Linear Correlation Curve Research Articles

Boric acids decorated polymers with Au nanoparticle anchor assisted laser desorption/ionization for qualitive and quantitative analysis of hydroxytyrosol in red wines

Hydroxytyrosol possesses a variety of biological and pharmacological activities that are beneficial to human health. However, the methodologies for its detection always suffered from problems. In this work, the gold nanoparticle modified polymer decorated with boric acids (pMBA/VPBA@Au) was synthesized and used both as the adsorbent and matrix to enrich and ionize small molecule substances through surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS). The pMBA/VPBA@Au displayed a low detection limit (8 × 10−6 M) and high selectivity (1:100) for the enrichment of hydroxytyrosol, and the linear correlation curve between the concentration of hydroxytyrosol and the intensity of MS had a good correlation (10−4-10−2 M, R2 = 0.997). Additionally, the pMBA/VPBA@Au was used to quantify hydroxytyrosol in red wines, and the contents were 0.053–0.094 μg/mL. In general, a simple and novel method for the detection of hydroxytyrosol by SALDI-MS using boric acid functionalized polymer was developed for the first time, showing a good practical application value.

In-situ Raman spectroscopic studies on electrochemical oxidation behavior of chromium in alkaline solution

The electrochemical oxidation mechanism of Cr in alkaline solution was deduced by combining electrochemistry with in-situ Raman spectroscopy. • Combined electrochemistry and in-situ Raman spectroscopy to study the electrochemical oxidation behavior of chromium in the alkaline condition. • A method for the determination of chromate by chromium electrode was presented. • The method can be applied to the determination of chromate in the electroplating solution. Chromium is a metal with high hardness, and strong oxidation resistance, doping chromium in the alloy will improve the alloy's oxidation resistance and corrosion resistance. However, the mechanisms of chromium electrodeposition, electrochemical oxidation, and corrosion are still controversial and only stay in the field of electrochemical research and lack in-situ data support. Therefore, we combine electrochemistry and in-situ Raman spectroscopy to study the electrochemical oxidation behavior of Cr in 0.5 M NaOH solution. The results show that the electrochemical oxidation behavior of Cr in the alkaline solution includes two steps. The first step is that the Cr layer loses six electrons and combines with OH − oxidized to CrO 4 2− , the second step is CrO 4 2− enriched on the Cr layer, and the Cr layer loses six electrons again oxidized to Cr 2 O 7 2− . We develop an electrochemical method for CrO 4 2− concentration detection in the chromium plating solution based on this mechanism. We obtain the linear correlation curve between CrO 4 2− concentration (0.1∼2.0 mol·L −1 ) and peak current density, which has simple, fast, and broad linear range characteristics.

Experimental study and numerical analysis on bearing capacity of 6082-T6 aluminum alloy columns under eccentric compression at elevated temperatures

This paper carried out an experimental study and numerical analyses on 6082-T6 aluminium alloy columns under eccentric loading at elevated temperatures. The mechanical properties of standard specimens were obtained from tensile tests performed at different temperatures. Thirty-two aluminium alloy columns were tested under eccentric compression at elevated temperatures to determine their corresponding bearing capacity. The experimental results showed that overall bending buckling occurred in all column specimens and that the bearing capacity of the specimens decreased with increasing temperature and eccentricity. Based on simulations of finite element (FE) models with different section dimensions and normalized slenderness ratios, the buckling bearing capacity and correlation curves of 652 aluminium alloy columns under eccentric compression were obtained. This paper proposed a new correction coefficient that can be used for design formula modification. The results can be seen that all the numerical curves are above the linear correlation curve and the proposed design formula was found to be suitable and effective through comparisons between the FEA results, test results and the modified correlation curve at different temperatures. Additionally, reliability analysis has also been conducted to evaluate the reliability level of the proposed design method for aluminium alloy columns at elevated temperatures.

Impact on degradation of antibiotics from poultry litter using Autothermal Thermophilic Aerobic Digestion (ATAD).

Tetracycline (TC) is one of the common antibiotics which is widely used in livestock growth promotion. The prevalent application TC may pave way to progression of antibiotic resistant bacteria. The main objective of this study is to determine the effect of Autothermal Thermophilic Aerobic Digestion (ATAD) on the fate of TC residues found in digested poultry litter. For the determination of TC in poultry litter, thin layer chromatography (TLC) and high performance liquid chromatography (HPLC) were done. TLC result revealed that the Rf value of standard TC on TLC plate was 0.97 which correlates with the Rf value of TC at 0, 12, 24 and 36 h of digested poultry litter sample and not at 48, 60 and 72 h. HPLC chromatogram revealed that the limits of detection and the recovery were 5 µg/kg and 96% for standard TC. Linear correlation curves were obtained over the series of 100–500 µg/mL with correlation coefficient of 0.996 and the calibration curve was Y = 0.001X + 0.066. These results confirmed the degradation of TC in ATAD digestion of poultry litter by abiotic processes.

Bearing capacity of aluminum alloy members under eccentric compression at elevated temperatures

This paper investigates the elevated-temperature flexural-torsional buckling behavior of aluminum alloy members under eccentric compression by means of experimental and numerical study. Firstly, fourteen I-shaped aluminum alloy members were tested under eccentric compression at elevated temperatures. All the members failed by flexural-torsional buckling. The test results indicated that the bearing capacity of the specimens decreases with the rise of the temperature and the increase of the eccentricity. Subsequently, finite element (FE) models were established using the non-linear code ANSYS, and were verified against the experimental results. In order to develop a further understanding, numerical analysis was carried out using numerous FE models considering two kinds of aluminum alloy brands, two kinds of section types, nine types of section dimensions and three types of temperatures. Finally, 432 correlation curves were obtained and all of them were above the linear correlation curve. Due to its simplicity, the linear correlation curve was proposed to calculate the bearing capacity of aluminum alloy members under eccentric compression at temperatures under 300 ℃. The test data were used to validate the reliability of the proposed curve. The results revealed that the proposed correlation curve is safe and economical, while the design method suggested in EC9 is more conservative, which can be used as re-checking for important structures.

Salinity impacts on water solubility and n-octanol/water partition coefficients of selected pesticides and oil constituents.

Salinity has been reported to influence the water solubility of organic chemicals entering marine ecosystems. However, limited data are available on salinity impacts for chemicals potentially entering seawater. Impacts on water solubility would correspondingly impact chemical sorption as well as overall bioavailability and exposure estimates used in the regulatory assessment. The pesticides atrazine, fipronil, bifenthrin, and cypermethrin, as well as the crude oil constituent dibenzothiophene together with 3 of its alkyl derivatives, all have different polarities and were selected as model compounds to demonstrate the impact of salinity on their solubility and partitioning behavior. The n-octanol/water partition coefficient (KOW ) was measured in both distilled-deionized water and artificial seawater (3.2%). All compounds had diminished solubility and increased KOW values in artificial seawater compared with distilled-deionized water. A linear correlation curve estimated salinity may increase the log KOW value by 2.6%/1 log unit increase in distilled water (R2 = 0.97). Salinity appears to generally decrease the water solubility and increase the partitioning potential. Environmental fate estimates based on these parameters indicate elevated chemical sorption to sediment, overall bioavailability, and toxicity in artificial seawater. These dramatic differences suggest that salinity should be taken into account when exposure estimates are made for marine organisms. Environ Toxicol Chem 2017;36:2274-2280. © 2017 SETAC.

Iron in typical and atypical parkinsonism – Mössbauer spectroscopy and MRI studies

Iron may play important role in neurodegeneration. The results of comparative studies of human brain areas (control and pathological) performed by Mossbauer spectroscopy (MS) and magnetic resonance imaging (MRI) techniques are presented. Mossbauer spectroscopy demonstrated a higher concentration of iron in atypical parkinsonism (progressive supranuclear palsy PSP) in the brain areas Substantia Nigra (SN) and Globus Pallidus (GP) involved in this pathological process, compared to control, while the concentration of iron in pathological tissues in typical parkinsonism (Parkinson’s disease - PD) did not differ from that in control. These results were compared with the changes in 1/T1 and 1/T2 (T1 and T2 being the relaxation times determined by MRI). A good linear correlation curve was found between the concentration of iron as determined by MS in different areas of control human brains and between 1/T1 and 1/T2. Whereas the finding in PSP-GP (the brain area involved in PSP) also fitted to such a correlation, this was not so for the correlation between pathological SN – the brain area involved in both diseases – and 1/T2, indicating a dependence of T2 on other factors than just the concentration of iron.

Single-sided Nuclear Magnetic Resonance for condition monitoring of cross-linked polyethylene exposed to aggressive media

The potential of single-sided Nuclear Magnetic Resonance (NMR) to monitor truly non-invasive changes in polymer materials during aging under aggressive media is for the first time evaluated. For this, the NMR method is used in combination with other condition monitoring methods including mechanical measurements, mass uptake, and differential scanning calorimetry. It is validated by studying for the first time the aging kinetics of silane cross-linked polyethylene (PEX) exposed to media used in oil and gas production and transportation, including aliphatic and aromatic hydrocarbons, sulphur solvents, and corrosion inhibitors in combination with CO2 and H2S. All investigated parameters changed, with the strongest effects detected for the NMR chain mobility and in the presence of hydrocarbons. Furthermore, a universal linear correlation curve could be established between the depression of the tensile strength and the chain mobility. This result represents a fundamental step towards establishing single-sided NMR as a new analytical tool for in situ condition monitoring of polyethylene working under sour conditions. The proposed approach can be easily extended to other polymer materials.

Residual stress prediction and control of Ta2O5/SiO2 multilayer based on layer structure designing

Residual stress, which can be inevitably introduced during the optical films deposition process, must be controlled in many applications since the surface deformation is caused. The residual stress is traditionally controlled by adjusting the process parameters. However, the process parameters are determined by other more desired properties in many fields. In these cases, layer structure is the only variable to change the residual stress status of the components. Ta2O5/SiO2 is most commonly used material pair in visible/near infrared (VIS/NIR) region. In this letter, stress behaviors of Ta2O5 and SiO2 single layers deposited by ion-assisted deposition (IAD) are studied. Stress-thickness linear correlation curves of the two materials are obtained, which agree with the commonly reported linear results. Based on these features, a kind of antireflection (AR) coating acted as back side coating is designed to control the residual stress of components by the layer structure designing. A series of AR coatings at 1 319 nm are designed, according to residual stress status desired to introduce.

Mensurações ultrassonográficas da cisterna da glândula mamária de caprino transgênico

Milk production of transgenic does was evaluated by ultrasound measurements of the mammary gland. Two Caninde goats, which were nine months of age were used in the trial, one non-transgenic or other transgenic for hG-CSF. For hormone-induced lactation, animals were given estradiol (0.25mg/kg, IM), progesterone (0.75mg/kg, IM), and prednisolone (0.4mg/kg, IM). Ultrasonographic exams were carried out during milking, using a Falcon 100 ultrasound equipment with a 5MHz convex probe and were performed by the same operator. The results were expressed as mean±standard error. The maximum greater length and shorter length of the cistern were respectively 5.14cm and 1.36cm for the transgenic animal and 7.28cm and 2.25cm for non-transgenic, which is consistent with the maximum milk volume produced. The relationship between the average area of cisterns and milk yield was expressed as a linear correlation curve, with a correlation coefficient significantly positive for both transgenic (Y=-1.1314+10.8538*x; r=0.97) and non-transgenic (Y=-21.7551+18.3634*x; r=0.97) animals. In conclusion, the ultrasound is a practice and appropriate technique to evaluate the cisterns in ruminant udders in transgenic animal.

Thioglucose-stabilized gold nanoparticles as a novel platform for colorimetric bioassay based on nanoparticle aggregation

Gold nanoparticles stabilized with thioglucose (TGlu-AuNPs), which have carboxyl groups on the particle surface as anchoring sites for covalent immobilization of biomolecules, were prepared by the chemical reduction of HAuCl 4 using 1-thio-β- d-glucose as a reducing and stabilizing agent, and their application to colorimetric bioassay was demonstrated using the carbohydrate–lectin system. p-Aminophenyl α- d-mannose (Man-NH 2) was covalently attached by a conventional method to the activated carboxyl groups on the TGlu-AuNPs. On addition of Con A to the Man-AuNPs, multiple binding events occurred between Con A and the mannoses immobilized on the particle surface. This Con A-induced aggregation resulted in a significant red shift in local surface plasmon resonance. The binding isotherm showed a sigmoidal curve, indicating cooperativity in the binding of Con A and the Man-AuNPs. In addition, Hill plots showed two nonequivalent binding modes, with the K d values for high- and low-affinity binding of 11.3 and 66.5 pM, respectively, which was significantly lower than that for methyl-α- d-mannose binding to Con A. The enhanced binding affinity between Man-AuNPs and Con A involves the cluster effect of the carbohydrate groups on the AuNPs. A linear correlation curve was obtained in the range 10–100 nM ( R 2 = 0.983). The limit of detection (LOD) for Con A was 9.0 nM in aqueous buffer, which is comparable to that of other conventional methods such as ELISA.

Native And Chimeric Metal-Binding Lactate Dehydrogenase As Detection And Protection Tools For Oxidative Stress Induced By Fenton'S Reaction

In the present study, a simple and reliable antioxidant screening technique based on lactate dehydrogenase (LDH) oxidation by Cu2+-mediated Fenton's reaction has successfully been developed. Oxidation of LDH by hydroxyl radical consequently leads to enzymatic inactivation, while addition of antioxidants can protect and regain enzyme activity. This method demonstrated a high feasibility on detecting of antioxidative activity of lipophilic (e.g. alpha-Tocopherol and beta-Carotene) and hydrophilic compounds (e. g. glutathione, mannitol and thiourea) in a single assay. Results from linear correlation curves revealed that the IC50 were in the order of beta-carotene (3.45 mu g/ml) > alpha-Tocopherol (52.31 mu g/ml) > Mn(II)-bacitracin (109.37 mu g/ml) > glutathione (122.63 mu g/ml). Detailed investigations revealed that oxidation of LDH resulted in enzyme degradation, which was metal- and time-dependent mechanism. Therefore, further experiments were conducted to determine whether extension of the N-terminus of LDH with metal- binding regions possesses protective effect against the inactivation process. Genetic construction of chimeric LDH carrying two and four repetitive sequences of cadmium binding peptide (CdBP), designated as CdBP2LDH and CdBP4LDH, has been carried out. From our findings, the CdBP2LDH and the CdBP4LDH exhibited protective action and enzyme activity regained 20-30 % and 70 % higher than that of the native LDH, respectively. Two possible mechanisms have been proposed to play important role in protection against metal- mediated Fenton's reaction: i) changing in redox potential of Cu2+ in metal-peptide complex, and ii) taking away of Cu2+ ion from the crucial amino acids by metal saturation at the cadmium-binding peptides.

The quantitative analysis of crystallinity using FT-Raman spectroscopy.

To establish if FT-Raman spectroscopy can be used to quantitate the degree of crystallinity in a model compound. Mixtures containing different proportions of amorphous and crystalline indomethacin were prepared. Using the peak intensity ratio 1698 cm(-1) (crystalline) to 1680 cm(-1) (amorphous), a correlation curve was prepared. This correlation curve was validated by testing further samples of known composition. Partially crystalline indomethacin was prepared by milling crystalline indomethacin. A linear correlation curve was obtained across the entire range of 0-100% crystallinity. Using this method, it was possible to detect down to either 1% amorphous or crystalline content. The largest errors were found to result from inhomogeneities in the mixing of the calibration and validation samples. The spectra of the mechanically processed samples were similar to the spectra of the calibration samples, and the degree of crystallinity could be estimated in these samples. FT-Raman spectroscopy is a potentially useful method to complement existing techniques for the quantitative determination of crystallinity.

Mixing of polar vortex air into middle latitudes as revealed by tracer‐tracer scatterplots

The occurrence of mixing of polar vortex air with midlatitude air is investigated by examining the scatterplots of insitu measurements of long‐lived tracers from the NASA ER‐2 aircraft during the Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE, April, May 1993; northern hemisphere) and the Airborne Southern Hemisphere Ozone Experiment / Measurements for Assessing the Effects of Stratospheric Aircraft (ASHOE/MAESA, March‐October 1994; southern hemisphere) campaigns. The tracer‐tracer scatterplots from SPADE form correlation curves which differ from those measured during previous aircraft campaigns (Airborne Antarctic Ozone Experiment (AAOE), Airborne Arctic Stratospheric Experiments I (AASE I) and II (AASE II)). It is argued that these anomalous linear correlation curves are “mixing lines” resulting from the recent mixing of polar vortex air into the middle latitude environment. Further support for this mixing scenario is provided by contour advection calculations and calculations with a simple one‐dimensional strain‐diffusion model. The scatterplots from the midwinter deployments of ASHOE/MAESA are consistent with those from previous midwinter measurements (i.e., no mixing lines), but the spring CO2:N2O scatterplots form altitude‐dependent mixing lines which indicate that air from the vortex edge region (but not from the inner vortex) is mixing with midlatitude air during this period. These results suggest that at altitudes above about 16 km the mixing of polar vortex air into middle latitudes varies with season: in northern and southern midwinter this mixing rarely occurs, in southern spring mixing of vortex‐edge air occurs, and after the vortex breakup mixing of inner vortex air occurs.