Optical Emission Spectroscopy Research Articles

Iron, Zinc and Total Phenolic Content in Cooked Biofortified NUA 45 and Gloria Sugar Beans: The Case of Zimbabwe

Biofortification involves breeding of staple crops that are micronutrient-dense and high yielding for example iron-biofortified beans. The biofortification of crops has been found to be cost effective and feasible to fight micronutrient deficiencies. The aim of the study was to determine the iron, zinc and total phenolic composition for the biofortified NUA 45 and Gloria sugar beans in raw as well as cooked samples with and without previous soaking. Determination of iron and zinc content in the raw, cooked bean grain samples with and without soaking was carried out by Inductively Coupled Plasma (ICP) Optical Emission Spectrometry whereas the determination of Total Phenolic Content was done using the Folin-Ciocalteau colorimetric method. The highest zinc concentration (0.295ppm) was found in raw Gloria sugar beans whilst the raw NUA 45 sugar beans had the highest iron content (0.755ppm) and total phenolic composition (352.8mg/100g). For the cooked bean samples Gloria sugar beans had the highest zinc concentration (0.247ppm) cooked after soaking. NUA 45 sugar beans had no significant difference on the zinc content after being cooked with and without soaking. Amongst the cooked samples the biofortified NUA 45 sugar beans cooked after soaking had the highest iron content (0.373ppm) as well as the highest total phenolic content in the beans cooked without soaking (200.5mg/100g). Biofortified NUA 45 and Gloria sugar beans proved to be good sources of iron, zinc and phenolic compounds. However, cooking with and without soaking diminished the iron, zinc and the total phenolic composition of the cooked NUA 45 and Gloria sugar beans.

Investigating the Level of Metal’s Toxicity in Used Cell Phone Batteries by TCLP and WET Methods

Introduction: Batteries are widely used in all kinds of electrical and electronic equipment. These batteries contain several metals that lead to the leakage of metals into the soil and underground water in the burial places, which pose serious risks to human health and the environment. Materials and Methods: In this study, the concentration of 15 metals (Ag, Al, As, Ba, Cd, Co, Cs, Cu, Fe, Li, Mn, Pb, Sr, Zn, Ni) in different components of 7 used battery models was investigated using Waste Extraction Test (WET) and Toxicity Characteristic Leaching Procedure (TCLP) toxicity. The concentration of metals was measured by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Metal concentrations were compared with the United States Environmental Protection Agency (USEPA) and California Department of Toxic Substances Control (CDTSC) standards. Results: The results showed that the average concentration of metals in both WET and TCLP methods was high, but the concentration of most metals in WET method was relatively higher than in TCLP method. Conclusion: The results showed that the recovery of metals from batteries is necessary, moreover safe burial of batteries is essential to reduce environmental risks.

Characterization and potential application of microspheres from sodium alginate cross-linked with pectin from Citrus depressa Hayata’s peels

BackgroundPectin from Taiwan Citrus depressa Hayata’s peels (CDH pectin) and sodium alginate (Na alginate) were mixed in neutral acidity to produce microhydrogel beads or microspheres. The potential use of the microspheres such as encapsulation materials for quercetin and nobiletin, DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity, toxic elements absorption ability, and thermal characteristics were explored.ResultsDifferent ratios of CDH pectin and Na alginate produced microspheres of varying sizes and shapes. The highest yield (47.59%) with the broadest diameter was obtained at a Na alginate—CDH pectin ratio of 2:1, while the smallest yield was obtained from Na alginate—CDH pectin ratio of 1:3 (24.13%). Increasing the amount of Na alginate resulted in more spherical microspheres, higher heavy metals (cobalt and nickel) removal rates, yet a lower swelling ratio. A high pectin concentration also increased the encapsulation efficiency of quercetin and nobiletin, reaching 91.5% and 86.74%, respectively. Quercetin and nobiletin release analysis (in vitro) showed a slow release of drugs from the microspheres. Less than 20% quercetin and nobiletin were released from the microspheres in SGF (simulated gastric fluid) pH 1.2 solution after 2 h and more than 40% of the encapsulated drug was released in SIF (simulated intestinal fluid) pH 6.8 after 4 h. The strong DPPH scavenging activity of quercetin (99%) was not hindered by encapsulation materials. ICP-OES (inductively coupled plasma–optical emission spectrometry) analysis demonstrated that the biopolymer can absorb cobalt and nickel from water. Thermogravimetric analysis (TGA) result showed that the combination of CDH pectin and Na alginate produced a biopolymer that exhibited a weight loss of only 1.86–4.33% at 100 °C.ConclusionsThese findings suggest that microspheres produced from CDH pectin cross-linked with sodium alginate had potential in nobiletin and quercetin encapsulation. Moreover, the polymer could absorb heavy metals and exhibit an important characteristic for hot food and beverage packaging applications.

Upcycling acid waste gas containing H2S and CO2 into syngas and sulfur by non-thermal plasma coupled with Zn-Mo/Al2O3 catalyst

Synergistic conversion of H2S and CO2 into syngas and sulfur in one step, not only achieves harmless treatment, but also produces valuable chemicals, which is an ideal strategy for waste gas upcycling. Nevertheless, due to the kinetic inertia and high thermodynamic stability of H2S and CO2, the process of the reaction has not received enough attention. Non-thermal plasma has advantages over thermal processes in the process of enhanced conversion owning to its non-equilibrium properties. Herein, a novel method of non-thermal plasma coupled by Zn-Mo/Al2O3 catalyst was demonstrated for the simultaneous conversion of H2S and CO2. Furthermore, compared to the single component catalysts (ZnS/Al2O3 and MoS2/Al2O3), the Zn-Mo/Al2O3 catalysts with different Zn/Mo ratios had excellent catalytic performance. In particular, the ZM(4/4) catalyst showed complete conversion of H2S and approximately 62 % of CO2 conversion, with the highest energy efficiency of 0.95 mmol/kJ and 120 h long-term stability. Meanwhile, the mechanism of the synergistic reaction between non-thermal plasma and catalysis was revealed by means of in-situ optical emission spectrometry. This study offers a new strategy for catalyst design for the highly efficient conversion of H2S-CO2 acid waste gas via plasma-catalytic method, and highlights the synergy between Zn-Mo/Al2O3 catalyst and non-thermal plasma to promote catalytic performance.

Ion chromatography coupled with optical emission spectrometry (IC-ICP-OES) methodology for the analysis of inositol phosphates in food and feed

This study presents the development of ion chromatography coupled with inductively coupled plasma optical emission spectrometry (IC-ICP-OES) for the simultaneous determination and quantification of inositol phosphates (InsPx). Using a CarboPac PA100 column with a nitric acid-water gradient, 28 InsPx isomers (InsP6 to InsP2) were separated within 33 min. The method eliminates baseline drift and post-column derivatization thereby simplifying detection and quantification. It achieves low detection limits of 63 μg/L P across a range of 63–3200 μg/L P. Various extraction and sample preparation methods for food and feed matrices were tested, including acidic and alkaline agents, C18 SPE and spin concentrators. The analysis shows intra-day and intra-laboratory reproducibility with deviations smaller than 1 % for standard solutions and under 4 % for feed samples (80 % recovery rate of phytate). This methodology is applicable to explore enzymatic degradation pathways and the analysis of InsPx in complex food and animal feed matrices.

Cloud point extraction and characterization of zinc oxide nanoparticles isolated from infant milk formulas

The increasing presence of nanoparticles in food products, especially in those consumed by sensitive populations like infants, raises justified health concerns. The presence of zinc oxide nanoparticles (ZnO-NPs) in three different commercial infant milk formulas were analyzed. In addition, one maternal food supplement was included in this study. Notably, existing regulations lack specificity regarding the size distribution of nanoparticles (NPs) and the maximum permissible concentrations in commercial infant products. Except in one sample, the total zinc content exceeded the reported amount in the nutritional label, which varied from 34 to 119 µg/g. This work validated the cloud point extraction (CPE) technique for the effective isolation of ZnO-NPs from the selected products. CPE was then used to evaluate the ZnO-NPs concentrations in commercially available infant formulas and maternal supplements. Using inductively coupled plasma optical emission spectrometry (ICP-OES), the ZnO-NPs and total Zn concentrations were determined. The ZnO-NPs concentration ranged from 16 to 39 µg/g, representing a considerable portion of the total zinc content. Transmission electron microscopy (TEM) analysis indicated the presence of nanoparticles with an average diameter of 6.3 nm. The NPs size could determine their cell internalization, and thus, the potential cytotoxic effects are discussed. These findings underscore the need for rigorous isolation and quantification of nanoparticles from infant milk formulas, and as an inevitable first step for in vitro and in vivo toxicity studies to address the potential health impact of nanoparticles in food products.

Analysis of discharge parameters of an argon cold atmospheric pressure plasma jet and its impact on surface characteristics of White Grapes

An argon cold atmospheric-pressure plasma (CAP) jet operated using bipolar pulsed power supply has been characterised electro-optically and the discharge parameters are optimized. An analysis has been done on the impact of the argon CAP jet treatment on the surface properties of white grapes for different treatment time period. The developed argon CAP jet is a plasma source based on dielectric barrier discharge (DBD) that has been tuned at various input parameters including applied voltage, frequency, average power consumption, and argon flow rate. Optical Emission Spectroscopy (OES) is used to identify the generated species along with plasma parameters. The collisional–radiative (CR) model is employed to extract the electron density (ne) and electron temperature (Te) from the spectra at the optimised applied voltage of 4 kV, frequency 20 kHz and argon flow rate of 4 slpm. The OES results coupled with the CR model (ne ∼ 1014 cm−3 and Te ∼ 1 eV) and the plasma gas temperature measurement through OH (A-X) transitions (Tg ∼ 310.5 K) show the non-equilibrium nature of the argon CAP jet. A comparative analysis between untreated and treated white grapes reveals that the argon CAP jet treatment influences surface microstructure, increasing hydrophilicity (with a ∼49.3% decrease in water contact angle) along with slight changes in surface temperature (∼5 °C increase), colour (ΔE* < 1.5), and physiochemical properties such as chemical composition (no change) and Total Soluble Solid (TSS) content (∼8.3%). It is inferred that this type of CAP jet treatment of white grapes only affects the physical characteristics of the grape surface and does not alter any chemical compositions.

Determination of adsorption capacity, regeneration ability, and aggregation tendency toward inorganic and organic pollutants of metal-doped carbon–silica composites in multicomponent systems

Abstract The main aim of the study was to develop a method for determining the adsorption capacity, regeneration ability, and aggregation tendency of metal-doped carbon–silica composites (iron-doped, C/Fe/SiO2, and manganese-doped, C/Mn/SiO2) against heavy metals and selected organic substances. The properties of these composites were compared with those of metal-free silica–carbon composite (C/SiO2). Inductively coupled plasma–optical emission spectrometry (ICP–OES) and high-pressure liquid chromatography were used to determine the adsorbed amounts and the desorption degree of organic/inorganic pollutants. Potentiometric titrations and electrophoretic mobility measurements were conducted to understand the mechanisms that were driving adsorption and particle aggregation. The size of the aggregates formed in the systems as well as the stability of the examined suspension were estimated by using ultraviolet-visible spectrophotometry. The performed experiments showed that the selected combination of methods is appropriate to determine the potential of metal-doped carbon–silica composites as adsorbents as well as the ease of their removal with adsorbed contaminants from aqueous solutions by sedimentation.

Multi-energy calibration and induced plasma optical emission spectrometry (MEC-MIP OES) as an alternative method for the multi-elemental determination of essential elements in cocoa.

The challenge of combining MEC-MIP OES arises from the limited number of emission lines available in this analytical technique. For the MEC-MIP OES optimization, the emission line wavelengths, sample dilution, proportion sample:standard for preparing MEC solutions, and nebulizer gas flow rate were studied. Then, the use of multi-energy calibration (MEC) and microwave-induced plasma optical emission spectrometry (MIP OES) was proposed as an alternative method for the determination of essential elements (Ca, K, Mg, Mn, and Na) in cocoa. In the optimized conditions, the method presented adequate analytical performance, with recoveries of 94-104% and relative standard deviations lower than 5%, showing adequate precision. The limits of detection (mg kg-1) were 12 for Ca, 2 for K, 3 for Mg, 3 for Mn, and 6 for Na. The proposed method was applied to analyze cocoa samples cultivated in Brazil and Ecuador after acid decomposition. The results were in the range (mg kg-1) of 409-1530 for Ca, 5520-13300 for K, 1460-3210 for Mg, 16-34 for Mn, and 28-61 for Na. Samples cultivated in Ecuador presented higher metal concentrations than the Brazilian samples. The proposed procedure was an easy and reliable approach for determining metals in cocoa samples, enabling multi-elemental determination with a lower cost and simplified calibration to be applied in routine applications.

Baru nut oil physicochemical properties, fatty acid and mineral nutritional quality: a high source of oligoelement selenium

Baru nut (Dipteryx alata Vogel) oil obtained by cold pressed machine yielded 24% (mg g–1), primarily composed of unsaturated fatty acids (⁓ 79%), with oleic and linoleic acids in the proportion of 2:1. The oxidative stability assessed by Rancimat method, Thermogravimetry analysis and Differential Scanning Calorimetry revealed thermal stability, which attributed to a higher amount of oleic than linoleic fatty acids, synergistic action of the natural antioxidants and low iodine index. The nutritional qualities were calculated to atherogenic (AI = 0.07), thrombogenic (TI = 0.22) and hypocholesterolemic/ hypercholesterolemic (HH = 13.77), and physicochemical indices: acidity (0.62), peroxide (9.99), saponification (179.93) were higher, whereas iodine (93.00) and relative density (0.9121) were found between the recommended Codex Alimentarius parameters. Mineral elements were quantified using ICP OES (inductively coupled plasma optical emission spectroscopy) in decreased order of Mg &gt; Se &gt; Zn &gt; Mn &gt; Al &gt; Cu, whereas As, Co, Cd, Cr, Fe, Ni, and Pb &lt; LOD. In addition, this oil showed optimal indices to non-cancer risk (CR &lt; 10–6), and non-carcinogenic: hazard quotient (HQ), and total hazard indices (HI) &lt; 1. Nevertheless, major attention is necessary for children and Se hypersensitive consumers, which baru oil daily consumption quantity was estimated based on selenium (Se) trace element at 0.7964 g kg–1. Thus, we recommend the consumption of baru nut oil for human health promotion and metabolic disease prevention.

Analysis of pulsed direct current reactive magnetron sputtering on a silicon target

Reactive sputtering is a very useful technique, particularly, for producing inhomogeneous interference filters, where the refractive index changes smoothly during deposition. In such a context, precise control of deposition parameters is crucial for replicating the desired optical properties. This study employed a pulsed DC power source to investigate the influence of a duty cycle on target poisoning, sputtering plasma characteristics, electric signals, and optical and morphological properties of synthesized films. Reactive pulsed DC magnetron sputtering was characterized by analyzing the behavior of plasma emission via optical emission spectroscopy and voltage-current signals, while modulating parameters such as the oxygen content within the vacuum chamber. A set of thin films was coated on glass substrates under different system conditions. These films underwent characterization employing spectroscopic ellipsometry to ascertain their optical constants, atomic force microscopy for surface morphology analysis, and x-ray diffraction for the determination of crystalline structures. The results indicate that longer duty cycles required higher oxygen levels to poison the target. Additionally, a detailed analysis of electrical signals revealed nonsquare waveforms, whose characteristics were influenced by both the duty cycle and the oxygen content within the sputtering chamber, resulting in higher effective voltages during the on-time of the voltage pulse. Grown films via reactive pulsed DC magnetron sputtering were also compared to films grown via conventional DC magnetron sputtering at equivalent conditions of target poisoning.

Development and Validation of an ICP‐OES Method to Determine Extractable and Leachable Metals in HDPE (Plastic) Pharmaceutical Packaging Material

ABSTRACTThe safety and effectiveness of pharmaceutical medicines depend heavily on extractables and leachables. Patients may be adversely affected by contaminants that enter drug products through packing materials. As a result, regulatory organizations like the European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) have set standards and regulations for evaluating and managing extractables and leachables. Characterizing the packing materials, carrying out extraction experiments and checking the extracted solutions for contaminants are all parts of this research. As part of the process for approving new drugs, regulatory agencies make use of these data. In present work, an inductively coupled plasma optical emission spectroscopy (ICP‐OES) method is developed and validated for quantifying trace elements from a high‐density polyethylene (HDPE) packaging material. The approach delineated in accordance with United States Pharmacopoeia (USP) &lt;661.1&gt; and &lt;661.2&gt; for the comprehensive analysis of 16 metallic elements including aluminium, arsenic, cadmium, chromium, cobalt, lead, mercury, nickel, titanium, vanadium, zinc, zirconium, barium, manganese, calcium and tin is applicable for evaluating the efficacy of packaging materials. The method detection limits (MDLs) complied as per USP 39‐NF 34 &lt;661.1&gt; along with relative standard deviations (RSDs) obtained were ranging from 0.3% to 3.1% and recoveries of all elements spiked at two different trace levels in HDPE samples were within 97%–110%, providing sensitive, accurate and reproducible methodology.

Microstructure characterization of plasma electrolytic oxidation coating on Hf-Nb-Ta-Zr high entropy alloy

The morphology, composition, and microstructure of plasma electrolytic oxidation (PEO) coating on Hf-Nb-Ta-Zr high entropy alloy (HEA) were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, glow discharge optical emission spectroscopy (GDOES) and transmission electron microscopy (TEM). The formation mechanism of PEO coating was analyzed. It was found that a dense PEO coating of ∼4 μm thick on the HEA surface was formed, which consisted of tetragonal and monoclinic ZrO2 phases, tetragonal and monoclinic HfO2 phases, Nb2O5 and Ta2O5 phases. The PEO coating from the alloy substrate to the surface contained five distinctive layers: amorphous barrier layer, nanocrystalline layer, columnar grain layer, amorphous outer layer, and top porous layer. Their formation was ascribed to the different cooling rates of the melt in the different depths of the discharge channel across the coating. Meanwhile, the formation of an amorphous barrier layer near the HEA substrate was also related to the mutual migration and diffusion of Hf4+, Nb5+, Ta5+, Zr4+ and O2− besides the rapid cooling of melt in the bottom of the discharge channel. The columnar grains of ∼70 nm wide were mainly composed of the monoclinic ZrO2 and monoclinic HfO2 phases, but both the amorphous layers enrich the Ta and Nb elements. It was believed that the high-content Ta and Nb in the HEA enhanced the formation of the amorphous layers.

A chemometric approach using I-optimal design for optimising Pb(II) removal using bentonite-chitosan composites and beads

This paper reports adsorption studies of Pb(II) ions onto Bentonite-Chitosan (Bt-Ch) composites or beads when using an I-optimal design experiment approach. Three adsorption factors (pH, adsorbent dosage, and initial concentration) were optimised whilst simultaneously investigating multiple adsorbents. The Bt-Ch composites and beads (type A and B) adsorbents were made using weight ratios 90%/10% and differed characteristically due to their preparation methods of solution blending and precipitation, respectively. A batch procedure was used for adsorption experiments, and the amounts of Pb(II) ions (adsorbed onto Bt-Ch composites/beads) were analysed using inductively coupled plasma optical emission spectrometry (ICP-OES). Adsorption experimental parameters were analysed and optimised by using a response surface method (I-optimal design) generated from Design-Expert® 13.0 software. The main achievements of this study were to intensify the understanding and application of I-optimal experimental designs, which allow simultaneous determination of adsorption capacities and efficiencies across multiple adsorbents in an economical manner. A reduced quadratic model provided the best fit for the experimental data and exhibited minimal deviation between predicted and experimental values. This was evidenced by the very small covariance (CV) values of 1.81% and 1.33% observed for adsorption capacity and adsorption efficiency, respectively, also suggesting high reproducibility. It was observed that the adsorption factors studied (pH, adsorbent dose, and initial concentration) have a more pronounced effect on the adsorption capacity (F-value = 714.37) compared to adsorption efficiency (F-value = 140.62). Adsorbent dosage was found to have the greatest effect on adsorption capacity, while the initial pH of Pb(II) solution had the greatest effect on adsorption efficiency. Under optimal conditions, the adsorption capacities of beads-A (73.2 mg/g) and beads-B (77.6 mg/g) were found to be higher than that of the corresponding composite (51.7 mg/g). Whilst the optimum adsorption efficiency values for all three adsorbents were ∼100% (with ranges of pH 2–5, initial concentrations 50–200 mg/L, and adsorbent dosage 0.05–0.5 mg). The desirability indexes for the optimised conditions for these respective responses (and each adsorbent) were found to be within the ranges of 0.892–0.974 and 0.945–0.967 for adsorption capacity and adsorption efficiency, respectively. These high desirability index values for both responses indicate that the optimised conditions lead to very good performance for both measures. The information obtained in this study provides detailed understanding of the adsorption phenomena of the adsorbents studied. It gives confidence in the use of I-optimal designs to be applied as a chemometric tool for the specific adsorbents studied herein and others.

Effects of mining activities and municipal wastewaters on element accumulation and integrated biomarker responses of the European chub (Squalius cephalus)

This study aimed to determine concentrations of 29 elements in the gills and liver as well as biomarker response in gills, liver, and blood of European chub from Pek River (exposed to long-term mining activities), and to compare these findings with individuals from Ibar River (influenced by emission of treated municipal wastewater) and Kruščica reservoir (source of drinking water) using inductively-coupled plasma optical emission spectrometry (ICP-OES). The metal pollution index (MPI) was also calculated. Supporting analyses for the detection of the municipal wastewater presence at investigated localities included analyses of microbiological indicators (total coliforms and Escherichia coli) of faecal pollution. We have assessed biomarker responses from molecular to organism level using the condition index, comet assay, micronucleus test, oxidative stress parameters, histopathological alterations, and fluorescence spectroscopy parameters. Multibiomarker analysis was summarized by Integrated Biomarker Response v2 (IBRv2). Among these locations, Kruščica exhibited the lowest, whereas the Pek River displayed the highest values for both categories of indicator bacteria. Due to the porphyry copper ores mining, individuals from Pek River had several times higher Cu concentrations in both gills and liver compared to the other localities which was confirmed by biomarker responses and IBRv2 value. On the contrary, fish from Kruščica reservoir were the least affected by elemental pollution which is also confirmed by low MPI and IBRv2 values. Responses of biomarkers correspond to the elemental accumulation in the liver and gills of the Ibar River are positioned between the Pek River and Kruščica reservoir. Of all the biomarkers analyzed in this study, the condition index was the least sensitive. The results of this study showed that fluorescence spectroscopy may be a method for fast screening of structural changes in gills caused by the pollution burden.

3D printed microplasma optical emission spectrometry coupled with ZIF-8 based dispersive solid-phase extraction for field analysis of waterborne arsenic

BackgroundArsenic contamination of drinking water has become a public health challenge over the world, particularly in Bangladesh, India, and China. Compared to the most used field test kits of waterborne arsenic, miniature microplasma atomic spectrometry retains advantages of accuracy, elemental specificity, and less matrix interference. Despite increased interest in arsenic detection by using miniature microplasma spectrometry, the improvements of its analytical performance, manufacturing cost and consistency still remain significant challenges. ResultsHerein, a miniature, battery-operated, and integrated hydride generation point discharge optical emission spectrometer (HG-μPD-OES, 116 mm length × 92 mm width × 104 mm height) was printed with a simple 3D printer and used for the highly sensitive and element-specific determination of arsenic by coupling to a dispersive solid-phase extraction (d-SPE) using zeolitic imidazolate framework-8 as adsorbent. The d-SPE simplifies sample treatment, significantly alleviates the interference arising from transition metal ions and improves sensitivity. A LOD of 0.07 μg L−1 for arsenic was obtained with relative standard deviations (RSDs, n = 11) better than 3.8 %. SignificanceThe 3D printing technique significantly improves the manufacturing cost and fabricating consistency of HG-μPD-OES. LOD were remarkably improved 27-fold compared to those obtained by conventional HG-μPD-OES, providing a promising method for the reliable, sensitive, and convenient field analysis of waterborne arsenic even its concentration as low as 0.2 μg L−1. The practicability and accuracy of the proposed method have been successfully verified via the field analysis of waterborne arsenic in a Certified Reference Material (GBW(E)080390) and a series of river and lake water samples.

Optical emission spectroscopy as a method for evaluating the change in Si etching structures profile in ICP SF6/C4F8 plasma: Microstructures

In this work, a method for in situ diagnostics of the etching profile of silicon structures (etching window sizes 15–400 μm) using optical emission spectroscopy was proposed. To determine the relationship between the etching profile and plasma parameters, the influence of technological parameters on the etching characteristics (vertical and lateral etching rate, selectivity in relation to photoresist, and sidewall angle) was studied. As a general parameter, which reflects the changes in plasma characteristics depending on the selected technological parameters, the parameter X (C/F ratio in SF6/C4F8 plasma) was introduced. Based on the results obtained, a general pattern between the lateral etching rate, sidewall angle, and optical emission spectra was identified. Thus, ranges of X values, at which the lateral etching rate does not exceed 5 nm/min for 15–30 μm structures and 15 nm/min for 100 μm structures, were estimated: 0.38 ≤ X ≤ 0.77 and 0.28 ≤ X ≤ 0.46, respectively. For 250–400 μm structures, ranges of X values, at which the sidewall angle is acute, straight, and obtuse, were determined: 0.16 ≤ X &amp;lt; 0.29, 0.29 ≤ X ≤ 0.41, 0.41 &amp;lt; X ≤ 0.75, respectively.

Failure Analysis of a Welded 316L Stainless-Steel Stack with Premature Damage Due to Stress-Corrosion Cracking

AbstractThis study analyzed the premature failure of a stainless-steel stack obtained from a mining company. The stack was manufactured using ASTM A240 Type 316L stainless steel. After one year of its service, massive leakages and cracks were observed near the welds. Following a visual examination of the stack, a representative sample was extracted and analyzed using visual and radiographic inspection, metallographic examination, scanning electron microscopy, energy-dispersive spectrometry, optical emission spectrometry, ferrite number analysis, and leak testing. Furthermore, corrosion mechanisms and the sequence of events leading to failure were determined. Two different mechanisms were identified: acid dew point corrosion caused by the condensation of H2SO4 and HCl at the inner walls of the chimney, followed by stress-corrosion cracking near the welded joints.

Microstructural evolution and formation of defect complexes in diamond films by nitrogen-containing plasma

Abstract The morphology and crystalline quality of polycrystalline diamond samples were studied by systematically varying the flowrate of nitrogen gas in the microwave plasma. A slight improvement in both crystallite size and crystalline quality is observed for a low concentration of 0.5 sccm nitrogen. With a further increase in nitrogen concentration, diamond switches from micro-crystalline (MCD) to nanocrystalline (NCD) with a nitrogen flow of 2.5 sccm (10% of methane concentration). The surface roughness of the sample is found to depend strongly on the crystallite size of the sample. Extensive spectroscopic studies have been done to understand the presence and formation of different defect complexes in diamond. The presence of nitrogen-containing defect complexes has been studied thoroughly and their concentration has been found to be limited by the solubility limit rather than the availability of reactants in the gas environment. In contrast, the effect these complexes have on the strain of the diamond film is found to be negligible. Optical emission spectroscopy (OES) of the plasma reveals the presence of C2 dimers as well as C-N radicals. However, they have little role in modifying diamond grain morphology or crystalline quality.

Copper abietate/polyvinyl acetate composite film for enhanced humidity sensing in Chinese herbal medicine monitoring systems

Sensing materials derived from natural and biodegradable sources are increasingly being developed and applied to realize environmentally friendly technologies. In this paper, we present the synthesis, characterization, and application of a novel copper abietate/polyvinyl acetate (CuA/PVAc) composite film, specifically engineered to enhance the humidity-sensing capabilities of Chinese herbal medicine monitoring systems. The sensing material was synthesized by strategically melding copper abietate, a natural renewable material, with PVAc to exploit their combined synergistic properties for optimal humidity-sensing performance. Comprehensive characterization techniques, including inductively coupled plasma optical emission spectrometry (ICP-OES), field-emission scanning electron microscopy (FESEM), water contact angle measurements, and Fourier transform infrared (FT-IR) spectroscopy, were employed to confirm the formation of CuA/PVAc composites. These analyses confirmed the homogeneity and intended chemical composition of the composite films.The resultant CuA-1/PVAc-4 (0.4 μg/μL) composite film exhibited a good logarithmic relation (0.9988) with relative humidity (RH) over a wide range (11 %–97 %) and high sensitivity (24.55 Hz/%RH). Moreover, this study introduces a novel, eco-friendly approach by integrating the CuA/PVAc composite with a quartz crystal microbalance (QCM) sensor and a sophisticated wireless circuit that enables real-time, Wi-Fi-based humidity monitoring tailored for the preservation of Chinese herbal medicines. The implementation of this wireless humidity detection system represents a significant advancement in the application of environmentally friendly materials in sensor technology and offers a practical and scalable approach for precise environmental monitoring.