Automatic COVID-19 detection mechanisms and approaches from medical images: a systematic review

Multimedia Tools and Applications - Since early 2020, Coronavirus Disease 2019 (COVID-19) has spread widely around the world. COVID-19 infects the lungs, leading to breathing difficulties. Early...     

Experimental study of journal bearings with undulating journal surface

A journal bearing test rig was designed and constructed to test the behaviour of journals with wavy surfaces, the circumferential undulations being varied both in amplitude and in number. Results show that wavy journal surfaces may well enhance the load carrying capacity of a bearing. Moreover, surface undulations are shown to move the journal centre locus closer to the load line, ie cause a lower attitude angle. These effects are found to be more pronounced with larger wave amplitudes, and with higher numbers of waves around the journal circumference. In general, friction is found to be reduced with increase in surface wave amplitude.Good agreement is shown to exist between test results and a computer aided analysis conducted by the authors to predict wavy journals performance¹. It has been established that a wavy journal surface may, under certain conditions, display higher load capacity, lower friction and permit safer running of journal than bearings with perfectly smooth surfaces.     

Preparation, structure and infrared spectrum of NaEuP2O7

Crystals of NaEuP₂O₇ have been grown by the flux technique and characterized by X-ray diffraction. Single crystal structure of NaEuP₂O₇ has been solved, for the first time; it crystallizes in the monoclinic P2₁/n space group with lattice parameters : a = 5.238(2), b = 8.443(4), c = 12.486(6) Å, β = 91.404°(2), V = 552.0(4) ų, Z = 4. The crystal structure has been refined yielding a final R(F²) =0.049 and R_w(F²) = 0.138 for 1313 independent reflections (F_o² ≥ 2σ(F_o²)). In this structure, the PO₄ tetrahedral are linked by bridging oxygen to give P₂O₇ groups, these groups are connected to the EuO₈ polyhedron by sharing two oxygen corners to form three-dimensional framework in which channels are noticed and where the sodium ions are located. The frequencies of the vibrational modes of the crystal were obtained from measurements of the infrared spectra.     

Volatile compounds from Chétoui olive oil and variations induced by growing area

Fruits from the same variety of Olea europaea L., grown under different environmental conditions in the north of Tunisia, were harvested at the same ripening degree and immediately processed. The volatile profile of virgin olive oils was established using solid phase, micro-extraction (SPME) and gas chromatography-mass spectrometry (GC-MS). Compounds belonging mainly to the following chemical classes characterised the volatile profiles: esters, aldehydes, ketons, aliphatic alcohols and hydrocarbons. Significant differences in the proportions of volatile constituents from oils of different geographical origins were detected and the major volatile in approximately 50% of the oil samples was the aldehyde (E)-2-hexenal. The results suggest that, beside the genetic factor, environmental conditions influence the volatile formation.     

The need for restructuring the education systems for techniciansand technologists in developing countries

Whilst educational authorities in developing countries are focusing their attention on the proliferation of universities, little attention is being paid towards improving the standards of vocational and technical education and increasing the number of vocational and technical institutes. There seems to be a lack of appreciation that skilled technicians and technologists are the backbone of any industrialised state and that it is their skill and competence that determine the standard of engineering practice attainable and set the level of technological and economic advancement that can be achieved. In this paper a comparative study of the technical education systems in both developed and developing countries is presented and it is proposed how in the latter they should be upgraded to improve the education of technicians and technician-engineers and make it an attractive alternative to a university education     

The Chemical Properties and Volatile Compounds of Virgin Olive Oil from Oueslati Variety: Influence of Maturity Stages in Olives

The aim of the present work was to investigate the influence of fruit ripening on oil quality and volatile compounds in an attempt to establish an optimum harvesting time for Oueslati olives, the minor olive variety cultivated in Tunisia. Our results showed that many analytical parameters, i.e., peroxide value, UV absorbance at 232–270 nm, chlorophyll pigments, carotenoids and oleic acid contents decreased during ripening, whilst linolenic acid increased. Free acidity remained practically stable with a very slight rise at the highest maturity index. The volatile compounds emitted by the Oueslati olive oil were characterized and quantified by HS‐SPME‐GC‐EIMS. Twenty‐three volatile compounds were identified, mainly aldehydes, sesquiterpenes and esters. The results show variations in the volatile fractions and quality parameters of Oueslati extra virgin olive oil obtained at different olive‐ripening stages. Fifteen sesquiterpenes were identified for the first time in this cultivar, mainly hydrocarbon derivatives, but also oxygenated ones. On the basis of the quality parameters and volatile fractions studied, the best stage of Oueslati olive fruits for oil processing seems to be at ripeness index about 3.0. Indeed, these results suggested the possibility of using sesquiterpenes for olive authenticity and traceability and demonstrated that the volatile fractions can be used as indicators of the degree of ripening of the olives used to obtain the corresponding virgin olive oils.     

Laboratory investigation on the condensation and corrosion rates of top of line corrosion in carbon steel: a case study from pipeline transporting wet gas in elevated temperature

A glass cell was designed to simulate the condition for top of line corrosion encountered in wet gas transportation pipelines. Aqueous solution of 3 wt-% NaCl saturated with CO₂ at atmospheric pressure was employed. Effect of temperature gradient in the formation of condensation and its rate was investigated. API 5L Grade X65 carbon steel material was used as the working electrode for the experiment. The condensation rate was measured for the temperature gradient of 20°C, 30°C and 50°C under atmospheric condition for 24?h duration of the experiment. The corrosion rate of the specimens was measured using weight loss and Linear Polarisation Resistance (LPR) techniques. The LPR probe was immersed in the collected condensed water from the experiment to calculate the corrosion rate. The measured corrosion rate from the weight loss technique was in agreement with the corrosion rate measured from LPR. The corrosion rate measurement was repeated with the addition of 1000?ppm of pH modifying agent. This study indicates that the corrosion rate of pipeline and piping when subject to temperature gradient of 50°C and above is very high and alarming.     

Design of a secondary standard for measuring arterial blood pressure

The measurement of blood pressure by mercury sphygmomanometer and auscultation is one of the oldest methods, and it is still widely used in health services. Nowadays, the usage of inexpensive electronic oscillometric devices for home and clinical use has increased dramatically. The purpose of this paper is to verify the reliability of such devices.