Isopropanol Solution Research Articles

Hydrolysis of 2D Transition-Metal Carbides (MXenes) in Colloidal Solutions.

Although oxidation was deemed as the main factor responsible for the instability of MXenes in aqueous colloids, here we put forward and test a hypothesis about the central role of water as the primary factor. We show that water and related processes of MXene hydrolysis play the main role in the phenomena leading to complete transformations of 2D titanium carbide MXenes into titania in aqueous environments. To demonstrate the role of water, the stability of two MXenes, Ti3C2T x and Ti2CT x, has been systematically studied in aqueous and nonaqueous colloids exposed to oxygen and inert gas atmospheres. The calculated time constant for degradation of Ti3C2T x dispersed in anhydrous iso-propanol saturated with pure oxygen exceeds 5 years, in striking contrast to the same MXene dispersed in water, where more than a half of it would transform into titania even in an oxygen-less atmosphere over ∼41 days. A thinner Ti2CT x MXene showed similar behavior, albeit with shorter time constants in both solvents, correspondingly. UV-vis and Raman spectroscopy were used to analyze the oxidation kinetics and composition of fresh and aged MXenes. An intense anatase peak was observed in MXenes stored in aqueous solutions under Ar atmosphere, while no signs of oxidation could be found in iso-propanol solutions of the MXenes stored under O2 atmosphere over a similar period of time.

High-performance polyamide/ceramic hollow fiber TFC membranes with TiO2 interlayer for pervaporation dehydration of isopropanol solution

To improve the pervaporation (PV) performance of isopropanol (IPA) dehydration, polyamide (PA) thin-film composite (TFC) membranes were fabricated by interfacial polymerization (IP) of 1,3-diaminopropane (DAPE) and trimesoyl chloride (TMC) on the surface of TiO2 modified ceramic hollow fiber (CHF) substrate. The TiO2 interlayer prepared by the sol-gel method completely cover the rough and macroporous surface of the α-Al2O3 hollow fiber, providing relatively smooth and intact surface but also abundant electrostatic sites (hydroxyl) for better IP. The PA layer prepared on the TiO2 interlayer is thinner, defect-free and exhibited higher smoothness and cross-linking degree than that on the original CHF support. The effects of monomer concentration, immersion time in aqueous phase and contact time of TMC solution were also investigated. The TFC membrane prepared under optimum conditions exhibited the outstanding PV separation index (PSI) value of 7.83 × 107 with separation factor above 12,000 and the permeate flux nearly 6.44 kg/m2 h for PV dehydration of 90 wt% IPA at 60 °C. After 100 h of long-term operation, the PV membrane maintains the high separation performance. This TFC membrane prepared by an effective and simple method provides an alternative for designing high-performance PV membrane in organics dehydration.

Self-Assembled Fullerene Crystals as Excellent Aromatic Vapor Sensors.

Here we report the aromatic vapor sensing performance of bitter melon shaped nanoporous fullerene C60 crystals that are self-assembled at a liquid-liquid interface between isopropyl alcohol and C60 solution in dodecylbenzene at 25 °C. Average length and center diameter of the crystals were ca. 10 μm and ~2 μm, respectively. Powder X-ray diffraction pattern (pXRD) confirmed a face-centered cubic (fcc) structure with cell dimension ca. a = 1.4272 nm, and V = 2.907 nm3, which is similar to that of the pristine fullerene C60. Transmission electron microscopy (TEM) confirmed the presence of a nanoporous structure. Quartz crystal microbalance (QCM) results showed that the bitter melon shaped nanoporous C60 performs as an excellent sensing system, particularly for aromatic vapors, due to their easy diffusion through the porous architecture and strong π–π interactions with the sp2-carbon.

Модификация поверхностных свойств эпитаксиальных слоев PbSnTe<In> с составом вблизи инверсии зон

AbstractHigh-resistance Pb_1 –_ x Sn_ x Te〈In〉 layers grown by molecular beam epitaxy on BaF_2(111) substrates with compositions close to band inversion have been investigated. The I–V characteristics and relaxation dependences of the photocurrent of the structures in dependence on the chemical surface treatment and subsequent exposure of the samples in air have been examined. It has been observed that the characteristics significantly transform depending on the physicochemical surface state. It has been found that the chemical surface treatment in the hydrochloric acid solution in isopropyl alcohol leads to an increase in the current by up to four orders of magnitude with the subsequent recovery of the I–V characteristics upon exposure of the samples in air for several days.

Эволюция физико-химических свойств поверхности GaSb(100) в растворах сульфида аммония

AbstractVarious conditions of passivation of the GaSb(100) surface by ammonium sulfide ((NH_4)_2S) solutions depending on the solution concentration, solvent, and treatment time are investigated by X-ray photoelectron spectroscopy and atomic-force microscopy. It is shown that treatment of the GaSb(100) surface by any (NH_4)_2S solution leads to removal of the native oxide layer from the semiconductor surface and the formation of a passivating layer consisting of various gallium and antimony sulfides and oxides. The surface with the lowest roughness (RMS = 0.85 nm) is formed after semiconductor treatment with 4% aqueous ammonium sulfide solution for 30 min. Herewith, the atomic concentration ratio Ga/Sb at the surface is ~2. It is also found that aqueous ammonium sulfide solutions do not react with elemental antimony incorporated into the native-oxide layer. The latter causes a leakage current and Fermi-level pinning at the GaSb(100) surface. However, a 4% (NH_4)_2S solution in isopropanol removes elemental antimony almost completely; herewith, the semiconductor surface remains stoichiometric if a treatment duration is up to 13 min.

Photocatalytic gypsum plasters – studies of air cleaning properties and selected technical parameters

This study aims to investigate the feasibility of using industrial waste plastics, polypropylene (PP), polyethylene (PE) and polyamide (PA), obtained from recycling factory, as reinforcement for mortar. As one of the main problems of using waste plastics in cementitious composites is the hydrophobic properties of the sur- face of the plastics, because it prevents the formation of adequate interfacial adhesion with cement paste. Surface treatment of waste plastics was applied using diluted solution of isopropanol. Three parameters were considered when designing the mortar mixtures; type of waste plastic (PP, PE, PA), their addition ratio and surface treatment. Bending and compression tests were conducted. 1.5% volume addition of PP and PE to mortars the flexural strength was increased, however, surface treatment of waste plastics did not affected this strength. As the waste plastic volume ratio increased, the flexural toughness of mortars reinforced with PP, PE and PA plastics was also increased. For the 1.5% volume ratio, there was the increase of flexural toughness with respect to the reference mortar and the highest influence had the PP. For the untreated waste plastics, there was significant increase in flexural toughness, while reduction in the compressive strength and compressive toughness was found, however, this surface treatment enhanced the compressive strength and compressive toughness with respect to untreated plastics. Waste plastics can be used for mortars and concretes reinforcement to improve the ductility and energy absorption capacity while eliminating pollution and regaining them in the economy as a structural material.

Solvent-based bonding of PMMA–PMMA for microfluidic applications

Solvent bonding is a simple, inexpensive and quick technique used for joining microfluidic parts made of thermoplastic polymers that results in high bonding strength and good optical clarity. However, selecting the right solvent as well as the curing conditions is an important step in providing a successful bond that ensures an appropriate bonding without squeeze-out and clogging of microchannels. In this study, different solvent mixtures and solvent phases (i.e., liquid vs. vapor), as well as a range of curing times and temperatures, were tested to bond poly(methyl methacrylate) samples. Additionally, effect of corona surface modification was also examined on bonding quality. Results were compared in terms of bonding strength and optical clarity. A solvent mixture of 20% dichloromethane and 80% isopropanol showed the greatest bonding strength (4.2 MPa, based on tensile test), while vaporized dichloromethane had the best optical clarity (only 2.22% reduction in power transmittance). Coronal surface modification also showed a 25% increase in bonding strength and 2% improvement on optical clarity, for 20% dichloromethane and 80% isopropanol solution at room temperature and curing time of 15 min.

Dimethyl sulfoxide and bromide methylamine co-treatment inducing defect healing for effective and stable perovskite solar cells

The morphology of the perovskite film is one of the decisive factors for high-efficiency perovskite solar cells. This work fabricates the compact and high-coveraged perovskite film by using the isopropanol solution dissolved with the dimethyl sulfoxide and bromide methylamine to process the as-prepared perovskite films. The dimethyl sulfoxide can dissolve the perovskite grains and retard the grain reconstruction rate. The bromide methylamine can widen the band gap and improve the device performances by alternating the compositions to form the stable cubic phase perovskite.

Modification of Nafion membrane by polyaniline providing uniform polymer distribution throughout the membrane

Oxidative polymerization of aniline in the presence of Nafion membranes has been carried out in a water–isopropanol mixture after preliminary impregnation of the membrane with the monomer (aniline) in aqueous isopropanol. Uniform distribution of polyaniline (PANI) throughout whole membrane volume has been found. On the contrary, aniline polymerization in water, even after preliminary impregnation of the membrane with the monomer, has resulted in the formation of PANI thin layer only on the membrane surfaces but not inside the membrane. The polymerization in water–isopropanol mixture has not led to the change in the membrane surface properties but has induced the structural reorganization of Nafion membrane accompanied by the increase in the membrane ionic cluster size and the distance between the fluorocarbon crystallites. Modification by PANI carried out either in water or in aqueous isopropanol solution has resulted in the decrease in the membrane proton conductivity by 5–10 times.

An influence of Al2O3 nanoparticles on the caloric properties and parameters of the phase transition of isopropyl alcohol in solid phase

In present paper we investigated the influence of Al2O3 nanoparticles on the specific heat capacity of isopropyl alcohol in the temperature range 80–186 K. The measurements of the specific heat capacity were performed by an adiabatic calorimeter. It was found that below the melting temperatures the solution of isopropyl alcohol with Al2O3 nanoparticles can be in crystalline, glassy and liquid metastable states. The presence of Al2O3 nanoparticles in isopropyl alcohol leads to a decrease of the specific heat capacity and the enthalpy of phase transitions “crystalline state – liquid” and “glassy state – liquid metastable state”. It was demonstrated that not only presence of the nanoparticles but also the existence of the adsorbed interfacial phase from the molecules of the base liquid around the nanoparticles decreases the isopropyl alcohol melting heat. Based on obtained experimental data for the melting heat of the nanofluids of isopropyl alcohol/Al2O3 the mass fraction of the base fluid in the interfacial phase and the mean equivalent radius of nanoparticles with interfacial phase have been determined at the melting point.

Two polymorphs of 2-(prop-2-yn-1-yl-oxy)naphthalene-1,4-dione: solvent-dependent crystallization.

The title compound, C13H8O3, crystallizes in two polymorphs, namely the monoclinic (space group P21/c) and triclinic (space group Pī) forms, obtained from N,N-di-methyl-formamide and isopropyl alcohol solutions, respectively. The mol-ecular structures and conformations in the two forms are essentially the same as each other. The naphtho-quinone ring systems are essentially planar with r.m.s. deviations of 0.015 and 0.029 Å for the monoclinic and triclinic forms, respectively. The O-propargyl groups are coplanar with the naphtho-quinone units with r.m.s deviations ranging from 0.04 to 0.09 Å. In the monoclinic crystal, mol-ecules are linked via pairs of C-H⋯O hydrogen bonds, forming a tape structure running along [120]. The tapes are further linked by a C-H⋯π inter-action into a layer parallel to the ab plane. Adjacent layers are linked by another C-H⋯π inter-action. In the triclinic crystal, mol-ecules are linked via C-H⋯O and π-π inter-actions, forming a layer parallel to the ab plane. Adjacent layers are linked by a C-H⋯π inter-action.

ANTIHYPERGLYCEMIC ACTIVITY OF TINOCRISPOSIDE BY STIMULATING 3T3-L1 ADIPOCYTE CELL DIFFERENTIATION

Objective: The aim of this study is to investigate the antihyperglycemic activity of tinocrisposide by stimulating 3T3-L1 adipocyte cell differentiation. Tinocrisposide is a furanoditerpene glycoside that was isolated from Tinospora crispa (Menispermaceae).Methods: Adipocyte cell differentiation activity of tinocrisposide in interval concentrations of 50, 25, 12.5, and 6.25 μg/ml has been investigated on 3T3-L1 cell line using insulin of 1 μg/ml as a positive and Dulbecco’s modified Eagle media (DMEM) as a negative control group. The effect of tinocrisposide was quantified with oil red O staining method by measuring an absorbance of lipid solution in isopropanol at a wavelength (λ) of 520 nm.Results: Tinocrisposide in the concentrations of 50, 25, 12.5, and 6.25 μg/ml insulin of 1 μg/ml and DMEM groups showed absorbance value of 0.7669, 0.7253, 0.6563, 0.6481, 0.954, and 0.2653, respectively. It was found that there was a significant difference statistically in lipid droplets accumulation among all groups (p<0.05) and tinocrisposide at a concentration of 50 μg/ml showed the highest lipid droplets accumulation in 3T3-L1 adipocyte cells.Conclusion: From the study, it could be concluded that tinocrisposide was able to stimulate the differentiation of adipocyte cell and had antihyperglycemic activity.

Asphaltenes Dissolution Mechanism Study by in Situ Raman Characterization of a Packed-Bed Microreactor with HZSM-5 Aluminosilicates

Asphaltenes, which are the most aromatic component of heavy oil, are responsible for the fouling and impairment in flow lines, wellbores, and other production facilities in the petroleum industry. Aromatic solvents such as xylenes are commonly used for the asphaltenes’ cleaning process. Understanding the mechanism of asphaltenes’ dissolution in aromatic solvents is significant for the development of a remediation strategy. The reduction of a reactor’s characteristic length scale leads to the decrease in experimental period while providing high-throughput information. Microfluidic systems with in situ spectroscopy is an excellent platform for time-effective studies of the molecular behavior of asphaltenes in simulated sandstone reservoirs. Here, we injected the HZSM-5 zeolite nanoparticles (707 nm aggregate–1 in isopropanol solution) with varying Al2O3/SiO2 ratios (from 0 to 1/26) into the quartz porous media to represent reservoirs with different characteristic acidity. In-line ultraviolet–visible light (...

Investigation of the 3D Printing Roughness Effect on the Performance of a Dielectric Rod Antenna

In this letter, the roughness effect of a three-dimensional (3-D) printed dielectric rod antenna is investigated. One of the issues of 3-D printing in microwave components and antennas is the limited printing resolution, which creates a surface roughness on printed devices and deteriorates the performance. The effect of surface roughness on the radiation characteristics and impedance matching of a dielectric rod antenna is studied. The roughness as a perturbation brings the antenna out of its optimum design by changing the E-field intensity alongside the rod. The whole antenna consisted of a coaxial to waveguide adapter and the dielectric rod is 3-D printed and the adaptor is dipped into a low viscosity solution of silver epoxy and isopropanol to coat a conductor layer on the inner surfaces of the waveguides. The fabrication method is cost effective and much easier than conventional methods.

Magneto-Optical Properties of the Magnetite-Graphene Oxide Composites in Organic Solvents.

Graphene oxide (GO) aqueous solutions are known to form liquid crystals that can switch in electric fields. Magnetic fields as external stimuli are inefficient toward GO because of its diamagnetic properties, and GO is known to be insoluble in most of the organic solvents. In this study, composites of GO with oleate-protected magnetite nanoparticles were prepared as stable colloid solutions in the mixed isopropanol-chloroform solvents. The structure of the composite particles and the optical properties of their solutions can be controlled by the ratio of the mixing parent components. The as-prepared solutions are highly responsive to external magnetic field. As the consequence, the optical transmission and the direction of light scattering can be efficiently manipulated. These systems pave the way for fabricating functional materials, such as magneto-optical switches, density-gradient materials, and micromotors. Solubility in nonpolar organic solvents broadens the scope of their potential applications.

High efficient hydrogen evolution over self-reproducible platinum photocatalyst

Abstract The current artificial photocatalysts often suffer from photocorrosion-induced irreversible damage and low efficiency. Here we report that under the UV irradiation of aqueous isopropanol solution, which photolysis to produce acetone and consume photoelectron in time and be oxidized to form acetone. And then the platinum nanoparticles can coordinate with product acetone on their surfaces to create a unique photocatalysis system for high efficient hydrogen evolution. In this system, the inherent close bonding between photoactive surface complexes and metallic platinum sites creates an efficient donor-acceptor system for charge transfer and leads to high efficiency, with hydrogen generation rate of 8.01 mmol⋅ h−1. Furthermore, in the presence of isopropanol the photoactive acetonyl-platinum complexes are generated reproducibly via a continuous isopropanol-to-acetone conversion and thus work sustainably. This finding indicates the possibility of artificially creating self-reproducible systems to drive photocatalytic reactions efficiently and robustly.

The response of the Intox EC/IR II to isopropanol and isopropanol/ethanol mixtures

The Intox EC/IR II was tested with isopropyl alcohol (IPA) solutions, and IPA and ethanol (EtOH) mixtures, at various concentrations to determine whether IPA contributes to, or produces, an apparent ethanol concentration (AEC). Two test modes were used – Subject Test, which has the interfering substance (IS) detection mechanism enabled and reports truncated results; and Quick Test, which reports untruncated results and does not detect IS. When testing IPA solutions alone, concentrations of 40 mg/dL (mg%) and above produced the IS status message while concentrations below 40 mg% produced numerical results in the Subject Test mode. With IPA alone, the IPA contribution to AEC was approximately half of the target IPA concentration. When IPA + EtOH mixtures were tested, all mixtures except one generated the IS status message. The one IPA + EtOH mixture, with 10 mg% IPA and 150 mg% target apparent EtOH, consistently produced numerical results in the Subject Test mode; however, the 10 mg% IPA in the mixture did not contribute to the AEC. This study showed that with the IS detection mechanism activated on the Intox EC/IR II, Subject Tests were aborted in instances where IPA would have contributed to the AEC and the AEC was 20 mg% or above.

Hydrothermally Synthesizing Nanospheres of Pd Loaded TiO2 for Photocatalytically Reducing CO2 in Isopropanol to Isopropyl Formate

Photocatalytic reduction of CO2 was carried out on villiform spherical catalysts of Pd-TiO2 in isopropanol solution. The catalysts were synthesized by hydrothermal method, their structures, morphologies and optical absorption properties were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis absorption spectroscopy (UV-vis). The photocatalytic activities with different loading amounts and morphologies were evaluated for determining the dominant effect and optimizing the catalyst preparation. Based on a villiform spherical TiO2 with the largest specific surface area in our experiments, we prepared a set of catalysts with various loading amounts of palladium and tested them by bubbling CO2 through the slurry of catalyst and isopropanol. The highest formation rate of isopropyl formate was 276.6 μmol/g·cat/h. Eventually we proposed the reaction mechanism.

Effects of mixed solvent on morphology of CH3NH3PbI3 absorption layers and photovoltaic performance of perovskite solar cells

In this paper, a two-step method is used to prepare a high-quality CH3NH3PbI3 layer for carbon-based hole conductor-free perovskite solar cells (PSCs). In the first step, the solvent for the PbI2/DMF solution is changed to a mixed solvent of N,N-dimethylformamide (DMF) with dimethyl sulfoxide (DMSO) from pure DMF solvent. This process requires 3.5 h for PbI2 films deposited from the PbI2/DMF solution to completely convert to perovskite in a methyl amine iodide (MAI)/iso-propyl alcohol (IPA) solution, and perovskite films have a rough surface with a few large crystals. This mixed solvent accelerates the conversion of PbI2 to CH3NH3PbI3, resulting in smooth CH3NH3PbI3 films without residual PbI2. Only 15 min are required for PbI2 films to completely convert to perovskite when the volume ratio of DMSO to DMF is 1:4. As a result, the photovoltaic performance, especially on the fill factor (FF) of PSCs fabricated from DMF/DMSO solvent, improved mainly due to the better contact of perovskite/carbon interface and faster charge transport of the perovskite layer.

A Fully Integrated Low-Power 30 GHz Complex Dielectric Sensor in a 0.25-$\mu$m BiCMOS Technology

This paper presents an integrated low-power dielectric sensor in K-band frequencies implemented in a $0.25 \mu \mathrm{m}$ SiGe BiCMOS process, including the sensing front-end and readout circuits. The sensor enables the measurement of both real and imaginary part of permittivity of the material under test (MUT). The MUT is exposed on the resonator component in a sensing oscillator, and the oscillator results in permittivity- and conductivity-dependent change in the output frequency and output power, respectively. The frequency information is translated into dc voltage using a frequency discriminator, and the output power is detected using a power detector. The sensor has been calibrated using iso-propanol, ethanediol, and acetone solutions. Methanol–ethanol mixture solutions, in steps of 25% of concentration change, have been used to demonstrate the functionality of the sensor. The selectivity is showed using methanol–ethanol mixtures with concentration differences of 5% around a mixture ratio of 50:50. The chip is $2.3 \text{mm}^{2}$ in size and consumes 60 mW power. The sensor measures complex permittivity within 3.7% accuracy for the real part and 4.3% for the imaginary part. As a compact and low-power solution, the sensor is a potential candidate for minimal invasive investigations of chemicals and bio-materials at mm-wave frequencies.