Spectroscopy Methods Research Articles

Background: Hemorrhagic shock remains a leading cause of preventable death. No artificial oxygen carrier based on hemoglobin or hemoproteins has been approved in the US as an alternative to donated blood. A major challenge for the hemoprotein oxygen carrier is the vasoconstrictive effects due to the nitric oxide (NO) scavenging. We have engineered a modified Regulator of Carbon Monoxide Metabolism (RcoM) heme-containing protein which shows no vasoconstrictive effects. We aim to validate the oxygen binding, NO dioxygenation rate, stability, and resuscitative effects of RcoM. Hypothesis: We hypothesize that RcoM is well tolerated and can behave as an artificial oxygen carrier due to ideal oxygen binding rate, low autoxidation rate, slow NO dioxygenation rate, and high thermal/chemical stability. Approach: We assessed biochemical features using UV-visible spectroscopy methods to determine the transitions between RcoM oxidation state and ligand binding and dissociation. We performed measures of oxygen binding and autoxidation. We carried out competition experiments in which equimolar amounts of RcoM and Hb were exposed to NO to measure NO deoxygenation rate. To assess oxygen carrier capabilities of Rcom, we used a murine model of traumatic, hemorrhagic shock utilizing anesthetized mice with a 2cm abdominal incision and left femoral artery and vein catheterization. Hemorrhage was induced by a 30-minute controlled bleeding to a target blood pressure of 25 to 40 mmHg, shock was maintained for 30 minutes, then infusion by lactated Ringer (LR) solution, 2mM stroma-free Hb, or 2mM RcoM at volume equal to removed blood and monitored for 30 minutes. Mean arterial pressure post resuscitation were compared to assess the tolerance and hemodynamics effects. Results: RcoM displays appropriate oxygen binding capacity and has an NO deoxygenation rate ten-fold lower than Hb. In the murine hemorrhagic model, there was no difference for the baseline MAP or in blood removed during the bleeding phase. Post-resuscitation MAP was significantly higher for RcoM (67.0 ± 6.3 mmHg) and Hb (60.4 ± 16.0 mmHg) compared to LR (25.9 ± 21.4 mmHg, p = 0.0029). There was no difference between Rcom and Hb in the post-resuscitation MAP ( p = 0.8573). Conclusion: This study demonstrates that resuscitation with RcoM supports the blood pressure in a murine traumatic hemorrhagic shock model, suggesting its potential application as a non-globin artificial oxygen carrier for hemorrhagic shock.

Isoprene, the most abundant endogenous hydrocarbon in human breath, is a promising biomarker for metabolic and cardiovascular diseases. In this paper, we present the detection of isoprene in exhaled breath using the off-beam Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) method. The sensor employs a homemade quantum cascade laser emitting at 11.03m. We use numerical simulations to evaluate the impact of interfering gases (CO2 and H2O) and optimize the laser modulation parameters. The limit of detection reached for 1 s acquisition time is close to 220 parts per billion in volume (ppbv) with a normalized noise equivalent absorption (NNEA) of 1.1×10−8cm−1·W·Hz−1/2. Breath measurements conducted on healthy volunteers reveal a significant increase in isoprene concentration from resting levels (~250–350 ppbv) to elevated levels (~450–650 ppbv) after moderate physical exercise.

A high-precision multi-channel rapid detection method for dynamic and static impedance spectroscopy of lithium batteries based on programmable current excitation

A spectroscopic real-time characterization method of material removal efficiency in water jet guided laser machining technology

This study involved the preparation of a new nanopolymer with outstanding environmental properties and high stability. The polymer was manufactured through a copolymerization process involving hydrophilic and hydrophobic monomers. The starting materials used were acrylic acid (AA), methyl cellulose (MC), and polylactic acid (PLA).To achieve the nanopolymerization, a free-radical photopolymerization method was employed. This process involved the polymerization of methyl cellulose, acrylic acid, and polylactic acid, with 1,6-hexanediol diacrylate (HDODA) as a cross-linking agent and 1-hydroxycyclohexylphenyl ketone as a photoinitiator.The resulting nanopolymer combines the properties of the starting materials, demonstrating its high environmental friendliness and structural stability. This makes it a promising candidate for applications requiring high-performance and sustainable materials. The nanopolymer was characterized using FTIR, TGA, DSC, SEM, and TEM techniques. The swelling ratio of this polymer was measured as a type of gel polymer. The study applied the nanopolymer to the spectroscopic determination of lead(II) ions. The optimal conditions for the determination process were determined, such as determining the wavelength of maximum absorption. A spectroscopic reference method was used to calculate the remaining ion using a new standard method for estimating the ion is characterized by the use of the reagent (2-[(6-Methoxy-2-benzothiazolyl) azo]-4-methoxyphenol) 6-MBTAMP at a wavelength of 670 nm, pH 7, reagent volume of 0.5 ml, and ion volume of 2 ml. A standard calibration curve for the lead(II) complex was also prepared before adsorption. Studying the best conditions for the adsorption process and estimating the effect of pH, shaking time, mass of the adsorbed surface, and volume of the ion solution on the adsorption process. A calibration curve was also prepared after the adsorption process to estimate the remaining lead(II) ions. Linearity range was 0.5 to 10 mg.L-1, and Sandell's sensitivity was 0.1666 µg.cm-2, molar absorptivity( Ƹ ) was 1.2432×103L.mol-1.cm-1.

Understanding the mechanisms of enantiomer binding and recognition with cyclodextrins by integrating capillary electrophoresis, nuclear magnetic resonance and quantum mechanics.

Spectroscopic method for measuring activity of cis-aconitate decarboxylase, an important metabolic regulator of immune responses.

Achieving anodic stripping voltammetric detection of aluminum via Zn-assisted g-C3N4-modified sensor system.

Hybrid artificial intelligence approaches and bioimpedance spectroscopy for classifying pancreatic disease.

A dinitrogen-bridged diruthenium complex bearing 2,6-pyridine-dicarboxylate (pydc2-), which coordinates in a κ2-ON bidentate mode, with ammine and hydroxido ligands has been synthesized by reactions of ruthenium(III) and/or ruthenium(II) complexes with hydrazine or dinitrogen as a dinitrogen source. A reaction of the diruthenium complex with pyridine affords a pyridine-substituted diruthenium complex. The electronic structures of the diruthenium complexes in a mixed-valence state have been investigated using UV-vis-NIR and IR spectroscopy and electrochemical methods.

11H-Indeno[2,1-a]azulenes were efficiently synthesized via the [8 + 2] cycloaddition of 2H-cyclohepta[b]furan-2-ones with the enamines generated from several 1-indanones. Subsequent transformations included halogenation, cross-coupling, oxidation, and/or Knoevenagel condensation to furnish the azulene-fused dicyanobenzofulvenes (DBFs). Comprehensive characterization was accomplished through single-crystal X-ray analysis, UV/vis absorption, fluorescence spectroscopy, and electrochemical methods. The DBFs exhibited pronounced absorption in the visible region, attributed to their donor-acceptor structures. Furthermore, notable halochromic behavior and fluorescence were observed in acidic media for 11H-indeno[2,1-a]azulenes, while the DBFs demonstrated distinct electrochromic properties with reversible spectral changes under the electrochemical redox conditions. Computational nucleus-independent chemical shift (NICS) calculations suggested weak antiaromaticity in the dicyanofulvene moiety of the DBFs.

The purpose of this study was to develop a reliable, rapid and sensitive method based on Ultra Violet spectroscopy (UV) for the determination of an anti-diabetic drug Linagliptin (LIN) in its pure form as well as in its pharmaceutical dosage forms. Different solvent blends were screened to select solvent blend which suits for the study. The solvent blend selected was comprising of Acetonitrile: Methanol: DW at 1:1:1 and same was used for the development, validation and quantification of LIN. The results show the linearity in the concentration range (1-50 µg/mL) with correlation coefficient R2 = 0.9999 with percent recovery (100 – 100.3 %) with RSD was less than 2%, LOD and LOQ 0.05657, 0.1714 µg/mL respectively. This method can show high quality and there is no significant interference with the excipients and in pharmaceutical forms. None of the studies showed the development of this method before.

Identifying reaction coordinates is a central challenge across all fields of chemistry. While the advancement of femtosecond spectroscopic techniques has enabled direct identification of reaction coordinates in ultrafast processes, new experimental or analytical approaches are required to access such information in photoinitiated processes of broader interest. In this study, we theoretically demonstrate a spectroscopic method capable of identifying vibrational modes with potential reactivities in non-reactive photochemical and photophysical systems. The method is based on femtosecond transient absorption spectroscopy and leverages the polarization dependence in wavepacket propagation arising from the position-dependent electronic character within the Born-Oppenheimer approximation. The vibrational wavepacket associated with the reactive mode exhibited clear dependencies on both polarization and detection frequency, whereas the non-reactive mode showed only weak polarization dependence. This contrast highlights a fundamental distinction between reactive and non-reactive modes in terms of their polarization-sensitive spectral responses. Leveraging this property, it may be possible to extract reaction coordinate information even for general photochemical and photophysical processes.

Based on readily available initial reagents, boron-containing compounds of various composition and structure have been synthesized. Hydroxymethyl esters of xanthogen, dithiophosphoric acids, hydroxymethylsulfamide and dialkyl esters of boric acid were used as initial reagents. As a result of the work done, a number of boron- and boron-nitrogen-containing compounds have been synthesized. The structure and composition of the synthesized compounds have been proven by studying their physicochemical properties, elemental analysis, and IR spectroscopy and gas chromatography (GLC) methods. A study of the tribological characteristics of S-(dialkyloxyboryl)xanthates and -diisopropyldithiophosphate in MS-20 aviation oil has established their high anti-seize efficiency, and the derivative of diisopropyldithiophosphoric acid is also characterized by anti-wear properties. The dependence of the extreme pressure properties of the synthesized compounds in the series of S-(dialkyloxyboryl)xanthates on the radical value in dialkyl esters of boric acid was revealed. A higher extreme pressure efficiency of the boron-containing ester of dithiphosphoric acid was shown compared to the ester of xanthic acid of a similar structure. Due to limited solubility in mineral oils, dibutoxyboryltoluenesulfamide was investigated as an antimicrobial additive in water-soluble cutting fluids (CFL). Analysis of the obtained results showed their high efficiency in this area of application

The structure and composition of the nanocomposite based on the mixture of natural polyamide base and FeO filler, some physico-chemical properties were studied using elemental analysis, IR-spectroscopy, X-ray phase analysis, quantum-chemical calculations, thermal analysis, UV spectrosco-py methods. Studies were conducted to study the chemical composition of the initial components and compositions. The mole ratio of polyamide and iron particles filled into it was determined. Based on the results of thermal analysis, the liquefaction, decomposition temperatures and thermal stability of the composite were studied. Changes in vibration frequencies of carbonyl and amino groups in the polyamide base were observed with the help of the obtained IR-spectra. It was found that the stabilization of FeO polyamide by base occurs through these groups

This article provides information on the medical use of certain medicinal plants of the Lamiaceae family, as well as on compounds found in essential oils derived from them. The study used natural and artificial methods of drying, extraction, chromatographic methods (TLC, CC), UV spectroscopy methods, and the samples obtained were tested for gram-positive and gram-negative bacteria to determine antimicrobial activity in vitro. Plants that have shown high activity are later used as raw materials for the production of antibiotics.

Corrosion of oil and gas equipment, in particular oil field and tubing, is one of the most common complicating factors in oil production. One of the most common, effective methods of preventing corrosion of tubing is the use of internal protective anti-corrosion coatings. An urgent task is to control the quality of internal anti-corrosion coatings, predict the life of the coating in oil production conditions. When choosing protective coatings suitable for operating conditions, the main criterion is resistance to pipeline operating conditions — operating temperature, pressure, chemical composition of the flowing medium. The optimal laboratory method for reproducing operating conditions in a well (high temperature, high pressure, mineralized medium with dissolved corrosive gases) is the method for conducting autoclave tests of coatings, which is included in the domestic industry standard GOST R 58346-2019 National Standard of the Russian Federation. Steel pipes and fittings for the petroleum industry. Protective paint coatings of internal surface. General technical requirements. «Despite the fact that there are successes in the domestic oil and gas industry in the formation of a regulatory framework used to control the quality of coatings, the addition of existing test methods with new methods is still relevant. This article will propose a method for testing pipe products with internal protective coatings using the «High-pressure electrochemical cell for testing anti-corrosion protective coatings applied to the inner surface of tubing» developed by the authors of this article. This method combines the advantages of the autoclave test method and the electrochemical impedance spectroscopy method and allows you to assess the state of the protective coating directly during the autoclave test on the principle of «in situ» (translated from lat. — «in place»). Potentially, the application of the «High Pressure Electrochemical Cell for Testing Anticorrosive Protective Coatings Applied to the Inner Surface of Tubing, in combination with existing methods for testing protective coatings, could be used to predict the lifetime of protective coatings.

Transient or time-resolved electron paramagnetic resonance spectroscopy (TR EPR) is a powerful method for studying various photogenerated paramagnetic species. The use of low-energy quanta, such as terahertz (THz) radiation, as an external stimulus in TR EPR allows the initiation of spin dynamics without generating new paramagnetic species other than those already present in the system. This spin dynamic reflects the return of the system to thermodynamic equilibrium, governed by a spin-lattice relaxation time, T1. The latter, together with a phase memory time, is of paramount importance for the practical implementation of single-molecule magnets and molecular spin qubits. In this work, we present TR EPR spectroscopy with pulsed heating by THz pulses as a versatile spectroscopic method for determining T1 in a wide range of paramagnetic systems. To define the scope of the method, we developed a numerical model based on the Liouville-von Neumann equation, with the equilibrium density matrix defined by the temperature profile of the lattice. Using experimental data obtained for [CoTp2] (cobalt(II) bis[tris(pyrazolyl)borate]) with S = 3/2, we compared the proposed method with two other commonly used techniques: alternating current (AC) magnetometry and pulsed EPR. All three methods were found to be in qualitative agreement and provided complementary information about the relaxation properties. TR EPR spectroscopy showed the orientation dependence of T1. AC magnetometry revealed the dependence of T1 on the value of the external magnetic field, which was attributed in the literature to a field-induced Raman process. Finally, pulsed EPR spectroscopy was found to be biased by strong spectral diffusion.

This study investigates the corrosion inhibition performance of a novel C4-substituted pyrazolone-based heterocyclic compound, namely 3-(5-methyl-3-oxo-2,3-dihydro-1H-pyrazol-4-yl)-3-phenylpropanoic acid (C4-PRZ-1), on mild steel (MS) in a 1 M hydrochloric acid (HCl) environment. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods were employed to evaluate the inhibitor's protective capabilities. The effects of varying inhibitor concentrations and temperature on inhibition efficiency were systematically examined. Results demonstrated that increasing the inhibitor concentration improved corrosion protection, with a maximum efficiency of 85% observed at 5.0 mM. Furthermore, raising the temperature from 298 to 328 K caused a decrease in the inhibitive efficiency of the examined compound. The adsorption behavior of C4-PRZ-1 on the MS surface followed the Langmuir's isotherm model. Thermodynamic parameters associated with the adsorption process were determined to provide further insight into the inhibition mechanism. Surface morphology and elemental composition analyses using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) confirmed the formation of a protective film on the steel surface. Additionally, density functional theory (DFT) calculations were conducted to explore the electronic interactions, particularly the charge transfer between chloride ions and the steel substrate. Monte Carlo simulations, in conjunction with simulated annealing algorithms (SAA) and adsorption locator techniques, further elucidated the molecular interactions between the inhibitor and the metal surface, supporting the experimental findings.

In the contemporary world, the problem of human psychological health is growing in extremely huge scales. However, the reason of this extreme growth is not always hidden under disorders of some centers in the neocortex. Very frequently, there occur deviations, concerning to the information transition pathways between different centers of human brain. Here is discussed the possibility to monitor dopamine in human organism from the point of diagnosis of number of neurodegenerative diseases. Creation of biosensor for dopamine on the basis of nucleic acids, which will serve as an underlayer – sensitive to dopamine, is considered one of the possible variants of the monitoring. In the present paper, is was studied the complexes of dopamine with DNA by the spectral (absorption, fluorescence) methods, in the presence of intercalating compounds acridine orange (AO) and ethidium bromide (EtBr). The results revealed a competitive binding of dopamine and intercalator to DNA. It leads to the decreasing of EtBr and AO affinity decrease to DNA. Besides, it was studied the interaction of dopamine with single-stranded synthetic polynucleotide poly(rA) which is considered to be a potential underlayer, interacting with dopamine. The dopamine binding constant to DNA, RNA and single-stranded homopolynucleotides, especially poly(rA) is determined experimentally by the method of absorption spectroscopy. The data show that dopamine interacts with poly(rA) and the affinity to poly(rA) is significant. Between these two compounds, there exists some affinity, which can be used as an underlayer for the construction of biosensor for the concentration determination of dopamine in blood plasma and urine. Based on the experimental data, we assume that in the given work the following position is new: the dopamine concentration may be determined in the blood and urine, which makes possible to assess the probability of the initiating neurodegenerative disease and to facilitate the disease symptoms.