Porosity Formation in Thin Welded Joints of Al–MG–LI Alloys

This work is about the study of the correlation of pore formation in welded joints of Al–MG–LI alloy with zirconium additives with the state of the base metal, thermal vacuum treatment, and welding technologies MIG and EBW. Metallographic analysis has been carried out, the phase composition of the alloy and weld metal has been investigated, and thermal cycles of welding have been calculated, allowing to estimate the residence time of metal in the alloying zone and weld metal in the liquid state. The nature of the allocation of strengthening fine-dispersed phases in the welded joints of the alloy has been determined. The regularity and character of pore formation in welded joints depending on the applicable thermal vacuum treatment (TVT) and welding technology have been revealed. It was established that TVT with subsequent hardening and aging has no effect on the phase composition of the alloy. However, this type of treatment contributes to the formation of a more homogeneous and uniform nature of the separation of fine-dispersed strengthening phases. It was revealed that the MIG technology (metal with and without TVT) is characterized by a large length of the fusion zone, the high residence time of metal in the fusion zone and weld metal in the liquid state, and the formation of pores. Phase formation in the temperature range of the beginning and end of the alloy crystallization occurs not only in the weld at the final stage of crystallization but also in the fusion zone, which may induce pore formation, whereas EBW welding shows the opposite trend and no pores. It was found that EBW technology prevents pore formation and makes it possible to obtain welded joints of 1420 Al alloys of the required quality.

MODERN PHYSICAL METHODS IN MANAGING SUPPURATIVE WOUNDS

Suppurative and inflammatory processes in soft tissues make up a considerable share, 35 – 40%, in the structure of surgical problems in inpatients. Suppurative and inflammatory processes are often characterized as acute, resulting in systemic infection, sepsis, and even fatal outcomes. In the total structure of lethal outcomes in surgical inpatient departments the mortality rate due to acute surgical infection makes up 40 – 60%. Long hospital treatment, insufficient effectiveness of existing treatment methods, additional expenses for recovery and rehabilitation put this issue in the forefront of the most challenging healthcare tasks. This review states out that management of suppurative wounds is still remaining the most pressing for surgeons nowadays. Despite the rich experience and ever-increasing techniques and approaches in treating suppurative wounds, the elaboration of more effective physical methods to stimulate the healing of the wounds seems to be promising. The physical methods can include vacuum treatment, laser and ultrasound wound treatment, ozon therapy, hyperbaric oxygenation, phototherapy, hydropress sanation. The above methods can considerably contribute to the wound treatment thus promote its rapid healing. However, each of the techniques listed has its own disadvantages (technical, biological, economical), and can be applied only at a particular stage of wound healing. In-depth analysis of all advantages and shortcomings, contraindications to each method, enables to improve the treatment outcomes for patients with suppurative wounds thus reducing the time of hospital staying and expenses.

New combined method of the thermoplastics turning

The article presents the results of experimental studies of thermoplastic turning with the use of advancing vacuum treatment of the work piece surface. It has been experimentally proven that turning thermoplastics with advancing vacuum treatment of the surface of the work pieces leads to a better machined surface of the part in comparison with the traditional turning method.

Synthesizing Aluminum Matrix Composites by Combining a Powder Metallurgical Technique and an In Situ Method

A method of synthesizing dispersion-strengthened aluminum matrix composites using a powder metallurgical technique and an in situ method was considered. Methods combination was aimed at ensuring energy efficiency, avoiding vacuum treatment of the reaction medium, and using inert gasses to protect from oxidation. Reinforcement phase precursors are capable of ensuring good wettability of dispersed particles by the molten matrix metal. The options of the methods’ practical implementation are presented by the example of producing aluminum matrix composites filled with various functional particles.

A New Approach for Determining Compressibility and Permeability Characteristics of Dredged Slurries with High Water Content

In the vacuum treatment of dredged slurries via prefabricated vertical drains (PVDs), both filtration and consolidation may happen to them when subjected to the vacuum gradient. Similar to the consolidation, the filtration may provide equally useful information on interpreting the constitutive behavior of the slurry. In this paper, a new approach utilizing the filtration process is devised to evaluate the constitutive behaviors of dredged slurries. The approach is composed of a vacuum filtration device and an iterative curve fitting algorithm. Two types of tests, namely step-vacuum filtration and constant-vacuum filtration followed by compression test, must be conducted on the slurry specimens, and only the time variations of the filtrate discharge should be recorded. On the basis of the recorded data, the curve fitting algorithm is adopted for determining the parameters of the constitutive equations. The effectiveness of the proposed approach is verified through comparing the obtained compressibility and permeability of the slurries with the data provided by the oedometer test and with the empirical relationships from different sources. The comparisons demonstrate that the constitutive relationships determined by the present approach can predict the compressibility and permeability characteristics of dredged slurries with an acceptable degree of accuracy.

Balancing Political and Criminogenic Needs: Evaluating the New Zealand Department of Corrections’ Response to Men Assessed With a Below Average Risk for Sexual Recidivism

Current research provides little evidence for the effectiveness of treatment in reducing sexual offence recidivism amongst low-risk populations. However, in real-world correctional settings, program delivery rarely occurs in a vacuum, treatment may be politically mandated and unidimensional measures of program success may preclude recognition of broader benefits. The current study investigated the effectiveness of a low-intensity treatment program, both in terms of participants’ recidivism outcomes and in terms of broader organizational/systems impacts. The results demonstrated low base rate recidivism across both program participants ( n = 311) and a comparison group of men who were assessed as demonstrating similar static sexual offence recidivism risk ( n = 391), and little evidence of reduced recidivism following treatment. However, program administration led to many potential participants being identified as demonstrating higher levels of dynamic risk and overridden to more intensive treatment options ( n = 101). Given evidence that such options do effectively reduce recidivism in higher risk populations, these findings may suggest an overall positive net effect.

Optimization of γ-Aminobutyric Acid (GABA) Accumulation in Germinating Adzuki Beans (Vigna angularis) by Vacuum Treatment and Monosodium Glutamate, and the Molecular Mechanisms

This study aimed to investigate the optimal hypoxic and monosodium glutamate (MSG) stress conditions for the enrichment of γ-Aminobutyric acid (GABA) in germinating adzuki beans and to reveal the potential underlying molecular mechanisms of GABA accumulation. Using single-factor experiments and response surface model, we investigated the effects of germination time, germination temperature, vacuum time, and MSG concentration on GABA contents, and further explored the activity and gene expression of glutamate decarboxylase (GAD) and polyamine oxidase (PAO) critical rate restriction enzymes during GABA synthesis. The optimal soaking temperature, soaking time, and pH conditions were 35°C, 16 h, and 5, respectively. Furthermore, the optimal germination conditions for optimal GABA enrichment were 48 h, 1.99 mg/ml MSG concentration, germination temperature of 31.49°C, and vacuum time of 15.83 h. Under such conditions, the predicted GABA concentration was 443.57 ± 7.18 mg/100 g, with no significant difference between the predicted and experimental data. The vacuum + MSG (FZM) treatment has a maximum contribution rate of GABA to 38.29%, which significantly increase GABA content, and the increase was associated with increased GAD and PAO activity. In addition, MSG in combination with vacuum treatment could significantly induce VaGAD4 and VaGAD6 genes in 2 days germination of adzuki beans. According to the results of the present study, vacuum + MSG treatment is an effective approach to enhancing GABA accumulation in germinating adzuki beans, which could be employed in enhancing the functional quality of germinating adzuki beans.

Hydrogen removal in circulating vacuum degasser under conditions of PJSC “NLMK”

For high­quality steel smelting, stage­by­stage production is required, which has a complex of metallurgical units capable for producing products with high performance properties and low content of harmful impurities. One of the harmful impurities is hydrogen, so it is important to limit its content in the metal. To ensure the specifed hydrogen content, the metal in the steel out­of­furnace treatment at Converter Shop No. 2 (CS­2) of PJSC “Novolipetsk Metallurgical Plant” (“NLMK”) is subjected to vacuum treatment in a circulating vacuum degasser. Despite the prevalence of circulating vacuum derassers, theoretically, mechanism of hydrogen removal in these metallurgical units has been insufciently studied. To increase efciency of hydrogen removal, theoretical calculations were performed to remove it from the metal. There are several mechanisms for hydrogen removing: direct transfer of hydrogen from metal to the surrounding space; formation of gas bubbles in metal and their direct ascent; nucleation of hydrogen bubbles at the border of refractory wall and metal; removal of hydrogen by metal blowing with neutral gas (argon). It is shown that the main ways of hydrogen removal in a circulating vacuum degasser are direct transfer of hydrogen from metal to the surrounding space and blowing of melt with transporting gas. In the CS­2 of PJSC “NLMK”, both ways are implemented at a circulating vacuum degasser. Vacuum pumps provide pressure in a vacuum chamber of less than 101.3 Pa (0.001 atm.). It promotes intensive removal of hydrogen from the metal surface. To ensure circulation of metal, transporting gas argon is supplied to the inlet pipe of the RH degasser, which also takes part in removal of dissolved gases by transferring hydrogen to neutral gas bubbles. Additionally, performed calculations have shown that the main way of degassing in conditions of CS­2 of PJSC “NLMK” is removal of hydrogen into the bubbles of carrier gas.