Source current harmonic mitigation of distorted voltage source by using shunt active power filter

In this paper, three-phase, four-wire shunt active power filter (SAPF) is utilized to mitigate system harmonics of distorted voltage source for unbalanced and nonlinear loads. Basically, the source voltage should be pure sinusoidal waveform to get a good mitigation of source current harmonics. In this under study system, the source voltage is assumed to be harmonic distortion non-sinusoidal voltage source. The phase locked loop (PLL) control circuit is wielded for extracting the fundamental component of the distorted source voltage to use it as an input signal to the SAPF control. Another input signal to the SAPF is the distorted load current. The SAPF control system uses (p-q) theory to calculate the optimum instantaneous current to be injected by the SAPF to mitigate the source current harmonics even the source voltage is harmonic distorted. MATLAB/SIMULINK software package is utilized to simulate the system under study. The effect of SAPF is tested when it’s used with and without the PLL control circuit. The simulation results show that, the THD of source current when using the PLL control circuit is improved to comply with the harmonic limits given in the IEEE 519-1992 and IEC 61000-4-7 standards

Effect of Graphene and Fullerene Nanofillers on Controlling the Pore Size and Physicochemical Properties of Chitosan Nanocomposite Mesoporous Membranes

Chitosan (CS) nanocomposite mesoporous membranes were fabricated by mixing CS with graphene (G) and fullerene (F) nanofillers, and the diffusion properties through CS membranes were studied. In addition, in order to enhance the binding between the internal CS chains, physical cross-linking of CS by sodium tripolyphosphate (TPP) was carried out. F and G with different weight percentages (0.1, 0.5, and 1 wt.%) were added on physically cross-linked chitosan (CLCS) and non-cross-linked chitosan (NCLCS) membranes by wet mixing. Permeability and diffusion time of CLCS and NCLCS membranes at different temperatures were investigated. The results revealed that the pore size of all fabricated CS membranes is in the mesoporous range (i.e., 2–50 nm). Moreover, the addition of G and F nanofillers to CLCS and NCLCS solutions aided in controlling the CS membranes’ pore size and was found to enhance the barrier effect of the CS membranes either by blocking the internal pores or decreasing the pore size. These results illustrate the significant possibility of controlling the pore size of CS membranes by cross-linking and more importantly the careful selection of nanofillers and their percentage within the CS membranes. Controlling the pore size of CS membranes is a fundamental factor in packaging applications and membrane technology

Rock slope stability analysis using shear strength reduction technique (SSRT) – case histories

Purpose. This study aims to evaluate the slope stability of open pit comprising massive and jointed rock mass. Methods. Mohr-Coulomb yield function (MC) with shear strength reduction technique (SSRT) are incorporated in finite element analysis (FEA) and four different slopes with varying geometry and geological structural features with an ultimate slope angle of 34° are analyzed using the two-dimensional FEA Program RS2D. The first slope comprises blocky rock mass; the second slope has a network of joints parallel to slope face; the third slope has a parallel joint networks dip out the slope face, and the last slope has a cross-joints network. Findings. The critical strength reduction factor (CSRF) indicates whether the slope face is stable (if CSRF ≥ 1) or not. The minimum CSRF of 0.53 (e.g. compared to 0.55 for parallel joints dip out to the slope face, 0.58 for joints parallel to slope face and 0.65 with no joint existed) is obtained with cross-joints network existed. The CSRF (e.g., CSRF = 0.49) reduces when the MC slip criterion is adopted with the jointed rock mass. Originality. This study attempts new stability indicator namely critical strength reduction factor (CSRF) embedded in shear strength reduction technique (SSRT), based on finite element (FEM) to assess the slope of open pit with respect to presence of geological discontinuities. Practical implications. The slope stability of rock mass is significant to design parameters in open pit mines. Unexpected instability is eventually costly, hazardous to personnel/machinery, disrupted to the mining operation and time-consuming. Therefore, this study Provides a methodology for the application of shear strength reduction technique (SSRT) when evaluating the slope stability of open pit mines with respect to existence of geological features. As a result, the mine planners and engineers will be able to know a head of time when and where necessary support is needed.Мета. Дослідження стійкості укосу при відкритій розробці вугільного пласта в умовах твердих і тріщинуватих порід на основі чисельного моделювання. Методика. Функція плинності Мора-Кулона і метод зменшення опору зсуву використані разом з аналізом кінцевих елементів, причому 4 укоси з відмінностями в геометрії та геологічних структурних характеристиках (з оптимальним кутом схилу 34°) проаналізовані за допомогою двомірної програми FEA Program RS2D. Перший укіс представлений бриластою гірської породою, другий укіс покритий сіткою тріщин, паралельних поверхні укосу, третій укіс має паралельні тріщини, перпендикулярні до поверхні укосу, і останній укіс покритий сіткою пересічних тріщин. Результати. Показано, що ступінь стійкості укосу характеризується індексом зменшення критичного опору (ІЗКО) і при ІЗКО ≥ 1 укіс вважається стійким. Встановлено, що мінімальне значення ІЗКО дорівнює 0.53 (0.55 – для паралельних тріщин, перпендикулярних до поверхні укосу; 0.58 – для тріщин паралельних поверхні укосу; 0.65 – при відсутності тріщин) і відповідає укосу, який покритий сіткою пересічних тріщин. ІЗКО зменшується (наприклад, до 0.49), коли зсувне зміщення функції плинності Мора-Кулона застосовується для аналізу тріщинуватих порід. Наукова новизна. Запропоновано індекс зменшення критичного опору в якості нового індикатора стійкості, який є ключовим фактором методу зменшення опору зсуву, заснованого на методі скінченних елементів, і застосовується для виявлення геологічних несуцільностей укосу кар’єру. Практична значимість. Запропоновано метод зменшення опору зсуву при оцінці стійкості схилу в кар’єрах з урахуванням існуючих геологічних особливостей. Стійкість породного масиву є важливим фактором при проектуванні параметрів кар’єрів, а при проектуванні шахт – для вибору місць та способів кріплення.Цель. Исследование устойчивости откоса при открытой разработке угольного пласта в условиях твердых и трещиноватых пород на основе численного моделирования. Методика. Функция текучести Мора-Кулона и метод уменьшения сопротивления сдвигу использованы вместе с анализом конечных элементов, причем 4 откоса с различиями в геометрии и геологических структурных характеристиках (с оптимальным углом склона 34°) проанализированы с помощью двухмерной программы FEA Program RS2D. Первый откос представлен глыбистой горной породой, второй откос покрыт сеткой трещин, параллельных поверхности откоса, третий откос имеет параллельные трещины, перпендикулярные к поверхности откоса, и последний откос покрыт сеткой пересекающихся трещин. Результаты. Показано, что степень устойчивости откоса характеризуется индексом уменьшения критичного сопротивления (ИУКС) и при ИУКС ≥ 1 откос считается устойчивым. Установлено, что минимальное значение ИУКС равно 0.53 (0.55 – для параллельных трещин, перпендикулярных к поверхности откоса; 0.58 – для трещин, параллельных поверхности откоса; и 0.65 – при отсутствии трещин) и соответствует откосу, который покрыт сеткой пересекающихся трещин. ИУКС уменьшается (например, до 0.49), когда сдвиговое смещение функции текучести Мора-Кулона применяется для анализа трещиноватых пород. Научная новизна. Предложен индекс уменьшения критичного сопротивления в качестве нового индикатора устойчивости, который является ключевым фактором метода уменьшения сопротивления сдвигу, основанного на методе конечных элементов, и применяется для выявления геологических несплошностей откоса карьера. Практическая значимость. Предложен метод уменьшения сопротивления сдвигу при оценке устойчивости склона в карьерах с учетом существующих геологических особенностей. Устойчивость породного массива является важным фактором при проектировании параметров карьеров, а при проектировании шахт – для выбора места и способов крепления.The authors acknowledge the support of Rocscience Inc. for getting a free full educational version of RS2D (Rock-Soil two-dimensional finite-element analysis program). The authors are grateful for their support

Predictors of Long Covid 19 Syndrome

Background: Symptoms of covid persist in most cases with development of a multisystem syndrome called long covid syndrome.Objective: The aim of the work was to evaluate symptoms that persist after the acute stage of the disease in a cohort of patients with confirmed or suspected COVID 19 and to define the predictors for long COVID syndrome.Patients and method: This retrospective study involved 164 patients with previously confirmed or highly suspected COVID 19 and still attending to the post covid outpatient clinic in El-Minia University Chest Hospital complaining from persistence of symptoms or for regular follow up. Their data was obtained from their previous medical reports. Results: Post Covid 19 symptoms were found in about 86 % of the studied patients with 42.7% reported neuropsychiatric symptoms and 26.8% reported respiratory symptoms. The most common reported symptoms in nonsevere cases were the anxiety disorders (18.9%), followed by chronic fatigue and neuropathy (15.2%), while chronic dyspnea in 9.8% mostly in severe cases, while vertigo and headache in 9.1%, musculoskeletal symptoms in 6.1% and skin lesions in 3.7%.Conclusion: It could be concluded that persistence of symptoms is very common after acute Covid 19 infection. Chronic dyspnea was reported more frequently in severe cases while anxiety reported mostly by patients with mild disease

Cosm-nutraceutical nanovesicles for acne treatment : physicochemical characterization and exploratory clinical experimentation

The full exploration of the ‘nutraceuticals’ therapeutic potential in cosmetics has been hindered by their poor stratum corneum permeation. Therefore, the aim of the present study was to formulate a nutraceutical; quercetin, in novel vitamin C based nanovesicles (aspasomes), and to explore their beneficial effects in the treatment of acne. Aspasomes were characterized for their particle size, zeta potential, entrapment efficiency (EE%), 3-months storage stability, skin deposition/permeation, antioxidant potential, and morphology. Aspasomes antibacterial efficacy on 'Propionibacterium acnes' using the zone of inhibition assay was also tested, whilst their safety on skin fibroblastic cells was assessed in vitro using 3T3 CCL92 cell lines. An exploratory clinical trial was conducted in acne patients, and the percentage reduction of inflammatory, non-inflammatory and total acne lesions was taken as the evaluation criterion. Results revealed that quercetin-loaded aspasomes displayed a desirable nanometer size (125–184 nm), negative charge with good storage stability, and high skin deposition reaching 40%. Aspasomes managed to preserve the antioxidant activity of quercetin, and exhibited a significantly higher antibacterial effect (15 ± 1.53 mm) against 'Propionibacterium acnes' than quercetin alone (8.25 ± 2.08 mm), and were safe on skin fibroblastic cells. Upon clinical examination in 20 acne patients (14 females, 6 males), quercetin aspasomes exhibited reduction percentages of 77.9%, 11.8% and 55.3% for inflammatory lesions, comedones and total lesions respectively. This opens vast applications of the presented formulation in the treatment of other oxidative skin diseases, and delineates the nutraceuticals and nanoformulations prepared from natural materials as promising dermatological treatment modes

Versatile additively manufactured (3D printed) wall-jet flow cell for high performance liquid chromatography- amperometric analysis: Application to the detection and quantification of New Psychoactive Substances (NBOMes)

Additive manufacturing (AM/3D printing) is an emerging technology of vast applicability, receiving significant interest in a plethora of industrial domains and scientific research since it allows the rapid translation of designs produced via computer software, into AM/3D printed objects. To date, AM/3D printed devices have been examined for their utilisation as convenient and cost-effective tools towards the detection and quantification of prevalent drugs of abuse. Herein, a novel AM/3D printed wall-jet flow cell was fabricated specifically for employment in high performance liquid chromatography-amperometric detection (HPLCAD) of various analytes (New Psychoactive Substances). Five sensing platforms were investigated, utilising different working electrodes, namely; screen-printed graphite electrodes (SPEs), AM/3D Proto-Pasta, AM/3D Black Magic, graphite sheet and AM/3D printed nanographite (NG) /polylactic acid (PLA)) towards the detection of New Psychoactive Substances. The flow cell was also optimised with respect to the cell geometry demonstrating significant benefits such as simple production and operation and the ability to tailor the platform to a variety of working electrodes. The AM/3D printed sensing platforms were characterised towards the (electro) analytical detection of four N-benzylmethoxy- derivatives: 25F-NBOMe, 25C-NBOMe, 25B-NBOMe and 25I-NBOMe. Furthermore, the (electro) analytical performance of the flow cell was compared with the findings in our previous work comprising of a commercially available impinging jet flow cell. The SPEs and the graphite sheet were found to demonstrate superior electrochemical (analytical) sensitivity and higher reproducibility towards the quantification of the drugs in question, followed by the NG/PLA AM, Proto-Pasta and the Black Magic. The working electrodes that exhibited satisfactory (electro) analytical responses were employed for the analysis of NBOMe derivatives in three simulated blotter papers

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

Global economic burden of unmet surgical need for appendicitis

Background: There is a substantial gap in provision of adequate surgical care in many low-and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods: Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results: Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion: For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe