Cellulose-Ester as Membrane Materials for Hemodialysis

1994 ◽  
Vol 17 (7) ◽  
pp. 385-391 ◽  
Author(s):  
M. Diamantoglou ◽  
H.D. Lemke ◽  
J. Vienken
Keyword(s):  
Blood Compatibility ◽  
Degree Of Substitution ◽  
Cellulose Ester ◽  
Regenerated Cellulose ◽  
Special Focus ◽  
Standard Type ◽  
Cellulose Esters ◽  
Recent Developments ◽  
Cellulosic Membrane ◽  
Chain Lengths

The majority of dialysis membranes are fabricated from regenerated unmodified cellulose. This standard type of cellulosic membrane is frequently under attack because of its alleged lack of biocompatibility. Recent developments, however, have proven that a chemical modification of the reactive surface groups of regenerated cellulose, the hydroxylgroups, limits the complement-activating potential of these materials and thus improves its blood-compatibility. We extended the idea of modifying cellulose for improved blood-compatibility to a series of different cellulose esters. Special focus was directed towards the question whether a variation of the type of substituent and degree of substitution could influence the blood-compatibility pattern of these materials: the analysis of blood-compatibility profiles showed a direct dependency on the type of substituent and the degree of substitution (DS). As an example, it was found that the DS, necessary for a complete reduction of complement activation, decreases with increasing chain lengths of aliphatic substituents. Optimal degrees of substitution are characteristic of the type of substituents and enable us to tailor materials specifically for optimized blood compatibility.

Preparation and characterization of cellulose bromo-isobutyl ester based on filter paper

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Rina Wu ◽  
Qiuyu Wang ◽  
Huayu Liu ◽  
Gaosheng Wang ◽  
Peng Lu
Keyword(s):  
Filter Paper ◽  
Food Packaging ◽  
Degree Of Substitution ◽  
Raw Material ◽  
Esterification Reaction ◽  
Dimethyl Formamide ◽  
Cellulose Ester ◽  
Cellulose Esters ◽  
Simple Method ◽  
Isobutyl Ester

AbstractCellulose bromo-isobutyl ester was prepared using filter paper as raw material through esterification reaction with 2-Bromoisobutyryl bromide (BIBB) in N, N-Dimethyl-formamide (DMF). Cellulose esters with different degree of substitution were obtained. FTIR result indicated the successful introduction of bromo isobutyryl group in cellulose to obtain cellulose ester (Cell-Br). The surface of modified filter paper become rough and grooves could be observed by SEM. The thermal stability of the cellulose ester decreased in comparison with unmodified filter paper. Besides, the hydrophobicity of the filter paper was improved and the water contact angle increased from 73.4° to 116.5° with increasing degree of substitution. The water vapor barrier property was improved by 26 %. Furthermore, it was also found the modified filter paper possessed antibacterial activity against S. aureus bacteria. The modified filter paper obtained could be potentially used in food packaging fields and the results provide a simple method to prepare functional filter paper.

Esterification of cellulose with betaine using p-toluenesulfonyl chloride for the in-situ activation of betaine

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7592-7607
Author(s):  
Yu Liu ◽  
Fangfang Wang ◽  
Yangyang Sun
Keyword(s):  
Synthesis Method ◽  
Degree Of Polymerization ◽  
Degree Of Substitution ◽  
Molar Ratio ◽  
Esterification Reaction ◽  
Cellulose Ester ◽  
Cellulose Esters ◽  
In Situ Activation ◽  
Modified Cellulose

A novel synthesis method was developed for betaine-modified cellulose ester using a mixed N,N-dimethylacetamide/lithium chloride solvent system; p-toluenesulfonyl chloride was used for the in-situ activation of the betaine. The influence of the reaction temperature and time, as well as the anhydroglucose unit to p-toluenesulfonyl chloride to betaine mass ratio on the degree of substitution of the product was evaluated. Increasing the proportion of betaine and p-toluenesulfonyl chloride was beneficial to the esterification reaction. The degree of substitution was 1.68 at 90 °C for 32 h with an anhydroglucose unit to p-toluenesulfonyl chloride to betaine molar ratio of 1 to 2 to 3. The physicochemical properties of the betaine-modified cellulose were closely related to the degree of substitution. Major changes in the morphologies, crystallinity, thermal properties, porosity, and the average degree of polymerization resulted from the modification. The introduction of betaine made cellulose esters thermally less stable than neat cellulose but more difficult to completely degrade. The crystalline structure of the cellulose esters was destroyed, and the products exhibited a porous nature. Dye sorption studies demonstrated that the betaine-modified cellulose holds the potential of adsorbing anionic substances, which is the premise of its application.

scholarly journals Advances in Single-Cell Printing

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 80
Author(s):  
Xiaohu Zhou ◽  
Han Wu ◽  
Haotian Wen ◽  
Bo Zheng
Keyword(s):  
Single Cell ◽  
Single Cell Analysis ◽  
Three Dimensional ◽  
Cell Isolation ◽  
Special Focus ◽  
Cell Analysis ◽  
Cell Array ◽  
Cell Printing ◽  
Recent Developments ◽  
Single Cell Isolation

Single-cell analysis is becoming an indispensable tool in modern biological and medical research. Single-cell isolation is the key step for single-cell analysis. Single-cell printing shows several distinct advantages among the single-cell isolation techniques, such as precise deposition, high encapsulation efficiency, and easy recovery. Therefore, recent developments in single-cell printing have attracted extensive attention. We review herein the recently developed bioprinting strategies with single-cell resolution, with a special focus on inkjet-like single-cell printing. First, we discuss the common cell printing strategies and introduce several typical and advanced printing strategies. Then, we introduce several typical applications based on single-cell printing, from single-cell array screening and mass spectrometry-based single-cell analysis to three-dimensional tissue formation. In the last part, we discuss the pros and cons of the single-cell strategies and provide a brief outlook for single-cell printing.

Recent Developments of Micropattern Detectors

2014 ◽  
pp. 156-194
Keyword(s):  
Large Hadron Collider ◽  
Visible Light ◽  
Parallel Plate ◽  
Hadron Collider ◽  
Special Focus ◽  
Large Area ◽  
Special Place ◽  
Recent Developments ◽  
New Generation ◽  
Detector Technology

In this chapter, the exciting developments in micropattern detectors in recent years are described. This includes GEM and MICROMEGAS detectors combined with micropixel readout, some peculiar designs of GEM and GEM-like detectors sensitive to UV and visible light, large area (>1m2) GEM and MICROMEGAS prototypes developed for the upgrades of the experiments at the large hadron collider, etc. A special focus is put on a new generation of spark-proof micropattern detectors, using resistive electrodes instead of traditional metallic ones. These detectors operate as ordinary micropattern detectors. However, in the case of occasional sparks, their current is limited by the resistivity of the electrodes so that the energy of the discharge is reduced by several orders of magnitude. Various designs of such detectors have been developed and successfully tested, including resistive GEM, resistive MICROMEGAS, resistive MSGC, etc. Among this family of detectors, a special place belongs to resistive parallel-plate micropattern detectors allowing one to achieve at the same time excellent spatial (38 µm) and time (77 ps) resolutions. Finally, the potential of multilayer detector technology for further optimization of the detector operation is discussed.

scholarly journals Arteriovenous access in hemodialysis: A multidisciplinary perspective for future solutions

2020 ◽  
Vol 44 (1) ◽  
pp. 3-16
Author(s):  
Bernd Stegmayr ◽  
Christian Willems ◽  
Thomas Groth ◽  
Albino Martins ◽  
Nuno M Neves ◽  
...  
Keyword(s):  
Arteriovenous Fistula ◽  
Vascular Access ◽  
Blood Compatibility ◽  
Arteriovenous Shunt ◽  
Emergency Situations ◽  
Hemodialysis Vascular Access ◽  
Recent Developments ◽  
Lumen Catheter ◽  
Multidisciplinary Perspective ◽  
And Function

In hemodialysis, vascular access is a key issue. The preferred access is an arteriovenous fistula on the non-dominant lower arm. If the natural vessels are insufficient for such access, the insertion of a synthetic vascular graft between artery and vein is an option to construct an arteriovenous shunt for punctures. In emergency situations and especially in elderly with narrow and atherosclerotic vessels, a cuffed double-lumen catheter is placed in a larger vein for chronic use. The latter option constitutes a greater risk for infections while arteriovenous fistula and arteriovenous shunt can fail due to stenosis, thrombosis, or infections. This review will recapitulate the vast and interdisciplinary scenario that characterizes hemodialysis vascular access creation and function, since adequate access management must be based on knowledge of the state of the art and on future perspectives. We also discuss recent developments to improve arteriovenous fistula creation and patency, the blood compatibility of arteriovenous shunt, needs to avoid infections, and potential development of tissue engineering applications in hemodialysis vascular access. The ultimate goal is to spread more knowledge in a critical area of medicine that is importantly affecting medical costs of renal replacement therapies and patients’ quality of life.

Bribery: cost of doing business in Africa

2017 ◽  
Vol 24 (1) ◽  
pp. 56-64
Author(s):  
Adefolake Adeyeye
Keyword(s):  
Secondary Data ◽  
Primary Data ◽  
Special Focus ◽  
Journal Articles ◽  
Content Type ◽  
Doing Business ◽  
Recent Developments ◽  
Research Findings ◽  
Media Reports ◽  
Available Information

Purpose The purpose of this paper is to examine the implications of foreign bribery and perceptions that bribery is just a cost of doing business in Africa in light of recent reports and developments in the global attempt to curb bribery and corruption. Design/methodology/approach The research relied on primary data from anti-corruption legislation, surveys and monitoring reports and secondary data from publicly available information, journal articles and media reports to analyse recent developments in the fight against corruption with a special focus on Africa. Findings The research findings and analysis suggest that foreign bribery, which is illegal but largely carried out with impunity and perceived as a just a cost of doing business in Africa, has heavy costs on developing nations and on corporations and individuals that are prosecuted. Although much has been done to curb corruption, it seems active enforcement takes place in only a limited number of countries. There is still the need for enhanced enforcement by nations, increased societal awareness of effective measures against corruption and improved corporate compliance and responsibility. Originality/value The paper contributes practical insights into improvements and lapses in the fight against foreign bribery and corruption. Using recent and relevant analysis, the paper revisits the resilience of bribery and corruption in spite of increased anti-corruption actions and the need for multiple and varied measures. The information provided will be useful for governments, corporations and civil society in the fight against corruption, which requires constant multilateral action and examination.

A new method for rapid degree of substitution and purity determination of chloroform-soluble cellulose esters, using 31P NMR

2010 ◽  
Vol 2 (10) ◽  
pp. 1499 ◽  
Author(s):  
Alistair W. T. King ◽  
Jarno Jalomäki ◽  
Mari Granström ◽  
Dimitris S. Argyropoulos ◽  
Sami Heikkinen ◽  
...  
Keyword(s):  
31P Nmr ◽  
Degree Of Substitution ◽  
New Method ◽  
Cellulose Esters ◽  
Purity Determination

scholarly journals Recent Advances in Flavin-Dependent Halogenase Biocatalysis: Sourcing, Engineering, and Application

Catalysts ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 1030 ◽  
Author(s):  
Johannes Büchler ◽  
Athena Papadopoulou ◽  
Rebecca Buller
Keyword(s):  
Small Molecule ◽  
Halogen Atom ◽  
Reaction Engineering ◽  
Special Focus ◽  
Molecular Scaffolds ◽  
Reaction Conditions ◽  
Bioactive Substances ◽  
Application Range ◽  
Technological Value ◽  
Recent Developments

The introduction of a halogen atom into a small molecule can effectively modulate its properties, yielding bioactive substances of agrochemical and pharmaceutical interest. Consequently, the development of selective halogenation strategies is of high technological value. Besides chemical methodologies, enzymatic halogenations have received increased interest as they allow the selective installation of halogen atoms in molecular scaffolds of varying complexity under mild reaction conditions. Today, a comprehensive library of aromatic halogenases exists, and enzyme as well as reaction engineering approaches are being explored to broaden this enzyme family’s biocatalytic application range. In this review, we highlight recent developments in the sourcing, engineering, and application of flavin-dependent halogenases with a special focus on chemoenzymatic and coupled biosynthetic approaches.

π-Electron rich small molecule sensors for the recognition of nitroaromatics

2015 ◽  
Vol 51 (89) ◽  
pp. 16014-16032 ◽  
Author(s):  
Sankarasekaran Shanmugaraju ◽  
Partha Sarathi Mukherjee
Keyword(s):  
Small Molecule ◽  
Fluorescent Sensors ◽  
Review Article ◽  
Special Focus ◽  
Nitroaromatic Explosives ◽  
Recent Developments ◽  
Made In

In this review article we provide an overview of the recent developments made in small molecule-based turn-off fluorescent sensors for nitroaromatic explosives with special focus on organic and H-bonded supramolecular sensors.

scholarly journals Effect of degree of substitution on the mechanical and thermomechanical properties of lauroyl cellulose ester films

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Nicolas Joly ◽  
Patrick Martin ◽  
Luc Liénard ◽  
Delphine Rutot ◽  
Fabrice Stassin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Mechanical Analysis ◽  
Thermomechanical Properties ◽  
Degree Of Substitution ◽  
Cellulose Ester ◽  
Plastic Films ◽  
Ester Formation ◽  
Homogeneous Media

AbstractCellulose-based plastic films were prepared in homogeneous media with a range of lauroyl fatty acid attachments by ester formation, expressed as the degree of substitution (DS). The esters were cast to form films and their mechanical properties studied. This study showed a surprising relationship between DS and elastic modulus as well as DS and tensile strength, where a peak was observed at DS 2.4. The unexpected variation of static elastic modulus (E) was confirmed by dynamic mechanical analysis (DMA) and this trend was also observed for glass transition temperature (Tg). These results are discussed in relation to sample cohesion.

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