Microstructure and Formability of Laser Welded Dissimilar Butt Joints of Austenitic-Ferritic Stainless Steels

Dissimilar laser welding of ferritic, type EN 1.4509, and austenitic, type EN 1.4307, stainless steel sheets was conducted at different energy inputs 30 and 80 J/mm and under different shield gases Ar and N and without shielding gas to evaluate the microstructure and hardness of the welded zone. The formability tests, using Erichsen principle, were carried out to determine the deformation behaviour of the dissimilar welded joints under biaxial straining. The fusion zone microstructure analysis revealed that the predominant phase structure is columnar coarse ferritic grains with slightly small content of austenite in the ferrite grain boundaries. The formability of the welded joints under Ar and N shielding gases is significantly improved, i.e., higher plasticity, compared with welded joints without shielding gas at both energy inputs.

PROXIMATE, MACRO ELEMENTAL AND GC-MS ANALYSIS OF SORBARIA TOMENTOSA

Sorbaria tomentosa (LindI.) of family Rosaceae, is a wild, medicinal, ornamental, large, woody plant locally known as “Karhee or Berre”, native to Pakistan. Proximate composition gives important information to assess the suitability of medicinal flora or their extracts taken orally by the trivial communities. In the current study, different proximate parameters like carbohydrate, ash, protein, moisture content and fat, along with carbon, hydrogen, nitrogen and sulphur were analyzed in whole plant of S. tomentosa. The results revealed the occurrence of considerable proportion of carbohydrates (52%) and protein (23.80%). Moisture, fat and ash contents were found in small content 6.25, 2.02 and 0.20%, respectively. Elemental analysis displayed the greater content of carbon (44.92%) followed by content of hydrogen (6.16%), nitrogen (5.17%) and sulphur (0.43%). GC-MS analysis of n-hexane fraction of S. tomentosa led to identification of five compounds viz., 3, 13-Dimethylpentadecanoic acid (1), 2, 4-Dimethyltetradecanoic acid (2), 2, 4-Heptadecadienoic acid; Etester (3), 2-Butylcyclopropanedodecanoic acid (4) and Heptadecanoic acid; Et ester (5). Toxicity tests, further isolation and identification of active constituents of test weed could confirm the discovery of novel plant drugs and safety in administration.

Effect of Various Type of Nanoparticles on Mechanical and Tribological Properties of Wear-Resistant PEEK + PTFE-Based Composites

The mechanical and tribological properties of polyetheretherketone (PEEK)- and PEEK + PTFE (polytetrafluoroethylene)-based composites loaded with and four types of nanoparticles (carbonaceous, metallic, bimetal oxide, and ceramic) under metal- and ceramic-polymer tribological contact conditions were investigated. It was found that loading with the nanofillers in a small content (0.3 wt.%) enabled improvement of the elastic modulus of the PEEK-based composites by 10–15%. In the metal–polymer tribological contact, wear resistance of all nanocomposites was increased by 1.5–2.3 times. In the ceramic-polymer tribological contact, loading PEEK with metal nanoparticles caused the intensification of oxidation processes, the microabrasive counterpart wear, and a multiple increase in the wear rate of the composites. The three component “PEEK/10PTFE/0.3 nanofillers” composites provided an increase in wear resistance, up to 22 times, for the metal–polymer tribological contact and up to 12 times for the ceramic-polymer one (with a slight decrease in the mechanical properties) compared to that of neat PEEK. In all cases, this was achieved by the polymer transfer film formation and adherence on the counterparts. The various effects of the four types of nanoparticles on wear resistance were determined by their ability to fix the PTFE-containing transfer film on the counterpart surfaces.

Evaluation of nutritional and elemental compositions of green and red cultivars of roselle: Hibiscus sabdariffa L.

Roselle—Hibiscus sabdariffa L. leaves at different stages of growth, calyces and seeds were analyzed for nutritional and anti-nutritional factors. All the treatments contained a good but varied proportion of carbohydrate in a range of 26.93–54.13%, crude protein from 5.7 to 27.06%, crude fat 1.16–13.09%, crude fibre 15.75–36.10%, energy 631.36–1065 kJ, ash 6.08–13.74% and moisture content 6.00–9.7%. The vitamins A, C and E were also found to be present in all the treatments in a different but substantial amount. The calcium, magnesium and iron contents in all the treatments were higher than the recommended daily allowance of 1250, 350, and 15 mg for adults, while the phosphorus and sodium values in all the treatments were below 1000 and 1500 mg RDA for adults. However, the Na + /K + for all the treatments were lower than 1. The values of anti-nutrients in the samples were small except post-flowering red which had high phytate content of 21.02%, although this can be easily reduced during processes like boiling and cooking. Thus, both cultivars of roselle contain high nutritional, elemental, and vitamins compositions and small content of anti-nutrients.

Passivation of chromium disilicide in acidic media

The anodic behavior of CrSi2 electrode in 0,5 M H2SO4, 0,5 M HClO4, 0,5 M HNO3 and 0,5 M HCl solutions has been studied by the methods of polarization, capacitance, and impedance measurements. It has been concluded that in the process of anodic oxidation at potentials from corrosion E to transpassivation E inclusive, an oxide film is formed on the surface of chromium disilicide in the studied media, which is close in composition to SiO2 (with a small content of chromium oxides). The presence of this film on the silicide surface determines its high chemical resistance in the studied solutions. The thickness of the oxide film on CrSi2 has been calculated depending on the potential and composition of the electrolyte. The growth constant of the oxide film has been determined.

Effect of lactase, transglutaminase and temperature on ice cream crystal by a response surface methodology approach

This study aimed to evaluate the ice cream crystal content considering the addition of enzymes lactase (0.3% to 0.9%) and transglutaminase (0.6% to 7.4%), employing different incubation temperatures (13 to 47 °C) through a 23 central composite rotatable design (DCCR). The crystals content was estimated by ice cream scattering in blades and the crystals images were obtained with a bright field optical microscope for counting and determining the crystals size using Image J software. All ice cream treatments prepared at 40 oC (T2, T6, and T8) and TA2 treatment (T2 treatment similar formulation) showed small content of crystals if compared with the temperatures of 20 and 30 ºC; it was probably associated with a large presence of air bubbles, fat globules and probably some casein micelles, making them ideal for small crystals agglomeration that form a firmer, smooth and cohesive texture. Moreover, the combined use of lactase and transglutaminase enzymes in the ice cream is viable, efficient and an easy technology for ice cream production. Furthermore, the use of response surface methodology was effective in selecting the best formulation in relation to desirability features ensuring its use in the ice cream development.

Flux growth, structure refinement and Mössbauer studies of Fe1– x Ga x BO3 single crystals

High-quality Fe1–x Ga x BO3 single crystals (0.0 ≤ x ≤ 1.0) in the form of basal plates were synthesized by the flux technique. The exact content of Fe and Ga and homogeneity of their distribution in the crystal structure were determined by energy-dispersive X-ray spectroscopy. The crystal structure was refined using single-crystal X-ray diffraction data. The electronic and magnetic properties were studied using Mössbauer spectroscopy. It is shown that even a small content of diamagnetic gallium leads to a rearrangement of the crystal structure and essentially changes the magnetic hyperfine parameters of the crystals.