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Inspired by the highly defined structure of biomacromolecules, e.g. deoxyribonuleic acid (DNA) and proteins, the preparation and characterization of sequence‐defined and uniform macromolecules gained interest in polymer chemistry. With the development of various synthetic approaches, the challenge of analyzing and confirming the uniform structures emerged. Here, the investigation on the performance of common analytical instruments for the characterization of uniform macromolecules regarding impurities of ±1 in degree of oligomerization is presented. Thus, different mixtures containing oligomers differing in one repeating unit of oligo(ethylene glycol)s (OEG)s, oligo(phenylene ethynylene)s (OPE)s, and Passerini oligomers, respectively, are synthesized, and analyzed by proton nuclear magnetic resonance spectroscopy (1H NMR), size exclusion chromatography (SEC), and high‐resolution electrospray ionization mass spectrometry (HR‐ESI‐MS). These results demonstrate the indispensability of a careful characterization using more than one technique for determining uniformity. In particular, the obtained SEC results show that it is a powerful tool for purity determination of low molecular weight oligomers. [ABSTRACT FROM AUTHOR]

Research Question/Issue: Are companies monitored by common owners (i.e., institutional investors that block‐own [owning 5% or more] several companies in a single industry) more likely than other companies to record goodwill impairments when their assets are overstated? Research Findings/Insights: We find that companies monitored by common owners are more likely than other companies to record goodwill impairments when their assets are overstated. The monitoring effect is stronger for common owners with a stronger incentive to monitor and with more industry knowledge and stronger for the co‐presence of multiple common owners. Our findings are in line with the notion that common owners have an economy of scale in monitoring and internalize the negative externality of delayed recording of goodwill impairment. We also find that common ownership is associated with lower information asymmetry, which in turn increases the timeliness of goodwill impairment. Theoretical/Academic Implications: Our research emphasizes the monitoring role of common ownership in recording goodwill impairments. We find support for the mechanisms enabling common owners to be better monitors. Practitioner/Policy Implications: The prevalence of common ownership has prompted regulatory and societal concerns regarding under‐investment in the oversight of the companies. Our findings documenting the association between common ownership and the timely recording of goodwill impairments are relevant to the ongoing debate regarding the potential costs and benefits of common ownership. [ABSTRACT FROM AUTHOR]

Here, we describe the preparation of bridged ethylene polyethylene oxide (BE‐PEO) surface‐modified silica packing materials for size exclusion chromatography. BE‐PEO surface‐modified silica was hydrolyzed and subsequent 1H nuclear magnetic resonance analysis of hydrolysis products confirmed the successful formation of BE‐PEO bonded surface. Silica particles exhibiting 3 µm diameters and 1000 Å nominal pore diameters were selected as a base material for this work out of the critical need to improve analytical capabilities for the testing of cell and gene therapy drug products. Accelerated high pH aging study revealed significant enhancement in column stability. Multi‐angle light scattering noise measurements showed inordinately lower baseline noise. Moreover, we evaluated the chromatographic performance of BE‐PEO silica‐packed columns through separations of a protein test mixture, DNA ladder, monoclonal antibody‐based therapeutics, and adeno‐associated viruses. BE‐PEO silica columns demonstrated high resolution, high recovery separations that were confirmed to be reproducible and capable of extended column lifetimes and exhibited low ionic and hydrophobic secondary interactions. In summary, BE‐PEO silica particles have yielded a new level of performance, improved base stability, and inherently lower baseline noise. These novel widepore particles will facilitate more sensitive size‐based detection and characterization of large biologics in the form of advanced gene therapy products. [ABSTRACT FROM AUTHOR]

In traditional Chinese medicine research, seaweeds used for drug and health food development mainly refer to Sargassum pallidum (Turn.) C. Ag. (SP) and Sargassum fusiforme (Harv.) Setch. (SF). In the Chinese Pharmacopoeia, polysaccharides are the main quality control indicators. The total sugar content is determined by the anthrone–sulfuric acid method to evaluate the quality of seaweeds. However, this method cannot reflect the structural characteristics of seaweed polysaccharides and cannot distinguish among different seaweed varieties. Given this, to comprehensively evaluate the quality of different seaweeds, this study conducted a thorough analysis of the primary structure of polysaccharides in 11 batches of SF and 7 batches of SP. The neutral sugar content was determined by the anthrone–sulfuric acid colorimetric method, weight average molecular weight (Mw) by high‐performance size exclusion chromatography coupled with multi‐angle laser light scattering and refractive index detector method, sulfate content by ion chromatography and monosaccharide composition by ultrahigh‐performance liquid chromatography method, while also using professional software for statistical and similarity analysis. The results showed significant differences (p < 0.05) in neutral sugar content and Mw between S. fusiforme polysaccharides and S. pallidum polysaccharides, which can be used to distinguish SF and SP. The monosaccharide composition fingerprint was analyzed using chemometric methods, and it was found that fucose and glucose could serve as differential markers to distinguish SF and SP. This study further deepens the understanding of polysaccharides in seaweeds and more comprehensively evaluates the quality of different seaweeds. [ABSTRACT FROM AUTHOR]

Extracellular domain (ECD) antigens are crucial components for antibody discovery, in vitro assays, and epitope mapping during therapeutical antibody development. Oftentimes, those antigens are difficult to produce while retaining the biologic function/activity upon extracellular secretion in commonly used expression systems. We have developed an effective method to cope with the challenge of generating quality antigen ECDs. In this method, a monoclonal antibody (Mab) or antibody fragment antigen‐binding (Fab) region acts as a "chaperone" to stabilize the antigen ECD through forming an antibody:antigen complex. This methodology includes transient co‐expression of the complex in Chinese hamster ovary cells and then dissociation of the purified complex into individual components by low pH treatment in the presence of arginine. The antigen is then separated from the chaperone on a preparative size exclusion chromatography (pSEC) followed by an optional affinity chromatography process to remove residual Mab or Fab. We demonstrate this co‐expression/disassociation methodology on two difficult‐to‐express antigen ECDs from cluster‐of‐differentiation/cytokine family and were successful in producing stable, biologically active antigens when the common methods using Histidine‐tagged and/or Fc‐fused protein failed. This can be applied as a general approach for antigen production if a Mab or binding partner is available. [ABSTRACT FROM AUTHOR]

This article focuses on two research questions arising from the 2010 U.S. Securities and Exchange Commission (SEC) Advisory on climate change reporting: (1) How does the discussion of climate change in SEC filings change after the Advisory? and (2) What are firms talking about when they talk about climate change? Findings were obtained from the 218,000 10‐K filings to the SEC during the 2000–2019 period. The study develops and applies text mining methodology based on extracting information from the "semantic associates" in the "neighborhoods" of indicative terms. On (1) it finds that climate change‐related reporting does increase substantially after the SEC guidance. On (2) a nuanced picture emerges. Firms with comparatively larger transition risks tend to discuss climate change comparatively more, focusing on regulation‐related topics. Firms exposed to the physical risks of climate change tend to discuss climate change somewhat less, focusing on meteorological topics. The results enrich our understanding regarding environmental policies and firms' behaviors regarding climate change. Theoretical and practical implications are provided. [ABSTRACT FROM AUTHOR]

Described here is the current status of the upgraded in situ size‐exclusion chromatography (SEC) system implemented with the D22 small‐angle neutron scattering (SANS) instrument at the Institut Laue–Langevin. Since its initial proof of principle in 2016, this SEC–SANS arrangement has been continuously requested by the user community, leading to the design of an upgraded version. A detailed description of the setup and its control is provided, and a few examples of protein structural investigations are presented, which will highlight the various possibilities and limitations of the setup to optimize experimental success. [ABSTRACT FROM AUTHOR]

The South Equatorial Current (SEC) in the south Indian Ocean (SIO) contributes to mass and heat exchanges among the Pacific, Indian, and Atlantic Oceans. By analyzing satellite and in situ observations, this study examines the seasonal structure and the interannual variability of the SEC. The SEC is mainly part of the Seychelles‐Chagos thermocline ridge (SCTR) circulation during December to April, and is composed of the internal SCTR circulation and the intrusive Indonesian Throughflow during May to November. The SEC thus presents straight and meandering routes in these two periods, respectively. Furthermore, observations and model experiments show that the SEC's meandering route has obvious interannual variability, with exceptional northwestward extension in 1994, 1997, and 2019 during the past three decades. These exceptional routes are caused primarily by extreme positive Indian Ocean Dipole (IOD) events, which induce a strengthened westward transport of the fresh water. These exceptional routes thus reflect the abnormal freshening in the SIO. Mooring observations reveal that a significant long‐term freshening event occurred in the SIO from August 2019 to at least July 2020. The persistent low salinity confirms that there is substantial water exchange in the SIO during the extreme positive IOD years. Plain Language Summary: The South Equatorial Current (SEC) in the south Indian Ocean is a critical current that contributes to intra‐basin and inter‐basin mass and heat exchanges. By combining in situ observations and model experiments, this study examines the seasonal structure and the interannual variation of the SEC. The SEC's structure is determined by the competition between the internal circulation and the intrusive Indonesian Throughflow, and thus presents straight and meandering routes in different months. Indonesian Throughflow is an ocean current supplying warm water from the Pacific to the Indian Ocean. The meandering route has obvious interannual variability, with exceptional northwestward extension in 1994, 1997, and 2019, which is mainly induced by extreme positive Indian Ocean Dipole (one of the dominant modes of variability of the Indian Ocean) events. Furthermore, mooring observations capture a long‐term freshening event in 2019–2020, verifying the substantial water exchange in the south Indian Ocean during the extreme 2019 positive Indian Ocean Dipole event. Key Points: The South Equatorial Current is composed of the internal circulation and the intrusive Indonesian Throughflow during May to NovemberThe extreme positive Indian Ocean Dipole events induce the exceptional northwestward extension of the South Equatorial CurrentObservations reveal a long‐term freshening event in the south Indian Ocean during August 2019–July 2020 [ABSTRACT FROM AUTHOR]

Pigeon iron–sulfur (Fe–S) cluster assembly 1 homolog (clISCA1) is a target protein for research into the biomagnetoreception mechanism, as the clCRY4/clISCA1 oligomer, a complex composed of the columnar clISCA1 oligomer and the magnetosensor candidate protein cryptochrome‐4 (clCRY4) oligomer, tends to orient itself along weak magnetic fields, such as geomagnetic fields, under blue light. To obtain insight into the magnetic orientation mechanism of the clCRY4/clISCA1 oligomer, we inspected magnetic field effects on the structure and molecular behavior of clISCA1 by small angle X‐ray scattering analysis. The results indicated that the clISCA1 protomer took the Fe–S cluster‐bound globular form and unbound rod‐like form. The globular clISCA1 protomer assembled to form columnar oligomers, which allowed for the binding of many Fe–S clusters at the interface between clISCA1 protomers. Moreover, the translational diffusion and the columnar oligomerization of clISCA1 were controlled by the external static magnetic field and Fe–S clusters bound to clISCA1. However, the columnar clISCA1 oligomer was not oriented along the external static magnetic field (~1 T) when clCRY4 was not bound to clISCA1. This result indicated that clCRY4 has a function to enhance the magnetic orientational property of clCRY4/clISCA1 oligomer. [ABSTRACT FROM AUTHOR]

Summary: We focus on textual analysis of the US Securities and Exchange Commission's accounting and auditing enforcement releases (AAERs). Our research question is: Did the Sarbanes–Oxley Act (SOX) 2002 affect the qualitative linguistic content of the AAERs in the post‐SOX period? To answer this question, we test the null hypotheses that there will be no differences in the qualitative verbiage and sentiment of AAERs in the time periods that we study related to the enactment of SOX: pre‐SOX and post‐SOX. To resolve the research question, we applied several text mining methods and classification machine‐learning methods. We first used two basic text‐mining methods, generating a bag of words and topic modeling, for descriptive analysis of the AAER content before the enactment of SOX and after the enforcement of SOX. We then conducted sentiment analysis using four sentiment dictionaries on the content of the two time periods: before SOX and after SOX. Finally, we developed three different classification models based on well‐known supervised learning algorithms and determined that SOX‐related AAERs could be distinguished from non‐SOX‐related AAERs. Based on the results, we conclude that there were significant linguistic differences in the AAER content of the post‐SOX period compared with the pre‐SOX period. In other words, post‐SOX‐related AAERs are qualitatively different in terms of linguistic contents and sentiment values compared with the non‐SOX‐related AAERs. [ABSTRACT FROM AUTHOR]

The commercially available partially bio‐based poly(butylene succinate) (PBS) and poly(butylene succinate‐co‐adipate) (PBSA) are subjected to prolonged and multiple extrusion cycles to investigate their thermal behavior. Empirically, both PBS and PBSA form branches at 190°C, with PBS possessing a higher tendency for branching than PBSA as studied by rheology and size exclusion chromatography (SEC). In each case, the branching is favored by fumaric acid moieties, making both PBS and PBSA susceptible to accelerated thermal oxidation. Indeed, the NMR signal attributed to fumaric acid disappears upon thermal processing of PBS and PBSA. Presumably, the bio‐based succinic acid used contains minor quantities of fumaric acid, yet still sufficient to cause this surprising processing behavior. The branching of both polymers is suppressed by stabilizers such as phenolic antioxidants, as proven by rheology and SEC. This is complemented by nuclear magnetic resonance (NMR), revealing that the fumaric acid signal is still well‐resolved in the stabilized processed samples. [ABSTRACT FROM AUTHOR]

Both exosomes and soluble factors have been implicated in the generation of an immunosuppressive tumour microenvironment. Determining the contribution of each requires stringent control of purity of the isolated analytes. The present study compares several conventional exosome isolation methods for the presence of co-enriched soluble factors while isolating exosomes from human melanoma-derived cell lines. The resultant preparations were analysed by multiplex bead array analysis for cytokine profiles, and by electron microscopy and nanotracking analysis for exosome size distribution and concentration. It is demonstrated that the amount and repertoire of soluble factors in exosome preparations is dependent upon the isolation method used. A combination of ultrafiltration and size exclusion chromatography yielded up to 58-fold more exosomes than ultracentrifugation, up to 836-fold lower concentrations of co-purified soluble factors when adjusted for exosome yield, and a greater than two-fold increase in PD-L1 expressing exosomes. Mechanistically, in context of the immunomodulatory effects of exosomes, the exosome isolation method should be carefully considered in order to limit any effects due instead to co-eluted soluble factors. [ABSTRACT FROM AUTHOR]

Recently, variable speed wind turbines (WTs) employing dual stator‐winding induction generators (DSWIGs) have gained interest in related kinds of literature. A DSWIG has two sets of stator windings known as power‐winding (PW) and control‐winding (CW), where CW is connected to a pulse‐width modulation converter called semiconductor excitation controller (SEC). This study, first, presents a topology for connection of DSWIG‐based WT to the grid, in which unlike most of the related kinds of literature, both the PW and CW contribute in transmission of active power to the grid. In the study system, PW is connected to the diode rectifier‐boost converter and CW to the SEC, and thus PW and CW active powers are controlled by the related boost converter and SEC, respectively. Hence, this study extends theoretical expression and presents a new relation for the generator torque as a function of the CW and boost converter currents, and then develops control structures for the study system. Next, mathematical expressions are presented for the selection of excitation capacitor at the PW terminals. Besides, the presented control strategy of the system is modified to enhance the WT‐low voltage ride‐through capability. In the end, simulation results are presented for examining the system performance and verifying the theoretical analyses. [ABSTRACT FROM AUTHOR]

Both exosomes and soluble factors have been implicated in the generation of an immunosuppressive tumour microenvironment. Determining the contribution of each requires stringent control of purity of the isolated analytes. The present study compares several conventional exosome isolation methods for the presence of co‐enriched soluble factors while isolating exosomes from human melanoma‐derived cell lines. The resultant preparations were analysed by multiplex bead array analysis for cytokine profiles, and by electron microscopy and nanotracking analysis for exosome size distribution and concentration. It is demonstrated that the amount and repertoire of soluble factors in exosome preparations is dependent upon the isolation method used. A combination of ultrafiltration and size exclusion chromatography yielded up to 58‐fold more exosomes than ultracentrifugation, up to 836‐fold lower concentrations of co‐purified soluble factors when adjusted for exosome yield, and a greater than two‐fold increase in PD‐L1 expressing exosomes. Mechanistically, in context of the immunomodulatory effects of exosomes, the exosome isolation method should be carefully considered in order to limit any effects due instead to co‐eluted soluble factors. [ABSTRACT FROM AUTHOR]

The mean‐field theory of Flory–Stockmayer for randomly branched polymers in the regime of strong chain overlap is extended to a calculation of MZ via the recursive method of Miller and Macosko. The formalism includes condensation polymers, copolymers, chain stoppers, bifunctional diluents to control the chain length between branch points, multiple branching agents, and arbitrary stoichiometries. MZ closely approximates the largest branched polymer in the system and is therefore a key parameter describing static scaling behavior near the gel point. Nonuniversal static scaling of MZ is illustrated with examples from the literature. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1415–1422 [ABSTRACT FROM AUTHOR]

Perfluorosulfonic acid ionomers have been widely used as proton‐conducting materials in polymer‐electrolyte membrane fuel cells and their dispersions in polar solvents are used to prepare proton‐conducting membranes as well as catalyst layers. While it has been known that the dispersed particles become monodisperse after heating to 230 °C or above, their size and shape have not been fully characterized yet. Cryogenic transmission electron microscopy images and small‐angle X‐ray scattering profiles of the dilute aqueous dispersions before and after heating to 240 °C have clearly shown that rod‐like particles became significantly shorter cylinders without changing their radii. Particle length distributions were lognormal and average molar mass and dispersity after heating to 240 °C were consistent with the values from size exclusion chromatography. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 813–818 [ABSTRACT FROM AUTHOR]

Abstract: Post‐translational modification of proteins by O‐linked β‐N‐acetylglucosamine (O‐GlcNAc) is catalyzed by O‐GlcNAc transferases (OGTs). O‐GlcNAc modification of proteins regulates multiple important biological processes in metazoans. However, whether protein O‐GlcNAcylation is involved in epigenetic processes during plant development is largely unknown. Here, we show that loss of function of SECRET AGENT (SEC), an OGT in Arabidopsis, leads to an early flowering phenotype. This results from reduced histone H3 lysine 4 trimethylation (H3K4me3) of FLOWERING LOCUS C (FLC) locus, which encodes a key negative regulator of flowering. SEC activates ARABIDOPSIS HOMOLOG OF TRITHORAX1 (ATX1), a histone lysine methyltransferase (HKMT), through O‐GlcNAc modification to augment ATX1‐mediated H3K4me3 histone modification at FLC locus. SEC transfers an O‐GlcNAc group on Ser947 of ATX1, which resides in the SET domain, thereby activating ATX1. Taken together, these results uncover a novel post‐translational O‐GlcNAc modification‐mediated mechanism for regulation of HKMT activity and establish the function of O‐GlcNAc signaling in epigenetic processes in plants. [ABSTRACT FROM AUTHOR]

Abstract: Integrating highly efficient luminescent dyes into poly(methyl methacrylate) matrices with well‐defined parameters, such as degree of polymerization and dispersity, is a key step in the development of emerging technologies such as fiber‐based solar collectors, sensors, contactless coupling devices and integrated light sources. In this work, four perylene‐based fluorescent dyes, perylene from Sigma‐Aldrich, Lumogen F Yellow 083 from BASF, Perylene Orange from TCI and Lumogen F Red 300 from BASF, were polymerized in bulk with methyl methacrylate. The molecular weight distribution was controlled by the ratio between the chain transfer agent and initiator and was measured by size exclusion chromatography. A dopant‐dependent increase in the degree of polymerization, in which the dye causes a drop in the concentration of active growing polymer chains, was observed. Spectroscopic online monitoring of the process in transmission mode confirmed this observation and indicated the formation of stable perylene radicals during the polymerization. Comparative experiments with fluorescent (metal) organic dyes did not show a similar effect. Fitting models for the dye‐dependent molecular weights for Lumogen Yellow and Lumogen Red are proposed. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This work investigates the two-step polymerization between methylene diphenyl diisocyanate (MDI), two different poly(tetramethylene oxide) macrodiols, and 1,4-butanediol (BD) as chain extender. At the end of the prepolymerization, the reaction mixture contains MDI in excess and a prepolymer with isocyanate end group. Then, BD and a solvent (tetrahydrofuran) were added to start the finishing stage under nominal stoichiometric equilibrium. The reaction was analyzed by Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance (1H-NMR), and size exclusion chromatography. 1H-NMR was employed to follow global concentrations of unreacted isocyanate end groups and internal urethane groups. This information enabled to estimate the following "effective" rate constants: k1 =1.07 x 10-3 L mol-1 s-1 for the prepolymerization; and k2=1.94 x 10-4 L mol-1 s-1 for the finishing stage. These values are subject to errors caused by biases introduced in the recipe, in the measurements, in the reaction conditions, in the quality of reagents, and in the reaction mechanism assumptions. Such errors also explain the dispersion of the published rate constants values. The ¹H-NMR measurements also enabled to estimate the evolution (with extent of reaction) of the numberaverage number of structural units along the prepolymerization and finishing stages; and such estimates reasonably verify Flory's classical expressions. [ABSTRACT FROM AUTHOR]

The folding/collapse of linear single chains to single-chain nanoparticles (SCNPs) is a field of intense activity. Current synthetic methods allow obtaining from sparse SCNP morphologies in solution - resembling those observed in intrinsically disordered proteins - to compact SCNP conformations, more akin to those displayed by globular enzymes. A useful characterization technique in the field of SCNPs is 'conventional' size-exclusion chromatography (SEC) with differential refractive index (DRI) detection, providing rapid and convincing evidence of SCNP formation through comparison of the SEC traces of the precursor and the SCNPs. Upon SCNP formation, a noticeable shift of the SEC curve toward longer retention times (i.e., lower hydrodynamic sizes) is observed. However, quantitative information embedded in the SEC curve about the actual 'compaction degree' of the SCNPs has not yet been extracted to distinguish between sparse and globular SCNPs. Here, a useful methodology for quantifying the compaction degree of SCNPs by SEC with conventional DRI detector is introduced allowing: i) construction of theoretical SEC curves corresponding to the collapse of a linear precursor having a log-normal molecular weight distribution to either sparse or globular SCNPs and ii) analysis of experimental SEC curves to estimate the actual morphology of synthetic SCNPs in solution. [ABSTRACT FROM AUTHOR]

ABSTRACT YY1 (Yin Yang 1) is a zinc finger protein with an essential role in various biological functions via DNA- and protein-protein interactions with numerous partners. YY1 is involved in the regulation of a broad spectrum of cellular processes such as embryogenesis, proliferation, tumorigenesis, and snRNA transcription. The more than 100 reported targets of the YY1 protein suggest that it contains intrinsically disordered regions that are involved in such diverse interactions. Here, we present a study of the structural properties of human YY1 using several biochemical and biophysical techniques (fluorescence, circular dichroism, gel filtration chromatography, proteolytic susceptibility) together with various bioinformatics approaches. To facilitate our exploration of the YY1 structure, the full-length protein as well as an N-terminal fragment (residues 1-295) and the C-terminal DNA binding domain were used. We found the N-terminus to be a non-compact fragment of YY1 with little residual secondary structure and lacking a well-defined tertiary structure. The results of our study indicate that YY1 belongs to the family of intrinsically disordered proteins (IDPs), which exist natively in a partially unfolded conformation. Proteins 2015; 83:1284-1296. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

A great number of studies have proven that sHsps protect cells by inhibiting protein aggregation under heat stress, while little is known about their function to protect cells under acid stress. In this work, we show that Hsp20.1 and Hsp14.1 oligomers dissociated to smaller oligomeric species or even dimer/monomer at low pH (pH 4.0 and pH 2.0), whereas no prominent quaternary structural changes were seen at 50 °C. Both oligomers and smaller oligomeric species exhibited abilities to suppress client aggregation at low pH and at 50 °C. These results suggest that sHsps may function in different modes in different stressed conditions. [ABSTRACT FROM AUTHOR]

The use of reliable reference compounds was recently shown as a powerful strategy for a thorough characterization of plasma-polymers, but their elaboration remains a topical issue since wet chemistry leads to linear structures with specific chain ends which poorly mimic the notorious disorder found in plasma-polymers. Here is proposed the elaboration of standards directly using aerosol assisted plasma polymerization. Exaggerating the phenomenon observed in a so-called ante plasma zone where no discharge is ignited but thick organic coatings are deposited brought the concept of discharge overfeeding to decrease the energy per particle and produce intermediate polymeric materials between conventional polymers and plasma-polymers, synthesized through a plasma-assisted free radical polymerization. [ABSTRACT FROM AUTHOR]

The present paper is focused on the use of promising bio-based thermoplastic--poly(L-lactic acid)--in textile applications and with possible limits related to its enhanced sensitivity to (bio)degradation. Linear and planar fabrics made of staple were exposed to standard washing cycles imitating the maintenance of textile materials. The effect of temperature and pH of the washing bath on the degradation rate of poly(L-lactic acid) was monitored by the abiotic hydrolysis test. The properties of the fabrics after carrying out the tests were evaluated from the changes of mass per areal weight, strength, and morphology of the fabrics. The changes of the structure of the polymer chains were assessed by differential scanning calorimetry, by the decrease of molar masses (determined using size exclusion chromatography) and of the viscosity of the polymer solutions, and by infrared spectroscopy. Poly(L-lactic acid) fabric finds application for various kinds of garments, and untreated fabric reliably tolerates 60 standard washing cycles. [ABSTRACT FROM AUTHOR]

An efficient route to architecturally defined, sub-20 nm soft nanoparticles fabricated from single polymer chains via intramolecular photodimerization of pendant anthracene units is presented. Photodimerization is confirmed by the disappearance of the characteristic anthracene π−π* absorption peak at ≈360 nm measured by UV-vis spectroscopy. Size exclusion chromatography (SEC) with UV, multi-angle light scattering (MALS), and viscometric detection confirms that as photodimers form, the chains fold to form nanoparticles, demonstrated by shifts in the SEC traces to longer retention times as a function of increased irradiation time. These shifts indicate a reduction in hydrodynamic radius, corroborated and quantified by viscometric data. MALS detector traces reveal the presence of a small amount of chain-chain coupling during this process, but confirm that this is primarily a single-chain phenomenon. Electron microscopy provides visual confirmation of nanoparticle formation. [ABSTRACT FROM AUTHOR]

The application of the systematic approach during detector offset determination in triple detector GPC polymer analysis has been shown to result in improvements in terms of the variations observed among the methods for molecular weight distribution determination. More importantly, the remaining, reduced variations are theoretically consistent with axial dispersion corrections proposed in the past. The use of the systematic approach for offset determination coupled with a robust axial dispersion correction offers the potential for completely reconciling the molecular weight results obtained from the three available methods of molecular weight determination in triple detector GPC. [ABSTRACT FROM AUTHOR]

Current results and limitations of a novel SEC-MR-NMR (size-exclusion chromatography-medium resolution nuclear magnetic resonance) system are presented, delivering a direct correlation of chemical structure and molecular weight. A 20 MHz 1H NMR spectrometer based on permanent magnets was combined with a SEC setup. The NMR sensitivity was improved by digital filters, shims, and a self-built flow probe when compared with time-domain instruments. For optimum NMR signal-to-noise ratio ( S/ N) of polymer fractions and concomitantly reduced S/ N of solvent signals, deuterated solvents or protonated solvents, with solvent suppression, were applied. Results are presented after optimization of both NMR and chromatographic components such as column dimension and volume flow. [ABSTRACT FROM AUTHOR]

Starch is the most important source of human food energy and also an important polymer for biofuels, processed food, and pharmaceutical industries. Precise determination of structural and functional properties of starch has been an outstanding factor for the improvement of dissolution and degradation processes, which are important procedures for commercial applications. Distinct separation techniques coupled with multiple detection methods such as Size Exclusion Chromatography (SEC), Field Flow fractionation (FFF), Analytical Ultracentrifugation, and Hydrodynamic Chromatography have provided powerful information about starch conformation. In the present review, we describe the usefulness and limitations of different separation methods particularly SEC and FFF, which are currently widely used. [ABSTRACT FROM AUTHOR]

Phytosterols are recognized as functional food components with cholesterol reducing properties in humans. The formation of phytosterol oligomers as a result of the thermo-oxidative degradation of sitosterol is shown to occur. The existence of oligomers is demonstrated by size exclusion chromatography (SEC) and confirmed by combined SEC-atmospheric pressure chemical ionization mass spectrometry (SEC/APCI-MS). A speculative structure for the sitosterol dimer with 3,7′ linkage is proposed consistent with data from tandem mass spectrometry and exact mass measurements. Higher molecular weight species arising from the formation of trimers or higher oligomers are seen in the mass spectra. Fragments of sitosterol formed by thermo-oxidative processes are also shown to oligomerize and their common structural characteristics are demonstrated by tandem mass spectrometry. The results presented provide evidence for the possible formation of oligomeric species involving sterols in addition to those known for acylglycerides in vegetable oils subjected to extreme oxidative stress such as in frying. [ABSTRACT FROM AUTHOR]

Prior research documents that US firms write off large in-process research and development charges (IPRD) for acquisitions, possibly overstating the current period expense to inflate future earnings. Consequently, in 1998, the US Securities and Exchange Commission (SEC) began scrutinizing IPRD charges. We use pre-acquisition R&D expenses of 144 target firms as a benchmark for assessing whether IPRD charges are appropriate. Overall, the results suggest that most firms during our sample period were not overly aggressive in expensing IPRD–especially for acquisitions subsequent to the SEC's scrutiny. The results also indicate that the SEC's intervention reduced the frequency of overstated IPRD charges. [ABSTRACT FROM AUTHOR]

Aprotinin, a bovine protease inhibitor of important therapeutic value, was expressed in tobacco plastid transformants. This disulphide bond-containing protein was targeted to the lumen of thylakoids using signal peptides derived from nuclear genes which encode lumenal proteins. Translocation was attempted via either the general secretion (Sec) or the twin-arginine translocation (Tat) pathway. In both cases, this strategy allowed the production of genuine aprotinin with its N-terminal arginine residue. The recombinant protease inhibitor was efficiently secreted within the lumen of thylakoids, accumulated in older leaves and was bound to trypsin, suggesting that the three disulphide bonds of aprotinin are correctly folded and paired in this chloroplast compartment. Mass spectrometric analysis indicated that translocation via the Sec pathway, unlike the Tat pathway, led predominantly to an oxidized protein. Translocation via the Tat pathway was linked to a slightly decreased growth rate, a pale-green leaf phenotype and supplementary expression products associated with the thylakoids. [ABSTRACT FROM AUTHOR]

The effects of pump failures in nine zone and pump configurations for the size-exclusion simulated moving bed purification of insulin are analyzed. Simulations based on verified intrinsic parameters are used to understand the dynamic wave phenomena. This understanding helps determine the best zone and pump configuration, determine the time window to recover from the degraded state, and formulate contingency responses to failures. The results show that the open-loop three-zone simulated moving bed is the best. It is more reliable, and has higher productivity and reduced residence time of the high molecular weight impurities. A disadvantage of the three-zone is the higher solvent consumption. In the recommended configuration: desorbent pump failure is critical and dual redundant pumps are recommended; feed pump failure is marginal and results in diluted product; and zone II pump failure is critical---the time window for corrective action is half a step-time. Zone pumps are recommended instead of outlet pumps because they do not result in stationary phase collapse from high pressure drop and allow higher productivity in pressure-limited systems. [ABSTRACT FROM AUTHOR]

Abstract: The effect of solvent on the rate of leuprolide degradation and on the structure of the degradation products was explored. Leuprolide solutions (370 mg/mL) were prepared in water and dimethyl sulfoxide (DMSO) for delivery in DUROS[sup TM] osmotic implants. Both solvent systems demonstrated better than 90% stability after 1 year at 37°C, where the DMSO formulation afforded better stability than the aqueous formulation and was used in subsequent clinical trials. The rate of leuprolide degradation in DMSO was also observed to accelerate with increasing moisture content, indicating that the aprotic solvent minimized chemical degradation. Interestingly, leuprolide degradation products varied with formulation vehicle. The proportions of leuprolide degradation products observed to form in water and DMSO at 37°C were hydrolysis > aggregation > isomerization > oxidation and aggregation > oxidation > hydrolysis > isomerization, respectively. Specifically, more N‐terminal hydrolysis and acetylation were observed under aqueous conditions, and increased Trp oxidation and Ser β‐elimination were seen under non‐aqueous conditions. Furthermore, the major chemical degradation pathway changed with temperature in the DMSO formulation (decreasing oxidation with increasing temperature), but not in the aqueous formulation. [ABSTRACT FROM AUTHOR]