1,720,962 research outputs found
Functional Polysaccharide Nanomaterials (PS-NMs) for the reduction of elevated serum cholesterol & progressive diet-induced obesity (DIO): A 'novel' application of PS-NMs.
No full textHigh plasma cholesterol (hypercholesterolemia) is a potential consequence of obesity that is becoming a major public health challenge. Excess caloric intake without a corresponding increase in energy expenditure is believed to be the major contributing factor to weight gain among Canadians leading to hypercholesterolemia. This ‘silent killer’, hypercholesterolemia is characterized by increased low-density lipoprotein cholesterol (LDL–C) that increases the risk of cardiovascular diseases which are still the leading cause of death and disability worldwide. Bile acid sequestrants (BAS), such as cholestyramine are positively charged indigestible resins that have been widely used for the treatment of hypercholesterolemia. However, it has many side effects, such as increasing the triglycerides level, constipation, flatulence, and abdominal pain all of which are due to its hydrophobic nature and large dose required for treatment.
Biopolymers are naturally occurring polymers and the polysaccharides (PS) is one of the subclasses, including cellulose, hemicellulose, starch, lignin, and chitin chitosan, gums etc. Among the PSs, cellulose is the most abundant and chitin the second. The amorphous regions of cellulose and chitin can be dissociated by acid hydrolysis, yielding high aspect-ratio rigid rod-like nanocrystals called cellulose nanocrystals (CNC) and chitin nanowhiskers (Cht.NWs). Moreover, chitosan (CS), which has a myriad of biomedical applications reported over the past centuries, can also be derived from chitin. All these nanoparticles (NPs) are proven to be excellent candidates for various applications as they possess S.M.A.R.T.© characteristics, which are sustainable, modifiable (due to the abundant surface primary hydroxyl groups), active (highly dispersible in water and shows physicochemical activity) renewable (easy surface modification making them renewable), and non-toxic (being natural, they are biocompatible). Thus, there is a significant motivation to modify these NPs with different cationic functional groups or polymers providing a platform to develop more efficacious natural polysaccharide nanomaterial (PS-NM) as BASs.
In this Ph.D. study, PS-NMs based biocompatible BASs were synthesized via the grafting of compounds with different quaternary ammonium groups (QAGs) (e.g. glycidyl trimethylammonium chloride i.e. GTMAC) or amino polymers (e.g. poly[2-(dimethylamino) ethyl methacrylate] i.e. PDMAEMA) onto CNCs, Cht.NWs and/or CS yielding quaternized/cationic NPs (Q-NP/C-NPs) with varying degrees of surface charge densities. The syntheses suggested that the (CNC/Cht.NW):(QAG containing compounds) of 1:10 yielded the largest surface charges. After purification, these Q-NPs were then characterized and evaluated using FTIR, dynamic and static light scattering (for structure confirmation, size, and zeta potential), potentiometric titration (for QAG or tertiary amino groups content, binding capacity), transmission electron microscopy (for the morphology of NPs), and UV-Vis spectroscopy. Most of the synthesized NPs possessed good aqueous dispersibility with diameters (DH) within the nano range (< 1µm), and the zetapotential (ZP) to be within the colloidally stable range (≥ ± 25 mV). The quaternary ammonium groups (QAGs) validated their high ZP values and the QAGs were from 0.8 mmol/g to 2.9 mmol/g.
The PS based NMs were strongly cationic, and they could be used to sequester negatively charged ligands (eg., anionic dyes or impurities, the bile salts from human GI systems, etc.) from aqueous samples in effluent treatment or reduced the LDL–C levels. Initially, the batch adsorption tests (BATs) with all these NMs were conducted using methyl orange (MO), a negatively charged dye as a model compound due to the lack of available techniques to quantify bile salts. The Qmax determined from the Langmuir Isotherm fitting model (~ 200 mg/g) strongly suggested that the nano-systems were excellent sequestrants for anionic compounds. Their scavenging performance for bile salt were evaluated using sodium cholate (SC or Na-Ch), one of the bile salts/acids (BS/BA) in the human body. The Qmax values were higher (Qmax for most of the NMs were > 300 mg/g) than MO, suggesting that the scavenging effects for SC were higher due to the combination of all three binding mechanisms, namely electrostatic, hydrophobic, and hydrogen bonding.
An electrochemical-based sensor for detecting SC was developed to quantify free or unbound BA/BSs in aqueous solutions. The Qmax data obtained from the BAT using this sensor showed promising binding of NMs with SC that further reinforced that all the NMs developed in this study were active bile acid sequestrants. In addition, from the carbon dioxide evolution analysis using Baker’s yeast, the PS-NM developed in this doctoral research displayed toxicity below that of cholestyramine, the widely used BAS in the market. Binding kinetics experiments showed the adsorption of SC onto these NPs was faster than cholestyramine, which suggested that the PS-NMs could be the BASs of choice and in vivo animal studies should be pursued
Characterization of counterion effects of gemini surfactants and in vitro studies of transfection efficiency for gene therapy in epithelial ovarian cancer.
Full text linkGene therapy has emerged as a promising strategy for the treatment or prevention of many acquired or genetic diseases that are considered incurable at the present time. Although viral and non-viral vector approaches are the major techniques employed for somatic gene transfer, non-viral vectors (cationic liposomes, dendrimers, chitosans, polymers & surfactants) have attracted great interest recently, due to their unique properties. A number of non-viral carriers have been extensively investigated and developed in recent years for targeted drug delivery or gene therapy in various pre-clinical/clinical trials. Despite this, the quest for new non-viral carriers with improved transfection and low toxicity is still proceeding, driven by a need to overcome safety concerns associated with viral vectors. Of the non-viral vectors, an intriguing class of building blocks which has elicited extensive interest are the third generation di-cationic surfactants: a class of bis-surfactants called “gemini surfactants (GSs)”. The interest is due to their unique self-assembly, hundredfold lower CMC (compared to their monomeric counterparts), thousand-fold improved surface activity, and ability to form a rich array of aggregate morphologies. In this project, the effect of various inorganic and organic counterions on micellization was studied and analyzed at air–water surfaces as well as in bulk solutions. Additionally, the size & zeta potential of the nanoparticles, and the in vitro transfection efficiency studies in human ovarian cancer cell lines were also analysed to investigate the dominant influence of the anions on the aggregation behavior and DNA delivery efficiency of eight surfactants of the ethanediyl-α,ω-bis-(dimethylhexadecyl-ammonium) type, [C16H33(CH3)2-N-(CH2)2-N-(CH3)2C16H33].2X– referred to as gemini 16-2-16; where X refers to the counterion were studied. Counterions of chloride (Cl–), bromide (Br–), ½ malate (C4H4O5– –), ½ tartrate (C4H4O6– –), adenosine mono phosphate, AMP (C10H13N5O7P–), guanosine mono phosphate, GMP (C10H13N5O8P–), cytidine mono phosphate, CMP (C9H13N3O8P–), and uridine mono phosphate, UMP (C9H12N2O9P–) were investigated and were classified into three different categories depending on their nature: (1) small inorganic counterions [chloride (Cl–), and bromide (Br–)] taken from the Hofmeister series were studied to focus on the effect of ion type; (2) Hydroxy-alkyl di-carboxylate counterions [malate (C4H4O5– –), and tartrate (C4H4O6– –)] were studied to focus on the effect of the hydrophilicity of counterions; and (3) heterocyclic ring containing nucleotide mono phosphate counterions were included to focus on mainly self-assembly and other parameters. We demonstrate the influence of different anions associated with this 16-2-16 series of gemini by analyzing the effect of counterions on the micellization and aggregation behavior of these gemini surfactants, characterized by determination of the critical micelle concentration (CMC), degree of micelle ionization (α), and free energy of micellization (ΔGM) and are discussed in terms of the hydrophilicity of anions, counterion hydration, interfacial packing of ions, and ionic morphology. Our results clearly revealed that a counterion effect on micellization and aggregate morphology, attributed to the balancing and controlling forces of the counterions to the surfactant itself. Hydrogen bonding among the –OH groups of the counterions (where applicable) and water molecules, as well as the strong hydrophobic interaction among the hydrocarbon side chains is postulated to be the main origins for the unique aggregation behaviors of these gemini surfactants. These amphiphiles can form both micelles and vesicles spontaneously with a micelle-to-vesicle transition at a concentration above the respective CMC. Furthermore, the size & zeta potential characterizations along with the in vitro transfection data manifest the significant impact of counterions on the GSs as therapeutic drug delivery carrier. Our transfection efficiency (TE) data also demonstrated that the surface charge density of the particles formed by the GSs is the predominant factor for cellular uptake and consequent TE of the respective GSs
Trend and Development of Soccer Research: An Observation
Full text linkThe game of soccer has been adopted by nearly every nation and it is one of the most decentralized sports in the world. Due to the popularity of soccer, several research studies on football’s performance have been conducted to satisfy the people’s interest. This systematic qualitative research used both online and offline approaches to compile the literature. Therefore, the current researcher would like to conduct an investigation that necessitates a study of soccer literature’s trends and development. The primary objective of this academic qualitative study was to examine soccer-specific skills, system and formation-based soccer studies, somatotype research in soccer, fitness research in soccer, wearable Global Positioning System (GPS) technology in soccer game, and drone technology in soccer game. The relationship between manual digit ratio (2D:4D) and soccer is also discussed, as well as how the prenatal testosterone hormone can affect soccer performance. Researchers discovered that today’s soccer game is more dynamic than previous types of soccer. The efficiency of skills is typically dependent on early decision making. The previous researchers have discussed new ways and methods for improving soccer performance. Since the issue is so extensive, the present researcher believes that more scientific research on soccer’s trend and development is required
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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