Absence Of Peroxide Research Articles

Uranium Extraction from Gattar Granite Sample After Leaching Using Nitrate Solution in Presence of Peroxide

The Gattar area is classified as one of the most important Egyptian uranium resources. In this work, the leaching of uranium from Gattar granitic ore containing 1138 ppm U using NaNO3 solution has been applied. The leaching factors of nitrate in the presence and absence of hydrogen peroxide as oxidant were studied and optimized. The obtained data show that uranium leaching in the absence of oxidants was only 46%. The main role of the peroxide is oxidizing the iron content to Fe3+ species, which is responsible for oxidizing the nonleachable U4+ to leachable U6+. Based on the obtained results with 0.005 M NaNO3 in the presence of 15 mmol l−1 H2O2 with a 4/1 liquid/solid ratio at 75°C for 6 h as optimum leaching conditions, the uranium leaching efficiency was 82.5%. The leach liquor was then subjected to an extraction step using 4% Alamine 336/kerosene. Alamine 336 extracted 92.3% from the leached uranium content. The resultant solvent was then treated with a carbonate solution to strip the loaded uranium. Finally, the carbonate solution was then treated with NaOH to precipitate the uranium species at pH 11.5.

Photo-Active K and Na Doped Strontium Ferrite by Co-Precipitation; Ph, Oxidative and Thermal Stabilities Characterisation

The perovskite nanoparticles, Sr1-XMXFeO3(M=Na and K, x=0.1, 0.2) were prepared using metal precursors; Fe(NO3)2.9H2O and Sr(NO3)2 by co-precipitation method in the presence of sodium dodecylsulphate. The produced powder was annealed at 500°C, 700°C, and 800°C in a Muffle furnace. The obtained powders were characterised using the powder X-ray diffraction (PXRD) which indicated that the samples crystallised in a distorted hexagonal structure. The prominent peak in each of the perovskite sample, increased with increasing annealing temperature. Thermogravimetric analysis (TGA) of the samples showed a weight loss between the temperature range of 300–500°C due to K2O decomposition. The differential thermal analysis (DTA) showed the powders to possess endothermic activities at the positive derivative weight lost, with desorption and vapourisation up to 400°C. The oxidative and thermal stabilities determined at 500°C and above for both the TGA and DTA were reported in this work. Scanning electron microscopy (SEM) of the powdered nanoparticles showed the morphology of the particles starting from the nucleation stage, to formation and distribution. The photocatalytic activity of all powders were tested against methylene blue pollutant as a mordant dye, both in the presence and absence of hydrogen peroxide at pH=6.8. Powders at lower annealing temperatures were not very active but all powders at 800°C showed the highest degradation efficiency for the Na and K doped SrFeO3, this was also confirmed at the pH of 12 for K-doped nanaoparticle on the MB photodegradation.

Development and demonstration of functionalized inorganic-organic hybrid copper phosphate nanoflowers for mimicking the oxidative reactions of metalloenzymes by working as a nanozyme.

Copper phosphate nanoflowers (CuPNFs) have been synthesized in the presence of different aromatic phenanthroline derivatives (Ln), leading to inorganic-organic hybrid materials (Ln-CuPNFs). Studies revealed that the morphology of nanoflowers varies as a function of the aromatic moiety present in the derivative, Ln (where 'n' corresponds to phenyl, naphthyl, anthracenyl, and pyrenyl) used for coating the nanomaterial. Other noticeable changes were the increase in the size of the flower by ∼2-3 fold in the presence of these derivatives. In the absence of such aromatic phenanthroline derivatives, i.e., the use of 1,10-phenanthroline-5-amine did not induce the formation of nanoflowers, suggesting that the organic derivatization used in the present study stabilizes the nanoflower structure. Nanoflowers were characterized using X-ray diffraction, Brunauer-Emmett-Teller (BET) isotherm, X-ray photoelectron spectroscopy, Raman and Infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy, thus covering a range of diffraction, spectroscopy, and microscopy techniques. Nanoflowers, Ln-CuPNFs, have been demonstrated for the oxidative reactions mimicking copper metalloenzymes in the presence and absence of hydrogen peroxide using different substrates. Thus, hybrid Ln-CuPNFs mediate the complete oxidation of o-phenylenediamine, dopamine, ascorbate oxidase, and terephthalic acid without causing much change in the morphology of the hybrid nanoflower material and with the retention of the activity supporting the hybrid as an acceptable enzyme mimicking material. Oxidation is mediated through hydroxyl radical formation and the order of the oxidative activity is pyrenyl > anthracenyl > naphthyl > phenyl for the inorganic-organic hybrid nanoflowers. The copper complex of pyrenyl-appended phenanthroline derivative also showed similar biomimetic activity.

Synthesis and characterization of enzymatically active micrometer protein-capsules

This work describes a general method for the encapsulation of enzymes with albumin as wall material and the enzyme catalase as prime example. Care was taken for the preparation of biochemically active sub-micrometer particles in order to prevent oxygen toxicity induced by artificial oxygen carriers of any type. In cell culture experiments, capsules containing catalase did not exhibit any harmful activities in the absence of peroxides. In the presence of hydrogen peroxide application of low and medium dosed capsules below 0.05 vol% (final concentration 0.001 vol%) even increased the cell damaging process. However, a higher dosage of capsules (>0.05 vol%) prevented completely cellular disruption induced by 5 mM hydrogen peroxide and decreased up to 90% of cellular damage at higher peroxide concentrations. These results demonstrated that encapsulated catalase was enzymatically active and the over-all activity of prepared catalase capsules was determined to be >1900 U mL−1 vol%−1.

UVC- and UVC/H2O2-Driven nonribosomal peptide antibiotics degradation: application to zinc bacitracin as a complex emerging contaminant

Zinc bacitracin (Zn-Bc) belongs to the group of nonribosomal peptide antibiotics (NRPA), comprising a mixture of non-biodegradable congeners characterized by complex structures containing cyclic, polycyclic, and branched chains. However, reports on the use of AOPs for the degradation of NRPA are non-existent. In this context, the present work investigated the photodegradation of Zn-Bc in aqueous solution by direct photolysis and the UVC/H2O2 process. The effects of the specific UVC photon emission rate and initial H2O2 concentration were studied following a Doehlert-design response surface approach. The results showed that all congeners photolyzed at the highest UVC doses in the absence of hydrogen peroxide, with a calculated quantum yield of 0.0141 mol Zn-Bc mol photons−1. However, no TOC removal was observed after 120 minutes of irradiation, suggesting the disruption of the peptide bonds in the antibiotic molecules without significant changes in the amino acid residues. The addition of H2O2 substantially accelerated Zn-Bc photodegradation, resulting in a remarkable removal of up to 71% of TOC. Most importantly, the antimicrobial activity against Staphylococcus aureus could be completely removed by both treatments. These findings point out that the UVC/H2O2 process can be straightly engineered for the treatment of metalloantibiotics-containing wastewater in pharmaceutical facilities.

Obtaining Protoanemonin through Selective Oxidation of D‐Fructose and 5‐(Hydroxymethyl)furfural in a Self‐catalysed Reaction

AbstractAlthough different ways of converting 5‐(hydroxymethyl)furfural (1) to various substrates with high value have been sought, few transformations have obtained building blocks that can be very useful in the area of fine chemistry. Herein, we report the synthesis of protoanemonin (5‐methylenefuran‐2(5H)‐one) from D‐fructose via compound (1), a versatile γ‐alkylidenebutenolide, using an efficient self‐catalysed process with formic acid, with high reaction performance and selectivity (up to 94% yield and 98% conversion from (1), while 28% yield from D‐fructose). This efficient and simple operational process involved a two‐phase aqueous‐organic system between chlorinated solvents (CHxCly) and hydrogen peroxide as the initial oxidizing agent. The reaction presents a key cleavage in the 5‐hydroxymethyl moiety of (1), due to the Baeyer‐Villiger oxidation (BVO) process that generates formic acid in situ. Ultimately, DFF and HMF were successfully obtained in 80% and 98% yield, respectively, starting from D‐fructose and using Preyssler heteropolyacids as Brønsted acid catalysts under an atmosphere of oxygen in the absence of hydrogen peroxide.

Oxidative properties and utility of fabricated MnSiO 3 nanoparticles for colorimetric detection of iron (II) in water samples

MnSiO3 nanoparticles (NPs) were prepared by precipitation method, their structure and composition were characterised by transmission electron microscopy, electron diffraction spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Due to the oxidase-like enzyme activity of MnSiO3, it can catalyse the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in acidic environment to form an oxidised TMB which has an absorption peak at 652 nm in the absence of hydrogen peroxide. When Fe2+ was added to the assay, the oxidase-like activity of MnSiO3 was inhibited, and the intensity of the absorption at 652 nm was reduced. Based on the high oxidase-like activity, a colorimetric method for Fe2+ detection was established, it showed high selectivity and sensitivity. In the optimised conditions, the limit of detection was 0.5 μM with a linear range from 3 to 63 μM. Moreover, the method was applied to determine Fe2+ in spiked water samples which gave satisfactory recoveries.

Curcumin supplementation in the maturation medium improves the maturation, fertilisation and developmental competence of porcine oocytes.

This study was conducted to determine the effects of supplementing the maturation medium with the antioxidant curcumin on the in vitro maturation (IVM), fertilisation and development of porcine oocytes. Curcumin supplementation was performed at concentrations of 0, 5, 10, 20, and 40 µM. At concentrations of 5-20 µM, curcumin had significant positive effects (P < 0.05) on maturation and fertilisation rates compared to the non-treated group. Of the groups cultured with 5-20 µM curcumin, the number of oocytes with DNA-fragmented nuclei after IVM was significantly lower than in groups matured without curcumin. Moreover, curcumin supplementation at 10 µM also gave a significantly higher rate of blastocyst formation compared with oocytes matured without curcumin. Increasing the curcumin concentration to 40 µM yielded negative effects on fertilisation and embryonic development compared with the groups treated with lower concentrations of curcumin. Supplementation with 10 µM curcumin had beneficial effects on the oocyte maturation rate and DNA fragmentation index compared to the non-treated group both in the presence and absence of hydrogen peroxide. These results indicate that curcumin supplementation at a suitable concentration (10 µM) is potentially useful for porcine oocyte culture systems, in terms of protecting oocytes from various forms of oxidative stress.

Black phosphorus quantum dots are useful oxidase mimics for colorimetric determination of biothiols.

Black phosphorus quantum dots (BP QDs) with small size are synthesized usingan easy to operate thermal method. It was found that BP QDs possess oxidase-mimicking activity. They can catalyze the oxidation of thesubstrate 3,3',5,5'-tetramethylbenzidine to produce a blue-colored product even in the absence of hydrogen peroxide. Active oxygen species are proved to be involved in the reaction through the experiments of radical scavenging and electron spin resonance. Biothiols including reduced glutathione and cysteine inactivate the oxidase-mimicking activity of BP QDs, concomitant to the fading of the blue solution. Thisprovides the base fora colorimetric method for the determination of glutathione and cysteine. The decreased absorbance at 652nm displays linear response to the concentrations of glutathione ranging from 0.1 to 5.0μmolL-1, and cysteine from 0.1 to 10.0μmolL-1. The detection limits are 0.02μmolL-1 and 0.03μmolL-1 for glutathione and cysteine, respectively. Successive determinations of 1.0μmolL-1 glutathione and 5.0μmolL-1 cysteine solution give relative standard deviations of 0.8% and 1.7% (n = 11), respectively. As a preliminary application, the practicability of the method was evaluated by the determination of glutathione in pharmaceutical preparations. This work not only discovers a useful oxidase mimics but also sets up a reliable platform based on BP QDs in colorimetric detection. Graphical abstract Schematic representation of colorimetric determination for biothiols through inactivating oxidase mimetic-like catalytic activity of black phosphorus quantum dots(BP QDs) on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB)with dissolved oxygento produce its blue oxidized product(oxTMB).

Expression of Heterologous OsDHAR Gene Improves Glutathione (GSH)-Dependent Antioxidant System and Maintenance of Cellular Redox Status in Synechococcus elongatus PCC 7942.

An excess of reactive oxygen species (ROS) can cause severe oxidative damage to cellular components in photosynthetic cells. Antioxidant systems, such as the glutathione (GSH) pools, regulate redox status in cells to guard against such damage. Dehydroascorbate reductase (DHAR, EC 1.8.5.1) catalyzes the glutathione-dependent reduction of oxidized ascorbate (dehydroascorbate) and contains a redox active site and glutathione binding-site. The DHAR gene is important in biological and abiotic stress responses involving reduction of the oxidative damage caused by ROS. In this study, transgenic Synechococcus elongatus PCC 7942 (TA) was constructed by cloning the Oryza sativa L. japonica DHAR (OsDHAR) gene controlled by an isopropyl β-D-1-thiogalactopyranoside (IPTG)-inducible promoter (Ptrc) into the cyanobacterium to study the functional activities of OsDHAR under oxidative stress caused by hydrogen peroxide exposure. OsDHAR expression increased the growth of S. elongatus PCC 7942 under oxidative stress by reducing the levels of hydroperoxides and malondialdehyde (MDA) and mitigating the loss of chlorophyll. DHAR and glutathione S-transferase activity were higher than in the wild-type S. elongatus PCC 7942 (WT). Additionally, overexpression of OsDHAR in S. elongatus PCC 7942 greatly increased the glutathione (GSH)/glutathione disulfide (GSSG) ratio in the presence or absence of hydrogen peroxide. These results strongly suggest that DHAR attenuates deleterious oxidative effects via the glutathione (GSH)-dependent antioxidant system in cyanobacterial cells. The expression of heterologous OsDHAR in S. elongatus PCC 7942 protected cells from oxidative damage through a GSH-dependent antioxidant system via GSH-dependent reactions at the redox active site and GSH binding site residues during oxidative stress.

Highly Sensitive Electrochemical Determination of Norepinephrine Using Poly Acrylic Acid‐Coated Nanoceria

AbstractWe synthesized a poly acrylic acid‐coated nanoceria (PNC) and developed colorimetric and electrochemical methods for determining norepinephrine (NE) using 3,3′‐5,5′‐tetramethylbenzidine (TMB) as a redox marker. The PNC was the nanozyme, an oxidase mimic with effective catalytic activity. During the reaction, PNC oxidized the TMB (TMBox) in the absence of hydrogen peroxide. The product not only showed visible color change from transparent to blue, but also generated an electrochemical current. NE reduced the TMBox, and the color changed from blue back to colorless. As a result, we were able to determine the NE concentration using both colorimetric and electrochemical methods. The colorimetric determination showed a linearity from 0.2 to 19 μM, with an estimated detection limit of 126 nM. For point‐of‐care applications, NE concentration was also detected on paper‐based devices. NE was detected from 1.0 to 25 μM with the detection limit of 863 nM. For electrochemical detection, gold nanoparticles were deposited on indium tin oxide glass as the working electrode. NE ranged from 0.1 to 300 μM, with an estimated detection limit of 66 nM, which was lower than for the colorimetric methods. Spike recovery values for NE in human plasma samples ranged from 93.4 to 108 %. These results demonstrate that using PNC nanozymes for electrochemical detection is a promising assay to determine NE.

Sustainable Magnetic Materials (from Chitosan and Municipal Biowaste) for the Removal of Diclofenac from Water.

The photodegradation of an aqueous solution of diclofenac (DCF) has been attempted in the presence of hydrogen peroxide and organic/inorganic hybrid magnetic materials under simulated and real solar light. The hybrid magnetic materials have been prepared via coprecipitation synthesis starting from iron(II) and iron(III) inorganic salts in the presence of bioderived organic products (i.e., chitosan or bio-based substances isolated from commercially available composted urban biowastes) acting as stabilizers of the iron-containing phase. In addition to the as prepared hybrid materials, the corresponding materials obtained after a pyrolytic step at low temperature (550 °C) have been tested. The obtained results evidenced the capability of the materials to activate hydrogen peroxide at mild pH promoting DCF (photo) degradation. All the materials feature also as adsorbents since a decrease of DCF is observed also when working in the dark and in the absence of hydrogen peroxide.

High catalytic activity of gold nanoparticle-templated, tyrosine-rich peptide self-assemblies for 3,3′,5,5′-tetramethylbenzidine oxidation in the absence of hydrogen peroxide

In this study, gold nanoparticle-templated, tyrosine-rich peptide (YC7@AuNPs) self-assemblies were examined as peroxidase enzyme–mimic catalysts for the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and its activity was monitored by changing the reaction conditions such as pH, temperature, initial TMB concentration, and catalyst (Au) loading amount. The YC7@AuNPs catalysts were active for TMB oxidation even in the absence of hydrogen peroxide. Michaelis–Menten kinetic analysis showed that the YC7@AuNPs catalysts without hydrogen peroxide have activities comparable to other peroxidase–mimic catalysts using hydrogen peroxide in terms of the Michaelis constant.

BSA interaction and DNA cleavage studies of anti-bacterial benzothiazol-2-yl-malonaldehyde

A new benzothiazole derivative, benzothiazol-2-yl-malonaldehyde (BTM) was synthesized and its biological potency has been investigated in terms of its anti-bacterial activity. Its interaction with bovine serum albumin (BSA) and DNA cleavage studies were also carried out. The interaction between BSA and BTM was studied by multi-spectroscopic approach, which included spectrofluorimetry, CD spctrophotometry and FTIR. The experiments were carried out at three different temperatures and the quenching mechanism was observed to be both static as well as dynamic. The binding was found to be moderate as evident by its binding constant values (of the order of 103). A single binding site was observed and site marker experiments showed site III of BSA for BTM. The negative values of ΔG0 suggested the spontaneity of the interaction and positive values for both ΔH0 and ΔS0 indicated that the nature of interaction was hydrophobic. The CD and FTIR studies revealed that the secondary structure of BSA has been altered upon binding of BTM. BTM cleaved the super-coiled DNA in the presence and absence of hydrogen peroxide at micro-molar concentration. It was also found from the antibacterial activity that BTM showed better activity against gram-negative bacteria Pseudomonas aeruginosa than the other bacterial stains used for the study.

Standardization of a new method for assessing the development of cataract in cultured bovine lenses

PurposeTo standardize a new method for assessing cataractogenesis in isolated cultured bovine lenses using L-cysteine as the standard anti-cataract agent. MethodsIntact bovine lenses were cultured in DMEM with L-cysteine in presence or absence of hydrogen peroxide (H2O2). Lens opacity (transmittance) was determined using a plate reader. Lens homogenate glutathione (GSH) and superoxide dismutase (SOD) contents were measured using enzyme immunoassays kits. ResultsDMEM-cultured lenses exhibited a time-dependent loss in transmittance (230–710 nm) up to 120 h, achieving the highest reduction of 38.6 ± 0.09% at 420 nm (p < .001;n = 12). Compared to untreated lenses (time in hours [t] = 0), L-cysteine (10−6 M and 10−5 M) significantly (p < .001;n = 6) increased time-dependent transmittance (420 nm) by 31.6 ± 0.17% and 28.0 ± 0.07%(t = 120), respectively. When compared to DMEM-cultured lenses (t = 0), H2O2 (10 mM, 50 mM and 100 mM) significantly (p < .001;n = 12) reduced transmittance by 57.8 ± 0.1, 57.4 ± 0.04 and 87.7 ± 0.6%(t = 120), respectively. Moreover, L-cysteine significantly (p < .001;n = 6) attenuated H2O2 (50 mM)-induced decrease in transmittance by 12.5 ± 0.05%(10−6 M), 13.0 ± 0.09%(10−5 M), 14.5 ± 0.08%(10−4 M) and 8.6 ± 0.11%(10−3 M)(t = 120), respectively.When compared to untreated lenses (t = 0), the time-dependent decrease (p < .001;n = 5) in lenticular total GSH content and total SOD activity of 46.1 ± 0.06% and 42.0 ± 1.65% (t = 120) was attenuated (p < .001;n = 5) by L-cysteine (10−6 M) by 76.6 ± 0.06% and 7.4 ± 1.98%, respectively. Similarly, the H2O2(50 mM)-induced decline (p < .001; n = 5) in total GSH content and SOD activity of 82.6 ± 0.08% and 86.6 ± 0.66% (t = 120) was attenuated by L-cysteine (10−4 M) by 74.7 ± 1.05% and 161.1 ± 4.9%, respectively. ConclusionMeasurement of spectral transmission coupled with assessment of the activity of antioxidant enzymes in bovine cultured lens can provide a useful tool in studies of cataracts in an animal model of this disease.

EPR detection of sulfanyl radical during sulfhemoglobin formation – Influence of catalase

Hemoglobin in its ferryl form oxidizes hydrogen sulfide and is transformed to sulfhemoglobin, where the sulfur is inserted covalently at the heme edge. Shown here is evidence that—as previously proposed by others—this process involves oxidation of hydrogen sulfide to a sulfanyl radical detectable by spin-trapping in electron paramagnetic resonance (EPR) spectroscopy. The yields and rates of formation of sulfhemoglobin as well as of the sulfanyl radical are affected by the same factors that affect the reactivity of hemoglobin ferryl, in bovine hemoglobin and in phytoglobins as well. A freely-diffusing sulfanyl radical is thus proposed to be involved in sulfhemoglobin formation. Catalase is shown to accelerate this process due to a previously described hydrogen sulfide oxidase activity, within which EPR evidence for sulfanyl generation is shown here for the first time. The reaction of preformed ferryl with hydrogen sulfide—in absence of hydrogen peroxide—is studied by stopped-flow at several pH values and explained in light of reactivity and redox potential control.

Bactericidal effects and accelerated wound healing using Tb4O7 nanoparticles with intrinsic oxidase-like activity

BackgroundNanomaterials that exhibit intrinsic enzyme-like characteristics have shown great promise as potential antibacterial agents. However, many of them exhibit inefficient antibacterial activity and biosafety problems that limit their usefulness. The development of new nanomaterials with good biocompatibility and rapid bactericidal effects is therefore highly desirable. Here, we show a new type of terbium oxide nanoparticles (Tb4O7 NPs) with intrinsic oxidase-like activity for in vitro and in vivo antibacterial application.ResultsWe find that Tb4O7 NPs can quickly oxidize a series of organic substrates in the absence of hydrogen peroxide. The oxidase-like capacity of Tb4O7 NPs allows these NPs to consume antioxidant biomolecules and generate reactive oxygen species to disable bacteria in vitro. Moreover, the in vivo experiments showed that Tb4O7 NPs are efficacious in wound-healing and are protective of normal tissues.ConclusionsOur results reveal that Tb4O7 NPs have intrinsic oxidase-like activity and show effective antibacterial ability both in vitro and in vivo. These findings demonstrate that Tb4O7 NPs are effective antibacterial agents and may have a potential application in wound healing.

Redox-cycling and intercalating properties of novel mixed copper(II) complexes with non-steroidal anti-inflammatory drugs tolfenamic, mefenamic and flufenamic acids and phenanthroline functionality: Structure, SOD-mimetic activity, interaction with albumin, DNA damage study and anticancer activity

Copper(II) complexes containing non-steroidal anti-inflammatory drugs (NSAIDs) have been the subject of many research papers and reviews. Here we report the synthesis, spectroscopic study and biological activity of novel mixed copper(II) complexes with NSAIDs: tolfenamic (tolf), mefenamic (mef) and flufenamic (fluf) acids and phenanthroline (phen): [Cu(tolf-O,O′)2(phen)] (1), [Cu(mef-O,O′)2(phen)] (2), [Cu(fluf-O,O′)2(phen)] (3). Complexes were characterized by X-ray analysis and EPR spectroscopy. Complexes 1–3 are monomeric, six-coordinate and crystallize in a monoclinic space group. Interaction of Cu(II) complexes with DNA was studied by means of absorption titrations, viscosity measurements and gel electrophoresis. The relative ability of the complexes to cleave DNA even in the absence of hydrogen peroxide is in the order 3 > 2 > 1. Application of the reactive oxygen species (ROS) scavengers, L-histidine, DMSO and SOD confirmed that singlet oxygen, hydroxyl radicals (Fenton reaction) and superoxide radical were formed, respectively. Thus, in addition to mechanism of intercalation, redox-cycling mechanism which in turn lead to the formation of ROS contribute to DNA damage. Cu(II) complexes exhibit excellent SOD-mimetic activity in the order 3~1 > 2. The fluorescence spectroscopy revealed that albumin may act as a targeted drug delivery vehicle for Cu(II) complexes (K~106). The anticancer activities of complexes 1–3 were investigated using an MTS assay (reduction of the tetrazolium compound) against three cancer cell lines (HT-29 human colon adenocarcinoma, HeLa and T-47D breast cancer cells) and mesenchymal stromal cells (MSC). The most promising compound, from the viewpoint of its NSAID biological activity is 3, due to the presence of the three fluorine atoms participating in the formation of weak hydrogen-bonds at the DNA surface.

Chemical Mechanical Planarization of Germanium using Polymorphs of Titania as Abrasive and Hydrogen Peroxide

Abstract In the present work, chemical mechanical planarization (CMP) slurry was formulated for polishing germanium (Ge) using rutile (titania (R)) and anatase (titania (A)) titania as abrasive and hydrogen peroxide (H2O2) as oxidizer. CMP experiments were carried out at identical process conditions with different polymorphs of titania abrasives to understand the role of abrasive on Ge material removal rate (MRR) in the presence and absence of hydrogen peroxide. Etch rate (ER) was calculated based on dissolution study to understand the reaction chemistry with Ge. The effect of pH, rotational speed of platen, pressure and hydrogen peroxide concentration of both polymorphs on Ge removal rate was investigated. Higher MRR and ER of Ge were obtained in alkaline region at pH 11 as compared to the acidic and neutral region. Surface area of titania polymorphs were measured using accelerated surface area and porosimetry system (ASAP). Transmission electron microscopy (TEM) results reveal that the particle size of the both the polymorphs was found to be less than 100 nm. Average particle size of abrasives, calculated using Sauter formula, was found to be 19.4 nm for titania (A) and 21.8 nm for titania (R).

A Review of Fast Bubble-Driven Micromotors Powered by Biocompatible Fuel: Low-Concentration Fuel, Bioactive Fluid and Enzyme.

Micromotors are extensively applied in various fields, including cell separation, drug delivery and environmental protection. Micromotors with high speed and good biocompatibility are highly desirable. Bubble-driven micromotors, propelled by the recoil effect of bubbles ejection, show good performance of motility. The toxicity of concentrated hydrogen peroxide hampers their practical applications in many fields, especially biomedical ones. In this paper, the latest progress was reviewed in terms of constructing fast, bubble-driven micromotors which use biocompatible fuels, including low-concentration fuels, bioactive fluids, and enzymes. The geometry of spherical and tubular micromotors could be optimized to acquire good motility using a low-concentration fuel. Moreover, magnesium- and aluminum-incorporated micromotors move rapidly in water if the passivation layer is cleared in the reaction process. Metal micromotors demonstrate perfect motility in native acid without any external chemical fuel. Several kinds of enzymes, including catalase, glucose oxidase, and ureases were investigated to serve as an alternative to conventional catalysts. They can propel micromotors in dilute peroxide or in the absence of peroxide.