Using Stereolithographic Printing to Manufacture Monolithic Microfluidic Devices with an Extremely High Aspect Ratio

Stereolithographic printing (SL) is widely used to create mini/microfluidic devices; however, the formation of microchannels smaller than 500 μm with good inner surface quality is still challenging due to the printing resolution of current commercial printers and the z-overcure error and scalloping phenomena. In the current study, we used SL printing to create microchannels with the aim of achieving a high degree of dimensional precision and a high-quality microchannel inner surface. Extensive experiments were performed and our results revealed the following: (1) the SL printing of microchannels can be implemented in three steps including channel layer printing, an oxygen inhibition process, and roof layer printing; (2) printing thickness should be reduced to minimize the scalloping phenomenon, which significantly improves dimensional accuracy and the quality of inner microchannel surfaces; (3) the inclusion of an oxygen inhibition step is a critical and efficient approach to suppressing the z-overcure error in order to eliminate the formation of in-channel obstructions; (4) microchannels with an extremely high aspect ratio of 40:1 (4000 μm in height and 100 μm in width) can be successfully manufactured within one hour by following the three-step printing process.

Eco-Friendly Approach to Corrosion Inhibition of Copper in HNO3 Solution by the Expired Tylosin Drug

Expired Tylosin Drug (ETD) is examined as corrosion inhibitor for copper (Cu) dipped in 2.0 M HNO3. The study was conducted utilizing ac impedance spectroscopy (EIS), weight loss (WL), polarization, and surface checks to illustrate the importance of this ETD to prevent the corrosion process for Cu. The influence of temperature and concentration of ETD on the efficiency of inhibition were tested. The corrosion mechanism occurs when the ETD molecules block the active center in the electrode surface. Langmuir isotherm is the isotherm that is applied in the process of adsorption. The effect of temperature at various temperatures on the corrosion efficiency was investigated in case of the presence and absence of ETD. Finally, thermodynamic parameters for the inhibition process were determined. Results were of all methods used are in good agreement.

Corrosion inhibition of aluminium in hydrochloric acid medium using cimetidine as inhibitor: empirical and optimization studies

Purpose The purpose of this study was to investigate cimetidine as corrosion inhibitor of aluminium in hydrochloric acid medium. Design/methodology/approach Cimetidine was characterized by gas chromatography mass spectrophotometer and Fourier transform infrared spectroscopy to determine its chemical composition and functional groups, respectively. Gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopic techniques were used in the corrosion inhibition process. Thermodynamic and adsorption parameters were evaluated. And response surface methodology was used to optimize the corrosion inhibition process. Findings Analysis of the results revealed that major constituents of cimetidine include metronidazole, n-hexadecanoic acid cyclohexane and methyl ester. It has C-H stretch, C = N stretch, CH3C-H bend, ring C = C stretch, -C-O-O stretch, N-H bend, C-O stretch and C-H bend as predominant functional groups. Adsorption of molecules of the inhibitor on the aluminium surface was spontaneous, and it followed mechanism of physical adsorption. Response surface methodology revealed that quadratic model adequately described the inhibition efficiency of cimetidine as function of inhibitor concentration, temperature and time. Chemical and electrochemical results are in agreement that the cimetidine is a viable corrosion inhibitor. Cimetidine was revealed as mixed-type inhibitor because it controlled both cathodic and anodic reactions. Originality/value Empirical and optimization studies of cimetidine drug as corrosion inhibitor of aluminium in hydrochloric acid medium were carried out. The research results can provide the basis for deploying drugs (with mucosal protective and antacid properties) for corrosion control of metallic structures.

L-Cysteine as an Irreversible Inhibitor of the Peroxidase-Mimic Catalytic Activity of 2-Dimensional Ni-Based Nanozymes

The ability to modulate the catalytic activity of inorganic nanozymes is of high interest. In particular, understanding the interactions of inhibitor molecules with nanozymes can bring them one step closer to the natural enzymes and has thus started to attract intense interest. To date, a few reversible inhibitors of the nanozyme activity have been reported. However, there are no reports of irreversible inhibitor molecules that can permanently inhibit the activity of nanozymes. In the current work, we show the ability of L-cysteine to act as an irreversible inhibitor to permanently block the nanozyme activity of 2-dimensional (2D) NiO nanosheets. Determination of the steady state kinetic parameters allowed us to obtain mechanistic insights into the catalytic inhibition process. Further, based on the irreversible catalytic inhibition capability of L-cysteine, we demonstrate a highly specific sensor for the detection of this biologically important molecule.

The Influence of Explicit Emotional Information on the Inhibition Process of Deceptive Response: Evidence from ERP

Deceptive response may be influenced by the individual’s internal emotional experience and external emotional information. Deception can bring nervous, fearful or even emotional experiences to the deceiver. The emotional experience can also affect deceptive behavior. Based on previous studies, this paper used facial expressions as a stimulus material, combined with explicit tasks, to study the impact of emotional information on the inhibition process of deceptive responses. The experiment adopted the emotional Stroop paradigm, used event-related potential to discuss the neural mechanism of the influence of explicit emotional information on deception. In the explicit task, it was found that high intensity triggered greater P300 amplitudes, high-intensity negative emotions triggered greater LPC amplitudes, and deceptive responses triggered greater N200, P300 and LPC amplitudes. These results show that in the explicit tasks, the impact of emotional information on fraudulent responses runs through the three stages of executive function. This is, inhibition stage, conflict and reaction monitoring stage and implementation stage. This study also found that negative emotion information had greater influence on deceptive response in explicit tasks.

A Potential Inhibition Process of Ricin Protein with the flavonoids Quercetin and Epigallocatechin Gallate. A Quantum-Chemical and Molecular Docking Study

Castor bean (Ricinus Communis) oil has been reported as one of the most important bio-based fuels; however, high amounts of toxic solid residue are generated in the production. This toxicity is due to several molecules, ricin protein being the most studied compound. The inhibition of the ricin protein is essential for eliminating its toxicity. The objective of this study is to predict the possible inhibition process via the interactions between the ricin protein and the flavonoids quercetin (Q) and epigallocatechin gallate (EGCG). The molecular structures of the complexes formed between the ricin protein and flavonoids were studied using quantum-chemical and molecular docking calculations to analyze the type of interaction, active site of the protein, binding energies, and different conformations in the inhibition process. Different methodologies were applied for the molecular structure determination; the best approximation was obtained with B3LYP/6-31G (d,p) theoretical methodology. Mappings of electrostatic potential (MEP) and frontier molecular orbitals were used for the identification of the probable sites of interaction, which were confirmed by molecular docking. The adjustment and alignment of flavonoid groups before and after the interaction, and charge transfer parameters, showed that Q and EGCG act as electron donors inside of the active site in ricin.

Conocarpus Erectus Extract as an Eco-Friendly Corrosion Inhibitor for Aluminum in Hydrochloric Acid Solution

Conocarpus Erectus extract was examined as a green corrosion inhibitor for Al in 1 M HCl and evaluated by different methods (chemical & electrochemical methods). Surface checks were used to illustrate the importance of this green extract to Al's corrosion inhibition process. The inhibition efficiency (%IE) increased with the raising of both Conocarpus Erectus extract dose and temperature, indicating that this extract was adsorbed chemically on Al surface. The %IE was 91.1% when the concentration Conocarpus Erectus extract was 300 ppm. Conocarpus Erectus extract inhibits both anodic and cathodic reactions, so it is a mixed kind inhibitor. The %IE of Al occurs by the adsorption process, and this metal is subject to the adsorption, according to Temkin isotherm. The surface examination was detected by utilizing a scanning electron microscope (SEM). The outcome data obtained from all experimental studies are excellent and proved the effectiveness of Conocarpus Erectus extract for Al's corrosion resistance.

Theoretical Insights into the Effect of Halogenated Substituent on the Electronic Structure and Spectroscopic Properties of the Favipiravir Tautomeric Forms and Its Implications on the Treatment of COVID-19

<p>In this study, we systematically investigated the electronic structure, spectroscopic (nuclear magnetic resonance, infrared, Raman, electron ionization mass spectrometry, UV-Vis, circular dichroism, and emission) properties, and tautomerism of halogenated favipiravir compounds (fluorine, chlorine, and bromine) from a computational perspective. Additionally, the effects of hydration on the proton transfer mechanism of the tautomeric forms of the halogenated favipiravir compounds are discussed. Our results suggest that spectroscopic properties allow for the elucidation of such tautomeric forms. As is well-known, the favipiravir compound has excellent antiviral properties and hence was recently tested for the treatment of new coronavirus (SARS-CoV-2). Through in silico modeling, in the current study, we evaluate the role of such tautomeric forms in order to consider the effect of drug-metabolism into the inhibition process of the main protease (M^pro) and RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 virus. These findings clearly indicated that all title compounds are better as RNA-inhibiting.</p>

Theoretical Insights into the Effect of Halogenated Substituent on the Electronic Structure and Spectroscopic Properties of the Favipiravir Tautomeric Forms and Its Implications on the Treatment of COVID-19

<p>In this study, we systematically investigated the electronic structure, spectroscopic (nuclear magnetic resonance, infrared, Raman, electron ionization mass spectrometry, UV-Vis, circular dichroism, and emission) properties, and tautomerism of halogenated favipiravir compounds (fluorine, chlorine, and bromine) from a computational perspective. Additionally, the effects of hydration on the proton transfer mechanism of the tautomeric forms of the halogenated favipiravir compounds are discussed. Our results suggest that spectroscopic properties allow for the elucidation of such tautomeric forms. As is well-known, the favipiravir compound has excellent antiviral properties and hence was recently tested for the treatment of new coronavirus (SARS-CoV-2). Through in silico modeling, in the current study, we evaluate the role of such tautomeric forms in order to consider the effect of drug-metabolism into the inhibition process of the main protease (M^pro) and RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 virus. These findings clearly indicated that all title compounds are better as RNA-inhibiting.</p>