bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrospray mass spectrometry of phospholipids
Authors: Pulfer Melissa , Murphy Robert C. 
Published: August 2003

Abstract

I.
Introduction
332

II.
Techniques and Methods
334

A.  Sample Preparation
334

B.  ESI‐MS/MS
336

1.  Glycerophosphocholine (GPCho) Lipids
336

2.  Sphingomyelin
341

3.  Glycerophosphoethanolamine (GPEtn) Lipids
342

4.  Glycerophosphatidic Acid (GPA) Lipids
344

5.  Glycerophosphoinositol (GPI) Lipids
346

6.  Glycerophosphoglycerol (GPGro) Lipids
349

7.  Glycerophosphoserine (GPSer) Lipids
349

8.  Cardiolipin
351

C.  Matrix‐Assisted Laser Desorption/Ionization (MALDI) Analysis
353

D.  Precursor‐Ion and Neutral‐Loss Scanning
353

E.  Quantitation
355

III.
Research Applications
356

IV.
Conclusion
359

Acknowledgments
360

Abbreviations
360

References
360

Phospholipids play a central role in the biochemistry of all living cells. These molecules constitute the lipid bilayer defining the outer confines of a cell, but also serve as the structural entities which confine subcellular components. Mass spectrometry has emerged as a powerful tool useful for the qualitative and quantitative analysis of complex phospholipids, including glycerophospholipids and the sphingolipid, sphingomyelin. Collision induced decomposition of both positive and negative molecular ion species yield rich information as to the polar head group of the phospholipid and the fatty‐acyl substituents esterified to the glycerophospholipid backbone. This review presents the current level of understanding of the mechanisms involved in the formation of various product ions following collisional activation of molecular ion species generated by electrospray ionization of the common glycerophospholipids, including phosphatidic acid, phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol, phosphatidylserine, cardiolipin, and sphingomyelin. Recent advances in the application of matrix assisted laser desorption ionization is also considered. Several applications of mass spectrometry applied to phospholipid analysis are presented as they apply to physiology as well as pathophysiology. © 2003 Wiley Periodicals, Inc., Mass Spec Rev 22:332–364, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mas.10061
Synthesis of novel graft polyhydroxyalkanoates
Authors: Renard Estelle , Tanguy Pierre‐Yves , Samain Eric , Guerin Philippe 
Published: August 2003

AbstractGraft copolymers were synthesized by direct condensation of methoxy‐poly(ethylene glycol) (MePEG) or methoxy‐poly(lactic acid) (MePLA) onto a reactive polyhydroxyalkanoate (PHA) backbone in organic solvent. Side carboxylic groups of the PHA were coupled with end hydroxyl groups of MePEG or MePLA in the presence of N,N′‐dicylohexylcarbodiimide (DCC). Graft copolymers were characterized by 1H NMR spectroscopy and size exclusion chromatography (SEC). NMR spectra of PHA‐g‐PEG and PHA‐g‐PLA showed the presence of significant amounts of PEG and PLA, respectively. No noticeable unreacted PEG or PLA were detected in SEC chromatograms. Grafting of hydrophilic polymers chains as PEG or biodegradable oligomers as PLA onto PHA backbone will generate polyesters with a more rapid water uptake and faster biodegradation rates. These PHA polymers conjugates could be interesting for bioactive agent delivery systems.
Mechanical and thermal properties of poly(3‐hydroxybutyrate) blends with starch and starch derivatives
Authors: Innocentini‐Mei Lucia H. , Bartoli Julio R. , Baltieri Rodrigo C. 
Published: August 2003

AbstractPoly(3‐hydroxybutyrate) (PHB) is a highly crystalline, biodegradable and biocompatible thermoplastic. However, its limited utilization as a commodity plastic is associated to both high cost and very poor mechanical properties. Blending PHB with a natural polymer, such as starch, is one way to improve its properties and to get low price raw materials, though they are not miscible since there are no strong interactions between the hydrophilic starch and the hydrophobic PHB. In this study binary blends of PHB were prepared with natural starch, starch‐adipate and grafted starch‐urethane derivatives. The PHB blends were characterized in terms of their mechanical and thermal properties. For all blends a decrease of the Young modulus was observed as compared to the pure PHB. However, blends containing natural starches and starch adipate resulted in brittle materials. A significant decrease of both glass transition temperature (Tg) and melting point (Tm) was observed for all formulations. The best results, lower modulus and Tg were obtained with grafted starch‐urethane blends using poly(propylene glycol).
Aqueous phase size exclusion chromatography of polyvinylalcohols of different degrees of hydrolysis
Authors: Lacík Igor , Šnauková Radka , Šimková Barbora , Hanzelová Silvia , Alexy Pavol 
Published: August 2003

AbstractThe aqueous‐phase size exclusion chromatography (SEC) represents a suitable method for the analysis of molecular weight distribution (MWD) of polyvinylalcohols (PVOHs) of different degree of hydrolysis ranging from 72 to 98 mol‐% applying the Suprema columns. Eluents of different composition were used consisting of either a mixture of water and acetonitrile for the lower degrees of hydrolysis (72 ‐ 88 mol‐%) or 0.1 M LiNO3 solution for the higher degrees of hydrolysis (88 ‐ 98 mol‐%). By knowing the M̄w̄ values of commercially available PVOHs samples of a given degree of hydrolysis and using the commercial water soluble narrow distribution standards, a principle of the constant hydrodynamic equivalence ratios was applied to obtain the absolute values of the molecular weights of PVOHs of different degree of hydrolysis. The effect of a various number of extrusion cycles on MWD of different PVOHs was used to demonstrate the sensitivity of the selected SEC conditions.
Characteristics and degradation of hybrid composite films prepared from PVA, starch and lignocellulosics
Authors: Cinelli Patrizia , Chiellini Emo , Gordon Sherald H. , Imam Syed H. 
Published: August 2003

AbstractA research cooperation between USDA and the University of Pisa led to the development of several composite blends of poly(vinyl alcohol) (PVA) and lignocellulosic fibers. The cast films were prepared by blending orange fibers (OR‐fibers) and PVA with and without cornstarch to yield flexible and cohesive films. To improve properties, films were also prepared by crosslinking PVA, starch and OR‐fibers with hexamethoxymethylmelamine (HMMM). Films were evaluated for their thermal stability, water permeability and biodegradation. Thermal gravimetric analyses indicated the potential usefulness of such blends in several thermoplastic applications. Films were permeable to water, and retained the moisture content in the soil while retaining their integrity. Films generally biodegraded within 30 days in compost, achieving between 50‐80% mineralization. Both neat PVA and blends that had been crosslinked showed comparatively slow degradation. A possible stimulating effect of lingocellulosic fillers on the biodegradation of PVA in blends has been observed.
Thermoplastic processing of protein‐based bioplastics: chemical engineering aspects of mixing, extrusion and hot molding
Authors: Pommet Marion , Redl Andréas , Morel Marie‐Hélène , Domenek Sandra , Guilbert Stéphane 
Published: August 2003

AbstractProteins, as heteropolymers, offer a large range of possible interactions and chemical reactions. The thermoplastic behavior of proteins has been studied in order to produce bioplastics by thermal or thermomechanical processes such as mixing, extrusion or hot molding. The extrusion trials were performed by using a co‐rotating twin‐screw extruder, recording torque, temperature and die pressure. Batch mixing was done in a two blade counter‐rotating mixer, with continuous recording of torque and product temperature. Proteins were alternatively extruded, mixed or hot molded under a large range of processing conditions. Protein aggregation during each process was estimated from the accumulation of SDS‐insoluble protein fraction.Protein aggregation evidences a cross‐linking reaction the activation energy of which was dependent on the thermoplastic process used. The increase in network density appears to be induced by the severity of the treatment: temperature and shear strongly affect the structural characteristics of the protein‐based bioplastics.
Novel blends from agave fibers and poly(methyl methacrylate)
Authors: Koschella Andreas , Heinze Thomas , Rivera Armenta Jose Luis , Mendoza Martinez Ana Maria 
Published: August 2003

AbstractCellulose‐rich fibers were isolated from Agave lechuguilla (AL) and Agave fourcroydes (AF) growing in the Mexican northeast. These fibers are a valuable feedstock for the preparation of blends with synthetic polymers like poly(methyl methacrylate), PMMA. Blends of different types of agave fibers (dewaxed, mercerized, and grafted) and PMMA were prepared and investigated by means of tension measurements and dynamic mechanical analysis. The fiber‐containing blends are more stable than the plain PMMA. Surprisingly, the mechanical stability of the blends is practically independent of the pretreatment of the fibers.Methyl methacrylate (MMA) was grafted onto the biopolymer fibers initiated by the cerammonium nitrate redox initiator. Grafting yields of 26.5% were realized with fibers from AL while up to 75.8% MMA was grafted onto fibers from AF. The materials were characterized by means of FTIR spectroscopy and DSC.
Unconventional cellulose products by fluorination of tosyl cellulose
Authors: Koschella Andreas , Heinze Thomas 
Published: August 2003

AbstractThe synthesis of novel deoxy‐fluoro cellulose derivatives obtained by nucleophilic displacement reactions (SN) of p‐toluenesulfonyl (tosyl) cellulose with tetrabutylammonium fluoride (TBAF) is described. Detailed studies concerning the influence of the reaction time and temperature as well as the water content of the TBAF on the composition of the products were carried out. The SN reaction occurs even at room temperature. The degree of substitution of deoxy‐fluoro moieties (DSF) is in the range from 0.22 to 0.47. The polymers contain remaining tosyl groups. Preliminary 19F NMR measurements reveal the presence of the CH2F group. The degradation temperature of the deoxy‐fluoro cellulose derivatives is increased compared to the starting tosyl cellulose, however, a distinct influence of the remaining tosyl groups appears.
Multifunctional polyesters as new candidate materials for biomedical applications. Synthesis and structural characterization
Authors: Signori Francesca , Solaro Roberto , Chiellini Emo , Lips Priscilla A.M. , Dijkstra Pieter J. , Feijen Jan 
Published: August 2003

AbstractThe present work was aimed at the development of functional polymeric materials to be used in the targeted delivery of proteic drug and tissue engineering fields. The adopted strategy was based on the design of special polymer classes whose structures and functionality could be easily modified by finely tuned synthetic procedures. Poly(ether ester)s containing H‐bonding units were chosen as promising materials for the proposed applications. Commercially available precursors were successfully used for the synthesis of symmetrical diesters containing different H‐bonding groups (amide, carbamate, and urea moieties). In all cases, pure products were obtained in good yields. Bulk polycondensation of the monomeric precursors with different mixtures of 1,4‐butanediol and PEG 1000 diol afforded a variety of high molecular weight polymeric structures. Physical‐chemical characterization of the polymers indicates that their thermal, mechanical, and swelling properties can be tailored by a proper selection of the H‐bonding group and of the composition of the feed mixture.
An investigation of the condensation kinetics in poly(ester‐amide) and poly(ester‐sulphide) preparation
Authors: Solaro Roberto , Bizzarri Ranieri , Chiellini Emo 
Published: August 2003

AbstractSynthetic processes leading to hydrophilic biodegradable polymers for bio‐inspired applications were investigated from a kinetic point of view. In accordance with the reported mechanism of ester aminolysis, polycondensation reactions of α‐amino‐ω‐esters, diesters, and diamines resulted markedly dependent on the basicity of the alkoxide leaving‐group, being relatively fast for penthachlorophenate monomers. Furthermore, experimental data concerning the homopolycondensation of penthachlorophenyl α‐amino‐ω‐oligo(ethyleneglycol) succinates of different degree of oligomerization clearly showed the existence of concurrent first and second‐order processes, which were attributed to the intramolecular cyclization and intermolecular polycondensation reaction, respectively. In contrast to theoretical predictions based on the collision theory, however, minor incidence of the cyclization reaction was shown by the shortest monomers, thus suggesting a significant kinetic effect due to steric hindrance and solvent‐reagent interactions. Analysis of the base‐catalyzed Michael‐type addition of α,ω‐oligo(oxyethylene)dithiols to methyl (meth)acrylate allowed for the optimization of the relevant polymerization process involving hydrophilic diacrylates. Interestingly, very low reaction rates were determined for methacrylic components, supposedly because of steric and electronic factors connected to the presence of the α‐methyl group. Minor effects on the reaction rate were also induced by solvent polarity and catalyst nature.
Polymeric nanoparticles based on polylactide and related copolymers
Authors: Chiellini Emo , Covolan Vera L. , Orsini Lorenzo M. , Solaro Roberto 
Published: August 2003

AbstractThe preparation of nanoparticle suspensions was carried out by using commercial biodegradable polymers as poly(d,l‐lactide), poly(d,l‐lactide‐co‐glycolide) and poly(d,l‐lactide‐co‐ϵ‐caprolactone). The method of preparation was based on the controlled addition of polymer organic solution to an aqueous phase containing dispersing agents. Poly(ethylene glycol) (10, 20, and 35 kDa grade), Tween 20, and Pluronic F‐127 were used as dispersing agents in the aqueous phase. Content and type of both polymeric matrix and dispersing agent resulted of paramount relevance for the attainment of monodispersed nanoparticles with average diameter of about 130 nm. The addition of a steric stabilizer allowed for nanoparticle purification and isolation while preventing their agglomeration. The best results were obtained by using 35 kDa grade poly(ethylene glycol) as dispersing agent and either mannitol or glycidylisopropylidenglyceryl‐β‐cyclo‐dextrin as steric stabilizer. The adopted procedure afforded biodegradable nanoparticle suspensions that could be used for the incapsulation and intravenous administration of biologically active proteins and oligopeptides.
Biodegradable ultra high strength poly(L‐lactide) rods for bone fixation
Authors: Hyon Suong‐Hyu , Jin Fengzhe , Jamshidi Khosrow , Tsutsumi Sadami , Kanamoto Tetsuo 
Published: August 2003

AbstractThe hydrostatic molecular orientation technique was used to explore the highest mechanical improvements achievable for poly‐L‐lactide (PLLA). The mechanical attributes of these materials designed for bone fracture fixation devices, i.e. bending strength and modulus were measured and compared with those prepared by stretching method. The starting samples were prepared by conventional melt extrusion at 200 °C followed by hydrostatic extrusion at 140 °C using glycerin filled extruder. Uniaxially stretched rods were prepared by drawing in silicon oil at 120 °C. The physical properties of these rods are inadequate as mechanical supports in the dynamic healing process of the bone. Moreover, they underwent a marked strength deterioration when immersed in aqueous buffered solution for 90 days. On the other hand, the hydrostatic extrusion technique produced rods with progressively higher bending strength that showed only a small drop after 90 days hydrolytic degradation. Micrographs suggested a superior molecular orientation and packing, which could be associated with the improved performance. The hydrostatic extrusion technique proved to be a safe and effective approach for strengthening biodegradable polymeric materials for dynamic mechanical support in orthopedic medical devices.
Biodegradation of packaging materials: composting of polyolefins
Authors: Pandey Jitendra K. , Kumar A. Pratheep , Singh R.P. 
Published: August 2003

AbstractThe compostability of LDPE, PP and heterophasic E‐P Copolymers was studied for 5 months under normal and accelerated composting environments. Bio‐susceptibility of pre‐UV (290 nm) treated films (∼ 100μm, 5 X 5 cm) was measured by monitoring the weight loss, intrinsic viscosity [η], chain scission, functional group evolution (FT‐IR) and surface morphology (SEM). It was found that with the increasing time of UV treatment, weight loss was increased in compost. Almost linear decrease in [η] was observed for irradiated and composted samples. The temperature of compost and extra addition of thermophilic microbes significantly influenced the biodegradation. In general, it was concluded that the composition of copolymer markedly affected the compostability and increased ethylene content, slowed down the microbial activity.
The enzymatic degradation of commercial biodegradable polymers by some lipases and chemical degradation of them
Authors: Tsutsumi Chikara , Hayase Nobuki , Nakagawa Katsuhiko , Tanaka Suminori , Miyahara Yasushi 
Published: August 2003

AbstractBiodegradable polyesters, poly(butylene succinate adipate) (PBSA), poly(butylene succinate) (PBS), poly(ethylene succinate) (PES), poly(butylene succinate)/poly(caprolactone) blend (HB02B) and poly(butylene adipate terephthalate) (PBAT), were evaluated about degradability for enzymatic degradation by lipases and chemical degradation in sodium hydroxide solution. In enzymatic degradation, PBSA was the most degradable by lipase PS, on the other hand, PBAT containing aromatic ring was little degraded by eleven kinds of lipases. In 1N NaOH solution, degradation rate of PES with ethylene unit was extremely fast, in comparison with other polyesters. Interestingly the degradation rate of PBSA in enzymatic degradation by lipase PS was faster than in chemical degradation.
Additives for controlled degradation of agricultural plastics: ENVIROCARETM
Authors: Bonora M. , De Corte D. 
Published: August 2003

AbstractENVIROCARETM additives are specialty chemicals that can be added to conventional thermoplastic polymers to obtain degradable agricultural plastic articles. Their main benefits are connected with their possible incorporation in “commodity plastics”. This allows the production of degradable agriculture plastic articles processable with standard manufacturing machines, without negative effects on the main properties of the plastic article and with evident costs advantages. Furthermore, required outdoor exposure lifetimes for different articles and different environmental conditions can be modulated with the incorporation of the appropriate additive loading in the plastic and with combinations of selected stabilizers. Mulch films, small tunnel films, banana bags and sleeves, direct covers, non‐woven, ropes, twines and pots are convenient agricultural applications for this technology. ENVIROCARETM products induce plastic degradation following a two steps mechanism: first the plastic is photo‐ and thermo‐oxidized during the outdoor exposure; once the degradation process has been activated by light or heat, ENVIROCARETM acts by increasing the degradation rate and degradation continues until the article is totally degraded. Since degradation is both photolytically and thermally triggered, degradation occurs both at the surface and in the soil. Experimental laboratory results allow the assessment of the contribution of different important parameters ‐ i.e. type of polymer, type of article, presence of other stabilizers/additives or pigments, different environmental conditions‐ on the control of the article lifetime and degradation. Field exposure in different environments integrates the test results and allows for the design of the additive systems adapted to the specific needs.
Effect of the remaining lanthanide catalysts on the hydrolytic and enzymatic degradation of poly‐(ϵ‐caprolactone)
Authors: Gattin Richard , Cretu Adina , Barbier‐Baudry Denise 
Published: August 2003

AbstractPoly‐(ϵ‐caprolactone) is a biodegradable polymer, which can be used for both medical and environmental applications.Due to its multiple applications the synthesis of such a polymer has been attracting an increasing attention in the past few decades.In our work, the polymers were synthesised by bulk polymerisation, using different lanthanide halides as initiators. The lanthanide derivatives are known as very active catalysts in the ring‐opening polymerisation of cyclic esters. Moreover, they are not toxic in comparison of catalysts, which are usually used for this synthesis.In this paper, the influence of the lanthanides on both the hydrolytic and enzymatic degradation of the PCL obtained by ring‐opening polymerization of ϵ‐caprolactone with different lanthanide‐based catalysts such as: lanthane chloride (LaCl3), ytterbium chloride (YbCl3) and samarium chloride (SmCl3) was assessed.Samarium seems to slightly accelerate the hydrolytic degradation of the polymer and to slow down or inhibit its enzymatic degradation, mainly when the molecular weight of the polymer is high. The behaviour of PCL containing another lanthanide like lanthane is dependent on the nature of the metallic ion. Complete degradation, by the Lipase PS from Pseudomonas cepacia, is achieved only with Ytterbium.
Thermal and mechanical behavior of amorphous and semi‐crystalline poly(vinylidene fluoride)/poly(methyl methacrylate) blends
Authors: Jarray Jlidi , Larbi Fadhel Ben Cheikh , Vanhulle Faustine , Dubault André , Halary Jean Louis 
Published: August 2003

AbstractVarious PVDF/PMMA (poly(vinylidene fluoride)/poly(methyl methacrylate)) blends were selected for mechanical testing in compression. At low PVDF content (less than 50/50 w/w), the blends remain amorphous and PVDF and PMMA are fully miscible. In PVDF‐richer blends, PVDF crystallizes in part, leading to a PMMA‐enriched homogeneous amorphous phase. In this study, the degree of crystallinity was set at equilibrium by appropriate annealing of the samples before testing. Mechanical analysis was focused on the low deformation range, and especially on the yield region. Depending on the test temperature and blend composition, three types of response were identified, depending on whether plastic deformation is influenced: 1) by the PMMA secondary relaxation motions, 2) by the PVDF/PMMA glass transition motions, or 3) by the crystallite‐constrained PVDF chains.
Morphology and micromechanical behaviour of styrene/butadiene block copolymers and their blends with polystyrene
Authors: Adhikari Rameshwar , Michler Goerg H. , Knoll Konrad 
Published: August 2003

AbstractThe correlation between the morphology and the deformation mechanism in styrene/butadiene block copolymers having modified architecture and in blends with homopolymer polystyrene (hPS) was studied. It was demonstrated that the morphology formation in the block copolymers is highly coupled with their molecular architecture. In particular, the micromechanical behaviour of a star block copolymer and its blends with polystyrene was investigated by using electron microscopy and tensile testing. A homogeneous plastic flow of polystyrene lamellae (thin layer yielding) was observed if the lamella thickness was in the range of 20 nm. The deformation micromechanism switched to the formation of craze‐like deformation zones when the average PS lamella thickness changed to about 30 nm and more.