bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoluminescence and photoluminescence excitation spectroscopy of CdSe/ZnS core‐shell free standing nanocrystals in the ultraviolet spectral range
Authors: Podhorodecki A. , Misiewicz J. , Nauka K.
Published: November 2006

Photoluminescence and photoluminescence excitation spectroscopy measurements of CdSe/ZnS nanocrystals have been carried out to investigate its optical properties. The effect of rapid decrease of the emission intensity at 570 nm has been explained when the excitation wavelengths are higher than about 300 nm. This behavior has been related to the presence of additional recombination channels in the core/shell structure. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear optical microscopy of a single self‐assembled InGaAs quantum dot
Authors: Wesseli M. , Ruppert C. , Trumm S. , Krenner H. J. , Finley J. J. , Betz M.
Published: November 2006

Carrier dynamics in InGaAs/GaAs quantum dots is analyzed with highly sensitive two‐color femtosecond transmission spectroscopy. Especially, a single artificial atom is addressed in the optical near‐field of a nanometer scale shadow mask. Resonantly exciting the wetting layer beneath the nanoisland, we detect transmission changes of the quantum dot with narrowband femtojoule probe pulses. We find bleaching signals in the order of 10–5 that arise from individual interband transitions. Moreover, the nonlinear optical response reveals a picosecond dynamics associated with carrier relaxation in the quantum dot. As a result, we have demonstrated an ultrafast optical tool for both manipulation and read‐out of a single self‐assembled quantum dot. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of InAs quantum dot growth for electrical spin injection devices
Authors: Passow T. , Li S. , Litvinov D. , Löffler W. , Fallert J. , Daniel B. , Lupaca‐Schomber J. , Kvietková J. , Gerthsen D. , Kalt H. , Hetterich M.
Published: November 2006

The influence of the growth conditions during molecular‐beam epitaxy on the properties of InAs/GaAs quantum dot structures were systematically investigated by low temperature photoluminescence spectroscopy and transmission electron microscopy. The circular polarization degree (CPD) of the electroluminescence was compared for two quantum‐dot spin‐injection light‐emitting diodes. The CPD depends on the position of the emission energy in the luminescence band. This correlation is similar for both samples despite the strongly different quantum dot morphologies. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scanning transmission electron microscopy of vertically stacked self organized quantum structures
Authors: Sauerwald A. , Kümmell T. , Löffler A. , Somers A. , Reithmaier J. P. , Forchel A. , Bacher G.
Published: November 2006

Chemically sensitive scanning transmission electron microscopy in combination with electron energy loss spectroscopy is applied to investigate self organized quantum structures. The impact of vertical stacking on size and chemical composition of both quantum dots and quantum dashes is studied. In case of our InAs quantum dashes grown on an InP substrate, a strong increase of the structure size with layer number is found while the chemical composition of the quantum dashes remains constant. In contrast, we do not observe any significant change in both composition and size in case of vertically stacked InGaAs quantum dots grown on a GaAs substrate. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Infrared detector based on modulation‐doped quantum‐dot structures
Authors: Mitin V. , Vagidov N. , Sergeev A.
Published: November 2006

We investigate a detector model, where quantum dots are surrounded by potential barriers created by modulation doping. Strong separation of the localized ground states and continuum conducting states drastically increases the photoelectron capture time. At room temperatures the photoelectron capture is conditioned by electron diffusion in the potential relief. Monte‐Carlo modeling with diffusion‐limited capture in the modulation‐doped quantum‐dot structures is used to calculate carrier lifetime and photoconductive gain as functions of the electric field. We evaluate the photodetector characteristics and show that photoconductive gain is substantially improved due to longer lifetimes of photoelectrons. Optimized quantum‐dot structures have a strong potential for development IR room‐temperature detectors. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetically driven coupling of electronic states in quantum dot molecules
Authors: Voskobyonikov O. , Liu J. L. , Chen J. H.
Published: November 2006

We consider lowest energy states of electrons confined in asymmetrical circular vertically stacked double InAs/GaAs quantum dot molecule. The energies where computed by using the effective three‐dimensional one band Hamiltonian, the energy (non‐parabolic) and position dependent electronic effective mass approximation, and the Ben Daniel‐Duke boundary conditions with the finite hard wall confinement potential. We demonstrated theoretically a possibility to drive dynamically coupled electronic states (relocate electronic wave functions from one dot to another) by applying external magnetic field. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Morphology and photoluminescence of seeded three‐dimensional InAs/GaAs(001) quantum‐dot crystals
Authors: Kiravittaya S. , Rastelli A. , Schmidt O. G.
Published: November 2006

We investigate the morphology and photoluminescence (PL) of quantum dots (QDs) in seeded three‐dimensional InAs/GaAs quantum‐dot crystals (QDCs). The QDs in the QDC show a dome shape for the second QD layer and they have a pyramid shape in all subsequent layers. The PL from the QDC with 11‐fold stacked QD layers shows an intense PL signal with narrow inhomogeneous linewidth. Both ground state PL peak energy and PL linewidth remain almost constant over the patterned area. A power‐dependent PL measurement is performed and compared with a simple quantum disk model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Radiation pressure induced splitting of resonant modes in a nanocrystal‐coated microcavity
Authors: Gerlach M. , Rakovich Yu. P. , Donegan J. F. , Gaponik N. , Rogach A. L.
Published: November 2006

Melamine formaldehyde microspheres were coated with a soft polyelectrolyte multilayer (PAH/PSS) and one monolayer of CdTe nanocrystals. A micro‐PL setup was used to trap the sample within the tightly focused laser beam. The radiation pressure was used to deform the spherical shape of the polyelectrolyte multilayer which changes the optical properties of the resonance modes (whispering gallery modes) in the microcavity. Optically induced shifting and splitting of the resonances were observed with changing characteristics based on varying particular parameters such as laser intensity and focus position. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stark spectroscopy of Coulomb interactions in individual InAs/GaAs self‐assembled quantum dots
Authors: Kowalik K. , Krebs O. , Senellart P. , Lemaître A. , Eble B. , Kudelski A. , Gaj J. , Voisin P.
Published: November 2006

We present results of polarization‐resolved micro‐photoluminescence (μ‐PL) experiments on self‐organized InAs/GaAs (QDs). We have investigated how Coulomb interactions are modified by application of an electric field. We observed systematic variation of bright exciton splitting for different electric field configurations (applied in the quantum dot plane or along the sample growth axis). The results show also dependence of direct Coulomb interactions of carriers inside the dots, manifested by changes of PL line position of charged excitons (X+ and X‐) with respect to the neutral excitonic line. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence and photo‐excitation properties of laser heterostructures with CdSe/ZnSe quantum dots
Authors: Lyublinskaya O. G. , Sedova I. V. , Sorokin S. V. , Toropov A. A. , Ivanov S. V.
Published: November 2006

We report on the photoluminescence excitation studies of optically pumped Cd(Zn)Se/ZnMgSSe laser heterostructures with CdSe/ZnSe quantum dots (QDs) in the active region, grown by molecular beam epitaxy on GaAs substrates. The weak coupling of CdSe QD excitons with the standing‐wave modes of the cavity formed between the sample surface and the II‐VI/GaAs interface has been observed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐organized dots of GaN:Mn grown by molecular beam epitaxy
Authors: Kuroda S. , Marcet S. , Halley D. , Ferrand D. , Cibert J. , Mariette H. , Yamamoto S. , Sakai T. , Ohshima T. , Itoh H.
Published: November 2006

Self‐organized dots of Mn‐doped GaN were grown on AlN by plasma‐assisted molecular beam epitaxy. The growth was performed in the nitrogen‐rich growth regime with the addition of small amount of Mn flux. The in‐situ surface observation using reflection high energy electron diffraction (RHEED) and the ex‐situ examination using atomic force microscope (AFM) revealed that the dot formation was observed only in the case where the amount of Mn flux was small. The estimate of Mn composition using particle induced X‐ray emission (PIXE) experiment showed that the Mn composition in the dots layer was much higher than in thick (Ga,Mn)N layers grown with the same amount of Mn flux. The maximum Mn composition for the high‐density dot formation was about x = 0.01. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy dependence of the electron‐hole in‐plane anisotropy in InAs/GaAs quantum dots
Authors: Testelin C. , Aubry E. , Chaouache M. , Maaref M. , Bernardot F. , Chamarro M. , Gérard J.‐M. , Ferreira R.
Published: November 2006

In pump‐probe experiments, we measured the anisotropic exchange energy splitting of the low‐lying electron‐hole pair states in an ensemble of as‐grown InAs/GaAs self‐assembled quantum dots. This splitting shows a monotonic decrease with the energy of interband emission. We discuss this result considering different parameters: shape anisotropy, wavefunction confinement, size of the quantum dots, and piezoelectric effect. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Onset of GaSb/GaAs quantum dot formation
Authors: Timm R. , Lenz A. , Eisele H. , Ivanova L. , Pötschke K. , Pohl U. W. , Bimberg D. , Balakrishnan G. , Huffaker D. L. , Dähne M.
Published: November 2006

We present cross‐sectional scanning tunneling microscopy results on GaSb nanostructures in GaAs, analyzing their shape, size and chemical composition. By comparing different quantum wells and quantum dot layers, grown both by metalorganic chemical vapor deposition and by molecular beam epitaxy, the onset of quantum dot evolution is studied. Quantum dots are found already after a deposition of 1 monolayer GaSb. Intermixing of the deposited GaSb with GaAs due to anion exchange as well as different effects of Sb segregation during overgrowth are demonstrated. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High efficiency photoluminescence from silicon nanocrystals prepared by plasma synthesis and organic surface passivation
Authors: Mangolini L. , Jurbergs D. , Rogojina E. , Kortshagen U.
Published: November 2006

An efficient synthesis route for highly luminescent silicon quantum dots is presented. Silicon nanocrystals were synthesized in the gas phase using an argon‐silane non‐thermal plasma in a continuous flow reactor. Liquid phase surface passivation was used to improve the optical properties and avoid surface oxidation of the silicon quantum dots. Various alkenes, such as octadecene, dodecene and styrene, were covalently bonded to the plasma‐produced particles, while strictly avoiding exposure of the raw powder to oxidizing agents. Stable colloidal solutions of silicon quantum dots with ensemble quantum yields between 60% and 70% were achieved. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Memory inhibition in quantum‐wire transistors controlled by quantum dots
Authors: Müller C. R. , Worschech L. , Forchel A.
Published: November 2006

Current‐voltage characteristics of in‐plane gated quantum‐wire transistors with embedded InGaAs quantum dots are studied at low temperatures. Due to the floating gate function of the quantum dots, for small bias voltages a threshold hysteresis of up to 0.9 V is observed between the up sweep and the down sweep of the gate voltage. With increasing bias the threshold hysteresis decreases, is even suppressed for a critical bias voltage and inverts its sign for higher biasing. We associate this bias controlled memory function to a bias voltage dependent gate efficiency of the quantum‐wire transistor. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tuning the magnetic properties of ZnCdSe/ZnSe quantum dots by thermal annealing
Authors: Margapoti E. , Worschech L. , Mahapatra S. , Brunner K. , Bougerol C. , Forchel A.
Published: November 2006

Photoluminescence of ZnCdSe/ZnSe quantum dots treated by thermal annealing is investigated in magnetic fields up to 6 T. Thermal annealing leads to considerable changes of the circular polarization properties, which we attribute to different spin relaxation times and exciton lifetimes. A negative diamagnetic shift is observed for quantum dots showing the largest TA‐induced shift of 80 meV. Possible origins are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimisation of quantum dot resonant tunnelling diodes for fibre wavelength detection
Authors: Li H. W. , Simmonds P. , Beere H. E. , Kardynal B. E. , See P. , Ritchie D. A. , Shields A. J.
Published: November 2006

We report the development of a quantum dot (QD) based photon detector at a fibre optic compatible wavelength. The device structure is based upon a lattice matched InGaAs/InAlAs resonant tunnelling diodes (RTD), grown on an InP substrate, containing a layer of self‐assembled QDs. The principle of operation is based upon sensing the change in the tunnelling current due to the capture of photo‐excited charges in quantum dots. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Biexcitonic complexes and the decay dynamics of trion and exciton in a single CdSe quantum dot
Authors: Koch M. , Kheng K. , Robin I. C. , André R.
Published: November 2006

We report dynamical studies of a single CdSe quantum dot for various excitation densities. Exciton and trion states refilling by recombination of neutral and charged biexciton is revealed by the observation of a delayed decay for the sharp trion and exciton lines respectively for increasing excitation intensity. The biexcitonic complexes lifetimes are then estimated from the rise time of the excitonic decays. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
InAs/InP quantum dots: from single to coupled dots applications
Authors: Cornet C. , Schliwa A. , Hayne M. , Chauvin N. , Doré F. , Even J. , Moshchalkov V. V. , Bimberg D. , Bremond G. , Bru‐Chevallier C. , Gendry M. , Loualiche S.
Published: November 2006

We report a brief overview of recent research developments on InAs/InP quantum dots (QDs). Eight‐band k · p calculations are performed on single InAs/InP QDs, and the impact of substrate orientation ((311)B or (100)) on electronic and optical properties is studied. A configuration interaction model is used to determine few‐particle states of these dots and a comparison with micro‐photoluminescence experiments on single InAs/InP QDs is made. It is then demonstrated that high QDs density can be reached on such a system, leading to lateral coupling between dots. Calculations and (magnetophoto‐) (photo‐) (electro‐) luminescence experiments are used to demonstrate that the lateral coupling leads to miniband effects, and to a better charge carrier redistribution between QDs for laser applications. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Human milk: Quantitative gas‐liquid chromatographic analysis of triglyceride and cholesterol content during lactation
Authors: Watts Rodney , Dils R.
Published: November 2006

Gas‐liquid chromatography has been used to follow changes in the triglyceride composition of human colostrum and milk from one donor during the first 10 days postpartum and to compare the compositions obtained with those at later stages of lactation.

New triglycerides of low molecular weight appeared during the first 5 days postpartum. Lower molecular weight triglycerides (<C48) continued to increase until the eighth day. Triglyceride C48 and total cholesterol content remained almost constant during the period of the study.

Comparison of triglyceride fatty acid composition on the third, sixth, and ninth days postpartum showed considerable specificity in all cases, but a tendency for randomization to occur as lactation proceeded.

The advantage of triglyceride over fatty acid analysis for this type of investigation is that in the former, new molecules appear. In the latter, only changes in the proportions of fatty acids occur.
Studies on the preparation and analysis of glyceryl ether derivatives and the isolation and reductive ozonolysis of unsaturated glyceryl ethers
Authors: Ramachandran S. , Sprecher Howard W. , Cornwell David G.
Published: November 2006

Glyceryl ethers were identified and quantified by the GLC analysis of their alkyl iodide (special conditions described), acetonide and allyl alkyl ether derivatives. The acetoxy‐mercuri‐methoxy derivatives of unsaturated glyceryl ether swere separated from saturated glyceryl ethers by TLC and the fractions were analyzed as alkyl iodides. Monoiodides from saturated glyceryl ethers and diiodides from unsaturated glyceryl ethers were also separated by TLC and then analyzed. Allyl alkyl ethers had small retention volumes and these derivatives were separated into pure fractions by preparative GLC. Ozonides were reduced either to alcohols with lithium aluminum hydrodie or to aldehydes with dimethyl sulfide. The alcohols were converted to mono‐ and diiodides which were separated by TLC and analyzed by GLC. The recovery of n‐C6 and n‐C7 monoiodides was not quantitative. Diiodides and aldehydes were both identified and quantified by GLC. Ozonolysis data suggest that the 16∶1 glyceryl ethers from dogfish liver oil contain 7,8 and 9,10 isomers and the 18∶1 glyceryl ethers contain 9,10 and 11,12 isomers.
Fatty acids in lipids of maturing wheat
Authors: Klopfenstein W. E. , Pomeranz Y.
Published: November 2006

Two varieties of hard red winter wheat were sampled at various stages of maturity. The lipids in those samples were fractionated into free polar, free nonpolar and bound lipids. Fatty acids of those fractions were determined. Major acids present were palmitic, oleic, linoleic and linolenic. Both wheat samples showed similar qualitative, but not quantitative patterns in distribution of fatty acids during maturation. In the free polar lipid fraction, the palmitic acid content decreased with maturation while the linoleic acid content increased. The free nonpolar fractions showed a slight increase in linoleic acid; the concentration of other acids decreased slightly as the wheat matured. The bound lipid fraction showed a marked increase in linoleic acid, accompanied by decreases in the other major fatty acids, especially linolenic.
The effect of antioxidant deficiency on tissue lipid composition in the rat. II. Liver
Authors: Witting L. A. , Theron J. J. , Horwitt M. K.
Published: November 2006

The hepatic phospholipids of the antioxidant‐deficient rat fed a source of both linoleate and linolenate showed a progressive net decrease in eicosapentaenoate, a progressive net increase in arachidonate, and there was a concomitant accumulation of fluorescent pigment of the lipofuscin or ceroid type in the tissue. An increased incorporation of isotopically labeled acetate into both the tetraenoic and pentaplus hexaenoic acid fractions was also noted, indicating that the disappearance of polyunsaturated fatty acids was partially countered by increased synthesis. Comparable results were obtained on diets containing either suboptimum or adequate levels of biologically available selenium. Vesicular dilation of the endoplasmic reticulum was noted in animals fed the tocopherol‐deficient diet. In separate experiments using a necrogenic diet containing torula yeast, these subcellular alterations were found to be prevented by tocopherol but not by selenium, although selenium supplementation did prevent macroscopically observable damage.
Comparison of antioxidant activities of tocol and its methyl derivatives
Authors: Olcott H. S. , Van der Veen J.
Published: November 2006

In tests with purified menhaden oil at 37C and with squalene at 37C and 50C, unsubstituted tocol, 7,8‐dimethyl tocol (γ‐tocol), and 8‐methyl tocol (σ‐tocol) were superior antioxidants to 5,7‐dimethyl tocol and 5,7,8‐trimethyl tocol (α‐tocol). In contrast to previous reports, there were no differences in the order of the activities of the tocopherols at different temperatures.
Fatty acid metabolism in the chloroplast lipids of green and blue‐green algae
Authors: Nichols B. W.
Published: November 2006

The pattern of uptake of radioactivity into chloroplast lipids when a green alga (Chlorella vulgaris) was incubated with sodium 2‐14C‐acetate differed appreciably from that obtained when two blue‐green algae (Anabaena cylindrica andAnacystis nidulans) were incubated under similar conditions.

The fatty acids of the digalactosyl diglyceride and sulphoquinovosyl diglyceride fractions from the blue‐green algae were labeled more rapidly than were those of the corresponding fractions fromC. vulgaris, whereas the activity in the acids of the phosphatidyl glycerol fraction fromA. cylindrica andA. nidulans was relatively lower than that in the green alga. The results indicate that the metabolic behavior of chloroplast lipids may vary considerably according to the class of alga concerned.

In all three alga, the evidence points to an intermediary function for the chloroplast lipids in fatty acid synthesis.

Only limited exchange of acyl groups between the different chloroplast lipids seemed to occur during photoautotrophic growth.
Liver lipids during development
Authors: Baldwin Jerry , Cornatzer W. E.
Published: November 2006

The fatty acid composition of the major liver microsomal phospholipids has been studied during pre‐ and postnatal development of the rabbit. The fatty acid composition of the total lipids, phosphatidyl choline, and phosphatidyl ethanolamine from animals −6, −3, 0, +3, +6, +9, +16, and +112 days of age was determined. Fatty acid composition is similar in phosphatidyl choline and phosphatidyl ethanolamine for oleic acid at +3, +6, +9, and +16 day old animals; palmitoleic acid at +9 day old animals and linoleic acid at −6, −3, and 0 day old animals.

Palmitoleic acid demonstrated a uniform decrease during early development in the total lipids and in both phosphatidyl choline and phosphatidyl ethanolamine; however, in the 112 day animal, the amount was just slightly lower than that observed for the earliest prenatal animal studied. Oleic acid decreased considerably during early postnatal development in the total lipids, phosphatidyl choline and phosphatidyl ethanolamine, but an increase in the 112 day animal was observed. Linoleic acid fluctuated considerably throughout postnatal development in the total lipids as well as in the two major phosphatides.

Lecithin biosynthesis has been studied by two pathways during development of rabbit liver from −6 days to +110 days. The two pathways of lecithin biosynthesis were evaluated by assaying the activities of the liver enzymes choline phosphotransferase and phosphatidylmethyltransferase at different time intervals during development. The greater enzymatic activity was observed in the cholinephosphotransferase during development.
Studies on drug‐induced lipodosis (V). Changes in the lipid composition of rat liver and spleen following the administration of 4,4′‐diethylaminoethoxyhexestrol
Authors: Adachi S. , Matsuzawa Y. , Yokomura T. , Ishikawa K. , Uhara S. , Yamamoto A. , Nishikawa M.
Published: November 2006

Administration of 4,4′‐diethylamino‐ethoxyhexestrol increased total phospholipids and free cholesterol in rat liver. An elevation of a peculiar glycerophospholipid, lysobisphosphatidic acid, was marked both in liver and spleen. An increase in phosphatidylinositol was also noticed in spleen. However these changes in rats were not so marked as in human cases. There was an accumulation of a substance in rat tissue which was identified as a derivative of the drug, while the intact drug accumulated in large amount in human cases. Differences in the effect of 4,4′‐diethylaminoethoxyhexestrol on lipid metabolism between human and rat seem to be related to the difference in drug digesting ability between these two animal species.
The distribution of cyclopropane and cyclopropene fatty acids in higher plants (Malvaceae)
Authors: Yano I. , Nichols B. W. , Morris L. J. , James A. T.
Published: November 2006

The occurrence and distribution of cyclopropane and cyclopropene fatty acids has been investigated in seeds, leaves and other tissues of several species of Malvaceae. Sterculic and malvalic acids and their dihydro‐analogs were present in all the plant tissues examined, the highest proportions generally being in immature seeds. The cyclic acids were mainly concentrated in the neutral lipids with lesser proportions in phospholipid or glycolipid classes. The occurrence of these acids in all tissues of some species offered the attractive possibility of establishing callus tissue cultures capable of synthesizing cyclopropane and cyclopropene fatty acids and thereby providing a more convenient and reproducible system for biosynthetic studies. Substantial proportions of these cyclic acids were found in callus tissue cultures propagated from twoMalva species.
TheTrans‐6 fatty acids ofPicramnia sellowii seed oil
Authors: Spencer G. F. , Kleiman R. , Earle F. R. , Wolff I. A.
Published: November 2006

The C18 monoenoic acids inPicramnia sellowii Planch. seed oil include bothcis‐andtrans‐6‐octadecenoic acids, as well as oleic acid. The hexadecenoic acids are also thecis‐ andtrans‐Δ6‐isomers, and the eicosenoic acids have Δ6‐unsaturation of undetermined geometric configuration. The C18 polyenoic acids detected are 9,12‐ and 6,9‐octadecadienoic and 9,12,15‐ and 6,9,12‐octadecatrienoic acids. Partial investigation of another species,P. pentandra Sw., revealed its oil to have a similar fatty acid composition.
Long chain fatty alcohols in normal and neoplastic tissues
Authors: Blank M. L. , Snyder Fred
Published: November 2006

Small quantities of long chain fatty alcohols (esterified or free or both) were found in four normal tissues (about 0.01% of total neutral lipids) and three neoplasms (about 0.3% of total neutral lipids). The major chain lengths (16∶0, 18∶0 and 18∶1) of the fatty alcohols in both normal and neoplastic cells qualitatively resemble the O‐alkyl chain lengths of glyceryl ethers. Our data showing that long chain fatty alcohols occur in vivo support the biological significance of the metabolic pathway that uses fatty alcohols as a substrate for the alkyl chain in glyceryl ether biosynthesis.
The activating effect of dietary protein on linoleic acid desaturation
Authors: Peluffo R. O. , De Gomez Dumm I. N. T. , Brenner R. R.
Published: November 2006

The desaturation of14C‐1‐linoleic acid to γ‐linolenic acid and their incorporation into the microsomal lipids of rats fed on a balanced diet and a protein diet were measured in vitro. It was shown that a protein diet does not change significantly the distribution of the radioactivity among the different lipidic fractions compared to the animals fed on a balanced diet. However the microsomal desaturation of linoleic acid to γ‐linolenic acid increased in the rats maintained on a protein diet. Besides, the amount and composition of the free fatty acids present in the microsomes of the animals fed on both diets were similar enough to discard the hypothesis that they may modify the desaturation of linoleic acid produced by the diet. The enzymic activity of the linoleyl desaturase of liver microsomes of animals fed on a protein diet, measured in substrate saturating conditions, is greater than in animals with balanced diet. Consequently the results support the hypothesis that a protein diet increases specifically the desaturating activity of the microsomes.
Ring location in cyclopropane fatty acid esters by boron trifluoride‐catalyzed methoxylation followed by mass spectroscopy
Authors: Minnikin David E.
Published: November 2006

Methyl esters of methylcis‐ andtrans‐9,10‐methyleneoctadecanoic acids react with 50% boron trifluoride‐methanol to produce unsaturated and methoxy‐esters; both products are shown by gas chromatography to be a mixture of several isomers. Mass spectra of the methoxylated esters are characterized by intense peaks due to cleavage adjacent to methoxy‐functions which allow the position of the ring in the original cyclopropane ester to be easily assigned. Methyl oleate is also partially attacked by 50% BF3−MeOH to produce a mixture of methyl 9‐ and 10‐methoxyoctadecanoates. 14% BF3−MeOH does not react with cyclopropane and olefinic esters under the reaction conditions employed.
Properties of ultrasonically irradiated human serum lipoproteins
Authors: Sato J. , Shimasaki H. , Hara I.
Published: November 2006

Human serum low density lipoprotein (LDL) and human serum high density lipoprotein (HDL) were treated with ultrasonic irradiation. The immunochemical properties, spectrophotometrical analysis and thiobarbituric acid test (TBA) value of ultrasonically irradiated lipoproteins were examined. The agar gel precipitin reaction of sonicated LDL disappeared as the irradiation time increased. The effects of ultrasonic irradiation upon human serum lipoproteins resulted in a loss of lipids from the sonicated lipoproteins and are increased in TBA value. TBA value of LDL increased in two steps.
On the rate of cholesterol esterification in cord blood serum
Authors: Lacko Andras G. , Rutenberg Harold L. , Soloff Louis A.
Published: November 2006

Cholesterol esterification was studied in adult and cord serum by measureing the initial rate of lecithin‐cholesterol acyl transferase (LCAT) activity. Cord serum had about one‐third as much free and esterified cholesterol and about one‐half as much LCAT as adult serum. When the adult LCAT activities are plotted against the individual's serum free cholesterol levels a straight line relationship results (0.101±.005% cholesterol esterified per min). Cord serum LCAT activities (.135±.0407% cholesterol esterified per min) in the main fall above the adult line. Our results show that cord serum can esterify cholesterol at a rate equal to or higher than adult serum when the LCAT activity is related to the amount of serum free cholesterol present.
The effect of the environmental temperature on the fatty acid composition and on thein vivo incorporation of 1‐14C‐acetate in goldfish (Carassius auratus L.)
Authors: Knipprath Werner G. , Mead James F.
Published: November 2006

Two‐year‐old goldfish were adapted to 10C and 35C environmental temperatures during a three‐week period, and the fatty acids from triglycerides and certain phospholipids were analyzed by gas‐liquid chromatography. Over‐all unsaturation of the major fatty acids increased with lower temperature in all lipids which were examined although fish maintained at 10C actually had less polyenoic acid in their tissues than did those maintained at 35C.

Fish acclimated to 10C and 30C were injected with 1‐14C‐acetate, and the activities of the isolated fatty acids were counted. The incorporation of14C into the fatty acids was much greater at the lower temperature. A comparison of the activities of saturated and unsaturated fatty acids within each temperature group revealed a tendency toward higher incorporation into the unsaturated acids at lower temperature. The possible correlations between accelerated biosynthesis of polyenoic acids and the lower tissue levels of these acids in the cold‐adapted fish are discussed.
Quantitative gas chromatography, using retention times
Authors: Brandt A. E. , Lands W. E. M.
Published: November 2006

Diffusion of an injected sample within a gas chromatographic column does not begin from a point source but from a band. Therefore the method of calculating relative areas by using retention time × peak height may require a correction factor to give a more accurate estimate of peak areas. When this correction was applied, the analysis was comparable with that obtained by the more time‐consuming triangulation method.
Studies on liver phosphatidyl cholines: I. Effects of fatty liver induction on phosphatidyl cholines from liver mitochondria and microsomes
Authors: Miller James E. , Cornatzer W. E.
Published: November 2006

Protein, total phospholipid, phosphatidyl cholines and phosphatidyl choline fractions from liver mitochondria and microsomes of female rats were analyzed after treatment with CCl4 (0.3 ml of CCl4 suspended in corn oil) or ethionine (50 mg in 0.9% saline) or after feeding a choline deficient, low protein diet for seven days. Phosphatidyl cholines were separated into four fractions differing in the degree of fatty acid unsaturation. Over 50% of total phosphatidyl choline phosphorus was present in fraction 3 of liver mitochondria and microsomes. The major fatty acid in fraction 1 was docosahexaenoic acid. Fraction 4 contains oleic and linoleic acids. Arachidonic acid occurs in fraction 2 and 3. Ethionine decreased the amount of microsomal protein and phosphatidyl choline fraction 1 of mitochondria. Microsomal protein was decreased by CCl4. The choline deficient, low protein diet caused a decrease in mitochondrial and microsomal phospholipids. The amount of the mitochondrial phosphatidyl choline decreased. Corn oil increased the level of phosphatidyl choline fraction 3. Choline deficiency decreased the amount of phosphatidyl choline fraction 3, increased fraction 4 of mitochondria and microsomes and increased fraction 1 of microsomes.
Fatty acid composition of adultSchistosoma mansoni
Authors: Smith Thomas M. , Brooks Thomas J. , White Harold B.
Published: November 2006

The fatty acid composition of triglyceride and total phospholipid fractions of adultSchistosoma mansoni has been examined. Both triglyceride and phospholipid contained fatty acids varying in chain length from 12 through 24 carbons; trace amounts of shorter chain components were found in the triglyceride fraction. A docosahexaenoic acid in the triglyceride fraction represented the highest degree of unsaturation encountered. Branched chain fatty acids of 16 and 18 carbons were found in both phospholipid and triglyceride. Examination of fatty acids from fluke total lipid revealed the presence of small amounts of odd numbered carbon fatty acids varying in chain length from 13 through 23 carbons.
Two synthetic phosphonate analogs of lecithin
Authors: Rosenthal Arthur F. , Pousada Manuel
Published: November 2006

The diether‐phosphonate lecithin analog DL‐2‐hexadecoxy‐3‐octadecoxypropyl‐phosphonylcholine was prepared in 55% overall yield by reaction of 2‐hexadecoxy‐3‐octadecoxypropylphosphonic acid with choline iodide andp‐toluenesulfonyl chloride, and purified chromatographically.

The diester‐phosphonate lecithin analog 1,2‐dipalmitoyl‐sn‐glycero‐3‐[2′‐trimethyl‐ammonium) ethylphosphonate) was prepared fromsn‐glycerol‐1,2‐dipalmitate and 2‐(trimethylammonium) ethylphosphonyl dichloride, and the reaction mixture purified chromatographically. The lecithin analog was obtained in an anhydrous form.
Screening for serum lipoprotein abnormalities: Comparison of ultracentrifugal, paper and thin‐layer starch‐gel electrophoresis techniques
Authors: Lewis Lena A.
Published: November 2006

Three methods for evaluation of serum lipoprotein abnormalities were compared: paper electrophoresis using buffer containing albumin, ultracentrifugation at d 1.21, and thin‐layer starch‐gel electrophoresis. Analyses by paper electrophoresis and by ultracentrifugation of 109 sera of patients with cholesterol levels between 78 and 1150 mg/100 ml showed that the electrophoretic procedure while not quantitative was an effective procedure for detecting and helping in classification of the type of serum lipoprotein abnormality. Paper electrophoresis is a valuable procedure in screening for lipoprotein abnormalities and can be used as a guide for additional studies. Thin‐layer starchgel electrophoresis did not always give results comparable to those of the other two procedures. In study of certain sera (for example, in pigeon serum and some myeloma sera) lipoprotein subfractions were more clearly resolved by starch‐gel electrophoresis than by paper electrophoresis or ultracentrifugation. Ultracentrifugal and starch‐gel electrophoretic techniques can be used effectively when more complete information is needed or when unusual materials are being studied.
Free fatty acid metabolism during stress: Exercise, acute cold exposure, and anaphylactic shock
Authors: Paul Pavle , Holmes William L.
Published: November 2006

Rates of turnover and oxidation of plasma free fatty acid (FFA) were determined in unanesthetized dogs during exercise, acute cold exposure and anaphylactic shock, with the aid of a technique involving the continuous infusion of albumin‐bound palmitate‐1‐14C and the simultaneous measurement of O2 uptake, CO2 output and the specific activities of CO2 and FFA. During exercise in normal untrained dogs, plasma FFA supplied 20–30% of the energy, whereas in trained dogs 70–90% of the energy was derived from the FFA oxidation. In resting dogs at room temperature the plasma FFA level was 0.58 μEq/ml with a turnover rate of 18.6 μEq/kg/min of which 22% was immeditely oxidized and contributed 29% to the exhaled CO2. These results were compared with data obtained in pancreatectomized and thyroidectomized dogs. Acute cold exposure (temperature 4–5C) increased the FFA level and turnover rate to 1.02 μEq/ml and 28.0 μEq/kg/min, respectively, of which 33% was immedaitely oxidized, contributing 46% to the exhaled CO2. During anaphylactic shock, blood lactate increased, FFA level and turnover rate were reduced, and the fraction which was immediately oxidized was depressed markedly, i.e., 3–9% of FFA turnover. Sodium lactate infusion, which induces a blood lactate level comparable to that seen in anaphylaxis or nicotinic acid infusion, markedly decreased the level and turnover rate of FFA. However the fraction of turnover oxidized remained the same as during the preinfusion period (range of 21–40%. Exercise or the administration of norepinephrine during anaphylactic shock provided results suggesting that endogenous lactic acid interferes with FFA oxidation, whereas exogenous, lactate had no effect on this oxidation.
Hepatic galactosylceramide in globoid cell leukodystrophy (Krabbe's disease)
Authors: Dawson Glyn
Published: November 2006

Glycosphingolipids were isolated from the liver of four patients with globoid cell leukodystrophy and compared to those from normal liver. The ratio of glucosylceramide to galactosylceramide was 0.8, 1.2, 1.3 and 7.5 in the four cases studied, compared to a value of greater than 10 in liver from control patients of the same age and sex. In addition to this accumulation of galactosylceramide, all four livers showed an elevated level of sulfatide, and in one case trihexosylceramide and globoside were also markedly elevated.
Egg yolk lipids and maternal diet in the nutrition of turkey embryo
Authors: Couch J. R. , Ferguson T. M. , Cornett B. M.
Published: November 2006

Turkey hens were fed diets containing no added fat nor diets supplemented with soybean oil or neatsfoot oil. The composition of neutral and polar lipid fatty acids present in the unincubated turkey egg yolk was compared with that of those present in the yolk sac of the developing turkey embryo at different stages of development. Comparisons were made of the fatty acid fractions in the entire embryo homogenates, except liver and heart, which were analyzed separately. Changes in the relative amounts of the fatty acids are reported as affected by age of the embryo and by dietary lipids. The fatty acids from both the neutral and polar lipids which were utilized to the greatest extent for embryonic development were palmitoleic, oleic, linoleic, and linolenic, regardless of the dietary supplements. Arachidonic, tetracosenoic, and docosahexaenoic acids also were metabolized by the embryo. Saturated fatty acids, used by the embryo as development progressed, were palmitic, stearic, and arachidic acids. Analyses of the liver fatty acids showed that the C16∶0 C16∶1, C18∶0, C18∶1, and C20∶4 acids in the neutral and polar lipids decreased with embryonic development and varied with the type of diet. The heart contained low levels of myristic, palmitic, stearic, arachidic, and arachidonic acids in the neutral lipids and palmitoleic and oleic acids in the polar lipids.
Lipid labeling with32P‐orthophosphate and14C‐acetate in marine copepods
Authors: Farkas Tibor , Nevenzel Judd C. , Benson A. A.
Published: November 2006

Freshly collectedCalanus pacificus were maintained in sea water containing 25 μCi/ml [32P]orthophosphate or 1 μCi/ml [14C]acetate at 10 C for 24 hr. The animals took up label from the environment and incorporated it into various lipid fractions. After incubation with [14C]acetate the order of specific activity of the different lipid classes was: phospholipids > free fatty acids > wax esters > triglycerides. Argentation thin layer chromatography of the fatty acid methyl esters showed that ca. 50% of the activity was in saturated fatty acids and 34% in polyunsaturated acids. When the animals were exposed to [32P]orthophosphate, lysophosphatidyl choline became most heavily labeled, followed by lysophosphatidyl ethanolamine, sphingomyelin, phosphatidyl ethanolamine, and phosphatidyl choline. Comparison of the data obtained with those available for decapods and mammals revealed striking similarities between these phylogenetically distant groups. It is believed that labeling the lipids of marine and freshwater planktonic crustaceans in this way will provide much information about the metabolism of lipids in these organisms.
Alternate pathways of cerebroside catabolism
Authors: Lin Yuh‐Nan , Radin Norman S.
Published: November 2006

A search was made for new degradative pathways for glucosyl and galactosyl ceramides in an effort to explain the failure of these lipids to accumulate in the brains of children with Krabbe's or Gaucher's disease. Using various buffers and incubation conditions, we tested brain homogenates from 12 day old rats with the stearate‐labeled and galactose‐labeled lipids. No evidence for direct deacylation (and formation of psychosines) could be obtained, nor was there any evidence for transacylation of sphingocyl phosphoryl choline or oxidation of the 6 position of the galactose moiety. Two new derivatives of galactosyl ceramide were observed, possibly fatty acid esters of unknown polar compounds. It is tentatively proposed that the etiology of infantile Krabbe's and Gaucher's diseases involves, not an accumulation of galactosyl and glucosyl ceramides, with consequent formation of toxic products, but rather malfunction of some other role of the corresponding glycosidases.
Excretion of lipids by the liver fluke (Fasciola Hepatica L)
Authors: Burren C. H. , Ehrlich I. , Johnson P.
Published: November 2006

Adult liver flukes kept in a glucoseenriched medium were found to excrete lipids. Analysis of the incubation medium showed that both neutral lipids (including cholesterol and its esters) and polar lipids were released. The rate of lipid excretion was greatly reduced when the excretory pores and mouths of the flukes were ligated. Histochemical examination of the flukes indicated that such lipids, released through the excretory pores, originate in the cells lining the excretory ducts.
The occurrence of diastereomers of phytanic and pristanic acids and their determination by gas‐liquid chromatography
Authors: Ackman R. G. , Hansen R. P.
Published: November 2006

The methyl esters of phytanic (3,7,11,15‐tetramethylhexadecanoic) and pristanic (2,6,10,14‐tetramethylpentadecanoic) acids derived from phytol each can be resolved into two diastereomers by gas‐liquid chromatography on an efficient open‐tubular, gas‐liquid chromatographic column with a polyester coating. Authentic D,D,D isomers prepared from the lipids of bacteriumH. cutirubrum gave only one peak. In mammals the D,D,D isomers usually predominate, but in marine life the L,D,D isomers apparently are the principal forms. The origin and metabolic roles of the diastercomers are discussed.
Polarography of conjugated unsaturated lipids
Authors: Kuta Edwin J. , Yu Mary
Published: November 2006

Conjugated fat‐soluble vitamins, methylenic interrupted and conjugated fatty acids were polarographically investigated in both basic and neutral solvents. The half‐wave potentials of all‐trans‐retinol, 13‐cis‐retinol, all‐trans‐retinyl acetate, all‐trans‐retinal, and Vitamin D2 and D3 were related to the number of double bonds in conjugation and their geometrical configuration. A minimum of three double bonds in conjugation and their geometrical configuration. A minimum of three double bonds in conjugation was required before reduction took place at the cathode, and as the number of conjugated bonds increased in the lipid compounds, the initial reduction wave took place at a lower half‐wave potential.

Investigation of conjugated double bonds in triglycerides and in alkali‐isomerized linolenic and arachidonic acids gave reduction waves the half‐wave potentials of which were related to the number of double bonds in conjugation. In both basic and neutral solvents there was a minimum of three double bonds in conjugation necessary to obtain a reduction wave at the dropping mercury electrode. Ultraviolet absorption curves of the prolonged reduction of polyunsaturated conjugated fatty acids indicate a step‐wise reduction of each end of the polyunsaturated conjugated double bonds.

In neutral solvent the log of the conjugated double bonds versus the half‐wave potential (versus mercury pool anode) gave a linear equation, E1=2.98−1.6 log C. A proposed mechanism for the step‐wise reduction of conjugated lipids is presented and discussed.
Role of luminal lecithin in intestinal fat absorption
Authors: O'Doherty P. J. A. , Kakis G. , Kuksis A.
Published: November 2006

The effects of biliary lecithin on fat absorption were studied in 1 day bile fistula rats fed micellar solutions of bile salt, monoglyceride and radioactive free fatty acids. By electron microscopy and measurement of uptake of radioactivity into liver and adipose tissue, it was shown that in the absence of bile lecithin there was significant impairment of fat release from mucosa. Fat clearance was effected by the feeding of phosphatidyl choline or choline, but not phosphatidyl ethanolamine, inositol or cholesterol. In the absence of luminal choline there was a decrease in incorporation of radioactive leucine into mucosal protein. It is concluded that biliary and dietary lecithin or choline play an important role in triglyceride transport out of intestinal mucosa, by providing surfactant lecithin for the chylomicron envelope and by supporting mucosal protein biosynthesis.
Application of silica gel‐sintered plate to thin layer lipid chromatographic analysis
Authors: Itoh T. , Tanaka M. , Kaneko H.
Published: November 2006

The merits and disadvantages of using the silica gel‐sintered plate for lipid chromatographic analysis were investigated in detail. The commercially available sintered plate could be used repeatedly, employing the reconditioning procedure which involved chromic‐sulfuric acid treatment and subsequent activation. The reconditioned sintered plate has now been used successfully 20 times, for lipid analysis without any deterioration of the excellent resolution power for complex lipid mixtures for all the solvent systems. Since the sintered plate is sturdy, the chromatogplate could be immersed directly in the liquid reaction mixture, so that spots on the chromatogram could be seen and impregnated plates prepared simply. The sintered plate was found to be much more economical than the silica gel‐coated plate.