Ultraviolet Irradiation Conditions Research Articles

Accuracy of EVC Method for the PiN Diode Pattern on SiC Epi-Wafer

In the previous report, we proposed the EVC (Expansion-Visualization-Contraction) method (Fig. 1) that effectively screens for malignant BPDs (basal plane dislocations) in the epi layer and near substrate interface, which expand to SSFs (Shockley-type stacking faults), leading to forward voltage degradation. The method intentionally utilizes the REDG (recombination enhanced dislocation glide) mechanism by UV (ultraviolet) irradiation in wafer sorting to replace the so-called burn-in (accelerated current stress) process, which is time-consuming during mass production. In this report, to verify the effectiveness of this method, we compared the SSFs expanded by forward biasing the PiN diode (Fig.3) on a wafer with the SSFs expanded by UV irradiating at the same PiN diode area where the metal electrode was removed by etching. The accuracy of the EVC method requires that SSFs expanded by forward biasing should be detected in the same positions as those of SSFs expanded by UV irradiation. Not all BPDs expand at the same time, but the number of expanded SSFs increases over time under constant forward current conditions. In this experiment, the current density was 400 A/cm2 for 8 minutes, and the excessive UV irradiation conditions was 143 W/cm2 for 20 minutes to avoid missing. Missing means the inability to check the SSFs expanded by forward biasing against the SSFs expanded by UV irradiation (Fig.2). For each diode electrode window, the presence or absence of SSFs were determined, and as shown in Table 2, 2 out of 49 window areas were missing, with the EVC method accuracy rate of 96 %.

Development of a standard evaluation method for microbial UV sensitivity using light-emitting diodes

Ultraviolet (UV) light is an effective disinfection method. In particular, UV light-emitting diodes (UV-LEDs) are expected to have many applications as light sources owing to their compact form factor and wide range of choices of wavelengths. However, the UV sensitivity of microorganisms for each UV wavelength has not been evaluated comprehensively because standard experimental conditions based on LED characteristics have not been established. Therefore, it is necessary to establish a standard evaluation method based on LED characteristics. Here, we developed a new UV-LED device based on strictly controlled irradiation conditions using LEDs for each wavelength (250–365 nm), checked the validity of the device characteristics and evaluated the UV sensitivity of Escherichia coli using this new evaluation method. For this new device, we considered accurate irradiance, accurate spectra, irradiance uniformity, accurate dose, beam angle, surrounding material reflections, and sample condition. From our results, the following UV irradiation conditions were established as standard: 1 mW/cm2 irradiance, bacterial solution with absorbance value of A600 = 0.5 diluted 10 times solution, solution volume of 1 mL, working distance (WD) of 100 mm. In order to compare the effects of irradiation under uniform conditions on inactivation of microorganisms, we assessed inactivation effect of E. coli by LED irradiation at each wavelength using the U280 LED as a standard wavelength. The inactivation effect for U280 LED irradiation was −0.95 ± 0.21 log at a dose of 4 mJ/cm2. Under this condition of dose, our results showed a high wavelength dependence of the inactivation effect at each UV wavelength peaking at 267 nm. Our study showed that this irradiation system was validated for the standard UV irradiation system and could be contributed to the establishment of food and water hygiene control methods and the development of equipment for the prevention of infectious diseases.

Integrated Physiologic and Proteomic Analyses Reveal the Molecular Mechanism of Navicula sp. in Response to Ultraviolet Irradiation Stress.

With the continuous development of space station construction, space ecosystem research has attracted increasing attention. However, the complicated responses of different candidate plants and algae to radiation stress remain unclear. The present study, using integrated physiologic and proteomic analyses, was carried out to reveal the molecular mechanism of Navicula sp. in response to ultraviolet (UV) irradiation stress. Under 12~24 h of high-dose UV irradiation conditions, the contents of chlorophyll and soluble proteins in Navicula sp. cells were significantly higher than those in the control and 4~8 h of low-dose UV irradiation groups. The activity of catalase (CAT) increased with the extension of irradiation time, and the activity of superoxide dismutase (SOD) decreased first and then increased. Furthermore, differential volcano plot analysis of the proteomic data of Navicula sp. samples found only one protein with a significant difference. Differential protein GO analysis unveiled that UV irradiation can activate the antioxidant system of Navicula sp. and further impact photosynthesis by affecting the photoreaction and chlorophyll synthesis of Navicula sp. The most significant differences in KEGG pathway analysis were also associated with photosynthesis. The above results indicate that Navicula sp. has good UV radiation resistance ability by regulating its photosynthetic pigment content, photosynthetic activity, and antioxidant system, making it a potential candidate for the future development of space ecosystems.

Time-Resolved Structural Analysis of Fast-Photoresponsive Surfactant Micelles by Stroboscopic Small-Angle Neutron Scattering.

Photoresponsive materials are garnering attention because of their applications toward building a sustainable society. A recently developed fast-photoresponsive amphiphilic lophine dimer (3TEG-LPD) responds rapidly to light, making it a promising candidate for drug-delivery systems. In this study, the mechanism of structural changes induced by ultraviolet (UV) irradiation in 3TEG-LPD micelles in an aqueous solution was investigated via an in situ time-resolved small-angle neutron scattering (SANS) technique. Since subsecond resolution was necessary to observe the structural changes in the 3TEG-LPD micelles, stroboscopic SANS analysis was employed to obtain scattering profiles with a time width of 0.5 s. The structural parameters were quantitatively determined by performing a model-fitting analysis of the SANS results. The stroboscopic SANS results showed that upon UV irradiation, the axial ratio and pseudo-aggregation number of the 3TEG-LPD micelles increased by 1.8 and 1.6 times, respectively, whereas the number of water molecules per surfactant molecule decreased. This finding suggested that the change in the shape of the micelles from spherical to ellipsoidal shape was accompanied by dehydration. Under the present UV irradiation conditions, this structural change of the micelle occurred rapidly during the first 30 s after the start of UV irradiation. Each structural parameter recovered exponentially and reversibly during the recovery process after the cessation of UV irradiation. The changes in these parameters were analyzed in terms of kinetics by comparing them with the changes in the molecular structure. We found that the change of the micelles proceeds approximately twice as fast as the association of the molecule. Furthermore, from the perspective of the critical packing parameter consideration, the SANS analysis revealed that the UV-induced changes in 3TEG-LPD micelles are dominated by the enthalpy contribution. This finding is expected to be useful for developing new materials for various applications.

Degradation of polycyclic aromatic hydrocarbons (PAHs) in smoked sausages by ultraviolet irradiation.

Ultraviolet (UV) irradiation has been widely employed to disinfect food, however, the efficacy of UV irradiation in degrading polycyclic aromatic hydrocarbons (PAHs) in smoked sausages has not been explored. In this article, the UV degradation ability of PAHs in smoked sausages was investigated with different UV irradiation conditions, including different irradiation powers, durations and wavelengths. The effects of UV radiation on the quality of sausages were also evaluated, and potential degradation mechanisms were elucidated. The results showed that the irradiation duration was the primary determinant of PAHs degradation, achieving 84.4% and 84.2% degradation rates at 16 W and 32 W power for 30 min, respectively. Among the three UV wavelengths assessed, 254 nm demonstrated a significantly higher degradation rate for benzo[a]pyrene (BaP), PAH4 and PAHs compared to 365 nm and 310 nm. To further explore the degradation mechanism, UV irradiation was combined with water, 0.1 mol/L hydrogen peroxide (H2 O2 ) and 0.1 mol/L ascorbic acid (vitamin C) coatings. The 0.1 mol/L H2 O2 coating exhibited the most pronounced degradation effect, suggesting that the highly reactive oxygen hydroxyl radicals (·OH) generated by UV irradiation played a critical role in initiating redox reactions. This systematic investigation paves the way for developing novel strategies to eliminate PAHs or other organic contaminants from smoked sausages. © 2023 Society of Chemical Industry.

Effective removal of hexavalent chromium from aqueous system by biochar-supported titanium dioxide (TiO

Environmental context Photocatalytic TiO2 materials are good prospects in water quality treatment due to their stable chemical properties and limited secondary pollution. TiO2 photocatalytic material prepared with biochar as a carrier can greatly improve the photocatalytic efficiency of CrVI, and the removal rate of CrVI can reach 84.4%. This study shows that biochar-supported TiO2 photocatalytic composites are feasible for the green and efficient removal of CrVI from an aqueous phase. Rationale TiO2 has great application prospects in the treatment of chromium-containing wastewater due to its photochemical stability and low toxicity. Loading TiO2 on solid adsorption materials can improve the photocatalytic efficiency and solve the problem of difficult separation and recovery of TiO2. Methodology In this study, biochar-supported TiO2 (BC-TiO2) and acid-washed biochar-supported TiO2 (HBC-TiO2) were prepared by a sol–gel method using biochar (BC) and acid-washed biochar (HBC) as adsorption carriers. The effects of various experimental parameters such as ultraviolet irradiation conditions, catalyst dose and pH on the removal efficiency of CrVI by BC, HBC, BC-TiO2 and HBC-TiO2 were investigated. The structure and morphology of the four materials were characterised. Results The results indicated that under the optimal reaction conditions (pH = 6, dosage of biochar materials/photocatalytic composites = 5 g/6 g), the removal percentage of CrVI changed as BC-TiO2 (Light) (84.43%) > HBC-TiO2 (Light) (80.19%) > BC-TiO2 (Dark) (57.9%) > HBC-TiO2 (Dark) (52.94%) > HBC (30.06%) > BC (14.66%). Loading TiO2 on biochar materials improved the specific surface area and increased the reaction sites when compared with BC and HBC. Discussion This study shows that BC-TiO2 is more suitable to remove CrVI from an aqueous system because of its high removal efficiency. The enrichment of CrVI on the biochars and the close contact between the biochar and TiO2 through the Ti–O–C dense heterojunction promote the interfacial transfer of CrVI, which is the key to the removal of CrVI. This study has great significance for the treatment of chromium-containing wastewater by photocatalytic composites.

Aging of poly (lactic acid)/poly (butylene adipate-co-terephthalate) blends under different conditions: Environmental concerns on biodegradable plastic

Biodegradable plastics (BPs) have been used to replace conventional plastics owing to their environmental harmless and ease of degradation. However, the aging processes of BPs in different environments remain unclear. In this study, we used poly (lactic acid)/poly (butylene adipate-co-terephthalate) (PLA/PBAT) films as model BPs and investigated the 30-d aging behavior of PLA/PBAT films under four conditions (i.e., air without ultraviolet (UV) irradiation, water without UV irradiation, air with UV irradiation, and water with UV irradiation). Our results showed that the aging of PLA/PBAT films was insignificant in all groups except the water with UV irradiation group. In the physical characterization, the PLA/PBAT films exhibited layered structures in water with UV irradiation condition, and the submicron- and nano-sized particles adhered to the bigger-sized fragments. In the chemical characterization, the carbonyl index (CI) of PLA/PBAT films in water with UV irradiation condition decreased from 3.84 to 1.36, and the oxygen-to-carbon (O/C) ratio reached a maximum of 1.78 at 20 d and declined to 0.49 at 30 d, indicating that the oxygen-containing functional groups underwent bond breaking and showed a rapid aging process. This is mainly attributed to the combined effect of hydrolysis and photolysis increases the contact area of PLA/PBAT films and accelerates the aging process. Furthermore, based on two-dimensional correlation spectroscopy (2D-COS) analysis, we suggest that free radicals generated in water with UV irradiation conditions also accelerate the aging process of PLA/PBAT films. This study explored the aging processes of PLA/PBAT films under different conditions, which could aid in clarifying the environmental behavior and provide further information to assess the potential risks of BPs.

Electro-optical characteristics of polymer-dispersed liquid crystal containing copper (II) phthalocyanine as a function of UV irradiation time

We describe a method of dispersing copper (II) phthalocyanine that can expand the application range of polymer-dispersed liquid crystals (PDLCs) among smart-window technologies. Property changes were monitored during the polymerization-induced phase separation method as the ultraviolet (UV) irradiation time was increased from 70 to 175 s. With increasing UV irradiation time, the number of droplets in the polymer matrix within the PDLC increased, while the droplet size decreased, as observed by polarized optical and low vacuum-scanning electron microscopies. Voltage–transmittance and response time were measured to observe the effects on electro-optical properties; the threshold and saturation voltages increased with increasing UV-irradiation time. The falling time of the response decreased with increasing irradiation time; a fast switching time of < 20 ms was observed in all cases. This study provides the performance of the produced PDLC varies according to the UV irradiation time, and conditions and processes necessary for producing blue PDLC are presented.

Nanoarchitectonics of (110) directed polyethylene glycol stabilized cerium nanoparticles for UV filtering applications

The use of zinc oxide (ZnO) and titanium oxide (TiO2) nanoparticles in ultraviolet (UV) filters can cause serious health issues due to their genotoxicity and cytotoxicity effect. Recent research on cerium oxide (CeO2) nanoparticles has demonstrated their biocompatible nature, excellent antioxidant and ultraviolet–visible (UV–Vis) absorption properties. CeO2-based nanocomposite materials or nano-architectures can offer uniform absorptive properties, therapeutic skin effect and easy skin application. In this study, cerium oxide-polyethylene glycol (CeO2-PEG) nano-architecture was prepared by hydrothermal processing with the aim to improve stability, antioxidant properties, and enhance UV absorption for UV filtering applications. The morphology study of the developed nanocomposite revealed the formation of polymer bands with well-dispersed CeO2 nanoparticles. The nanocomposite structure has exhibited excellent UV absorption in the UV range 200–400 nm due to decrease in optical band gap in comparison to the naked CeO2 NPs. The evaluation of the photocatalytic activity (PCA) of the nanocomposite structure against P25 photocatalyst and ZnO nanoparticles showed no dye (crystal violet) degradation on UV irradiation. Hence, PCA assay verified the absence of ROS generation and increased stability of the nanostructure under UV irradiation. The investigation of antioxidant properties of the Ce-PEG nanocomposite by a dichlorofluorescein (DCF)-based assay revealed sufficient intracellular ROS scavenging in comparison to N-acetylcysteine (NAC) and H2O2 only assays. In vitro toxicity evaluation of Ce-PEG nanocomposite towards non-malignant human keratinocyte cell line (HaCaT) revealed a non-significant cell mortality ~ 10% of control at a dosage of 50 mg L−1. The nanocomposite structure also exhibited excellent UV protection for HaCaT cells under UV irradiation conditions compared to P25. Our findings suggest that the developed nanocomposite combined the antioxidant and UV absorption properties of CeO2 and skin emollient role of (PEG), and hence offered a novel biocompatible and multifunctional structure for sunscreens and therapeutic skin product.Graphical abstract

Nano-MIL-88A(Fe) Enabled Clear Cellulose Films with Excellent UV-Shielding Performance and Robust Environment Resistance

While tremendous efforts have been dedicated to developing cellulose-based ultraviolet (UV)-blocking films, challenges still remain in simultaneously achieving high transparency, low haze and excellent UV shielding properties via simple and green strategy. Here, we present a facile and eco-friendly route to fabricate flexible, biodegradable and clear UV-shielding nano-MIL-88A(Fe)@carboxymethylated cellulose films (M(Fe)CCFs) via in situ synthesis of nano-MIL-88A(Fe) in carboxymethylated cellulose hydrogel followed by natural drying. The carboxymethylated cellulose film has high transmittance (93.2%) and low haze (1.8%). The introduction of nano-MIL-88A(Fe) endowed M(Fe)CCFs superior UV-shielding ability, while retaining high transmittance (81.5–85.3%) and low haze (2.5–4.9%). Moreover, M(Fe)CCFs showed stable UV blocking performance under UV irradiation, high temperature, acidic or alkaline conditions. Quite encouragingly, the UV-shielding ability of M(Fe)CCFs did not deteriorate, even after 30 days of immersion in aqueous solution, providing films with a long-term use capacity. Thus, M(Fe)CCFs show high potential in the UV protection field. Overall, these UV-blocking films with outstanding performances are a promising candidate to replace conventional film materials made from synthetic polymers in fields such as packaging and flexible electronics.

Aqueous-phase Oxidation of Dissolved Organic Matter (DOM) from Extracts of Ambient Aerosols

Recently, a large number of laboratory studies have focused on the aqueous-phase photochemistry of single organic compound in atmospheric condensed phases, yet few studies have been conducted on the aqueous-phase photochemical oxidation of real-world complex dissolved organic matter (DOM). Therefore, in this work, we report experimental results for the photochemical oxidation of DOM extracts from ambient fine aerosol samples upon direct photolysis or against OH oxidation, under both simulated sunlight and ultraviolet irradiation conditions. The products at different stages of photolysis were analyzed via UV-vis and spectroscopy and soot-particle aerosol mass spectrometry (SP-AMS) to investigate their optical and chemical characteristics. The results demonstrate the effective degradation of DOM under UV irradiation, and the f44 values of the corresponding products aremuch lower than under sunlight irradiation. A variety of carboxylic acids were generated during liquid-phase photolysis, and oxalic acid was found to be the most abundant. The light absorbance and concentration of HULIS did not change significantly under sunlight illumination; however, under UV and UV+·OH conditions, the concentration of HULIS increased continuously with reaction time. The HULIS concentration at 23 h was approximately four times the initial value, indicating the formation of brown carbon species with carboxyl, hydroxyl, and aromatic and other functional groups. Our results show that the increase in light absorptivity and formation rate of brown carbon from DOM are limited when aqueous-phase oxidation occurs under sunlight illumination. In comparison, DOM can constantly decompose into HULIS or small molecules under ultraviolet light illumination, and the light absorptivity of the remaining organic matter may be relatively high, resulting in final products with a high unit mass absorption efficiency (MAE). We have investigated the aqueous-phase oxidation of actual filter extracts for the first time, and our results provide valuable insights to the formation of air pollution complexes.

Natural lignocellulosic nanofibril film with excellent ultraviolet blocking performance and robust environment resistance

Due to the current state of ozone layer depletion and potential risk of skin cancer, researches on sustainable cellulose-based films with ultraviolet (UV) blocking capabilities has attracted widespread attention. However, pure cellulose-based film required UV absorbent to be incorporated because of its poor UV blocking ability. In this work, natural lignocellulosic nanofibril (LCNF) film was fabricated by vacuum filtration and pressing process without any complex chemical modification or adding UV absorbers. The residual lignin retained in LCNF was found to act as natural macro-molecular UV absorber. LCNF film with lignin content of 4.89–15.68% exhibited excellent thermal stability, and their UVA and UVB blocking were in the range of 81.4–99.5% and 96.7–100%, respectively. Moreover, LCNF film exhibited stable UV shielding performance under high temperature, UV irradiation, acidic or alkaline conditions, providing LCNF film with a long-term use capacity. Overall, LCNF film is more environmentally friendly and harmless, which shows high potentials in anti-counterfeiting materials, UV protection, and windshields for vehicles.

Molecular globules in the Veil bubble of Orion

Strong winds and ultraviolet (UV) radiation from O-type stars disrupt and ionize their molecular core birthplaces, sweeping up material into parsec-size shells. Owing to dissociation by starlight, the thinnest shells are expected to host low molecular abundances and therefore little star formation. Here, we expand previous maps made with observations using the IRAM 30 m telescope (at 11″ ≃ 4500 AU resolution) and present square-degree12CO and13CO (J= 2–1) maps of the wind-driven “Veil bubble” that surrounds the Trapezium cluster and its natal Orion molecular core (OMC). Although widespread and extended CO emission is largely absent from the Veil, we show that several CO “globules” exist that are blueshifted in velocity with respect to OMC and are embedded in the [C II] 158μm-bright shell that confines the bubble. This includes the first detection of quiescent CO at negative local standard of rest velocities in Orion. Given the harsh UV irradiation conditions in this translucent material, the detection of CO globules is surprising. These globules are small (Rg= 7100 AU), not massive (Mg= 0.3M⊙), and are moderately dense:nH= 4 × 104cm−3(median values). They are confined by the external pressure of the shell,Pext∕k≳ 107cm−3K, and are likely magnetically supported. They are either transient objects formed by instabilities or have detached from pre-existing molecular structures, sculpted by the passing shock associated with the expanding shell and by UV radiation from the Trapezium. Some represent the first stages in the formation of small pillars, others of isolated small globules. Although their masses (Mg&lt;MJeans) do not suggest they will form stars, one globule matches the position of a known young stellar object. The lack of extended CO in the “Veil shell” demonstrates that feedback from massive stars expels, agitates, and reprocesses most of the disrupted molecular cloud gas, thereby limiting the star-formation rate in the region. The presence of molecular globules is a result of this feedback.

Free‐radical‐mediated copper‐catalyzed triazole formation under UV‐irradiation

Methoxy‐polyethylene glycol (MPEG)‐doped Cu (I)‐polyaniline acts as an efficient catalyst for the 1,2,3‐triazole formation reaction. The catalyst shows excellent performance when the reaction was carried out under ultraviolet irradiation conditions due to the photo‐induced free‐radical formation from the MPEG. A detailed mechanistic discussion on the free‐radical generation, free‐radical‐mediated hydrogen abstraction and triazole formation has been outlined in this manuscript. The catalyst system is equally active for one‐pot multi‐component strategies for the title reaction.

Enhanced UV Flexible Photodetectors and Photocatalysts Based on TiO2 Nanoplatforms

In this study, titanium dioxide (TiO2) nanostructured films were synthesized under microwave irradiation through low temperature synthesis (80 °C) and integrated in ultraviolet (UV) photodetectors and as photocatalysts. Bacterial nanocellulose (BNC), tracing paper, and polyester film were tested as substrates, since they are inexpensive, flexible, recyclable, lightweight, and when associated to low temperature synthesis and absence of a seed layer, they become suitable for several low-cost applications. The nanostructured TiO2 films and substrates were structurally characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, X-ray diffraction, and Raman spectroscopy. The optical properties of all materials were investigated. The TiO2 nanostructured films were implemented as a photoactive layer of UV photodetectors and demonstrated significant increase of conductance upon exposed to UV irradiation. The photodetection behaviour of each material was investigated by in-situ Kelvin probe force microscopy experiments, in which the contact potential difference varied under dark or UV irradiation conditions, demonstrating higher shift for the BNC-based UV photodetector. Photocatalytic activity of the films was assessed from rhodamine B degradation under solar radiation, and BNC based devices revealed to be the best photocatalyst. The structural characteristics of the TiO2 films and substrates were correlated to the differences in the UV photodetection and photocatalytic performances.

Effects of TiO2 nanoparticles on the photodegradation of poly(lactic acid)

ABSTRACTPhotodegradable poly(lactic acid) (PLA)/titanium dioxide (TiO2) nanocomposites could be utilized as an eco‐friendly material. The photocatalytic degradation was investigated under accelerating artificial ultraviolet irradiation conditions for the period up to 100 days according to GB/T16422.3/ISO 4892.4. The change of surface color, gloss loss, morphology, weight loss, intrinsic viscosity, chemical structure, mechanical properties at different irradiation times were verified via solid reflection spectrophotometer, scanning electron microscopy, Ubbelohde viscometer, Fourier transform infrared spectrometer, and tensile test. The structural change accompanied by the degradation of the irradiated samples clearly showed that the photodegradation of PLA/TiO2 nanocomposites process was via a bulk erosion mechanism. The photodegradability of PLA/TiO2 samples was higher than that of pure PLA and benefitted a lot from a good dispersion of TiO2 nanoparticles. The present study suggests that the photodegradation of PLA could be controlled by loading dispersed g‐TiO2 nanoparticles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46509.

Three-Dimensionally Conformal Porous Microstructured Fabrics via Breath Figures: A Nature-Inspired Approach for Novel Surface Modification of Textiles

Breath figures (BFs) are a kind of water droplet arrays that can be formed by condensing aqueous vapor onto a cold surface, such as dewy phenomenon on a spider web. This study developed a BF-inspired approach for direct introduction of desired materials onto the textile surfaces with three-dimensionally conformal porous microstructures by the evaporation of solution-coated fabric under high humidity environment, which brings a brand-new kind of modified textiles, three-dimensionally conformal porous microstructured fabrics (CPMFs). Such kind of CPMFs can possess customized multifunctional properties of introduced materials, and meanwhile maintain the inherent properties and unique texture features of fabrics. This nature-inspired BF approach is robust and versatile for customized preparation of CPMFs based on different fabrics with different common polymers. Moreover, it is also feasible for one-step functionalization of CPMFs by the incorporation of nanoparticles (such as titanium dioxide nanoparticles, TiO2 NPs) into the porous microstructures during the BF process. Comparing to the sample modified without porous microstructures, the resultant TiO2 NPs-incorporated CPMFs show an obviously enhanced performance on photocatalytic degradation of pollutants under the same ultraviolet irradiation conditions.

Biomimetic Bone-Like Apatite Coating on Anodised Titanium in Simulated Body Fluid under UV Irradiation

Low temperature deposition techniques of bioceramics coatings are now being researched and developed to avoid deficiencies inherent in high temperature techniques. Biomimetic coatings is a solution-based method conducted at ambient temperature to deposit bioactive coatings on the surface. The current study aims to investigate the effect of ultraviolet (UV) irradiation on the coating of bone-like apatite on the anodised surface. High purity titanium foils were anodised with an applied voltage of 350 V, current density of 70 mA.cm-2 in mixture of 0.04 M β-glycerophosphate disodium salt pentahydrate (β-GP) and 0.4 M calcium acetate (CA) for 10 min. After anodic oxidation, UV light treatment was conducted in pH-adjusted distilled water for 12 hours with ultraviolet light A (UVA) irradiation. Subsequently, the UV-treated anodised titanium foils were soaked in SBF for 7 days with/without UVA irradiation. After SBF immersion for 7 days, anodised titanium with combination of UV light treatment and UV irradiation during in vitro testing was fully covered by highly crystalline bone-like apatite at maximal thickness of 2.8 μm. This occurred mainly due to the formation of large amounts of Ti-OH groups which act as nucleation sites for bone-like apatite. This study also revealed that UV irradiation during in vitro testing is superior in promoting growth of bone-like apatite compared to UV light treatment. The suggested mechanism for bone-like apatite formation on anodised titanium under different UV irradiation conditions is illustrated in this article. The findings of this study indicated that biomimetic bone-like apatite coating with assistance of UV irradiation is an effective method in accelerating the formation of bone-like apatite.

Durably superhydrophobic textile based on fly ash coating for oil/water separation and selective oil removal from water

Fly ash as an industrial solid waste can pose great risks to the environment. In the present study, superhydrophobic cotton textile for oil/water separation was developed based on the formation of fly ash coating and subsequent hydrophobization. The hierarchical fly ash coating immobilized exhibited superhydrophobicity with a water contact angle of 152°. The as-prepared textile can effectively separate a series of oil/water mixtures with high separation efficiency up to 97.3%. Furthermore, the obtained textile can be used under acidic, alkaline, salty, and ultraviolet irradiation conditions. After sixteen cycles of oil/water separation, the textiles still maintained stable superhydrophobicity and high separation efficiency. Owning to good environmental friendliness, low cost, high separation efficiency, and excellent durability and recyclability, the as-prepared textile may be a promising candidate for the separation of oil/water mixtures.

Hybrid UV Active Pixel Sensor Implemented Using GaN MSM UV Sensor and Si-Based Circuit

A hybrid active pixel sensor (APS) was implemented for ultraviolet (UV) imagers by combining a metal–semiconductor–metal (MSM)-type GaN UV sensor and a standard Si CMOS APS controller. The photodetector region of the APS circuit was replaced by a GaN MSM UV sensor, and it was connected together on the printed circuit board with standard Si CMOS APS circuit chip. The dark and photoresponsive current densities of the fabricated MSM UV sensor were $2.5 \times 10^{\mathrm {\mathbf {-6}}}$ and $1.6 \times 10^{\mathrm {\mathbf {-3}}}$ A/cm $^{\mathrm {\mathbf {2}}}$ , respectively, at 10 V bias. The fabricated hybrid UV APS has clearly distinguishable ON/OFF operation states under dark and 365-nm UV irradiation conditions. The calculated photoresponsivity of the hybrid-type GaN UV APS was as high as 5.1 V/W.