Ppm In Water Research Articles

Photocatalytic Decomposition of Amoxicillin Using Zinc Ferrite Nanoparticles

Catalysts enriched in Zinc ferrite (ZFO) were synthesized using coprecipitation and hydrothermal methods. Mixtures of crystalline nanoparticles (ZFO and α-Fe2O3, several allotropic varieties of FeO) were characterized by various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM, SEM), N2 sorption, UV-visible spectrophotometry (UV-Vis) and X-ray photoelectron spectroscopy (XPS). After detailed characterizations, the catalytic performance of the solids (1 g/L) in the degradation of amoxicillin (AMX) (10 mg/L) as an antibiotic pollutant in water was evaluated. In addition, we used air as the oxygen source and adjusted the pH to 5.0. Consequently, the catalysts obtained via the hydrothermal method HT-ZFO had a high activity (100% of AMX removal in less than 100 min when an LED (75 W) light was used) compared to a similar mixture of oxides with graphene HT-ZFO-GO (a longer time of 150 min) that was necessary for the complete degradation of AMX. Impregnation with an aqueous solution containing 80 mg of GO obtained using Hummer’s method, reduced into RGO by an ultrasound treatment, enhances the initial reaction rate but is associated with a prolonged time for complete AMX removal (10 ppm in water) that we attribute to its spontaneous corrosion.

Geochemical and Geospatial Distribution of Organic Contaminants in the Flood Plain of Ekpetiama, Niger Delta Region of Nigeria

This study investigated the geochemical and geospatial distribution of organic contaminants in the floodplain water and sediments of Ekpetiama in the Niger Delta Region of Nigeria. This study is necessary because there are limited data on the level of organic contamination in this section of the Niger Delta Region of Nigeria. The extinction of planktons in Ekpetiama became a source of concern to the residents. This concern is because this section of the coastal plain provides fisher folks with livelihood. So, there was a need to track the source of contamination in this part of the Niger Delta region. Previous studies have suggested a high level of Total Petroleum Hydrocarbon and Total Hydrocarbon Content as possible sources of reduced dissolved oxygen in similar deltaic terrain. A total of 10 water and 10 sediment samples were collected and analyzed in triplicate at an interval of 100 m in the flood plain. A particle size analyzer was used to perform particle size analyses of air-dried sediments. The American Public Health Association method (APHA) was used to do the chemical analysis of the water samples. Here, a liquid-liquid extraction procedure was performed on sediment samples using 30 mL of Dichloromethane (DCM) as the extracting agent. The results were subjected to statistical validation. The mean grain size ranged from 2.37-4.83, kurtosis (1.94-0.49), and skewness (-0.8-0.71). The contaminant indicators (pH, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen and Total Organic Carbon) point to the presence of organic contamination of the flood plain. The results indicated a total petroleum hydrocarbon range of 0.47-0.87 ppm in water and 0.69-0.96 ppm in sediments and a total hydrocarbon content range of 1.10-2.80 ppm in water and 2.56-3.90 ppm in sediment# samples. The results were above the permitted limits of the World Health Organisation. The source of ecological damage is the abnormal concentrations of organic contaminants in the flood plain. These results significantly caused ecosystem damage and human health effects in the food chain. This study provides information to the National Oil Spill Detection and Response Agency for a cleanup process.

Geochemical and Geospatial Distribution of Organic Contaminants in the Flood Plain of Ekpetiama, Niger Delta Region of Nigeria

This study investigated the geochemical and geospatial distribution of organic contaminants in the floodplain water and sediments of Ekpetiama in the Niger Delta Region of Nigeria. This study is necessary because there are limited data on the level of organic contamination in this section of the Niger Delta Region of Nigeria. The extinction of planktons in Ekpetiama became a source of concern to the residents. This concern is because this section of the coastal plain provides fisher folks with livelihood. So, there was a need to track the source of contamination in this part of the Niger Delta region. Previous studies have suggested a high level of Total Petroleum Hydrocarbon and Total Hydrocarbon Content as possible sources of reduced dissolved oxygen in similar deltaic terrain. A total of 10 water and 10 sediment samples were collected and analyzed in triplicate at an interval of 100 m in the flood plain. A particle size analyzer was used to perform particle size analyses of air-dried sediments. The American Public Health Association method (APHA) was used to do the chemical analysis of the water samples. Here, a liquid-liquid extraction procedure was performed on sediment samples using 30 mL of Dichloromethane (DCM) as the extracting agent. The results were subjected to statistical validation. The mean grain size ranged from 2.37-4.83, kurtosis (1.94-0.49), and skewness (-0.8-0.71). The contaminant indicators (pH, biochemical oxygen demand, chemical oxygen demand, dissolved oxygen and Total Organic Carbon) point to the presence of organic contamination of the flood plain. The results indicated a total petroleum hydrocarbon range of 0.47-0.87 ppm in water and 0.69-0.96 ppm in sediments and a total hydrocarbon content range of 1.10-2.80 ppm in water and 2.56-3.90 ppm in sediment# samples. The results were above the permitted limits of the World Health Organisation. The source of ecological damage is the abnormal concentrations of organic contaminants in the flood plain. These results significantly caused ecosystem damage and human health effects in the food chain. This study provides information to the National Oil Spill Detection and Response Agency for a cleanup process.

The Effect of Water Hardness and pH on the Efficacy of Peracetic Acid and Sodium Hypochlorite against SARS-CoV-2 on Food-Contact Surfaces.

Sodium hypochlorite (NaOCl) and peracetic acid (PAA) are commonly used disinfectants with a maximum recommended concentration of 200 ppm for food-contact surfaces. The objectives of this study were to assess the effect of pH and water hardness on NaOCl and PAA efficacy against SARS-CoV-2 on stainless steel (SS). The two disinfectants were prepared at 200 ppm in water of hardness 150 or 300 ppm with the final pH adjusted to 5, 6, 7, or 8. Disinfectants were applied to virus-contaminated SS for one minute at room temperature following the ASTM E2197 standard assay. SARS-CoV-2 infectivity was quantified using TCID50 assay on Vero-E6 cells. In general, increasingly hard water decreased the efficacy of NaOCl while increasing the efficacy of PAA. Hard water at 300 ppm significantly increased virus log reduction with PAA at pH 8 by ~1.5 log. The maximum virus log reductions were observed at pH 5 for both NaOCl (~1.2 log) and PAA (~2 log) at 150 and 300 ppm hard water, respectively. In conclusion, PAA performed significantly better than NaOCl with harder water. However, both disinfectants at 200 ppm and one minute were not effective (≤3 log) against SARS-CoV-2 on contaminated food-contact surfaces, which may facilitate the role of these surfaces in virus transmission.

In vitro inactivation of SARS-CoV-2 by ozonated water via novel hand hygiene device.

The COVID-19 pandemic has heightened awareness of the need for novel surface disinfectants and hand-hygiene modalities. Ozone gas is an effective surface disinfectant, but toxicity limits its use in human applications. Ozonated water is a safer means to use ozone for disinfection, especially for human antisepsis. However, there are little data available regarding the effectiveness of ozonated water in eliminating severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). This study utilizes a novel hand hygiene device that produces a stable ozone concentration of 0.5 +/-0.1ppm in water and applies it using a proprietary spray that controls droplet size, velocity, and direction. The Device was used to apply ozonated water to a known quantity of SARS-CoV-2 Delta Variant viral particles on a non-porous surface (glass) for seven seconds. Post-exposure growth was compared to the unexposed matched control utilizing the Spearman-Karber method. Compared to control, ozonated water decreased SARS-CoV-2 viral growth by a mean log10 reduction of 4.33, or>99.99%reduction. These results suggest that the ozonated water, when applied by a spray hand hygiene device, is highly effective at surface disinfection of SARS-CoV-2.

Radiologically Identified Morphologic Changes of Maxillary and Mandibular Bones among Diagnosed Cases of Skeletal Fluorosis in Ethiopia

In 1937, the chronic toxic effect of fluoride on skeletal fluorosis was demonstrated for the first time in history in the Indian state of Madras. Exposure to fluoride concentrations greater than eight ppm in water is reported to cause skeletal fluorosis. Skeletal fluorosis is a chronic metabolic bone disease resulting from prolonged ingestion of large amounts of fluoride. Bone knee syndrome, osteosclerosis, pathological fractures, calcification of ligaments, joint stiffness, immobility, muscle atrophy, and severe forms of neurological deficits are some of the consequences of skeletal fluorosis. Skeletal fluorosis, as such, is a highly morbid disease. Yet, the condition is overlooked, and, most importantly, little is known about its effects on the facial skeleton. This unique, investigative, crosssectional study was initiated to evaluate the morphologic changes in the jawbone caused by skeletal fluorosis in adults diagnosed with skeletal fluorosis. A two-dimensional radiograph was used to evaluate the possible skeletal fluorosis-related morphological changes in the maxillary and mandibular bones. A total of 9 patients diagnosed with skeletal fluorosis underwent panoramic radiography of the maxillary bones and mandibular. Several skeletal fluorosis-related morphological changes were detected in the jaw bones of 6 study participants, including exostosis, osteosclerosis, thickened cortical bone, narrowed bone marrow, and periosteal plaques. According to studies, these morphological changes pose a serious threat to the healing process of the bone. Therefore, surgeons practicing in the Oro-craniofacial region must be alert to potential perioperative and postoperative complications when treating patients diagnosed with skeletal fluorosis.

Mxenes-Au NP Hybrid Plasmonic 2D Microplates in Microfluidics for SERS Detection.

Combined with microfluidics, surface-enhanced Raman spectroscopy (SERS) exhibits huge application prospective in sensitive online detection. In current studies, the design and optimization of plasmonic enhanced structures in microfluidics for SERS detection could be an interesting challenge. In this work, hybrid plasmonic 2D microplates composed of Mxenes (Ti3C2Tx) microplates and in-situ synthesized Au nanoparticles (Au NPs) are fabricated in a microchannel for enhanced structures in SERS microfluidics. Benefiting from the 2D Mxenes microplates with complex distributions, the enhanced areas generated by Au NPs are quite enlarged in a microchannel, which exhibits high sensitivity in SERS detection at 10−10 M for Nile blue (NB) molecules in microfluidics. The mechanism of electromagnetic enhancement (EM) and chemical enhancement (CM) is analyzed. The experimental data indicate the ultrasonic times of Mxenes and the concentration of Au3+ play important roles in the sensitivity of SERS detection, which is confirmed by the simulated electric field distributions. Furthermore, a typical pesticide (thiram) at 100 in water is detected on these SERS microfluidics with hybrid plasmonic enhanced structures, which demonstrates that our work not only strengthens the knowledge of plasmonics but also enlarges the application of SERS.

Regeneration Process of Ammonia-Absorbed Zirconium Phosphate to Zirconium Phosphate

Zirconium phosphate [Zr(HPO4)2·H2O] absorbs 2 mol(NH3)/mol[Zr(HPO4)2·H2O] with a low equilibrium plateau ammonia concentration of around 1 ppm in water. In this study, in order to investigate the regeneration process of ammonia-absorbed zirconium phosphate [Zr(NH4PO4)2·H2O], Zr(NH4PO4)2·H2O was heat-treated above 353 K under an inert gas. Then, the structures of the heat-treated samples were evaluated using powder X-ray diffraction and thermogravimetry–mass spectrometry measurements. Zr(NH4PO4)2·H2O started to desorb ammonia and the crystal water at 353 K. Then, Zr(NH4PO4)2·H2O was changed to the anhydrous monoammoniate [Zr(NH4PO4)(HPO4)] at 473 K and formed anhydrous zirconium phosphate [Zr(HPO4)2] at 673 K. The anhydrous zirconium phosphate and the anhydrous monoammoniate reabsorbed ammonia in ammonia water. Those initial absorption rates were small compared with Zr(HPO4)2·H2O. The slow kinetics of the anhydrous zirconium phosphate corresponded to the small interlayer distances. The ammonia concentration composition isotherms indicated that the anhydrous zirconium phosphate and anhydrous monoammoniate have a low ammonia equilibrium plateau concentration of around 1 ppm in ammonia water. Zr(NH4PO4)2·H2O is formed from Zr(NH4PO4)(HPO4) by the reabsorption of ammonia and water after 1–10 cycles. We found that zirconium phosphate is an ammonia remover which can be used repeatedly at 473 K.

Uptake and depuration of water-soluble fractions (WSF) of crude oil by the bivalve Corbicula fluminea (Müller) from Shatt Al-Arab river

This study includes laboratory uptake and depuration experiments. The bivalve C. fluminea is exposed to 5ml of WSF of Nahran–Umar crude oil for each liter of river water for 48 hours in the static toxicity test system. The exposure water and animals are periodically taken for analysis of total hydrocarbons concentrations by spectroflurometer. After the exposure period is over, the bivalve transferred to clean river water for depuration period of 48 hours. The experiments show that there are no mortalities due to WSF of Nahran–Umar crude oil. The bivalve is usually active during the 12–16 hours of the experiments. Hydrocarbons concentrations in the exposure water decreased are slowly in a linear fashion so that no measurable concentrations remained after 32 hours. Hydrocarbons accumulated by the bivalve are slowly during the first few hours of exposure. After 2 hours of exposure, the concentration of hydrocarbons is approximately 0.38 ppm in water, while in tissues it is 4.8 ppm. After 20 hours, hydrocarbons are present in water at a concentration of 0.09ppm, while the bivalve tissues contained 17.7 ppm hydrocarbons. After 25 hours of exposure, the hydrocarbons concentration decreased in the bivalve tissues. At the end of the exposure period, the bivalve contains approximately 7.4 ppm. After 48 hours in clean river water, tissues burden decreased to 0.22 ppm of hydrocarbons. The bivalve remained contaminated with small concentrations of hydrocarbons for 20 days. The complete depuration occurred at 26 days.

Thy-AuNP-AgNP Hybrid Systems for Colorimetric Determination of Copper (II) Ions Using UV-Vis Spectroscopy and Smartphone-Based Detection.

A colorimetric probe based on a hybrid sensing system of gold nanoparticles (AuNPs), silver nanoparticles (AgNPs), and thymine (Thy) was developed for easy and rapid detection of copper (II) ions (Cu2+) in solution. The underlying principle of this probe was the Cu2+-triggered aggregation of the nanoparticle components. Color change of the sensing solution (from red to purple) was clearly observed with naked eyes. The experimental parameters, including pH and concentration of tris buffer, thymine concentration and AgNP dilution ratios, were investigated and optimized. Once optimized, the limits of detection were found to be 1, 0.09 and 0.03 ppm for naked eyes, smartphone application and UV-vis spectrophotometer, respectively. Furthermore, determination of Cu2+ was accomplished within 15 min under ambient conditions. For quantitative analysis, the linearity of detection was observed through ranges of 0.09–0.5 and 0.03–0.5 ppm using smartphone application and UV-vis spectrophotometer, respectively, conforming to the World Health Organization guideline for detection of copper at concentrations < 2 ppm in water. This developed hybrid colorimetric probe exhibited preferential selectivity toward Cu2+, even when assessed in the presence of other metal ions (Al3+, Ca2+, Pb2+, Mn2+, Mg2+, Zn2+, Fe3+, Ni2+, Co2+, Hg2+ and Cd2+). The developed procedure was also successfully applied to quantification of Cu2+ in real water samples. The recovery and relative standard deviation (RSD) values from real water sample analysis were in the ranges of 70.14–103.59 and 3.21–17.63%, respectively. Our findings demonstrated a successful development and implementation of the Thy-AuNP-AgNP hybrid sensing system for rapid, simple and portable Cu2+ detection in water samples using a spectrophotometer or a smartphone-based device.

Mantle rain toward the Earth's surface: A model for the internal cycle of water

The internal or deep water cycle controls the volume of the oceans at the surface of the Earth. The advent of subduction 2–3 billion years ago initiated the transport of water back to the Earth's interior. With one ocean mass injected into the deep mantle over the last 2–3 billion years, some mantle regions must have become saturated and thus turned into a deep source of water. The mantle transition zone (MTZ) between 410 and 660 km depths is unlikely to be a source of hydrous melt, because its minerals can integrate several thousand ppm of water. On the contrary, the low-velocity layer (LVL) lying above the 410 km-discontinuity is one such source. As proposed by the “Transition-Zone-Water-Filter Model”, the LVL is ubiquitously formed by the global uplift of the hydrous MTZ as a counter flow of subduction of slabs into deeper regions. The seismic signature of the LVL is compatible with the presence of 0.5–1% melt. This melt is produced by dehydration melting during upwelling of the mantle transition zone (MTZ) containing 2200(300) ppm wt H2O, which corresponds to 0.6 ocean mass stored today in the MTZ. Hydrous silicate melt can be gravitationally stable just above the 410 km discontinuity. We propose, here, that at the upper limit of the LVL it becomes buoyant, especially where the mantle is particularly hot and/or hydrous. Once it becomes buoyant, the melt can percolate rapidly upwards through the mantle. As a consequence, the olivine-bearing mantle (OBM) could be almost saturated in water, due to the presence of upwelling hydrous melt. On its path, the melt may be responsible for the seismic low-velocity zones at mantle depths of between 80 and 150 km. It could also be a source for refertilisation of the lithospheric mantle. Based on this model, there should be ~1.0 oceanic mass (OM) stored in the upper mantle today. Secular cooling of the mantle implies an increased capacity of the OBM minerals to store water. The related decrease of oceans' mass at the Earth's surface is estimated to ~20% per one billion years.

Effect of quercetin and curcumin in rats sub-acutely exposed to cadmium chloride: haemato-biochemical changes, oxidative stress parameters and histopathological changes in intestine, liver and kidney of rats

Quercetin is a flavonoid mostly found in fruits and vegetables. Curcumin is the main natural polyphenol found in the rhizome of Curcuma longa and in others Curcuma spp.. Individually, quercetin and curcumin had shown to have various pharmacological properties. The increasing level of cadmium in the environment is alarming as cadmium affects the antioxidant defense system with ability to persist in the body for long time. The bioaccumulation of cadmium is well-known, which is dangerous for the health of human and animals after continuous exposure to it. The present experiment was carried out to evaluate the ameliorating effect of quercetin (50 mg/kg daily orally for 28 days) and curcumin (100 mg/kg daily orally for 28 days) alone and in combination of both against cadmium-induced (100 ppm in water for 28 days) alterations in biochemical markers and histological changes in intestine, liver and kidney of rats. Body weight gain in rats of toxicity group during the 4th week of study period was significantly affected by the cadmium. Cadmium exposure significantly increased the levels of AST, ALT, ALP, bilirubin and glucose in serum along with higher level of MDA in intestine, liver and kidney of rats. The administration of quercetin and curcumin in combination as compared to individual treatment along with cadmium exposure had shown significantly lower levels of above parameters. Various histological changes were noticed in intestine, liver and kidney of rats following exposure to cadmium which were improved in rats treated with individual or combined treatment of quercetin and curcumin. Quercetin alone had shown the ameliorating effect against cadmium-induced alteration in kidney of rats. While, combination of quercetin and curcumin has been found to protect the intestine and liver from cadmium-induced damage following sub-acute exposure in rats. However, further study is needed to explore the mechanism of protective effect of the quercetin and curcumin against cadmiuminduced changes in intestine, liver and kidney.

Bioaccumulation of Zn and 137Cs in Glauconomya virens (Linnaeus, 176) Upon Exposure to Sigle and Mixture of Zn or 137Cs and Salinity

This study aims to determine the effect of concentrations and salinity of seawater on the bioaccumulation of zinc and cesium in the Glauconomya virens. Salinity conditions and contaminant concentrations in the marine environment can change due to weather and other inputs. A biokinetic experiment was carried out using a single compartment approach that used radiotracer 65Zn and 137Cs. The experiments conducted were biota collection, acclimatization, bioaccumulation, and elimination. Acclimatization aims for the adaptation of biota in an experimental environment. Bioaccumulation was by placing the biota in an aquarium containing seawater media spiked by 65Zn, Zn, and 137Cs radiotracer contaminants. The elimination process was the release of contaminants from the body of the biota by placing them in clean and flowing seawater. The experimental results show that the uptake and elimination of Zn and Cs were influenced by these two parameters (water concentration and salinity). The highest value of Concentration Factor (CF) for Zn was 11.14 ml.g-1 under influences its concentration of 0.7 ppm in water. In the depuration process, Zn maintained by G virens were 39.44; 31.17; 23.62; and 23.92% after these organisms accumulate this element from seawater containing 0.1; 0.3, 0.5, and 0.7 ppm, respectively. The highest of 137Cs under influences its concentration of 3 Bg.ml-1 reached 2.65 mL.g-1. The effect of salinity is directly proportional to the factor value of Zn and 137Cs concentration.

PHOTOCATALYTIC ACTICVITY OF TiO2-Eu2O3 PHOTOCATALYST FOR PHENOL DECOMPOSITON IN AQUEOUS SOLUTIONS

TiO2-Eu2O3 catalyst nanocomposite materials were synthesized from tetra-n-butyl orthotitanate, rare earth oxide Eu2O3 by a sol gel method, with a polyvinyl alcohol gel agent. Characteristic structures and properties were determined by infrared (IR) spectrometry, X-ray diffraction, a scanning electron microscope (SEM), and a transmission electron microscope (TEM). The composition and ingredients of TiO2-Eu2O3 and the Ti/Eu ratio were shown in the XRD diagram and Energy Dispersive X-ray (EDX) fluorescence spectroscopy. The results of testing the photocatalytic properties of the material to treat phenol with a concentration of 10 ppm in water for processing efficiency reached over 90 %. The obtained materials, namely photochemical catalyst materials, can be applied in the field of enviromental treatment, especially photochemical catalytic decomposition catalysts in visible light to treat textile wastewater and organic pollutants in water, as well as bactericidal effects.

Glymphatic System Visualized by Chemical-Exchange-Saturation-Transfer Magnetic Resonance Imaging

Dysfunction of the glymphatic system may play a significant role in the development of neurodegenerative diseases. However, in vivo imaging of the glymphatic system is challenging. In this study, we describe an unconventional MRI method for imaging the glymphatic system based on chemical exchange saturation transfer, which we tested in an in vivo porcine model of impaired glymphatic function. The blood, lymph, and cerebrospinal fluid (CSF) from one pig were used for testing the MRI effect in vitro at 7 Tesla (T). Unilateral deep cervical lymph node ligation models were then performed in 20 adult male Sprague-Dawley rats. The brains were scanned in vivo dynamically after surgery using the new MRI method. Behavioral tests were performed after each scanning session and the results were tested for correlations with the MRI signal intensity. Finally, the pathological assessment was conducted in the same brain slices. The special MRI effect in the lymph was evident at about 1.0 ppm in water and was distinguishable from those of blood and CSF. In the model group, the intensity of this MRI signal was significantly higher in the ipsilateral than in the contralateral hippocampus. The correlation between the signal abnormality and the behavioral score was significant (Pearson's, R2 = 0.9154, p < 0.005). We conclude that the novel MRI method can visualize the glymphatic system in vivo.

Temperature-Dependent Emission and Turn-Off Fluorescence Sensing of Hazardous "Quat" Herbicides in Water by a Zn-MOF Based on a Semi-Rigid Dibenzochrysene Tetraacetic Acid Linker.

A zinc metal-organic framework, i.e., Zn-MOF (Zn-DBC), with ca. 27% solvent-accessible void volume was synthesized from a rationally designed tetraacid based on sterically insulated dibenzo[g,p]chrysene core; the latter inherently features concave shapes. Due to rigidification of the fluorophore in the MOF, Zn-DBC exhibits a respectable fluorescence quantum yield of ca. 30% in the solid state. The fluorescent and water-stable Zn-DBC MOF was found to display intriguing temperature-dependent emission behavior with an activation barrier of 1.06 kcal/mol for radiationless deactivation from the singlet-excited state. It is shown that the Zn-MOF can be employed as an efficient sensory material for detection of hazardous "quat" dicationic herbicides in water by diffusion-limited "turn-off" fluorescence. Due to confinement of the cationic guest analytes within the pores of the MOF, the fluorescence quenching via excited-state charge transfer mechanism is shown to depend on the molecular size of the analyte in addition to the redox potentials. Remarkably, Zn-DBC permits sensing of DQ, a well-known toxic "quat" herbicide, with a detection limit as low as 2.8 ppm in water. The unique structural attributes of the Zn-MOF for highly efficient fluorescence sensing of toxic herbicides in water are thus exemplified for the first time.

Water content in solid polymer electrolytes: the lost knowledge.

We reproducibly quantify the water content in different SPE systems through various processing/drying conditions and tie the residual amounts of water to heightened ionic conductivities. Moreover, we emphasise on the need to control the sample preparation and isolation as hydration occurs instantly when the dried sample encounters air.

Bi-Modal Failure Mechanism of Rolling Contact Bearings

The theory of failure of rolling contact bearings is based on fluctuating high level loading and material fatigue. This theory is unimodal, considering only the solid components of the bearing, and ignoring the liquid phase, which is the lubricant. Bearing life is rather dispersed, reaching a ratio of 20 between the extreme values. Since this theory was established, several exceptional phenomena were detected that could not be explained by it, such as: 1) Pitting damage beyond the contact path; 2) Detrimental effect of a minute quantity of water in the lubricant on bearing life. 25 ppm of water in the lubricant brought about shorter bearing life by over than 30%. The bimodal failure theory considers both solid and liquid bearing components. The damaging process of the lubricant evolves from its cavitation. During this process vapor filled cavities are formed in low pressure zones. When these cavities reach high pressure zones they implode exothermally. These implosions cause local high pressure pulses reaching 30,000 at accompanied by a temperature rise of about 2000 degrees K [1]. This paper includes cavitation erosion test results on stainless steel samples by vibratory and water tunnel test rigs. Various methods of lubricant dehydration are presented and evaluated. The main conclusion from this analysis is the use of water-free lubricants, for long life of RC bearings and more uniform service life thereof.

Removal of Fe (II) in groundwater using rice husk-sourced biosorbent in continuous column adsorption

Ferrous is one of the groundwater contaminants that negatively impacts health and the environment. The allowed ferrous content is < 1 ppm in water for daily use. Removal of Fe in groundwater by adsorption using low-cost bio-sorbent from rice husk has been conducted. The process was carried out in continuous mode using two types of rice husk-sourced adsorbents, one was only carbonated at 400 C and another was followed by a physical activation at 650 C. To study the effects of physical activation on the surface characteristics, both types of biosorbents were characterized by Scanning Electron Microscope and Fourier-transform infrared spectroscopy. The concentration of artificial sample before and after adsorption was evaluated using the Atomic Absorption Spectroscopy. From the results, the adsorption using physically activated sorbent had greater removal efficiency of 74.02% compared to that of without activation treatment, which was only 65.70%. In addition, the concentration of ferrous was successfully reduced to 1,029 and 0.779 ppm from the initial concentration of 3 ppm for the process using the adsorbent without and with activation, respectively. It can be concluded that the physically activated rice husk has the potential to be used for adsorption of Ferrous in continuous column.

Inkjet printed electrochemical aptasensor for detection of Hg2+ in organic solvents

Real-time detection of heavy metal traces from industrial waste is key to control any potential environmental pollution by early critical point intervention. This opens a market niche for real-time, portable, and cost-efficient devices for environmental and biosafety monitoring. Despite the rapid growth of heavy metal monitoring as a research field, and the promising performance of an increasing number of novel platforms reported, the chances to transfer the lab-scale platforms developed to successful commercialization stages are dramatically low.This work proposes for the first time the use of ink-jet printed gold electrodes as a reliable, stable and fully-scalable approach for aptamer-based detection of mercury (Hg2+) traces in water and organic solvents. A controlled fabrication process was demonstrated by keeping the 90% of the charge transfer (RCT) values obtained from the as-fabricated electrodes (n = 11) within ± 1 SD (RSD = 2.92%) from the mean value and following a mesokurtic normal-like distribution (p = 0.905). The as-fabricated platform achieved a LOD of 0.01 ppm in water and enhanced sensitivity of 2-fold when tested in organic solvents, with a LOD of 0.005 ppm which is far below the minimal sensitive required for practical implementation, according to the EPA stipulations. Finally, the aptamer-based gold ink-jet printed platform provided with enough evidence to state that the signal collected from Hg2+ was significantly different (p < 0.001) from the signal provided by interferent ions tested (arsenic, lead and cadmium) at the same concentration (50 ppm), evidencing a high specificity. From the best of our knowledge, this work reports for the first time a gold inkjet-printed impedimetric platform for aptamer-based detection of Hg2+ in organic solvents, showing promising viability for future prototyping and scaling-up.