Absorption Spectroscopy Techniques Research Articles

Green Synthesis and Bioactivity of Aliphatic N-Substituted Glycine Derivatives.

Standard amino acids have an asymmetric α-carbon atom to which -COOH, -NH2, -H, and -R groups are bonded. Among them, glycine is the simplest (R = -H) with no asymmetric carbon, and other natural amino acids are C-substituted of glycine. Here, we have designed and made a green synthesis of some new N-substituted glycine derivatives with R-(NH)CH2-COOH formula, where R is flexible and hydrophobic with different chain lengths and benches of the type propyl, butyl, sec-butyl, tert-butyl, pentyl, isopentyl, tert-pentyl, hexyl, 2-aminoheptyl, and octyl. These glycine derivatives were characterized by recording their melting points and FT-IR, mass, 1H NMR, and 13C NMR spectra. DFT studies revealed that 2-aminoheptyl glycine had the highest electronegativity value and can thus act as a good bidentate ligand for the metal centers. ADME comparative results and bioavailability radars indicated that both octyl- and 2-aminoheptyl glycine had the most lipophilicity, making them good agents in cell passing. Furthermore, lipophilicity determination showed that octyl glycine was the best and propylgly was more soluble than others. Based on solubility, lipophilicity, and dipole moment values, propyl- and 2-aminoheptyl-glycine were considered for bio-macromolecular interaction studies. Thus, the interaction of these two agents with DNA and HSA was studied using absorption spectroscopy and circular dichroism techniques. Due to the presence of the R-amine group, they can interact with the DNA by H-binding and hydrophobicity, while electrostatic mode could not be ruled out. Meanwhile, molecular docking studies revealed that octyl- and 2-aminoheptyl glycine had the highest negative docking energy, which reflects their higher tendency to interact with DNA. The DNA binding affinity of two candidate AAs was determined by viscosity measurement and fluorescence emission recording, which confirms that groove binding occurs. Also, the toxicity of these synthesized amino acid derivates was tested against the human foreskin fibroblast (HFF) cell line. They showed IC50 values within the range of 127-344 μM after 48 h with the highest toxicity for 2-aminoheptyl glycine.

Exploring the pH-Responsive Interaction of β-Blocker Drug Propranolol with Biomimetic Micellar Media: Fluorescence and Electronic Absorption Studies.

Interaction of neutral and charged lipophilic beta-blocker drug, propranolol (PPL) with biomimicking nanocavities formed by micelles bearing same and opposite charges namely, cationic cetyltrimethylammonium bromide (CTAB), a surface-active ionic liquid 1-hexadecyl-3-methylimidazolium chloride (HDMIC) and anionic sodium dodecyl sulphate (SDS) have been investigated using fluorescence and absorption spectroscopic techniques. Binding of PPL to SDS at pH < pKa is characterised by biphasic interactions with decrease in fluorescence intensity at lower concentrations and subsequent increase post micellization. All the surfactants show significant interactions with the neutral drug molecule at pH > pKa, which is evident from the strongest binding constant ( ) values at pH 10.4. Results of quenching studies indicate that the location of drug molecule is determined by its charge, which is influenced by both pH and charge on micelle surface. For PPL-CTAB and PPL-HDMIC systems, quenching was strongest at pH 10.4, moderate at pH 7.4 and was absent at pH 3.5. However, the PPL-SDS system displayed similar values at all pH conditions, suggesting that the probe is at the same position regardless of pH. Non-covalent interactions, which play crucial role in biological systems, are similarly the primary driving force governing the interaction between PPL and surfactant micelles.

Thiocyanato and Schiff base coordinated mono/di-nuclear Ni(II) complexes: Syntheses, crystal structures and protein binding

Thiocyanato and Schiff base coordinated mono/di-nuclear Ni(II) complexes: Syntheses, crystal structures and protein binding

A mid‐infrared laser absorption sensor for calibration‐free measurement of nitric oxide in laminar premixed methane/ammonia cofired flames

Abstract An interband cascade laser (ICL)‐based absorption sensor was developed for calibration‐free and high‐fidelity measurement of nitric oxide (NO) in laminar premixed methane/ammonia cofired flames using a combination of a micro‐probe and a low‐pressure, high‐temperature gas cell. The developed sensor, which has been shown to be particularly suitable for kinetic studies of ammonia combustion, used a tunable, continuous, narrow‐linewidth, free‐space ICL operating at ~5.2 μm to target the optimal NO transition centered at 1900.07 cm−1. A direct absorption spectroscopy technique with a reduced line model was implemented for calibration‐free measurements. Comprehensive experiments were first conducted to evaluate the sensor performance against the standard gas mixture at varied pressure from 20 to 101 kPa at 393 K, showing a relative difference of ≤2.5% and a measurement uncertainty of ≤2.0%. Such a sensor shows a minimum detection limit of ~2 ppm at the integration time of 1 s. The sensor was then applied for investigating the NO formation in ammonia‐methane cofiring flames with various ammonia blending ratios; the acquired experimental data was further used as benchmark data for evaluation of literature chemical mechanisms for ammonia combustion. The developed sensor system was demonstrated to be capable of providing quantitative and spatially resolved measurement of NO in ammonia‐methane cofired flames.

Promising SnOx electron transport layer for polymer solar cells

Promising SnOx electron transport layer for polymer solar cells

Excited State Kinetics of Benzo[a]pyrene Is Affected by Oxygen and DNA

Benzo[a]pyrene is a widespread environmental pollutant and a strong carcinogen. It is important to understand its bio-toxicity and degradation mechanism. Herein, we studied the excited state dynamics of benzo[a]pyrene by using time-resolved fluorescence and transient absorption spectroscopic techniques. For the first time, it is identified that benzo[a]pyrene in its singlet excited state could react with oxygen, resulting in fluorescence quenching. Additionally, effective intersystem crossing can occur from its singlet state to the triplet state. Furthermore, the interaction between the excited benzo[a]pyrene and ct-DNA can be observed directly and charge transfer between benzo[a]pyrene and ct-DNA may be the reason. These results lay a foundation for further understanding of the carcinogenic mechanism of benzo[a]pyrene and provide insight into the photo-degradation mechanism of this molecule.

Ultrafast dynamics and relaxation pathways in Eu(III) complexes with fluorinated β–diketonate ligands

Ultrafast dynamics and relaxation pathways in Eu(III) complexes with fluorinated β–diketonate ligands

Intoxicação crônica por chumbo em uma onça pintada (Panthera onca) alvejada com projéteis de chumbo - relato de caso

ABSTRACT Lead is a heavy metal and an important cause of acute or chronic toxicosis in humans, domestic, and wild animals. This report aims to describe a case of chronic lead poisoning in a jaguar (Panthera onca) kept under human care that was rescued from the wild environment. The animal was rescued in poor condition in 2004 and kept under human care at the Belo Horizonte Zoological Garden (Minas Gerais, Brazil) until 2020, when it presented with anorexia, vomiting and ataxia. Over the past years the animal had episodes of anemia and increased serum urea and creatinine. Radiography demonstrated 21 radiopaque projectiles on the right side of the face. At necropsy there were multiple projectiles surrounded by fibrous tissue in the subcutaneous of the right side of the face, fibrinous peritonitis, multiple gastric ulcers, and melena. The lead dosage was performed using the atomic absorption spectrometry technique using renal tissue collected at necropsy, with a result of 908 ppb (µg/kg). The findings of projectiles associated with the dosage of lead above the reference limits allow the diagnosis of chronic intoxication in this case.

Contamination, ecological and health risk assessments of potentially toxic elements in soil around a municipal solid waste disposal facility in Southwestern Nigeria

Contamination, ecological and health risk assessments of potentially toxic elements in soil around a municipal solid waste disposal facility in Southwestern Nigeria

Sensitive carbon monoxide detection based on laser absorption spectroscopy with hollow‐core antiresonant fiber

Abstract A carbon monoxide (CO) sensing system based on hollow‐core antiresonant fiber (HC‐ARF) is developed using tunable diode laser absorption spectroscopy (TDLAS) technology. A HC‐ARF with length of 75 cm is applied as light transmission passage and gas chamber. Compared with conventional multipass cell, HC‐ARF has the advantages of compact volume, low cost, steady transmission, and simple optical alignment. Two techniques of direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS) were used respectively. In DAS, the minimum detection limit (MDL) was 12251.04 ppm. In WMS, the modulation depth of this HC‐ARF based CO‐TDLAS sensor was optimized to be 0.13 cm−1 and the R‐squared numeric of the linear relationship between the peak of the 2 f signal and the gas concentration was 0.99, indicating that the system has a nice linear responsiveness to the CO gas concentration. Finally, the MDL of the sensor was calculated to be 196.33 ppm.

Deciphering structural changes in LiNixMnyCozO2 cathodes of Li ion batteries during cycling: Experimental and theoretical investigations

Deciphering structural changes in LiNixMnyCozO2 cathodes of Li ion batteries during cycling: Experimental and theoretical investigations

Study of the Adsorption Efficacy of Cr(III) on a Metal Oxide-Based Material Derived from the Quartz Sand Enrichment Process

In the present study, the efficacy of chromium removal from water media was studied. For this purpose, a metal oxide based material, derived from the enrichment process of quartz coastal sand was used as possible adsorbent of chromium (III) ions. Following additional modification of the adsorbent, the effect of operational parameters including pH, contact time and Cr(III) concentration were studied according to one-factor-at-a-time procedure. Adsorption efficacy was assessed by the measurement of the remaining chromium concentration in solution, after adsorption. Atomic absorption spectroscopy technique, with flame atomization was used for the determination of chromium concentration in solution. Obtained results revealed that selected material exhibited higher adsorption efficacy in alkaline solution (pH = 6-9). The maximum removal efficacy (>93%) was achieved after 180 minutes of contact time, with an adsorbent dosage of 5 g/L and initial chromium concentration 20 mg/L. The adsorption process for Cr(III) follow the Freundlich isotherm and gives high correlation coefficient R². Calculations performed based on the Langmuir isotherm showed that the maximum adsorption efficiency of Cr³⁺ in the natural metal-oxide material has resulted 10 mg/g or 10000 μg/g. Pseudo second order reaction kinetics has provided a realistic description for removal of Cr(III) from solution with high correlation coefficient R² of (0.999). The adsorption isotherms were better described by the Freundlich equation (R² = 0.934). Adsorption of trivalent chromium ions onto selected material followed the pseudo second order model (R² = 0.996). Hence, the residual materials derived from the enrichment processes of quartz sand can be used as alternative adsorbent for the removal of trivalent chromium ions from aqueous solutions.

A new zinc(II) complex of 2-benzoimidazoledisulfide ligand: synthesis, X-ray crystallographic structure, investigation of CT-DNA and BSA interaction by spectroscopic techniques and molecular docking

A new zinc(II) complex of 2-benzoimidazoledisulfide ligand: synthesis, X-ray crystallographic structure, investigation of CT-DNA and BSA interaction by spectroscopic techniques and molecular docking

Rapid and Robust Analytical Method for the Determination of Copper Content in Commercial Pesticides and Antifouling Biocides

The quality control of the agrochemicals and biocidal products in the market requires valid determination methods for the active ingredient content and is of utmost interest to ensure environmental protection, human health, and successful pest control. Copper has been used as fungicide for centuries, and today is still in the market in hundreds of products for various uses and is applied in very high application rates, both in pesticides and biocides. The aim of the present study was to develop a new fast, efficient, and inexpensive analytical method for the determination of copper content in antifouling Product Type 21 (PT-21) biocides as well as in copper containing pesticides. The samples were oxidized by microwave-assisted acid digestion method and copper content was determined by flame atomic absorption spectrometry technique. The recoveries of the method ranged from 87.9% to 97.6% for antifouling paints, and 98.6% to 99.95% for pesticides, while the percentage Relative Standard Deviation (%RSD) was lower than 6% in all cases. The validated method Limit of Quantification (LOQ) was 5 μg mL−1 that was sufficient for the present analysis needs. As a result, it is concluded that the method is easily applicable and transferable, with reasonable consumption of reagents, characterized by high reliability and sensitivity; therefore, it is suitable for monitoring the levels of copper in antifouling products as well as pesticides containing copper as active substance.

Influence of the saturation effect on the Zeeman and hfs spectra

The technique of laser absorption spectroscopy is widely used in the study of the atomic structure. In order to thoroughly analyze the recorded structure of complex atoms, the effect of saturation must be taken into account. In the current paper we present a method of analysis of Zeeman and hyperfine structures spectra obtained with the use of laser spectroscopy, which allows to take into account the effect of saturation.Graphic abstract

Metal(loid)s in tap-water from schools in central Bangladesh (Mirpur): Source apportionment, water quality, and health risks appraisals

Considering the health risks originating from the exposure of metal(loid)s in tap-water and the concomitant vulnerability of school-going students, 25 composite tap water samples from different schools and colleges of central Bangladesh (Mirpur, Dhaka) were analyzed by atomic absorption spectroscopic technique. Elemental abundances of Na, Mg, K, Ca, Cr, Mn, Fe, Co, Ni, Zn, As, Cd, and Pb in the studied tap water samples varied from 4520 to 62250, 2760–29580, 210–3000, 15780–78130, 1.54–5.32, 7.00–196, 2.00–450, 0.04–1.45, 8.23–24.4, 0.10–813, 0.10–10.5, 0.002–0.212, and 1.55–15.8 μgL−1, respectively. Dissolved metal(loid)s' concentrations were mostly within the national and international threshold values with few exceptions which were also consistent with the entropy-based water quality assessment. Multivariate statistical approaches demonstrated that hydro-geochemical processes like water-rock interactions mostly govern the major elemental (Na, Mg, K, Ca) compositions in tap water. However, anthropogenic processes typically control the trace elemental compositions where supply pipeline scaling was identified as the major source. Cluster analysis on sampling sites separated two groups of schools and colleges depending on their establishment years where tap water from older schools and colleges possesses relatively higher levels of metal(loid)s. Hence, gradual pipeline scaling on a temporal scale augmented the metal(loid)s' concentrations in tap-water. In terms of non-carcinogenic health risks estimation, studied tap-water seems to be safe, whereas elemental abundances of Pb and As can cause carcinogenic risks to school-going people. However, progressive deterioration of water quality by pipeline scaling will be supposed to cause significant health risks in the future, for which preventative measures should be adopted.

Tuning the atomic configuration environment of MnN4 sites by Co cooperation for efficient oxygen reduction

Tuning the atomic configuration environment of MnN4 sites by Co cooperation for efficient oxygen reduction

Chemical characteristics of bottom ash from biomedical waste incinerators in Ghana.

Biomedical waste (BMW) incineration is the most used alternative disposal method in developing countries, such as Ghana. The improper disposal of incinerator-generated bottom ash (BA) is a significant concern due to the hazardous nature of waste. A study was conducted at Tema Hospital (TGH) and Asuogyaman Hospital (VRAH) incinerator sites. The BA samples were sent to the Council for Scientific and Industrial Research, Institute of Industrial Research, Ghana. The BA samples were weighed with fisher analytical balance, ground, and sieved with standard grade meshes of 120, 100, and 80 to determine the BA particle size distribution. The chemical composition and heavy metals were analysed using X-ray fluorescence spectrometry (XRF) and atomic absorption spectroscopy (AAS) techniques. The results indicated the chemical composition of the analysed BA samples was CaCO3 (49.90%), CaO (27.96%) and MgCO3 (6.02%) for TGH and CaCO3 (48.30%), CaO (27.07%), and SiO2 (6.10%) for VRAH, respectively. The mean concentration (M) (kg m-3) and standard deviation (SD) for TGH in the BA were 7.082 ± 0.478 (Ti), 4.657 ± 0.127 (Zn) and 4.271 ± 1.263 (Fe), while that of VRAH consisted of 10.469 ± 1.588 (Ti), 7.896 ± 2.154 (Fe) and 4.389 ± 0.371 (Zn). Therefore, the heavy metals' mean concentration at the BA is above the WHO permissible limits of soil, i.e., 0.056kgm-3 (Ti), 0.085kgm-3 (Pb), 0.100kgm-3 (Cr) and 0.036kgm-3 (Cu). Furthermore, the heavy metal mean concentrations of TGH and VRAH present in the BA analysed samples were ranked in descending order: Ti > Zn > Fe and Ti > Fe > Zn, respectively. It is therefore recommended that BA must be properly disposed of because of the hazardous nature of heavy metals present in the analysed samples, which are able to cause environmental and public health issues.

‘Turn-ON’ furfurylamine-based fluorescent sensor for Cd2+ ion detection and its application in real water samples

‘Turn-ON’ furfurylamine-based fluorescent sensor for Cd2+ ion detection and its application in real water samples

A halophilic Chromohalobacter species from estuarine coastal waters as a detoxifier of manganese, as well as a novel bio-catalyst for synthesis of n-butyl acetate.

Anthropogenic pollution due to ferro-manganese ore transport by barges through the Mandovi estuary in Goa, India is a major environmental concern. In this study a manganese (Mn) tolerant, moderately halophilic Chromohalobacter sp. belonging to the family Halomonadaceae was isolated from the sediments of a solar saltern adjacent to this Mandovi estuary. Using techniques of Atomic absorption spectroscopy, Scanning electron microscopy-Energy dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy and Atomic Force Microscopy, the Chromohalobacter sp. was explored for its ability to tolerate and immobilize Mn in amended and unamended media with 20% natural salt concentration (w/v). In aqueous media supplemented with 0.1 mM Mn, the Chromohalobacter sp. was capable of sequestering up to 76% Mn with an average immobilization rate of 8 mg Mn /g /day. Growth rate kinetic analysis using Gompertz mathematical functions was found to model the experimental data well. The model inferred that the maximum growth rate of Chromohalobacter sp. was at 10% natural salt concentration (w/v). The Chromohalobacter sp. was further found to be multimetal tolerant showing high tolerance to Iron (Fe), Nickel (Ni) and Cobalt (Co), (each at 4 mM), and tolerated Manganese (Mn) up to 6 mM. Morphologically, the Chromohalobacter sp. was a non-spore forming, Gram negative motile rod (0.726 μ× 1.33 μ). The adaptative mechanism of Chromohalobacter sp. to elevated Mn concentrations (1 mM) resulted in the reduction of its cell size to 0.339 μ× 0.997 μ and the synthesis of an extracellular slime, immobilizing Mn from the liquid phase forming Manganese oxide, as confirmed by Scanning Electron Microscopy. The expression of Mnx genes for manganese oxidation further substantiated the finding. This bacterial synthesized manganese oxide also displayed catalytic activity (∼50% conversion) for the esterification of butan-1-ol with CH3COOH to yield n-butyl acetate. This Chromohalobacter sp. being indigenous to marine salterns, has adapted to high concentrations of heavy metals and high salinities and can withstand this extremely stressed environment, and thus holds a tremendous potential as an environmentally friendly "green bioremediator" of Mn from euryhaline environments. The study also adds to the limited knowledge about metal-microbe interactions in extreme environments. Further, since Chromohalobacter sp. exhibits commendable catalytic activity for the synthesis of n-butyl acetate, it would have several potential industrial applications.