bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and characteristic of lactose‐oleoylchitosan and the application of its self‐aggregates as drug delivery system
Authors: Zhang Shanshan , Li Yanyan , Ren Guodong , Chen Xiguang , Meng Xiangjun
Published: April 2011

Amphiphilic polymers lactose‐oleoylchitosan (Lac‐OCH) with different degree of substitution (DS) of lactose were prepared. The chemical structure of the new chitosan derivative was tested and verified. The rheological features including solubility and viscosity of Lac‐OCH were investigated. The introduction of hydrophilic group lactose could improve the solubility of the polymer and Lac‐OCH was soluble in acetic acid solution under pH 7.0. The viscosity of Lac‐OCH decreased a little along with the increasing of DS of lactose. Lac‐OCH with high DS, middle DS, and low DS of lactose possessed small critical aggregation concentration value, and the critical aggregation concentration value rised along with the increasing of DS of lactose. However, the affect was not obvious. In brief, the CAC values were 0.0325, 0.0340, and 0.0344 mg/mL corresponding to the samples of low DS, middle DS, and high DS. Lac‐OCH, obtained by hydrophilic modified using lactose, could also form self‐assembled nanoparticles by oil/water (O/W) emulsification method comparing with OCH. The Lac‐OCH nanoparticles showed dense, axiolitic texture, and the average diameter was approximate 200 nm. The sustained‐release characteristics of Lac‐OCH nanoparticles were studied using Doxorubicin as model drug. The results revealed the promising potential of amphiphilic Lac‐OCH as drug carrier. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Preparation and characterization of polyurea/polyurethane double‐shell microcapsules containing butyl stearate through interfacial polymerization
Authors: Lu Shaofeng , Xing Jianwei , Zhang Zhaohuan , Jia Gaopeng
Published: April 2011

Double‐shell microcapsules containing butyl stearate were prepared through interfacial polymerization. The outer shell is polyurea formed through polymerization of toluene‐2,4‐diisocyanate (TDI) and diethylene triamine, and the inner shell is polyurethane (PU) formed through polymerization of TDI and polypropylene glycol 2000 (PPG2000). Styrene maleic anhydride copolymer was used as emulsifier. The effects of core to monomer ratio and dosage of PPG2000 on core content and encapsulation efficiency of microcapsules were investigated. The core content has a maximum at core to monomer ratio of 3–4, and the encapsulation efficiency has a maximum value of 95% at core to monomer ratio of 2. The prepared microcapsules were smooth and compact and have an obvious latent heat of 85 J/g. The shell structure of microcapsules was polyurea and PU. The average diameter of the microcapsules was 1–5 μm. The stabilities of the double‐shell microcapsule, such as anti‐ethanol wash and antiheat properties are obviously improved than those of single‐shell microcapsule. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Effect of MWCNTs irradiation grafting treatment on the surface properties of PBO fiber
Authors: Zhang Chunhua , Yuan Wenjing , Wang Shengrui , Liang Xifeng
Published: April 2011

The aim of this article is improved the surface properties of Poly[p‐phenylenebenzobisoxazole] (PBO) fiber with epichlorohydrin hybridized carboxylic multi walled carbon nanotubes (MWCNTs‐Ecp) grafting by using γ‐ray irradiation technology. The surface chemical properties, the surface morphology, the amount of the grafted MWCNTs on PBO fiber and the surface free energy of PBO fibers have been analyzed. The results show that MWCNTs‐Ecp have been grafted on the surface of PBO fiber by γ‐ray irradiation treatment. The surface chemical inertness and the surface smoothness of PBO fiber are significantly improved by grafting MWCNTs‐Ecp chains, the amount of the grafted MWCNTs on PBO fiber is about 11.9%, and the surface free energy of PBO fiber has an increase of 42.6% by generating some active groups such as COOH, OH, and CCl on the surface of PBO fiber. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and characterization of mesoporous carbon with narrow pore size distribution derived from rare earth–macromolecule complexes
Authors: Li Yanqiu , Li Kaixi
Published: April 2011

Mesoporous carbon with narrow pore size distribution was novelly derived from rare earth–macromolecule complexes, which were formed by the coordination between grafted novolac‐type phenolic resin and rare earth ions (Ce3+). The as‐made resins or carbons were characterized by infrared spectrum, thermogravimetry, carbon tetrachloride adsorption, nitrogen adsorption, and scanning electron microscope. The results showed that the rare earth–macromolecule complexes were formed successfully, which could promote the dispersion of rare earth elements in the precursor and further control the pore structure and pore size distribution of as‐made mesoporous carbon during steam‐activation process. The as‐made mesoporous carbon exhibited typical mesoporous structure and relatively narrow pore size distribution, and the mesoporosity of it was up to 88%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Polyurethane membranes with tunable surface properties for biomedical applications
Authors: Ignacio Carlos , Gomes Igor A. S. , Oréfice Rodrigo L.
Published: April 2011

The use of surfaces with tunable properties triggered by external stimuli is effective in controlling the interactions between biomaterials and biological entities, such as proteins and cells. The goal of this work is to prove that the presence of poly‐n‐isopropylacrylamide (P‐N‐IPAAm) chains grafted onto polyurethane (PU) membranes and used for medical wound dressings can allow the behavior of the surfaces to be shifted from hydrophobic to hydrophilic by reducing the temperature to values lower than the low critical solution temperature (LCST) of the polymer, which is close to 32°C. The manipulation of this behavior can then be used to control cell and protein adhesion on the surface. Grafting of P‐N‐IPAAm was accomplished by treating the surface of polyurethane membranes with ultraviolet (UV) radiation, followed by polymerizing the isopropylacrylamide from the modified surfaces. The wettability of the surfaces was studied using contact angle measurements as a function of temperature. Infrared spectroscopy was also used to characterize these modified surfaces. The ability of the grafted surfaces to allow adsorption of proteins was evaluated as a function of temperature. The results showed that the amount of proteins adsorbed on the polyurethane membranes could be radically changed by altering the temperature above or below 32°C. In vivo biocompatibility tests were performed on P‐N‐IPPAm samples, and no indication of toxicity was noted after 7 days of implantation. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis and properties of polyurethane‐urea‐based liquid bandage materials
Authors: Choi Soo‐Jeong , Lee Jung‐Hee , Lee Young‐Hee , Hwang Dae‐Youn , Kim Han‐Do
Published: April 2011

To obtain ideal liquid bandage polymer materials, a series of polyurethane‐urea dispersions were synthesized from 4,4′‐diisocyanato dicyclohexylmethane (H12MDI) and ethylene diamine with different molar ratio of polyol blend [polyethylene glycol (PEG, Mn = 2000 g/mol)/hydroxy terminated poly(dimethylsiloxane) (PDMS, Mn = ∼ 550 g/mol)] and acetone/ethanol as a solvent. The effect of PDMS content in PEG/PDMS on the viscosity, mechanical properties, water contact angle/surface energy, insolubility in water (%), water absorption (%), equilibrium water content (%), and water vapor transmission rate (g m−2 day−1) of polyurethane‐urea films was investigated. As PDMS content increased, the water contact angle, insolubility in water, and tensile strength/elastic recovery of film sample increased; however, the surface energy, water absorption (%), equilibrium water content (%), and water vapor transmission rate (g m−2 day−1) of film sample decreased. By a wound‐healing evaluation using a full‐thickness rat model experiment, it was found that a wound covered with a typical polyurethane‐urea liquid bandage film (PD2 sample) was filled with new epithelium without any significant adverse reactions. These results suggest that the polyurethane‐urea‐based liquid bandages (samples: PD2 and PD3) prepared in this study may have high potential as new wound dressing materials, which provide and maintain the adequate wet environment required to prevent scab formation and dehydration of the wound bed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Influence of esterification crosslinking structures of rayon fibers with 1,2,3,4‐butanetetracarboxylic acid on tensile properties
Authors: Wang Xiaqin , Zhou Xingping , Wu Lishun , Zhang Jingfang , Li Xuefeng
Published: April 2011

1,2,3,4‐Butanetetracarboxylic acid (BTCA) was applied to crosslink amorphous regions of cotton‐type rayon fibers via anhydride‐mediated esterification for the purpose of a molecular‐level control over macroscopic properties. Formation of intrafiber crosslinked structures of the rayon fibers was a facile and efficient method to diminish swelling degree and enhance tensile properties. Crosslinking was conducted under a series of curing temperature and various dosages of BTCA with the presence of sodium hypophosphite as the catalyst for anhydride formation. It was found that crosslinking conditions, both the curing temperature and dosage of the crosslinking agent, made notable impacts on the crosslinking behaviors of the rayon fibers. The dry and wet tensile strength of the rayon fibers were optimized for both the dosage of the crosslinking agent and the curing temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Novel functional nitrile butadiene rubber/magnetite nano composites for NTCR thermistors application
Authors: Al‐Juaid Salih S. , El‐Mossalamy E. H. , M. Arafa H. , Al‐Ghamdi A. A. , Daiem A. M. Abdel , El‐Tantawy Farid
Published: April 2011

A new negative temperature coefficient of resistor (NTCR) thermistors based on nitrile butadiene rubber/magnetite (NBR/Fe3O4) nanocomposites were successfully fabricated by conventional roll milling technique. X‐ray diffraction and transmission (TEM) analysis showed that the product is mainly magnetite nanoparticles with diameter of 10‐13 nm. The microstructure of (NBR/Fe3O4) nanocomposites were examined by scanning electron microscopy (SEM) and FTIR spectroscopy. The dispersion of magnetite nanoparticles in the NBR rubber matrix and interfacial bonding between them were rather good. The thermal stability of nanocomposites was also obviously improved with the inclusion of the magnetite nanoparticles. The thermal conductivity, thermal diffusivity and specific heat of nanocomposites were investigated. The electrical conductivity of the NBR/Fe3O4 increases with the rise in temperature exhibiting a typical negative temperature coefficient of resistance (NTCR) behavior like a semiconductor. The nature of the temperature variation of electrical conductivity and values of activation and hopping energy, suggest that the transport conduction process is controlled by hopping mechanism. Values of characteristics parameters of the thermistors like thermistor constant, thermistor sensitivity and thermistor stability is quite good for practical application as NTCR devices at high temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
The mechanism and energy of activation of the melting of poly (ε‐caprolactone) with and without prior treatment with span 80
Authors: Fraga‐López Francisco , Manuel Martínez‐Ageitos J. , Rodríguez‐Núñez Eugenio , Blanco‐Mendez José , Luzardo‐Álvarez Asteria , Calvo‐Carnota Emilio , Jiménez‐Carrillo Lisbeth
Published: April 2011

Differential scanning calorimetry (DSC) is used to determine the energy of activation and melting mechanism of PCL and of mixtures of PCL with the surfactant Span 80. The melting of poly(ε‐caprolactone) follows a nucleation and growth model with an Avrami exponent of 4. Addition of Span 80 reduces the energy of activation of this process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Synthesis of biodegradable material poly(lactic acid‐co‐aspartic acid) via direct melt polycondensation and its characterization
Authors: Ye Rui‐Rong , Wang Zhao‐Yang , Wang Qun‐Fang , Yang Kai , Luo Shi‐He
Published: April 2011

Directly starting from L‐lactic acid (LA) and L‐aspartic acid (Asp), biodegradable material poly(lactic acid‐co‐aspartic acid) [P(LA‐co‐Asp)] was synthesized via melt polycondensation. The synthetic conditions, including type and dosage of catalyst, temperature, and time of copolymerization, and influence of molar feed ratio were discussed. The structure and properties of the copolymer were systematically characterized with FTIR, 1H‐NMR, GPC, DSC, and XRD. With the increase of Asp in the feed, [η] and Mw decreased, and the crystallinity of the copolymer disappeared gradually. Compared to the homopolymer, poly(L‐lactic acid) synthesized via melt polycondensation and the copolymer P(LA‐co‐Asp) had a higher glass‐transition temperature (Tg). The copolymer P(LA‐co‐Asp) with Mw of 4400–24300 Da was obtained, which could meet the demand as a drug‐delivery carrier material. Compared to the ring‐opening polymerization of the cyclic intermediates, including lactide, the novel direct copolycondensation method was a cheap and practical method for the synthesis of copolymer P(LA‐co‐Asp) as biomedical materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Dielectric properties of new fully conjugated 2H‐ and metal‐pyrazinoporphyrazine network polymers
Authors: Abdel‐Razik H. H. , El‐Sayed S. , Hassen A.
Published: April 2011

2,7‐Di‐tert‐butylpyrene was oxidized to 2,7‐di‐tert‐butylpyrene‐4,5,9,10‐tetraone. The latter through condensation reaction with vicinal diamine such as diaminomaleodinitrile afforded heterocyclic monomer, 2,7‐di‐tert‐butyl pyrene[4,5][9,10]bis(2,3‐pyrazine‐5,6‐dinitrile), which was cyclotetramerized to the corresponding 2H‐ and metal‐pyrazinoporphyrazine‐based network polymers (2H‐PyzPz and M‐PyzPz, M = Co, Ni, Zn, or Cu). Elemental analytical results, Infrared, and NMR spectral data of the new prepared molecules are consistent with their assigned formulations. Molecular masses and metal contents of the synthesized polymers proved to be of high molecular masses, which confirm the efficiency of tetramerization polymerization and complexation reactions. Dielectric permittivity, ε′, loss tangent, tan δ, and ac conductivity, σac(ω), of 2H‐PyzPz and M‐PyzPz films were studied as a function of temperature and frequency. It was found that dielectric permittivity, ε′, decreases with the increase of frequency and increases with the increase in temperature. Ac conductivity, σac(ω), is found to vary as Bωs and the frequency exponent, s, is less than unity around room temperature indicating a dominant hopping process. On the other hand, σac(T) of all samples is thermally activated with low activation energies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.
Synthesis, characterization, and properties of poly(amide‐imide)s from a new diimide‐diacid by direct polycondensation with various diamines
Authors: Ghaemy Mousa , Movagharnezhad Nasim , Khajeh Soheila
Published: April 2011

A new diimide‐diacid, 2,2′‐(5‐(4‐(4‐(4,5‐diphenyil‐1H‐imidazol‐2‐yl)phenoxy)phenylcarbam‐oyl)‐1,3‐phenylenebis(1,3‐dioxoisoindoline‐5‐carboxylic‐acid)(DADA), was synthesized from the reaction between trimellitic anhydride and a new diamine, N‐(4‐(4‐(4,5‐diphenyl‐1H‐imidazole‐2‐yl)phenoxylphenyl)‐3,5‐diaminobenzamide(NIDA). The direct polycondensation of DADA with various diamines was carried out in NMP in the presence of triphenylposphite and pyridine as condensing agents. The resulting poly(amide‐imide)s (PAIs) were amorphous, readily soluble in many polar aprotic solvents and showed inherent viscosities of 0.35–0.47 dL/g. According to thermal analysis, these polymers exhibited glass transition temperatures (Tgs) in the range of 207–271°C, and their initial decomposition temperature (Ti) varied from 260 to 330°C and temperature of 10% weight loss (T10) from 325 to 520°C in N2. These polymers in NMP solution exhibited strong UV–vis absorption maxima at 320 nm and their fluorescence emission peaks appeared around 425–450 nm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.
Semiconductor‐assisted self‐cleaning polymeric fibers based on zinc oxide nanoparticles
Authors: Moafi Hadi Fallah , Shojaie Abdollah Fallah , Zanjanchi Mohammad Ali
Published: April 2011

Self‐cleaning polymeric fibers have been successfully prepared by depositing ZnO nanoparticle onto wool and polyacrylonitrile (PAN) fibers with good compatibility and significant photocatalytic self‐cleaning activity using the sol‐gel process at ambient temperature. scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X‐ray diffraction, Brunauer‐Emmett‐Teller surface area analysis, and thermogravimetric analysis have been adopted as the characterization techniques. Transmission electron microscopy studies revealed presence of zinc oxide nanoparticles with 10–15 nm in size. Brunauer‐Emmett‐Teller measurement showed surface area of 48 m2/g for the ZnO nanoparticles. Photocatalytic activity of the self‐cleaning materials were tested by measuring the photo‐assisted degradation of methylene blue (MB) and eosin yellowish (EY) under ultraviolet‐visible illumination. The results indicate that both of the ZnO‐coated polyacrylonitrile and ZnO‐coated wool fibers acquire photocatalytic activity toward dyes degradation. The photocatalytic activity of the treated fibers is maintained upon several numbers of photodegradation cycles. This facile and cheap preparation technique can be also applied to new polymeric fabrics to produce self‐cleaning materials for industrial application. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Focal fat lesions at vertebral corners on magnetic resonance imaging predict the development of new syndesmophytes in ankylosing spondylitis
Authors: Chiowchanwisawakit Praveena , Lambert Robert G. W. , Conner‐Spady Barbara , Maksymowych Walter P.
Published: April 2011

Objective

Focal fat infiltration is frequently visible on magnetic resonance imaging (MRI) of the spine in patients with ankylosing spondylitis (AS) and likely reflects postinflammatory tissue metaplasia. To support the concept of coupling between inflammation and new bone formation, we tested the hypothesis that focal fat infiltration at a vertebral corner is more likely to evolve into a de novo syndesmophyte.

Methods

MRI scans were obtained at baseline and radiographs were obtained at baseline and 2 years in 100 AS patients from 2 cohorts: a clinical trial cohort (n = 38) and an observational cohort (n = 62). In the clinical trial cohort, patients were randomized to receive anti–tumor necrosis factor (anti‐TNF) therapy or placebo for 12–24 weeks and then open‐label treatment for 2 years. In the observational cohort, patients received either standard therapy (n = 36) or anti‐TNF therapy (n = 26) for 2 years. Vertebral corner inflammation and fat infiltration were assessed independently by pairs of readers who were blinded with regard to the radiographic findings.

Results

New syndesmophytes developed significantly more frequently in vertebral corners with fat in both the clinical trial (10.2%) and the observational (6.5%) cohort as compared to those without either feature on baseline MRI (3.1% [P = 0.008] and 1.4% [P = 0.0002], respectively). Adjusting for within‐patient variations in baseline syndesmophytes/ankylosis, vertebral corners that were fat‐positive/inflammation‐positive significantly predicted new syndesmophytes, with an odds ratio (OR) of 7.6 (95% confidence interval [95% CI] 1.5–38.5 [P = 0.01]), while a model that included baseline variations in both fat and inflammation showed an OR of 5.8 (95% CI 2.2–15.3 [P < 0.001]) for inflammation and an OR of 1.9 (95% CI 0.9–4.1 [P = 0.1]) for fat.

Conclusion

Our data lend support to the hypothesis that inflammatory lesions evolve into new bone through a process of tissue metaplasia that includes fat infiltration.
Hypoxia induces mitochondrial mutagenesis and dysfunction in inflammatory arthritis
Authors: Biniecka Monika , Fox Edward , Gao Wei , Ng Chin Teck , Veale Douglas J. , Fearon Ursula , O'Sullivan Jacintha
Published: April 2011

Objective

To assess the levels and spectrum of mitochondrial DNA (mtDNA) point mutations in synovial tissue from patients with inflammatory arthritis in relation to in vivo hypoxia and oxidative stress levels.

Methods

Random Mutation Capture assay was used to quantitatively evaluate alterations of the synovial mitochondrial genome. In vivo tissue oxygen levels (tPO2) were measured at arthroscopy using a Licox probe. Synovial expression of lipid peroxidation (4‐hydroxynonenal [4‐HNE]) and mitochondrial cytochrome c oxidase subunit II (CytcO II) deficiency were assessed by immunohistochemistry. In vitro levels of mtDNA point mutations, reactive oxygen species (ROS), mitochondrial membrane potential, and markers of oxidative DNA damage (8‐oxo‐7,8‐dihydro‐2′‐deoxyguanine [8‐oxodG]) and lipid peroxidation (4‐HNE) were determined in human synoviocytes under normoxia and hypoxia (1%) in the presence or absence of superoxide dismutase (SOD) or N‐acetylcysteine (NAC) or a hydroxylase inhibitor (dimethyloxalylglycine [DMOG]). Patients were categorized according to their in vivo tPO2 level (<20 mm Hg or >20 mm Hg), and mtDNA point mutations, immunochemistry features, and stress markers were compared between groups.

Results

The median tPO2 level in synovial tissue indicated significant hypoxia (25.47 mm Hg). Higher frequency of mtDNA mutations was associated with reduced in vivo oxygen tension (P = 0.05) and with higher synovial 4‐HNE cytoplasmic expression (P = 0.04). Synovial expression of CytcO II correlated with in vivo tPO2 levels (P = 0.03), and levels were lower in patients with tPO2 <20 mm Hg (P < 0.05). In vitro levels of mtDNA mutations, ROS, mitochondrial membrane potential, 8‐oxo‐dG, and 4‐HNE were higher in synoviocytes exposed to 1% hypoxia (P < 0.05); all of these increased levels were rescued by SOD and DMOG and, with the exception of ROS, by NAC.

Conclusion

These findings demonstrate that hypoxia‐induced mitochondrial dysfunction drives mitochondrial genome mutagenesis, and antioxidants significantly rescue these events.
Synthesis and luminescence properties of Ca3Ga2Si3O12:RE3+ (RE = Eu/Tb) powder phosphors
Authors: Bhushana Reddy M. , Sailaja S. , Vemasevana Raju K. , Nageswara Raju C. , Giridhar P. , Vengala Rao B. , Sudhakar Reddy B.
Published: April 2011

Rare earth ions (Eu3+ or Tb3+)‐activated Ca3 Ga2 Si3O12 (CaGaSi) phosphors were synthesized by using a sol–gel method. Photoluminescence spectra of Eu3+:CaGaSi phosphors exhibited five emission bands at 578, 592, 612, 652 and 701 nm, which were assigned to the transitions (5D0 → 7F0, 7F1, 7F2, 7F3 and 7F4), respectively, with an excitation wavelength of λexci = 392 nm. Among these, the transition 5D0 → 7F2 (612 nm) displayed bright red emission. In the case of Tb3+:CaGaSi phosphors, four emission bands were observed at 488 (5D4 → 7F6), 543 (5D4 → 7F5), 584 (5D4 → 7F4) and 614 nm (5D4 → 7F3) from the measurement of PL spectra with λexci = 376 nm. Among these, the transition 5D4 → 7F5 at 543 nm displayed bright green emission. The structure and morphology of the phosphors were studied from the measurements of X‐ray diffraction (XRD), scanning electron microscopy (SEM) and energy‐dispersive X‐ray analysis (EDAX) results. Copyright © 2011 John Wiley & Sons, Ltd.
Sodium azide as a specific quencher of singlet oxygen during chemiluminescent detection by luminol andCypridinaluciferin analogues
Authors: Bancirova Martina
Published: April 2011

Reactive oxygen species (ROS) are presently thought to play important role in an increasing number of the physiological and pathological processes in living organisms. Various chemiluminescent (CL) compounds have been studied in order to find suitable and specific probes for the detection of particular ROS species. The CL of luminol is known to be non‐specific and can be induced by various oxidants. TwoCypridinaluciferin analogues, CLA and MCLA, have been used for the detection of ROSin vivo. CLAs are thought to emit light only when reacting with superoxide and singlet oxygen. It is possible to distinguish the particular ROS by using a specific quencher or scavenger, e.g. superoxide dismutase (SOD) or sodium azide (NaN3). The CL reactions of luminol (3‐aminophthalhydrazide), CLA [2‐methyl‐6‐phenyl‐3,7‐dihydroimidazo(1,2α) pyrazin‐3‐one] and MCLA [2‐methyl‐6‐(p‐methoxyphenyl)‐3,7‐dihydroimidazo(1,2α) pyrazin‐3‐one] were studied in three hydrogen peroxide decomposition systems (H2O2–HRP; H2O2–CuSO4; and H2O2–NaOCl). The measurements were carried out in phosphate buffer, pH 7.4, at 25 °C, using a luminometer (Fluoroskan Ascent FL and Sirius C). NaN3was used as the specific quencher of singlet oxygen. The results demonstrate that the proclaimed specifity of the CL ofCypridinaluciferin analogues towards singlet oxygen has to be discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Filtration kinetics of chitosan separation by electrofiltration
Authors: Gözke Gözde , Kirschhöfer Frank , Heissler Stefan , Trutnau Mirko , Brenner‐Weiss Gerald , Ondruschka Jelka , Obst Ursula , Posten Clemens
Published: April 2011

Downstream processing of chitosan requires several technological steps that contribute to the total production costs. Precipitation and especially evaporation are energy‐consuming processes, resulting in higher costs and limiting industrial scale production. This study investigated the filtration kinetics of chitosan derived from cell walls of fungi and from exoskeletons of arthropods by electrofiltration, an alternative method, thus reducing the downstream processing steps and costs. Experiments with different voltages and pressures were conducted in order to demonstrate the effect of both parameters on filtration kinetics. The concentration of the biopolymer was obtained by the average factor of 40 by applying an electric field of 4 V/mm and pressure of 4 bars. A series of analytical experiments demonstrated the lack of structural and functional changes in chitosan molecules after electrofiltration. These results, combined with the reduction of energy and processing time, define the investigated method as a promising downstream step in the chitosan production technology.
A single, selective and simple validated method for simultaneous estimation of amiloride and hydrochlorothiazide in human plasma by liquid chromatography–tandem mass spectrometry
Authors: Jangid Arvind G. , Tale Rajesh H. , Vaidya Vikas V.
Published: April 2011

A single, simple and selective method for simultaneous estimation of amiloride and hydrochlorothiazide in human plasma was validated using triamterine and hydrochlorothiazide13C,d2 as internal standard. The compounds were separated on a reverse‐phase column with an isocratic mobile phase consisting of 2 mm ammonium acetate pH 3.0 and acetonitrile (30:70, v/v) and detected by tandem mass spectrometry with positive/negative ion mode. The analytes and internal standards were extracted from plasma using simple solid phase extraction. The ion transitions recorded in multiple reaction monitoring mode were m/z 230.1 → 116.0 for amiloride, m/z 254.1 → 237.1 for internal standard, triamterine in positive mode and m/z 296.1 → 204.9 for hydrochlorothiazide, m/z 299.2 → 205.8 for internal standard, hydrochlorothiazide13C,d2 in negative ion mode. Linearity in plasma was observed over the concentration range 0.1–10 ng/mL for amiloride and 5.0–500.0 ng/mL for hydrochlorothiazide. The mean recovery was 41.1 and 81.5% for amiloride and hydrochlorothiazide respectively. The coefficient of variation of the assay was less than 11.2 and 5.2% for amiloride and hydrochlorothiazide, respectively, and the accuracy was 89.0–98.1 and 96.6–102.9% for amiloride and hydrochlorothiazide, respectively. The validated method can be applied to the pharmacokinetic study of amiloride and hydrochlorothiazide. Copyright © 2011 John Wiley & Sons, Ltd.
Assessment of cytotoxicity, apoptosis and DNA damages in Colo320 colorectal cancer cells selected for oxaliplatin resistance
Authors: Virag Piroska , Brie Ioana , Fischer‐Fodor Eva , Perde‐Schrepler Maria , Tatomir Corina , Balacescu Ovidiu , Irimie Alexandru , Postescu Ion Dan
Published: April 2011

Despite the notable efficacy of oxaliplatin in the treatment of colorectal cancers, the metastatic tumours ultimately become resistant to the drug. This study investigated whether the oxaliplatin‐resistant cells display different behaviour to this drug versus the sensitive cells and if this difference may be further exploited into the clinical treatments improvement. In order to establish a stable cell line resistant to oxaliplatin, a human colorectal cancer cell line (Colo320) was exposed to increasing doses of the drug up to the clinically relevant plasma concentration. Four cell groups with different levels of chemoresistance were subjected to additional doses of oxaliplatin, and their cytotoxicity, apoptosis and DNA damage production were assessed. Cells selected for resistance to oxaliplatin reacted differently to the application of additional doses of the drug, displaying lower toxicity and cellular death and fewer DNA cross‐links formation, in accordance with the extent of the oxaliplatin pretreatments. As the cross‐links formation by oxaliplatin being the main cause for cytotoxicity of this drug and a correlation between cytotoxicity and clinical outcome being shown repeatedly, we consider that the evaluation of oxaliplatin‐induced cytotoxicity, apoptosis and DNA damage could be a valuable tool to assess the tumour cells sensitivity and thus to predict the response to chemotherapy. Copyright © 2011 John Wiley & Sons, Ltd.
Chemical Synthesis and Expression of the HIV‐1 Rev Protein
Authors: Siman Peter , Blatt Ofrah , Moyal Tal , Danieli Tsafi , Lebendiker Mario , Lashuel Hilal A. , Friedler Assaf , Brik Ashraf
Published: April 2011

The HIV‐1 Rev protein is responsible for shuttling partially spliced and unspliced viral mRNA out of the nucleus. This is a crucial step in the HIV‐1 lifecycle, thus making Rev an attractive target for the design of anti‐HIV drugs. Despite its importance, there is a lack of structural, biophysical, and quantitative information about Rev. This is mainly because of its tendency to undergo self‐assembly and aggregation; this makes it very difficult to express and handle. To address this knowledge gap, we have developed two new highly efficient and reproducible methods to prepare Rev in large quantities for biochemical and structural studies: 1) Chemical synthesis by using native chemical ligation coupled with desulfurization. Notably, we have optimized our synthesis to allow for a one‐pot approach for the ligation and desulfurization steps; this reduced the number of purification steps and enabled the obtaining of desired protein in excellent yield. Several challenges emerged during the design of this Rev synthesis, such as racemization, reduced solubility, formylation during thioester synthesis, and the necessity for using orthogonal protection during desulfurization; solutions to these problems were found. 2) A new method for expression and purification by using a vector that contained an HLT tag, followed by purification with a Ni column, a cation exchange column, and gel filtration. Both methods yielded highly pure and folded Rev. The CD spectra of the synthetic and recombinant Rev proteins were identical, and consistent with a predominantly helical structure. These advances should facilitate future studies that aim at a better understanding of the structure and function of the protein.
Supported Transition Metal Catalysts for Hydrodechlorination Reactions
Authors: Keane Mark A.
Published: April 2011

As halogenated waste is xenobiotic with no analogous compounds in nature, there is no natural means of ameliorating the negative environmental impact caused by halo‐organic emissions. The presence of organo‐halogens in effluent discharges is of increasing concern, owing to the mounting evidence of adverse stratospheric ozone, ecological effects, and the impact on public health. There is a pressing need, driven by legislative and financial imperatives, to develop robust and efficient treatment technologies. This Review considers the application of catalytic hydrodechlorination (HDC) as a progressive approach to the conversion and recycling of toxic chloro‐compounds. An overview of the existing treatment technologies is provided with an assessment of the benefits of catalytic HDC over separation/oxidation methodologies. Taking the transformation of chloro‐aromatics, the catalytic HDC of liquid and gas phase reactants is considered in turn with a critical analysis of the pertinent literature. Two “case studies” are considered in detail: i) the liquid phase HDC of chlorophenols over alumina supported palladium, focusing on the critical process and catalyst structural characteristics that influence HDC performance; ii) the gas phase conversion of a range of halogenated (Cl and Br) aromatics over silica supported nickel with an examination of the dehalogenation activity/selectivity response as a function of the nature of the aromatic reactant.
Synthesis, Structure, Aggregation‐Induced Emission, Self‐Assembly, and Electron Mobility of 2,5‐Bis(triphenylsilylethynyl)‐3,4‐diphenylsiloles
Authors: Zhao Zujin , Liu Dandan , Mahtab Faisal , Xin Linyuan , Shen Zhongfang , Yu Yong , Chan Carrie Y. K. , Lu Ping , Lam Jacky W. Y. , Sung Herman H. Y. , Williams Ian D. , Yang Bing , Ma Yuguang , Tang Ben Zhong
Published: April 2011

2,5‐Bis(triphenylsilylethynyl)‐3,4‐diphenylsiloles with different 1,1‐substituents [XYSi(CPh)2(CCCSiPh3)2] (Ph=phenyl) were synthesized in high yields by the Sonogashira coupling of 2,5‐dibromo‐3,4‐diphenylsiloles with triphenylsilylacetylene, and two of these were characterized crystallographically. Crystal structures and theoretical calculations showed that the new silole molecules had higher conjugation than 2,5‐diarylsiloles. They possessed low HOMO and LUMO energy levels due to the electron‐withdrawing effect of the triphenylsilylethynyl groups. Cyclic voltammetry analysis revealed low electron affinities, which were comparable to those of perfluoroarylsiloles. B3LYP/6‐31* calculations demonstrated that the new siloles possessed large reorganization energies for electron and hole transfers and high electron mobilities. A mobility of up to 1.2×10−5 cm2 V−1 s−1 was obtained by the transient electroluminescence method, which was about fivefold higher than that of tris(8‐hydroxyquinolinato)aluminum, a widely used electron‐transport material, under the same conditions. All of the silole molecules possessed high thermal stability. Although, their solutions were weakly emissive, their nanoparticle suspensions and thin films emitted intense blue‐green light upon photoexcitation, demonstrating a novel feature of aggregation‐induced emission (AIE). Polarized emissions were observed in the silole crystals. The addition of solvents, which did not dissolve the silole molecules, into silole‐containing solutions caused self‐assembly of the molecules, which produced macroscopic fibrils with strong light emissions.
Signal Transducers and Enzyme Cofactors are Susceptible to Oxidation by Nanographite Impurities in Carbon Nanotube Materials
Authors: J. E. Stuart Emma , Pumera Martin
Published: April 2011

Carbon nanotubes (CNTs) are often employed in biofuel cells, artificial photosystems and bioelectronics in order to enhance electron transfer and to efficiently shuttle electrons between redox active molecules and the electrode surface. However, it should be noted that typical CNTs are highly heterogeneous materials, containing large amounts of impurities. Herein, we report the influence of nanographite impurities contained within CNTs upon the redox properties of signal transducers and enzyme cofactors that are vital for the functioning of biofuel cells, artificial leaves and bioelectronics as well as for the survival of living organisms. We investigate the susceptibility of tyrosine and tryptophan, amino acids involved in electron transfer and biorecognition reactions as well in the synthesis of neurotransmitters, in addition we also consider the susceptibility of the principal electron carrier β‐nicotinamide adenine dinucleotide. We conclude that nanographite impurities within CNTs are responsible for the “electrocatalytic” oxidation of NADH and two amino acids involved in signal transduction, tyrosine and tryptophan. Our findings are of high importance for both industrial and biomedical applications.
UV–Raman and NMR Spectroscopic Studies on the Crystallization of Zeolite A and a New Synthetic Route
Authors: Ren Limin , Li Caijin , Fan Fengtao , Guo Qiang , Liang Desheng , Feng Zhaochi , Li Can , Li Shougui , Xiao Feng‐Shou
Published: April 2011

UV–Raman and NMR spectroscopy, combined with other techniques, have been used to characterize crystallization of zeolite A. In situ UV–Raman spectroscopy shows that the starting gel for crystallization of zeolite A contains a lot of four‐ring (4R) building units and the appearance of six‐ring (6R) building blocks is the signal for crystal formation. 29Si NMR spectroscopy results suggest that the starting gel is double four‐ring (D4R) rich and during crystallization of zeolite A both α and β cages appear. 27Al NMR spectroscopy results indicate the absence of Al (2Si) species in the starting gel, suggesting the absence of single 4R building units in the starting gel. Furthermore, composition analysis of both solid and liquid samples shows that the solid rather than liquid phase predominates for the crystallization of zeolite A. Therefore, it is proposed that the crystallization of zeolite A mainly occurs in the solid phase by self‐assembly or rearrangement starting from the zeolite building units mainly consisting of D4R. The essential role of D4R is directly confirmed by successful conversion from a solution of D4R to zeolite A in the presence of NaCl, and the importance of solid phase is reasonably demonstrated by the successful synthesis of zeolite A from a dry aluminosilicate gel. By considering that the solid phase has a major contribution to crystallization, a novel route was designed to synthesizing zeolite A from the raw materials water glass (Na2SiO3 in aqueous solution) and NaAlO2, without additional water and NaOH; this route not only simplifies synthetic procedures, but reduces water consumption.
Chiral Monofluorobenzyl Carbanions: Synthesis of Enantiopure β‐Fluorinated β‐Phenylethylamines
Authors: García Ruano José L. , Parra Alejandro , Alonso Inés , Fustero Santos , del Pozo Carlos , Arroyo Yolanda , Sanz‐Tejedor Ascensión
Published: April 2011

The preparation of a stabilized monofluorobenzyl carbanion by means of a remote homochiral sulfinyl group and its completely stereoselective reactions with N‐p‐tolylsulfinylimines are described. The use of these reactions followed by the simultaneous removal of both chiral auxiliaries with tBuLi, which occurs without epimerization at the benzylic position, provides the quickest entry to enantiomerically pure β‐fluorinated β‐phenylethylamines.
Numerical Determination of the Translocation Rate of Particles Through a Pore
Authors: Geier Stephanie , Hernández‐Ortiz Juan P. , de Pablo Juan J.
Published: April 2011

Die Bewegung von großen Partikeln durch enge Poren hindurch ist ein sehr seltenes Ereignis. Deshalb ist die Bestimmung der Durchgangsrate mit Hilfe von konventionellen Simulationsmethoden wenig effizient. Die Durchgangsrate eines kugelförmigen Partikels durch eine Porengeometrie wurde in dieser Arbeit mit Hilfe des Forward Flux Sampling (FFS) bestimmt und mit dem Ergebnis konventioneller Simulationsmethoden verglichen.
Investigation on the effect of blade patterns on continuous solid mixing performance
Authors: Gao Yijie , Ierapetritou Marianthi , Muzzio Fernando
Published: April 2011

Previous experimental and computational work has demonstrated that the geometry of the impeller has a significant effect on the mixing performance of continuous powder mixers. In particular, different blade patterns using either all blades pushing the powder forward (‘forward pattern’) are less effective than patterns where some of the blades push the powder backwards (‘alternate pattern’). In this article, we use Discrete Element Method to investigate this issue, as well as to examine whether batch mixers can be used to estimate the cross‐sectional mixing rate of continuous mixing process. Mixing and flow of particles are examined in simple geometries consisting of a cylindrical cross‐section agitated by impellers. In these geometries, blades are designed ‘forward’ and ‘alternate’ to study different blade patterns. Periodic boundary conditions are used to approximate an idealised cross‐section of a continuous mixer. In addition, to examine whether an experimentally realisable batch system could be used to validate these cross‐sectional simulations, we examine mixing in geometries with solid end walls. Performance in these elemental systems is compared qualitatively in terms of radially averaged velocity vectors, and quantitatively in terms of the mixing rate and the fill level profile. Results show that end walls and symmetric blade pairs of the ‘alternate’ blade patterns lead to faster mixing. Non‐symmetric elemental systems display both increased fill level uniformity and similar mixing performance for both blade patterns. Results demonstrate the need for caution when attempting to use batch mixing information to estimate the cross‐sectional mixing rate of continuous powder mixers.
Decitabine and suberoylanilide hydroxamic acid (SAHA) inhibit growth of ovarian cancer cell lines and xenografts while inducing expression of imprinted tumor suppressor genes, apoptosis, G2/M arrest, and autophagy
Authors: Chen Min‐Yu , Liao Warren S.‐L. , Lu Zhen , Bornmann William G. , Hennessey Violeta , Washington Michele N. , Rosner Gary L. , Yu Yinhua , Ahmed Ahmed Ashour , Bast Robert C.
Published: April 2011

BACKGROUND:

Epigenetic therapy has had a significant impact on the management of hematologic malignancies, but its role in the treatment of ovarian cancer remains to be defined. The authors previously demonstrated that treatment of ovarian and breast cancer cells with DNA methyltransferase and histone deacetylase (HDAC) inhibitors can up‐regulate the expression of imprinted tumor suppressors. In this study, demethylating agents and HDAC inhibitors were tested for their ability to induce re‐expression of tumor suppressor genes, inhibiting growth of ovarian cancer cells in culture and in xenografts.

METHODS:

Ovarian cancer cells (Hey and SKOv3) were treated with demethylating agents (5‐aza‐2′‐deoxycytidine [DAC] or 5‐azacitidine [AZA]) or with HDAC inhibitors (suberoylanilide hydroxamic acid [SAHA] or trichostatin A [TSA]) to determine their impact on cellular proliferation, cell cycle regulation, apoptosis, autophagy, and re‐expression of 2 growth inhibitory imprinted tumor suppressor genes: guanosine triphosphate‐binding Di‐RAS‐like 3 (ARHI) and paternally expressed 3 (PEG3). The in vivo activities of DAC and SAHA were assessed in a Hey xenograft model.

RESULTS:

The combination of DAC and SAHA produced synergistic inhibition of Hey and SKOv3 cell growth by apoptosis and cell cycle arrest. DAC induced autophagy in Hey cells that was enhanced by SAHA. Treatment with both agents induced re‐expression of ARHI and PEG3 in cultured cells and in xenografts, correlating with growth inhibition. Knockdown of ARHI decreased DAC‐induced autophagy. DAC and SAHA inhibited the growth of Hey xenografts and induced autophagy in vivo.

CONCLUSIONS:

A combination of DAC and SAHA inhibited ovarian cancer growth while inducing apoptosis, G2/M arrest, autophagy, and re‐expression of imprinted tumor suppressor genes. Cancer 2011;. © 2011 American Cancer Society.
Analysis of differential shrinkage in frozen brain sections and its implications for the use of guard zones in stereology
Authors: Carlo C.N. , Stevens C.F.
Published: April 2011

Increasing numbers of neuroanatomists are using stereological methods, and unbiased stereological estimation rules recommend the use of guard zones with the optical disector method to count objects of interest within a volume. Although these methods are statistically unbiased, we believe there is a need to explore sources of systematic bias (e.g., effects of tissue processing and sectioning) that may be affecting estimates of object number. Toward this end, we evaluated neuron distribution through, and tissue shrinkage in, non‐embedded tissue cut on a freezing microtome. Our data show that in the x‐ and y‐planes there are minimal changes in tissue area during tissue processing, sectioning, and staining. In the z‐axis (perpendicular to the cutting surface), however, sections shrink to ∼25% of the cut thickness. This z‐axis shrinkage was quite variable between sections (coefficient of variation about 10%) but stable within the same section (coefficient of variation about 3%). Lastly, individual particle densities are non‐uniform through the thickness of the section when the densities should have been uniform. We advise experimenters to use a new protocol, a modified optical disector, for estimation when objects to be counted are marked such that the x‐, y‐, and z‐coordinates are recorded through the full thickness of a section and guard zones are applied post data collection based on the characteristics of the object distribution along the z‐axis. It is likely that individual experiments with different embedding materials and histological processing steps could require guard zones of varying sizes, or none at all, depending on object distribution in the z‐axis. J. Comp. Neurol. 519:2803–2810, 2011. © 2011 Wiley‐Liss, Inc.
Distribution and physiological effects of B‐type allatostatins (myoinhibitory peptides, MIPs) in the stomatogastric nervous system of the crab Cancer borealis
Authors: Szabo Theresa M. , Chen Ruibing , Goeritz Marie L. , Maloney Ryan T. , Tang Lamont S. , Li Lingjun , Marder Eve
Published: April 2011

The crustacean stomatogastric ganglion (STG) is modulated by a large number of amines and neuropeptides that are found in descending pathways from anterior ganglia or reach the STG via the hemolymph. Among these are the allatostatin (AST) B types, also known as myoinhibitory peptides (MIPs). We used mass spectrometry to determine the sequences of nine members of the AST‐B family of peptides that were found in the stomatogastric nervous system of the crab Cancer borealis. We raised an antibody against Cancer borealis allatostatin‐B1 (CbAST‐B1; VPNDWAHFRGSWa) and used it to map the distribution of CbAST‐B1‐like immunoreactivity (‐LI) in the stomatogastric nervous system. CbAST‐B1‐LI was found in neurons and neuropil in the commissural ganglia (CoGs), in somata in the esophageal ganglion (OG), in fibers in the stomatogastric nerve (stn), and in neuropilar processes in the STG. CbAST‐B1‐LI was blocked by preincubation with 10−6 M CbAST‐B1 and was partially blocked by lower concentrations. Electrophysiological recordings of the effects of CbAST‐B1, CbAST‐B2, and CbAST‐B3 on the pyloric rhythm of the STG showed that all three peptides inhibited the pyloric rhythm in a state‐dependent manner. Specifically, all three peptides at 10−8 M significantly decreased the frequency of the pyloric rhythm when the initial frequency of the pyloric rhythm was below 0.6 Hz. These data suggest important neuromodulatory roles for the CbAST‐B family in the stomatogastric nervous system. J. Comp. Neurol. 519:2658–2676, 2011. © 2011 Wiley‐Liss, Inc.