bluuebunny/crossref_metadata_2025 huggingface dataset:
Toll‐like receptor 9 expression in mucoepidermoid salivary gland carcinoma may associate with good prognosis
Authors: Korvala Johanna , Harjula Teresa , Siirilä Kristiina , Almangush Alhadi , Aro Katri , Mäkitie Antti A. , Grénman Reidar , Karttunen Tuomo J. , Leivo Ilmo , Kauppila Joonas H. , Salo Tuula
Published: February 2014

Background

Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy. Although several biomarkers have been evaluated, histological grade remains the most valuable prognostic marker. Toll‐like receptor 9 (TLR9) is an immune receptor recognizing microbial DNA. Its expression associates with prognosis or cancer properties in several cancers. This study examined the role of TLR9 in MEC.

Methods

Sixty patients with salivary gland MEC were collected from two Finnish university hospitals, and tumor samples were stained for TLR9. Salivary gland high‐grade MEC cell line (UT‐MUC‐1) was cultured to assess TLR9 and MMP‐13 expression. The function of TLR9 was studied in vitro using traditional Matrigel® invasion assay and novel human myoma organotypic model.

Results

Cancer‐specific survival was related with tumor grade (P = 0.01), and there were no deaths in patients with low‐grade MEC. TLR9 was expressed in 56 of 60 (93%) tumors. High TLR9 expression indicated better survival in the patient series (P = 0.002) and showed a trend for association with lower disease stage (P = 0.06) and higher differentiation grade (P = 0.068). In multivariate analysis, TLR9 expression was prognostically insignificant due to heavy correlation to disease stage and higher gradus. Treating UT‐MUC‐1 cells with TLR9 ligand CpG in vitro induced MMP‐13 expression and invasion in Matrigel® invasion assay, whereas decreased invasion was seen in myoma organotypic model.

Conclusion

Functional TLR9 is present in salivary MEC, and high level of expression may indicate good prognosis. However, more studies are needed to evaluate biological consequences of TLR9 interaction in tumor cells.
Absence of matrix‐like chondrule rims in CR2 LAP 02342
Authors: Wasson John T. , Rubin Alan E.
Published: February 2014

In numerous past papers, it was concluded that the fine (<1 μm) matrix immediately adjacent to, and radially symmetric around, chondrules in primitive chondrites consists of compact (low‐porosity) rims that were attached in the solar nebula. We present here textural and compositional evidence that no matrix‐like (or accretionary) rims around chondrules are present in the well‐preserved CR2 chondrite LAP 02342. Fine‐grained matrix‐rich regions (i.e., candidate “rims”) at the edges of chondrules were studied with an electron‐microprobe‐based matrix‐grid technique; comparison of the “rims” data for matrix regions near these chondrules showed the candidate “rims” to be compositionally heterogeneous, inconsistent with origins as radially symmetric, matrix‐like rims formed by gradual accretion. This evidence (together with simulations and laboratory studies indicating that accretionary processes produced highly porous aggregates) strongly suggests that nebular processes did not produce compact matrix‐like rims around chondrules in any chondrite group.
Inhibition of autophagy enhances the effects of the AKT inhibitor MK‐2206 when combined with paclitaxel and carboplatin in BRAF wild‐type melanoma
Authors: Rebecca Vito W. , Massaro Renato R. , Fedorenko Inna V. , Sondak Vernon K. , Anderson Alexander R. A. , Kim Eunjung , Amaravadi Ravi K. , Maria‐Engler Silvya S. , Messina Jane L. , Gibney Geoffrey T. , Kudchadkar Ragini R. , Smalley Keiran S. M.
Published: February 2014

This study investigates the mechanism of action behind the long‐term responses (12–16 months) of two BRAF WT melanoma patients to the AKT inhibitor MK‐2206 in combination with paclitaxel and carboplatin. Although single agent MK‐2206 inhibited phospho‐AKT signaling, it did not impact in vitro melanoma growth or survival. The combination of MK‐2206 with paclitaxel and carboplatin was cytotoxic in long‐term colony formation and 3D spheroid assays, and induced autophagy. Autophagy was initially protective with autophagy inhibitors and deletion of ATG5 found to enhance cytotoxicity. Although prolonged autophagy induction (>6 days) led to caspase‐dependent apoptosis, drug resistant clones still emerged. Autophagy inhibition enhanced the cell death response through reactive oxygen species and could be reversed by anti‐oxidants. We demonstrate for the first time that AKT inhibition in combination with chemotherapy may have clinical activity in BRAF WT melanoma and show that an autophagy inhibitor may prevent resistance to these drugs.
Detecting changes in biomass productivity in a different land management regimes in drylands using satellite‐derived vegetation index
Authors: Helman D. , Mussery A. , Lensky I. M. , Leu S.
Published: February 2014

We investigated the use of a satellite‐derived vegetation index to detect changes in biomass productivity in different land management regimes in drylands of the Northern Negev. Two well‐documented management regimes, conservation and afforestation using a contour trenching technique were monitored. Biomass data on annual vegetation were collected from field survey and compared to a time series of the Normalized Difference Vegetation Index (NDVI). A significant relationship between NDVI and biomass (r = 0.83, P < 0.01) confirmed the applicability of satellite information to monitoring biomass production in this low productivity area. However, a strong positive relationship between NDVI and precipitation (r = 0.96 ± 0.01, P < 0.001) prevented the conventional use of trend analysis to detect changes in biomass productivity. Trends in the NDVI and precipitation use efficiency were similar in both sites due to a rainfall effect. Use of a reference site revealed the magnitude and direction of change in biomass productivity in the different land management regimes. Measures of soil organic matter confirmed these differences between the two managed sites and the reference site. We suggest that the use of abandoned lands for a reference may enhance the ability to detect changes in biomass productivity in drylands.
On the Combined Effect on Operating Range of Adjustable Inlet Guide Vanes and Variable Speed in Process Multistage Centrifugal Compressors
Authors: Scotti Del Greco Alberto , Tapinassi Libero
Published: February 2014

Adjustable inlet guide vanes (IGVs) and variable speed drivers are known as providing process compressors with an effective regulation all throughout the operating envelope of the machine. A large amount of work exists in literature reporting the successful control of multistage centrifugal compressors by means of IGVs or speed separately, while a few studies document the combined use of both devices and their effect on compressor performance. The present paper details the off-design behavior of a multistage centrifugal compressor equipped with both types of control. It is shown that classical IGVs' advantage in extending the operating envelope of a fixed speed multistage compressor tends to reduce when speed regulation is active too. In this sense, the average level of peripheral Mach numbers inside the compressor may be interpreted as a sort of threshold since it deeply affects the stage mismatching at off-design conditions. This consideration is corroborated by a number of applications in a wide range of design peripheral Mach numbers. Based on those cases, the paper reviews the general effectiveness of the combined regulation, thus outlining some general rules of thumb for the choice of the optimal control device for a multistage centrifugal compressor.
Analysis of Drying and Dilution in Phosphoric Acid Fuel Cell (PAFC) Using Galvanometric Study and Electrochemical Impedance Spectroscopy
Authors: Paul Tanmoy , Seal Mrinal , Banerjee Dipali , Ganguly Saibal , Kargupta Kajari , Sandilya Pavitra
Published: February 2014

Different experimental and analytical techniques namely steady state galvanometric study and electrochemical impedance spectroscopy (EIS) are employed to generate rule sets for identification of the acid drying and dilution phenomena in a phosphoric acid fuel cell (PAFC). The slope of steady state current versus voltage is used as a performance marker. A new parameter Δ, which signifies the net moisture transport in PAFC, is introduced and evaluated from the experimental data to locate the regimes of electrolyte dilution and drying. Based on these two parameters, the performance of a PAFC is mapped on the plane of operating variables. Performance decay at higher cell temperature and lower humidifier temperature (below 60 °C) signifies acid drying; on the contrary the same at lower cell temperature and higher humidifier temperature is attributed to acid dilution. EIS is employed by imposing a sinusoidal potential excitation on steady state DC load and the shift of maximum phase angle position in the frequency spectrum is used as a diagnostic marker. Results show absence of peak in the domain of positive frequency for acid drying condition, while acid dilution causes the peak to be shifted at higher frequency value. Electrochemical timescales estimated from EIS increases by many order of magnitudes compared to that in a normal PAFC, when electrolyte drying occurs. The results obtained from EIS analysis are in agreement with the performance mapping based on galvanometric steady analysis. The results are significant in context of water management and humidity control in a PAFC. The tools and parameters introduced in the present publication show promising potential to map the performance and SOH of a PAFC on the plane of various operating variables. Results and logics revealed are of significance in development of inferential model for the online optimization of PAFC.
Investigation of Hydrodynamics and Heat Transfer Effects Due to Light Guides in a Column Photobioreactor
Authors: Gerdes Caitlin R. , Suess Taylor N. , Anderson Gary A. , Gent Stephen P.
Published: February 2014

The objective of this research is to predict how the placement of structural light guides within a column photobioreactor (PBR) affects the fluid mechanics and heat transfer of the system. The photobioreactor studied is modeled and analyzed using computational fluid dynamics (CFD). A bubble sparger provides carbon dioxide and mixing. Five different arrays and eight carbon dioxide volumetric flow rates are tested. Based on this setup, the bubble flow patterns, velocities, and temperature distributions are analyzed and the recommended placement of light guides is determined for predicting the growing conditions suitable for microalgae and other photosynthetic organisms.
Utilization of Pore-Size Distributions to Predict Thermophysical Properties and Performance of Biporous Wick Evaporators
Authors: Reilly Sean W. , Catton Ivan
Published: February 2014

A sintered copper porous medium is an extremely effective structure used to enhance the evaporative heat transfer properties of a heat pipe. It provides both capillary pressure to passively draw liquid in and increased surface area to more effectively heat the liquid. A biporous wick is particularly effective for this application as there are two distinct size distributions of pores; small pores to provide ample capillary pressure to drive flow through the wick and large pores to provide high permeability for escaping vapor. The modeling described in this work is based on the work of Kovalev who used a pore size distribution in order to determine the most probable liquid saturation at a given position. The model distinguishes phases by choosing a “cutoff” pore size, where larger pores were assumed to be filled with vapor and smaller pores were assumed to be filled with liquid. For a given thickness and thermophysical properties of the liquid, this 1-D model predicts the temperature difference across the wick for a given input power. The modeling proposed in this work yielded results that compare very well with experimental data collected on biporous evaporators by Semenic.
A Model for the Prediction of Thermal Response of Bone in Surgical Drilling
Authors: Maani Nazanin , Farhang Kambiz , Hodaei Mohammad
Published: February 2014

This paper develops a mathematical model for predicting the thermal response in the surgical drilling of bone. The model accounts for the bone, chip, and drill bit interactions by providing a detailed account of events within a cylindrical control volume enveloping the drill, the cut bone chip within the drill bit flute, and the solid bone. Lumped parameter approach divides the control volume into a number of cells, and cells within the subvolumes representing the drill solid, the bone chip, and the bone solid are allowed to interact. The contact mechanics of rough surfaces is used to model chip–flute and chip–bone frictional interaction. In this way, not only the quantification of friction due to sliding contact of chip–flute and chip–bone rough surface contact is treated but also the contact thermal resistances between the rubbing surfaces are included in the model. A mixed combination of constant and adaptive mesh is employed to permit the simulation of the heat transfer as the drill bit penetrates deeper into the bone during a drilling process. Using the model, the effect of various parameters on the temperature rise in bone, drill, and the chip is investigated. It is found that maximum temperature within the bone occurs at the location adjacent to the corner of the drill-tip and drill body. The results of the model are found to agree favorably with the experimental measurements reported within the existing literature on surgical drilling.
Hygrothermal Behavior of Advanced Polymers Above Water Boiling Temperatures
Authors: Jang Changsoo , Han Bongtae
Published: February 2014

Hygroscopic and thermal expansion behavior of advanced polymers is investigated when subjected to combined high temperature and moisture conditions. An enhanced experimental–numerical hybrid procedure is proposed to overcome the limitations of the existing methods when used at temperatures above the water boiling temperature. The proposed procedure is implemented to measure the hygrothermal strains of three epoxy molding compounds and a no-filler underfill over a wide range of temperatures including temperatures beyond the water boiling temperature. The effects of moisture content on the glass transition temperature (Tg) and coefficient of thermal expansion (CTE) are evaluated from the measurement data. A formulation to predict the Tg change as a function of moisture content is also presented.
Actuation Torque Reduction in Parallel Robots Using Joint Compliance
Authors: Borràs Júlia , Dollar Aaron M.
Published: February 2014

This work studies in detail how the judicial application of compliance in parallel manipulators can produce manipulators that require significantly lower actuator effort within a range of desired operating conditions. We propose a framework that uses the Jacobian matrices of redundant parallel manipulators to consider the influence of compliance both in parallel with the actuated joints as well as the passive joints, greatly simplifying previous approaches. We also propose a simple optimization procedure to maximize the motor force reduction for desired regions of the workspace and range of external forces. We then apply the method to a Stewart-Gough platform and to a 3-URS (universal rotational and spherical joint) manipulator. Our results show that parallel manipulators with tasks that involve a preferred external force direction, as for instance, big weights in the platform, can see large reductions in actuator effort through the judicial use of compliant joints without significantly losing rigidity.
An Experimental Powered Lower Limb Prosthesis Using Proportional Myoelectric Control
Authors: Huang Stephanie , Wensman Jeffrey P. , Ferris Daniel P.
Published: February 2014

One way to provide powered lower limb prostheses with greater adaptability to a wearer's intent is to use a neural signal to provide feedforward control of prosthesis mechanics. We designed and tested the feasibility of an experimental powered ankle-foot prosthesis that uses pneumatic artificial muscles and proportional myoelectric control to vary ankle mechanics during walking. The force output of the artificial plantar flexor muscles was directly proportional to the subject's residual gastrocnemius muscle activity. The maximum force generated by a pair of artificial muscles fixed at nominal length was 3513 N. The maximum planter flexion torque that could be generated during walking was 176 Nm. The force bandwidth of the pneumatic artificial muscles was 2 Hz. The electromechanical delay was 33 ms, the time to peak tension was 48 ms, and the half relaxation time was 50 ms. We used two artificial muscles as dorsiflexors and two artificial muscles as plantar flexors. The prosthetic ankle had 25 deg of dorsiflexion and 35 deg of plantar flexion with the artificial muscles uninflated. The intent of the device was not to create a commercially viable prosthesis but to have a laboratory prototype to test principles of locomotor adaptation and biomechanics. We recruited one unilateral transtibial amputee to walk on a treadmill at 1.0 m/s while wearing the powered prosthesis. We recorded muscle activity within the subject's prescribed prosthetic socket using surface electrodes. The controller was active throughout the entire gait cycle and did not rely on detection of gait phases. The amputee subject quickly adapted to the powered prosthesis and walked with a functional gait. The subject generated peak ankle power at push off that was similar between amputated and prosthetic sides. Our results suggest that amputees can use their residual muscles for proportional myoelectric control to alter prosthetic mechanics during walking.
A Multi-Objective Optimization Approach to Active Power Control of Wind Farm
Authors: Zou Jianxiao , Yao Junping , Zou Qingze , Xu Hongbing , Zhang Zhenzhen
Published: February 2014

With more and more wind farms integrated into the power grid, the stability and security of the grid can be significantly affected by the wind-farm-generated power, due to the intermittent and volatile nature of the wind-farm-generated power. Therefore, control of the wind-farm power to meet the stability and quality requirements becomes important. Active control of wind-farm power, however, is challenging because the wind-farm output power can only be reliably predicted for a short period of time (i.e., ultrashort term power prediction), and large variations exist in the wind-turbine output power. In this paper, an optimal active power control scheme is proposed to maximize the running time of each wind turbine, and minimize the on-and/or-off switching of wind turbines, resulting in substantial reduction of wind-turbine wear and thereby, maintenance cost, and extension of wind-turbine lifetime, all together, a significant saving of operation cost of the whole wind farm. The proposed approach is illustrated by implementing it to the active power allocation of a wind-farm model in simulation.
Investigation of a Hybrid Photovoltaic-Biomass System With Energy Storage Options
Authors: Hosseini Mehdi , Dincer Ibrahim , Rosen Marc A.
Published: February 2014

A hybrid photovoltaic (PV)-biomass system with energy storage options is investigated based on energy and exergy analyses. The hybrid system consists of a photovoltaic system, an electrolyser, and a biomass gasifier, which is integrated with a biomass-based gas turbine. The PV system is accountable for 56% of the annual exergy destruction in the hybrid system, while 38% of the annual exergy destruction occurs in the biomass-gas turbine (GT) system. The overall energy and exergy efficiencies of the hybrid PV-biomass system with energy storage options are 34.8% and 34.1%, respectively. A 29% increase in both energy and exergy efficiencies is reported with an increase in the steam-to-carbon ratio (SC) in the range of 1–3 mol/mol. The related specific carbon dioxide emission reduction is 1441–583 g/kWh. In contrast to SC, an increase in gas turbine inlet temperature results in a negative effect on the overall energy and exergy efficiencies, and it does not make a significant contribution to the reduction in specific carbon dioxide emission.
Rectal schwannoma on endoscopic polypectomy
Authors: Baskaran Vadsala , Cho Wai Sum , Perry Michael
Published: February 2014

Conventional gastrointestinal schwannomas are rare, most frequently occurring in the stomach while colorectal locations are uncommon and only a small number of cases have been reported. We are reporting this case as it is a very rare tumour at a very rare location. Though schwannomas are considered benign neoplasms, rare cases of malignant schwannoma have been reported. Owing to the uncertainty of the prognosis, our patient is under long-term endoscopic surveillance.
An unusual case of ectodermal dysplasia: combating senile features at an early age
Authors: Gupta Mudit , Sundaresh Kumbar Jayadevappa , Batra Manu , Rathva Vandana J
Published: February 2014

Ectodermal dysplasia (ED) refers to a group of inherited diseases that have developmental defects in at least two major structures derived from the ectoderm, that is, hair, teeth, nails and sweat glands. Although more than 192 distinct disorders have been described, the most common is X-linked recessive hypohidrotic ED (Christ-Siemens-Touraine syndrome). Since such patients usually presents with missing teeth, dentists are usually the first person to diagnose such cases. Diagnosis of such cases is important because absence of sweat glands can lead to hyperthermia which can be life-threatening if proper care is not taken. Through this manuscript, we report a case of anhidrotic ED affecting deciduous and permanent dentition, which is rare.
Ventricular fibrillation due to coronary vasospasm
Authors: Naqvi Syed Yaseen , Hanley Alan , Crowley James
Published: February 2014

A 43-year-old woman developed a sudden-onset severe chest pain and breathlessness at home. She collapsed within minutes and received bystander cardiopulmonary resuscitation from her husband. On arrival, the paramedics identified ventricular fibrillation requiring defibrillation. She was admitted to the intensive care unit for observation. A coronary angiogram performed at our hospital demonstrated non-obstructive disease of the right coronary artery. Her antidepressant medications were discontinued and she was discharged. No specific cause was found for the arrhythmia and collapse. One week later, she developed similar chest pain. An ECG showed transient ST-elevation in the inferior leads. Symptoms and ECG changes resolved with sublingual nitroglycerin. During the course of a repeat coronary angiogram the patient developed severe spasm of the right coronary artery associated with typical chest pain and ST-elevation in the inferior leads. She was treated with insertion of a drug-eluting stent and a cardiac defibrillator.
Synthesis, structure, and properties of the hexagermane Pri3Ge(GePh2)4GePri3
Authors: Roewe Kimberly D. , Golen James A. , Rheingold Arnold L. , Weinert Charles S.
Published: February 2014

The synthesis of the hexagermane Pri3Ge(GePh2)4GePri3 was achieved starting from the cyclotetragermane (Ph2Ge)4. Ring-opening of (Ph2Ge)4 with Br2 yielded Br(GePh2)4Br that was converted to H(GePh2)4H, and this material was treated with two equiv. of Pri3GeNMe2 to furnish Pri3Ge(GePh2)4GePri3 via the hydrogermolysis reaction. The X-ray crystal structures of (Ph2Ge)4, Br(GePh2)4Br and Pri3Ge(GePh2)4GePri3 were determined. The hexagermane Pri3Ge(GePh2)4GePri3 represents the longest structurally characterized linear oligogermane reported to date and exhibits physical properties that resemble those of the larger polygermane systems. The hexagermane is luminescent and interacts with polarized light, appearing pale yellow under one orientation of polarized light and deep blue under the opposite orientation. The electrochemistry of Pri3Ge(GePh2)4GePri3 was also explored, and this species exhibits the expected five irreversible oxidation waves.
The mean crystallite size within a hydrogenated nanocrystalline silicon based photovoltaic solar cell and its role in determining the corresponding crystalline volume fraction
Authors: Schmidt K.J. , Lin Y. , Beaudoin M. , Xia G. , O’Leary S.K. , Yue G. , Yan B.
Published: February 2014

We examine the dependence of the crystalline volume fraction on the mean crystallite size for hydrogenated nanocrystalline silicon based photovoltaic solar cells; this work builds upon an earlier study by Schmidt et al. (Mater. Res. Soc. Symp. Proc. 1536 (2013)). For each photovoltaic solar cell considered, the X-ray diffraction and Raman spectra are measured. Through the application of Scherrer’s equation, the X-ray diffraction results are used to determine the corresponding mean crystallite sizes. Through peak decomposition, the Raman results are used to estimate the corresponding crystalline volume fraction. Plotting the crystalline volume fraction as a function of the mean crystallite size, it is found that larger mean crystallite sizes tend to favor reduced crystalline volume fractions. The ability to randomly pack smaller crystallites with a greater packing fraction than their larger counterparts was suggested as a possible explanation for this observation.
Measurement of Impedance Changes of Porous Ni(OH)2 Electrodes at Different State of Charge
Authors: Chladil Ladislav , Dvořák Petr
Published: February 2014

Nickel hydroxide is the typical material for positive electrodes of alkali accumulators. This material is known for its big changes of electron conductivity in different state of charge. The article is focused on measurement impedance of Ni(OH)2 pocket electrode in different state od charge by using electrochemical impedance spectroscopy (EIS) technique.
Electrochemical Deposition of Tin and Silicon Studied by EQCM
Authors: Kavalek Ondrej , Vondrak Jiri , Sedlarikova Marie
Published: February 2014

Silicon and Tin thin films were prepared by electrochemical deposition on copper and nickel substrates in the Atmosbag. Electrochemical activity is described by cyclic voltammetry and for studying increase of weight were used EQCM. Deposited layers were studied by optic microscopy, electron microscopy and X-ray diffraction.
Reuse of Recycled Solar Cells
Authors: Šimonová Lucie , Vaněk J. , Demchikhin Sergey
Published: February 2014

Recycle of old and damaged solar panels is becoming more discussed topic. Therefore, we focused on the thermal and chemical recycling of photovoltaic modules, their advantages and disadvantages. Methods which are required for removing residual impurities from the surface of obtained article are an integral part of the recycling. We examined if we can use these cells to manufacture new solar panels. We also focused on the economic and environmental conditions of the process.
Electrochemical Impedance Spectroscopy – Just One of Many Tools to Study Batteries and Power Sources
Authors: Vanýsek Petr
Published: February 2014

Electrochemical Impedance Spectroscopy (EIS) is one of the many methods available to the researcher in electrochemistry. To take full advantage of its capabilities, one should understand the method and the underlying principles. In this work voltammetry on a stationary electrode, as well as with a rotated disk electrode (RDE) are presented together with EIS results, exemplified by reduction and oxidation of vanadium salts in 3 mol/l sulfuric acid. This contribution summarizes highlights, but also pitfalls of impedance measurements and their interpretation, as they are relevant to the practice and theory of electrochemical work. The most significant component in the equivalent circuit is the change transfer resistance, which matches well the voltammetric curves of the RDE experiment. A high-frequency artifact can be eliminated by formally fitting it to an inductor and resistor of series; both of these components have, however, negative value.
Laplace’s Pressure Induced Rhombohedral Phase in the Scandia-Stabilized Zirconia Ceramics
Authors: Barbashov Vladimir , Nesova Elizaveta , Pismenova Natalia
Published: February 2014

Grain-size effect on the conductivity and phase composition ofscandia stabilized zirconia ceramics produced from DKKK(Japan) powder with composition 89 mol.% ZrO2 + 10 mol. %Sc2O3 + 1 mol. % CeO2 was established. It was shown using Xrayphase analysis that decreasing the grain size of ceramics from 16 to 0.6 mkm leads in formation of rhombohedral phase. For finegrained material, anisotropic properties of material are fixed clearly in Arrhenius plots of ionic conductivity.
Comparism of Membranes Based on PVA with Commercial Produced Membranes
Authors: Subarda Jiri , Novak Vitezslav , Kunovjanek Miroslav , Musil Michal
Published: February 2014

PVA membrane types are very siutable for application in fuel cells. These embody good properties and humidify abilities at higher temperatures. At temperature about 100 °C these membrane types have an optimal voltage-ampere and power charcteristics. In this paper are described experimental preparation and conductivity measurements of polyvinyl alcohol (PVA) polymer electrolyte membranes. This type of membranes and commercially produced membranes are measured in low temperature polymer electrolyte membrane (PEM) fuel cell Quintech. Fundamental characteristics (e. g. volt-ampere and power characteristics) of fuel cells containing PVA membranes and commercial produced membranes were compared
A Numerical Study on the Effects of Gas Channel Wettability in PEM Fuel Cells
Authors: Alrahmani Mosab , Chen Rui , Ibrahim Salah , Patel Samir
Published: February 2014

The wettability of channel walls and gas diffusion layer has a great influence on the water management of fuel cells. In this paper, a numerical study has been carried out to examine the effect of the wall and gas diffusion layer wettability on gas channels. The investigation employed a three dimensional numerical simulation using the volume-of-fluid (VOF) method to simulate the air-water flow in a straight micro-channel representing a gas channel in a PEM fuel cell. Nine combinations of wall and GDL wettabilities were investigated. Different wettability combinations were found to give different water behaviour. For fixed wall wettability, the pattern of the analysed parameters was changing between uniform cyclic, random cyclic and continuous. In addition, it was found that changing the GDL wettability has a greater impact on the analysed parameter compared to changing the wall wettability.
The Impacts of Image Resolution on Permeability Simulation of Gas Diffusion Layer Using Lattice Boltzmann Method
Authors: Jinuntuya Fontip , Chen Rui , Ostadi Hossein , Jiang Kyle , Gao Yuan , Zhang Xiaoxian
Published: February 2014

The effect of image resolution on gas permeability through the x-ray reconstructed carbon paper gas diffusion layer (GDL) of a polymer electrolyte fuel cell (PEFC) was examined in this paper. The 3D models of the GDL at 6 different resolutions were obtained by the x-ray computed tomography imaging technique. Each GDL image was then characterized its gas permeability through the lattice Boltzmann (LB) numerical method. The results suggest that the image resolution has a great impact on gas permeability in both principal and off-principal flow directions. The coarser resolutions can contribute to significant changes in the resulting permeability. However, it can reduce calculation time to a great extent. The results also indicate that the GDL image at the resolution of 2.72 mm provides a good compromise between computation time and accuracy.
TiO2 Nanorods for Lithium-Ion Anodes
Authors: Cech Ondrej , Kovar P. , Sedlarikova Marie , Vondrak Jiri
Published: February 2014

This work deals with TiO2 based anode material for lithium-ion secondary batteries. The aims of this study is to synthetize and characterize TiO2 - nanorod based active anode material using up scalable process with just slightly modified synthesis method commonly used for production of this type material. Low temperature treatment of raw samples was made and structural and electrochemical properties in correlation with treatment temperature were investigated. Using of these substances as promising li-ion anode materials was successfully tested by charge-discharge cycling and structural characterization by XRD and SEM was made.
Comparison of the Characteristics of LixMn2O4 Synthesized by Microwave and Solid-State Methods
Authors: Globa Nataliy I. , Shmatok Yury V. , Prisyazhnyi Vitaliy D.
Published: February 2014

LixMn2O4 obtained by using microwave method has been investigated as cathode material. TG analysis showed that the microwave method can be used to obtain the LiMn2O4 precursor. The lattice parameters and crystallite size were established by XRD method. The obtained value correlates well with the known literature data. The specific capacity of LiMn2O4 was 120 mAh/g and was stable in cycling at a current rate of 1C.
Performance of LiFePO4/C and Carbon Fibers Composite as Cathodes in Lithium-Ion Batteries and Battery Modeling
Authors: Thomas Jorge , Castro Elida Beatriz , Milocco Ruben , Sedlarikova Marie , Visintin Arnaldo
Published: February 2014

Currently, the cathode material LiFePO4/C is the most promising active material for high-power lithium-ion batteries for electric vehicle applications and it has been observed that its response is also dependent on the nature of the carbon used as support. This paper presents the preliminary results from the synthesis of LiFePO4 supported on carbon fibers where phosphate and fibers are synthesized together at a single stage. The electrodes built with this material have a good electrochemical response with the typical behavior of LiFePO4. In addition, the behavior of these materials has been characterized from the viewpoint of the electrochemistry of charge/discharge processes in order to provide knowledge for the global modelling of batteries. A Battery Management System (BMS) is also currently being developed in order to control the operating conditions and the state of charge of Li-ion batteries. The development of a BMS requires an adequate modeling of the dynamic accumulation processes taking place in the battery. A general model has been derived and validated in terms of the experimental performance of a Li-ion battery and some results are presented below.
Use of Dimethyl Sulfone as Additive in Aprotic Electrolytes
Authors: Máca Josef , Vondrák Jiri , Sedlaříková Marie
Published: February 2014

The aim of this work is to determination the influence of dimethyl sulfone on electrical properties of electrolytes. Dimethyl sulfone is an adjacent product by many chemical manufactories. The key thought of this article is to find a possibility to use of this adjacent product. In this work is dimethyl sulfone used as additive into commonly applied solvents that are used for aprotic electrolytes. There will be established properties in low flammable solvent such as sulfolane too. The article will discussed specific conductivity of this solvents mixtures.
Enhanced Capacity and Safety of Lithium-Ion Accumulators
Authors: Sedlaríková Marie , Vondrák J. , Libich J. , Dvořák Otto , Buřičová Hana
Published: February 2014

This paper is based on a research of negative materials for lithium-ion accumulators. In the research are considered manufacturing methods, which can lead to enhance capacity of lithium-ion accumulators along with improving their safety. In the first part of our research we prepared specific improved materials for negative electrode. These materials should be able to reduce or completely remove the irreversible capacity of lithium-ion accumulators. Electrode materials were made by lithiation process with help of n-butyllithium reagent. In this way prepared materials already contain the lithium ions, the Li, which were intercalated to materials. For experimental purposes were chosen commonly used graphite materials, the natural graphite and expanded graphite. The second part of this study is focused on safety testing of various lithiated materials. These tests were performed on STA i1500 device, this device offers two analyses TG and DCS; analyses are based on the changes of temperature.
I-V Characteristic Measurement of Solar Cell
Authors: Vanek Jiri , Kaderka Tomasz
Published: February 2014

This paper deals with creating a workplace for automatic measurement of I-V characteristics of photovoltaic cells in the LabVIEW. Challenge is to create a functional program, which automatically measures the I-V characteristics not only in the lighted cells, but also in the shaded cell (diode mode). The program calculates the power and important parameters, such as short-circuit current, open circuit voltage, maximum power, current and voltage at maximum power article. The program allows you to export the measured values to a text file. In the last chapter of this work is made control measurements of three samples of monocrystal photovoltaic cell by the measuring workplace. The measurement is compared with the reference device Solar Cell Tester.
Usage of the Fuel Cell-Powered Electric Drive in Aviation
Authors: Prochazka Petr , Pazdera Ivo , Bencalik Karol
Published: February 2014

Weight and consumed space of the fuel cell systems are one of the most important factors limiting its utilization in electric airplanes. Possibilities of its implementation in electric airplane are frequently discussed issues. Power – mass relationship depending on installed power of the fuel cell shows, that the power/mass ratio is unsatisfactory, when powering electric motor directly from fuel cell. Configuration with high-power small-capacity battery and relatively small fuel cell is more profitable. Some calculations were done for functional prototype of the small airplane VUT 051 RAY, its take-off weight is about 600 kg and its max. power is 55 kW. There are some practical measurements on the Ballard fuel cell system presented in this paper, which can documents disputableness of its usage in airplane. Hydrogen management (hydrogen tank, cooling system, armatures etc.) still represents outstanding issue due to high volumes and weight of the whole fuel cell system. Current progress in the field of the Li-Ion accumulators, generally decreases importance of hydrogen-drive systems and focuses more attention to simply accumulator powered airplane.
Battery System for the Airplane VUT 051 RAY
Authors: Cipin Radoslav , Kadlec Josef , Klima Bohumil , Hutak Petr
Published: February 2014

This paper deals with battery monitoring system for the airplane VUT 051 RAY and description of the whole airplane battery. The whole battery for airplane consists of 3060 Li-ion cells Panasonic NCR18650A. These cells are separately installed into 30 battery packs, which are connected in series. Nominal parameters of the whole battery are 324 V, 102 Ah and maximal current 204 A. In this article, there are shown some detail of installation of the battery in the airplane and some tests.
Impact of Fast-Chargers for Traction Batteries on Distribution Network
Authors: Červinka Dalibor , Vorel Pavel
Published: February 2014

High-power converters with high frequency pulse transformers are used in fast-chargers for electric vehicles to decrease their size and price. These converters and their input rectifiers have significant impact on distribution network. Distribution net impact can be split into 3 basic domains: EMC issues, unusually high local concentration of consumed power and presence of higher harmonics in input current. The third domain is the main objective of the article. An advantageous solution of input rectifier was proposed. A conception with a passive diode input rectifier and a DC-link with an extremely low capacity is used in this conception. Dimensioning of this DC-link capacitor to ensure mentioned low impact on distribution net is presented. The final part of the paper demonstrates overall applicability of RN14-140 fast-charger pattern via presentation of high harmonics of phase current measurements.
High-Power Charger for SUPER-EL Electric Passenger Car
Authors: Vorel Pavel , Červinka Dalibor
Published: February 2014

Fast-chargers improve dominantly the practical usability of electric vehicles because they enable to charge the traction accumulators during short time periods (ones of hours or tens of minutes). Nowadays “on board” fast-chargers are required instead of heavy and large stationary solutions. Therefore stronger requirements on high power/mass and power/volume ratio appear. This paper introduces fast-chargers developed by the authors for concrete users. The high power/mass and power/volume ratios are achieved using a non-tradition DC/DC converter operating at a very high switching frequency. Progressive silicon-carbide semiconductors are used in this converter. The developed devices are constructed as auxiliary portable devices (not „on board“). Their dimensions are very small and so the devices can be placed always in the vehicles. Then the charger can be plugged-in to the common grid 3x400V anywhere to charge the traction accumulator.
Problems of Energy Saving in Electrical Experimental Network/Smart Grid
Authors: Vesely Ivo , Zezulka Frantisek , Sembera Jaroslav , Sajdl Ondrej
Published: February 2014

This contribution deals with an idea of smart grids, a physical realization of a DC smart grid laboratory model (E.E.N.) and a strategy of its control. An author’s idea is to utilize a maximum of renewable energy which is available in an every moment. It would be a logical and the most economical principle, but it is in a contradiction with physical principles of electrical energy, with requirements coming from consumers and with possibilities of an electrical distribution system and information and control systems. A saving electrical energy is a difficult problem. In the contribution authors specify most of existing possibilities of the electrical energy saving. In a chapter DC laboratory smart grid authors describe and design a physical realization of the DC smart grid with saving into different technologies. And one of these ways is hydrogen.
The Finite Volume Method in Photovoltaic - The Cooling System of Concentrator Solar Panels
Authors: Maxa Jirí , Vyroubal Petr , Vaněk Jiri , Solčanský Marek , Křivík Petr
Published: February 2014

In concentrator cells, light is concentrated using lens to fall on solar cells to produce maximum energy as possible. By using concentrator cells light intensity is increased by targeting on certain area, which in result increases electricity production. Design and optimization of cooling equipment for heating concentrator solar cells is realized by SolidWorks and Flow Simulation systems. The device is analyzed on the flow and heat transfer to optimize the functional sample.
Conductive Ceramic as an Additive of Negative Active Mass of Lead Acid Battery
Authors: Bača Petr , Křivík Petr , Tošer Pavel
Published: February 2014

There were performed experiments with a conductive additive Ti4O7 in negative active mass of lead acid battery. First results indicate that the additive throughout the tested range of weight percent does not improve the cycle life of the negative active mass in the partial state of charge (PSoC) cycling.
Influence of the Oxygen Cycle on the Temperature of the Lead Acid Battery Cell
Authors: Křivík Petr
Published: February 2014

Heat changes in the lead acid battery cell during charging and discharging are affected by the construction of the cell and by method of cycling. They affect the use properties of the electrodes and they can change the capacity and cycle life of the cell.
Critical Crack Length for the Initiation of Unstable Propagation in Relation to Fracture Toughness and the Evaluation of Stress and Deformation Characteristics Obtained From Tensile Testing
Authors: Binar Tomáš , Dvořák Ivan , Kadlec Jaromír , Joska Zdenek , Korecki Zbysek , Kvapilová Petra
Published: February 2014

The paper is concerned with the relation between temperature and critical crack length for the initiation of a brittle crack unstable propagation at the yield strength level stress. For the purpose of calculation, results of dynamic fracture toughness test were applied; the experiment was supplemented with measuring stress and deformation characteristics in a determined test temperature range. For comprehensive assessment of test temperature effects, a fractographic analysis of fracture surfaces was conducted.
The Ways How to Measure the Characteristics of a Solar Panel
Authors: Tošer Pavel , Bača Petr , Neoral Jiří
Published: February 2014

The testing of a solar panels and photovoltaic cells as well is a very interesting method of NDTs (non destructive techniques) allowing the fast and safe inspection. Measuring method uses infrared thermography and this is known more than 10 years and is becoming increasingly important standard. Accurate thermographic images of photovoltaic cells reveal quickly and purposefully for example shunt effects, short circuits, faulty contacts etc.
Resistivity and Impedance Changes of Lead-Acid Accumulator
Authors: Abraham Pavel , Bača Petr , Vaculík Sebastian
Published: February 2014

This paper describes active mass and collector resistivity and impedance changes of lead-acid accumulator electrodes. Data was obtained during experiment with pulse charging cycling of old lead-acid accumulator. Resistivity changes of active mass and collector were measured using four-point direct current method. Impedance changes were observed by electrochemical impedance spectroscopy. Old lead-acid accumulator previously not used for almost half of a year was used in the experiment. Reasons why pulse charging was used follows: increased efficiency of charging, gas generation reduction, corrosion speed reduction, sulfation reversion of old cells.
Impedance Characteristics of Lead-Acid Accumulators with Various Amounts of Titanium Dioxide in Negative Plates
Authors: Abraham Pavel , Vaculík Sebastian , Bača Petr
Published: February 2014

It has been established that addition of carbon additives to the negative active material of lead-acid batteries increases battery charge acceptance in hybrid electric vehicle mode of operation (1). But the latest findings show that the titanium dioxide has similar effect (2). Hence this paper deals with impedance characteristics of experimental lead-acid accumulators with various amounts of titanium dioxide in active mass of negative electrodes. Electrochemical impedance spectroscopy was used for all measurements. Obtained data was subsequently fitted by equivalent circuits. It was investigated that ohmical resistivity of lead-acid cell increases with higher amounts of titanium dioxide in active mass of negative electrodes.
Membranes for Alkaline Accumulators
Authors: Musil Michal , Kunovjánek Miroslav , Pleha D.
Published: February 2014

In this paper, we report information about our recent research in the field of membranes for alkaline accumulators. Various types of experimentally prepared membranes were tested. We were focused on ionic conductivity and dendritic resistance measurements and on stability in highly alkaline liquid electrolytes. Different materials for electrode coating were also tested as ionic conductivity membranes and holders for active electrode material.