Novel Collimated Beam Setup to Study the Kinetics of VUV‐Induced Reactions

Vacuum UV (VUV) process is an incipient advanced oxidation process, which can be used for water treatment. This process relies on the formation of hydroxyl radicals through the VUV‐induced photolysis of water. In particular, the use of ozone‐generating mercury vapor lamps, which emit 10% of the radiation at 185 nm and 90% at 254 nm, is showing very promising results for the degradation of micropollutants. The kinetics of VUV process has been studied in batch‐ and flow‐through reactors, but the effect of 254 and 185 nm photons cannot be isolated, mass transfer resistances can take place and the interpretation of the results is complex. In this technical note, a new VUV collimated beam to conduct kinetic tests is presented, which offers several advantages: (1) it allows the irradiation of samples with 185, 254 nm photons, or both, (2) the concentration of reagents is uniform in the reaction volume and (3) it allows to change the fluence rate by changing the distance between the lamp and the photoreactor. Details of the geometry are presented, as well as an analysis of the collimation and uniformity of the radiation of the new VUV‐collimated beam setup.     

Quantification of sunscreen 2-phenylbenzimidazole-5-sulfonic acid in cosmetic products and water samples by HPTLC/densitometry with fluorescent detection

The water-soluble sunscreen 2-phenylbenzimidazole-5-sulfonic acid (PBS) was quantified in a sun-care product and water samples by thin layer chromatography followed by densitometric scanning in fluorescence mode (cut-off filter 370 nm, wavelength of excitation — 300 nm). Normal phase TLC was performed on silica gel 60 as stationary phase. Mobile phase used was ethyl acetate-ethanol-water 70:35:30 (v/v/v). The limit of detection (LOD) was 0.0004 μg spot-1, and the limit of quantification (LOQ) was — 0.001 μg spot^?1 without any sample pre-concentration.      

Influence of vegetable oil on the synthesis of bioactive nanocarriers with broad spectrum photoprotection

Due to their unique features, most nanostructured lipid carriers (NLCs) in association with vegetable oils that exhibit UV filtering properties and bioactivity could be used in many cosmetic formulations. Therefore, in this work, a new application of pomegranate seed oil (PSO) in the cosmetic sector was developed, based on the synthesis of bioactive lipid nanocarriers loaded with various UV filters by the hot high pressure homogenization technique. To get broad spectrum photoprotection, different UVA and UVB filters have been used (Avobenzone — AVO, Octocrylen-OCT, Bemotrizinol — BEMT). The influence of the solid lipids combined with PSO on the particle size, physical stability and entrapment efficiency was investigated using 8 nanocarrier systems. An improved physical stability and an appropriate size were obtained for NLCs prepared with Emulgade, carnauba wax and PSO (e.g. ?30.9÷-36.9 mV and 160÷185 nm). NLCs showed an entrapment efficiency above 90% and assured slow release rates of UV filters, especially for BEMT (5%). The developed nanocarriers have been formulated into safe and effective sunscreens containing low amounts of synthetic UV filters coupled with a high percent of natural ingredients. The highest SPF of 34.3 was obtained for a cream comprising of 11% PSO and 3.7% BEMT

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Spectral properties of coumarin derivatives in various environments

The structural and spectral properties of coumarin derivatives in complex environments were investigated within the time-dependent density functional theory (TD DFT). Absorption spectra calculations were obtained at TD PBE0/6-31+G(d,p) level of theory for coumarin47 in the gas-phase and in various polar and non-polar organic solvents. The geometries of coumarins 6, 30, 47 and 522 in the gas phase and in inclusion complexes with the β-cyclodextrin (βCD) were determined by PM3 and DFT (HCTH/6-31G) calculations. Encapsulation of coumarin in βCD and associated changes in electronic structure produced either a red or blue shift in the absorption spectra of coumarins. A proposed cavity model for βCD-coumarin complex in water solution allowed identification of various contributions to the overall shift in the absorption spectra of coumarin upon complex formation in a solvent environment      

Application of UV detection in HPLC in the total antioxidant potential assay

HPLC has been already used for the TAP estimation. Phenylalanine, salicylic, p-hydroxybenzoic (pHBA) or terephthalic (TPA) acids have been used as sensor compounds. Products of their reaction with the hydroxyl radicals, generated in the Fenton-like reaction, were analyzed using electrochemical or fluorescence detection. This paper describes the TAP assay based on the hydroxyl radicals reaction with pHBA, reversed-phase-HPLC separation and UV photometric detection. The elaborated assay has been used to evaluate TAP values of some apiculture products.      

Comparison of the Disinfection Effects of Vacuum-UV (VUV) and UV Light on Bacillus subtilis Spores in Aqueous Suspensions at 172, 222 and 254 nm

The efficacy of UV and vacuum-UV (VUV) disinfection of Bacillus subtilis spores in aqueous suspensions at wavelengths of 172, 222 and 254 nm was evaluated. A Xe₂* excilamp, a KrCl* excilamp and a low-pressure mercury lamp were used as almost monochromatic light sources at these three wavelengths. The first-order inactivation rate constants at 172, 222 and 254 nm were 0.0023, 0.122 and 0.069 cm² mJ⁻¹, respectively. Therefore, a 2 log reduction of B .  subtilis spores was reached with fluences (UV doses) of 870, 21.6 and 40.4 mJ cm⁻² at these individual wavelengths. Consequently, for the inactivation of B .  subtilis spores, VUV exposure at 172 nm is much less efficient than exposure at the other two wavelengths, while exposure at 222 nm is more efficient than that at 254 nm, which is probably because triplet energy transfer from DPA to thymine bases at 222 nm is higher than that at 254 nm. This research indicated quantitatively that VUV light is not practicable for microorganism disinfection in water and wastewater treatment. However, in comparison with other advanced oxidation processes ( e.g. UV/TiO₂, UV/H₂O₂ or O₃/H₂O₂) the VUV-initiated photolysis of water is likely more efficient in generating hydroxyl radicals and more effective for the inactivation of microorganisms.     

Fabrication of superhydrophobic surface of stearic acid grafted zinc by using an aqueous plasma etching technique

A stable superhydrophobic surface of stearic acid grafted zinc was fabricated with two steps, that is, the zinc surface was firstly treated with glow discharge electrolysis plasma (GDEP) and then followed by a grafted reaction of stearic acid onto the treated zinc surface. Results indicated that the wettability of zinc substrate changed from superhydrophily to superhyphodrobicity with a water contact angle (CA) up to 158° and a water sliding angle (SA) less than 5°. The surface morphology and composition were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively.      

Determination of some frequently used antibiotics in waste waters using solid phase extraction followed by high performance liquid chromatography with diode array and mass spectrometry detection

This study is focused on the determination of some important antibiotics from different classes in waste water samples using solid phase extraction followed by high performance liquid chromatography with two detectors, diode array and mass spectrometer in positive ionisation mode. The investigated antibiotics include three penicillins (amoxicillin, ampicillin, penicillin G), two cephalosporins (ceftazidime, ceftriaxone), and two tetracyclines (tetracycline, doxycycline). The studied antibiotics were extracted from waste water samples using hydrophilic-lipophilic balanced cartridges. The extraction of antibiotics from water matrices was tested at several pH values. The best recoveries were obtained at pH 3 and 7 respectively. Depending on the nature of antibiotic, the limits of detection and quantification were obtained in the range of 0.07–0.92 µg mL^?1 and 0.21–2.77 µg mL^?1 respectively. Influent and effluent waste water samples were collected from a Waste Water Treatment Plant from Romania in order to detect the studied antibiotics. The antibiotics detected in the influent waste water samples were ceftriaxone (334 µg L^?1), tetracycline (146 µg L^?1) and doxycycline (110 µg L^?1). In effluent waste water samples no target antibiotics were detected.      

Agglomeration of ZnS nanoparticles without capping additives at different temperatures

ZnS nanoparticles were precipitated in diluted aqueous solutions of zinc and sulphide ions without capping additives at a temperature interval of 0.5–20°C. ZnS nanoparticles were arranged in large flocs that were disaggregated into smaller agglomerates with hydrodynamic sizes of 70–150 nm depending on temperature. A linear relationship between hydrodynamic radius (R _a ) and temperature (T) was theoretically derived as R _a =652 - 2.11 T. The radii of 1.9–2.2 nm of individual ZnS nanoparticles were calculated on the basis of gap energies estimated from their UV absorption spectra. Low zeta potentials of these dispersions of ?5.0 mV to ?6.3 mV did not depend on temperature. Interactions between individual ZnS nanoparticles were modelled in the Material Studio environment. Water molecules were found to stabilize ZnS nanoparticles via electrostatic interactions.      

Effect of microwave irradiation on polyphenolic compounds from Satureja hortensis L.

Summer savory (Satureja hortensis L.) is most often used as a culinary herb, but it also has medicinal benefits. The extracts from control and irradiated savory were obtained by ultrasound extraction for 30 minutes in an ethanol — water (80:20, v/v) mixture. Polyphenolic compounds from savory were identified and characterized by high-performance liquid chromatography coupled with a photodiode array detector and mass spectrometer. The separation was performed using an Altima C18 column (100×3 mm, 3 μm) and as mobile phase two solvent mixture: A — acetonitrile and B — water-formic acid (99.9:0.1, v/v). Peaks were identified with authentic standards in accordance to retention time, UV spectra and molecular mass. It was identified as caffeic acid, rosmarinic acid, luteolin, naringenin and apigenin. A quantitative determination of polyphenolic compounds was performed applying the external standard method. Our study showed large quantitative differences between the control plant and the irradiated plant.      

The first synthesis of 3-deoxyoripavine and its utilization in the preparation of 10-deoxyaporphines and cyprodime

The synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields.      

Effects of mechanical activation on structure and photocatalytic properties of ZnO powders

Zinc oxide (ZnO) was mechanically activated in air using a planetary ball mill using varying milling speeds and time. The obtained samples were analyzed by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and UV-Vis diffusion reflectance spectroscopy. The photocatalytic activity of the mechanically treated ZnO powders were investigated in the reaction of Malachite Green (MG) degradation in aqueous solution under UV-light irradiation. A decrease in the crystallite size (from 90 to 10 nm) accompanied by an increase of microstrains and lattice parameters were established applying different milling speeds. The agglomeration of the particles was observed by SEM analysis. The absorption spectra of the initial and mechanically activated ZnO samples show shifting of the band position from 360 to 330 nm, which can be related to decrease in the crystalline size. The ZnO powders activated at lower milling speeds (for shorter time intervals) exhibit highest photocatalytic activity.      

Ionic liquids based on 2-chloroethyltrimethylammonium chloride (CCC) as plant growth regulators

Plant growth regulator — 2-chloroethyltrimethylammonium chloride (CCC) was converted into ionic liquid in the metathesis reaction. New forms of CCC as ILs were stable in air as well in contact with water and organic solvents. The biological action of the cation (CCC) in ILs was preserved. Type of anion determined hydrophobicity and hydrophilicity of the whole molecule and it also influenced the biological activity of the plant growth regulator. All of the investigated salts retarded growth of winter wheat stems and most of them increased yield at the same time, when compared to control and standard 2-chloroethyltrimethylammonium chloride.      

Facile ultrasensitive monitoring of mercury ions in water by fluorescent ratiometric detection

Prospects for analytical application of 2,5-diphenyloxazole-substituted 3-hydroxychromone for detection of mercury ions are presented. Sensitivity and selectivity for a number of metal ions both in methanol solution and in the plasticized polymer are outlined. Ultrasensitive and highly selective fluorescent ratiometric response of the polymer film containing the title compound for mercury ions in water media is revealed. Reversibility of ratiometric response to mercury ions and influence of plasticizer’s content in the polymer film on the optical feedback are also discussed.      

Mechanical, thermal and surface properties of polyacrylamide/dextran semi-interpenetrating network hydrogels tuned by the synthesis temperature

The mechanical, rheological, thermal, and surface behaviors of three polyacrylamide/dextran (PAAm/Dx) semi-interpenetrating polymer network (semi-IPN) hydrogels, prepared at 22°C, 5°C and ?18°C, were investigated. The results were compared with those obtained on cross-linked PAAm without Dx synthesized under the same conditions. Hydrogels prepared at the lowest temperature were the most mechanically stable. The thermal stability of the semi-IPN hydrogels is slightly lower than the corresponding PAAm gels, irrespective of preparation temperature. The water vapor sorption capacity depended on the presence of Dx as well as preparation temperature, which determines the network morphology.      

Preparation of selectively protected protoescigenin derivatives for synthesis of escin analogs and neoglycoconjugates

Protoescigenin, the main aglycone of horse chestnut saponin mixture known as escin, was selected as substrate for exploratory chemistry towards selective protection, followed by propargyl ether formation and subsequent condensation with azido-monosaccharides, to obtain novel triazole linked conjugates of the triterpene.      

Polymer conjugates with potential biological activity based on new derivatives of 2-mercaptobenzoxazole-synthesis and characterization

New potentially biologically active compounds derived from 2-mercapto-benzoxazole were synthesized and coupled on polymeric support of poly (maleic anhydride-alt-vinyl acetate) for the preparation of polymer-drug conjugates with controlled drug release. All compounds were characterized by elemental and spectroscopy (FT-IR, ¹H-NMR) analysis. The toxicological tests recommend the products for further laboratory screening.      

Photonic crystals obtained by soap-free emulsion terpolymerization

This paper presents the use of soap-free emulsion terpolymerization to obtainphotonic crystals (PCs). Monodisperse latexes resulted from the polymerization of styrene (ST) with 2-hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) at different compositions defined as system A, B and C respectively. The water solubility of the macroradicals determined different nucleation mechanisms in all three cases. The micellar nucleation mechanism was more predominant for generating system A, whereas the homogeneous nucleation was specific for system C. For system B, both nucleation mechanisms werepossible with the same probability. The latexes and the resulted PCs were characterized by optical microscopy (OM), dynamic light scattering (DLS), gel permeation chromatography (GPC) and UV-VIS spectroscopy.      

Synthesis and characterization of nanosized NiO2 and NiO using Triton® X-100

Nanosized NiO₂ particles with an average diameter of 15 nm are prepared by treating of Ni(NO₃)₂ · 6H₂O with an aqueous solution of KClO in the presence of Triton® X-100. This black fine powder of nickel peroxide was characterized by XRD diffraction, energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). The as-prepared NiO₂ can be easily transformed to nanosized NiO merely by washing it with acetone. The obtained NiO has an average diameter of 40 nm and was characterized by the same means used for NiO₂. The nanoparticles of NiO₂ and NiO were obtained in high yields and purities.