Chromate conversion coatings and their current application

This paper describes formation, composition and possible production technologies of application chromate coatings. Summation of common examples of applications of these coatings in corrosion protection of metals and alloys is provided. Individual chromate coatings are divided by their dominant anions either with CrVI or CrIII. Restrictions of chromate coatings with dominantly CrVI and related toxicity of hexavalent chromium is discussed in detail. In conclusion, examples of both chromium and other, alternative coatings are summed up. Application of these coatings as a protection for concrete hot-dip galvanized reinforcement is also reviewed

Design of Peptides With, α,β-Dehydro-Residues: A Dipeptide With a Branched β-Carbon Dehydro-Residue at the (\u3ci\u3ei\u3c/i\u3e+1) Position, Methyl \u3ci\u3eN\u3c/i\u3e-(benzyloxycarbonyl)-α,β-Didehydrovalyl-L-Tryptophanate

The structure of the title peptide, C25H27N3O5, has been determined and its conformation analysed. Values of the standard peptide torsion angles are φ(1) = -44.2 (3)°, ψ(1) = 135.9 (2)°, φ(2) = -141.6 (2)° and ψ(T/2) = 168.0 (2)°. The crystal structure is stabilized by an intermolecular hydrogen bond, with an N···O distance of 2.919 (3)Å, which is formed between screw-axis-related NH and CO groups of dehydrovaline residues

Pulsation of M-type Mira variables with moderately different mass: search for observable mass effects

Models of M-type Miras with masses of 1 $M_\odot$ and 1.2 $M_\odot$, i.e. with envelope masses of about 0.4 $M_\odot$ and 0.6 $M_\odot$, have been constructed, and a comparison has been made of their observable properties. Geometric pulsation of continuum-forming layers is found to be little affected by the mass difference. The influence of molecular contamination of near-infrared continuum bandpasses upon interferometrically measured fit diameters ranges from undetectable to quite significant. Some pulsation cycles of the lower-mass model Mira show substantially stronger contamination than that found in any cycle of the higher-mass star. Observations which sample pulsation phase well and continuously are crucial for avoiding misinterpretations, because the assignment of absolute pulsation phases is inherently uncertain by at least 0.1 cycles, diameter changes may be strongly phase-dependent, and cycle-to-cycle variations may be substantial. In accord with expectations, we find that cycle-to-cycle variations that show up in light curves and in near-continuum diameters tend to be larger and more common in the low-mass models, leading to one possible way to discriminate mass. Two other methods, based on high-precision measurements of the pulsation amplitude and on derivation of pre-maximum effective temperatures from diameter measurements, are also discussed. High-layer features that may be strongly affected by mass are not well described by present dust-free models.Comment: Accepted for MNRAS, 8 Pages, 8 Figure

Numerical Analysis of Historical Reinforced Concrete Shell

This article is focused on the numerical analysis of the historical structure of the reinforced concrete shell. Shells form the roof of the tram depot. It was built in the 50s of the 20th century. The shells are conoid shaped with a control curve in the form of a catenary. The construction of the depot began to show excessive deformation and lose its stability. At present, the depot is out of service and the shells are temporarily supported. This prompted the commissioning of a diagnostic survey and numerical analysis of the structure. The diagnostic research revealed the quality and strength of the concrete, the reinforcement of the structure, the actual thickness of the shells, the structure of the roof cladding and defects in the structure (cracks, etc.) At the same time, the bottom surface of the whole structure was scanned with a 3D scanner and selected points of the structure were measured by geodetic methods. Numerical analysis focused on one shell at the edge of the depot structure. The model was created in Atena 3D software. The main aim of the analysis was to determine the behavior of the structure under load and to predict the ways of its deformation for different loading methods to determine the possible reason for the current deformed shape. Consequently, compare these predicted behaviors with the real deformed structure, whether its deformation corresponds to normal behavior

Outcome of pedicle screw fixation with transpedicular bone grafting in fracture of thoracolumbar vertebrae

Background: Posterior short segment instrumentation for thoracolumbar fracture is known for high implant failure rate because of the lack of anterior support. Anterior body augmentation by transpedicular bone grafting has been developed as an alternative to overcome this failure. In this study, we have evaluated the outcome of the cases of the unstable thoracolumbar spine injuries managed surgically with pedicle screws and transpedicular bone grafting.Methods: 20 patients were included in this study and were followed up for up to 6 months postoperatively. We assessed the outcome of each patient with Frankel scale and visual analog score (VAS) post-operatively clinically and radio logically by measuring Cobb’s angle and anterior vertebral body height post-operatively on follow-up at 6 weeks, 12 weeks, and 24 weeks.Results: We found that males had higher incidence with most common mode of injury was fall from height. D12 was single most involved vertebrae. The average Cobb’s angle during preoperative stage was 12 degrees and 22.05 degrees at 6th week and this was maintained till 24th week. The mean difference of anterior vertebral body height between pre-operative and 24th post-operative week was 7.15 mm. The mean VAS pre-operatively was 9.8 which changed to 0.75 at 24 weeks follow up. These were statistically highly significant.Conclusions: Our study established that Pedicle screw fixation with transpedicular bone grafting has a satisfactory result and can restore vertebral height, increase the stability of the injured vertebrae and leads to a significant improvement in the patient’s quality of life

Comparison of functional outcomes between cemented and uncemented bipolar hemiarthroplasty for intracapsular neck femur fractures

Background: The neck of femoral fracture is common and leading fracture in orthopaedic practice. The older age group and female are more to prone to develop this fracture.Methods: A prospective, clinical observational, analytical comparative study was undertaken in the department of Orthopaedics of Geetanjali Medical College and Hospital in Udaipur, Rajasthan from January 2018 to June 2019. 52 adult patients with neck of femur fracture, 26 patients in each group. Results: In our study, the mean age was 77.72 years. Female preponderance was seen in our study. In our study mean duration of surgery in uncemented group was 65.78 minutes and mean duration of surgery in cemented group was 79.89 minutes. The mean total HHS in our patient was 86.63 with standard deviation of 6.18. Mean HHS for cemented group was 86 and for uncemented group was 87.23. We found 20 excellent result and 27 good results (35.71% and 51.92% respectively). We also found 5 fair result (12.37%). There were 2 complications, both in cemented group, one had post-operative dislocation and other had a cement reaction.Conclusions: Both cemented and uncemented hemiarthroplasty are equally good options in the treatment of femoral neck fractures in the elderly. However, it is to be noted that the duration of surgery & complications, were both less in the uncemented group as compared to cemented hemiarthroplasty group in our study.

Discussion about magnesium phosphating

The paper describes results from recently published research focused on production of non-conventional magnesium phosphate Mg3(PO4)2・4H2O – bobierrite, or MgHPO4・3H2O – newberyite) coating for both magnesium alloys and/or mild steel. This new kind of coating is categorized in the context of current state of phosphating technology and its potential advantages and crystal structure is discussed. At the same time, the suitable comparison techniques for magnesium phosphate coating and conventional zinc phosphate coating are discussed