Oral Drug Delivery Systems Comprising Altered Geometric Configurations for Controlled Drug Delivery

Recent pharmaceutical research has focused on controlled drug delivery having an advantage over conventional methods. Adequate controlled plasma drug levels, reduced side effects as well as improved patient compliance are some of the benefits that these systems may offer. Controlled delivery systems that can provide zero-order drug delivery have the potential for maximizing efficacy while minimizing dose frequency and toxicity. Thus, zero-order drug release is ideal in a large area of drug delivery which has therefore led to the development of various technologies with such drug release patterns. Systems such as multilayered tablets and other geometrically altered devices have been created to perform this function. One of the principles of multilayered tablets involves creating a constant surface area for release. Polymeric materials play an important role in the functioning of these systems. Technologies developed to date include among others: Geomatrix® multilayered tablets, which utilizes specific polymers that may act as barriers to control drug release; Procise®, which has a core with an aperture that can be modified to achieve various types of drug release; core-in-cup tablets, where the core matrix is coated on one surface while the circumference forms a cup around it; donut-shaped devices, which possess a centrally-placed aperture hole and Dome Matrix® as well as “release modules assemblage”, which can offer alternating drug release patterns. This review discusses the novel altered geometric system technologies that have been developed to provide controlled drug release, also focusing on polymers that have been employed in such developments

Multi-task learning boosted predictions of the remaining useful life of aero-engines under scenarios of working-condition shift

International audienc

Effect of freeze–thaw cycle on physical and mechanical properties and damage characteristics of sandstone

Abstract Rock deterioration under freeze–thaw cycles is a concern for in-service tunnel in cold regions. Previous studies focused on the change of rock mechanical properties under unidirectional stress, but the natural rock mass is under three dimensional stresses. This paper investigates influences of the number of freeze–thaw cycle on sandstone under low confining pressure. Twelve sandstone samples were tested subjected to triaxial compression. Additionally, the damage characteristics of sandstone internal microstructure were obtained by using acoustic emission (AE) and mercury intrusion porosimetry. Results indicated that the mechanical properties of sandstone were significantly reduced by freeze–thaw effect. Sandstone’ peak strength and elastic modulus were 7.28–37.96% and 6.38–40.87% less than for the control, respectively. The proportion of super-large pore and large pore in sandstone increased by 19.53–81.19%. We attributed the reduced sandstone’ mechanical properties to the degenerated sandstone microstructure, which, in turn, was associated with increased sandstone macropores. The macroscopic failure pattern of sandstone changed from splitting failure to shear failure with an increasing of freeze–thaw cycles. Moreover, the activity of AE signal increased at each stage, and the cumulative ringing count also showed upward trend with the increase of freeze–thaw number

Temporal and spatial distributions and influencing factors of HABs outbreaks around the north of Shandong Peninsula during 2000–2019: based on remote sensing images and field monitoring data

Red tides have many harmful effects on offshore ecosystem and even human health, which has become a global marine environmental problem. In recent years, the occurrence of red tides has become more frequent and extensive in the offshore area of China. As one of the important sea areas in northern China, the north of Shandong Peninsula is also facing the impact of red tides. Relevant data and information on red tides outbreaks around the north of Shandong Peninsula (This study refers to the coastal area of Yantai) from 2000 to 2019 were collected in this study, and then, the comprehensive human activity intensity model was constructed. It was found that the occurrence of red tides in this area had a certain aggregation on both temporal and spatial scales, and the reason was related to nearshore human activities. Different types of land cover in coastal zone had a more significant impact on the occurrence of red tides. The types of water and structures had a certain correlation with the occurrence of red tides

A Data Augmentation Boosted Dual Informer Framework for the Performance Degradation Prediction of Aero-Engines

International audienc

Cloning, Synthesis and Functional Characterization of a Novel α-Conotoxin Lt1.3

α-Conotoxins (α-CTxs) are small peptides composed of 11 to 20 amino acid residues with two disulfide bridges. Most of them potently and selectively target nicotinic acetylcholine receptor (nAChR) subtypes, and a few were found to inhibit the GABAB receptor (GABABR)-coupled N-type calcium channels (Cav2.2). However, in all of α-CTxs targeting both receptors, the disulfide connectivity arrangement “C1-C3, C2-C4” is present. In this work, a novel α4/7-CTx named Lt1.3 (GCCSHPACSGNNPYFC-NH2) was cloned from the venom ducts of Conus litteratus (C. litteratus) in the South China Sea. Lt1.3 was then chemically synthesized and two isomers with disulfide bridges “C1-C3, C2-C4” and “C1-C4, C2-C3” were found and functionally characterized. Electrophysiological experiments showed that Lt1.3 containing the common disulfide bridges “C1-C3, C2-C4” potently and selectively inhibited α3β2 nAChRs and not GABABR-coupled Cav2.2. Surprisingly, but the isomer with the disulfide bridges “C1-C4, C2-C3” showed exactly the opposite inhibitory activity, inhibiting only GABABR-coupled Cav2.2 and not α3β2 nAChRs. These findings expand the knowledge of the targets and selectivity of α-CTxs and provide a new structural motif to inhibit the GABABR-coupled Cav2.2

Experiment and Mechanism Investigation on Freezing-Thawing of Sandstone with Different Water Contents

Freezing-thawing cycles seriously affect the safety of underground engineering in cold regions. At present, most research studies focus on the effect of number and freezing temperature on freezing-thawing cycles. As another important factor, the mechanism of rock mass water content affecting freezing-thawing is less studied. This paper studied the influence of the water content on mechanical property, microstructure, and acoustic emission characteristics of sandstone. The results indicated that the uniaxial compressive strength (UCS) and elastic modulus (E) of sandstone after 20 freezing-thawing cycles decreased as the water content increased. However, the decreasing rate of UCS gradually decreased, while the decreasing rate of E gradually increased. Furthermore, the empirical formulas of UCS and E about water content were obtained. The porosity and plasticity of sandstone after 20 freezing-thawing cycles increased as the water content increased. The empirical formulas of UCS and E about water content were obtained. The porosity and plasticity of sandstone after 20 freezing-thawing cycles increased as the water content increased. The decreasing trend of UCS with porosity was the same as that of UCS with water content. The failure form of sandstone gradually changed from splitting failure to shear failure. The results of the acoustic emission test showed that the stress-strain curves combined with acoustic emission ring counting could reveal the damage evolution process of sandstone during loading

Fabrication of ZnO-Carbon Dots Composite via Microcrystalline Cellulose for Enhanced Photocatalytic Hydrogen Production under Simulated Sunlight Irradiation

The composite ZnO@CDs was prepared via the hydrothermal method. Microcrystalline cellulose (MCC) was used as the source of carbon dots (CDs). X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, and transmission electron microscopy analyses were used to characterize the structure and morphology of ZnO@CDs. The prepared ZnO showed a flake morphology with the exposed plane of (001). The X-ray photoelectron spectroscopy and photoluminescence spectroscopy (PL) characterization showed that CDs can be produced by decomposition of MCC and then attached on the surface of ZnO. The photocatalytic properties of ZnO@CDs were investigated under simulated sunlight irradiation. The hydrogen production reached 1240 µmol·g-1 in 30 min, which was much higher than the bare ZnO. The mechanism for the enhanced catalytic property of ZnO@CDs was studied. A high hydrogen production rate (2480 µmol·g-1·h-1) in the short term would enable ZnO@CDs to work as an emergency power supply by hydrogen production and use for restoring electricity and wireless communication in complicated situations