Modern Approaches to the Technology of Tablet Dosage Forms of Thioctic Acid (Review)

Introduction. Thioctic (α-lipoic) acid is an endogenous antioxidant and is used for liver diseases, poisoning with salts of heavy metals, hyperlipidemia, atherosclerotic heart disease, neuropathy, insulin-resistant forms of diabetes mellitus, etc. technologies for producing tableted medicinal preparations of thioctic acid, necessary for the pharmaceutical development of thioctic acid tablets at pharmaceutical industry enterprises.Text. The review considers the physicochemical properties of the pharmaceutical substance thioctic acid, the features of its pharmaceutical and technological properties, and compatibility with excipients. In the technology of thioctic acid tablets, methods of direct compression and compression with preliminary wet granulation, including those using organic solvents, are used. To increase photostability, thioctic acid tablets are coated. Information on excipients in the composition of core tablets and film coat of thioctic acid tablets registered in Russia is presented. The problems of tabletting thioctic acid are described: sintering of the granulate during the drying process, adhesion of the tabletting mass to the pressing tool and the resulting unevenness of the tablet surface. The ways of optimizing the tabletting process of thioctic acid using various compositions of excipients, improving the flowability of a pharmaceutical substance both during its synthesis and as a result of technological processing, choosing the optimal modes of granulation, drying, pressing are considered.Conclusion. As a result of the analysis of the literature data, the features of the technology for producing thioctic acid tablets were revealed, which are due to the high content of the pharmaceutical substance in tablets (up to 600 mg), the need to use a minimum amount of excipients (from 27 to 51 %), poor flowability, and low melting point of the pharmaceutical substance. Improvement of compressibility and prevention of adhesion can be achieved by using the pharmaceutical substance thioctic acid of a certain granulometric composition, auxiliary substances of the basic nature and a high content of glidants (up to 6 %). The identified manufacturing features should be taken into account in the pharmaceutical development of thioctic acid tablets.

Conceptual Design of an Attachment Based Reconfigurable Machine Tool Using Design Structure Matrix

There has been very little research in the field of Reconfigurable machine Tools (RMTs). None of the past research developed a method to design a set of RMT configurations required to machine a part-family. This thesis presents a novel method to determine the functional specifications of the RMT configurations required to machine a part-family. The method is developed by firstly designing the RMT required to machine a single part. Thereafter, this method is extrapolated to suit the problem of a part-family. To design the RMTs for a single part, firstly, the part is decomposed into manufacturing features. Next, a novel method is developed to cluster the features. Each of these feature-clusters corresponds to a single RMT configuration. Based on the machining requirements of these RMT configurations, the modules are designed. These modules are assembled to form the final RMTs. The method is demonstrated by applying it to an example part.

Conceptual Design of an Attachment Based Reconfigurable Machine Tool Using Design Structure Matrix

There has been very little research in the field of Reconfigurable machine Tools (RMTs). None of the past research developed a method to design a set of RMT configurations required to machine a part-family. This thesis presents a novel method to determine the functional specifications of the RMT configurations required to machine a part-family. The method is developed by firstly designing the RMT required to machine a single part. Thereafter, this method is extrapolated to suit the problem of a part-family. To design the RMTs for a single part, firstly, the part is decomposed into manufacturing features. Next, a novel method is developed to cluster the features. Each of these feature-clusters corresponds to a single RMT configuration. Based on the machining requirements of these RMT configurations, the modules are designed. These modules are assembled to form the final RMTs. The method is demonstrated by applying it to an example part.

Evaluation of geometrical benchmark artifacts containing multiple overhang lengths fabricated using material extrusion technique

Fused deposition modelling (FDM) is a process of joining materials based on material entrusion technique to produce objects from 3D model using layer-by-layer technique as opposed to subtractive manufacturing. However, many challenges arise in the FDM-printed part such as warping, first layer problem and elephant food that was led to an error in dimensional accuracy of the printed parts especially for the overhanging parts. Hence, in order to investigate the manufacturability of the FDM printed part, various geometrical and manufacturing features were developed using the benchmarking artifacts. Therefore, in this study, new benchmarking artifacts containing multiple overhang lengths were proposed. After the benchmarking artifacts were developed, each of the features were inspected using 3D laser scanner to measure the dimensional accuracy and tolerances. Based on 3D scanned parts, 80% of the fabricated parts were fabricated within ±0.5 mm of dimensional accuracy as compared with the CAD data. In addition, the multiple overhang lengths were also successfully fabricated with a very significant of filament sagging observed.

Graph-Based Feature Recognition and Combination Method for Automatic Process Planning System

Generating the Numerical Control (NC) tool path for machining a complex shaped component is highly dependent on the proficiency of a Computer-Aided Manufacturing (CAM) programmer in manufacturing field, although the CAM systems now are highly integrated. A Computer-Aided Process Planning (CAPP) system, which can automatically extract the manufacturing features from the Computer-Aided Design (CAD) model and generate the machining process planning, has been expected for a long time. In this research, a graph-based CAPP system was proposed. It mainly includes four modules, data conversion module, feature classification module, feature combination module and process planning module. The first two modules claim a graph-based feature recognition method, output the recognized manufacturing features which are classified into four classes and defined as specific types. The feature combination module generates different paths to combine manufacturing features from a goal model into raw material shape by four kinds of combination methods corresponding to the four classes. Finally, the process planning module will give a cost estimation of all those paths with the consideration of manufacturing resources and time cost. A relatively optimized machining method and machining sequence will be generated as the output of this proposed system.

Laboratory Rational of Changes in the Crystal Lattice of Nickel-Titanium Endodontic Rotary Files in Autoclaving

Objectives. The aim of this study was to investigate the changes of the crystal lattice of NiTi instruments after repeated autoclave sterilization cycles based on the results to conclude about the influence of multiple sterilization on the characteristics of ProTaper clinical use. Methods. 21 samples of ProTaper Universal rotary files were divided into 3 groups of 7 samples. After 1, 4, and 7 cycles of sterilization, the samples were observed using еnergy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). Results. EDS analysis confirmed that all samples were composed mainly of nickel and titanium, also Fe (presumably steel), Cr, Co, and Zn were found. The percentage of nickel and titanium was affected by repeated sterilization cycles. The mass fraction of Fe, Co, Zn, and Cr decreased after 1, 4, and 7 sterilization cycles. According to the results of the second study, it was found that, with increasing autoclaving cycles, the percentage of Fe decreased. There were changes in the three obtained diffractograms, which indicated an increase in the number of the martensitic phase and a decrease in austenitic. The cutting efficiency of the ProTaper is also reduced during repeated sterilization cycles, which can be caused by the austenitic and martensitic phase displacement. Conclusion. Manufacturing features and repeated sterilization cycles increase the internal deformation in the structure of NiTi alloy, which increases the risk of fracture.