Corr Value Research Articles

Comparing univariate filtration preceding and succeeding PLS-DA analysis on the differential variables/metabolites identified from untargeted LC-MS metabolomics data

BackgroundPLS-DA of high-dimensional metabolomics data is frequently employed to capture the most pertinent features to sample classification. But the presence of numerous insignificant input features could distort the PLS-DA model, blow up and scramble the selected differential features. Usually, univariate filtration is subsequently complemented to refine the selected features, but often giving unstable results. Whereas by precluding insignificant features through univariate data prefiltration assessed by FDR adjusted p-value, PLS-DA can generate more stable and reliable differential features. We explored and compared these two data analysis procedures to gain insights into the underlying mechanisms responsible for the disparate results. ResultsThe effect of univariate data filtration preceding and succeeding PLS-DA analysis on the identified discriminative features/metabolites was investigated using LC-MS data acquired on the samples of human serum and C. elegans extracts, with and without metabolite standards spiked to simulate the treated and control groups of biological samples. It was shown that the univariate data prefiltration before PLS-DA usually gave less but more stable and likely more reliable and meaningful differential features, while PLS-DA applied directly to the original data could be affected by the presence of insignificant features and orthogonal noise. Large number of insignificant variables and orthogonal noise could distort the generated PLS-DA model and affect the p(corr) value, and artificially inflate the calculated VIP values of relevant features due to the increased total number of input features for model construction, thus leading to more false positives selected by the conventional VIP threshold of 1.0. Significance and noveltyUnivariate data filtration preceding PLS-DA was important for the identification of reliable differential features if using a conventional threshold of VIP of 1.0. Presence of insignificant features could distort the PLS-DA model and inflate VIP values. Appropriate VIP threshold is associated with the numbers of input features and the model components. For PLS-DA without univariate prefiltration, threshold of VIP larger than 1.0 is recommended for the selection of discriminative features to reduce the false positives.

Crystal structure, far-infrared spectroscopy, and microwave dielectric properties of two novel vanadates CaRECeV3O12 (RE = Nd, Sm)

Two novel low-εr CaRECeV3O12 (RE = Nd, Sm) microwave dielectric ceramics were prepared to utilize the solid-state method. According to XRD and Raman spectroscopy data, the CaRECeV3O12 (RE = Nd, Sm) ceramics had a tetragonal zircon-type with an I41/amd space group. Dense CaNdCeV3O12 and CaSmCeV3O12 ceramics sintered at 1225 °C and 1200 °C showed εr ∼11.85 ± 0.1 and 11.33 ± 0.1, Q × f ∼40,100 ± 500 GHz and 43,290 ± 500 GHz, τf ∼ −27.2 ± 0.5 ppm/°C and −22.4 ± 0.5 ppm/°C, along with αL of 9.4 ppm/°C and 8.5 ppm/°C, respectively. The measured εr and corrected εr(corr) values were larger than εr(C-M) (9.41 and 9.47) in CaNdCeV3O12 and CaSmCeV3O12 due to the cations being, on average, under-bonded and the overall structures being in a slightly expanded state. The slightly higher |<d>| value of CaNdCeV3O12 led to its higher εr(corr) value, even though it had a lower αD/Vm value. The sign and magnitude of τf values for CaNdCeV3O12 and CaSmCeV3O12 were mainly determined by their positive temperature coefficients of dielectric polarizability ταm of +36.2 ppm/°C and +32.1 ppm/°C, respectively. The inherent dielectric constant and dielectric loss were examined using far-infrared reflectivity spectra, Raman spectra, and the packing fraction.

Improvement in comprehensive properties of nanocomposite coatings electro-codeposited with nitride and ceria

Metal matrix composite coatings have attracted scientific and engineering interest because of their excellent mechanical properties. Nano-Si3N4 reinforced nickel coatings with different ceria contents were fabricated by electrodeposition. The microstructures, hardness, and tribological properties as well as corrosion behaviors of the composite coatings were studied in detailed. The results show that incorporation of ceria nanoparticles into the nickel matrix can decrease the grain size and facilitate the (111) texture of the coatings, leading to a smooth surface, compact microstructure, and dispersion-strengthening composites. The 6CeO2 coating with the highest hardness of 520 HV50g demonstrates the best wear resistance, while the 3CeO2 coating shows the best corrosion resistance with the smallest i corr value of 0.0972 μA/cm2. The study suggests a significant improvement in mechanical and anti-corrosion properties by incorporation with the ceria nanoparticles, which has important implications for the surface protection of engineering materials.

Validation and Reliability of Lifestyle Instruments for Indonesian Adolescents with Hypertension Family History: A Rasch Model

BACKGROUND: There are lifestyle changes among adolescents in this modern era, such as less physical activities, because many activities can be carried out using modern technology, unhealthy food habits such as eating junk food, canned food and beverages, and preserved fruits and vegetables, poor sleeping habits, stress, and smoking behavior. These lifestyles are harmful and lead to cardiometabolic diseases such as obesity and hypertension, especially in adolescents with hypertension history in the family. AIM: This study aimed to assess the validation and reliability of healthy lifestyle instruments for Indonesian adolescents with a family history of hypertension. METHODS: This study is a survey research conducted from July 2021 to February 2022 in South Sumatera, Indonesia. The subjects were adolescents with a family history of hypertension and recruited using purposive random sampling. Adolescents aged 10–18 years old who returned signed parental consent forms, gave written assent to participate, and completed the questionnaire were included in the study. The questionnaire was consisted of three sections, Section I contained internal factors, Section II related to external factors, and Section III related to healthy lifestyle. The study was approved by the Research Ethics Committee Universitas Padjadjaran Bandung. Winsteps software was used to analyze the validity, reliability, unidimentionality, and rating scale. RESULTS: Obtained 103 valid question items with OUTFIT values 0.5 &lt; mean square &lt; 1.5; −2.0 &lt; ZSTD &lt; 2.0; and the point measure correlation (Pt Mean Corr) value is in the range of 0.32 &lt; Pt Measure Corr &lt; 0.85. The reliability value of respondents and instruments is 0.88, with a ’Cronbach’s alpha value of 0.95. The raw variance explained by the measured value is 72.3%, and all unexplained variance values are &lt;15%. CONCLUSIONS: Healthy lifestyle instruments are valid and reliable, so it is feasible to measure the healthy lifestyle of Indonesian adolescents with a family history of hypertension. This instrument can measure the success of a program or intervention in changing a lifestyle in adolescents at risk of developing hypertension, especially adolescents with a family history of hypertension. We suggest further research involving more participants in a broader area. We hope the healthy lifestyle instruments can be used in a standardized manner for all regions of Indonesia.

Optimising the corrosion performance of hot-rolled steel bar in concrete

ABSTRACT To optimising the corrosion resistance mechanism of hot-rolled steel bar, the effects of different tempering temperatures and high-oxygen-rich oxidation times were studied by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, electrochemical and atmospheric corrosion tests. The thickness of the oxide layer of the rebar could reach 10 μm and rarely corroded after high-oxygen-rich oxidation at 850°C for 1 s, which exhibits superior corrosion resistance. The electrochemical test results showed that the I corr value after 1 s of high-oxygen-rich oxidation at 850°C was about 0.02 mA cm−2, which was 56.4% lower than that of the heated specimen at 685°C (0.045 mA cm−2). The results of Raman spectroscopy showed that the rust layer of the heated specimen at 685°C mainly consisted of α-Fe2O3, γ-FeOOH and α-FeOOH, and the oxidised layer after 1 s of high-oxygen-rich oxidation at 850°C mainly consisted of α-Fe2O3 and Fe3O4, which maintained the original oxidised layer morphology.

The bifunctional role played by thiocyanate anions on the active dissolution and the passive film of titanium in hydrochloric acid

ABSTRACT The electrochemical behaviour of titanium dissolution and passivation in HCl was examined with and without the SCN− anions using potentiodynamic polarisation, electrochemical impedance spectroscopy, and current transients techniques. The nature of the Ti oxide film was characterised by utilising XPS and SEM tools. The corrosion current i corr, the critical passivation current i cc, and the passive current i pass values increased significantly when the HCl concentration, scan rate, and temperature were raised. On the contrary, the addition of SCN− anions decreases the i corr value, indicating that the Ti dissolution was inhibited as a result of SCN− adsorption on the Ti surface. The inhibition efficiency increased with increasing the concentration of SCN−. However, SCN− anions lead to destabilised passivity in the passive zone. The formation of the Ti oxide film is a diffusion-controlled operation, as shown by the i–t curves. According to the XPS measurements, the passive oxide coating consists mainly of TiO2 and less of Ti2O3.

Facile and eco-friendly synthesis of polyaniline/ZnO composites for corrosion protection of AA-2024 aluminium alloy

In this study, organic/inorganic PANI/ZnO composites with different weight proportions were prepared via a simple and environmentally friendly method consisting of ultrasonication and a solution combustion method using urea as fuel. Powder X-ray diffraction and EDAX were carried out to investigate the structure, crystallinity and chemical composition of the samples. Raman spectra were recorded to provide information about the interactions between PANI chains and ZnO. The grain size and morphology were evaluated by laser granulometry. The anti-corrosion properties of ZnO/PANI composites were evaluated for AA-2024 substrates after coating using the drop-deposition technique and ( N -methylpyrrolidone) (NMP) as the solvent. The composite coating was almost stable over a period of 30 days when exposed to an aqueous solution of 3.5% NaCl, as determined by the gravimetric method. The contact angle technique was used to measure the hydrophobicity, which increased to 85° for the coated composite substrate. The potentiodynamic curves showed considerable improvement in the corrosion resistance with increasing ZnO content, and 60 wt% ZnO/PANI resulted in the lowest i corr value with a protection efficiency of 99.99.

Co-deposition of micro- and nano-sized SnO2 particles in the Zn-matrix composite coatings produced from a Zn-sulphate bath by electroplating

The Zn-coating and Zn-composite coatings were produced by electroplating technique. The Zn-composite coatings are generated with the co-deposition of SnO 2 microparticles and SnO 2 nanoparticles. The deposit characteristics of coated samples have been depicted by SEM photo-micrographs and contact angle study. The corrosion behavior of the prepared coated samples was evaluated by electrochemical tests such as polarization (Tafel) and electrochemical impedance spectroscopy (EIS). The bare Zn-coating shows a more negative E corr value (−1.121 V vs SCE) whereas, Zn-nano SnO 2 composite coating exhibited less negative E corr (−1.084 V vs SCE) compared to E corr (−1.091 V vs SCE) of Zn-micro SnO 2 composite coating. Similarly, the R ct values of bare Zn-coating, Zn-micro SnO 2 composite coating and Zn-nano SnO 2 composite coating were found to be 92 Ω cm 2 , 907 Ω cm 2 , and 1919 Ω cm 2 , respectively. The studies revealed the increased corrosion resistance property of Zn-nano SnO 2 composite coating than Zn-micro SnO 2 composite coating.

Student Perspective on Technology Enabled/Enhanced Active Learning in Educational: Rasch Measurement Model

Nowadays, the industrial revolution 4.0 had given a great impact on education. An active environment which applied technology in education can developed multiple skills in students. Technology Enabled/Enhanced Active Learning (TEAL) is one of the active environments that used technology in education. TEAL is the combination of several active learning domains which enhances students' understanding of learning and built job-related skills. However, students have lack of knowledge in their field which led to increase in unemployment of students. Hence, TEAL can help students in perform their practical works to develop knowledge and skills in students. This pilot study was distributed survey question about create an active and effective environment using TEAL application among the engineering students. The survey is consisted of 141 items and was distributed to 40 respondents. This pilot study used Rasch Measurement Model for measuring the validity and reliability of survey questions. Winsteps software is used to check the functionality of the item in terms of (i) Reliability and separation of respondents - items; (ii) detect the polarity items of PTMEA CORR Value; (iii) the item fit based on MNSQ Value; and (iv) Determine the dependent items based on the standardized residual value measurement correlation. The final result 109 items is suitable to use for measurement of the real study in future work.

Pilot analysis of Student Perspective on Technology Enabled/Enhanced Active Learning in Educational: Rasch Measurement Model

Nowadays, the industrial revolution 4.0 had given a great impact on education. An active environment which applied technology in education can developed multiple skills in students. Technology Enabled/Enhanced Active Learning (TEAL) is one of the active environments that used technology in education. TEAL is the combination of several active learning domains which enhances students' understanding of learning and built job-related skills. However, students have lack of knowledge in their field which led to increase in unemployment of students. Hence, TEAL can help students in perform their practical works to develop knowledge and skills in students. This pilot study was distributed survey question about create an active and effective environment using TEAL application among the engineering students. The survey is consisted of 141 items and was distributed to 40 respondents. This pilot study used Rasch Measurement Model for measuring the validity and reliability of survey questions. Winsteps software is used to check the functionality of the item in terms of (i) Reliability and separation of respondents - items; (ii) detect the polarity items of PTMEA CORR Value; (iii) the item fit based on MNSQ Value; and (iv) Determine the dependent items based on the standardized residual value measurement correlation. The final result 109 items is suitable to use for measurement of the real study in future work.

Student Perspective on Technology Enabled/Enhanced Active Learning in Educational: Rasch Measurement Model

Nowadays, the industrial revolution 4.0 had given a great impact on education. An active environment which applied technology in education can developed multiple skills in students. Technology Enabled/Enhanced Active Learning (TEAL) is one of the active environments that used technology in education. TEAL is the combination of several active learning domains which enhances students' understanding of learning and built job-related skills. However, students have lack of knowledge in their field which led to increase in unemployment of students. Hence, TEAL can help students in perform their practical works to develop knowledge and skills in students. This pilot study was distributed survey question about create an active and effective environment using TEAL application among the engineering students. The survey is consisted of 141 items and was distributed to 40 respondents. This pilot study used Rasch Measurement Model for measuring the validity and reliability of survey questions. Winsteps software is used to check the functionality of the item in terms of (i) Reliability and separation of respondents - items; (ii) detect the polarity items of PTMEA CORR Value; (iii) the item fit based on MNSQ Value; and (iv) Determine the dependent items based on the standardized residual value measurement correlation. The final result 109 items is suitable to use for measurement of the real study in future work.

Electrochemical Characterization of Ruthenium Using Potassium Bromate As Oxidizer for Titania Based CMP Slurry

Introduction: Chemical mechanical planarization (CMP) uses chemical and mechanical action for removing the surface topography. It is widely used in integrated chip fabication. Due to the miniaturization of semiconductor chips, focus on the use of ruthenium (Ru) as barrier layer has increased as it allows direct electrodeposition of copper (Cu). The present work involved study of different parameters such as concentration and pH on Ru removal rate (RR) using a slurry consisting of titania as abrasive and potassium bromate (KBrO3) as oxidizer. Electrochemical characterization of Ru was carried out in KBrO3 solutions to investigate the dissolution phenomena. The corrosion current (I corr) values of Ru were obtained from the extrapolation of Tafel curves. An electrical equivalent circuit (EEC) was proposed to model the electrochemical impedance spectroscopy (EIS) results. Methods: A bench top polisher was used to perform the CMP experiments. A pressure of 3.5 psi was applied to the Ru disc and the platen speed was maintained at 150 rpm for all the CMP runs. The specimen holder speed was kept at 250 rpm. For studying the effect of pH on Ru RR, 1 wt% concentration of oxidizer and abrasive was used. For studies on the effect of concentration of abrasives, 1 wt% concentration of oxidizer was used while maintaining the pH at 2. Similarly, the effect of oxidizer concentation was carried out at pH 2, maintaining abrasive concentration at 1 wt%. Slurry pH was adjusted using HNO3 or KOH. Electrochemical studies were performed to understand the chemical dissolution of Ru. All the electrochemical runs were conducted using 1 wt% oxidizer concentration. Three electrode configuration with platinum counter and Ag/AgCl reference electrodes were used for the electrochemical studies. A scan rate of 1 mV/s was used for potentiodynamic polarization studies and the EIS runs were performed at OCP between the frequency range 100 kHz and 0.01 Hz. Results: The effect of pH on Ru RR reveals that the Ru RR is maximum at pH 2, decreases at pH 3 and increases till pH 7 and decreases gradually in the alkaline region. The effect of abrasive loading on Ru RR in presence of 1 wt% KBrO3 at pH 2 shows that the removal rate of Ru increases significantly till abrasive loading of 3 wt% and saturates after that. The effect of oxidizer concentration on Ru RR in presence of 1 wt% titania at pH 2 shows that the Ru RR increases with increase in oxidizer concentration of the slurry due to the formation of oxide layer on the surface which is removed with the help of polishing pad and/or the abrasive particles. The potentiodynamic polarization curves of Ru (as shown in Fig. 1) at various pH values in presence of 1 wt% KBrO3 were studied. I corr value of ruthenium in KBrO3 solution at various pH follows a trend similar to the CMP RR. Fig. 1 shows the Nyquist plot of Ru at various pH values in presence of 1 wt% KBrO3. The Nyquist plots of Ru exhibits capacitive loop at high frequency with depressed semicircle. Discussion: It has been reported that the isoelectric point of ruthenium oxide ranges from 4 to 6 and titanium (IV) oxide ranges from 5 to 6 [1-3]. Therefore, Ru and titania particles act as positively charged at low pH [4]. KBrO3 dissociates to form K+ and BrO3 - ions. Bromate ions surround the titania particles. Thus the particle charge is negative in the presence of KBrO3. Due to the opposite charge between the abrasive particle and the ruthenium surface, there exists a strong electrostatic interaction, which causes higher removal rate at lower pH.

Parametric Study of Silica Precipitation from Geothermal Brine

The effects of reaction temperature, reaction time, and concentration of sodium hydroxide (NaOH) on yield and spectral similarity correlation (Corr) of silica harvested from geothermal brine are determined. The yield of geothermal silica is observed to increase when the reaction temperature is decreased, and when reaction time and NaOH concentration are increased. The Corr value is observed to increase when reaction temperature, reaction time, and NaOH concentration are decreased. The main effect of NaOH concentration and temperature significantly affects the yield and Corr of geothermal silica, respectively. To produce geothermal silica of high yield and spectral similarity to commercial silica filler for polymer, the optimum condition to precipitate silica from geothermal brine is predicted at temperature= 28°C, reaction time=12 h, and NaOH concentration= 7.5 %w/w.

Comparison of structural, mechanical and corrosion properties of thin TiO 2 /graphene hybrid systems formed on Ti–Al–V alloys in biomedical applications

Abstract In this paper, comparative studies on the mechanical and corrosion properties of hybrid coating systems based on titanium dioxide thin films (200 nm) and graphene monolayers have been investigated. The pure titanium dioxide layers were deposited on a Ti6Al4V alloy surface using the conventional magnetron sputtering process and the so-called “magnetron sputtering with modulated plasma” process. A graphene monolayer was transferred to a titanium alloy substrate using the “PMMA-mediated” method. The structural characteristics of the obtained thin films were examined by using Raman spectroscopy, X-ray diffraction (XRD), a scanning electron microscope (SEM) and atomic force microscopy (AFM) measurement. The mechanical properties, i.e. hardness, were tested by using a nanoindenter test. The corrosion properties of the coatings were determined by analysis of the voltammetric curves. The deposited TiO 2 thin film prepared by the conventional magnetron sputtering process consisted of visible grains with the size of ca. 50–100 nm and had a nanocrystalline anatase phase (TiO 2 (a)). The TiO 2 thin film deposited by plasma-modulated sputtering had a nanocrystalline rutile structure TiO 2 (r) and its surface consisted of big, irregular grains and was not as homogeneous as the coating prepared by the conventional method. The hardness of TiO 2 (a) and TiO 2 (r) thin films was equal: 7.59 GPa and 14.2 GPa, respectively. Graphene transferred to a titanium dioxide thin film surface was a single layer without defects. Unfortunately, the nanoindentation method, used to measure the hardness of the titanium dioxide/graphene coating systems, is not sensitive to one or few atomic layers of graphene deposited on the top of the coating structures. Therefore, the measurement did not reveal changes of titanium dioxide thin film hardness after graphene deposition, in comparison with uncoated TiO 2 thin films such as TiO 2 (a) and TiO 2 (r) thin films. Futhermore, the graphene monolayer can be very easily removed from the titanium dioxide thin film surface (e.g. by scratching). The best corrosion properties (the lower value of corrosion current density) were obtained for sample Ti6Al4V coated with a TiO 2 (a) thin film. A deposition graphene monolayer on the top of all tested thin films improves the corrosion potential (E corr ) value, which is much more positive than E corr registered for the other samples. A positive value of the corrosion potential is characteristic of materials with low electrochemical activity and thereby very good corrosion resistance. Moreover, these coatings systems maintain stability of the mechanical properties during the corrosion process.

Instrument Development Sports Risk Management Practice Using Rasch Measurement Model

Instruments Sports Risk Management Practices (APRS) was constructed to identify risk management practicesamong coaches IPG sports in Malaysia. This study was conducted to prove the validity and reliability of APRSby building Rasch model. The respondents comprised of coaches and athletes IPG which represents IPGMs theGames Institute for Higher Education 2013. Validity and reliability of the questionnaire were measured usingWinsteps software version 3.69.1.11. The results showed that the reliability index for the item and therespondents are respectively 0.75 and 0.99. In terms of polarity, each item is capable of measuring APRS coachwith the Institute of Teacher Education Malaysia PTMEA CORR value between 0.15 to 0.85. Incompatibilitytest items showed no item should be dropped because the outfit mean-square value is in the range of 0.6 to 1.4and test unidimensionality shows the standardized residual variance was 50.9%, equivalent to the model of 50.9%with the largest secondary dimension in contrast to the first record variance of 5.6 %. APRS capable ofmeasuring constructs built the identification, evaluation, selection and implementation of operations.

Corrosion Fatigue Behavior of Submerged Arc Welded High Strength Steel Used in Naval Structures

Corrosion prevention is a major concern for naval structures particularly for welded joint of high strength steel. Although cathodic protection (CP) is still widely used to prevent corrosion of structural steels in marine environment, effectiveness of CP has not been proven for structural steels with a yield stress above 400 MPa. In the present investigation, high strength steel plate of DMR 249A was welded by Submerged Arc Welding (SAW) process and the corrosion fatigue tests were performed on weld metal in air and 3.5% NaCl solution at room temperature with R ratio of 0.1 and a cyclic frequency of 0.01 Hz with and without cathodic potential. Optimum cathodic potential for weld metal was also evaluated in unstressed condition from the minimum corrosion coefficient among four potentials (under at -800, -875, -950, -1025) mV based on potentiostatic polarization curves (E corr value) of weld metal. Corrosion fatigue results suggest that optimum cathodic potential data (-875 mV) determined in unstressed condition could be used to improve the corrosion fatigue life of weld metal used in naval structure.

Corrosion behaviour of heat treated boron free and boron containing Ti–13Zr–13Nb (wt%) alloy in simulated body fluid

The corrosion behaviour of heat treated Ti-13Zr-13Nb (TZN) and Ti-13Zr-13Nb-0.5B (TZNB) alloys in Hank's solution has been investigated. The microstructure of the heat treated TZN alloy consisted of α, β or martensite. Addition of boron to TZN alloy led to the formation of dispersed TiB particles and modification of microstructure. In general, the furnace cooled TZN sample showed lower corrosion potential (E(corr)) than the air cooled sample. Aging of water quenched samples decreased the E(corr) value. The passive current density of TZN samples varied within a narrow range. Presence of boron in TZN alloy decreased the corrosion potential and substantially increased the passive current density. Results showed that boron deteriorated the corrosion resistance of TZN alloy.

Electrochemical impedance studies of modified Ni–P and Ni–Cu–P deposits in alkaline medium

Ni–P and Ni–Cu–P deposits were supported over the commercial carbon using the electroless plating technique. The formed samples were characterized by applying SEM, XRD and EDX analyses. An amorphous Ni–P surface was obtained with 73.70 wt% Ni and 11.45 wt% P. The addition of copper to the plating bath reduces the deposited amount of nickel and phosphorus. The electrochemical performance of these deposits has been investigated in 0.1 M KOH solution using electrochemical impedance spectroscopy (EIS) measurements. The effect of pH, deposition time and temperature of the plating bath on the impedance characteristics of the two deposits was studied. It was found that the resistance ( R T) and relative thickness (1/ C T) of the two coatings in 0.1 M KOH solution increase with increasing either pH or deposition time or temperature of the plating bath. Our results indicate that Ni–Cu–P deposit has more corrosion resistance and lower corrosion current density ( i corr) value than Ni–P deposit under different conditions. EIS results were well confirmed by potentiodynamic polarization and cyclic voltammetry techniques.

A new association between polymorphisms of the SLC6A7 gene in the chromosome 5q31–32 region and asthma

The human chromosomal 5q31-33 region has been implicated as a susceptibility locus for several immune-mediated diseases including asthma in several populations. Recently, the extraneuronal GABAergic system has been implicated as a new link to airway obstruction in asthma. In addition, the SLC6A7 gene, which is positioned at 5q31-32 and encodes the transporter for an excitatory neurotransmitter of L-proline, has never been studied for its association with asthma. In this study, resequencing of all exon, promoter region (2 kb), and exon-intron boundary regions in the SLC6A7 gene found a total of 33 single nucleotide polymorphisms (SNPs) in 24 Korean asthmatic patients. After the initial SNP survey, a total of 17 common SNPs with minor allele frequency (MAF) over 10% were genotyped in 498 asthmatic patients and 303 normal controls. Logistic analyses revealed significant associations between genetic variants of the SLC6A7 gene and asthma (P-value up to 6.0 x 10(-4); P(corr) value up to 0.009). In further regression analyses, minor alleles of intronic +11431T>C, +12213C>T and +12927A>G in linkage disequilibrium block 2 and +20113T>C in 3'UTR significantly increased the bronchodilator response in asthmatics (P-value of recessive model up to 0.008; which are not significant after multiple correction). Therefore, our findings suggest that SLC6A7 could be a susceptible gene for asthma.

Structure of Water in the Vicinity of Amphoteric Polymers as Revealed by Vibrational Spectroscopy

The water incorporated in a thin film of amphoteric terpolymers composed of various ratios of methacrylic acid (MA), N-[3-(dimethylamino)propyl]methacrylamide (DMAPMA) and n-butyl methacrylate was analyzed using the band shapes of the O–H stretching in the infrared spectra. At an early stage of sorption of water into the polymer film, the O–H stretching band for the water incorporated in the film with comparative contents of MA and DMAPMA residues was similar to that for bulk water. These results clearly indicate that the amphoteric polymers with comparative contents of cationic and anionic groups do not significantly disturb the hydrogen-bonded network structure of water, probably due to the counteraction of the electrostatic hydration effect by the proximity between the anionic and cationic side groups. The number of platelets adhered to the film with comparative contents of MA and DMAPMA residues was relatively the smallest among the examined terpolymer films, which suggested a correlation between the mildness of the charge-balanced polymeric materials to the structure of incorporated water and their blood-compatibilities. In addition, the structure and hydrogen bonding of water in an aqueous solution of co-polymers composed of various ratios of MA and DMAPMA or [3-(methacryloylamino)propyl]trimethylammonium chloride (MAPTAC) were also analyzed using the contours of the O–H stretching in the polarized Raman spectra. The number of hydrogen bonds disrupted due to the presence of one monomer residue (N corr value) for PolyMA was largely positive, and with an increase in the content of the DMAPMA or MAPTAC residues, the N corr value became smaller, and after passing a minimum (which was still slightly positive) at a roughly equivalent molar ratio, the N corr value increased again. This is in a significant contrast with the largely positive N corr values for the homo-polymers (PolyMA, PolyDMAPMA and PolyMAPTAC), and other ordinary polyelectrolytes. The effect of the charge-balanced co-polymer on the hydrogen-bonded network structure of vicinal water observed by Raman spectroscopy was in accordance with that of the charge-balanced terpolymer film observed by infrared spectroscopy.