Polymer in Pharmaceutical Drug Delivery System

The current review article focuses on polymers in pharmaceutical drug delivery of therapeutic agents. These dosage forms include tablets, patches, tapes, films, semisolids and powders. Polymers are the backbone of a pharmaceutical drug delivery system as they control the release of the drug from the device. Biodegradable polymers attracts the attention of its use as they can be degraded to non‐toxic monomers and most important, a constant rate of drug release can be achieved from a biodegradable polymer based controlled release device. Natural polymers can be used as the means of achieving predetermined rates of drug delivery and their physico‐chemical characteristics with the ease of availability provide a platform to use it as a polymer for drug delivery systems. Biodegradable polymers have been widely used in biomedical applications because of their known biocompatibility and biodegradability. In the biomedical area, polymers are generally used as implants and are expected to perform long term service. These improvements contribute to make medical treatment more efficient and to minimize side effects and other types of inconveniences for patients. The main role of polymer is to protect drug from physiological environment and prolong release of drug to improve its stability. The drug is release from polymer by diffusion, degradation and swelling. In addition to this review presents characteristics and behaviours of plant derived and mucoadhesive polymers which are currently used in drug delivery.

Methods of manufacture and innovations in steel aerosol cans’ production

The production of aerosols has had a significant position in the industry for many years. We use aerosol products almost every day for very different purposes. The aerosol industry growth very dynamically, the shapes and the materials of the containers are changing, but the main principle remains the same – “aerosol dispenser shall mean any non-reusable container made of metal, glass or plastic and containing a gas compressed, liquefied or dissolved under pressure, with or without a liquid, paste or powder, and fitted with a release device allowing the contents to be ejected as solid or liquid particles in suspension in a gas, as a foam, paste or powder or in a liquid state”. The purpose of this article is to present the methods of aerosols’ steel can manufacture together with the changes that have been made over the last century. Since the beginning of aerosol industry metal is the main material from which aerosol containers are made of, and steel is one of the most popular raw materials, the main law requirements regarding aerosol containers made of steel will be analysed. As the consequence of these analyses, the future possible development directions will be shown.

Reactive Oxygen Species-Responsive Miktoarm Amphiphile for Triggered Intracellular Release of Anti-Cancer Therapeutics

Reactive oxygen species (ROS)-responsive nanocarriers have received considerable research attention as putative cancer treatments because their tumor cell targets have high ROS levels. Here, we synthesized a miktoarm amphiphile of dithioketal-linked ditocopheryl polyethylene glycol (DTTP) by introducing ROS-cleavable thioketal groups as linkers between the hydrophilic and hydrophobic moieties. We used the product as a carrier for the controlled release of doxorubicin (DOX). DTTP has a critical micelle concentration (CMC) as low as 1.55 μg/mL (4.18 × 10−4 mM), encapsulation efficiency as high as 43.6 ± 0.23% and 14.6 nm particle size. The DTTP micelles were very responsive to ROS and released their DOX loads in a controlled manner. The tocopheryl derivates linked to DTTP generated ROS and added to the intracellular ROS in MCF-7 cancer cells but not in HEK-293 normal cells. In vitro cytotoxicity assays demonstrated that DOX-encapsulated DTTP micelles displayed strong antitumor activity but only slightly increased apoptosis in normal cells. This ROS-triggered, self-accelerating drug release device has high therapeutic efficacy and could be a practical new strategy for the clinical application of ROS-responsive drug delivery systems.

Experimental Analysis on Heat Release of Pulsating Heat Pipe Phase Change Regenerator with Different Working Fluids

In order to improve the problems of serious energy waste and low utilization rate, this paper designs and builds an experimental platform for a pulsating heat pipe type phase change heat storage device. The temperature changes with time in the heat storage and release device of the barium hydroxide octahydrate phase change material under different working conditions is studied. The results show that during the heat release process, when the pulsating heat pipe is filled with water, the cooling water temperature rises to the highest, and the heat recovery rate is as high as 64%. Otherwise, the initial temperature of the cooling water during the heat release process is studied. Result shows that the initial temperature of the cooling water increases, the longer the latent heat of phase change and the total heat release time, and the higher the temperature rise of the cooling water. The experimental design of this paper can provide a reference for researchers in related fields.

Development of On-Board Tilt Mirror Calibration Mechanism without Holding and Release Mechanism

The on-board tilting mirror calibration mechanism has a mechanical driving part that helps to achieve the main functional modes of deployment and stow when calibrating a spaceborne imaging sensor. In general, it is necessary to consider a holding and release device in the mechanism design, to secure the structural safety of the mechanical driving part in severe launch environments. However, in the present study, we proposed a novel design strategy based on mass balancing, to guarantee mechanical safety on the driving part of the tilt mirror mechanism, although the implementation of the holding and release mechanism was not considered in the design. The effectiveness of the proposed design was experimentally verified via launch vibration and life cycle tests. The test results demonstrated that the mechanism fulfills all the required functions, and the design approach proposed in this study is effective for ensuring mechanical safety on the driving part of the tilting mirror mechanism in severe launch vibration environments.

Electrospun coaxial hyaluronan-based fiber networks for ophthalmic drug release

A micro-sized core-shell drug release device has been prepared by coaxial electrospinning based on a polylactide shell and the inner core phase made of high molecular weight hyaluronan or a cross-linked hyaluronan network. Timolol, which was inserted into the core phase, is widely used as drug for glaucoma treatment to depress the intraocular eye pressure and should be released over a longer time period from this fiber networks. Release studies of drug loaded fiber devices showed an only moderate burst release of timolol in the first days followed by a continuous longlasting drug release period over several weeks. With these findings, coaxial electrospinning represents a promising approach for the development of drug release systems with long-lasting, relatively constant drug delivery.

Use of Intravaginal Progesterone-Releasing Device Results in Similar Pregnancy Rates and Losses to Long-Acting Progesterone to Synchronize Acyclic Embryo Recipient Mares

The objectives of this study were: (1) to assess uterine features and serum progesterone concentrations of acyclic mares synchronized and resynchronized with intravaginal progesterone release device (IPRD), and (2) to compare pregnancy rates and losses of cyclic and acyclic embryo recipient mares treated with different synchronization protocols. In Experiment 1, mares (n = 12) received estradiol for 3 days (E2-3d), and then 24 h after the last injection, an IPRD was inserted and kept in place for 9 days. Three days after IPRD removal, mares were treated with E2-3d, and then a new IPRD was inserted and maintained for three days. Serum progesterone concentrations were assessed 2, 6, and 12 h after insertion and removal of IPRD, and then daily from the insertion of the first IPRD to one day after removal of the second IPRD. Experiment 2 was conducted with embryo recipient mares randomly assigned to four groups: (1) Cyclic: mares (n = 75) had ovulation confirmed after receiving a single dose of histrelin when a periovulatory follicle was first detected, (2) LAP4: acyclic mares (n = 92) were treated with E2-3d and then administered a single dose of LAP4 24 h after the last estradiol injection, (3) IPRD: acyclic mares (n = 130) were treated with E2-3d and an IPRD for 4–8 days, and (4) RE-IPRD: acyclic mares (n = 32) were synchronized as in the IPRD group but not used for embryo transfer (ET), then 8 to 15 days later, the mares were resynchronized with E2-3d and an IPRD for 4–8 days. In vivo-produced Day-8 embryos were collected and transferred 4–8 days after ovulation or progesterone treatments. Mares in IPRD and RE-IPRD groups had the intravaginal device removed immediately before ET, and then a new IPRD was inserted right after ET. Pregnancy diagnosis was performed at 5, 30, and 60 days after ET. Once pregnancy was confirmed, mares in the three acyclic groups received weekly injections of LAP4 (1.5 g) until 120 days of pregnancy. Mares in IPRD and RE-IPRD groups had the device removed three days after the first pregnancy diagnosis. In Experiment 1, progesterone concentrations increased rapidly starting 2 h after insertion of IPRD (p < 0.05); then, concentrations plateaued well above pregnancy maintenance until removal on days 9 and 3, respectively. Progesterone concentrations were reduced to baseline 24 h after IPRD removal (p < 0.05). For experiment 2, there was no difference in pregnancy rates across groups (65–74%) or pregnancy losses by 60 days of gestation (7–12%) (p > 0.05). In conclusion, the IPRD used herein resulted in a rapid increase and a sharp decline in progesterone concentrations upon its insertion and removal, respectively. Finally, our results demonstrated that IPRD could be a compatible alternative to LAP4 to synchronize and resynchronize acyclic embryo recipient mares.

Numerical simulation and application of micro-nano bubble releaser for irrigation

In oxygenated irrigation, there are problems of large oxygenated bubble particles, low oxygen concentration in water, and mismatch with current irrigation systems. In this paper, numerical simulation of micro-nano bubble releaser was carried out and the development of oxygenated irrigation equipment was studied. The release method of dissolved gas was selected to generate micro-nano bubbles after comparing different micro-nano bubble generation methods. The basic structure of the core-component releaser of generating micro-nano bubbles was initially determined. Effects of different structures of the release device on water aeration performance were studied by CFD analysis method. An optimal structure of the releaser was determined with orthogonal experiments based on a single factor experiment. The structural parameters included a throat of a 3 mm diameter, a 2 mm thick turbulent cavity, a six-degree exit angle, and two outlets. Optimal inlet and outlet pressure difference of the release device was 0.3 MPa. The bubble had an average particle size of 373.1 nm as measured. The release device was fabricated by 3D printing technology and the micro-nano bubble aeration irrigation device was developed. The system function test was carried out. Under the standard state, the performance parameters of the micro-nano bubble aerator included the maximum oxygen concentration of 11.4 mg/L, a total oxygen transfer coefficient of 0.4139 min-1, 0.0114 kg/h oxygenation capacity, and 60.81% oxygen utilization rate. The device had advantages of a high oxygen-increasing efficiency and a small volume, making it quite prospective in the field of oxygenated irrigation.