Ultra-high Performance Liquid Chromatography in Steroid Analysis

The latest version of liquid chromatography is ultra-high performance (or pressure) chromatography (UHPLC). In the technique, short and narrow-bore columns with particle sizes below 3 µm are used. The extremely high pressure used results in very short analysis times, excellent separation, and good resolution. This makes UHPLC a good choice for steroidal analysis. Steroids are a highly interesting area of study; they can be recognized as biomarkers for several diseases and are a relevant topic in doping testing. In this thesis articles on the topic ‘steroid analysis with UHPLC’, published prior to April 2017, are reviewed. UHPLC is always combined with mass spectrometry (MS) for steroid analysis. The MS utilized is usually of multi-dimension: quadrupole time of flight (QTOF) or triple quadrupole (QqQ). The instrumentation is suitable for both untargeted and targeted analysis. In untargeted studies, the study of changes in the human metabolome has been especially interesting. The articles on targeted studies are usually focused on doping control and quantification of identified biomarkers. The analysis with UHPLC-MS/MS usually provide reliable results with fast analysis time, without complicated sample preparation. Typically, the sample preparation processes can include only protein precipitation, liquid-liquid extraction or solid-phase extraction. UHPLC is also a valuable tool in simple and routine analysis. The separation efficiency is increased by the small plate height and the analysis time can thus be reduced. In this thesis work the technique was utilized for the analysis of food additives. For validation of an UHPLC method the repeatability, trueness, bias, measurement uncertainty and other factors need to be assessed. The experimental part of the thesis is dedicated to describe the development and validation of a method for analysis of five food additives and caffeine. The developed method was partly validated, with the aim to fulfil the needs of the Finnish Customs Laboratory. The optimized method comprised of an injection volume of 2 µL and a flow rate of 1.0 mL/min. The buffer was a phosphate buffer at pH of 4.0 and the gradient elution program was from 6 % to 30 % of acetonitrile in 1.6 minutes, then 1.6-1.7 minutes with 6% acetonitrile. The total run time was only 1.7 minutes. The limit of detection values was between 0.02 µg/mL and 1.73 µg/mL. The limit of quantitation values was between 0.054 µg/mL to 5.78 µg/mL, which should be sufficient for the Customs needs in the sense of checking if a product is over a certain limit. Expanded measurement uncertainties were around 20 %

Pitting Stochastic Study in Airframe Aluminium Alloy using Non-linear Ultrasonic

Pitting corrosion is considered to be one of the principal degradation mechanisms for high-strength aluminum alloys. The aircraft airframe has been the most demanding application for aluminum alloys. The combined effects of corrosion and cyclic loading have been shown to produce cracks from corrosion pits and pits have frequently been the source of cracks on aircraft components operating in fleets. Once the pit or group of pits form, the rate of pit growth is dependent mainly on the material, environmental conditions and type and state of stress. Therefore, to estimate the total corrosion fatigue life of a component, it is of great importance to develop realistic models to establish the component life in these situations and to formulate methods by which designers and operators know likely sources of pitting early in the design and fleet operation. There are certain gaps in knowledge with regards to life prediction for pitting initiated fatigue. The need is to gauge the extent of pitting damage of a component or material non-destructively and predict the remaining life through superimposition of the pertinent operational, environmental and material parameters. However, a foolproof non-destructive means to characterize and three-dimensionally map pits is not available. The pitting phenomenon has to be analyzed statistically and the kinetics of pitting assessed through a change in the statistical distribution parameter of pits rather than deterministic equations relating pit dimensions to time. In this work we have applied high frequency ultrasonic and non-linear ultrasonic to assess the damage due to pitting and attempt has been made to establish correlations between this non-destructive tools and pit stochastic

COMPARATIVE STUDY OF YELLOW-BILLED BABBLER (TURDOIDES AFFINIS) FEATHERS REVEALS UNIFORMITY IN THEIR MICROSTRUCTURES AMONG INDIVIDUALS

Though a few in numbers, investigations on feather microstructures from the early 20th century till date, have contributed immensely to various fields such as phylogeny, palaeontology, archaeology, wildlife forensic, biomechanics and so on. However, existing studies on feather micro-structures of birds endemic to the India/Indian sub-continent are few in number and limited in their scope. Also, no study has ever been conducted to compare feather microstructures of different individuals of a species from India. To address this issue, a comparative feather microstructure study of three individuals of Turdoides affinis, a passerine endemic to the Indian sub-continent was done. Select microstructure parameters for five different types of feathers were studied in detail. The molecular sexing method was used to elucidate the sex of T. affinis individuals for gender based differences if any. Results of the study identified that two of T. affinis individuals were female whereas one of them was male. Morphometrically, tail contour was the longest (9.63±0.76 cm) and bristle were the shortest (1.00±0.07 cm) feather. Semiplume had the longest barb length (1.73±0.04 cm) and shortest barbs (0.16±0.01 cm) were present in bristles. Subpennaceous barbs and knob-shaped villi, characteristic of members of the Passeriformes family, was also observed in all three individuals. This study records no significant difference in feather characteristics amongst the three T. affinis individuals irrespective of the differences in their sex and size. Systematically documented feather micro-characteristics of T. affinis in this study could be used as a species identification tool and would provide baseline data for the feather catalogue of Indian bird species being compiled at SACON

Interaction of strain rate and hydrogen input on the embrittlement of 7075 T6 Aluminum alloy

The effect of hydrogen on the mechanical properties of AA 7075- T6 was studied by in-situ hydrogen charging with slow strain rate technique in two aqueous media. A comparative study has been made on the stress-strain curve, time to failure at different strain rates (10−4–10−6 s−1) in the air and by in- situ hydrogen charging. A variable effect of strain rate on embrittlement was observed. The alloy developed a surface film of oxide or hydroxide in the environments tested in spite of cathodic charging. This oxide film interferes with hydrogen embrittlement in the alloy. The kinetics of film formation and consistency of the film were dependent on the environment. At intermediate strain rates the film interfered and reduced hydrogen entry, while at the slowest strain rates hydrogen embrittlement was significant

Effect of temper on the distribution of pits in AA7075 alloys

A comparative study of pitting severity in T6 and T73 tempers of AA7075 in 0.1 M NaCl is reported here. Pitting was more severe for T6 tempers compared to T73 tempers. This could be attributed to higher pit nucleation sites in the former. The statistical distributions for pit areas indicated nucleation saturation in T73. The extreme value distributions showed differences for the two tempers. These differences in pit distribution are explained on the basis of the role of constituent as well as strengthening particles as well as the role of grain boundary η precipitates

The Effect of pitting on fatigue lives of peak-aged and overaged 7075 aluminum alloys

Fatigue lives at high peak stresses for peak-aged (T6) and overaged (T73) 7075 aluminum alloy were compared in the uncorroded and precorroded (pitted) states. Absolute fatigue lives of T73 samples were much higher than that of T6 in the virgin as well as precorroded condition, but the normalized life of T73 was less than that of T6, indicating an intrinsic crack initiation resistance in the former, borne out by fractography, which showed that fatigue cracks almost always initiated at pits for T73 but not for T6. The various crack initiation methodologies observed and the effect of pitting on fatigue lives in the two aging conditions are discussed

Hydrogen entry into pipeline steel under freely corroding conditions in two corroding media

Hydrogen permeation through API 5L X65 pipeline steel was studied under freely corroding conditions in NACE solution (simulated seawater) and poisoned 1 N H2SO4. A steady state condition with regards to permeation flux is not obtained due to the presence of corrosion product, changing sample dimension and a possible change in hydrogen availability on the corroding surface. A unique way of calculating the sub-surface hydrogen concentration (C0) under non-steady state freely corroding conditions has been developed. The C0 has been evaluated as a function of exposure time in NACE solution and poisoned H2SO4 solution. The sub-surface hydrogen concentration (C0) increased initially but then decreased with increasing exposure to the corroding solutions, after demonstrating an early maximum. The changes in C0 have been explained taking into consideration the corrosion products that developed, the possible anodic reactions, the changes in sample thickness and other issues in the dynamic system

Dataset from genome sequencing, assembly and mining of microsatellite markers in barred-button quail (Turnix suscitator)

Turnix suscitator (barred-button quail) is a member of the primitive genus Turnix in the highly diverse order of shore birds Charadriiformes. Absence of genome scale data of T. suscitator has limited our understanding about its systematics, taxonomic and evolutionary history as well has hindered the characterization of genome wide microsatellite markers of the same. Hence we generated whole genome short read sequences of T. suscitator, created a high quality assembly and mined genome-wide microsatellite markers from the same. A total of 34142524 reads were sequenced with an estimated genome size of 817 mb. SPAdes assembly consisted of 320761 total contigs and an estimated N50 value of 907 base pairs. Krait identified a total of 77028 microsatellite motifs covering 0.64% of the total sequences in the SPAdes assembly. Further the whole genome sequence and genome wide microsatellites dataset of T. suscitator will facilitate future genomic/evolutionary studies of Turnix species