CS Molecule Research Articles

Stimuli‐Mediated Structural Interchange Between Pd6 and Pd12 Architectures: Selective Recognition of E‐Stilbene by the Pd6 Architecture and its Photoprotection

AbstractThe dynamic behaviour of metal‐ligand bonding cultivates stimuli‐mediated structural transformations in self‐assembled molecular architectures. The propensity of synthetically designed self‐assembled systems to interchange between higher‐order architectures is increased multi‐fold when the building blocks have higher conformational degrees of freedom. Herein, we report a new ligand, (2,7‐bis(di(pyridin‐4‐yl)amino)‐9H‐fluoren‐9‐one) (L), which, upon self‐assembly with a cis‐[(ethylene‐1,2‐diamine)Pd(NO3)2] acceptor (M), resulted in the formation of a M6L3 trifacial barrel (C1) in water. Interestingly, during crystallization, a rare M12L6 triangular orthobicupola architecture (C2) was generated along with C1. C2 could also be generated in solution via the application of several stimuli. C1 in aqueous media could stabilize one trans‐stilbene (tS) or cis‐stilbene (cS) molecule in its cavity, with a selectivity for the former from their mixture. Moreover, C1 acted as an effective host to prevent the otherwise facile photoisomerization of tS to cS inside its hydrophobic cavity under UV irradiation. Conversely, the visible‐light‐induced reverse isomerization of encapsulated cS to encapsulated tS could be achieved readily due to the better stabilization of tS within the cavity of C1 and its transparency to visible light. A multi‐functional system was therefore designed, which at the same time is stimuli‐responsive, shows isomer selectivity, and photo‐protects trans‐stilbene.

Sulfur fractionation using high-resolution continuum source molecular absorption spectrometry with calcium and hydrophobic palladium nanoparticles as chemical modifiers

The unprecedented use of high-resolution continuum source molecular absorption spectrometry (HR-CS MAS) for the fractionation of organic and inorganic sulfur (S) species through monitoring the CS molecule is presented here. Two separate methods for determining organic (CSorg) and inorganic (CSino) sulfur were developed to work sequentially. The optimized temperature program for both methodologies has two pyrolysis steps and one vaporization step (1st Tpyr: 1800 and 2ndTpyr: 800 °C, and Tvap: 2500 °C). The fractionation was achieved by implementing hydrophobic Pd NPs and Ca as chemical modifiers for the CSorg and CSino methods. Method development was performed by applying different statistical models, allowing the definition of optimal conditions for the chemical modifier mass, and minimizing the S species interconversion, i.e., Doehlert design, and central composite design. The limits of detection (LoD) for CSorg and CSino were 2.4 and 2.1 mg L−1, respectively. Recovery tests evaluated the method's specificity and accuracy; over 92 % recovery was found for both CSorg and CSino. Thus, the proposed methods offer a reliable alternative for fractionating organic and inorganic S by using HR-CS MAS.

Stimuli-Mediated Structural Interchange Between Pd6 and Pd12 Architectures: Selective Recognition of E-Stilbene by the Pd6 Architecture and its Photoprotection.

The dynamic behaviour of metal-ligand bonding cultivates stimuli-mediated structural transformations in self-assembled molecular architectures. The propensity of synthetically designed self-assembled systems to interchange between higher-order architectures is increased multi-fold when the building blocks have higher conformational degrees of freedom. Herein, we report a new ligand, (2,7-bis(di(pyridin-4-yl)amino)-9H-fluoren-9-one) (L), which, upon self-assembly with a cis-[(ethylene-1,2-diamine)Pd(NO3)2] acceptor (M), resulted in the formation of a M6L3 trifacial barrel (C1) in water. Interestingly, during crystallization, a rare M12L6 triangular orthobicupola architecture (C2) was generated along with C1. C2 could also be generated in solution via the application of several stimuli. C1 in aqueous media could stabilize one trans-stilbene (tS) or cis-stilbene (cS) molecule in its cavity, with a selectivity for the former from their mixture. Moreover, C1 acted as an effective host to prevent the otherwise facile photoisomerization of tS to cS inside its hydrophobic cavity under UV irradiation. Conversely, the visible-light-induced reverse isomerization of encapsulated cS to encapsulated tS could be achieved readily due to the better stabilization of tS within the cavity of C1 and its transparency to visible light. A multi-functional system was therefore designed, which at the same time is stimuli-responsive, shows isomer selectivity, and photo-protects trans-stilbene.

Chitosan grafting coumarin-3-carboxylic acid fluorescent fiber with enhanced strength prepared by in-situ wet-spinning

Chitosan grafting coumarin-3-carboxylic acid (CS-g-CCA) fiber with fluorescent function and enhanced tensile strength was successfully prepared by in-situ wet-spinning. FTIR and NMR results demonstrate that CCA is successfully grafted onto the CS molecule chains. As the grafting rate increases from 4.2 to 15.8 %, the spinning solution viscosity increases from 22 to 54 Pa·s. SEM observations show that the CS and CS-g-CCA fiber surfaces and cross-sections exhibit homogeneity and smoothness. Likewise, as the drawing ratio increases from 1.0 to 1.4, 2D WAXS patterns illustrate the molecular chain oriented significantly along the drawing direction. The CS-g-CCA fiber (the grafting rate of 15.8 %) exhibits a maximum breaking strength of 1.06 cn/dtex, increasing by 20 % more than the CS fiber. Meanwhile, it has a peak fluorescence intensity of around 480 nm. In addition, the continuous preparation process simplifies the technological route and improves the preparation efficiency of CS-g-CCA fiber. As-prepared CS-g-CCA fiber with enhanced tensile strength and elevated fluorescence efficiency lays the foundation for potential application in fluorescent probes, anti-counterfeiting, and biomedicine fields.

Thiolated chitosan nanoparticles for stable delivery and smart release of As2O3 for liver cancer through dual actions

In this work, multifunctional thiolated chitosan derivatives (DCA-CS-PEG-FA-NAC) were synthesized, and arsenic trioxide (ATO) was loaded onto the derivatives through glutathione (GSH)-sensitive AsIII-S bonds, and stable CS-ATO nanodrugs were prepared by simple self-assembly method. By adjusting the thiol substitution degree of CS, the drug loading capacity of the nanodrugs was significantly improved, which could reach 20 ATO per CS molecule (DCA10.7-CS-PEG3.1-FA-NAC20.2-ATO). In vitro release studies obviously showed the low leakage of ATO under physiological conditions while over 95 % ATO was released after 24 h under GSH. In vitro and in vivo investigations demonstrated that the DCA10.7-CS-PEG3.1-FA-NAC20.2-ATO nanodrug could significantly enhance the tumor intracellular accumulation of ATO, reduce the toxic and side effects of ATO on healthy organs, and improve the therapeutic effect of ATO on the HepG2 mice tumor model (tumor inhibition rate was as high as 86.4 %), indicating the potential application of ATO in clinical treatment of liver cancer.

Molecule opacity study on low-lying states of CS

CS molecule, which plays a key role in atmospheric and astrophysical circumstances, has drawn great attention for long time. Owing to its large state density, the detailed information of the electronic structure of CS is still lacking. In this work, the high-level MRCI+Q method is used to compute the potential energy curves, dipole moments and transition dipole moments of singlet and triplet states correlated with the lowest dissociation limit of CS, based on which high accurate vibration–rotation levels and spectroscopic constants of bound states are evaluated. The opacity of CS relevant to atmospheric circumstance is computed at a pressure of 100 atms for different temperatures. With the increase of temperature, band systems from different transitions mingle with each other, and band boundaries become blurred, which are originated from the increased population on vibrational excited states and electronic excited states at high temperature.

Magic conditions for multiple rotational states of bialkali molecules in optical lattices

We investigate magic-wavelength trapping of ultracold bialkali molecules in the vicinity of weak optical transitions from the vibrational ground state of the X$^1\Sigma^+$ potential to low-lying rovibrational states of the b$^3\Pi_0$ potential, focussing our discussion on the $^{87}$Rb$^{133}$Cs molecule in a magnetic field of $B=181\,$G. We show that a frequency window exists between two nearest neighbor vibrational poles in the dynamic polarizability where the trapping potential is "near magic" for multiple rotational states simultaneously. We show that the addition of a modest DC electric field of $E=0.13\,\text{kV}/\text{cm}$ leads to an exact magic-wavelength trap for the lowest three rotational states at a angular-frequency detuning of $\Delta_{v'=0} = 2\pi\times 218.22$\,GHz from the X$^1\Sigma^+ (v=0, J=0)\rightarrow$ b$^3\Pi_0 (v'=0, J=1)$ transition. We derive a set of analytical criteria that must be fulfilled to ensure the existence of such magic frequency windows and present an analytic expression for the position of the frequency window in terms of a set of experimentally measurable parameters. These results should inform future experiments requiring long coherence times on multiple rotational transitions in ultracold polar molecules.

CS Depletion in Prestellar Cores

Abstract The CS molecule is known to be adsorbed onto dust in cold and dense conditions, causing it to be significantly depleted in the central region of cores. This study is aimed to investigate the depletion of the CS molecule using the optically thin molecular line observations. We mapped five prestellar cores, L1544, L1552, L1689B, L694-2, and L1197, using two molecular lines, (J = 2 − 1) and (J = 1 − 0) with the NRO 45 m telescope, doubling the number of cores where the CS depletion was probed using . In most of our targets, the distribution of emission shows features that suggest that the CS molecule is generally depleted in the center of the prestellar cores. The radial profile of the CS abundance with respect to directly measured from the CS emission and the Herschel dust emission indicates that the CS molecule is depleted by a factor of ∼3 toward the central regions of the cores with respect to their outer regions. The degree of the depletion is found to be even more enhanced, by an order of magnitude, when the contaminating effect introduced by the presence of CS molecules in the surrounding envelope that lie along the line of sight is removed. Except for L1197—which is classified as relatively the least evolved core in our targets, based on its observed physical parameters—we found that the remaining four prestellar cores are suffering from significant CS depletion at their central region, regardless of the relative difference in their evolutionary status.

Investigation of different chemical modifiers based on the Pd/Mg mixture for the determination of sulfur in shale oil by high-resolution continuum source graphite furnace molecular absorption spectrometry

This study investigated different combinations of Pd/Mg, as chemical modifier, for sulfur determination, via CS molecule, in shale oil samples by high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS). It was evaluated the mixture Pd/Mg in aqueous solution, Pd/Mg in propan-1-ol and the Pd/Mg in propan-1-ol plus Ru as a permanent modifier. The best sensitivity was achieved with Pd/Mg mixture in propan-1-ol. The high solubility of the samples in propan-1-ol promotes a better interaction with the modifier and, consequently, a more efficient thermal stability of the CS molecules. Due to the high sulfur content in the samples, the analytical line at 258.288 nm was used. Only a minimum sample preparation was required, i.e., a dilution in propan-1-ol by a factor of 1:10 (w/w). Temperatures of 800 °C and 2200 °C were the optimized conditions for pyrolysis and vaporization, respectively. The calibration curve was constructed with l-cysteine aqueous standard solutions. The characteristic mass was 27 ng; detection and quantification limits were 0.012% (w/w) and 0.039% (w/w), respectively. The accuracy of the proposed method was confirmed by the statistical agreement (Student's and Welch's t-test at 95% confidence level) using the certified reference material CRM NIST 1084a and an OTE oil sample whose sulfur content was previously determined by the standard method ASTM D4294. The method was successfully applied in three shale oil samples. The sulfur content in the investigated samples ranged from 1.0% (w/w) to 1.3% (w/w).

Effect of external magnetic field on the shift of resonant frequency in photoassociation of ultracold Cs atoms**Project supported by the National Key Research and Development Program of China (Grant No. 2017YFA0304203), the Chang Jiang Scholars and Innovative Research Team in the University of the Ministry of Education of China (Grant No. IRT13076), the National Natural Science Foundation of China (Grant

We study the influence of external magnetic field on the shift of the resonant frequency in the photoassociation of ultracold Cs atoms, which are captured in a magnetically levitated optical crossed dipole trap. With the increase of the photoassociation laser intensity, the linear variation of the frequency shift is measured by recording the photoassociation spectra of the long-range state of Cs molecule below the 6S1/2+6P1/2 dissociation limit at different magnetic fields. The slope of the frequency shift to the intensity of the photoassociation laser exhibits a strong dependence on the external magnetic field. The experimental data is simulated with an analytic theory model, in which a single channel rectangular potential with the tunable well depth is introduced to acquire the influence of the magnetic field on the atomic behavior in the effective range where photoassociation occurs.

A comparative study on the bond features in CO, CS, and PbS.

Covalent and noncovalent interactions dominate most compounds in the condensed phase and gas phase. For a classical diatomic molecule CO, it is usually regarded as a triple-bond system with one dative bond. In this work, the photoelectron velocity-map imaging spectra of the CS and PbS anions were first measured. The two interactions have been intuitively understood by a comparative investigation of electrostatic potential (ESP) and bond features in CO, CS, and PbS. It is suggested that both electrostatic and dative covalent interactions compete in CO molecules, while dative covalent interaction prevails in CS molecules and electrostatic interaction dominates in PbS molecules. As a consequence, CO has a very small dipole moment (∼0.1 D) compared to the large dipole moment in CS (>1.8 D) and PbS (>4 D). It is indicated that the electron affinity value increases with the increasing dipole moment in the order of CO < CS < PbS. In addition, intriguing ESP with negative bond-ends and positive bond-cylindrical-surface in CO is also revealed by comparing with that in CS and PbS. In the latter, the two molecules present opposite ESP maps. Molecular orbital analyses indicate surprising participation of Pb 5d orbitals in the Pb-S chemical bonding although Pb belongs to main-group elements. Further bond analyses using electron localization function, natural resonance theory, and bond order methods suggest that covalence is dominant in CS and ionicity is a major component in PbS, but somewhere in between for CO molecules. By a comparative study in this work, the CS molecule is also revealed as a promising ligand molecule for the transition-metal coordination chemical synthesis.

A dual-functional bimetallic-organic framework nanosensor for detection and decontamination of lachrymator in drinking water

A novel nanosensor (MOFs-SH) was constructed from a nanorod bimetallic-organic frameworks, exhibits highly selective and sensitive recognition and detection of 2-chlorobenzalmalononitrile (CS) lachrymator. By combining the high selectivity of thiol-ene click reaction and the strong luminescence properties of lanthanide metal-organic frameworks, MOFs-SH has demonstrated high selectivity and sensitivity towards CS, with satisfactory rapidity, accuracy, reliability and practicality. Mercaptan was used as a connector between MOFs and CS molecule by coordination bond and click reaction, thus induced a luminescence quenching based on an acceptor-excited photoinduced electron transfer mechanism. The electron transfer process between MOFs-SH and CS led to significant fluorescence quenching of the nanosensor, by which CS could be sensed, and high detection sensitivity up to 32.1 ppb was attained. Moreover, the nanosensor was successfully applied to determine CS in drinking water samples, and surprisingly shows the ability to purify polluted drinking water which polluted by CS (Qa = 425 mg g-1). This first reported CS sensing and decontaminate platform have been promising application for highly sensitive detection and postwar water purification of CS toxicant.

Survey of Regions with Methanol Masers in the CS (J = 2–1) Line: Statistical Characteristics of Radiation

The paper aims at establishing relations between the parameters of methanol maser emission that originates in dense star-forming regions and parameters of a dense core using emission of the CS molecule. A total of 164 sources toward the positions of methanol masers using the RT-22 radio telescope at CrAO, Ukraine, have been observed. For 85 sources, the CS (J = 2–1) line emission was detected. Most of the sources have been selected from catalogs of the class I and class II methanol masers. For methanol masers, this is the most complete survey in the CS (J = 2–1) line on the northern sky. A comparative analysis of parameters of methanol masers spectra in the CS (J = 2–1) line, and methanol masers, luminosities of dense cores, and infrared sources, has been performed. The detection rates of the CS (J = 2–1) line emission, its intensities and widths, the differences between the systematic velocities and velocities of the maser line centers have been investigated. The radiation detection rates in the CS (J = 2–1) line are shown to differ for various source samplings. The form of the dependences lgLcs – lgLbol, lgLmas – lgLcs and lgLmas – lgLbol has been found for sources with which methanol masers are associated. Based on the luminosity of infrared sources, samples of sources in which the CS (J = 2–1) line emission is detected with a higher probability have been determined.

Stimuli-responsive luminescent coumarin thiazole hybrid dye: Mechanism of excited-state intramolecular double proton transfer

Recently, a novel coumarin thiazole hybrid dye with azomethine linkage is synthesized. It is revealed that the symmetrical structures 3,3'-(5,5'-((1E,1'E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(2-morpholinothiazole-5,4-diyl))bis(4-hydroxy-2H-chromen-2-one) (abbreviated as CS) takes shape two intramolecular hydrogen bonds and that excited-state intramolecular proton transfer (ESIPT) takes place with thiazole nitrogen atoms [Dyes Pigments. 142, 2017, 121]. However the corresponding reaction mechanisms are lacking. This study uses density functional and time-dependent density functional theory to calculate hydrogen-bond lengths, hydrogen-bond angles, infrared vibrational spectra and Mulliken charges of relevant groups, which confirm the excited-state hydrogen-bond strengthening mechanism. Enhanced hydrogen-bond strength facilitates the ESIPT process of the CS molecule. The absorption and fluorescence emission spectra of CS in dimethyl formamide (DMF) are calculated, which are consistent with the observed results in experiment. To further illustrate mechanism of excited-state double proton transfer (ESDPT) reactions, the potential energy surfaces of CS are constructed and analyzed, which demonstrate ESDPT more likely occur stepwise rather than concertedly. The frontier molecular orbitals of CS system are also calculated and display the nature of the charge redistribution, which demonstrate that CS system exhibits light fastness because ESIPT process inhibits intramolecular charge transfer.

Unveiling the inner morphology and gas kinematics of NGC 5135 with ALMA

The local Seyfert 2 galaxy NGC5135, thanks to its almost face-on appearance, a bulge overdensity of stars, the presence of a large-scale bar, an AGN and a Supernova Remnant, is an excellent target to investigate the dynamics of inflows, outflows, star formation and AGN feedback. Here we present a reconstruction of the gas morphology and kinematics in the inner regions of this galaxy, based on the analysis of Atacama Large Millimeter Array (ALMA) archival data. To our purpose, we combine the available $\sim$100 pc resolution ALMA 1.3 and 0.45 mm observations of dust continuum emission, the spectroscopic maps of two transitions of the CO molecule (tracer of molecular mass in star forming and nuclear regions), and of the CS molecule (tracer of the dense star forming regions) with the outcome of the SED decomposition. By applying the $^{\rm 3D}$BAROLO software (3D-Based Analysis of Rotating Object via Line Observations), we have been able to fit the galaxy rotation curves reconstructing a 3D tilted-ring model of the disk. Most of the observed emitting features are described by our kinematic model. We also attempt an interpretation for the emission in few regions that the axisymmetric model fails to reproduce. The most relevant of these is a region at the northern edge of the inner bar, where multiple velocity components overlap, as a possible consequence of the expansion of a super-bubble.

Synthesis and Characterization of Fatty Acid Grafted Chitosan Polymer and Their Nanomicelles for Nonviral Gene Delivery Applications.

The aim of this study was to synthesize and characterize fatty acid-grafted-chitosan (fatty acid-g-CS) polymer and their nanomicelles for use as carriers for gene delivery. CS was hydrophobically modified using saturated fatty acids of increasing fatty acyl chain length. Carbodiimide along with N-hydroxysuccinimide was used for coupling carboxyl group of fatty acids with amine groups of CS. Proton nuclear magnetic resonance and Fourier transform infrared spectroscopy were used to quantify fatty acyl substitution onto CS backbone. The molecular weight distribution of the synthesized polymers was determined using size exclusion high performance liquid chromatography and was found to be in range of the parent CS polymer (∼50 kDa). The critical micelle concentration (cmc) of the polymers was determined using pyrene as a fluorescent probe. The cmc was found to decrease with an increase in fatty acyl chain length. The amphiphilic fatty acid-g-CS polymers self-assembled in an aqueous environment to form nanomicelles of ∼200 nm particle size and slightly positive net charge due to the cationic nature of free primary amino groups on CS molecule. These polymeric nanomicelles exhibited excellent hemo- and cytocompatibility, as evaluated by in vitro hemolysis and MTT cell viability assay, respectively, and showed superior transfection efficiency compared to unmodified chitosan and naked DNA. The surface of these nanomicelles can be further modified with ligands allowing for selective targeting, enhanced cell binding, and internalization. These nanomicelles can thus be exploited as potential nonviral gene delivery vectors for safe and efficient gene therapy.

Method development and validation for sulfur determination via CS molecule in petroleum green coke by high resolution continuum source molecular absorption spectrometry

Development and validation of a method for determination of sulfur via CS molecule in petroleum green coke samples by high resolution continuum source molecular absorption spectrometry (HR-CS MAS) is the aim of this work. The protocol adopted for the method validation followed criteria based on international guidelines. Optimizations and determination of the analyte in the samples were carried out at the wavelength 258.0330nm, at the same spectral interval of the analytical line of Tl. Slurry prepared using Triton X-100 (0.05% v/v) without the use of HNO3, is proposed as a simple and fast sample treatment. Chemical modifier KOH (1.0% m/v) was important to promote the formation and stabilization of CS molecule. Pyrolysis and Vaporization temperatures were optimized using different compounds, ammonium sulfate, l-cysteine monohydrochloride and thiourea aqueous solutions, and also certified reference material, NIST 2718, and petroleum green coke. Compromise temperature conditions were 1000°C and 2600°C, for pyrolysis and vaporization, respectively. Aqueous calibration with thiourea presented the best condition and was chosen for the determination of the analyte. The obtained concentrations of sulfur in coke samples were between 6.20mgg−1 and 9.40mgg−1. The following parameters were evaluated as validation protocol: accuracy, precision, linearity, limits of detection and quantification, sensitivity, selectivity, robustness, working range and measurement uncertainty. Weighted least square (WLS) method was employed to estimate LOD and LOQ, since it leads to lower final uncertainty. The evaluation of the validation parameters, especially the measurement uncertainty, confirmed the satisfactory performance of the method.

Investigation of the self-assembly of CS and PCL copolymers with different molecular weights in water solution by coarse-grained molecular dynamics simulation

Coarse-grained molecular dynamics (CGMD) simulation was employed to investigate how stable chondroitin sulfate-graft-polycaprolactone (CS-PCL, CP) copolymers self-assemble into micelles in an aqueous environment. Three types of CP containing low (2.4%), medium (6.3%), and high (18.7%) PCL contents (denoted L-CP, M-CP, and H-CP, respectively) in which PCL molecules consisting of 63 monomers were grafted onto each CS molecule consisting of 120 monomers were considered. L-CP and M-CP were found to display spheroidal micellar structures, while H-CP presented a rod-like structure, in agreement with previous experimental observations. In addition, the entanglement of the PCL segment increased as its molecular weight was increased. The number density distribution profiles of PCL, CS, and water molecules indicated that there were a few water molecules between the PCL core of the micelle and the water solution surrounding the micelle (in the micelle layer immediately above the core), and the number density of water in the CP micelle increased as the PCL content decreased. Using the radius of gyration, the three-dimensional conformations of the micelles were explored. When the number of CP chains was 3, H-CP adopted a long nanorod form, whereas L-CP and M-CP were roughly nanospherical. When the number of CP chains was increased beyond 3, however, the structure of L-CP changed from a nanosphere to a nanodisk. Finally, the slope of the mean square displacement profile was greatest when the molecular weight of the PCL segment was lowest, indicating that the mobilities of the CS and PCL segments are highest in L-CP. The self-diffusion coefficients of the CS and PCL segments decreased as the number of PCL segments grafted increased. Graphical abstract Morphologies of H-CP micelle.

Superb hydroxyl radical-mediated biocidal effect induced antibacterial activity of tuned ZnO/chitosan type II heterostructure under dark

Reactive oxygen species (ROS) is the most dominating factor for bacteria cell toxicity due to release of oxidative stress. Hydroxyl radical (·OH) is a strong oxidizing ROS that has high impact on biocidal activity. This present paper highlights ·OH influenced antibacterial activity and biocidal propensity of tuned ZnO/chitosan (ZnO/CS) nanocomposite against Pseudomonas putida (P. putida) in the absence of light for the first time. For this purpose, the CS proportion was increased by 25 % (w/w) of ZnO during the preparation of ZnO/CS nanocomposite and a systematic study of different ROS like superoxide anion (O 2 ·− ), hydrogen peroxide (H2O2) and ·OH production as well as their kinetics was carried out both under UV irradiation and in dark by UV–Vis spectroscopy using NBT dye, starch and iodine reaction and fluorescence spectroscopy using terephthalic acid. The decoration of ZnO nanoparticles (ZnO·NPs) with CS tuning was characterized by XRD and FTIR spectroscopy, revealing sustained crystallinity and surface coating of ZnO NP (size about ~24 nm) by CS molecule. The hybridization of ZnO nanoparticles with CS@50 wt% (w/w) resulted superior biocidal activity (81 %) within 3 h in dark mediated by optimum production of ·OH among all ROS. Here we have proposed the enhanced production of ·OH in ZnO/CS due to generation of holes by entrapment of electrons in acceptor level formed in nanocomposite for the first time, and the acceptor levels were probed by Positron annihilation lifetime spectroscopy. The increase in non-positronium (non-Ps) formation probability (I2) in ZnO/CS nanocomposite confirmed the acceptor levels. This work also confirms surface defect-mediated ROS generation in dark, and zinc interstitials are proposed as active defect sites for generation of holes and ·OH for the first time and confirmed by steady-state room temperature photoluminescence spectroscopy. Finally, a plausible mechanism was hypothesized focusing on hole generation in ZnO NP and hole transfer from CS for the first time, and a heterostructure of type II was proposed.

Determination of sulfur in bovine serum albumin and l-cysteine using high-resolution continuum source molecular absorption spectrometry of the CS molecule

In this study, the content of sulfur in bovine serum albumin and l-cysteine was determined using high-resolution continuum source molecular absorption spectrometry of the CS molecule, generated in a reducing air-acetylene flame. Flame conditions (height above the burner, measurement time) were optimized using a 3.0% (v/v) sulfuric acid solution. A microwave lab station (Ethos Plus MW) was used for the digestion of both compounds. During the digestion step, sulfur was converted to sulfate previous to the determination. Good repeatability (4–10%) and analytical recovery (91–106%) was obtained.