bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure of the Chloride‐ and Bromide‐Intercalated Layered Double Hydroxides of Li and Al – Interplay of Coulombic and Hydrogen‐Bonding Interactions in the Interlayer Gallery
Authors: Nagendran Supreeth , Kamath P. Vishnu
Published: July 2013

Rietveld refinement of the structures of the [LixAl(OH)3]Xx·yH2O (X = Br, Cl; y ≈ 1/2, 2/3) layered double hydroxides (LDHs) shows that the halide ion occupies two distinct positions in each phase. One position (2a), promoted by Coulombic attraction, is proximal to the Li+ ion, which is the seat of the positive charge in the metal hydroxide layer. The other position (6h) is within a close hydrogen‐bonding distance from the hydroxy group of the metal hydroxide layer as well as the intercalated water molecule. The LDH with intercalated Br– ions crystallizes in two different structures, one of which is isostructural with the Cl– analogue. In the other structure obtained at a higher relative humidity (≥76 %; y ≈ 2/3), the Br– ion occupies a site proximal to the Al3+ ion (2b), and intercalated water molecules are proximal to the Li+ ion. In this structure, the hydration of the Li+ ion in a distant coordination shell overcomes Coulombic interactions with Br– ions. On partial dehydration (ambient humidity 29 %; y ≈ 1/2), this Br– ion reversibly reverts back to the site (2a) proximal to the Li+ ion, which results in a humidity‐induced structure change without any variation in the basal spacing. Thereby, the position of the halide ion in the interlayer gallery is determined by the interplay of Coulombic and hydrogen‐bonding interactions.
Luminescent Properties of RbSrPO4:Eu2+ Phosphors for Near‐UV‐Based White‐Light‐Emitting Diodes
Authors: Yim Dong Kyun , Song Hee Jo , Roh Hee‐Suk , Kim Seung‐Joo , Han Byung Suh , Jin Yun‐Ho , Hong Hyun‐Seon , Kim Dong‐Wan , Hong Kug Sun
Published: July 2013

A phosphor based on a phosphate host matrix, RbSrPO4:Eu2+ (RSP), was synthesized by a conventional solid‐state reaction, and the crystal structure of the RSP host material was investigated by Rietveld refinement. The RSP phosphor could be excited efficiently by light in the 220–430 nm UV/Vis range and exhibited a highly intense emission peak at 450 nm. We discovered the effect of the activated Eu2+ concentration and the concentration quenching mechanism. Also, light absorption and quantum efficiency of the RSP phosphor were measured when excited in the near‐UV region. Finally, the effect of temperature on the photoluminescence emission intensity of the RSP phosphor and its thermal activation energy were investigated. All of these characteristics indicate that this phosphor has potential for use in near‐UV‐based white LEDs.
Simple Route to Adducts of (Amino)(aryl)carbene with Phosphorus Pentafluoride
Authors: Guzyr Olexandr I. , Zasukha Sergiy V. , Vlasenko Yurii G. , Chernega Alexander N. , Rozhenko Alexander B. , Shermolovich Yuriy G.
Published: July 2013

The tetramethyl ester of (hydroxy)(phenyl)methylenebis(phosphonic acid) reacts with morpholinosulfur trifluoride (MOST) to provide, along with the expected product of the substitution of a hydroxy group by fluorine, the adduct of (morpholino)(phenyl)carbene with PF5, compound 3a. Fluorination of dimethyl α‐aroylphosphonates with MOST yields adducts of (amino)(aryl)carbene with PF5 (p‐XC6H4)(Morph)C:→PF5 [3a–f, where Morph is morpholyl, X = H (a), Me (b), OEt (c), F (d), Cl (e), CF3 (f)] as the major reaction products. The reaction mechanism proposed is based on experimental data and DFT calculations. The structure of adduct 3a was determined by X‐ray studies. Hydrolysis of compounds 3e and 3f, bearing substituents Cl and CF3 on the phenyl ring, respectively, yields previously unknown benzoylpentafluorophosphates [p‐XC6H4–C(=O)PF5]–MorphH+.
Color‐Tunable Fluorescent Dyes Based on Benzo[c]coumarin
Authors: Krzeszewski Maciej , Vakuliuk Olena , Gryko Daniel T.
Published: July 2013

Hurtley condensation was shown to be a perfect tool with which to assemble a diversified library of derivatives of benzo[c]coumarin. Not only do simple resorcinols and ortho‐bromobenzoic acids undergo this reaction, but also dihydroxynaphthalenes and 3‐bromothiophene‐2‐carboxylic acid, affording the desired compounds in moderate yields. In the case of naphthalenediols, intriguing regioselectivity is observed, which holds promise for its utilization in the synthesis of previously inaccessible molecules. Further transformation made it possible to obtain benzo[c]coumarin bearing amino and nitro groups at various positions, which served as entry points to prepare complex hybrids of 1,4‐benzoxazin‐2‐ones and benzo[c]coumarins. The hydroxyl group proved to be the synthetic handle, enabling the synthesis of strongly solvatochromic, soluble analogues. The effect of structural variation on photophysical properties was studied in detail for almost 30 compounds. The relationship between the structure and photophysical properties was thoroughly elucidated by comparison with simple analogues (coumarins, benzoxazinones). All of the obtained compounds exhibit moderate to large Stokes shifts (3300–12500 cm–1). The type of π‐expansion of the chromophore strongly influences the overall optical phenomena. Compounds possessing alkyl substituents on the benzo[c]coumarin core have much higher fluorescence quantum yields than their analogues bearing amino, fluorine, and other complex substituents. Interestingly, the product possessing a fused coumarin–thiophene skeleton exhibits over twofold higher fluorescence quantum yield than any of its coumarin–benzene analogues.
Inductive Effects through Alkyl Groups – How Long is Long Enough?
Authors: Tandon Raman , Nigst Tobias A. , Zipse Hendrik
Published: July 2013

The influence of the length of alkyl substituents on various kinetic, thermodynamic, and spectroscopic properties of 4‐(dialkylamino)pyridines has been determined by using a combination of experimental and theoretical methods. The chain‐length dependence of these properties has subsequently been analyzed by using a quantitative model for through‐bond inductive effects.
Conformational Behavior of 1:1 [α/α‐Hydrazino]mer, 1:1 [α/Aza‐β3‐amino]mer and 1:1 [Aza‐β3‐amino/α]mer Series: Three Series of Foldamers
Authors: Acherar Samir , Salaün Arnaud , Le Grel Philippe , Le Grel Barbara , Jamart‐Grégoire Brigitte
Published: July 2013

Analysis of 1H NMR spectroscopic data allowed us to assign the secondary structure of three new series of mixed foldamers. 1:1 [α/aza‐β3‐amino]mers, 1:1 [aza‐β3‐amino/α]mers and 1:1 [α/α‐hydrazino]mers are self‐organized in solution by a hydrogen bond network of alternating a γ‐turn and a hydrazinoturn. Nevertheless, owing to the donor and acceptor H‐bond characters of the amidic NH, 1:1 [α/α‐hydrazino]mers can exist as an equilibrium between pseudospiranic and hydrazinoturn conformations.
Electrochemical Detection of Avian Influenza Virus Genotype Using Amino‐ssDNA Probe Modified Gold Electrodes
Authors: Malecka Kamila , Grabowska Iwona , Radecki Jerzy , Stachyra Anna , Góra‐Sochacka Anna , Sirko Agnieszka , Radecka Hanna
Published: July 2013

A DNA biosensor for the detection of specific oligonucleotide sequences of Avian Influenza Virus type H5N1 has been proposed. The NH2‐ssDNA probe was deposited onto a gold electrode surface to form an amide bond between the carboxyl group of thioacid and the amino group from ssDNA probe. The signals generated as a result of hybridization were registered in square wave voltammetry and electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3−/4− as a redox marker. The genosensor is capable to determine 20‐mer and 180‐bp (PCR products) oligonucleotides complementary sequences with detection limit in the fM range. The genosensor displays good selectivity and sensitivity. The 20‐mer as well as 180‐bp oligonucleotides without a complementary sequence generate very low signal.
A Novel Hydrogen Peroxide Biosensor Based on Adsorption of Horseradish Peroxidase onto a Nanobiomaterial Composite Modified Glassy Carbon Electrode
Authors: Moyo Mambo , Okonkwo Jonathan O. , Agyei Nana M.
Published: July 2013

In this work, a novel hydrogen peroxide biosensor derived from maize tassel (MT) and multiwalled carbon nanotube (MWCNT) composite was used to adsorb horseradish peroxidase (HRP) onto the surface of a glassy carbon electrode through electrostatic interactions. The morphology and structure of the products were characterized by SEM, FTIR and UV‐visible spectroscopy. The electrochemical and electrocatalytic performance of the HRP/MT‐MWCNT/GCE was studied using voltammetric and amperometric methods. The amperometric response of the biosensor varied linearly with concentration of H2O2 from 9 µM to 1 mM with detection limit of 4.0 µM (S/N=3). Furthermore, the biosensor exhibited good reproducibility and stability.
Electric Field Driven Extraction of Inorganic Anions Across a Polymer Inclusion Membrane
Authors: Schmidt‐Marzinkowski Julia , See Hong Heng , Hauser Peter C.
Published: July 2013

The potential use of plasticized cellulose acetate membranes for electric field driven extraction and preconcentration of inorganic anions was studied. The extraction of highly lipophilic ions such as perchlorate is possible by employing a membrane without any ion carrier, while anions of low lipophilicity, such as phosphate, require a carrier. Best extraction efficiency could be obtained for a membrane of 20 µm thickness and an applied voltage of 200 V. In a flow‐through arrangement the preconcentration factor was inversely dependent on the flow rate but constant for different concentrations. The extraction of perchlorate down to 2 nM was demonstrated.
Effective and Functional Surface Design for Biosensing Applications Based on a Novel Conducting Polymer and PMMA/Clay Nanocomposite
Authors: Kesik Melis , Kocer Ozgecan , Kanik Fulya Ekiz , Unlu Naime Akbasoglu , Rende Eda , Aslan‐Gurel Evren , Rossi Rene M. , Udum Yasemin Arslan , Toppare Levent
Published: July 2013

Surface functionalization plays a crucial role in the design of biosensors. For this purpose, a novel functional monomer, 6‐(4,7‐bis(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐5‐yl)‐2H‐benzo[d][1,2,3]triazol‐2‐yl)hexan‐1‐amine (BEDOA‐6), was designed and synthesized. Poly(BEDOA‐6) was utilized as an immobilization matrix for glucose oxidase biosensor construction. Moreover, polymethylmethacrylate (PMMA) layered silicate nanocomposites were prepared by in situ suspension polymerization. Conducting polymer surface was modified with PMMA/clay nanocomposite material and a glucose biosensor was developed. In addition, XPS and SEM were utilized to characterize the surface properties. The biosensor shows a wide linear range between 2.8 µM and 1.2 mM to glucose with a low detection limit of 1.99 µM. Finally, the biosensor was tested on serum samples containing actual human blood. The results were in well‐agreement with a reference method.
Micellar electrokinetic chromatography–electrospray ionization mass spectrometry employing a volatile surfactant for the analysis of amino acids in human urine
Authors: Moreno‐González David , Toraño Javier Sastre , Gámiz‐Gracia Laura , García‐Campaña Ana M. , de Jong Gerhardus J. , Somsen Govert W.
Published: July 2013

A new MEKC‐ESI‐MS method for the analysis of amino acids (AAs) in human urine was developed employing ammonium perfluorooctanoate (APFO) as volatile surfactant. The influence of APFO on the MS signal of AAs was evaluated by infusion experiments, which showed that APFO hardly affects analyte responses and presents significantly less ion suppression than equal concentrations of ammonium acetate. In order to obtain efficient separation of AAs, MEKC parameters such as the pH and APFO concentration of the BGE, were optimized. Optimum AA resolution, including baseline separation of leucine and isoleucine, was obtained using 150 mM APFO (pH 9.0) as BGE, representing a considerable selectivity improvement over CE using 50 mM ammonium acetate (pH 9.0). Optimization of CE‐MS parameters, such as sheath liquid composition and flow rate, and ESI and MS settings, led to LODs ranging from 9 to 26 ng/mL for the 20 tested AAs, which is highly favorable for an MEKC‐MS method. Good linearity (r2 > 0.99) and repeatability were obtained for all AAs tested with RSD values of 3.0–6.7% for peak area and <1.5% for migration time. The applicability of the MEKC‐MS method was demonstrated by the quantitative determination of AAs in urine employing only a 1:1 dilution with BGE as sample pretreatment. All AAs could selectively be detected and quantified obtaining relevant concentration values for normal human urine.
Microalgae fermentation of acetic acid‐rich pyrolytic bio‐oil: Reducing bio‐oil toxicity by alkali treatment
Authors: Zhao Xuefei , Chi Zhanyou , Rover Marjorie , Brown Robert , Jarboe Laura , Wen Zhiyou
Published: July 2013

Bio‐oil derived from fast pyrolysis of lignocellulosic biomass contains various substrates that can be fermented to fuels and chemicals. The goal of this research was to utilize an acetic acid‐rich fraction of bio‐oil for the growth and lipid production by microalga Chlamydomonas reinhardtii. As toxic compounds are contained in the bio‐oil, the algae cannot survive in medium containing this bio‐oil fraction even at a low level (0.05 wt %). An alkali‐based treatment with sodium hydroxide was used to reduce the toxicity and enhance its fermentability by microalgae. It was found that treating the acetic acid‐rich bio‐oil fraction by adjusting pH to 10 greatly improved the algal growth. The algae can thrive in medium containing 4 wt % alkali‐treated bio‐oil fraction. When using a metabolic‐evolved strain with high level of toxicity tolerance, the algae were even capable of growing in medium containing 5.5 wt % bio‐oil fraction, which replaced 100% of the acetic acid in the medium. The algal biomass grown in medium containing alkali‐treated bio‐oil fraction exhibited fatty acid profiles similar to the culture grown in pure acetic acid, but with a lower total fatty acid content. but the total fatty acid content (∼10% DW) was lower than that of the control (∼20% DW).The benefit of alkali treatment for enhancing algal growth was confirmed to be due to the removal of toxic compounds such as furfural, acetol, phenolics, and 5‐hydroxymethylfurfural (HMF). Collectively, the results showed that fast pyrolysis‐microalgal fermentation is a viable approach for producing lipid from lignocellulosic biomass. Alkali‐based treatment is an effective method for reducing bio‐oil toxicity, and thereby, greatly enhancing the algae fermentability of bio‐oil. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 955–961, 2013
Force–displacement mixed control for collapse tests of multistory buildings using quasi‐static loading systems
Authors: Pan Peng , Zhao Gang , Lu Xinzheng , Deng Kailai
Published: July 2013

In quasi‐static tests for structures with multi‐DOF, the forces exerted to the structures commonly follow a prescribed force profile, for example, triangular pattern and/or uniform pattern. Therefore, force control is the natural choice. However, force control is no longer applicable when the specimens sustain significant stiffness and strength degradation, particularly in collapse tests. To solve this problem, a force–displacement mixed control algorithm is proposed, which is able to achieve stable control in quasi‐static tests following prescribed force profiles. On the basis of the FlexTest IIm platform of the MTS Systems Corporation (14000 Technology Dr, Eden Prairie, MN 55344 United States), a test program named Tsinghua University mixed control test program, which uses a mixed control algorithm, was developed. The algorithm was initially applied to an elastic test of a cantilever column to verify its accuracy and stability and then to a collapse test of a multistory RC frame to investigate its effectiveness. In the collapse test, the effects of major control parameters, that is, the number of iterative rounds and the loading time of each round on the control accuracy, were also studied. The test results show that the test program applying the mixed control algorithm can achieve stable control of the collapse tests maintaining the expected force profile. Increasing the number of iterative rounds and the loading time of each round can improve the control accuracy. Copyright © 2013 John Wiley & Sons, Ltd.
Peripheral inflammatory markers in amnestic mild cognitive impairment
Authors: Karim Salman , Hopkins Steve , Purandare Nitin , Crowther Jackie , Morris Julie , Tyrrell Pippa , Burns Alistair
Published: July 2013

Objective

To prospectively monitor plasma inflammatory marker concentrations in peripheral blood, over 12 months, in subjects with amnestic mild cognitive impairment (MCI), and to determine the relationship between peripheral inflammatory markers and cognitive decline.

Methods

Seventy patients with amnestic MCI were recruited from two sites providing specialist memory assessment services in Manchester. The baseline assessment included physical examination, neuro‐psychological testing and venous blood samples for C‐reactive protein (CRP) and interleukin 6 (IL‐6) concentrations. Sixty two participants were followed up after 12 months and the assessments were repeated.

Results

Data analysis revealed a significant rise in CRP, but not IL‐6 concentrations over 12 months, which was not confounded by demographic variables. The neuro‐psychological test scores had no association with CRP or IL‐6 concentrations at baseline or 12 months follow‐up.

Conclusion

This study adopted the unique approach of prospectively investigating peripheral inflammatory markers in a cohort with amnestic MCI. A significant rise in CRP concentrations over 12 months, but lack of significant association with cognition, provide no evidence for a relationship between systemic inflammation and cognitive decline in amnestic MCI. © 2013 The Authors. International Journal of Geriatric Psychiatry published by John Wiley & Sons, Ltd.
Quantifying recent acceleration in sea level unrelated to internal climate variability
Authors: Calafat F. M. , Chambers D. P.
Published: July 2013

Sea level observations suggest that the rate of sea level rise has accelerated during the last 20 years. However, the presence of considerable decadal‐scale variability, especially on a regional scale, makes it difficult to assess whether the observed changes are due to natural or anthropogenic causes. Here we use a regression model with atmospheric pressure, wind, and climate indices as independent variables to quantify the contribution of internal climate variability to the sea level at nine tide gauges from around the world for the period 1920–2011. Removing this contribution reveals a statistically significant acceleration (0.022 ± 0.015 mm/yr2) between 1952 and 2011, which is unique over the whole period. Furthermore, we have found that the acceleration is increasing over time. This acceleration appears to be the result of increasing greenhouse gas concentrations, along with changes in volcanic forcing and tropospheric aerosol loading.
Distribution of natural halocarbons in marine boundary air over the Arctic Ocean
Authors: Yokouchi Yoko , Inoue Jun , Toom‐Sauntry Desiree
Published: July 2013

Ongoing environmental changes in the Arctic will affect the exchange of natural volatile organic compounds between the atmosphere and the Arctic Ocean. Among these compounds, natural halocarbons play an important role in atmospheric ozone chemistry. We measured the distribution of five major natural halocarbons (methyl iodide, bromoform, dibromomethane, methyl chloride, and methyl bromide) together with dimethyl sulfide and tetrachloroethylene in the atmosphere over the Arctic Ocean (from the Bering Strait to 79°N) and along the cruise path to and from Japan. Methyl iodide, bromoform, and dibromomethane were most abundant near perennial sea ice in air masses derived from coastal regions and least abundant in the northernmost Arctic, where the air masses had passed over the ice pack, whereas methyl chloride and methyl bromide showed the opposite distribution pattern. Factors controlling those distributions and future prospects for natural halocarbons in the Arctic are discussed.
Surface vegetation patterning controls carbon accumulation in peatlands
Authors: Loisel Julie , Yu Zicheng
Published: July 2013

Localized ecohydrological feedbacks have been proposed as important internal drivers of patterns and processes in terrestrial ecosystems. However, there is a significant gap between the prominence of theoretical models and the paucity of observations describing linkages between ecosystem structure and functioning. Here we report empirical evidence for strong interactions between surface vegetation patterning and long‐term carbon sequestration rates in four peat bogs in Patagonia on the basis of high‐resolution stratigraphic analyses. Peatland development across the study region was characterized by repeated switches between wet‐ and dry‐adapted plant communities, depicting changes between hollows (wet assemblages) and lawns (dry assemblages) that could represent past surface patterning. We found a site‐specific relationship between the frequency of the wet‐to‐dry cycles and carbon accumulation rates that followed a power function, with rapid vegetation shifts causing high peat accumulation rates. Our results show strong evidence for internal regulation of vegetation dynamics and peatland growth, implying that understanding peatland processes is a prerequisite for peat‐based paleoclimate reconstructions.
Mass‐induced sea level change in the northwestern North Pacific and its contribution to total sea level change
Authors: Cheng Xuhua , Li Lijuan , Du Yan , Wang Jing , Huang Rui‐Xin
Published: July 2013

Over the period 2003–2011, the Gravity Recovery and Climate Experiment (GRACE) satellite pair revealed a remarkable variability in mass‐induced sea surface height (MSSH) in the northwestern North Pacific. A significant correlation is found between MSSH and observed total sea surface height (SSH), indicative of the importance of barotropic variability in this region. For the period 2003–2011, MSSH rose at a rate of 6.1 ± 0.7 mm/yr, which has a significant contribution to the SSH rise (8.3 ± 0.7 mm/yr). Analysis of the barotropic vorticity equation based on National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis product, GRACE, and altimetry data suggests that the MSSH signal is primarily caused by negative wind stress curl associated with an anomalous anticyclonic atmospheric circulation. Regression analysis indicates that trends in MSSH and surface wind are related to the Pacific Decadal Oscillation, whose index had a decreasing trend in the last decade.
Cassini CAPS‐ELS observations of negative ions in Titan's ionosphere: Trends of density with altitude
Authors: Wellbrock A. , Coates A. J. , Jones G. H. , Lewis G. R. , Waite J. H.
Published: July 2013

Observations with the Electron Spectrometer sensor of the Cassini Plasma Spectrometer (CAPS‐ELS) have revealed the existence of negative ions in Titan's ionosphere. Negative ions are observed during encounters whenever the instrument points in the ram direction at altitudes 950–1400 km. Complex hydrocarbon and nitrile chemical processes are believed to take place which play a role in haze formation. The heaviest ions observed so far have masses up to 13,800 amu/q. Using data from 34 Titan encounters, we show for the first time negative ion density trends of different mass groups, including total densities, with altitude. We determine peak densities and the associated altitudes at which they are observed and the highest altitudes at which individual mass groups are found.
An explanation of bright areas inside Shackleton Crater at the Lunar South Pole other than water‐ice deposits
Authors: Haruyama Junichi , Yamamoto Satoru , Yokota Yasuhiro , Ohtake Makiko , Matsunaga Tsuneo
Published: July 2013

Whether water molecules of cometary and/or solar wind origin migrated to and accumulated in cold permanently shadowed areas at the lunar poles has long been debated from the perspective of scientific interest and expectations for future utilization. Recently, high reflectance condition was observed inside the lunar South Pole Shackleton Crater for the 1064.4 nm of the Lunar Orbiter Laser Altimeter on the Lunar Reconnaissance Orbiter, and the high reflectance was explained to perhaps be due to a surface frost layer in excess of 20% water‐ice. Here we investigate the crater with the Selenological Engineering Explorer Multi‐band imager that has nine bands in the visible to near‐infrared range, including a 1050 nm band (62 m/pixel resolution). Part of the illuminated inner wall of Shackleton Crater exhibits high reflectance at 1050 nm but also exhibits the diagnostic 1250 nm spectral absorption, a signature that is consistent with naturally bright purest anorthosite.
Hydrogeochemical interpretation of water seepage through a geological barrier at a reservoir boundary
Authors: Kim Gyoo‐Bum , Park Joon‐Hyeong
Published: July 2013

A geological barrier such as a mountain ridge surrounding a large reservoir generally plays some part in preventing water leakage from the reservoir, but water flows out naturally according to the hydraulic gradient because the reservoir water level is typically higher than that outside. The hydrogeological, geochemical, and isotopic properties of water in the Daechung Dam area were analysed to characterize the source and the phenomenon of the groundwater flowing through the geological barrier. Our geochemical analysis showed that the concentrations of anions and cations tended to increase, due to the longer residence time of the water, as the distance between the sampling site and reservoir increased. Elevation differences (calculated using oxygen and hydrogen isotopes) between the highest and lowest sampling sites ranged between 350 and 420 m based on the altitude effect on isotope concentration, but the actual difference was only 35 m. These results, including analysis of the rate of water seepage from the reservoir (ca. 2.3% to 14.4% of natural recharge), indicate the possibility that groundwater in the study area originated from reservoir water that was derived from upstream water and rainfall in the high mountainous area of the upper watershed. Copyright © 2013 John Wiley & Sons, Ltd.
Interpretation of mean‐field bias correction of radar rain rate using the concept of linear regression
Authors: Yoo Chulsang , Park Cheolsoon , Yoon Jungsoo , Kim Jungho
Published: July 2013

In this study, the correction problem of mean‐field bias of radar rain rate was investigated using the concept of linear regression. Three different relationships were reviewed for their slopes to be used as the bias correction factor: Relationship 1 (R1) is based on the conventional linear regression, relationship 2 (R2) is forced to pass the origin and relationship 3 (R3) is the line whose slope is the G/R ratio. In other words, R1 is the regression line connecting the intercept and the mass centre of measurement pairs, R2 is the regression line forced to pass the origin, and R3 is the line connecting the origin and the mass centre. The slopes of all three relationships were reviewed analytically to compare them, and thereby, the effect of zero measurements could be evaluated. Additionally, the effect of using switched independent and dependent variables on the derived slopes was also evaluated. The theoretically derived results were then verified by analysing the rainfall event on 10–11 August 2010 in Korea. Finally, the difference between the bias‐corrected radar rain rate and the rain gauge rain rate was quantified by root mean square error and mean error so that it could be used as a measure for the evaluation of bias correction factors. In conclusion, the slope of R2 was found to be the best for the bias correction factor. However, when deciding the slope of this R2, the radar rain rate should be used as the independent variable in the low rain rate region, and the rain gauge rain rate in the high rain rate region above a certain threshold. Copyright © 2013 John Wiley & Sons, Ltd.
Nonsteroidal anti‐inflammatory drugs suppress cancer stem cells via inhibiting PTGS2 (cyclooxygenase 2) and NOTCH/HES1 and activating PPARG in colorectal cancer
Authors: Moon Chang Mo , Kwon Ji‐Hee , Kim Ji Suk , Oh Sun‐Hee , Jin Lee Kyoung , Park Jae Jun , Pil Hong Sung , Cheon Jae Hee , Kim Tae Il , Kim Won Ho
Published: July 2013

Cancer stem cells (CSCs) play a pivotal role in cancer relapse or metastasis. We investigated the CSC‐suppressing effect of nonsteroidal anti‐inflammatory drugs (NSAIDs) and the relevant mechanisms in colorectal cancer. We measured the effect of NSAIDs on CSC populations in Caco‐2 or SW620 cells using colosphere formation and flow cytometric analysis of PROM1 (CD133)+CD44+ cells after indomethacin treatment with/without prostaglandin E2 (PGE2) or peroxisome proliferator‐activated receptor γ (PPARG) antagonist, and examined the effect of indomethacin on transcriptional activity and protein expression of NOTCH/HES1 and PPARG. These effects of indomethacin were also evaluated in a xenograft mouse model. NSAIDs (indomethacin, sulindac and aspirin), celecoxib, γ‐secretase inhibitor and PPARG agonist significantly decreased the number of colospheres formation compared to controls. In Caco‐2 and SW620 cells, compared to controls, PROM1 (CD133)+CD44+ cells were significantly decreased by indomethacin treatment, and increased by 5‐fluorouracil (5‐FU) treatment. This 5‐FU‐induced increase of PROM1 (CD133)+CD44+ cells was significantly attenuated by combination with indomethacin. This CSC‐inhibitory effect of indomethacin was reversed by addition of PGE2 and PPARG antagonist. Indomethacin significantly decreased CBFRE and increased PPRE transcriptional activity and their relative protein expressions. In xenograft mouse experiments using 5‐FU‐resistant SW620 cells, the 5‐FU treatment combined with indomethacin significantly reduced tumor growth, compared to 5‐FU alone. In addition, treatment of indomethacin alone or combination of 5‐FU and indomethacin decreased the expressions of PROM1 (CD133), CD44, PTGS2 (cyclooxygenase 2) and HES1, and increased PPARG expression. NSAIDs could selectively reduce the colon CSCs and suppress 5‐FU‐induced increase of CSCs via inhibiting PTGS2 (cyclooxygenase 2) and NOTCH/HES1, and activating PPARG.
Targeting acute myeloid leukemia with a proapoptotic peptide conjugated to a toll‐like receptor 2‐mediated cell‐penetrating peptide
Authors: Li Ke , Lv Xiao‐Xi , Hua Fang , Lin Heng , Sun Wei , Cao Wen‐Bin , Fu Xiao‐Ming , Xie Jing , Yu Jiao‐Jiao , Li Zhe , Liu Hong , Han Ming‐Zhe , Hu Zhuo‐Wei
Published: July 2013

Cell‐penetrating peptides provide a unique platform to create a new generation of cancer therapeutics with enhanced efficacy and diminished toxicity. In our study, enhanced expression of toll‐like receptor 2 (TLR2) was observed in acute myeloid leukemia (AML) cells. Screening of a phage display peptide library using Biopanning and Rapid Analysis of Selective Interactive Ligands (BRASIL) identified a TLR2‐binding peptide motif, Pep2. We show that the TLR2‐binding peptide motif targeted and penetrated into leukemia cells in a TLR2‐dependent manner. Moreover, a synthetic, chimeric peptide composed of the TLR2‐binding motif linked to a programmed cell death‐inducing sequence, D(KLAKLAK)2, induced apoptosis in AML cells with high TLR2 expression (TLR2high) but not in chronic myeloid leukemia (CML) cells with low TLR2 expression (TLR2low). The antileukemia activity of this chimeric peptide was confirmed in leukemia patient samples and an animal model of myeloid leukemia, as the development of leukemia was significantly delayed in mice with TLR2high AML compared to TLR2low CML NOD/SCID mice. TUNEL assays on bone marrow tissue slices revealed that the chimerical peptide induced leukemia cell apoptosis in a TLR2‐dependent manner. Together, our findings indicate that TLR2 is a potential therapeutic target for the prevention and treatment of AML, and the prototype, Pep2‐D(KLAKLAK)2, is a promising drug candidate in this setting.
Cardiovascular morbidity in long‐term survivors of early‐onset cancer: A population‐based study
Authors: Kero A.E. , Järvelä L.S. , Arola M. , Malila N. , Madanat‐Harjuoja L.M. , Matomäki J. , Lähteenmäki P.M.
Published: July 2013

Improvements in cancer therapy have resulted in an expanding population of early‐onset cancer survivors. In contrast to childhood and adolescent cancer survivors, there is still a lack of data concerning late morbidities among young adult (YA) cancer survivors. Thus, our aim was to investigate cardiac and vascular morbidity among early‐onset cancer survivors with a special interest in YA cancer survivors. In a population‐based setting, we explored the risk of cardiovascular disease in early‐onset cancer survivors compared to healthy siblings. Patients diagnosed with cancer below 35 years of age since 1975 were identified from the Finnish Cancer Registry, and 5‐year survivors were included in our study (N = 13,860). Information on cardiovascular morbidity was collected from the national hospital discharge registry. Compared to siblings, cancer survivors aged 0–19 and 20–34 at diagnosis had significantly elevated hazard ratios (HRs) for the studied outcomes: HR 13.5 (95% CI 8.9–20.4) and 3.6 (95% CI 2.8–4.6) for cardiomyopathy/cardiac insufficiency; HR 3.4 (95% CI 2.3–5.1) and 1.7 (95% CI 1.4–2.0) for atherosclerosis/brain vascular thrombosis; HR 3.3 (95% CI 1.7–6.5) and 1.8 (95% CI 1.5–2.1) for myocardial infarction/cardiac ischemia and HR 1.7 (95% CI 1.2–2.6) and 1.4 (95% CI 1.2–1.7) for cardiac arrhythmia. In both groups, depending on the outcome, the HR for adverse events was highest among lymphoma, brain tumor, leukemia and testicular malignancy survivors. Our results regarding late effects of childhood cancer survivors confirmed previous findings. Additionally, our study provides novel information concerning the YA cancer survivor population. Hence, our data may help in planning the risk‐based long‐term follow‐up of early‐onset cancer survivors.
Dose‐dependent surface endothelialization and biocompatibility of polyurethane noble metal nanocomposites
Authors: Hess Christian , Schwenke Andreas , Wagener Philipp , Franzka Steffen , Laszlo Sajti Csaba , Pflaum Michael , Wiegmann Bettina , Haverich Axel , Barcikowski Stephan
Published: July 2013

Surface pre‐endothelialization is a promising approach to improve the hemocompatibility of implants, medical devices, and artificial organs. To promote the adhesive property of thermoplastic polyurethane (TPU) for endothelial cells (ECs), up to 1 wt % of gold (Au) or platinum (Pt) nanoparticles, fabricated by pulsed laser ablation in polymer solution, were embedded into the polymer matrix. The analysis of these nanocomposites showed a homogenous dispersion of the nanoparticles, with average diameters of 7 nm for Au or 9 nm for Pt. A dose‐dependent effect was found when ECs were seeded onto nanocomposites comprising different nanoparticle concentrations, resulting in a fivefold improvement of proliferation at 0.1 wt % nanoparticle load. This effect was associated with a nanoparticle concentration‐dependent hydrophilicity and negative charge of the nanocomposite. In dynamic flow tests, nanocomposites containing 0.1 wt % Au or Pt nanoparticles allowed for the generation of a confluent and resistant EC layer. Real‐time polymerase chain reaction quantification of specific markers for EC activation indicated that ECs cultivated on nanocomposites remain in an inactivated, nonthrombogenic and noninflammatory state; however, maintain the ability to trigger an inflammatory response upon stimulation. These findings were confirmed by a platelet and leukocyte adhesion assay. The results of this study suggest the possible applicability of TPU nanocomposites, containing 0.1 wt % Au or Pt nanoparticles, for the generation of pre‐endothelialized surfaces of medical devices. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1909–1920, 2014.
Increased osseointegration effect of bone morphogenetic protein 2 on dental implants: An in vivo study
Authors: Yoo Daniel , Tovar Nick , Jimbo Ryo , Marin Charles , Anchieta Rodolfo B. , Machado Lucas S. , Montclare Jin , Guastaldi Fernando P. S. , Janal Malvin N. , Coelho Paulo G.
Published: July 2013

Application of recombinant human bone morphogenetic protein 2 (rhBMP‐2) to implant surfaces has been of great interest due to its osteoinductive potential. However, the optimal coating methodology has not been clarified. The objective of the study was to determine whether the application of rhBMP‐2 onto plasma‐sprayed hydroxyapatite implant surfaces by immersion in protein solution before implant installation would result in significantly improved bone apposition. Using a sheep iliac model, titanium (Ti) and plasma‐sprayed calcium–phosphate (PSCaP)‐coated implants uncoated and coated with rhBMP‐2 were assessed for their osteogenic effects in the peri‐implant area over time in terms of osseointegration and de novo bone formation. After 3 and 6 weeks postoperatively, the samples were retrieved and were subjected to bone‐to‐implant contact (BIC) and bone area fraction occupancy (BAFO) evaluation. When rhBMP‐2 was applied to the PSCaP surface, significant increases in BIC and BAFO were observed at 3 weeks in vivo, whereas when adsorbed directly onto the titanium implant surface, rhBMP‐2 did not as effectively improve the bone response (although significantly higher than control Ti). The outcomes of the present study suggested that the combination of plasma‐sprayed calcium–phosphate surface and rhBMP‐2 coating significantly enhanced osseointegration, which validated the postulated hypothesis. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1921–1927, 2014.
Sericin–carboxymethyl cellulose porous matrices as cellular wound dressing material
Authors: Nayak Sunita , Kundu S. C.
Published: July 2013

In this study, porous three‐dimensional (3D) hydrogel matrices are fabricated composed of silk cocoon protein sericin of non‐mulberry silkworm Antheraea mylitta and carboxymethyl cellulose. The matrices are prepared via freeze‐drying technique followed by dual cross‐linking with glutaraldehyde and aluminum chloride. The microstructure of the hydrogel matrices is assessed using scanning electron microscopy and biophysical characterization are carried out using Fourier transform infrared spectroscopy and X‐ray diffraction. The transforming growth factor β1 release from the cross‐linked matrices as a growth factor is evaluated by immunosorbent assay. Live dead assay and 3‐[4,5‐dimethylthiazolyl‐2]‐2,5‐diphenyl tetrazolium bromide assay show no cytotoxicity of blended matrices toward human keratinocytes. The matrices support the cell attachment and proliferation of human keratinocytes as observed through scanning electron microscope and confocal images. Gelatin zymography demonstrates the low levels of matrix metalloproteinase 2 (MMP‐2) and insignificant amount of MMP‐9 in the culture media of cell seeded matrices. Low inflammatory response of the matrices is indicated through tumor necrosis factor alpha release assay. The results indicate that the fabricated matrices constitute 3D cell‐interactive environment for tissue engineering applications and its potential use as a future cellular biological wound dressing material. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Synthesis, characterization, and antiplasmodial activity of polymer‐incorporated aminoquinolines
Authors: Aderibigbe B. A. , Neuse E. W. , Sadiku E. R. , Shina Ray S. , Smith P. J.
Published: July 2013

In this research, aminoquinoline compounds were synthesized, characterized, and incorporated into water‐soluble polymers to form conjugates. The conjugates were characterized by X‐ray diffraction, thermal gravimetric analysis, scanning electron microscope, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy to confirm the successful incorporation of the aminoquinoline compound on to the polymer. The synthesized conjugates were screened for in vitro antiplasmodial activity in triplet test against chloroquine‐sensitive strain of Plasmodium falciparum and chloroquine drug was used as a reference drug in all the experiments. A full dose–response was performed to determine the concentration inhibiting 50% of parasite growth (IC50 value). Polymeric conjugates containing 3‐diethylamino‐1‐propylamine solubilizing units were found to be most active against the chloroquine‐sensitive strain of P. falciparum. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1941–1949, 2014.
A novel coculture model of HUVECs and HUASMCs by hyaluronic acid micropattern on titanium surface
Authors: Li Jingan , Zhang Kun , Xu Ying , Chen Jiang , Yang Ping , Zhao Yuancong , Zhao Ansha , Huang Nan
Published: July 2013

Orientation smooth muscle cell environment plays a positive role in the development of a functional, adherent endothelium. Therefore, building an orientation coculture model of endothelial cells (ECs) and smooth muscle cells (SMCs) on biomaterials surface may provide more help for understanding the interaction between the two cells in vitro. In the present study, a “SMCs‐ColIV‐ECs” coculture model was built on the hyaluronic acid (HA) patterned titanium (Ti) surface, and compared with the previous “SMCs‐HAa‐ECs” model on endothelial cell number, morphology index, nitric oxide (NO), and prostacyclin2 (PGI2) release, anticoagulation property, human umbilical artery smooth muscle cells (HUASMCs) inhibition property and retention under fluid flow shear stress. The result indicated that “SMCs‐ColIV‐ECs” model could enhance the number, spreading area, and major/minor index of human umbilical vein endothelial cells (HUVECs), which contributed to the retention of HUVECs on the surface. Greater major/minor index may produce more NO and PGI2 release, contributing to the anticoagulation property and HUASMCs inhibition property. In summary, this novel “SMCs‐ColIV‐ECs” coculture model improved the previous “SMCs‐HAa‐ECs” model, and may provide more inspiration for the human vascular intima building on the biomaterials in vitro. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1950–1960, 2014.
Graphene oxide nanoparticles for enhanced photothermal cancer cell therapy under the irradiation of a femtosecond laser beam
Authors: Li Jing‐Liang , Hou Xue‐Liang , Bao Hong‐Chun , Sun Lu , Tang Bin , Wang Jin‐Feng , Wang Xun‐Gai , Gu Min
Published: July 2013

Nano‐sized graphene and graphene oxide (GO) are promising for biomedical applications, such as drug delivery and photothermal therapy of cancer. It is observed in this work that the ultrafast reduction of GO nanoparticles (GONs) with a femtosecond laser beam creates extensive microbubbling. To understand the surface chemistry of GONs on the microbubble formation, the GONs were reduced to remove most of the oxygen‐containing groups to get reduced GONs (rGONs). Microbubbling was not observed when the rGONs were irradiated by the laser. The instant collapse of the microbubbles may produce microcavitation effect that brings about localized mechanical damage. To understand the potential applications of this phenomenon, cancer cells labeled with GONs or rGONs were irradiated with the laser. Interestingly, the microbubbling effect greatly facilitated the destruction of cancer cells. When microbubbles were produced, the effective laser power was reduced to less than half of what is needed when microbubbling is absent. This finding will contribute to the safe application of femtosecond laser in the medical area by taking advantage of the ultrafast reduction of GONs. It may also find other important applications that need highly localized microcavitation effects. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2181–2188, 2014.
Immunocompatibility evaluation of hydrogel‐coated polyimide implants for applications in regenerative medicine
Authors: Sirova Milada , Vlierberghe Sandra Van , Matyasova Veronika , Rossmann Pavel , Schacht Etienne , Dubruel Peter , Rihova Blanka
Published: July 2013

Immunocompatibility of gelatin‐based hydrogels to be applied as implant coatings for local regenerative treatment has been studied. First, the bio‐ and immuno‐acceptability of the methacrylamide‐modified gelatin hydrogels per se was screened. The results indicated that the hydrogels support cell growth. Metabolic activity of normal cells and permanent cell lines representing various cell types (endothelial, epithelial, fibroblast, and monocyte/macrophage) cultivated on the gelatin hydrogels was moderately lower compared to cells cultivated on tissue culture plastic. The cells cultivated on the hydrogels produced identical cytokines as the control cells although at lower levels. Importantly, no inflammatory activity, measured by nitric oxide and pro‐inflammatory cytokine (IL‐1α, IL‐6, and TNFα) production, was observed in peritoneal cells and monocyte/macrophage RAW 264.7 cell line cultivated on the hydrogels. Finally, polyimide (PI) implantable membranes were surface‐modified with gelatin hydrogels and screened for their in vivo immunocompatibility. Their histological examination performed after subcutaneous implantation in mice produced a sound proof of immunoacceptability. Normal tissue repair, mild cellular infiltration and edema mainly induced by the surgery were observed after 2 and 6 days. No adverse tissue responses were induced by the implants. Analysis performed after 4 and 9 weeks indicated areas of foreign body granuloma without formation of a fibrous capsule. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1982–1990, 2014.
A comparison of the stress corrosion cracking susceptibility of commercially pure titanium grade 4 in Ringer's solution and in distilled water: A fracture mechanics approach
Authors: Roach Michael D. , Williamson R. Scott , Thomas Joseph A. , Griggs Jason A. , Zardiackas Lyle D.
Published: July 2013

From the results of laboratory investigations reported in the literature, it has been suggested that stress corrosion cracking (SCC) mechanisms may contribute to early failures in titanium alloys that have elevated oxygen concentrations. However, the susceptibility of titanium alloys to SCC in physiological environments remains unclear. In this study, a fracture mechanics approach was used to examine the SCC susceptibility of CP titanium grade 4 in Ringer's solution and distilled de‐ionized (DI) water, at 37°C. The study duration was 26 weeks, simulating the non‐union declaration of a plated fracture. Four wedge loads were used corresponding to 86–95% of the alloy's ligament yield load. The longest cracks were measured to be 0.18 mm and 0.10 mm in Ringer's solution and DI water, respectively. SEM analysis revealed no evidence of extensive fluting and quasi‐cleavage fracture features which, in literature reports, were attributed to SCC. We thus postulate that the Ringer's solution accelerated the wedge‐loaded crack growth without producing the critical stresses needed to change the fracture mechanism. Regression analysis of the crack length results led to a significant best‐fit relationship between crack growth velocity (independent variable) and test electrolyte, initial wedge load, and time of immersion of specimen in electrolyte (dependent variables). © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 73–79, 2014.