Optimizing Photoelectrochemical UV Imaging Photodetection: Construction of Anatase/Rutile Heterophase Homojunctions and Oxygen Vacancies Engineering in MOF-Derived TiO2.

Self-powered photoelectrochemical (PEC) ultraviolet photodetectors (UVPDs) are promising for next-generation energy-saving and highly integrated optoelectronic systems. Constructing a heterojunction is an effective strategy to increase the photodetection performance of PEC UVPDs because it can promote the separation and transfer of photogenerated carriers. However, both crystal defects and lattice mismatch lead to deteriorated device performance. Here, we introduce a structural regulation strategy to prepare TiO2 anatase-rutile heterophase homojunctions (A-R HHs) with oxygen vacancies (OVs) photoanodes through an in situ topological transformation of titanium metal-organic framework (Ti-MOF) by pyrolysis treatment. The cooperative interaction between A-R HHs and OVs suppresses carrier recombination and accelerates carrier transport, thereby significantly enhancing the photodetection performance of PEC UVPDs. The obtained device realizes a high on/off ratio of 10,752, a remarkable responsivity of 24.15 mA W-1, an impressive detectivity of 3.28 × 1011 Jones, and excellent cycling stability. More importantly, under 365 nm light illumination, a high-resolution image of "HUST" (the abbreviation of Harbin University of Science and Technology) was obtained perfectly, confirming the excellent optical imaging capability of the device. This research not only presents an advanced methodology for constructing TiO2-based PEC UVPDs, but also provides strategic guidance for enhancing their performance and practical applications.

UV imaging for the rapid at-line content determination of different colourless APIs in their tablets with artificial neural networks.

This paper presents a novel high-resolution and rapid (50 ms) UV imaging system, which was used for at-line, non-destructive API content determination of tablets. For the experiments, amlodipine and valsartan were selected as two colourless APIs with different UV induced fluorescent properties according to the measured solid fluorescent spectra. Images were captured with a LED-based UV illumination (385-395 nm) of tablets containing amlodipine or valsartan and common tableting excipients. Blue or green colour components from the RGB colour space were extracted from the images and used as an input dataset to execute API content prediction with artificial neural networks. The traditional destructive, solution-based transmission UV measurement was applied as reference method. After the optimization of the number of hidden layer neurons it was found that the relative error of the content prediction was 4.41 % and 3.98 % in the case of amlodipine and valsartan containing tablets respectively. The results open the possibility to use the proposed UV imaging-based system as a rapid, in-line tool for 100 % API content screening in order to greatly improve pharmaceutical quality control and process understanding.

UV-VIS imaging-based investigation of API concentration fluctuation caused by the sticking behaviour of pharmaceutical powder blends.

Surface powder sticking in pharmaceutical mixing vessels poses a risk to the uniformity and quality of drug formulations. This study explores methods for evaluating the amount of pharmaceutical powder mixtures adhering to the metallic surfaces. Binary powder blends consisting of amlodipine and microcrystalline cellulose (MCC) were used to investigate the effect of the mixing order on the adherence to the vessel wall. Elevated API concentrations were measured on the wall and within the dislodged material from the surface, regardless of the mixing order of the components. UV imaging was used to determine the particle size and the distribution of the API on the metallic surface. The results were compared to chemical maps obtained by Raman chemical imaging. The combination of UV and VIS imaging enabled the rapid acquisition of chemical maps, covering a substantially large area representative of the analysed sample. UV imaging was also applied in tablet inspection to detect tablets that fail to meet the content uniformity criteria. The results present powder adherence as a possible source of poor content uniformity, highlighting the need for 100% inspection of pharmaceutical products to ensure product quality and safety.

Design and Development of an Ultraviolet All-Sky Imaging System.

All-sky cameras capture a panoramic view of the full sky from horizon to horizon to generate a wide-angle image of the observable sky. State-of-the-art all-sky imagers are limited to imaging in the visible and infrared spectrum and cannot image in the UV spectrum. This article describes the development of an all-sky imaging system capable of capturing 130° wide-angle sky images from horizon to horizon in the UV-AB spectrum. The design of the UV all-sky imaging system is based on low-cost, accessible, and scalable components to develop multiple images that can be deployed over a wider geographical area. The spectral response of the camera system has been validated in the UV spectrum (280-420 nm) using a monochromatic UV beam with an average power output of 22 nW. UV all-sky imaging systems complement existing infrared and visible all-sky cameras. They have wide applications in astronomy, meteorology, atmospheric science, vulcanology, meteors and auroral monitoring, and the defence sector.

Research progress on the application of spectral imaging technology in pharmaceutical tablet analysis.

Tablet as a traditional dosage form in pharmacy has the advantages of accurate dosage, ideal dissolution and bioavailability, convenient to carry and transport. The most concerned tablet quality attributes include active pharmaceutical ingredient (API) contents and polymorphic forms, components distribution, hardness, density, coating state, dissolution behavior, etc., which greatly affect the bioavailability and consistency of tablet final products. In the pharmaceutical industry, there are usually industry standard methods to analyze the tablet quality attributes. However, these methods are generally time-consuming and laborious, and lack a comprehensive understanding of the properties of tablets, such as spatial information. In recent years, spectral imaging technology makes up for the shortcomings of traditional tablet analysis methods because it provides non-contact and rich information in time and space. As a promising technology to replace the traditional tablet analysis methods, it has attracted more and more attention. The present paper briefly describes a series of spectral imaging techniques and their applications in tablet analysis. Finally, the possible application prospect of this technology and the deficiencies that need to be improved were also prospected.

Real-Time Monitoring of SO2 Emissions Using a UV Camera with Built-in NO2 and Aerosol Corrections.

Nitrogen dioxide (NO2) absorption correction of the sulfur dioxide (SO2) camera was demonstrated for the first time. The key to improving the measurement accuracy is to combine a differential optical absorption spectroscopy (DOAS) instrument with the SO2 camera for the real-time NO2 absorption correction and aerosol scattering correction. This method performs NO2 absorption correction by the correlation between the NO2 column density measurement of the DOAS and the NO2 optical depth of the corresponding channel from the SO2 camera at a narrow wavelength window around 310 and 310 nm. The error of correction method is estimated through comparison with only using the second channel of the traditional SO2 camera to correct for aerosol scattering and it can be reduced by 11.3% after NO2 absorption corrections. We validate the correction method through experiments and demonstrate it to be of greatly improved accuracy. The result shows that the ultraviolet (UV) SO2 camera system with NO2 absorption corrections appears to have great application prospects as a technology for visualized real-time monitoring of SO2 emissions.

Low-Temperature Vapor-Phase Anion-Exchange Strategy for Wide-Bandgap Double-Perovskite Cs2AgBiCl6 Films toward Weak Ultraviolet Light Imaging.

Low-temperature synthesis of high-quality, high-stability, wide-bandgap perovskite films by solution methods is still challenging. Herein, large-scale wide-bandgap Cs2AgBiCl6 (CABC) double perovskite films are synthesized by a vapor-phase anion-exchange strategy. By dedicatedly designing an ultrathin TiO2 modification layer between the substrate and double perovskites, high-quality heterojunctions with matched energy band alignment are formed, contributing to a remarkably enhanced ON/OFF ratio of 2.4 × 104 (86 times) and a responsivity of 16 mA W-1 (12 times). Additionally, the ultraviolet photodetectors (UV PDs) exhibit an excellent UV detection limit of 1.18 µW cm-2 (20 nW), a broad linear dynamic range of 146 dB, and a high specific detectivity of 2.06 × 1011 Jones, as well as long-term stability. Finally, we further demonstrate a weak UV imaging system using CABC UV PDs as imaging sensors. The system is capable of imaging weak UV signals as low as 2.94 µW cm-2 (50 nW). Our results provide a feasible approach for low-temperature fabrication of wide-bandgap perovskite UV PDs and explore the promising application for weak UV detection and imaging.

Methodological Considerations in Development of UV Imaging for Characterization of Intra-Tumoral Injectables Using cAMP as a Model Substance.

A UV imaging release-testing setup comprising an agarose gel as a model for tumorous tissue was developed. The setup was optimized with respect to agarose concentration (0.5% (w/v)), injection procedure, and temperature control. A repeatable injection protocol was established allowing injection into cavities with well-defined geometries. The effective resolution of the SDi2 UV imaging system is 30-80 µm. The linear range of the imaging system is less than that of typical spectrophotometers. Consequently, non-linear cAMP calibration curves were applied for quantification at 280 nm. The degree of deviation from Beer's law was affected by the background absorbance of the gel matrix. MATLAB scripts provided hitherto missing flexibility with respect to definition and utilization of quantification zones, contour lines facilitating visualization, and automated, continuous data analysis. Various release patterns were observed for an aqueous solution and in situ forming Pluronic F127 hydrogel and PLGA implants containing cAMP as a model for STING ligands. The UV imaging and MATLAB data analysis setup constituted a significant technical development in terms of visualizing behavior for injectable formulations intended for intra-tumoral delivery, and, thereby, a step toward establishment of a bio-predictive in vitro release-testing method.

Drug diffusion in biomimetic hydrogels: importance for drug transport and delivery in non-vascular tumor tissue.

Hydrogels of varying complexity are routinely used as scaffolds and 3D structures for in vitro tumor models to increase physiological relevance within pre-clinical cancer research. Relatively simple hydrogels such as agarose are well characterised, meanwhile biomimetic gels containing collagen and fibrin(ogen) have been studied to a much lesser extent. In this study, hydrogels mimicking the biophysical characteristics of liver cancer progression were investigated in terms of their UV-properties and influence on diffusion coefficients of different substances. UV-imaging technology was used to both visualize and quantify the diffusion process in a simple and rapid way. In general, agarose gel diffusion agreed well with predictions using the Stokes-Einstein equation meanwhile the biomimetic gels reduced diffusion coefficients by up to 70%. For doxorubicin, spatio-temporal tissue concentration modelling was used to translate in vitro diffusion to the more clinical context of tumor penetration in a solid liver tumor supplied by arterial blood.

In Situ Fabrication of PdSe2/GaN Schottky Junction for Polarization-Sensitive Ultraviolet Photodetection with High Dichroic Ratio.

Polarization-sensitive ultraviolet (UV) photodetection is of great technological importance for both civilian and military applications. Two-dimensional (2D) group-10 transition-metal dichalcogenides (TMDs), especially palladium diselenide (PdSe2), are promising candidates for polarized photodetection due to their low-symmetric crystal structure. However, the lack of an efficient heterostructure severely restricts their applications in UV-polarized photodetection. Here, we develop a PdSe2/GaN Schottky junction by in situ van der Waals growth for highly polarization-sensitive UV photodetection. Owing to the high-quality junction, the device exhibits an appealing UV detection performance in terms of a large responsivity of 249.9 mA/W, a high specific detectivity, and a fast response speed. More importantly, thanks to the puckered structure of the PdSe2 layer, the device is highly sensitive to polarized UV light with a large dichroic ratio up to 4.5, which is among the highest for 2D TMD material-based UV polarization-sensitive photodetectors. These findings further enable the demonstration of the outstanding polarized UV imaging capability of the Schottky junction, as well as its utility as an optical receiver for secure UV optical communication. Our work offers a strategy to fabricate the PdSe2-based heterostructure for high-performance polarization-sensitive UV photodetection.

Impact of Swelling of Spray Dried Dispersions in Dissolution Media on their Dissolution: An Investigation Based on UV Imaging.

Impact of SDD-dissolution medium interactions on the swelling and dissolution of spray dried dispersions (SDDs) was investigated using UV imaging by monitoring SDD swelling in situ, along with correlating of the swelling with the micro-dissolution and intrinsic dissolution of SDDs. SDDs of ketoconazole or indomethacin with three polymers: polyvinylpyrrolidone (PVP), hydroxypropyl cellulose (HPC), and hydroxypropyl methylcellulose acetate succinate (HPMC-AS) were prepared for the study. Dissolution media employed for assessing swelling and dissolution include water, acetate buffer, phosphate buffer, fasted state simulated intestinal fluid (FaSSIF), and fed state simulated intestinal fluid (FeSSIF), in which influence of polymers and drugs together with the physical-chemical properties of dissolution media (pH, and the presence of sodium taurocholate and lecithin) on SDD swelling and dissolution was evaluated. It appears that hydrophilic and hydrophobic properties of polymers can significantly impact SDD swelling and thus the dissolution. Furthermore, properties of dissolution media such as pH as well as presence of bile salts and lecithin seems to affect SDD swelling and dissolution as well. Throughout the text, thermodynamic swelling of polymers was used to interpret SDD dissolution behavior. Finally, practical implication of polymer swelling on dissolution was discussed.

Interfacial Gradient-Energy-Band-Alignment Modulation via a Vapor-Phase Anion-Exchange Reaction toward Lead-Free Perovskite Photodetectors with Excellent UV Imaging Capability.

Bi-based inorganic perovskites have attracted great attention in optoelectronics, as they feature similar photoelectric properties but have high stability and lead-free merits. Unfortunately, due to the high exciton binding energy and small Bohr radius, their photodetection performance still largely lags behind that of Pb-based counterparts. Herein, using a vapor-phase chloride ion-substitution strategy, Cs3Bi2Br9 photodetectors (PDs) with gradient energy band alignment were delicately modulated, contributing to a high carrier separation/collection efficiency. The optimized Bi-based perovskite ACCT (Al2O3/Cs3Bi2Br9/Cs3Bi2ClxBr9-x/TiO2) PDs exhibit outstanding performance, the ON/OFF ratio and linear dynamic range (LDR) are significantly improved by 20 and 2.6 times, respectively. Significantly, we further demonstrate the high-SNR (signal-to-noise ratio) UV imaging based on the optimized device, which shows 21.887 dB higher than that of the pristine device. Finally, the vapor-phase anion-exchange modified perovskite PDs show long-term stability and high UV resistance. Vapor-phase ion-substitution is a promising approach for the synergistic effect of matched energy band alignment and interface passivation, which can be applied to other perovskite-based optoelectronic devices.

Application of UV dissolution imaging to pharmaceutical systems.

UV-vis spectrometry is widely used in the pharmaceutical sciences for compound quantification, alone or in conjunction with separation techniques, due to most drug entities possessing a chromophore absorbing light in the range 190-800 nm. UV dissolution imaging, the scope of this review, generates spatially and temporally resolved absorbance maps by exploiting the UV absorbance of the analyte. This review aims to give an introduction to UV dissolution imaging and its use in the determination of intrinsic dissolution rates and drug release from whole dosage forms. Applications of UV imaging to non-oral formulations have started to emerge and are reviewed together with the possibility of utilizing UV imaging for physical chemical characterisation of drug substances. The benefits of imaging drug diffusion and transport processes are also discussed.

Strong Polarized Photoluminescence CsPbBr3 Nanowire Composite Films for UV Spectral Conversion Polarization Photodetector Enhancement.

In this work, we proposed a fluorescence conversion layer with polarization characteristics to enhance UV polarization detection for the first time. To achieve this goal, the colloidal lead halide CsPbBr3 nanowires (NWs) with appropriate lengths were synthesized by the method of ultrasonication synthesis assisted by the addition of hydrobromic acid (HBr) ligands. By adding HBr, the properties of synthesized NWs are improved, and due to the controllable perovskite-stretched NWs, polymer composite films were fabricated, which can generate photoluminescence (PL) with strong polarization. The optimized stretched composite film can achieve a polarization degree of 0.42 and dichroism ratio (I∥/I⊥) of 2.49 at 520 nm. Based on this film, an imaging system with polarization-selective properties and efficient UV spectral conversion was developed. The spectrum conversion of 266 to 520 nm luminescence wavelength was realized and sensitive to the polarization of incoming 266 nm UV light. The experimental results also showed that the response after spectral conversion is greatly improved, and different responsivities can correspond to different polarization states. This imaging system overcomes the insufficiency of the conventional charge coupled device (CCD), which makes it difficult to receive the optical signal for high-quality UV imaging. The use of light conversion films with polarization characteristics for polarized UV imaging is of great significance for improving the detection of solar-blind UV bands and the recognition of military targets.

A novel UV-fluorescence approach to assess the long wear efficacy of foundations.

BACKGROUND: The long wear properties of foundations are regarded as a must-have in terms of claims. Here, we propose an instrumental approach based on UV-fluorescence imaging as an alternative to clinical grading methods. METHODS: A method was developed, with UV-fluorescence images captured with the Visia CR as a first step, followed by images analysis using Image-Pro plus. Repeated-measures correlation was used to assess the degree of association between the UV-fluorescence method and a grading method when removing the foundation incrementally from the skin using wipes. Thresholds to ascertain whether a foundation pass or fail long-wearing using the newly developed method were established using a mixed linear model and cross-validated using two subsets of a panel of 20 women. RESULTS: The method could measure incremental removal of foundation using wipes, in a similar fashion to a grading method, as outlined with repeated measures correlation (r = -.86). Pass/fail thresholds established with the mixed linear model were tested versus the grading method when assessing a foundation under real conditions for a duration over 24 hours, with minimal discrepancies between the two methods. CONCLUSION: By capitalising on foundation physical/chemical properties, the proposed method allows to assess their long wear properties, irrespective of basal skin tone or foundation shade. It offers the advantage of appealing visuals for efficacy and to be less resource intensive than a clinical grading approach.

Formulation of co-amorphous systems from naproxen and naproxen sodium and in situ monitoring of physicochemical state changes during dissolution testing by Raman spectroscopy.

Co-amorphous systems comprising low-molecular weight drugs and co-formers constitute an interesting approach to optimize pharmaceutical performance of drugs with low aqueous solubility. Within the different types of co-amorphous systems, the combination of a drug with its own salt may be an attractive formulation option due the absence of any inactive co-formers. The aim of this study was to investigate the possibility of forming a co-amorphous system from naproxen (NAP) and its sodium salt (NAP(Na)). Ball milling of NAP and NAP(Na) at equal molar ratio resulted in the formation of a co-amorphous system whilst NAP and NAP(Na) alone were crystalline following both, ball milling and melt quenching. Infrared spectroscopy and physical stability testing revealed that intermolecular interactions were able to maintain the ball milled NAP-NAP(Na) system amorphous for 2 months at 40 °C. Surprisingly, the dissolution rate of co-amorphous NAP-NAP(Na) was only intermediate between those of crystalline NAP and crystalline NAP(Na). In situ Raman spectroscopic measurements indicated an initial phase separation of the co-amorphous form to NAP and NAP(Na) followed by dissociation of sodium from NAP(Na) and crystallization to NAP. These findings contribute to the design of co-amorphous formulations with the combination of a drug and its own salt.

Design and development of a novel fused filament fabrication (FFF) 3D printed diffusion cell with UV imaging capabilities to characterise permeation in pharmaceutical formulations.

The present work aimed at designing and developing a novel 3D printed diffusion cell capable of UV imaging using the fused filament fabrication (FFF) method. UV imaging has proven to be very versatile in the area of pharmaceutics giving insights into various phenomena including the dissolution behaviour of dosage forms, intrinsic dissolution rates and the drug precipitation processes. A 3D printed diffusion cell in the similitude of a Franz cell was successfully printed using polylactic acid (PLA) filaments equipped with quartz for the imaging area. A model ibuprofen (IBU) gel formulation was tested by introducing the dosage form through the 3D printed donor compartment. The drug concentration permeated through the skin mimic (silicone membrane) was determined from the 3D printed receptor compartment using UV imaging in real-time. The results showed successful UV imaging of the permeation of IBU gel in the novel diffusion cell potentially negating further analytical testing such as the HPLC process required for Franz cell tests thereby reducing costs. Potential interactions between the drug and filament used in the 3D printed process suggests although this concept can be moved towards commercialisation, care should be taken with choice of filament used in the 3D printing process.

An investigation into the use of low quantities of functional additives to control drug release from hot melt extruded solid dispersions for poorly soluble drug delivery.

The motivation of this study is to demonstrate the practicality of producing slow release and fast release products in a single-step hot melt extrusion (HME) process. HPMCAS as the carrier material showed good potential in monolithic controlled release formulations for the model drug, carbamazepine (CBZ). As binary formulations, CBZ-HPMCAS extrudates showed zero-order release over 24 h which was accompanied by the swelling of the extrudates. A range of functional excipients was used at low quantities to modulate the release rate. The release rates of the HME extrudates could be either accelerated by the incorporations of low quantities (5% w/w) of soluble additives or further sustained by adding lipid excipient, Gelucire 50/13. Clear phase separations of the soluble additives including crosscarmellose sodium, sodium starch glycolate, maltodextrin and lactose in the extrudates led to higher interior porosity and quicker erosion in comparison to the binary extrudates. The phase separated Gelucire in the extrudates led to the substantial swelling of the extrudates and resulted in further prolonged drug release. This study provided clear formulation strategies for modulating the drug release rate from controlled release formulation prepared directly by single-step HME. In addition, this research work also evaluates for the first time HME extrudates simultaneous swelling and drug release using this UV imaging technique. The whole dose cell of this instrumentation is utilised to provide insights into the dissolution process of solid dispersions prepared by HME.

Surface dissolution UV imaging for characterization of superdisintegrants and their impact on drug dissolution.

Superdisintegrants are a key excipient used in immediate release formulations to promote fast tablet disintegration, therefore understanding the impact of superdisintegrant variability on product performance is important. The current study examined the impact of superdisintegrant critical material attributes (viscosity for sodium starch glycolate (SSG), particle size distribution (PSD) for croscarmellose sodium (CCS)) on their performance (swelling) and on drug dissolution using surface dissolution UV imaging. Acidic and basic pharmacopoeia (compendial) media were used to assess the role of varying pH on superdisintegrant performance and its effect on drug dissolution. A highly soluble (paracetamol) and a poorly soluble (carbamazepine) drug were used as model compounds and drug compacts and drug-excipient compacts were prepared for the dissolution experiments. The presence of a swelled SSG or CCS layer on the compact surface, due to the fast excipient hydration capacity, upon contact with dissolution medium was visualized. The swelling behaviour of superdisintegrants depended on excipient critical material attributes and the pH of the medium. Drug dissolution was faster in presence compared to superdisintegrant absence due to improved compact wetting or compact disintegration. The improvement in drug dissolution was less pronounced with increasing SSG viscosity or CCS particle size. Drug dissolution was slightly more complete in basic compared to acidic conditions in presence of the studied superdisintegrants for the highly soluble drug attributed to the increased excipient hydration capacity and the fast drug release through the swelled excipient structure. The opposite was observed for the poorly soluble drug as potentially the improvement in drug dissolution was compromised by drug release from the highly swelled structure. The use of multivariate data analysis revealed the influential role of excipient and drug properties on the impact of excipient variability on drug dissolution.

Monitoring of Antimicrobial Drug Chloramphenicol Release from Electrospun Nano- and Microfiber Mats Using UV Imaging and Bacterial Bioreporters.

New strategies are continuously sought for the treatment of skin and wound infections due to increased problems with non-healing wounds. Electrospun nanofiber mats with antibacterial agents as drug delivery systems provide opportunities for the eradication of bacterial infections as well as wound healing. Antibacterial activities of such mats are directly linked with their drug release behavior. Traditional pharmacopoeial drug release testing settings are not always suitable for analyzing the release behavior of fiber mats intended for the local drug delivery. We tested and compared different drug release model systems for the previously characterized electrospun chloramphenicol (CAM)-loaded nanofiber (polycaprolactone (PCL)) and microfiber (PCL in combination with polyethylene oxide) mats with different drug release profiles. Drug release into buffer solution and hydrogel was investigated and drug concentration was determined using either high-performance liquid chromatography, ultraviolet-visible spectrophotometry, or ultraviolet (UV) imaging. The CAM release and its antibacterial effects in disc diffusion assay were assessed by bacterial bioreporters. All tested model systems enabled to study the drug release from electrospun mats. It was found that the release into buffer solution showed larger differences in the drug release rate between differently designed mats compared to the hydrogel release tests. The UV imaging method provided an insight into the interactions with an agarose hydrogel mimicking wound tissue, thus giving us information about early drug release from the mat. Bacterial bioreporters showed clear correlations between the drug release into gel and antibacterial activity of the electrospun CAM-loaded mats.