bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Evapotranspiration Using SWAT for the Middle Narmada Catchment
Authors: Mishra Rajat , Singh Praveen Vikram , Kumar Anil , Singh Pramod Kumar , Kumar Pravendra
Published: February 2024

This study delves into the hydrological dynamics of a region by analyzing monthly and annual datasets that encompass the intricate interplay among rainfall, potential evapotranspiration (PET), and actual evapotranspiration (ET) using SWAT model for the Gadarwara watershed of middle Narmada catchment. The research identifies a distinct wet season characterized by escalating precipitation from January to June, peaking in July and August. Interestingly, despite heightened rainfall during these months a decline in actual evapotranspiration is discerned, hinting at potential environmental influences. The transition from the wet to the dry season reveals a cyclical pattern culminating in minimal ET values in December. The annual dataset unveils years marked by significant variability in rainfall, ET, and PET, underscoring the region's responsiveness to climatic fluctuations. These insights bear paramount importance for sectors such as agriculture and water resource management, facilitating strategic planning during periods of elevated water availability. Furthermore, the data contributes to the calibration and validation of SWAT, enhancing their reliability in simulating real-world processes. In sum, the comprehensive dataset enhances our understanding of regional hydrology, offering guidance for sustainable water management practices amid evolving climatic conditions.
Effect of Integrated Nutrient Management on Productivity and Quality of Rice
Authors: Singh Hitendra , Pal Sudhir , Kumar Dinesh , Kumar Ashok , Verma Anupama , Sachan Ravindra
Published: February 2024

The present field experiment was conducted at crop research farm Nawabganj of C.S. Azad University of Agriculture and Technology Kanpur, under the Central Plain zone of Uttar Pradesh, during Kharif season of 2018. The experiment comprised of 9 treatment combinations in randomized block design with three replications consisted of T1: Control, T2: 100 % RDF(120:60:60), T3: 75 % RDF + 25 % N as FYM, T4: 75 % RDF + 25 % N as CWC, T5: 75 % RDF + 25 % N as PM, T6: 75 % RDF + 25 % N as FYM + CWC, T7: 75 % RDF + 25 % N as CWC+ PM, T8: 75 % RDF + 25 % N as FYM + PM, T9: 75 % RDF + 25 % N as FYM + PM + CWC. On the basis of the results emanated from present investigation, it could be concluded that application of 75 % RDF + 25 % N as FYM + PM + CWC applied in rice to significantly increases yield attributes, yield and protein content. Results showed that maximum among the different fertility levels, application of T7 [75 % RDF + 25 % N as CWC + PM] significantly enhanced productivity parameters i.e. grain yield and straw yield over the control.
Phytosociological Analysis of Functional Components in Silvipastoral Land Use Systems of Himachal Pradesh, India
Authors: Lata Swaran , Paul Shiv , Chauhan Vivek , Varsha
Published: February 2024

Phytosociological studies are important for devising suitable conservation strategies of the plant genetic resources. Himachal Pradesh is a north-western Himalayan state with diverse landscape having rich and unique floristic diversity. Silvipastoral systems are one among the most prominent agroforestry land use systems which contributes significantly in productivity, ecological balance and livelihood of local communities. Thus, to know the status of floristic and phytosociological diversity in these land use systems, the present study has been conducted from April 2018 to March 2022 in 12 selected villages in Himachal Pradesh. Total number of plant species recorded in study area was 1046 (including 114 tree, 170 shrub and 762 herb species), belonging to 108 families and 538 genera. Poaceae, Asteraceae, Fabaceae, Rosaceae and Lamiaceae were the five most dominant families. Maximum tree density recorded for species Myrica esculenta (980 ind. ha-1) at site 3, Grewia optiva (660 ind. ha-1) at site 2 and Grewia optiva (640 ind. ha-1) at Site 1 Naun, Mandi, followed by Bauhinia variegata (630 ind. ha-1) at Site 2 Banalgi, Solan in zone-II. On the basis of IVI, Cedrus deodara (252.30) was most dominant species followed by Quercus oblongata (193.11), Pinus wallichiana (164.68) and Myrica esculenta (149.10). Among the shrubs Hippophae salicifolia (119.24) was most dominant species followed by Berberis lycium (96.14) and Berberis aristata (90.98). However, Achyranthus aspera (107.66) was most dominant herb species followed by Commelina benghalensis (97.50) and Sonchus asper (44.01). The lowest value of IVI was observed for Capsella bursa-pastoris (9.63) and Tanacetum dolichophyllum (10.54). According to CAMP (Conservation Assessment and Management Prioritization), 2013 nine species viz., Angelica glauca, Berberis aristata, Dioscorea deltoidea, Polygonatum cirrhifolium, Hyoscyamus niger, Bunium persicum, Ephedra gerardiana, Juniperus communis and Selinum vaginatum are threatened and requires conservation and management efforts. In past no study was conducted on floristic and phytosociology diversity of silvipastoral systems of Himachal Pradesh. Hence, present study will definitely act as base line data for further in-depth studies on restoration of degraded lands and silvipastoral system management and improvement programs.
Antiangiogenic Effects of Infliximab in Chick Chorioallantoic Membrane Model
Authors: Duman Reşat , Vurmaz Ayhan
Published: February 2024

Introduction: TNF-α plays a key role in initiating pathologic angiogenesis, however, literature on the effects of infliximab on angiogenesis is limited.

Objective: The study aimed to investigate the effects of infliximab on angiogenesis in an in vivo chick chorioallantoic membrane (CAM) model.

Methods: The study was approved by the local ethics committee on animal experimentation. Thirty fertilized specific pathogen-free eggs were incubated and kept under appropriate temperature and humidity control. On the third day of the incubation, infliximab (1 µmol) dissolved in phosphate-buffered saline in the first group, phosphate-buffered saline (negative control) (0.1 ml) in the second group, anti-VEGF (positive control) (1 µmol) in the third group were administered by injection. On the eighth day of incubation, the vascular structures of the CAMs were macroscopically examined, and standard digital photographs were taken. The digital images were analyzed, and data including mean vessel density, thickness, and number were compared between groups. P < 0.05 was considered statistically significant.

Results: Angiogenesis was significantly reduced in the anti-VEGF and infliximab groups compared to the saline-only group. Vessel thickness, vessel number, and vessel density were significantly less in the infliximab and anti-VEGF groups compared to the saline-only group (p=0.034, 0.029, 0.024, respectively).

Conclusions: Infliximab showed promising antiangiogenic effects in the chick CAM model. Thus, infliximab could be a treatment agent in pathological processes in which angiogenesis is responsible. The antiangiogenic effect of infliximab could be due to the inhibition of various angiogenesis-related cytokines and adhesion molecules. Further studies are needed to clarify the exact mechanisms.
A Review: Application of Cold Plasma in Food Processing Industry
Authors: Karkhanis Riddhi Prasad , Singh Sury Pratap
Published: February 2024

Nowadays, demand for minimally processed food has increased globally very rapidly. However, the food preservation and the period of storage is a key challenge in front of the food processing industry.So to overcome this problem,recently widely used cold plasma technology which is an alternative method for heat treatment. It is a novel, non-heat transferable, nature-friendly, and money-saving technology which does not change the organoleptic characteristics of food and enhances the microbiological quality of food.It helps to preserve the natural aroma and flavour. Cold plasma technology is agrowingtechnique and it has significant potential to decrease the undesirable effects on nutritional as well as quality characteristics of food. The review evaluates the recent status of this technique in the food processing sector. As this is a grow ingmethod which is utilized in several food processing sectors they are listed below. Cold plasma technology shows promising results primarily in shelf life extension as well as in microbial inactivation.
Seismic Response of RCC Buildings on Hill Slopes with Step Back and Step Back - Set Back Configuration
Authors: Singh Rajendra , Sekhawat R. S. , Gupta Trilok
Published: February 2024

Framed structures constructed on hill slopes have different structural behavior than those on flat ground due to the scarcity of flat land. As these buildings are unsymmetrical, they attract large amounts of shear forces and torsional moments, leading to unequal distribution due to varying column lengths. In this study, the dynamic response of hill buildings has been compared with step back and step back set back building without and with bracing at corner of the building in terms of maximum storey stiffness and storey displacement. Two different types of buildings have been modeled and analyzed using ETABS v 18.0 finite element code. A parametric study has been conducted, in which hill buildings are geometrically varied in height of the structure due to hill slope. All sixteen analytical models have been subjected to seismic forces along and across the hill slope direction and analyzed by using the Response Spectrum Method.

All 16 models were analysed using ETABS v18. Three dimensional space frame analysis is carried out for four different configurations such as step back buildings with bracings at corner of the building, step back buildings without bracings, step back and set back building with bracings at corner of the building, step back and set back building without bracings. The maximum storey stiffness and storey displacement for the step back and step back-setback buildings with and without bracing are at 15 ͦ and 30 ͦ, respectively, compare with bracing buildings, the value in step back & step back set back building drastically decreases, resulting in the stability of the building.
The European Ceramic Society (ECerS)
Authors: Metselaar Rudi
Published: May 2005

The European Ceramic Society (ECerS) is a federation of ceramic societies from eleven European nations. The Society was run for the first two years of its existence by the Dutch ceramists but now control has passed over to the Germans who will direct matters for the next two years. The first president of the new Society explains its aims and constitution.
High resolution solid state NMR of quadrupolar nuclei
Authors: Blümich Bernhard
Published: May 2005

Dynamic Angle Spinning (DAS) and Double Rotation (DOR) solid state NMR are two new methods which have recently been applied to the study of elements with half‐integral quadrupolar spins. An increase in resolution is achieved over magic angle spinning (MAS) NMR by spinning the sample at two different angles, either sequentially (DAS), or simultaneously (DOR).
How to tailor molecular electronics or why is nature taking the ‘soft’ approach
Authors: Haarer Dietrich
Published: May 2005

Nature performs “molecular electronics” with astounding efficiency. Now, researchers attempt to duplicate these processes in order to produce, for example, molecular switches. The recent direction of molecular electronics work has been towards ever increasing miniaturization but this is in fact not how nature approaches the problem. The current status of human “molecular electronics” is assessed and compared with nature's highly successful version.
Highly conjugated, substituted polyacetylenes via the ring‐opening metathesis polymerization of substituted cyclooctatetraenes
Authors: Grubbs Robert H. , Gorman Christopher B. , Ginsburg Eric J. , Marder Seth R.
Published: May 2005

Soluble polyacetylenes with high conjugation length and high molecular weight are a goal of polymer scientists. The ring‐opening metathesis polymerization of substituted cyclooctatetraenes (COT) to form soluble substituted polyacetylenes which display iodine doped conductivities in the range 0.1 to 50 S/cm are reported. The solubility is imparted by the alkyl groups which occupy, on average, every eighth carbon atom of the polymer backbone.
Ceramics in Maastricht
Authors: Brook Richard J.
Published: May 2005

Richard Brook reports on the first meeting of the newly formed European Ceramic Society, Tord Eriksson on a meeting in Sweden on chromogenic materials, Bernd Eigenmann on the annual meeting of the German Metallurgical Society (DGM) during which the Society changed its name, and Jean‐Paul Behr describes a recent top meeting on information storage held in France.
Nuclear magnetic resonance imaging of polymers and polymer composites
Authors: Jezzard Peter , Wiggins Christopher J. , Carpnter T. Adrian , Hall Laurance D. , Jackson Peter , Clayden Nigel J. , Walton Nicholas J.
Published: May 2005

Since its inception in the early 1970s, the nuclear magnetic resonance (NMR) imaging technique has developed to the point that it is now used as a routine clinical diagnostic tool in many hospitals. As a result, virtually all; research in NMR imaging was until recently directed towards mapping the water and lipid distribution contained in human soft tissue, and it is only within the last few years that a start., has been made in exploring the non‐medical applications of NMR imaging. In this review article we discuss some of the many applications of NMR imaging to studies of the production and evaluation of 'advanced materials', particularly polymers and polymer composites, and review some ofthe studies which have already been undertaken. It is hoped that this article will be read both by polymer scientists and engineers interested in this powerful new research tool for studying their materials, and also by those already involved in other aspects of NMR imaging who are seeking challenging new problems.
On the relation between charge‐storage capacity and π‐topology of different oligonaphthylenes
Authors: Anton Ute , Bohnen Angelika , Koch Karl‐Heinz , Naarmann Herbert , Räder Hans Joachim , Müllen Klaus
Published: May 2005

The relationship between charge‐storage capacity and π‐topology in conjugated polymers needs to be understood in order to optimize polymer structuress for use in, for example, anodic electrodes in secondary lithium battery elements. Cyclic voltammetry has been used to study the redox behavior of conjugated oligomers related to that shown in the figure.

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Interpenetrating organometallic polymer networks: Synthetic and morphological aspects
Authors: Corain Benedetto , Zecca Marco , Jeřàbek Karel , Lora Silvano , Palma Giancarlo
Published: May 2005

A molecular composite representing a new way of dispersing metal centers on solid supports is reeported. Co‐polymerization of vinylferrocene with dimethyl‐acrylamide in the presence of a cross‐linker inside a polyacrylamide resin matrix results in an interpenetratiing organometallic polymer network based on the unit ssshown in the figure.

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End‐capped oligothiophenes—new model compounds for polythiophenes
Authors: Bäuerle Peter
Published: May 2005

New end‐capped oligothiophenes (see figure) have been synthesized via nickel‐catalyzed Grignard cross‐coupling reaction. Dueto the reactive positions in the terminal thiophene units being blocked it is possible to accurately characterize the spectroscopic and electrochemical properties of the materials. Estimation of the properties of an 'ideal' polythiophene consisting of 'infinite' chains can be made via extrapolation.

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Poly(alkylenedioxythiophene)s—new, very stable conducting polymers
Authors: Heywang Gerhard , Jonas Friedrich
Published: May 2005

The stabililty of conducting polymerss is enhanced by the presence in the doped polymer structure of substituents which are able to stabilize prositive charge while having only minor steric effects. The insufficient stability of conducting poplymers has greatly hindered their wide application but the title compounds have recently been shown to fullfil the above requirements and their synthesis, properties, and potential applications are described.
Metal dithiolene complexes for all‐optical switching devices
Authors: Oliver Stephen , Winter Christopher
Published: May 2005

Optical data storage, transmission, and handling will require a means to carry out all‐optical switching of information if semiconductor‐based electronics are not to become a serious bottle‐neck for the technology. The various materials which aree being examined wiith a view of this application are reviewed are some recent progress made with metal dithiolene complexes (see figure) described.

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Raman scattering in high‐ Tc, superconductors
Authors: Thomsen Christian
Published: May 2005

The non‐destructive analysis of superconductors is made possible by Raman scattering techniques. A number of fundamental properties can be examined due to the coupling of electronic system of the materials with the phonons which are actually measured in Raman scattering, including the superconducting energy gap and the Fermi velocity. The aspects of materials characterization are reviewed and the insight and which Raman scattering experiments offer into electron‐phonon coupling discussed.
Structure–property relationships determining the spontaneous polarization in FLC‐polymers
Authors: Poths Holger , Zentel Rudolf , Schönfeld Axel , Kremer Friedrich , Siemensmeyer Klaus
Published: May 2005

Ferroelectric liquid crystals (FLCs) have great potential in the future development of high‐resolution displays. A key requirements for their application is an understanding of the relationship between the molecular structure of the liquid crystals and their spontaneous polarization (P8) which in turn influences the switching speed of the materials. Here, it is shown that bulky substituents, which hinder rotation about the long axis of the mesogens (see figure) lead to a higher P8.

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Growth of cubic (100) SrTiO3 thin films by plasma‐enhanced chemical vapor deposition using a novel titanium precursor
Authors: Holzschuh Helga , Suhr Harald
Published: May 2005

Plasma‐enhanced CVD has been used, together with a new titanium precursor (see Figure), for the deposition of epiaxed (100) SrTiO3 thin films at a growth temperature of 500 ° C. In technical applications (100) SrTiO3 thin films have been found to be the ideal substrate for the growth “1‐2‐3‐” superconductors due to the perfect lattice match. The new precursor is easy to synthesize handle, and is stable against air and moisture.

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Atom‐selective imaging of n‐conductive crystals of the ordered phase TlSbSe2 by scanning tunneling microscopy
Authors: Stocker Wolfgang , Salk Manfred , Wacker Klaus , Magonov Sergei N. , Cantow Hans‐Joachim
Published: May 2005

Element‐specific visualization of the (001) surface of n‐conducting crystals of the ordered phase of TlSbSe2 has been achieved using scanning tunneling microscopy (STM). The interpretation of the STM images is fully consistent with a refined evaluation of the crystallographic data, and the two types of surfaces within the unit cell are confirmed.
Measuring dynamic surface and interfacial tensions
Authors: Miller Reinhard , Hofmann Armin , Hartmann Rainer , Halbig Andreas , Schano Karl‐Heinz
Published: May 2005

The surface and interfacial tensions of pure liquids and surfacttant solutions can be measured using a variety of techniques including the drop volume method (see Figure) and the ring or plate method. The various methods are briefly discussed and an automated version of the drop volume method which reliably produces results of the highest quality presented.
Characterization of lanthanum sulphides
Authors: Dunleavy Michael , Allen Geoffrey C. , Paul Michael
Published: May 2005

With application in infrared lenses, lanthanum sulphide and calcium lanthanum sulphide are ceramic materials which require a low defect density in order to minimize light scattering and maximize mechanical strength. Solution routes to monodispersed ceramics are investigated, offering materials with improved packing in the green body and considerable energy saving through the lower preparation temperatures.
Nonlinear optical materials for integrated optics: Telecommunications and sensors
Authors: Dorn Reimund , Baums Dieter , Kersten Peter , Regener Rolf
Published: May 2005

The status of advanced nonlinear optical materials is reviewed with regard to the requirements implied by their respective applications. Although many functions utilizing nonlinear optical (NLO) materials have been demonstrated in research laboratories, only a few components have found a place in real systems. While this is partly due to a lack of product development effort, the performance of the materials is not adequate in other cases. III–V based semiconductors show promise for a broad penetration of the field of signal processing for telecommunications and data processing. Linear and nonlinear optical polymers may be applied in assembly and interconnection and in small to medium sized switching matrices. As a prerequisite the anticipated performance has to be achieved, and stability to be demonstrated. Manufacturing maturity is approached by inorganic ferroelectrics, LINbO3being the most prominent example.
Nanostructured Materials
Authors: Gleiter Herbert
Published: May 2005

The heterogenous structure of nanostructured materials distinguishes them from materials such as glasses which have a homogeneously disordered microstructure. In the figure, the atoms marked in black are in the center of the grains, the white one forming the surface of the individual grains, this structure resulting in the remarkable properties of the materials.

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Synthesis and characterization of a tetra‐alkylated alpha‐conjugated duodecithiophene
Authors: Yassar Abderrahim , Delabauglise Didier , Hmyene Mohamed , Nessak Belkassem , Horowitz Gilles , Garnier Francis
Published: May 2005

An understanding of the doping process in polythiophene is a step closer with the synthesis and characterization of tetradecylduodecithiophene (see figure), the longest oligomer of thiophene so far isolated, which is soluble and acts as an effectife model for the polymer.

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A route to boron nitride via new BN precursors
Authors: Schmid Günter , Piontek Thorsten
Published: May 2005

Boron nitride films are of great potential interest due to their hardness and chemical inertness. A new method for their production is proposed based on oligomeric BN precursors. The procedure requires less energy and less general expenditure than previous methods and could now make BN films attractive for application. Details are given and the method and products compared with those of older procedures.
Preparation of mixtures of silicon oxynitride and silicon nitride by the reaction of calcium silicide with ammonium chloride
Authors: Hofer Ferdinand , Veigl Walter , Hengge Edwin
Published: May 2005

Silicon nitride and silicon oxynitride materials have great potential for high‐temperature, load‐bearing applications because of their high strength, high thermal shock resistance and good oxidation resistance. The subnitride (Si3N)n formed by the known reaction of CaSi2 with ammonium halides is shown here to react with nitrogen providing a new route to, for example, silicon nitride fibers (see figure).

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Poly(glucose‐pyrrole) modified electrodes: A novel chiral electrode for enantioselective recognition
Authors: Moutet Jean‐Claude , Saintl‐Aman Eric , Tran‐Van François , Angibeaud Pierre , Utille Jean‐Pierre
Published: May 2005

Chiral electrode materials possessing enantioselective recognition properties or capable of performing chiral electrosynthesis are of great potential interest. The synthesis of a chiral pyrrolic monomer (see figure) and the enantioselective properties of the modified electrode surface obtained upon its polymerization are reported.

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Poly(isothianaphthene–bithiophefe): A new regularly structured polythiophene analogue
Authors: Lorcy Dominique , Cava Michael P.
Published: May 2005

A new, low band‐gap polymer(see figure), a hybrid of polythiophene and polyisothianaphthene, has been synthesized. Current interest in the synthesis of low bandgap polymers is considerable in view of their potentially superior conductivity and nonlinear optical properties. The results complement well the independent analogous work reported by Bäuerle et al. in the following article.

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Metal‐catalyzed alkynylation of (bromophenyl)‐oligophenylene. A rapid route to thermoset precursors of high density monolithic glass‐like carbon
Authors: Stephens Eric B. , Tour James M.
Published: May 2005

High‐density glass‐like carbon has numerous applications in the aerospace, electronic, medical implant and automotive industries. Much effort has been devoted to limiting the number of impregnation cycles necessary for the preparation of carbon in this form, and now it has been shown that organometallic methods permit a two‐step (oligomerization and functionalization) entry into thermoset precursors for high‐density glass‐like carbon.
Transformation of a kinetically prohibited mesophase of a linear polymer into an enantiotropic mesophase via cyclization
Authors: Percec Virgil , Kawasumi Masaya
Published: May 2005

The synthesis of a novel family of liquid crystals, cyclic compounds without chain ends, raises a series of fundamental questions, since many technological applications of conventional rod‐like low molecular weight liquid crystals rely on teh chain ends for alignment. The figure shown the conformation of the cyclic tetramer in the nematic phase.

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Synthesis of Gallane‐Amine adducts as potential precursors for GaAs and (AlGa)as MOVPE processes and the crystal structure of the {gallane · 1,3‐bis(dimethylamino)propane} adduct H3Ga · N(CH3)2(CH2)3N(CH3)2
Authors: Lorberth Jörg , Dorn Reiner , Wocadlo Sigrid , Massa Werner , Göbel Ernst O. , Marschner Thomas , Protzmann Harry , Zsebök Otto , Stolz Wolfgang
Published: May 2005

Novel gallane‐amine adducts have been synthesized and tested as alternative sources for the epitaxial growth of GaAs and (AlGa)As thin layers by metal organic vapor phase epitaxy. These precursors solve the problem of unwanted incorporation of carbon that arises with standard metalorganic sources. A single‐crystal X‐ray diffraction study provides more detailed insight into the molecular geometries of gallane‐amine adducts.
The colloidal process: A new approach to advanced ceramics
Authors: Sugita Kiyoshi
Published: May 2005

A third route to advanced ceramics, in addition to the traditional sintering and deposition‐from‐gas approaches, is provided by the colloidal process. This produces ceramic materials from solution precursors via a “colloidal state”. The various stages of the process are considered, along with applications, including the preparation of new derivatives, and commercialization.
Containerless processing: A route to high‐purity materials
Authors: Nanko Makoto , Ishizaki Kozo
Published: May 2005

Minimization of contamination is particularly important in the preparation of semiconductors and special glasses. A technique is presented in which contamination from the crucible during melting is avoided by suspending the material in high pressure gas. A particular application is the production of perfect spheres. The figure shows a perfect sphere of polyethylene formed by melting a cube like that on the left.

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Bioabsorbable surgical composite materials
Authors: Törmälä Pertti
Published: May 2005

Biomaterials, materials that are used in medical devices such as surgical implants, are often no longer biostable materials, for example metals or plastics, but bioabsorbable materials, which are degraded and digested in the body. These have the advantage that an operation to remove implants such as bone fracture fixation pins, screws and plates can be avoided. The work is aimed at developing self‐reinforced bioabsorbable composites for use in fracture fixation, and in creating new tissues and artificial organs.
Materials research for advanced solid‐state electronic devices
Authors: Gibbons George
Published: May 2005

GEC‐Marconi Materials Technology (GMMT) is actively engaged in a broad‐based program of research in semiconducting materials. George Gibbons, the technical director of the GMMT Caswell laboratory, introduces some of this work, which is then described in more detail in several other articles in this issue by members of the laboratory. Interest is focused on how materials technology drives the progress made in solid‐state devices and circuits, with the next big advance being expected in the development of optoelectronic integrated circuits.
Advanced materials for GaAs Microwave Devices
Authors: Smith Robin S. , Eddison Ian G.
Published: May 2005

A number of III–V compound semiconductors have higher electron mobilities and peak electron velocities than silicon. This makes these materials attractive for use in high‐frequency applications. However, the use of these materials was delayed for a number of years by the fact that, most of these compounds such as GaAs lack a stable native Oxide and display a large interface trap density at the junction with other materials. These problems were overcome in the early 1960s by the development of the MESFET (metal semiconductor FET) where the control electrode was formed; by a metal Schottky contact directly onto the GaAs surface. Early devices were fabricated in epitaxial conducting layers deposited, by for example vapor phase epitaxy, onto GaAs substrates. As the quality of these substrates improved, the conducting layers were formed by implantation of silicon ions directly into the substrate surface. The requirement for devices working at even higher frequencies has necessitated the move from implanted MESFETs to more complicated multi‐layer heterostructures, for devices such as HEMTs (high electron mobility transistors) and HBTs (heterojunction bipolar transistors), which can only be produced using epitaxial techniques. In this article the technique of ion‐implantation and molecular beam epitaxy are described together with a description of HEMTs and HBTs.
Plasma sprayed anti‐reflection coatings for microwave optical components
Authors: Osbond Paul
Published: May 2005

Plasma spraying of anti‐reflection (AR) coatings onto high permittivity microwave ceramics is a very attractive novel technique for minimizing reflections from optical components. This technique should be able to supersede conventional solutions to the loss of power by reflections, such as the ‘moth‐eye’ AR surface (see Figure). Plasma spraying avoids the machining problems presented by the size and spacing of the protuberances required for ‘moth‐eye’ AR surfaces for microwave optical ceramic components.

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Novel piezoelectric materials
Authors: Twiney Robert C.
Published: May 2005

The unique properties of piezopolymersendow them with particular advantages for use in electroacoustic devices such as the self‐supporting dome hydrophone shown in the Figure. Thin or especially thick films can be fabricated, and three‐dimensional forming of the materials can be accomplished by standard techniques. Further interesting possibilities offered by incorporating a ferroelectric ceramic into a non‐electroactive polymer matrix are sketched.
A new technique for characterizing the porous structure of materials: Standard porosimetry of polyaniline emeraldine salts and bases
Authors: Volf'kovich Yuril M. , Zolotova Tamara K. , Levi Michael D. , Letuchy Yakov A.
Published: May 2005

Standard porosimetry is a new technique for measuring the pore radius distribution in microporous materials. Comparison of the porous structure parameters obtained by this technique and by gas adsorption measurements and SEM, both established methods, on polyaniline emeraldine salts and bases demonstrates that standard porosimetry can be used for the characterization of the porous structure of powders of conductive polymers and that this novel method has several advantages.
First tetrathiafulvalene (TTF) cation‐radical salt containing the inorganic polyoxometalate β‐[Mo8O26]4⊖
Authors: Gómez‐García Carlos J. , Coronado Eugenio , Triki Smaïl , Ouahab Lahcène , Delhaes Pierre
Published: May 2005

Polyoxometalate complexes are attractive precursors for the preparation of new radical‐ion salts based on π‐electron organic donors of the tetrathiafulvalene (TTF) type, the most widely used molecules in the synthesis of organic conductors and superconductors. The well‐defined sizes and shapes of polyoxometalates, as well as their ability to undergo multiple electron reduction, may induce novel structural and electronic properties in the organic component. The preparation and the X‐ray crystal structure analysis of the new compound (TTF)7Mo8O26 are presented.
Advances in negative Poisson's ratio materials
Authors: Lakes Roderic
Published: May 2005

Solids that become fatter in cross‐section when stretched are rare, but do exist. How such materials—which have a negative Poisson's ratio—can be created with specific properties, the implications of these unusual properties, and recent advances are discussed. The Figure shows an example of a negative Poisson's ratio structure with mechanical isotropy in two dimensions: the laminate of Milton.

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Electrorheological fluids — structure and dynamics
Authors: Halsey Thomas C.
Published: May 2005

Electrorheological fluids are colloidal suspensions that solidify under the influence of electric fields, due to the fact that electric fields induce interactions between particles arising from either the dielectric or the conductivity response of the particles. These interactions are principally dipolar at long distances. However, because of the image forces induced by constant potential electrodes, the long range dipolar repulsion is suppressed. It follows that the ground state of the system consists of a macroscopic phase separation into regions of high and low particle concentrations. The mechanism by which the suspension approaches this phase separation may be strongly dependent on thermal fluctuations. In hydrodynamical flows, these suspensions behave as shear‐thinning “Bingham plastics”.
Poly(naphtho[2,3‐c]thiophene‐alt‐bithiophene): A novel low band gap polymer
Authors: Lakshmikantham M. V. , Lorcy Dominique , Scordilis‐Kelley Chariclea , Wu Xiang‐Li , Parakka James P. , Metzger Robert M. , Cava Michael P.
Published: May 2005

A naphtho[2,3‐c]thiophene‐containing mixed polymer (Figure sows this unit) has been synthesized. Such materials have low band gaps and as a result are of interest for potential application in nonlinear optics. Synthetic details are presented and the propeties of the new material compared with those predicted on the basis of MNDO calculations.

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Preparation and characterization of microporous metal oxides
Authors: Maier Wilhelm F. , Tilgner Ingo‐Carsten , Wiedorn Michael , Ko Hee‐Chan
Published: May 2005

The reliable preparation of microporous membranes capable of molecular‐size exclusion requires the availability of stable microporous and uniform inorganic oxides with a monomodal and narrow pore‐size distribution and a pore diameter maximum below 1 nm. A new method of pore‐size analysis is presented and the optimization of the sol‐gel process used to produce the microporous oxides discussed.
Microporous inorganic membranes: Preparation, characterization and separation properties
Authors: Maier Wilhelm F. , Tilgner Ingo‐Carsten , Wiedorn Michael , Ko Hee‐Chan , Ziehfreund Andreas , Sell Rainer
Published: May 2005

Inorganic membranes, which are chemically, thermally, and mechanically resistant and which can be thermally regenerated, offer a number of potential advantages over organic polymer membranes. Here, microporous silica, aluminia, titania, and zirconia (see Figure) membranes on commercially available supports are reported which exhibit remarkable separation behavior, far beyond the cutoff range of common ultrafiltration.

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Glasses, ceramics, and glass‐ceramics containing carbon or nitrogen
Authors: Partridge Graham
Published: May 2005

Non‐oxide ceramics, for example SiC, Si3N4 and other carbides and nitrides, have been shown to have properties, particularly at elevated temperatures, which make them suitable for use under exacting environmental conditions. These materials are discussed along with partially carbon‐ and nitrogen‐substituted glasses and ceramics such as sialons (Si‐Al‐O‐N) and other oxynitride phases. The preparation and sintering characteristics as well as properties and applications are reviewed.
Molecular materials for second‐order nonlinear optical applications
Authors: Marder Seth R. , Perry Joseph W.
Published: May 2005

Strategies for the optimization of molecular second‐order nonlinearities have emerged over the past few years, but significant questions still remain. This review highlights recent conceptual advances in the field of nonlinear optical molecular materials, concentrating on design criteria for the molecules themselves, e.g., the influence of resonance structures, bond length alternation, and reduced aromaticity, and the use of organometallic compounds and octupolar molecules. Factors affecting the properties of bulk materials composed of such molecules are also discussed.
Gas phase molecular modeling of liquid crystals: Electro‐optical anisotropies
Authors: Bremer Matthias , Tarumi Kazuaki
Published: May 2005

Molecular modeling of liquid crystals is important as it provides information without the need for chemical synthesis. The first ever quantitative correlation of semiempirically obtained quantities with electro‐optical parameters measured in 80 bulk liquid crystals is reported here. The Figure shows the calculated relative energy of an LC as a function of two torsion angles.

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New HTSCs—still far below room temperature
Authors: Majewski Peter
Published: May 2005

Tcs climb, but although superconductivity at liquid nitrogen temperatures has become almost commonplace there is still a long way to go before room temperature is reached. Recent progress is discussed in the optimization of the preparation parameters and superconducting properties of the “classical” high‐temperature superconductors (HTSCs) of the YBCO and BSCCO series, and possible future directions in the search for new HTSCs (preferably ones that do not include toxic element such as Hg) are suggested.
Crystal structures of oligothiophenes and their relevance to charge transport
Authors: Hotta Shu , Waragai Katsunori
Published: May 2005

The crystal structures and morphologies of oligothiophenes, in the form of both single crystals and thin films, are reviewed and compared with those of other oligomers and conducting polymers. The “herringbone” structure emerges as a pivotal motif, in particular for charge transport. Although further research is necessary to elucidate the charge transport mechanism, this does not prevent the structural and electronic features of conducting oligomers being exploited in electronic devices such as FETs and LEDs.
Side chain influence on mesomorphic properties: Low‐temperature melting of metal‐containing liquid crystals
Authors: Maldivi Pascal , Bonnet Laurence , Giroud‐Godquin Anne‐Marie , Ibn‐Elhaj Mohammed , Guillon Daniel , Skoulios Antoine
Published: May 2005

Metal‐containing liquid crystals offer the possibility of obtaining mesogenic materials with novel electronic properties. However, the transition temperatures need to be reduced before applications can be found. The authors describe the first fully characterized metallomesogens with an authentic columnar mesophase near room temperature, which were obtained by inserting carbon‐carbon double bonds as the “R” group in te carboxylate ligands (see Figure).

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Ultrathin films of cellulose on silicon wafers
Authors: Schaub Matthias , Wenz Gerhard , Wegner Gerhard , Stein Andreas , Klemm Dieter
Published: May 2005

The first preparation of thin films of cellulose itself is reported. Cellulose exhibits excellent wetting behavior, is extremely stable against oxidation and other chemical degradation and in thin‐film form would have a number of applications. The method involves the preparation of LB films of trimethylcellulose (see Figure) and the in situ conversion of these thin films on silicon substrates to cellulose.

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Electroluminescence from oligothiophene‐based light‐emitting devices
Authors: Geiger Friedhelm , Stoldt Marion , Schweizer Heinz , Bäuerle Peter , Umbach Eberhard
Published: May 2005

The first LEDs based on oligothiophenes are reported. Polymer‐based devices have the advantages that their physical properties can be tailored, they can be easily fabricated, and they can emit all colors, but they have poor stability, a high impurity level, and low luminance. The systematic study of the electroluminescence properties of oligothiophenes described here is aimed to isolate the effects of various parameters, by controlling the structure of the oligomers used, and to extrapolate the results to polymers for use in LEDs.
Highly ordered films of neat calix[4]arenes for second order nonlinear optics
Authors: Kelderman Erik , Heesink Gerard J. T. , Derhaeg Lode , Verbiest Thierry , Klaase Piet T. A. , Verboom Willem , Engbersen Johan F. J. , van Hulst Niek F. , Clays Koen , Persoons Andre , Reinhoudt David N.
Published: May 2005

In substituted calix[4]‐arenes—cyclophanes consisting of four phenol moieties connected by methylene bridgesthe number and also the relative positions of the donor and/or acceptor π‐conjugated (D‐π‐A) units can be varied by changing the configuration. The Figure illustrates the cone configuration. The molecular and thin‐film NLO properties of three tetra‐D‐π‐A‐substituted calix[4]arenes, including their orientation in thin films and the stability of their NLO properties, are described.

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Scanning probe surface modification
Authors: Corbitt Thomas S. , Crooks Richard M. , Ross Claudia B. , Hampden‐Smith Mark J. , Schoer Jonathan K.
Published: May 2005

Nanometer‐scale manipulation of surfaces by scanning probe devices has expanded amazingly since the first reports in the mid‐1980s. General approaches to scanning probe microscope induced surface patterning are discussed. The Figure shows a scanning electron micrograph of an STM‐defined pattern of a HS(CH2)17CH3 monolayer resist on a Au(111) substrate.

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Polymers and the Environment— current problems and future research
Authors: Wegner Gerhard , Wagemann Kurt
Published: May 2005

Is waste disposal by physical recycling always the best solution? Taking plastics as an example, the various alternatives—physical recycling, chemical recycling, thermal recycling, biologically degradable polymers—and the problems connected with them—separation of mixtures, additives, the need to keep biodegradable and other polymers separate—are examined. Topics for future research are proposed.
Molecular Magnetism: A basis for new materials
Authors: Gatteschi Dante
Published: May 2005

Molecular magnetism, which includes the study of organic magnets, spin cross‐over, and large spin clusters, has recently begun to concentrate on the design and synthesis of new magnetic compounds. Simple molecules, based on nitroxides and nitronyl nitroxides (see Figure), have been found to order ferromagnetically. The field is reviewed, stressing the possibility of combining properties.

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Scanning probe microscopy study of the incommensurate modulation and surface defects in the layered telluride TaGe0.355Te2
Authors: Bengel Hardy , Cantow Hans‐Joachim , Magonov Sergei N. , Monconduit Laure , Evain Michel , Liang Weigen , Whangho Myung‐Hwan
Published: May 2005

The detection of atomic‐size defects by atomic force microscopy (AFM) is demonstrated. For example, the dark grooves in the image of the surface of the incommensurate layered telluride phase TaGe0.355Te2 (see Figure) indicate a defect. The origin of this incommensurate structure of layered tellurides is established and it is shown that high applied forces enhance the image contrast in AFM.

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Channel‐to‐channel rearrangements of host lattices in clathrate crystals induced by guest exchange via Gas‐solid contacts
Authors: Hayashi Naoto , Mazaki Yasuhiro , Kobayashi Keiji
Published: May 2005

Host‐lattice rearrangements in clathratesas a result of sorptive gas exchange are reported for the first time. Unlike any other clathrates, those produced by the recrystallization of bis(9‐hydroxyfluoren‐9‐yl)thieno‐[3,2‐b]thiohene from ethanol andn‐propanol exhibit guest‐responsive channel‐type cavities: their structure differs for the guest ethanol and propanol. The structures, lattice rearrangements and guest displacement of the system are discussed.
Paramagnetic metal‐containing mesogenic polyazomethines
Authors: Alonso Pablo J. , Martínez Jesús I. , Oriol Luis , Piñol Milagros , Serrano José Luis
Published: May 2005

Paramagnetic moieties in mesogenic polymers can provide valuable information about macromolecular orientation. The results of EPR and polarized light investigations on three polyazomethines bearing hydroxyl groups and containing paramagnetic centers are reported. The micrograph in the Figure shows the threaded texture of a polyazomethine, derived from naphthalenediamine, containing oxovanadium(IV) centers.

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Voltammetric studies of solution and solid‐state properties of monodisperse oligo(p‐phenylenevinylene)s
Authors: Meerholz Klaus , Gregorius Heike , Müllen Klaus , Heinze Jürgen
Published: May 2005

Four well‐defined monodisperse oligo(p‐phenylenevinylene)s (see Figure, n = 3 to 6) have been used in solid‐state voltammetric investigations as model compounds for the related polymer. The redox behavior in solution and in the solid state is compared and an interpretation of the controversial “current plateau” proposed.

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Thermally stable multilared organic electroluminescent devices using novel starburst molecules, 4,4′,4″‐Tri(N‐carbazolyl)triphenylamine (TCTA) and 4,4′,4″‐Tris(3‐methylphenylphenylamino)triphenylamine (m‐MTDATA), as hole‐transport materials
Authors: Kuwabara Yoshiyuki , Ogawa Hiromitsu , Inada Hiroshi , Noma Naoki , Shirota Yasuhiko
Published: May 2005

Organic electroluminescent devices with improced thermal stability and good performance characteristics are reported. The hole‐transport material is a novel π‐electron “starburst” molecule, TCTA (see Figure), whose glass‐transition temperature is increased by the introduction of a structurally rigid moiety.

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Continuous polymer fractionation
Authors: Wolf Bernhard A.
Published: May 2005

Continuous polymer fractionation(CPF) has been developed to provede access to large amounts of well‐defined fractions where it is impossible to synthesize polymers with a narrow molecular weight distribution. The principle of CPF and some details of its implementation are presented. Examples of fractionation are reported, together with problems that can arise and their solutions. As there is a widespread need for uniform, it is anticipated that CPF will become a routine operation.
Sol–gel processing of optical and electrooptical materials
Authors: Levy David , Esquivias Luis
Published: May 2005

The sol–gel process represents a room‐temperature method of producing a wide range of ceramic materials through the formation of a glassy network by the polymerization of suitable monomers. The use of the technique to produce, for example, sonogels, organic‐inorganic composites, NLO glasses, and electrooptical materials such as gel‐glass dispersed liquid crystald (GDLCs) is reviewed. An example of a GDLC is shown on this issue's front cover, 4‐pentyl‐4‐biphenylcarbonitrile in the LC state being dispersed in a thin film of silica.