Blank Samples Research Articles

Simultaneous determination of 28 fragrance components in cosmetics by gas chromatography-tandem mass spectrometry

With the increasing number of cosmetic products, their flavor and fragrance components are receiving greater and greater attention. Establishing an analytical method of determining these components in cosmetics is one of the most effective measures to eliminate consumers' concerns. In this study, a method for the simultaneous determination of 28 fragrance residues in cosmetics by gas chromatography-tandem mass spectrometry (GC-MS/MS) was developed. The samples were extracted using methanol and those containing more oil and grease were purified using a neutral alumina solid-phase extraction column, whereas those with more complex compositions were purified by QuEChERS. The analytes in the samples were measured by GC-MS/MS, characterized using their retention times and characteristic ion pairs, and quantified with an external standard. The respective limits of detection (LODs, S/N=3) and quantification (LOQs, S/N>10) of the compounds were in the ranges 2-20 and 5-50 μg/kg. The linearities of the concentration curves of the 28 substances were good in the ranges 1-100, 2-200, 4-200, and 10-1000 μg/L, and the correlation coefficients of the quantitative ion pairs were >0.999. Twenty-eight fragrances were added to blank samples at spiked levels of 50-500 μg/kg, and the recoveries ranged from 71.3% to 120.4%, with RSDs of 1.5%-14.6%. The method could be applied in the determination of fragrances in cosmetics because it was simple, sensitive, and stable and could effectively exclude the interferences of complex matrices. The method was used to determine the fragrance components in 16 cosmetic products, and some fragrance components were detected in 12 samples. Increased attention should be paid to the safeties of fragrances and flavors used in cosmetics.

Hydration Characteristics and Mechanical Properties of Cement-Based Materials Modified by Calcined Zeolite and Montmorillonite

Montmorillonite and clinoptilolite zeolite were used as representative materials to prepare calcined clay-cement binary cementitious materials in order to study the effect of calcination treatment on the activation of clay minerals and the activity difference between layered and framed clays in this research. The influence of different calcined clay content (2%, 4%, 6%, 8%, 10%) on the fluidity, compressive strength, microstructure, phase change, and hydration heat of cement-based materials were analyzed. The calcined clay improves the fluidity of cement-based materials as compared with the uncalcined group. The addition of calcined montmorillonite (CMT) improves the development of mechanical strength, and the optimal compressive strength reaches 85 MPa at 28 days with 8% CMT. However, the activity of calcined clinoptilolite zeolite (CZL) is weak with few reaction sites, which slightly reduced the mechanical strength as compared to the blank sample. The addition of CMT changes the microscopic morphology of hydration products such as C-S-H and C-A-H, leading to the formation and transformation of ettringite in the early stage. It promotes the gradual polymerization of Si-O bonds into SiO-Si bonds simultaneously, which accelerates the early hydration process. However, CZL acts mainly as a filling function in the cementitious system. In brief, CMT as an admixture can improve the mechanical properties of cement, but CZL has little effect. This work provides a guideline for the applications of calcined clay in cement, considering the influence of clay type on workability and mechanical strength.

Collaborative resource utilization of hazardous chromium ore processing residue (COPR) and C-bearing dust during limonitic laterite sintering process

Much chromite ore processing residue (COPR), which is defined as hazardous solid waste due to virulent Cr (Ⅵ), is produced from chromium salt industry. C-bearing dust from steel industry is a kind of typically solid waste with poor surface activity. The iron ore sintering process has the potential on large-scale harmless utilization of COPR and C-bearing dust. This study proposes a new approach of co-utilizing COPR and C-bearing dust during limonitic laterite sintering process. The negative influence of COPR and C-bearing dust on permeability was offset by the fuel attribute of extra C from C-bearing dust. The results indicate that, while 6% COPR and 8% C-bearing dust were added, the tumble index and yield of the sinters were basically equal to those of the blank samples. The toxic Cr (Ⅵ) was reduced to Cr (Ⅲ) which was concentrated in high alumina spinel phases during the sintering process. The obtained sinters were identified as nontoxic, and no secondary waste was generated throughout the clean utilization process.

A simple preparation system for Tritium and Radiocarbon at the GXNU laboratory

A very simple system for preparing Tritium and Radiocarbon sample was established at Guangxi Normal University (GXNU), China. A series of 3H and 14C preparation experiments were conducted to verify the reliability of the system. The recovery rates of Tritium and graphite obtained were more than 85 %. The beam current of H− and 12C− for each sample was greater than 12uA and 40uA, respectively, which meets the requirement of AMS measurement. The measurement results of blank samples indicate the stability of the sample preparation system, and the tritium and carbon contamination introduced during the sample preparation processes were less than 3 × 10−16 and 2 × 10−15, respectively. The results show that the simple sample preparation system is compact, low-contamination, and efficient, and meets the requirements for 3H and 14C measurements.

Screening of Azotobacter, Bacillus and Pseudomonas Species as Plant Growth-Promoting Bacteria

In this study, bacteria from the genus of Azotobacter, Bacillus and Pseudomonas were isolated from the roots of Phaseolus vulgaris and used as plant growth-promoting bacteria for Sinapis alba L., Brassica napus L., Amaranthus retroflexus L., Linum usitatissimum L., Panicum miliaceum L. and Rumex patientia L. plants. The results showed that all three bacteria had different effects on plants growth considering both sterile and non-sterile soil. Bacillus sp. induced the greatest influence in terms of the root length of Sinapis alba L. grown in sterile soil (with 28%), while considering non-sterile soil, Pseudomonas sp. increased the root and shoot length by 11.43% and 25.15%, respectively, compared to the blank sample. Azotobacter sp. exerted the highest beneficial influence on Brassica napus L. growth in non-sterile soil, since the root and shoot lengths were stimulated with 27.64% and 52.60%, respectively, compared to uninoculated plants. Bacillus sp. had a positive effect on the growth of the shoot length of Amaranthus retroflexus L. (with 30.30% in sterile soil and 3.69% in non-sterile soil compared to the control). Azotobacter sp. stimulated the growth of the root length of Rumex patientia L. with 35.29% in sterile soil and also the shoot length of Panicum miliaceum L. in non-sterile soil by 20.51% compared to the control. Further, the roots and shoots of Linum usitatissimum L. grown in non-sterile soil and in the presence of Pseudomonas sp. increased by 178.38% and 15.08%, respectively, compared to the flax grown in sterile soil. Statistically, according to Tukey’s Honestly Significant Difference (HSD) test results, not all observed differences in plants grown with the selected bacteria are significantly different compared to the control.

Development of a Quantitative Colour-Based Software Method to Evaluate the Effectiveness of Active Antioxidant Packaging on Fresh Sliced Mushrooms

A software-based procedure consisting of colour measurement of mushrooms was developed for assessing the effectiveness of a new antioxidant active packaging. As active agents, sodium metabisulphite combined with citric acid, green tea extract combined with α-tocopherol and purple carrot extract were evaluated. After obtaining the image of mushrooms with a conventional flatbed scanner, a MATLAB code was specially designed to obtain and compare histograms. Then, data were processed using principal component analysis (66% of the accumulated variance explained) and a successful classification of samples according to their age and antioxidant system was obtained. The developed procedure greatly exceeded the discrimination capabilities of other commonly used methods such as CIE L*a*b* (which was unable to find any significant difference between blank and antioxidant-treated mushrooms; L*blank = 70 ± 3; L*metabisulphite = 75 ± 5; L*green tea = 75 ± 5; L*carrot = 69 ± 5) and visual panel (where only sodium metabisulphite sample was perceived to be significantly different from the rest of the samples, with 27 positive votes out of 50). The developed method classified correctly up to 90% of blank samples according to their age. Besides, 100% and 70% of the mushrooms treated with sodium metabisulphite and green tea, respectively, were found to be fresher than their corresponding blanks. Among samples with sodium metabisulphite, 33% behaved as one-day blank samples, and 67% acted as 4-day blank samples, while among samples with green tea, 10% were found in the 1-day group, and 60% were found in the 4-day group. In contrast, purple carrot proved to be inefficient as an antioxidant. Thus, the difference between blank mushroom samples and those treated with antioxidants was objectively measured.

Assessment of Corrosion Protection Performance of FeOOH/Fe3O4/C Composite Coatings Formed In Situ on the Surface of Fe Metal in Air-Saturated 3.5 wt.% NaCl Solution

The purpose of this work is to evaluate the corrosion-inhibition behavior of deposited carbon and some iron-oxide hybrid coatings which derived from the in situ deposition method on the surface of Fe foil. Various contents of precursor methane gas were deposited over a mild iron foil substrate and formed different composites. It was found that the incorporation of C into the Fe matrix led to a thin film on the surface of the matrix and produced an anti-corrosion effect. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and potentiometric tests were used to compare the corrosion behaviors of the films in air-saturated 3.5 wt.% NaCl solution. According to the results, Fe-oxide- and C-composite-coated iron foil has a much higher corrosion resistance than the raw blank sample without the addition of C. Generally, the corrosion charge transfer resistance of one kind of iron oxide coated with carbon layers of several nanometers was enhanced up to 28,379 times (Rct changes from 1487 Ω cm2 to 4.22 × 107 Ω cm2), which is the biggest improvement so far. The maximum protection efficiency was obtained for the in situ grown coating prepared by 10 and 15 sccm CH4 precursor gas (eta = 100%). In conclusion, an iron oxide and carbon composite was found to be a great candidate for applications in the corrosion-resistance area.

Simultaneous Method for Selected PBDEs and HBCDDs in Foodstuffs Using Gas Chromatography-Tandem Mass Spectrometry and Liquid Chromatography-Tandem Mass Spectrometry.

Flame retardants are added to consumer products to retard the ignition of combustible materials. Technical mixtures of polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) were massively used for several decades. They are bioaccumulative, persistent, and have adverse effects on organisms. Recognised as persistent organic pollutants, they are banned almost worldwide. Food is the principal source of human exposure. Yet, no maximum residue limits for food have been established in the EU. Nevertheless, monitoring of specific congeners is recommended. Simultaneous analysis of HBCDDs and PBDEs is rarely encountered, especially including BDE-209, as this thermally unstable congener is particularly challenging for analysis. We have developed a method for the simultaneous determination of all relevant PBDEs and HBCDDs recommended for monitoring by the EU. In the method, single sample preparation is used for different types of foodstuffs, applying ultrasound-assisted extraction, clean-up by gel permeation, and adsorption chromatography. Analyses were performed on the same extract, first by GC-MS/MS(EI) method for PBDEs and followed by LC-MS/MS(ESI) method for HBCDDs. The analytical method was validated on a blank sample of milk formula at 2-3 fortification levels, including recommended LOQ level of 0.01 µg/kg wet weight. Satisfactory accuracy with recoveries 85-119%, intra-day precision (1.5-11.3%), and inter-day precision (4.3-18.4%) was obtained. The method ensures LOQs that are compliant with the EU recommendations for all PBDEs and HBCDDs, including BDE-209. Method applicability was further confirmed on proficiency testing samples of baby food, fish, and citrus.

A reference methodology for microplastic particle size distribution analysis: Sampling, filtration, and detection by optical microscopy and image processing

AbstractMicroplastic (MP) contamination in natural water circulation is a concern for environmental issues and human health. Various types of polymer materials have been identified and were detected in MP analytic test procedures. Beyond MP polymer type, particle size and form play a major role in water analysis due to possible negative toxicologic effects on flora and fauna. However, the correct quantitative measurement of MP size distribution over several orders of magnitude is strongly influenced by sample preparation, filtration materials and processes, and microanalytical techniques, as well as data acquisition and analysis. In this paper, a reference methodology is presented aiming at an improved quantitative analysis of MP particles. An MP analysis workflow is demonstrated including all steps from reference materials to sample preparation, filtration handling, and MP particle size distribution analysis. Background‐corrected particle size distributions (1–1000 µm) have been determined for defined polyethylene (PE) and polyethylene terephthalate (PET) reference samples. Microscopically measured particle numbers and errors have been cross‐checked with the total initial mass. In particular, defined reference MP samples (PE, PET) are initially characterized and applied to filtration experiments. Optical microscopy imaging on full‐area Si filters with subsequent image analysis algorithms is used for statistical particle size distribution analysis. To quantify the effects of handling and filtration, several blind tests with distilled water are carried out to determine the particle background for data evaluation. Particle size distributions of PE and PET reference samples are qualitatively and quantitatively reproduced with respect to symmetry, and maximum and cut‐off diameter of the distribution. It is shown that especially MP particles with a radius of >50 µm can be detected and retrieved with high reliability. For particle sizes <50 µm, a significant interference with background contamination is observed. Data from blank samples allows a correction of background contaminations. Furthermore, for enhanced sampling statistics, the recovery of the initial amount of MP will be qualitatively shown. The results are intended as an initial benchmark for MP analytics quality. This quality is based on statistical MP particle distributions and covers the complete analytic workflow starting from sample preparation to filtration and detection. Microscopic particle analysis provides an important supplement for the evaluation of established spectroscopic methods such as Fourier‐transform infrared spectroscopy or Raman spectroscopy.

Significantly Affected Lubrication Behavior of Silicone Oil Lubricated Si3N4/Glass Contact after Cleaning with Different Solvents

Conventional methyl silicone oils have poor lubricating properties in boundary lubrication regions, particularly for ceramic/oxide point contact lubrication. In this study, the residues of various organic solvents on the surfaces of Si3N4 spheres/glass disks were used to determine their effect on the lubricating properties of silicone oil 200. The minute ethanol residues significantly enhanced the antifriction and antiwear properties of silicone oil. Compared to the blank sample, the coefficient of friction (COF) and wear volume of silicone oil 200 with the residual ethanol friction pair were reduced by >40% and >98%, respectively. Being immiscible with silicone oil, the minute ethanol residues also removed impurities from the glass surface and maintained a clean interface, thus effectively blocking direct interactions between the friction pair interfaces. In addition, the residual ethanol reduced the atomic force microscope probe-to-glass surface adhesive force in the silicone oil 200 environment, thus allowing it to maintain low COF and wear rates over a broader range of speeds, loads, and times. In contrast to previous work, this study is the first to effectively regulate the lubrication properties of silicone oil using a residual organic solvent. The findings further verified that the adsorption of vapor molecules can significantly alter the surface forces between interfaces. Thus, adjusting the adhesion force through trace amounts of organic solvent residues may provide novel research inputs, thereby guiding the expansion and scope of silicone oil lubrication applications.

Preparation and properties of Ag-loaded zinc oxide antibacterial coating on medical cobalt-chromium alloy

Medical cobalt-chromium alloy has been widely used in oral implants due to its excellent mechanical properties, corrosion resistance, etc. However, its antibacterial properties should be improved as an implant. In this paper, nano-zinc oxide and Ag-loaded zinc oxide coating were prepared on cobalt-chromium alloy using the hydrothermal and photoreduction methods, and the influencing factors of the preparation process were studied. The effects of pH, hydrothermal temperature and time on the morphology of nano-sized zinc oxide were investigated. The results show that the zinc oxide has satisfactory morphology when the hydrothermal time is 3.0 h, hydrothermal temperature is 100 ℃, and pH value is 9.5. The effects of light intensity, illumination duration and AgNO3 concentration on the size and dispersion of silver nanoparticles on the Ag-loaded zinc oxide were studied. The results show that the Ag-loaded zinc oxide has satisfactory morphology under the illumination intensity of 0.6 W/m2 , illumination duration of 60 min and AgNO3 concentration of 1.0 mol/L. By analyzing the morphology, phase, quality and thickness of zinc oxide and Ag-loaded zinc oxide coating, it is found that the needle-like zinc oxide array is uniformly loaded with silver particles. The average thickness of the coatings is 6.80 μm, and the average weight is 1.67 mg. The antibacterial test shows that the Ag-loaded zinc oxide coating has better antibacterial performance than the pure zinc oxide coating, both of which were better than the blank control sample.

Production, characterization, and antimicrobial activity of almond gum/polyvinyl alcohol/chitosan composite films containing thyme essential oil nanoemulsion for extending the shelf-life of chicken breast fillets

In this study, thyme essential oil (TEO) nanoemulsion was immobilized within composite films based on almond gum (AG), polyvinyl alcohol (PVA), and chitosan (CS). The physical, mechanical, water barrier, microstructural and antimicrobial properties of composite films were assessed. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the intermolecular interactions in the composite film matrix. The results indicated that the incorporation of TEO into the composite films increased thickness, moisture content, and water vapor permeability, while it reduced light transmittance and transparency value. The antimicrobial activity of films against gram-negative and gram-positive bacteria was tested using a disc diffusion method. The effect of composite on the microbiological properties of chicken breast fillets was investigated during refrigerated storage for 21 days. The microbial populations of total mesophilic, psychrotrophic, and lactic acid bacteria of the samples that were coated with the composite containing TEO were lower than the permitted limit after 21 days while for blank samples they were higher than 7 log CFU/g after 7 days which is considered as the maximum acceptable total count limit. Results disclosed that AG/PVA/CS composite films containing TEO nanoemulsion can be applied as eco-friendly active food packaging to enhance the shelf-life of food products.

Labeling Terms and Production Claims Influence Consumers’ Palatability Perceptions of Ground Beef

The objective of this study was to evaluate consumers’ palatability ratings of ground beef from the same source when provided information about the labeling prior to evaluation. Chubs (n=15) from the same production lot and day of 80% lean/20% fat ground beef were procured and fabricated into 151.2 g patties. Pairs of patties from each chub were randomly assigned to one consumer panel session and to 1 of 8 different labeling terms: all natural, animal raised without added antibiotics (WA), animal raised without added hormones (WH), fresh never frozen (FNF), grass-fed, locally sourced, premium quality, USDA organic (ORG), and a blank sample (NONE). Consumers (N=105) evaluated each sample on 0-to-100-point line scales for tenderness, juiciness, flavor liking, texture liking, overall liking, and purchasing intent and also evaluated each palatability trait as either acceptable or unacceptable. Prior to sample evaluation, the consumers were provided additional labeling information about the ground beef. Consumers found no differences (P>0.05) among the samples with the different labeling terms for tenderness, juiciness, texture liking, overall liking, tenderness acceptability, flavor acceptability, and texture acceptability for all the treatments evaluated. For flavor liking, there was a larger increase (P<0.05) in ratings for samples labeled as grass-fed in comparison with WA, WH, and premium quality–labeled samples. There was a large increase (P<0.05) in the consumer ratings for overall liking when product was labeled as all natural, WA,WH, FNF, locally sourced, premium quality, and ORG. Additionally, there was a larger decrease (P<0.05) in the per-centage of samples rated as acceptable overall when labeled as WA in comparison with all other treatments. These results indicate that adding production claims that consumers are familiar with can improve their palatability perception.

Studi Pengaruh Kontaminasi Properti Rheology Water Based Mud di Lapangan Sunyu

Studi Pengaruh Kontaminasi Properti Rheology Water Based Mud di Lapangan Sunyu

Experiences in the commissioning of the first radiocarbon dating laboratory based on the carbosorb method in Tehran

In this paper, the experiences in the commissioning of the first radiocarbon dating laboratory based on the carbosorb method in Tehran are presented and described. Its purpose is to: (a) validate the predefined procedures, (b) introduce the relevant commissioning equipment, and (c) report on significant experiences in the sample preparation. The procedure of sample preparation for the carbosorb method including acid-base degreasing, carbonization, oxidizing, and refinement of CO2 gas, followed by chemical conversion to a compound suitable for C-14 dating was achieved in this work. Using a Liquid Scintillation Counter (LSC), the measurements of the prepared standard, blank, and of a modern sample were carried out and the results were discussed. The similar radiocarbon activities of blank and marble samples confirmed the minimum absorption of environmental CO2 gas during sample preparation and the measured specific activity of the wood sample proved the absorption of radiocarbon in the cocktail.

PERFORMANCE AND INTER-COMPARISON TESTS OF THE MICADAS AT THE RADIOCARBON LABORATORY OF LANZHOU UNIVERSITY, CHINA

ABSTRACTSince 2018, the radiocarbon laboratory of Lanzhou University has been equipped with a compact accelerator mass spectrometer—a 200-KV mini carbon dating system (MICADAS), together with an auto graphitization equipment (AGE III). The laboratory has for a long time prepared graphite targets for 14C dating of plant fossils, charcoal, bones, and bulk organic matter. Herein, we give an overview of the operating status and performance of the dating facility. The long-term measurements of the standard and blank samples indicated that the results for MICADAS in Lanzhou University were accurate and stable and of high sensitivity. Fifteen sets of organic materials collected from archaeological sites in northwest China were selected for an inter-comparison study involving the participation of four specialist laboratories. The 14C dating results for the homogenized archaeological samples from several of the laboratories showed a high degree of consensus. The long-term performance and inter-comparison data for MICADAS confirmed that the radiocarbon laboratory of Lanzhou University could provide stable and accurate 14C dating results. In this context, the 14C dating results for a number of key archaeological/environmental samples were validated.

THE VALIDATION OF THE METHOD FOR QUINOLONES RESIDUES DETERMINATION IN SAMPLES OF MILK, EGG POWDER, TISSUES, BLOOD PLASMA OF ANIMALS USING THE METHOD OF ENZYME-LINKED IMMUNOSORBENT ASSAY

The article presents the results of validation of screening method for the determination of quinolone antibiotics residues (enrofloxacin, ciprofloxacin, marbofloxacin, danofloxacin) in tissue samples, egg powder, milk and blood plasma using RIDASCREEN®Chinolone/Quinolones test kits from R-Biopharm (Germany). According to the information provided by the manufacturer of the kit, the quantitative determination of quinolones content of can be carried out in the following matrices: shrimp, fish, eggs, meat. In accordance with European Commission Decision 2002/657/EC, the methods proposed by the manufacturer were validated taking into account the maximum permissible levels (MRLs), and the results of the development of sample preparation techniques for the assay of liver, milk and blood plasma for various representatives of antibiotics of quinolone group and the corresponding validation results were presented.
 The suitability of the technique was confirmed on the basis of establishing of main validation parameters for screening methods (technical threshold and cut-off factor) using control (blank) samples (muscle and parenchymal tissues of poultry and animals, cow’s milk, blood plasma of broiler chickens and egg powder) and spiked with quinolones standard solutions at the level of ½ MRL according to the "added-found" criterion. The main advantages of the developed method are the simplicity of performance, rapidity and economic efficiency.
 The reliability of the results obtained by the developed method was verified using confirmatory UPLC-MS/MS method. The results of comparative study of control (blank) samples of chicken muscle tissues, egg powder and cow’s milk and spiked with enrofloxacin standard solution at the level of 2.5 and 5.0 μg/kg are presented.
 The proposed methods for liver, milk and blood plasma sample preparation can be used to study withdrawal periods and bioequivalence of veterinary drugs based on quinolone antibiotics.

Early warning of Diaporthe infection in kiwifruit soft rot by plasmonic dimer-enhanced Raman spectroscopy.

Diaporthe genus is the dominant pathogens of kiwifruit soft rot with long incubation period and rapid onset and very hard to detect in advance. It is of great significance to develop point-of-care tests for disease prevention and field management. Here we screen a pair of genus-level primers for constructing plasmonic dimer Rayleigh/Raman spectroscopy, which enables rapid, specific, and sensitive detection of Diaporthe genus in real kiwifruits. Dark-filed Rayleigh scattering clearly visualizes the target-induced dimer assembly of nanoprobes. Plasmonic dimer-enhanced Raman spectroscopy has high specificity for 12 common isolates of Diaporthe genus in one batch samples with highly accurate results and much higher sensitivity than polymerase chain reaction (PCR). It realizes the recognition of Diaporthe infection at an early stage of 24h when the kiwifruits do not have any noticeable symptoms. It demonstrates a bright prospect of point-of-care tests for early warning of kiwifruit soft rot infection and quality control.

Synthesis of High-Energy Faceted TiO2 Nanocrystals with Enhanced Photocatalytic Performance for the Removal of Methyl Orange

In this work, brookite TiO2 nanocrystals with co-exposed {001} and {120} facets (pH0.5-T500-TiO2 and pH11.5-T500-TiO2), rutile TiO2 nanorod with exposed {110} facets and anatase TiO2 nanocrystals with exposed {101} facets (pH3.5-T500-TiO2) and {101}/{010} facets (pH5.5-T500-TiO2, pH7.5-T500-TiO2 and pH9.5-T500-TiO2) were successfully synthesized through a one-pot solvothermal method by using titanium (V) iso-propoxide (TTIP) colloidal solution as the precursor. The crystal structure, morphology, specific surface area, surface chemical states and photoelectric properties of the pHx-T500-TiO2 (x = 0.5, 1.5, 3.5, 5.5, 7.5, 9.5, 11.5) were characterized by powder X-ray diffraction (XRD), field scanning transmission electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), nitrogen adsorption instrument, X-ray photoelectron spectroscopy (XPS), UV-Visible diffuse reflectance spectra and electrochemical impedance spectroscopy (EIS). The photocatalytic activity performance of the pHx-T500-TiO2 samples was also investigated. The results showed that as-prepared pH3.5-T500-TiO2 nanocrystal with exposed {101} facets exhibited the highest photocatalytic activity (95.75%) in the process of photocatalytic degradation of methyl orange (MO), which was 1.1, 1.2, 1.2, 1.3, 1.4, 1.6, 10.7, 15.1 and 27.8 fold higher than that of pH5.5-T500-TiO2 (89.47%), P25-TiO2 (81.16%), pH9.5-T500-TiO2 (79.41%), pH7.5-T500-TiO2 (73.53%), pH0.5-T500-TiO2 (69.10%), CM-TiO2 (61.09%), pH11.5-T500-TiO2 (8.99%), pH1.5-T500-TiO2 (6.33%) and the Blank (3.44%) sample, respectively. The highest photocatalytic activity of pH3.5-T500-TiO2 could be attributed to the synergistic effects of its anatase phase structure, the smallest particle size, the largest specific surface area and exposed {101} facets.

Analysis of electrochemical current noise data arising from corrosion of Al alloy in a gel electrolyte by wavelet and recurrence methods

Gel electrolytes are preferred to liquid electrolytes due to the slower movement of ions, thereby lower damage. However, the use of gel electrolytes causes an increase in corrosion susceptibility due to the non-flat surfaces of cells. The use of corrosion inhibitors is one of the most practical methods for corrosion protection. The effect of penicillin as an inhibitor in a gel electrolyte containing 3.5% NaCl was investigated on the corrosion of 6061 Al alloy. Both electrochemical impedance spectroscopy (EIS) and electrochemical current noise (ECN) techniques were employed for data collection. The ECN data were analyzed by both the wavelet transform and the recurrence methods. According to EIS data, the inhibition efficiency (IE) increased from 77% to 94% for up to 15 days. The IE values obtained from ECN data increased from 81% to 90% over immersion time. The recurrence plots of the blank sample proved the increase of pit density with increasing the immersion time from 1 day to 15 days. However, the SDPS plots of the blank sample showed an increase of pit size with increasing the immersion time from 1 to 15 days. The recurrence plots proved the inhibition effect of penicillin on the corrosion of Al alloy that is apparent from the significant lowering of vertical black lines.