Microorganisms’ discrimination using an electronic nose-chemometric approach

Mestrado de dupla diplomação com a Université Libre de TunisThe detection/identification of microorganisms is of major relevance for food quality and safety. Traditional analytical procedures (e.g., culture methods, immunological techniques, and polymerase chain reaction), while accurate and widely used, are time-consuming, costly, and generate a large amount of waste. Sensor-based instruments have evolved as quicker and sensitive complementary identification tools for yeasts, bacteria and fungi. Electronic noses (E-noses), in combination with chemometrics, have been effectively employed for the detection/discrimination of different microorganisms, providing a green, quick, cost-effective, and non-destructive/non-invasive assessment. The successful use of the E-noses may be related to the generation of distinctive olfactory fingerprints of certain volatile organic compounds (VOCs) during the microorganism's growth. These devices have already been used to detect/discriminate fungi and bacteria (e.g.,Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, Listeria monocytogenes, Pseudomonas aeruginosa), namely in milk, juice, soups,goat and pork meat,fruits and vegetables. Thus, a lab-made E-nose, with nine metal oxide semiconductor sensors, was applied to detect, differentiate, andquantify four common food contamination/quality indicator bacteria, including two Gram positive (E. faecalisand S. aureus) and two Gram negative (E. coli and P. aeruginosa). Besides, to support the E-nose performance the volatile profiles generated by these bacteria were also assessed by headspace solid-phase micro extraction gas-chromatography-mass spectrometry. The volatile profiles comprised 15 identified VOCs, being 10 of them emitted by at least one of the four bacteria evaluated, namely two alcohols (1-butanol, and 1-nonanol), three pyrazines (2-ethyl-6-methyl-pyrazine, 3-ethyl-2,5-dimethylpyrazine,and trimethylpyrazine), three terpenes (camphene, D-limonene, and ƒÒ-pinene), and two other compounds (2,4-thujadiene and indole). The four bacteria could be distinguished using the electrical resistance signals produced by the E-nose in combination with linear discriminate analysis (90% of correct classifications for leave-one-out cross-validation). Additionally, multiple linear regression models, with root mean square errors lower than 4 colony forming units, were successfully established (0.9428 . R2.0.9946). Overall, the E-nose proved to be an effective qualitative-quantitative tool for analyzing bacteria in solid matrices, being foreseen it possible application to solid food matrices.A deteccao/identificacao de microorganismos e de grande relevancia para a qualidade e seguranca dos alimentos. Os procedimentos analiticos tradicionais (por exemplo, metodos de cultura, tecnicas imunologicas e reacao em cadeia de polimerase), embora precisos e amplamente utilizados, sao demorados, dispendiosos e geram uma grande quantidade de residuos. Os instrumentos baseados em sensores evoluiram como ferramentas de identificacao complementares mais rapidas e sensiveis para leveduras, bacterias e fungos. Os narizes eletronicos, em combinacao com a quimetria, foram efetivamente empregados para a deteccao/discriminacao de diferentes microorganismos, proporcionando uma avaliacao verde, rapida, economica e nao destrutiva/nao invasiva. O uso bem-sucedido dos E-noses pode estar relacionado a geracao de impressoes olfativas distintivas de certos compostos organicos volateis (VOCs) durante o crescimento do microorganismo. Estes dispositivos ja foram usados para detectar/discriminar fungos e bacterias (por exemplo, Enterococcus faecalis, Escherichia coli, Klebsiella pneumonia, Listeria monocytogenes, Pseudomonas aeruginosa), nomeadamente no leite, suco, sopas, carne de cabra e de porco, frutas e legumes. Assim, um E-nose feito em laboratorio, com nove sensores semicondutores de oxido de metal, foi aplicado para detectar, diferenciar e quantificar quatro bacterias comuns de contaminacao alimentar / indicador de qualidade, incluindo duas Gram positivas (E. faecalis e S. aureus) e duas Gram negativas. (E. coli and P. aeruginosa). Alem disso, para apoiar o desempenho do nariz E, os perfis volateis gerados por essas bacterias tambem foram avaliados por micro-espectrometria de extraccao de gas-cromatografia-massa de fase solida.Os perfis Volateis consistiam em 15 VOCs identificados, sendo 10 deles emitidos por pelo menos uma das quatro bacterias avaliadas, ou seja, dois alcoois (1-butanol e 1-nonanol), tres pirazinas (2-etil-6-metil-pirazina, 3-etil-2,5-dimetilpyrazina, e trimethylpyrazine), tres terpenos (hcampene, D-limonene e-pinene), e outros dois compostos. (2,4-thujadiene and indole). As quatro bacterias poderiam ser distinguidas usando os sinais de resistencia eletrica produzidos pelo E-nose em combinacao com a analise discriminante linear (90% das classificacoes corretas para a validacao cruzada de abandono-um-out). Alem disso, foram estabelecidos com sucesso multiplos modelos de regressao linear, com erros medios do quadrado raiz inferiores a 4 unidades de formacao de colonia (0,9428 . R2.0,9946). No geral, o E-nose provou ser uma ferramenta qualitativa-quantitativa eficaz para analisar bacterias em matrizes solidas, prevendo-se a possivel aplicacao a matrizs de alimentos solidos

The Design of FTTH Network

The aim of this thesis is to explain the problems of optical access networks with wavelength division multiplexers, main purpose is to demonstrate the difference between theoretical and real measurement. The work is divided into several thematic areas. The introduction outlines the basic of telecommunications, fiber optics lasers, single mode, multimode, lasers fibers cables & cores, splitters division multiplexing system, there are known solutions discussed fundamental wavelength multiplexes and their possible combinations. The following chapter deals with the active elements such as AON, PON, which are essential part xWDM systems such as optical lasers, detectors and amplifiers. Another chapter focuses on passive elements, which form a key part of the wavelength multiplex. Methods of measurement of WDM/PON networks are discussed in the following part. The next section describes the topology used active and passive optical networks. The penultimate part of the work consists of architecture & technology of xWDM such as GPON and WDM-PON networks and comparing their transmission parameters. The final part of the paper presents the results of practical experimental measurements of optical access networks with wavelengths division multiplex while these results are compared with the theoretical output & methods of Optical lost test, OTDR & LSPM, with advantage & disadvantage of every methods. The second part of practical is the draft to the connection resident housing units of 30 houses, boarding-house (10 rooms) and 2 shops, 20 km distant from exchange. With comparing the possibilities of two options- passive and active optical network- PON system – WDM- Wave multiplex. Suggest the possibility of measuring and monitoring the created network.The aim of this thesis is to explain the problems of optical access networks with wavelength division multiplexers, main purpose is to demonstrate the difference between theoretical and real measurement. The work is divided into several thematic areas. The introduction outlines the basic of telecommunications, fiber optics lasers, single mode, multimode, lasers fibers cables & cores, splitters division multiplexing system, there are known solutions discussed fundamental wavelength multiplexes and their possible combinations. The following chapter deals with the active elements such as AON, PON, which are essential part xWDM systems such as optical lasers, detectors and amplifiers. Another chapter focuses on passive elements, which form a key part of the wavelength multiplex. Methods of measurement of WDM/PON networks are discussed in the following part. The next section describes the topology used active and passive optical networks. The penultimate part of the work consists of architecture & technology of xWDM such as GPON and WDM-PON networks and comparing their transmission parameters. The final part of the paper presents the results of practical experimental measurements of optical access networks with wavelengths division multiplex while these results are compared with the theoretical output & methods of Optical lost test, OTDR & LSPM, with advantage & disadvantage of every methods. The second part of practical is the draft to the connection resident housing units of 30 houses, boarding-house (10 rooms) and 2 shops, 20 km distant from exchange. With comparing the possibilities of two options- passive and active optical network- PON system – WDM- Wave multiplex. Suggest the possibility of measuring and monitoring the created network.

Imaging of Shear Waves Induced by Lorentz Force in Soft Tissues

This study presents the first observation of elastic shear waves generated in soft solids using a dynamic electromagnetic field. The first and second experiments of this 5 study showed that Lorentz force can induce a displacement in a soft phantom and that this displacement was detectable by an ultrasound scanner using speckle-tracking algorithms. For a 100 mT magnetic field and a 10 ms, 100 mA peak-to-peak electrical burst, the displacement reached a magnitude of 1 um. In the third experiment, we showed that Lorentz force can induce shear waves in a phantom. A physical model 10 using electromagnetic and elasticity equations was proposed. Computer simulations were in good agreement with experimental results. The shear waves induced by Lorentz force were used in the last experiment to estimate the elasticity of a swine liver sample

A critical examination of the regulation of the financial services sector in South Africa.

Master of Law in Business Law. University of KwaZulu-Natal, Howard College 2014.The financial system of a country has a crucial role to play in economic growth. The system, efficiently directs savings of lenders to ultimate borrowers. It also provides an efficient payment system through the banking institutions. Every country seeks to have effective laws regulating its financial system to ensure the efficiency and effectiveness of such system. However, the global financial crisis in 2008 revealed that the soft regulation approach adopted by most countries was not effective and that tougher regulation was needed. This led many countries to reform their system of financial regulation and to adopt a macro-prudential regulation approach. The macro-prudential approach deals with the financial stability and soundness of the financial system as a whole and not the individual financial institutions in isolation. South Africa is no exception. Although South Africa, compared with many other developed countries, was protected from the repercussions of the crisis, it introduced a number of financial regulatory reforms. Following the trend in the United Kingdom, South Africa has indicated an intention to adopt a twin-peaks model of financial regulation to make the financial sector of the country safer and to serve the country better. This dissertation seeks to consider the impact of the twin-peaks model of financial regulation on the financial sector in South Africa. It is intended that the model will provide protection for consumers of financial services on issues which are not covered by the Consumer Protection Act, 2008. The model will dispense with the need for a multiplicity of regulators. This will ensure that there is proper control over market conduct, and will prevent unscrupulous persons from jumping from one regulator to another to avoid detection. It is suggested that it would be better for South Africa, to introduce a regulatory system that suits its own problems and environment instead of adopting systems adopted by other countries. However, it is acknowledged that this may take a couple of years to be conceived, prepared and implemented, which could result in consumers and investors being prejudiced by unscrupulous advisors. It is concluded therefore that the twin-peaks model may have some flaws and may be cumbersome for South Africa, but it is an immediate solution, and it can be optimised to accommodate South Africa‟s specific needs as time goes by. It is also suggested that the model should embrace the National Credit Regulator in order to provide an efficient control of the credit industry, and to ensure that an Africa Bank type saga does not re-occur

Characteristics and outcome of patients with pheochromocytoma at a tertiary endocrinology clinic in Durban, South Africa over 14 years

Objectives: To evaluate the characteristics and outcomes of treatment of patients with pheochromocytoma at Inkosi Albert Luthuli Central Hospital (ILACH) in Durban, South Africa over 14 years.Design: Retrospective chart review.Setting and subjects: Patients with pheochromocytoma attending the endocrinology clinic at IALCH between 2012 and 2016 were studied.Outcome measures: Clinical, biochemical and radiological data were collected at presentation, on discharge, one year and five years after surgical intervention; tumour characteristics, histopathological features and surgical outcome were also assessed.Results: The analysis included 35 patients (mean age 33.2 ± 15.7 years; 60% female). Headache (68.6%), palpitation (60%) and sweating (57.6%) were the three most common presenting symptoms; hypertension was the predominant clinical finding (85.7%). Most pheochromocytomas were sporadic (82.9%), adrenal gland tumours (68.6%) and benign (77.1%); of eight patients with malignant tumours, two were familial. Adrenalectomy was undertaken in the majority (n = 34; 97.1%); 55.2% were large tumours. The use of adjunctive radiotherapy (n = 4; 11.4%) and chemotherapy (n = 1; 2.9%) was low. There was low overall mortality (5.7%), but 57.6% developed intraoperative hypotension. At one year postoperatively, 80% (n = 28) of patients were defined as cure, biochemically in 23 (82.1%) and with radiology in five (17.9%).Conclusions: Most patients presenting to IALCH had large intra-abdominal tumours with high cure rate, low mortality but a high rate of perioperative complications. Late presentation and large tumour size was a feature.Keywords: pheochromocytoma , South Africa, surgical outcom

Inducible Clindamycin Resistance among Staphylococci Isolated from Burn Patients

Clindamycin has been used successfully to treat pneumonia and soft-tissue infections caused by methicillin-resistant Staphylococcus aureus. However, inducible clindamycin resistance has been described as a cause of treatment failure of such infections. A total of 159 staphylococcal isolates from different clinical specimens from burn patients in Tripoli Burn Center were tested for inducible clindamycin resistance by the disk-diffusion induction test. Inducible clindamycin resistance was detected in 66.2% of 65 methicillin-resistant S. aureus isolates and in none of 55 methicillin-sensitive S. aureus, 10 methicillin-resistant coagulase negative staphylococci and 29 methicllin-sensitive coagulase negative staphylococci isolates. In our setting, clindamycin can be used for the treatment of infections due to staphylococci, but we recommend that staphylococci isolates, particularly methicillin-resistant S. aureus, are tested by the D-test before treatment

Multidrug resistance and extended-spectrum β-lactamases genes among0 Escherichia coli from patients with urinary tract infections in Northwestern Libya

Introduction: Multidrug resistance (MDR) and emergence of extended-spectrum β-lactamases (ESBLs) that mediate resistance to b-lactam drugs among Escherichia coli and other uropathogens have been reported worldwide. However, there is little information on the detection of ESBLs genes in E. coli from patients with urinary tract infections (UTIs) in the Arab countries using polymerase chain reaction (PCR), and in Libya such information is lacking.Methods: All patients attending Zawiya Teaching Hospital in Zawiya city between November 2012 and June 2013 suspected of having UTIs and from whom midstream urine samples were taken as part of the clinical workup were included in this prospective study. Samples were examined for uropathogens by standard bacteriological procedures. VITEK-2 automated microbiology system was used to identify the isolated uropathogens and determine the susceptibility of E. coli and Klebsiella spp. isolates to antimicrobials. In addition, phenotypically ESBLs-positive E. coli isolates were tested for ESBLs genes by PCR.Results: The present study enrolled 1,790 patients with UTIs. Uropathogens were found in 371 (20.7%) urine specimens examined. Mixed pathogens were detected in two specimens with 373 total pathogens isolated. E. coli and Klebsiella spp. were the predominant uropathogens at 55.8% (208/373) and 18.5% (69/373), respectively. Other pathogens were detected in 25.7% (96/373) of urine samples. Of the E. coli and Klebsiella spp. tested, 69.2 and 100% were resistant to ampicillin, 6.7 and 33.3% to ceftriaxone, and 23.1 and 17.4% to ciprofloxacin, respectively. MDR (resistance to ]3 antimicrobial groups) was found in 69 (33.2%) of E. coli and in 29 (42%) of Klebsiella spp. isolates. ESBLs were detected phenotypically in 14 (6.7%) of E. coli and in 15 (21.7%) of Klebsiella spp. isolates. Thirteen out of the 14 phenotypically ESBL-positive E. coli were positive for ESBL genes by PCR. blaTEM gene was detected in seven isolates, blaOXA gene in 10 isolates and blaCTX-M gene in six isolates. blaSHV gene was not detected in the present study.Conclusion: The isolation of MDRESBL-producing uropathogens undoubtedly will limit the choices clinicians have to treat their patients with UTIs. Therefore, there is an urgent need for surveillance studies on antimicrobial resistance and prevalence of ESBLs among uropathogens to guide the clinical treatment of UTIs in Libya in the future.Keywords: urinary tract infections; Escherichia coli; extended-spectrum β-lactamases; multidrug resistance; Liby

Letter to the Editor: New Delhi metallo- ß -lactamase and OXA-48 carbapenemases in Gram-negative bacilli isolates in Libya

No Abstrac

Viscosity effects on sand flow regimes and transport velocity in horizontal pipelines

Solids transport in multiphase systems is one of the issues under the umbrella of ‘‘flow assurance.’ But unlike issues such as waxes and hydrates, solids transport has received relatively little interest to date. The overall aim of this research was to investigate the fluid viscosity effects on sand particle transport characteristics in pipelines. Investigations were conducted using a 3-inch test facility for oil and a 4- inch flow loop for water and CMC experiments. Three oil viscosities were used including 105 cP, 200 cP and 340 cP. The sand used had a density of 2650 kg/m3 and a median diameter of 0.2 mm. The sand loadings were 50 lb/1000 bbl and 200lb/1000bbl. Based on the King et al (2000) sand minimum transport condition definition, the sand transport velocity for water, CMC solutions and oil (105 cP, 200 cP and 340 cP) were determined by visual observation and camera. The observed sand/oil flow regimes were compared. For oil/sand tests, it was observed that the dominant regime when approaching the critical sand transport velocity was the sliding sand bed, sand dunes were notably absent. However, for water and 7 cP CMC solution, sand dunes and sliding sand bed regimes were observed when approaching the sand transport velocity. For 20cP CMC solution, it was observed that the sand particles in the region between the main dunes were very active compared to those within the dunes