bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in Nutritional Therapy of Acute Pancreatitis
Authors: Chávez-Tostado Mariana , Verónica Chávez-Tostado Karla , Fuentes-Orozco Clotilde , González-Ojeda Alejandro , Luisa Mendoza-Magaña María , Alberto Ramírez-Herrera Mario , Cervantes-Guevara Gabino , Alonso Cervantes-Cardona Guillermo , Cervantes-Pérez Enrique , Mercedes Hernández-Corona Diana , González-Heredia Tonatiuh , Méndez-del Villar Miriam , Fernanda Isadora Meraz-Corona María , Omar Guzmán-Ornelas Milton , Alberto Ramírez-Mendoza Abraham , Arandeni Ramírez-Mendoza Steffany
Published: September 2022

Acute pancreatitis (AP) is a frequent abdominal acute inflammatory disorder and the leading cause of hospital admissions in gastrointestinal units. Clinical manifestations of AP vary from a mild edematous form to severe fulminant pancreatitis with major devastating complications. To date, experimental therapeutic agents remain scarce for the treatment of this disease. Nutritional therapy with appropriate nutrient supplementation is key to limiting the acute inflammation and preventing and managing complications associated with AP. This chapter focuses on novel therapeutic agents for nutritional intervention including enteral versus parenteral nutrition strategies, and nutritional supplements such as probiotics, glutamine, omega-3 fatty acids, and vitamins in the treatment of AP.
The COVID-19 Vaccines: The Current Standpoint
Authors: Kim Jaeyoung , Thapa Nikita
Published: September 2022

Coronavirus disease 2019 (COVID-19) is a global pandemic that has affected millions of people worldwide. Vaccination seems to be the potent solution to achieve herd immunity and limit viral spread. Various platforms have been utilized to manufacture COVID-19 vaccines such as adenovirus-based vaccines, inactivated virus, DNA-based vaccines, recombinant protein, or mRNA-based vaccines. This chapter covers different viewpoints and the present status of in-use vaccine including the advantages and disadvantages.
GEOLOGICAL FEATURES IDENTIFIED FROM FIELD OBSERVATIONS AND REMOTE SENSING DATA ON THE UM TAGHIR AREA, EASTERN DESERT, EGYPT
Authors: Awad H. A. , El-Leil I. A. , Kamel M. , Tolba A. , Nastavkin A. V. , El-Wardany R. M.
Published: September 2022

The current study presents the integration between field observations and remotely sensed data for detection and extraction of geological structural features using Sentinel-2A and Aster DEM images. The area under investigation is represented by the Neoproterozoic East African Orogeny encompassing a part of the Arabian Nubian Shield. All the rock units studied belong to the Late Cryogenian-Ediacaran periods that are divided into two large terrains (continental arc terrain and oceanic arc terrain). The metagabbro and metavolcaniclastic rocks make up the oceanic terrain, while the gabbro, tonalite, granodiorite, dokhan volcanic, monzogranite and alkali feldspar granite comprise continental arc terrain. The Sentinel-2A remote sensing and ASTER DEM data have meaningful application in respect of geological interpretation. Lineament analysis is one of the most useful tools in geological mapping and mineral exploration. Several methods of processing and extracting lithological information and lineaments were applied to the Sentinel-2A and ASTER DEM data covering the present study. The methods include various image enhancements (FCC, MNF and PCA) and the application of directional filters (Sobel). The study results show that the area was subjected to stresses of various directions (WNW – ESE, NW-SE, NE-SW, N-S, NNE – SSW, and E-W). There occurred some important structure-related and mineralization events like migmatization (in granodiorites) and bearing mineralization (in gabbro), which are associated with major elements of evidence-based structural control of the area and with the proximity of the Quena Safaga shear zone-related mineralization.
Atravesando la Red. Arte, textiles y tecnología digital
Authors:   Universidad de Vigo, Coleman Sara
Published: September 2022

En esta era tecnodigital, donde lo real y lo virtual, lo biológico y lo social, lo analógico y lo digital se entrecruzan constantemente, nuestra concepción del mundo ya no puede ser entendida si no es sobre la base de las interconexiones y atravesamientos que en ella se producen. Habitando, pues, esta multiplicidad de redes interconectadas, donde todo son filamentos y conexiones de múltiples direcciones, el presente artículo propone repensar el lugar que ocupa la materialidad en la era tecnodigital a través de los modos textiles. Para ello, y teniendo en cuenta que los textiles encierran la clave de todo un desarrollo tecnológico digital que empieza a gestarse con la Primera Revolución Industrial, comenzaremos realizando un recorrido socio-técnico-histórico que tratará de explicar cómo los modos textiles se relacionan con la tecnología digital para, posteriormente, investigar las interrelaciones y modulaciones que se dan entre ellos en la práctica artística contemporánea. Por lo que, a partir de tres casos de estudio, realizaremos un análisis siguiendo el modelo tecnológico textil propuesto por los filósofos Gilles Deleuze y Felix Guattari en su libro Mil mesetas. Capitalismo y esquizofrenia (1980), en el que trabajan alrededor de los pares de conceptos: lo liso / lo estriado y segmentaridad dura / segmentaridad flexible. El artículo pretende aportar, así, una perspectiva neomaterialista sobre el arte en relación con la cultura digital.
Happygram: narrativas visuales en la sociedad panóptica
Authors:   Universidad de A Coruña, Mesías-Lema José María , Sabela Eiriz Sabela
Published: September 2022

El auge de las redes sociales y el protagonismo de la fotografía en ellas han traído cambios en la producción y en la recepción de las imágenes, así como en la construcción de nuestra intimidad. Dentro de este entorno social digital, nos convertimos en consumidores y productores de imágenes al mismo tiempo, voyeurs observados a uno y otro lado de la pantalla, que comparten vidas ficcionadas y fotografiadas compulsivamente para su consumo online. En este artículo, abordamos la autobiografía mediática construida en la esfera virtual y que compone la Happygram, poniendo el foco de atención en la transformación de la mirada y de la imagen fotográfica, así como en las nuevas narrativas visuales que se generan en nuestro archivo personal. Paralelamente, analizamos las respuestas fotográficas en el arte contemporáneo ante estas nuevas dinámicas, que reflexionan sobre el protagonismo del selfie y el registro de las experiencias que compartimos y consumimos en este panóptico digital.
Transparencia en periodismo: entre el ejercicio ético y la búsqueda de credibilidad informativa
Authors:   Universitat Oberta de Catalunya, Martínez Martínez Silvia
Published: September 2022

Frente a la crisis de credibilidad y la difusión de las conocidas como fake news, el periodismo se encuentra ante la necesidad de recuperar la confianza del público. La transparencia, además de cumplir con los principios de ética profesional, puede ser una vía para mejorar la fiabilidad con respecto a la labor informativa. Para lograrlo, los medios combinan desde la apertura de datos hasta la trazabilidad del propio proceso o newsmaking. La tecnología vuelve aquí a incorporarse para ayudar a desarrollar herramientas que favorezcan esa imagen de transparencia informativa.
Conceptualising Global Indigenous and Indigenist models of Inclusive and Equitable Education
Authors: Lindbolm Anne , Jannok Nutti Ylva
Published: September 2022

The role of colonial education systems in the cultural genocide of Indigenous children in many countries is an urgent matter to be meticulously scrutinised in order to address structural inequities. It is time to envision and construct context-based authentically inclusive education.
In this article, we critically examine and address structural inequities in education with examples from our own research in Sámi and First Nations contexts, and discuss possible implications for the inclusive education of all Indigenous children, with emphasis on the early years of
education. Dominant models of special education are displayed followed by conceptualising Indigenous and Indigenist models as ways to reimagine, restructure and inspire the positive change towards inclusive equitable education from early years education and onward for diverse Indigenous children,
and enhance the development of teacher education programmes.
Effect of Sb/Bi atom substitution site on electronic transport properties of Mg2Si0.375Sn0.625 alloy
Authors: Li Xin , Xie Hui , Zhang Ya-Long , Ma Ying , Zhang Jun-Tao , Su Heng-Jie ,   School of Materials Engineering, Xi’an Aeronautical University, Xi’an 710077, China
Published: September 2022

Mg2(Si,Sn)-based thermoelectric materials, which are environmentally friendly and low-cost, have great development potential in a moderate temperature range. Electronic transport properties of Mg2Si1-xSnx alloys can be optimized by doping elements. Doping is still one of the most effective methods of optimizing electronic transport performance, such as carrier concentration, mobility, and effective mass. The most effective doping elements are Sb and Bi. Much attention has been paid to the influence of element type and doping content. Different substitution sites will also greatly affect the electronic transport parameters. In this work, the defect formation energy value of Mg2Si0.375Sn0.625 alloy for substituting Sb atoms and Bi atoms for Sn sties and Si sites, respectively, are calculated by first-principles calculations. The influence on electronic transport parameters is systematically analyzed by combining the calculated results of band structures and density of states. Corresponding component Sb and Bi atoms doped Mg2Si0.375Sn0.625 alloys are prepared by rapid solidification method, and microstructures, Seebeck coefficients, and electrical conductivities of the alloys are measured. Combined with the predicted results by solving the Boltzmann transport equation, electronic transport performances are compared and analyzed. The results indicate that both Sn and Si sites are equally susceptible to Sb and Bi doping, but the Si sites are preferentially substituted due to their lower ∆Ef values. Doped Bi atoms provide a higher electron concentration, and Sb atoms offer higher carrier effective mass. Thus, the maximum σ value of the Mg2Si0.375Sn0.615Bi0.01 alloy is 1620 S/cm. The maximum S value of the Mg2Si0.365Sn0.625Sb0.01 alloy is –228 μV/K. Correspondingly, the highest PF value for this alloy is 4.49 mW/(m·K) at T = 800 K because of the dominant role of S values. Although its power factor is slightly lower, the Mg2Si0.375Sn0.615Sb0.01 alloy is expected to exhibit lower lattice thermal conductivity due to the lattice shrinkage caused by substituting Sb sites for Sn sites. The optimal doping concentration of the Bi-doped alloy is lower than that of the Sb-doped alloy. These results are expected to provide a significant reference for optimizing the experimental performance of Mg2(Si, Sn)-based alloys.
Analysis and FPGA implementation of memristor chaotic system with extreme multistability
Authors: Zhang Gui-Zhong , Quan Xu , Liu Song ,   College of Intelligent Systems Science and Engineering, Hubei Minzu University, Enshi 445000, China
Published: September 2022

The memristor is a kind of nonlinear element with nanometer size, which can enhance the complexity of a chaotic system. With the further research of chaos, several novel nonlinear phenomena have been found by scholars, such as hidden attractors, coexisting attractors and multi-stability. Meanwhile, the extremely multi-stability representation system coexists with the infinite attractors, which has become a hot spot in the field of memristor chaos research in recent years. A general method to construct a chaotic systems of multiple coexistence is to increase the number of equilibrium points of chaotic system by means of control. The introduction of memristor results in the linear distribution of the equilibrium points of chaotic system in space, which are the linear equilibrium points. The existing researches show that chaotic system with extremely multi-stability can produce better chaotic sequence, which can be used in engineering fields such as secure communication. Therefore, it is of great significance to construct chaotic systems with rich dynamic behaviors by using memristors.

In order to further improve the complexity of the chaotic system, a five-dimensional memristor chaotic system is constructed by replacing the coupling parameters in the four-dimensional chaotic system based on Sprott-B with a magnetically controlled memristor. The dynamic behavior of the system is analyzed by bifurcation diagram, Lyapunov exponent spectrum, phase portrait, Poincaré map, dynamic map and other conventional means. The analysis shows that the new system has rich dynamic behaviors: when the system parameters change, the system can produce a large number of chaotic attractors with different topological structures and periodic limit cycles with different periods. When different parameters change, the dynamic characteristics of the system also change; when the system parameters are fixed, the system not only has an offset enhancement phenomenon that depends on the change of the initial conditions, but also shows a very strong sensitivity to the initial values and a great adjustment range of the initial values, which leads the infinite chaos and periodic attractors to coexist, namely extremely multi-stability appears. Finally, the digital circuit of the memristor chaotic system is implemented based on the field programmable gate array (FPGA) technology. The phase portrait captured on the oscilloscope is consistent with that from the numerical simulation, which verifies the correctness and realizability of the memristor system.
The effect of stable cavitation on dendrite growth within ultrasonic field
Authors: Zhang Ying  , Wu Wen-Hua  , Wang Jian-Yuan  , Zhai Wei  ,   School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China
Published: September 2022

Applying ultrasonic waves in liquid alloys produces refined grain structures, which is mainly contributed to ultrasonic cavitation and acoustic streaming. According to the bubbles lifetime and whether are fragmented into "daughter" bubbles, acoustic cavitation can be divided into transient cavitation and stable cavitation. As compared with the transient cavitation, the interaction between stable cavitation bubbles and solidifying alloys have been rarely reported in previous literatures. In this work, the effect of stable cavitation on the dendritic growth of succinonitrile (SCN)-8.3mol.% water organic transparent alloy is systematically investigated by high-speed digital image technique and numerical simulation. It is firstly found that when the bubble migration direction was consistent with that of dendritic growth, the periodic high pressure generated during bubble oscillation process increased the local undercooling, promoting the dendrites growth velocity effectively. Meanwhile, the concentrated stress inside dendrites induced by the linearly oscillation of cavitation bubble could break up dendrites into fragments. Specifically, if there were stable cavitation bubbles suspended around the liquid-solid interface, periodically alternating flow field and high shear force in their surrounding liquid phase was produced. As a result, the nearby dendritic fragments would be attracted to those bubbles and then transformed into spherical grains.
Effect of Different Sb/Bi Substituted Sites on Electronic Transport Properties of Mg2Si0.375Sn0.625 Alloy
Authors: Li Xin  , Xie Hui  , Zhang Ya-Long  , Ma Ying  , Zhang Jun-Tao  , Su Heng-Jie  ,   School of Materials Engineering, Xi'an Aeronautical University, Xi'an 710077, China
Published: September 2022

Mg2(Si, Sn)-based thermoelectric materials, which are environmentally friendly and low-cost, have great development potential at moderate temperature range. Electronic transport properties of Mg2Si1-xSnx alloys can be optimized by doping elements. Doping is still one of the most effective methods for optimizing electronic transport performance, such as carrier concentration, mobility, and effective mass. The most effective doping elements are Sb and Bi. A significant amount of attention has been focused on the influence of element type and doping content. Different substituted sites will also have a great impact on the electronic transport parameters. In this work, the defect formation energy values of Mg2Si0.375Sn0.625 alloys for Sb/Bi atoms substituting Sn/Si sites were calculated by first-principles calculations. The influence on electronic transport parameters was systematically analyzed combined with the calculated results of band structures and density of states. Corresponding component Sb/Bi doped Mg2Si0.375Sn0.625 alloys were prepared by rapid solidification method, and microstructures, Seebeck coefficients, and electrical conductivities of the alloys were measured. Combined with the predicted results by solving the Boltzmann transport equation, electronic transport performance was compared and analyzed. The results indicate that, both Sn and Si sites were equally susceptible to Sb and Bi doping, but the Si sites were preferentially substituted due to their lower ∆Ef values. Doped Bi atoms provided a higher electron concentration, and Sb atoms provided a higher carrier effective mass. Thus, the maximum σ value of the Mg2Si0.375Sn0.615Bi0.01 alloy was 1620 Scm-1. The maximum S value of the Mg2Si0.365Sn0.625Sb0.01 alloy was -228 μVK-1. Correspondingly, the highest PF value for this alloy was 4.49 mWm-1K-1 at T=800 K because the dominant role of S values. Although its power factor was slightly lower, the Mg2Si0.375Sn0.615Sb0.01 alloy was expected to exhibit lower lattice thermal conductivity due to the lattice shrinkage caused by Sb substituting Sn sites. The optimal doping concentration of the Bi-doped alloys was lower than that of the Sb-doped alloys. These results are expected to provide a significant reference for the experimental performance optimization of Mg2(Si, Sn)-based alloys.
Analysis and FPGA implementation of a Memristor chaotic system with extreme multistability
Authors: Zhang Gui-zhong  , Quan Xu  , Li Song  ,   College of Intelligent Systems Science and Engineering, Hubei Minzu University, Enshi 44500, China
Published: September 2022

The memristor is a kind of nonlinear element with nanometer size, which can enhance the complexity of a chaotic system. With the further research of chaos, several novel nonlinear phenomena have been found by scholars, such as hidden attractors, coexisting attractors and multi-stability. Meanwhile, the extremely multi-stability representation system has the coexistence of infinite attractors, which has become a hot spot in the field of memristor chaos research in recent years. The common method to construct a chaotic systems of multiple coexistence is to increase the number of equilibrium points of chaotic systems by means of control. The introduction of memristor results in the linear distribution of the equilibrium points of chaotic systems in space, which is the linear equilibrium points. The extant research shows that chaotic systems with extremely multi-stability can produce better chaotic sequences, which can be used in engineering fields such as secure communication. Therefore, it is of great significance to construct chaotic systems with rich dynamic behaviors by using memristors.
In order to further improve the complexity of the chaotic system, a five-dimensional memristor chaotic system is constructed by replacing the coupling parameters in the four-dimensional chaotic system based on Sprott-B with a magnetically controlled memristor. The dynamic behavior of the system is analyzed by bifurcation diagram, Lyapunov exponent spectrum, phase portrait, Poincaré map, dynamic map and other conventional means. The analysis shows that the new system has rich dynamic behaviors:when the system parameters change, the system can produce a large number of chaotic attractors with different topological structures and periodic limit cycles with different periods. When different parameters change, the dynamic characteristics of the system also change; When the system parameters are fixed, the system not only has an offset enhancement phenomenon that depends on the change of the initial conditions, but also shows a very strong sensitivity to the initial values and a great adjustment range of the initial values, which leads to the coexistence of infinite chaos and periodic attractors namely extremely multi-stability. Finally, the digital circuit of the memristor chaotic system is implemented based on PFGA technology. The phase portrait captured on the oscilloscope is consistent with the numerical simulation, which verifies the correctness and realizability of the memristor system.
Progress of functionalized atomic force microscopy in the study of the properties of nanometric dielectric materials
Authors: Meng Jingyi  , Lu Hong-Wei  , Ma Shile  , Zhang Jiaqi  , He Fumin  , Su Weitao  , Zhao Xiaodong  , Tian Ting  , Wang Yi  , Xing Yu  ,   1. School of Sciences, Hangzhou Dianzi University, Hangzhou 310018, China;,   2. Haining Institute, Hangzhou Dianzi University, Haining, China
Published: September 2022

The rapid development of the electrical and electronic industry requires components with miniaturization, flexibility, and intelligence. As an important material for the preparation of electronic components, dielectric materials need to have excellent dielectric properties such as high breakdown electric field, high energy storage density and low dielectric loss. Due to the lack of ultra-high resolution characterization tools, the research on the improvement of dielectric material properties has remained at the macroscopic level in the past. The invention of atomic force microscopy, a measurement instrument with nanoscale high resolution, has shown unique advantages in the study of nanodielectrics, and the birth of functional atomic force microscopy has made important contributions to characterize the electrical, optical, and mechanical properties of nano-dielectric micro-regions. In this paper, we review the progress of atomic force microscopy, electrostatic force microscopy, Kelvin probe force microscopy, piezoelectric response force microscopy and atomic microscopy-infrared spectroscopy in the study of nanodielectric applications. Firstly, their structures and principles are introduced; secondly, their recent research progress in studying the microscopic morphology, interfacial structure, domain behavior and charge distribution in the nanometer region of dielectric materials is presented, and finally, the problems in the existing research and possible future research directions are discussed.
Design and fabrication of large-area superconducting nanowire single photon detector arrays
Authors: Zhang Xiao  , Lv Jia-Yu  , Guan Yan-Qiu  , Li Hui  , Wang Xi-Ming  , Zhang La-Bao  , Wang Hao  , Tu Xue-Cou  , Kang Lin  , Jia Xiao-Qing  , Zhao Qing-Yuan  , Chen Jian  , Wu Pei-Heng  ,   Reaserch Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210023, China
Published: September 2022

Superconducting nanowire single-photon detectors (SNSPDs) are currently one of the most mainstream single-photon detectors with excellent comprehensive performance, including low time jitter, high efficiency, low dark count and wide spectrum. However, the traditional single-pixel SNSPD suffers from a lack of spatial resolution and a small photosensitive surface, which creates bottlenecks associated with optical coupling efficiency. In addition, a single-pixel detector does not have the photon number resolution ability, whose working speed cannot be further improved due to the existence of dead time. In this case, array devices can make up for the above deficiencies. Therefore, the development of a large-area SNSPD array is the key to free-space photon detection and other applications. In recent years, experimental groups at home and abroad have started relevant research and have made great progress. However, the large-area SNSPD array faces intractable problems, including complex processes, low yield and difficult fabrication, owing to the photosensitive surface consisting of large amounts of superconducting nanowires. At present, the existing studies mainly use three-dimensional technology with complicated process steps to fabricate large array SNSPDs. How to simplify the process has become a research focus.
In this paper, we design a large-area nanowire array structure and propose an innovative plane process. Taking advantage of the property that the electron beam resists HSQ forming a silicon oxide electrical isolation layer after exposure, we fabricate a large array SNSPD with a simplified two-dimensional process and realize dimensionality reduction for the traditional three-dimensional process of a multilayer structure. By measurement in parallel, the devices enjoy high yield with no bad points found. In addition, a fully superconducting electrode is adopted in our design to reduce the thermal effect of resistors. We add series and parallel resistors in the pixels to divide the bias current evenly and expand the array scale optionally. At the same time, we also offer the design details of array SNSPDs, the related simulation of hot spots to verify the rationality of the design, the optimization of the preparation conditions of array devices, measurement scheme formulation and other related work.
This work provides an idea for the design and fabrication of ultra-large array SNSPDs, which is expected to be applied to the fabrication of megapixel array SNSPDs. Combined with an efficient readout circuit, a focal plane photon detection and imaging system with both a large field of view and high sensitivity will be realized.
Ovarian development, spawning season, size at maturity and fecundity of Acentrogobius viridipunctatus (Valenciennes, 1837) in the Vietnamese Mekong Delta
Authors: Dinh Quang Minh , Nguyen Ton Huu Duc , Truong Ngon Trong , Doan Diep Xuan , Nguyen Tien Thi Kieu
Published: September 2022

This present study provides an overview of the reproductive traits, including ovarian development, spawning season, size at maturity (Lm), and fecundity of Acentrogobius viridipunctatus – a high economic value fish in the Vietnamese Mekong Delta (VMD). A total of 432 females were collected using trawl nets from January to December 2020 at four sites, including Long Huu-Tra Vinh (LHTV), Trung Binh-Soc Trang (TBST), Dien Hai-Bac Lieu (DHBL), and Tan Thuan-Ca Mau (TTCM). The ovarian diameter was seen to increase from 2.09 (stage I) to 6.57 mm (stage V). Histological analysis showed that the goby was a multi-spawner due to the different oocyte stages found in stages IV and V of ovaries. It can release eggs all year-round due to the monthly appearance of ovarian stages IV and V during the study period, with the main peak in the 2–4 months of the wet season noted with the highest value of gonadosomatic index at that time. The Lm increased from 6.6 cm at TBST to 9.4 cm at TTCM. This species displayed relatively high fecundity, ranging from 5,481 to 130,683 eggs/female. The average fecundity of this fish was 27,698 ± 7,983 eggs/female at LHTV, 46,592 ± 7,264 eggs/female at TBST, 23,271 ± 4,985 eggs/female at DHBL, and 31,408 ± 2,515 eggs/female at TTCM. Egg diameter ranged from 0.45 ± 0.01 at DHBL to 0.50 ± 0.01 at TBST. For sustainable exploitation, local governments should ask the fishers to avoid catching fish during the main spawning period, and the fish length at first capture should be >Lm.
In situ observation of holopelagic Sargassum distribution and aggregation state across the entire North Atlantic from 2011 to 2020
Authors: Goodwin Deborah S. , Siuda Amy N.S. , Schell Jeffrey M.
Published: September 2022

Between 2011 and 2020, 6,790 visual observations of holopelagic Sargassum were recorded across the North Atlantic Ocean to describe regional distribution, presence, and aggregation state at hourly and 10 km scales. Influences of oceanographic region and wind/sea conditions as well as temporal trends were considered; marine megafauna associates documented the ecological value of aggregations. Holopelagic Sargassum was present in 64% of observations from the western North Atlantic. Dispersed holopelagic Sargassum fragments and clumps were found in 97% of positive observations whereas aggregated windrows (37%) and mats (1%) were less common. Most field observations noted holopelagic Sargassum in quantities below the AFAI algorithm detection limit for the MODIS sensor. Aggregation state patterns were similar across regions; windrow proportion increased with higher wind speeds. In 8 of 10 years in the Sargasso Sea holopelagic Sargassum was found in over 65% of observations. In contrast, the Tropical Atlantic and Caribbean Sea exhibited greater inter-annual variability (1–88% and 11–78% presence, respectively) that did not align with extremes in central Atlantic holopelagic Sargassum areal coverage determined from satellite observations. Megafauna association patterns varied by taxonomic group. While some study regions were impacted by holopelagic Sargassum dynamics in the equatorial Atlantic, the Sargasso Sea had consistently high presence and operated independently. Field observations capture important dynamics occurring at fine spatiotemporal scales, including transient aggregation processes and ecological value for megafauna associates, and therefore remain essential to future studies of holopelagic Sargassum.
Epoxy Sepabeads: A Novel Epoxy Support for Stabilization of Industrial Enzymes via Very Intense Multipoint Covalent Attachment
Authors: Mateo Cesar , Abian Olga , Fernández‐Lorente Gloria , Pedroche Justo , Fernández‐Lafuente Roberto , Guisan Jose M.
Published: July 2002

Sepabeads‐EP (a new epoxy support) has been utilized to immobilize‐stabilize the enzyme penicillin G acylase (PGA) via multipoint covalent attachment. These supports are very robust and suitable for industrial purposes. Also, the internal geometry of the support is composed by cylindrical pores surrounded by the convex surfaces (this offers a good geometrical congruence for reaction with the enzyme), and it has a very high superficial density of epoxy groups (around 100 μmol/mL). These features should permit a very intense enzyme‐support interaction. However, the final stability of the immobilized enzyme is strictly dependent on the immobilization protocol. By using conventional immobilization protocols (neutral pH values, nonblockage of the support) the stability of the immobilized enzyme was quite similar to that achieved using Eupergit C to immobilize the PGA. However, when using a more sophisticated three‐step immobilization/stabilization/blockage procedure, the Sepabeads derivative was hundreds‐fold more stable than Eupergit C derivatives. The protocol used was as follows: (i) the enzyme was first covalently immobilized under very mild experimental conditions (e.g., pH 7.0 and 20 °C); (ii) the already immobilized enzyme was further incubated under more drastic conditions (higher pH values, long incubation periods, etc.) in order to “facilitate” the formation of new covalent linkages between the immobilized enzyme molecule and the support; (iii) the remaining epoxy groups of the support were blocked with very hydrophilic compounds to stop any additional interaction between the enzyme and the support. This third point was found to be critical for obtaining very stable enzymes: derivatives blocked with mercaptoethanol were much less stable than derivatives blocked with glycine or other amino acids. This was attributed to the better masking of the hydrophobicity of the support by the amino acids (having two charges).
Anaerobic Dechlorinating Bacteria
Authors: El Fantroussi Saïd , Naveau Henry , Agathos Spiros N.
Published: July 2002

Anaerobic dehalogenation is attracting great interest since it opens new research horizons based on the novel biochemical mechanisms identified in this field such as halorespiration, i.e. the utilization of halogenated compounds as electron acceptors. Moreover, anaerobic bacteria seem to be more efficient than their aerobic counterparts in removing halogen atoms from polyhalogenated compounds. Thus, anaerobic dehalogenation can be considered as a promising means for bioremediation treatments of persistently polluted environments. In this line, identification of pure strains capable of dehalogenation will give important information about the diversity of organisms implicated in this process and also fundamental explanations of the diverse biochemical mechanisms involved. In light of these considerations, we chose to focus this review on the physiological descriptions, dechlorination activities, phylogenetic diversity, and potential biotechnological applications of these pure anaerobic strains capable of dehalogenation.
Fibrinogen is degraded and internalized during incubation with neutrophils, and fibrinogen products localize to electron lucent vesicles
Authors: KIRSCH Richard , JAFFER Mohamed A. , WOODBURNE Vivienne E. , SEWELL Trevor , KELLY Sharon L. , KIRSCH Ralph E. , SHEPHARD Enid G.
Published: July 2002

A biologically relevant relationship exists between neutrophils and coagulation processes. Several studies have focused on the ability of neutrophil proteases (both intracellular and membrane-associated) to degrade fibrinogen. The present study investigates the events following the interaction of activated neutrophils with soluble fibrinogen. During incubation of PMA-stimulated neutrophils with fibrinogen at 37°C, fibrinogenolysis occurred, and degraded fibrinogen became associated with the neutrophil. Immunoelectron microscopy identified these fibrinogen products to be located within electron lucent vesicles, and not on the surface of the cell, suggesting that they are internalized. Although a specific interaction between fibrinogen and the neutrophil membrane might assist uptake, in the presence of physiological concentrations of fibrinogen, internalization occurred largely via a non-specific pinocytic process. Studies at low temperature revealed that both intact and degraded forms of fibrinogen can associate with neutrophils. The fibrinogen products detected intracellularly in experiments performed at 37°C might represent uptake of degraded as well as intact forms of fibrinogen, the latter being rapidly degraded intracellularly. This route of fibrinogenolysis contributes minimally to the overall extent of the degradation process, the majority occurring extracellularly. Neutrophils thus possess a proteolytic mechanism for preventing accumulation of surface ligand, perhaps allowing them to evade the immunomodulatory effects of such ligands during inflammation.
CCAAT/enhancer-binding proteins: structure, function and regulation
Authors: RAMJI Dipak P. , FOKA Pelagia
Published: July 2002

CCAAT/enhancer binding proteins (C/EBPs) are a family of transcription factors that all contain a highly conserved, basic-leucine zipper domain at the C-terminus that is involved in dimerization and DNA binding. At least six members of the family have been isolated and characterized to date (C/EBPα—C/EBPζ), with further diversity produced by the generation of different sized polypeptides, predominantly by differential use of translation initiation sites, and extensive protein—protein interactions both within the family and with other transcription factors. The function of the C/EBPs has recently been investigated by a number of approaches, including studies on mice that lack specific members, and has identified pivotal roles of the family in the control of cellular proliferation and differentiation, metabolism, inflammation and numerous other responses, particularly in hepatocytes, adipocytes and haematopoietic cells. The expression of the C/EBPs is regulated at multiple levels during several physiological and pathophysiological conditions through the action of a range of factors, including hormones, mitogens, cytokines, nutrients and certain toxins. The mechanisms through which the C/EBP members are regulated during such conditions have also been the focus of several recent studies and have revealed an immense complexity with the potential existence of cell/tissue- and species-specific differences. This review deals with the structure, biological function and the regulation of the C/EBP family.
Assessment of the reliability of 2D inversion of apparent resistivity data
Authors: Olayinka Abel I. , Yaramanci Ugur
Published: July 2002

The reliability of inversion of apparent resistivity pseudosection data to determine accurately the true resistivity distribution over 2D structures has been investigated, using a common inversion scheme based on a smoothness‐constrained non‐linear least‐squares optimization, for the Wenner array. This involved calculation of synthetic apparent resistivity pseudosection data, which were then inverted and the model estimated from the inversion was compared with the original 2D model. The models examined include (i) horizontal layering, (ii) a vertical fault, (iii) a low‐resistivity fill within a high‐resistivity basement, and (iv) an upfaulted basement block beneath a conductive overburden. Over vertical structures, the resistivity models obtained from inversion are usually much sharper than the measured data. However, the inverted resistivities can be smaller than the lowest, or greater than the highest, true model resistivity. The substantial reduction generally recorded in the data misfit during the least‐squares inversion of 2D apparent resistivity data is not always accompanied by any noticeable reduction in the model misfit. Conversely, the model misfit may, for all practical purposes, remain invariant for successive iterations. It can also increase with the iteration number, especially where the resistivity contrast at the bedrock interface exceeds a factor of about 10; in such instances, the optimum model estimated from inversion is attained at a very low iteration number. The largest model misfit is encountered in the zone adjacent to a contact where there is a large change in the resistivity contrast. It is concluded that smooth inversion can provide only an approximate guide to the true geometry and true formation resistivity.
Forces in atomic force microscopy in air and water
Authors: Weisenhorn A. L. , Hansma P. K. , Albrecht T. R. , Quate C. F.
Published: July 2002

A new atomic force microscope, which combines a microfabricated cantilever with an optical lever detection system, now makes it possible to measure the absolute force applied by a tip on a surface. This absolute force has been measured as a function of distance (=position of the surface) in air and water over a range of 600 nm. In the absolute force versus distance curves there are two transitions from touching the surface to a total release in air caused by van der Waals interaction and surface tension. One transition is due to lifting off the surface; the other is due to lifting out of an adsorbed layer on the surface. In water there is just one transition due to lifting off the surface. There is also a transition in air and water when the totally released tip is pulled down to touch the surface as the surface and tip are brought together. Based on the force versus distance curves, we propose a procedure to set the lowest possible imaging force. It can now be as low as 10−9 N or less in water and 10−7 N in air.
Sputter deposition of dense diamond-like carbon films at low temperature
Authors: Cuomo Jerome J. , Doyle James P. , Bruley John , Liu Joyce C.
Published: July 2002

Thin carbon films were deposited by ion beam sputtering at temperatures of 77–1073 K. Using Rutherford backscattering spectrometry and electron energy loss spectroscopy, the trends in film density and bonding were examined as a function of deposition conditions. It has been found that film density and sp3 bonding character unexpectedly increased with increased substrate thermal conductivity and decreasing substrate temperature, reaching values of 2.9 g/cc and 50%, respectively.
Thermal stability of GaN investigated by low-temperature photoluminescence spectroscopy
Authors: Lin M. E. , Sverdlov B. N. , Morkoç H.
Published: July 2002

We have studied the thermal behavior of 1-μm-thick GaN films grown by plasma-enhanced molecular beam epitaxy. Samples were annealed at elevated temperatures in a nitrogen environment and were characterized by low-temperature photoluminescence (PL). After GaN samples were annealed at up to 700 °C, the free-exciton transition PL line intensity improved. This PL line intensity degraded when annealing temperatures reached 900 °C. After annealing at 900 °C, GaN samples with inferior crystalline quality exhibited a line at 2.3 eV attributed to point defects and antisite defects.
Titanium dioxide photocatalysts produced by reactive magnetron sputtering
Authors: Weinberger B. R. , Garber R. B.
Published: July 2002

A process is described for the deposition of anatase titanium dioxide films by reactive magnetron sputtering. The films have a porous columnar morphology with a high effective surface area making them well suited to be used as photocatalysts. Data are presented on the use of such films in the photocatalytic decomposition of gas phase pollutants in air.
Chromatic aberration of symmetric two-cylinder electrostatic lenses
Authors: Vijayakumar P. S. , Szilagyi M.
Published: July 2002

Accurate calculations of the axial chromatic aberration coefficients of symmetric two-cylinder bipotential electrostatic lenses for three different gap values (0.10D, 0.50D, and 1.0D) are presented. This is an extension of the first-order properties and the third-order spherical aberration coefficients published by Harting and Read.
A computer-controlled all-pass phase shift filter for a variable frequency two-phase ac magnetic susceptometer
Authors: Hall D. B. , Knop J. M. , Ayers S. M. , Klemme G. A. , Schreiber G. A.
Published: July 2002

A well-established method for the accurate measurement of small changes in ac magnetic susceptibility is to initially null and then monitor the output of the susceptometer as various parameters are modified. Use of a computer-controlled phase shift filter has allowed us to build a system that will introduce virtually orthogonal signals to compensate for the in-phase and out-of-phase components of the output. The system described is designed for use over the frequency range 50 Hz–4 kHz. Extended frequency ranges are possible with only slight modifications.
Impulse excitation apparatus to measure resonant frequencies, elastic moduli, and internal friction at room and high temperature
Authors: Roebben G. , Bollen B. , Brebels A. , Van Humbeeck J. , Van der Biest O.
Published: July 2002

This paper presents a new apparatus to measure elastic properties and internal friction of materials. The apparatus excites the test specimen by a light mechanical impact (impulse excitation) and performs a software-based analysis of the resulting vibration. The resonant frequencies fr of the test object are determined and, in the case of isotropic and regular shaped specimens, the elastic moduli are calculated. The internal friction value (Q−1) is determined for each fr as Q−1=k/(πfr) with k the exponential decay parameter of the vibration component of frequency fr. A furnace was designed and equipped with automated impulse excitation and vibration detection devices, thus allowing computer-controlled measurements at temperatures up to 1750 °C. The precision of the measured fr depends on the size and stiffness of the specimen, and varies from the order of 10−3 (that is ±1 Hz at 1 kHz) in soft, high damping materials or light specimens, to values as precise as 10−5 (that is ±0.1 Hz at 10 kHz) in larger or stiffer specimens. The highly reproducible Q−1 measurements are accurate whenever the relation Q−1=k/(πfr) holds. The precision of the Q−1 measurement depends on the suspension or support of the specimen, and on the specimen size. Since external energy losses are relatively smaller for larger specimens, the lower limit of measurable Q−1 extends from 10−3 for small specimens (for example <1 g) down to 10−5 with increasing specimen size. High temperature tests have shown that Q−1 can be monitored up to values of about 0.1.
Operation characteristics of piezoelectric quartz tuning forks in high magnetic fields at liquid helium temperatures
Authors: Rychen J. , Ihn T. , Studerus P. , Herrmann A. , Ensslin K. , Hug H. J. , van Schendel P. J. A. , Güntherodt H. J.
Published: July 2002

Piezoelectric quartz tuning forks are investigated for use as force sensors in dynamic mode scanning probe microscopy at temperatures down to 1.5 K and in magnetic fields up to 8 T. The mechanical properties of the forks are extracted from the frequency dependent admittance and simultaneous interferometric measurements. The performance of the forks in a cryogenic environment is investigated. Force-distance studies performed with these sensors at low temperatures are presented.
Exciton diffusion and dissociation in a poly(p-phenylenevinylene)/C60 heterojunction photovoltaic cell
Authors: Halls J. J. M. , Pichler K. , Friend R. H. , Moratti S. C. , Holmes A. B.
Published: July 2002

We report measurements of the photovoltaic response of two-layer photocells formed with layers of the conjugated polymer poly(phenylenevinylene), PPV and fullerene, C60, formed between indium-tin oxide and aluminum electrodes. Peak quantum efficiencies of up to ∼9% (electrons collected per incident photon) were measured under short-circuit conditions. We model the photovoltaic response as arising from excitons photogenerated in the PPV layer which are able to diffuse to the interface with the C60 layer where they are ionized. We obtain a value for the exciton diffusion range of 7±1 nm, both from the spectral response and from the absolute efficiency. We demonstrate that the branching ratio for the creation of singlet excitons from absorbed photons is close to unity.
Passivation of P
b0 and P
b1 interface defects in thermal (100) Si/SiO2 with molecular hydrogen
Authors: Stesmans A.
Published: July 2002

It is found that the passivation of both the Pb0 and Pb1 defects in (100)Si/SiO2 (grown at <750 °C) with molecular H2 may well be described by the same defect- H2 reaction-limited kinetic model applying to interfacial Pb defects in (111) Si/SiO2 grown at 850 °C. Yet, whereas Pb was typified by a single-valued activation energy Ea=1.66 eV, both Pb0 and Pb1 are found to exhibit a Gaussian spread σEa=0.15±0.03 eV around their respective mean Ea values, determined as 1.51 and 1.57±0.04 eV. Such a spread complies with previous electron spin resonance data on stress-induced structural variations within the Pb bath. All three interface defects thus passivate comparably.
Scanning force microscopy measurements of latent image topography in chemically amplified resists
Authors: Ocola L. E. , Fryer D. S. , Reynolds G. , Krasnoperova A. , Cerrina F.
Published: July 2002

Noncontact scanning force microscopy topography measurements of exposed and undeveloped photoresists are reported. A negative chemically amplified photoresist, SAL605, was patterned by electron beam direct writing of 1 μm line linear gratings, and 5 mm pads. A relief image of exposed unbaked resist has been observed of the order of a few Å, and then monitored as a function of time after exposure. This relief image undergoes a topography transformation with postexposure bake (PEB), yielding a ridge located at the exposed–unexposed region interface, extending several nanometers in vertical and about one micrometer laterally. The effect has been investigated as a function of PEB time and exposure dose. Correlations of the observed phenomena with optical film thickness monitoring techniques and previously reported data on the photoresist chemical changes during exposure and PEB are discussed. Two independent mechanisms contributing to the image formation are identified. The data show that the local chemistry of the latent image at the edges of feature is different than in wider features. This has important implications for the application of chemically amplified resists to high-resolution lithography.