Comprehensive Studies of the Processes of the Molecular Transfer of the Momentum, Thermal Energy and Mass in the Nutrient Media of Biotechnological Industries

This article puts forward arguments in favor of the necessity of conducting complex measurements of molecular transport coefficients that quantitatively determine the coefficients of dynamic viscosity, thermal diffusivity and molecular diffusion. The rheological studies have been carried out on the viscometers of two types: those with a rolling ball (HÖPPLER® KF 3.2.), and those with a rotary one (Rheotest RN 4.1.). The thermophysical studies have been performed using the analyzer Hot Disk TPS 2500S. The measurements have been taken in the temperature range of 283 to 363 K. The concentration of dry substances has varied from 16.2 to 77.7% dry wt. An empirical equation for calculating the density of aqueous solutions of beet molasses has been obtained. The diagrams of the dependence of the dynamic viscosity on the shear rate in the range of 1 s−1 to 500 s−1 at different temperatures have been provided. The diagrams of the dependence of the coefficients of thermal conductivity and thermal diffusivity on the temperature and the concentration of dry substances have been presented, and empirical equations for their calculation have been obtained. The findings can be used for engineering calculations of hydrodynamic and heat-exchange processes in biotechnological equipment.

Design and manufacturing of an innovative rolling ball tool: A step forward towards the development of SPIF process

Incremental sheet forming (ISF) is an innovative forming technology which is widely used in various sectors of mechanical production. This is particularly useful for rapid prototyping and limited batch without a specific die. A new class of this method is single-point incremental forming (SPIF). This paper presents a comprehensive experimental investigation on the SPIF of Aluminum sheets, and, in particular, the influence of the forming tool is taken into account. A new rolling ball tool is designed to follow this, and the formability of the Aluminum sheets under the SPIF procedure is investigated for both new and conventional tools. Moreover, a number of important process parameters such as the feed rate, forming force, and surface roughness are considered in the experiments’ design. Finally, the optimal conditions in achieving a developed SPIF procedure in terms of the mentioned factors are reported and discussed. The findings of this work suggest that the surface quality after the forming process can be enhanced by 55% when using the new designed tool, while the forming force is reduced by 38% at the same time.

Improving the technology of rolling rail steels by a comprehensive optimization parameter

The authors have developed a technique for improving the rolling modes of rail steels based on a complex optimization parameter. The technology of rolling rail profiles in the roughing stands of rail-and-structural steel mills and the technology of rolling ball blanks and grinding balls from the rejection of continuously cast blanks of rail steels are selected as the methodology objects. The generalized optimization parameter is the generalized Harrington desirability function, which depends on the partial desirability indicators according to the criteria of energy efficiency, quality of rolled products, material conservation and mill productivity. The share of influence of the listed partial optimization criteria on the generalized desirability function is taken into account by using weighting coefficients. Justification of the coefficient values is based on the results of a comparative analysis of reserves for reducing costs or losses in value terms. An algorithm for applying the technique has been developed. The analysis and generalization of the available initial data and additional research were carried out as a part of the first block. These studies are aimed at obtaining justified analytical dependencies of particular optimization criteria and measured rolling parameters. The second block is justification of the specific direction of rolling modes, the choice of which is carried out on the basis of checking the compliance of boundary conditions. The third block includes development of the parameters of the new rolling mode and assessment of its applicability and effectiveness. The fourth block involves pilot testing of a new rolling mode in the conditions of an existing rolling mill and if it is necessary, adjusting the methodology for determining the forecast values of the measured indicators. With the use of the developed methodology, the modes of rolling of railway and sharp rails in the roughing stands of universal rail-and-structural steel mill of JSC “EVRAZ ZSMK” were improved, and the mode of rolling grinding balls from the rejection of rail blanks at the cross-screw rolling mill of JSC “GMZ” was changed. There is a significant improvement in the quality, technical and economic indicators, which indicates the effectiveness of the developed methodology.

A 3D Multidirectional Piezoelectric Energy Harvester using Rope-Driven Mechanism for Low Frequency and Ultralow Intensity Vibration Environment

Though numerous piezoelectric vibration energy harvesters (PVEHs) have been designed and investigated to provide power supply for wireless sensors or wearable devices, it remains a challenge for traditional PVEHs to work effectively in an environment of low frequency, low acceleration and multidirectional vibrations. This work presents a PVEH using a low-frequency energy-capturing resonant system formed by a rolling ball in a hemispherical shell and driven by a rope. Due to the symmetry of the sphere, the ball can be excited at multiple directions in 3D space, and the piezoelectric beam can be pulled by the ball through a rope in multiple directions. Thus, the efficient multidirectional energy harvesting under low frequency (< 10 Hz) and ultralow intensity (< 0.1 g) vibrations could be realized. A mass-spring-damper equivalent model was built to understand the operation mechanism of the proposed PVEH. The results show that the proposed PVEH has a potential to collect energy in any direction in 3D space, and could achieve a good angle bandwidth with 360° for φ and 240° for β under the excitation of a = 0.04 g, f = 6.8 Hz with the acceleration defined in the spherical coordinate system. The developed PVEH can generate 6.5 μW under a low-intensity excitation (0.03 g), and the normalized power density can reach 22.63 μW/(cm3g2Hz). Moreover, the minimum start-up acceleration analysis of the proposed PVEH indicates that the PVEH can capture multidirectional energy from vibrations as low as 0.01 g. In addition, both simulation and experimental study on rope redundancy and ball mass show that they can be used to adjust the device performance easily without structure re-fabrication. Overall, this study demonstrates a new mechanism that could effectively harvest low frequency, ultralow intensity and multidirectional vibration

Adsorption Behavior of Hydroquinone by Diatomite-based Porous Ceramsite

Diatomite-based porous ceramsite is a new kind of environmental material. In this study, ceramsite was prepared by wet grinding, a rolling-ball method, and high temperature-calcination using diatomite as the main raw material with the addition of a pore-forming agent and sintering assistant. X-ray diffraction, scanning electron microscopy, and mercury injection, were used to analyze the structure and characteristics of the prepared materials. Using hydroquinone as the target pollutant, the adsorption behavior of diatomite-based porous ceramsite was investigated. Results indicated that the diatomite-based porous ceramsite had a pore size ranging from 500 to 3000 nm, a specific surface area of 6.14 m2.g-1, and a porosity of 47.8%. When pH was 7, the removal rate and adsorption capacity of the hydroquinone by the diatomite-based porous ceramsite was 91.2% and 4.56 m2.g-1, respectively. In the adsorption process of hydroquinone by diatomite-based porous ceramsite, the diffusion of a liquid membrane was dominant, which could be better described by the quasi-first-order kinetic equation. The Langmuir and Koble-Corrigan equations had a higher fitting degree of data for the adsorption isotherms. The adsorption characteristics of the diatomite-based porous ceramsite are in accordance with the fixed-point adsorption of a single molecular layer and belong to a heterogeneous composite adsorption system. The correlation coefficient R2 and k value of hydroquinone adsorption by the diatomite-based porous ceramsite determined by the liquid film diffusion model were 0.848 and 0.0417, respectively.

Failures of Sliding Bearings

A mechanical part, which supports the moving part, is termed a mechanical bearing and can be classified into rolling (ball or roller) bearings and sliding bearings. This article discusses the failures of sliding bearings. It first describes the geometry of sliding bearings, next provides an overview of bearing materials, and then presents the various lubrication mechanisms: hydrostatic, hydrodynamic, boundary lubrication, elastohydrodynamic, and squeeze-film lubrication. The article describes the effect of debris and contaminant particles in bearings. The steps involved in failure analysis of sliding bearings are also covered. Finally, the article discusses wear-damage mechanisms from the standpoint of bearing design.

Characterisation of Bacteriophage-Encoded Depolymerases Selective for Key Klebsiella pneumoniae Capsular Exopolysaccharides

Capsular polysaccharides enable clinically important clones of Klebsiella pneumoniae to cause severe systemic infections in susceptible hosts. Phage-encoded capsule depolymerases have the potential to provide an alternative treatment paradigm in patients when multiple drug resistance has eroded the efficacy of conventional antibiotic chemotherapy. An investigation of 164 K. pneumoniae from intensive care patients in Thailand revealed a large number of distinct K types in low abundance but four (K2, K51, K1, K10) with a frequency of at least 5%. To identify depolymerases with the capacity to degrade capsules associated with these common K-types, 62 lytic phage were isolated from Thai hospital sewage water using K1, K2 and K51 isolates as hosts; phage plaques, without exception, displayed halos indicative of the presence of capsule-degrading enzymes. Phage genomes ranged in size from 41–348 kb with between 50 and 535 predicted coding sequences (CDSs). Using a custom phage protein database we were successful in applying annotation to 30 - 70% (mean = 58%) of these CDSs. The largest genomes, of so-called jumbo phage, carried multiple tRNAs as well as CRISPR repeat and spacer sequences. One of the smaller phage genomes was found to contain a putative Cas type 1E gene, indicating a history of host DNA acquisition in these obligate lytic phage. Whole-genome sequencing (WGS) indicated that some phage displayed an extended host range due to the presence of multiple depolymerase genes; in total, 42 candidate depolymerase genes were identified with up to eight in a single genome. Seven distinct virions were selected for further investigation on the basis of host range, phage morphology and WGS. Candidate genes for K1, K2 and K51 depolymerases were expressed and purified as his6-tagged soluble protein and enzymatic activity demonstrated against K. pneumoniae capsular polysaccharides by gel electrophoresis and Anton-Paar rolling ball viscometry. Depolymerases completely removed the capsule in K-type-specific fashion from K. pneumoniae cells. We conclude that broad-host range phage carry multiple enzymes, each with the capacity to degrade a single K-type, and any future use of these enzymes as therapeutic agents will require enzyme cocktails for utility against a range of K. pneumoniae infections.