Search results for "cellulose"
showing 10 items of 318 documents
Nanoporous kaolin – cellulose nanofibril composites for printed electronics
2017
Cellulose nano- and microfibrils (CNF/CMF) grades vary significantly based on the raw materials and process treatments used. In this study four different CNF/CMF grades were combined with kaolin clay pigment particles to form nanoporous composites. The attained composite properties like porosity, surface smoothness, mechanical properties and density properties depended strongly on the raw materials used. In general, higher kaolin content (~80 wt%) led to controllable shrinkage during drying, which resulted in improved dimensional stability of composites, compared to a lower kaolin content (~50 wt%). On the other hand, the use of a plasticizer and a high amount of CNF/CMF was essential to pr…
Improvement of xylose fermentation of Saccharomyces cerevisiae
2012
The increasing need of oil and the negative impacts of fossil fuels on climate change have motivated the research towards environmental friendly alternatives to diminish the use of fossil resources. Until today, bioethanol production and use has increased worldwide. The raw materials used today compete with food industry and conquently, the ethanol production from lignocellulose has been developed intensively. However, to make the processes economically competitive, also pentoses in lignocellulose should be fermented at high rate. Saccharomyces cerevisiae, alias baker’s yeast has an excellent ethanol production capacity but it can not naturally utilize xylose. Several xylose-utilizing S. ce…
Osmolality of various viscoelastic substances: comparative study.
2000
Abstract Purpose To determine the osmolality of various viscoelastic substances. Setting Department of Ophthalmology, Johannes Gutenberg-University, Mainz, and Institute for Medical Device Testing, Memmingen, Germany. Methods The analysis was carried out according to the European Pharmacopoeia by means of a calibrated osmometer using the freezing-point depression method. Each syringe was analyzed as a duplicate analysis. Results Mean osmolalities (mOsmol/kg) of the sodium hyaluronate viscoelastic substances were Allervisc® 299; Allervisc® Plus 307; Amvisc® Plus 335; AMO Vitrax® 284; Biolon® 279; Dispasan® 311; Dispasan® Plus 314; Healon® 295; Healon GV® 312; Healon®5 322; HYA-Ophtal® 376; M…
Muscle adenylate kinase in Duchenne muscular dystrophy
1986
Abstract On the basis of electrophoretic and enzyme inhibition studies it was postulated that an aberrant adenylate kinase occurs in muscle and serum of patients with Duchenne muscular dystrophy (Schirmer, R.H. and Thuma, E. (1972) Biochim. Biophys. Acta 268, 92–97; Hamada, M. et al. (1981) Biochim. Biophys. Acta 660, 227–237; Hamada et al. (1985) J. Biol. Chem. 260, 11595–11602. On the basis of the following results we conclude that Duchenne muscular dystrophy patients do not possess an unusual adenylate kinase isoenzyme. (1) In muscle biopsies from five Duchenne patients, the electrophoretic mobility of adenylate kinase and the inhibition of the enzyme by P 1 , P 5 -di(adenosine-5′)pentap…
The role of hemostatic devices in neurosurgery. A systematic review.
2021
Hemostasis represents a fundamental step in every surgical procedure. During neurosurgical procedures, proper and robust hemostasis into confined spaces can significantly reduce the odds of perioperative complications. Over the decades, multiple methods have been applied, and several medical devices have been developed to promote and guarantee proper hemostasis. This study presents a systematic review of the most used intraoperative hemostatic methods and devices in neurosurgery. Insightful research was performed on the PubMed database according to the PRISMA guidelines. This comprehensive review of scientific literature represents a synoptic panel where the most used intraoperative hemosta…
Oxidative tissue damage after phacoemulsification: influence of ophthalmic viscosurgical devices.
2003
To quantify the oxidative tissue damage after phacoemulsification, correlate the damage to the energy applied, and investigate the influence of ophthalmic viscosurgical devices (OVDs).Department of Ophthalmology, University of Mainz, Mainz, Germany.The study comprised 130 eyes operated on by 1 surgeon using the same phacoemulsification machine. Some eyes received an OVD before phacoemulsification and some did not. Energy values were expressed as phaco time; that is, ultrasound (US) time (seconds) after conversion to 100% phaco power. Patients were grouped as follows: Group 1, phaco time less than 20 seconds and no OVD; Group 2, phaco time 20 to 40 seconds and no OVD; Group 3, phaco time mor…
Innovative barriers for peritoneal adhesion prevention: liquid or solid? A rat uterine horn model.
2005
Objective To compare the effects of solid barriers (PDLA membrane and foil, Interceed), innovative barrier solutions (Adept and Hyalobarrier Gel, phospholipid emulsion), and Ringer’s lactate solution in preventing postsurgical peritoneal adhesions in the rat. Design Prospective, randomized experimental study. Setting Rat model in an academic research environment. Animal(s) Female, nonpregnant Wistar rats. Intervention(s) Standardized surgical injuries were applied to the parietal and visceral peritoneum and the uterine horns. The barrier agents were applied and the wound was closed. A second-look laparoscopy was performed 31 days after surgery to assess adhesion formation. Main Outcome Meas…
Regeneration of cellulose by water addition to phosphoric acid/cellulose mixture
2013
In the last years, phosphoric acid has been increasingly considered as a simple and economic solvent for cellulose pretreatment before its degradation to glucose. Cellulose swells in 71–80% phosphoric acid solutions, whereas at higher H3PO4 concentrations dissolution appears to occur. In addition, it is reported that regenerated cellulose is more easily fermentable to bioethanol. The aim of the present study was to elucidate the mechanism for cellulose regeneration following treatment with phosphoric acid at room temperature. CPMAS 13C NMR spectra revealed a downfield shift of the 13C NMR signals from the regenerated cellulose as compared to the crystalline one. CPMAS 31P NMR spectroscopy s…
Selective hemicellulose hydrolysis of Scots pine sawdust
2019
The depletion of fossil resources is driving forward the search for new and alternative renewable feedstocks in the production of renewable chemicals, which could replace the petroleum-based ones. One such feedstock is pine (Pinus sylvestris) sawdust, which is generated enormous amounts in Finnish sawmills yearly. However, prior to the utilization in high-value applications, it needs to be fractionated into its constituents. In this work, the objective was to produce monomeric hemicellulose sugars from pine sawdust without degrading cellulose or lignin simultaneously. The influence of the reaction temperature and time, as well as acid type and concentration, was studied. Based on the result…
Analytical pyrolysis of wood and non-wood materials from integrated biorefinery concepts
2019
Wood and non-wood differ with respect to their anatomical, physical, and chemical properties, even among their species, resulting in different behaviors during thermal conversion. Hence, understanding the degradation of these feedstocks by pyrolysis is attractive to establish biorefinery possibilities for renewable resources. Additionally, biomass pretreatment technology plays an important role in many biorefinery processes. Therefore, an approach that integrates such pretreatment with pyrolysis offers an attractive, novel method for improving the end-product spectrum (e.g., enriched either with aliphatic or aromatic constituents). Furthermore, a rapid analytical method for biomass feedstoc…