesin–dockerin interaction under investigation occurs in solution rather than between soluble and immobilized proteins. Unbound dockerins are then detected through their interaction with immobilized cohesins. Because our method allows us to assess the effect of mutations on particularly tenacious protein–protein interactions much more accurately than do other prevalent methods used to measure binding affinity, we therefore suggest this approach as a method of choice for comparing relative binding in high‐affinity interactions. Copyright © 2012 John Wiley & Sons, Ltd.
Design of selective production of sophorolipids by Rhodotorula bogoriensis through nutritional requirements
Authors: Ribeiro Isabel A. , Bronze Maria R. , Castro Matilde F. , Ribeiro Maria H.L.
Published: October 2012

Rhodotorula bogoriensis is known as the producer of longer chain acidic sophorolipids (SLs) with a unique hydroxylation position where the sophorose unit is linked to the 13‐hydroxydocosanoic acid. The influence of initial inoculum concentration, hydrophilic and hydrophobic carbon, and nitrogen sources on R. bogoriensis growth and SL production was evaluated to obtain a selective SL production. Experiments took place in microtiter plates, used as minireactors, after the verification of its suitability compared with shake flasks.

The common structure of SLs is the 13‐[2′‐O‐β‐d‐glucopyranosyl‐β‐d‐glucopyranosyloxy]‐docosanoic acid SL. The analysis of the fermentation media using high‐performance liquid chromatography with evaporative light scattering detector showed the production of four main SLs, respectively, in the following forms: (i) deacetylated (peak A) (C22:0 SL), (ii) 6″monoacetylated (peak B) (C22:0‐6″Ac SL), (iii) 6′monoacetylated (peak C) (C22:0‐6′Ac SL), and (iv) 6′,6″ diacetylated (peak D) (C22:0‐6′,6″Ac SL).

The identification of compounds in SL mixtures was performed by liquid chromatography with electrospray ionization mass spectrometry analysis, and no differences were observed. Besides the four compounds detected using high‐performance liquid chromatography with evaporative light scattering detector chromatograms, three other SLs was identified, corresponding to mono‐ and diacetylated C24:0 hydroxy fatty acid SLs. To our knowledge, this work presents for the first time the production and identification of C24:0 SLs. A longer hydrophobic tail on SLs had an important role in the improvement of surface active properties.

The selection of a specific time for fermentation end and the use of different carbon (e.g. glucose, fructose, mannose, lactose, galactose, xylose) and nitrogen (e.g. peptone, (NH4)2SO4 and NaNO3) sources led to a selective production of de‐, mono‐, and diacetylated SLs by R. bogoriensis. Copyright © 2012 John Wiley & Sons, Ltd.
Molecularly imprinted composite cryogel for albumin depletion from human serum
Authors: Andaç Müge , Baydemir Gözde , Yavuz Handan , Denizli Adil
Published: October 2012

A new composite protein‐imprinted macroporous cryogel was prepared for depletion of albumin from human serum prior to use in proteom applications. Polyhydroxyethyl‐methacylate‐based molecularly ımprinted polymer (MIP) composite cryogel was prepared with high gel fraction yields up to 83%, and its morphology and porosity were characterized by Fourier transform ınfrared, scanning electron microscopy, swelling studies, flow dynamics, and surface area measurements. Selective binding experiments were performed in the presence of competitive proteins human transferrin (HTR) and myoglobin (MYB). MIP composite cryogel exhibited a high binding capacity and selectivity for human serum albumin (HSA) in the presence of HTR and MYB. The competitive adsorption amount for HSA in MIP composite cryogel is 722.1 mg/dL in the presence of competitive proteins (HTR and MYB). MIP composite cryogel column was successfully applied in the fast protein liquid chromatography system for selective depletion of albumin in human serum. The depletion ratio was highly increased by embedding beads into cryogel (85%). Finally, MIP composite cryogel can be reused many times with no apparent decrease in HSA adsorption capacity. Copyright © 2012 John Wiley & Sons, Ltd.