bluuebunny/crossref_metadata_2025 huggingface dataset:
Applicability of ground‐penetrating radar as a tool for nondestructive soil‐depth mapping on Pleistocene periglacial slope deposits
Authors: Gerber Rolf , Felix‐Henningsen Peter , Behrens Thorsten , Scholten Thomas
Published: June 2009

Soil depth plays a decisive role in determining soil properties in mountainous regions for ecological site assessment. To evaluate the use of ground‐penetrating radar (GPR) for fast and high‐resolution mapping within mountainous regions, we examined the possibilities and limitations of GPR to determine soil depth over bedrock and to delineate individual substrate layers formed during the Pleistocene in a periglacial environment (Pleistocene periglacial slope deposits, PPSD). Selected catenae in representative subregions of the study area (Dill catchment, SE Rhenish Massif, Germany) have been successfully mapped using GPR. A practicable method was developed using a 400 MHz antenna to reach a mean penetration depth of 1.5 m and to map different substrates and layers of PPSD based on calibrations of the GPR at soil pits along 12 catenae. Colluvium, the three types of PPSD layers, as well as the in situ bedrock could be distinguished in most sections of the GPR surveys. Characteristic GPR facies caused by intrinsic material properties of the different substrates, such as stone content and soil moisture content, could be distinguished in different geomorphologic and lithological settings. A layer‐based velocity distribution was determined for characteristic substrate layers at soil pits enabling us to considerably enhance the accuracy of soil‐depth prediction. Compared to traditionally surveyed soil profiles, our results demonstrate an accuracy of layer thickness surveying within a standard deviation of approx. 0.1 m. It is demonstrated that the combination of GPR with conventional soil‐pit mapping is an efficient and valid method to produce high‐resolution data of substrate distribution.
Root–shoot communication of field‐grown maize drought‐stressed at different rates as modified by atmospheric conditions
Authors: Asch Folkard , Bahrun Andi , Jensen Christian R.
Published: June 2009

Maize is often grown in drought‐prone environments and, thus, drought resistance is an important trait. In order to minimize production losses, plants need to respond and adapt early and fast to moisture loss in the root zone. From experiments under controlled conditions, constituents of the xylem sap, such as the plant hormone abscisic acid (ABA), or xylem pH have long been recognized to act as signals in root–shoot communication. To investigate early signals of field‐grown maize under conditions of progressive drought, a field trial was set up in a field lysimeter for two consecutive years. Although the experimental set‐up was very similar in the two years, plant responses to moisture loss were significantly different in both, the cascade of events and the intensity of responses. The main difference between the two years was in atmospheric vapor‐pressure deficit (VPD), accelerating the drying rate of the soil in the second year. In contrast to observations during the first year, the sudden increase in VPD in the second year caused a strong, transient peak in xylem sap ABA concentration, but no change in xylem pH or leaf ABA concentration was observed. Whereas the water relations of the maize plants remained stable in the first year, they were severely unbalanced in the second. It is argued that the strong xylem‐ABA signal triggered a change from adaptation mechanisms to survival mechanisms. Modulations due to VPD of constituents of the signal cascade induced by drought are discussed with regard to possible resistance strategies, their initiation, and their modification by combining primary environmental signals.
Summer temperature variations in Lapland during the Medieval Warm Period and the Little Ice Age relative to natural instability of thermohaline circulation on multi‐decadal and multi‐centennial scales
Authors: Helama Samuli , Timonen Mauri , Holopainen Jari , Ogurtsov Maxim G. , Mielikäinen Kari , Eronen Matti , Lindholm Markus , Meriläinen Jouko
Published: June 2009

New tree ring‐based analysis for climate variability at a regional scale is presented for high latitudes of Europe. Our absolutely dated temperature reconstruction seeks to characterise the summer temperatures since AD 750. The warmest and coolest reconstructed 250‐year periods occurred at AD 931–1180 and AD 1601–1850, respectively. These periods share significant temporal overlap with the general hemispheric climate variability due to the Medieval Warm Period (MWP) and the Little Ice Age (LIA). Further, we detect a multi‐decadal (ca. 50‐ to 60‐year) rhythm, attributable to instability of the North Atlantic Deep Water, in the regional climate during the MWP but not during the LIA. Intensified formation of the North Atlantic Deep Water further appeared coincident to the initiation and continuation of MWP, the mid‐LIA transient warmth occurring during the period AD 1391–1440, and to recent warming. Our results support the view that the internal climate variability (i.e. thermohaline circulation) could have played a role in the earlier start of the MWP in several proxy reconstructions compared to the externally forced model simulations. Copyright © 2009 John Wiley & Sons, Ltd.
Palaeoceanography and climate changes off North Iceland during the last millennium: comparison of foraminifera, diatoms and ice‐rafted debris with instrumental and documentary data
Authors: Knudsen Karen Luise , Eiríksson Jón , Jiang Hui , Jónsdóttir Ingibjörg
Published: June 2009

Planktonic and benthic foraminifera data, as well as ice‐rafted debris data, from a 210Pb‐dated multicore (B05‐2006‐MC04) covering the last ca. 130 a on the North Icelandic shelf (∼450 m water depth) are compared with instrumental data and with the Sea Ice Index for the area. There is indication of a strong connection between atmospheric and oceanic changes. A pronounced rise in the sea surface temperature is documented by the proxy data to occur at AD 1910, which is shortly before the rise in the air temperature in the region at ca. AD 1920 but coinciding with the first rise in instrumentally measured annual sea surface temperature. The Great Salinity Anomaly in the 1960s and early 1970s is, however, not clearly expressed in the environmental proxies. There has been a mean sedimentation rate of about 300 cm ka−1 at the core site, based on a tephrochronological age model for the core MD99‐2275. The foraminifera and diatom assemblages show increased influence of Atlantic water masses during the time interval ca. AD 800–1300 (the so‐called Medieval Warm Period or Medieval Climatic Anomaly), whereas the interval ca. AD 1300–1910 (encompassing the Little Ice Age) was characterised by decreased sea surface temperatures due to intensified influence of Arctic waters of the East Icelandic Current. Copyright © 2009 John Wiley & Sons, Ltd.
A 1000‐year record of dry conditions in the eastern Canadian prairies reconstructed from oxygen and carbon isotope measurements on Lake Winnipeg sediment organics
Authors: Buhay William Mark , Simpson Shawna , Thorleifson Harvey , Lewis Mike , King John , Telka Alice , Wilkinson Paul , Babb Jeff , Timsic Sandra , Bailey Dan
Published: June 2009

A short sediment core (162 cm), covering the period AD 920–1999, was sampled from the south basin of Lake Winnipeg for a suite of multi‐proxy analyses leading towards a detailed characterisation of the recent millennial lake environment and hydroclimate of southern Manitoba, Canada. Information on the frequency and duration of major dry periods in southern Manitoba, in light of the changes that are likely to occur as a result of an increasingly warming atmosphere, is of specific interest in this study. Intervals of relatively enriched lake sediment cellulose oxygen isotope values (δ18Ocellulose) were found to occur from AD 1180 to 1230 (error range: AD 1104–1231 to 1160–1280), 1610–1640 (error range: AD 1571–1634 to 1603–1662), 1670–1720 (error range: AD 1643–1697 to 1692–1738) and 1750–1780 (error range: AD 1724–1766 to 1756–1794). Regional water balance, inferred from calculated Lake Winnipeg water oxygen isotope values (δ18Oinf‐lw), suggest that the ratio of lake evaporation to catchment input may have been 25–40% higher during these isotopically distinct periods. Associated with the enriched δ18Ocellulose intervals are some depleted carbon isotope values associated with more abundantly preserved sediment organic matter (δ13COM). These suggest reduced microbial oxidation of terrestrially derived organic matter and/or subdued lake productivity during periods of minimised input of nutrients from the catchment area. With reference to other corroborating evidence, it is suggested that the AD 1180–1230, 1610–1640, 1670–1720 and 1750–1780 intervals represent four distinctly drier periods (droughts) in southern Manitoba, Canada. Additionally, lower‐magnitude and duration dry periods may have also occurred from 1320 to 1340 (error range: AD 1257–1363), 1530–1540 (error range: AD 1490–1565 to 1498–1572) and 1570–1580 (error range: AD 1531–1599 to 1539–1606). Copyright © 2009 John Wiley & Sons, Ltd.
Comparative analysis between a proxy‐based climate reconstruction and GCM‐based simulation of temperatures over the last millennium in China
Authors: Tan Ming , Shao Xuemei , Liu Jian , Cai Binggui
Published: June 2009

The application of general circulation models (GCMs) could improve our understanding of climate forcing. Furthermore, longer climate records spanning a wider range of climate states could help in assessing the skill of the models for simulating climates different from the present. We first attempt to find a way to combine proxy records which are affected by different seasonal temperatures, and then present a large‐scale temperature reconstruction over the last millennium for China by combining the Beijing stalagmite layer series and the Qilian tree ring sequence to compare with the GCM‐based ECHO‐G simulated millennial temperature record for China. The correlation coefficient between the simulated and the reconstructed temperature records is 0.61 based on a 31‐year running mean (exceedingP < 0.01). An asymmetricalV‐like low‐frequency variation shown both by the combined proxy record and the simulated series is the major long‐term pattern in the last millennial temperature in China, suggesting that solar irradiance as well as greenhouse gases could explain much of the low‐frequency variations in the climate. However, there still exist high‐frequency discrepancies between the two time series, which may be due to (1) the overestimated climatic effect of volcanoes within the GCM and/or (2) proxies which are not sensitive enough to respond to the volcanic eruptions. Copyright © 2009 John Wiley & Sons, Ltd.
A thousand‐year record of temperature variations for Germany and Central Europe based on documentary data
Authors: Glaser Rüdiger , Riemann Dirk
Published: June 2009

This paper presents a temperature reconstruction of the past 1000 years for Central Europe, based on chronological records. The advantages and limitations of this hermeneutic, text‐based approach are discussed and the statistic methodology is introduced. Historical documents represent direct observation of weather and atmospheric conditions with highest temporal resolution available and precise dating. A major advantage of these extensive data is that they allow the reconstruction of large numbers of variables such as winter temperature, precipitation, pressure patterns or climate extremes as well as floods or storms. Within this hermeneutic climatological research approach, even human impacts and social dimensions of climate development can be examined. In order to quantify the historical information, statistical methods are applied, based on an index approach. Copyright © 2009 John Wiley & Sons, Ltd.
Photocolorimetric determination of yolk colour in relation to selected quality parameters of eggs
Authors: Dvořák Petr , Doležalová Jana , Suchý Pavel
Published: June 2009

BACKGROUND: Determination of egg yolk colourity and colour was carried out by means of a new photocolorimetric methodology based on the CIELAB system. Measurements (after gloss elimination) were performed using a Color Guide Sphere Spex photocolorimeter. For comparison, a standard method according to the Yolk Colour Fan® (Roche) was used.

RESULTS: Yolk colourity was measured in 252 eggs from layers of Isa Brown breed (aged 51–80 weeks). The colourity parameter L* ranged from 43.42 to 68.51. The parameter a* ranged from 0.05 to 13.49 and the parameter b* ranged from 22.38 to 48.18. The normal (Gaussian) distribution curve for the individual parameters was validated. The resulting number of 8700 combinations of yolk colour parameters was given by multiplication of possible results in the experiment while taking into account the instrumental accuracy. All results according to the Yolk Colour Fan® (Roche) scale represented a range of three colour stripes.

CONCLUSION: The photocolorimetric determination is more precise than the Yolk Colour Fan® (Roche) method. No correlation between yolk colourity parameters and yolk cholesterol concentration was found. The highest correlation (r = −0.919) was observed between yolk colourity parameter b* (yellow colour) and total egg weight. Copyright © 2009 Society of Chemical Industry
Help on the way: Senior leaders can benefit from working with a mentor
Authors: Zachary Lois J. , Fischler Lory A.
Published: June 2009

As leaders gain seniority, many of them view their days of being a mentee as behind them. They see mentoring as a developmental activity designed primarily to help new or emerging leaders. But mentoring can be a powerful tool for helping leaders at all levels grow and develop. Finding and working successfully with the right mentor requires commitment and following the correct steps.
Staying on track: How to keep in touch with your development progress
Authors: Hannum Kelly M. , Hoole Emily
Published: June 2009

Devising a developmental goal and efficiently tracking your progress toward the goal require articulating your goal, creating an action plan, gathering information about your behavior, identifying barriers and supports, and revising your action plan. Following these steps will greatly enhance your chances of reaching your goal.
Skin fluorescence controlled photodynamic photorejuvenation (wrinkle reduction)
Authors: Bjerring Peter , Christiansen Kaare , Troilius Agneta , Bekhor Philip , de Leeuw Jaap
Published: June 2009

Background

Identical skin fluorescence can be obtained after one hour spraying with 0.5% liposome‐encapsulated 5‐ALA and after 0.5 hour application of 20% 5‐ALA in a cream base. In this study the clinical outcome and side effects using the 0.5% 5‐ALA in Caucasian skin are investigated and compared to earlier reported non‐ablative treatments for wrinkles and improvements of skin texture using 20% ALA photodynamic photorejuvenation.

Methods and Materials

37 healthy Caucasian female patients participated in a randomized, prospective split face study. Two different intense pulsed light (IPL) treatment modalities were investigated; both employed a pre‐treatment of approximately one hour of spraying with 0.5% liposome encapsulated 5‐ALA. One modality combined type I photorejuvenation with wrinkle reduction (C‐PDT) using a waveband from 530 to 750 nm and short pulse durations (7 J/cm2, 2 × 2.5 ms, delay 10 ms). The other modality (PDT alone) emitted a band of wavelengths from 400 to 720 nm, three passes were performed (3.5 J/cm2, 30 ms pulse duration).

Results

After a series of three C‐PDT or PDT‐alone treatments, the patients obtained statistically significant (P< 5 × 10‐5) reductions in periorbital and perioral wrinkles. Using the Fitzpatrick wrinkle scale, periorbital wrinkles were reduced by 1.2 grades (SD: 1.1) and 1.1 (SD: 1.1), respectively and perioral wrinkles were reduced by 0.8 grades (SD: 1.0) and 0.7 (SD: 0.9) respectively. The difference in treatment efficacy between. C‐PDT and PDT alone treated sides was not statistically significant (P = 0.224).

Conclusion

The present study shows that statistically significant improvements in wrinkle reduction and skin texture, equivalent to previously reported results obtained with 20% ALA, can be obtained with 0.5% liposome encapsulated 5‐ALA. Only minor and infrequent side effects were registered at the 0.5% 5‐ALA treated areas. Skin fluorescence monitoring during pre‐treatrnent with 5‐ALA may improve clinical efficacy, reduce time consumption and increase safety of the treatment. Lasers Surg. Med. 41:327–336, 2009. © 2009 Wiley‐Liss, Inc.
Biological reconstruction after resection of bone tumors of the proximal tibia using allograft shell and intramedullary free vascularized fibular graft: Long‐term results
Authors: Innocenti Marco , Abed Yasser Y. , Beltrami Giovanni , Delcroix Luca , Manfrini Marco , Capanna Rodolfo
Published: June 2009

Reconstruction after excision of bone tumor of the proximal tibia is a challenging issue for the reconstructive surgeon. The combined use of a free fibular flap and allograft can provide a reliable reconstructive option in this location. This article describes the authors' long‐term follow‐up using this technique. Twenty‐seven patients that had resection of proximal tibia bone tumors underwent reconstruction using this technique. Only 21 patients that had primary reconstruction were included in this study. All patients had their surgeries performed at least 24 months before the end of the study. The average age at time of operation was 18.1 years. The average follow‐up time was 139.3 months. Limb salvage was 82.7%. The average length of the resected tibial segment was 15.3 cm and that of the residual proximal tibia remaining after resection was 2.7 cm. The average time of union of fibula was 5.4 months and for union of allograft was 19.1 months. Primary union of the allograft was achieved in 90.5% of cases. Full weight‐bearing was achieved at an average of 21.6 months. Ten patients (47.6%) had 14 local complications. The (MTSRS) average score at final follow‐up was 27.3. Local recurrences occurred in two patients (9.5%). Distant metastasis to the lung occurred in three patients (14.3%). One patient died of disease. This technique provides good long‐term results in reconstruction of proximal tibia. The viability of the fibula is a cornerstone in both success of reconstruction as well as successful management of complications. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
How to bring about change in the Bangladesh civil service? Attempts to change mindsets, behaviours and practice
Authors: Jacobs Colin
Published: June 2009

This article addresses three critical questions central to many donor funded programmes which seek to enable pro‐poor reform and growth. In the context of Bangladesh, the research asks first, does the civil service has a role in promoting change of this kind? Second, can a senior civil service development programme succeed in creating reform minded civil servants? And, third, if so how might the contribution be made both more substantive and of value? These questions are addressed systematically through a literature review and evidence drawn from Managing at the Top (MATT 2)—a DFID funded programme. Some tentative conclusions are drawn in the final section. Copyright © 2009 John Wiley & Sons, Ltd.
Downregulation of CD36 results in reduced phagocytic ability of peritoneal macrophages of women with endometriosis
Authors: Chuang Pei‐Chin , Wu Meng‐Hsing , Shoji Yutaka , Tsai Shaw‐Jenq
Published: June 2009

Endometriosis, defined as the growth of endometrial tissues outside of the uterine cavity, is a severe and complex disease affecting more than 10% of women. The aetiology of endometriosis is unclear but immune dysfunction might be an important factor for its development. The natural function of the immune system is to detect and destroy aberrant or abnormal cells. Failure of the immune system to eradicate these aberrant cells often results in disease pathogenesis. We report here that the phagocytic ability of macrophages is reduced in peritoneal macrophages isolated from women with endometriosis. In‐depth investigation revealed that the level of CD36, a class B scavenger receptor, in peritoneal macrophages derived from women with endometriosis was lower than that in normal macrophages. Blockage of CD36 function by neutralized antibody or knocking down CD36 using siRNA impaired the phagocytic ability of normal macrophages. In contrast, forced expression of CD36 in macrophages isolated from women with endometriosis restored phagocytic ability. Taken together, we identified that the scavenger receptor CD36 is reduced in the peritoneal macrophages of women with endometriosis, which leads to a decrease of the phagocytic ability of macrophages. These findings revealed a potential mechanism of immune dysfunction during endometriosis development. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Determination of nickel, calcium and magnesium in xylem sap by flame atomic absorption spectrometry using a microsampling technique
Authors: Alves Sheila , Gonçalves Maria L. Simões , Santos Margarida M. Correia dos
Published: June 2009

Introduction

Knowledge of xylem sap chemical composition is important to the understanding of translocation, detoxification and tolerance mechanisms. However, the small amount of sample available often hampers its characterisation. Hence, low volume consumption techniques are needed for xylem sap analysis.

Objective

To develop a microsampling technique for the determination of elements in xylem sap from different plants by flame atomic absorption spectrometry (FAAS).

Methodology

The microsampling device was optimised in terms of sample volume and integration time. The analytical characteristics of the microsampling technique (µ‐FAAS) were established and compared with those of FAAS with traditional continuous nebulisation. The method was validated by means of an independent technique.

Results

Ca, Mg and Ni were determined in a 50 µL aliquot of xylem sap solution/element that was introduced directly into the flame via the microsampling accessory. Good precision was obtained with relative standard deviations of 1.1, 0.6 and 2.3% for Ca, Mg and Ni, respectively. Matrix effects resulting from the physical characteristics of the samples and possible chemical interferences caused by phosphate and/or sulphate were ruled out.

Conclusion

A simple, rapid and reproducible microsampling technique coupled to FAAS was developed and successfully applied in the determination of Ca, Mg and Ni in xylem sap. Copyright © 2009 John Wiley & Sons, Ltd.
A retention index calculator simplifies identification of plant volatile organic compounds
Authors: Lucero Mary , Estell Rick , Tellez María , Fredrickson Ed
Published: June 2009

Introduction

Plant volatiles (PVOCs) are important targets for studies in natural products, chemotaxonomy and biochemical ecology. The complexity of PVOC profiles often limits research to studies targeting only easily identified compounds. With the availability of mass spectral libraries and recent growth of retention index (RI) libraries, PVOC identification can be achieved using only gas chromatography coupled to mass spectrometry (GCMS). However, RI library searching is not typically automated, and until recently, RI libraries were both limited in scope and costly to obtain.

Objective

To automate RI calculation and lookup functions commonly utilised in PVOC analysis.

Methodology

Formulae required for calculating retention indices from retention time data were placed in a spreadsheet along with lookup functions and a retention index library. Retention times obtained from GCMS analysis of alkane standards and Koeberlinia spinosa essential oil were entered into the spreadsheet to determine retention indices. Indices were used in combination with mass spectral analysis to identify compounds contained in Koeberlinia spinosa essential oil.

Results

Eighteen compounds were positively identified. Total oil yield was low, with only 5 ppm in purple berries. The most abundant compounds were octen‐3‐ol and methyl salicylate. The spreadsheet accurately calculated RIs of the detected compounds.

Conclusion

The downloadable spreadsheet tool developed for this study provides a calculator and RI library that works in conjuction with GCMS or other analytical techniques to identify PVOCs in plant extracts. Copyright © 2009 John Wiley & Sons, Ltd.
Chemoenzymatic synthesis of Y‐shaped amphiphilic block copolymers and their micellization behavior
Authors: Zhang Bao , Li Yapeng , Sun Jinghui , Wang Shuwei , Zhao Yili , Wu Zhanyu
Published: June 2009

BACKGROUND: Y‐shaped block copolymers are a type of special star polymer that have received considerable attention due to their unique morphologies and phase behavior. This research is based on the preparation of novel Y‐shaped block copolymers using enzymatic ring‐opening polymerization (eROP) and atom‐transfer radical polymerization (ATRP), followed by an investigation of their micellization properties.

RESULTS: Y‐shaped block copolymers consisting of polycaprolactone and poly(glycidyl methacrylate) were synthesized successfully by the combination of eROP and ATRP. NMR, gel permeation chromatography (GPC), Fourier transform infrared and atomic force microscopy analyses confirmed the compositions of the block copolymers. The dispersity obtained from GPC was less than 1.4, which indicated a control of the polymerization. The self‐assembly behavior of the Y‐shaped block copolymers was investigated in aqueous media. Aggregates of various morphologies (such as spherical micelles, lamellae, worm‐like micelles and large compound micelles) were observed. In addition, it was found that both the copolymer composition and concentration in tetrahydrofuran greatly influenced the morphologies of the aggregates.

CONCLUSION: The results suggest that the Y‐shaped diblock copolymers can be synthesized by simple methods. They have various morphologies, including normal spherical micelles, lamellae, worm‐like micelles and large compound micelles. Copyright © 2009 Society of Chemical Industry
Synthesis, characterization and properties of biodegradable poly(butylene succinate)‐block‐poly(propylene glycol) segmented copolyesters
Authors: Huang Xi , Li Chuncheng , Zheng Liuchun , Zhang Dong , Guan Guohu , Xiao Yaonan
Published: June 2009

BACKGROUND: To obtain a biodegradable thermoplastic elastomer, a series of poly(ester‐ether)s based on poly(butylene succinate) (PBS) and poly(propylene glycol) (PPG), with various mass fractions and molecular weights of PPG, were synthesized through melt polycondensation.

RESULTS: The copolyesters were characterized using 1H NMR, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, mechanical testing and enzymatic degradation. The results indicated that poly(ester‐ether)s with high molecular weights were successfully synthesized. The composition of the copolyesters agreed very well with the feed ratio. With increasing content of the soft PPG segment, the glass transition temperature decreased gradually while the melting temperature, the crystallization temperature and the relative degree of crystallinity decreased. Mechanical testing demonstrated that the toughness of PBS was improved significantly. The elongation at break of the copolyesters was 2–5 times that of the original PBS. Most of the poly(ester‐ether) specimens were so flexible that they were not broken in Izod impact experiments. At the same time, the enzymatic degradation rate of PBS was enhanced. Also, the difference in molecular weight of PPG led to properties being changed to some extent among the copolyesters.

CONCLUSION: The synthesized poly(ester‐ether)s having excellent flexibility and biodegradability extend the application of PBS into the areas where biodegradable thermoplastic elastomers are needed. Copyright © 2009 Society of Chemical Industry
Methodology and experimental system for measuring and displayingI–Vcharacteristic curves of PV facilities
Authors: Durán E. , Andújar J. M. , Galán J. , Sidrach‐de‐Cardona M.
Published: June 2009

This paper describes a methodology and the developed system for measuring, capturing, and displayingI–VandP–Vcharacteristic curves of photovoltaic (PV) modules or arrays based on single‐ended primary inductance converters (SEPIC) in parallel connection, operating in interleaved mode. The proposed methodology and the developed system allow the real time capture and displaying of theI–VandP–Vcurves of a PV panel or array, and show several advantages with regard to classical methods: simple structure, scalability, fast response, versatility, direct display, and low cost. The measuring of the characteristic curves of PV modules includes high speed of response and high fidelity, with low ripple. An experimental prototype based on four SEPIC converters in parallel connection has been implemented to validate the proposed methodology. This new methodology and experimental system has been registered in the Spanish Patent and Trademark Office with the number P200930198. Copyright © 2009 John Wiley & Sons, Ltd.
Surface Coating by Repeated Plasma‐Assisted Grafting and Cross‐Linking of Molecular Precursors
Authors: Ohl Andreas , Besch Wilfried , Steffen Hartmut , Foest Rüdiger , Arens Michael , Wandel Klaus
Published: June 2009

Plasma assisted deposition of thin films with defined chemical structure and controlled thickness of a few nanometers requires basically new coating techniques. Here, repeated grafting deposition of molecular precursors was investigated. This technique might lead to plasma polymer films with new properties. Self‐limited growth of layers with monomolecular thickness is shown. Film thickness is a linear function of the number of growth cycles. The growth rate per cycle is independent of precursor dosing time and to some degree also of plasma exposure time. However, imperfect gap penetration must be admitted. Chemical structure retention can be better than for usual plasma polymerization. A potential usefulness for deposition of films with tailored surface chemistry is demonstrated.

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Rapidly Solidified Thick Iron Base Alloy Deposit with Vanadium Carbide Particles Produced by Plasma Spraying
Authors: Hoshiyama Yasuhiro , Hirano Kentaro , Miyake Hidekazu
Published: June 2009

Fe‐C‐V alloy powder is low‐pressure plasma sprayed to produce iron base composite deposits with finely dispersed vanadium carbide particles. The as‐sprayed deposit formed on a water‐cooled substrate is composed of α phase that is saturated with vanadium and carbon, V8C7 and amorphous. The form of vanadium carbides in the as‐sprayed deposit shows more granular compared with that in the cast whose chemical compositions are similar to that of deposit. With increasing heat treatment temperature up to 1 273 K and heat treatment time up to 7.2 ks, the carbide particles coarsen. The constituents of the as‐sprayed deposit formed on a non‐cooled substrate are α and V8C7. The hardness of deposit formed on a water‐cooled substrate is higher than that of deposit formed on a non‐cooled substrate.
Wear Mechanisms of (Cr,Al,Y)N PVD Coatings at Elevated Temperatures
Authors: Scheerer Herbert , Berger Christina
Published: June 2009

Over the past years there have been developments in machining operations to replace the use of liquid cooling by dry cutting operations. This results in higher loads for the tools and therefore demands the continuous development of surface coatings. (Cr,Al,Y)N‐coatings designed at the Institute of Materials Technology in Darmstadt, Germany, show beneficial tribological properties especially at high loads and high temperatures. Samples of different yttrium content have been distinguished and compared to an industrial TiAlN coating. Even though the configuration of the (Cr,Al,Y)N coatings is not yet as optimised as that of the TiAlN, which leaves plenty of room for improvement, the (Cr,Al,Y)N shows comparable and partly superior properties to the TiAlN coating. An increasing yttrium content of the (Cr,Al,Y)N leads to a more amorphous microstructure and to finer and denser morphology with a smoother surface. The TiAlN, in contrast, exhibits a porous, columnar structure. This results in advantages in the wear behaviour as well as in the oxidation resistance. Furthermore, a distinct improvement of the adhesion of the layer to the carrier is determinable, which results in higher sustainable loads at the scratch test.
Can WSeC Coatings Be Competitive to WSC Ones?
Authors: Evaristo Manuel , Polcar Tomas , Cavaleiro Albano
Published: June 2009

WSeC coatings were deposited by co‐sputtering from WSe2 and C targets. Carbon content varied from 25 up to 70 at.%, Se/W ratio was between 0.9 and 1.0, with no significant influence of the carbon content on their variations. The hardness of the coatings was evaluated by nano‐indentation with values between 3.8 and 5.6 GPa. The structure of the coatings analysed by X‐ray diffraction in glancing mode could be defined as quasi‐amorphous. The tribological properties were evaluated in an SRV machine using reciprocating ball‐on‐disk tests under increasing loads. In general, the friction gets decreased with increasing loads. The comparison with other transition metals, dichalcogenides alloyed with carbon, namely MoSeC and WSC systems, showed that WSeC coatings could be a good alternative with almost identical friction properties.
Interaction of Stearic Acid Deposited on Silicon Samples With Ar/N2 and Ar/O2 Atmospheric Pressure Microwave Post‐discharges
Authors: Noël Cédric , Duday David , Verdier Stéphane , Choquet Patrick , Belmonte Thierry , Migeon Henri‐Noël
Published: June 2009

In this work, the interactions of a stearic acid film deposited on silicon by spin coating with the post‐discharge of an Ar/N2 or Ar/O2 atmospheric pressure microwave plasma are studied. Sample surface before and after plasma treatment is analysed by means of different surface analysis methods (water contact angle measurements, XPS, ToF‐SIMS and FTMS). Both plasma treatments modify the surface but with a higher etching rate for Ar/O2 post‐discharges. The creation of double carbon bonds CC is observed during the treatments, with a higher quantity after Ar/N2 treatments. The mechanisms leading to modifications of stearic acid are discussed.
Development of VHF Plasma Source with Short Discharge Gap for Solar Cells
Authors: Yamauchi Yasuhiro , Baba Tomoyoshi , Takeuchi Yoshiaki , Takatsuka Hiromu , Muta Hiroshi , Uchino Kiichiro , Kawai Yoshinobu
Published: June 2009

A new balanced power feeding method was applied to produce a large area VHF plasma using short discharge gaps and the electric characteristics of the discharge electrodes were measured as a function of pressure for different discharge gaps. It was found that the new balanced power feeding method is suitable for short gap discharges in the VHF range. Furthermore, the plasma parameters were examined as a function of pressure for different discharge gaps. The plasma density peaked at a certain pressure independent of the length of discharge gaps.
Comparative Study of Total Power Density at a Substrate in Pulsed DC Magnetron and Hollow‐Cathode Plasma Jet Sputtering Systems
Authors: Čada Martin , Virostko Petr , Kment Štěpán , Hubička Zdeněk
Published: June 2009

The pulsed DC magnetron and hollow‐cathode plasma jet sources have been studied from the point of view of total energy flux density at a “floating” substrate. Both plasma sources were operated under identical experimental conditions and differences between both systems were investigated. The aim of this work is focused on the characterization of total power density at electrically isolated substrate for various duty cycles and for different pulsing frequencies. A calorimeter probe with incorporated thermocouple junction was used for measurement of the total power density on the substrate. The main results from the calorimeter probe show clearly that total power density at the substrate is much higher for the planar magnetron operating at low duty cycle and high pulsing frequency than for the plasma jet. The total power density measured in the planar magnetron depends more strongly on the duty cycle and the pulsing frequency than measured in the plasma jet.
Production of VHF excited H2 Plasma by New Method of Superposing the Standing Waves
Authors: Kaneko Hirofumi , Kodera Akio , Soejima Yukio , Tsuji Shinji , Murata Masayoshi
Published: June 2009

A novel VHF plasma source using a method of superposing standing waves is proposed in this article. The characteristics of VHF plasma generated by this method were measured with the Langmuir probe and a digital camera. Here, the frequency was 80 MHz, and an electrode size and discharge gap of electrodes was 1 800 × 300 mm2 and 20 mm, respectively. The distributions of plasma light emission were uniform across the whole electrode in the pressure range from 0.1 to 0.3 Torr. The spatial profile of the ion saturation current density was flat in the direction of the electrode. In this case, the non‐uniformity of VHF plasma was less than ±10% at 0.3 Torr.
Combined Laser Alloying/Dispersing and Plasma Nitriding, an Efficient Treatment for Improving the Service Lifetime of the Forging Tools
Authors: Gläser Thorsten , Bausch Sascha , Ruset Cristian , Grigore Eduard , Craciunescu Teddy , Tiseanu Ion
Published: June 2009

During the application, the active surface of the forging dies is subjected to intense mechanical and thermal stresses combined with chemical oxidation. The fatigue resistance is an important characteristic which limits the service lifetime of the forging tools. This characteristic was significantly improved by a combined treatment between laser alloying/dispersing and plasma nitriding. This treatment was developed for W1.2365 and W1.2344 steels using TiC and WC + Co powders as additive materials. The surface layers have been examined by optical microscopy, glow discharge optical spectrometry (GDOS), energy dispersive X‐ray (EDX), X‐ray microtomography and other techniques. The combined treatment was successfully applied to a number of 13 forging tools from 4 European Companies, leading to an increase of their lifetime by factors ranging between 180 and 270%.
Effect of Pre‐deforming on Low Temperature Plasma Nitriding of Austenitic Stainless Steel
Authors: Nishimoto Akio , Akamatsu Katsuya
Published: June 2009

This paper reports a study on the effect of a modified layer caused by pre‐deforming on the low temperature plasma nitriding of SUS 316 austenitic stainless steel. The pre‐deformed sample was prepared by the rolling in 0, 1, 2, 5, and 10% ratios. Plasma nitriding was carried out at 673 and 723 K for 18 ks under 600 Pa pressures in the presence of N2/H2 in 50:50 ratio. After nitriding, maximum hardness ∼1 070 HV was achieved on the pre‐deformed sample. XRD pattern showed that the most dominant phase of the nitrided layer consisted of the expanded austenite (S phase). In addition, the pre‐deforming by the rolling had a great influence on the increment of hardness and thickness of the S phase.
Micro‐Particles as Electrostatic Probes for Plasma Sheath Diagnostics
Authors: Wolter Matthias , Haass Moritz , Ockenga Taalke , Blažek Josef , Kersten Holger
Published: June 2009

In basic plasma physics and plasma technology, micro‐particles (dust grains) play an important role for the investigation and understanding of the behavior of different plasma species. It is well known that micrometer‐sized particles can find an equilibrium position if all acting forces to the particles are balanced. This stable point is a few millimeters above the powered electrode in the plasma sheath. In our experimental set‐up, we observed the position and the motion of microscopic test particles with a typical radius between 4.78 and 13.3 µm. In addition to the experiments, we also investigate the particle behavior by a numerical model. By comparison between the numerical model and the experimental observation, internal plasma parameters can be obtained.
Retarding Field Analyzer for Ion Energy Distribution Measurement Through a Radio‐Frequency or Pulsed Biased Sheath
Authors: Gahan David , Dolinaj Borislav , Hayden Chanel , Hopkins Michael B.
Published: June 2009

A compact, floating retarding field energy analyzer for measurement of ion energy distributions impacting an electrode through a radio‐frequency or pulsed bias sheath in a plasma discharge is presented. The analyzer is designed to sit on the electrode surface, in place of the substrate, and wide‐band low pass filters allow it to float at the electrode potential. This avoids the need for modification of the electrode. The capabilities of the analyzer are demonstrated through ion energy distribution and electron energy distribution measurements at the electrode surface in an inductively coupled plasma reactor. For a sinusoidal radio‐frequency driving signal applied to the electrode the analyzer is shown to resolve ions with different mass. When the radio‐frequency power to the plasma pulsed the analyzer is used to resolve the ion energy distributions at different times in the pulse. The high energy tail of the electron energy distribution reaching the electrode surface is also measured. A comparison with a Langmuir probe shows exceptional agreement in the energy region where both devices overlap.
Multiphysics Coupling Simulation of Silicon Nitride CVD Using an RLSA Source
Authors: Brcka Jozef , Kang Song‐Yun
Published: June 2009

The plasma produced by a radial line slot antenna (RLSA) source is discussed based on a simulation using a multiphysics coupled 2D fluid model. The technological aspects in a silicon nitride chemical vapor deposition (CVD) process using a disilane and ammonia mixture are addressed. The model includes the incompressible Navier–Stokes module (INSM), the multiple convection and diffusion transport modules (CDTM), the convection and conduction heat transport (CCHT) for gas and electron temperature, and the transverse electromagnetic (TEM) wave propagation for a planar microwave source structure coupled to the plasma. The dominant precursors, deposition rate and mechanisms, and performance of the CVD process in terms of the film properties are investigated. The ionic and radical component 2D distributions are calculated and the simulation results are correlated with experimental data. The significant impact of the surface reactions with the involvement of H, NH, and NxHy radicals and ions is established.
Monte Carlo Simulation of Electrons' and Ions' Trajectories in Magnetron Sputtering Systems
Authors: Holik Miroslav , Bradley James , Bellido‐Gonzalez Victor , Monaghan Dermot
Published: June 2009

A 3D simulation system has been developed to study electron and ion densities and other plasma parameters in circular and rectangular magnetron sputtering systems. Typically, 105 particles of each species are tracked simultaneously for a time period when the plasma parameters' distributions get stabilised. During this period, the particles undergo Lorentz force and different kinds of collisions. The collisions are generated by Monte Carlo method using null‐collision technique.
Repair and online mechanical integrity monitoring
Authors: Ternowchek Sam , Deonarine Sheldon
Published: June 2009

Described in this article are a series of cracks found in a vessel during a routine inspection. The welding methods and procedures used to address unique problems associated with the repair of these cracks are described. After the repairs were completed and inspected, an online Acoustic Emission (AE) system was installed to monitor the mechanical integrity of the vessel while in operation. The system presents data locally for use by operations personnel as well as remotely, via the internet, for detailed analysis by engineers.

A major benefit of online monitoring is that it can show an association between defect growth and operating conditions should process information be recorded by the system. AE data, therefore, can help optimize the operating conditions to minimize or eliminate defect growth and equipment damage.

Until recently, online AE monitoring was confined to a few, specialized applications such as high energy piping in refineries and power plants. The advent of better computers and software, high speed internet connections, and more reliable instrumentation has made remote monitoring a reality. The AE specialist can now operate the AE system and evaluate online data remotely and report results by web site or e‐mail.

The AE system has also been of use as a process monitor in addition to the vessel integrity monitor. It provides an ongoing condition assessment of the vessel. Gasket leaks on start up and valve leakage are some of the problems that have been identified with the online AE system. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2010
Suppressed surface‐recombination structure and surface passivation for improving current gain of 4H‐SiC BJTs
Authors: Nonaka Kenichi , Horiuchi Akihiko , Negoro Yuki , Iwanaga Kensuke , Yokoyama Seiichi , Hashimoto Hideki , Sato Masashi , Maeyama Yusuke , Shimizu Masaaki , Iwakuro Hiroaki
Published: June 2009

4H‐SiC bipolar junction transistors (BJTs) are one of the promising candidates for next‐generation power devices. 4H‐SiC BJTs have the advantages of low on‐resistance and high temperature capability. On the other hand, high common emitter current gain is required from a practical use point of view because BJTs are current‐controlled devices. In order to improve the current gain of 4H‐SiC BJTs, we have concentrated on suppressing surface recombination on the SiC surface, which is a critical limiting factor of the current gain and can be suppressed by reducing carrier density and/or trap density. We have proposed novel 4H‐SiC bipolar junction transistors with suppressed surface‐recombination structure: SSR‐BJTs that have the SiC surface with low carrier density, characterized by a lightly doped n‐type layer (LDN layer) and a highly resistive p‐type region (HRP region). In addition, surface passivation suitable for reducing surface traps has been investigated by applying a new characterization method of surface‐recombination current in which the sp · Ls value, a product of a surface‐recombination velocity (sp) and a surface‐diffusion length (Ls), is derived from an analysis of forward I–V characteristics of SiC pn diodes. We have experimentally demonstrated that the sp · Ls value is a practical indicator to evaluate surface passivation. By using the characterization, an effective passivation method with the combination of a pyrogenic oxidation, a post‐oxidation anneal in H2 ambient, and an anneal in NH3 ambient has been developed. SSR‐BJTs with a variety of device structures and process conditions have been fabricated to investigate their characteristics. A fabricated SSR‐BJT showed a recorded maximum current gain of 134 at room temperature with a specific on‐resistance of 3.2 mΩ cm2 and a blocking voltage VCEO of 950 V. The SSR‐BJT kept a current gain of 60 °C at 250 °C with a specific on‐resistance of 8 mΩ cm2. These results have demonstrated the outstanding current‐gain capability of the SSR‐BJTs compared to conventional BJTs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Amorphisation and sub‐100‐nm exfoliation of hydrogen‐ion‐implanted silicon
Authors: Moutanabbir O. , Terreault B. , Giguère A.
Published: June 2009

The basic physics and the chemical role of H in amorphisation and exfoliation of H‐ion‐implanted silicon were investigated by Raman scattering and transmission electron microscopy. We found that a continuous, thermally stable, 50‐nm‐thick amorphous layer formed upon implantation of 5‐keV H ions at 150 K. Such amorphisation is contrary to earlier theoretical predictions but gives support to recent molecular dynamics calculations. After high temperature annealing, H‐saturated mono‐ and di‐vacancies became dominant in the Si‐H Raman spectrum. (001) platelets and microcracks apppeared in the c‐Si beyond the a‐Si layer, leading to the exfoliation of a 90‐nm thick layer. Deuterium implantation leads to the formation of a thicker (∼100 nm) amorphous layer but inhibits exfoliation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)