Lipoproteins of fetal and newborn calves and adult steer: A study of developmental changes

Serum lipoproteins in fetal and newborn calves were characterized and compared with those of adult animals. Fetal calf serum contains only low density (LDL) and high density (HDL) lipoproteins; the LDL is the major lipoprotein class. Fetal LDL are ca. 26.0 nm diameter and are morphologically unusual in that particles form linear aggregates or “chains” in which LDL have flattened, parallel sides. These particles contain only apolipoprotein B and are high in polar lipids. Fetal HDL consist of 8.2-nm, round particles which contain large amounts of chlesteryl ester thus suggesting an active lecithin: cholesterol acyltransferase system in the fetal state. The major protein in fetal HDL is apolipoprotein A−I (80%); however, another component with a molecular weight (MW) of ca. 9,000 is also present. Newborn calves show a 5-fold increase in HDL concentration. These particles are 9.0 nm spherical particles and they contain mainly apolipoprotein A−I although C-apolipoproteins are also present; the lipid and apolipoprotein composition of newborn HDL is similar to that of adults. Newborn calves possess very low density (VLDL) lipoproteins which have a mean diameter of 61 nm and are similar in size and composition to those of adult animals; their apolipoprotein composition is principally apolipoprotein B, although C-apolipoproteins and apolipoprotein A−I are also present. The LDL of neonatal and adult animals are similar in morphology, chemical composition and apolipoprotein content. In both instances, LDL are round particles ca. 19.0 nm diameter which contain less polar lipids than the fetal animal. Apolipoprotein B is the major protein in newborn LDL, but adult LDL additionally contains a protein of 27,000 MW which probably represents apolipoprotein A−I from overlapping α-migrating particles in this region. The altered morphology and composition of fetal LDL, together with the lack of VLDL, suggest that the LDL particles may be synthesized de novo. Preliminary data was presented at the American Oil Chemists' Society Meeting, 1979.     

Enzymatic method of increasing phosphatidylcholine content of lecithin

An enzymatic method was established to increase the phosphatidylcholine (PC) contents of soybean and egg lecithins. Other phospholipids of lecithin were phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidic acid (PA). Seven preparations of phospholipase D (PLD), PLD-1 to PLD-6 ofStreptomyces origin and PLD-7 of cabbage origin, were tested for their ability to increase PC by transphosphatidylation in the presence of choline chloride (CC). The reactions were carried out at 30 C in a biphasic system that consisted of an aqueous phase containing PLD along with a buffer (optimum pH) having desired concentration of CC and Ca²⁺ and an ethyl acetate phase containing lecithin phospholipids. Intermitttent samples were extracted and analyzed by HPLC. Four of six PLD’s ofStreptomyces origin showed good transphosphatidylation (increase of PC contents of soybean lecithin from approximately 35% to 60–70% on a phospholipid basis) at 2.5 M CC, but the other two microbial PLD’s completely hydrolyzed the phospholipids to PA. Cabbage PLD-7 showed poor transphosphatidylation. PLD-3 gave the highest PC contents (70%) at 1.75 M CC. One hundred percent transphosphatidylation of pure PE to PC was achieved with PLD-3. PI was inert to the attack of most PLD preparations examined with the exception that PLD-3 hydrolyzed PI significantly. Purified PI could not be transphosphatidylized to PC; 100% PA was formed. Soybean lecithin containing about 80% PC and purified egg yolk lecithin with 75% PC could be converted to products having 95% PC and almost 100% PC, respectively, by PLD-3 at 1.75M CC. Studies on Enzymatic Conversion of Phospholipids (v)     

Relationship between particle size and photochromic characteristics of tungsten oxide films prepared by electric current heating method using tungsten wire

Tungsten oxide films were deposited on glass substrates placed above tungsten wires heated by electric current in air. The film thickness in a region just above the wire (region A) was thinner than that in other region (region B). The observation using scanning electron microscope revealed that the films consisted of particles. The shapes of the particles were sphere in the region A while smaller octahedron shape was found in the region B. The amount of the particles in the region B was greater than that in A. The ratio of the number of small particles with a diameter ≤500 nm to the total particle number in the region A increased with decreasing applied voltage during the electric current heating, whereas, in the region B, the size of particles was ≤500 nm and had no applied voltage dependence. The films exhibited photochromism; the reflectance in the near-infrared region was decreased by the ultraviolet irradiation. In region A, the photochromic effects increased with decreasing applied voltage to the wire. On the other hand, in region B, the photochromic effects did not show the applied voltage dependence. Consequently, it was found that the obtained films showed positive correlation between photochromic effect and the ratio of the number of small particles (≤500 nm) to the total particle number. The particles in region B are suitable for mass production of the photochromic material because the photochromic effect and the amount of particles in region B are greater than those in A.     

Unusually tight aggregation in detonation nanodiamond: Identification and disintegration

A remarkable observation that detonation of oxygen-deficient explosives in an inert medium produces ultra-fine diamond particles having diameters of 4-5 nm was made four decades ago, but this novel form of diamond has never been isolated in pure form thereafter. The reason for the difficulty was that the core aggregates having a diameter range of 100-200 nm are extremely tight and could not be broken up by any known method of de-aggregation. After a number of futile attempts, we were able to obtain primary particles by using the recently emerging technique of stirred-media milling with micron-sized ceramic beads. The milled aqueous slurry of nanodiamond gave a stable, thick and dark-coloured colloidal solution. After light sonication, dynamic light scattering measurements gave a sharp distribution in the single-digit nano-range, and HRTEM indicated separate particles having diameters of 4-5 nm, which agreed with the X-ray value of 4.4 nm for the primary particles. A model is presented for the core aggregates, which resembles the well-known grape-shaped ‘aggregate structure’ of the hardest type of carbon black.     

Synthesis of brushite particles in reverse microemulsions of the biosurfactant surfactin

In this study the "green chemistry" use of the biosurfactant surfactin for the synthesis of calcium phosphate using the reverse microemulsion technique was demonstrated. Calcium phosphates are bioactive materials that are a major constituent of human teeth and bone tissue. A reverse microemulsion technique with surfactin was used to produce nanocrystalline brushite particles. Structural diversity (analyzed by SEM and TEM) resulted from different water to surfactin ratios (W/S; 250, 500, 1000 and 40,000). The particle sizes were found to be in the 16-200 nm range. Morphological variety was observed in the as-synthesized microemulsions, which consisted of nanospheres (~16 nm in diameter) and needle-like (8-14 nm in diameter and 80-100 nm in length) noncalcinated particles. However, the calcinated products included nanospheres (50-200 nm in diameter), oval (~300 nm in diameter) and nanorod (200-400 nm in length) particles. FTIR and XRD analysis confirmed the formation of brushite nanoparticles in the as-synthesized products, while calcium pyrophosphate was produced after calcination. These results indicate that the reverse microemulsion technique using surfactin is a green process suitable for the synthesis of nanoparticles.     

Oil-in-water emulsions formulated with sunflower lecithins: Vesicle formation and stability

Oil-in-water emulsions (30∶70, vol/vol) were formulated with sunflower lecithin to characterize the destabilization processes and the vesicles formed. Dispersions containing levels of 0.1% lecithin were more stable against coalescence than the control system. When the lecithin concentration was increased to 0.5%, the presence of spherical structures, such as vesicles, was recorded that occluded the emulsion inside. Vesicles underwent a creaming process, and a narrow coalescence zone was detected in the upper layers of the samples. As the lecithin concentration was increased, more vesicles were formed, representing as much as 80% of the system volume. A reduction in the average size of vesicles was observed at high lecithin concentrations (2.5 and 5.0%). The vesicle size distribution changed as a function of lecithin concentration, decreasing the ratio of large to small particles in the same way. Coalescence took place in zones where large-volume vesicles were in contact in the upper portion of the tube sample. The results obtained suggest that sunflower lecithins present interesting emulsifying properties that may prove useful in food technology.     

Preparation and characteristics of ultrafine metal particles immobilized on fine polymer particles

Ultrafine metal particles immobilized on fine copolymer particles were produced by reduction of copolymer particles–metal ion complexes. Submicrometer-size copolymer particles containing nitrogen, prepared by emulsifier-free emulsion polymerization, were applied. Transmission electron microscopy (TEM) observation and X-ray diffraction analysis indicated that ultrafine noble metal particles with diameter below 10 nm were formed and uniformly immobilized on the surface of copolymer particles. © 1995 John Wiley & Sons, Inc.     

Structure of Zirconia Prepared by Homogeneous Precipitation

The structure of pure zirconia powders prepared by homogeneous precipitation was examined by electron microscopy. Some of these powders consisted of metastable tetragonal zirconia in the form of spherical aggregates up to 1 μm in diameter. The size of single crystals within these particles exceeded 100 nm, which is much larger than usually reported for metastable zirconia. We conclude that the existence of these large teragonal monocrystals is due principally to the very fine internal porosity within the domains, which gave rise to a surface area/volume ratio sufficient to stabilize tetragonal zirconia by the same mechanism as in nanocrystalline powders.     

Electron microscopic observations of inclusion complexes of α-, β-, and γ-cyclodextrins

Inclusion complexes of α-, β-, and γ-cyclodextrins (α-, β-, and γ-CyDs) were prepared with poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), and poly(ethylene adipate) (PEA), respectively. By observing respective inclusion complexes by transmission electron microscopy, it was found that the crystalline complexes grew as follows: (1) α-CyD-PEO complexes formed a hexagonal crystal, (2) β-CyD-PPO complexes crystallized with hexagonal lateral packing of molecular columns with their axes tilted at the basal plane, and (3) γ-CyD-PEA crystallized in a tetragonal form with a super lattice with cell dimensions a=b=13.40 nm, which consisted of sub-cell with cell dimensions a′=b′=1.657 nm. No diffuse scattering was observed in the electron diffraction pattern of complexes of α-CyD-PEO and β-CyD-PPO, because disordering of guest molecules within host channels gave no diffuse scattering as long as host molecules were arrayed in an ordered way. γ-CyD-PEA complexes gave characteristic streaky diffuse scattering along a^* and b^*. Stacking faults occurred in γ-CyD-PEA complexes.     

Modification of textile fibres with nanolayers of fluorine-containing interpolymer complexes

A method of modifying textile fibres based on application by layers of an anchor polymer and a fluorine containing SF capable of forming a nanosize surface interpolymer complex that gives the fibres assigned properties is proposed. Formation of the interpolymer complexes of fluorine-containing SF with cationic water-soluble polymers was investigated. It was found that particles from 52 to 59 nm in size are formed as a result of the intermolecular interaction, and a modifying nanosize layer forms when they are deposited on the fibres and treated with heat. Surface modification is not inferior in quality to modification using polymer nanodispersions — synthetic fluorine-containing latexes. The modifying effect of the interpolymer complexes is almost independent of the nature of the textile materials.     

Rapid transmethylation of microgram amounts of phosphatidylcholine on potassium methoxide/celite columns1,2,3

A rapid and convenient method for the determination of acyl groups in phosphatidylcholine (PC) has been developed. Transmethylation reactions were carried out on potassium methoxideimpregnated Celite microcolumns that were readily prepared from Pasteur pipettes. The methods were tested on microgram amounts of synthetic L-α-phosphatidylcholines (di-14∶0; di-18∶2; α-16∶0-β-14∶0) and on egg yolk lecithin, in methylene chloride or hexane solution. Transmethylation of these lipids occurred rapidly at room temperature. Gas liquid chromatographic (GLC) analysis of the product methyl esters demonstrated that the reaction was neither selective for one acyl position of PC over the other, nor sensitive to the amount of unsaturation within the acyl group. The results of the acyl group analysis of natural egg yolk lecithin compared favorably with the results from an established procedure. Presented at AOCS 68th Annual Meeting, New York, May 1977. Reference to brand or firm name does not constitute endorsement by the U.S. Department of Agriculture over others of a similar nature not mentioned. Chloroform and carbon disulfide have been classified by OSHA as carcinogens and/or toxic materials; they should be handled with care under proper ventilation.     

Phosphatidylcholine hydroperoxide levels in human plasma are lower than previously reported

The quantification of PC hydroperoxide (PCOOH) in human plasma was studied by HPLC with chemiluminescence detection (HPLC-CL). We identified for the first time the monohydroperoxide of 1-palmitoyl-2-linoleoyl-PC hydroperoxide (PC 16∶0/18∶2-OOH) in plasma by LC-MS and HPLC-CL. The standard compound, PC 16∶0/18∶2-OOH (synthetic PCOOH), as well as PCOOH from egg yolk, was used. Comparison of the PCOOH concentration in each participant's plasma as determined by use of a Finepak SIL NH₂ column with 2-propanol/methanol/water as the mobile phase (system A, the conventional method) gave a higher concentration than did an LC-18-DB column with methanol containing 0.01% triethylamine (system B). The mean PCOOH concentration for the 43 healthy volunteers was 55.1±30.4 pmol/mL (mean±SD) for system A and 16.3±9.9 pmol/mL for system B. Moreover, the main peak of the plasma extract appeared at a different time from that of synthetic PCOOH or egg yolk PCOOH in system A, whereas in system B plasma sample retention time practically corresponded to that of standard PCOOH. These findings confirm that the PCOOH plasma concentration is not so high as previously reported.     

蛋黄磷脂的提纯

利用蛋白质不溶或微溶于某些溶剂的特点,用混合溶剂萃取粗蛋黄磷脂制备精蛋黄磷脂的工艺,该工艺易于实现工业化生产,磷脂纯度可达98%以上。     

TEM and electron tomography studies of carbon nanospheres for lithium secondary batteries

The structure of carbon nanospheres of 100-200 nm diameter, which showed superior high-speed charge-discharge behavior as the negative electrode in a lithium ion battery, was investigated with XRD, SEM and TEM with an electron tomography attachment. Observation of carbon 0 0 2 lattice images, as well as electron diffraction patterns, illustrated that heterogeneous microtexture was formed as the polyhedronization of the particle proceeded with heat-treatment. The outside region of the particle heat-treated at 2800 °C has stacking structure of aromatic layers with some distribution of d₀₀₂, while the center region consisted of non-graphitic. Structure defects seemed to be concentrated along the ridgelines of the polyhedronized particles after heat-treatment. The electron tomography technique clarified the morphology of the graphitized particles, although the images should be understood with other crystallographic measurements. A slice image computed in the 3D-reconstruction process showed the inner texture of the graphitized particles more clearly than the conventional TEM bright-field image.     

Growth of large-diameter (∼4 nm) single-wall carbon nanotubes in the nanospace of mesoporous material SBA-15

Single-wall carbon nanotubes (SWCNTs) have been synthesized by supported-catalyst chemical vapor deposition (CCVD) using one-dimensional (1D) channels of mesoporous silica (SBA-15; mean channel diameter, 6.0 nm) functionalized with carboxyl groups where Co and Fe complexes are encapsulated. The synthesized SWCNTs have much larger diameters than the SWCNTs synthesized by conventional CCVD. Transmission electron microscope observations reveal that large-diameter SWCNTs (<4.2 nm) are grown in 1D channels of SBA-15. Large metal particles formed in the channels should play an important role in the growth of the SWCNTs with larger diameters.     

Physicochemical characterization of psychosine by 1H nuclear magnetic resonance and electron microscopy

Krabbe's disease is an autosomal recessive disease that affects the lysosomal enzyme galactosylceramidase. The storage of one of its substrates, psychosine (β-galactosylsphingosine), is thought to be responsible for the induction of pathological changes. Psychosine has a free amine group which is necessary for the mediation of its toxic effects. In the present study, the physicochemical properties of psychosine were investigated. Nuclear magnetic resonance (NMR) detected pH titration was used to determine that the amine group had a pKa of 7.18±0.05. Pulsed-field gradient NMR spectroscopy was used to determine that the diffusion coefficient of 2.8 mM psychosine in D₂O at pD 4.46 or 7.04 is 1.16±0.02×10⁻¹⁰ m²/s or 0.77±0.02×10⁻¹⁰ m²/s, respectively. Negative staining electron microscopy (EM) studies of acidic and neutral solutions of psychosine also were performed. At pH 4.5, spherical structures were formed, which were relatively stable between 3, 120, and 216 h following preparation; the diameter ranged from ∼14 nm at the earliest time point to ∼18 nm at the last time point. The critical micelle concentration (CMC) was 1.26 mM at pH 4.0. At pH 7.1, the structures changed from spherical structures with a diameter of 15–23 nm, at the earliest time point, to a heterogeneous population of structures ranging from spherical structures, with a diameter of only a few nm, to irregularly shaped oblong structures that had one or more dimensions exceeding 100 nm. The NMR and EM data indicate that the deprotonation of the amine group causes psychosine to form aggregates that are unstable, which prevents a determination of the CMC at a neutral pH. These data indicate that molecular interactions of psychosine at the acidic pH of the lysosome, where it is normally digested, are more orderly than those at the pH of the cytoplasm or extracellular space where psychosine goes during disease.     

Indium Tin Oxide@Carbon Core-Shell Nanowire and Jagged Indium Tin Oxide Nanowire

This paper reports two new indium tin oxide (ITO)-based nanostructures, namely ITO@carbon core–shell nanowire and jagged ITO nanowire. The ITO@carbon core–shell nanowires (~50 nm in diameter, 1–5 μm in length,) were prepared by a chemical vapor deposition process from commercial ITO nanoparticles. A carbon overlayer (~5–10 in thickness) was observed around ITO nanowire core, which was in situ formed by the catalytic decomposition of acetylene gas. This carbon overlayer could be easily removed after calcination in air at an elevated temperature of 700°C, thus forming jagged ITO nanowires (~40–45 nm in diameter). The growth mechanisms of ITO@carbon core–shell nanowire and jagged ITO nanowire were also suggested.     

Lecithin in oil-in-water emulsions

Summary A study was made to investigate the use of purified phosphatide in I.V. emulsions. Lecithin isolated from egg yolk and purified by alumina and silica chromatography was analyzed by chromatographic strip techniques as a one-component material. Highly purified lecithin was found to be an inefficient emulsifier. Moreover emulsions containing highly purified lecithin were heat-sensitive. An emulsion physical stability test was developed to evaluate emulsifier formulations containing purified phosphatides for use with small amounts of emulsions (approximately 50 g.). Using this procedure, a considerable number of substances were tested as additives to enhance the purified lecithin's emulsifying power. None were found to be as effective as natural soybean phosphatide, which was used as a control. From these observations it is indicated that pure phosphatides are inefficient emulsifiers and that those phosphatide preparations possessing good emulsifying characteristics are presumably mixtures or complexes of the phosphatides with other substances. This investigation was supported in part by funds from the Office of the Surgeon General. One of the laboratories of the Southern Utilization Research and Development Division. Agricultural Research Service, United States Department of Agriculture.     

The molecular dynamic simulation on impact and friction characters of nanofluids with many nanoparticles system

Impact and friction model of nanofluid for molecular dynamics simulation was built which consists of two Cu plates and Cu-Ar nanofluid. The Cu-Ar nanofluid model consisted of eight spherical copper nanoparticles with each particle diameter of 4 nm and argon atoms as base liquid. The Lennard-Jones potential function was adopted to deal with the interactions between atoms. Thus motion states and interaction of nanoparticles at different time through impact and friction process could be obtained and friction mechanism of nanofluids could be analyzed. In the friction process, nanoparticles showed motions of rotation and translation, but effected by the interactions of nanoparticles, the rotation of nanoparticles was trapped during the compression process. In this process, agglomeration of nanoparticles was very apparent, with the pressure increasing, the phenomenon became more prominent. The reunited nanoparticles would provide supporting efforts for the whole channel, and in the meantime reduced the contact between two friction surfaces, therefore, strengthened lubrication and decreased friction. In the condition of overlarge positive pressure, the nanoparticles would be crashed and formed particles on atomic level and strayed in base liquid.     

Carbon nanotubes and onions from carbon monoxide using Ni(acac)2 and Cu(acac)2 as catalyst precursors

New catalyst precursors (copper and nickel acetylacetonates) have been used successfully for the synthesis of carbon nanotubes and onion particles from carbon monoxide. Catalyst nanoparticles and carbon products were produced by metal-organic precursor vapour decomposition and catalytic disproportionation of carbon monoxide in a laminar flow reactor at temperatures between 705 and 1216 °C. Carbon nanotubes (CNTs) were formed in the presence of nickel particles at 923-1216 °C. The CNTs were single-walled, 1-3 nm in diameter and up to 90 nm long. Hollow carbon onion particles (COPs) were produced in the presence of copper particles at 1216 °C. The COPs were from 5 to 30 nm in diameter and consisted of several concentric carbon layers surrounding a hollow core. The results of computational fluid dynamics calculations to determine the temperature and velocity profiles and mixing conditions of the species in the reactor are presented. The mechanisms for the formation of both CNTs and COPs are discussed on the basis of the experimental and computational results.