Strong UV Absorption Research Articles

Strong UV absorption by nanoparticulated lignin in polymer films with reinforcement of mechanical properties

In this paper, we report about function of nanoparticulated lignin derivative as a UV absorber for polymer films. The lignin derivative obtained by simultaneous enzymatic saccharification and comminution (SESC lignin) exhibited strong UV absorption in a poly(vinyl alcohol) matrix without dramatically affecting its transparency. Furthermore, a small amount of SESC lignin simultaneously acted as a mechanical/thermal enhancer of the polymer film. The presented UV absorption system does not require toxic additives; i.e., the SESC lignin is expected for utilization as a UV absorber in food/medicine packaging films. Furthermore, the SESC lignin can be prepared via an environmentally friendly process. Therefore, the strong UV absorption property of the SESC lignin not only promotes the utilization of plant biomass as a high-value industrial material but also reduces the environmental load caused by heatproof materials derived from toxic petroleum-based resources.

A novel bis(terpyridine) with π−conjugated phenyl viologen and its metallo- supramolecular polymers: Synthesis and electrochromism

A novel phenylene viologen functionalized bis(terpyridine) is synthesized and characterized with 1HNMR and Maldi-tof-MS. This rod-like and π-conjugated molecule, 1,1'-[4'-(4-phenyl)-2,2:6′,2″- terpyridine-4,4′-bipyridine-1,1′-diium dichloride (TPV+22Cl−), synthesized by Zincke reaction of 4'-(4-aminophenyl)-2,2:6′,2″-terpyridine with 1,1′-bis (2,4-dinitrophenyl)-4,4′-bipyridine,1,1′-diium dichloride, exhibited strong absorption and fluorescence in wide UV and visible wavelength range. It complexes with Fe- and Ru- ions and can self-assemble into metallo-supramolecular polymers in solution, which can be coated on ITO-glass. The electrochemical characteristics of TPV+22Cl− and its Fe-TPV+2-BF4 supramolecular polymer in solution were studied with cyclic voltammetry. Four different color states, colorless (transparent), purple, reddish brown and grayish green, were observed in a cycle of redox reaction during the cyclic voltammetry scanning. A simple liquid electrochromic device with the Fe-TPV+2-BF4 supramolecular polymer film as working electrode, and with LiClO4 aqueous and K3Fe(CN)6, was fabricated. It can be colored/bleached reversibly between purple and green-yellowish colors by switching the applied voltage from 0 to 0.8 V. The π-conjugation among the bis(terpyridine)s and the phenylene viologen leads the subunits electronically and chemically connected. This interesting viologen functionalized bis(terpyridine) dye will find applications in wide ranges.

Optical absorption in polycrystalline PETN, RDX, HMX, CL-20 and HNS and its possible effect on exploding bridgewire detonator function

ABSTRACT Exploding bridgewire (EBW) detonators work by bursting a thin conducting wire as a result of a high voltage discharge. This process is known to produce a strong UV emission. The roles of optical absorption, photochemistry, shock sensitivity, and impact sensitivity are assessed with respect to the relative roles each plays in the operation of an EBW detonator. The optical absorptivity and penetration depth have been measured using dilute polycrystalline samples of PETN, RDX, HMX, CL-20 and HNS in KBr between 190 and 1100 nm. The results show strong absorption at UV wavelengths with a gradual decline at longer ones. It is found that while strong UV absorption appears to be necessary, it is not sufficient to make an effective EBW detonator.

Crystal structure and photoluminescence properties of garnet−type as−synthesized and aged Li7La3−xZr2O12:xTb phosphors

The crystal structure and photoluminescence (PL) properties of Tb3+−activated garnet−type Li7La3−xZr2O12 garnet phosphors are reported. As−synthesized Li7La3−xZr2O12:xTb (0.02 ≤ x ≤ 0.10) phosphors form a tetragonal crystal structure and emit efficient green light due to the 5D4 → 7F5 transition of Tb3+. On the other hand, aged Li7La3−xZr2O12:xTb phosphors form mixed tetragonal and cubic crystal structures and contain a small amount of Li2CO3. The aged LLZO:xTb phosphors are brownish due to the oxidation of Tb3+ to Tb4+. The Tb4+ ions act as quenching sites for Tb3+ green emission owing to their strong absorption in UV–visible region. The aging significantly degrades emission intensities and color quality due to the presence of Tb4+ and Li2CO3.

Spectra and Photorelaxation of Hydroxyphenyl-benzotriazole-Type UV Absorbers: From Monomers to Nanoparticles.

Water-insoluble organic UV filters such as 2,2'-methylene-bis-(6-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol) (MBBT) can be prepared as aqueous dispersions of nanoparticles. The particles consist of the respective UV absorber molecules and show strong UV absorbance. Because there is a certain solubility of such UV absorbers in organic solvents, it is possible to measure the absorbance spectrum in solution also, for instance, in ethanol or dioxane. The UV spectrum of the aqueous dispersion shows a significant bathochromic shift of the long-wavelength band with an additional shoulder. For the understanding of the observed changes of UV-vis spectra of this UV absorber, either dissolved in an organic solvent or dispersed as nanoparticles in water, density functional theory (DFT) calculations were carried out with the respective monomer and aggregates of MBBT molecules in different media. The calculated UV-vis spectra of isolated, that means dissolved, MBBT molecules in ethanol and in dioxane agree well with the experimentally observed ones. The observed changes in the shape and position of experimental UV-vis spectra in aqueous dispersion cannot be explained with the solvent effect alone. It was found that the studied molecules could form stable energetically favorable π-stacked dimers, which show UV-vis spectra in reasonable agreement with those experimentally observed in aqueous dispersion. Such aggregates of MBBT are most likely the reason for the observed bathochromic shift in the UV-vis absorption spectrum. In addition, the mechanism of the photochemical deactivation of the excited MBBT molecules was studied in detail with time-dependent DFT in dioxane and in water. The energetically most favorable pathway for the deactivation of absorbed energy by MBBT occurs through intramolecular enol-keto tautomerization in the first excited singlet state.

Influence of alkali hydroxides on synthesis, physico-chemical and photoluminescence properties of zinc oxide nanoparticles

ZnO nanoparticles (NPs) have been synthesised by co-precipitation method using zinc nitrate in the presence of two different alkali hydroxides. The XRD analysis of as-prepared products, before and after washing demonstrates its importance in removal of the water soluble nitrates of alkali metals formed during co-precipitation. The X-ray diffraction patterns of the synthesised ZnO NPs confirm the formation of ZnO with hexagonal wurtzite phase. The ZnO NPs synthesised, as confirmed by the XRD pattern, in the presence of NaOH show comparatively smaller crystallite size. These quasi-spherical ZnO NPs show strong UV absorption and dominant visible PL emission, suitable for biomedical and photocatalytic applications.

3D paper-based microfluidic device: a novel dual-detection platform of bisphenol A.

A novel platform of microfluidic paper-based analytical devices (μPADs) for dual detection of bisphenol A (BPA), a model analyte, was fabricated using an electronic digital plotter to create the stacked layer of μPADs and generate the lateral-flow channel without using an external pump. Two detection techniques, including electrochemical detection and laser desorption ionization mass spectrometric detection (LDI-MS), were used complementarily to improve the precision in the detection of BPA. The fluid sample was delivered to both detection zones by the capillary action, automatically generated from the fabricated microfluidic device. For an electrochemical sensor, two ballpoint pens filled with silver nanoparticles (AgNPs) and multiwall carbon nanotube (MWCNT) ink were used to print onto the paper with a contact printing method using a digital plotter. To further improve the sensitivity, zinc oxide (ZnO) was used to modify both electrochemical and LDI-MS detection zones. For BPA detection, high electrocatalytic properties and strong UV absorption of ZnO promote the electron transfer in the electrochemical sensor and ionization efficiency in LDI-MS with low interferences compared with a conventional organic matrix. Under optimal conditions, this platform showed a dual detection capability for BPA with a detection limit of 0.35 μM for electrochemical detection and with an ultralow detection limit of 0.01 pM for LDI-MS. This novel platform might be very useful for trace analyses requiring high precision detection of various analytes.

Ultraviolet shielding properties of cotton fabric supported by titanium-calcium hydroxyapatite solid solution particles

Titanium-calcium hydroxyapatite (TiCaHap) particles were tried to be prepared by a wet method using starting solution with the ratio of Ti/(Ti + Ca) (denoted as [XTi]) from 0 to 1 and pure TiCaHap particles were obtained from the condition with [XTi] from 0 to 0.10. The particles were characterized by field emission scanning electron spectroscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and spectrophotometry. Ultraviolet-visual (UV-vis) spectroscopy revealed that TiCaHap particles exhibit strong UV absorption under 380 nm. The UV absorption increased with an increase in concentrations of Ti4+. The TiCaHap prepared with [XTi] = 0.05 was supported on cotton fabric. The UV shielding ability of the cotton fabric was enhanced by the addition of the TiCaHap particles. The influences of pre-treatment using a cationizing agent and washing with water or a sodium dodecyl sulfate solution for the cotton fabrics were also discussed.

Absolute Configuration of Mycosporine-Like Amino Acids, Their Wound Healing Properties and In Vitro Anti-Aging Effects.

Mycosporine-like amino acids (MAAs) are water-soluble metabolites, reported to exhibit strong UV-absorbing properties. They have been found in a wide range of marine organisms, especially those that are exposed to extreme levels of sunlight, to protect them against solar radiation. In the present study, the absolute configuration of 14 mycosporine-like-amino acids was determined by combining the results of electronic circular dichroism (ECD) experiments and that of advanced Marfey’s method using LC-MS. The crystal structure of a shinorine hydrate was determined from single crystal X-ray diffraction data and its absolute configuration was established from anomalous-dispersion effects. Furthermore, the anti-aging and wound-healing properties of these metabolites were evaluated in three different assays namely the inhibition of collagenase, inhibition of advanced glycation end products (AGEs) and wound healing assay (scratch assay).

CaS:Eu2+@CaZnOS:Mn2+: A dual-UV/green-excited and dual-red-emitting spectral conversion with all-weather resistance

To pursue green ecological agriculture, long-life functionalized green house is looking for solar spectrum conversions with well spectral match, outstanding thermal and chemical stabilities, excellent anti-photobleaching and UV-conversion performance. CaS:Eu2+-based phosphors are widely known as a candidate for agricultural films with remarkable green-to-red conversion performance while they are also notorious for poor stabilities. In this work, a core-shell structured CaS:Eu2+@CaZnOS:Mn2+ composite phosphor was synthesized by a two-step solid state method. The coating layer of thermally and chemically inert oxysulfide prevents the sulfide core phosphor from hydrophilic, air-sensitive and heat-induced decompositions. Moreover, the addition of Mn2+ in CaZnOS shell qualifies the composite phosphor with strong UV absorption, which contributes to the improvement of the anti-photodegradation of the inner CaS:Eu2+ and the anti-aging of practical polymer films. The additional UV-to-orange red conversion resulting from CaZnOS:Mn2+ further extends the red components for the indoor plants. As a result, this dual UV/green excited and dual red-emitting super stable chalcogenide phosphor can be used as a general spectral conversion for plant cultivation.

A renewable dynamic covalent network based on itaconic anhydride crosslinked polyglycerol: Adaptability, UV blocking and fluorescence

An adaptive dynamic covalent network with UV blocking and fluorescence is prepared by crosslinking hyperbranched polyglycerol (HPG) with itaconic anhydride (IA) via esterification. The abundant hydroxyl groups and ester linkages in the resulting polymer (HPG/IA) afford the dynamic transesterification at elevated temperatures and enable adaptive behaviors such as stress relaxation and reparability. Because the double bonds of IA are purposely reserved in the crosslinked network, the HPG/IA exhibits excellent UV blocking due to the strong UV absorption of the double bonds. HPG/IA also exhibits strong glass adherence. With a OH/anhydride ratio of 4/1, HPG/IA displays an adhesion shear strength to glass of ~30 kPa, which is explained by the flexible structure that ensures a good contact of the polymer film with glass and the high dielectric constant that favors accumulation of electrostatic charges. Interestingly, HPG/IA exhibits strong fluorescence (FL) under UV light, and the FL of HPG/IA exhibits strong selective quenching with respect to Fe3+. These unique properties make HPG/IA a promising functional material for UV blocking glass film and fluorescent Fe3+ sensor.

Characterization of MB-102, a New Fluorescent Tracer Agent for Point-of-Care Renal Function Monitoring

MB-102 is a fluorescent tracer agent designed for measurement of point-of-care glomerular filtration rate (GFR) and is currently in clinical studies. MB-102 possesses a strong UV absorbance at 266 nm and 435 nm, and broad fluorescent emission at ~560 nm when excited at ~440 nm. The MB-102 formulation is stable at 2°C-8°C for >3 years. The pKa's of the 2 acid groups are 2.71 and 3.40. Both X-ray crystallography and HPLC confirmed the D, D chirality of MB-102 in solid, in solution, and in the drug formulation. Initial safety and toxicity was published previously [Bugaj and Dorshow, 2015], which enabled the commencement of clinical studies. In vitro studies showed that 4.1% of MB-102 is bound to human plasma proteins, compared to 6.0% for the accepted standard GFR agent iohexol. The blood-to-plasma ratio for MB-102 was 0.590, illustrating minimal distribution of MB-102 into red blood cells. The manufacture of MB-102 under good manufacturing practice yields the designed molecular structure at high purity (>95% wt/wt).

The role of substrate temperature on defects, electronic transitions, and dark current behavior of ZnO films fabricated by spray technique

We have studied structural, electrical, and optical properties of ZnO thin films deposited by a spray technique. The samples were deposited by varying the deposition temperature from 200 °C (S200) up to 500 °C (S500). As the results, using X-ray diffraction and Raman scattering experiments, improvement in crystalline is observed by increasing the deposition temperature as indicated by the intensity enhancement of (002) plane and the E2-high vibration mode. From I–V curves, the photosensitivity of the films also increases up to 37 times (S500) with increasing the temperature. We reveal that strong UV absorption in S500 plays a significant role in the enhancement of sensitivity. On the other hand, the low dark current in S300 is due to the high density of oxygen vacancies, leading to higher mid-gap transitions, green emission, and Schottky barrier height. In the same time, the narrowing effect of the band gap from 3.28 to 3.20 eV is observed with the decrease of the temperature, which is related to the defect states from oxygen vacancies. Our study is essential to design and massively fabricate ZnO-based optoelectronic devices using a simple technique.

Nano Biomedical Potential of Biopolymer Chitosan-Capped Silver Nanoparticles with Special Reference to Antibacterial, Antibiofilm, Anticoagulant and Wound Dressing Material

Silver nanoparticles have been widely used to treat bacterial infections on wounds. Chitosan is a natural polymer having good biocompatibility and biodegradability. Chitosan have antibacterial effects and are largely used in healthcare practices to cure wounds. In this scenario, an attempt was made to biologically synthesize AgNPs using the chitosan extracted from shrimp shell waste. The synthesized Ch-AgNPs exhibited strong UV absorption spectra at 404 nm. XRD spectrum confirmed the presence of nanocrystals with an average crystallite size of 26 nm. HR-TEM images have shown spherical shaped particles with the size ranging between 10 and 50 nm. Ch-AgNPs exhibited antibacterial activity in a dose-dependent manner and greater activity was observed against P. aeruginosa. The zone of inhibition against P. aeruginosa was 10, 15 and 20 mm at 25, 50 and 100 µg mL−1, respectively. The zone of inhibition against MRSA was 8, 15 and 18 mm at 25, 50 and 100 µg mL−1 respectively. Ch-AgNPs effectively inhibited the biofilm of MRSA and P. aeruginosa at 100 µg mL−1. In addition, Ch-AgNPs coated band-aid cloth showed greater antibacterial activity compared to uncoated band-aid cloth. Furthermore, Ch-AgNPs exhibited anticoagulant activity by inhibiting the coagulation of human blood for 24 h.

9,10‐Dithio/oxo‐Anthracene as a Novel Photosensitizer for Photoinitiator Systems in Photoresists

AbstractFive novel 9,10‐dithio/oxo‐anthracenes (ANs) are synthesized, which can be used as efficient photosensitizers for a biimidazole (BCIM) photoinitiator system in dry film photoresists. The potential of ANs as photosensitizer for BCIM is investigated in detail through fluorescence spectra, ESR, and real‐time FT‐IR. The resulting ANs possess strong absorption in the near UV–vis range from 350 to 450 nm with high molar extinction coefficients. The thiol ether and phenyl groups can make UV–vis absorption to be enhanced and red‐shifted significantly. Upon irradiation with 365 or 450 nm of light, BCIM can be photosensitized by ANs and can initiate photopolymerization of acrylate monomer (HDDA) efficiently. The dry film photoresist containing AN@BCIM photoinitiator system can form fine micro‐patterns with high resolution through 405 nm laser direct‐writing photolithography.

Bromide counterion as a spectroscopic sensor at the interface of cetyltrimethylammonium micelles.

The strong UV absorption of the bromide in aqueous solution undergoes a remarkable red shift of more than 10 nm induced by the addition of the salts that constitute a saline buffer. The maximum absorption wavelength of the bromide is displaced from approximately 194 nm in ultrapure water to wavelengths above 200 nm, depending on the composition of the solution. The bromide spectrum as counterion of the cetyltrimethylammonium in the surfactant CTAB also shows sensitivity to the aggregation behavior of the tensioactive, being able to detect intermolecular interactions even at concentrations lower than the critical micelle concentration. And, when the micelles are assembled, the bromide absorption detects the interfacial rearrangements caused by the incorporation of ions. To know more about those interfacial features, the pyrene molecular probe was used, taking advantage of the extensive knowledge of its spectroscopy. Pyrene verifies the existence of changes in the interfacial organization which confirm that the sensitivity of the bromide spectrum is based on the ability of the ion to detect its microenvironment, and therefore reaffirms that its absorption spectrum can be used as a local sensor. The present work encourages the use of bromide as a sensor ion in the UV region between 190 and 210 nm, which would avoid the introduction of external molecular probes that could disturb the system.

Effect of Noble Metals on Luminescence and Single-Molecule Magnet Behavior in the Cyanido-Bridged Ln-Ag and Ln-Au (Ln = Dy, Yb, Er) Complexes.

Self-assembly of lanthanide(III) complexes of 2,2':6',2″-terpyridine (terpy) with dicyanidoargentate(I) and dicyanidoaurate(I) anions in water results in the formation of six isostructural dinuclear systems [LnIII(terpy)(H2O)(NO3)2][MI(CN)2] (LnIII/MI = Dy/Ag, 1; Dy/Au, 2; Yb/Ag, 3; Yb/Au, 4; Er/Ag, 5; Er/Au, 6). They form three-dimensional supramolecular networks based on dinuclear molecules linked by hydrogen bonds, π-π interactions, and argentophilic (Ag···Ag) or aurophilic (Au···Au) interactions. All of the assemblies show complex solid-state strong UV and weak vis-NIR absorption due to overlapping contributions from 2,2':6',2″-terpyridine, dicyanidoargentate(I), dicyanidoaurate(I), and lanthanide(III) ions. Moreover, they exhibit excitation-wavelength-dependent multicolor photoluminescence ranging from bright white to blue via yellow, green, and cyan colors due to variable contributions from the dicyanidometalate and ligand. Assemblies 3-6 show NIR emission originating from YbIII and ErIII metal centers. Furthermore, compounds 1-6 and their magnetically diluted samples are magnetic-field-induced single-molecule magnets with energy barriers of up to 35 K. The effect of noble metal substitution on the magnetic properties of particular lanthanide ions is described. The influence on the thermal anisotropic energy barrier, which relates to the strength of the magnetic anisotropy, depends on the type of lanthanide used. The Ag-to-Au substitution enhances the anisotropy of the prolate YbIII ion and decreases it for the oblate DyIII ion. It also modifies the strength of dipolar interactions affecting the slow magnetic relaxation processes.

Fabriction of ZnO Nanorods with Strong UV Absorption and Different Hydrophobicity on Foamed Nickel under Different Hydrothermal Conditions.

ZnO nanorods have been grown on the surface of foamed nickel by a two-step method. Firstly, a layer of ZnO seed is sputtered on the surface of the foamed nickel by magnetron sputtering, and then the hydrothermal method is used to grow ZnO nanorods at different conditions (solution concentration, reaction time and reaction temperature). The results show that the morphology of ZnO nanorods is closely related to the solution concentration, reaction time, and reaction temperature. The energy band structure formed by the foamed nickel and ZnO seed layers and the growth mechanism of ZnO nanorods are discussed. The samples are characterized by Energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and Raman spectroscopy. The absorption characteristics of samples to light are characterized by ultraviolet-to-visible (UV–VIS) absorption. The hydrophilicity of the samples is characterized by the static contact angle. By analyzing the performance characteristics of the samples at different conditions, we finally obtained the optimal growth parameters. At the optimal parameters, the morphology of the grown nanorods is regular, the ultraviolet band has strong absorption, and the surface of the samples forms a superhydrophobic surface.

Synthesis of chloromethyl benzimidazole grafted polybenzimidazole with enhanced UV absorption and its effect as a stabilizer on the ultraviolet‐aging behaviors of poly(vinyl chloride) films

ABSTRACTPoly(vinyl chloride) (PVC) is particularly susceptible to UV damage, and its durability can be reduced substantially when it is exposed to outdoor environments. In this study, high‐molecular‐weight polybenzimidazole (PBI) was synthesized and then grafted with 2‐chloromethyl benzimidazole. The polybenzimidazole grafted with 2‐chloromethyl benzimidazole (PBI‐g‐CMBeIm) could absorb over 99% of UV light in the region 220–420 nm. Then, PVC–PBI‐g‐CMBeIm blend films were prepared by a solution‐casting method, and the effects of the PBI‐g‐CMBeIm content and UV‐irradiation time on the properties of these films were investigated. The results show that the benzimidazole moieties incorporated into the macromolecular chain of PBI provided additional conjugation units, and this allowed the films to have a stronger UV absorption and broader λ range. The yield strength of the PVC–PBI‐g‐CMBeIm blend films irradiated for 1000 h ranged from 16.5 to 27.7 MPa; this increased 3.2–14.4 MPa compared with that of the pure PVC. The strength retention rate of the pure PVC was 28.8%, whereas that of the PVC–PBI‐g‐CMBeIm blend films was in the range 34.1–55.2%. The addition of PBI‐g‐CMBeIm also effectively increased the thermal degradation temperature of the blend films and slowed down their thermal degradation rate. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47626.

Black ceramic coatings on Ti alloy with enhanced high absorptivity and high emissivity by plasma electrolytic oxidation

AbstractA black ceramic coating with high absorptivity and emissivity was successfully prepared on TA7 (Ti‐5Al‐2.5Sn) in a hybrid electrolyte solution by plasma electrolytic oxidation for improving the imaging precision of optical system. The influence of electrolyte components and technical parameters on the composition, structure, and optical properties was investigated. The results show the coatings with typically porous structure are mainly composed of O, P, Si, Ti, V, Fe, and Ni. The corresponding amorhous oxide in the outer layer endows the coating with strong absorption in the visible light and infrared areas, and the crystallized TiO2 indwelling the inner layer contributes to the strong UV absorption property. In addition, the micropores of the coatings have different size ranges corresponding to the wavelengths, facilitating the increase of absorptivity and emissivity in some degree. The absorptivity and emissivity can be adjusted by electrolyte components and technical parameters. The coating presents the best absorptivity of 0.962 and emissivity of 0.950 in the electrolyte solution of 3 g/L NH4VO3, 5 g/L FeSO4, and 5 g/L C4H6O4Ni under 400 V for 10 minutes.