Search

Honey nanoparticles have shown numerous unique characteristics such as biocompatibility and are excellent agents for biological applications. This study aims to investigate honey nanoparticles for 2, 2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical scavenging activity and their ability to offer protection against gamma radiation. In vitro antioxidant activity study of honey nanoparticles has shown good free radical scavenging activity for DPPH radical assayed within a concentration range of (0.05–2.5) × 10 − 4 g/l, at higher concentrations of nanoparticles showed reverse trend in absorbance and inhibition indicating this finite range of concentration is suitable for scavenging free radicals, also nanoparticles were found to have significant antioxidant capacity and thus can be used as potential radical scavenger against deleterious damages caused by the free radicals. [ABSTRACT FROM AUTHOR]

We propose in this study to develop a rapid, reliable, and non-culture method to detect and estimate bacteriophage (phage) titre as an alternative to the routine use of the double agar overlay assay (DLA). The present method is based on the analysis of nanoparticle (NPs) dispersion/aggregation dynamic in interaction with the phage. Titanium dioxide nanoparticles (TiO2-NPs) were used as nanosensors to detect and monitor virions' titres in aqueous samples. Dispersion stability of TiO2-NPs in aqueous suspension was investigated using a UV-Visible spectrophotometer. The comparison of NP spectral profiles with and without phage elucidated the impact of phage's titre on NP dispersion/aggregation behaviour in an aqueous solution. Indeed, the increase of nanoparticle dispersion stability is correlated with the increase of phage titre. Thus, based on this result, the phage was considered as a bio-dispersant agent. The determination of area under spectral profiles limiting the UV region [200–400 nm] was allowed to quantify, and compare the NPs bio-dispersion rate, in relation with added phage at different titres. In this study, this method was applied to monitor the phage amplification cycle for the detection of bacteria in viable but non-culturable (VBNC) state after water treatment by photocatalysis. The analysis of NP bio-dispersion rate shows an increase of TiO2-NP dispersion stability correlated with an increase of free phage titration, mainly after the entry of target bacteria in VBNC state underestimated using a conventional method. Thus, this method could allow the establishment of new recommendations of wastewater treatment and assessment. [ABSTRACT FROM AUTHOR]

One useful technique for increasing the efficiency of organic dye-sensitized solar cells (DSSCs) is to extend the π-conjugated bridges between the donor (D) and the acceptor (A) units. The present study used the DFT and TD–DFT techniques to investigate the effect of lengthening the polyene bridge between the donor N, N-dimethyl-anilino and the acceptor dicyanovinyl. The results of the calculated key properties were not all in line with expectations. Planar structure was associated with increasing the π-conjugation linker, implying efficient electron transfer from the donor to the acceptor. A smaller energy gap, greater oscillator strength values, and red-shifted electronic absorption were also observed when the number of polyene units was increased. However, some results indicated that the potential of the stated dyes to operate as effective dye-sensitized solar cells is limited when the polyene bridge is extended. Increasing the polyene units causes the HOMO level to rise until it exceeds the redox potential of the electrolyte, which delays regeneration and impedes the electron transport cycle from being completed. As the number of conjugated units increases, the terminal lobes of HOMO and LUMO continue to shrink, which affects the ease of intramolecular charge transfer within the dyes. Smaller polyene chain lengths yielded the most favorable results when evaluating the efficiency of electron injection and regeneration. This means that the charge transfer mechanism between the conduction band of the semiconductor and the electrolyte is not improved by extending the polyene bridge. The open circuit voltage (VOC) was reduced from 1.23 to 0.70 V. Similarly, the excited-state duration (τ) decreased from 1.71 to 1.23 ns as the number of polyene units increased from n = 1 to n = 10. These findings are incompatible with the power conversion efficiency requirements of DSSCs. Therefore, the elongation of the polyene bridge in such D-π-A configurations rules out its application in solar cell devices. [ABSTRACT FROM AUTHOR]

Green synthesis is an easy and economical method of synthesizing silver nanoparticles (AgNPs). However, many variables, including the ideal temperature, the volume and concentration of silver nitrate, the amount of plant extract, etc., affect the green synthesis. This article aims to determine the ideal temperature and plant extract amount using the UV-VIS spectrum. It was found above 40 °C was required for both Calendula arvensis (field marigold) leave extract and silver nitrate to synthesize AgNPs. The optimum temperatures were 55 °C and 60 °C for AgNO3 and plant extract, respectively and it was determined using Taguchi orthogonal array based on the UV-VIS spectrum. Silver nanoparticles (AgNPs) can be incorporated into textiles by padding and in-situ methods, but they need accurate plant extract amounts for good antibacterial efficiency. Two equations were proposed for determining the optimum plant extract amount for padding and in-situ methods. Several AgNPs loaded samples were prepared following the derived equations. For evaluating the efficiency of the equations C.reticulata (orange) peel extract was used besides C.arvensis plant extract. The samples were also characterized by antibacterial tests, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and X-ray diffraction (XRD). It showed when plant extract was taken according to the equations, around 45 nm nanoparticle size and 100% antibacterial activity were obtained. However, taking 1 ml more plant extract than that of the calculated amount of plant extract increased nanoparticle size to 107 nm and reduced antibacterial activity to 90%.

This study utilized a colorimeter to determine the color values of 23 beauty tea (BT) samples, the color and the taste characteristics were also quantitatively described through ultraviolet–visible (UV–Vis) spectroscopy and taste equivalent quantification. Furthermore, metabolomic analysis was conducted by using ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS). Correlation analysis was employed to preliminarily identify the compounds that contribute to the color and taste of BT infusion. Finally, the contributing compounds were further determined through verification experiment. The results showed that within a certain range, as the color of BT infusion deepened, the taste became stronger, more bitter and astringent, while on the contrary, it became sweeter and mellower. Theaflavins, kaempferol, astragalin, and 5-p-coumaroylquinic acid influenced both the color and taste of the BT infusion. Gallic acid was also determined as a contributor to the color. This study provides new insights into research on tea quality in infusion color and taste aspects.

According to several studies, phytochemicals, such as polyphenols, flavones, and flavonoids have significant anticancer properties that can combat various malignancies. Even though its action is highly dependent on the intracellular availability of reduced glutathione, Quercetin is regarded as an excellent free-radical scavenging antioxidant flavonoid. Apart from its antioxidant properties, Quercetin has a direct pro-apoptotic action in tumor cells. It has been shown to inhibit the proliferation of multiple human cancer cell lines at various cell cycle stages. The choice of a suitable chemopreventive agent was based on epidemiological studies that showed that consuming a specific dietary component (e.g. Quercetin) can lower the incidence of specific cancer death. MLK4 (KIAA1804) is the second most often altered kinase in colorectal carcinomas with microsatellite stability (MSS) (CRC). MLK4 regulates various physiological cellular processes, including cell cycle, senescence, and apoptosis, and mechanistic evidence suggests MLK4 is involved in carcinogenesis. In this study, the molecular structure of the Quercetin molecule was optimized using DFT/B3LYP method with a cc-pVTZ basis set, and the structural parameters were calculated. The generated vibrational spectra and the optimized molecular geometry were thoroughly reviewed and compared with experimental findings, resulting in a strong correlation. FMOs analysis was performed, which confirms the molecular reactivity of the Quercetin molecule. The anti-tumor efficacy of Quercetin was examined against the colon cancer target protein through in silico parameters, such as molecular docking and dynamics, ADME studies, MM-GBSA calculations, and the Pharmacophore hypothesis. From the analysis, the docked complex showed the highest docking score and maintained the complex stability and flexibility throughout the simulation period. Thus, the present study concluded that Quercetin could be a potent inhibitor of targeted colon cancer protein. [ABSTRACT FROM AUTHOR]

Amphotericin B (AmB) is an amphiphilic drug commonly formulated in liposomes and administered intravenously to treat systemic fungal infections. Recent studies on the liposomal drug product have shed light on the AmB aggregation status in the bilayer, which heat treatment (curing) modifies. Although toxicity was found related to aggregation status - loose aggregates significantly more toxic than tight aggregates - the precise mechanism linking aggregation and toxicity was not well understood. This study directly measured drug release rate from various AmB liposomal preparations made with modified curing protocols to evaluate correlations among drug aggregation state, drug release, and in vitro toxicity. UV–Vis spectroscopy of these products detected unique curing-induced changes in the UV spectral features: a ∼25 nm blue-shift of the main absorption peak (λmax) in aqueous buffer and a decrease in the OD346/OD322 ratio upon thermal curing, reflecting tighter aggregation. In vitro release testing (IVRT) data showed, by applying and fitting first-order release kinetic models for one or two pools, that curing impacts two significant changes: a 3–5-fold drop in the overall drug release rate and a ten-fold decrease in the ratio between the loosely aggregated and the tightly aggregated, more thermodynamically stable drug pool. The kinetic data thus corroborated the trend independently deduced from the UV–Vis spectral data. The in vitro toxicity assay indicated a decreased toxicity with curing, as shown by the significantly increased concentration, causing half-maximal potassium release (TC50). The data suggest that the release of AmB requires dissociation of the tight complexes within the bilayer and that the reduced toxicity relates to this slower rate of dissociation. This study demonstrates the relationship between AmB aggregation status within the lipid bilayer and drug release (directly measured rate constants), providing a mechanistic link between aggregation status and in vitro toxicity in the liposomal formulations.

[Display omitted] • Electrostatic interactions have the most important role in the adsorption of ILs on the surfaces. • The interaction strength in the pure ILs decreases upon adsorption on the surfaces. • The adsorption of ILs on the surfaces is accompanied by charge transfer from the surfaces to the ILs. • The IL adsorption leads to the decrease of E g and η values and an increase of ω values of the surfaces. • Electron excitation in the IL@surface complexes is generally intra-fragment electron transfer. The adsorption of nine common ionic liquids (ILs) on two well-known structures of graphitic carbon nitride (g-C 3 N 4) nanosheets, including Triazine-g-C 3 N 4 and Heptazine-g-C 3 N 4 has been investigated using density functional theory (DFT) method in gas phase and water solvent. The interactions between the ILs and the nanosheets are characterized by several techniques, such as quantum theory of atoms in molecules (QTAIM) analysis, noncovalent interaction (NCI) plots, and energy decomposition analysis (EDA) method. Interestingly, the obtained results showed that electrostatic interactions have the highest contributions to the interaction energies between the ILs and the surfaces, followed by dispersion interactions and orbital interactions (ΔE elec > ΔE disp > ΔE orb) The most important Van der Waals (vdW) interactions between the ILs and the surfaces include π–π, C H...N, C H...π (C N), and C N...X (X = F, N, O) interactions. On the other hand, the adsorption of ILs is accompanied by charge transfer from the surfaces to the ILs. The calculated adsorption energy (E ads) showed that the [Bmim][PF 6 ] IL has the highest adsorption affinity on the Triazine-g-C 3 N 4 (−28.28 kcal/mol) and Heptazine-g-C 3 N 4 (−26.68 kcal/mol) surfaces. Thermochemistry calculations showed that the E ads , ΔH ads , and ΔG ads values of IL@surface complexes decrease on moving from gas phase to water media. However, our results showed that the adsorption of ILs on the surfaces is still exothermic and proceeds spontaneously. Upon adsorption of ILs, a decrease in the HOMO–LUMO energy gap (E g) is observed and is accompanied by an increase in the reactivity and electrophilic character of the surfaces. TD-DFT calculations showed that the weak adsorption of ILs leads to small red or blue shifts in the absorption bands of the Triazine-g-C 3 N 4 and Heptazine-g-C 3 N 4 surfaces. However, no significant changes are observed in the shape of the absorption spectra of the surfaces. Furthermore, the transition density matrix (TDM) heat maps of the IL@surface complexes showed that the electrons and holes are generally concentrated on the Triazine-g-C 3 N 4 and Heptazine-g-C 3 N 4 surfaces in the IL@surface complexes, signifying that the electronic transitions occur mainly on the surfaces. [ABSTRACT FROM AUTHOR]

Theoretical frameworks play a pivotal role in comprehending the optical characteristics of gold nanorods, providing valuable perspectives on the factors that impact their optical properties. These frameworks play a key role in anticipating how nanorods will perform under different circumstances and in validating experimental findings against theoretical projections. Through the utilization of theoretical frameworks, scientists can efficiently delve into creative nanostructure designs, ultimately enriching our understanding of how gold nanorods react optically for both academic research and practical implementations. The optical behavior of elongated gold spheroids was extensively analyzed using both the quasi-static approximation (QSA) and the Modified Long Wavelength Approximation (MLWA) to gauge their effectiveness in projecting experimental results. While the QSA proves beneficial in specific scenarios, its accuracy tends to be overshadowed by empirical data obtained from UV–visible spectroscopy and helium ion microscopy (HIM). In contrast, the MLWA exhibits a stronger alignment with empirical findings, thus providing a more accurate theoretical groundwork. This alignment implies that the MLWA considers intricacies and variables overlooked by the QSA, establishing it as a more dependable approach for envisaging the optical conduct of such nanostructures. The juxtaposition emphasizes the significance of selecting appropriate theoretical frameworks in the realm of nanoscale optics, with the MLWA emerging as the preferred option for investigations concerning elongated gold spheroids. [Display omitted] • Comparison between theoretical models and experimental findings enhances understanding of optical properties prediction. • The MLWA approach closely aligns with experimental results, highlighting its relevance in nanorods' optical behavior interpretation. • MLWA demonstrates superior predictive accuracy compared to QSA in modeling these interactions. [ABSTRACT FROM AUTHOR]

UV-VIS spectrophotometry is one of the methods used to perform qualitative and quantitative analysis of organic and inorganic compounds. However, until now there has been no further research that studies and describes the detailed analysis of UV-VIS spectral data in terms of determining the structure of chemical compounds. Therefore, this paper contains guidelines that are used as information on how to read and interpret data from the UV-VIS spectrum in terms of determining the structure of chemical compounds. Steps on how to analyze the UV-VIS spectrum are presented. This paper is expected to provide useful information for researchers and novice students who are studying UV-VIS spectrophotometry.

In this report, the real part of ac conductance (Σ(T, f)) of pure ZnO nanoparticle, manganese-doped ZnO nanocapsules and nanoplates was estimated as a component of frequency (f) by shifting zero-frequency Ohmic conductance (Σ0) with the tuning of the temperature (T) to understand the nonlinear AC conduction mechanism in semiconductor. The UV–VIS absorption spectrum showed a change in band gap from 3.67 eV for pure ZnO NPs to 3.31 eV for Mn-doped ZnO NPs with the change in excitonic peak from 372.5 nm for ZnO NPs to 375 nm for Mn-ZnO NPs. The HRTEM and SAED analysis along with XRD showed formation of nanocapsules and nanoplates with hexagonal wurtzite crystal phase. The doped semiconductor nanocrystals showed a 'T' dependent transition nature. Scaling speculations from theoretical models are used to dissect the effects of ac conduction and the nonlinearity exponent (xf) of the onset frequency f c ∼ Σ 0 x f . The overall scaling formalism for the ac conductance Σ0 was properly scaled with a universal curve as per the information for Σ(T,f) under different T. The metallic and semiconductor contribution in the dc conductivity of the doped nanosystems is highlighted. The normalized conductance (Σ/Σ0) as a function of normalized frequency curves was depicted by a single power law for Mn-ZnO nanocapsules and nanoplates. The AC conduction process showed that xf is a lot of phase delicate and can be utilized to describe the phase changes in these doped nanosystems originated due to change in Mn2+ doping concentration. [ABSTRACT FROM AUTHOR]

Photon capture by chlorophylls and other chromophores in light-harvesting complexes and photosystems is the driving force behind the light reactions of photosynthesis. Excitation of photosystem II allows it to receive electrons from the water-oxidizing oxygen-evolution complex and to transfer them to an electron-transport chain that generates a transmembrane electrochemical gradient and ultimately reduces plastocyanin, which donates its electron to photosystem I. Subsequently, excitation of photosystem I leads to electron transfer to a ferredoxin which can either reduce plastocyanin again (in so-called “cyclical electron-flow”) and release energy for the maintenance of the electrochemical gradient, or reduce NADP+ to NADPH. Although photons in the far-red (700–750 nm) portion of the solar spectrum carry enough energy to enable the functioning of the photosynthetic electron-transfer chain, most extant photosystems cannot usually take advantage of them due to only absorbing light with shorter wavelengths. In this work, we used computational methods to characterize the spectral and redox properties of 49 chlorophyll derivatives, with the aim of finding suitable candidates for incorporation into synthetic organisms with increased ability to use far-red photons. The data offer a simple and elegant explanation for the evolutionary selection of chlorophylls a, b, c, and d among all easily-synthesized singly-substituted chlorophylls, and identified one novel candidate (2,12-diformyl chlorophyll a) with an absorption peak shifted 79 nm into the far-red (relative to chlorophyll a) with redox characteristics fully suitable to its possible incorporation into photosystem I (though not photosystem II). chlorophyll d is shown by our data to be the most suitable candidate for incorporation into far-red utilizing photosystem II, and several candidates were found with red-shifted Soret bands that allow the capture of larger amounts of blue and green light by light harvesting complexes.

A new aroylhydrazone ligand, di-2-pyridyl ketone-4-methoxybenzhydrazone (DKMBH·H2O) and its three complexes with cobalt(II), copper(II) and zinc(II), labelled Co(DKMB)Cl (1), Cu(DKMB)Cl (2), and Zn(DKMB)Cl (3) have been prepared and structurally studied. The spectroscopic techniques like IR, UV-Vis, MS, and ¹H NMR, as well as CHN analysis and thermal analysis, have been used to physico-chemically characterize the synthesized compounds. The IR and ¹H NMR analyses have made clear that the aroylhydrazone remains in the amido form in the solid state. The IR spectral measurements further support the tridentate character of the NNO donor aroylhydrazone. In all complexes, pyridine nitrogen, azomethine nitrogen, and iminolate oxygen of the tridentate aroylhydrazone are involved to coordinate to the metal centre. [ABSTRACT FROM AUTHOR]

In the field of cultural heritage, understanding the nature of pigments and dyes is of great importance for conservation issues. Among the many natural dyes used in paintings or textiles, madder was one of the most important sources of red color at the time and was present in a wide variety of objects. However, due to extraction challenges, impurities, and high costs, a lot of information are not easily available. In this publication we designed a computational protocol able to reproduce the spectroscopic properties of two dyes, alizarin and alizarin red S. This framework allows us to compute both Ultraviolet–Visible absorption spectra and Nuclear Magnetic Resonance (NMR) with good accuracy as well as reproduce with precision the CIELAB color. We have also explored different types of interactions that impact these properties, notably the solvation effect. We found that microsolvation is sufficient to reproduce the experimental measurements made in water. The high accuracy of the computation method makes this technique particularly promising for a non-destructive study of dyes on works of art and the preservation of cultural heritage. • Alizarin is the main colored compound of natural Madder. • A computational protocol has been designed to reproduce photo-physical properties. • Solvation models and deprotonated forms can impact UV–Vis and NMR spectra. • The CIE color coordinates can also be predicted with accuracy. • We also tried a more water-soluble analog with success. [ABSTRACT FROM AUTHOR]

Background and Objectives: Quantifying the acid value of stored wheat is of great significance for timely treatment and avoiding waste. For the low‐fat content in wheat, the aim of this study is to propose a microchemical way for the acid value analysis. Findings: Twenty‐four wheat samples are taken from the grain reserve depot and the acid values of them are analyzed by the spectral response of one phthalocyanine dye, tetra‐α‐octoxy substituted zinc phthalocyanine, to a fatty acid. Under the experimental conditions, a linear relation exists between the absorbance of this dye at 749 nm (A749 nm) and the concentration logarithm (lncb) of fatty acid (palmitic acid) in chloroform, R2 = 1.000. Conclusions: By the aforesaid linearity, 1 µl of extracted wheat oil is enough to determine the acid values of wheat samples, which can avoid the interference from the color of the sample in traditional titration. Significance and Novelty: The UV‐visible method has great potential in the actual analysis of the acid value of wheat samples and has important reference value for the analysis of other related agricultural products, food and drugs, and so on. [ABSTRACT FROM AUTHOR]

Nowadays, the incorporation of nanoparticles into thermal fluids has become one of the most suitable strategies for developing high-performance fluids. An unconventional improvement of thermo–physical properties was observed with the addition of 1% wt. of nanoparticles in different types of fluids, such as molten salts, allowing for the design of more thermally efficient systems using nanofluids. Despite this, there is a lack of knowledge about the effect that nanoparticles produce on the thermal stability and the decomposition kinetics of the base fluid. The present study performs IR- and UV-vis spectroscopy along with thermogravimetric analysis (TGA) of pure nitrate and nitrate based nanofluids with the presence of SiO2 and Al2O3 nanoparticles (1% wt.). The results obtained support that nanoparticles accelerate the nitrate to nitrite decomposition at temperatures below 500 °C (up to 4%), thus confirming the catalytic role of nanoparticles in nanofluids. [ABSTRACT FROM AUTHOR]

DFT calculations at B3LYP/6–31 g(d,p) with the D3 version of Grimme’s dispersion are performed to investigate the application of TM-encapsulated Mg12O12 nano-cages (TM = Mn, Fe, and Co) as a hydrogen storage material. The molecular dynamic (MD) calculations are utilized to examine the stability of the considered structures. TD-DFT method reveals that the TM-encapsulation converts the Mg12O12 from an ultraviolet into a visible optical active material. The adsorption energy values indicate that the Mn and Fe atoms encapsulation enhances the adsorption of H2 molecules on the Mg12O12 nano-cage. The pristine Mg12O12 and CoMg12O12 do not meet the requirements for hydrogen storage materials, while, the MnMg12O12 and FeMg12O12 obey the requirements. MnMg12O12 and FeMg12O12 can carry up to twelve and nine H2 molecules, respectively. The hydrogen adsorption causes a redshift for the λmax value of the UV–Vis. spectra of the MnMg12O12 and FeMg12O12 nano-cages. The thermodynamic calculations show that the hydrogen storage reaction for MnMg12O12 nano-cage is a spontaneous reaction while for FeMg12O12 nano-cage is not spontaneous. The results suggested that the MnMg12O12 nano-cage may be a promising material for hydrogen storage applications.

[Display omitted] The synthesis, molecular structure, and electronic properties of sodium tris(phenanthrene-9,10-diolato)germanate(iv) are described. The germanate complex is readily oxidized in air to produce 9,10-phenanthrenequinone, and the resulting quinones and the ligands reveal intermolecular π-stacking interaction in the polymeric association in the solid state. Addition of phenanthroline to the germanate complex leads to a monomeric structure. [ABSTRACT FROM AUTHOR]

Photon capture by chlorophylls and other chromophores in light-harvesting complexes and photosystems is the driving force behind the light reactions of photosynthesis. Excitation of photosystem II allows it to receive electrons from the water-oxidizing oxygenevolution complex and to transfer them to an electron-transport chain that generates a transmembrane electrochemical gradient and ultimately reduces plastocyanin, which donates its electron to photosystem I. Subsequently, excitation of photosystem I leads to electron transfer to a ferredoxin which can either reduce plastocyanin again (in so-called "cyclical electron-flow") and release energy for the maintenance of the electrochemical gradient, or reduce NADP+ to NADPH. Although photons in the far-red (700≥750 nm) portion of the solar spectrum carry enough energy to enable the functioning of the photosynthetic electron-transfer chain, most extant photosystems cannot usually take advantage of them due to only absorbing light with shorter wavelengths. In this work, we used computational methods to characterize the spectral and redox properties of 49 chlorophyll derivatives, with the aim of finding suitable candidates for incorporation into synthetic organisms with increased ability to use far-red photons. The data offer a simple and elegant explanation for the evolutionary selection of chlorophylls a, b, c, and d among all easily-synthesized singly-substituted chlorophylls, and identified one novel candidate (2,12-diformyl chlorophyll a) with an absorption peak shifted 79 nm into the far-red (relative to chlorophyll a) with redox characteristics fully suitable to its possible incorporation into photosystem I (though not photosystem II). chlorophyll d is shown by our data to be the most suitable candidate for incorporation into far-red utilizing photosystem II, and several candidates were found with red-shifted Soret bands that allow the capture of larger amounts of blue and green light by light harvesting complexes. [ABSTRACT FROM AUTHOR]

In the present work, we have synthesized new molecular hybrids consisting of porphyrin ring system connected at the meso positions with phenyl groups and/or, through p-phenylene linkers, with 1,4-dihydropyridine or pyridine moieties. In general, the directed use of dihydropyridine aldehyde, under time-modified Adler–Longo procedures, gave the best overall yields of the following meso-substituted dihydropyridine-porphyrins of general formula A1B3, A2B2, or A4, where A stands for phenyl-dihydropyridine and B for phenyl substituents. The corresponding meso-substituted pyridine-porphyrin hybrids were obtained from oxidation of the dihydropyridineporphyrins with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The UV-vis spectra bands of the A4 dihydropyridine-porphyrin were unexpectedly red-shifted, having a rhodoporphyrin Q-bands profile. It was also found that an increased production of 1O2 correlates with a higher number of dihydropyridine or pyridine moieties in the hybrid molecule. All porphyrin hybrids were considered adequate candidates to be employed in photodynamic therapy. [ABSTRACT FROM AUTHOR]

Coagulation and flocculation are two of the steps in the water treatment process in which chemical coagulants based on iron salts or aluminum are used. In order to replace the aluminum or to reduce the concentration of the metal, several natural alternatives to assist in the coagulation/flocculation process have been evaluated, including the use of Abelmoschus escuentus Moench (okra) as a flocculating agent. To determine the degradation time of the okra solution, spectral measurements were performed on the UV–Vis region. The coagulation/flocculation tests were carried out in a jar test equipment, using aluminum polychoride as a coagulant, 1-mgL−1 okra solution as a flocculation aid, and the alkalinizing hydroxide of calcium. Through the spectral measurements and the test in the jar test, it was possible to verify that the solution of the okra remains stable only until the time of 24 h, and after this time, begins the degradation process of the constituents of the okra that promote the flocculation of it. In addition, satisfactory results were obtained in the treatment of water in 24 h, allowing the use of okra as flocculation aid and aluminum polychloride coagulant, as in effluent color removal, with an efficiency of 91 to 96%, and organic matter removal, with an efficiency of 92 to 93.5%. [ABSTRACT FROM AUTHOR]

[Display omitted] • The stability of standard nitric oxide solution is possible to study by UV–Vis spectrometry. • It is possible to observe changes over the 365 days' observation as well as during one-day observation in dependence on the nitric oxide solution "age" (presence of oxygen - under air-equilibrated conditions). • Nitrous acid tetrad appeared after one week and disappeared after three months. • Peak of nitrate ion appeared after one month, and it grew for the next two months. • The spectrum of nitrate ions has been stable for the rest of the year. The stability of standard nitric oxide solution can be observed by UV–Vis spectrometry; it is possible to observe changes over 365 days of storage but also over one day under air-equilibrated conditions. Nitrous acid tetrad appeared after one week and disappeared after three months; the peak of nitrate ions appeared after one month and grew for the next two months, it reached the maximum when the nitrous acid tetrad disappeared, and the spectrum of nitrate ions was stable for the rest of the year. [ABSTRACT FROM AUTHOR]

Aurones are a small subclass of the flavonoid family known primarily for their unusual structure and the golden yellow color they impart to the flowers of snapdragons and cosmos. Most studies of aurones focus on their range of biological activities, but relatively little has been reported with respect to their optical properties, unlike their aza and thio analogs. What little is known has focused entirely on the influence of the benzylidene portion. In this study, the influence of substitution in the benzofuranone ring on the UV–vis spectrum is explored, as well as an initial screening of their toxicity and a qualitative preliminary study of their potential to act as fabric dyes.

DFT and TD-DFT calculations are employed to examine the adsorption of halogen atoms (F, Cl, and Br) and molecules (F2, Cl2, and Br2) on cobalt-doped porphyrin (CoP). The impact of an external static electric field (EF) on the adsorption and the UV–Vis spectra is studied. The adsorption of halogen atoms as well as F2 molecule is chemisorption in the range from −1.14 to −2.41 eV while the adsorption of Cl2 and Br2 is physisorption. The adsorbate–substrate interaction reduces the HOMO-LUMO gap (Eg) to be 1.79–2.72 eV compared to 3.11 eV for CoP. The EF controls the adsorption process where the positive EF improves the corrected adsorption energy (Eadscorr.) while the negative EF attenuates the Eadscorr.. Additionally, the positive EF leads to a decrease in the Eg while, the negative EF increases the Eg. Consequently, for sensing purposes, high sensitivity and low response time are expected for the CoP at the positive EF while negative EF encourages the desorption process and decreases the recovery time. The CoP is optically active with λmax of 494 nm. The UV–Vis spectra analysis shows that the adsorption of halogen atoms causes a blue shift of λmax to be 394, 488, and 491 nm while the adsorption of halogen molecules causes a red shift of λmax to be 892, 846, and 698 nm, respectively. The λmax for adsorbate–substrate complexes is affected by the EF. Our results declare that the cobalt-doped porphyrin may be utilized as a candidate sensor for the considered halogen atoms and molecules.

The reaction of 5,6‐dicyano‐4,7‐diethylbenzo[1,2,3]trithiole (1) with trichloroborane in p‐xylene and subsequent substitution of the chloro group with phenol produced boron (III) subphthalocyanine 2 with three trithiole rings. Upon treatment of 1 with trichloroborane in p‐xylene in the presence of unsubstituted phthalonitrile or tetrafluorophthalonitrile, unsymmetrical subphthalocyanines 3, 4, 6, and 7 with one or two trithiole rings were obtained after the reaction with phenol. The Q‐band absorption of 2 appeared at λmax=611 nm in the UV‐vis spectrum and the emission was observed at λe=630 nm. Decreasing the number of fused trithiole rings and ethyl groups resulted in higher energy shifts of the Q‐band absorption in the UV‐vis spectra and downfield chemical shifts of the 11B NMR signals. Compounds 2, 3, and 4 were treated by pentachloro antimonate in dichloromethane, the solution of which showed strong ESR signals. The structures of simplified model compounds were optimized using the DFT method with the Gaussian 09 program at the B3LYP/6‐31G (d, p) level. [ABSTRACT FROM AUTHOR]

Two new picolinate complexes, namely diaquabis(6-chloropyridine-2-carboxylato-N,O)cobalt(II) (1) and diaquabis(6-chloropyridine-2-carboxylato-N,O)manganese(II) (2) were synthesized. These complexes were all characterized using FT-IR and UV–Vis spectra, single crystal X-ray diffraction method and thermal analysis. Both complexes have similar molecular structure characterized as distorted octahedral geometry. B3LYP level was also executed to provide a deeper insight to the structural, electronic and nonlinear optical properties of 1 and 2. The detailed vibrational analysis was performed for 1 and 2 on the basis of potential energy distribution (PED) analysis. The natural bond orbital (NBO) energies between the lone pair electrons of donor N/O atoms and anti-lone pair electrons of Co(II) and Mn(II) ions also proved the distorted octahedral geometry for both complexes. The band gap energy values for the allowed direct transition are found 4.29 and 4.26 eV by using Tauc model for complex 1 and 2, respectively. Finally, the optical conductivity (σopt), electrical conductivity (σelec), the third-order nonlinear optical susceptibility χ(3), the molar polarizability αp and dielectric property are determined for the title complexes in the UV–Vis region. The first-order hyperpolarizability (β) parameter for 2 was obtained as higher than that of 1 due to the high spin electronic configuration of Mn(II) central ions [ABSTRACT FROM AUTHOR]

The effect and mechanism of the combined process of semi-aerobic aged refuse biofilter (SAARB) and ozone oxidation on landfill leachate degradation were investigated. While SAARB pretreatment alone could remove most of the organics, especially 99.97% ammonia (NH4 +-N), high concentrations of biorefractory organics such as humic acids and fulvic acids were noted in the SAARB-pretreated leachate. Therefore, a subsequent ozone oxidation treatment was performed, which achieved 34.3% chemical oxygen demand (COD), 44.1% UV254, and 67.6% color number (CN) removal efficiencies, respectively. Furthermore, the UV-vis spectroscopy and three-dimensional fluorescence spectrum analyses demonstrated that refractory organics (i.e., aromatic compounds) in SAARB-pretreated leachate were substantially degraded and removed after ozone oxidation process, leading to a significant decline of humification in the leachate. Overall, the combined process of SAARB and ozone oxidation showed a complementary effect on the removal of organics and NH4 +-N from landfill leachate, and could achieve 95.0% COD, 99.5% CN, 98.2% UV254, and nearly 100.0% NH4 +-N removal efficiencies. [ABSTRACT FROM AUTHOR]

In this study, we want to characterize egg white protein-tomato extract complex based on the UV-Vis spectrum. The formulation of antioxidant complex Non-Freeze-drying (NFD) was made at a ratio of 1:10 (v/v) while the Freeze-drying (FD) sample was made at a ratio of 1:2 (v/v). The results showed that the absorption peak of FD complex profile value was lower than the single ingredient, while the tomato extract was higher than the complex profile. On the contrary, the NFD complex showed a higher peak absorption value than to every single ingredient. Based on each UV-Vis spectrum profile, the tomato extract profile shifted the absorption peak, and the absorbance value of the FD sample was changing higher than the NFD sample, while the egg white protein spectrum profile did not change significantly in the FD and NFD samples. The absorption peak of the complex is higher than the single ingredient indicated that the characterization of the complex had been formed. In the NFD complex profile, the absorption peaks formed at the wavelength regions of 230 nm and 280 nm with absorbance values of 2.51 and 0.76 and its number has higher than those of the FD complex with absorbance values of 2.47 and 1.82 at wavelengths of 220 and 265 nm. [ABSTRACT FROM AUTHOR]

[Display omitted] • Increasing the length of the D-A linker leads to a decrease in E b but increases planarity. • The introduction of PC71BM units creates more CT channels and lowers E b. • The simulated electronic absorption spectrum of dyad 4 is enhanced with respect to the others. Small-molecule single-component organic solar cells (SM-SCOSCs) have great potential for commercial application. However, the effects of changes of donor–acceptor linker length and acceptor unit of small molecules of active layers on their photoelectric properties are still not well understood. In this work, four state-of-the-art dyads 1–4 were selected to investigate these effects since dyad 4 created the highest power conversion efficiency (PCE) of 5.34% of SM-SCOSC; and their electronic structures were investigated. The results indicate that increasing the length of the donor–acceptor connecting bridge leads to a decrease in exciton binding energy, and so does replacing the acceptor component PC61BM with PC71BM. Furthermore, the simulated electronic absorption spectrum of dyad 4 is enhanced with respect to others. We also find that the introduction of PC71BM creates more channels for transitions from local excited states to charge transfer states. This work gains a deep insight into the relationship between molecular structure and performance of SM-SCOSC. [ABSTRACT FROM AUTHOR]

Accurate characterization of melanin using analytical methodologies has proved to be difficult due to its heterogeneity, insolubility in wide pH and broad range of solvents. The present study was undertaken to characterize melanin extracted from an environmental Aspergillus fumigatus AFGRD105 by studying its genes, chemical properties and spectral data. A gene based approach to confirm the type of melanin carried out indicated the extracted melanin to be of the dihydroxynaphthalene type. On comparison with synthetic melanin, UV–Vis and IR spectra of the extracted melanin revealed characteristic peaks that can be further used for confirmation of DHN-melanin extracted from any source. Solid state 13C NMR spectroscopy established the presence of the hydroxyl-naphthalene moiety and validated the results obtained by genetic analysis. The correct assignment of the observed spectral frequency characteristic of functional groups can be further adapted in future works that deal with binding capacities and biomolecule systems involving melanin.

Selenium nanoparticles have been widely used in the various areas especially in medical field for its anticancer and immune modulatory properties. To reduce the toxic chemicals released by chemical process, the present work was aimed at synthesis of selenium nanoparticles by microbes. In this study, microbes were isolated from soil samples from different areas of Bangalore and screened for the antioxidant activity by DPPH assay. The organism with highest antioxidant activity (IC50 value = 11.6µg/mL) was identified as Bacillus species. Under experimental conditions, this microbe along with sodium selenite synthesised selenium nanoparticle indicated by the colour change of the medium to reddish orange. The synthesised selenium nanoparticles were further characterised. From UV-Vis spectrophotometry, the maximum peak was obtained at 266.5nm. The FT-IR analysis showed peaks at different wavelengths with the maximum of 3200cm-1 showing the presence of alcoholic group. The shape and size of the selenium nanoparticles was also calibrated by SEM analysis as oval and 209nm-748nm respectively. The nanoparticles were further analysed for antimicrobial assays by well diffusion method against E. coli, S. aureus, P. aeruginosa, St. mutans and antifungal assay against the strains of C. albicans, A. niger and A. flavus. The highest zone of inhibition was observed against E.coli (1.7 cm) at a concentration of 400µg and maximum for C. albicans (2.5cm) at a concentration of 400µg. Microbial synthesized nanoparticles emerges as a promising medicine in curing different disorders because of its potent antioxidant and antimicrobial activity. [ABSTRACT FROM AUTHOR]

Radiation is energy travelling through space. Sunlight radiation such as ultraviolet (UV) radiation are higher-energy radiation which are used in medicine and energy industry such as dye sensitized solar cells (DSSCs). We recently designed new Ru-complexes through novel ligands based on a recently synthesised high performance dye, i.e. [(η6-p-cymene)Ru(4,4′,5,5′-H4tcbpy)Cl]Cl [1] (A as L1-Ru-L2) for applications in DSSCs. Two electron rich top-ligands, η6-N, N, N′, N′-tetramethyl-p-phenylenediamine (new dye D) and η6- 1,4 di[(dimethylamino)ethyl] benzene (new dye E) outperform other ligands for the new high performance Ru-complexes. Our time dependent density functional theory (TD-DFT) using the CAM-B3LYP/6-311G+(d)/LANL2DZ functional and basis-set model reveals the apparent enhancement of the major UV–vis bands of metal to ligand charge transfer (MLCT) in the new dyes. The major UV–vis bands of the new dyes D and E are red shifted 35 nm and 78 nm, respectively, from the MLCT band of the reference dye A centred at 433 nm. We further discovered that the electron rich top-ligands (L1) are responsible to lift a cluster of occupied outer valence orbitals such as HOMO, HOMO-1 and HOMO-2 in the new D and E complexes, while the virtual orbitals which concentrate on the lower ligand L2 (4,4′,5,5′ H4 tcbpy) remain almost unchanged. The top-ligand L1 enhances the MLCT transition of the new dyes D and E through the dominant 7dz2 electrons of the transition metal Ru in their HOMOs. The present study provides the rational of ligand control for metal complexes in broader applications such as electron transfer and electronics. [ABSTRACT FROM AUTHOR]

Photochemical systems are an alternative to reduce the biological and chemical contaminants persistent in hospital wastewater treatment. Although the photochemical systems are currently used in wastewater treatments, the efficiency of these systems still needs to be studied. In this work, a broadband method to evaluate the efficiency of photochemical systems: UV/H2O2, UV/O3, and UV/H2O2/O3, for hospital wastewater treatments is presented. The method is based on the analysis of the broadband changes in the UV-Vis absorption spectra with the real-time radiation exposure. The results presented indicate that the UV/H2O2/O3 system has a higher percentage of decontaminated water and decontamination speed than the UV/H2O2 and UV/O3 systems. In this regard, the proposed method provides a good alternative to evaluate the efficiency of photochemical systems used in hospital wastewater treatments. [ABSTRACT FROM AUTHOR]

Abstract Cyclophanediene (CPD)-dihydropyrene (DHP) is a negative T-type photochrome pair having a thermodynamically stable colored form, i.e. , DHP. Interconversion between cyclophanediene and dihydropyrene is associated with significant changes in dipole moment, absorption wavelength and polarizability, which can impart substantial linear and nonlinear optical response. In this study, phototunable linear and nonlinear optical response of cyclophanediene-dihdyropyrene photoswitches is described. Cyclophanedienes and dihydropyrenes are functionalized at the internal position for maximum changes in volume and polarizability. The UV–Vis spectra are calculated at ɷB97XD, which was validated through a benchmark approach. An excellent correlation is observed between theoretical and experimental absorption spectra. Several CPD-DHP pairs have been recognized for clean interconversion in UV–Vis light without formation of a photostationary state. Nonlinear optical response of dihydropyrenes is remarkably higher than that of cyclophanedienes. In general, the calculated hyperpolarizability values of dihydropyrenes are about two to three orders of magnitude higher than those for cyclophanedienes. The trends in calculated hyperpolarizabilities are rationalized through two level method. The high nonlinear optical response of dihydropyrenes stems from low excitation energies. The remarkable difference in hyperpolarizabilities of these isomeric forms paves path for the design of phototunable nonlinear optical materials. Graphical abstract Image 1 Highlights • The UV–Vis spectra of CPD-DHP pairs are studied experimentally and theoretically. • Cyclophanedienes-dihydropyrenes are excellent photo tunable NLO contrast switches. • Hyperpolarizability of DHPs is two to three orders of magnitude higher than CPDs. • The NLO switch can be reversed by functional group modifications. • The trends in hyperpolarizabilities are rationalized through two level method. [ABSTRACT FROM AUTHOR]

π-Electron systems of silicon have attracted attention because of their narrow HOMO-LUMO gap and high reactivity, but the structural diversity remains limited. Herein, new dialkylboryl-substituted disilenes were synthesized by the selective desilylation-borylation of the corresponding trimethylsilyl-substituted disilenes. The dialkylboryl-substituted disilenes were fully characterized by a combination of NMR spectroscopy, MS spectrometry, single-crystal X-ray diffraction analysis, and theoretical calculations. The longest-wavelength absorption bands of boryldisilenes were bathochromically shifted compared to the corresponding silyl-substituted disilenes, indicating a substantial conjugation between π(Si=Si) and vacant 2p(B) orbitals. In the presence of 4-(dimethylamino)pyridine (DMAP), the dialkylboryl groups in the boryl-substituted disilenes were easily converted to trimethylsilyl groups, suggesting the dialkylboryl-substituted disilenes in the presence of a base serve as the surrogates of disilenyl anions (disilenides).

[Display omitted] • The unmixing method in the remote sensing field was transferred and improved to identify water pollution sources for the first time. • The UV–VIS spectra of surface water samples are used for the source abundance inversion. • The proposed automatic encoder algorithm for radial basis bilinear hybrid model structure has higher precision than the traditional unmixing algorithm. Water resources are one of the most important strategic resources for human survival and development. At present, surface water pollution incidents occur frequently, most of which are caused by enterprises' over-discharge, stolen discharge, and other activities to evade supervision. Automatic and rapid determination of pollution source types is conducive to further targeting pollution-causing enterprises and realizing scientific accountability in law enforcement. The existing method mainly adopts the pattern recognition method for pollution discrimination, which is only suitable for the situation of a single source of pollutant, and cannot identify the pollution for multiple pollution sources mixed surface water. To solve the problem of identification of mixed chemical pollutants in surface water pollution sources and identification of simultaneous emission of multiple pollution sources, a total pollution source analysis method based on spectral unmixing is proposed in this paper, which is a radial basis bilinear mixing model automatic encoder algorithm. The unsupervised autoencoder neural network method was used to solve the proportion of water pollution types by using the spectral database of water pollution sources to realize the identification function of water pollution types and determine the types of pollutant discharge enterprises. In this paper, surface water was collected as experimental samples, mixed with domestic sewage, industrial sewage, agricultural sewage, and other pollution sources, and simulated experiments were carried out to estimate the type and proportion of water pollution. Experimental results show that the detection accuracy of the proposed algorithm is significantly improved compared with the traditional algorithm. Among them, the accuracy of judging whether there is industrial sewage in the mixed experiment of three types of pollution is as high as 95.2%. This method provides an important basis for pollution source investigation and accountability. [ABSTRACT FROM AUTHOR]

Solar energy and its conversion to electricity is an important research in the last decade. Solar cells are consist of a p-type semiconductor as donor and an n-type semiconductor as acceptor. Organic polymers as organic semiconductors are used in an organic solar cell. This research is a theoretical investigation of fullerene C60 as donor and C60 doped derivatives with Silicon and Germanium atoms as acceptors for basic structure of a solar cell. This research is done not only with using related equations but also with investigating theoretical UV-Vis spectrum of the chosen donors-acceptors and their absorption wavelengths, oscillator strength and maximum coefficient absorptions of these solar cells. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The complex La{CS(NH 2) 2.CO (NH 2) 2 }Cl 3 crystallizes into orthorhombic structure. • Exhibits 96% transmittance with 277 nm as cut off wavelength. • The photon energy 4.0–4.68 eV is the band gap of the complex. • Correlated barrier hoping mechanism dominates the conduction process. Abstract A hybrid complex of lanthanum chloride with urea and thiourea is crystallized at room temperature by conventional solution method. The structural investigations by single crystal X-ray diffraction confirmed the orthorhombic system with cell dimensions a = 7.676 Å, b = 8.564 Å, c = 5.498 Å, α = β = γ = 90°. The optical studies by UV–VIS absorption spectroscopy shows the complex exhibits transmittance about 96%. The complex is characterized as the wide band gap crystals with value greater than 4 eV. The dielectric properties were studied in frequency range 10 kHz–1 MHz in temperature range 303–453 K. The ac conductivity was found to obey the universal power law and suggests the correlated barrier hoping mechanism dominating the conduction process. The thermal stability and the decomposition mechanism were confirmed by thermo gravimetric and differential thermo analytical (TG/DTA) techniques. [ABSTRACT FROM AUTHOR]

A multi-hydroxyl Schiff-base derivative, N -2′-hydroxyl-1′-naphthyl methylene-2-amino phenol (HNMAP), was synthesized and characterized by FTIR, 1 H NMR and UV–vis spectroscopy. It was noted to find there was great effect for solvent and pH on the UV–vis spectroscopy of HNMAP. Especially, some metal ions could make its UV–vis spectra changed regularly with different time-resolved effects. For example, a real-time and multi-wavelength response to Fe 2+ at 520 nm, 466 nm and 447 nm and a quite slow one about 26 min to Fe 3+ at 447 nm and 466 nm, respectively. Under the optimized conditions, the changes in the corresponding absorption intensities at above wavelengths were in proportion to c Fe 2+ or c Fe 3+ during respectively partitioned linear ranges, which realized to quantitatively detect Fe 2+ or Fe 3+ with a large linear range more than two orders of magnitude. A 1:1 complex mode for HNMAP-Fe 2+ and 1:2 for HNMAP-Fe 3+ were proposed from UV–vis spectral titration and Job's plot. HNMAP would be a potential sensor for colorimetric detection of Fe 2+ and Fe 3+ in practice. [ABSTRACT FROM AUTHOR]

Dioxin is a highly toxic and caustic substance, which widely existed in the atmosphere, soil and water with tiny particles. Dioxin pollution has become a major problem that concerns the survival of mankind, which must be strictly controlled. The bond length, bond angle, energy, dipole moment, orbital energy level distribution of dioxin under the external field are investigated using DFT (density functional theory) on basis set level of B3LYP/6-31G (d, p). The results indicate that with the increase of the electric field, the length of one Carbon-Oxygen bond increases while another Carbon-Oxygen bond decreases. The energy gradually decreases with the electric field, while the change of the dipole moment has an opposite trend. In the infrared spectra, the vibration frequency decreases with the electric field increasing and shows an obvious red shift. Moreover, the ultraviolet-visible absorption spectra under different electric fields are analyzed with TD-DFT (time-dependent density functional theory) method. The wavelength of the strongest absorption peak increases and occurs red shift with the increase of the electric field. All the above results can provide reference for further research on the properties of dioxin under different external electric field. [ABSTRACT FROM AUTHOR]