Krzysztof Jan Siczek

Development of the rectal dosage form with silver-coated glass beads for local-action applications in lower sections of the gastrointestinal tract

Abstract Context: Recent findings indicating the anti-inflammatory action of silver preparations through modulation of the gut microbiota and apoptosis of inflammatory cells predestine silver use in inflammatory bowel disease (IBD). Objective: The aim of our study was to validate the possibility of effective silver release from silver-coated glass beads for anti-inflammatory local application in the lower sections of the gastrointestinal (GI) tract. Materials and methods: Silver-coated glass beads were prepared using magnetron method. Release of silver from the silver-coated glass bead surface was carried out in BIO-DIS reciprocating cylinder apparatus. Erosion of silver coating and indirect estimation of the silver release dynamics was assessed using scanning electron microscope. Rectal suppositories containing silver-coated glass beads were prepared using five different methods (M1–M5) and X-ray scanned for their composition. Results and discussion: The XR microanalysis and the chemical composition analysis evidenced for a rapid (within 30 min) release of nearly 50% of silver from the coating of the glass beads, which remained stable up to 24 h of incubation. The most homogeneous distribution of beads in the entire volume of the suppository was obtained for formulation M5, where the molten base was poured into mold placed in an ice bath, and the beads were added after 10 s. Conclusions: Our study is the first to present the concept of enclosing silver-coated glass beads in the lipophilic suppository base to attenuate inflammation in the lower GI tract and promises efficient treatment with reduced side effects.

Non-linear method of determining vehicle pre-crash speed based on tensor B-spline products with probabilistic weights — Intermediate car class

In the following study we consider the Intermediate Car Class. We apply a novel non-linear method, where the work W of car deformation is defined as an algebraic function of deformation ratio Cs. We use the data from the NHTSA (National Highway Traffic Safety Administration) database comprising numerous frontal crash tests. On the basis of this database, we determine the mathematical model parameters. In the so-called energetic approach, collisions are treated as non-elastic. The velocity threshold that defines the elastic collision was set to be 11km/h. Such an approach, which greatly simplifies our considerations, determines the linear dependence of energy lost during deformation on deformation coefficient Cs. The coefficient Cs is calculated as a weighted mean value of deformation points C1-C6. In this paper, the authors suggest a more precise non-linear method in order to determine the work of deformation.

Research on valve trains

This chapter presents testing methods and testers used during studies on the valve train and its components, friction, wear, and noise therein. It also discusses the computer simulation of friction and wear at the nodes valve–guide and valve–seat insert. The chapter analyzes the effect of the wear of components of the studied system on the sum of flows in the gap between the valve stem and guide and between the seat faces of the valve and its insert. The chapter also presents the simplified simulation algorithm for the analyzed system. In subsequent iterations, the geometrical and material parameters of the system components can be changed, which makes the model very flexible. On the basis of calculations carried out by this algorithm, a rough estimation of how much time is required for the repair of the seat insert–lightweight valve–guide system can be obtained.

Future valve train systems

In this chapter, the properties of camless valve drives in comparison to classical cam drives are discussed. Particularly, the concept, design, and analysis of the electromagnetic drive, including its single and multiply version, are presented. Next, the concept and design of different versions of electromechanic valve drives are presented. Also, different realizations of electrohydraulic valve drives are discussed, And functional models for them are presented. The electropneumatic valve drive is analyzed. The advantages and disadvantages of the previously mentioned valve drives are presented. Special attention is placed on the problem of obtaining small values for the valve settling speed.

Spark-ignition engine valve trains

In the chapter was presented the division of the systems of valve drives in terms of complexity: without adjusting valve timing and valve lifts, with adjustable timing, with the stepwise adjustable valve lifts and adjustable timing, with stepless adjustable valve lifts and adjustable timing. It was also presented the division of variable valve timing systems: the mechanisms for changing the position of the camshaft relative to the crankshaft, the mechanisms for changing the duration of the valve opening and possibly valve lift, modern engine valve drive solutions, other manners to change the timing. Some of them are only the prototypes. It was presented also the camshaft-based mechanisms for the valve variable operation in the produced engines. It was discussed the variable valve timing via shifting the camshaft phases, including Alfa Romeo camshaft phaser, Suzuki camshaft phaser, Mazda S-VT system, Toyota VVT-i systems, BMW VANOS system and the double-VANOS system, Delphi Variable Cam Phaser, Rover VVC system, Mahle CamInCam system. It was also discussed the variable valve timing via special design, including the Suzuki SNVT system, the Porsche VarioCam system. It was described tribological processes arising in such systems.

Valve train thermodynamic effects

In the chapter was explained the term ‘valve events’, ant their role was discussed on the basis of changes in cylinder volume in a phase relationship with the valve opening profile. Particularly it was presented the effects of changes to Outlet (Exhaust) Valve Opening Timing—EVO, to Outlet Valve Closing Timing—EVC, to Inlet Valve Opening Timing—IVO, to Inlet Valve Closing Timing—IVC. It was discussed also the role of Inlet (Intake) Cam Phasing, Outlet (Exhaust) Cam Phasing, Dual-Equal Cam Phasing and Dual-Independent Cam Phasing. Recently the different Cold-Start Valve Phasing Strategies have become very important area of studies on the engine operation. In the chapter was discussed also the role of Valve Overlap, Valve Stroke, Exhaust Gas Recirculation (EGR). Also it was presented the effect of Valve Timing on Effective Compression Ratio, In-cylinder turbulence, the exhaust temperature, the over-expansion and turbo charging. It was presented different Two- and Three-Step Strategy of Variable Valve Actuation and also strategies for full variable valve timing control.

Chapter 6 – Valve train kinetic effects

In the chapter was described the control cycle of valve motion, consisting of: Run-up Phase (elimination of valve clearance), Operating motion Phase, Run-down Phase (formation of valve clearance), Cut-off the drive Phase. It was also discussed operating conditions of the valve train components. Special attention was put on valve rotation and auxiliary rotation system used in modern engines. It was also analysed the effect of misalignment of seat insert relative to valve guide, forces loading elements of valve train, especially of the friction nature. Also it was discussed the role of stiffness of valve train, contact between cam and follower, cam profile, valve spring, lash adjusters and hydraulic chain tensioners. It was also discussed the friction phenomena in the nodes of the cam valve train with fixed phases. In the chapter it was presented the criteria for the tribological quality of the system. It was explained, that the optimum valve motion is possible if it is obtained the required values of quality indicators, including: filling of the area under the curve of valve lift, the extreme value of the positive geometric acceleration, an extreme negative acceleration, extreme geometric speed, the speed of valve settling, rhe radius of curvature of the cam track, determination of the angle ϕ1 of the maximum speed of the valve (modified Turkish and Derdinger criterion), the intensity ratio of vibrations generated by the cam extortion of drive motion throughout the cam.

Chapter 7 – Valve train tribology

In the chapter the term tribology was explained. It was discussed the tribological problems occurring in the guide-lightweight valve-seat insert subsystem. The basic concepts related to the friction were shown, including the dry, boundary, mixed and liquid friction and tribofilms. It was also presented guidelines for the design of the model for the guide-valve-seat insert assembly treated as a tribological system. It was created the model of friction in friction pairs the system including the valve head–oil–pollutant-seat insert subsystem and the valve stem–oil-pollutant-guide subsystem. Different models of friction and method of friction compensation were discussed. Also the wear process of friction pairs the mentioned system was analyzed and related model of wear was created.

Compression-ignition engine valve trains

In the chapter it was presented valve timing control systems used in CI engines. Phasers used in SI engines are insufficient in the case of the CI engines. Instead of them the systems ensuring control of the rising period or opening period of the valve are used. These include: systems of direct action: electro-hydraulic and electro-magnetic, hydraulic systems of “lost lift”, profile generation systems—delta sT, Meta, variable speed systems. The main differences in operation of the systems were evident in the courses of valves lifts while changing valve timing. Such courses of valves lifts were also presented in the chapter. It was also discussed the use of variable valve control system for the standard CI engines. Also the summary for the review of the cam valve drives used in both SI and CI with their short comparison was included.

Advanced mechanical valve train design and analysis

In the chapter it was presented solutions obtaining variable valve stroke by switching the cam profile. They include different Honda VTEC systems, Mitsubishi MIVEC system, Nissan NVCS system, Nissan Neo VVL system, CamPro CPS system, Delphi 2-Step Valve Lift System and Yamaha Variable Valve Actuation system. It was also discussed systems with continuous change of valve stroke, including Nissan VVEL system, Toyota Valvematic system, Presta DeltaValveControl system. Further it was presented solutions with variable valve lift, connecting the valve timing change and changing of the profile. They include Porsche VarioCam Plus system, Toyota VVTL-i system. It was also presented solutions for variable control of the valves via the camshaft, including BMW Valvetronic system, Fiat Fully-Variable-Valve-Train system, UniValve system, Meta VVH System. Additionally it was summarized the review of the cam valve drives.