Boosting the Electrocatalytic Conversion of Nitrogen to Ammonia on Metal-Phthalocyanine-Based Two-Dimensional Conjugated Covalent Organic Frameworks.

The electrochemical N2 reduction reaction (NRR) under ambient conditions is attractive in replacing the current Haber-Bosch process toward sustainable ammonia production. Metal-heteroatom-doped carbon-rich materials have emerged as the most promising NRR electrocatalysts. However, simultaneously boosting their NRR activity and selectivity remains a grand challenge, while the principle for precisely tailoring the active sites has been elusive. Herein, we report the first case of crystalline two-dimensional conjugated covalent organic frameworks (2D c-COFs) incorporated with M-N4-C centers as novel, defined, and effective catalysts, achieving simultaneously enhanced activity and selectivity of electrocatalytic NRR to ammonia. Such 2D c-COFs are synthesized based on metal-phthalocyanine (M = Fe, Co, Ni, Mn, Zn, and Cu) and pyrene units bonded by pyrazine linkages. Significantly, the 2D c-COFs with Fe-N4-C center exhibit higher ammonia yield rate (33.6 µg h-1 mgcat-1) and Faradaic efficiency (FE, 31.9%) at -0.1 V vs reversible hydrogen electrode than those with other M-N4-C centers, making them among the best NRR electrocatalysts (yield rate >30 µg h-1 mgcat-1 and FE > 30%). In situ X-ray absorption spectroscopy, Raman spectroelectrochemistry, and theoretical calculations unveil that Fe-N4-C centers act as catalytic sites. They show a unique electronic structure with localized electronic states at Fermi level, allowing for stronger interaction with N2 and thus faster N2 activation and NRR kinetics than other M-N4-C centers. Our work opens the possibility of developing metal-nitrogen-doped carbon-rich 2D c-COFs as superior NRR electrocatalyst and provides an atomic understanding of the NRR process on M-Nx-C based electrocatalysts for designing high-performance NRR catalysts.

Electron radiation effects on the structural and electrical properties of MoS2 field effect transistors.

The effects of space radiation on the structural and electrical properties of MoS2 field effect transistors (FETs) were investigated. The 1 MeV electronically equivalent International Space Station (ISS) track was used to apply fluence equivalent to the orbital for 10 (1.0 × 1012 cm-2) and 30 years (3.0 × 1012 cm-2) using the AP8 and AE8 models. X-ray photoelectron spectroscopy (XPS), Raman and photoluminescence (PL) spectra were recorded before and after irradiation. Electron irradiation produced strong desulfurization effects in MoS2 FETs. The PL spectra before and after irradiation did not change significantly, while the [Formula: see text] and A1g Raman modes were red- and blue-shifted, respectively. The XPS results demonstrated a strong desulfurization effect of the electron beam on MoS2. This reduction indicates a much higher amount of irradiation-induced S vacancies compared to Mo vacancies. The electrical characteristics of the device were measured before and after irradiation. The increase in the channel leakage current after irradiation was attributed to the oxide trapping positive charges. MoS2 FETs irradiated by the electron-beam demonstrated a decreased current. This phenomenon can be attributed to the combination of the states at the SiO2/MoS2 interfaces and Coulomb scattering. Our study provides a deeper understanding of the influence of 1 MeV electron-beam irradiation on MoS2-based nano-electronic devices for future space applications.

Modulation of electronic and optical properties by surface vacancies in low-dimensional ß-Ga2O3.

Calculations using the Heyd-Scuseria-Ernzerhof screened hybrid functional reveal the detailed influence that surface vacancies have on the electronic and optical properties of low-dimensional (LD) ß-Ga2O3. Vacancies manifest subtle changes to the electronic characteristics as oxygen states predominate the valence band at the surface. Dielectric functions at the surface are found to increase with vacancies and defects. A broad impact on optical properties, such as absorption coefficients, reflectivity, refractive indices, and electron loss, is seen with increased vacancy defects. Both visible and infrared regions show direct correlation with vacancies while there is a marked decrease in the deep ultraviolet (UV) region. These calculations on the ß-Ga2O3 model system may guide the rational design of two-dimensional optical devices with minimized van der Waals forces.

Cardiotonic Pill Reduces Myocardial Ischemia-Reperfusion Injury via Increasing EET Concentrations in Rats.

Accumulating data suggest that epoxyeicosatrienoic acids (EETs) and 20-hydroxyeicosatetraenoic acid, both cytochrome P450 (P450) enzyme metabolites of arachidonic acid (AA), play important roles in cardiovascular diseases. For many years, the cardiotonic pill (CP), an herbal preparation derived from Salviae Miltiorrhizae Radix et Rhizoma, Notoginseng Radix et Rhizoma, and Borneolum Syntheticum, has been widely used in China for the treatment of coronary artery disease. However, its pharmacological mechanism has not been well elucidated. The purpose of this study was to investigate the chronic effects of the CP on myocardial ischemia-reperfusion injury (MIRI) and AA P450 enzyme metabolism in rats (in vivo) and H9c2 cells (in vitro). The results showed that CP dose dependently (10, 20, and 40 mg/kg/d; 7 days) mitigated MIRI in rats. The plasma concentrations of EETs in CP-treated ischemia-reperfusion (I/R) rats (40 mg/kg/d; 7 days) were significantly higher (P < 0.05) than those in controls. Cardiac Cyp1b1, Cyp2b1, Cyp2e1, Cyp2j3, and Cyp4f6 were significantly induced (P < 0.05); CYP2J and CYP2C11 proteins were upregulated (P < 0.05); and AA-epoxygenases activity was significantly increased (P < 0.05) after CP (40 mg/kg/d; 7 days) administration in rats. In H9c2 cells, the CP also increased (P < 0.05) the EET concentrations and showed protection in hypoxia-reoxygenation (H/R) cells. However, an antagonist of EETs, 14,15-epoxyeicosa-5(Z)-enoic acid, displayed a dose-dependent depression of the CP's protective effects in H/R cells. In conclusion, upregulation of cardiac epoxygenases after multiple doses of the CP-leading to elevated concentrations of cardioprotective EETs after myocardial I/R-may be the underlying mechanism, at least in part, for the CP's cardioprotective effect in rats.

The cardioprotection of dihydrotanshinone I against myocardial ischemia-reperfusion injury via inhibition of arachidonic acid ω-hydroxylase.

Arachidonic acid (AA) is a precursor that is metabolized by several enzymes to many biological eicosanoids. Accumulating data indicate that the ω-hydroxylation metabolite of AA, 20-hydroxyeicosatetraenoic acid (20-HETE), is considered to be involved in the myocardial ischemia-reperfusion injury (MIRI). The inhibitors of AA ω-hydroxylase, however, are demonstrated to exhibit protective effects on MIRI. Dihydrotanshinone I (DI), a bioactive constituent of danshen, is proven to be a potent inhibitor of AA ω-hydroxylase by our preliminary study in vitro. The purpose of the present study was to investigate the cardioprotection of DI against MIRI and its effects on the concentrations of 20-HETE in vivo. Rats subjected to 30 min of ischemia followed by 24 h of reperfusion were assigned to intravenously receive vehicle (sham and ischemia-reperfusion), low (1 mg/kg), middle (2 mg/kg), or high (4 mg/kg) doses of DI before reperfusion. The results demonstrated that DI treatment could improve cardiac function, reduce infarct size, ameliorate the variations in myocardial zymogram and histopathological disorders, decrease 20-HETE generation, and regulate apoptosis-related protein in myocardial ischemia-reperfusion rats. These findings suggested DI could exert considerable cardioprotective action on MIRI by the attenuation of 20-HETE generation, subsequent myocardial injury, and apoptosis through inhibition on AA ω-hydroxylase.

Theoretical Study of the Reactive Mechanisms of Li-Doped Ni-Based Oxygen Carrier during Chemical Looping Combustion.

Ni-based oxygen carriers (OCs) are considered promising materials in the chemical looping combustion (CLC) process. However, the reactivity of Ni-based OCs still offers the potential for further enhancement. In this work, the Li doping method has been employed for the modification of Ni-based OCs. The reactivity and microreaction mechanisms of different concentrations of Li-doped Ni-based OCs with CO in CLC are clarified using density functional theory (DFT) simulation. The structures, energy, and density of states are obtained through computational investigation of the reaction path in elementary reactions. The results show that (1) the adsorption energies of CO molecules on NiO surfaces with 4, 8, and 12% Li doping concentrations are -0.53, -0.48, and -0.54 eV, respectively, demonstrating an enhanced reactivity compared to that of pure NiO (-0.41 eV); (2) the calculation of the transition state indicates that the most favorable pathway for CO oxidation takes place on the surface of NiO with an 8% Li doping concentration, exhibiting the lowest energy barrier of 0.51 eV; and (3) the oxygen vacancy formation energies on the surface of NiO are 3.05, 2.30, and 2.10 eV for 4, 8, and 12% doping concentrations, respectively. Additionally, the decrease in oxygen vacancy formation energies exhibits a gradual decline with an increasing Li doping concentration. By comprehensive analysis, 8% is considered to be the optimal doping concentration of NiO for chemical looping combustion.

Leading officials' accountability audit of natural resources and haze pollution: evidence from China.

Leading officials' accountability audit of natural resources (AANR) is a major institutional arrangement for China to promote the construction of an ecological civilization. Based on city-level panel data from 2010 to 2017, this study investigates the role of AANR on haze pollution by the difference-in-differences (DID) and spatial DID models. The results show that the AANR significantly reduces the haze pollution of pilot cities, and this conclusion remains robust under multiple scenarios, such as the parallel trend test, tendency score matching, placebo test, and excluding the policy interference in the same period. The AANR promotes the governance of haze pollution in pilot areas, mainly by improving environmental control and increasing financial investment in environmental protection. Furthermore, the promotion effect of the AANR on haze governance has strong heterogeneity with regard to urban air quality; eastern, central, and western regions; legal environment; and public attention. The AANR not only reduces the haze pollution of pilot cities but also has a spatial spillover effect on neighboring areas, but this effect is not pronounced. Therefore, it is of great significance for haze pollution control to continuously promote and improve the departure audit of natural resource assets, perform audit work according to local conditions, and establish interregional cooperative mechanisms.

Challenges and strategies for ocular posterior diseases therapy via non-invasive advanced drug delivery.

Posterior segment diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) are vital factor that seriously threatens human vision health and quality of life, the treatment of which poses a great challenge to ophthalmologists and ophthalmic scientists. In particular, ocular posterior drug delivery in a non-invasive manner is highly desired but still faces many difficulties such as rapid drug clearance, limited permeability and low drug accumulation at the target site. At present, many novel non-invasive topical ocular drug delivery systems are under development aiming to improve drug delivery efficiency and biocompatibility for better therapy of posterior segment oculopathy. The purpose of this review is to present the challenges in the noninvasive treatment of posterior segment diseases, and to propose strategies to tackle these bottlenecks. First of all, barriers to ocular administration were introduced based on ocular physiological structure and behavior, including analysis and discussion on the influence of ocular structures on noninvasive posterior segment delivery. Thereafter, various routes of posterior drug delivery, both invasive and noninvasive, were illustrated, along with the respective anatomical obstacles that need to be overcome. The widespread and risky application of invasive drug delivery, and the need to develop non-invasive local drug delivery with alternative to injectable therapy were described. Absorption routes through topical administration and strategies to enhance ocular posterior drug delivery were then discussed. As a follow-up, an up-to-date research advances in non-invasive delivery systems for the therapy of ocular fundus lesions were presented, including different nanocarriers, contact lenses, and several other carriers. In conclusion, it seems feasible and promising to treat posterior oculopathy via non-invasive local preparations or in combination with appropriate devices.

Elucidating interactive effects of sulfidated nanoscale zero-valent iron and ammonia on anaerobic digestion of food waste.

In our previous study, anaerobic digestion of food waste could be effectively enhanced by adding sulfidated nanoscale zero-valent iron (S-nZVI) under high-strength ammonia concentrations. In this study, in order to further elucidate the specific interactive effects of S-nZVI and ammonia on anaerobic digestion of nitrogen-rich food waste, the methanogenic performance of anaerobic digestion systems respectively added with nanoscale zero-valent iron (nZVI) and S-nZVI were compared and monitored under different ammonia stress conditions. Both nZVI and S-nZVI could effectively stimulate the methanogenesis process among ammonia concentrations ranging from 0 to 3500 mg/L. However, the enhancing effects of S-nZVI and nZVI on anaerobic digestion of food waste were different, in which anaerobic digestion systems added with S-nZVI and nZVI performed best under 2500 mg/L of ammonia and 1500 mg/L of ammonia, respectively. Furthermore, the analysis of microbial communities suggested that ammonia stress enriched acetoclastic methanogens, while adding nZVI and S-nZVI into anaerobic digestions stimulated the process of hydrogenotrophic methanogenesis. Moreover, S-nZVI performed better in promoting the evolution of DIET-related microorganisms than nZVI, resulting in enhanced methane production under high ammonia-stressed conditions. This work provided fundamental knowledge about the interactive effects of S-nZVI and ammonia on the anaerobic digestion of food waste.

Exploring the potential to enhance drug distribution in the brain subregion via intranasal delivery of nanoemulsion in combination with borneol as a guider.

The number of people with Alzheimer's disease (AD) is increasing annually, with the nidus mainly concentrated in the cortex and hippocampus. Despite of numerous efforts, effective treatment of AD is still facing great challenges due to the blood brain barrier (BBB) and limited drug distribution in the AD nidus sites. Thus, in this study, using vinpocetine (VIN) as a model drug, the objective is to explore the feasibility of tackling the above bottleneck via intranasal drug delivery in combination with a brain guider, borneol (BOR), using nanoemulsion (NE) as the carrier. First of all, the NE were prepared and characterized. In vivo behavior of the NE after intranasal administration was investigated. Influence of BOR dose, BOR administration route on drug brain targeting behavior was evaluated, and the influence of BOR addition on drug brain subregion distribution was probed. It was demonstrated that all the NE had comparable size and similar retention behavior after intranasal delivery. Compared to intravenous injection, improved brain targeting effect was observed by intranasal route, and drug targeting index (DTI) of the VIN-NE group was 154.1%, with the nose-to-brain direct transport percentage (DTP) 35.1%. Especially, remarkably enhanced brain distribution was achieved after BOR addition in the NE, with the extent depending on BOR dose. VIN brain concentration was the highest in the VIN-1-BOR-NE group at BOR dose of 1 mg/kg, with the DTI reaching 596.1% and the DTP increased to 83.1%. BOR could exert better nose to brain delivery when administrated together with the drug via intranasal route. Notably, BOR can remarkably enhance drug distribution in both hippocampus and cortex, the nidus areas of AD. In conclusion, in combination with intranasal delivery and the intrinsic brain guiding effect of BOR, drug distribution not only in the brain but also in the cortex and hippocampus can be enhanced significantly, providing the perquisite for improved therapeutic efficacy of AD.

Consolidation of hydrogenotrophic methanogenesis by sulfidated nanoscale zero-valent iron in the anaerobic digestion of food waste upon ammonia stress.

The feasibility of adding sulfidated nanoscale zero-valent iron (S-nZVI) into anaerobic systems to improve anaerobic digestion of food waste (FW) under ammonia stress was evaluated in this study. The addition of S-nZVI improved the methane production compared to nanoscale zero-valent iron (nZVI), indicating that sulfidation significantly reinforced the enhancement effect of nZVI in consolidating the hydrogenotrophic methanogenesis. The promoted methanogenic performance was associated with chemical reaction and variances of microbial community induced by S-nZVI. With the characteristics of generation of Fe2+ and slow-release of H2, S-nZVI made the anaerobic system respond positively in facilitating extracellular polymeric substances secretion and optimizing the microbial community structure. Moreover, microbial community analysis showed that S-nZVI addition enriched the species related to biohydrogen production (e.g., Prevotella) and ammonia-tolerant hydrogenotrophic methanogenesis (e.g., Methanoculleus), possibly enhancing the hydrogenotrophic methanogenesis pathway to accelerate methane production. Therefore, adding S-nZVI into the anaerobic systems might propose a feasible engineering strategy to improve the methanogenic performance of the anaerobic digestion of FW upon ammonia stress.

A collaborative strategy for enhanced anaerobic co-digestion of food waste and waste activated sludge by using zero valent iron and ferrous sulfide.

The application of sulfidated zero-valent iron as an alternative used in coupled anaerobic systems to improve methane production is usually restricted by its high production costs and toxic gasses and wastewater generation. In this study, a collaborative strategy for coupling zero-valent iron (ZVI) and ferrous sulfide (FeS) together into anaerobic systems was used to evaluate the enhancement of methanogenesis during the co-digestion of food waste and waste activated sludge, with the microbial evolution and metabolic pathway revealed. Results showed that the enhanced hydrolysis and acidogenesis process of co-digestion in this coupled anaerobic system could be attributed to synergistic interactions among ZVI, FeS, and microorganisms. Furthermore, both acetoclastic and hydrogenotrophic pathways could be promoted by coupling ZVI and FeS. This study demonstrated that coupling ZVI and FeS together into anaerobic systems would be a promising method for improving the methanogenic performance for municipal solid waste treatment.

Fungal mash enzymatic pretreatment combined with pH adjusting approach facilitates volatile fatty acids yield via a short-term anaerobic fermentation of food waste.

As an alternative for commercial enzyme, crude enzyme of fungal mash could promote food waste (FW) hydrolysis, but its specific effects coupled pH adjusting on the production of volatile fatty acids (VFAs) remains unknown. The crude enzyme produced from an Aspergillus awamori, named complex-amylase (CA), was added to short-term anaerobic system of FW fermentation. Results showed that adding CA significantly improved the solubility and degradability of biodegradable and non-biodegradable organics in FW, where the SCOD concentration with adding CA increased by 116.9% relative to the control but a marginal enhancement on VFAs yield. In contrast, adding CA combined with adjusting pH 8 markedly increased the VFAs production to 32.0 g COD/L, almost 10 times as much as the control. Besides, pH adjusting altered the metabolic pathway from lactate-type to butyrate-type. Adding CA coupled pH adjusting significant increase the component of butyrate compared with pH adjusting alone. Moreover, microbial community analysis indicated that adding CA reinforced proportion of the butyrate-producing bacteria (e.g., Dialister) under basic conditions, thus enhancing the butyrate metabolic pathways. This study demonstrated that fungal mash pretreatment coupled pH conditioning could be an economical way to enhance VFAs yield for FW valorization during anaerobic fermentation.

Monodispersed CaCO3@hydroxyapatite/magnetite microspheres for efficient and selective extraction of benzoylurea insecticides in tea beverages samples.

A novel monodispersed CaCO3@hydroxyapatite/magnetite microsphere (CaCO3 @HAP/Fe3O4) was prepared via an in-situ growth strategy, and applied as an adsorbent for efficient and selective adsorption of benzoylurea insecticides (BUs) in various tea beverages samples. The sorbent exhibited uniformity in particle size, good mono-dispersibility and excellent solvent stability. The adsorption equilibrium of BUs (100 ng/mL) in 10 mL of tea beverages samples was achieved on 20 mg of CaCO3 @HAP/Fe3O4 within 10 min. The adsorption followed pseudo-second-order kinetics and Langmuir models and the maximum adsorption capacities of 131.9-161.3 mg/g were accomplished via hydrophobic interactions, hydrogen bonding, and the affinity of F atom and Ca2+. Coupled with high performance liquid chromatography, the method offered wide linear ranges of 0.8-1000 ng/mL with correlation coefficients (r) ≥ 0.9995, low limits of detection of 0.2-0.3 ng/mL and large enrichment factors of 75.7-102. The recoveries ranged from 75.7%- 102% with intra- and inter-day precisions of 1.9%- 9.3% and 1.6%- 11.8%, respectively. In addition, CaCO3 @HAP/Fe3O4 could be easily regenerated and reused at least 10 times with no significant loss of recovery. These results revealed an alternative strategy for fast and convenient determination of BUs in tea beverages samples and proved the great feasibility of CaCO3 @HAP/Fe3O4 in the application for the selective adsorption of BUs.

Rapid initiation of methanogenesis in the anaerobic digestion of food waste by acclimatizing sludge with sulfidated nanoscale zerovalent iron.

Although coupling of sulfidated nanoscale zero-valent iron (S-nZVI) into anaerobic digestion of food waste (FW) for improving methanogenesis has been reported, the specific role of S-nZVI during start-up process and its influence on subsequent methanogenesis and system stability remains unknown. In this study, S-nZVI was added into the unacclimatized sludge system to investigate its influence on microbial acclimatization and methanogenic performance. During acclimatization phase, CH4 production improved and VFAs transformation facilitated with the addition of S-nZVI. Furthermore, enzymatic activity analysis and electrochemical measurements presented direct evidence that electron transfer capacity of acclimatized sludge was significantly improved. S-nZVI favored the transition of microbial community to a robust and specialized population. During evaluation phase, acclimatized sludge still exhibited strong methanogenic ability, but the microbial community inevitably changed under the stress of FW. This research provides a novel perspective on initiating anaerobic digestion of FW for shorter start-up time and stronger methanogenesis.

Chlorine doping of MoSe2 flakes by ion implantation.

The efficient integration of transition metal dichalcogenides (TMDs) into the current electronic device technology requires mastering the techniques of effective tuning of their optoelectronic properties. Specifically, controllable doping is essential. For conventional bulk semiconductors, ion implantation is the most developed method offering stable and tunable doping. In this work, we demonstrate n-type doping in MoSe2 flakes realized by low-energy ion implantation of Cl+ ions followed by millisecond-range flash lamp annealing (FLA). We further show that FLA for 3 ms with a peak temperature of about 1000 °C is enough to recrystallize implanted MoSe2. The Cl distribution in few-layer-thick MoSe2 is measured by secondary ion mass spectrometry. An increase in the electron concentration with increasing Cl fluence is determined from the softening and red shift of the Raman-active A1g phonon mode due to the Fano effect. The electrical measurements confirm the n-type doping of Cl-implanted MoSe2. A comparison of the results of our density functional theory calculations and experimental temperature-dependent micro-Raman spectroscopy data indicates that Cl atoms are incorporated into the atomic network of MoSe2 as substitutional donor impurities.

Design of circular-ring film embedded contact lens for improved compatibility and sustained ocular drug delivery.

Contact lenses are ideal medical devices to sustain the release of ophthalmic drugs. However, the incorporation of drug loaded system can cause visual obstruction and poor oxygen/light permeability which restrict the application of contact lens for long-term wearing. Inspired by the physiological structure of our human eyes, we assume a circular-ring type inner layer embedded CLs might be a good solution to address the above-mentioned problems. In this study, taking betaxolol hydrochloride (BH) as a model drug, its complex with ion exchange resin was used as a carrier for adjusting drug loading amount, which is being dispersed into circular-ring shape Eudragit® S100 film as an inner layer, silicone-based hydrogel as the outer layer. Influence of resin particle size and drug/S100 ratio on drug release profiles was investigated. It was demonstrated that using resin as a carrier can not only increase drug loading amount but also sustain drug release, with the drug release rate well-tuned by either changing particle size of the resin or S100 ratio. Meanwhile S100 can well function as a pH-triggered drug release matrix, with limited drug leakage in the storage medium. Light transmittance of over 97% was achieved in the novel circular-ring layer-embedded CLs. Oxygen permeability coefficient (Dk) of the circular-ring film embedded CLs was 31.1 ± 3.7 barrer, similar to that of pure CLs. The sustained drug release behavior of this circular-ring embedded CLs was also well demonstrated in vivo. A level A IVIVC between in vitro drug release and in vivo drug concentration in tear fluid of the circular-ring embedded CLs was established. In conclusion, this circular-ring embedded contact lens is very promising for ophthalmic drug delivery with enhanced compatibility, sustained and pH triggered drug release characteristics.

Comparison of thermosensitive in situ gels and drug-resin complex for ocular drug delivery: In vitro drug release and in vivo tissue distribution.

Conventional ophthalmic eye drops are limited by their rapid elimination rate and short time of action. Ion exchange resin has been used to achieve sustained ocular drug delivery but the high selectivity of drug molecules restricts its broad application. In situ gel system seems to be a good strategy to address these problems but the influence of in situ gel type on the sustained release behavior and tissue distribution after ocular application is unclear. Therefore, in this study, using betaxolol hydrochloride as a model drug, poloxamer 407 and methylcellulose as the carriers, two thermosensitive in situ gel systems were prepared and characterized. Influence of formulation composition type and concentration on in vitro drug release was studied. Tissue distribution after ocular delivery of two different thermosensitive in situ gels was studied and compared with commercial BH eye drop (Betoptic S®). In vitro studies demonstrated that addition of 4% HPMC 606W in 15% P407 solution and 5% PEG4000 in 2% MC solution obtained gels with appropriate gelation temperature and similar sustained drug release rate. In vivo tissue distribution study indicated that they presented similar drug concentration in cornea, iris-ciliary and aqueous humor irrespective of gel type, with higher drug concentration achieved after 4 h compared to the commercial resin suspension eye drops. The AUC and MRT of the two in situ gel eye drops were 2 times higher than that of the commercial resin suspension eye drops in cornea. In conclusion, the two thermosensitive in situ gels have prolonged drug release after ocular drug delivery compared with ion exchange resin eye drops, implying their potential applications in clinic with broad drug adoptability.

Inner layer-embedded contact lenses for ion-triggered controlled drug delivery.

Drug leakage during manufacturing and storage process is the main obstacle hindering the application of contact lenses as the carrier for extended ocular drug delivery. In this study, we have designed a novel inner layer-embedded contact lens capable of ion-triggered drug release for extended ocular drug delivery. Using betaxolol hydrochloride as a drug model, drug-ion exchange resin complex dispersed polymer film was used as an inner layer, and silicone hydrogel was used as an outer layer to fabricate inner layer-embedded contact lens. Influence of composition of the inner film and crosslinking degree of the outer hydrogel on drug release profile was studied and optimized for weekly use. The ion-triggered drug eluting property enables the inner layer-embedded contact lens being stable when stored in distilled water at 5 °C for at least 30 days with ignorable drug loss and negligible changes in drug release kinetics. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 168 h in tear fluid, indicating significant improvement in drug corneal residence time. A level A IVIVC was established between in vitro drug release and in vivo drug concentration in tear fluid. In conclusion, this inner layer embedded contact lens design could be used as a platform for extended ocular drug delivery with translational potential for both anterior and posterior ocular disease therapy.

Interaction between hydrogen and gallium vacancies in ß-Ga2O3.

In this paper, the revised Heyd-Scuseria-Ernzerhof screened hybrid functional (HSE06) is used to investigate the interaction between hydrogen with different concentrations and gallium vacancies in ß-Ga2O3. The hydrogen can compensate a gallium vacancy by forming hydrogen-vacancy complex. A gallium vacancy can bind up to four hydrogen atoms, and formation energies decrease as the number of hydrogen atoms increases. Hydrogen prefers to bind with three coordinated oxygen. The bonding energy and annealing temperatures of complexes containing more than two hydrogen atoms are computed, and show relatively high stability. In addition, vacancy concentrations increase with the increasing vapor pressures. This paper can effectively explain the hydrogen impact in ß-Ga2O3.