Separate Trace Research Articles

STRENGTH FEATURES OF HARDENED STEEL TREATMENT BY TOOLS EQUIPPED WITH PcBN OF BH, BL GROUP

A set of studies has been carried out to investigate the power features of machining hardened steel with a tool equipped with PcBN of the VN group, obtained from the initial cBN powders coated with Ti and uncoated compounds, as well as PcBN of the BL group. The determined features of the machining process have shown that the wear of the cutting tool has a significant impact on the value of the cutting force components – when cutting at a speed of 350 m/min, the machining process with a tool of PcBN group BH obtained from coated powders, compared to machining with a tool of PcBN group BH obtained from uncoated powders, is characterized by a 15–20% lower value of the cutting force components. During high-speed machining under dynamic shock loads, a tool equipped with BH PcBN obtained from coated cBN powders, unlike cutters made of BL PcBN, retains its performance at a feed rate of 0, 38 mm/rev - usually, working under such conditions leads to brittle fracture of the tool equipped with PcBN of group BL due to chipping of individual fragments of the cutting edge from the back surface, and on the tool equipped with PcBN (5% Ti), there are separate traces of microchipping. The obtained research results indicate the possibility of using tools equipped with PcBN of group BH, sintered from coated cBN powders, under high-speed cutting conditions, which is typical for tools made of PcBN of group BL, but in the presence of dynamic loading.

Preparation of amyloid N-terminal nonapeptide imprinted monolithic column and evaluation of adsorption properties

A novel β-amyloid protein capillary microextraction column was designed and prepared using epitope molecular imprinting technology for specific recognition of trace β-amyloid proteins in complex biological matrices. Using N-terminal nonapeptide of β-amyloid protein as template molecule, choline chloride-MAA and N-hydroxymethyl acrylamide as functional monomers, ethylene glycol dimethacrylate as crosslinker, the imprinted capillary monolithic column was prepared by thermal polymerization in the acetonitrile-water system. The optimal preparation parameters were obtained with the ratio of template: functional monomer: crosslinker at 1:6:16 (mmol/mmol/mmol). The physical property evaluation through Scanning electron microscopy, Fourier transform infrared spectroscopy analysis, zeta potential analysis, particle size analysis, and Brunauer-emmett-teller showed that a porous imprinted monolithic column with a high specific surface area was successfully prepared. The static adsorption experiment showed that the theoretical maximum adsorption capacity was 0.060 μg/column and the optimal imprinting factor was 2.27. Under the optimal extraction conditions, the imprinted column exhibited good template selectivity and excellent robustness. Finally, the extraction efficiency of the capillary imprinted column in actual plasma was evaluated using ELISA method. For Aβ 40 and Aβ 42, the detection limits were 1.00 pg/mL and 0.67 pg/mL, the quantification limits were 3.00 pg/mL and 2.00 pg/mL, the detection ranges were 7.5–120.0 pg/mL and 5.0–80.0 pg/mL, respectively. After extraction of plasma samples, the measured concentrations of Aβ 40 and Aβ 42 by imprinted column were 157.31 pg/mL and 48.22 pg/mL, respectively, which were significantly higher than the measured concentrations by non-imprinted column of 89.60 pg/mL and 41.02 pg/mL. In summary, the epitope imprinted capillary monolithic column prepared in this study can effectively enrich and separate trace amounts of amyloid proteins in complex samples, and is expected to provide a new sample pretreatment method for clinical detection of amyloid proteins.

Preliminary Investigation of a Potential Optical Biosensor Using the Diamond™ Nucleic Acid Dye Applied to DNA and Friction Ridge Analysis from Fingerprint Traces.

Developments in science and technology lead to an increasing use of scientific evidence in litigation. Interdisciplinary research can improve current procedures and introduce new ones for the disclosure and examination of evidence. The dactyloscopic trace is used for personal identification by matching minutiae (the minimum required may vary by country) or for extracting DNA material from the trace under investigation. The research presented in this article aims to propose the merging of two currently used personal identification methods, DNA analysis and dactyloscopic trace analysis, which are currently treated as separate forensic traces found at a crime scene. Namely, the forensic trace to be analyzed is the dactyloscopic trace containing DNA, and both sources of information needed for identification are examined as one. Promega's Diamond™ Nucleic Acid Dye, presented as a safe alternative to ethidium bromide, works by binding to single- and double-stranded DNA and is used to visualize the separation of material in a gel and to detect DNA in forensic samples. Spectroscopic studies as absorption and emission spectra and fluorescence microscopy observations presented in our research confirm that Diamond™ Nucleic Acid Dye can also be used to visualize fingerprints on non-absorbent surfaces and that combining the two methods into one can significantly increase the evidential value and contribute to the design of an innovative fast-acting optical biosensor.

Comparing Neural Correlates of Memory Encoding and Maintenance for Foveal and Peripheral Stimuli.

Visual working memory is believed to rely on top-down attentional mechanisms that sustain active sensory representations in early visual cortex, a mechanism referred to as sensory recruitment. However, both bottom-up sensory input and top-down attentional modulations thereof appear to prioritize the fovea over the periphery, such that initially peripheral percepts may even be assimilated by foveal processes. This raises the question whether and how visual working memory differs for central and peripheral input. To address this, we conducted a delayed orientation recall task in which an orientation was presented either at the center of the screen or at 15° eccentricity to the left or right. Response accuracy, EEG activity, and gaze position were recorded from 30 participants. Accuracy was slightly but significantly higher for foveal versus peripheral memories. Decoding of EEG recordings revealed a clear dissociation between early sensory and later maintenance signals. Although sensory signals were clearly decodable for foveal stimuli, they were not for peripheral input. In contrast, maintenance signals were equally decodable for both foveal and peripheral memories, suggesting comparable top-down components regardless of eccentricity. Moreover, although memory representations were initially spatially specific and reflected in voltage fluctuations, later during the maintenance period, they generalized across locations, as emerged in alpha oscillations, thus revealing a dynamic transformation within memory from separate sensory traces to what we propose are common output-related codes. Furthermore, the combined absence of reliable decoding of sensory signals and robust presence of maintenance decoding indicates that storage activity patterns as measured by EEG reflect signals beyond primary visual cortex. We discuss the implications for the sensory recruitment hypothesis.

Separation trace amounts of copper ion by solid-phase extraction with carbon-based sorbent prior to flame atomic absorption spectrometry

ABSTRACT In this research, a carbon adsorbent modified with curcumin ligand was utilised in the solid-phase extraction procedure. This method was coupled with flame atomic absorption spectrometry to pre-concentrate and separate trace amounts of copper ions in aqueous solutions. Different experimental parameters, including pH, eluent type and concentration, adsorbent dose, extraction time and sample volume, were studied and optimised. The obtained optimum conditions for the proposed method were: pH of solution, 4.8; extraction time, 9 min; adsorbent dose, 0.01 g; type and concentration of eluent, 1:1 mixture of HCl and HNO3 0.5 mol L−1. Under optimal conditions, the pre-concentration factor of 400.0 and linear range values of the method were 0.031–1.875 µg/L and 12.5–750 µg/L for copper ions in the initial and final solutions, respectively. The relative standard deviation (RSD) for seven replicate detections of 0.05 µg L−1 of copper ion in initial solution was calculated as 2.2%. Furthermore, the detection limit of 0.008 µg L−1 was determined for the suggested method. In order to investigate the selectivity of modified carbon adsorbent, the influence of some interfering ions on the extraction and recovery of Cu (II) was studied. Finally, the present method was employed for the determination of copper ions in real water samples and standard alloys.

MWCNT@TiSiO4 nanocomposite for dispersive solid phase extraction of traces cadmium in food and environmental samples

Cadmium contamination presents substantial hazards to both human health and the environment due to its persistent presence in ecosystems and toxic characteristics. It accumulates in soil and water, causing chronic renal and respiratory issues, and carcinogenicity. Effective detection for monitoring the environmental and public health effects of Cd is required. This study addresses a new separation and enrichment method with a novel MWCNT@TiSiO4 nanocomposite synthesized via sol-gel and calcination synthesis techniques. A comprehensive characterization of the nanocomposite was conducted utilizing X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, and Field Emission-Scanning Electron Microscopy (FE-SEM) techniques. The nano-sorbent was utilized in conjunction with dispersive solid phase extraction (DSPE) to separate and preconcentrate trace amounts of Cd(II) prior to its determination by using flame atomic absorption spectrometry (FAAS). The optimization of analytical parameters, including pH, sample and eluent volumes, sorbent quantities, and eluent composition, was studied. The effect of matrix components was investigated. The method showed a low limit of detection (LOD), limit of quantification (LOQ), and relative standard deviation (%RSD) of 0.053 ng mL−1, 0.176 ng mL−1, and 4.6%, respectively. The method was validated by analyzing certified reference materials. The developed methodology was applied to determine Cd(II) levels in water, tobacco, and food samples. The recovery values were quantitative (90–101%). The maximum and minimum concentrations of Cd in food samples were in shrimp (47.87 ng g−1) and lentil (11.25 ng g−1), respectively.

A Frequency Detection Circuit for Constant ON-Time LED Driver Chip

To meet the high-reliability requirements of switch mode power supply LED driver chips with constant on-time architecture, a detection mechanism circuit that can detect the switching frequency of the architecture is proposed. The detection circuit completes the conversion from switching frequency to output voltage through separate voltage tracing technology. The detection circuit uses the method of frequency error calculation to eliminate the interference of frequency jump on detection. The design is based on a 180 nm process simulation. The simulation results show that the detection mechanism has good linearity for frequency measurement and can eliminate the interference of frequency jump.

Solvent Extraction, Sequential Separation and Trace Determination of La (III), Ce (III), Nd (III) and Gd (III) with 2, 14-bis[m-nitrophenyl]-Calix[4]Resorcinarene-8, 20-bis[N- phenylbenzo]-dihydroxamic Acid

ABSTRACT A novel reagent 2,14-bis[m-nitrophenyl]-calix[4]resorcinarene-8,20-bis[N-phenylbenzo]-dihydroxamic acid (NPC4RADHA) is reported for the liquid-liquid extraction, separation, and simultaneous trace determination of La(III), Ce(III), Nd(III), and Gd(III). The method involves optimizing various parameters such as the concentration of NPC4RADHA, pH, solvent, and extraction time to achieve maximum purity (99.98%) extraction of these rare earths. The stability constant, molar absorptivity, and Beer’s law have been studied. The extracted samples were directly analyzed by ICP-AES, which improves sensitivity with determination limits of 0.020 ng/mL, 0.028 ng/mL, 0.018 ng/mL and 0.025 ng/mL for La, Ce, Nd, and Gd, respectively. The method has been applied to the determination of these elements in monazite sand and standard geological samples. The separation and determination mixture of a Ce(III) and Ce(IV) has been reported.

PO-01-014 IMPACT OF GENDER ON P- AND R-WAVE AMPLITUDE IN A SURFACE EKG SIMULATION STUDY FOR INSERTABLE CARDIAC MONITOR

Cosmetic concerns or anatomic differences between males and females may influence implantation location of Insertable Cardiac Monitor (ICM). To assess device, implant and patient factors impacting electrogram sensing by proxy of precordial single-lead surface EKG recordings. 150 participants each had 12 separate tracings of single-lead surface EKG acquired using Northeast Holter (DR200/HE) placed at the parasternal 4th intercostal space to mimic ICM recordings. 3M electrodes were positioned at different vector length (75mm & 45mm) for each of three vector angles (vertical, oblique, horizontal) repeated in two postures (upright & supine). Height and weight were assessed for body surface area (BSA) calculation and impedance-based body fat percentage (BF%) was measured. All EKG strips were uploaded into DigitizeIt software for offline analysis by blinded technicians. Kruskal-Wallis test with Dunn’s multiple pairwise comparisons was performed to assess gender differences in EGM amplitudes. A total of 1,800 tracings from 150 participants [55.5% male, median age 59years (IQR 35 – 73)] were assessed. Compared to male participants, females had lower weight [73 (60 - 87) vs. 84kg (75 – 98), p<.001] but higher BF% [24.4 ± 8.8 vs. 35.2 ± 9.6%, p<.001]. There was no difference between gender for pairwise comparisons of median P-wave amplitude in each vector angle using different vector lengths (Panel A). Male participants had larger R-wave in vertical orientation for both vector lengths, but no difference for R-wave amplitude was seen for other angles (Panel B). Overall median amplitude of P-wave was 45% larger (.042 vs. .029mV, p<.001) and R-wave was 53% larger (.81 vs. .53 mV, p<.001) for vector length of 75 vs 45mm. The oblique vector angle had the largest P-wave amplitude of .038mV (.022 – .054) and R-wave of 0.76mV (0.52 – 1.08). P-wave amplitude was identical between both gender at all vector angles. Marginal differences in R-wave amplitude are noted between males and females for vertical vector only, but not with oblique or horizontal angle. Although the oblique angle had the largest P- and R-wave amplitudes, a longer sensing vector provides larger EGM amplitudes which may be important for achieving adequate electrogram sensing when ICM implant orientation is influenced by cosmetic or anatomical considerations.

Aversive memory conditioning induces fluoxetine-dependent anxiety-like states in the crab Neohelice granulata.

The interactions between memory processes and emotions are complex. Our previous investigations in the crab Neohelice led to an adaptation of the affective extension of sometimes opponent processes (AESOP) model. The model proposes that emotions generate separate emotive memory traces, and that the unfolding of emotional responses is a crucial component of the behavioral expression of reactivated memories. Here, we show that an aversive conditioning, that used changes in an innate escape response to an aversive visual stimulus, induced an emotional behavior that endured beyond the stimuli: the aversive memory training built an anxiety-like state evaluated in a dark/light plus-maze. We found that, after the training session, crabs displayed aversion to maze light areas, and an increased time immobilized in the dark zones of the maze, an anxiety-like behavior induced by stressors or physiological conditions in other crustaceans. The training-dependent anxiety-like behavior was blocked by pretraining administration of fluoxetine, suggesting an underlying serotonin-dependent phenomenon. We hypothesize that this training-induced anxiety-like state generates a separate emotive memory trace that is reinstated and crucial for the modulation of memory expression once the memory is reactivated.

Design, Synthesis and Application of Chemically Modified Amberlite XAD‐2 for Separation and Preconcentration of Pb(II)

AbstractA highly selective, efficient, green analytical method was developed to separate and preconcentrate trace amounts of lead from aqueous samples using gallic acid‐immobilized Amberlite XAD‐2. The method was designed by determining the stability constant of the Pb‐GA complex and plotting the chemical speciation diagram, which indicated strong complexation of Pb(II) with GA (log βPb‐GA=9.50). The species distribution curve for the Pb‐GA complex indicates almost 98 % complexation, forming Pb‐GA as the predominant species. Considering the strong interaction of GA toward the lead, GA was immobilized on the polymeric matrix of Amberlite XAD‐2, and the conditions for the uptake of lead from the aqueous solutions were optimized by both batch and column methods. The sorption capacity and concentration factor of modified Amberlite XAD‐2 for Pb(II) were found to be 4554 μg g−1 and100 respectively. The method was employed for the determination of lead in various wastewater samples. Molecular modeling studies were also performed on GA‐immobilized Amberlite XAD‐2 to determine the active structure of GA on the surface.

Tendon Cells Root Into (Instead of Attach to) Humeral Bone Head via Fibrocartilage-Enthesis.

Large joints are composed of two closely linked cartilages: articular cartilage (AC; rich in type II collagen, a well-studied tissue) and fibrocartilaginous enthesis (FE; rich in type I collagen, common disorder sites of enthesopathy and sporting injuries, although receiving little attention). For many years, both cartilages were thought to be formed by chondrocytes, whereas tendon, which attaches to the humeral bone head, is primarily considered as a completely different connective tissue. In this study, we raised an unconventional hypothesis: tendon cells directly form FE via cell transdifferentiation. To test this hypothesis, we first qualitatively and quantitatively demonstrated distinct differences between AC and FE in cell morphology and cell distribution, mineralization status, extracellular matrix (ECM) contents, and critical ECM protein expression profiles using comprehensive approaches. Next, we traced the cell fate of tendon cells using ScxLin (a tendon specific Cre ScxCreERT2; R26R-tdTomato line) with one-time tamoxifen induction at early (P3) or young adult (P28) stages and harvested mice at different development ages, respectively. Our early tracing data revealed different growth events in tendon and FE: an initial increase but gradual decrease in the ScxLin tendon cells and a continuous expansion in the ScxLin FE cells. The young adult tracing data demonstrated continuous recruitment of ScxLin cells into FE expansion during P28 and P56. A separate tracing line, 3.2 Col 1Lin (a so-called "bone-specific" line), further confirmed the direct contribution of tendon cells for FE cell formation, which occurred in days but FE ECM maturation (including high levels of SOST, a potent Wnt signaling inhibitor) took weeks. Finally, loss of function data using diphtheria toxin fragment A (DTA) in ScxLin cells demonstrated a significant reduction of ScxLin cells in both tendons and FE cells, whereas the gain of function study (by stabilizing β-catenin in ScxLin tendon cells via one-time injection of tamoxifen at P3 and harvesting at P60) displayed great expansion of both ScxLin tendon and FE mass. Together, our studies demonstrated that fibrocartilage is an invaded enthesis likely originating from the tendon via a quick cell transdifferentiation mechanism with a lengthy ECM maturation process. The postnatally formed fibrocartilage roots into existing cartilage and firmly connects tendon and bone instead of acting as a simple attachment site as widely believed. We believe that this study will stimulate more intense exploring in this understudied area, especially for patients with enthesopathy and sporting injuries.

Lamellar structure silver sulfide nanoparticles for adsorption and selective separation of zirconium, yttrium and strontium ions

This work is devoted to the preparation and characterization of silver sulfide (Ag2S) nanoparticles and used as an adsorbent for the separation and purification of Zr(IV), Y(III), and Sr(II) as a simulation mode for the purification of 89Zr from its parents (Y or Sr) and separation of 90Y from its parent Sr using batch and dynamic conditions. N2 adsorption-desorption isotherm for Ag2S is of type IV with a specific surface area (222 ± 0.4 m2/g). The surface is homogeneous texture in which connected channels of diameter 8.3 µm with embedded lamellar structures and the average nanoparticle sizes of 42 ± 3 nm. Ag2S nanoparticles sorbent material shows high selectivity for Zr(IV) from 0.01 M HCl with fast kinetics while 67.2% of Y(III) was removed at pH 4.5 and Sr(II) ions are nil. The adsorption process is exothermic and the intra-particle diffusion and film diffusion were involved in the adsorption mechanism. Also, the separation process was achieved using the column technique with a purity of 100% using different concentrations of HNO3 as eluent. Silver sulfide as an adsorbent material shows a promising potential with high sensitivity for separation and purification trace of Zr, Y, and Sr ions.

Abstract 9552: Optimal Sensing Vector for Maximal Pwave Amplitude, Implications for Insertable Cardiac Monitor (ICM) Implantation

Introduction: Pwave visibility on electrograms (EGMs) obtained by Insertable Cardiac Monitor (ICM) can enhance the diagnostic accuracy of atrial arrhythmias. Objective: To assess the optimal sensing vector for maximal Pwave amplitude obtained on sinus rhythm strips from the precordial region of patients undergoing cardiac investigation. Methods: 150 participants each had 12 separate tracings of single-lead surface EKG acquired using Northeast Holter (DR200/HE) placed to mimic ICM recordings. 3M electrodes were positioned at different vector length (75mm &amp; 45mm) for each of three angles (vertical, oblique, horizontal) repeated in two postures (upright &amp; supine). Impedance-based body fat percentage (BF%) was measured. Fifty patients also received ICM implant in 1:1 recruitment (Medtronic LINQ:Biotronik Biomonitor IIIm) with device EGM attained. All EKG and EGM were uploaded into DigitizeIt software for offline analysis by blinded technicians who measured calibrated Pwave amplitude. The minimum amplitude for readily visible Pwave on ICM has previously been reported as .015mV, and this threshold was used to define acceptable Pwave amplitude. Results: 150 participants [55.5% male, median age 59years (IQR 35 - 73)] each had 12 EKG strips obtained (total 1,800). Median Pwave was 45% larger for 75 vs. 45mm (.042 vs. .029mV, p&lt;.001). Good correlation was seen for EKG and EGM, with Pwave ICC .74 (95%CI .58 - .84). In total, 79% (n=1,415) of EKG had sufficient Pwave visibility (≥.015mV), with a greater proportion seen for 75 vs. 45mm vector (84% vs 73%, p&lt;.001). Overall, Pwave amplitude was lower for higher BF% patients. Among the top third BF% (figure), Pwaves were twice [OR 2.03 (95%CI 1.04 - 3.95)] as likely to be of visible amplitude for 75mm vector (oblique angle) compared to the best 45mm vector (vertical). Conclusion: Longer sensing vector provides superior Pwave amplitude, particularly for high BF%, which is important when factoring ICM device selection for patients.

An eco-friendly ultrasound-assisted deep eutectic solvent-based liquid–phase microextraction method for enrichment and quantification of nickel in environmental samples

An eco-friendly and easy ultrasound-assisted liquid phase microextraction approach using deep eutectic solvent (UA-DES-LPME) was established to preconcentrate and separate trace amount of nickel (Ni(II)) in various environmental samples before flame atomic absorption spectrometric estimation. In this method, Ni(II) was complexed with 2-(benzothiazolyl azo) orcinol reagent. The impacts various parameters on the microextarction of Ni(II) was investigated. The calibration graph is linear in the range of 1–500 µg L−1 and limits of detection and quantification were determined as 0.27 and 0.90 μg L−1, respectively. The RSD% and preconcentration factor were 2.30% and 100, respectively. The analysis of certified reference materials demonstrated the validity of the established procedure. The microextraction method provided here simple, rapid, cheap, green and was effectively used to determine nickel levels in a variety of environmental samples with recoveries ranged of 95.0–98.54%.

Comparison of awake Electroencephalography, Electroencephalography after Sleep Deprivation, and Melatonin-Induced Sleep Electroencephalography Sensitivity in the Diagnosis of Epilepsy in Adults

Introduction: The aim of this study was to compare routine awake electroencephalography (r-EEG), melatonin-induced sleep EEG (m-EEG) and EEG (d-EEG) after sleep deprivation studies in terms of epileptiform anomalies (EA), and to compare d-EEG and m-EEG studies in terms of sleep induction in patients requiring differential diagnosis of epileptic seizure/nonepileptic seizure. Methods: The study included 45 patients aged 18–45 years who had at least one seizure suspected to be epileptic but could not be diagnosed with epilepsy with clinical and laboratory findings. Each patient underwent r-EEG on the 1st day, d-EEG on the 2nd day after 24 h of sleeplessness, and m-EEG on the 3rd day after the administration of 6 mg melatonin following 7 h night sleep. Three separate EEG tracings of the patients were compared for EA. The d-EEG and m-EEG methods were examined for their ability to achieve sleep, total sleep time (ST), and sleep latency (SL). Results: When the detection rate of EA in d-EEG and m-EEG was compared with that of r-EEG, it was found to be significantly higher (P &lt; 0.001) (73.3% with d-EEG, 75.6% with m-EEG, and 35.6% with r-EEG). Sleep was achieved at a rate of 100% after receiving melatonin and at a rate of 97.8% with sleep deprivation. There was no significant difference between d-EEG and m-EEG in terms of mean ST and SL (ST = 58.6 ± 12.6 min and 59.7 ± 8.3 min, respectively; SL = 287.6 ± 484.3 s and 152.2 ± 178.7 s after the start of the EEG, respectively). Conclusions: Sleep EEG is superior to awake EEG in terms of detecting EA. In an EEG study, where melatonin was used to induce sleep, the sleep rate and SL were similar to those of d-EEG, and melatonin did not have an EA increasing or suppressing effect on EEG. Given the ease of application and low side effect profile, it is thought that m-EEG may be an applicable method in the diagnosis of epilepsy.

Selective recovery of rhenium from the simulating leaching solutions of uranium ore by amino guanidine functionalized microcrystalline cellulose microsphere

Rhenium (Re) is the rarest metallic element. Re recovery from leaching solution of uranium ore can not only expand the Re resource, but also improve the mining value of uranium ore. In this paper, amino guanidine functionalized cellulose (AGfC) was successfully synthesized and employed as material for effective and selective separation of Re. The adsorption behavior of AGfC toward Re was systematically investigated with batch and fix-bed column experiments. The results demonstrated that the adsorption kinetics were followed by the pseudo-second-order kinetic model. The adsorption isotherm was followed by the Langmuir model, which calculated a maximum adsorption capacity of 264.55 mg/g at pH 2.37. The fix-bed column tests revealed that the Thomas model and Yoon-Nelson model can best describe the column adsorption data. Especially, AGfC can effectively and selectively separate trace ReO4– from the simulated underground leaching solutions of uranium ore. Furthermore, AGfC can be effectively regenerated by HCl or HNO3. FTIR and XPS analyses showed that the adsorption mechanism of ReO4– was the hydrogen bond and the electrostatic interaction by the positive charge of AGfC.

Removing of some heavy metals from cutting rock samples by using nano graphene oxide

A modified Totland's approach was used to separate and preconcentrate trace elements from cutting rock samples obtained from different depths of oil fields in Maysan Province, Iraq. FT-IR, UV-Vis spectrophotometer, (XRD) X-ray diffraction spectroscopy, (ZP) Zeta potential analyzer, and (FESEM) field emission scanning electronic microscopy, were used to characterize (NGO) nano graphene oxide, synthesized by a modified Hummer's method. The (SPME) method solid phase micro extraction method employed to remove the trace elements (Mg, Co, Ni, Cu, Cd, and Pb) from cutting rock samples under the optimum conditions. The average concentrations of Magnesium, Cobalt, Nickel, Copper, Cadmium, and Lead, the average concentrations in cutting rock samples (direct technique) were (9.72 g/mL), (1.318 g/mL), (5.646 g/mL), (0.616 g/mL), (0.567 g/mL), and (9.296 g/mL). The average element concentrations by SPME technique (2.082 g/mL), (0.24 g/mL), (1.066 g/mL), (0.162 g/mL), (0.055 g/mL), and (2.153 g/mL) for Magnesium, Cobalt, Nickel, Copper, Cadmium, and Lead, respectively were decreased, confirming the chemical adsorption process on the (NGO) surface sheets.

Separation behavior of As, Zn and Cd trace impurities in the deep vacuum purification process of refined lead

Environmentally friendly vacuum distillation has been employed to purify refined lead (99.996%), aiming to separate low-boiling point trace impurities of As, Zn and Cd in refined lead and to provide a foundation for the preparation of high-purity lead (5 N) and ultrapure lead (6 N). In this paper, the low-boiling point trace impurities As, Zn and Cd in refined lead are removed by low-temperature vacuum distillation (LTVD). Detailed analysis of the initial and purified lead was performed by glow discharge mass spectrometry (GDMS) to reveal that Cd and Zn were evaporated as volatiles and were removed from the refined lead in a crucible. Correspondingly, the contents of Zn and Cd impurities decreased from 4 ppmw and 1 ppmw to 0.006 ppmw and 0.01 ppmw, respectively. In contrast to the removal efficiencies of Zn and Cd by LTVD, the removal efficiency of As impurities is only 4%. To cope with this, a novel high-temperature pyrolysis-zone condensation (HTP-ZC) vacuum purification process is proposed for further As separation. The HTP-ZC results indicate that As, Cd and Zn are condensed as residues and removed in the condensation stage. Removal efficiencies of 99.96% for As, 99.98% for Zn, and approximately 100% for Cd were achieved. This approach, with huge industrialization potential, pushes the direct yield of the product to 90% and effectively removes trace impurities with low boiling points, such as As, Cd and Zn, in refined lead. The proposed HTP-ZC process has the potential to stably, cleanly and efficiently produce high-purity lead and ultrapure lead.

Pilot Evaluations of Two Bluetooth Contact Tracing Approaches on a University Campus: Mixed Methods Study.

BackgroundMany have proposed the use of Bluetooth technology to help scale up contact tracing for COVID-19. However, much remains unknown about the accuracy of this technology in real-world settings, the attitudes of potential users, and the differences between delivery formats (mobile app vs carriable or wearable devices).ObjectiveWe pilot tested 2 separate Bluetooth contact tracing technologies on a university campus to evaluate their sensitivity and specificity, and to learn from the experiences of the participants.MethodsWe used a convergent mixed methods study design, and participants included graduate students and researchers working on a university campus during June and July 2020. We conducted separate 2-week pilot studies for each Bluetooth technology. The first was for a mobile phone app (“app pilot”), and the second was for a small electronic “tag” (“tag pilot”). Participants validated a list of Bluetooth-identified contacts daily and reported additional close contacts not identified by Bluetooth. We used these data to estimate sensitivity and specificity. Participants completed a postparticipation survey regarding appropriateness, usability, acceptability, and adherence, and provided additional feedback via free text. We used tests of proportions to evaluate differences in survey responses between participants from each pilot, paired t tests to measure differences between compatible survey questions, and qualitative analysis to evaluate the survey’s free-text responses.ResultsAmong 25 participants in the app pilot, 53 contact interactions were identified by Bluetooth and an additional 61 by self-report. Among 17 participants in the tag pilot, 171 contact interactions were identified by Bluetooth and an additional 4 by self-report. The tag had significantly higher sensitivity compared with the app (46/49, 94% vs 35/61, 57%; P<.001), as well as higher specificity (120/126, 95% vs 123/141, 87%; P=.02). Most participants felt that Bluetooth contact tracing was appropriate on campus (26/32, 81%), while significantly fewer participants felt that using other technologies, such as GPS or Wi-Fi, was appropriate (17/31, 55%; P=.02). Most participants preferred technology developed and managed by the university rather than a third party (27/32, 84%) and preferred not to have tracing apps on their personal phones (21/32, 66%), due to “concerns with privacy.” There were no significant differences in self-reported adherence rates across pilots.ConclusionsConvenient and carriable Bluetooth technology may improve tracing efficiency while alleviating privacy concerns by shifting data collection away from personal devices. With accuracy comparable to, and in this case, superior to, mobile phone apps, such approaches may be suitable for workplace or school settings with the ability to purchase and maintain physical devices.