Preparation and evaluation of sustained-release solid dispersions co-loading gastrodin with borneol as an oral brain-targeting enhancer

Borneol is a traditional Chinese medicine that can promote drug absorption from the gastrointestinal tract and distribution to the brain.However,stomach irritation may occur when high doses of borneol are used.In the present work,gastrodin,the main bioactive ingredient of the traditional Chinese drug“Tianma”(Rhizoma Gastrodiae)was used as a model drug to explore reasonable application of borneol.Sustained-release solid dispersions(SRSDs)for co-loading gastrodin and borneol were prepared using ethylcellulose as a sustained release matrix and hydroxy-propyl methylcellulose as a retarder.The dispersion state of drug within the SRSDs was analyzed by using scanning electron microscopy,differential scanning calorimetry,and powder X-ray diffractometry.The results indicated that both gastrodin and borneol were molecularly dispersed in an amorphous form.Assay of in vitro drug release demonstrated that the dissolution profiles of gastrodin and borneol from the SRSDs both fitted the Higuchi model.Subsequently,gastric mucosa irritation and the brain targeting of the SRSDs were evaluated.Compared with the free mixture of gastrodin and borneol,brain targeting of SRSDs was slightly weaker(brain targeting index:1.83 vs.2.09),but stomach irritation obviously reduced.Sustained-release technology can be used to reduce stomach irritation caused by borneol while preserving sufficient transport capacity for oral brain-targeting drug delivery.

Fabrication,microstructures,and optical properties of Yb:Lu_(2)O_(3) laser ceramics from co-precipitated nano-powders

The Yb:Lu_(2)O_(3)precursor made up of spherical particles was synthesized through the co-precipitation method in the water/ethanol solvent.The 5 at% Yb:Lu_(2)O_(3)powder is in the cubic phase after calcination at 1100℃ for 4 h.The powder also consists of spherical nanoparticles with the average particle and grain sizes of 96 and 49 nm,respectively.The average grain size of the pre-sintered ceramic sample is 526 nm and that of the sample by hot isostatic pressing grows to 612 nm.The 1.0 mm-thick sample has an in-line transmittance of 81.6%(theoretical value of 82.2%)at 1100 nm.The largest absorption cross-section at 976 nm is 0.96×1^(0-20)cm^(2) with the emission cross-section at 1033 nm of 0.92×10^(-20)cm^(2) and the gain cross sections are calculated with the smallest population inversion parameter β of 0.059.The highest slope efficiency of 68.7% with the optical efficiency of 65.1% is obtained at 1033.3 nm in quasi-continuous wave(QCW)pumping.In the case of continuous wave(CW)pumping,the highest slope efficiency is 61.0% with the optical efficiency of 54.1%.The obtained laser performance indicates that Yb:Lu_(2)O_(3)ceramics have excellent resistance to thermal load stresses,which shows great potential in high-power solid-state laser applications.

Fabrication and performance evaluation of novel transparent ceramics RE:Tb_(3)Ga_(5)O_(12)(RE=Pr,Tm,Dy)toward magneto-optical application

Transparent ceramics are at the heart of modern magneto-optical materials providing promising opportunities for Faraday isolators.1.0 at%RE:Tb3Ga5O12(rare earth(RE)=Pr,Tm,Dy)transparent ceramics were successfully prepared by air sintering and sequential HIP technique using the coprecipitated powders as the raw material.All the powders have shown to be a pure cubic terbium gallium garnet(TGG)phase and exhibit good dispersion.Additionally,a change could not be observed in particle shape with the different doped ions.After the two-step sintering,all the obtained ceramics have good optical quality,and the in-line transmittances at 1070 nm are higher than 80%.Moreover,no secondary phase can be detected from the microstructures.However,the pores which remain entrapped in the ceramics can be noted.The Verdet constant of ceramic samples is optimized by RE doping,and the Verdet constant at 632.8 nm is about−143 rad·T^(−1)·m^(−1),which is about 5%higher than that of TGG ceramics.Finally,the thermo-optical properties of 1.0 at%RE:TGG transparent ceramics are compared.The annealed TGG ceramic showed the best thermo-optical properties,and the thermally induced depolarization of 1.0 at%Ce:TGG and 1.0 at%Tm:TGG was inferior to that of annealed TGG ceramic.

Fabrication and properties of non-stoichiometric Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)magneto-optical ceramics

Non-stoichiometric Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)(x=-0.07-0.45)magneto-optical ceramics were fabricated by solid-state reactive sintering in vacuum combined with hot isostatic pressing(HIP)posttreatment without any sintering aids.The phase composition,densification process,microstructure,optical transmittance,and Verdet constant of Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics were investigated.The in-line transmittance of(Tb_(0.93)Hf_(0.04))_(2)Hf_(2)O_(7.07)ceramics with a thickness of 2.0 mm reaches 74.6%at 1064 nm.The Verdet constant of Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics is-153.4,-155.8,and-181.2 rad/(T-m)at the wavelength of 633 nm when x=-0.07,0,and 0.1,respectively.The Verdet constant increases with the increase of Tb content,and these values are higher than that of the commercial Tb_(3)Ga_(5)O_(12) crystal,indicating that non-stoichiometric Tb_(2)(Hf_(1-x)Tb_(x))_(2)O_(7-x)ceramics have a great potential for the application in Faraday isolators.