bluuebunny/crossref_metadata_2025_split huggingface dataset:
Communication Satellites
Authors: Hoeber Christopher F. 
Published: December 2010

AbstractThis chapter gives an overview of the history and current applications of communications satellites, as well as their typical architecture and the technologies used to make them work. Fifty years ago, pioneering communications satellites relayed a handful of signals between two huge ground antennas. Today, their powerful sophisticated descendants broadcast video and audio to millions of users, provide Internet access capacities of more than 100 Gbps, support two‐way personal communications to tiny personal antennas in satellite phones, and transport huge amounts of business information. Modern satellites are complex marvels of systems engineering, balancing and integrating many subsystems and functions into systems that optimize communications capacity and performance, reliability, mass, and cost. The design has evolved to large body stabilized box‐shaped spacecraft with deployable solar arrays and antennas, directing radio frequency waves to the Earth at high power. The communications payload repeater and antenna engineering strategies as discussed in this chapter illustrate how major requirements are addressed and technologies are selected. The bus or platform discussion highlights the technologies that support the payload through launch vibration, bring it to its assigned orbit location and keep it there, point it very accurately, power and control it, and so on. These bus subsystems include power, structures, mechanisms, thermal control, attitude and orbit control, command and data handling, and propulsion.
Science Satellites – Landers and Rovers
Authors: Kornfeld Richard P. 
Published: December 2010

Abstract
Since the dawn of space exploration more than 50 years ago, bold attempts to land rovers and landers on other celestial objects were undertaken. While initial exploration focused on the Moon and the neighboring planets ‐ Venus and Mars, more recent exploration included the surfaces of asteroids, comets, and some of the outer planets and its moons. This chapter surveys past, present, and potential future surface missions, discusses some of the engineering considerations applicable to landers and rovers, and closes with case studies of missions to the Moon, Venus, and Mars.
Science Satellites: Interplanetary Spacecraft
Authors: McNutt Ralph L. 
Published: December 2010

AbstractInterplanetary spacecraft have played key roles in both scientific exploration of the solar system and national policy from the beginning of the Space Age. Initially simple low‐mass satellites, interplanetary spacecraft have become major scientific investigations with multiple international connections for answering fundamental questions about the origin, state, and evolution of all major bodies in the solar system. Such spacecraft and their payloads represent significant investments of both time and money and must operate reliably under extreme conditions. While relying on many satellite standard parts and some satellite standard systems, interplanetary spacecraft represent a small fraction of all spacecraft launched. Pressing the limits of launch vehicle, propulsion, telecommunications, and spacecraft longevity, these machines are custom made to their missions and continue to return knowledge of our universe that can be obtained in no other way to Earth from across the solar system and beyond.
Elevated pulmonary artery pressure among Amhara highlanders in Ethiopia
Authors: Hoit Brian D. , Dalton Nancy D. , Gebremedhin Amha , Janocha Allison , Zimmerman Peter A. , Zimmerman Allison M. , Strohl Kingman P. , Erzurum Serpil C. , Beall Cynthia M. 
Published: December 2010

AbstractObjectivePulmonary arterioles respond to hypoxia with constriction that raises vascular resistance and pulmonary artery blood pressure. The response is sustained indefinitely by the chronic hypoxia of high‐altitude residence among highlanders of European and Andean descent, but not Tibetans. The objective of this study was to identify the consequences of lifelong hypoxia exposure for the pulmonary vasculature among Amhara high‐altitude natives from Ethiopia.MethodsA three‐way static group comparison tested for the effect of Amhara ancestry and high residence altitude on pulmonary hemodynamics measured using echocardiography in samples of 76 healthy adult Amhara lifelong residents at 3700 m, 54 Amhara lifelong residents at 1200 m, and 46 U.S. low‐altitude residents at 282 m.ResultsAmhara at 3700 m had average Doppler‐estimated pulmonary artery systolic pressure (tricuspid regurgitant gradient) of 27.9 ± 8.4 (SD) mm Hg as compared with 21.9 ± 4.0 among Amhara at low altitude and 16.5 ± 3.6 in the U.S. low‐altitude reference sample. However, there was no residence altitude effect on pulmonary blood flow or vascular resistance. Amhara ancestry was associated with greater pulmonary artery systolic pressure and pulmonary blood flow, yet lower pulmonary vascular resistance.ConclusionsThe Amhara at 3700 m had elevated pulmonary artery pressure, but without the elevated pulmonary vascular resistance characteristic of the classic model of the response to long‐term hypoxia by the pulmonary vasculature. The elevated pressure among Amhara may be a consequence of high pulmonary blood flow regardless of altitude and represent a newly identified pattern of response. Am. J. Hum. Biol., 2011. © 2010 Wiley‐Liss, Inc.
Synthesis and Antimicrobial Activity of Some New N‐Substituted Quinoline Derivatives of 1H‐Pyrazole
Authors: Thumar Nilesh J. , Patel Manish P. 
Published: December 2010

AbstractA new series of 32 derivatives of 4‐pyrazolyl‐N‐(hetero)arylquinoline 5a–p and 6a–p were synthesized by a one‐pot base‐catalyzed cyclocondensation reaction of 1‐phenyl‐3‐(hetero)aryl‐pyrazole‐4‐carbaldehyde 1a–h, malononitrile 2, and 3‐(hetero)aryl‐5,5‐disubstitutedcyclohex‐2‐enone 3a–b or 4a–b, respectively. All the synthesized compounds were characterized by elemental analysis, FT‐IR, 1H‐NMR, and 13C‐NMR spectral data. All the synthesized compounds were screened, against six bacterial pathogens, namely Bacillus subtilis, Clostridium tetani, Streptococcus pneumoniae, Salmonella typhi, Vibrio cholerae, Escherichia coli, and antifungal activity, against two fungal pathogens Aspergillus fumigatus and Candida albicans, using broth microdilution MIC method. Some of the compounds were found to be more or equipotent against most of the employed strains than commercially available drugs as evident from the screening data.
New Insights into Keggin‐Type 12‐Tungstophosphoric Acid from 31P MAS NMR Analysis of Absorbed Trimethylphosphine Oxide and DFT Calculations
Authors: Huang Shing‐Jong , Yang Chih‐Yi , Zheng Anmin , Feng Ningdong , Yu Ningya , Wu Pei‐Hao , Chang Yu‐Chi , Lin Ying‐Chih , Deng Feng , Liu Shang‐Bin 
Published: December 2010

AbstractThe acid and transport properties of the anhydrous Keggin‐type 12‐tungstophosphoric acid (H3PW12O40; HPW) have been studied by solid‐state 31P magic‐angle spinning NMR of absorbed trimethylphosphine oxide (TMPO) in conjunction with DFT calculations. Accordingly, 31P NMR resonances arising from various protonated complexes, such as TMPOH+ and (TMPO)2H+ adducts, could be unambiguously identified. It was found that thermal pretreatment of the sample at elevated temperatures (≥423 K) is a prerequisite for ensuring complete penetration of the TMPO guest probe molecule into HPW particles. Transport of the TMPO absorbate into the matrix of the HPW adsorbent was found to invoke a desorption/absorption process associated with the (TMPO)2H+ adducts. Consequently, three types of protonic acid sites with distinct superacid strengths, which correspond to 31P chemical shifts of 92.1, 89.4, and 87.7 ppm, were observed for HPW samples loaded with less than three molecules of TMPO per Keggin unit. Together with detailed DFT calculations, these results support the scenario that the TMPOH+ complexes are associated with protons located at three different terminal oxygen (Od) sites of the PW12O403− polyanions. Upon increasing the TMPO loading to >3.0 molecules per Keggin unit, abrupt decreases in acid strength and the corresponding structural variations were attributed to the change in secondary structure of the pseudoliquid phase of HPW in the presence of excessive guest absorbate.
Anionic Activators for Differential Sensing with Cell‐Penetrating Peptides
Authors: Montenegro Javier , Matile Stefan 
Published: December 2010

AbstractThe design, synthesis, and evaluation of small peptides with one to three negative charges and one to three hydrazides as key components of membrane‐based synthetic sensing systems are reported. Their spontaneous reaction with hydrophobic aldehydes or ketones gives rapid access to small collections of amphiphilic anions. These anionic amphiphiles can activate polycations as anion transporters in lipid‐bilayer membranes. Odorants are used as representative hydrophobic aldehydes and ketones, and cell‐penetrating peptides (CPPs) as polycationic transporters in fluorogenic vesicles. Different activities obtained with different counterion activators are used to generate multidimensional patterns that can be recognized by principal component and hierarchical cluster analysis to extract unique “fingerprints” for individual analytes (including enantiomers, cis–trans isomers or perfumes as illustrative analyte mixtures). Comparison of the peptide activators reveals that carboxylates perform better than phosphonates. Gemini‐like activators containing two carboxylates and two hydrophobic hydrazone tails are best, whereas excessive charges and tails give weaker activities. This result differs from cationic activators of polyanionic transporters such as DNA, which worked best with octopus amphiphiles with one cationic head and four hydrophobic tentacles.
Mesenchymal stem cells from development to postnatal joint homeostasis, aging, and disease
Authors: De Bari Cosimo , Kurth Tobias B. , Augello Andrea 
Published: December 2010

AbstractJoint morphogenesis involves signaling pathways and growth factors that recur in the adult life with less redundancy to safeguard joint homeostasis. Loss of such homeostasis due to abnormal signaling networks as in aging could lead to diseases such as osteoarthritis. Stem cells are the cellular counterpart and targets of the morphogenetic signals, and they function to maintain the tissues by ensuring replacement of cells lost to physiological turnover, injury, aging, and disease. Mesenchymal stem cells (MSCs) are key players in regenerative medicine for their ability to differentiate toward multiple lineages such as cartilage and bone, but they age along the host body and senesce when serially passaged in culture. Understanding correlations between aging and its effects on MSCs is of the utmost importance to explain how aging happens and unravel the underlying mechanisms. The investigation of the MSC senescence in culture will help in developing more efficient and standardized cell culture methods for cellular therapies in skeletal regenerative medicine. An important area to explore in biomedical sciences is the role of endogenous stem cell niches in joint homeostasis, remodeling, and disease. It is anticipated that an understanding of the stem cell niches and related remodeling signals will allow the development of pharmacological interventions to support effective joint tissue regeneration, to restore joint homeostasis, and to prevent osteoarthritis. Birth Defects Research (Part C) 90:257–271, 2010. © 2010 Wiley‐Liss, Inc.
Überspannung „sichtbar“ gemacht
Authors: Wille Leif , Witt Alexander , Flint Alfred 
Published: December 2010

AbstractIn der technischen Anwendung von Elektrolysen, aber auch im Unterricht bei der Behandlung des Themas „Elektrochemie“ spielt die Überspannung eine bedeutende Rolle. Klassisch wird dieses Thema über die Ermittlung unterschiedlicher Zersetzungsspannungen beim gleichen Elektrolyten aber unterschiedlichem Elektrodenmaterial erschlossen. Im Folgenden wird nun ein Vorschlag unterbreitet, wie man ausgehend von einem überraschenden Ergebnis bei einer Elektrolyse schließlich zu einem Experiment kommt, in dem die vom Elektrodenmaterial abhängige Überspannung zur Abscheidung von Wasserstoff und Sauerstoff quasi „offensichtlich“ wird.
Adsorption of Amaranth Dye onto Alumina Reinforced Polystyrene
Authors: Ahmad Rais , Kumar Rajeev 
Published: December 2010

AbstractAdsorptive removal of toxic amaranth dye by alumina reinforced polystyrene (ARP) composite was studied as a function of contact time, pH, initial dye concentration, and temperature. The results indicated that adsorption was strongly dependent on pH and temperature of the dye solution. The adsorption was favored at low pH with the maximum removal at pH 2.0. Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D–R) models were used for the description of adsorption equilibrium data and the best interpretation for the experimental data was given by the D–R model. The adsorption kinetics was tested using pseudo first order, pseudo second order, Elovich, intraparticle, and film diffusion models and the removal by ARP followed a pseudo second order kinetics. Thermodynamic studies revealed that both adsorption and desorption was spontaneous and endothermic in nature. From the exhausted adsorbent, about 70 and 96% desorption was obtained with (99%) CH3OH and 0.1 M NaOH, respectively.
Synthesis and in vitro/in vivo Evaluation of the Antitrypanosomal Activity of 3‐Bromoacivicin, a Potent CTP Synthetase Inhibitor
Authors: Conti Paola , Pinto Andrea , Wong Pui E. , Major Louise L. , Tamborini Lucia , Iannuzzi Maria C. , De Micheli Carlo , Barrett Michael P. , Smith Terry K. 
Published: December 2010

AbstractThe first convenient synthesis of enantiomerically pure (αS,5S)‐α‐amino‐3‐bromo‐4,5‐dihydroisoxazol‐5‐yl acetic acid (3‐bromoacivicin) is described. We demonstrate that 3‐bromoacivicin is a CTP synthetase inhibitor three times as potent as its 3‐chloro analogue, the natural antibiotic acivicin. Because CTP synthetase was suggested to be a potential drug target in African trypanosomes, the in vitro/in vivo antitrypanosomal activity of 3‐bromoacivicin was assessed in comparison with acivicin. Beyond expectation, we observed a 12‐fold enhancement in the in vitro antitrypanosomal activity, while toxicity against mammalian cells remained unaffected. Despite its good in vitro activity and selectivity, 3‐bromoacivicin proved to be trypanostatic and failed to completely eradicate the infection when tested in vivo at its maximum tolerable dose.
X‐Ray Near‐Edge Absorption Study of Temperature‐Induced Low‐Spin‐to‐High‐Spin Change in Metallo‐Supramolecular Assemblies
Authors: Arezki Bahia , Schwarz Guntram , Bodenthin Yves , Luetzenkirchen‐Hecht Dirk , Markert Christian , Wagner Ralph , Frahm Ronald , Kurth Dirk G. , Pietsch Ullrich 
Published: December 2010

AbstractX‐ray absorption near the iron K edge (XANES) was used to investigate the characteristics of temperature‐induced low‐spin‐to‐high‐spin change (SC) in metallo‐supramolecular polyelectrolyte amphiphile complexes (PAC) containing FeN6 octahedra attached to two or six amphiphilic molecules. Compared to the typical spin‐crossover material Fe(phen)2(NCS)2 XANES spectra of PAC show fingerprint features restricted to the near‐edge region which mainly measures multiple scattering (MS) events. The changes of the XANES profiles during SC are thus attributed to the structure changes due to different MS path lengths. Our results can be interpreted by a uniaxial deformation of FeN6 octahedra in PAC. This is in agreement with the prediction that SC is originated by a structural phase transition in the amphiphilic matrix of PAC, but in contrast to Fe(phen)2(NCS)2, showing the typical spin crossover being associated with shortening of all the metal–ligand distances.
Use of Polyoxometalate Catalysts in Ionic Liquids to Enhance the Dissolution and Delignification of Woody Biomass
Authors: Sun Ning , Jiang Xinyu , Maxim Mirela L. , Metlen Andreas , Rogers Robin D. 
Published: December 2010

AbstractA well‐known polyoxometalate, [PV2Mo10O40]5−, in both acidic (acidic POM, H5[PV2Mo10O40]) and ionic liquid‐compatible form ([C2mim]POM, [1‐ethyl‐3‐methylimidazolium]4H[PV2Mo10O40]), has been studied as a catalyst for the dissolution and delignification of wood in the ionic liquid (IL) 1‐ethyl‐3‐methylimidazolium acetate ([C2mim]OAc). Differences were observed with variables such as the form of POM, POM loading, and reaction conditions. Generally, the addition of POM leads to a faster dissolution, a lower lignin content in the recovered cellulose‐rich materials (isolated pulp), and a lower isolated yield of lignin due to its oxidation. Acidic POM decreases the lignin content of the pulp without compromising the yield of the pulp. [C2mim]POM in the IL facilitates greater delignification (lower lignin content in pulp) than the IL with acidic POM; however, the overall pulp yield is also lower indicating some degradation of the carbohydrates. The POM can be recovered with [C2mim]OAc after evaporation of the reconstitution solvent (e.g., acetone/water) and can be reused, albeit with some loss of POM and loss of POM activity under the current conditions.
Fabrication of La0.8Sr0.2CrO3‐based Perovskite Film via Flame‐Assisted Vapor Deposition for H2 Production by Reforming
Authors: Sansernnivet Mayuree , Laosiripojana Navadol , Assabumrungrat Suttichai , Charojrochkul Sumittra 
Published: December 2010

AbstractFlame‐assisted vapor deposition (FAVD) has a principle similar to conventional CVD in which a film is deposited from a vapor phase. It is a simple and cost‐effective technique as it is operated in an open atmosphere. The microstructure of the deposited films is controlled by varying the processing parameters. In our research, an oxide film of lanthanum chromite perovskite‐based (La0.8Sr0.2CrO3) material is fabricated, using the FAVD technique, on a stainless steel substrate (SS430) for an application in solid oxide fuel cells (SOFC). The precursor solution for La0.8Sr0.2CrO3 film is prepared from metal nitrate compounds with a concentration in the range 0.0125 − 0.0500 M. Dense and porous films are fabricated, depending on various processing parameters such as fuel to water ratio, air pressure, flow rate of a precursor, and the distance between the spray nozzle and the substrate. The effect of various processing parameters on the microstructure and phase formation of the deposited film are investigated using scanning electron microscopy (SEM) and X‐ray diffraction (XRD). The deposition temperature resulting from the total heat of combustion from the combination of all the deposition parameters is very important in determining the properties of the films. According to the SEM images, a small particle size on the nanometer scale is found at high deposition temperature. On the other hand, the particles are connected into a dense film at low deposition temperatures. The main phase of LaCrO3 is found in all deposition temperatures (temp range). For hydrogen production, the methane steam reforming over the porous film of La0.8Sr0.2CrO3 at 900 °C is investigated. Under specific operating conditions (low inlet H2O/CH4 ratio), its catalytic reactivity is comparable to metallic‐based catalysts but with less inlet steam required.
Coordination Chemistry of Thiazole‐Based Ligands: New Complexes Generating 3D Hydrogen‐Bonded Architectures
Authors: Rossin Andrea , Di Credico Barbara , Giambastiani Giuliano , Gonsalvi Luca , Peruzzini Maurizio , Reginato Gianna 
Published: December 2010

AbstractThe hydrothermal (solvothermal) reactions of ZnII, CoII, and CuII salts with the thiazole‐based ligands 2‐Htzc (thiazole‐2‐carboxylic acid), 4‐Htzc (thiazole‐4‐carboxylic acid), and Htzc‐py [2‐(2‐pyridyl)thiazole‐4‐carboxylic acid] led to the formation of coordination complexes with assorted geometry at the metal centers. The new complexes were characterized by conventional spectroscopic methods as well as by single‐crystal X‐ray analysis, TG–MS, and PXRD. Crystallographic studies have shown that an extended supramolecular network is generated in the solid state through the formaton of hydrogen bonds between the several polar groups present in the complex frameworks.
Synthesis, Structures, and Aggregation Properties of N‐Acylamidines
Authors: Wigbers Christof , Prigge Jörg , Mu Zhongchen , Fröhlich Roland , Chi Lifeng , Würthwein Ernst‐Ulrich 
Published: December 2010

AbstractN‐Acylamidines 1a–q, which are important ligands for metal ion complexation, were easily prepared either by acylation of amidines 2 or by treatment of N‐acylimidates 3 with amines. Additionally, the reaction of amidinium salts with aroyl halides in the presence of sodium hydroxide gave the aryl derivatives 1r–1ad and three azobenzene derivatives 1ae–1ag. The respective substitution pattern of these novel derivatives was selected with respect to possible steric and electronic effects in coordination reactions as well as with regard to the aggregation properties. N‐Acylamidines 1 may exist as three types of tautomers, which were examined in solution by NMR spectroscopic analysis and by quantum chemical DFT and SCS‐MP2‐calculations for single molecules in the gas phase. Internal rotations require activation energies between 3–17 (C–N) and 15–27 (C=N) kcal/mol. Due to their excellent ability to form intra‐ and intermolecular hydrogen bonds, these molecules show very variable aggregation behavior in the solid state (X‐ray analysis) as well as on surfaces, depending on the substitution pattern. Thus, dimeric (1c, 1d, and 1u) and tetrameric (1f) aggregates with strong NH···OC hydrogen bonding, as well as polymeric chain structures (1x and 1z) were observed in the solid state. Furthermore, a dimer 1k involving only the amidine subunits, rather than the carbonyl function, was found. Monolayers of molecules 1u and 1ab physisorbed at the liquid/HOPG (high orientated pyrolytic graphite) interface in 1‐phenyloctane solution were examined by Scanning Tunneling Microscopy (STM).
Peptide–Heterocycle Chimera: New Classes of More Drug‐Like Peptidomimetics by Ligations of Peptide–Bis(electrophiles) with Various Bis(nucleophiles)
Authors: El‐Dahshan Adeeb , Nazir Samina , Ahsanullah  , Ansari Farzana Latif , Rademann Jörg 
Published: December 2010

AbstractSeveral C‐terminal peptidyl‐substituted bis‐ and tris(electrophiles) were prepared by starting from polymeric phosphoranylidenacetates as acyl anion equivalents. After C‐acylations with amino acids and peptide elongation, the obtained peptidyl‐phosphoranylideneacetate resins were either cleaved oxidatively, delivering peptidyl‐diketo esters, or saponified, leading to immediate decarboxylation. The generated peptidyl‐phosphorane could be treated with aldehydes to yield peptidyl vinyl ketones or could be cleaved oxidatively to yield peptidyl keto aldehydes. Ligation with various bis(nucleophiles) including hydrazines, hydroxylamine, diamines, amino‐thiols, amidines, and guanidines were investigated in the formation of peptide‐heterocycle chimera containing pyrazoline, pyrazole, isoxazole, isoxazoline, thiazepine, quinoxaline, and imidazolone heterocycles.