Transient response analysis for DC-DC boost converter

DC-DC Boost Converter and Hybrid Posicast Controller is developed and simulated using MATLAB Simulink software. DC-DC Boost converter has a very high overshoot and a very high settling time which produce oscillated output response. In order to overcome this weakness, Hybrid Posicast Controller is used in order to regulate the output voltage to a desire value. Hybrid Posicast Controller operated within the feedback loop of the system. Transfer function of DC-DC Boost Converter are derived and Posicast elements of and Td can be calculated directly from the transfer function. Single gain, K is used in order to eliminate the overshoot and minimize the settling time. Simulation results show that Hybrid Posicast Controller effectively regulate the output voltage to a desire value even though load resistance and duty cycle have been changed with a various values. DC-DC Boost Converter using Posicast Controller has an excellent performance to overcome unregulated 377$ input voltage, eliminate overshoot and minimize the settling tim

Bacterial cellulose films: influence of bacterial strain and drying route on film properties

© 2014, Springer Science+Business Media Dordrecht. Structural properties of bacterial cellulose (BC) depend on the microstructure of the material, which in turn is influenced by the bacterial strain. This paper reports the production of BC thin films from two bacterial strains, gluconacetobacter xylinus (GX) and gluconacetobacter europaeus (GE), and three methods of drying the films; at room temperature, freeze drying and supercritical drying. The porosity, transparency, water absorption capacity (WAC) and mechanical properties of the obtained films are further investigated. We conclude that materials with different properties can be fabricated by selecting the bacterial strain or the drying method. Supercritical drying of films of GE achieved mechanically robust and extremely light films, 0.05 g/mL, with up to 96 % of porosity, and with a WAC up 110 times their dried weight. We determined that materials resulting from GE strain are not much affected by the drying method. On the other hand, GX produced BC films more sensitive to the drying method used. Films are denser, 0.6–0.2 g/mL, with tunable porosity from 60 to 90 % and their maximum WAC is 66 times their dried weight.The research leading to these results has received funding from the People Program (Marie Curie Actions) of the European Union’s Seventh Framework Program (FP7/2007-2013) under REA grant agreement no 303630 and cofounded by the European Social Fund. Authors acknowledge the funding from Spanish Ministry of Economy MAT 2012-35324, from the Generalitat de Catalunya 2014SGR213, COST Action MP1202, Ramon y Cajal grant RYC-2010-06082 (AL), and Chinese Scholarship Council fellowship (MZ). The group of Dr. Alex Peralvarez for their help in the bacterial culture, Dr. Josep PuigMartı´ and the group of Prof. David Amabilino for the use of the optical microscope, Prof. Elies Molins and Toni Pons for the use and training in the use of the freeze drier and Dr. Roberto L. Guzman de Villoria for his advices in the mechanical measurements.Peer Reviewe

Meneliti perlaksanaan amalan keselamatan di bengkel pendawaian elektrik di Politeknik Kuching, Sarawak

Amalan keselamatan adalah salah satu aspek yang perlu dititikberatkan di bengkel. Kajian ini bertujuan untuk meneliti perlaksanaan amalan keselamatan di bengkel pendawaian elektrik yang menumpukan kepada perlaksanaan prosedur keIja amali oleh pensyarah dan pelajar, pengurusan bengkel yang berkesan (peralatan dan persekitaran) dan latihan kecemasan. Responden kajian ini terdiri daripada 30 orang pelajar Semester 1, Jabatan Kejuruteraan Elektrik di Politeknik Kuching Sarawak. Kesemua responden ini mengikuti mata pelajaran pendawaian elektrik. Soal selidik digunakan untuk mengumpul data yang dikehendaki. Kesemua data dianalisis dalam bentuk peratusan dengan menggunakan perisian Microsoft Excel. Dapatan kajian menunjukkan prosedur keselamatan keIja amali amali, pengurusan bengkel (peralatan dan perseldtaran) dan perlaksanaan latihan kecemasan dalam keadaan baik kecuali item latihan kecemasan beIjadual yang perlu diambil tindakan lanjutan

Proton beam therapy causing pericarditis - a rare case of radiation induced cardiotoxicity.

Acute pericarditis is caused by the inflammation of the pericardium which can result in an effusion around the heart. Proton beam therapy causing radiation-induced pericarditis is not a well-known cause of pericarditis. We present a case of a patient with Li-Fraumeni Syndrome who developed acute onset pericarditis, presumed to be secondary to proton beam therapy

Beyond the scavenging of reactive oxygen species (ROS): direct efect of cerium oxide nanoparticles in reducing fatty acids content in an in vitro model of hepatocellular steatosis

Cerium oxide nanoparticles; Oxidative stress; Nonalcoholic fatty liver diseaseNanopartículas de óxido de cerio; Estrés oxidativo; Enfermedad del hígado graso no alcohólicoNanopartícules d’òxid de ceri; Estrès oxidatiu; Malalties hepàtiques no alcohòliquesNonalcoholic fatty liver disease (NAFLD) is characterized by hepatic accumulation of lipids. Antisteatotic effects of cerium oxide nanoparticles (CeO2NPs) have recently been shown in animal models of liver disease. However, it is unclear whether the activity of CeO2NPs is related solely to the decrease in oxidative stress or, in addition, they directly decrease liver fatty acid accumulation. To address this question, in this work, we used an in vitro model of hepatocellular steatosis, exposing HepG2 cells to oleic and palmitic acid. Cell uptake of CeO2NPs and their effect on oxidative stress and viability of hepatic cells cultured with H2O2 were also evaluated. Results show that CeO2NPs were uptaken by HepG2 cells and reduced oxidative stress and improved cell viability. Treatment with oleic and palmitic acid increased lipogenesis and the content of different fatty acids. CeO2NPs reduced palmitic and stearic acid and most fatty acids consisting of more than 18 carbon atoms. These effects were associated with significant changes in elongase and desaturase activity. In conclusion, CeO2NPs directly protected HepG2 cells from cell injury in oxidative stress conditions and reduced fatty acid content in steatotic conditions by inducing specific changes in fatty acid metabolism, thus showing potential in the treatment of NAFLD.This research was funded by Ministerio de Economía y Competitividad, grant number PI15-00077 to G.C. and SAF2016-75358-R to M.M-R., co-financed by FEDER, European Union, “A way of making Europe”.; “Secretaria d’Universitats i Recerca del Departament d’Empresa i Coneixement de la Generalitat de Catalunya, convocatòria d’Indústria del Coneixement modalitat B”, grant number 2018_PROD_00187 toW.J, cofinanced by the European Union through the European Regional Development Fund (ERDF), “A way of making Europe”.; CIBERehd is financed by the Instituto de Salud Carlos III.;Wuyi University Funding for Hight Talents Introduction, grant number 2018TP010 to E.C. and 2018TP011 to M.Z.; Foundation from Department of Education of Guangdong Province, grant number 2016KCXTD005 and 2017KSYS010, to E.C. and M.Z. The APC was funded by Wuyi University Funding for Hight Talents Introduction, grant number 2018TP010 to E.C

Minat dan persepsi murid Melayu daripada keluarga sosioekonomi tinggi di sebuah sekolah antarabangsa terhadap pembelajaran bahasa Melayu

Bahasa Melayu ialah bahasa rasmi dalam konteks pendidikan di Malaysia. Di sekolah antarabangsa, Bahasa Melayu ialah bahasa kedua kepada murid-murid warganegara Malaysia yang belajar di sekolah antarabangsa tersebut. Justeru, kajian ini bertujuan untuk meneroka minat murid pembelajaran Bahasa Melayu dalam murid kaum Melayu yang datang daripada keluarga sosioekonomi tinggi (Top 20- T20) di belajar di sebuah sekolah antarabangsa. Seramai tiga orang murid keluarga T20 dijadikan peserta kajian. Ketiga-tiga peserta kajian berumur 11 tahun dan kesemua mereka ialah murid lelaki. Kajian kualitatif dengan menggunakan kaedah temu bual dan analisis dokumen. Data temu bual dianalisis secara bertema. Dapatan kajian menunjukkan bahawa murid-murid T20 ini tidak berminat belajar Bahasa Melayu. Mereka beranggapan Bahasa Melayu tidak penting dan membosankan. Ibu bapa murid Melayu T20 tidak ada masa, sibuk bekerja, tidak bertutur dalam Bahasa Melayu sebaliknya bertutur bahasa Inggeris di rumah. Implikasi daripada kajian ini ialah Bahasa Melayu tidak penting bagi murid-murid yang belajar di sekolah antarabangsa, termasuk dalam kalangan murid kaum Melayu. Faktor sosioekonomi murid yang datang daripada keluarga T20 banyak mempengaruhi penggunaan Bahasa Melayu, terutamanya di rumah. Oleh itu, guru-guru Bahasa Melayu yang mengajar di sekolah antarabangsa perlu mempelbagaikan kaedah pengajaran mereka agar murid-murid T20 ini berminat, berasa seronok dan bermotivasi untuk belajar Bahasa Melayu. Sikap negatif mereka terhadap Bahasa Melayu yang dianggap tidak penting dan membosankan perlu diatasi melalui pengajaran yang kreatif dan menyeronokkan

Beyond the Scavenging of Reactive Oxygen Species (ROS): Direct Effect of Cerium Oxide Nanoparticles in Reducing Fatty Acids Content in an In Vitro Model of Hepatocellular Steatosis

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic accumulation of lipids. Antisteatotic effects of cerium oxide nanoparticles (CeO2NPs) have recently been shown in animal models of liver disease. However, it is unclear whether the activity of CeO2NPs is related solely to the decrease in oxidative stress or, in addition, they directly decrease liver fatty acid accumulation. To address this question, in this work, we used an in vitro model of hepatocellular steatosis, exposing HepG2 cells to oleic and palmitic acid. Cell uptake of CeO2NPs and their effect on oxidative stress and viability of hepatic cells cultured with H2O2 were also evaluated. Results show that CeO2NPs were uptaken by HepG2 cells and reduced oxidative stress and improved cell viability. Treatment with oleic and palmitic acid increased lipogenesis and the content of different fatty acids. CeO2NPs reduced palmitic and stearic acid and most fatty acids consisting of more than 18 carbon atoms. These effects were associated with significant changes in elongase and desaturase activity. In conclusion, CeO2NPs directly protected HepG2 cells from cell injury in oxidative stress conditions and reduced fatty acid content in steatotic conditions by inducing specific changes in fatty acid metabolism, thus showing potential in the treatment of NAFLD

Mesoporous silica coated CeO2nanozymes with combined lipid-lowering and antioxidant activity induce long-term improvement of the metabolic profile in obese Zucker rats

Obesity is one of the most important public health problems that is associated with an array of metabolic disorders linked to cardiovascular disease, stroke, type 2 diabetes, and cancer. A sustained therapeutic approach to stop the escalating prevalence of obesity and its associated metabolic comorbidities remains elusive. Herein, we developed a novel nanocomposite based on mesoporous silica coated cerium oxide (CeO2) nanozymes that reduce the circulating levels of fatty acids and remarkably improve the metabolic phenotype in a model of obese Zucker rats five weeks after its administration. Lipidomic and gene expression analyses showed an amelioration of the hyperlipidemia and of the hepatic and adipose metabolic dysregulations, which was associated with a down-regulation of the hepatic PI3K/mTOR/AKT pathway and a reduction of the M1 proinflammatory cytokine TNF-a. In addition, the coating of the CeO2 maximized its cell antioxidant protective effects and minimized non-hepatic biodistribution. The one-pot synthesis method for the nanocomposite fabrication is implemented entirely in aqueous solution, room temperature and open atmosphere conditions, favoring scalability and offering a safe and translatable lipid-lowering and antioxidant nanomedicine to treat metabolic comorbidities associated with obesity. This approach may be further applied to address other metabolic disorders related to hyperlipidemia, low-grade inflammation and oxidative stress.This research was supported by the Instituto de Salud Carlos III (PI19/00774 to G. C. and G. F.-V.), Dirección General de Investigación Científica y Técnica (RTI2018-094734-B-C2 to W. J.), co-financed by FEDER, European Union, “A way of making Europe”, and the Secretaria d'Universitats i Recerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya (2018_PROD_00187 to W. J.), the National Natural Science Foundation of China (31950410536 to E. C. and 22005221 to M. Z.), the Wuyi University Funding (2018TP010 to E. C., and 2018TP011 and 2020FKZX05 to M. Z.), Guangdong Science and Technology Department (2019A050512006 to E. C.), and the Academy of Finland (309374 to J. M. R.)

Scalable synthesis of multicomponent multifunctional inorganic core@mesoporous silica shell nanocomposites

Integrating multiple materials with different functionalities in a single nanostructure enables advances in many scientific and technological applications. However, such highly sophisticated nanomaterials usually require complex synthesis processes that complicate their preparation in a sustainable and industrially feasible manner. Herein, we designed a simple general method to grow a mesoporous silica shell onto any combination of hydrophilic nanoparticle cores. The synthetic strategy, based on the adjustment of the key parameters of the sol-gel process for the silica shell formation, allows for the embedment of single, double, and triple inorganic nanoparticles within the same shell, as well as the size-control of the obtained nanocomposites. No additional interfacial adhesive layer is required on the nanoparticle surfaces for the embedding process. Adopting this approach, electrostatically stabilized, small-sized (from 4 to 15 nm) CeO2, Fe3O4, Gd2O3, NaYF4, Au, and Ag cores were used to test the methodology. The mean diameter of the resulting nanocomposites could be as low as 55 nm, with high monodispersity. These are very feasible sizes for biological intervention, and we further observed increased nanoparticle stability in physiological environments. As a demonstration of their increased activity as a result of this, the antioxidant activity of CeO2 cores was enhanced when in core-shell form. Remarkably, the method is conducted entirely at room temperature, atmospheric conditions, and in aqueous solvent with the use of ethanol as co-solvent. These facile and even "green" synthesis conditions favor scalability and easy preparation of multicomponent nanocomposite libraries with standard laboratory glassware and simple benchtop chemistry, through this sustainable and cost-effective fabrication process.This work was financially supported by the National Natural Science Foundation of China (31950410536 to E.C. and 22005221 to M.Z.), the Wuyi University (2018TP010 to E.C., 2018TP011 and 2020FKZX05 to M.Z., and 2019TD02 to J.P.), Guangdong Science and Technology Department (2019A050512006 to E.C.), the Academy of Finland (309374 to J.M.R.), and the Instituto de Salud Carlos III of Spain (PI19/00774 to G.F-V and G.C.), co-financed by FEDER, European Union, “A way of making Europe”

Beyond the scavenging of reactive oxygen species (Ros) : direct effect of cerium oxide nanoparticles in reducing fatty acids content in an in vitro model of hepatocellular steatosis

Altres ajuts: Secretaria d'Universitats i Recerca del Departament d'Empresa i Coneixement de la Generalitat de Catalunya, convocatòria d'Indústria del Coneixement modalitat B", grant number 2018_PROD_00187 toW.J, cofinançat per la Unió Europea a través de la European Regional Development Fund (ERDF)Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic accumulation of lipids. Antisteatotic effects of cerium oxide nanoparticles (CeO₂NPs) have recently been shown in animal models of liver disease. However, it is unclear whether the activity of CeONPs is related solely to the decrease in oxidative stress or, in addition, they directly decrease liver fatty acid accumulation. To address this question, in this work, we used an in vitro model of hepatocellular steatosis, exposing HepG2 cells to oleic and palmitic acid. Cell uptake of CeO₂NPs and their effect on oxidative stress and viability of hepatic cells cultured with H₂O₂ were also evaluated. Results show that CeO₂NPs were uptaken by HepG2 cells and reduced oxidative stress and improved cell viability. Treatment with oleic and palmitic acid increased lipogenesis and the content of different fatty acids. CeO₂NPs reduced palmitic and stearic acid and most fatty acids consisting of more than 18 carbon atoms. These effects were associated with significant changes in elongase and desaturase activity. In conclusion, CeO₂NPs directly protected HepG2 cells from cell injury in oxidative stress conditions and reduced fatty acid content in steatotic conditions by inducing specific changes in fatty acid metabolism, thus showing potential in the treatment of NAFLD