Clean Conditions Research Articles

Immobilization of ionic liquids (ILs) on magnetic mesoporous silica nanotubes: A high throughput and reusable nanocatalyst for the green synthesis of indeno[1,2-b]indolone derivatives

The acidic ionic liquid supported on the magnetic mesoporous silica nanotubes (M-MSNTs/IL) was prepared as a new magnetic catalyst and fully characterized with FE-SEM, HR-TEM, EDS, TGA, BET, VSM, FT-IR, EDX, elemental mapping and XPS. The template of catalyst was magnetic aminated MWCNTs (M-MWCNTs/CONHBu), which removed through calcination process and magnetic mesoporous silica nanotubes (M-MSNTs) were obtained and functionalized using adenine based ionic liquid. The prepared catalyst was successfully applied as a new reusable heterogeneous catalyst for the one-pot three-component indeno[1,2-b]indole-9,10-dione derivatives in water at 75 °C. All of desired products were obtained in good to excellent yields (79–96 %) after relatively short reaction times. M-MSNTs/IL also exhibited a remarkable performance with TOF of 61.2 h-1 and TON of 86.7. The use of M-MSNTs/IL catalyst in the synthesis of indeno[1,2-b]indole-9,10-dione derivatives revealed several advantages including mild reaction conditions, high yield of pure products, clean reaction conditions, avoiding the production of toxic waste, chemical stability of the catalyst, low amount and reusability of catalyst. In addition, the applied nanocatalyst was recovered with an external magnet and reused 6 times without considerable reduction in its catalytic activity.

Experimental Analysis of the Effect of Limescale on the Wettability of Indirect Evaporative Cooling System Plates

Indirect evaporative cooling systems have attracted much interest in recent years as they guarantee good cooling effectiveness, with lower energy demand with respect to traditional systems, thus helping to address the issue of climate change. Many studies have shown that an increase in the wettability of recuperator plates results in an improvement in the system performance. However, if the water injected into the system comes from the city water supply, it will contain calcium carbonate residuals, which will form limescale layers on the plates, thus possibly changing their wetting behavior. Therefore, the wettability of three surfaces (an aluminum uncoated surface, AL, a standard epoxy coating, STD, and a hydrophilic lacquer, HPHI) was analyzed in the presence of limescale formations, and compared with that obtained in a previous study for corresponding clean surfaces. The results showed that the HPHI contact angle was reduced in the presence of limescale (median: 50°), that for STD was slightly increased (median: 81°), and that for AL was again reduced (median: 75°). Consequently, HPHI was confirmed to be the most wettable surface in both clean and limescale conditions. Finally, an analysis was undertaken evaluating the spreading factor and the reversible work of adhesion, which were in good agreement with the qualitative visual observations of the plates covered with limescale.

Symmetry of the stochastic Rayleigh equation and features of bubble dynamics near the Blake threshold

Ultrasonic cleaning is widely accepted as being an extremely efficient method of decontaminating a diverse range of objects and products. Optimization of the process is generally achieved by variation in the intensity and the spectrum of ultrasound. This spectrum takes the form of individual lines, which are superimposed on the noise background. The stochastic dynamics of the bubble in the acoustic field, consisting of a strong harmonic and noise components, is considered. Application of Lie groups reveals the internal symmetry of the problem. An analytical solution of the problem has been derived in the vicinity of the static stability threshold (Blake threshold). A greater understanding of the stochastic bubble dynamics leads to determining the optimal conditions for ultrasonic cleaning.

Spatiotemporal Variations of the Effects of Aerosols on Clouds and Precipitation in an Extreme‐Rain‐Producing MCS in South China

AbstractPrevious studies focus mostly on the storm‐scale‐averaged precipitation responses to aerosols. Yet, the spatiotemporal variations of the aerosol effects can lead to localized and short‐duration precipitation changes that are more relevant for improving rainfall forecasts. Here, we investigate the cloud and precipitation responses to aerosols during different life stages and in subregions with various cloud top heights of an extreme‐rain‐producing mesoscale convective system (MCS) in South China using the coupled WRF‐Chem model. Results show mostly similar MCS‐averaged precipitation responses between the polluted and clean conditions due to compensations among the subregions. However, the spatiotemporally discretized changes are divergent. Specifically, during the developing stage, aerosols increase precipitation in all subregions through generating larger precipitating hydrometers produced from the accretion of more cloud droplets. The most prominent precipitation enhancement occurs in the subregion with the strongest clean‐condition rainfall. In the mature stage, the CCN activation abates, and so does the aerosol‐induced precipitation increase. In the mixed‐phase (−40°C < Ttop < 0°C) and cold (Ttop ≤ −40°C) cloud top subregions, aerosols also reduce the melting of the ice‐phase precipitating hydrometers, which process becomes more important to precipitation formation during the mature stage. Therefore, the drop of rainfall rate is more significant in these ice‐phase‐involved subregions, bringing the polluted precipitation to be less than that in the clean condition during the mature stage. The substantial spatiotemporal variations of the aerosol effects and the early intensification of heavy precipitation suggest the importance of incorporating aerosols in the modeling and prediction of regional heavy rainfall events.

Zeta potential characterization of the effects of fouling and cleaning of hollow fibre forwards osmosis membrane modules

Commercial Aquaporin Inside® hollow fibre forward osmosis (HFFO) membranes embedded in lab-scale filtration modules were employed to study their fouling propensity during forward osmosis (FO) up-concentration of a fermentation broth resulting from vaccine production. The fouling and subsequent cleaning processes were analysed in terms of the lumen side active layer zeta potential of the HFFO membranes. The zeta potential indicated significant adsorption of contaminants from the feed solution on the membrane's active surface. Various cleaning conditions: alkaline, alkaline + surfactant, complexation and acidic (hydrochloric and citric), were used to investigate the potential enhancement of contaminant removal compared to a simple rinse with deionized water. Despite a full recovery of the membrane performance after cleaning, the zeta potential measurements indicated contaminants remaining on the membrane surface. The extent of this residual contamination depends strongly on the applied cleaning conditions. Rinsing with deionized water and alkaline cleaning (with or without surfactant) results in a shift in the fouled membrane isoelectric point (IEP) with a concomitant shift of the zeta potential towards the IEP and zeta potential of the pristine membrane. However, cleaning with either the complexation agent or under acidic conditions exhibits a more negative zeta potential of the fouled HFFO membranes compared to the pristine membrane, indicating an additional effect superimposed on the removal of organic contaminants.

Beauty is in the nose of the beholder: Fragrance modulates attractiveness, confidence and femininity ratings and neural responses to faces of self and others

Previous research investigated cross-modal influence of olfactory stimuli on perception and evaluation of faces. However, little is known about the neural dynamics underpinning this multisensory perception, and no research examined perception for images of oneself, and others, in presence of fragrances. This study investigated the neural mechanisms of olfactory-visual processing using electroencephalography (EEG) and subjective evaluations of self- and other-images.22 female participants evaluated images of female actors and themselves while being exposed to the fragrance of a commercially available body wash or clean air delivered via olfactometer. Participants rated faces for attractiveness, femininity, confidence and glamorousness on visual analogue scales. EEG data was recorded and event-related potentials (ERPs) associated with onset of face stimuli were analysed to consider effects of fragrance presence on face processing, and interactions between fragrance and self-other image-type.Subjective ratings of confidence, attractiveness and femininity were increased for both image-types in pleasant fragrance relative to clean air condition. ERP components covering early-to-late stages of face processing were modulated by the presence of fragrance. Findings also revealed a cross-modal fragrance-face interaction, with pleasant fragrance particularly affecting ERPs to self-images in mid-latency ERP components.Results showed that the pleasant fragrance of the commercially available body wash impacted how participants perceived faces of self and others. Self- and other-image faces were subjectively rated as more attractive, confident and feminine in the presence of the pleasant fragrance compared to an un-fragranced control. The pleasant fragrance also modulated underlying electrophysiological activity. For the first time, an effect of pleasant fragrance on face perception was observed in the N1 component, suggesting impact within 100 ms. Pleasant fragrance also demonstrated greater impact on subsequent neural processing for self, relative to other-faces. The findings have implications for understanding multisensory integration during evaluations of oneself and others.

Development and Implementation of Physics-Informed Neural ODE for Dynamics Modeling of a Fixed-Wing Aircraft Under Icing/Fault

Accurate dynamics modeling is crucial for the safety and control of fixed-wing aircraft under perturbation (e.g. icing/fault). In this work, we propose a physics-informed Neural Ordinary Differential Equation (PI-NODE)-based scheme for aircraft dynamics modeling under icing/fault. First, icing accumulation and control surface faults are considered and injected into the nominal (clean) aircraft dynamics model. Second, the physics knowledge of aircraft dynamics modeling is divided into kinematics and kinetics. The former is universally applicable and borrows directly from the nominal aircraft. The latter kinetics knowledge, which hinges on external forces and moments, is inaccurate and challenging under icing/fault. To address this issue, we employ Neural ODE to compensate for the residual between the aircraft dynamics under icing/fault and the nominal (clean) condition, resulting in a naturally continuous-time modeling approach. In experiments, we benchmark the proposed PI-NODE against three baseline methods in a dedicated flight scenario. Comparative studies validate the higher accuracy and improve the generalization ability of the proposed PI-NODE for aircraft dynamics modeling under icing/fault.

Engineering surface dipoles on mixed conducting oxides with ultra-thin oxide decoration layers

Improving materials for energy conversion and storage devices is deeply connected with an optimization of their surfaces and surface modification is a promising strategy on the way to enhance modern energy technologies. This study shows that surface modification with ultra-thin oxide layers allows for a systematic tailoring of the surface dipole and the work function of mixed ionic and electronic conducting oxides, and it introduces the ionic potential of surface cations as a readily accessible descriptor for these effects. The combination of X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) illustrates that basic oxides with a lower ionic potential than the host material induce a positive surface charge and reduce the work function of the host material and vice versa. As a proof of concept that this strategy is widely applicable to tailor surface properties, we examined the effect of ultra-thin decoration layers on the oxygen exchange kinetics of pristine mixed conducting oxide thin films in very clean conditions by means of in-situ impedance spectroscopy during pulsed laser deposition (i-PLD). The study shows that basic decorations with a reduced surface work function lead to a substantial acceleration of the oxygen exchange on the surfaces of diverse materials.

Coprecipitation as a One-Step Se Separation for Determination of Isotope Ratios Completed with Revised Uncertainty Evaluation.

This study introduces a simplified purification method for analyzing 82Se/78Se isotope ratios in diverse natural samples using hydride generation MC-ICP-MS. Unlike the thiol resin method, which is time-consuming and sensitive to the concentrations of reagents used at individual stages, our proposed alternative is quicker, simpler, and robust. The procedure involves coprecipitation of selenium with iron hydroxide and dissolution in hydrochloric acid. Combining hydride generation and a second cleanup stage achieves sufficient purification for Se isotope ratio measurements. The method is efficient, taking 3-4 h after sample decomposition, utilizing common reagents [HCl, Fe(NO3)3, NH4Cl] without evaporation or clean lab conditions. Results on 82Se/78Se isotope ratios in various matrices are presented, comparing them with literature data. All isotopic results have been subjected to a newly proposed state-of-the-art approach to uncertainty estimation dedicated to isotope ratio measurements. The approach is based on applying Monte Carlo simulations with consideration of different samples' results normalized by the expected value. By doing that, we obtained estimated uncertainty for any Se sample with the influence of particular measurements on the final estimation included. We employ a Monte Carlo simulation-based uncertainty estimation approach for isotope ratio measurements, providing estimated uncertainty for each selenium sample.

Potential risk assessment of respiratory exposure to heavy metals in the air dust for the metropolitans of Khuzestan Province, Iran

<p>The present study aimed to compare the concentration of 14 metals in the air of 4 cities of Khuzestan province (Ahvaz, Dezful, Mahshahr, and Abadan) in dusty and non-dustynon-dustyy conditions, and determine risk and non-carcinogenic risk in a six-month period from 2017 to 2018 (autumn, winter, and spring). A total of 72 samples were collected in dusty and 72 samples in non-dustydusty conditions at different locations and times using a high volume sampling pump with 110 lit/s flow rate and a fiberglass filter with the pure size of 1μm for 6 hours. Additionally, the concentration of metals was measured using the Spectro Acros Model (Germany) device. Risk assessment and probable ways of entering the body of these metals were determined using USEPA indicators. The average concentration of metals (except for Ni, Mg, and Mn) was higher in dusty conditions non-dustythan in non-dustyy conditions (p < 0.05).The concentration order of heavy metals in dusty and non-dustyy condictions was Zn>Mn>Pb>Ni>Cr>Fe>Cu, and Mg >Mn>Pb>Ni>Cr>Fe, respectively, showing the origin of Zn in the polluted air caused by dust and pollution transfer from outside into cities by this phenomenon. In children and adults, every four cities of Ding (inhalation of dust particles through direct dust consumption) were the main way to attract more metals. Chromium and nickel, chromium and magnesium, and nickel and magnesium were observed among the children of Abadan, Ahvaz, and Dezful and Mahshahr, respectively. The maximum HI indicator was observed for magnesium in Abadan, copper, and magnesium in Ahvaz, chromium, zinc, nickel, and ferrous in Mahshahr in dusty and non-dusty conditions. Moreover, lead had the maximum HI indicator in Abadan and Ahvaz in the non-dustydusty condition. Based on the HI<1 standard, in dusty and clean air conditions, all of the four cities had no concerning issues of non-carcinogenic effects for children and adults.</p>

Aerosol‐Correlated Cloud Activation for Clean Conditions in the Tropical Atlantic Boundary Layer During LASIC

AbstractAerosol measurements during the DOE ARM Layered Atlantic Smoke Interactions with Clouds (LASIC) campaign were used to quantify the differences between clean and smoky cloud condensation nuclei (CCN) budgets. Accumulation‐mode particles accounted for ∼70% of CCN at supersaturations <0.3% in clean and smoky conditions. Aitken‐mode particles contributed <20% and sea‐spray‐mode particles <10% at supersaturations <0.3%, but at supersaturations >0.3% Aitken particles contributions increased to 30%–40% of clean CCN. For clean conditions, the Hoppel minimum diameter was correlated to the accumulation‐mode number concentration, indicating aerosol‐correlated cloud activation was controlling the lower diameter cutoff for which particles serve as CCN. For smoky conditions, the contributions of Aitken particles increase and the correlation of cloud activation to accumulation‐mode particles is masked by the lower‐hygroscopicity smoke. These results provide the first multi‐month in situ quantitative constraints on the role of aerosol number size distributions in controlling cloud activation in the tropical Atlantic boundary layer.

An Evaluation of Fuzzy in Image Enhancement: Design and Comparison for Penicillium and Aspergillus Species

The main focus in this study is to enhance and classify the image of a type of filamentous fungi named Penicillium and Aspergillus. For image enhancement, fuzzy-partition gamma adaptive histogram equalization (FpGAHE) is proposed to improve the quality of an image, in particular the low quality of a microscopic image. Two stages have been considered in this technique. In the first stage, a fuzzy partition is developed to handle the inconsistency of the gray level values of the images by introducing a fuzzy set. In the second stage, surrounding neighborhood is employed to avoid the imbalance data and reduce the drastically changes of brightness values of the image. The performances are evaluated into two parts i.e., image processing and image classification by using the collected microscopic images of fungi species. To evaluate the effectiveness of the proposed technique, the existing techniques, AHE and AGC is compared to the FpGAHE. In image processing, the result attained shows that the proposed technique has a better performance by obtaining the highest value for the PSNR, SSIM and FSIM evaluation for the species of A. terreus in clean condition. Meanwhile, in image classification, five different nearest neighbor classifiers have been tested. The results show the proposed FpGAHE with Improved Fuzzy-Based k Nearest Centroid Neighbor (IFkNCN) classifier perform the best result compare to other nearest neighbor classifier by obtaining the value of 92.59 and 93.95 for the salt and pepper and Gaussian noise corrupted images respectively.

Does energy consumption matter for climate change in Africa? New insights from panel data analysis

Africa, abundant in natural resources, faces growth challenges due to widespread energy poverty and heightened biofuel use with severe environmental impacts. Recognizing the connection between energy consumption and climate change is crucial for implementing sustainable solutions and establishing guidelines for future energy practices amidst the adverse effects of climate change on the continent's ecosystem. To this effect, the present study examines the effect of energy consumption on climate change in African countries from 2004 to 2019. Employing the Discroll and Kraay estimation technique and the Generalized Method of Moment on secondary data, the results indicate that Energy Use as kg of oil, Fossil Fuel Energy Consumption, and Energy Depletion positively and significantly affect Climate change. At the same time, Renewable Energy Consumption reveals a correcting effect on climate variations in Africa. The results are valid for other climate change measures and are robust to endogeneity control. Based on the results, applicable economic policies are proposed regarding the efficient and optimum use of various energy sources for Africa's clean and sustainable climatic conditions.

Effect of Long-Term Sodium Hypochlorite Cleaning on Silicon Carbide Ultrafiltration Membranes Prepared via Low-Pressure Chemical Vapor Deposition.

Sodium hypochlorite (NaClO) is widely used for the chemical cleaning of fouled ultrafiltration (UF) membranes. Various studies performed on polymeric membranes demonstrate that long-term (>100 h) exposure to NaClO deteriorates the physicochemical properties of the membranes, leading to reduced performance and service life. However, the effect of NaClO cleaning on ceramic membranes, particularly the number of cleaning cycles they can undergo to alleviate irreversible fouling, remains poorly understood. Silicon carbide (SiC) membranes have garnered widespread attention for water and wastewater treatment, but their chemical stability in NaClO has not been studied. Low-pressure chemical vapor deposition (LP-CVD) provides a simple and economical route to prepare/modify ceramic membranes. As such, LP-CVD facilitates the preparation of SiC membranes: (a) in a single step; and (b) at much lower temperatures (700-900 °C) in comparison with sol-gel methods (ca. 2000 °C). In this work, SiC ultrafiltration (UF) membranes were prepared via LP-CVD at two different deposition temperatures and pressures. Subsequently, their chemical stability in NaClO was investigated over 200 h of aging. Afterward, the properties and performance of as-prepared SiC UF membranes were evaluated before and after aging to determine the optimal deposition conditions. Our results indicate that the SiC UF membrane prepared via LP-CVD at 860 °C and 100 mTorr exhibited excellent resistance to NaClO aging, while the membrane prepared at 750 °C and 600 mTorr significantly deteriorated. These findings not only highlight a novel preparation route for SiC membranes in a single step via LP-CVD, but also provide new insights about the careful selection of LP-CVD conditions for SiC membranes to ensure their long-term performance and robustness under harsh chemical cleaning conditions.

Nondestructive evaluation of mechanical heart valve disc thickness degradation due to accelerated durability test using THz-TDS measurements

ABSTRACT Quality assurance and control during the mechanical heart valve components’ production process is paramount to mitigate most of the valve-related complications arising from valve replacement. Nondestructive evaluation of heart valve implants with complex profiles during production is challenging due to the biocompatibility requirements and clean room assembly conditions. This study first tested the UHMWPE disc of TTK Chitra mechanical heart valve models TC1 and TC2 using Terahertz imaging in reflection mode. The UHMWPE discs were raster scanned in X-Y directions to obtain a Terahertz-C scan to locate the macro defects due to wear out, and to distinguish between the true positive and true negative samples. The results were verified with digital microscope studies. Second, this study investigates a unique relationship between Terahertz imaging in reflection mode and heart valve disc degradation due to accelerated durability study. Third, the variation of disc surface roughness due to accelerated durability test was studied by Gaussian curve fitting analysis of fast Fourier transform of the Terahertz reflections. Finally, a comparison between the TC1 and TC2 heart valve model’s wear-out foot print was carried out using Terahertz C-scan. Our results imply that Terahertz time-domain spectroscopy has promising applications in NDE measurements of biocompatible implants.

Impact of try-in paste removal on the fatigue behavior of bonded lithium disilicate ceramics

This in vitro study assessed the effectiveness of three cleaning protocols (air-water spray, 37% phosphoric acid, or Ivoclean) on lithium disilicate restorations' fatigue behavior after try-in paste application, compared to a clean condition. Lithium disilicate discs (IPS e.max CAD, Ivoclar) with Ø-= 12 mm and 1 mm thickness were prepared from prefabricated CAD-CAM blocks, polished, subjected to CAD-CAM milling topography simulation and crystallization. After, etching with 5% hydrofluoric acid and the application of try-in paste (Variolink try-in paste shade white; load of 2.5 N for 5 min) was performed. Discs that received try-in paste were divided into three groups according to the removal protocol: SPRAY – air-water spray for 30 s; HPO – active application of 37% phosphoric acid for 60 s; IVOC – application of Ivoclean for 20 s. Control group (CTRL group) did not receive the try-in paste application. Half of the specimens (n= 15) were tested in the baseline condition (24 h up to 7 days), and the others underwent 25,000 thermal cycles (5 – 55 °C) + 210 days of distilled water storage (37 °C). Additional specimens (n= 3) underwent monotonic testing (1 mm/min). Fatigue testing involved a cyclic fatigue approach (20 Hz, initial load = 100 N – 5000 cycles, step size = 50 N – 10,000 cycles) until a visible crack appeared. Fractographic and topographic analyses were performed. Fatigue data were statistically analyzed with two-way ANOVA, Kaplan-Meier log-rank (Mantel-Cox), and independent t-test (α= 0.05). In the baseline condition, the IVOC group resulted in a superior fatigue behavior compared to the CTRL and SPRAY groups, but similar to the HPO group. The HPO and SPRAY presented a similar fatigue behavior to the CTRL group. It was noticed a decrease in fatigue behavior after aging, which resulted in all the cleaning protocols leading to similar fatigue behavior compared to the CTRL group. On the SPRAY group surface, try-in pastes remnants were noticed. In summary, despite a detrimental impact at baseline conditions, all tested cleaning protocols seem proper to remove the try-in paste from the ceramic's surface in the long-term evaluation.

Rosin as a Natural Alternative for the effective disinfection of ESKAPE Pathogens and Clostridioides difficile spores.

Hospital-acquired infections (HAIs) caused by antimicrobial-resistant ESKAPE pathogens are a significant concern for the healthcare industry, with an estimated cost of up to ${\$}$45 billion per year in the US alone. Clostridioides difficile is an additional opportunistic pathogen that also poses a serious threat to immunocompromised patients in hospitals. Infections caused by these pathogens lead to increased hospital stays and repeated readmission, resulting in a significant economic burden. Disinfectants and sporicidals are essential to reduce the risk of these pathogens in hospitals, but commercially available products can have a number of disadvantages including inefficacy, long contact times, short shelf lives, and operator health hazards. In this study we evaluated the effectiveness of Rosin (a natural substance secreted by coniferous trees as a defence mechanism against wounds in tree bark) and its commercial derivative Rosetax-21 as disinfectants and sporicidal against the six ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) and spore preparations from Clostridioides difficile. Both Rosin and Rosetax-21 were tested under simulated clean and dirty conditions (with BSA) against the ESKAPE pathogens, and C. difficile spore preparations. In clean conditions, Rosin (5% weight/volume: w/v) demonstrated significant efficacy against five of the ESKAPE pathogens, with A. baumannii and E. faecium being the most susceptible, and K. pneumoniae the most resistant, showing only a one-log reduction after a 5min treatment. However, in dirty conditions, all pathogens including K. pneumoniae exhibited at least a 3-log reduction to Rosin within 5min. Rosetax-21 (5%w/v) was found to be less effective than Rosin in clean conditions, a trend that was exacerbated in the presence of BSA. Additionally, both Rosin and Rosetax-21 at 2.5% (w/v) achieved complete eradication of C. difficile spores when combined with 0.5% glutaraldehyde, though their standalone sporicidal activity was limited. The findings from this study highlight the potential of Rosin and Rosetax-21 as both bactericidal and sporicidal disinfectants, with their efficacy varying based on the conditions and the pathogens tested. This presents an avenue for the development of novel healthcare disinfection strategies, especially against HAIs caused by antimicrobial-resistant ESKAPE pathogens and C. difficile.

Evaluation of a microscale quantitative suspension test to determine the bactericidal and yeasticidal activity of glutaral - one step to improve sustainability in disinfectant testing.

To evaluate a newly developed microscale quantitative suspension test compared to the existing standard suspension test using determination of the bactericidal and yeasticidal activity of glutaral as one step to improve the sustainability of disinfectant testing. The testing principles of the quantitative suspension test according to VAH method 9 (comparable to EN 13727) was used as a standard suspension test using 8.0 mL product test solution, 1.0 mL organic load and 1.0 mL test suspension. In addition, a micro-scale suspension test was performed in 96-well plates with 160 µL product test solution, 20 µL organic load and 20 µL test suspension. S. aureus ATCC 6538, P. aeruginosa ATCC 15442 and C. albicans ATCC 10231 were test organisms. Glutaral was tested at concentrations of 0.05%, 0.1%, 0.2% and 0.3% with exposure times of 1, 5 and 15 min. Polysorbate 80 (30 g/L), lecithin (9 g/L), L-histidine (1 g/L) and glycine (10 g/L) were used as validated neutralizers. After serial dilution of the disinfectant-neutralizer-mixture, plates were incubated for 48 h at 36°C (bacteria) or 72 hours at 30°C (C. albicans) and colony forming units (cfu) counted. The lg reduction was calculated as the difference between the results of the water control and the disinfectant at the end of the exposure time. All experiments were done in triplicate under clean conditions. Means of lg reduction were compared with the unpaired t-test, p<0.05 was considered to be significant. Sufficient bactericidal activity according the VAH test requirements of at least 5 lg was found with both methods in 16 data sets of 24 data sets in total, and insufficient bactericidal activity of less than 5 lg was found with both methods in 7 data sets. In one data set, the mean lg reduction was above 5 lg with the microscale method and <5 lg with the VAH method, with no significant difference between the data sets (p=0.3096; 0.2% glutaral, 1 min, P. aeruginosa). A sufficient yeasticidal activity of at least 4 lg was found with both methods in one data set, an insufficient yeasticidal activity of less than 4 lg was found with both methods in 8 data sets. With one exception, no significant differences were detected between the two methods below the efficacy threshold. The microscale quantitative suspension test proved to provide results similar to those of VAH method 9 when the bactericidal and yeasticidal activity of glutaralwas evaluated, with 32 out of 33 evaluations yielding consistent results in terms of efficacy. Its suitability should be confirmed with additional bacterial species, additional biocidal active substances and in other laboratories.

A Needle in the Haystack

For the past 20 years, the GEOTRACES program has produced transformative insights into the cycling of trace elements and isotopes (TEIs) in the ocean. Modeled after the 1970s GEOSECS (Geochemical Ocean Sections Study) program, the goals of this ambitious study were to conduct large-scale measurements of TEI concentrations and to determine the biogeochemical processes that controlled their distributions throughout the global ocean. Perhaps the biggest hurdle to overcome was how to accurately measure less than nanomolar concentrations of TEIs from the deck of a 3,000 gross tonnage steel ship. Contaminants were literally everywhere, requiring scientists and crew to become innovative in their attempts to maintain clean conditions for sample collection, storage, and measurement. GEOTRACES encouraged international partnerships while instilling a collaborative approach in the next generation of scientists. The practices GEOTRACES developed led to consistent high-quality measurements across diverse lab groups and provided an extensive and open database. GEOTRACES has truly been a labor of love among all the scientists and crews involved, and the program continues as a lofty example of the discoveries possible when conducting such wide-ranging collaborative research.

Condition assessment criteria evaluation of asymmetric aged and fully aged silicone rubber insulators based on leakage current harmonics

AbstractThe leakage current characteristic monitoring of transmission line insulators is considered a worthy technique for insulator state prediction. In this paper, the harmonic analysis of leakage current signals has been performed to analyze the composite insulator condition. Experimental studies of asymmetrically aged, fully aged, and virgin insulators have been conducted. The effects of different aging types, pollution, and humidity on leakage current components, such as harmonics and the phase differences with the applied voltage, have been investigated. The analysis of the results shows that the effect of asymmetric aging on leakage current components is non‐linear, and this non‐linearity increases with the degree of pollution. Also, the type of insulator aging can be determined by the ratio of the third‐ and fifth‐order leakage current harmonics. For instance, the classification of insulators into virgin, asymmetrically aged, and fully aged can be determined by examining the corresponding value ranges of 0–0.5, 0.5–0.9, and &gt; 0.9, respectively. Similarly, the phase difference values of &lt; 15% and those &gt; 15% indicate the clean and polluted operating conditions individually.