Preparation and evaluation of gel formulations for oral sustained delivery to dysphagic patients

Background: Oral sustained release gel formulations may provide a means of administering drugs to dysphagic and geriatric patients who have difficulties with handling and taking oral dosage forms. Aim: We have designed gel formulations for the oral administration of paracetamol with suitable rheological characteristics for ease of administration to patients with swallowing difficulties and sufficient integrity in the acidic environment of the stomach to achieve a sustained release of this drug. Method: Gels formed by gelatin, agar, gellan, pectin, and xyloglucan were assessed for suitable gel strength and in vitro and in vivo release characteristics. Results: Gellan (1.5%?w/v) and xyloglucan gels (1.5%?w/w) had acceptable gel strengths for ease of swallowing and retained their integrity in the rat stomach sufficiently well to sustain the release of paracetamol over a period of 6 hours. Comparison of 1.5%?xyloglucan gels with a commercially available preparation with identical paracetamol concentrations demonstrated improved sustained release properties of the xyloglucan gels. Conclusions: Gels formed by gellan and xyloglucan have suitable rheological and sustained release characteristics for potential use as vehicles for oral delivery of drugs to dysphagic patients.     

Oral Sustained Delivery of Theophylline and Cimetidine from In Situ Gelling Pectin Formulations in Rabbits

ABSTRACT

The aim of this study was to evaluate the potential of an in situ gelling pectin formulation as a vehicle for the oral sustained delivery of theophylline and cimetidine. In vitro studies demonstrated diffusion-controlled release of theophylline from 1, 1.5, and 2% w/v pectin gels. Release of this drug from 1.5% w/v pectin gels formed in situ in rabbit stomach was sustained over a period of 12 hours giving a theophylline bioavailability some seven fold higher than when administered from a commercial syrup. In contrast, interactions between cimetidine and pectin led to weak gelation of the pectin sols that prevented any meaningful determination of in vitro release characteristics. Similarly, in vivo release profiles from pectin formulations containing cimetidine were similar to that from a solution of this drug in buffer, indicative of weak gelation. Examination of the content of the rabbit stomach 5 hours after administration of 1.5% w/v pectin sols containing drug confirmed gel formation, but gels containing cimetidine were noticeably softer than those containing theophylline.     

A fully depleted lean-channel transistor (DELTA)-a novel verticalultrathin SOI MOSFET

A fully depleted lean-channel transistor (DELTA) that has a gate with a vertical ultrathin SOI structure is reported. In the deep submicrometer region, selective oxidation is useful in realizing SOI isolation. It provides high crystalline quality, as good as that of conventional bulk single-crystal devices. Using experiments and three-dimensional simulation, it was shown that the gate structure has effective channel controllability and its vertical ultrathin SOI structure provides superior device characteristics     

Development of a new loading test apparatus for microfocus X-ray CT and its application to the investigation of soil behavior surrounding driven open-section piles

In recent years, X-ray CT scanners with task-specific modifications, such as microfocus and/or a synchrotron, have been widely implemented in a variety of fields, including medical and industrial fields. Since microfocus X-ray CT systems enable the visualization of whole samples, and also yield a relatively high resolution of the region of interest in the sample, they are commonly utilized in the fields of soil mechanics and geotechnical engineering. This paper describes a novel loading test apparatus that is specifically designed for microfocus X-ray CT systems capable of performing loading tests to investigate soil behavior during the installation of driven open-section piles. The loading tests were designed to take the micro-level spatial resolution of microfocus X-ray CT systems into account. Digital image correlation (DIC) is subsequently implemented to analyze the obtained CT images, making it possible for measurements to be taken of the displacement fields in the ground following installation of the model pile. Finally, the versatility of this novel test apparatus is proof of its high potential for application in different types of loading tests.     

Low-temperature gasification of a woody biomass under a nickel-loaded brown coal char

Catalytic gasification of a woody biomass, Japanese cypress, was investigated under a prepared nickel-loaded brown coal (LY-Ni) char in a two-stage fixed-bed reactor. The nickel-loaded brown coal was prepared by ion-exchange method with a nickel loading rate of 8.3 wt.%. Nickel species dispersed well in the brown coal, and the LY-Ni char via devolatilization at 600 °C showed a great porous property with a specific surface area of 382 m² g^− 1.The LY-Ni char was confirmed to be quite active for the Japanese cypress volatiles gasification at a relatively low-temperature range from 450 to 650 °C. For example, at 550 °C, 16.6 times hydrogen gas and 6.3 times total gases were yielded from the catalytic steam gasification of Japanese cypress volatiles under the LY-Ni char, compared with the case of non-catalyst. The biomass tar decomposition showed a dependence on catalyst temperatures. When the catalyst temperature was higher than 500 °C, Japanese cypress tar converted much efficiently, high gas yields and high carbon balances were obtained.     

Stabilization of Finite Automata with Application to Hybrid Systems Control

This paper discusses the state feedback stabilization problem of a deterministic finite automaton (DFA), and its application to stabilizing model predictive control (MPC) of hybrid systems. In the modeling of a DFA, a linear state equation representation recently proposed by the authors is used. First, this representation is briefly explained. Next, after the notion of equilibrium points and stabilizability of the DFA are defined, a necessary and sufficient condition for the DFA to be stabilizable is derived. Then a characterization of all stabilizing state feedback controllers is presented. Third, a simple example is given to show how to follow the proposed procedure. Finally, control Lyapunov functions for hybrid systems are introduced based on the above results, and the MPC law is proposed. The effectiveness of this method is shown by a numerical example.     

Production of a functionally graded artificial tooth root by unique sequence of processes

 A unique sequence of processes is used to produce a prototype of a functionally graded artificial tooth root: (1) Dry-jet spraying of the mixture of Ti and Al₂O₃ ultrafine particles (UFPs) produced by radio-frequency plasma onto the surface of a cylindrical Ti rod, where the composition of the UFPs is changed gradually in the outward radial direction from Ti to Al₂O₃; (2) Temperature-gradient sintering of the deposited composite, where the Ti – and the Al₂O₃– rich sides are heated simultaneously at about 1400 K and 1800 K, respectively; (3) Plasma spray coating of hydroxyapatite (HAP) onto the outermost Al₂O₃ surface of the sintered composite. The final product has compressive strength of more than 200 MPa and is durable against fatigue test of 10⁷ stress cycles at 1000 N. The adhesion strength between the Ti substrate and the Ti-Al₂O₃ functionally graded layer exceeds 65 MPa. No contamination with heavy metals is detected throughout the processes and biological cell growth is confirmed to occur on the HAP surface. With these mechanical and biochemical properties the composite produced here is considered to be highly suitable for an artificial tooth root. A series of processes developed here are expected to be applied to the production of various kinds of fine-grained functionally graded materials with complicated forms. Received: 13 October 1997 / Accepted: 27 October 1997