Surface Of Barrel Research Articles

Influence of corrosion-active non-metallic inclusions on the accelerated destruction of the internal surface of the Oplot-M tank barrel

The metallographic features of operational damage to the inner surface of the barrel of the Oplot-M tank were analyzed. It was established that with the movement from the chamber to the cut of the barrel, the number and size of damage decreases, which is related to the distribution of pressures of working gases, temperature and aggressiveness of the environment. It is shown that the damage is placed on the inner surface chaotically and the nature of their destruction is corrosive and corrosive-mechanical in origin. Local analysis of their chemical composition revealed a high oxygen content, which indicates the formation of oxide-hydroxide compounds. The surface layers of the barrel were studied and it was established that a "white" layer with a thickness of ~50 μm and a microhardness of 930 kg/mm2 is formed on the surface, the structure of the inner layer of the steel of the barrel is troostite (HW 225 kg/mm2). 
 The effect of corrosion-active non-metallic inclusions (KANV) on the destruction of the surface of a barrel made of steel 38KHN3MFA was studied. It is shown that more sensitive to changes in the technical state of steel due to degradation are studies of corrosion resistance, microelectrochemical heterogeneity and impact toughness of steel. It was established that the presence of KANV in the steel structure leads to an increase in corrosion currents by 4 times and microelectrochemical heterogeneity, in particular, non-periodic potential peaks of 50-70 and 200-230 mV. Due to the influence of tap water on the surface of the steel, corrosion ulcers of a rounded shape and a size of 50-80 μm were recorded, which contribute to the local corrosion of the steel. The analysis of steel fractures revealed that inclusions of a round shape with a size of 3-5 μm contain impurities of harmful elements Al, Mg, F, which accelerate local corrosion on the surface of the steel of the tank barrel. It is shown that the study of fractures, and not of samples, provides an opportunity to estimate not only the size and density of inclusions, but also their chemical composition.

Characterization of plasticizing process of single screw extruder with grooved melting zone

In order to improve the throughput and plasticizing capability of traditional single screw extruder (SSE), grooves at the inner surface of barrel were extended from the feeding zone to the melting zone of the extruder. However, the melting behavior and plasticizing quality of polymers in the grooved SSE can not be observed and measured intuitively because of the closed structure of the extruder. In this study, four types of detection techniques, including visualization technology, ultrasound testing, melt pressure on-line detecting and mechanical properties analysis, were developed to characterize the plasticizing capability of SSE with grooved melting zone. Four screws with different compression ratios were also utilized to investigate the plasticizing performance of SSE with grooved melting zone. The procedure conditions, such as barrel temperature and screw speed, were also analyzed. The experimental results showed that cooperating with an anti-compression ratio screw, SSE with grooved melting zone had a reasonable melt pressure, improved throughput and great plasticizing performance, which was very promising in the polymer processing industry.

Genetic Background in Patients with Severe Factor XIII A-Subunit Deficiency Treated with Recombinant FXIII

AbstractAbstract 1125 Background and Objectives:Congenital Factor XIII (FXIII) deficiency is a rare, autosomal recessive bleeding disorder, with a significant majority of patients showing defects in the FXIII-A subunit. The disease is caused by a variety of F13A1 gene mutations resulting in a severe quantitative FXIII-A type I deficiency. Here, we report a wide spectrum of mutations identified in 41 severe Factor XIII-A deficiency patients (≥6 years of age, mean, 26.4; range, 7–60). Patients and Methods:A total of 41 patients were recruited in a multinational (23 centers, 11 countries), open-label, single-arm, phase 3, prophylaxis trial for the evaluation of the efficacy and safety of a novel recombinant FXIII (rFXIII). Eleven of the 41 patients (Israel [n=8], Switzerland [n=2] and Italy [n=1]) already had established genetic backgrounds and carried previously reported F13A1 mutations. Mutational screening in the remaining 30 patients who had unknown genetic status was done using direct sequencing on an ABI Prism 3130TL (Applied Biosystems, Weiterstadt, Germany). For two patients with splice-site mutations, cDNA analysis was done with RT-PCR (Quiagen One-step RT-PCR kit). The crystallographic model of the recombinant human cellular coagulation FXIIIA zymogen (EC: 2.3.2.13, resolution solved to 2.1Å) was downloaded from the Protein Data Bank (data file 1F13) for viewing, analysis and graphical rendering using YASARAver11.11.2. Classic molecular dynamic simulation approaches were used on the FXIII-A crystal structure to evaluate the effect of the novel missense mutations on protein structure. Results and Discussion:In total, 31 distinct mutations in 41 patients have been identified revealing 13 missense mutations, seven small deletions, six splice-site mutations, three nonsense mutations, one large deletion and one small insertion. Amongst this cohort of mutations, 16 mutations were novel. In one patient, a heterozygous missense mutation was detected in spite of severe deficiency symptoms shown by the patient. We assume that the other mutation could not be detected within the scope of our screening set up. The IVS5–1G>A (c.691–1G>A) splice-site mutation was the most commonly occurring (n=9 [21.9%]) mutation in this cohort. Two siblings carried a missense mutation in F13A1 gene (Ser295Arg) and in combination with a novel variant in F13B gene (Ser634Phe). This variant does not seem to significantly affect the B-subunit stability, since it is located in the terminal part of the molecule. Missense mutations are of special interest since they help to better understand the structure and function of FXIII A-subunit. The MD simulation of four novel missense mutations predicted a damaging effect on the protein structure for three of the missense mutations (Glu229Arg, Leu275Phe, and Arg703Trp) based on changes in bonding patterns, free energy calculations, change in local secondary structure etc. The Leu588Gln located on the surface of barrel 1 domain was not observed to cause a significant change in local structure, nevertheless, owing to its surface presentation it might influence the interaction with FXIII B-subunit. The analysis for the two novel splice-site mutations (IVS7+1G>A, IVS12+1G>A) did not show any aberrant mRNA product. Inhibitor development is the most undesirable side-effect of treatment with plasma-derived or rFXIII products. Overall, the incidence of inhibitors in patients with congenital FXIII deficiency is unknown, but is expected to be much lower compared with other coagulopathies, e.g. hemophilia A. In the present study, none of the patients treated with rFXIII (a mean treatment period of 322 days) developed FXIII neutralizing antibodies. Four patients developed transient low-titer anti-rFXIII antibodies that had no neutralizing activity. Interestingly, two patients (male and female) were siblings carrying the same common splice-site mutation in intron 5 (IVS5-1 G>A). The third patient was compound heterozygous for two missense mutations (Gln229Arg; Ser413Leu). The fourth patient was also found to be compound heterozygous for two missense mutations (Arg77His; Leu275Phe). Conclusion:To conclude, the identified mutations, including 16 novel mutations, are implicated in the causality of severe FXIII deficiency. However, none of these mutations were associated with the development of inhibitory antibodies in the context of treatment with rFXIII. Disclosures:Tehranchi:Novo Nordisk: Employment, Equity Ownership. Oldenburg:Biogen Idec, Swedish Orphan Biovitrum: Honoraria; Baxter, Bayer, Biotest, CSL Behring, Grifols, Inspiration, Novo Nordisk, Octapharma, Pfizer: Honoraria, Research Funding.