bluuebunny/crossref_metadata_2025 huggingface dataset:
Intrarenal Renin-Angiotensin-System Dysregulation after Kidney Transplantation
Authors: Kovarik Johannes J. , Kaltenecker Christopher C. , Kopecky Chantal , Domenig Oliver , Antlanger Marlies , Werzowa Johannes , Eskandary Farsad , Kain Renate , Poglitsch Marko , Schmaldienst Sabine , Böhmig Georg A. , Säemann Marcus D.
Published: July 2019

Angiotensin-converting enzyme inhibitors (ACEis) are beneficial in patients with chronic kidney disease (CKD). Yet, their clinical effects after kidney transplantation (KTx) remain ambiguous and local renin-angiotensin system (RAS) regulation including the ‘classical’ and ‘alternative’ RAS has not been studied so far. Here, we investigated both systemic and kidney allograft-specific intrarenal RAS using tandem mass-spectrometry in KTx recipients with or without established ACEi therapy (n = 48). Transplant patients were grouped into early (<2 years), intermediate (2–12 years) or late periods after KTx (>12 years). Patients on ACEi displayed lower angiotensin (Ang) II plasma levels (P < 0.01) and higher levels of Ang I (P < 0.05) and Ang-(1–7) (P < 0.05) compared to those without ACEi independent of graft vintage. Substantial intrarenal Ang II synthesis was observed regardless of ACEi therapy. Further, we detected maximal allograft Ang II synthesis in the late transplant vintage group (P < 0.005) likely as a consequence of increased allograft chymase activity (P < 0.005). Finally, we could identify neprilysin (NEP) as the central enzyme of ‘alternative RAS’ metabolism in kidney allografts. In summary, a progressive increase of chymase-dependent Ang II synthesis reveals a transplant-specific distortion of RAS regulation after KTx with considerable pathogenic and therapeutic implications.
Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chloride) in a Randomized, Double-Blind, Placebo-controlled Clinical Trial of Healthy Overweight Adults
Authors: Conze Dietrich , Brenner Charles , Kruger Claire L.
Published: July 2019

Nicotinamide riboside (NR) is a newly discovered nicotinamide adenine dinucleotide (NAD+) precursor vitamin. A crystal form of NR chloride termed NIAGEN is generally recognized as safe (GRAS) for use in foods and the subject of two New Dietary Ingredient Notifications for use in dietary supplements. To evaluate the kinetics and dose-dependency of NR oral availability and safety in overweight, but otherwise healthy men and women, an 8-week randomized, double-blind, placebo-controlled clinical trial was conducted. Consumption of 100, 300 and 1000 mg NR dose-dependently and significantly increased whole blood NAD+ (i.e., 22%, 51% and 142%) and other NAD+ metabolites within 2 weeks. The increases were maintained throughout the remainder of the study. There were no reports of flushing and no significant differences in adverse events between the NR and placebo-treated groups or between groups at different NR doses. NR also did not elevate low density lipoprotein cholesterol or dysregulate 1-carbon metabolism. Together these data support the development of a tolerable upper intake limit for NR based on human data.
Iron overload reduces synthesis and elimination of bile acids in rat liver
Authors: Prasnicka Alena , Lastuvkova Hana , Alaei Faradonbeh Fatemeh , Cermanova Jolana , Hroch Milos , Mokry Jaroslav , Dolezelova Eva , Pavek Petr , Zizalova Katerina , Vitek Libor , Nachtigal Petr , Micuda Stanislav
Published: July 2019

Excessive iron accumulation in the liver, which accompanies certain genetic or metabolic diseases, impairs bile acids (BA) synthesis, but the influence of iron on the complex process of BA homeostasis is unknown. Thus, we evaluated the effect of iron overload (IO) on BA turnover in rats. Compared with control rats, IO (8 intraperitoneal doses of 100 mg/kg every other day) significantly decreased bile flow as a consequence of decreased biliary BA secretion. This decrease was associated with reduced expression of Cyp7a1, the rate limiting enzyme in the conversion of cholesterol to BA, and decreased expression of Bsep, the transporter responsible for BA efflux into bile. However, IO did not change net BA content in faeces in response to increased intestinal conversion of BA into hyodeoxycholic acid. In addition, IO increased plasma cholesterol concentrations, which corresponded with reduced Cyp7a1 expression and increased expression of Hmgcr, the rate-limiting enzyme in de novo cholesterol synthesis. In summary, this study describes the mechanisms impairing synthesis, biliary secretion and intestinal processing of BA during IO. Altered elimination pathways for BA and cholesterol may interfere with the pathophysiology of liver damage accompanying liver diseases with excessive iron deposition.
Silent Changes in Sleep Quality Following Mandibular Setback Surgery in Patients with Skeletal Class III Malocclusion: A Prospective Study
Authors: On Sung Woon , Kim Hyun Jun , Cho Dong Hyeon , Moon Yeo Rae , Il Song Seung
Published: July 2019

Mandibular setback surgery (MSS) for skeletal class III patients can result in a relative reduction of pharyngeal airway space (PAS). Consequently, there is a possibility of the decline of sleep quality after surgery. We investigated changes in sleep quality measured by overnight polysomnography (PSG) and the three-dimensional (3D) volumes of PAS following MSS with or without Le Fort I osteotomy (LF I) in class III patients (N = 53). Overnight PSG and cone beam computed tomography were conducted at preoperative stage (T0) and postoperative 3 months (T1). Measurements of PAS volumes were performed, and the subjective symptoms of sleep were evaluated by self-questionnaires. There were significant increases in respiratory disturbance index (RDI) and total respiratory effort-related arousal (RERA) index during T0-T1. The 3D volumes of PAS showed significant decreases in the oropharyngeal airway, hypopharyngeal airway, and total airway spaces. No significant changes were observed in subjective symptoms of sleep. MSS with or without LF I for class III patients could worsen sleep quality by increasing sleep parameters such as the RDI and RERA in PSG, and reduce volumes of PAS at postoperative 3 months. Although subjective symptoms may not show significant changes, objective sleep quality in PSG might decrease after MSS.
Bacterial Density and Biofilm Structure Determined by Optical Coherence Tomography
Authors: Hou Jiapeng , Wang Can , Rozenbaum René T. , Gusnaniar Niar , de Jong Ed D. , Woudstra Willem , Geertsema-Doornbusch Gésinda I. , Atema-Smit Jelly , Sjollema Jelmer , Ren Yijin , Busscher Henk J. , van der Mei Henny C.
Published: July 2019

Optical-coherence-tomography (OCT) is a non-destructive tool for biofilm imaging, not requiring staining, and used to measure biofilm thickness and putative comparison of biofilm structure based on signal intensity distributions in OCT-images. Quantitative comparison of biofilm signal intensities in OCT-images, is difficult due to the auto-scaling applied in OCT-instruments to ensure optimal quality of individual images. Here, we developed a method to eliminate the influence of auto-scaling in order to allow quantitative comparison of biofilm densities in different images. Auto- and re-scaled signal intensities could be qualitatively interpreted in line with biofilm characteristics for single and multi-species biofilms of different strains and species (cocci and rod-shaped organisms), demonstrating qualitative validity of auto- and re-scaling analyses. However, specific features of pseudomonas and oral multi-species biofilms were more prominently expressed after re-scaling. Quantitative validation was obtained by relating average auto- and re-scaled signal intensities across biofilm images with volumetric-bacterial-densities in biofilms, independently obtained using enumeration of bacterial numbers per unit biofilm volume. The signal intensities in auto-scaled biofilm images did not significantly relate with volumetric-bacterial-densities, whereas re-scaled intensities in images of biofilms of widely different strains and species increased linearly with independently determined volumetric-bacterial-densities in the biofilms. Herewith, the proposed re-scaling of signal intensity distributions in OCT-images significantly enhances the possibilities of biofilm imaging using OCT.
An unexpected genetic diversity pattern and a complex demographic history of a rare medicinal herb, Chinese asparagus (Asparagus cochinchinensis) in Korea
Authors: Lee Soo-Rang , Park Han-Sol , Kim Bo-Yun , Lee Jung-Hoon , Fan Qiang , Gaskin John F. , Kim Young-Dong
Published: July 2019

Range-wide population studies of wide spread species are often associated with complex diversity patterns resulting from genetically divergent evolutionary significant units (ESUs). The compound evolutionary history creating such a pattern of diversity can be inferred through molecular analyses. Asparagus cochinchinensis, a medicinally important perennial herb, is in decline due to overharvesting in Korea. Eight A. cochinchinensis populations in Korea and three populations from neighboring countries (China, Japan and Taiwan) were examined using nine nuclear microsatellite loci and three chloroplast microsatellite loci to characterize molecular diversity patterns. The average within-population diversity was limited likely due to long-term bottlenecks observed in all eight populations. High pairwise FST values indicated that the populations have largely diverged, but the divergences were not correlated with geographic distances. Clustering analyses revealed a highly complex spatial structure pattern associated with two ESUs. Approximate Bayesian Computation (ABC) suggests that the two ESUs split about 21,000 BP were independently introduced to Korea approximately 1,800 years ago, and admixed in secondary contact zones. The two ESUs found in our study may have different habitat preferences and growth conditions, implying that the two genetically divergent groups should be considered not only for conservation and management but also for breeding programs in agricultural areas.
Retinal myeloid cells regulate tip cell selection and vascular branching morphogenesis via Notch ligand Delta-like 1
Authors: Haupt Fabian , Krishnasamy Kashyap , Napp L. Christian , Augustynik Michael , Limbourg Anne , Gamrekelashvili Jaba , Bauersachs Johann , Haller Hermann , Limbourg Florian P.
Published: July 2019

During angiogenesis, single endothelial cells (EC) specialize into tip cells that guide vessel sprouting towards growth factor gradients and instruct the adjacent vessel stalk. The balance between tip and stalk cells is regulated by endothelial Notch signalling through the expression of Notch ligand Delta-like 4 (Dll4) in tip cells, which suppresses a tip cell fate in adjacent stalk cells. Here we show, using genetic reporter and conditional deletion strategies, that myeloid cells regulate tip cell numbers and Dll4 expression via the Notch ligand Dll1 during vascular development in the retina. Dll1 is selectively expressed by a subpopulation of retinal myeloid cells, which progressively localizes to the sprouting vascular network. Conditional, myeloid-specific deletion of Dll1 impairs endothelial Dll4 tip-stalk gradient resulting in an increase of endothelial tip cells and EC filopodia, accompanied by an increase in vascular density and branching. In vitro, co-culture of human EC with monocyte-derived macrophages induced Dll1 upregulation in macrophages and Dll4 upregulation and an endothelial tip cell signature in EC. Furthermore, culturing human EC on recombinant DLL1 induced endothelial Dll4 expression and a tip cell program, indicating that changes are Dll1-dependent. Thus, myeloid cells regulate tip cell fate and angiogenesis through expression of Notch ligand Dll1.
Correlation Analysis of the Anterolateral Ligament Length with the Anterior Cruciate Ligament Length and Patient’s Height: An Anatomical Study
Authors: Hohenberger Gloria M. , Maier Marco , Schwarz Angelika M. , Grechenig Peter , Weiglein Andreas H. , Hauer Georg , Leithner Andreas , Sadoghi Patrick
Published: July 2019

The aim of this study was to evaluate the anatomical characteristics of the anterolateral ligament of the knee (ALL) with the focus on potential gender differences. The ALL length and the length of the lateral collateral ligament (LCL) were taken in extension. The length of the anterior cruciate ligament (ACL) was measured at 120° flexion. We correlated the length of the ALL with the LCL and ACL with respect to potential gender differences. The ALL was significantly (p = 0.044) shorter in females (mean length: 32.8 mm) compared to males (mean length: 35.7 mm). The length of the ALL correlated significantly positively with the lengths of the ACL (p < 0.001) and the LCL (p < 0.001). There was no significant correlation with the total leg length (TLL) (p = 0.888) and body size (p = 0.046). Furthermore, TLL and donor size correlated significantly positively (p < 0.001). The ALL length correlated significantly positively with the ACL and the LCL length. The ALL length did neither correlate with the TLL nor the donor size. This fact may contribute to planning of graft harvesting in the upcoming techniques for ALL reconstruction.
Enhancement of element production by incomplete fusion reaction with weakly bound deuteron
Authors: Wang H. , Otsu H. , Chiga N. , Kawase S. , Takeuchi S. , Sumikama T. , Koyama S. , Sakurai H. , Watanabe Y. , Nakayama S. , Ahn D. S. , Baba H. , Chen S. D. , Chikaato K. , Cortés M. L. , Fukuda N. , Hirayama A. , Hosoda R. , Isobe T. , Kawakami S. , Kondo Y. , Kubono S. , Maeda Y. , Masuoka S. , Michimasa S. , Murray I. , Nakajima R. , Nakamura T. , Nakano K. , Nishimura M. , Ozaki T. , Saito A. , Saito T. , Sato H. , Shimizu Y. , Shimoura S. , Söderström P. -A. , Soudo Y. , Sun X. H. , Suwa J. , Suzuki D. , Suzuki H. , Takeda H. , Takechi M. , Togano Y. , Tomai T. , Yamada H. , Yasuda M. , Yoshida K.
Published: July 2019

Searching for effective pathways for the production of proton-rich and neutron-rich isotopes is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. To produce nuclei effectively, an optimal combination of reaction mechanism and energy is required. We report a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 107Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential for incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
Retracted Article: MiR-132 enhances proliferation and migration of HaCaT cells by targeting TIMP3
Authors: Jiang Lina , Jiang Yizhou , Ji Xiaohui , Li Jiangtao , Zhai Ximei
Published: July 2019

MicroRNAs (miRNAs) are involved in multiple skin pathologies, including wound healing.
Amyloidogenic model peptides as catalysts for stereoselective aldol reactions
Authors: Pelin Juliane N. B. D. , Gerbelli Barbara B. , Soares Bruna M. , Aguilar Andrea M. , Alves Wendel A.
Published: July 2019

Different polymorphic forms of peptide assemblies influence the stereoselectivity of aldol reactions in water medium.
Facet-selective adsorption of Fe(ii) on hematite visualized by nanoscale secondary ion mass spectrometry
Authors: Taylor Sandra D. , Kovarik Libor , Cliff John B. , Rosso Kevin M.
Published: July 2019

Novel isotopic labelling and imaging techniques are used to directly observe the autocatalytic reaction and facet-selective adsorption of Fe(ii) onto individual hematite (Fe2O3) crystallites.
Strong, detachable, and self-healing dynamic crosslinked hot melt polyurethane adhesive
Authors: Wang Shuliang , Liu Zenghe , Zhang Luzhi , Guo Yifan , Song Jianchun , Lou Jiaming , Guan Qingbao , He Chuanglong , You Zhengwei
Published: July 2019

A dynamic oxime–carbamate based polyurethane hot melt adhesive was developed with outstanding adhesion performance to multiple substrates, and detachable and self-healing properties.
Two zinc(ii) coordination polymers based on flexible co-ligands featuring assembly imparted sensing abilities for Cr2O72− and o-NP
Authors: Zhang Meili , Zheng Yanjin , Liu Min , Ren Yixia , Wang Zhixiang , Cao Jia , Wang Jijiang
Published: July 2019

Two zinc(ii) complexes exhibit the different architectures, and they have been shown to be excellent discriminative probe for the highly selective and sensitive detection of Cr2O72− and o-NP based on their sensitive fluorescence quenching.
Synthetic approaches for advanced multi-block anion exchange membranes
Authors: Shin Dongwon , Nugraha Adam F. , Wijaya Farid , Lee Sojeong , Kim Eunyoung , Choi Jieun , Kim Hyoung-Juhn , Bae Byungchan
Published: July 2019

Multi-block copolymers bearing ionic functional groups were synthesized through direct polymerization or post-functionalization.
Robust fault‐detection based on residual K–L divergence for wind turbines
Authors: Zhang Yuxian , Wang Kefeng , Qian Xiaoyi , Gendeel Mohammed
Published: July 2019

A robust fault‐detection design based on residual Kullback–Leibler (K–L) divergence, which is applied to a 5 MW offshore wind turbine (WT) benchmark, is presented. The main challenges of the wind turbine fault detection lie in its complex operation conditions and disturbances as well as measurement noise. For overcoming these difficulties, the measured data are divided on the basis of the operation conditions of WT. The robust residual generator based on parity vector is adopted to calculate the residual under different operation conditions. The K–L divergence based on probability density function is employed to measure the residual. Then, the threshold for the fault detection is determined in line with both false alarm rate and missed detection rate. The simulation results show that the performance and effectiveness of the proposed robust fault detection are better than compared with other data‐driven fault‐detection approaches.
Hybrid data‐model method to improve generation estimation and performance assessment of grid‐tied PV: a case study
Authors: Sundararajan Aditya , Sarwat Arif I.
Published: July 2019

Increased installed capacity of distributed photovoltaic (PV) systems has necessitated accurate measurement and tracking of PV performance under locality‐specific conditions of irradiance, temperature, and derate factors. Existing PV generation estimation methods are strictly model based and not responsive to changes in weather and system losses. Metrics computed using these methods, therefore, do not capture the real PV behaviour well. This study proposes a hybrid data‐model method (HDMM) that uses historical PV data in addition to model information to improve the accuracy of generation estimation. The generation estimated by HDMM is used to compute performance metrics – performance ratio, yield, capacity factor, energy performance index, and power performance index – for two real‐world PV systems at Miami (, 1.4 MW) and Daytona (, 1.28 MW) for 2017. The significance of these metrics is then evaluated, and a preliminary analysis of inverter efficiencies is provided. Results from this study show that when compared with the existing estimation method, HDMM performs better on an average by 75% for and 10% for . Further, at a given point in time, system is likely to perform better than . The study gives system installers and other stakeholders better PV system visibility, enabling aggregation and transactive energy.
Sliding mode type‐2 neuro‐fuzzy power control of grid‐connected DFIG for wind energy conversion system
Authors: Moradi Hassan , Alinejad‐Beromi Yousef , Yaghobi Hamid , Bustan Danyal
Published: July 2019

This study presents an adaptive sliding mode type‐2 neuro‐fuzzy controller for power control of doubly fed induction generators (DFIGs). DFIG‐based wind turbine system is variable‐speed constant‐frequency wind energy conversion system. In this proposed control scheme, in order to enhance its performance, sliding mode control (SMC) theory is used for online training the parameters of type‐2 fuzzy system membership functions. To regulate the antecedent and consequent part parameters, the SMC adaptive technique is used according to the controller inputs. These inputs are active and reactive power errors and their time derivative, which applied to the structure of T2NF system. The proposed controller employs an interval type‐2 fuzzy system because of the uncertainties of the wind speed and variation in parameters in the wind power conversion system. The simulations carried out for a DFIG‐based 1.5 MW wind turbine. The results of simulation are compared with the classical proportional–integral controller to confirm the effectiveness of this control scheme. This comparison is carried out between the cut‐in and rated region wind speeds. The results of simulation show that the proposed control scheme has better performance to track the peak power and is more robust to machine parameter variations.
A new control strategy for low‐voltage ride‐through of three‐phase grid‐connected PV systems
Authors: Wen Hao , Fazeli Meghdad
Published: July 2019

Power quality and current limitation are the most important aspects of the grid‐connected power converters under fault. Since the distributed energy resources are widely used, fault management strategy is important for micro‐grids applications. This paper presents a new control strategy for low‐voltage ride‐through for 3‐phase grid‐connected photovoltaic systems. The proposed method, which is designed in a synchronous frame using positive and negative sequence components, can protect the inverter from overcurrent failure under both symmetrical and unsymmetrical faults and provides reactive power support. The method does not require a hard switch to switch from MPPT to a non‐MPPT algorithm, which ensures a smooth transition.
Smart noise jamming suppression method based on fast fractional filtering
Authors: Han Bowen , Yang Xiaopeng , Wu Xuchen , Li Shuai
Published: July 2019

Smart noise jamming based on digital radio frequency memory (DRFM) has both oppressive jamming effect and deceptive jamming effect, and it is difficult to be effectively suppressed by traditional anti‐jamming methods. In order to solve this problem, an anti‐jamming method for linear frequency modulation (LFM) pulse compression radar system is proposed. The proposed method is combined with fractional Fourier transform (FrFT) and fractional domain filtering strategy. Here, first, the FrFT transform is performed on the received signal, and the optimal transform angle is calculated by calculating the fractional fourth‐order origin moment. Then, the narrow‐band filter is performed in the fractional domain to extract the target signal and suppress the jamming signal. Finally, fractional Fourier inverse transform is done to restore the target signal. The simulation results show that the method not only can effectively suppress smart noise jamming but also can accurately detect the position of the target.
Decoupling self‐correcting method for non‐uniform dual circular array
Authors: Zhang Jiajia , Chen Hui , Liu Weijian
Published: July 2019

According to the structural characteristics of non‐uniform dual circular array (NDCA), a new method is proposed to solve the problem of mutual coupling error. In this algorithm, solving the mutual coupling problem of NDCA can be equivalent to solving that of non‐uniform linear array (NLA). Firstly, the mutual coupling matrix is divided into several blocks. Then, each sub‐block can be decomposed into the sum of several matrices with special characteristics by matrix addition method. As a result, the signal angles and mutual coupling coefficients can be conveniently decoupled. Compared with the iterative self‐calibration algorithm, the proposed algorithm has a small amount of calculation. Moreover, it neither requires any prior information nor has problem of local convergence. The new method can accurately estimate the signal directions and mutual coupling coefficients.
Fast ship contour extraction in SAR images
Authors: Nie Yuan‐Ying , Fan Shu‐Chen , Shui Peng‐Lang
Published: July 2019

Fast ship contour extraction in synthetic aperture radar (SAR) images plays an important role in sea surface surveillance. Ship contours and sizes and shapes extracted from them are salient features in ship classification and recognition. This study presents a two‐step method to fast extract ship contours. At the first step, an existing object detection method is used to extract bounding boxes of ships. Next, the morphological operators are applied to each box to yield a compact external contour. At the second step, using the compact external contour as the initial contour, the active contour algorithm is used to iteratively generate ship contours. Owing to compact initial external contour, the active contour algorithm avoids the topological merging and splitting, two time‐consuming operations. In this way, ship contours can be fast extracted.
Development of inductive‐loaded ultra‐wideband monopole antennas from stepped‐impedance resonators
Authors: Asokan Hefilia , Gopalakrishnan Srivatsun
Published: July 2019

An ultra‐wideband (UWB) printed monopole antenna is designed from stepped‐impedance resonator (SIR) geometry. An inductor which is loaded in series between the radiating strips combines the multiple resonance bands of a two‐strip stepped‐impedance printed monopole antenna into a single ultra‐wide resonance band. The two‐strip inductive‐loaded stepped‐impedance printed monopole antenna is theoretically analysed for its resonant frequencies with the proposed modified transmission line analysis of inductive‐loaded SIR model. The proposed analysis is validated by comparing the resonances with the electromagnetic simulation results and real‐time measured results from the fabricated prototype of the antenna. The prototype of the two‐strip inductive‐loaded stepped‐impedance printed monopole antenna fabricated on the low‐cost FR4 substrate, resonated for the ultra‐wide frequency range from 2.58 to 10 GHz.
Application of soy protein isolate in the fining of red wine
Authors: Ficagna Evandro , Gava Angelo , Rossato Simone Bertazzo , Rombaldi César Valmor , Zavareze Elessandra da Rosa
Published: July 2019

Soy protein isolate was evaluated as a potential fining agent as an alternative to the predominant protein commercial fining agents (ovalbumin, porcine gelatin, and pea protein isolate). Two red wines (cv. ‘Merlot’ and cv. ‘Lambrusco Maestri’) were finned, bottled, and analyzed for phenolic content, color, turbidity, and sensory profile. Independent of the protein used, fining promoted a reduction in a majority of the phenolic compound, a slight (but significant) reduction of chromatic properties, and a decrease in the turbidity of the wines. A decrease in astringency, persistence, bitterness, and wine body, as well as an increase in brightness, clarity, and acidity, was also observed in all treatments. The application of soy protein isolates yielded similar results to those obtained with other commercial fining agents, both in the physicochemical and the sensory measures, which favors its usage as an alternative to the traditional fining agents of animal-protein origin.
Analysis of harmonic resonance mechanism of PV power plant
Authors: Jing Shi , Zhimin Wang , Zhonghua Huang , Yanshou Qi
Published: July 2019

Great amount of PV inverters connected with the PV power plant causes the power system to become electronically power and affects the operation mode of the traditional power system. High-frequency switching characteristics of PV inverters carry a large number of harmonic components, even lead to the harmonic resonance of a multi-machine parallel system. In the paper, based on physical mechanism of power electronics, a high-order model of harmonic impedance of a typical PV power plant is established, and harmonic resonance mechanism in parallel operation of PV power plant is analyzed, as well as key factors.
Simulation of single phase photovoltaic system based on fuzzy logic control with multilevel inverter
Authors: Raweh Ezzaldden , Pi Wei , Busati Omar , Rehman Abdul , Mubbarak Saif , Wang Yinshun
Published: July 2019

To control the solar power, reliability and stability are two main challenges. In addition, the total harmonic distortion (THD) must be within limits for optimal operation. In an inverter, the harmonics are produced during the conversion of DC power to AC power, which will affect the power electronic devices. Therefore, to overcome such challenges in high voltage and high power systems multilevel inverter (MLI) topology is more useful. Such type of inverters uses various DC voltage levels to generate the stepped AC at its output, approaching the sinusoidal shape. The cascaded H-bridge, capacitor-clamped, and diode-clamped are the most commonly used multilevel inverters topologies. For photovoltaic (PV) usage, cascaded H-bridge (CHB) MLI is more adaptive among the three topologies, where for each H-bridge unit; each PV model behaves as an isolated DC source. This paper specifically focused on the simulation of PV power as a source to the system and displayed the potential of a single-phase 11-level CHB inverter. For switching the IGBT devices, sinusoidal pulse width modulation (SPWM) is applied. Moreover, the fuzzy logic control (FLC) is introduced to improve the power quality. FLC reduce the THD via finding the appropriate set of IGBT switch signals. To show the improvement in the operation and reduction in the complex harmony signal effects of the CHB 11-level inverter, the proposed system is designed in Matlab/Simulink software. Finally, the results show that the dynamic behavior of the FLC is much better than the traditional proportional integral derivative (PID) controller.
Robust energy storage allocation for transmission grid integrated by multiple wind farms
Authors: Jinmin Cheng , Weiyuan Wang , Xuan Yu , Kai Xia , Yiqing Xu , Zhendong Wan , Guanzhong Wang
Published: July 2019

Since optimal planning for energy storage sizing and locating is critical to meet the requirement of total wind power absorption, a robust optimization theory based energy storage allocation model for transmission grid with multiple wind farms integrated is proposed in this paper. The model fully considers the transmission capacity limitation, and uses linear decision rule to optimize the allocation of the reserve capacity of the adjustable units and energy storage devices to cope with the fluctuation of wind power, which makes full use of the regulation capacity in the system. Some statistical information of wind power, such as expectation and interval, is used to describe the uncertainty of wind power. The uncertainty model is transformed into a deterministic model by using the duality optimization theory, which provides convenience for engineering application. The Garver’s 6-bus transmission system model is used for example analysis, which shows that the proposed method can effectively solve the energy storage planning problem for uncertain wind power integrated power systems.
Research on large-scale wind power utilization technology based on energy storage
Authors: Zhang Xiaochen , Du Wei , Fu Jinzhou , Yang Dongmei , Chen Yonghua
Published: July 2019

To improve the wind power utilization, methods of adding electricity storage device, adding heat storage device, treating the heat pipe network as a heat storage device are proposed. Firstly, the characteristics of cogeneration, electricity storage and heat storage equipment are analyzed. Secondly, the objective function of thermoelectric system is constructed. Meanwhile, system constraints are also introduced. Then, the scheduling model is transformed into a linear programming problem and solved with CPLEX toolbox. Finally, a typical cogeneration case is established to test the effectiveness of the proposed methods. The simulation results show that all these methods can effectively improve the amount of wind power utilization.
Perspectives of modern energy storage in miniscule photovoltaic installations
Authors: Olszewska Danuta , Kiełczykowska Paulina , Olszewski Miłosz
Published: July 2019

In the research work environmental pollution information and idea of solution of this problem through renewable energy sources were presented. The methods of solar energy coversion as well as methods of its storage in lithium batteries were described. The work presents an analysis of energy system: solar panel and energy bank in households. The ecological aspect of this solution was studied. For this purpose, the costs of new single-family house connection to the energy grid and photovoltaic system connection with a modern lithium battery were calculated. Electricity consumption cost estimation within ten years was made and then it was compared to the expenses for connected photovoltaic system with lithium battery. Aim of the study was realized based on the cost of connection to the energy grid and the costs of photovoltaic system connection with Tesla batteries. From the above data one can see that after about 7 years with lower solar exposure level costs of the installation based on renewable energy sources installation will pay off and after that one can only record a profit from storing and producing electricity.
Analysis of the possibility of identifying incorrect operation of heating devices in real conditions
Authors: Nygard Adam , Bartoszewicz Jarosław , Urbaniak Rafał
Published: July 2019

The paper presents a preliminary stage of works aiming at a development of a method of identification of a wrong use of heating equipment under actual conditions of operation based on an a continuous analysis of oxygen level in the exhaust gas. The investigations were carried out on a test stand at the Chair of Thermal Engineering of Poznan University of Technology. For the tests, the author used a Q-EKO 15 boiler by Heiztechnik available in the Polish and European markets. In order to develop the method of identification of a wrong use of the boiler, the investigations were divided into two stages. In the first stage, the boiler was tested according to the PN-EN 303-5 standard using the manufacturer-recommended fuel. In the second stage of the investigations, an experiment was performed simulating a wrong use of the boiler burning waste material under actual conditions of operation. To this end, generally applied modifications in the boiler design were performed allowing the use of waste material as fuel. During the tests, the amount of oxygen O2 in the exhaust gas was monitored. It was observed that even slight attempt to operate the boiler incorrectly could be detected based on the analysis of the oxygen level in the exhaust gas.
Analysis of the anti-icing system used in air handling units with a counterflow heat exchanger
Authors: Jaszczur Marek , Kleszcz Sławosz , Borowski Marek
Published: July 2019

The present paper examines one of the most popular anti-icing solutions on the system performance. Different ratios of flowing fresh air to exhaust air were applied in order to heat the exchanger’s iced surface with warm air. The analysed system demonstrated that the system efficiency significantly dropped down under unfavourable conditions in winter. The results show that this type of solution is insufficient and should not be applied. A long operation with the iced surface can cause irreversible permanent damage to the heat exchanger unit and a serious system failure.
Analysis of Demand Side Response potential in energy clusters
Authors: Manujlo Andrzej , Kaleta Mariusz
Published: July 2019

The paper analyses the possibilities of Demand Side Response (DSR) applications from the point of view of an electricity power cluster. Three possible scenarios for DSR mechanisms that facilitate balancing the cluster in short horizon were formulated. Two scenarios include shifting a part of demand that creates unplanned balancing energy in the cluster. In the first scenario, the unplanned balancing energy is moved to hours with lowerprices on the Balancing Market (BM), while in second scenarios we assume that this energy is bought on the competitive market. The third scenario concerns mitigation of investment cost for local distributed resources (DERs) due to DSR program. We present an analysis of monetary savings that has been carried out for exemplary clusters in Polish electrical energy system and based on Polish Balancing Market and Power Exchange data. Although the potential savings per household are too small to create strong incentives for DSR, this amount of money could be notable for the local community as a whole. There is also a big opportunity for increasing the benefits resulting from DSR in case of perceived stronger differentiation of unbalanced prices on BM as well as strong trend for price increase. We believe that presented results may play an important role to draw the potential development directions for national power clusters.
The preparation of composite solid fuels in the roll press
Authors: Kosturkiewicz Bogdan , Janewicz Andrzej
Published: July 2019

Directive 2009/28/EC of the European Parliament and of the Council of 23 April 2009 on the promotion of the use of energy from renewable sources and amending and subsequently repealing Directives 2001/77/EC and 2003/30/EC, and the annex to resolution 202/2009 of the Council of Ministers of 10 November 2009 on the energy policy of Poland until up to 2030 indicate the necessity of increasing the contribution of renewable fuels in the energy balance of Poland. This increase is supposed to strengthen Polish energy security. The undertakings of the Polish government indicate the increase in utilisation of various renewable energy sources such as biomass. Due to that, new technologies connected with the management of the traditional energy sources, such as lignite, have to be developed. Due to its high moisture, lignite is perceived as a lowefficiency fuel. The calorific value of lignite can be improved upon by mixing it with biomass, e.g. sawdust, and briquetting it in roll presses equipped with asymmetrical layout compacting system. Such technology can be used only if the mixed ingredients are adequately prepared beforehand. Research in this field has been conducted in the Department of Manufacturing Systems AGH University of Science and Technology in Cracow. Based on this research, PW 500 roll press design was prepared. PW 500 roll press is prepared for briquetting composite solid fuels based on a mixture of lignite extracted in Szczerców and two types of biomass: oat straws and spruce sawdust. The results of the aforementioned briquetting are presented in this article.
Assessment of soil contamination by oil-derived compounds in the Kielce agglomeration using gas chromatography coupled with mass spectrometry (GC-MS)
Authors: Kmiecik Natalia , Jurek Krzysztof , Kowalski Adam
Published: July 2019

Soil contamination with petroleum-derived compounds is one of the most serious ecological problems. Their main source in urbanized areas is public transport. According to the Regulation of the Polish Minister of Environment about the assessment of earth’s surface contamination, hydrocarbon compounds are divided into: gasolines and oils, aromatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs). The subject of the research is the use of a gas chromatography coupled with mass spectrometry (GC-MS) method to assess the degree of soil contamination in the vicinity of the main communication routes of the Kielce agglomeration. This method is useful for the detection and identification of many organic compounds occurring in samples in very small quantities, which cannot be determined by common methods. For the purpose of this study, 14 soil samples were collected. After carrying out extraction with various methods, the ultrasonic solvent extraction method was chosen as the most effective way of extracting hydrocarbon impurities for the GC-MS studies. During single analysis, both oil fraction and PAHs quantities were determined.
Microspheres as potential fillers in composite polymeric materials
Authors: Magiera Anna , Kuźnia Monika , Jerzak Wojciech , Ziąbka Magdalena , Lach Radosław , Handke Bartosz
Published: July 2019

Microspheres used in our work were acquired from one of Kazakhstan coal-fueled power plant. The size of the microspheres varied between 45 and 400 μm, the median particle size (D50) was 158 μm. Microscopic analysis revealed that the material consisted mainly of cenospheres. The results of elemental and oxide analysis showed that microspheres were composed of aluminosilicates. Identified crystalline phases were mullite (approx. 12 %) and trace amount of quartz (silica). Microscopic observations of the cross-sectional surface of both unmodified PUR foam and foams modified with microspheres showed a well formed, cellular structure of all materials. The observed cells are polyhedron in shape, most of them are closed, microspheres were uniformly distributed within polymer matrix and placed between cells. The apparent densities calculations of the samples showed that when microspheres were added to the polymer matrix, apparent density of the resulting composite materials increased. The results of elemental analysis pointed out the highest content of all three elements in unmodified PUR foam sample. The addition of the microspheres to the system resulted in decrease of the concentration of all three elements.
Thermochemical energy storage – from fundamental research to TRL IV
Authors: Babiński Piotr , Kotyczka – Morańska Michalina , Zuwała Jarosław
Published: July 2019

The paper presents the results of the fundamental research devoted to the application of MgSO4 as a heat carrier for thermochemical seasonal storage system devoted for household application followed by the results of 35kWh storage tank (TRL IV) charging and discharging tests. Seasonal thermochemical heat storage, based on the reversible reactions of hydratation and dehydratation of a solid medium gives an opportunity to accumulate the energy with a storage capacity exceeding 300-400 kWh/m3.
Comparison of CO2 gasification of coal in isothermal and non-isothermal conditions
Authors: Czerski Grzegorz , Grzywacz Przemysław , Śpiewak Katarzyna
Published: July 2019

The thermogravimetric method allows to carry out measurements both in isothermal conditions for a given temperature and in non-isothermal conditions at a set heating rate. The aim of the work was to compare the process of gasification of the same coal in an atmosphere of CO2 under isothermal and non-isothermal conditions. The measurements were carried out with the use of DynTHERM Thermogravimetric analyzer by Rubotherm. Char derived from Polish bituminous coal “Janina” was used as material for gasification. In case of the isothermal method the measurements were performed at three temperatures – 850 °C, 900 °C and 950 °C, while in case of the non-isothermal method for three heating rates, i.e. 3 K/min, 5 K/min and 10 K/min. Based on the results obtained, kinetics curves of conversion degree of the gasification process were developed and kinetic parameters of the gasification reaction i.e. reaction order, activation energy and pre-exponential factor were determined. The values of the kinetic parameters obtained from measurements performed in isothermal and non-isothermal conditions were compared.
The application of modified cenospheres in DeNOx process
Authors: Samojeden Bogdan , Grzybek Teresa , Szymaszek Agnieszka , Ligęza Oliwia , Kowalczyk Wioletta , Motak Monika
Published: July 2019

Cenospheres were modified with iron, manganese and/or copper ions by the hydrotalcite method. The obtained catalysts were characterized by FTIR, XRD and low-temperature nitrogen sorption. The best catalyst at low temperature (200 °C) was CBFe-Mn while at the highest measured temperature of 500 °C both CBFe-Mn and CBMn-Cu showed similar performance.
Migraine : données épidémiologiques, cliniques et thérapeutiques
Authors: Roos Caroline
Published: July 2019

La migraine a une prévalence estimée entre 10 et 14 %, elle est donc la pathologie neurologique la plus fréquente. Elle concerne une population jeune, dont deux tiers de femmes, et son impact en termes économiques est essentiellement en lien avec les coûts indirects. La migraine peut être épisodique ou chronique en fonction de la fréquence de jours de céphalée (≥ 15 jours par mois). Le diagnostic est posé à l’interrogatoire selon des critères internationaux. La migraine s’explique par une activation du système dit trigéminocervical, avec libération en cascade de neuromédiateurs participant à l’inflammation neurogène et l’activation des neurones de second ordre. La migraine avec aura se manifeste par des symptômes neurologiques, évoluant lors de la marche migraineuse, d’une durée de moins de 60 minutes, expliqués par le phénomène de dépolarisation corticale envahissante. Le traitement comporte deux axes : le traitement de crise par un anti-inflammatoire non stéroïdien (AINS) ou un triptan, et le traitement de fond prescrit au cas par cas, les molécules de première intention selon les recommandations françaises étant les bêta-bloquants, puis en cas d’échec, le topiramate, l’oxétorone ou l’amitriptyline.
Mécanismes de régulation cérébrale impliqués dans la crise migraineuse
Authors: Bourgeais-Rambur Laurence , Beynac Laurianne , Villanueva Luis
Published: July 2019

L’aura migraineuse ainsi que le manque d’habituation aux stimuli hétéro-sensoriels suggèrent l’implication du cortex cérébral dans la pathogenèse migraineuse. D’autre part, les signes prémonitoires couramment observés chez les migraineux, tels que les perturbations du cycle veille-sommeil et les modifications de l’humeur, sont liés à une régulation hypothalamique. Nos études effectuées chez le rat ont permis de mettre en évidence plusieurs mécanismes de plasticité dysfonctionnelle au sein du tronc cérébral, de l’hypothalamus et du cortex cérébral à l’origine des céphalées migraineuses et algies vasculaires de la face. Une meilleure connaissance de ces mécanismes constitue un préalable nécessaire pour la mise en œuvre de nouvelles stratégies thérapeutiques dépourvues d’effets secondaires et/ou à visée prophylactique.
Effect of specimen bed on the material removal due to the repetitive single ball impacts
Authors: Akhondizadeh Mehdi , Atashafrooz Meysam
Published: July 2019

Specimen wear due to the repetitive single ball impact is investigated experimentally by a drop test machine. Effect of the impact energy, incidence angle and bed material is studied. Specimen mass loss is measured after 1000 impacts. The crater dimension on the specimen surface is measured to indicate its correlation with the wear variation. Results show that the rubber bed has the undeniable positive role in decrement of the wear due to impact comparing with the steel bed. A relation between the energies which give the same wear, in both cases of the rubber and steel bed, is extracted. Results can be helpful in designing the appropriate bed where the medium and high energy impacts encouraged.