During the last years, enzyme-based biosensors have gained much more attention among the researchers and have had great success in the determination of different biological macromolecules. ...Nanomaterials with intrinsic enzyme-mimic activity are widely used in biomedicine as artificial enzymes. Here, we report glucose oxidase-mimic activity of nanolayered manganese-calcium (Mn–Ca) oxide nanoparticles (NL-MnCaO2). In this work, NL-MnCaO2nanoparticles were synthesized and characterized using different techniques including transmission electron microscopy (TEM), scanning electron microscopy (SEM), fourier-transform infrared spectroscopy (FTIR) and powder X-ray diffraction (XRD). Also, the ability of these compounds for the glucose and hydrogen peroxide (H2O2) determination was investigated. A non-enzymatic strategy for the colorimetric detection of glucose and H2O2 was reported which can be utilized not only for the rapid detection and analysis of glucose by the naked eye but also the quantitative assay of glucose by spectrophotometry. The in situ generated H2O2 and gluconic acid (GA) from the oxidation of glucose through the glucose oxidase-mimicking activity of NL-MnCaO2 was detected using a colorimetric method. Also, the results confirmed the application of these compounds for the detection of glucose in human serum samples with a detection limit (LOD) of 6.12 × 10−6 M. The results showed that NL-MnCaO2 can be used as an alternative for the natural enzymes and act as a simple, sensitive and enzyme-free biosensor for the detection of glucose in real samples. The proposed strategy shows some advantages including sensitivity, short detection time and low detection limit.
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•Glucose oxidase-like activity of NL-MnCaO2 was investigated using colorimetric method.•An enzyme free biosensor for the detection of glucose in real samples was developed.•Catalytic efficiency of NL-MnCaO2 was dependent on pH and temperature.•NL-MnCaO2 is a multi-functional enzyme mimetic nanostructure which can be used in various fields of biomedicine.
Abstract This study explored the catalytic performance of two robust zirconium-based metal–organic frameworks (MOFs), MIP-202(Zr) and UiO-66-(CO 2 H) 2 in the ring-opening of epoxides using alcohols ...and amines as nucleophilic reagents. The MOFs were characterized by techniques such as FT-IR, PXRD, FE-SEM, and EDX. Through systematic optimization of key parameters (catalyst amount, time, temperature, solvent), MIP-202(Zr) achieved 99% styrene oxide conversion in 25 min with methanol at room temperature using 5 mg catalyst. In contrast, UiO-66-(CO 2 H) 2 required drastically harsher conditions of 120 min, 60 °C, and four times the catalyst loading to reach 98% conversion. A similar trend was observed for ring-opening with aniline –MIP-202(Zr) gave 93% conversion in one hour at room temperature, while UiO-66-(CO 2 H) 2 needed two hours at 60 °C for 95% conversion. The superior performance of MIP-202(Zr) likely stems from cooperative Brønsted/Lewis acid sites and higher proton conductivity enabling more efficient epoxide activation. Remarkably, MIP-202(Zr) maintained consistent activity over five recycles in the ring-opening of styrene oxide by methanol and over three recycles in the ring-opening of styrene oxide by aniline. Testing various epoxide substrates and nucleophiles revealed trends in reactivity governed by electronic and steric effects. The results provide useful insights into tuning Zr-MOF-based catalysts and highlight the promise of the cost-effective and sustainable MIP-202(Zr) for diverse epoxide ring-opening reactions on an industrial scale.
Ultra-small and highly dispersive (< 10 nm) iron oxide hydroxide is characterized by some methods. The compound is an efficient and stable catalyst for alcohol oxidation, organic sulfide oxidation, ...and epoxidation of alkenes in the presence of H
O
. The electrochemical oxygen-evolution reaction of the iron oxide hydroxide is also tested under acidic, neutral, and alkaline conditions. In the presence of the iron oxide hydroxide, excellent conversions (75-100%) and selectivities of substrates (92-97%), depending on the nature of the sulfide, were obtained. Benzylalcohols having electron-donating and-withdrawing substituents in the aromatic ring were oxidized to produce the corresponding aldehydes with excellent conversion (65-89%) and selectivity (96-100%) using this iron oxide hydroxide. The conversion of styrene and cyclooctene toward the epoxidation in the presence of this catalyst are 60 and 53%, respectively. Water oxidation for the catalysts was investigated at pH 2, 6.7, 12, and 14. The onset of OER at pH 14 is observed with a 475 mV overpotential. At 585 mV overpotential, a current density of more than 0.18 mA/cm
and a turnover frequency of 1.5/h is observed. Operando high-resolution visible spectroscopy at pH 14, similar to previously reported investigations, shows that Fe(IV)=O is an intermediate for water oxidation.
A new organic-functionalized Cu-based Anderson-type polyoxomolybdate, namely (C
H
N
)
Na(H
O)
C
H
CuMo
N
O
·2(H
O) (Cu
-POM), was synthesized via a simple one-pot reaction and subsequently ...characterized using a range of analytical and spectral techniques. Structural investigation by single crystal X-ray diffraction analysis revealed that the polyanion component of the synthesized compound (i.e. C
H
CuMo
N
O
) possesses a δ-isomer Anderson-type structure, which is surrounded by four lattice water molecules and four C
H
N
-NaH
(H
O)
cations in the crystal packing arrangement. The resulting double-sided tris-functionalized Anderson-type compound can function as highly effective heterogeneous photocatalysts for the copper(I)-catalyzed Huisgen azide-alkyne cycloaddition (Cu-AAC) reaction of terminal alkyne, benzyl halides, and sodium azide (acts as the azidonation and reducing agent) in aqueous media. Ultraviolet light irradiation enhances the catalytic activity of Cu
-POM ~ 4.4 times of the "off" situation under reaction conditions of 0.00239 mmol cat., 80 °C, 8 h, 2 mL H
O, So that the isolated yields for the AAC reaction involving a variety of terminal alkynes and benzyl halides using the Cu
-POM catalyst ranged between 19-97%. The current study is the first report about using an efficient and economical Cu(II)-POM/UV/NaN
catalytic system in the Cu-AAC reaction and reveals its significant potential for applying to other Cu(I)-catalyzed reactions.
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•Copper(II)—polyhedral oligomeric silsesquioxane (POSS)—bridged Schiff base was synthesized.•Excellent yield has been achieved.•Recoverability and reusability of catalyst was studied.
...The azide–alkyne cycloaddition reaction was investigated under catalytic conditions involving a copper(II)—polyhedral oligomeric silsesquioxane (POSS)—bridged Schiff base. This material demonstrated a high catalytic activity in organic synthesis of 1,4-triazoles. No additive such as a base or a reductant was required. Finally, recoverability and reusability of the POSS-bridged Schiff base–Cu(II) catalyst was analyzed.
Designing efficient membranes for desalination to help reduce the water shortage crisis has been the subject of various studies. In this study, first, CuAl LDH nanosheets were prepared and the ...surface of some thin-film composite (TFC) membranes was modified by them. Afterward, the novel heterostructure nanocomposite consisting of CuAl LDH and WS
2
nanosheets was synthesized by hydrothermal method, and a new kind of thin-film nanocomposite (TFN) membranes were made using them. All the obtained membranes performance was studied in the forward osmosis (FO) process. The effects of the prepared compounds on the morphology, chemical structure, hydrophilicity, and topology of the polyamide (PA) active layer were evaluated by scanning electron microscopy (SEM), FT-IR spectroscopy, energy-dispersive X-ray (EDX), powder x-ray diffraction (XRD), water contact angle (WCA) goniometer and atomic force microscope (AFM) analysis. Finally, by comparing the results for both types of modified membranes, the membrane containing 0.025 wt% of the nanocomposite modifier showed the highest water flux (29.30 LMH) and selectivity (0.38 g/L) that was chosen as the optimal membrane. Also, the anti-fouling properties of this membrane were studied and the obtained results showed an increase in the fouling resistance compared to the membrane without filler.
Graphical Abstract
In the present work, we used vanadium oxide nanoparticles (V
2
O
5
NPs) with intrinsic peroxidase-mimic activity for the removal of malachite green (MG). V
2
O
5
NPs were synthesized and ...characterized using different methods such as scanning electron microscopy, Fourier-transform infrared spectroscopy and powder X-ray diffraction technique. Enzyme-mimetic catalytic activity of V
2
O
5
NPs was assessed spectrophotometrically by using a calorimetric method and the results showed the peroxidase-like activity of these particles. Kinetic parameters including
K
m
and
V
max
were calculated to be 48.31 × 10
–3
mM and 0.93 mM/min (for TMB as a substrate) and 26.47 mM and 1.39 mM/min (for H
2
O
2
as a substrate), respectively. Also, decolorization of MG was investigated in the presence of prepared nanoparticles and the results indicated that the V
2
O
5
NPs completed the decolorization process of MG within 2 h. These results suggest that V
2
O
5
NPs, with intrinsic peroxidase-mimic activity, can be effective in decolorizing and detoxifying MG from wastewaters of food and aquaculture industries.
Nanoparticles of manganese oxide supported on tungsten oxide (WO
3
) were synthesized by an impregnation method using Mn(NO
3
)
2
and Na
2
WO
4
as a source of manganese and tungsten. Atomic ...absorption spectroscopy (AAS), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the physicochemical properties of compounds. Due to a highly dispersed state of manganese or insertion of manganese ions into the WO
3
lattice, no manganese oxide peak was observed in the XRD patterns of the W
1−
x
Mn
x
O
3
nanoparticles. Investigation of W
1−
x
Mn
x
O
3
by AAS and EDX showed that the relative atomic abundance of Mn present in the bulk and on the surface of WO
3
was 3.68% and 4.8% respectively. For the first time, the catalytic oxidation of olefins and alcohols, in the presence of these materials and hydrogen peroxide (H
2
O
2
) as a green oxidant at room temperature was studied. The recoverability and catalyst leaching of the W
1−
x
Mn
x
O
3
nanoparticles in epoxidation of styrene as a model reaction were also investigated.
Background
Translation quality assessment (TQA) suffers from subjectivity in both neighboring disciplines: ‘TEFL’ and ‘Translation Studies, and more empirical studies are required to get closer to ...objectivity in this domain. The present study evaluated the quality of the written translation of TEFL students through three different approaches to translation quality assessment (TQA) in order to examine the efficiency and reliability of the three methods and ultimately suggest the most reliable one.
Methods
Thirty BA TEFL university students translated a text from English into Persian, and three raters scored the translated texts through three different methods of assessment.
Results
The results of statistical analysis indicated that, the error analysis method B was more reliable than holistic method C, but was less reliable than combined method D.
Conclusions
That is, when we combined the results of both error analysis and holistic methods in a proportion of 70/30, the new combined error analysis-holistic method got a better reliability rating, and accurate results than holistic and analytic methods. Therefore, the combined method may be suggested as a reliable method for evaluating and scoring the TEFL students’ translations.
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•Co3O4-NPs were synthesized and modified by argon cold plasma (Ar-Co3O4-NPs).•Surface plasma modification improved the peroxidase-mimic activity of Ar-Co3O4-NPs.•Enhanced catalytic ...activity of Ar-Co3O4-NPs was used for the degradation of MG dye.•Ar-Co3O4-NPs exhibited a high dye removal efficiency of 96.78 % within 70 min.•ANN with a 5:7:1 topology successfully modeled the catalytic degradation process.
This study highlights a simple and efficient nanochemistry-based approach for the effective degradation of triphenylmethane and toxic dye, malachite green (MG) using Argon cold plasma-modified cobalt oxide nanoparticles (Ar-Co3O4-NPs). Synthesized particles were characterized using scanning electron microscope, X-ray diffraction, and Fourier-transform infrared spectroscopy. The peroxidase-mimic activity of Co3O4-NPs was evaluated, and the results confirmed that the catalytic activity of Co3O4-NPs was enhanced after plasma modification. The decomposition of MG was tested using the improved catalytic activity of Ar-Co3O4-NPs in model aqueous solution. The results indicated the ability of 0.16 g/mL Ar-Co3O4-NPs to completely degrade 40 µM MG within 70 min with a decolorization efficiency of 96.78%. Experimental conditions were optimized for maximum MG removal. Gas chromatography-mass spectrometry was used to determine the byproducts of MG degradation, and the findings indicated the production of less toxic products. The toxicity of the resultant metabolites of MG degradation was evaluated against E. coli and B. subtilis and the results confirmed less toxic product formation. Artificial neural networks (ANNs) were used to model the catalytic degradation data, and the strong correlation between experimental observations and ANN model predictions suggested that the designed model could accurately predict MG dye removal efficiency under different operating conditions.
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