bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of load type (pollen or nectar) and load mass on hovering metabolic rate and mechanical power output in the honey beeApis mellifera
Authors: Feuerbacher Erica , Fewell Jennifer H. , Roberts Stephen P. , Smith Elizabeth F. , Harrison Jon F. 
Published: May 2003

SUMMARYIn this study we tested the effect of pollen and nectar loading on metabolic rate (in mW) and wingbeat frequency during hovering, and also examined the effect of pollen loading on wing kinematics and mechanical power output. Pollen foragers had hovering metabolic rates approximately 10% higher than nectar foragers, regardless of the amount of load carried. Pollen foragers also had a more horizontal body position and higher inclination of stroke plane than measured previously for honey bees (probably nectar foragers). Thorax temperatures ranked pollen &gt; nectar &gt; water foragers,and higher flight metabolic rate could explain the higher thorax temperature of pollen foragers. Load mass did not affect hovering metabolic rate or wingbeat frequency in a regression-model experiment. However, using an analysis of variance (ANOVA) design, loaded pollen and nectar foragers (mean loads 27% and 40% of body mass, respectively) significantly increased metabolic rate by 6%. Mean pollen loads of 18% of body mass had no effect on wingbeat frequency, stroke amplitude, body angle or inclination of stroke plane, but increased the calculated mechanical power output by 16–18%(depending on the method of estimating drag). A rise in lift coefficient as bees carry loads without increasing wingbeat frequency or stroke amplitude(and only minimal increases in metabolic rate) suggests an increased use of unsteady power-generating mechanisms.
Comparative analysis of DNA vectors at mediating RNAi in Anopheles mosquito cells and larvae
Authors: Brown Anthony E. , Crisanti Andrea , Catteruccia Flaminia 
Published: May 2003

SUMMARY
Heritable RNA interference (RNAi) mediated by transgenes exhibiting dyad symmetry represents an important tool to study the function of genes expressed at late developmental stages. In this study, we determined whether the transcriptional machinery of Anopheles mosquitoes is capable of directing suppression of gene expression from DNA constructs designed to transcribe double-stranded RNA (dsRNA) as extended hairpin-loop RNAs. A series of DNA vectors containing sense and antisense regions of the green fluorescent protein EGFP target gene was developed. The effect of these vectors on a transiently expressed or stably integrated EGFP gene was assessed in an Anopheles gambiae cell line and in Anopheles stephensi larvae. Our data indicate that dsRNA-mediated silencing of a target gene from plasmid DNA can be achieved at high levels in Anopheles cell lines and larvae. The region that links the sense and antisense sequences of the target gene plays a determining role in the degree of silencing observed. These results provide important information for the development of heritable RNAi in Anopheles.
Mechanisms of frequency and amplitude modulation in ring dove song
Authors: Beckers Gabriël J. L. , Suthers Roderick A. , Cate Carel ten 
Published: May 2003

SUMMARYBirdsong assumes its complex and specific forms by the modulation of phonation in frequency and time domains. The organization of control mechanisms and intrinsic properties causing such modulation have been studied in songbirds but much less so in non-songbirds, the songs of which are often regarded as relatively simple. We examined mechanisms of frequency and amplitude modulation of phonation in ring doves Streptopelia risoria,which are non-songbirds. Spontaneous coo vocalizations were recorded together with concurrent pressure patterns in two different air sacs and air flow rate in the trachea. The results show that amplitude modulation is the result of the cyclic opening and closure of a valve instead of fluctuations in driving pressure, as is the current explanation. Frequency modulation is more complex than previously recognized and consists of gradual, continuous time–frequency patterns, punctuated by instantaneous frequency jumps. Gradual frequency modulation patterns correspond to pressure variation in the interclavicular air sac but not to pressure variation in the cranial thoracic air sac or air flow rate variation in the trachea. The cause of abrupt jumps in frequency has not been identified but can be explained on the basis of intrinsic properties of the vocal organ. Air sac pressure variation as a mechanism for frequency modulation contrasts with the specialized syringeal musculature of songbirds and may explain why the fundamental frequency in non-songbird vocalizations is generally modulated within a limited frequency range.
Phenotypic flexibility of structure and function of the digestive system of Japanese quail
Authors: Starck J. Matthias , Rahmaan Gamal Hasan Abdel 
Published: May 2003

SUMMARYOrganisms adjust their phenotype to fluctuating conditions of the environment and to changing internal demands. We report flexible responses of the gizzard and the small intestine of Japanese quail to a high-fibre diet. Switching from a standard diet to a high-fibre diet results in a highly significant increase in gizzard size, intestine length, mucosal surface,thickness of the intestinal muscular layer and vascularization of the mucosa. After diet switching, increased or decreased gizzard size results from changes in cell size, i.e. smooth muscle cell hypertrophy and hypotrophy,respectively. Increased cell proliferation is not the cause of increase in gizzard size. In the small intestine, however, we found elevated levels of cell proliferation after diet switching and conclude that increased capacity(upregulation) of the small intestine is based on increased rates of mitosis in the intestinal crypts. It is highly probable that elevated levels of cell proliferation in the crypts are balanced by elevated levels of cell extrusion at the tip of intestinal villi. The lipid contents of the liver were reduced,indicating that lipid stores in the liver were mobilized to fuel the flexible response of the gastrointestinal tract. During changes of organ size in response to changes in food composition, resting metabolic rate was not altered.
Ectopic transplantation of the accessory medulla restores circadian locomotor rhythms in arrhythmic cockroaches (Leucophaea maderae)
Authors: Reischig Thomas , Stengl Monika 
Published: May 2003

SUMMARY
The presence of an endogenous circadian clock in the brain of an animal was first demonstrated in the cockroach Leucophaea maderae. However, the clock's cellular basis remained elusive until pigment-dispersing hormone-immunoreactive neurons, which express the clock genes periodand timeless in Drosophila, were proposed as pacemaker candidates. In several insect species, pigment-dispersing hormone-immunoreactive neurons are closely associated with the accessory medulla, a small neuropil in the optic lobe, which was suggested to be a circadian clock neuropil. Here, we demonstrate that ectopic transplantation of adult accessory medulla into optic lobe-less cockroaches restores circadian locomotor activity rhythms in L. maderae. All histologically examined cockroaches that regained circadian activity regenerated pigment-dispersing hormone-immunoreactive fibres from the grafts to original targets in the protocerebrum. The data show that the accessory medulla is the circadian pacemaker controlling locomotor activity rhythms in the cockroach. Whether pigment-dispersing hormone-immunoreactive neurons are the only circadian pacemaker cells controlling locomotor activity rhythms remains to be examined.
Expression of two isoforms of the vacuolar-type ATPase subunit B in the zebrafishDanio rerio
Authors: Boesch S. T. , Eller B. , Pelster B. 
Published: May 2003

SUMMARYIn the present study we tested the hypothesis that two isoforms of the regulatory subunit B of vacuolar-type ATPase (V-ATPase) are expressed in the zebrafish Danio rerio. The complete coding sequences for both isoforms, vatB1 and vatB2, were cloned and sequenced. BLASTX analysis revealed the greatest similarity to amino acid sequences of B subunits from the European eel Anguilla anguilla and rainbow trout Oncorhynchus mykiss. The isoforms were expressed in a bacterial system and the recombinant proteins verified using isoform-specific antibodies directed against vatB isoforms of the eel. The distribution of both isoforms in zebrafish tissues was investigated using reverse transcriptase-polymerase chain reaction and western blot analysis. The results revealed that at the RNA level both isoforms were expressed in all tested organs, i.e. the gills,swimbladder, heart, kidney, liver, spleen, intestine and skeletal muscle. At the protein level, however, there were tissue-specific variations in the levels of the two vatB isoforms expressed. The highest amounts of V-ATPase were detected in total protein preparations from gill, heart and liver tissue. In liver tissue, however, the western blot analysis indicated that vatB1 was not as prominent as vatB2, and immunohistochemistry revealed that antibodies directed against vatB1 yielded a very weak staining in a number of cells,while an antibody directed against vatB1 and vatB2 yielded a strong staining in virtually every cell. Similarly, neurosecretory cells of the small intestine were stained with an antibody directed against vatB1 and vatB2, but not with an antibody specific for vatB1. Therefore we conclude that the differential expression of two isoforms of the V-ATPase subunits, which may serve different functions as in several mammalian species, may also be a common phenomenon in teleost fish.
Increased Stability of Organically Modified MCM-41 Synthesized by a One-step Procedure
Authors: Igarashi Naoko , Tanaka Yoshinori , Nakata Shin-ichi , Tatsurni Takashi 
Published: May 2003

Abstract
Organically functionalized mesoporous silica MCM-41 materials synthesized by a one-step procedure are found to be structurally more stable than the unfunctionalized ones. This increased stability can be ascribed to the increase in hydrophobicity.
Application of Polymer Supported Base in Solid Phase Synthesis: Convenient Synthesis of N-Aryl-N′-benzyl Piperazine Derivatives
Authors: Yamamoto Yasuo , Tanabe Kiyoshi , Okonogi Tsuneo 
Published: May 2003

Abstract
N-Aryl-N′-benzyl piperazine derivatives were synthesized using REM resin. In cleavage step, the piperazine derivatives were successfully prepared in a good yield and excellent purity by treatment with novel polymer supported base in the absence of any base.
Reactions of Selenothioic Acid S-Esters and Diselenoic Acid Esters with Trialkyl Phosphites Leading to α-Phosphoryl Sulfides and Selenides
Authors: Murai Toshiaki , Izumi Chiyoko , Kato Shinzi 
Published: May 2003

Abstract
The reaction of selenothioic acid S-esters with trialkyl phosphites proceeded smoothly to afford α-phosphoryl sulfides as a major product in good to high yields. The reaction was also applicable to diselenoic acid esters. On the contrary, selenothioic acid S-butyl ester underwent oxidative dimerization with triphenylphosphine to give a divinyl diselenide.
A Novel Synthesis of Highly Branched-Alkyl Aryl Ketones Using the Conjugate Addition of the Gilman Lithio Cuprate to β-Methylthio-α,β-unsaturated Ketones: Abnormal Reactivity of the Intermediary Enolates toward Molecular Oxygen
Authors: Arai Takayuki , Akazome Motohiro , Ogura Katsuyuki 
Published: May 2003

Abstract
In order to synthesize highly branched-alkyl aryl ketones, l-(methylthio)-1-alken-2-yl phenyl ketones were subjected to the reaction with lithium dialkylcuprate. The high reactivity of an intermediary enolate toward molecular oxygen was found to give α-hydroperoxy ketones.
Conformational Switching in the Thermal and Photochemical Synthesis of cis- and trans-Ruthenium Bis(bipyridine) Sulfoxide Complexes
Authors: Hesek Dusan , Inoue Yoshihisa , Everitt Simon R L 
Published: May 2003

Abstract
The preparation of ruthenium bis(bipyridine) sulfoxides has been carried out under thermal or photochemical conditions, leading to good yields of products with trans or cis configurations, and the configuration of the starting material has also been observed to influence the preferred structure of the final product.
Zinc Complexes of Artificial Histidine-containing Dipeptides as Catalysts of Hydrolyses of p-Nitrophenyl Phosphates
Authors: Ichikawa Kazuhiko , Uddin M Khabir , Nakata Kou 
Published: May 2003

Abstract
Zinc complexes of histidine-containing peptide derived from N,N′-dihistidylethylenediamine L1 and im-bzl-N,N″-dihistidyldiethylenetriamine L2 were designed and examined as catalysts for hydrolyses of bis(p-nitrophenyl)phosphate (BNPP) and p-nitrophenyl phosphate (NPP). The zinc complex of L1 was inactive and another L2 complex hydrolyzed efficiently BNPP and NPP: their pseudo-first-order rate constants are 1.1 × 10−5 s−1 and 2.1 × 10−5 s−1, respectively.
A Clay-Metal Complex Ultrathin Film as Prepared by the Langmuir-Blodgett Technique
Authors: Tamura Kenji , Setsuda Hitoshi , Taniguchi Masahiro , Nakamura Takayoshi , Yamagishi Akihiko 
Published: May 2003

Abstract
A clay-metal complex hybrid film with the thickness of 5.0 ± 1.0 nm was prepared by the Langmuir-Blodgett technique. According to the method, a hectorite clay dispersed in an aqueous subphase was adsorbed by a cationic monolayer of amphiphilic Ru(II) complex. The surface structure of a film deposited onto a hydrophilic glass plate was studied with an atomic force microscope (AFM).
Creation of Acid Sites on SBA-15 Mesoporous Silica by Alumination
Authors: Cheng Mojie , Wang Zhengbao , Sakurai Keiji , Kumata Fumio , Saito Takeshi , Komatsu Takayuki , Yashima Tatsuaki 
Published: May 2003

Abstract
The new mesoporous silica with large pore size, SBA-15, was aluminated through the reaction with aluminum chloride. The present alumination method showed a good control of aluminum content but little influence on the pore structure. Aluminum atoms were incorporated into the framework of SBA-15, which resulted in a new kind of mesoporous acid catalyst.
Synthesis and Structural Characterization of Ln(III) Complexes (Ln = Eu, Gd, Tb, Er, Tm, Lu) of Tripodal Tris[2-(salicylideneamino)ethyl]amine
Authors: Kanesato Masatoshi , Yokoyama Toshiro 
Published: May 2003

Abstract
The preparation and characterization of Ln(III) complexes (Ln = Eu, Gd, Tb, Er, Tm, Lu) of heptadentate (N4O3) ligand trensal, tris[2-(salicylideneamino)ethyl]amine (H3L1), have been studied. The molecular structures of [LnL1] were determined by X-ray structural analysis ; these are heptadentate complexes in which the metal ions are coordinated by the three oxygen atoms and the four nitrogen atoms.
Effective Trap of Zwitterionic Intermediate during Oxygenation of Electron-Rich Naphthalenes with Singlet Oxygen by the Intramolecular Alcohol
Authors: Fujita Morifumi , Ohshiba Masaki , Yamasaki Yayoi , Sugimura Takashi , Tai Akira 
Published: May 2003

Abstract
The presence of a zwitterionic intermediate during the oxygenation of electron-rich naphthalenes with singlet oxygen is clarified by the clean and efficient formation of hydroperoxide via nucleophilic addition of the intramolecular alcohol to the intermediate and by its stereochemical analysis using an optically active linker of the alcohol.
Organosulfur Functionality as an Alternative Enantiocontrollable Coordinating Element in Chiral Phosphine Ligands for Palladium-Catalyzed Asymmetric Allylic Alkylations
Authors: Hiroi Kunio , Suzuki Yoshio , Abe Ikuko 
Published: May 2003

Abstract
The synthesis of (S)-proline-derived phosphines bearing organosulfur groups and the use of them as chiral ligands in palladium-catalyzed asymmetric allylic alkylations were accomplished successfully. The mechanism is discussed on the basis of the stereochemical results, presumably by participation of organosulfur groups as alternative enantiocontrollable coordinating elements.
Polymer-Mediated Extraction of Porphirinato Chelates for a Spectrophotometric Approach to Sub-ppt Level Detection of Metal Ions
Authors: Saitoh Tohru , Ohkubo Satoko , Matsubara Chiyo 
Published: May 2003

Abstract
Negatively charged copper(II) and zinc(II) chelates with 5,10,15,20-tetrakis(4-carboxyphenyl)-21H,23H-porphine were incorporated into the precipitates formed from the aqueous solutions of thermo-responsive polymer; poly(N-isopropylacrylamide). In the presence of an appropriate kind and amount of quaternary ammonium ion, the recovery of the chelate was quantitatively. Sub-ppt level zinc(II) in water by the photometric detection in HPLC was successfully achieved, because of the highly efficient concentration.
Observation and Quantification of a Liquid Motion under a Magnetic Field Gradient
Authors: Devos Olivier , Aogaki Ryoichi 
Published: May 2003

Abstract
A new dynamic phenomenon in high magnetic field, i.e., an expanding liquid ring formation according to parabolic distribution of magnetic field, was discussed. Then, a new experimental technique by using this phenomenon was developed in order to observe and quantify such motion of paramagnetic or diamagnetic liquid.
Absolute Configuration of 8,8′-Dialkyl-1,1′-Biisoquinoline
Authors: Tsue Hirohito , Fujinami Hideyuki , Itakura Takeshi , Tsuchiya Ryuta , Kobayashi Kimiko , Takahashi Hiroki , Hirao Ken-ichi 
Published: May 2003

Abstract
Absolute configurations of 1,1′-biisoquinoline derivatives, in which a series of alkyl groups are introduced at the 8- and 8′-positions, have been determined by using two kinds of well-established methods.
Preparation of a UV-absorbed Transparent Monolithic Titanium Oxide Gel by the Catalytic Sol-Gel Process with a Phenanthroline Hydrochloride Catalyst
Authors: Matsumoto Taki , Murakami Yasushi , Takasu Yoshio 
Published: May 2003

Abstract
UV-absorbed transparent monolithic titanium oxide gels were prepared by the catalytic sol-gel process with 1,10-phenanthroline hydrochloride and n-butylamine. When 1,10-phenanthroline was added to the precursor solution, transmittance of the gels increased. The higher the content of 1,10-phenanthroline hydrochloride and the lower content of water, the more transparent gel was formed. The transparent titanium oxide gels were obtained by reducing hydrolysis and promoting polycondensation.
A Novel Optical Oxygen Sensing Based on Quenching of Photoexcited Triplet State of C70 in Polystyrene Film by Oxygen Using Time-resolved Spectroscopy
Authors: Amao Yutaka , Asai Keisuke , Okura Ichiro 
Published: May 2003

Abstract
A novel optical oxygen sensor based on the quenching of triplet-triplet absorption of C70 molecule by oxygen has been developed using time-resolved spectroscopy. The photoexcited triplet state of C70 was quenched effectively by oxygen and large Stern-Volmer constant was obtained.
Photochemical Isomerization of trans-Dichlorotetrakis(dimethylphenylphosphine)osmium(II)
Authors: Ikuo Akira , Otani Kenichiro , Chijimatsu Tamiko , Uzawa Jun , Yasufuku Katsutosi , Teratani Shousuke 
Published: May 2003

Abstract
Photochemical isomerization of trans-dichlorotetrakis(dimethylphenylphosphine)osmium(II) to its cis-form was confirmed by NMR and IR spectroscopy. The quantum yield of isomerization was 0.9 at 410 nm which was much larger than that (0.03 at 410 nm) of trans-dichlorobis(diphenylphosphinoethane)osmium(II).
Ruthenium-Catalyzed Coupling of Aromatic Carbon-Hydrogen Bonds in Aromatic Imidates with Olefins
Authors: Kakiuchi Fumitoshi , Sato Taisuke , Yamauchi Masakazu , Chatani Naoto , Murai Shinji 
Published: May 2003

Abstract
Catalytic C-H/olefin coupling can be directed by N,O-heterocyclic substituents. The Ru3(CO)12-catalyzed reaction of 4,4-dimethyl-2-(2-methylphenyl)-5,6-dihydro-4H-1,3-oxazine (1) with triethoxyvinylsilane gave a mixture of the corresponding 1:1 addition product (3a) and its olefinic analogue (3b) in good yields in ca. a 1:1 ratio. In the case of the reaction of 4,4-dimethyl-2-(2-methylphenyl)-4,5-dihydro-1,3-oxazole (7), the olefinic analogue (8b) of the coupling product (8a) was obtained as the major product. The existence of a new reaction pathway is discussed.
Synthesis and Photoinduced Electron Transfer of Pyromellitimide-Linked Porphyrin in Constrained Hydrophobic Environment of Unimer Micelle
Authors: Higashida Suguru , Nishiyama Katsura , Yusa Shin-ichi , Morishima Yotaro , Imahori Hiroshi , Kaneda Takahiro , Sakata Yoshiteru 
Published: May 2003

Abstract
Pyromellitimide-linked zincporphyrin dyad was covalently incorporated into hydrophobic cluster of amphiphilic polysulfonate. Accelerated photoinduced electron transfer of the dyad in the copolymer was observed as compared with that of the corresponding dyad in THF, indicating the large contribution of the constrained microenvironment for electron transfer.
Syntheses and Biological Activities of Dendrimeric Mastoparans
Authors: Kurita Takashi , Kosemura Yoshiko , Kumakura Konosuke , Kasai Hisataka , Ito Hisashi 
Published: May 2003

Abstract
Dendritic formation of mastoparan molecule by a carboxyl-terminal linkage to a lysine branch increased the original mastoparan activity for hemolysis and catecholamine release from adrenal chromaffin cells. The most potent dendrimer in hemolytic activity, approximately 8000 times as active as mastoparan, was octameric mastoparan.
Development of a Hydrogen Selective Ceramic Membrane and Its Application for the Conversion of Greenhouse Gases
Authors: Prabhu Anil K , Oyama S Ted 
Published: May 2003

Abstract
A new membrane with 100% selectivity to hydrogen was developed by chemical vapor deposition of a silica precursor on Vycor glass. Application of the modified membrane to the CO2 reforming of CH4 produced conversion levels above equilibrium.
Deactivation of External Acid Sites of H-Mordenite with Ceria Modification in the Isopropylation of Biphenyl
Authors: Nakajima Katsutoshi , Tawada Shogo , Sugi Yoshihiro , Kubota Yoshihiro , Hanaoka Taka-aki , Matsuzaki Takehiko , Kunimori Kimio 
Published: May 2003

Abstract
Cerium modification of H-mordenite was highly effective for the deactivation of acid sites on external surfaces in the isopropylation of biphenyl. The selectivity for 4,4′-diisopropylbiphenyl (4,4′-DIPB) over unmodified H-mordenite decreased with the increase of reaction temperature because of the isomerization of 4,4′-DIPB at the external acid sites. The isomerization was effectively prevented by the ceria modification of H-mordenites.
Coordination of Epithio Groups of p-tert-Butylthiacalix[4]arene in a Zn2+ Complex Studied by X-Ray Crystallography
Authors: Iki Nobuhiko , Morohashi Naoya , Kabuto Chizuko , Miyano Sotaro 
Published: May 2003

Abstract
Single-crystal X-ray analysis has shown that p-tert-butylthiacalix[4]arene (H4L) binds to Zn2+ ion by bridging sulfur atoms in addition to phenolic oxygen atoms to form [Zn4L(H2L)2].
Synthesis and Structure of the Cationic External Donor-Stabilized Silyleneiron Complex [Cp(OC)2Fe=Si(p-Tol)2·HMPA]PF6 by Hydride Abstraction from a (Hydrosilyl)iron Complex
Authors: Kobayashi Hideki , Ueno Keiji , Ogino Hiroshi 
Published: May 2003

Abstract
Hydride abstraction from a hydrosilyliron complex FpSiH(p-Tol)2 (1: Fp = CpFe(CO)2, Cp =η-C5H5, p-Tol = 4-C6H4Me) with Ph3CPF6 in the presence of HMPA (HMPA = P(O)(NMe2)3) afforded a cationic silyleneiron complex stabilized by HMPA [Fp=Si(p-Tol)2·HMPA]PF6 (2) in 88% yield. The X-ray crystal structure analysis of 2 revealed the relatively long Fe-Si bond and the short Si-O dative bond compared to those of the known donor-stabilized silylene complexes.
Highly Diastereoselective Reduction of Chiral (Ferrocenylseleno)methyl Aryl and Alkyl Ketones
Authors: Shirahata Makoto , Yamazaki Hiroshi , Fukuzawa Shin-ichi 
Published: May 2003

Abstract
Chiral (ferrocenylseleno)methyl aryl and alkyl ketones (3) were easily prepared by the reaction of chiral ferrocenylselenenyl triflates and silyl enol ethers. They were reduced by DIBAH to give corresponding β-hydroxy ferrocenyl selenides (4) in good yields with up to &gt;99% de.