Intravitreal brimonidine inhibits formdeprivation myopia in guinea pigs

Background:The use of ocular hypotensive drugs has been reported to attenuate myopia progression.This study explores whether brimonidine can slow myopia progression in the guinea pig form-deprivation(FD)model.Methods:Three-week-old pigmented male guinea pigs(Cavia porcellus)underwent monocular FD and were treated with 3 different methods of brimonidine administration(eye drops,subconjunctival or intravitreal injections).Four different concentrations of brimonidine were tested for intravitreal injection(2μg/μL,4μg/μL,20μg/μL,40μg/μL).All treatments continued for a period of 21 days.Tonometry,retinoscopy,and A-scan ultrasonography were used to monitor intraocular pressure(IOP),refractive error and axial length(AL),respectively.On day 21,guinea pigs were sacrificed for RNA sequencing(RNA-seq)to screen for associated transcriptomic changes.Results:The myopia model was successfully established in FD animals(control eye vs.FD eye,respectively:refraction at day 20,0.97±0.18 D vs.−0.13±0.38 D,F=6.921,P=0.02;AL difference between day 0 and day 21,0.29±0.04mm vs.0.45±0.03 mm,F=11.655,P=0.004).Among the 3 different brimonidine administration methods,intravitreal injection was the most effective in slowing myopia progression,and 4μg/μL was the most effective among the four different concentrations of brimonidine intravitreal injection tested.The AL and the refraction of the brimonidine intravitreal injection group was significantly shorter or more hyperopic than those of other 2 groups.Fourμg/μL produced the smallest difference in AL and spherical equivalent difference values.FD treatment significantly increased the IOP.IOP was significantly lower at 1 day after intravitreal injections which was the lowest in FD eye of intravitreal injection of brimonidine.At day 21,gene expression analyses using RNA-seq showed upregulation of Col1a1 and Mmp2 expression levels by intravitreal brimonidine.Conclusions:Among the 3 different administration methods,intravitreal injection of brimonidine was the most effective in slowing myopia progression in the FD guinea pig model.Intravitreal brimonidine at 4μg/μL significantly reduced the development of FD myopia in guinea pigs.Expression levels of the Col1a1 and Mmp2 genes were significantly increased in the retinal tissues of the FD-Inj-Br group.

Adsorption and photoreduction of Cr(Ⅵ)via diatomite modified by Nb2O5 nanorods

We report the design and synthesis of Nb2Os@diatomite composite materials.The composite materials are prepared by the hydrothermal conversion of raw diatomite and activated niobic acid powder in ammonium oxalate aqueous solution,with various hydrothermal reaction durations.The specific surface area of the diatomite modified by Nb2Os nanorods reaches a maximum of 153 m2 /g,which is almost five times higher than that of raw diatomite.Insights are gained into the function of sodium dodecyl benzene sulfonate and the mechanism of loading Nb2O5 on diatomite in the solution phase.The controllable growth dynamics allow the morphology and production of the Nb2O5@diatomite structure to be controlled.Adsorption experiments indicate that the diatomite modified by Nb2O5 nanorods is an effective adsorbent for quickly removing Cr(Ⅵ) from wastewater at room temperature.The maximum adsorption capacity is 115 mg/g.The Cr(Ⅵ) removal capacity is further improved under ultraviolet light irradiation,owing to the synergistic effect of surface adsorption and Nb2O5 photoreduction.The composite therefore has potential practical application.

Controlled synthesis of Zeolite adsorbent from lowgrade diatomite:A case study of self-assembled sodalite microspheres

Highly efficient and sustainable conversion technologies to generate uniform sodalite(Na8(AlSiO4)6(OH)2)zeolite micro spheres with low-grade waste natural diatomite as raw materials via a solution-mediated crystallization route were developed in the present study.The synthesis process can be considered as an in-situ zeolitization of diatomite precursor without involving any me so scale template and any post-synthetic modification.The mass ratios of diatomite and AlCl3·6 H2 O have remarkable effect on the morphology,crystal structure and porosity of sodalite zeolite product.The preferred sodalite microspheres with uniform mesoporous of size 3.5-5.5 nm and large surface area of 162.5 m2/g exhibit well removal performance for heavy metal ions(Pb(II),Cd(II),Zn(II),and Cu(II)),with the highest adsorption abilities for Pb(II)ions of 365 mg/g.In addition,the effect of contact time,initial ion concentration,competitive adsorption and solution pH were evaluated.The removal performance results from synergistic effects of dominating cation-exchange and additional surface chemisorption.The study may broadly help unveil chemical control reactions of the zeolitization processes of diatomite,and thus facilitates the development of promising zeolite materials for the use in natural and engineered aquatic environments by recvcling waste diatomite resources.

Flower-, wire-, and sheet-like MnO_2-deposited diatomites:Highly efficient absorbents for the removal of Cr(Ⅵ)

Flower-, wire-, and sheet-like MnO2-deposited diatomites have been prepared using a hydrothermal method with Mn（Ac）2, KMnO4 and/or MnSO4 as Mn source and diatomite as support. Physical properties of the materials were characterized by means of numerous analytical techniques, and their behaviors in the adsorption of chromium（VI） were evaluated. It is shown that the IvinO2-deposited diatomite samples with different morphologies possessed high surface areas and abundant surface hydroxyl groups （especially the wire-like MnO2/diatomite sample）. The wire-like MnO2/diatomite sample showed the best performance in the removal of Cr（VI）, giving the maximum Cr（VI） adsorption capacity of 101 mg/g.

Nb_2O_5 nanowires in-situ grown on carbon fiber: A high-efficiency material for the photocatalytic reduction of Cr(Ⅵ)

Niobium oxide nanowire-deposited carbon fiber（CF） samples were prepared using a hydrothermal method with amorphous Nb2O5·nH2O as precursor. The physical properties of the samples were characterized by means of numerous techniques, including X-ray diffraction（XRD）, energy-dispersive spectroscopy（EDS）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, selected-area electron diffraction（SAED）, UV–visible spectroscopy（UV–vis）, N2 adsorption–desorption, Fourier transform infrared spectroscopy（FT-IR）, and X-ray photoelectron spectroscopy. The efficiency for the removal of Cr（VI） was determined.Parameters such as pH value and initial Cr（VI） concentration could influence the Cr（VI） removal efficiency or adsorption capacity of the Nb2O5/carbon fiber sample obtained after hydrothermal treatment at 160°C for 14 hr. The maximal Cr（VI） adsorption capacity of the Nb2O5 nanowire/CF sample was 115 mg/g. This Nb2O5/CF sample also showed excellent photocatalytic activity and stability for the reduction of Cr（Ⅵ） under UV-light irradiation： the Cr（VI） removal efficiency reached 99.9% after UV-light irradiation for 1 hr and there was no significant decrease in photocatalytic performance after the use of the sample for 10 repeated cycles. Such excellent Cr（VI） adsorption capacity and photocatalytic performance was related to its high surface area,abundant surface hydroxyl groups, and good UV-light absorption ability.

Intravitreal brimonidine inhibits formdeprivation myopia in guinea pigs

Background:The use of ocular hypotensive drugs has been reported to attenuate myopia progression.This study explores whether brimonidine can slow myopia progression in the guinea pig form-deprivation(FD)model.Methods:Three-week-old pigmented male guinea pigs(Cavia porcellus)underwent monocular FD and were treated with 3 different methods of brimonidine administration(eye drops,subconjunctival or intravitreal injections).Four different concentrations of brimonidine were tested for intravitreal injection(2μg/μL,4μg/μL,20μg/μL,40μg/μL).All treatments continued for a period of 21 days.Tonometry,retinoscopy,and A-scan ultrasonography were used to monitor intraocular pressure(IOP),refractive error and axial length(AL),respectively.On day 21,guinea pigs were sacrificed for RNA sequencing(RNA-seq)to screen for associated transcriptomic changes.Results:The myopia model was successfully established in FD animals(control eye vs.FD eye,respectively:refraction at day 20,0.97±0.18 D vs.−0.13±0.38 D,F=6.921,P=0.02;AL difference between day 0 and day 21,0.29±0.04mm vs.0.45±0.03 mm,F=11.655,P=0.004).Among the 3 different brimonidine administration methods,intravitreal injection was the most effective in slowing myopia progression,and 4μg/μL was the most effective among the four different concentrations of brimonidine intravitreal injection tested.The AL and the refraction of the brimonidine intravitreal injection group was significantly shorter or more hyperopic than those of other 2 groups.Fourμg/μL produced the smallest difference in AL and spherical equivalent difference values.FD treatment significantly increased the IOP.IOP was significantly lower at 1 day after intravitreal injections which was the lowest in FD eye of intravitreal injection of brimonidine.At day 21,gene expression analyses using RNA-seq showed upregulation of Col1a1 and Mmp2 expression levels by intravitreal brimonidine.Conclusions:Among the 3 different administration methods,intravitreal injection of brimonidine was the most effective in slowing myopia progression in the FD guinea pig model.Intravitreal brimonidine at 4μg/μL significantly reduced the development of FD myopia in guinea pigs.Expression levels of the Col1a1 and Mmp2 genes were significantly increased in the retinal tissues of the FD-Inj-Br group.