Optimisation of the composition and production of mannitol/microcrystalline cellulose tablets

NARCIS (Netherlands)

Westerhuis, J.A; de Haan, P; Zwinkels, J; Jansen, W.T; Coenegracht, P.M J; Lerk, C.F

1996-01-01

Mixtures of mannitol and microcrystalline cellulose (MCC) were investigated on a small-production scale by granulation in a high-shear mixer and compression into tablets. For both excipients only a few cases of incompatibilities with active ingredients are known. Tablets with only MCC as the filler

Modification and characterization of microcrystalline cellulose with succinic anhydride

International Nuclear Information System (INIS)

Santos, Clecio M.R.; Santos, Douglas C.; Freitas, Gizele B.; Cardoso, Giselia

2011-01-01

Cellulose is a natural polymer, non-toxic, biodegradable and renewable source. With increasing global attention to environmental problems, the chemical modification of cellulose has been evaluated with increasing applicability in various industrial sectors. The cellulose can be chemical modified through the hydroxyl present in their molecules. This paper aims to present the main results in the modification of microcrystalline cellulose. The sample was pure and modified chemically and morphologically characterized by absorption spectroscopy in the infrared (IR) and showed the band in the 1551cm -1 characterization modification made, X-ray diffraction (XRD) where it was observed that the change led to a reduction significant crystallinity, and determination of average pore radius through the analyzer porosity and surface area resulting in values of 6.97 angstrom for pure sample and 8.62 angstrom for the modified. In addition to these tests we determined the average degree of substitution finding the value of 1.67. (author)

Antibacterial Modification of Microcrystalline Cellulose by Grafting Copolymerization

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Ying Liu

2015-11-01

Full Text Available Microcrystalline cellulose (MCC has the advantage of a high specific surface area as compared to that of conventional cellulose fibers. In this study the monomer methacrylamide (MAM was used to treat MCC by grafting copolymerization. SEM, FTIR, and solid 13C NMR were used to characterize the morphology and composition of MAM-g-MCC. After the chlorination of MAM-g-MCC with 10% sodium hypochlorite solution, the grafted MCC exhibited antibacterial activity as a result of the formation of N-Cl bonds. The thermal stability, antibacterial ability, and storage stability of chlorinated MAM-g-MCC were also studied. The results showed that the chlorinated MAM-g-MCC had excellent storage stability and could inactivate all S. aureus and E. coli O157:H7 within 10 min.

Bioconversion of different sizes of microcrystalline cellulose pretreated by microwave irradiation with/without NaOH

International Nuclear Information System (INIS)

Peng, Huadong; Chen, Hongzhang; Qu, Yongshui; Li, Hongqiang; Xu, Jian

2014-01-01

Highlights: • High concentration of alkali or temperature was necessary in cellulose degradation. • Effects of alkali pretreatment could be enhanced with the addition of microwave irradiation. • The structures diversities of microcrystalline cellulose were eliminated in the fermentation. • The significance of particle size and treat condition varied with reaction time. - Abstract: The process of microwave irradiation (MWI) pretreatment on microcrystalline cellulose (MCC) with different sizes with/without NaOH was investigated on the variation of the ratio of degradated solid residue (R DS ), particle size, crystallinity index (CrI), crystallite size (Sc) and specific surface area (SSA). High concentration of alkali or high temperature was necessary in dissolving or decomposing the cellulose. Appropriate pretreatment severity eliminated the effects of structural diversities in feedstocks, which led to convergence in the ethanol fermentation. After the reaction proceeded to 120 h, the samples could be converted to glucose completely and the highest ethanol yield of the theoretical was 58.91% for all the samples pretreated by the combined treatment of MWI and NaOH. In addition, the statistical analysis implied that when reaction time got to 24 h, particle size and pretreatment condition affected much more significant than other factors

Water-in-oil Pickering emulsions stabilized by stearoylated microcrystalline cellulose.

Science.gov (United States)

Pang, Bo; Liu, Huan; Liu, Peiwen; Peng, Xinwen; Zhang, Kai

2018-03-01

Hydrophobic particles with static water contact angles larger than 90° are more like to stabilize W/O Pickering emulsions. In particular, high internal phase Pickering emulsions (HIPEs) are of great interest for diverse applications. However, W/O HIPEs have rarely been realized using sustainable biopolymers. Herein, we used stearoylated microcrystalline cellulose (SMCC) to stabilize W/O Pickering emulsions and especially, W/O HIPEs. Moreover, these W/O HIPEs can be further used as platforms for the preparation of porous materials, such as porous foams. Stearoylated microcrystalline cellulose (SMCC) was prepared by modifying MCC with stearoyl chloride under heterogeneous conditions. Using SMCC as emulsifiers, W/O medium and high internal phase Pickering emulsions (MIPEs and HIPEs) with various organic solvents as continuous phases were prepared using one-step and two-step methods, respectively. Polystyrene (PS) foams were prepared after polymerization of oil phase using HIPEs as templates and their oil/water separation capacity were studied. SMCC could efficiently stabilize W/O Pickering emulsions and HIPEs could only be prepared via the two-step method. The internal phase volume fraction of the SMCC-stabilized HIPEs reached as high as 89%. Diverse internal phase volume fractions led to distinct inner structures of foams with closed or open cells. These macroporous polystyrene (PS) foams demonstrated great potential for the effective absorption of organic solvents from underwater. Copyright © 2017 Elsevier Inc. All rights reserved.

Investigation of the powder flow behaviour of binary mixtures of microcrystalline celluloses and paracetamol

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Ira Soppela

2010-03-01

Full Text Available The flow behaviour of binary mixtures of paracetamol and different grades of microcrystalline celluloses (Avicel® PH101, PH102 and PH200 was studied using a new testing method. The effect of physical characteristics of the powder including tribocharging and the addition of lubricant on the flow properties of the different mixtures was investigated. As expected, the flowability of the samples was affected both by the amount of paracetamol and the physical properties of microcrystalline celluloses (MCC and the mixtures. The effect of lubricant varied depending on the MCC grade: magnesium stearate was able to improve the flowability of the mixtures containing PH102 and PH200 while it did not affect the flowability of PH101. Multivariate analysis showed that the flow of the binary excipient-drug mixtures through an orifice is affected by several phenomena, such as charging, surface moisture, carrier payload and particle size.

Antibody bond to the microcrystalline cellulose in progesterone radioimmunoassay

International Nuclear Information System (INIS)

Krnavek, B.

1992-01-01

A suspension of microcrystalline cellulose with bonded globulin fraction of the polyclonal antibody against progesterone was prepared and applied to the radioimmunoanalysis of progesterone in full milk and in blood serum. The results were compared with those obtained using RETRO-test kits; the comparison gave evidence that the novel technique can fully replace the RETRO-test, the elimination of the separating medium (activated carbon, polyethylene glycol) being an asset. The obtained correlation coefficient and regression equation for a simultaneous determination of 120 samples by the two methods were r = 0.964 and y = 1.113x - 0.939, respectively

Influence of Tableting on Enzymatic Activity of Papain along with Determination of Its Percolation Threshold with Microcrystalline Cellulose

Science.gov (United States)

Sharma, Manu; Sharma, Vinay; Majumdar, Dipak K.

2014-01-01

The binary mixture tablets of papain and microcrystalline cellulose (MCC), dicalcium phosphate dihydrate (DCP), carrageenan, tragacanth, and agar were prepared by direct compression. Carrageenan, tragacanth, and agar provided maximum protection to enzyme activity compared to MCC and DCP. However, stability studies indicated highest loss of enzyme activity with carrageenan, tragacanth, and agar. Therefore, compression behaviour of different binary mixtures of papain with MCC at different compaction pressures, that is, 40–280 MPa, was studied according to Heckel equation. The compressibility studies of binary mixtures indicated brittle behavior of papain. The application of percolation theory on the relationship between critical density as a function of enzyme activity and mixture composition revealed the presence of percolation threshold for binary mixture. Papain-MCC mixture composition showed significant percolation threshold at 18.48% (w/w) papain loading. Microcrystalline cellulose provided higher protection during stability study. However, higher concentrations of microcrystalline cellulose, probably as dominant particles, do not protect the enzyme with their plastic deformation. Below the percolation threshold, that is, 18.48% (w/w) papain amount in mixture with plastic excipient, activity loss increases strongly because of higher shearing forces during compaction due to system dominance of plastic particles. This mixture range should therefore be avoided to get robust formulation of papain. PMID:27350972

Visible light activated TiO2/microcrystalline cellulose nanocatalyst to destroy organic contaminants in water.

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Hybrid TiO2/microcrystalline cellulose (MC) nanophotocatalyst was prepared in situ by a facile and simple synthesis utilizing benign precursors such as MC and TiCl4. The as-prepared nanocomposite was characterized by XRD, XPS, BET surface area analyzer, UV–vis DRS and TGA. Surfac...

Physical and structural properties of polyaniline/microcrystalline cellulose nanocomposite

Science.gov (United States)

Abdi, Mahnaz M.; Liyana, Rawaida; Tahir, Paridah Md; Heng, Lee Yook; Sulaiman, Yusran; Waheeda, Nur Farhana; Hassan, Nabihah Abu

2017-12-01

A composite of Polyaniline/Microcrystalline Cellulose (PAni/MCC) was prepared via a chemical polymerization method in the presence of ammonium persulfate (NH4)2S2O8 as oxidant and cetyltrimethylammonium bromide (CTAB) as a cationic surfactant. The results of FESEM showed that the morphology of nanocomposite depends on the monomer concentration. Wire-like and porous nanostructure was observed for PAni/MCC/CTAB composite that could be suitable for enzyme immobilization and sensor applications. The electrochemical properties of the composites were studied using Cyclic Voltammetry (CV) and it was shown that PAni/MCC/CTAB composite generated a higher current response compared to the pure PAni. The synergy effect of MCC and CTAB on the physical and electrochemical properties of composite resulted in higher electron transferring in PAni/MCC/CTAB. The presence of significant peaks of PAni and MCC in FT-IR spectrum of nanocomposite indicating polymerization of aniline on the surface of MCC. Characteristic peaks of crystalline cellulose were observed at 22.8 and 14.7 2theta in XRD pattern.

[A study of the properties of tablets from mixtures of two size degrees of alpha-lactose monohydrate and microcrystalline cellulose].

Science.gov (United States)

Muzíková, J

2006-03-01

The paper examines the strength and disintegration time of compacts from the mixtures of two types of Tablettosas. Tablettosa 70 and Tablettosa 100 with microcrystalline cellulose represented by Vivapur 102. The mixtures of dry binders were prepared in the ratios of 3:1, 1:1, and 1:3. The effect of two concentrations of the lubricant magnesium stearate on the strength and disintegration time of compacts was also examined. Tablet strength increased with higher representation of microcrystalline cellulose in the mixture, and decreased with higher stearate concentration. The compacts from the mixtures with Tablettosa 100 showed higher strength. Disintegration time was highest in the compacts with the largest perccintage of microcrystalline cellulose, and longer in the case of the mixtures with Tablettosa 100. Stearate did not exert a negative effect on disintegration time. In the mixtures of Tablettosas with Vivapur 102 in a ratio of 1:1, the effect of the model active ingredient acetylsalicylic acid on the above-mentioned properties of tablets was tested. acetylsalicylic acid produced a further decrease in the strength of compacts and shortened the disintegration time in more instances in the cased of the mixtures with Tahlettosa 100.

Physicochemical Characterization of Microcrystalline Cellulose Extracted from Kenaf Bast

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N. A. Sri Aprilia

2016-03-01

Full Text Available Microcrystalline cellulose (MCC was successfully prepared from bleached kenaf bast fiber through hydrochloric acid hydrolysis. The influence of hydrolysis time (1 to 3 h on the MCC physicochemical properties was examined. Scanning electron microscopy (SEM, X-ray diffraction (XRD, particle size analysis, Fourier transform infrared spectroscopy (FT-IR, and thermal gravimetric analysis (TGA were utilized to characterize the isolated MCC. According to FTIR analysis, the chemical composition of MCC was not changed with the reaction time. The reaction times, however, did affect the thermal stability of MCC. The thermal stability decreased linearly with increasing hydrolysis time. The optimum hydrolysis time was determined based on the morphological, structural, and thermal properties of the kenaf bast MCC.

Spherical composite particles of rice starch and microcrystalline cellulose: A new coprocessed excipient for direct compression

OpenAIRE

Limwong, Vasinee; Sutanthavibul, Narueporn; Kulvanich, Poj

2004-01-01

Composite particles of rice starch (RS) and microcrystalline cellulose were fabricated by spray-drying technique to be used as a directly compressible excipient. Two size fractions of microcry stalline cellulose, sieved (MCS) and jet milled (MCJ), having volumetric mean diameter (D50) of 13.61 and 40.51 μm, respectively, were used to form composite particles with RS in various mixing ratios. The composite particles produced were evaluated for their powder and compression properties. Although ...

Facile synthesis of TiO2/microcrystalline cellulose nanocomposites: photocatalytically active material under visible light irradiation

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Doped TiO2 nanocomposites were prepared in situ by a facile and simple synthesis utilizing benign and renewable precursors such as microcrystalline cellulose (MC) and TiCl4 through hydrolysis in alkaline medium without the addition of organic solvents. The as-prepared nanocompos...

Influence of alkaline hydrogen peroxide pre-hydrolysis on the isolation of microcrystalline cellulose from oil palm fronds.

Science.gov (United States)

Owolabi, Abdulwahab F; Haafiz, M K Mohamad; Hossain, Md Sohrab; Hussin, M Hazwan; Fazita, M R Nurul

2017-02-01

In the present study, microcrystalline cellulose (MCC) was isolated from oil palm fronds (OPF) using chemo-mechanical process. Wherein, alkaline hydrogen peroxide (AHP) was utilized to extract OPF fibre at different AHP concentrations. The OPF pulp fibre was then bleached with acidified sodium chlorite solution followed by the acid hydrolysis using hydrochloric acid. Several analytical methods were conducted to determine the influence of AHP concentration on thermal properties, morphological properties, microscopic and crystalline behaviour of isolated MCC. Results showed that the MCC extracted from OPF fibres had fibre diameters of 7.55-9.11nm. X-ray diffraction (XRD) analyses revealed that the obtained microcrystalline fibre had both celluloses I and cellulose II polymorphs structure, depending on the AHP concentrations. The Fourier transmission infrared (FTIR) analyses showed that the AHP pre-hydrolysis was successfully removed hemicelluloses and lignin from the OPF fibre. The crystallinity of the MCC was increased with the AHP concentrations. The degradation temperature of MCC was about 300°C. The finding of the present study showed that pre-treatment process potentially influenced the quality of the isolation of MCC from oil palm fronds. Copyright © 2016 Elsevier B.V. All rights reserved.

Dielectric barrier discharge plasma pretreatment on hydrolysis of microcrystalline cellulose

Science.gov (United States)

Huang, Fangmin; Long, Zhouyang; Liu, Sa; Qin, Zhenglong

2017-04-01

Dielectric barrier discharge (DBD) plasma was used as a pretreatment method for downstream hydrolysis of microcrystalline cellulose (MCC). The degree of polymerization (DP) of MCC decreased after it was pretreated by DBD plasma under a carrier gas of air/argon. The effectiveness of depolymerization was found to be influenced by the crystallinity of MCC when under the pretreatment of DBD plasma. With the addition of tert-butyl alcohol in the treated MCC water suspension solution, depolymerization effectiveness of MCC was inhibited. When MCC was pretreated by DBD plasma for 30 min, the total reducing sugar concentration (TRSC) and liquefaction yield (LY) of pretreated-MCC (PMCC) increased by 82.98% and 34.18% respectively compared with those for raw MCC.

Bacterial cellulose/boehmite composites

International Nuclear Information System (INIS)

Salvi, Denise T.B. de; Barud, Hernane S.; Messaddeq, Younes; Ribeiro, Sidney J.L.; Caiut, Jose Mauricio A.

2011-01-01

Composites based on bacterial cellulose membranes and boehmite were obtained. SEM results indicate that the bacterial cellulose (BC) membranes are totally covered by boehmite and obtained XRD patterns suggest structural changes due to this boehmite addition. Thermal stability is accessed through TG curves and is dependent on boehmite content. Transparency is high comparing to pure BC as can be seen through UV-vis absorption spectroscopy. (author)

EPR response of sucrose and microcrystalline cellulose to measure high doses of gamma radiation; Respuesta EPR de sacarosa y celulosa micro cristalina para medir altas dosis de radiacion gamma

Energy Technology Data Exchange (ETDEWEB)

Torijano, E.; Cruz, L.; Gutierrez, G.; Azorin, J.; Aguirre, F. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Cruz Z, E., E-mail: eftc@xanum.uam.mx [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

2015-10-15

Solid dosimeters of sucrose and microcrystalline cellulose (Avicel Ph-102) were prepared, following the same process, in order to compare their EPR response against that of the l-alanine dosimeters considered as reference. All lots of dosimeters were irradiated with gamma radiation in Gamma beam irradiator with 8 kGy/h of the Nuclear Sciences Institute of UNAM. Doses ranged from 1 to 10 kGy respectively. We found that both the response of sucrose as microcrystalline cellulose were linear; however, the response intensity was, on average, twenty times more for sucrose. Comparing this against the EPR response of l-alanine in the range of doses, it was found that the response to sucrose is a third part; and microcrystalline cellulose is a sixtieth, approximately. The results agree with those found in the literature for sucrose, leaving open the possibility of investigating other dosage ranges for cellulose. (Author)

A study of a novel coprocessed dry binder composed of α-lactose monohydrate, microcrystalline cellulose and corn starch.

Science.gov (United States)

Mužíková, Jitka; Srbová, Alena; Svačinová, Petra

2017-12-01

This paper deals with a study of the novel coprocessed dry binder Combilac®, which contains 70% of α-lactose monohydrate, 20% of microcrystalline cellulose and 10% of native corn starch. These tests include flow properties, compressibility, lubricant sensitivity, tensile strength and disintegration time of tablets. Compressibility is evaluated by means of the energy profile of compression process, test of stress relaxation and tablet strength. The above-mentioned parameters are also evaluated in the physical mixture of α-lactose monohydrate, microcrystalline cellulose and native corn starch and compared with Combilac. Combilac shows much better flowability than the physical mixture of the used dry binders. Its compressibility is better, tablets possess a higher tensile strength. Neither Combilac, nor the physical mixture can be compressed without lubricants due to high friction and sticking to the matrix. Combilac has a higher lubricant sensitivity than the physical mixture of the dry binders. Disintegration time of Combilac tablets is comparable with the disintegration time of tablets made from the physical mixture.

Effect of environmental conditions on the mechanical properties and fungal degradation of polycaprolactone/microcrystalline cellulose/wood flour composites

Science.gov (United States)

Ronald Sabo; Liwei Jin; Nicole Stark; Rebecca E. Ibach

2013-01-01

Polycaprolactone (PCL) filled with microcrystalline cellulose (MCC), wood flour (WF), or both were characterized before and after exposure to various environmental conditions for 60 days. PCL/WF composites had the greatest tensile strength and modulus compared to neat PCL or PCL composites containing MCC. Electron microscopy indicated better adhesion between WF...

Enzymatic hydrolysis of biomimetic bacterial cellulose-hemicellulose composites.

Science.gov (United States)

Penttilä, Paavo A; Imai, Tomoya; Hemming, Jarl; Willför, Stefan; Sugiyama, Junji

2018-06-15

The production of biofuels and other chemicals from lignocellulosic biomass is limited by the inefficiency of enzymatic hydrolysis. Here a biomimetic composite material consisting of bacterial cellulose and wood-based hemicelluloses was used to study the effects of hemicelluloses on the enzymatic hydrolysis with a commercial cellulase mixture. Bacterial cellulose synthesized in the presence of hemicelluloses, especially xylan, was found to be more susceptible to enzymatic hydrolysis than hemicellulose-free bacterial cellulose. The reason for the easier hydrolysis could be related to the nanoscale structure of the substrate, particularly the packing of cellulose microfibrils into ribbons or bundles. In addition, small-angle X-ray scattering was used to show that the average nanoscale morphology of bacterial cellulose remained unchanged during the enzymatic hydrolysis. The reported easier enzymatic hydrolysis of bacterial cellulose produced in the presence of wood-based xylan offers new insights to overcome biomass recalcitrance through genetic engineering. Copyright © 2018 Elsevier Ltd. All rights reserved.

Characterization of TEMPO-oxidized bacterial cellulose

International Nuclear Information System (INIS)

Nascimento, Eligenes S.; Pereira, Andre L.S.; Lima, Helder L.; Barroso, Maria K. de A.; Barros, Matheus de O.; Morais, Joao P.S.; Borges, Maria de F.; Rosa, Morsyleide de F.

2015-01-01

The aim of this study was to characterize the TEMPO-oxidized bacterial cellulose, as a preliminary research for further application in nanocomposites. Bacterial cellulose (BC) was selectively oxidized at C-6 carbon by TEMPO radical. Oxidized bacterial cellulose (BCOX) was characterized by TGA, FTIR, XRD, and zeta potential. BCOX suspension was stable at pH 7.0, presented a crystallinity index of 83%, in spite of 92% of BC, because of decrease in the free hydroxyl number. FTIR spectra showed characteristic BC bands and, in addition, band of carboxylic group, proving the oxidation. BCOX DTG showed, in addition to characteristic BC thermal events, a maximum degradation peak at 233 °C, related to sodium anhydro-glucuronate groups formed during the cellulose oxidation. Thus, BC can be TEMPO-oxidized without great loss in its structure and properties. (author)

Applications of bacterial cellulose and its composites in biomedicine.

Science.gov (United States)

Rajwade, J M; Paknikar, K M; Kumbhar, J V

2015-03-01

Bacterial cellulose produced by few but specific microbial genera is an extremely pure natural exopolysaccharide. Besides providing adhesive properties and a competitive advantage to the cellulose over-producer, bacterial cellulose confers UV protection, ensures maintenance of an aerobic environment, retains moisture, protects against heavy metal stress, etc. This unique nanostructured matrix is being widely explored for various medical and nonmedical applications. It can be produced in various shapes and forms because of which it finds varied uses in biomedicine. The attributes of bacterial cellulose such as biocompatibility, haemocompatibility, mechanical strength, microporosity and biodegradability with its unique surface chemistry make it ideally suited for a plethora of biomedical applications. This review highlights these qualities of bacterial cellulose in detail with emphasis on reports that prove its utility in biomedicine. It also gives an in-depth account of various biomedical applications ranging from implants and scaffolds for tissue engineering, carriers for drug delivery, wound-dressing materials, etc. that are reported until date. Besides, perspectives on limitations of commercialisation of bacterial cellulose have been presented. This review is also an update on the variety of low-cost substrates used for production of bacterial cellulose and its nonmedical applications and includes patents and commercial products based on bacterial cellulose.

Metallization of bacterial cellulose for electrical and electronic device manufacture

Science.gov (United States)

Evans, Barbara R [Oak Ridge, TN; O'Neill, Hugh M [Knoxville, TN; Jansen, Valerie Malyvanh [Memphis, TN; Woodward, Jonathan [Knoxville, TN

2010-09-28

A method for the deposition of metals in bacterial cellulose and for the employment of the metallized bacterial cellulose in the construction of fuel cells and other electronic devices is disclosed. The method for impregnating bacterial cellulose with a metal comprises placing a bacterial cellulose matrix in a solution of a metal salt such that the metal salt is reduced to metallic form and the metal precipitates in or on the matrix. The method for the construction of a fuel cell comprises placing a hydrated bacterial cellulose support structure in a solution of a metal salt such that the metal precipitates in or on the support structure, inserting contact wires into two pieces of the metal impregnated support structure, placing the two pieces of metal impregnated support structure on opposite sides of a layer of hydrated bacterial cellulose, and dehydrating the three layer structure to create a fuel cell.

Bacterial Cellulose Production from Industrial Waste and by-Product Streams.

Science.gov (United States)

Tsouko, Erminda; Kourmentza, Constantina; Ladakis, Dimitrios; Kopsahelis, Nikolaos; Mandala, Ioanna; Papanikolaou, Seraphim; Paloukis, Fotis; Alves, Vitor; Koutinas, Apostolis

2015-07-01

The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen) 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L) and commercial sucrose (4.9 g/L) were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L) were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102-138 g · water/g · dry bacterial cellulose, viscosities of 4.7-9.3 dL/g, degree of polymerization of 1889.1-2672.8, stress at break of 72.3-139.5 MPa and Young's modulus of 0.97-1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.

Preparation of cellulose II and IIII films by allomorphic conversion of bacterial cellulose I pellicles

International Nuclear Information System (INIS)

Faria-Tischer, Paula C.S.; Tischer, Cesar A.; Heux, Laurent; Le Denmat, Simon; Picart, Catherine; Sierakowski, Maria-R.

2015-01-01

The structural changes resulting from the conversion of native cellulose I (Cel I) into allomorphs II (Cel II) and III I (Cel III I ) have usually been studied using powder samples from plant or algal cellulose. In this work, the conversion of Cel I into Cel II and Cel III I was performed on bacterial cellulose films without any mechanical disruption. The surface texture of the films was observed by atomic force microscopy (AFM) and the morphology of the constituting cellulose ribbons, by transmission electron microscopy (TEM). The structural changes were characterized using solid-state NMR spectroscopy as well as X-ray and electron diffraction. The allomorphic change into Cel II and Cel III I resulted in films with different crystallinity, roughness and hydrophobic/hydrophilicity surface and the films remained intact during all process of allomorphic conversion. - Highlights: • Description of a method to modify the allomorphic structure of bacterial cellulose films • Preparation of films with specific morphologies and hydrophobic/hydrophilic surface characters • First report on cellulose III films from bacterial cellulose under swelling conditions • Detailed characterization of cellulose II and III films with complementary techniques • Development of films with specific properties as potential support for cells, enzymes, and drugs

Bacterial Cellulose Production from Industrial Waste and by-Product Streams

Directory of Open Access Journals (Sweden)

Erminda Tsouko

2015-07-01

Full Text Available The utilization of fermentation media derived from waste and by-product streams from biodiesel and confectionery industries could lead to highly efficient production of bacterial cellulose. Batch fermentations with the bacterial strain Komagataeibacter sucrofermentans DSM (Deutsche Sammlung von Mikroorganismen 15973 were initially carried out in synthetic media using commercial sugars and crude glycerol. The highest bacterial cellulose concentration was achieved when crude glycerol (3.2 g/L and commercial sucrose (4.9 g/L were used. The combination of crude glycerol and sunflower meal hydrolysates as the sole fermentation media resulted in bacterial cellulose production of 13.3 g/L. Similar results (13 g/L were obtained when flour-rich hydrolysates produced from confectionery industry waste streams were used. The properties of bacterial celluloses developed when different fermentation media were used showed water holding capacities of 102–138 g·water/g·dry bacterial cellulose, viscosities of 4.7–9.3 dL/g, degree of polymerization of 1889.1–2672.8, stress at break of 72.3–139.5 MPa and Young’s modulus of 0.97–1.64 GPa. This study demonstrated that by-product streams from the biodiesel industry and waste streams from confectionery industries could be used as the sole sources of nutrients for the production of bacterial cellulose with similar properties as those produced with commercial sources of nutrients.

Molecular weights and molecular weight distributions of irradiated cellulose fibers by gel permeation chromatography

International Nuclear Information System (INIS)

Kusama, Y.; Kageyama, E.; Shimada, M.; Nakamura, Y.

1976-01-01

Radiation degradation of cellulose fibers was investigated by gel permeation chromatography (GPC). Scoured cotton of Mexican variety (cellulose I), Polynosic rayon (cellulose II), and their microcrystalline celluloses obtained by hydrolysis of the original fibers were irradiated by Co-60 γ-rays under vacuum or humid conditions. The irradiated samples were then nitrated under nondegradative conditions. The molecular weights and molecular weight distributions were measured by GPC using tetrahydrofuran as solvent. The relationship between molecular weight and elution count was obtained with cellulose trinitrate standards fractionated by preparative GPC. The degree of polymerization of the fibers decreased with increasing irradiation dose, but their microcrystalline celluloses were only slightly degraded by irradiation, especially in microcrystalline cellulose from cellulose I. Degradation of the fibers irradiated under humid conditions was less than that irradiated under vacuum. It was found that the G-values for main-chain scission for the irradiated cellulose I, cellulose II, microcrystalline cellulose I, and microcrystalline cellulose II were 2.8, 2.9, less than 1, and 2.9, respectively, but the G-value for main-chain scission for the irradiated cellulose II was increased to 11.2 at irradiation doses above 3 Mrad. Consequently, it is inferred that cellulose molecules in the amorphous regions are degraded more readily, and the well-aligned molecules in crystalline regions are not as easily degraded by irradiation

The effect of pulping concentration treatment on the properties of microcrystalline cellulose powder obtained from waste paper.

Science.gov (United States)

Okwonna, Okumneme O

2013-10-15

Microcrystalline cellulose (MCC) powder was isolated from three grades of waste paper: book, Groundwood/Newsprint and paperboard, through the processes of pulping and hydrolysis. Pulping treatment on these grades of waste paper was done using varying concentrations of caustic soda. Effects of the concentration of the pulping medium on the thermal and kinetic properties were investigated. Also determined were the effects of this on the physico-chemical properties. The chemical structure was characterized using an infrared spectroscopy (FTIR). Results showed these properties to be affected by the concentration of the pulping medium. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparison of Bacterial Cellulose Production among Different Strains and Fermented Media

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Maryam Jalili Tabaii

2015-12-01

Full Text Available The effect of different carbon sources on bacterial cellulose production by Gluconacetobacter xylinus (PTCC 1734 and two newly isolated strains (from vinegar under static culture conditions was studied. The production of bacterial cellulose was examined in modified Hestrin-Shramm medium by replacing D-glucose with other carbon sources. The results showed that the yield and characteristics of bacterial cellulose were influenced by the type of carbon source. Glycerol gave the highest yield in all of the studied strains (6%, 9.7% and 3.8% for S, A2 strain and Gluconacetobacter xylinus (PTCC 1734, respectively. The maximum dry bacterial cellulose weight in the glycerol containing medium is due to A2 strain (1.9 g l-1 in comparison to Gluconacetobacter xylinus as reference strain (0.76 g l-1. Although all of the studied strains were in Gluconacetobacter family, each used different sugars for maximum production after glycerol (mannitol and fructose for two newly isolated strains and glucose for Gluconacetobacter xylinus. The maximum moisture content was observed when sucrose and food-grade sucrose were used as carbon source. Contrary to expectations, while the maximum thickness of bacterial cellulose membrane was attained when glycerol was used, bacterial cellulose from glycerol had less moisture content than the others. The oxidized cellulose showed antibacterial activities, which makes it as a good candidate for food-preservatives.

Processing of micro-nano bacterial cellulose with hydrolysis method as a reinforcing bioplastic

Science.gov (United States)

Maryam, Maryam; Dedy, Rahmad; Yunizurwan, Yunizurwan

2017-01-01

Nanotechnology is the ability to create and manipulate atoms and molecules on the smallest of scales. Their size allows them to exhibit novel and significantly improved physical, chemical, biological properties, phenomena, and processes because of their size. The purpose of this research is obtaining micro-nano bacterial cellulose as reinforcing bioplastics. Bacterial cellulose (BC) was made from coconut water for two weeks. BC was dried and grinded. Bacterial cellulose was given purification process with NaOH 5% for 6 hours. Making the micro-nano bacterial cellulose with hydrolysis method. Hydrolysis process with hydrochloric acid (HCl) at the conditions 3,5M, 55°C, 6 hours. Drying process used spray dryer. The hydrolysis process was obtained bacterial cellulose with ±7 μm. The addition 2% micro-nano bacterial cellulose as reinforcing in bioplastics composite can improve the physical characteristics.

Processing of micro-nano bacterial cellulose with hydrolysis method as a reinforcing bioplastic

International Nuclear Information System (INIS)

Maryam, Maryam; Yunizurwan, Yunizurwan; Dedy, Rahmad

2017-01-01

Nanotechnology is the ability to create and manipulate atoms and molecules on the smallest of scales. Their size allows them to exhibit novel and significantly improved physical, chemical, biological properties, phenomena, and processes because of their size. The purpose of this research is obtaining micro-nano bacterial cellulose as reinforcing bioplastics. Bacterial cellulose (BC) was made from coconut water for two weeks. BC was dried and grinded. Bacterial cellulose was given purification process with NaOH 5% for 6 hours. Making the micro-nano bacterial cellulose with hydrolysis method. Hydrolysis process with hydrochloric acid (HCl) at the conditions 3,5M, 55°C, 6 hours. Drying process used spray dryer. The hydrolysis process was obtained bacterial cellulose with ±7 μm. The addition 2% micro-nano bacterial cellulose as reinforcing in bioplastics composite can improve the physical characteristics. (paper)

Characterization of Polylactic Acid/ Microcrystalline Cellulose/ Montmorillonite Hybrid Composites

International Nuclear Information System (INIS)

Reza Arjmandi; Azman Hassan; Haafiz, M.K.M.; Zainoha Zakaria; Inuwa, I.M.

2014-01-01

The objective of this study is to investigate the effect of montmorillonite (MMT)/ microcrystalline cellulose (MCC) hybrid fillers on mechanical properties and morphological characteristics of polylactic acid (PLA) composites. PLA/ MMT nano composites and PLA/ MMT/ MCC hybrid composites were prepared by solution casting method. Morphology and tensile properties of PLA composites were investigated using Field emission scanning electron microscopy and Instron tensile testing machine. The maximum tensile strength of PLA/ MMT nano composites was obtained with 5 phr contents of MMT, which corresponding to 30.75 MPa. Based on optimized formulation of PLA/ MMT nano composites (5 phr MMT contents), various amounts of MCC (0 to 7 phr) were added into optimum formulation of PLA/ MMT in order to produce PLA/ MMT/ MCC hybrid composites. Fourier transform infrared spectroscopy revealed some level of interaction between PLA and both MMT and MCC in the hybrid composites. However, the percent elongation at break of the hybrid composites was generally higher than PLA/ MMT nano composites. Additionally, Young's modulus of the PLA/ MMT/ MCC hybrid composites increased gradually with increasing of MCC contents and was higher than PLA/ MMT at all compositions. The present results are the first among a series of experiments that have been designed in order to probe the effect of MMT and MCC in the PLA. (author)

A novel process for synthesis of spherical nanocellulose by controlled hydrolysis of microcrystalline cellulose using anaerobic microbial consortium.

Science.gov (United States)

Satyamurthy, P; Vigneshwaran, N

2013-01-10

Degradation of cellulose by anaerobic microbial consortium is brought about either by an exocellular process or by secretion of extracellular enzymes. In this work, a novel route for synthesis of nanocellulose is described where in an anaerobic microbial consortium enriched for cellulase producers is used for hydrolysis. Microcrystalline cellulose derived from cotton fibers was subjected to controlled hydrolysis by the anaerobic microbial consortium and the resultant nanocellulose was purified by differential centrifugation technique. The nanocellulose had a bimodal size distribution (43±13 and 119±9 nm) as revealed by atomic force microscopy. A maximum nanocellulose yield of 12.3% was achieved in a span of 7 days. While the conventional process of nanocellulose preparation using 63.5% (w/w) sulfuric acid resulted in the formation of whisker shaped nanocellulose with surface modified by sulfation, controlled hydrolysis by anaerobic microbial consortium yielded spherical nanocellulose also referred to as nano crystalline cellulose (NCC) without any surface modification as evidenced from Fourier transform infrared spectroscopy. Also, it scores over chemo-mechanical production of nanofibrillated cellulose by consuming less energy due to enzyme (cellulase) assisted catalysis. This implies the scope for use of microbial prepared nanocellulose in drug delivery and bio-medical applications requiring bio-compatibility. Copyright © 2012 Elsevier Inc. All rights reserved.

Provision of micro-nano bacterial cellulose as bio plastic filler by sonication method

Science.gov (United States)

Maryam; Rahmad, D.; Yunizurwan; Kasim, A.; Novelina; Emriadi

2017-07-01

Research and development of bioplastic has increased recently as a solution for substitution of conventional plastic which have many negative impacts to environment. However, physical properties and mechanical properties of its still lower than conventional plastic. An alternative solution for that problem is by using fillers that can increase the strength. Bacterial cellulose is considered as potential source for filler, but still need to be explored more. The privileges of bacterial cellulose are easy to get and does not have lignin, pectin, and hemicelluloses which are impurities in other celluloses. This research focused on gaining bacterial cellulose in micro-nano particle form and its impact on increasing the strength of bio plastic. Ultrasonication has been used as method to form micro-nano particle from bacterial cellulose. The result showed this method may form the particle size of bacterial cellulose approximately ± 3μm. Next step, after getting ± 3μm particle of bacterial cellulose, is making bio plastic with casting method by adding 1% of bacterial cellulose, from the total material in making bio plastic. Physical characteristic of the bio plastic which are tensile strength 11.85 MPa, modulus young 3.13 MPa, elongation 4.11% and density 0.42 g/cm3. The numbers of physical properties showwthat, by adding 1% of bacterial cellulose, the strength of bio plastic was significantly increase, even value of tensile strength has complied the international standard for bio plastic.

Evaluation of tablet disintegrant properties of microcrystalline ...

African Journals Online (AJOL)

This study was aimed at exploring the application of microcrystalline cellulose from cassava fermentation waste as a disintegrant in the formulation of paracetamol tablets for immediate release. Alkali delignification of the dried cassava fermentation fibres, followed by bleaching and acid depolymerisation was employed in ...

Biodegradation evaluation of bacterial cellulose, vegetable cellulose and poly (3-hydroxybutyrate in soil

Directory of Open Access Journals (Sweden)

Suellen Brasil Schröpfer

2015-04-01

Full Text Available In recent years, the inappropriate disposal of polymeric materials has increased due to industrial development and increase of population consumption. This problem may be minimized by using biodegradable polymers, such as bacterial cellulose and poly(hydroxybutyrate, from renewable resources. This work was aimed at monitoring and evaluating degradation of bacterial cellulose, vegetable cellulose and poly(3-hydroxybutyrate using Thermogravimetric Analysis and Scanning Electron Microscopy. Controlled mass polymer samples were buried in pots containing soil. Samples were removed in 30 day intervals up to 180 days. The results show that the mass of the polymer increased in the first month when in contact with the soil but then it was degraded as evidenced by mass loss and changes on the sample surface.

Effects of electron beam radiation dose on the compatibilization behaviour in recycled polypropylene/microcrystalline cellulose composites

Science.gov (United States)

Samat, N.; Motsidi, S. N. R.; Lazim, N. H. M.

2018-01-01

The purpose of this research was to evaluate the influence of dose level of electron beam on the compatibilization behavior of recycled polypropylene (rPP) in rPP/microcrystalline cellulose (MCC) composites. Initially, the rPP was irradiated with various dose of electron beam (5 kGy up to 250 kGy) which then mixed with unirradiated rPP (u-rPP) at a ratio of 30:70 respectively. The composites were prepared by incorporating a series wt% of MCC fibers into rPP (u-rPP : i-rPP) using extruder and finally moulded with an injection moulding machine. The compatibility behavior of irradiated rPP (i-rPP) were analysed with mechanical tensile and thermal methods. The results of mechanical analysis showed great improvement in tensile modulus but an increase in radiation dosage gradually decreased this property. Nevertheless, the tensile strength exhibited a minor effect. The thermal stability of composites is lowered with increase in the absorbed dose, more significantly at higher content of MCC. Fracture surface observations reveal adhesion between the cellulose and rPP matrix.

Surface physical chemistry properties in coated bacterial cellulose membranes with calcium phosphate.

Science.gov (United States)

de Olyveira, Gabriel Molina; Basmaji, Pierre; Costa, Ligia Maria Manzine; Dos Santos, Márcio Luiz; Dos Santos Riccardi, Carla; Guastaldi, Fernando Pozzi Semeghini; Scarel-Caminaga, Raquel Mantuaneli; de Oliveira Capote, Ticiana Sidorenko; Pizoni, Elisabeth; Guastaldi, Antônio Carlos

2017-06-01

Bacterial cellulose has become established as a new biomaterial, and it can be used for medical applications. In addition, it has called attention due to the increasing interest in tissue engineering materials for wound care. In this work, the bacterial cellulose fermentation process was modified by the addition of chondroitin sulfate to the culture medium before the inoculation of the bacteria. The biomimetic process with heterogeneous calcium phosphate precipitation of biological interest was studied for the guided regeneration purposes on bacterial cellulose. FTIR results showed the incorporation of the chondroitin sulfate in the bacterial cellulose, SEM images confirmed the deposition of the calcium phosphate on the bacterial cellulose surface, XPS analysis showed a selective chemical group influences which change calcium phosphate deposition, besides, the calcium phosphate phase with different Ca/P ratios on bacterial cellulose surface influences wettability. XTT results concluded that these materials did not affect significantly in the cell viability, being non-cytotoxic. Thus, it was produced one biomaterial with the surface charge changes for calcium phosphate deposition, besides different wettability which builds new membranes for Guided Tissue Regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

The effect of iron catalyzed graphitization on the textural properties of carbonized cellulose : Magnetically separable graphitic carbon bodies for catalysis and remediation

NARCIS (Netherlands)

Hoekstra, Jacco; Beale, Andrew M.; Soulimani, Fouad; Versluijs-Helder, Marjan; Van De Kleut, Dirk; Koelewijn, Jacobus M.; Geus, John W.; Jenneskens, Leonardus W.

2016-01-01

Whereas pyrolysis of pristine microcrystalline cellulose spheres yields nonporous amorphous carbon bodies, pyrolysis of microcrystalline cellulose spheres loaded with iron salts leads to the formation of magnetically separable mesoporous graphitic carbon bodies. The microcrystalline cellulose

A study of the compressibility and properties of tablets from co-processed dry binder composed of microcrystalline cellulose and glyceryl monostearate.

OpenAIRE

Muchová, Sandra

2013-01-01

The paper studies the co-processed dry binder LubriTose™ MCC from the viewpoint of energy evaluation of the compression process, strength and disintegration time of tablets. The results were compared with the identical evaluation of physical mixtures of microcrystalline cellulose with several types of lubricants. LubriTose™ MCC showed the lowest value of energy for friction, the highest value of energy accumulated by the tablet, and the highest plasticity of all tableting materials under stud...

Extraction of microcrystalline cellulose from rice straw and its effect on polyvinyl alcohol biocomposites film

Science.gov (United States)

Chin, Kwok-Mern; Ting, Sam Sung; Lin, Ong Hui; Owi, Wei Tieng

2017-07-01

The poor management and underutilization of agricultural wastes had proliferated interest of researchers around the world to find alternatives to utilize them as potential value-added products. One of the green alternatives is by extracting cellulose from these waste materials and incorporating them in polymer as reinforcement fillers. The surging amount of plastic waste also posed major issues to the environment due to its recalcitrance to degrade. Microcrystalline cellulose (MCC-RS) was extracted from rice straw through cyclic alkaline and bleaching treatment to remove hemicellulose and lignin respectively. Polyvinyl alcohol (PVOH) was chosen as the matrix and different ratios of PVOH / MCC-RS films were prepared (2.5, 5.0, 7.5 and 10.0wt% of MCC) through solution casting method and its tensile, thermal and morphological properties were studied. X-ray powder diffraction (XRD) results showed increased crystallinity of MCC-RS after chemical treatment (from 44.5% to 60.8%) due to the successful removal of lignin and hemicellulose, which was then confirmed with Fourier transform infrared spectroscopy (FTIR) results. For the biocomposites, both tensile strength and Young's modulus of the films increased with increasing MCC-RS content up until 7.5wt%, supported with scanning electron microscopy (SEM) results which depicted improvement in the interfacial adhesion between MCC-RS and PVOH. From the overall results, the improvement in properties of biocomposite from cellulose-based microfiller had shown promising future in application of the water soluble plastic packaging industry.

Conductivity percolation in loosely compacted microcrystalline cellulose: An in situ study by dielectric spectroscopy during densification.

Science.gov (United States)

Nilsson, Martin; Frenning, Göran; Gråsjö, Johan; Alderborn, Göran; Strømme, Maria

2006-10-19

The present study aims at contributing to a complete understanding of the water-induced ionic charge transport in cellulose. The behavior of this transport in loosely compacted microcrystalline cellulose (MCC) powder was investigated as a function of density utilizing a new type of measurement setup, allowing for dielectric spectroscopy measurement in situ during compaction. The ionic conductivity in MCC was found to increase with increasing density until a leveling-out was observed for densities above approximately 0.7 g/cm3. Further, it was shown that the ionic conductivity vs density followed a percolation type behavior signifying the percolation of conductive paths in a 3D conducting network. The density percolation threshold was found to be between approximately 0.2 and 0.4 g/cm3, depending strongly on the cellulose moisture content. The observed percolation behavior was attributed to the forming of interparticulate bonds in the MCC and the percolation threshold dependence on moisture was linked to the moisture dependence of particle rearrangement and plastic deformation in MCC during compaction. The obtained results add to the understanding of the density-dependent water-induced ionic transport in cellulose showing that, at given moisture content, the two major parameters determining the magnitude of the conductivity are the connectedness of the interparticluate bonds and the connectedness of pores with a diameter in the 5-20 nm size range. At densities between approximately 0.7 and 1.2 g/cm3 both the bond and the pore networks have percolated, facilitating charge transport through the MCC compact.

Isolation and characterization of microcrystalline cellulose from roselle fibers.

Science.gov (United States)

Kian, Lau Kia; Jawaid, Mohammad; Ariffin, Hidayah; Alothman, Othman Y

2017-10-01

In this study, microcrystalline cellulose (MCC) was extracted from roselle fiber through acid hydrolysis treatment and its properties were compared with those of commercially available MCC. The physicochemical and morphological characteristics, elemental composition, size distribution, crystallinity and thermal properties of the obtained MCC were analyzed in this work. Fourier transform infrared spectroscopy (FTIR) analysis provided clear evidence that the characteristic peak of lignin was absent in the spectrum of the MCC prepared from roselle fiber. Rough surface and slight aggregation of MCC were observed by scanning electron microscopy (SEM). Energy dispersive X-ray (EDX) analysis showed that pure MCC with small quantities of residues and impurities was obtained, with a similar elemental composition to that of commercial MCC. A mean diameter of approximately 44.28μm was measured for MCC by using a particle size analyzer (PSA). X-ray diffraction (XRD) showed the crystallinity increased from 63% in roselle pulp to 78% in roselle MCC, the latter having a slightly higher crystallinity than that of commercial MCC (74%). TGA and DSC results indicated that the roselle MCC had better thermal stability than the roselle pulp, whereas it had poorer thermal stability in comparison with commercial MCC. Thus, the isolated MCC from roselle fibers will be going to use as reinforcing element in green composites and may be a precursor for future roselle derived nanocellulose, and thus a promising subject in nanocomposite research. Copyright © 2017 Elsevier B.V. All rights reserved.

Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain

Science.gov (United States)

Florea, Michael; Hagemann, Henrik; Santosa, Gabriella; Micklem, Chris N.; Spencer-Milnes, Xenia; de Arroyo Garcia, Laura; Paschou, Despoina; Lazenbatt, Christopher; Kong, Deze; Chughtai, Haroon; Jensen, Kirsten; Freemont, Paul S.; Kitney, Richard; Reeve, Benjamin; Ellis, Tom

2016-01-01

Bacterial cellulose is a strong and ultrapure form of cellulose produced naturally by several species of the Acetobacteraceae. Its high strength, purity, and biocompatibility make it of great interest to materials science; however, precise control of its biosynthesis has remained a challenge for biotechnology. Here we isolate a strain of Komagataeibacter rhaeticus (K. rhaeticus iGEM) that can produce cellulose at high yields, grow in low-nitrogen conditions, and is highly resistant to toxic chemicals. We achieved external control over its bacterial cellulose production through development of a modular genetic toolkit that enables rational reprogramming of the cell. To further its use as an organism for biotechnology, we sequenced its genome and demonstrate genetic circuits that enable functionalization and patterning of heterologous gene expression within the cellulose matrix. This work lays the foundations for using genetic engineering to produce cellulose-based materials, with numerous applications in basic science, materials engineering, and biotechnology. PMID:27247386

Bacterial cellulose biosynthesis: diversity of operons, subunits, products and functions

Science.gov (United States)

Römling, Ute; Galperin, Michael Y.

2015-01-01

Summary Recent studies of bacterial cellulose biosynthesis, including structural characterization of a functional cellulose synthase complex, provided the first mechanistic insight into this fascinating process. In most studied bacteria, just two subunits, BcsA and BcsB, are necessary and sufficient for the formation of the polysaccharide chain in vitro. Other subunits – which differ among various taxa – affect the enzymatic activity and product yield in vivo by modulating expression of biosynthesis apparatus, export of the nascent β-D-glucan polymer to the cell surface, and the organization of cellulose fibers into a higher-order structure. These auxiliary subunits play key roles in determining the quantity and structure of the resulting biofilm, which is particularly important for interactions of bacteria with higher organisms that lead to rhizosphere colonization and modulate virulence of cellulose-producing bacterial pathogens inside and outside of host cells. Here we review the organization of four principal types of cellulose synthase operons found in various bacterial genomes, identify additional bcs genes that encode likely components of the cellulose biosynthesis and secretion machinery, and propose a unified nomenclature for these genes and subunits. We also discuss the role of cellulose as a key component of biofilms formed by a variety of free-living and pathogenic bacteria and, for the latter, in the choice between acute infection and persistence in the host. PMID:26077867

Functionalization of Microcrystalline Cellulose with N,N-dimethyldodecylamine for the Removal of Congo Red Dye from an Aqueous Solution

Directory of Open Access Journals (Sweden)

Dongying Hu

2014-08-01

Full Text Available Microcrystalline cellulose (MCC was functionalized with quaternary amine groups for use as an adsorbent to remove Congo Red dye (CR from aqueous solution. The ultrasonic pretreatment of MCC was investigated during its functionalization. Characterization was conducted using infrared spectroscopy (FT-IR, X-ray photoelectron spectroscopy (XPS, X-ray diffraction (XRD, and scanning electron microscopy (SEM. The batch adsorption of the functionalized MCC was studied to evaluate the effects of dye concentration, pH of solution, temperature, and NaCl concentration on the adsorption CR. The adsorbent (FM-1 obtained using ultrasonic pretreatment of MCC under 10.8 kJ•g–1 exhibited an adsorption capacity of 304 mg•g–1 at initial pH under a dose of 0.1 g•L–1 and initial concentration of 80 mg•L–1. After functionalization, the FT-IR and XPS results indicated that the quaternary amine group was successfully grafted onto the cellulose, the surface was transformed to be coarse and porous, and the crystalline structure of the original cellulose was disrupted. FM-1 has been shown to be a promising and efficient adsorbent for the removal of CR from an aqueous solution.

Characterization of the bacterial cellulose dissolved on dimethylacetamide/lithium chloride

Energy Technology Data Exchange (ETDEWEB)

Lima, Glaucia de Marco [Universidade do Vale do Itajai (PMCF/UNIVALI), Itajai, SC (Brazil). Programa de Mestrado em Ciencias Farmaceuticas; Sierakowski, Maria Rita; Faria-Tischer, Paula C.S.; Tischer, Cesar A., E-mail: cesar.tischer@pq.cnpq.b [Universidade Federal do Parana (BIOPOL/UFPR), Curitiba, PR (Brazil). Lab. de Biopolimeros

2009-07-01

The main barrier to the use of cellulose is his insolubility on water or organic solvents, but derivates can be obtained with the use of ionic solvents. Bacterial cellulose, is mainly produced by the bacterium Acetobacter xylinum, and is identical to the plant, but free of lignin and hemi cellulose, and with several unique physical-chemical properties. Cellulose produced in a 4 % glucose medium with static condition was dissoluted on heated DMAc/LiCl (120 '0 C, 150 '0 C or 170 '0 C). The product of dissolved cellulose was observed with 13 C-NMR and the effect on crystalline state was seen with x-ray crystallography. The crystalline structure was lost in the dissolution, becoming an amorphous structure, as well as Avicel. The process of dissolution of the bacterial cellulose is basics for the analysis of these water insoluble polymer, facilitating the analysis of these composites, by 13 C-NMR spectroscopy, size exclusion chromatography and light scattering techniques. (author)

Characterization of the bacterial cellulose dissolved on dimethylacetamide/lithium chloride

International Nuclear Information System (INIS)

Lima, Glaucia de Marco; Sierakowski, Maria Rita; Faria-Tischer, Paula C.S.; Tischer, Cesar A.

2009-01-01

The main barrier to the use of cellulose is his insolubility on water or organic solvents, but derivates can be obtained with the use of ionic solvents. Bacterial cellulose, is mainly produced by the bacterium Acetobacter xylinum, and is identical to the plant, but free of lignin and hemi cellulose, and with several unique physical-chemical properties. Cellulose produced in a 4 % glucose medium with static condition was dissoluted on heated DMAc/LiCl (120 '0 C, 150 '0 C or 170 '0 C). The product of dissolved cellulose was observed with 13 C-NMR and the effect on crystalline state was seen with x-ray crystallography. The crystalline structure was lost in the dissolution, becoming an amorphous structure, as well as Avicel. The process of dissolution of the bacterial cellulose is basics for the analysis of these water insoluble polymer, facilitating the analysis of these composites, by 13 C-NMR spectroscopy, size exclusion chromatography and light scattering techniques. (author)

Alexa Fluor-labeled Fluorescent Cellulose Nanocrystals for Bioimaging Solid Cellulose in Spatially Structured Microenvironments

Energy Technology Data Exchange (ETDEWEB)

Grate, Jay W.; Mo, Kai-For; Shin, Yongsoon; Vasdekis, Andreas; Warner, Marvin G.; Kelly, Ryan T.; Orr, Galya; Hu, Dehong; Dehoff, Karl J.; Brockman, Fred J.; Wilkins, Michael J.

2015-03-18

Cellulose nanocrystal materials have been labeled with modern Alexa Fluor dyes in a process that first links the dye to a cyanuric chloride molecule. Subsequent reaction with cellulose nanocrystals provides dyed solid microcrystalline cellulose material that can be used for bioimaging and suitable for deposition in films and spatially structured microenvironments. It is demonstrated with single molecular fluorescence microscopy that these films are subject to hydrolysis by cellulose enzymes.

Eggshell and Bacterial Cellulose Composite Membrane as Absorbent Material in Active Packaging

Directory of Open Access Journals (Sweden)

S. Ummartyotin

2016-01-01

Full Text Available Bacterial cellulose and eggshell composite was successfully developed. Eggshell was mixed with bacterial cellulose suspension and it was casted as a composite film. CaCO3 derived from eggshell was compared with its commercial availability. It can be noted that good dispersion of eggshell particle was prepared. Eggshell particle was irregular in shape with a variation in size. It existed in bacterial cellulose network. Characterization on composite was focused on thermal and mechanical properties. It showed that flexibility and thermal stability of composite were enhanced. No significant effect of mechanical properties was therefore observed. The thermal stability of composite was stable up to 300°C. The adsorption experiment on water and vegetable oil capacity was performed. The enhancement on adsorption was due to the existence of eggshell in bacterial cellulose composite. It exhibited the potential to be a good candidate for absorbent material in active packaging.

Enhanced Cellulose Degradation Using Cellulase-Nanosphere Complexes

Science.gov (United States)

Blanchette, Craig; Lacayo, Catherine I.; Fischer, Nicholas O.; Hwang, Mona; Thelen, Michael P.

2012-01-01

Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS) and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC); however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production. PMID:22870287

Enhanced cellulose degradation using cellulase-nanosphere complexes.

Directory of Open Access Journals (Sweden)

Craig Blanchette

Full Text Available Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC; however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production.

Enhanced cellulose degradation using cellulase-nanosphere complexes.

Science.gov (United States)

Blanchette, Craig; Lacayo, Catherine I; Fischer, Nicholas O; Hwang, Mona; Thelen, Michael P

2012-01-01

Enzyme catalyzed conversion of plant biomass to sugars is an inherently inefficient process, and one of the major factors limiting economical biofuel production. This is due to the physical barrier presented by polymers in plant cell walls, including semi-crystalline cellulose, to soluble enzyme accessibility. In contrast to the enzymes currently used in industry, bacterial cellulosomes organize cellulases and other proteins in a scaffold structure, and are highly efficient in degrading cellulose. To mimic this clustered assembly of enzymes, we conjugated cellulase obtained from Trichoderma viride to polystyrene nanospheres (cellulase:NS) and tested the hydrolytic activity of this complex on cellulose substrates from purified and natural sources. Cellulase:NS and free cellulase were equally active on soluble carboxymethyl cellulose (CMC); however, the complexed enzyme displayed a higher affinity in its action on microcrystalline cellulose. Similarly, we found that the cellulase:NS complex was more efficient in degrading natural cellulose structures in the thickened walls of cultured wood cells. These results suggest that nanoparticle-bound enzymes can improve catalytic efficiency on physically intractable substrates. We discuss the potential for further enhancement of cellulose degradation by physically clustering combinations of different glycosyl hydrolase enzymes, and applications for using cellulase:NS complexes in biofuel production.

Methacrylate hydrogels reinforced with bacterial cellulose

Czech Academy of Sciences Publication Activity Database

Hobzová, Radka; Dušková-Smrčková, Miroslava; Michálek, Jiří; Karpushkin, Evgeny; Gatenholm, P.

2012-01-01

Roč. 61, č. 7 (2012), s. 1193-1201 ISSN 0959-8103 R&D Projects: GA AV ČR KJB400500902 Institutional research plan: CEZ:AV0Z40500505 Keywords : bacterial cellulose * methacrylate hydrogel * composite Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.125, year: 2012

Antimicrobial Bacterial Cellulose-Silver Nanoparticles Composite Membranes

Directory of Open Access Journals (Sweden)

Hernane S. Barud

2011-01-01

Full Text Available Antimicrobial bacterial cellulose-silver nanoparticles composite membranes have been obtained by “in situ” preparation of Ag nanoparticles from hydrolytic decomposition of silver nitrate solution using triethanolamine as reducing and complexing agent. The formation of silver nanoparticles was evidenced by the X-ray diffraction, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and absorption in the UV-Visible (350 nm to 600 nm. Thermal and mechanical properties together with swelling behavior for water were considered. TEA concentration was observed to be important in order to obtain only Ag particles and not a mixture of silver oxides. It was also observed to control particle size and amount of silver contents in bacterial cellulose. The composite membranes exhibited strong antimicrobial activity against Gram-negative and Gram-positive bacteria.

Evaluation of several microcrystalline celluloses obtained from agricultural by-products

Directory of Open Access Journals (Sweden)

John Rojas

2011-01-01

Full Text Available Microcrystalline cellulose (MCCI has been widely used as an excipient for direct compression due to its good flowability, compressibility, and compactibility. In this study, MCCI was obtained from agricultural by-products, such as corn cob, sugar cane bagasse, rice husk, and cotton by pursuing acid hydrolysis, neutralization, clarification, and drying steps. Further, infrared spectroscopy (IR, X-ray diffraction (XRD, optical microscopy, degree of polymerization (DP, and powder and tableting properties were evaluated and compared to those of Avicel PH101, Avicel PH102, and Avicel PH200. Except for the commercial products, all materials showed a DP from 55 to 97. Particles of commercial products and corn cob had an irregular shape, whereas bagasse particles were elongated and thick. Rice and cotton particles exhibited a flake-like and fiber-like shape, respectively. MCCI as obtained from rice husk and cotton was the most densified material, while that produced from corn cob and bagasse was bulky, porous, and more compressible. All products had a moisture content of less than 10% and yields from 7.4% to 60.4%. MCCI as obtained from bagasse was the most porous and compressible material among all materials. This product also showed the best tableting properties along with Avicel products. Likewise, all MCCI products obtained from the above-mentioned sources showed a more rapid disintegration time than that of Avicel products. These materials can be used as a potential source of MCCI in the production of solid dosage forms.

Characterisation of bacterial cellulose partly acetylated by dimethylacetamide/lithium chloride

International Nuclear Information System (INIS)

Lima, G. de Marco; Sierakowski, M.-R.; Faria-Tischer, P.C.S.; Tischer, C.A.

2011-01-01

Cellulose is a water-insoluble polysaccharide used at an industrial scale for the manufacture of paper and films or in the dust form, natural, hydrolysed or derivatised. The cellulose produced by G. hansenii (former A. xylinum) has a structure identical to that of plants, but is free of lignin and hemicellulose, with several unique physical-chemical properties. The main barrier to the use of cellulose is its insolubility in water and most organic solvents, but soluble derivatives can be obtained with the use of ionic solvents. Bacterial cellulose, produced in a static, 4% glucose medium, was dissolved in hot DMAc/LiCl (120, 150 or 170 deg. C). The solution was analysed by 13 C NMR, and the effect of the dissolution on the crystalline state was shown by X-ray crystallography. The crystalline structure was lost upon dissolution, becoming amorphous; this was also observed for Avicel plant cellulose. The soluble cellulose was partly acetylated in acetic anhydride with acetic anhydride-cellulose ratios of 1:50, 1:6 and 1:12 (w/v). The resulting cellulose acetates were examined by infrared spectroscopy, and the best result was 43% (w/v). The degree of acetylation was determined via 1 H NMR spectroscopy by comparing the area of the glucose ring at 2.60-5.20 ppm and that of the methyl proton of the acetate group at 1.80-2.20 ppm. The 13 C NMR spectra showed acetylation at C6 >> C2 > C3 at 60-80 ppm, with C1 signals at ∼ 100-104 ppm. The derivatisation of bacterial cellulose in DMAc/LiCl/acetic anhydride (1:4:50, v/v/v) gave rise to 87% substitution. The process of dissolution of the bacterial cellulose is essential for the analysis of the insoluble polymer in water, facilitating analysis and characterisation of these composites by 13 C NMR spectroscopy, size exclusion chromatography and light scattering techniques.

Bio-coloration of bacterial cellulose assisted by immobilized laccase.

Science.gov (United States)

Song, Ji Eun; Su, Jing; Noro, Jennifer; Cavaco-Paulo, Artur; Silva, Carla; Kim, Hye Rim

2018-02-13

In this work a process for the bio-coloration of bacterial cellulose (BC) membranes was developed. Laccase from Myceliophthora thermophila was immobilized onto BC membranes and retained up to 88% of residual activity after immobilization. Four compounds belonging to the flavonoids family were chosen to test the in situ polymerase activity of immobilized laccase. All the flavonoids were successfully polymerized by laccase giving rise to yellow, orange and dark brown oligomers which conferred color to the BC support. The optimal bio-coloration conditions were studied for two of the tested flavonoids, catechol and catechin, by varying the concentration and time of incubation. High color depth and resistance to washing were obtained for both compounds. The highly porous bacterial cellulose material demonstrated great performance as a bio-coloration support, in contrast to other materials cited in literature, like cotton or wool. The process developed is presented as an environmentally friendly alternative for bacterial cellulose bio-coloration and will contribute deeply for the development of new fashionable products within this material.

Isolation of bacterial cellulose nanocrystalline from pineapple peel waste: Optimization of acid concentration in the hydrolysis method

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Anwar, Budiman; Rosyid, Nurul Huda; Effendi, Devi Bentia; Nandiyanto, Asep Bayu Dani; Mudzakir, Ahmad; Hidayat, Topik

2016-02-01

Isolation of needle-shaped bacterial cellulose nanocrystalline with a diameter of 16-64 nm, a fiber length of 258-806 nm, and a degree of crystallinity of 64% from pineapple peel waste using an acid hydrolysis process was investigated. Experimental showed that selective concentration of acid played important roles in isolating the bacterial cellulose nanocrystalline from the cellulose source. To achieve the successful isolation of bacterial cellulose nanocrystalline, various acid concentrations were tested. To confirm the effect of acid concentration on the successful isolation process, the reaction conditions were fixed at a temperature of 50°C, a hydrolysis time of 30 minutes, and a bacterial cellulose-to-acid ratio of 1:50. Pineapple peel waste was used as a model for a cellulose source because to the best of our knowledge, there is no report on the use of this raw material for producing bacterial cellulose nanocrystalline. In fact, this material can be used as an alternative for ecofriendly and cost-free cellulose sources. Therefore, understanding in how to isolate bacterial cellulose nanocrystalline from pineapple peel waste has the potential for large-scale production of inexpensive cellulose nanocrystalline.

Characterization of TEMPO-oxidized bacterial cellulose; Caracterizacao de celulose bacteriana tempo-oxidada

Energy Technology Data Exchange (ETDEWEB)

Nascimento, Eligenes S.; Pereira, Andre L.S.; Lima, Helder L.; Barroso, Maria K. de A., E-mail: eligenessampaio@hotmail.com [Universidade Federal Ceara (UFC), Fortaleza, CE (Brazil); Barros, Matheus de O. [Instituto Federal do Ceara (IFCE), Fortaleza, CE (Brazil); Morais, Joao P.S. [Embrapa Algodao, Campina Grande, PB (Brazil); Borges, Maria de F.; Rosa, Morsyleide de F. [Embrapa Agroindustria Tropical, Fortaleza, CE (Brazil)

2015-07-01

The aim of this study was to characterize the TEMPO-oxidized bacterial cellulose, as a preliminary research for further application in nanocomposites. Bacterial cellulose (BC) was selectively oxidized at C-6 carbon by TEMPO radical. Oxidized bacterial cellulose (BCOX) was characterized by TGA, FTIR, XRD, and zeta potential. BCOX suspension was stable at pH 7.0, presented a crystallinity index of 83%, in spite of 92% of BC, because of decrease in the free hydroxyl number. FTIR spectra showed characteristic BC bands and, in addition, band of carboxylic group, proving the oxidation. BCOX DTG showed, in addition to characteristic BC thermal events, a maximum degradation peak at 233 °C, related to sodium anhydro-glucuronate groups formed during the cellulose oxidation. Thus, BC can be TEMPO-oxidized without great loss in its structure and properties. (author)

Cellulose- and xylan-degrading thermophilic anaerobic bacteria from biocompost.

Science.gov (United States)

Sizova, M V; Izquierdo, J A; Panikov, N S; Lynd, L R

2011-04-01

Nine thermophilic cellulolytic clostridial isolates and four other noncellulolytic bacterial isolates were isolated from self-heated biocompost via preliminary enrichment culture on microcrystalline cellulose. All cellulolytic isolates grew vigorously on cellulose, with the formation of either ethanol and acetate or acetate and formate as principal fermentation products as well as lactate and glycerol as minor products. In addition, two out of nine cellulolytic strains were able to utilize xylan and pretreated wood with roughly the same efficiency as for cellulose. The major products of xylan fermentation were acetate and formate, with minor contributions of lactate and ethanol. Phylogenetic analyses of 16S rRNA and glycosyl hydrolase family 48 (GH48) gene sequences revealed that two xylan-utilizing isolates were related to a Clostridium clariflavum strain and represent a distinct novel branch within the GH48 family. Both isolates possessed high cellulase and xylanase activity induced independently by either cellulose or xylan. Enzymatic activity decayed after growth cessation, with more-rapid disappearance of cellulase activity than of xylanase activity. A mixture of xylan and cellulose was utilized simultaneously, with a significant synergistic effect observed as a reduction of lag phase in cellulose degradation.

Preparation, Characterization, and Cationic Functionalization of Cellulose-Based Aerogels for Wastewater Clarification

Directory of Open Access Journals (Sweden)

Yang Hu

2016-01-01

Full Text Available Aerogels are a series of materials with porous structure and light weight which can be applied to many industrial divisions as insulators, sensors, absorbents, and cushions. In this study, cellulose-based aerogels (aerocelluloses were prepared from cellulosic material (microcrystalline cellulose in sodium hydroxide/water solvent system followed by supercritical drying operation. The average specific surface area of aerocelluloses was 124 m2/g. The nitrogen gas (N2 adsorption/desorption isotherms revealed type H1 hysteresis loops for aerocelluloses, suggesting that aerocelluloses may possess a porous structure with cylindrically shaped pores open on both ends. FTIR and XRD analyses showed that the crystallinity of aerocelluloses was significantly decreased as compared to microcrystalline cellulose and that aerocelluloses exhibited a crystalline structure of cellulose II as compared to microcrystalline cellulose (cellulose I. To perform cationic functionalization, a cationic agent, (3-chloro-2-hydroxypropyl trimethylammonium chloride, was used to introduce positively charged sites on aerocelluloses. The cationized aerocelluloses exhibited a strong ability to remove anionic dyes from wastewater. Highly porous and low cost aerocelluloses prepared in this study would be also promising as a fast absorbent for environmental pollutants.

Self-supported silver nanoparticles containing bacterial cellulose membranes

International Nuclear Information System (INIS)

Barud, Hernane S.; Barrios, Celina; Regiani, Thais; Marques, Rodrigo F.C.; Verelst, Marc; Dexpert-Ghys, Jeannette; Messaddeq, Younes; Ribeiro, Sidney J.L.

2008-01-01

Hydrated bacterial cellulose (BC) membranes obtained from cultures of Acetobacter xylinum were used in the preparation of silver nanoparticles containing cellulose membranes. In situ preparation of Ag nanoparticles was achieved from the hydrolytic decomposition of silver triethanolamine (TEA) complexes. Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) patterns both lead to the observation of spherical metallic silver particles with mean diameter of 8 nm well adsorbed onto the BC fibriles

Characterization of cellulose nanowhiskers

International Nuclear Information System (INIS)

Nascimento, Nayra R.; Pinheiro, Ivanei F.; Morales, Ana R.; Ravagnani, Sergio P.; Mei, Lucia

2015-01-01

Cellulose is the most abundant polymer earth. The cellulose nanowhiskers can be extracted from the cellulose. These have attracted attention for its use in nanostructured materials for various applications, such as nanocomposites, because they have peculiar characteristics, among them, high aspect ratio, biodegradability and excellent mechanical properties. This work aims to characterize cellulose nanowhiskers from microcrystalline cellulose. Therefore, these materials were characterized by X-ray diffraction (XRD) to assess the degree of crystallinity, infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) to the morphology of nanowhiskers and thermal stability was evaluated by Thermogravimetric Analysis (TGA). (author)

Extraction of cellulose microcrystalline from galam wood for biopolymer

Science.gov (United States)

Ismail, Ika; Sa'adiyah, Devy; Rahajeng, Putri; Suprayitno, Abdi; Andiana, Rocky

2018-04-01

Consumption of plastic raw materials tends to increase, but until now the meet of the consumption of plastic raw are still low, even some are still imported. Nowadays, Indonesia's plastic needs are supported by petrochemicals where raw materials are still dependent abroad and petropolymer raw materials are derived from petroleum which will soon be depleted due to rising petroleum needs. Therefore, various studies have been conducted to develop natural fiber-based polymers that are biodegradable and abundant in nature. It is because the natural polymer production process is very efficient and very environmentally friendly. There have been many studies of biopolymers especially natural fiber-based polymers from plants, due to plants containing cellulose, hemicellulose and lignin. However, cellulose is the only one who has crystalline structures. Cellulose has a high crystality compared to amorphous lignin and hemicellulose. In this study, extracted cellulose as biopolymer and amplifier on composite. The cellulose is extracted from galam wood from East Kalimantan. Cellulose extraction will be obtained in nano / micro form through chemical and mechanical treatment processes. The chemical treatment of cellulose extraction is alkalinization process using NaOH solution, bleaching using NaClO2 and acid hydrolysis using sulfuric acid. After chemical treatment, ultrasonic mechanical treatment is made to make cellulose fibers into micro or nano size. Besides, cellulose results will be characterized. Characterization was performed to analyze molecules of cellulose compounds extracted from plants using Fourier Transformation Infra Red (FTIR) testing. XRD testing to analyze cellulose crystallinity. Scanning Electron Microscope (SEM) test to analyze morphology and fiber size.

Cost-effective production of bacterial cellulose using acidic food industry by-products.

Science.gov (United States)

Revin, Victor; Liyaskina, Elena; Nazarkina, Maria; Bogatyreva, Alena; Shchankin, Mikhail

2018-03-13

To reduce the cost of obtaining bacterial cellulose, acidic by-products of the alcohol and dairy industries were used without any pretreatment or addition of other nitrogen sources. Studies have shown that the greatest accumulation of bacterial cellulose (6.19g/L) occurs on wheat thin stillage for 3 days of cultivation under dynamic conditions, which is almost 3 times higher than on standard Hestrin and Schramm medium (2.14g/L). The use of whey as a nutrient medium makes it possible to obtain 5.45g/L bacterial cellulose under similar conditions of cultivation. It is established that the pH of the medium during the growth of Gluconacetobacter sucrofermentans B-11267 depends on the feedstock used and its initial value. By culturing the bacterium on thin stillage and whey, there is a decrease in the acidity of the waste. It is shown that the infrared spectra of bacterial cellulose obtained in a variety of environments have a similar character, but we found differences in the micromorphology and crystallinity of the resulting biopolymer. Copyright © 2018 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

The effect of bacterial cellulose on the shape memory behavior of polyvinyl alcohol nanocomposite hydrogel

Science.gov (United States)

Pirahmadi, Pegah; Kokabi, Mehrdad

2018-01-01

Most research on shape memory polymers has been confined to neat polymers in their dry state, while, some hydrogel networks are known for their shape memory properties. Hydrogels have low glass transition temperatures which are below 100°C depend on the content of water. But they are usually weak and brittle, and not suitable for structural applications due to their low mechanical strengths because of these materials have large amount of water (>50%), so they could not remember original shape perfectly. Bacterial cellulose nanofibers with perfect properties such as high water holding capacity, high crystallinity, high tensile strength and good biocompatibility can dismiss all the drawbacks. In the present study, polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel prepared by repetitive freezing-thawing method. The bacterial cellulose was used as reinforcement to improve the mechanical properties and stimuli response. Differential scanning calorimetry was employed to obtain the glass transition temperature. Nanocomposite morphology was characterized by field-emission scanning electron microscopy and mechanical properties were investigated by standard tensile test. Finally, the effect of bacterial cellulose nanofiber on shape memory behavior of polyvinyl alcohol/bacterial cellulose nanocomposite hydrogel was investigated. It is found that switching temperature of this system is the glass transition temperature of the nano domains formed within the system. The results also show increase of shape recovery, and shape recovery speed due to presence of bacterial cellulose.

Recognition of lysozyme using surface imprinted bacterial cellulose nanofibers.

Science.gov (United States)

Saylan, Yeşeren; Tamahkar, Emel; Denizli, Adil

2017-11-01

Here, we developed the lysozyme imprinted bacterial cellulose (Lyz-MIP/BC) nanofibers via the surface imprinting strategy that was designed to recognize lysozyme. This study includes the molecular imprinting method onto the surface of bacterial cellulose nanofibers in the presence of lysozyme by metal ion coordination, as well as further characterizations methods FTIR, SEM and contact angle measurements. The maximum lysozyme adsorption capacity of Lyz-MIP/BC nanofibers was found to be 71 mg/g. The Lyz-MIP/BC nanofibers showed high selectivity for lysozyme towards bovine serum albumin and cytochrome c. Overall, the Lyz-MIP/BC nanofibers hold great potential for lysozyme recognition due to the high binding capacity, significant selectivity and excellent reusability.

Synthesis and properties of regenerated cellulose-based hydrogels with high strength and transparency for potential use as an ocular bandage

International Nuclear Information System (INIS)

Patchan, M.; Graham, J.L.; Xia, Z.; Maranchi, J.P.; McCally, R.; Schein, O.; Elisseeff, J.H.; Trexler, M.M.

2013-01-01

Cellulose is a biologically derived material with excellent wound-healing properties. The high strength of cellulose fibers and the ability to synthesize gels with high optical transparency make these materials suitable for ocular applications. In this study, cellulose materials derived from wood pulp, cotton, and bacterial sources were dissolved in lithium chloride/N,N-dimethylacetamide to form regenerated cellulose hydrogels. Material properties of the resulting hydrogels, including water content, optical transparency, and tensile and tear strengths, were evaluated. Synthesis parameters, including activation time, dissolution time, relative humidity, and cellulose concentration, were found to impact the material properties of the resulting hydrogels. Overnight activation time improves the optical transparency of the hydrogels from 77% to 97% at 550 nm, whereas controlling cellulose concentration improves their tear strength by as much as 200%. On the basis of the measured transmittance and strength values of the regenerated hydrogels prepared via the optimized synthesis parameters, Avicel PH 101, Sigma-Aldrich microcrystalline cellulose 435236, and bacterial cellulose types were prioritized for future biocompatibility testing and potential clinical investigation. - Highlights: • Hydrogels were prepared (via LiCl/DMAc) from 7 different types of cellulose. • Synthesis parameters (activation, gelation, and concentration) were optimized. • Impact of synthesis parameters on transparency and strength was explored

Synthesis and properties of regenerated cellulose-based hydrogels with high strength and transparency for potential use as an ocular bandage

Energy Technology Data Exchange (ETDEWEB)

Patchan, M. [Research and Exploratory Development Department, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Graham, J.L. [Department of Biomedical Engineering, Johns Hopkins University, School of Medicine, 720 Rutland Avenue/Ross 720, Baltimore, MD 21205 (United States); Xia, Z.; Maranchi, J.P. [Research and Exploratory Development Department, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); McCally, R. [Research and Exploratory Development Department, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Wilmer Eye Institute, Johns Hopkins Medical Institutions, 600 N. Wolfe Street, Baltimore, MD 21287 (United States); Schein, O. [Wilmer Eye Institute, Johns Hopkins Medical Institutions, 600 N. Wolfe Street, Baltimore, MD 21287 (United States); Elisseeff, J.H. [Department of Biomedical Engineering, Johns Hopkins University, School of Medicine, 720 Rutland Avenue/Ross 720, Baltimore, MD 21205 (United States); Trexler, M.M., E-mail: morgana.trexler@jhuapl.edu [Research and Exploratory Development Department, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States)

2013-07-01

Cellulose is a biologically derived material with excellent wound-healing properties. The high strength of cellulose fibers and the ability to synthesize gels with high optical transparency make these materials suitable for ocular applications. In this study, cellulose materials derived from wood pulp, cotton, and bacterial sources were dissolved in lithium chloride/N,N-dimethylacetamide to form regenerated cellulose hydrogels. Material properties of the resulting hydrogels, including water content, optical transparency, and tensile and tear strengths, were evaluated. Synthesis parameters, including activation time, dissolution time, relative humidity, and cellulose concentration, were found to impact the material properties of the resulting hydrogels. Overnight activation time improves the optical transparency of the hydrogels from 77% to 97% at 550 nm, whereas controlling cellulose concentration improves their tear strength by as much as 200%. On the basis of the measured transmittance and strength values of the regenerated hydrogels prepared via the optimized synthesis parameters, Avicel PH 101, Sigma-Aldrich microcrystalline cellulose 435236, and bacterial cellulose types were prioritized for future biocompatibility testing and potential clinical investigation. - Highlights: • Hydrogels were prepared (via LiCl/DMAc) from 7 different types of cellulose. • Synthesis parameters (activation, gelation, and concentration) were optimized. • Impact of synthesis parameters on transparency and strength was explored.

Bacterial Cellulose Ionogels as Chemosensory Supports.

Science.gov (United States)

Smith, Chip J; Wagle, Durgesh V; O'Neill, Hugh M; Evans, Barbara R; Baker, Sheila N; Baker, Gary A

2017-11-01

To fully leverage the advantages of ionic liquids for many applications, it is necessary to immobilize or encapsulate the fluids within an inert, robust, quasi-solid-state format that does not disrupt their many desirable, inherent features. The formation of ionogels represents a promising approach; however, many earlier approaches suffer from solvent/matrix incompatibility, optical opacity, embrittlement, matrix-limited thermal stability, and/or inadequate ionic liquid loading. We offer a solution to these limitations by demonstrating a straightforward and effective strategy toward flexible and durable ionogels comprising bacterial cellulose supports hosting in excess of 99% ionic liquid by total weight. Termed bacterial cellulose ionogels (BCIGs), these gels are prepared using a facile solvent-exchange process equally amenable to water-miscible and water-immiscible ionic liquids. A suite of characterization tools were used to study the preliminary (thermo)physical and structural properties of BCIGs, including no-deuterium nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and X-ray diffraction. Our analyses reveal that the weblike structure and high crystallinity of the host bacterial cellulose microfibrils are retained within the BCIG. Notably, not only can BCIGs be tailored in terms of shape, thickness, and choice of ionic liquid, they can also be designed to host virtually any desired active, functional species, including fluorescent probes, nanoparticles (e.g., quantum dots, carbon nanotubes), and gas-capture reagents. In this paper, we also present results for fluorescent designer BCIG chemosensor films responsive to ammonia or hydrogen sulfide vapors on the basis of incorporating selective fluorogenic probes within the ionogels. Additionally, a thermometric BCIG hosting the excimer-forming fluorophore 1,3-bis(1-pyrenyl)propane was devised which exhibited a ratiometric (two

Improvement production of bacterial cellulose by semi-continuous process in molasses medium.

Science.gov (United States)

Cakar, Fatih; Ozer, Işılay; Aytekin, A Özhan; Sahin, Fikrettin

2014-06-15

Bacterial cellulose (BC) has unique properties such as structural, functional, physical and chemical. The mass production of BC for industrial application has recently become attractive to produce more economical and high productive cellulose. In this study, to improve the productivity of bacterial cellulose (BC), BC production by Gluconacetobacter xylinus FC01 was investigated in molasses medium with static semi-continuous operation mode. Cell dry weight, polysaccharide, sugar and cellulose concentrations were monitored and cellulose was characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The highest cellulose yield (1.637 g/L) was obtained in SCP50-7d, which molasses of 1/2 ratio for 7 days by static semi-continuous operation mode. The results show that BC can be highly produced by G. xylinus in molasses with static semi-continuous process than batch process. We claimed that low-cost medium with semi-continuous operation mode in static culture is a good candidate for industrial scale BC productions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bacterial Cellulose-Hydroxyapatite Nanocomposites for Bone Regeneration

Directory of Open Access Journals (Sweden)

S. Saska

2011-01-01

Full Text Available The aim of this study was to develop and to evaluate the biological properties of bacterial cellulose-hydroxyapatite (BC-HA nanocomposite membranes for bone regeneration. Nanocomposites were prepared from bacterial cellulose membranes sequentially incubated in solutions of CaCl2 followed by Na2HPO4. BC-HA membranes were evaluated in noncritical bone defects in rat tibiae at 1, 4, and 16 weeks. Thermogravimetric analyses showed that the amount of the mineral phase was 40%–50% of the total weight. Spectroscopy, electronic microscopy/energy dispersive X-ray analyses, and X-ray diffraction showed formation of HA crystals on BC nanofibres. Low crystallinity HA crystals presented Ca/P a molar ratio of 1.5 (calcium-deficient HA, similar to physiological bone. Fourier transformed infrared spectroscopy analysis showed bands assigned to phosphate and carbonate ions. In vivo tests showed no inflammatory reaction after 1 week. After 4 weeks, defects were observed to be completely filled in by new bone tissue. The BC-HA membranes were effective for bone regeneration.

Plasticized Biodegradable Poly(lactic acid) Based Composites Containing Cellulose in Micro- and Nanosize

OpenAIRE

Halász, Katalin; Csóka, Levente

2013-01-01

The aim of this work was to study the characteristics of thermal processed poly(lactic acid) composites. Poly(ethylene glycol) (PEG400), microcrystalline cellulose (MCC), and ultrasound-treated microcrystalline cellulose (USMCC) were used in 1, 3, and 5 weight percents to modify the attributes of PLA matrix. The composite films were produced by twin screw extrusion followed by film extrusion. The manufactured PLA-based films were characterized by tensile testing, differential scanning calorim...

Characterization of low crystallinity cellulose as a direct compression excipient: Effects of physicochemical properties of cellulose excipients on their tabletting characteristics

Science.gov (United States)

Kothari, Sanjeev Hukmichand

A scale-up method for the preparation of a new excipient, low crystallinity powder cellulose (LCPC), was established. Physicochemical characterization of a series of LCPC materials was performed, and compared to the physicochemical properties of commercially existing cellulose excipients, microcrystalline cellulose (AvicelsRTM) and powdered celluloses (Solka Flocs RTM). Low crystallinity cellulose powders had high amorphous contents (>50%) and a low degree of polymerization (2 kg), typically showed low yield pressures (200 MPa), and intermediate compactability (250--600 MPa2) values. Mechanical characterization of the three types of cellulose materials, and the statistical models obtained for the results, indicated that a high porosity (>810%), a high average of amorphous content (>40%) and moisture content (>4%), and a low degree of polymerization (disintegration times (5 to 90 seconds) for LCPC tablets at low as well as high solid fractions suggest the high affinity of these materials to water, due to their high amorphous contents that expose a larger number of hydroxyl groups to water, compared to the more crystalline materials, such as microcrystalline celluloses, the tablets of which showed extremely long disintegration times (24 to 6000 seconds). The physicochemical and mechanical characterization of low crystallinity cellulose suggests it to be a promising direct compression excipient for immediate release tablet formulations.

Mussel-inspired fabrication of konjac glucomannan/microcrystalline cellulose intelligent hydrogel with pH-responsive sustained release behavior.

Science.gov (United States)

Wang, Lin; Du, Yu; Yuan, Yi; Mu, Ruo-Jun; Gong, Jingni; Ni, Yongsheng; Pang, Jie; Wu, Chunhua

2018-07-01

Intelligent hydrogels are attractive biomaterials for various applications, however, fabricating a hydrogel with both adequate self-healing ability and mechanical properties remains a challenge. Herein, a series of novel intelligent konjac glucomannan (KGM)/microcrystalline cellulose (MCC) hydrogels were prepared vis the mussel-inspired chemistry. MCC was firstly functionalized by the oxidative polymerization of dopamine, and the intelligent hydrogels were obtained by mixing aqueous solutions of KGM and functionalized MCC (PDMCC). By introducing PDMCC, a more compact interconnected porous structure formed for the resulting hydrogels. The self-healing ability and mechanical properties of intelligent hydrogels were dependence on the PDMCC content. Compared with KGM hydrogels, KGM/PDMCC hydrogels exhibited a more distinct pH sensitivity and a lower initial burst release, which was attributed to the compact structure and strong intermolecular hydrogen bond interaction between PDMCC and KGM. These results suggest that the KGM/PDMCC intelligent hydrogels may be promising carriers for controlled drug delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

In-vitro Degradation Behaviour of Irradiated Bacterial Cellulose Membrane

International Nuclear Information System (INIS)

Darwis, D.; Khusniya, T.; Hardiningsih, L.; Nurlidar, F.; Winarno, H.

2012-01-01

Bacterial cellulose membrane synthesized by Acetobacter xylinum in coconut water medium has potential application for Guided bone Regeneration. However, this membrane may not meet some application requirements due to its low biodegradation properties. In this paper, incorporation of gamma irradiation into the membrane is a developed strategy to increase its biodegradability properties. The in-vitro degradation study in synthetic body fluid (SBF) of the irradiated membrane has been analyzed during periods of 6 months by means of weight loss, mechanical properties and scanning electron microscopy observation compared to that the un-irradiated one. The result showed that weight loss of irradiated membrane with 25 kGy and 50 kGy and immersed in SBF solution for 6 months reached 18% and 25% respectively. While un-irradiated membrane did not give significant weight loss. Tensile strength of membranes decreases with increasing of irradiation dose and further decreases in tensile strength is observed when irradiated membrane was followed by immersion in SBF solution. Microscope electron image of cellulose membranes shows that un-irradiated bacterial cellulose membrane consists of dense ultrafine fibril network structures, while irradiation result in cleavage of fibrils network of cellulose. The fibrils network become loosely after irradiated membrane immersed in SBF solution due to released of small molecular weight carbohydrates formed during by irradiation from the structure (author)

Fabrication and investigation of a biocompatible microfilament with high mechanical performance based on regenerated bacterial cellulose and bacterial cellulose.

Science.gov (United States)

Wu, Huan-Ling; Bremner, David H; Wang, Hai-Jun; Wu, Jun-Zi; Li, He-Yu; Wu, Jian-Rong; Niu, Shi-Wei; Zhu, Li-Min

2017-10-01

A high-strength regenerated bacterial cellulose (RBC)/bacterial cellulose (BC) microfilament of potential use as a biomaterial was successfully prepared via a wet spinning process. The BC not only consists of a 3-D network composed of nanofibers with a diameter of several hundred nanometers but also has a secondary structure consisting of highly oriented nanofibrils with a diameter ranging from a few nanometers to tens of nanometers which explains the reason for the high mechanical strength of BC. Furthermore, a strategy of partially dissolving BC was used and this greatly enhanced the mechanical performance of spun filament and a method called post-treatment was utilized to remove residual solvents from the RBC/BC filaments. A comparison of structure, properties, as well as cytocompatibility between BC nanofibers and RBC/BC microfilaments was achieved using morphology, mechanical properties, X-ray Diffraction (XRD) and an enzymatic hydrolysis assay. The RBC/BC microfilament has a uniform groove structure with a diameter of 50-60μm and XRD indicated that the crystal form was transformed from cellulose Iα to cellulose III I and the degree of crystallinity of RBC/BC (33.22%) was much lower than the original BC (60.29%). The enzymatic hydrolysis assay proved that the RBC/BC material was more easily degraded than BC. ICP detection indicated that the residual amount of lithium was 0.07mg/g (w/w) and GC-MS analysis showed the residual amount of DMAc to be 8.51μg/g (w/w) demonstrating that the post-treatment process is necessary and effective for removal of residual materials from the RBC/BC microfilaments. Also, a cell viability assay demonstrated that after post-treatment the RBC/BC filaments had good cytocompatibility. Copyright © 2017 Elsevier B.V. All rights reserved.

A Novel Platform for Evaluating the Environmental Impacts on Bacterial Cellulose Production.

Science.gov (United States)

Basu, Anindya; Vadanan, Sundaravadanam Vishnu; Lim, Sierin

2018-04-10

Bacterial cellulose (BC) is a biocompatible material with versatile applications. However, its large-scale production is challenged by the limited biological knowledge of the bacteria. The advent of synthetic biology has lead the way to the development of BC producing microbes as a novel chassis. Hence, investigation on optimal growth conditions for BC production and understanding of the fundamental biological processes are imperative. In this study, we report a novel analytical platform that can be used for studying the biology and optimizing growth conditions of cellulose producing bacteria. The platform is based on surface growth pattern of the organism and allows us to confirm that cellulose fibrils produced by the bacteria play a pivotal role towards their chemotaxis. The platform efficiently determines the impacts of different growth conditions on cellulose production and is translatable to static culture conditions. The analytical platform provides a means for fundamental biological studies of bacteria chemotaxis as well as systematic approach towards rational design and development of scalable bioprocessing strategies for industrial production of bacterial cellulose.

Bacterial Cellulose (BC) as a Functional Nanocomposite Biomaterial

Science.gov (United States)

Nandgaonkar, Avinav Ghanashyam

Cellulosic is the most abundant biopolymer in the landscape and can be found in many different organisms. It has been already seen use in the medical field, for example cotton for wound dressings and sutures. Although cellulose is naturally occurring and has found a number of applications inside and outside of the medical field, it is not typically produced in its pure state. A lengthy process is required to separate the lignin, hemicelluloses and other molecules from the cellulose in most renewables (wood, agricultural fibers such as cotton, monocots, grasses, etc.). Although bacterial cellulose has a similar chemical structure to plant cellulose, it is easier to process because of the absence of lignin and hemicelluloses which require a lot of energy and chemicals for removal. Bacterial cellulose (BC) is produced from various species of bacteria such as Gluconacetobacter xylinus. Due to its high water uptake, it has the tendency to form gels. It displays high tensile strength, biocompatibility, and purity compared to wood cellulose. It has found applications in fields such as paper, paper products, audio components (e.g., speaker diaphragms), flexible electronics, supercapacitors, electronics, and soft tissue engineering. In my dissertation, we have functionalized and studied BC-based materials for three specific applications: cartilage tissue engineering, bioelectronics, and dye degradation. In our first study, we prepared a highly organized porous material based on BC by unidirectional freezing followed by a freeze-drying process. Chitosan was added to impart additional properties to the resulting BC-based scaffolds that were evaluated in terms of their morphological, chemical, and physical properties for cartilage tissue engineering. The properties of the resulting scaffold were tailored by adjusting the concentration of chitosan over 1, 1.5, and 2 % (by wt-%). The scaffolds containing chitosan showed excellent shape recovery and structural stability after

Recent developments in the production and applications of bacterial cellulose fibers and nanocrystals.

Science.gov (United States)

Reiniati, Isabela; Hrymak, Andrew N; Margaritis, Argyrios

2017-06-01

Cellulosic nanomaterials provide a novel and sustainable platform for the production of high performance materials enabled by nanotechnology. Bacterial cellulose (BC) is a highly crystalline material and contains pure cellulose without lignin and hemicellulose. BC offers an opportunity to provide control of the products' properties in-situ, via specific BC production methods and culture conditions. The BC potential in advanced material applications are hindered by a limited knowledge of optimal BC production conditions, efficient process scale-up, separation methods, and purification methods. There is a growing body of work on the production of bacterial cellulose nanocrystals (BCNs) from BC fibers. However, there is limited information regarding the effect of BC fibers' characteristics on the production of nanocrystals. This review describes developments in BC and BCNs production methods and factors affecting their yield and physical characteristics.

The productive cellulase binding capacity of cellulosic substrates.

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Karuna, Nardrapee; Jeoh, Tina

2017-03-01

Cellulosic biomass is the most promising feedstock for renewable biofuel production; however, the mechanisms of the heterogeneous cellulose saccharification reaction are still unsolved. As cellulases need to bind isolated molecules of cellulose at the surface of insoluble cellulose fibrils or larger aggregated cellulose structures in order to hydrolyze glycosidic bonds, the "accessibility of cellulose to cellulases" is considered to be a reaction limiting property of cellulose. We have defined the accessibility of cellulose to cellulases as the productive binding capacity of cellulose, that is, the concentration of productive binding sites on cellulose that are accessible for binding and hydrolysis by cellulases. Productive cellulase binding to cellulose results in hydrolysis and can be quantified by measuring hydrolysis rates. In this study, we measured the productive Trichoderma reesei Cel7A (TrCel7A) binding capacity of five cellulosic substrates from different sources and processing histories. Swollen filter paper and bacterial cellulose had higher productive binding capacities of ∼6 µmol/g while filter paper, microcrystalline cellulose, and algal cellulose had lower productive binding capacities of ∼3 µmol/g. Swelling and regenerating filter paper using phosphoric acid increased the initial accessibility of the reducing ends to TrCel7A from 4 to 6 µmol/g. Moreover, this increase in initial productive binding capacity accounted in large part for the difference in the overall digestibility between filter paper and swollen filter paper. We further demonstrated that an understanding of how the productive binding capacity declines over the course of the hydrolysis reaction has the potential to predict overall saccharification time courses. Biotechnol. Bioeng. 2017;114: 533-542. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

A study of a co-processed dry binder composed of microcrystalline cellulose and glycerol monostearate.

Science.gov (United States)

Mužíková, Jitka; Muchová, Sandra

2012-10-01

The paper studies the co-processed dry binder LubriToseTM MCC from the viewpoint of energy evaluation of the compression process, strength and disintegration time of tablets. The results were compared with the identical evaluation of physical mixtures of microcrystalline cellulose with several types of lubricants. LubriTose MCC showed the lowest value of energy for friction, the highest value of energy accumulated by the tablet, and the highest plasticity of all tableting materials under study. There were no marked differences in the values of the energy of decompression. The tensile strength of tablets from LubriTose MCC was lower than in those from the mixture of Vivapur® 12 and glycerol monostearate, in the compression forces of 4 and 5 kN it was comparable with the tensile strength of tablets from Vivapur 12 with Poloxamer 407. Disintegration time of tablets from LubriTose MCC was shorter than that of those from Vivapur 12 with glycerol monostearate at the compression force of 3 kN, in the case of the compression forces of 4 and 5 kN no statistically significant difference was found between the values of these tableting materials.

Statistical Optimization for Acid Hydrolysis of Microcrystalline Cellulose and Its Physiochemical Characterization by Using Metal Ion Catalyst

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Md. Ziaul Karim

2014-10-01

Full Text Available Hydrolyzing the amorphous region while keeping the crystalline region unaltered is the key technology for producing nanocellulose. This study investigated if the dissolution properties of the amorphous region of microcrystalline cellulose can be enhanced in the presence of Fe3+ salt in acidic medium. The process parameters, including temperature, time and the concentration of metal chloride catalyst (FeCl3, were optimized by using the response surface methodology (RSM. The experimental observation demonstrated that temperature and time play vital roles in hydrolyzing the amorphous sections of cellulose. This would yield hydrocellulose with higher crystallinity. The factors that were varied for the production of hydrocellulose were the temperature (x1, time (x2 and FeCl3 catalyst concentration (x3. Responses were measured in terms of percentage of crystallinity (y1 and the yield (y2 of the prepared hydrocellulose. Relevant mathematical models were developed. Analysis of variance (ANOVA was carried out to obtain the most significant factors influencing the responses of the percentage of crystallinity and yield. Under optimum conditions, the percentage of crystallinity and yield were 83.46% and 86.98% respectively, at 90.95 °C, 6 h, with a catalyst concentration of 1 M. The physiochemical characteristics of the prepared hydrocellulose were determined in terms of XRD, SEM, TGA and FTIR analyses. The addition of FeCl3 salt in acid hydrolyzing medium is a novel technique for substantially increasing crystallinity with a significant morphological change.

Electro-mechanical properties of hydrogel composites with micro- and nano-cellulose fillers

International Nuclear Information System (INIS)

Shahid U N, Mohamed; Deshpande, Abhijit P; Rao, C Lakshmana

2015-01-01

Stimuli responsive cross-linked hydrogels are of great interest for applications in diverse fields such as sensors and biomaterials. In this study, we investigate polymer composites filled with cellulose fillers. The celluloses used in making the composites were a microcrystalline cellulose of commercial grade and cellulose nano-whiskers obtained through acid hydrolysis of microcrystalline cellulose. The filler concentration was varied and corresponding physical, mechanical and electro-mechanical characterization was carried out. The electro-mechanical properties were determined using a quasi-static method. The fillers not only enhance the mechanical properties of the composite by providing better reinforcement but also provide a quantitative electric potential in the composite. The measurements reveal that the polymer composites prepared from two different cellulose fillers possess a quantitative electric potential which can be utilized in biomedical applications. It is argued that the mechanism behind the quantitative electric potential in the composites is due to streaming potentials arising due to electrical double layer formation. (paper)

Ultrasound-assisted swelling of bacterial cellulose

OpenAIRE

Song, J.; Su, Jing; Loureiro, Ana; Sá, M.; Cavaco-Paulo, Artur; Kim, Hye Rim; Silva, Carla

2017-01-01

Bacterial cellulose (BC) was obtained by static cultivation using commercial BC gel from scoby. BC membranes (oven dried and freeze-dried) were swelled with 8% NaOH, in absence and in presence of ultrasound (US), for 30, 60 and 90 min. The influence of swelling conditions on both physico-chemical properties and molecules entrapment was evaluated. Considering the highest levels of entrapment, an optimum swelling procedure was established: 8% NaOH for 30 min. at room temperature in the presence...

In vitro chondrogenesis with lysozyme susceptible bacterial cellulose as a scaffold.

Science.gov (United States)

Yadav, Vikas; Sun, Lin; Panilaitis, Bruce; Kaplan, David L

2015-12-01

A current focus of tissue engineering is the use of adult human mesenchymal stem cells (hMSCs) as an alternative to autologous chondrocytes for cartilage repair. Several natural and synthetic polymers (including cellulose) have been explored as a biomaterial scaffold for cartilage tissue engineering. While bacterial cellulose (BC) has been used in tissue engineering, its lack of degradability in vivo and high crystallinity restricts widespread applications in the field. Recently we reported the formation of a novel bacterial cellulose that is lysozyme-susceptible and -degradable in vivo from metabolically engineered Gluconacetobacter xylinus. Here we report the use of this modified bacterial cellulose (MBC) for cartilage tissue engineering using hMSCs. MBC's glucosaminoglycan-like chemistry, combined with in vivo degradability, suggested opportunities to exploit this novel polymer in cartilage tissue engineering. We have observed that, like BC, MBC scaffolds support cell attachment and proliferation. Chondrogenesis of hMSCs in the MBC scaffolds was demonstrated by real-time RT-PCR analysis for cartilage-specific extracellular matrix (ECM) markers (collagen type II, aggrecan and SOX9) as well as histological and immunohistochemical evaluations of cartilage-specific ECM markers. Further, the attachment, proliferation, and differentiation of hMSCs in MBC showed unique characteristics. For example, after 4 weeks of cultivation, the spatial cell arrangement and collagen type-II and ACAN distribution resembled those in native articular cartilage tissue, suggesting promise for these novel in vivo degradable scaffolds for chondrogenesis. Copyright © 2013 John Wiley & Sons, Ltd.

Preparation and characterization of novel wound dressing based on silver nanoparticle-impregnated bacterial cellulose and bacterial cellulose-aloe vera

International Nuclear Information System (INIS)

Ventigan, Sarla V.; Santiago, Karen S.; Balitaan, Jolleen Natalie I.

2015-01-01

Ideal wound dressings stimulate wound healing, control unpleasant odors, and provide antimicrobial action in wounds. However, most traditional wound dressings such as gauze and biological dressings exhibit exudate leaking which increases the risk of infection and delayed wound healing of tissues. This study aims to develop and characterize a bio-composite of bacterial cellulose and aloe vera having the ideal features of a wound dressing from Acetobacter xylinum-activated culture medium supplemented with various aloe vera concentrations from )-50% (v/v) and the film which exhibits the most uniform results is used for the incorporation of silver nanoparticle as an antibacterial agent. The biopolymer composites of bacterial cellulose and aloe vera were developed by adding 0-50% aloe vera (v/v) in the A. xylinum-activated coconut water medium during biosynthesis in static cultivation for 10 days. The films obtained after drying the membranes were named as bacterial cellulose-aloe vera (BC-A) films. The moisture content of films reached 99% which indicates that the films may be suitable for providing a moist environment to facilitate wound healing fast. With the addition of aloe vera up to 30% (v/v) during BC synthesis, it resulted in a significant improvement in the water absorption capacity of the films showing a WAC ration of 36.46 (r.s.d.= 12.17%, n=3) compared to the unmodified film having a ratio of 9.03 (r.s.d.= 13.95%, n=3). However, the addition of aloe vera at a concentration greater than 30% (v/v) resulted in a decrease in pellicle formation which can be observed from the very weak properties of the films. The BC-A (30%) displayed significantly improved in comparison to the unmodified BC film. Also, it is capable of absorbing high amount of water than its weight and can act as a potential wound dressing which reduces irritation and inflammation. (author)

Bacterial Cellulose Production from Beet Molasses | Keshk | African ...

African Journals Online (AJOL)

The yield of the bacterial cellulose (BC) produced from beet molasses was higher than that using glucose as a sole carbon source. The structure of BC produced in presence of beet molasses was studied using IR spectroscopy and X-ray diffractometry. IR spectra show the relative absorbance of CO- C ether linkage (at 1120 ...

Synthesis and Characterization of Alkylated Bacterial Cellulose in an Ionic Liquid

Directory of Open Access Journals (Sweden)

Jinmin Qin

2015-02-01

Full Text Available Bacterial cellulose was alkylated by alkyl halide in the ionic liquid 1-butyl-3-methylimmidazolium chloride ([Bmim]Cl with NaH as the alkaline agent. The derivatives were characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, elemental analyses, X-ray diffraction, and thermal gravimetric analyses. The resultant bacterial cellulose alkylated derivatives (BCADs had a degree of substitution (DS between 0.21 and 2.01. The effects of the alkylating agent, reactant amount, and temperature on the DS were investigated. BCADs with a butyl substituent had a higher DS than did those with ethyl or propyl groups. The crystallinity and thermal stability of the derivatives decreased after modification owing to the change in morphological structure.

Cellulosic hydrogen production with a sequencing bacterial hydrolysis and dark fermentation strategy.

Science.gov (United States)

Lo, Yung-Chung; Bai, Ming-Der; Chen, Wen-Ming; Chang, Jo-Shu

2008-11-01

In this study, cellulose hydrolysis activity of two mixed bacterial consortia (NS and QS) was investigated. Combination of NS culture and BHM medium exhibited better hydrolytic activity under the optimal condition of 35 degrees C, initial pH 7.0, and 100rpm agitation. The NS culture could hydrolyze carboxymethyl cellulose (CMC), rice husk, bagasse and filter paper, among which CMC gave the best hydrolysis performance. The CMC hydrolysis efficiency increased with increasing CMC concentration from 5 to 50g/l. With a CMC concentration of 10g/l, the total reducing sugar (RS) production and the RS producing rate reached 5531.0mg/l and 92.9mg/l/h, respectively. Furthermore, seven H2-producing bacterial isolates (mainly Clostridium species) were used to convert the cellulose hydrolysate into H2 energy. With an initial RS concentration of 0.8g/l, the H2 production and yield was approximately 23.8ml/l and 1.21mmol H2/g RS (0.097mmol H2/g cellulose), respectively.

Magnetically modified bacterial cellulose: A promising carrier for immobilization of affinity ligands, enzymes, and cells

Energy Technology Data Exchange (ETDEWEB)

Baldikova, Eva [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Pospiskova, Kristyna [Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71 Olomouc (Czech Republic); Ladakis, Dimitrios; Kookos, Ioannis K. [Department of Chemical Engineering, University of Patras, 26504 Patras, Rio (Greece); Koutinas, Apostolis A. [Department of Food Science and Human Nutrition, Agricultural University of Athens, Iera Odos 75, Athens 11855 (Greece); Safarikova, Mirka [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Safarik, Ivo, E-mail: safarik@nh.cas.cz [Global Change Research Institute, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic); Regional Centre of Advanced Technologies and Materials, Palacky University, Slechtitelu 27, 783 71 Olomouc (Czech Republic); Department of Nanobiotechnology, Biology Centre, ISB, CAS, Na Sadkach 7, 370 05 Ceske Budejovice (Czech Republic)

2017-02-01

Bacterial cellulose (BC) produced by Komagataeibacter sucrofermentans was magnetically modified using perchloric acid stabilized magnetic fluid. Magnetic bacterial cellulose (MBC) was used as a carrier for the immobilization of affinity ligands, enzymes and cells. MBC with immobilized reactive copper phthalocyanine dye was an efficient adsorbent for crystal violet removal; the maximum adsorption capacity was 388 mg/g. Kinetic and thermodynamic parameters were also determined. Model biocatalysts, namely bovine pancreas trypsin and Saccharomyces cerevisiae cells were immobilized on MBC using several strategies including adsorption with subsequent cross-linking with glutaraldehyde and covalent binding on previously activated MBC using sodium periodate or 1,4-butanediol diglycidyl ether. Immobilized yeast cells retained approximately 90% of their initial activity after 6 repeated cycles of sucrose solution hydrolysis. Trypsin covalently bound after MBC periodate activation was very stable during operational stability testing; it could be repeatedly used for ten cycles of low molecular weight substrate hydrolysis without loss of its initial activity. - Highlights: • Bacterial cellulose was magnetically modified with magnetic fluid. • Magnetic cellulose is an efficient carrier for affinity ligands. • Enzymes and cells can be efficiently immobilized to magnetic cellulose.

Oxidoreductive Cellulose Depolymerization by the Enzymes Cellobiose Dehydrogenase and Glycoside Hydrolase 61▿†

Science.gov (United States)

Langston, James A.; Shaghasi, Tarana; Abbate, Eric; Xu, Feng; Vlasenko, Elena; Sweeney, Matt D.

2011-01-01

Several members of the glycoside hydrolase 61 (GH61) family of proteins have recently been shown to dramatically increase the breakdown of lignocellulosic biomass by microbial hydrolytic cellulases. However, purified GH61 proteins have neither demonstrable direct hydrolase activity on various polysaccharide or lignacious components of biomass nor an apparent hydrolase active site. Cellobiose dehydrogenase (CDH) is a secreted flavocytochrome produced by many cellulose-degrading fungi with no well-understood biological function. Here we demonstrate that the binary combination of Thermoascus aurantiacus GH61A (TaGH61A) and Humicola insolens CDH (HiCDH) cleaves cellulose into soluble, oxidized oligosaccharides. TaGH61A-HiCDH activity on cellulose is shown to be nonredundant with the activities of canonical endocellulase and exocellulase enzymes in microcrystalline cellulose cleavage, and while the combination of TaGH61A and HiCDH cleaves highly crystalline bacterial cellulose, it does not cleave soluble cellodextrins. GH61 and CDH proteins are coexpressed and secreted by the thermophilic ascomycete Thielavia terrestris in response to environmental cellulose, and the combined activities of T. terrestris GH61 and T. terrestris CDH are shown to synergize with T. terrestris cellulose hydrolases in the breakdown of cellulose. The action of GH61 and CDH on cellulose may constitute an important, but overlooked, biological oxidoreductive system that functions in microbial lignocellulose degradation and has applications in industrial biomass utilization. PMID:21821740

Plasticized Biodegradable Poly(lactic acid Based Composites Containing Cellulose in Micro- and Nanosize

Directory of Open Access Journals (Sweden)

Katalin Halász

2013-01-01

Full Text Available The aim of this work was to study the characteristics of thermal processed poly(lactic acid composites. Poly(ethylene glycol (PEG400, microcrystalline cellulose (MCC, and ultrasound-treated microcrystalline cellulose (USMCC were used in 1, 3, and 5 weight percents to modify the attributes of PLA matrix. The composite films were produced by twin screw extrusion followed by film extrusion. The manufactured PLA-based films were characterized by tensile testing, differential scanning calorimetry (DSC, scanning electron microscopy (SEM, wide angle X-ray diffraction (WAXD, and degradation test.

Kombucha-synthesized bacterial cellulose: preparation, characterization, and biocompatibility evaluation.

Science.gov (United States)

Zhu, Changlai; Li, Feng; Zhou, Xinyang; Lin, Lin; Zhang, Tianyi

2014-05-01

Bacterial cellulose (BC) is a natural biomaterial with unique properties suitable for tissue engineering applications, but it has not yet been used for preparing nerve conduits to repair peripheral nerve injuries. The objectives of this study were to prepare and characterize the Kampuchea-synthesized bacterial cellulose (KBC) and further evaluate the biocompatibility of KBC with peripheral nerve cells and tissues in vitro and in vivo. KBC membranes were composed of interwoven ribbons of about 20-100 nm in width, and had a high purity and the same crystallinity as that of cellulose Iα. The results from light and scanning electron microscopy, MTT assay, flow cytometry, and RT-PCR indicated that no significant differences in the morphology and cell function were observed between Schwann cells (SCs) cultured on KBC membranes and glass slips. We also fabricated a nerve conduit using KBC, which was implanted into the spatium intermusculare of rats. At 1, 3, and 6 weeks post-implantation, clinical chemistry and histochemistry showed that there were no significant differences in blood counts, serum biochemical parameters, and tissue reactions between implanted rats and sham-operated rats. Collectively, our data indicated that KBC possessed good biocompatibility with primary cultured SCs and KBC did not exert hematological and histological toxic effects on nerve tissues in vivo. Copyright © 2013 Wiley Periodicals, Inc.

Fractal analysis of SEM images and mercury intrusion porosimetry data for the microstructural characterization of microcrystalline cellulose-based pellets

International Nuclear Information System (INIS)

Gomez-Carracedo, A.; Alvarez-Lorenzo, C.; Coca, R.; Martinez-Pacheco, R.; Concheiro, A.; Gomez-Amoza, J.L.

2009-01-01

The microstructure of theophylline pellets prepared from microcrystalline cellulose, carbopol and dicalcium phosphate dihydrate, according to a mixture design, was characterized using textural analysis of gray-level scanning electron microscopy (SEM) images and thermodynamic analysis of the cumulative pore volume distribution obtained by mercury intrusion porosimetry. Surface roughness evaluated in terms of gray-level non-uniformity and fractal dimension of pellet surface depended on agglomeration phenomena during extrusion/spheronization. Pores at the surface, mainly 1-15 μm in diameter, determined both the mechanism and the rate of theophylline release, and a strong negative correlation between the fractal geometry and the b parameter of the Weibull function was found for pellets containing >60% carbopol. Theophylline mean dissolution time from these pellets was about two to four times greater. Textural analysis of SEM micrographs and fractal analysis of mercury intrusion data are complementary techniques that enable complete characterization of multiparticulate drug dosage forms

Comparison of pharyngocutaneous fistula closure with and without bacterial cellulose in a rat model.

Science.gov (United States)

Demir, Berat; Sarı, Murat; Binnetoglu, Adem; Yumusakhuylu, Ali Cemal; Filinte, Deniz; Tekin, İshak Özel; Bağlam, Tekin; Batman, Abdullah Çağlar

2018-04-01

The present study aimed to compare the effects of bacterial cellulose used for closure of pharyngocutaneous fistulae, a complication of total laryngectomy, with those of primary sutures in a rat model. Thirty female Sprague-Dawley underwent experimental pharyngoesophagotomy and were grouped depending on the material used for pharyngocutaneous fistula closure: group I, which received primary sutures alone, group II, which received bacterial cellulose alone; and group III, which received both. After 7 days, the rats were sacrificed. Pharyngocutaneous fistula development was assessed, the gross wound was inspected, and histological examination was conducted. Pharyngocutaneous fistulae developed in 12 rats (41%) in all: 6 from group I (21%), 4 from group II (14%) and 2 from group III (7%). Fibroblast density and inflammatory cell infiltration were significantly greater in group III than group I. We concluded that bacterial cellulose may be useful for pharyngocutaneous fistula closure. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of cellulose nanowhiskers; Caracterizacao do nanowhiskers de celulose

Energy Technology Data Exchange (ETDEWEB)

Nascimento, Nayra R.; Pinheiro, Ivanei F.; Morales, Ana R.; Ravagnani, Sergio P.; Mei, Lucia, E-mail: 25nareis@gmail.com [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

2015-07-01

Cellulose is the most abundant polymer earth. The cellulose nanowhiskers can be extracted from the cellulose. These have attracted attention for its use in nanostructured materials for various applications, such as nanocomposites, because they have peculiar characteristics, among them, high aspect ratio, biodegradability and excellent mechanical properties. This work aims to characterize cellulose nanowhiskers from microcrystalline cellulose. Therefore, these materials were characterized by X-ray diffraction (XRD) to assess the degree of crystallinity, infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) to the morphology of nanowhiskers and thermal stability was evaluated by Thermogravimetric Analysis (TGA). (author)

Composite scaffolds for cartilage tissue engineering based on natural polymers of bacterial origin, thermoplastic poly(3-hydroxybutyrate) and micro-fibrillated bacterial cellulose

Czech Academy of Sciences Publication Activity Database

Akaraonye, E.; Filip, J.; Šafaříková, Miroslava; Salih, V.; Keshavarz, T.; Knowles, J.C.; Roy, I.

2016-01-01

Roč. 65, č. 7 (2016), s. 780-791 ISSN 0959-8103 Institutional support: RVO:60077344 Keywords : polyhydroxyalkanoates * poly(3-hydroxybutyrate) * bacterial cellulose * micro-fibrillated cellulose * tissue engineering scaffold * composite materials Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.070, year: 2016

Green synthesis of hybrid graphene oxide/microcrystalline cellulose aerogels and their use as superabsorbents

Energy Technology Data Exchange (ETDEWEB)

Wei, Xiao; Huang, Ting; Yang, Jing-hui; Zhang, Nan; Wang, Yong, E-mail: yongwang1976@163.com; Zhou, Zuo-wan

2017-08-05

Highlights: • Hybrid GO/MCC aerogels were prepared using LiBr aqueous solution as the solvent. • GO was exfoliated by MCC through the strong interaction between them. • The adsorption ability of GO per unit mass in the hybrid aerogels was greatly enhanced. - Abstract: In this work, we developed a green synthesis method to prepare the hybrid aerogels containing graphene oxide (GO) and microcrystalline cellulose (MCC) using lithium bromide (LiBr) aqueous solution as the solvent, which insured the complete dissolution of MCC. The interaction between GO and MCC was investigated through different methods The results demonstrate that there is a strong interaction between GO and MCC molecules, which promotes the exfoliation of GO in the hybrid aerogels. The hybrid GO/MCC aerogels exhibit typical three dimensional porous structure and the pore morphology can be well adjusted by changing the content of GO. The adsorption ability of the hybrid aerogels was measured using methylene blue (MB) as an adsorbate. The results show that the adsorption ability of GO per unit mass is greatly enhanced compared with the pure GO aerogel, especially at relatively low GO content the adsorption amount of GO per unit mass is enhanced up to 2630 mg/g. Further results demonstrate that the hybrid GO/MCC aerogels still obey the pseudo-second-order adsorption model, which is similar to that of the pure GO aerogel. The mechanism for the amplified adsorption ability of GO in the hybrid GO/MCC aerogels is then analyzed.

Green synthesis of hybrid graphene oxide/microcrystalline cellulose aerogels and their use as superabsorbents

International Nuclear Information System (INIS)

Wei, Xiao; Huang, Ting; Yang, Jing-hui; Zhang, Nan; Wang, Yong; Zhou, Zuo-wan

2017-01-01

Highlights: • Hybrid GO/MCC aerogels were prepared using LiBr aqueous solution as the solvent. • GO was exfoliated by MCC through the strong interaction between them. • The adsorption ability of GO per unit mass in the hybrid aerogels was greatly enhanced. - Abstract: In this work, we developed a green synthesis method to prepare the hybrid aerogels containing graphene oxide (GO) and microcrystalline cellulose (MCC) using lithium bromide (LiBr) aqueous solution as the solvent, which insured the complete dissolution of MCC. The interaction between GO and MCC was investigated through different methods The results demonstrate that there is a strong interaction between GO and MCC molecules, which promotes the exfoliation of GO in the hybrid aerogels. The hybrid GO/MCC aerogels exhibit typical three dimensional porous structure and the pore morphology can be well adjusted by changing the content of GO. The adsorption ability of the hybrid aerogels was measured using methylene blue (MB) as an adsorbate. The results show that the adsorption ability of GO per unit mass is greatly enhanced compared with the pure GO aerogel, especially at relatively low GO content the adsorption amount of GO per unit mass is enhanced up to 2630 mg/g. Further results demonstrate that the hybrid GO/MCC aerogels still obey the pseudo-second-order adsorption model, which is similar to that of the pure GO aerogel. The mechanism for the amplified adsorption ability of GO in the hybrid GO/MCC aerogels is then analyzed.

New biphasic monocomponent composite material obtained by the partial oxypropylation of bacterial cellulose

International Nuclear Information System (INIS)

Rosa, Joyce Rover; Silva, Ingrid S.V. da; Pasquini, Daniel; Santos, Daniele B. dos; Barud, Hernane S.; Ribeiro, Sidney J.L.

2011-01-01

This study aimed to partial oxypropylation of bacterial cellulose (CB), as well as the characterization of pure CB, oxypropylated CB (CBO) and oxypropylated CB after Soxhlet extraction with hexane (CBOE). The oxypropylation reaction was carried out by propylene oxide polymerization, catalyzed by KOH, in the presence of CB The CB samples, before and after modification, were subjected to analysis of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was possible verify that the partial transformation of bacterial cellulose by inserting a layer of thermoplastic polymer on its surface occurred efficiently, obtaining a biphasic monocomponent composite material. (author)

Cellulose with a High Fractal Dimension Is Easily Hydrolysable under Acid Catalysis

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Mariana Díaz

2017-05-01

Full Text Available The adsorption of three diverse amino acids couples onto the surface of microcrystalline cellulose was studied. Characterisation of modified celluloses included changes in the polarity and in roughness. The amino acids partially break down the hydrogen bonding network of the cellulose structure, leading to more reactive cellulose residues that were easily hydrolysed to glucose in the presence of hydrochloric acid or tungstophosphoric acid catalysts. The conversion of cellulose and selectivity for glucose was highly dependent on the self-assembled amino acids adsorbed onto the cellulose and the catalyst.

Effect of the conditions of preparation on the properties of a cellulose exchanger containing salicylic acid as a functional group

Energy Technology Data Exchange (ETDEWEB)

Lieser, K H; Foerster, M; Burba, P [Technische Hochschule Darmstadt (Germany, F.R.). Fachbereich Anorganische Chemie und Kernchemie

1977-04-01

The preparation of a cellulose derivative containing salicylic acid as functional group was varied in order to find optimal conditions with respect to fast exchange as well as high capacity. Two kinds of cellulose (cross-linked and microcrystalline) and different reaction times were used. The properties of the products were investigated by titration curves to determine the capacity and by measuring the non-isotopic exchange Na/sup +//*Fe/sup 3 +/ and the isotopic exchange *Fe/sup 3 +//Fe/sup 3 +/ as a function of time. Microcrystalline cellulose and a reaction time of 15 min gave optimal results.

Dispersions of attractive semiflexible fiberlike colloidal particles from bacterial cellulose microfibrils.

Science.gov (United States)

Kuijk, Anke; Koppert, Remco; Versluis, Peter; van Dalen, Gerard; Remijn, Caroline; Hazekamp, Johan; Nijsse, Jaap; Velikov, Krassimir P

2013-11-26

We prepared dispersions from bacterial cellulose microfibrils (CMF) of a commercial Nata de Coco source. We used an ultra-high-energy mechanical deagglomeration process that is able to disperse the CMFs from the pellicle in which they are organized in an irregular network. Because of the strong attractions between the CMFs, the dispersion remained highly heterogeneous, consisting of fiber bundles, flocs, and voids spanning tens to hundreds of micrometers depending on concentration. The size of these flocs increased with CMF concentration, the size of the bundles stayed constant, and the size of the voids decreased. The observed percolation threshold in MFC dispersions is lower than the theoretical prediction, which is accounted for by the attractive interactions in the system. Because bacterial cellulose is chemically very pure, it can be used to study the interaction of attractive and highly shape-anisotropic, semiflexible fiberlike colloidal particles.

Comparative evaluation of the powder and compression properties of various grades and brands of microcrystalline cellulose by multivariate methods.

Science.gov (United States)

Haware, Rahul V; Bauer-Brandl, Annette; Tho, Ingunn

2010-01-01

The present work challenges a newly developed approach to tablet formulation development by using chemically identical materials (grades and brands of microcrystalline cellulose). Tablet properties with respect to process and formulation parameters (e.g. compression speed, added lubricant and Emcompress fractions) were evaluated by 2(3)-factorial designs. Tablets of constant true volume were prepared on a compaction simulator at constant pressure (approx. 100 MPa). The highly repeatable and accurate force-displacement data obtained was evaluated by simple 'in-die' Heckel method and work descriptors. Relationships and interactions between formulation, process and tablet parameters were identified and quantified by multivariate analysis techniques; principal component analysis (PCA) and partial least square regressions (PLS). The method proved to be able to distinguish between different grades of MCC and even between two different brands of the same grade (Avicel PH 101 and Vivapur 101). One example of interaction was studied in more detail by mixed level design: The interaction effect of lubricant and Emcompress on elastic recovery of Avicel PH 102 was demonstrated to be complex and non-linear using the development tool under investigation.

Polyvinyl Chloride / Attapulgite / Micro-crystalline Cellulose (MCC Composites Preparation and Analysis of the Role of MCC as a Compatibilizer

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Bo Wang

2015-09-01

Full Text Available To improve the performance of polyvinyl chloride (PVC, composites incorporating polyvinyl chloride (PVC, attapulgite nanoparticles (ANPs, and microcrystalline cellulose (MCC were successfully prepared. The composites had higher vicat softening temperatures (VSTs and the MCC had a great influence on mechanical properties of the composites. When MCC was added from 0 to 5 per hundred parts of PVC (phr, the mechanical properties of the composites increased, but the mechanical properties of the composites decreased when the MCC was more than 5 phr. The tensile breaking stress, tensile strength, and impact strength were maximized with increases of 19.76 N (4.1%, 29.66 MPa (15.5%, and 13.8 MPa (7% when 5 phr MCC was added. Infrared spectral analysis indicated that MCC and ANPs were present in the composites. Scanning electron microscopy showed that the composites system was distributed into two phases, which indicated that MCC in composites was dissolved in the PVC matrix, and some of MCC coated the surface of ANPs as a compatibilizer. Overall, this study provided a promising method for PVC modification to improve its performance.

Spatially Resolved Characterization of Cellulose Nanocrystal-Polypropylene Composite by Confocal Raman Microscopy

Science.gov (United States)

Umesh P. Agarwal; Ronald Sabo; Richard S. Reiner; Craig M. Clemons; Alan W. Rudie

2012-01-01

Raman spectroscopy was used to analyze cellulose nanocrystal (CNC)–polypropylene (PP) composites and to investigate the spatial distribution of CNCs in extruded composite filaments. Three composites were made from two forms of nanocellulose (CNCs from wood pulp and the nanoscale fraction of microcrystalline cellulose) and two of the three composites investigated used...

Correlation between cellulose physical-chemical properties and its solubilization and derivatization in DMAc/LiCl

International Nuclear Information System (INIS)

Ramos, Ludmila de A.; Frollini, Elisabete; Assaf, Jose M.

2001-01-01

We report on the dissolution and acetylation under homogeneous solution conditions, in DMAc/LiCl, of microcrystalline cellulose Avicel PH 101, as well as cellulose from cotton linter and mercerized cotton linter. The porous and crystalline cellulose structures were investigated by BET method and X-rays diffraction, respectively. During dissolution, the cellulose structural changes were followed by Scanning Electron Microscopy (SEM) and X-rays diffraction. The degree of substitution (DS) of the products was discussed regarding cellulose properties. (author)

Biomimetic design of a bacterial cellulose/hydroxyapatite nanocomposite for bone healing applications

Energy Technology Data Exchange (ETDEWEB)

Zimmermann, Kristen A., E-mail: kazimmer@vt.edu [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24060 (United States); School of Biomedical Engineering Sciences, Virginia Tech, Blacksburg, VA 24060 (United States); LeBlanc, Jill M.; Sheets, Kevin T.; Fox, Robert W. [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24060 (United States); Gatenholm, Paul [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA 24060 (United States); School of Biomedical Engineering Sciences, Virginia Tech, Blacksburg, VA 24060 (United States)

2011-01-01

This study describes the design and synthesis of bacterial cellulose/hydroxyapatite nanocomposites for bone healing applications using a biomimetic approach. Bacterial cellulose (BC) with various surface morphologies (pellicles and tubes) was negatively charged by the adsorption of carboxymethyl cellulose (CMC) to initiate nucleation of calcium-deficient hydroxyapatite (cdHAp). The cdHAp was grown in vitro via dynamic simulated body fluid (SBF) treatments over a one week period. Characterization of the mineralized samples was done with X-ray Photoelectron Spectroscopy (XPS) and Field Emission Scanning Electron Microscopy (FESEM) with Energy Dispersive Spectroscopy (EDS). The amount of cdHAp observed varied among different samples. XPS demonstrated that the atomic presence of calcium and phosphorus ranged from 0.44 at.% to 7.71 at.% Ca and 0.27 at.% to 11.18 at.% P. The Ca/P overall ratio ranged from 1.22 to 1.92. FESEM images showed that the cdHAp crystal size increased with increasing nanocellulose fibril density. To determine the viability of the scaffolds in vitro, the morphology and differentiation of osteoprogenitor cells was analyzed using fluorescence microscopy and alkaline phosphatase gene expression. The presence of cdHAp crystals on BC surfaces resulted in increased cell attachment.

Performance of improved bacterial cellulose application in the production of functional paper.

Science.gov (United States)

Basta, A H; El-Saied, H

2009-12-01

The purpose of this work was to study the feasibility of producing economic flame retardant bacterial cellulose (BC) and evaluating its behaviour in paper production. This type of BC was prepared by Gluconacetobacter subsp. xylinus and substituting the glucose in the cultivation medium by glucose phosphate as a carbon source; as well as using corn steep liquor as a nitrogen source. The investigated processing technique did not dispose any toxic chemicals that pollute the surroundings or cause unacceptable effluents, making the process environmentally safe. The fire retardant behaviour of the investigated BC has been studied by non-isothermal thermogravimetric analysis (TGA & DTGA). The activation energy of each degradation stage and the order of degradation were estimated using the Coats-Redfern equation and the least square method. Strength, optical properties, and thermogravimetric analysis of BC-phosphate added paper sheets were also tested. The study confirmed that the use of glucose phosphate along with glucose was significant in the high yield production of phosphate containing bacterial cellulose (PCBC1); more so than the use of glucose phosphate alone (PCBC2). Incorporating 5% of the PCBC with wood pulp during paper sheet formation was found to significantly improve kaolin retention, strength, and fire resistance properties as compared to paper sheets produced from incorporating bacterial cellulose (BC). This modified BC is a valuable product for the preparation of specialized paper, in addition to its function as a fillers aid.

Production, property, and application of bacterial cellulose; Bakuteriaserurosu no seisan, butsusei no tokucho to sono riyo

Energy Technology Data Exchange (ETDEWEB)

Yamanaka, S.; Watanabe, K. [Ajinomoto Co. Inc., Tokyo (Japan). Central Research Lab.; Iguchi, M. [Agency of Industrial Science and Technology, Tokyo (Japan)] Nishi, Y. [Sony Corp., Tokyo (Japan)

1998-09-01

Cellulose produced by bacterial is called bacterial cellulose (BC). The morphology and physical properties of BC are found to be quite unique in comparison with those of higher class plants. The properties are elucidated and a study is made to utilize the properties. The outline of this study is introduced in the sequence of BC production, BC morphology, elucidation of the physical property, and study on the application. BC consists of ultrafine fibers, and the widths of fibers are in the range from (1/199) to (1/1,000) of cotton fibers, forming distinctive network structure. It is assumed that the high Young`s modulus is based on the structural features of BC. Researches have been made on various applications to such fields as audio, paper, food, and compounds where the features of cellulose are utilized effectively. The morphology of cellulose can be varied by adding drugs which can change a part of the protein. It is expected that cellulose structure can be controlled in the future by the application of this technology. 18 refs., 6 figs., 2 tabs.

Adsorption mechanism of microcrystalline cellulose as green adsorbent for the removal of cationic methylene blue dye

International Nuclear Information System (INIS)

Tan, K.B.; Salamatinia, B.

2016-01-01

The adsorption mechanism of pure cellulose is yet to be explored. Thus, in this study, the adsorption mechanism of Microcrystalline Cellulose (MCC), a polysaccharide which is renewable, low cost and non-toxic, was studied on the adsorption of model dye Methylene blue (MB). It was found that the main adsorption mechanism of MB on MCC was due to the electrostatic attraction between the positively charged MB dye and negatively charged MCC. Thus, physical adsorption was the dominant effect, since electrostatic attraction is categorized as physical adsorption. This was verified by Dubinin-Radushkevich isotherm, whereby mean free energy adsorption value was found to be less than 8 kJ/mol. The values of Gibbs free energy for thermodynamics studies were found to be within the range of -20 kJ/mol and 0 kJ/mol, which also indicated physical adsorption. It was due to the electrostatic attraction as adsorption mechanism of this adsorption process which resulted rapid adsorption of MB dye. It was found that equilibrium dye concentration was achieved between 1-3 minutes, depending on the adsorption temperature. The rapid adsorption, as compared to a lot of materials, showed the potential of MCC as the future of green adsorbent. The adsorption of Methylene Blue on MCC fitted well in Langmuir Isotherm, with R2 values of higher than 0.99, while fitted moderately in Freundlich Isotherm, with R2 values between 0.9224 and 0.9223. Comparatively, the adsorption of MB on MCC fitted best Langmuir Isotherm as compared to Freundlich Isotherm which monolayer adsorption occurred at the homogenous surface of MCC. This also indicated adsorbed MB molecules do not interact with each other at neighboring adsorption sites. The maximum adsorption capacity calculated from Langmuir Isotherm was found to be 4.95 mg/g. Despite the potential of MCC as green adsorbent, the challenge of low adsorption capacity has to be addressed in the future. (author)

Biosynthesis of highly porous bacterial cellulose nanofibers

Science.gov (United States)

Hosseini, Hadi; Kokabi, Mehrdad; Mousavi, Seyyed Mohammad

2018-01-01

Bacterial cellulose nanofibers (BCNFs) as a sustainable and biodegradable polymer has drawn tremendous research attention in tissue engineering, bacterial sensors and drug delivery due to its extraordinary properties such as high purity, high crystallinity, high water absorption capacity and excellent mechanical strength in the wet state. This awesome properties, is attributed to BCNFs structure, therefore its characterization is important. In this work, the bacterial strain, Gluconacetobacter xylinus (PTCC 1734, obtained from Iranian Research Organization for Science and Technology (IROST)), was used to produce BCNFs hydrogel using bacterial fermentation under static condition at 29 °C for 10 days in the incubator. Then, the biosynthesized BCNFs wet gel, were dried at ambient temperature and pressure and characterized using Brunauer-Emmett-Teller (BET) and Field emission scanning electron microscopy (FE-SEM) analysis. FESEM image displayed highly interconnected and porous structure composed of web-like continuous, nanofibers with an average diameter of 48.5±2.1 nm. BET result analysis depicted BCNFs dried at ambient conditions had IV isotherm type, according to the IUPAC classification, indicating that BCNFs dried at ambient condition is essentially mesoporous. On the other hand, BET results depicted, mesoporous structure is around 85%. In addition, Specific surface area (SBET) obtained 81.45 m2/g. These results are in accordance with the FESEM observation.

Design and characterization of synthetic fungal-bacterial consortia for direct production of isobutanol from cellulosic biomass.

Science.gov (United States)

Minty, Jeremy J; Singer, Marc E; Scholz, Scott A; Bae, Chang-Hoon; Ahn, Jung-Ho; Foster, Clifton E; Liao, James C; Lin, Xiaoxia Nina

2013-09-03

Synergistic microbial communities are ubiquitous in nature and exhibit appealing features, such as sophisticated metabolic capabilities and robustness. This has inspired fast-growing interest in engineering synthetic microbial consortia for biotechnology development. However, there are relatively few reports of their use in real-world applications, and achieving population stability and regulation has proven to be challenging. In this work, we bridge ecology theory with engineering principles to develop robust synthetic fungal-bacterial consortia for efficient biosynthesis of valuable products from lignocellulosic feedstocks. The required biological functions are divided between two specialists: the fungus Trichoderma reesei, which secretes cellulase enzymes to hydrolyze lignocellulosic biomass into soluble saccharides, and the bacterium Escherichia coli, which metabolizes soluble saccharides into desired products. We developed and experimentally validated a comprehensive mathematical model for T. reesei/E. coli consortia, providing insights on key determinants of the system's performance. To illustrate the bioprocessing potential of this consortium, we demonstrate direct conversion of microcrystalline cellulose and pretreated corn stover to isobutanol. Without costly nutrient supplementation, we achieved titers up to 1.88 g/L and yields up to 62% of theoretical maximum. In addition, we show that cooperator-cheater dynamics within T. reesei/E. coli consortia lead to stable population equilibria and provide a mechanism for tuning composition. Although we offer isobutanol production as a proof-of-concept application, our modular system could be readily adapted for production of many other valuable biochemicals.

Fibrillar assembly of bacterial cellulose in the presence of wood-based hemicelluloses.

Science.gov (United States)

Penttilä, Paavo A; Imai, Tomoya; Sugiyama, Junji

2017-09-01

Composite materials mimicking the plant cell wall structure were made by culturing cellulose-producing bacteria together with secondary-wall hemicelluloses from wood. The effects of spruce galactoglucomannan (GGM) and beech xylan on the nanoscale morphology of bacterial cellulose were studied in the original, hydrated state with small-angle X-ray scattering (SAXS). The SAXS intensities were fitted with a model covering multiple levels of the hierarchical structure. Additional information on the structure of dried samples was obtained using scanning and transmission electron microscopy and infra-red spectroscopy. Both hemicelluloses induced a partial conversion of the cellulose crystal structure from I α to I β and a reduction of the cross-sectional dimensions of the cellulose microfibrils, thereby affecting also their packing into bundles. The differences were more pronounced in samples with xylan instead of GGM, and they became more significant with higher hemicellulose concentrations. Copyright © 2017 Elsevier B.V. All rights reserved.

Production of bacterial cellulose and enzyme from waste fiber sludge

Science.gov (United States)

2013-01-01

Background Bacterial cellulose (BC) is a highly crystalline and mechanically stable nanopolymer, which has excellent potential as a material in many novel applications, especially if it can be produced in large amounts from an inexpensive feedstock. Waste fiber sludge, a residue with little or no value, originates from pulp mills and lignocellulosic biorefineries. A high cellulose and low lignin content contributes to making the fiber sludge suitable for bioconversion, even without a thermochemical pretreatment step. In this study, the possibility to combine production of BC and hydrolytic enzymes from fiber sludge was investigated. The BC was characterized using field-emission scanning electron microscopy and X-ray diffraction analysis, and its mechanical properties were investigated. Results Bacterial cellulose and enzymes were produced through sequential fermentations with the bacterium Gluconacetobacter xylinus and the filamentous fungus Trichoderma reesei. Fiber sludges from sulfate (SAFS) and sulfite (SIFS) processes were hydrolyzed enzymatically without prior thermochemical pretreatment and the resulting hydrolysates were used for BC production. The highest volumetric yields of BC from SAFS and SIFS were 11 and 10 g/L (DW), respectively. The BC yield on initial sugar in hydrolysate-based medium reached 0.3 g/g after seven days of cultivation. The tensile strength of wet BC from hydrolysate medium was about 0.04 MPa compared to about 0.03 MPa for BC from a glucose-based reference medium, while the crystallinity was slightly lower for BC from hydrolysate cultures. The spent hydrolysates were used for production of cellulase with T. reesei. The cellulase activity (CMCase activity) in spent SAFS and SIFS hydrolysates reached 5.2 U/mL (87 nkat/mL), which was similar to the activity level obtained in a reference medium containing equal amounts of reducing sugar. Conclusions It was shown that waste fiber sludge is a suitable raw material for production of

An XRPD and EPR spectroscopy study of microcrystalline calcite bioprecipitated by Bacillus subtilis

Science.gov (United States)

Perito, B.; Romanelli, M.; Buccianti, A.; Passaponti, M.; Montegrossi, G.; Di Benedetto, F.

2018-05-01

We report in this study the first XRPD and EPR spectroscopy characterisation of a biogenic calcite, obtained from the activity of the bacterium Bacillus subtilis. Microcrystalline calcite powders obtained from bacterial culture in a suitable precipitation liquid medium were analysed without further manipulation. Both techniques reveal unusual parameters, closely related to the biological source of the mineral, i.e., to the bioprecipitation process and in particular to the organic matrix observed inside calcite. In detail, XRPD analysis revealed that bacterial calcite has slightly higher c/a lattice parameters ratio than abiotic calcite. This correlation was already noticed in microcrystalline calcite samples grown by bio-mineralisation processes, but it had never been previously verified for bacterial biocalcites. EPR spectroscopy evidenced an anomalously large value of W 6, a parameter that can be linked to occupation by different chemical species in the next nearest neighbouring sites. This parameter allows to clearly distinguish bacterial and abiotic calcite. This latter achievement was obtained after having reduced the parameters space into an unbiased Euclidean one, through an isometric log-ratio transformation. We conclude that this approach enables the coupled use of XRPD and EPR for identifying the traces of bacterial activity in fossil carbonate deposits.

Influence of the crystalline structure of cellulose on the production of ethanol from lignocellulose biomass

Science.gov (United States)

Smuga-Kogut, Małgorzata; Zgórska, Kazimiera; Szymanowska-Powałowska, Daria

2016-01-01

In recent years, much attention has been devoted to the possibility of using lignocellulosic biomass for energy. Bioethanol is a promising substitute for conventional fossil fuels and can be produced from straw and wood biomass. Therefore, the aim of this paper was to investigate the effect of 1-ethyl-3-methylimidazolium pretreatment on the structure of cellulose and the acquisition of reducing sugars and bioethanol from cellulosic materials. Material used in the study was rye straw and microcrystalline cellulose subjected to ionic liquid 1-ethyl-3-methylimidazolium pretreatment. The morphology of cellulose fibres in rye straw and microcrystalline cellulose was imaged prior to and after ionic liquid pretreatment. Solutions of ionic liquid-treated and untreated cellulosic materials were subjected to enzymatic hydrolysis in order to obtain reducing sugars, which constituted a substrate for alcoholic fermentation. An influence of the ionic liquid on the cellulose structure, accumulation of reducing sugars in the process of hydrolysis of this material, and an increase in ethanol amount after fermentation was observed. The ionic liquid did not affect cellulolytic enzymes negatively and did not inhibit yeast activity. The amount of reducing sugars and ethyl alcohol was higher in samples purified with 1-ethyl-3-methy-limidazolium acetate. A change in the supramolecular structure of cellulose induced by the ionic liquid was also observed.

Synthesis of flexible magnetic nanohybrid based on bacterial cellulose under ultrasonic irradiation

International Nuclear Information System (INIS)

Zheng, Yi; Yang, Jingxuan; Zheng, Weili; Wang, Xiao; Xiang, Cao; Tang, Lian; Zhang, Wen; Chen, Shiyan; Wang, Huaping

2013-01-01

Flexible magnetic membrane based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of the Fe 3 O 4 nanoparticles under different conditions and its properties were characterized. The results demonstrated that the Fe 3 O 4 nanoparticles coated with PEG were well homogeneously dispersed in the BC matrix under ultrasonic irradiation with the saturation magnetization of 40.58 emu/g. Besides that, the membranes exhibited the striking flexibility and mechanical properties. This study provided a green and facile method to inhibit magnetic nanoparticle aggregation without compromising the mechanical properties of the nanocomposites. Magnetically responsive BC membrane would have potential applications in electronic actuators, information storage, electromagnetic shielding coating and anti-counterfeit. - Highlights: ► Flexible magnetic film is prepared by in situ synthesis on bacterial cellulose. ► Ultrasound and PEG are used together to inhibit the nanoparticle aggregation. ► The magnetic membrane demonstrates the great superparamagnetic behavior

Size- and dose-dependent toxicity of cellulose nanocrystals (CNC) on human fibroblasts and colon adenocarcinoma.

Science.gov (United States)

Hanif, Zahid; Ahmed, Farrukh R; Shin, Seung Won; Kim, Young-Kee; Um, Soong Ho

2014-07-01

A controlled preparation of cellulose nanocrystals of different sizes and shapes has been carried out by acid hydrolysis of microcrystalline cellulose. The size- and concentration-dependent toxicity effects of the resulting cellulose nanocrystals were evaluated against two different cell lines, NIH3T3 murine embryo fibroblasts and HCT116 colon adenocarcinoma. It could serve as a therapeutic platform for cancer treatment. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, characterization and adsorption properties of microcrystalline cellulose based nanogel for dyes and heavy metals removal.

Science.gov (United States)

El-Naggar, Mehrez E; Radwan, Emad K; El-Wakeel, Shaimaa T; Kafafy, Hany; Gad-Allah, Tarek A; El-Kalliny, Amer S; Shaheen, Tharwat I

2018-07-01

Recently, naturally occurring biopolymers have attracted the attention as potential adsorbents for the removal of water contaminants. In this work, we present the development of microcrystalline cellulose (MCC)-based nanogel grafted with acrylamide and acrylic acid in the presence of methylene bisacrylamide and potassium persulphate as a crosslinking agent and initiator, respectively. World-class facilities such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), surface analysis, field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and zeta sizer were used to characterize the synthesized MCC based nanogel. The prepared nanogel was applied to remove reactive red 195 (RR195) dye and Cd (II) from aqueous medium at different operational conditions. The adsorption experiments showed that the feed concentration of monomers has a significant effect on the removal of RR195 which peaked (93% removal) after 10min of contact time at pH2 and a dose of 1.5g/L. On contrary, the feed concentration has insignificant effect on the removal of Cd (II) which peaked (97% removal) after 30min of contact time at pH6 and a dose of 0.5g/L. The adsorption equilibrium data of RR195 and Cd (II) was best described by Freundlich and Langmuir, respectively. Conclusively, the prepared MCC based nanogels were proved as promising adsorbents for the removal of organic pollutants as well as heavy metals. Copyright © 2018 Elsevier B.V. All rights reserved.

The Disintegration Process in Microcrystalline Cellulose Based Tablets, Part 1: Influence of Temperature, Porosity and Superdisintegrants

Science.gov (United States)

Yassin, Samy; Goodwin, Daniel J; Anderson, Andrew; Sibik, Juraj; Wilson, D Ian; Gladden, Lynn F; Zeitler, J Axel

2015-01-01

Disintegration performance was measured by analysing both water ingress and tablet swelling of pure microcrystalline cellulose (MCC) and in mixture with croscarmellose sodium using terahertz pulsed imaging (TPI). Tablets made from pure MCC with porosities of 10% and 15% showed similar swelling and transport kinetics: within the first 15 s, tablets had swollen by up to 33% of their original thickness and water had fully penetrated the tablet following Darcy flow kinetics. In contrast, MCC tablets with a porosity of 5% exhibited much slower transport kinetics, with swelling to only 17% of their original thickness and full water penetration reached after 100 s, dominated by case II transport kinetics. The effect of adding superdisintegrant to the formulation and varying the temperature of the dissolution medium between 20°C and 37°C on the swelling and transport process was quantified. We have demonstrated that TPI can be used to non-invasively analyse the complex disintegration kinetics of formulations that take place on timescales of seconds and is a promising tool to better understand the effect of dosage form microstructure on its performance. By relating immediate-release formulations to mathematical models used to describe controlled release formulations, it becomes possible to use this data for formulation design. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3440–3450, 2015 PMID:26073446

Box-Behnken experimental design for chromium(VI) ions removal by bacterial cellulose-magnetite composites.

Science.gov (United States)

Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin Ion; Mihalache, Nicoleta; Botez, Adriana; Matei, Cristian; Berger, Daniela; Damian, Celina Maria; Ionita, Valentin

2016-10-01

In this study bacterial cellulose-magnetite composites were synthesised for the removal of chromium(VI) from aqueous solutions. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis and X-ray Photoelectron Spectroscopy (XPS) were used to characterize the bacterial cellulose-magnetite composites and to reveal the uniform dispersion of nanomagnetite in the BC matrix. Magnetic properties were also measured to confirm the magnetite immobilization on bacterial cellulose membrane. The effects of initial Cr(VI) concentration, solution pH and solid/liquid ratio upon chromium removal were examined using the statistical Box-Behnken Design. Because of the possibility of magnetite dissolution during chromium(VI) adsorption, the degree of iron leaching was also analysed in the same conditions as Cr(VI) adsorption. From the factors affecting chromium(VI) adsorption the most important was solution pH. The highest Cr(VI) removal efficiency was observed at pH 4, accompanied by the lowest iron leaching in the solution. The adsorption experiments also indicated that the adsorption process of chromium(VI) is well described by Freundlich adsorption model. Our results proved that the BC-magnetite composites could be used for an efficient removal of chromium(VI) from diluted solutions with a minimum magnetite dissolution during operation. Copyright © 2016 Elsevier B.V. All rights reserved.

Screening of Acetic Acid Bacteria from Pineapple Waste for Bacterial Cellulose Production using Sago Liquid Waste

Directory of Open Access Journals (Sweden)

Nur Arfa Yanti

2017-12-01

Full Text Available Bacterial cellulose is a biopolymer produced by fermentation process with the help of bacteria. It has numerous applications in industrial sector with its characteristic as a biodegradable and nontoxic compound in nature. The potential application of BC is limited by its production costs, because BC is produced from expensive culture media. The use of cheap carbon and nutrient sources such as sago liquid waste is an interesting strategy to overcome this limitation. The objective of this study was to obtain the AAB strain that capable to produce bacterial cellulose from sago liquid waste. Isolation of AAB strains was conducted using CARR media and the screening of BC production was performed on Hestrin-Schramm (HS media with glucose as a carbon source. The strains of AAB then were evaluated for their cellulose-producing capability using sago liquid waste as a substrate. Thirteen strains of AAB producing BC were isolated from pineapple waste (pineapple core and peel and seven of them were capable to produce BC using sago liquid waste substrate. One of the AAB strains produced a relatively high BC, i.e. isolate LKN6. The result of morphological and biochemical test was proven that the bacteria was Acetobacter xylinum. The result of this study showed that A. xylinum LKN6 can produce a high yield of BC, therefore this strain is potentially useful for its utilization as a starter in bacterial cellulose production. 

Synthesis of thermoplastic starch-bacterial cellulose nanocomposites via in situ fermentation

OpenAIRE

Osorio, Marlon A.; Restrepo, David; Velásquez-Cock, Jorge A.; Zuluaga, Robin O.; Montoya, Ursula; Rojas, Orlando; Gañán, Piedad F.; Marin, Diana; Castro, Cristina I.

2014-01-01

In this paper, a nanocomposite based on thermoplastic starch (TPS) reinforced with bacterial cellulose (BC) nanoribbons was synthesized by in situ fermentation and chemical crosslinking. BC nanoribbons were produced by a Colombian native strain of Gluconacetobacter medellinensis; the nanocomposite was plasticized with glycerol and crosslinked with citric acid. The reinforcement percentage in the nanocomposites remained constant throughout the fermentation time because of the TPS absorption ca...

Use of agroindustrial waste in the preparation of nanocomposites based on bacterial cellulose and hydroxyapatite

International Nuclear Information System (INIS)

Duarte, Eden B.; Chagas, Bruna S. das; Feitosa, Judith P.A.; Andrade, Fabia K.; Borges, Maria F.; Muniz, Celli R.; Souza Filho, Men de Sa M.; Rosa, Morsyleide F.; Brigida, Ana I.; Morais, Joao P.S.

2015-01-01

Environmental issues have supported the interest in renewable sources and agroindustrial residues became a significant resource for the production of new materials. The present work presents the use of agroindustrial residues to obtain bacterial cellulose (BC) for further elaboration of nanocomposites with hydroxyapatite (HA). The production of BC membranes occurred in Hestrin & Schramm medium, cashew juice and sisal liquid waste cultivated under static conditions. After the incubation period, the BC membranes were purified and nanocomposites prepared by successive immersion of the purified membranes in solutions of Calcium Chloride (CaCl_2), and Sodium Phosphate (Na_2HPO_4), followed by drying and subsequent characterization. The materials obtained were characterized by Thermogravimetric Analysis (TGA) and X-ray Diffraction (XRD). Additionally, in vitro tests were performed for nanocomposites. The results showed the production of cellulose from the three substrates studied, without the need for further supplementation or pH change. In all characterizations, structure and typical behavior of bacterial cellulose were found. The composites showed bioactivity and the adsorption capacity of proteins, which lead to potential biocompatibility of these materials. (author)

The Disintegration Process in Microcrystalline Cellulose Based Tablets, Part 1: Influence of Temperature, Porosity and Superdisintegrants.

Science.gov (United States)

Yassin, Samy; Goodwin, Daniel J; Anderson, Andrew; Sibik, Juraj; Wilson, D Ian; Gladden, Lynn F; Zeitler, J Axel

2015-10-01

Disintegration performance was measured by analysing both water ingress and tablet swelling of pure microcrystalline cellulose (MCC) and in mixture with croscarmellose sodium using terahertz pulsed imaging (TPI). Tablets made from pure MCC with porosities of 10% and 15% showed similar swelling and transport kinetics: within the first 15 s, tablets had swollen by up to 33% of their original thickness and water had fully penetrated the tablet following Darcy flow kinetics. In contrast, MCC tablets with a porosity of 5% exhibited much slower transport kinetics, with swelling to only 17% of their original thickness and full water penetration reached after 100 s, dominated by case II transport kinetics. The effect of adding superdisintegrant to the formulation and varying the temperature of the dissolution medium between 20°C and 37°C on the swelling and transport process was quantified. We have demonstrated that TPI can be used to non-invasively analyse the complex disintegration kinetics of formulations that take place on timescales of seconds and is a promising tool to better understand the effect of dosage form microstructure on its performance. By relating immediate-release formulations to mathematical models used to describe controlled release formulations, it becomes possible to use this data for formulation design. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 104:3440-3450, 2015. © 2015 The Authors. Journal of Pharmaceutical Sciences published by Wiley Periodicals, Inc. and the American Pharmacists Association.

Sonication reduces the attachment of Salmonella Typhimurium ATCC 14028 cells to bacterial cellulose-based plant cell wall models and cut plant material.

Science.gov (United States)

Tan, Michelle S F; Rahman, Sadequr; Dykes, Gary A

2017-04-01

This study investigated the removal of bacterial surface structures, particularly flagella, using sonication, and examined its effect on the attachment of Salmonella Typhimurium ATCC 14028 cells to plant cell walls. S. Typhimurium ATCC 14028 cells were subjected to sonication at 20 kHz to remove surface structures without affecting cell viability. Effective removal of flagella was determined by staining flagella of sonicated cells with Ryu's stain and enumerating the flagella remaining by direct microscopic counting. The attachment of sonicated S. Typhimurium cells to bacterial cellulose-based plant cell wall models and cut plant material (potato, apple, lettuce) was then evaluated. Varying concentrations of pectin and/or xyloglucan were used to produce a range of bacterial cellulose-based plant cell wall models. As compared to the non-sonicated controls, sonicated S. Typhimurium cells attached in significantly lower numbers (between 0.5 and 1.0 log CFU/cm 2 ) to all surfaces except to the bacterial cellulose-only composite without pectin and xyloglucan. Since attachment of S. Typhimurium to the bacterial cellulose-only composite was not affected by sonication, this suggests that bacterial surface structures, particularly flagella, could have specific interactions with pectin and xyloglucan. This study indicates that sonication may have potential applications for reducing Salmonella attachment during the processing of fresh produce. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of Electron-Beam Irradiation on Bacterial Cellulose Membranes Used as Transdermal Drug Delivery Systems

International Nuclear Information System (INIS)

Stoica-Guzun, A.

2006-01-01

Multiple methods are used to modify material surfaces. Radiation is an effective tool for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. Bacterial cellulose is a promising biomaterial synthesized by Acetobacter xylinum. It has a distinctive ultrafine reticulated structure that may become a perfect matrix as an optimal wound healing environment. In this work, high energy irradiation (γ rays from 137 C s) was applied to modify bacterial cellulose membranes. The effect of varying irradiation doses on membranes permeability was studied. Tetracycline was involved in the study of diffusivity as model drug. Release and permeation of drug from irradiated and non-irradiated membranes were done using a diffusion cell. The membrane permeability was determined using a psudo-steady state analysis based on Fick's law

Immobilization of collagen peptide on dialdehyde bacterial cellulose nanofibers via covalent bonds for tissue engineering and regeneration

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Wen XX

2015-07-01

Full Text Available Xiaoxiao Wen,1 Yudong Zheng,1 Jian Wu,2 Lu-Ning Wang,1 Zhenya Yuan,1 Jiang Peng,3 Haoye Meng3 1School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, People’s Republic of China; 2Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Soochow, People’s Republic of China; 3Institute of Orthopedics, Chinese PLA General Hospital, Beijing, People’s Republic of China Abstract: Bacterial cellulose (BC is an alternative nanostructured biomaterial to be utilized for a wide range of biomedical applications. Because of its low bioactivity, which restricted its practical application, collagen and collagen hydrolysate were usually composited into BC. It is necessary to develop a new method to generate covalent bonds between collagen and cellulose to improve the immobilization of collagen on BC. This study describes a facile dialdehyde BC/collagen peptide nanocomposite. BC was oxidized into dialdehyde bacterial cellulose (DBC by regioselective oxidation, and then composited with collagen peptide (Col-p via covalent bonds to form Schiff’s base type compounds, which was demonstrated by the results of microstructures, contact angle, Col-p content, and peptide-binding ratio. The peptide-binding ratio was further affected by the degree of oxidation, pH value, and zeta potential. In vitro desorption measurement of Col-p suggested a controlled release mechanism of the nanocomposite. Cell tests indicated that the prepared DBC/Col-p composite was bioactive and suitable for cell adhesion and attachment. This work demonstrates that the DBC/Col-p composite is a promising material for tissue engineering and regeneration. Keywords: bacterial cellulose, dialdehyde cellulose, collagen peptide, composite materials, cytoactivity 

New thermophilic anaerobes that decompose crystalline cellulose

Energy Technology Data Exchange (ETDEWEB)

Taya, M; Hinoki, H; Suzuki, Y; Yagi, T; Yap, M G.S.; Kobayashi, T

1985-01-01

Two strains (designated as 25A and 3B) of cellulolytic, thermophilic, anaerobic, spore-forming bacteria were newly isolated from an alkaline hot spring through enrichment cultures at 60/sup 0/C. Though strain 25A was nearly identical to Clostridium thermocellum ATCC 27405 as a reference strain, strain 3B had some characteristics different from the reference; no flagellation, alkalophilic growth property (optimum pH of 7.5-8) and orange-colored pigmentation of the cell mass. Strain 3B effectively decomposed micro-crystalline cellulose (Avicel) and raw cellulosics (rice straw, newspaper, and bagasse) without physical or chemical pretreatments. 20 references, 2 figures, 2 tables.

Influence of Cellulose on the Mechanical and Thermal Stability of ABS Plastic Composites

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K. Crews

2016-01-01

Full Text Available Microcrystalline cellulose was explored as possible biodegradable fillers in the fabrication of ABS plastic composites. TGA indicates that upon inclusion of cellulose microcrystals the thermal stability of the ABS plastics was improved significantly when compared to the neat ABS plastic counterparts. Furthermore, inclusion of extracted cellulose from plant biomass showed a higher thermal stability with maximum decomposition temperatures around 131.95°C and 124.19°C for cellulose from cotton and Hibiscus sabdariffa, respectively, when compared to that of the purchased cellulose. In addition, TMA revealed that the average CTE value for the neat ABS and 1 : 1 ratio of cellulose to ABS fabricated in this study was significantly lower than the reported CTE (ca. 73.8 μm/m°C.

Exploring the potential of polacrilin potassium as a novel superdisintegrant in microcrystalline cellulose based pellets prepared by extrusion-spheronization

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Amita K Joshi

2011-01-01

Full Text Available Polacrilin potassium (PP, an ion exchange resin, was used as a superdisintegrant to improve the dissolution of rifampicin, from microcrystalline cellulose (MCC based pellets prepared by extrusion-spheronization. Production of fast release pellets by extrusion-spheronization using MCC is a complicated process. In the present study, pellets were prepared containing 50% w/w rifampicin (BCS class II drug and 40% w/w MCC as extrusion-spheronization aid. Different levels of PP and lactose ratio investigated were 0:10, 2:8, 4:6, 6:4, 8:2, and 10:0. Pellets were evaluated for yield, size, size distribution, shape, porosity, friability, residual moisture, and dissolution efficiency (DE at 30 minutes. Incorporation of this novel superdisintegrant had no adverse effect on the mechanical and micromeritic characteristics of pellets. All the batches of pellets showed high yields′, ~90%; narrow particle size distribution; aspect ratio, 1.0-1.1; friability, <1%; and porosity, 45.51-49.84%. Dissolution profiles were compared using model-independent approaches; DE and similarity factor, f 2 . Addition of Polacrilin results in significant improvement in the DE of rifampicin. The dissolution profiles were significantly different from the dissolution profile of pellets formulated without PP. This preliminary study indicates that PP can serve as an effective superdisintegrant in MCC pellets prepared by extrusion-spheronization.

Water-induced charge transport in tablets of microcrystalline cellulose of varying density: dielectric spectroscopy and transient current measurements

International Nuclear Information System (INIS)

Nilsson, Martin; Alderborn, Goeran; Stroemme, Maria

2003-01-01

Room temperature dielectric frequency response data taken over 13 decades in frequency on microcrystalline cellulose (MCC) tablets of varying density are presented. The frequency response shows on three different processes: the first one is a high-frequency relaxation process whose magnitude increases and reaches a plateau as the tablet density increases. This process is associated with orientational motions of local chain segments via glycosidic bonds. The second relaxation process, related to the presence of water in the MCC matrix, is insensitive to changes in tablet density. At lower frequencies, dc-like imperfect charge transport dominates the dielectric spectrum. The dc conductivity was found to decrease with increasing tablet density and increase exponentially with increasing humidity. Transient current measurements indicated that two different ionic species, protons and OH - ions, lied behind the observed conductivity. At ambient humidity of 22%, only one in a billion of the water molecules present in the tablet matrix participated in long range dc conduction. The diffusion coefficient of the protons and OH - ions were found to be of the order of 10 -9 cm 2 /s, which is the same as for small salt building ions in MCC. This shows that ionic drugs leaving a tablet matrix may diffuse in the same manner as the constituent ions of water and, thus, elucidates the necessity to understand the water transport properties of excipient materials to be able to tailor the drug release process from pharmaceutical tablets

High alkaline tolerant electrolyte membrane with improved conductivity and mechanical strength via lithium chloride/dimethylacetamide dissolved microcrystalline cellulose for Zn-Air batteries

International Nuclear Information System (INIS)

Zhang, Yuansong; Li, Cong; Cai, Xiaoxia; Yao, Jinshui; Li, Mei; Zhang, Xian; Liu, Qinze

2016-01-01

LiCl/DMAc (dimethylacetamide) solution dissolved microcrystalline cellulose (LD-MCC) showed potential benefits to the alkaline solid polymer electrolyte (ASPE). High alkali tolerance (up to 70 wt% KOH loading), remarkable improvements in ionic conductivity (from 0.018 S cm −1 to 0.153 S cm −1 ) and mechanical properties (3-fold increase in tensile strength from 0.28 MPa to 0.76 MPa) were achieved just via an incorporation of 5 wt% of LD-MCC into the ASPE matrix. Wide-angle X-ray diffraction indicated that LD-MCC entrapped KOH and hindered its aggregation. X-ray Energy Dispersive Spectrometer revealed that K + was preferentially located on the LD-MCC surfaces rather than the polymeric matrix. Scanning Electron Microscopy of freeze-dry sample demonstrated a submicro-porous morphology with reduced average pore size (175 nm) after the incorporation of LD-MCC in ASPE matrix. The incorporated LD-MCC acted as KOH stabilizer, hydrophilicity agent and OH − transport media. Distinct micro-structures before and after the incorporation of LD-MCC were investigated to reveal the special role of LD-MCC in the performance improvement of ASPE membrane.

Bacterial cellulose membrane as flexible substrate for organic light emitting devices

International Nuclear Information System (INIS)

Legnani, C.; Vilani, C.; Calil, V.L.; Barud, H.S.; Quirino, W.G.; Achete, C.A.; Ribeiro, S.J.L.; Cremona, M.

2008-01-01

Bacterial cellulose (BC) membranes produced by gram-negative, acetic acid bacteria (Gluconacetobacter xylinus), were used as flexible substrates for the fabrication of Organic Light Emitting Diodes (OLED). In order to achieve the necessary conductive properties indium tin oxide (ITO) thin films were deposited onto the membrane at room temperature using radio frequency (r.f.) magnetron sputtering with an r.f. power of 30 W, at pressure of 8 mPa in Ar atmosphere without any subsequent thermal treatment. Visible light transmittance of about 40% was observed. Resistivity, mobility and carrier concentration of deposited ITO films were 4.90 x 10 -4 Ohm cm, 8.08 cm 2 /V-s and - 1.5 x 10 21 cm -3 , respectively, comparable with commercial ITO substrates. In order to demonstrate the feasibility of devices based on BC membranes three OLEDs with different substrates were produced: a reference one with commercial ITO on glass, a second one with a SiO 2 thin film interlayer between the BC membrane and the ITO layer and a third one just with ITO deposited directly on the BC membrane. The observed OLED luminance ratio was: 1; 0.5; 0.25 respectively, with 2400 cd/m 2 as the value for the reference OLED. These preliminary results show clearly that the functionalized biopolymer, biodegradable, biocompatible bacterial cellulose membranes can be successfully used as substrate in flexible organic optoelectronic devices

Assessing the loading and release of metronidazole from bacterial cellulose film as a pharmaceutical dressing

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Mohammad Ali Salehi

2017-08-01

Full Text Available Background: Bacterial cellulose membrane (BCM produced by Gluconacetobacter xylinus is an advantageous bacterial product and because of its unique properties could be used as an ideal dressing. The aim of this study was to consider the capability of this biomaterial in the release of Metronidazole. In the case of proving this capability, it provides the basis for the production of a dressing containing this type of antibiotic. Materials and Methods: In this study, BCM was initially synthesized by Gluconacetobacter xylinus. The BCM was loaded by Metronidazole. Then the release process was considered in distilled water and buffer phosphate Saline. The ultra violet spectrophotometry was applied for measuring the concentration of the released drug. Results: The chemical structure of bacterial cellulose was confirmed by Fourier Transform Infrared (FT-IR spectroscopy. The release of Metronidazole in distilled water and phosphate buffered Saline was reached to 84.27% and 84.71%, respectively. Due to higher release in phosphate buffered Saline media, it seems that the trend of release in vitro provides efficient results. Conclusion: Results of this study provides the basis for future research on supplying an ideal dressing from this microbial product.

Bacterial Cellulose Membranes Used as Artificial Substitutes for Dural Defection in Rabbits

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Chen Xu

2014-06-01

Full Text Available To improve the efficacy and safety of dural repair in neurosurgical procedures, a new dural material derived from bacterial cellulose (BC was evaluated in a rabbit model with dural defects. We prepared artificial dura mater using bacterial cellulose which was incubated and fermented from Acetobacter xylinum. The dural defects of the rabbit model were repaired with BC membranes. All surgeries were performed under sodium pentobarbital anesthesia, and all efforts were made to minimize suffering. All animals were humanely euthanized by intravenous injection of phenobarbitone, at each time point, after the operation. Then, the histocompatibility and inflammatory effects of BC were examined by histological examination, real-time fluorescent quantitative polymerase chain reaction (PCR and Western Blot. BC membranes evenly covered the surface of brain without adhesion. There were seldom inflammatory cells surrounding the membrane during the early postoperative period. The expression of inflammatory cytokines IL-1β, IL-6 and TNF-α as well as iNOS and COX-2 were lower in the BC group compared to the control group at 7, 14 and 21 days after implantation. BC can repair dural defects in rabbit and has a decreased inflammatory response compared to traditional materials. However, the long-term effects need to be validated in larger animals.

Prevalence and trends of cellulosics in pharmaceutical dosage forms.

Science.gov (United States)

Mastropietro, David J; Omidian, Hossein

2013-02-01

Many studies have shown that cellulose derivatives (cellulosics) can provide various benefits when used in virtually all types of dosage forms. Nevertheless, the popularity of their use in approved drug products is rather unknown. This research reports the current prevalence and trends of use for 15 common cellulosics in prescription drug products. The cellulosics were powdered and microcrystalline cellulose (MCC), ethyl cellulose, hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC), hypromellose (HPMC), HPMC phthalate, HPMC acetate succinate, cellulose acetate (CA), CA phthalate, sodium (Na) and calcium (Ca) carboxymethylcellulose (CMC), croscarmellose sodium (XCMCNa), methyl cellulose, and low substituted HPC. The number of brand drug products utilizing each cellulosics was determined using the online drug index Rxlist. A total of 607 brand products were identified having one or more of the cellulosics as an active or inactive ingredient. An array of various dosage forms was identified and revealed HPMC and MCC to be the most utilized cellulosics in all products followed by XCMCNa and HPC. Many products contained two or more cellulosics in the formulation (42% containing two, 23% containing three, and 4% containing 4-5). The largest combination occurrence was HPMC with MCC. The use of certain cellulosics within different dosage form types was found to contain specific trends. All injectables utilized only CMCNa, and the same with all ophthalmic solutions utilizing HPMC, and otic suspensions utilizing HEC. Popularity and trends regarding cellulosics use may occur based on many factors including functionality, safety, availability, stability, and ease of manufacturing.

In vitro evaluation of osteoblastic cells on bacterial cellulose modified with multi-walled carbon nanotubes as scaffold for bone regeneration

Energy Technology Data Exchange (ETDEWEB)

Gutiérrez-Hernández, José Manuel [Coordination for Innovation and Application of Science and Technology, Autonomous University San Luis Potosi, 78000 San Luis Potosi (Mexico); Department of Wood, Cellulose and Paper Research, University Guadalajara, 45110 Guadalajara (Mexico); Escobar-García, Diana María [Laboratory of Basic Sciences, Faculty of Dentistry, Autonomous University San Luis Potosi, 78000 San Luis Potosi (Mexico); Escalante, Alfredo [Department of Wood, Cellulose and Paper Research, University Guadalajara, 45110 Guadalajara (Mexico); Flores, Hector [Laboratory of Basic Sciences, Faculty of Dentistry, Autonomous University San Luis Potosi, 78000 San Luis Potosi (Mexico); González, Francisco Javier [Coordination for Innovation and Application of Science and Technology, Autonomous University San Luis Potosi, 78000 San Luis Potosi (Mexico); Gatenholm, Paul [Chalmers University of Technology, Department of Chemistry and Chemical Engineering, Biopolymer Technology, SE-412 96 Göteborg (Sweden); Toriz, Guillermo, E-mail: gtoriz@dmcyp.cucei.udg.mx [Department of Wood, Cellulose and Paper Research, University Guadalajara, 45110 Guadalajara (Mexico); Chalmers University of Technology, Department of Chemistry and Chemical Engineering, Biopolymer Technology, SE-412 96 Göteborg (Sweden)

2017-06-01

In this paper we explore the use of native bacterial cellulose (BC) in combination with functionalized multi-walled carbon nanotubes (MWNTs) as an original biomaterial, suitable three-dimensional (3D) scaffold for osteoblastic cell culture. Functionalized MWNTs were mixed with native BC (secreted by Gluconacetobacter xylinus) with the aim of reinforcing the mechanical properties of BC. The results indicate that BC-MWNTs scaffolds support osteoblast viability, adhesion and proliferation at higher levels as compared to traditional culture substrates. Chemically functionalized MWNTs are also an excellent material to be used as scaffold because these did not affect cell viability and showed an enhanced osteoblast adhesion. These results suggest the potential for this combination of biomaterials, i.e. BC and carbon nanomaterials, as scaffolds for bone regeneration. - Highlights: • Functionalization of multiwalled carbon nanotubes with carboxyl groups for reduces their toxicity against osteoblastic cells. • Use of native bacterial cellulose with functionalized multi-walled carbon nanotubes as scaffolds for tissue engineering. • Bacterial cellulose with multi-walled carbon nanotubes as scaffolds give an excellent option to be used in bone regeneration.

In vitro evaluation of osteoblastic cells on bacterial cellulose modified with multi-walled carbon nanotubes as scaffold for bone regeneration

International Nuclear Information System (INIS)

Gutiérrez-Hernández, José Manuel; Escobar-García, Diana María; Escalante, Alfredo; Flores, Hector; González, Francisco Javier; Gatenholm, Paul; Toriz, Guillermo

2017-01-01

In this paper we explore the use of native bacterial cellulose (BC) in combination with functionalized multi-walled carbon nanotubes (MWNTs) as an original biomaterial, suitable three-dimensional (3D) scaffold for osteoblastic cell culture. Functionalized MWNTs were mixed with native BC (secreted by Gluconacetobacter xylinus) with the aim of reinforcing the mechanical properties of BC. The results indicate that BC-MWNTs scaffolds support osteoblast viability, adhesion and proliferation at higher levels as compared to traditional culture substrates. Chemically functionalized MWNTs are also an excellent material to be used as scaffold because these did not affect cell viability and showed an enhanced osteoblast adhesion. These results suggest the potential for this combination of biomaterials, i.e. BC and carbon nanomaterials, as scaffolds for bone regeneration. - Highlights: • Functionalization of multiwalled carbon nanotubes with carboxyl groups for reduces their toxicity against osteoblastic cells. • Use of native bacterial cellulose with functionalized multi-walled carbon nanotubes as scaffolds for tissue engineering. • Bacterial cellulose with multi-walled carbon nanotubes as scaffolds give an excellent option to be used in bone regeneration.

In situ synthesis of silver-nanoparticles/bacterial cellulose composites for slow-released antimicrobial wound dressing.

Science.gov (United States)

Wu, Jian; Zheng, Yudong; Song, Wenhui; Luan, Jiabin; Wen, Xiaoxiao; Wu, Zhigu; Chen, Xiaohua; Wang, Qi; Guo, Shaolin

2014-02-15

Bacterial cellulose has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity, which is one of critical skin-barrier functions in wound healing. To overcome such deficiency, we developed a novel method to synthesize and impregnate silver nanoparticles on to bacterial cellulose nanofibres (AgNP-BC). Uniform spherical silver nano-particles (10-30 nm) were generated and self-assembled on the surface of BC nano-fibers, forming a stable and evenly distributed Ag nanoparticles coated BC nanofiber. Such hybrid nanostructure prevented Ag nanoparticles from dropping off BC network and thus minimized the toxicity of nanoparticles. Regardless the slow Ag(+) release, AgNP-BC still exhibited significant antibacterial activities with more than 99% reductions in Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, AgNP-BC allowed attachment and growth of epidermal cells with no cytotoxicity emerged. The results demonstrated that AgNP-BC could reduce inflammation and promote wound healing. Copyright © 2013 Elsevier Ltd. All rights reserved.

Cytotoxicity and Acute Gastrointestinal Toxicity of Bacterial Cellulose-Poly (acrylamide-sodium acrylate Hydrogel: A Carrier for Oral Drug Delivery

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Manisha Pandey 1,2 * , Hira Choudhury 1, Mohd Cairul Iqbal Mohd Amin 2

2016-12-01

Full Text Available Background: Preliminary safety evaluation of polymer intended to use as drug delivery carrier is essential. Methods: In this study polyacrylamide grafted bacterial cellulose (BC/AM hydrogel was prepared by microwave irradiation initiated free radical polymerization. The synthesized hydrogel was subjected to in vitro cytotoxicity and acute gastrointestinal toxicity studies to evaluate its biological safety as potential oral drug delivery carrier. Results: The results indicate that hydrogel was non cytotoxic and did not show any histopathological changes in GI tract after a high dose of oral administration. Conclusion: The results revealed that hydrogel composed of bacterial cellulose and polyacrylamide is safe as oral drug delivery carrier.

Synthesis and characterization of polyvinyl alcohol/cellulose cryogels and their testing as carriers for a bioactive component

Energy Technology Data Exchange (ETDEWEB)

Paduraru, Oana Maria; Ciolacu, Diana; Darie, Raluca Nicoleta; Vasile, Cornelia, E-mail: cvasile@icmpp.ro

2012-12-01

Novel physically cross-linked cryogels containing polyvinyl alcohol (PVA) and various amounts of microcrystalline cellulose were obtained by freezing/thawing technique. The main goal of this study was to improve the properties and the performances of the pure PVA cryogels. The morphological aspects of the cryogels were studied by scanning electron microscopy (SEM). The Fourier transform infrared spectroscopy (FT-IR) was used to reveal the presence of the interactions between the two polymers. Changes in crystallinity of the samples were confirmed by X-ray diffraction (XRD) and by FT-IR spectroscopy. The modification of the thermal behavior induced by cellulose was studied by thermogravimetry. Rheological analysis revealed higher values of storage modulus (G Prime ) for the cryogels containing higher amounts of cellulose. The degree and rate of swelling were controlled by the presence of the natural polymer in the network. The potential application as bioactive compound carriers was tested, using vanillin as an active agent. Highlights: Black-Right-Pointing-Pointer Novel PVA/microcrystalline cellulose cryogels were obtained by freezing/thawing. Black-Right-Pointing-Pointer The main advantage of this technique is that no chemical crosslinker is being used. Black-Right-Pointing-Pointer The presence of cellulose improves the swelling properties and the cryogels' strength. Black-Right-Pointing-Pointer The potential application as carriers for bioactive components was tested.

Effects of different fermentation methods on bacterial cellulose and acid production by Gluconacetobacter xylinus in Cantonese-style rice vinegar.

Science.gov (United States)

Fu, Liang; Chen, Siqian; Yi, Jiulong; Hou, Zongxia

2014-07-01

A strain of acidogenic bacterium was isolated from the fermentation liquid of Cantonese-style rice vinegar produced by traditional surface fermentation. 16S rDNA identification confirmed the bacterium as Gluconacetobacter xylinus, which synthesizes bacterial cellulose, and the acid productivity of the strain was investigated. In the study, the effects of the membrane integrity and the comparison of the air-liquid interface membrane with immerged membrane on total acidity, cellulose production, alcohol dehydrogenase (ADH) activity and number of bacteria were investigated. The cellulose membrane and the bacteria were observed under SEM for discussing their relationship. The correlations between oxygen consumption and total acid production rate were compared in surface and shake flask fermentation. The results showed the average acid productivity of the strain was 0.02g/(100mL/h), and the integrity of cellulose membrane in surface fermentation had an important effect on total acidity and cellulose production. With a higher membrane integrity, the total acidity after 144 h of fermentation was 3.75 g/100 mL, and the cellulose production was 1.71 g/100 mL after 360 h of fermentation. However, when the membrane was crushed by mechanical force, the total acidity and the cellulose production were as low as 0.36 g/100 mL and 0.14 g/100 mL, respectively. When the cellulose membrane was forced under the surface of fermentation liquid, the total acid production rate was extremely low, but the activity of ADH in the cellulose membrane was basically the same with the one above the liquid surface. The bacteria were mainly distributed in the cellulose membrane during the fermentation. The bacterial counts in surface fermentation were more than in the shake flask fermentation and G. xylinus consumed the substrate faster, in surface fermentation than in shake flask fermentation. The oxygen consumption rate and total acid production rate of surface fermentation were respectively 26

A study on displacement of crystalline diffraction peaks in electron-beam irradiated filter paper cellulose

International Nuclear Information System (INIS)

Zhou Ruimin; Xiang Qun; Song Jing

1997-01-01

It is found that the crystalline diffraction angles of the electron-beam irradiated filter paper cellulose shift regularly when the irradiation dose is increased. The experiments indicate that the molecules between crystalline area and amorphous area in the filter paper cellulose will be degraded by the irradiation and the cellulose molecules in the surface of crystal will come off, thus the microcrystalline dimension will be reduced and the diffraction angle will become smaller. The fact that intensity of the 002 peak for filter paper samples decreases gradually with the increasing storage time can be attributed to the post-irradiation effect

Hydrolysis of cellulose catalyzed by quaternary ammonium perrhenates in 1-allyl-3-methylimidazolium chloride.

Science.gov (United States)

Wang, Jingyun; Zhou, Mingdong; Yuan, Yuguo; Zhang, Quan; Fang, Xiangchen; Zang, Shuliang

2015-12-01

Quaternary ammonium perrhenates were applied as catalyst to promote the hydrolysis of cellulose in 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The quaternary ammonium perrhenates displayed good catalytic performance for cellulose hydrolysis. Water was also proven to be effective to promote cellulose hydrolysis. Accordingly, 97% of total reduced sugar (TRS) and 42% of glucose yields could be obtained under the condition of using 5mol% of tetramethyl ammonium perrhenate as catalyst, 70μL of water, ca. 0.6mmol of microcrystalline cellulose (MCC) and 2.0g of [Amim]Cl as solvent under microwave irradiation for 30min at 150°C (optimal conditions). The influence of quaternary ammonium cation on the efficiency of cellulose hydrolysis was examined based on different cation structures of perrhenates. The mechanism on perrhenate catalyzed cellulose hydrolysis is also discussed, whereas hydrogen bonding between ReO4 anion and hydroxyl groups of cellulose is assumed to be the key step for depolymerization of cellulose. Copyright © 2015. Published by Elsevier Ltd.

Controlled silver delivery by silver-cellulose nanocomposites prepared by a one-pot green synthesis assisted by microwaves

Energy Technology Data Exchange (ETDEWEB)

Silva, Ana Rosa; Unali, Gianfranco, E-mail: ana.rosa.silva@ua.pt [Structured Materials Expertise Group, Unilever Discover Port Sunlight, Quarry Road East, Bebington CH63 3JW (United Kingdom)

2011-08-05

Controlled silver release from cellulosic nanocomposites was achieved by synthesizing silver nanoparticles, under microwave heating for 1-15 min, in a one-pot, versatile and sustainable process in which microcrystalline cellulose simultaneously functions as reducing, stabilizing and supporting agent in water; chitin, starch and other cellulose derivatives could also be used as reducing, stabilizing and supporting agents for silver nanoparticles and the method was also found to be extensible to the preparation of noble metal (Au, Pt) and metal oxide nanoparticle (ZnO, Cu, CuO and Cu{sub 2}O) nanocomposites.

Controlled silver delivery by silver-cellulose nanocomposites prepared by a one-pot green synthesis assisted by microwaves

International Nuclear Information System (INIS)

Silva, Ana Rosa; Unali, Gianfranco

2011-01-01

Controlled silver release from cellulosic nanocomposites was achieved by synthesizing silver nanoparticles, under microwave heating for 1-15 min, in a one-pot, versatile and sustainable process in which microcrystalline cellulose simultaneously functions as reducing, stabilizing and supporting agent in water; chitin, starch and other cellulose derivatives could also be used as reducing, stabilizing and supporting agents for silver nanoparticles and the method was also found to be extensible to the preparation of noble metal (Au, Pt) and metal oxide nanoparticle (ZnO, Cu, CuO and Cu 2 O) nanocomposites.

Bionanocomposite films based on plasticized PLA-PHB/cellulose nanocrystal blends.

Science.gov (United States)

Arrieta, M P; Fortunati, E; Dominici, F; López, J; Kenny, J M

2015-05-05

Optically transparent plasticized poly(lactic acid) (PLA) based bionanocomposite films intended for food packaging were prepared by melt blending. Materials were plasticized with 15wt% of acetyl(tributyl citrate) (ATBC) to improve the material processability and to obtain flexibile films. Poly(hydroxybutyrate) (PHB) was used to increase PLA crystallinity. The thermal stability of the PLA-PHB blends was improved by the addition of 5 wt% of cellulose nanocrystals (CNC) or modified cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose. The combination of ATBC and cellulose nanocrystals, mainly the better dispersed CNCs, improved the interaction between PLA and PHB. Thus, an improvement on the oxygen barrier and stretchability was achieved in PLA-PHB-CNCs-ATBC which also displayed somewhat UV light blocking effect. All bionanocomposite films presented appropriate disintegration in compost suggesting their possible applications as biodegradable packaging materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fabrication, characterization and evaluation of bacterial cellulose-based capsule shells for oral drug delivery

DEFF Research Database (Denmark)

Ullah, Hanif; Badshah, Munair; Mäkilä, Ermei

2017-01-01

Bacterial cellulose (BC) was investigated for the first time for the preparation of capsule shells for immediate and sustained release of drugs. The prepared capsule shells were characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The BC...... to gelatin capsules with both immediate and sustained drug release properties depending upon the compositions of the encapsulated materials....

A Molecular Description of Cellulose Biosynthesis

Science.gov (United States)

McNamara, Joshua T.; Morgan, Jacob L.W.; Zimmer, Jochen

2016-01-01

Cellulose is the most abundant biopolymer on Earth, and certain organisms from bacteria to plants and animals synthesize cellulose as an extracellular polymer for various biological functions. Humans have used cellulose for millennia as a material and an energy source, and the advent of a lignocellulosic fuel industry will elevate it to the primary carbon source for the burgeoning renewable energy sector. Despite the biological and societal importance of cellulose, the molecular mechanism by which it is synthesized is now only beginning to emerge. On the basis of recent advances in structural and molecular biology on bacterial cellulose synthases, we review emerging concepts of how the enzymes polymerize glucose molecules, how the nascent polymer is transported across the plasma membrane, and how bacterial cellulose biosynthesis is regulated during biofilm formation. Additionally, we review evolutionary commonalities and differences between cellulose synthases that modulate the nature of the cellulose product formed. PMID:26034894

Bacterial populations and environmental factors controlling cellulose degradation in an acidic Sphagnum peat.

Science.gov (United States)

Pankratov, Timofey A; Ivanova, Anastasia O; Dedysh, Svetlana N; Liesack, Werner

2011-07-01

Northern peatlands represent a major global carbon store harbouring approximately one-third of the global reserves of soil organic carbon. A large proportion of these peatlands consists of acidic Sphagnum-dominated ombrotrophic bogs, which are characterized by extremely low rates of plant debris decomposition. The degradation of cellulose, the major component of Sphagnum-derived litter, was monitored in long-term incubation experiments with acidic (pH 4.0) peat extracts. This process was almost undetectable at 10°C and occurred at low rates at 20°C, while it was significantly accelerated at both temperature regimes by the addition of available nitrogen. Cellulose breakdown was only partially inhibited in the presence of cycloheximide, suggesting that bacteria participated in this process. We aimed to identify these bacteria by a combination of molecular and cultivation approaches and to determine the factors that limit their activity in situ. The indigenous bacterial community in peat was dominated by Alphaproteobacteria and Acidobacteria. The addition of cellulose induced a clear shift in the community structure towards an increase in the relative abundance of the Bacteroidetes. Increasing temperature and nitrogen availability resulted in a selective development of bacteria phylogenetically related to Cytophaga hutchinsonii (94-95% 16S rRNA gene sequence similarity), which densely colonized microfibrils of cellulose. Among isolates obtained from this community only some subdivision 1 Acidobacteria were capable of degrading cellulose, albeit at a very slow rate. These Acidobacteria represent indigenous cellulolytic members of the microbial community in acidic peat and are easily out-competed by Cytophaga-like bacteria under conditions of increased nitrogen availability. Members of the phylum Firmicutes, known to be key players in cellulose degradation in neutral habitats, were not detected in the cellulolytic community enriched at low pH. © 2011 Society for

Preparation and characterization of reinforced papers using nano bacterial cellulose.

Science.gov (United States)

Tabarsa, Taghi; Sheykhnazari, Somayeh; Ashori, Alireza; Mashkour, Mahdi; Khazaeian, Abolghasem

2017-08-01

The main goal of this work was to reinforce softwood pulp (SP) with bacterial cellulose (BC) to generate a sustainable biocomposite. BC is a nanocellulose, which was anticipated to increase interfacial adhesion between the cellulosic fibers and BC. The organism used was Gluconacetobacter xylinus, which was incubated in a static Hestrin-Schramm culture at 28°C for 14days. The specimens of BC, SP and the reinforced SP with BC were characterized using X-ray diffraction (XRD), FT-IR, FESEM, and physico-mechanical testing. The crystallinity index was found to be 83 and 54% for BC and SP, respectively. FT-IR spectra showed that the composition of BC was fully different from that of SP fibers. Based on FESEM images, one can conclude that BC and softwood fibers do form a good combination with a nonporous structure. BC fibers fill in among the softwood fibers in the sheet. The physical and mechanical properties showed that as the dosage of BC increased, the properties of tensile index, tear index, and burst index greatly improved, while the porosity and the elongation decreased. The reason for the improved mechanical properties can be attributed to the increase of interfibrillar bonding which reduced porosity. This would be due to the high aspect ratio of BC that is capable of connecting between the cellulosic fibers and BC nanofibers, enhancing a large contact surface and therefore producing excellent coherence. This study suggests that BC could be a promising material for reinforcing composites at low loading. Copyright © 2017 Elsevier B.V. All rights reserved.

Towards an Integrated QR Code Biosensor: Light-Driven Sample Acquisition and Bacterial Cellulose Paper Substrate.

Science.gov (United States)

Yuan, Mingquan; Jiang, Qisheng; Liu, Keng-Ku; Singamaneni, Srikanth; Chakrabartty, Shantanu

2018-06-01

This paper addresses two key challenges toward an integrated forward error-correcting biosensor based on our previously reported self-assembled quick-response (QR) code. The first challenge involves the choice of the paper substrate for printing and self-assembling the QR code. We have compared four different substrates that includes regular printing paper, Whatman filter paper, nitrocellulose membrane and lab synthesized bacterial cellulose. We report that out of the four substrates bacterial cellulose outperforms the others in terms of probe (gold nanorods) and ink retention capability. The second challenge involves remote activation of the analyte sampling and the QR code self-assembly process. In this paper, we use light as a trigger signal and a graphite layer as a light-absorbing material. The resulting change in temperature due to infrared absorption leads to a temperature gradient that then exerts a diffusive force driving the analyte toward the regions of self-assembly. The working principle has been verified in this paper using assembled biosensor prototypes where we demonstrate higher sample flow rate due to light induced thermal gradients.

Licuri fibers characterization after treatment to produce cellulose nanocrystals

International Nuclear Information System (INIS)

Castro, E.G.; Oliveira, J.C.; Miranda, C.S.; Jose, N.M.

2014-01-01

Cellulose nanocrystals have been widely studied in the materials area due to their high aspect ratio, which is directly related to a good performance as mechanical reinforcement. Obtaining this nanocrystals from commercial bleached pulps, as eucalyptus, or microcrystalline cellulose is well studied. Trying to find new extraction sources, exploring better the huge variety of Brazil’s natural fibers and giving the opportunity of development to small communities, the present work verifies the influence of two bleaching methodologies, sodium hypochlorite or hydrogen peroxide, on licuri fibers. Previous washing and mercerization steps were performed before bleaching. The product of each step was analysed by: DSC, TGA, XRD, SEM and FTIR. The yield of each step was also calculated. (author)

A universal route for the simultaneous extraction and functionalization of cellulose nanocrystals from industrial and agricultural celluloses

Energy Technology Data Exchange (ETDEWEB)

Chen, Guo-Yin; Yu, Hou-Yong, E-mail: phdyu@zstu.edu.cn; Zhang, Cai-Hong [Zhejiang Sci-Tech University, The Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education, College of Materials and Textiles (China); Zhou, Ying; Yao, Ju-Ming, E-mail: yaoj@zstu.edu.cn [Zhejiang Sci-Tech University, National Engineering Lab for Textile Fiber Materials & Processing Technology (China)

2016-02-15

A simple route was designed to extract the cellulose nanocrystals (CNCs) with formate groups from industrial and agricultural celluloses like microcrystalline cellulose (MCC), viscose fiber, ginger fiber, and bamboo fiber. The effect of reaction time on the microstructure and properties of the CNCs was investigated in detail, while microstructure and properties of different CNCs were compared. The rod-like CNCs (MCC) with hundreds of nanometers in length and about 10 nm in width, nanofibrillated CNCs (ginger fiber bamboo fiber) with average width of 30 nm and the length of 1 μm, and spherical CNCs (viscose fiber) with the width of 56 nm were obtained by one-step HCOOH/HCl hydrolysis. The CNCs with improved thermal stability showed the maximum degradation temperature (T{sub max}) of 368.9–388.2 °C due to the introduction of formate groups (reducibility) and the increased crystallinity. Such CNCs may be used as an effective template for the synthesis of nanohybrids or reinforcing material for high-performance nanocomposites.

A universal route for the simultaneous extraction and functionalization of cellulose nanocrystals from industrial and agricultural celluloses

International Nuclear Information System (INIS)

Chen, Guo-Yin; Yu, Hou-Yong; Zhang, Cai-Hong; Zhou, Ying; Yao, Ju-Ming

2016-01-01

A simple route was designed to extract the cellulose nanocrystals (CNCs) with formate groups from industrial and agricultural celluloses like microcrystalline cellulose (MCC), viscose fiber, ginger fiber, and bamboo fiber. The effect of reaction time on the microstructure and properties of the CNCs was investigated in detail, while microstructure and properties of different CNCs were compared. The rod-like CNCs (MCC) with hundreds of nanometers in length and about 10 nm in width, nanofibrillated CNCs (ginger fiber bamboo fiber) with average width of 30 nm and the length of 1 μm, and spherical CNCs (viscose fiber) with the width of 56 nm were obtained by one-step HCOOH/HCl hydrolysis. The CNCs with improved thermal stability showed the maximum degradation temperature (T max ) of 368.9–388.2 °C due to the introduction of formate groups (reducibility) and the increased crystallinity. Such CNCs may be used as an effective template for the synthesis of nanohybrids or reinforcing material for high-performance nanocomposites

Influence of polyvinylpyrrolidone, microcrystalline cellulose and colloidal silicon dioxide on technological characteristics of a high-dose Petiveria alliacea tablet.

Science.gov (United States)

García-Pérez, Martha-Estrella; Lemus-Rodríguez, Zoe; Hung-Arbelo, Mario; Vistel-Vigo, Marlen

2017-12-01

Petiveria alliacea L. (Phytolaccaceae) is a perennial shrub used by its immunomodulatory, anticancerogenic and anti-inflammatory properties. This study determined the influence of polyvinylpyrrolidone (PVP), colloidal silicon dioxide (CSD) and microcrystalline cellulose (MC) on the technological characteristic of a high-dose P. alliacea tablet prepared by the wet granulation method. The botanical and pharmacognostic analysis of the plant material was firstly performed, followed by a 2 3 factorial design considering three factors at two levels: (a) the binder (PVP) incorporated in formulation at 10% and 15% (w/w); (b) the compacting agent (CSD) added at 10% and 15% (w/w) and; (c) the diluent (MC) included at 7.33% and 12.46% (w/w). The analysis of pharmaceutical performance and the accelerated and long-term stability of the best prototype were also completed. The binder, compacting agent and the interaction binder/diluent had a significant impact on breaking force of high-dose P. alliacea tablet. The optimum formula was found to contain 15% (w/w) of CSD, 7.33% (w/w) of MC and 10% (w/w) of PVP. At these conditions, the tablet shows a breaking force of 77.96 N, a friability of 0.39%, a total phenol content of 1.30 mg/tablet and a maximum disintegration time of 6 min. The use of adequate amounts of PVP, MC and CSD as per the factorial design allowed the preparation of a tablet suitable for administration, despite the inappropriate flow and compressibility properties of the P. alliacea powder.

Production and characterization of nanospheres of bacterial cellulose from Acetobacter xylinum from processed rice bark

International Nuclear Information System (INIS)

Goelzer, F.D.E.; Faria-Tischer, P.C.S.; Vitorino, J.C.; Sierakowski, Maria-R.; Tischer, C.A.

2009-01-01

Bacterial cellulose (BC), biosynthesized by Acetobacter xylinum, was produced in a medium consisting of rice bark pre-treated with an enzymatic pool. Rice bark was evaluated as a carbon source by complete enzymatic hydrolysis and monosaccharide composition (GC-MS of derived alditol acetates). It was treated enzymatically and then enriched with glucose up to 4% (w/v). The BC produced by static and aerated processes was purified by immersion in 0.1 M NaOH, was characterized by FT-IR, X-ray diffraction and the biosynthetic nanostructures were evaluated by Scanning Electronic (SEM), Transmission Electronic (TEM) and Atomic Force Microscopy (AFM). The BC films arising from static fermentation with rice bark/glucose and glucose are tightly intertwined, partially crystalline, being type II cellulose produced with rice bark/glucose, and type I to the produced in a glucose medium. The nanostructurated biopolymer obtained from the rice bark/glucose medium, produced in a reactor with air flux had micro- and nanospheres linked to nanofibers of cellulose. These results indicate that the bark components, namely lignins, hemicelluloses or mineral contents, interact with the cellulose forming micro- and nanostructures with potential use to incorporate drugs

Conversion of industrial (ligno)cellulose feeds to isosorbide with heteropoly acids and Ru on carbon

Energy Technology Data Exchange (ETDEWEB)

Op de Beeck, B.; Van Lishout, J.; Jacobs, P.A.; Sels, B.F. [Centre for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Kasteelpark Arenberg 23, 3001 Heverlee (Belgium); Geboers, J. [Max-Planck-Institut fuer Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Muelheim an der Ruhr (Germany); Van de Vyver, S. [Massachusetts Institute of Technology MIT, Massachusetts Avenue 77, Cambridge, MA 02139-4307 (United States); Snelders, J.; Courtin, C.M. [Centre for Food and Microbial Technology, Katholieke Universiteit Leuven, Kasteelpark Arenberg 22, 3001 Heverlee (Belgium); Huijgen, W.J.J. [Biomass and Energy Efficiency BEE, Energy research Centre of the Netherlands ECN, Westerduinweg 3, 1755 LE Petten (Netherlands)

2013-01-11

The catalytic valorization of cellulose is currently subject of intense research. Isosorbide is among the most interesting products that can be formed from cellulose as it is a potential platform molecule and can be used for the synthesis of a wide range of pharmaceuticals, chemicals, and polymers. A promising direct route from cellulose to isosorbide is presented in this work. The strategy relies on a one-pot bifunctional catalytic concept, combining heteropoly acids, viz. H4SiW12O40, and redox catalysts, viz. commercial Ru on carbon, under H2 pressure. Starting from pure microcrystalline cellulose, a rapid conversion was observed, resulting in over 50% isosorbide yield. The robustness of the developed system is evidenced by the conversion of a range of impure cellulose pulps obtained by organosolv fractionation, with isosorbide yields up to 63%. Results were compared with other (ligno)cellulose feedstocks, highlighting the importance of fractionation and purification to increase reactivity and convertibility of the cellulose feedstock.

Cellulose hydrolysis by fungi. 2. Cellulase production by Trichoderma harzianum in liquid medium fermentation

Energy Technology Data Exchange (ETDEWEB)

Roussos, S.; Raimbault, M. (Laboratoire de Microbiologie ORSTOM, Centre de Recherche IRCHA, 91 - Vert-le-Petit (France))

Microcrystalline cellulose (cellulose Avicel, Merck) supported growth of Trichoderma harzianum and induced production of cellulases in liquid cultures. After 50 h growth, the total cellulasic activities present in both the supernatant and the mycelium were 3,000 IU/l of carboxymethyl cellulose, 400 IU/l of filter paper activity, and 4 IU/l of cotton activity corresponding to 1.7 g/l of proteins. Cellulase production could be increased by a preliminary treatment of cellulose, and pH regulation during growth. The influence of inoculum concentration was studied and an optimum of 3 X 10/sup 7/ conidia/g dry weight of substrate was demonstrated. Using a synthetic culture medium, a soluble factor of germination was demonstrated which could be leached out by 3 successive washings of conidia.

ZnO nanostructures directly grown on paper and bacterial cellulose substrates without any surface modification layer.

Science.gov (United States)

Costa, Saionara V; Gonçalves, Agnaldo S; Zaguete, Maria A; Mazon, Talita; Nogueira, Ana F

2013-09-21

In this report, hierarchical ZnO nano- and microstructures were directly grown for the first time on a bacterial cellulose substrate and on two additional different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures.

Magnetically modified bacterial cellulose: A promising carrier for immobilization of affinity ligands, enzymes, and cells

Czech Academy of Sciences Publication Activity Database

Baldíková, E.; Pospíšková, K.; Ladakis, D.; Kookos, I.K.; Koutinas, A.A.; Šafaříková, Miroslava; Šafařík, Ivo

2017-01-01

Roč. 71, February (2017), s. 214-221 ISSN 0928-4931 Institutional support: RVO:60077344 Keywords : bacterial cellulose * Komagataeibacter sucrofermentans * copper phthalocyanine * crystal violet * yeast cells * trypsin Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Bioproducts (products that are manufactured using biological material as feedstock) biomaterials, bioplastics, biofuels, bioderived bulk and fine chemicals, bio-derived novel materials Impact factor: 4.164, year: 2016

Strategies for cost-effective and enhanced production of bacterial cellulose.

Science.gov (United States)

Islam, Mazhar Ul; Ullah, Muhammad Wajid; Khan, Shaukat; Shah, Nasrullah; Park, Joong Kon

2017-09-01

Bacterial cellulose (BC) has received substantial attention because of its high purity, mechanical strength, crystallinity, liquid-absorbing capabilities, biocompatibility, and biodegradability etc. These properties allow BC to be used in various fields, especially in industries producing medical, electronic, and food products etc. A major discrepancy associated with BC is its high production cost, usually much higher than the plant cellulose. To address this limitations, researchers have developed several strategies for enhanced production of BC including the designing of advanced reactors and utilization of various carbon sources. Another promising approach is the production of BC from waste materials such as food, industrial, agricultural, and brewery wastes etc. which not only reduces the overall BC production cost but is also environment-friendly. Besides, exploration of novel and efficient BC producing microbial strains provides impressive boost to the BC production processes. To this end, development of genetically engineered microbial strains has proven useful for enhanced BC production. In this review, we have summarized major efforts to enhance BC production in order to make it a cost-effective biopolymer. This review can be of interest to researchers investigating strategies for enhanced BC production, as well as companies exploring pilot projects to scale up BC production for industrial applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Water absorption and maintenance of nanofiber cellulose ...

African Journals Online (AJOL)

DR. NJ TONUKARI

2012-05-17

May 17, 2012 ... Physiochemical properties of bacterial cellulose producing by Gluconacetobacter rhaeticus TL-2C was ... shape of the mold (Czaja et al., 2006). ... impurity, and then it was freeze-dried and ground to a fine ... Figure 1. Microstructure and chemical structure of bacterial cellulose producing G. rhaeticus TL-2C.

Preliminary study on biosynthesis and characterization of bacteria cellulose films from coconut water

Science.gov (United States)

Indrianingsih, A. W.; Rosyida, V. T.; Jatmiko, T. H.; Prasetyo, D. J.; Poeloengasih, C. D.; Apriyana, W.; Nisa, K.; Nurhayati, S.; Hernawan; Darsih, C.; Pratiwi, D.; Suwanto, A.; Ratih, D.

2017-12-01

Bacterial cellulose produced by Acetobacter xylinum is a unique type of bacterial cellulose. It contains more than 90% of water. A preliminary study had shown that bacterial cellulose films has remarkable mechanical properties. The aim of this study was to investigate the optimum condition such as percentage of carbon source, time of cultivation, and pH to produce bacterial cellulose films from local coconut water, and its characterization on morphology, swelling ability and tensile strength of dried bacterial cellulose. A. xylinum was grown on coconut water culture medium with addition of 3%, 5%, and 7% of sugar, while the cultivation time was vary from 3 days, 5 days and 7 days. pH condition was conducted in pH 3, pH 5 and pH 7. Bacterial cellulose samples were dried using oven with temperature of 100°C until the moisture content reached 4-5%. This study showed that several parameters for optimum condition to produce bacterial cellulose films from local waste of coconut water had been obtained (5% of carbon source; pH 5; and 7 day of incubation period). The electron microscopy also showed that dried bacterial cellulose films had pores covered by fibrils on the surface. Therefore, the present work proposes the optimum formula and condition that can be used based on properties of end product needed.

Construction of a Bacterial Cellulase Cocktail for Saccharification of Regenerated Cellulose and Pretreated Corn Stover

Directory of Open Access Journals (Sweden)

Alei Geng

2015-09-01

Full Text Available To apply bacterial cellulases for efficient saccharification of biomass, three Clostridium thermocellum cellulases and a Thermoanaerobacter brockii β-1,4-glucosidase were synthesized in Escherichia coli, and the proportions among them were optimized. When the activities of CelD, CBHA, CBH48Y, and CglT were set at 554, 0.91, 0.91, and 856 mU per assay, respectively, the percent conversion of regenerated cellulose (0.92 g/L reached 80.9% within 24 h at 60 °C without shaking. Meanwhile, the percent conversion of pretreated corn stover (0.62 g/L reached 70.1%. Gradually raising the loads of regenerated cellulose from 0.92 to 4.58 g/L resulted in a linear increase in glucose production from 870 to 3208 μg (R2=0.997, as well as a decrease in the percent conversion from 80.9% to 59.6%. These findings suggested that the cellulase cocktail is efficient in saccharification of regenerated cellulose, as well as pretreated corn stover, and has potential applications in the biofuels industry.

Low melting point pyridinium ionic liquid pretreatment for enhancing enzymatic saccharification of cellulosic biomass.

Science.gov (United States)

Uju; Nakamoto, Aya; Shoda, Yasuhiro; Goto, Masahiro; Tokuhara, Wataru; Noritake, Yoshiyuki; Katahira, Satoshi; Ishida, Nobuhiro; Ogino, Chiaki; Kamiya, Noriho

2013-05-01

The potential of 1-hexylpyridinium chloride ([Hpy][Cl]), to pretreat cellulosic feedstocks was investigated using microcrystalline cellulose (Avicel) and Bagasse at 80 °C or 100 °C. Short [Hpy][Cl] pretreatments, conversion of pretreated Avicel to glucose was attained after 24h enzymatic saccharification under optimal conditions, whereas regenerated Bagasse showed 1-3-fold higher conversion than untreated biomass. FT-IR analysis of both Avicel and Bagasse samples pretreated with [Hpy][Cl] or 1-ethyl-3-methyimidazolium acetate ([Emim][OAc]) revealed that these ionic liquids behaved differently during pretreatment. [Hpy][Cl] pretreatment for an extended duration (180 min) released mono- and disaccharides without using cellulase enzymes, suggesting [Hpy][Cl] has capability for direct saccharification of cellulosic feedstocks. On the basis of the results obtained, [Hpy][Cl] pretreatment enhanced initial reaction rates in enzymatic saccharification by either crystalline polymorphic alteration of cellulose or partial degradation of the crystalline cellulosic fraction in biomass. Copyright © 2012 Elsevier Ltd. All rights reserved.

A soft biomolecule actuator based on a highly functionalized bacterial cellulose nano-fiber network with carboxylic acid groups.

Science.gov (United States)

Wang, Fan; Jeon, Jin-Han; Park, Sukho; Kee, Chang-Doo; Kim, Seong-Jun; Oh, Il-Kwon

2016-01-07

Upcoming human-related applications such as soft wearable electronics, flexible haptic systems, and active bio-medical devices will require bio-friendly actuating materials. Here, we report a soft biomolecule actuator based on carboxylated bacterial cellulose (CBC), ionic liquid (IL), and poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) ( PSS) electrodes. Soft and biocompatible polymer-IL composites were prepared via doping of CBC with ILs. The highly conductive PSS layers were deposited on both sides of the CBC-IL membranes by a dip-coating technique to yield a sandwiched actuator system. Ionic conductivity and ionic exchange capacity of the CBC membrane can be increased up to 22.8 times and 1.5 times compared with pristine bacterial cellulose (BC), respectively, resulting in 8 times large bending deformation than the pure BC actuators with metallic electrodes in an open air environment. The developed CBC-IL actuators show significant progress in the development of biocompatible and soft actuating materials with quick response, low operating voltage and comparatively large bending deformation.

To Evaluate the Effect of Solvents and Different Relative Humidity Conditions on Thermal and Rheological Properties of Microcrystalline Cellulose 101 Using METHOCEL™ E15LV as a Binder.

Science.gov (United States)

Jagia, Moksh; Trivedi, Maitri; Dave, Rutesh H

2016-08-01

The solvent used for preparing the binder solution in wet granulation can affect the granulation end point and also impact the thermal, rheological, and flow properties of the granules. The present study investigates the effect of solvents and percentage relative humidity (RH) on the granules of microcrystalline cellulose (MCC) with hydroxypropyl methyl cellulose (HPMC) as the binder. MCC was granulated using 2.5% w/w binder solution in water and ethanol/water mixture (80:20 v/v). Prepared granules were dried until constant percentage loss on drying, sieved, and further analyzed. Dried granules were exposed to different percentage RH for 48 h at room temperature. Powder rheometer was used for the rheological and flow characterization, while thermal effusivity and differential scanning calorimeter were used for thermal analysis. The thermal effusivity values for the wet granules showed a sharp increase beginning 50% w/w binder solution in both cases, which reflected the over-wetting of granules. Ethanol/water solvent batches showed greater resistance to flow as compared to the water solvent batches in the wet granule stage, while the reverse was true for the dried granule stage, as evident from the basic flowability energy values. Although the solvents used affected the equilibration kinetics of moisture content, the RH-exposed granules remained unaffected in their flow properties in both cases. This study indicates that the solvents play a vital role on the rheology and flow properties of MCC granules, while the different RH conditions have little or no effect on them for the above combination of solvent and binder.

Novel Cu@SiO2/bacterial cellulose nanofibers: Preparation and excellent performance in antibacterial activity

International Nuclear Information System (INIS)

Ma, Bo; Huang, Yang; Zhu, Chunlin; Chen, Chuntao; Chen, Xiao; Fan, Mengmeng; Sun, Dongping

2016-01-01

The antibacterial composite based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of SiO 2 coated Cu nanoparticles (Cu@SiO 2 /BC) and its properties were characterized. Its chemical structures and morphologies were evaluated by Fourier transformation infrared spectrum (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the SiO 2 coated Cu particles were well homogeneously precipitated on the surface of BC. The Cu@SiO 2 /BC was more resistant to oxidation than the Cu nanoparticles impregnated into BC (Cu/BC) and then Cu@SiO 2 /BC could prolong the antimicrobial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). - Graphical abstract: Schematic illustration of the preparation of Cu@SiO 2 /BC. Due to its unique structure, the Cu@SiO 2 /BC membrane shows excellent antibacterial effects and can be used for a long time. - Highlights: • This work paves the novel way to fabricate antibacterial nanomaterial with good efficiency. • We prepare the antibacterial membrane based on bacterial cellulose by in-situ synthesis of SiO 2 -coated Cu nanoparticles. • The antibacterial membrane is more resistant to oxidation and can prolong the antimicrobial activity.

Kinetic and mass transfer studies on the isomerization of cellulose hydrolyzate using immobilized Streptomyces cells

Energy Technology Data Exchange (ETDEWEB)

Ghose, T K; Chand, S

1978-01-01

Streptomyces cells possessing glucose isomerase activity, heat-treated and confined within polyester sacs have been used in batch/continuous isomerization of enzymatically hydrolyzed microcrystalline cellulose. Conversion data at different concentrations of substrate closely follow the reactor performance equation based on the reaction kinetics. The effect of external film and pore diffusional resistances were experimentally found to be negligible. The dispersion effects in the packed bed column have been evaluated by pulse input tracer analysis. Continuous operation of the column to isomerize cellulose hydrolyzate (2.0 M glucose) showed an exponential deactivation of enzyme activity with a half-life of 447 h.

Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

Energy Technology Data Exchange (ETDEWEB)

Stoica-Guzun, Anicuta [Department of Chemical Engineering, ' Politehnica' University Bucharest, 313 Splaiul Independentei, 060042 Bucharest (Romania)], E-mail: astoica@mt.pub.ro; Stroescu, Marta; Tache, Florin [Department of Chemical Engineering, ' Politehnica' University Bucharest, 313 Splaiul Independentei, 060042 Bucharest (Romania); Zaharescu, Traian [Advanced Research Institute for Electrical Engineering, 313 Splaiul Unirii, 030138 Bucharest (Romania)], E-mail: zaharescut@icpe-ca.ro; Grosu, Elena [Department of Chemical Engineering, ' Politehnica' University Bucharest, 313 Splaiul Independentei, 060042 Bucharest (Romania)

2007-12-15

Ionizing radiation is an effective energetic source for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. In this work, gamma rays have been applied to induce changes in bacterial cellulose membranes. Permeation of drug (tetracycline) was theoretically and experimentally investigated starting from the effect of {gamma}-irradiation on membranes permeability. Release and permeation of drug from irradiated and non-irradiated membranes have been performed using a diffusion cell.

Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

International Nuclear Information System (INIS)

Stoica-Guzun, Anicuta; Stroescu, Marta; Tache, Florin; Zaharescu, Traian; Grosu, Elena

2007-01-01

Ionizing radiation is an effective energetic source for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. In this work, gamma rays have been applied to induce changes in bacterial cellulose membranes. Permeation of drug (tetracycline) was theoretically and experimentally investigated starting from the effect of γ-irradiation on membranes permeability. Release and permeation of drug from irradiated and non-irradiated membranes have been performed using a diffusion cell

Effect of electron beam irradiation on bacterial cellulose membranes used as transdermal drug delivery systems

Science.gov (United States)

Stoica-Guzun, Anicuta; Stroescu, Marta; Tache, Florin; Zaharescu, Traian; Grosu, Elena

2007-12-01

Ionizing radiation is an effective energetic source for polymer surfaces modification in order to obtain transdermal systems with different controlled release properties. In this work, gamma rays have been applied to induce changes in bacterial cellulose membranes. Permeation of drug (tetracycline) was theoretically and experimentally investigated starting from the effect of γ-irradiation on membranes permeability. Release and permeation of drug from irradiated and non-irradiated membranes have been performed using a diffusion cell.

Optimized Monitoring of Production of Cellulose Nanowhiskers from Opuntia ficus-indica (Nopal Cactus

Directory of Open Access Journals (Sweden)

Horacio Vieyra

2015-01-01

Full Text Available Preparation of cellulose nanowhiskers (CNWs has grown significantly because they are useful for a wide range of applications. Additional advantage in their design requires that they meet the following characteristics: nontoxicity, abundance, sustainability, renewability, and low cost. To address these requirements, nanowhiskers were prepared from Opuntia ficus-indica (nopal cellulose by acid hydrolysis. Monitoring the process of CNWs preparation is necessary to ensure maximum yield and purity of the end product. In this study, the cellulose preparation was monitored by analyzing microscopic morphology by SEM; the purity degree was determined by fluorescence microscopy as a novel and rapid technique, and FTIR spectroscopy was used for confirmation. The additional parameters that monitored the process were the crystallinity index by X-ray diffraction and the size of the particle by dynamic light scattering (DLS. Nopal cellulose was found to be comparable to commercial microcrystalline cellulose. The use of Opuntia ficus-indica is a viable alternative for the production of highly pure CNWs and the strategy to supervise the preparation process was rapid.

Method for depositing high-quality microcrystalline semiconductor materials

Science.gov (United States)

Guha, Subhendu [Bloomfield Hills, MI; Yang, Chi C [Troy, MI; Yan, Baojie [Rochester Hills, MI

2011-03-08

A process for the plasma deposition of a layer of a microcrystalline semiconductor material is carried out by energizing a process gas which includes a precursor of the semiconductor material and a diluent with electromagnetic energy so as to create a plasma therefrom. The plasma deposits a layer of the microcrystalline semiconductor material onto the substrate. The concentration of the diluent in the process gas is varied as a function of the thickness of the layer of microcrystalline semiconductor material which has been deposited. Also disclosed is the use of the process for the preparation of an N-I-P type photovoltaic device.

Bacterial cellulose–kaolin nanocomposites for application as biomedical wound healing materials

International Nuclear Information System (INIS)

Wanna, Dwi; Alam, Parvez; Alam, Catharina; Toivola, Diana M

2013-01-01

This short communication provides preliminary experimental details on the structure–property relationships of novel biomedical kaolin–bacterial cellulose nanocomposites. Bacterial cellulose is an effective binding agent for kaolin particles forming reticulated structures at kaolin–cellulose interfaces and entanglements when the cellulose fraction is sufficiently high. The mechanical performance of these materials hence improves with an increased fraction of bacterial cellulose, though this also causes the rate of blood clotting to decrease. These composites have combined potential as both short-term (kaolin) and long-term (bacterial cellulose) wound healing materials. (paper)

CELLULOSIC NANOCOMPOSITES: A REVIEW

Directory of Open Access Journals (Sweden)

Martin A. Hubbe

2008-08-01

Full Text Available Because of their wide abundance, their renewable and environmentally benign nature, and their outstanding mechanical properties, a great deal of attention has been paid recently to cellulosic nanofibrillar structures as components in nanocomposites. A first major challenge has been to find efficient ways to liberate cellulosic fibrils from different source materials, including wood, agricultural residues, or bacterial cellulose. A second major challenge has involved the lack of compatibility of cellulosic surfaces with a variety of plastic materials. The water-swellable nature of cellulose, especially in its non-crystalline regions, also can be a concern in various composite materials. This review of recent work shows that considerable progress has been achieved in addressing these issues and that there is potential to use cellulosic nano-components in a wide range of high-tech applications.

In situ and ex situ modifications of bacterial cellulose for applications in tissue engineering.

Science.gov (United States)

Stumpf, Taisa Regina; Yang, Xiuying; Zhang, Jingchang; Cao, Xudong

2018-01-01

Bacterial cellulose (BC) is secreted by a few strains of bacteria and consists of a cellulose nanofiber network with unique characteristics. Because of its excellent mechanical properties, outstanding biocompatibilities, and abilities to form porous structures, BC has been studied for a variety of applications in different fields, including the use as a biomaterial for scaffolds in tissue engineering. To extend its applications in tissue engineering, native BC is normally modified to enhance its properties. Generally, BC modifications can be made by either in situ modification during cell culture or ex situ modification of existing BC microfibers. In this review we will first provide a brief introduction of BC and its attributes; this will set the stage for in-depth and up-to-date discussions on modified BC. Finally, the review will focus on in situ and ex situ modifications of BC and its applications in tissue engineering, particularly in bone regeneration and wound dressing. Copyright © 2016. Published by Elsevier B.V.

Nanocomposites of cellulose/iron oxide: influence of synthesis conditions on their morphological behavior and thermal stability

International Nuclear Information System (INIS)

Ma Mingguo; Zhu Jiefang; Li Shuming; Jia Ning; Sun Runcang

2012-01-01

Nanocomposites of cellulose/iron oxide have been successfully prepared by hydrothermal method using cellulose solution and Fe(NO 3 ) 3 ·9H 2 O at 180 °C. The cellulose solution was obtained by the dissolution of microcrystalline cellulose in NaOH/urea aqueous solution, which is a good system to dissolve cellulose and favors the synthesis of iron oxide without needing any template or other reagents. The phases, microstructure, and morphologies of nanocomposites were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectra (EDS). The effects of the heating time, heating temperature, cellulose concentration, and ferric nitrate concentration on the morphological behavior of products were investigated. The experimental results indicated that the cellulose concentration played an important role in both the phase and shape of iron oxide in nanocomposites. Moreover, the nanocomposites synthesized by using different cellulose concentrations displayed different thermal stabilities. - Highlights: ► Nanocomposites of cellulose/iron oxide have been prepared by hydrothermal method. ► The cellulose concentration played an important role in the phase of iron oxide. ► The cellulose concentration played an important role in the shape of iron oxide. ► The samples displayed different thermal stabilities.

Ultrafine nano-network structured bacterial cellulose as reductant and bridging ligands to fabricate ultrathin K-birnessite type MnO2 nanosheets for supercapacitors

Science.gov (United States)

Zhang, Xiaojuan; He, Mingqian; He, Ping; Li, Caixia; Liu, Huanhuan; Zhang, Xingquan; Ma, Yongjun

2018-03-01

In this work, nanostructured ultrathin K-birnessite type MnO2 nanosheets are successfully prepared by a rapid and environmently friendly hydrothermal method, which involves only a facile redox reaction between KMnO4 and nano-network structured bacterial cellulose with abundant hydroxyl groups. The results show that the unique three-dimensional interwoven structured bacterial cellulose acts as not only reductant but also bridging ligands for assembling nanoscaled building units to control the desired morphology of prepared MnO2. Furthermore, electrochemical performances of prepared MnO2 are investigated as electrode materials for supercapacitors by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectrum in 1.0 M Na2SO4 electrolyte. The resulting ultrathin K-birnessite type MnO2 nanosheets based electrode exhibits higher capacitance (328.2 F g-1 at 0.2 A g-1), excellent rate capability (328.2 F g-1 and 200.4 F g-1 at 0.2 A g-1 and 2.0 A g-1, respectively) and satisfactory cyclic stability (91.6% of initial capacitance even after 2000 cycles at 3.0 A g-1). This work suggests that bacterial cellulose as reductant is a promising candidate in the development of nanostructures of metal oxides.

Multifunctional PLA-PHB/cellulose nanocrystal films: processing, structural and thermal properties.

Science.gov (United States)

Arrieta, M P; Fortunati, E; Dominici, F; Rayón, E; López, J; Kenny, J M

2014-07-17

Cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose by acid hydrolysis were added into poly(lactic acid)-poly(hydroxybutyrate) (PLA-PHB) blends to improve the final properties of the multifunctional systems. CNC were also modified with a surfactant (CNCs) to increase the interfacial adhesion in the systems maintaining the thermal stability. Firstly, masterbatch pellets were obtained for each formulation to improve the dispersion of the cellulose structures in the PLA-PHB and then nanocomposite films were processed. The thermal stability as well as the morphological and structural properties of nanocomposites was investigated. While PHB increased the PLA crystallinity due to its nucleation effect, well dispersed CNC and CNCs not only increased the crystallinity but also improved the processability, the thermal stability and the interaction between both polymers especially in the case of the modified CNCs based PLA-PHB formulation. Likewise, CNCs were better dispersed in PLA-CNCs and PLA-PHB-CNCs, than CNC. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pretreatment of Cellulose By Electron Beam Irradiation Method

Science.gov (United States)

Jusri, N. A. A.; Azizan, A.; Ibrahim, N.; Salleh, R. Mohd; Rahman, M. F. Abd

2018-05-01

Pretreatment process of lignocellulosic biomass (LCB) to produce biofuel has been conducted by using various methods including physical, chemical, physicochemical as well as biological. The conversion of bioethanol process typically involves several steps which consist of pretreatment, hydrolysis, fermentation and separation. In this project, microcrystalline cellulose (MCC) was used in replacement of LCB since cellulose has the highest content of LCB for the purpose of investigating the effectiveness of new pretreatment method using radiation technology. Irradiation with different doses (100 kGy to 1000 kGy) was conducted by using electron beam accelerator equipment at Agensi Nuklear Malaysia. Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) analyses were studied to further understand the effect of the suggested pretreatment step to the content of MCC. Through this method namely IRR-LCB, an ideal and optimal condition for pretreatment prior to the production of biofuel by using LCB may be introduced.

Evaluation of cellulose-binding domain fused to a lipase for the lipase immobilization.

Science.gov (United States)

Hwang, Sangpill; Ahn, Jungoh; Lee, Sumin; Lee, Tai Gyu; Haam, Seungjoo; Lee, Kangtaek; Ahn, Ik-Sung; Jung, Joon-Ki

2004-04-01

A cellulose-binding domain (CBD) fragment of a cellulase gene of Trichoderma hazianum was fused to a lipase gene of Bacillus stearothermophilus L1 to make a gene cluster for CBD-BSL lipase. The specific activity of CBD-BSL lipase for oil hydrolysis increased by 33% after being immobilized on Avicel (microcrystalline cellulose), whereas those of CBD-BSL lipase and BSL lipase decreased by 16% and 54%, respectively, after being immobilized on silica gel. Although the loss of activity of an enzyme immobilized by adsorption has been reported previously, the loss of activity of the CBD-BSL lipase immobilized on Avicel was less than 3% after 12 h due to the irreversible binding of CBD to Avicel.

Applicability of bacterial cellulose as an alternative to paper points in endodontic treatment.

Science.gov (United States)

Yoshino, Aya; Tabuchi, Mari; Uo, Motohiro; Tatsumi, Hiroto; Hideshima, Katsumi; Kondo, Seiji; Sekine, Joji

2013-04-01

Dental root canal treatment is required when dental caries progress to infection of the dental pulp. A major goal of this treatment is to provide complete decontamination of the dental root canal system. However, the morphology of dental root canal systems is complex, and many human dental roots have inaccessible areas. In addition, dental reinfection is fairly common. In conventional treatment, a cotton pellet and paper point made from plant cellulose is used to dry and sterilize the dental root canal. Such sterilization requires a treatment material with high absorbency to remove any residue, the ability to improve the efficacy of intracanal medication and high biocompatibility. Bacterial cellulose (BC) is produced by certain strains of bacteria. In this study, we developed BC in a pointed form and evaluated its applicability as a novel material for dental canal treatment with regard to solution absorption, expansion, tensile strength, drug release and biocompatibility. We found that BC has excellent material and biological characteristics compared with conventional materials, such as paper points (plant cellulose). BC showed noticeably higher absorption and expansion than paper points, and maintained a high tensile strength even when wet. The cumulative release of a model drug was significantly greater from BC than from paper points, and BC showed greater compatibility than paper points. Taken together, BC has great potential for use in dental root canal treatment. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Green thermal-assisted synthesis and characterization of novel cellulose-Mg(OH)2 nanocomposite in PEG/NaOH solvent.

Science.gov (United States)

Ponomarev, Nikolai; Repo, Eveliina; Srivastava, Varsha; Sillanpää, Mika

2017-11-15

Synthesis of nanocomposites was performed using microcrystalline cellulose (MCC), MgCl 2 in PEG/NaOH solvent by a thermal-assisted method at different temperatures by varying time and the amount of MCC. Results of XRD, FTIR, and EDS mapping showed that the materials consisted of only cellulose (CL) and magnesium hydroxide (MH). According to FTIR and XRD, it was found that crystallinity of MH in cellulose nanocomposites is increased with temperature and heating time and decreased with increasing of cellulose amount. The PEG/NaOH solvent has a significant effect on cellulose and Mg(OH) 2 morphology. BET and BJH results demonstrated the effects of temperature and cellulose amount on the pore size corresponding to mesoporous materials. TG and DTG analyses showed the increased thermal stability of cellulose nanocomposites with increasing temperature. TEM and SEM analyses showed an even distribution of MH nanostructures with various morphology in the cellulose matrix. The cellulose presented as the polymer matrix in the nanocomposites. It was supposed the possible interaction between cellulose and Mg(OH) 2 . The novel synthesis method used in this study is feasible, cost-efficient and environmentally friendly. Copyright © 2017 Elsevier Ltd. All rights reserved.

High Performance Regenerated Cellulose Membranes from Trimethylsilyl Cellulose

KAUST Repository

Ali, Ola

2013-05-01

Regenerated cellulose (RC) membranes are extensively used in medical and pharmaceutical separation processes due to their biocompatibility, low fouling tendency and solvent resistant properties. They typically possess ultrafiltration and microfiltration separation characteristics, but recently, there have been attempts to widen their pool of applications in nanofiltration processes. In this work, a novel method for preparing high performance composite RC membranes was developed. These membranes reveal molecular weight cut-offs (MWCO) of less than 250 daltons, which possibly put them ahead of all commercial RC membranes and in competition with high performance nanofiltration membranes. The membranes were prepared by acidic hydrolysis of dip-coated trimethylsilyl cellulose (TMSC) films. TMSC, with a degree of silylation (DS) of 2.8, was prepared from microcrystalline cellulose by reaction with hexamethyldisilazane under the homogeneous conditions of LiCl/DMAC solvent system. Effects of parameters, such as coating solution concentration and drying rates, were investigated. It was concluded that higher TMSC concentrations as well as higher solvent evaporation rates favor better MWCOs, mainly due to increase in the selective layer thickness. Successful cross-linking of prepared membranes with glyoxal solutions, in the presence of boric acid as a catalyst, resulted in MWCOs less than 250 daltons. The suitability of this crosslinking reaction for large scale productions was already proven in the manufacturing of durable-press fabrics. For us, the inexpensive raw materials as well as the low reaction times and temperatures were of interest. Moreover, the non-toxic nature of glyoxal is a key advantage in medical and pharmaceutical applications. The membranes prepared in this work are strong candidates for separation of small organic solutes from organic solvents streams in pharmaceutical industries. Their hydrophilicity, compared to typical nanofiltration membranes, offer

Modification of Bacterial Cellulose Biofilms with Xylan Polyelectrolytes.

Science.gov (United States)

Santos, Sara M; Carbajo, José M; Gómez, Nuria; Ladero, Miguel; Villar, Juan C

2017-11-28

The effect of the addition of two [4-butyltrimethylammonium]-xylan chloride polyelectrolytes (BTMAXs) on bacterial cellulose (BC) was evaluated. The first strategy was to add the polyelectrolytes to the culture medium together with a cell suspension of the bacterium. After one week of cultivation, the films were collected and purified. The second approach consisted of obtaining a purified and homogenized BC, to which the polyelectrolytes were added subsequently. The films were characterized in terms of tear and burst indexes, optical properties, surface free energy, static contact angle, Gurley porosity, SEM, X-ray diffraction and AFM. Although there are small differences in mechanical and optical properties between the nanocomposites and control films, the films obtained by BC synthesis in the presence of BTMAXs were remarkably less opaque, rougher, and had a much lower specular gloss. The surface free energy depends on the BTMAXs addition method. The crystallinity of the composites is lower than that of the control material, with a higher reduction of this parameter in the composites obtained by adding the BTMAXs to the culture medium. In view of these results, it can be concluded that BC-BTMAX composites are a promising new material, for example, for paper restoration.

Simultaneous microwave-assisted synthesis, characterization, thermal stability, and antimicrobial activity of cellulose/AgCl nanocomposites

International Nuclear Information System (INIS)

Li, Shu-Ming; Fu, Lian-Hua; Ma, Ming-Guo; Zhu, Jie-Fang; Sun, Run-Cang; Xu, Feng

2012-01-01

By means of a simultaneous microwave-assisted method and a simple chemical reaction, cellulose/AgCl nanocomposites have been successfully synthesized using cellulose solution and AgNO 3 in N,N-dimethylacetamide (DMAc) solvent. The cellulose solution was firstly prepared by the dissolution of the microcrystalline cellulose and lithium chloride (LiCl) in DMAc. DMAc acts as both a solvent and a microwave absorber. LiCl was used as the reactant to fabricate AgCl crystals. The effects of the heating time and heating temperature on the products were studied. This method is based on the simultaneous formation of AgCl nanoparticles and precipitation of the cellulose, leading to a homogeneous distribution of AgCl nanoparticles in the cellulose matrix. The experimental results confirmed the formation of cellulose/AgCl nanocomposites with high-purity, good thermal stability and antimicrobial activity. This rapid, green and environmentally friendly microwave-assisted method opens a new window to the high value-added applications of biomass. -- Highlights: ► Cellulose/AgCl nanocomposites have been synthesized by microwave method. ► Effect of heating temperature on the nanocomposites was researched. ► Thermal stability of the nanocomposites was investigated. ► Cellulose/AgCl nanocomposites had good antimicrobial activity. ► This method is based on the simultaneous formation of AgCl and cellulose.

Antimicrobial bacterial cellulose nanocomposites prepared by in situ polymerization of 2-aminoethyl methacrylate.

Science.gov (United States)

Figueiredo, Ana R P; Figueiredo, Andrea G P R; Silva, Nuno H C S; Barros-Timmons, Ana; Almeida, Adelaide; Silvestre, Armando J D; Freire, Carmen S R

2015-06-05

Antimicrobial bacterial cellulose/poly(2-aminoethyl methacrylate) (BC/PAEM) nanocomposites were prepared by in situ radical polymerization of 2-aminoethyl methacrylate, using variable amounts of N,N-methylenebis(acrylamide) (MBA) as cross-linker. The obtained nanocomposites were characterized in terms of their structure, morphology, thermal stability, mechanical properties and antibacterial activity. The ensuing composite membranes were significantly more transparent than those of pure BC and showed improved thermal and mechanical properties. The antibacterial activity of the obtained nanocomposites was assessed towards a recombinant bioluminescent Escherichia coli and only the non-crosslinked nanocomposite (BC/PAEM) proved to have antibacterial activity. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evolving Microbial Communities in Cellulose-Fed Microbial Fuel Cell

Directory of Open Access Journals (Sweden)

Renata Toczyłowska-Mamińska

2018-01-01

Full Text Available The abundance of cellulosic wastes make them attractive source of energy for producing electricity in microbial fuel cells (MFCs. However, electricity production from cellulose requires obligate anaerobes that can degrade cellulose and transfer electrons to the electrode (exoelectrogens, and thus most previous MFC studies have been conducted using two-chamber systems to avoid oxygen contamination of the anode. Single-chamber, air-cathode MFCs typically produce higher power densities than aqueous catholyte MFCs and avoid energy input for the cathodic reaction. To better understand the bacterial communities that evolve in single-chamber air-cathode MFCs fed cellulose, we examined the changes in the bacterial consortium in an MFC fed cellulose over time. The most predominant bacteria shown to be capable electron generation was Firmicutes, with the fermenters decomposing cellulose Bacteroidetes. The main genera developed after extended operation of the cellulose-fed MFC were cellulolytic strains, fermenters and electrogens that included: Parabacteroides, Proteiniphilum, Catonella and Clostridium. These results demonstrate that different communities evolve in air-cathode MFCs fed cellulose than the previous two-chamber reactors.

Microcrystalline identification of selected designer drugs.

Science.gov (United States)

Elie, Leonie; Baron, Mark; Croxton, Ruth; Elie, Mathieu

2012-01-10

A microcrystalline test for the detection of 4-methylmethcathinone (mephedrone), benzylpiperazine (BZP) and 5,6-methylenedioxy-2-aminoindane (MDAI) using aqueous solutions of mercury chloride is described. Each of the compounds investigated formed specific drug-reagent crystals within minutes. The uniqueness of the test was confirmed by comparison of the microcrystalline response to that of other psychoactive stimulants and a common cutting agent. The limit of detection and cut-off levels for reference standards were established to 3 g/L and 5 g/L for mephedrone, 0.5 g/L for MDAI and 0.2 g/L and 0.3 g/L for BZP, respectively. Various mixtures of standards of either mephedrone, BZP or MDAI combined with caffeine were investigated for their microcrystalline response. Results showed that simultaneous detection of drug and cutting agent was possible with the concentrations tested but were dependant on the ratio of drug to cutting agent. BZP could be detected alongside caffeine from as low as 20% (v/v), MDAI from 40% (v/v) and mephedrone from 50% (v/v) and higher. Finally, seven samples of online purchased 'legal highs' were analysed using the developed test and the findings were compared to FTIR and GC-MS results. It was shown that 6 out of 7 samples did not contain the advertised active ingredient. Five samples consisted of BZP, caffeine and 1-[3-(trifluoromethyl)phenyl]piperazine (3-TFMPP). The microcrystalline tests carried out on these samples showed positive results for both BZP and caffeine without interference from other substances present. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Embedding of bacterial cellulose nanofibers within PHEMA hydrogel matrices: tunable stiffness composites with potential for biomedical applications

Czech Academy of Sciences Publication Activity Database

Hobzová, Radka; Hrib, Jakub; Širc, Jakub; Karpushkin, Evgeny; Michálek, Jiří; Janoušková, Olga; Gatenholm, P.

2018-01-01

Roč. 2018, 17 January (2018), s. 1-11, č. článku 5217095. ISSN 1687-4110 R&D Projects: GA ČR(CZ) GA16-04863S; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : bacterial cellulose * PHEMA * biomedical application Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 1.871, year: 2016

Fermentation Tecniques and Applications of Bacterial Cellulose: a Review Técnicas de fermentación y aplicaciones de la celulosa bacteriana: una revisión

OpenAIRE

Luz Dary Carreño Pineda; Luis Alfonso Caicedo Mesa; Carlos Arturo Martínez Riascos

2012-01-01

Bacterial cellulose is a polymer obtained by fermentation with microorganismsfrom Acetobacter, Rhizobium, Agrobacterium and Sarcina genera. Amongthem, Acetobacter xylinum is the most efficient specie. This polymer hasthe same chemical composition of plant cellulose, but its conformation andphysicochemical properties are different, making it attractive for several applications, especially in the areas of food, separation processes, catalysis andhealth, due to its biocompatibility. However, the ma...

Cellulose Synthesis in Agrobacterium tumefaciens

Energy Technology Data Exchange (ETDEWEB)

Alan R. White; Ann G. Matthysse

2004-07-31

We have cloned the celC gene and its homologue from E. coli, yhjM, in an expression vector and expressed the both genes in E. coli; we have determined that the YhjM protein is able to complement in vitro cellulose synthesis by extracts of A. tumefaciens celC mutants, we have purified the YhjM protein product and are currently examining its enzymatic activity; we have examined whole cell extracts of CelC and various other cellulose mutants and wild type bacteria for the presence of cellulose oligomers and cellulose; we have examined the ability of extracts of wild type and cellulose mutants including CelC to incorporate UDP-14C-glucose into cellulose and into water-soluble, ethanol-insoluble oligosaccharides; we have made mutants which synthesize greater amounts of cellulose than the wild type; and we have examined the role of cellulose in the formation of biofilms by A. tumefaciens. In addition we have examined the ability of a putative cellulose synthase gene from the tunicate Ciona savignyi to complement an A. tumefaciens celA mutant. The greatest difference between our knowledge of bacterial cellulose synthesis when we started this project and current knowledge is that in 1999 when we wrote the original grant very few bacteria were known to synthesize cellulose and genes involved in this synthesis were sequenced only from Acetobacter species, A. tumefaciens and Rhizobium leguminosarum. Currently many bacteria are known to synthesize cellulose and genes that may be involved have been sequenced from more than 10 species of bacteria. This additional information has raised the possibility of attempting to use genes from one bacterium to complement mutants in another bacterium. This will enable us to examine the question of which genes are responsible for the three dimensional structure of cellulose (since this differs among bacterial species) and also to examine the interactions between the various proteins required for cellulose synthesis. We have carried out one

Application of Molecular Techniques to Elucidate the Influence of Cellulosic Waste on the Bacterial Community Structure at a Simulated Low-Level-Radioactive-Waste Site

International Nuclear Information System (INIS)

Field, Erin K.; D'Imperio, Seth; Miller, Amber R.; VanEngelen, Michael R.; Gerlach, Robin; Lee, Brady D.; Apel, William A.; Peyton, Brent M.

2010-01-01

Low-level radioactive waste sites, including those at various U.S. Department of Energy (DOE) sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a non-radioactive model low-level waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rDNA clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both the clone library and PhyloChip results revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more unique Operational Taxonomic Units (OTUs), and therefore more relative diversity, than the clone libraries. Calculated diversity indices suggest that diversity is lowest in the Fill (F) and Fill Waste (FW) layers and greater in the Wood Waste (WW) and Waste Clay (WC) layers. Principal coordinates analysis and lineage specific analysis determined that Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulose degrading microorganisms suggests the FW layer is an enrichment environment for cellulose degradation. Overall, these results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system.

Preparation of Pd/Bacterial Cellulose Hybrid Nanofibers for Dopamine Detection

Directory of Open Access Journals (Sweden)

Dawei Li

2016-05-01

Full Text Available Palladium nanoparticle-bacterial cellulose (PdBC hybrid nanofibers were synthesized by in-situ chemical reduction method. The obtained PdBC nanofibers were characterized by a series of analytical techniques. The results revealed that Pd nanoparticles were evenly dispersed on the surfaces of BC nanofibers. Then, the as-prepared PdBC nanofibers were mixed with laccase (Lac and Nafion to obtain mixture suspension, which was further modified on electrode surface to construct novel biosensing platform. Finally, the prepared electrochemical biosensor was employed to detect dopamine. The analysis result was satisfactory, the sensor showed excellent electrocatalysis towards dopamine with high sensitivity (38.4 µA·mM−1, low detection limit (1.26 µM, and wide linear range (5–167 µM. Moreover, the biosensor also showed good repeatability, reproducibility, selectivity and stability and was successfully used in the detection of dopamine in human urine, thus providing a promising method for dopamine analysis in clinical application.

Novel Cu@SiO{sub 2}/bacterial cellulose nanofibers: Preparation and excellent performance in antibacterial activity

Energy Technology Data Exchange (ETDEWEB)

Ma, Bo [Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094 (China); Department of Life Sciences of Lianyungang Teacher' s College, Sheng Hu Lu 28, Lianyungang 222006 (China); Huang, Yang; Zhu, Chunlin; Chen, Chuntao; Chen, Xiao; Fan, Mengmeng [Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094 (China); Sun, Dongping, E-mail: sundpe301@163.com [Chemicobiology and Functional Materials Institute of Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094 (China)

2016-05-01

The antibacterial composite based on bacterial cellulose (BC) was successfully prepared by in-situ synthesis of SiO{sub 2} coated Cu nanoparticles (Cu@SiO{sub 2}/BC) and its properties were characterized. Its chemical structures and morphologies were evaluated by Fourier transformation infrared spectrum (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The results demonstrated that the SiO{sub 2} coated Cu particles were well homogeneously precipitated on the surface of BC. The Cu@SiO{sub 2}/BC was more resistant to oxidation than the Cu nanoparticles impregnated into BC (Cu/BC) and then Cu@SiO{sub 2}/BC could prolong the antimicrobial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). - Graphical abstract: Schematic illustration of the preparation of Cu@SiO{sub 2}/BC. Due to its unique structure, the Cu@SiO{sub 2}/BC membrane shows excellent antibacterial effects and can be used for a long time. - Highlights: • This work paves the novel way to fabricate antibacterial nanomaterial with good efficiency. • We prepare the antibacterial membrane based on bacterial cellulose by in-situ synthesis of SiO{sub 2}-coated Cu nanoparticles. • The antibacterial membrane is more resistant to oxidation and can prolong the antimicrobial activity.

Production of bioplastic from jackfruit seed starch (Artocarpus heterophyllus) reinforced with microcrystalline cellulose from cocoa pod husk (Theobroma cacao L.) using glycerol as plasticizer

Science.gov (United States)

Lubis, M.; Gana, A.; Maysarah, S.; Ginting, M. H. S.; Harahap, M. B.

2018-02-01

The production of bioplastic from jackfruit seed starch reinforced with microcrystalline cellulose (MCC) cocoa pod husk using glycerol as plasticizer was investigated to determine the most optimum mass and volume of MCC and glycerol in producing bioplastics. To produce MCC, Cocoa pod husk was subjected to alkali treatment, bleaching, and hydrochloric acid hydrolysis. The degree of crystallinity of MCC, were determined by XRD, functional group by FT-IR and morphologycal analysis by SEM. Analysis of bioplastic mechanical properties includes tensile strength and elongation at break based on ASTM D882 standard. Bioplastics were produced by casting method from jackfruit seed starch and reinforced with MCC from cocoa pod husk at starch mass to MCC ratio of 6:4, 7:3, 8:2, and 9:1, using glycerol as plasticizer at 20%, 25%, 30% (wt/v of glycerol to starch). From the result, the isolated MCC from cocoa pod husk were in a form of rod-like shape of length 5-10 µm with diameter 11.635 nm and 74% crystallinity. The highest tensile strength of bioplastics was obtained at starch to MCC mass ratio of 8:2, addition of 20% glycerol with measured tensile strength of 0.637 MPa and elongation at break of 7.04%. Transform infrared spectroscopy showed the functional groups of bioplastics, which the majority of O-H groups were found at the bioplastics with reinforcing filler MCC that represented substantial hydrogen bonds.

Modification of Bacterial Cellulose Biofilms with Xylan Polyelectrolytes

Directory of Open Access Journals (Sweden)

Sara M. Santos

2017-11-01

Full Text Available The effect of the addition of two [4-butyltrimethylammonium]-xylan chloride polyelectrolytes (BTMAXs on bacterial cellulose (BC was evaluated. The first strategy was to add the polyelectrolytes to the culture medium together with a cell suspension of the bacterium. After one week of cultivation, the films were collected and purified. The second approach consisted of obtaining a purified and homogenized BC, to which the polyelectrolytes were added subsequently. The films were characterized in terms of tear and burst indexes, optical properties, surface free energy, static contact angle, Gurley porosity, SEM, X-ray diffraction and AFM. Although there are small differences in mechanical and optical properties between the nanocomposites and control films, the films obtained by BC synthesis in the presence of BTMAXs were remarkably less opaque, rougher, and had a much lower specular gloss. The surface free energy depends on the BTMAXs addition method. The crystallinity of the composites is lower than that of the control material, with a higher reduction of this parameter in the composites obtained by adding the BTMAXs to the culture medium. In view of these results, it can be concluded that BC–BTMAX composites are a promising new material, for example, for paper restoration.

Microfibrillated cellulose and new nanocomposite materials: a review

DEFF Research Database (Denmark)

Siró, Istvan; Plackett, David

2010-01-01

Due to their abundance, high strength and stiffness, low weight and biodegradability, nano-scale cellulose fiber materials (e.g., microfibrillated cellulose and bacterial cellulose) serve as promising candidates for bio-nanocomposite production. Such new high-value materials are the subject...... in order to address this hurdle. This review summarizes progress in nanocellulose preparation with a particular focus on microfibrillated cellulose and also discusses recent developments in bio-nanocomposite fabrication based on nanocellulose....

Investigation into the suitability of capillary tubes for microcrystalline testing.

Science.gov (United States)

Elie, Leonie E; Baron, Mark G; Croxton, Ruth S; Elie, Mathieu P

2013-07-01

A comparison between microcrystalline tests performed on microscope slides and flat capillary tubes with inner diameters ranging from 0.1 to 0.7 mm was carried out to explore the appropriateness of tubes for rapid testing of suspected drugs of abuse in the laboratory as well as in the field. Tests for mephedrone, cocaine, and phencyclidine were chosen as examples to investigate the handling of the capillary tubes, the influence on crystal habit, size, and the effects on the limit of detection. Image stacking software was used to increase the depth of field of micrographs taken from developed microcrystals greatly enhancing the interpretability even months after carrying out the microcrystalline test. Additionally, the potential of seeding capillary tubes with a reagent was studied. Pre-treatment of tubes would allow microcrystalline tests to be carried out quicker and anywhere without the necessity of taking along expensive and hazardous reagents. The sealing of capillary tubes containing developed microcrystalline tests in order to preserve results for a long period of time was successfully done by applying paraffin wax to the open ends. Finally, it was concluded that capillary tubes are suitable vessels for performing microcrystalline tests. The increased portability of the improved set-up allows tests to be safely executed outside laboratories without impairing the quality of the result. Findings were applied to six legal high samples purchased online between May and August 2011. The active ingredients like MDAI as well as cutting agents like caffeine were successfully identified using the microcrystalline test technique in capillary tubes. Copyright © 2012 John Wiley & Sons, Ltd.

Thin stillage supplementation greatly enhances bacterial cellulose production by Gluconacetobacter xylinus.

Science.gov (United States)

Wu, Jyh-Ming; Liu, Ren-Han

2012-09-01

Thin stillage (TS), a wastewater from rice wine distillery can well sustain the growth of Gluconacetobacter xylinus for production of bacterial cellulose (BC). When used as a supplement to the traditional BC production medium (Hestrin and Schramm medium), the enhancement of BC production increased with the amount of TS supplemented in a static culture of G. xylinus. When TS was employed to replace distilled water for preparing HS medium (100%TS-HS medium), the BC production in this 100%TS-HS medium was enhanced 2.5-fold to a concentration of 10.38 g/l with sugar to BC conversion yield of 57% after 7 days cultivation. The cost-free TS as a supplement in BC production medium not only can greatly enhance the BC production, but also can effectively dispose the nuisance wastewater of rice wine distillery. Copyright © 2012 Elsevier Ltd. All rights reserved.

In situ synthesis of silver chloride nanoparticles into bacterial cellulose membranes

International Nuclear Information System (INIS)

Hu Weili; Chen Shiyan; Li Xin; Shi Shuaike; Shen Wei; Zhang Xiang; Wang Huaping

2009-01-01

In situ synthesis of silver chloride (AgCl) nanoparticles was carried out under ambient conditions in nanoporous bacterial cellulose (BC) membranes as nanoreactors. The growth of the nanoparticles was readily obtained by alternating dipping of BC membranes in the solution of silver nitrate or sodium chloride followed by a rinse step. X-ray diffraction (XRD) patterns indicated the existence of AgCl nanoparticles in the BC and scanning electron microscopy (SEM) images showed that the AgCl nanoparticles well dispersed on the surface of BC and penetrated into the BC network. The AgCl nanoparticle-impregnated BC membranes exhibited high hydrophilic ability and strong antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The preparative procedure is facile and versatile, and provides a simple route to manufacturing of useful antimicrobial membranes, which would be a good alternative for antimicrobial wound dressing.

Simple preparation of Fenton catalyst@bacterial cellulose for waste water treatment

Science.gov (United States)

Wibowo, Arie; Febi Indrawan, Radian; Triadhi, Untung; Hasdi Aimon, Akfiny; Iskandar, Ferry; Ardy, Husaini

2018-02-01

Heterogeneous fenton catalyst is one of the attractive technologies for destruction of persistent and non-biodegradable pollutant in wastewater, because it can be used in wide range of pH and recyclable. Herein, commercial bacterial celluloses (BCs) were used as an alternative support of fenton catalyst to improve their catalytic activity. Scanning Electron Microscope (SEM) observations indicated that the presence of BCs and decreasing precursor concentration might promote formation of smaller particle sizes of catalyst from 3.5 μm of bare catalyst to 0.7 μm of catalyst@BC. UV-vis measurement showed that fast degradation of dyes with half-time degradation at around 25 min was observed in sample using catalyst@BCs with precursor concentration of 0.01 M. Successful preparation of heterogeneous fenton catalyst with smaller particle size and better catalytic activity is important for their application in wastewater treatment.

Plasma processing of microcrystalline silicon films : filling in the gaps

NARCIS (Netherlands)

Bronneberg, A.C.

2012-01-01

Hydrogenated microcrystalline silicon (µc-Si:H) is a mixed-phase material consisting of crystalline silicon grains, hydrogenated amorphous silicon (a-Si:H) tissue, and voids. Microcrystalline silicon is extensively used as absorber layer in thin-film tandem solar cells, combining the advantages of a

Cellulose nanocrystal properties and their applications

Directory of Open Access Journals (Sweden)

mahdi jonoobi

2015-05-01

Full Text Available The main purpose of this work is to provide an overview of recent research in the area of cellulose nonmaterials production from different sources. Due to their abundance, their renewability, high strength and stiffness, being eco-friendly, and low weight; numerous studies have been reported on the isolation of cellulose nanomaterials from different cellulosic sources and their use in high performance applications. This work covers an introduction into the nano cellulose definition as well as used methods for isolation of nanomaterials (nanocrystals from various sources. The rod-like cellulose nanocrystals (CNC can be isolated from sources like wood, plant fibers, agriculture and industrial bio residues, tunicates, and bacterial cellulose using acid hydrolysis process. Following this, the paper focused on characterization methods, materials properties and structure. The current review is a comprehensive literature regarding the nano cellulose isolation and demonstrates the potential of cellulose nanomaterials to be used in a wide range of high-tech applications.

The operable modeling of simultaneous saccharification and fermentation of ethanol production from cellulose.

Science.gov (United States)

Shen, Jiacheng; Agblevor, Foster A

2010-03-01

An operable batch model of simultaneous saccharification and fermentation (SSF) for ethanol production from cellulose has been developed. The model includes four ordinary differential equations that describe the changes of cellobiose, glucose, yeast, and ethanol concentrations with respect to time. These equations were used to simulate the experimental data of the four main components in the SSF process of ethanol production from microcrystalline cellulose (Avicel PH101). The model parameters at 95% confidence intervals were determined by a MATLAB program based on the batch experimental data of the SSF. Both experimental data and model simulations showed that the cell growth was the rate-controlling step at the initial period in a series of reactions of cellulose to ethanol, and later, the conversion of cellulose to cellobiose controlled the process. The batch model was extended to the continuous and fed-batch operating models. For the continuous operation in the SSF, the ethanol productivities increased with increasing dilution rate, until a maximum value was attained, and rapidly decreased as the dilution rate approached the washout point. The model also predicted a relatively high ethanol mass for the fed-batch operation than the batch operation.

Phase distribution of products of radiation and post-radiation distillation of biopolymers: Cellulose, lignin and chitin

International Nuclear Information System (INIS)

Ponomarev, A.V.; Kholodkova, E.M.; Metreveli, A.K.; Metreveli, P.K.; Erasov, V.S.; Bludenko, A.V.; Chulkov, V.N.

2011-01-01

Influence of both the absorbed dose and the dose rate of 8 MeV electron-beam radiation on destruction of microcrystalline cellulose, pine lignin and krill chitin was investigated. Two conversion modes were compared: (1) post-radiation distillation PRD and (2) electron-beam distillation EBD. Cellulose, chitin and lignin demonstrate different responses to irradiation and distillation in PRD and EBD modes. Treatment in EBD mode transforms biopolymers to organic liquid more productively than conventional dry distillation and treatment in PRD mode. Both radiation heating and an irradiation without heating intensify chitin and cellulose decomposition and distillation. At the same time lignin decaying rather efficiently in EBD mode appears to be insensitive to a preliminary irradiation in PRD mode up to a dose of 2.4 MGy. - Highlights: → Direct conversion of cellulose, chitin and lignin to organic liquid is intensified by electron-beam irradiation. → Alternative approach to bio-oil production. → Both electron-beam distillation mode and post-radiation distillation mode are effective for cellulose and chitin conversion. → Electron-beam distillation mode is preferable for lignin conversion. → Preliminary deep dehydration of biopolymers is realizable at low dose rates.

Functionality of innovative and generic celluloses in metronidazole formulations

Directory of Open Access Journals (Sweden)

Carmen Cristina Díaz Ramírez

2011-03-01

Full Text Available The wide variety of excipients available calls for evaluation of their functionality, in this case of the pharmaceutical performance of microcrystalline celluloses and sodium cross-linked carboxymethylcelluloses from different sources. This evaluation includes parameters such as powder flow, compactibility, ejection pressure and dissolution from fast-release tablets as well as from floating granules and controlled-release tablets. In a previous study, the excipient Carmacel® presented better disintegration properties compared to Croscarmellose®. However, the evaluation showed better compactibility performance for Croscarmellose®. These characteristics were observed using pure excipients. Nevertheless, these advantages have not been confirmed in tests employing immediate-release or modified-release formulations containing metronidazole. Regarding microcrystalline celluloses, the present comparative evaluation between pure Alfacel ® types 101 and 102 and pure Avicel® types 101 and 102 showed better compactibility performance for the latter. However, for metronidazole formulations, this advantage was not evident in the innovative excipient. Notwithstanding, this study revealed better compactibility performance of microcrystalline cellulose type 101. In terms of powder flow properties, Avicel® and Alfacel® showed similar performance. However, the results revealed better powder flow employing microcrystalline cellulose type 102 for both excipients. Based on the results obtained, it can be concluded that the employment of innovative and generic excipients have both advantages and disadvantages. The observed differences however, tend to disappear as the excipients are diluted in a formulation, thereby equalizing their influence on product performance.A variedade de excipientes disponível no mercado requer adequada seleção desses no que se refere à sua funcionalidade, como no caso de celuloses microcristalinas (Avicel® 101 e 102 e Alfacel

Low power high growth rate deposition of microcrystalline silicon

OpenAIRE

Feltrin, A; Bugnon, G; Meillaud, F; Bailat, J; Ballif, C

2008-01-01

Microcrystalline growth regimes and solar cells obtained in different pressure and silane depletion conditions are studied in a large area KAI-S plasma reactor. The microcrystalline material quality is systematically investigated by Fourier Transform Photocurrent Spectroscopy (FTPS) to evaluate the defect density. It is shown that higher pressure and silane depletion positively affect the material quality. A clear correlation between FTPS measurements and cell efficiency is established, showi...

Influence of ambient moisture on the compaction behavior of microcrystalline cellulose powder undergoing uni-axial compression and roller-compaction: a comparative study using near-infrared spectroscopy.

Science.gov (United States)

Gupta, Abhay; Peck, Garnet E; Miller, Ronald W; Morris, Kenneth R

2005-10-01

This study evaluates the effect of variation in the ambient moisture on the compaction behavior of microcrystalline cellulose (MCC) powder. The study was conducted by comparing the physico-mechanical properties of, and the near infrared (NIR) spectra collected on, compacts prepared by roller compaction with those collected on simulated ribbons, that is, compacts prepared under uni-axial compression. Relative density, moisture content, tensile strength (TS), and Young modulus were used as key sample attributes for comparison. Samples prepared at constant roller compactor settings and feed mass showed constant density and a decrease in TS with increasing moisture content. Compacts prepared under uni-axial compression at constant pressure and compact mass showed the opposite effect, that is, density increased while TS remained almost constant with increasing moisture content. This suggests difference in the influence of moisture on the material under roller compaction, in which the roll gap (i.e., thickness and therefore density) remains almost constant, vs. under uni-axial compression, in which the thickness is free to change in response to the applied pressure. Key sample attributes were also related to the NIR spectra using multivariate data analysis by the partial least squares projection to latent structures (PLS). Good agreement was observed between the measured and the NIR-PLS predicted values for all key attributes for both, the roller compacted samples as well as the simulated ribbons. Copyright (c) 2005 Wiley-Liss, Inc. and the American Pharmacists Association

Production of Starch Based Bioplastic from Cassava Peel Reinforced with Microcrystalline Celllulose Avicel PH101 Using Sorbitol as Plasticizer

Science.gov (United States)

Maulida; Siagian, M.; Tarigan, P.

2016-04-01

The production of starch based bioplastics from cassava peel reeinforced with microcrystalline cellulose using sorbitol as plasticizer were investigated. Physical properties of bioplastics were determined by density, water uptake, tensile strength and Fourier Transform Infrared Spectroscopy. Bioplastics were prepared from cassava peel starch plasticized using sorbitol with variation of 20; 25; 30% (wt/v of sorbitol to starch) reinforced with microcrystalline celllulose (MCC) Avicel PH101 fillers with range of 0 to 6% (wt/wt of MCC to starch). The results showed improvement in tensile strength with higher MCC content up to 9, 12 mpa compared to non-reinforced bioplastics. This could be mainly attributed to the strong hydrogen bonds between MCC and starch. On the contrary, the addition of MCC decreased the elongation at break, density and water uptake. Fourier Transform Infrared Spectroscopy showed the functional groups of bioplastics, which the majority of O-H groups were found at the bioplastics with reinforcing filler MCC that represented substantial hydrogen bonds. The highest tensile strength value was obtained for bioplastic with MCC content 6% and sorbitol content 20%. With good adhesion between MCC and starch the production of bioplastics could be widely used as a substitute for conventional plastics with more benefits to the environment.

Production of Starch Based Bioplastic from Cassava Peel Reinforced with Microcrystalline Celllulose Avicel PH101 Using Sorbitol as Plasticizer

International Nuclear Information System (INIS)

Maulida; Siagian, M; Tarigan, P

2016-01-01

The production of starch based bioplastics from cassava peel reeinforced with microcrystalline cellulose using sorbitol as plasticizer were investigated. Physical properties of bioplastics were determined by density, water uptake, tensile strength and Fourier Transform Infrared Spectroscopy. Bioplastics were prepared from cassava peel starch plasticized using sorbitol with variation of 20; 25; 30% (wt/v of sorbitol to starch) reinforced with microcrystalline celllulose (MCC) Avicel PH101 fillers with range of 0 to 6% (wt/wt of MCC to starch). The results showed improvement in tensile strength with higher MCC content up to 9, 12 mpa compared to non-reinforced bioplastics. This could be mainly attributed to the strong hydrogen bonds between MCC and starch. On the contrary, the addition of MCC decreased the elongation at break, density and water uptake. Fourier Transform Infrared Spectroscopy showed the functional groups of bioplastics, which the majority of O-H groups were found at the bioplastics with reinforcing filler MCC that represented substantial hydrogen bonds. The highest tensile strength value was obtained for bioplastic with MCC content 6% and sorbitol content 20%. With good adhesion between MCC and starch the production of bioplastics could be widely used as a substitute for conventional plastics with more benefits to the environment. (paper)

Preparation and Characterization of Jute Cellulose Crystals-Reinforced Poly(L-lactic acid Biocomposite for Biomedical Applications

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Mohammed Mizanur Rahman

2014-01-01

Full Text Available Crystalline cellulose was extracted from jute by hydrolysis with 40% H2SO4 to get mixture of micro/nanocrystals. Scanning electron microscope (SEM showed the microcrystalline structure of cellulose and XRD indicated the Iβ polymorph of cellulose. Biodegradable composites were prepared using crystalline cellulose (CC of jute as the reinforcement (3–15% and poly(lactic acid (PLA as a matrix by extrusion and hot press method. CC was cellulose derived from mercerized and bleached jute fiber by acid hydrolysis to remove the amorphous regions. FT-IR studies showed hydrogen bonding between the CC and the PLA matrix. The X-ray diffraction (XRD and differential scanning calorimetry (DSC studies showed that the percentage crystallinity of PLA in composites was found to be higher than that of neat PLA as a result of the nucleating ability of the crystalline cellulose. Furthermore, Vicker hardness and yield strength were found to increase with increasing cellulose content in the composite. The SEM images of the fracture surfaces of the composites were indicative of poor adhesion between the CC and the PLA matrix. The composite with 15% CC showed antibacterial effect though pure films but had no antimicrobial effect; on the other hand its cytotoxicity in biological medium was found to be medium which might be suitable for its potential biomedical applications.

On the compressibility of TiC in microcrystalline and nanoparticulate form

International Nuclear Information System (INIS)

Gu, Q F; Krauss, G; Steurer, W; Gramm, F

2008-01-01

The compressibility of TiC in microcrystalline and nanoparticulate (30-50 nm) form was studied by in situ high-pressure synchrotron radiation x-ray diffraction measurements up to 53.7 GPa using a diamond anvil cell. Both materials are structurally stable within the framework of the experiments applying quasihydrostatic pressure conditions. Under nonhydrostatic pressure conditions, the lattice of microcrystalline TiC is rhombohedrally distorted. Comparable values for the bulk modulus were found for both materials, i.e. K 0 = 254(7) GPa, K' = 4.8(4) for microcrystalline TiC and K 0 = 276(14) GPa, K' = 3.5(8) for nanoparticulate TiC, respectively. High-resolution transmission electron microscopy investigations revealed a nearly single-domain microstructure of the nanoparticles. The microstructure and size of the nanoparticles, making a size-induced effect on the mechanical properties negligible, explain well the observed similarity of the mechanical properties of microcrystalline and nanoparticulate TiC.

Surface Photochemistry: Benzophenone as a Probe for the Study of Modified Cellulose Fibres

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L. F. Vieira Ferreira

2007-01-01

Full Text Available This work reports the use of benzophenone, a very well characterized probe, to study new hosts (i.e., modified celluloses grafted with alkyl chains bearing 12 carbon atoms by surface esterification. Laser-induced room temperature luminescence of air-equilibrated or argon-purged solid powdered samples of benzophenone adsorbed onto the two modified celluloses, which will be named C12-1500 and C12-1700, revealed the existence of a vibrationally structured phosphorescence emission of benzophenone in the case where ethanol was used for sample preparation, while a nonstructured emission of benzophenone exists when water was used instead of ethanol. The decay times of the benzophenone emission vary greatly with the solvent used for sample preparation and do not change with the alkylation degree in the range of 1500–1700 micromoles of alkyl chains per gram of cellulose. When water was used as a solvent for sample preparation, the shortest lifetime for the benzophenone emission was observed; this result is similar to the case of benzophenone adsorbed onto the “normal” microcrystalline cellulose surface, with this latter case previously reported by Vieira Ferreira et al. in 1995. This is due to the more efficient hydrogen abstraction reaction from the glycoside rings of cellulose when compared with hydrogen abstraction from the alkyl chains of the modified celluloses. Triplet-triplet transient absorption of benzophenone was obtained in both cases and is the predominant absorption immediately after laser pulse, while benzophenone ketyl radical formation occurs in a microsecond time scale both for normal and modified celluloses.

NMR relaxometric probing of ionic liquid dynamics and diffusion under mesoscopic confinement within bacterial cellulose ionogels

Science.gov (United States)

Smith, Chip J.; Gehrke, Sascha; Hollóczki, Oldamur; Wagle, Durgesh V.; Heitz, Mark P.; Baker, Gary A.

2018-05-01

Bacterial cellulose ionogels (BCIGs) represent a new class of material comprising a significant content of entrapped ionic liquid (IL) within a porous network formed from crystalline cellulose microfibrils. BCIGs suggest unique opportunities in separations, optically active materials, solid electrolytes, and drug delivery due to the fact that they can contain as much as 99% of an IL phase by weight, coupled with an inherent flexibility, high optical transparency, and the ability to control ionogel cross-sectional shape and size. To allow for the tailoring of BCIGs for a multitude of applications, it is necessary to better understand the underlying principles of the mesoscopic confinement within these ionogels. Toward this, we present a study of the structural, relaxation, and diffusional properties of the ILs, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpy][Tf2N]), using 1H and 19F NMR T1 relaxation times, rotational correlation times, and diffusion ordered spectroscopy (DOSY) diffusion coefficients, accompanied by molecular dynamics (MD) simulations. We observed that the cation methyl groups in both ILs were primary points of interaction with the cellulose chains and, while the pore size in cellulose is rather large, [emim]+ diffusion was slowed by ˜2-fold, whereas [Tf2N]- diffusion was unencumbered by incorporation in the ionogel. While MD simulations of [bmpy][Tf2N] confinement at the interface showed a diffusion coefficient decrease roughly 3-fold compared to the bulk liquid, DOSY measurements did not reveal any significant changes in diffusion. This suggests that the [bmpy][Tf2N] alkyl chains dominate diffusion through formation of apolar domains. This is in contrast to [emim][Tf2N] where delocalized charge appears to preclude apolar domain formation, allowing interfacial effects to be manifested at a longer range in [emim][Tf2N].

Optical and electronic properties of microcrystalline silicon as a function of microcrystallinity

International Nuclear Information System (INIS)

Han, Daxing; Yue, Guozhen; Lorentzen, J. D.; Lin, Jing; Habuchi, H.; Wang, Qi

2000-01-01

Films were prepared by hot wire chemical vapor deposition at ∼240 degree sign C with varied hydrogen dilution ratios R=H 2 :SiH 4 from 1 to 20. The optical and electronic properties as a function of microcrystallinity were studied. We found: (a) At low H dilution R≤2, there is no measurable crystallinity by Raman spectroscopy and x-ray diffraction in the a-Si:H matrix, but an optical absorption peak at ∼1.25 eV appears; when R=2, the film shows the lowest subgap absorption, the highest photosensitivity, and the largest optical gap. (b) When R≥3, the c-Si phase is measurable by Raman and a low-energy photoluminescence (PL) band (0.84-1.0 eV) appears in addition to the high-energy band (1.3-1.4 eV). Meanwhile, all the absorption spectra show a featureless line shape. (c) An energy redshift is observed for both PL peaks as the film grows thicker. Finally, (d) the conductivity activation energy first decreases from 0.68 to 0.12 eV, then increases with increasing microcrystallinity. A mode of two sets of energy bands of electronic states for these two-phase materials is suggested. (c) 2000 American Institute of Physics

Biomimetic synthesis of hydroxyapatite/bacterial cellulose nanocomposites for biomedical applications

International Nuclear Information System (INIS)

Wan, Y.Z.; Huang, Y.; Yuan, C.D.; Raman, S.; Zhu, Y.; Jiang, H.J.; He, F.; Gao, C.

2007-01-01

Hydroxyapatite (HAp) and bacterial cellulose (BC) are both excellent materials for use in biomaterial areas. The former has outstanding osteoconductivity and bioactivity and the latter is a high-strength nano-fibrous and extensively used biomaterial. In this work, the HAp/BC nanocomposites with a 3-dimensional (3-D) network were synthesized via a biological route by soaking both phosphorylated and unphosphorylated BCs in 1.5 simulated body fluid (SBF). Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) were employed to characterize the HAp/BC nanocomposites. SEM observations demonstrated that HAp crystals were uniformly formed on the phosphorylated BC fibers after soaking in 1.5 SBF whereas little HAp was observed on individual unphosphorylated BC fibers. Our experimental results suggested that the unphosphorylated BC did not induce HAp growth and that phosphorylation effectively triggered HAp formation on BC. Mechanisms were proposed for the explanation of the experimental observations. XRD and FTIR results revealed that the HAp crystals formed on the phosphorylated BC fibers were carbonate-containing with nano-sized crystallites and crystallinities less than 1%. These structural features were close to those of biological apatites

Biomimetic synthesis of hydroxyapatite/bacterial cellulose nanocomposites for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Wan, Y.Z. [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)]. E-mail: yzwantju@yahoo.com; Huang, Y. [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Yuan, C.D. [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Raman, S. [Department of Community Health and Epidemiology, Queen' s University, Kingston, Ontario, Canada K7L 3N6 (Canada); Zhu, Y. [School of Chemical Engineering, Tianjin University, Tianjin 300072 (China); Jiang, H.J. [Wendeng Hospital of Orthopaedics, Shandong 264400 (China); He, F. [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Gao, C. [School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

2007-05-16

Hydroxyapatite (HAp) and bacterial cellulose (BC) are both excellent materials for use in biomaterial areas. The former has outstanding osteoconductivity and bioactivity and the latter is a high-strength nano-fibrous and extensively used biomaterial. In this work, the HAp/BC nanocomposites with a 3-dimensional (3-D) network were synthesized via a biological route by soaking both phosphorylated and unphosphorylated BCs in 1.5 simulated body fluid (SBF). Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), and transmission electron microscopy (TEM) were employed to characterize the HAp/BC nanocomposites. SEM observations demonstrated that HAp crystals were uniformly formed on the phosphorylated BC fibers after soaking in 1.5 SBF whereas little HAp was observed on individual unphosphorylated BC fibers. Our experimental results suggested that the unphosphorylated BC did not induce HAp growth and that phosphorylation effectively triggered HAp formation on BC. Mechanisms were proposed for the explanation of the experimental observations. XRD and FTIR results revealed that the HAp crystals formed on the phosphorylated BC fibers were carbonate-containing with nano-sized crystallites and crystallinities less than 1%. These structural features were close to those of biological apatites.

Chitin and Cellulose Processing in Low-Temperature Electron Beam Plasma

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Tatiana Vasilieva

2017-11-01

Full Text Available Polysaccharide processing by means of low-temperature Electron Beam Plasma (EBP is a promising alternative to the time-consuming and environmentally hazardous chemical hydrolysis in oligosaccharide production. The present paper considers mechanisms of the EBP-stimulated destruction of crab shell chitin, cellulose sulfate, and microcrystalline cellulose, as well as characterization of the produced oligosaccharides. The polysaccharide powders were treated in oxygen EBP for 1–20 min at 40 °C in a mixing reactor placed in the zone of the EBP generation. The chemical structure and molecular mass of the oligosaccharides were analyzed by size exclusion and the reversed phase chromatography, FTIR-spectroscopy, XRD-, and NMR-techniques. The EBP action on original polysaccharides reduces their crystallinity index and polymerization degree. Water-soluble products with lower molecular weight chitooligosaccharides (weight-average molecular mass, Mw = 1000–2000 Da and polydispersity index 2.2 and cellulose oligosaccharides with polymerization degrees 3–10 were obtained. The 1H-NMR analysis revealed 25–40% deacetylation of the EBP-treated chitin and FTIR-spectroscopy detected an increase of carbonyl- and carboxyl-groups in the oligosaccharides produced. Possible reactions of β-1,4-glycosidic bonds’ destruction due to active oxygen species and high-energy electrons are given.

Characterization of purified bacterial cellulose focused on its use on paper restoration.

Science.gov (United States)

Santos, Sara M; Carbajo, José M; Quintana, Ester; Ibarra, David; Gomez, Nuria; Ladero, Miguel; Eugenio, M Eugenia; Villar, Juan C

2015-02-13

Bacterial cellulose (BC) synthesized by Gluconacetobacter sucrofermentans CECT 7291 seems to be a good option for the restoration of degraded paper. In this work BC layers are cultivated and purified by two different methods: an alkaline treatment when the culture media contains ethanol and a thermal treatment if the media is free from ethanol. The main goal of these tests was the characterization of BC layers measured in terms of tear and burst indexes, optical properties, SEM, X-ray diffraction, FTIR, degree of polymerization, static and dynamic contact angles, and mercury intrusion porosimetry. The BC layers were also evaluated in the same terms after an aging treatment. Results showed that BC has got high crystallinity index, low internal porosity, good mechanical properties and high stability over time, especially when purified by the alkaline treatment. These features make BC an adequate candidate for degraded paper reinforcement. Copyright © 2014 Elsevier Ltd. All rights reserved.

Production and Characterization of a New Bacterial Cellulose/Poly(Vinyl Alcohol Nanocomposite

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Miguel Gama

2013-05-01

Full Text Available Bacterial cellulose (BC is characterized for its high water holding capacity, high crystallinity, an ultrafine fiber network and high tensile strength. This work demonstrates the production of a new interpenetrated polymer network nanocomposite obtained through the incorporation of poly(vinyl alcohol (PVA on the BC matrix and evaluates the effect of oven drying on the morphological, mechanical and mass transfer properties of the composite membranes. Both the addition of PVA and oven drying induce the appearance of larger pores (circa 1–3 µm in average diameter in dried BC/PVA membranes. Both types of treatments also affect the permeability of the composite, as assessed by the diffusion coefficients of polyethylene glycol (PEG molecules (900, 8,000, 35,000 and 100,000 Da across the membranes. Finally, the Young’s modulus of dry pristine BC decreases following PVA incorporation, resulting in a change from 3.5 GPa to 1 GPa and a five-fold loss in tensile strength.

Improved in situ saccharification of cellulose pretreated by dimethyl sulfoxide/ionic liquid using cellulase from a newly isolated Paenibacillus sp. LLZ1.

Science.gov (United States)

Hu, Dongxue; Ju, Xin; Li, Liangzhi; Hu, Cuiying; Yan, Lishi; Wu, Tianyun; Fu, Jiaolong; Qin, Ming

2016-02-01

A cellulase producing strain was newly isolated from soil samples and identified as Paenibacillus sp. LLZ1. A novel aqueous-dimethyl sulfoxide (DMSO)/1-ethyl-3-methylimidazolium diethyl phosphate ([Emin]DEP)-cellulase system was designed and optimized. In the pretreatment, DMSO was found to be a low-cost substitute of up to 70% ionic liquid to enhance the cellulose dissolution. In the enzymatic saccharification, the optimum pH and temperature of the Paenibacillus sp. LLZ1 cellulase were identified as 6.0 and 40°C, respectively. Under the optimized reaction condition, the conversion of microcrystalline cellulose and bagasse cellulose increased by 39.3% and 37.6%, compared with unpretreated cellulose. Compared to current methods of saccharification, this new approach has several advantages including lower operating temperature, milder pH, and less usage of ionic liquid, indicating a marked progress in environmental friendly hydrolysis of biomass-based materials. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bacterial cellulose production from cotton-based waste textiles: enzymatic saccharification enhanced by ionic liquid pretreatment.

Science.gov (United States)

Hong, Feng; Guo, Xiang; Zhang, Shuo; Han, Shi-fen; Yang, Guang; Jönsson, Leif J

2012-01-01

Cotton-based waste textiles were explored as alternative feedstock for production of bacterial cellulose (BC) by Gluconacetobacter xylinus. The cellulosic fabrics were treated with the ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([AMIM]Cl). [AMIM]Cl caused 25% inactivation of cellulase activity at a concentration as low as of 0.02 g/mL and decreased BC production during fermentation when present in concentrations higher than 0.0005 g/mL. Therefore, removal of residual IL by washing with hot water was highly beneficial to enzymatic saccharification as well as BC production. IL-treated fabrics exhibited a 5-7-fold higher enzymatic hydrolysis rate and gave a seven times larger yield of fermentable sugars than untreated fabrics. BC from cotton cloth hydrolysate was obtained at an yield of 10.8 g/L which was 83% higher than that from the culture grown on glucose-based medium. The BC from G. xylinus grown on IL-treated fabric hydrolysate had a 79% higher tensile strength than BC from glucose-based culture medium which suggests that waste cotton pretreated with [AMIM]Cl has potential to serve as a high-quality carbon source for BC production. Copyright © 2011 Elsevier Ltd. All rights reserved.

Structure and properties of microcrystalline chitosan

International Nuclear Information System (INIS)

Pighinelli, Luciano; Guimaraes, Fernando Machado; Paz, Luan Rios; Zanin, Gabrielle Brehm; Kmiec, Marzena; Tedesco, Felipe Melleu; Reis, Victoria Oliva dos; Silva, Matheus Machado; Becker, Cristiane Miotto; Zehetmeyer, Gislene; Rasia, Gisele

2016-01-01

Full text: The microcrystalline chitosan is a modified form of chitosan; it has been elaborated from obtaining method of chitosan salts. It is characterized by special properties of the initial chitosan such as biocompatibility, bioactivity, non-toxic, biodegradability [1]. The objective of this study is to develop a different method to obtain the microcrystalline chitosan and the following characterization of the initial chitosan and MCCh. The material was characterized by FTIR, scanning of electron microscopy, SEM, nuclear magnetic resonance, NMR, and x-ray diffraction. The results indicate that the process to obtain MCCh, did not change the structure of the initial chitosan. The MCCh shows the same functional groups of the initial chitosan. The NMR results shows the acetylated and deacetylated groups. The morphology shows a homogeneous structure of surface. The X-ray diffraction shows the reduction of the crystallinity in the MCCh, indicating a bigger amorphous structure of the MCCh. The chitosan and its derivatives are polymers with excellent properties to be used in regenerative medicine because of ensure efficiency in healing process. This polysaccharide has a great potential to develop a new generation of biomaterials that can be used in regenerative medicine and tissue engineering [2]. References: [1]. LI, Q. et al. Applications and properties of chitosan. In: GOOSEN, M. F. A. (Ed.). Applications of chitin and chitosan. Basel: Technomic, 1997. p. 3-29; [2]. Luciano Pighinelli, Magdalena Kucharska, Dariuz Wawro. Preparation of Microcrystalline chitosan: (MCCh0/tricalcium phosphate complex with Hydroxyapatite in sponge and fibre from for hard tissue regeneration. (author)

Structure and properties of microcrystalline chitosan

Energy Technology Data Exchange (ETDEWEB)

Pighinelli, Luciano; Guimaraes, Fernando Machado; Paz, Luan Rios; Zanin, Gabrielle Brehm; Kmiec, Marzena; Tedesco, Felipe Melleu; Reis, Victoria Oliva dos; Silva, Matheus Machado, E-mail: lpighinelli@hotmail.com [Universidade Luterana, Sao Paulo, SP (Brazil); Becker, Cristiane Miotto; Zehetmeyer, Gislene; Rasia, Gisele [Centro Universitario SENAI CIMATEC, Salvador, BA (Brazil). Instituto de Engenharia de Materiais Polimericos

2016-07-01

Full text: The microcrystalline chitosan is a modified form of chitosan; it has been elaborated from obtaining method of chitosan salts. It is characterized by special properties of the initial chitosan such as biocompatibility, bioactivity, non-toxic, biodegradability [1]. The objective of this study is to develop a different method to obtain the microcrystalline chitosan and the following characterization of the initial chitosan and MCCh. The material was characterized by FTIR, scanning of electron microscopy, SEM, nuclear magnetic resonance, NMR, and x-ray diffraction. The results indicate that the process to obtain MCCh, did not change the structure of the initial chitosan. The MCCh shows the same functional groups of the initial chitosan. The NMR results shows the acetylated and deacetylated groups. The morphology shows a homogeneous structure of surface. The X-ray diffraction shows the reduction of the crystallinity in the MCCh, indicating a bigger amorphous structure of the MCCh. The chitosan and its derivatives are polymers with excellent properties to be used in regenerative medicine because of ensure efficiency in healing process. This polysaccharide has a great potential to develop a new generation of biomaterials that can be used in regenerative medicine and tissue engineering [2]. References: [1]. LI, Q. et al. Applications and properties of chitosan. In: GOOSEN, M. F. A. (Ed.). Applications of chitin and chitosan. Basel: Technomic, 1997. p. 3-29; [2]. Luciano Pighinelli, Magdalena Kucharska, Dariuz Wawro. Preparation of Microcrystalline chitosan: (MCCh0/tricalcium phosphate complex with Hydroxyapatite in sponge and fibre from for hard tissue regeneration. (author)

Occurrence of Cellulose-Producing Gluconacetobacter spp. in Fruit Samples and Kombucha Tea, and Production of the Biopolymer.

Science.gov (United States)

Neera; Ramana, Karna Venkata; Batra, Harsh Vardhan

2015-06-01

Cellulose producing bacteria were isolated from fruit samples and kombucha tea (a fermented beverage) using CuSO4 solution in modified Watanabe and Yamanaka medium to inhibit yeasts and molds. Six bacterial strains showing cellulose production were isolated and identified by 16S rRNA gene sequencing as Gluconacetobacter xylinus strain DFBT, Ga. xylinus strain dfr-1, Gluconobacter oxydans strain dfr-2, G. oxydans strain dfr-3, Acetobacter orientalis strain dfr-4, and Gluconacetobacter intermedius strain dfr-5. All the cellulose-producing bacteria were checked for the cellulose yield. A potent cellulose-producing bacterium, i.e., Ga. xylinus strain DFBT based on yield (cellulose yield 5.6 g/L) was selected for further studies. Cellulose was also produced in non- conventional media such as pineapple juice medium and hydrolysed corn starch medium. A very high yield of 9.1 g/L cellulose was obtained in pineapple juice medium. Fourier transform infrared spectrometer (FT-IR) analysis of the bacterial cellulose showed the characteristic peaks. Soft cellulose with a very high water holding capacity was produced using limited aeration. Scanning electron microscopy (SEM) was used to analyze the surface characteristics of normal bacterial cellulose and soft cellulose. The structural analysis of the polymer was performed using (13)C solid-state nuclear magnetic resonance (NMR). More interfibrillar space was observed in the case of soft cellulose as compared to normal cellulose. This soft cellulose can find potential applications in the food industry as it can be swallowed easily without chewing.

Direct Modification of Microcrystalline Cellulose with Ethylenediamine for use as Adsorbent for Removal Amitriptyline Drug from Environment.

Science.gov (United States)

Bezerra, Roosevelt D S; Leal, Régis C; da Silva, Mateus S; Morais, Alan I S; Marques, Thiago H C; Osajima, Josy A; Meneguin, Andréia B; da S Barud, Hernane; C da Silva Filho, Edson

2017-11-22

Cellulose derivatives have been widely used as adsorbents for the removal of micropollutants such as drugs, dyes, and metals, due to their abundance, low cost and non-contaminating nature. In this context, several studies have been performed searching for new adsorbents (cellulose derivatives) efficient at contaminant removal from aqueous solutions. Thus, a new adsorbent was synthesized by chemical modification of cellulose with ethylenediamine in the absence of solvent and applied to the adsorption of amitriptyline (AMI) in aqueous solution. The modification reaction was confirmed by X-ray Diffraction (XRD), elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry/Differential Scanning Calorimeter (TG/DSC), solid state Nuclear Magnetic Resonance of ¹H and 13 C (¹H-NMR and 13 C-NMR). Moreover, the effectiveness of reaction was confirmed by computational calculations using Density Functional Theory (DFT) at level B3LYP/6-31G(d). This adsorption process was influenced by pH, time, concentration, temperature and did not show significant changes due to the ionic strength variation. Through these experiments, it was observed that the maximum adsorption capacity of AMI by CN polymer at 298 K, 300 min, and pH 7 was 87.66 ± 0.60 mg·g -1 .

Direct Modification of Microcrystalline Cellulose with Ethylenediamine for Use as Adsorbent for Removal Amitriptyline Drug from Environment

Directory of Open Access Journals (Sweden)

Roosevelt D. S. Bezerra

2017-11-01

Full Text Available Cellulose derivatives have been widely used as adsorbents for the removal of micropollutants such as drugs, dyes, and metals, due to their abundance, low cost and non-contaminating nature. In this context, several studies have been performed searching for new adsorbents (cellulose derivatives efficient at contaminant removal from aqueous solutions. Thus, a new adsorbent was synthesized by chemical modification of cellulose with ethylenediamine in the absence of solvent and applied to the adsorption of amitriptyline (AMI in aqueous solution. The modification reaction was confirmed by X-ray Diffraction (XRD, elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR, Thermogravimetry/Differential Scanning Calorimeter (TG/DSC, solid state Nuclear Magnetic Resonance of 1H and 13C (1H-NMR and 13C-NMR. Moreover, the effectiveness of reaction was confirmed by computational calculations using Density Functional Theory (DFT at level B3LYP/6-31G(d. This adsorption process was influenced by pH, time, concentration, temperature and did not show significant changes due to the ionic strength variation. Through these experiments, it was observed that the maximum adsorption capacity of AMI by CN polymer at 298 K, 300 min, and pH 7 was 87.66 ± 0.60 mg·g−1.

Use of agroindustrial waste in the preparation of nanocomposites based on bacterial cellulose and hydroxyapatite; Utilizacao de residuos agroindustriais na elaboracao de bionanocompositos baseados em celulose bacteriana e hidroxiapatita

Energy Technology Data Exchange (ETDEWEB)

Duarte, Eden B.; Chagas, Bruna S. das; Feitosa, Judith P.A. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil); Andrade, Fabia K.; Borges, Maria F.; Muniz, Celli R.; Souza Filho, Men de Sa M.; Rosa, Morsyleide F., E-mail: morsyleide.rosa@embrapa.br [Embrapa Agroindustria Tropical, Fortaleza, CE (Brazil); Brigida, Ana I. [Embrapa Agroindustria de Alimentos, Barra de Guaratiba, Rio de Janeiro, RJ (Brazil); Morais, Joao P.S. [Embrapa Algodao, Campina Grande, PB (Brazil)

2015-07-01

Environmental issues have supported the interest in renewable sources and agroindustrial residues became a significant resource for the production of new materials. The present work presents the use of agroindustrial residues to obtain bacterial cellulose (BC) for further elaboration of nanocomposites with hydroxyapatite (HA). The production of BC membranes occurred in Hestrin & Schramm medium, cashew juice and sisal liquid waste cultivated under static conditions. After the incubation period, the BC membranes were purified and nanocomposites prepared by successive immersion of the purified membranes in solutions of Calcium Chloride (CaCl{sub 2}), and Sodium Phosphate (Na{sub 2}HPO{sub 4}), followed by drying and subsequent characterization. The materials obtained were characterized by Thermogravimetric Analysis (TGA) and X-ray Diffraction (XRD). Additionally, in vitro tests were performed for nanocomposites. The results showed the production of cellulose from the three substrates studied, without the need for further supplementation or pH change. In all characterizations, structure and typical behavior of bacterial cellulose were found. The composites showed bioactivity and the adsorption capacity of proteins, which lead to potential biocompatibility of these materials. (author)

Characterization of a Cellulomonas fimi exoglucanase/xylanase-endoglucanase gene fusion which improves microbial degradation of cellulosic biomass.

Science.gov (United States)

Duedu, Kwabena O; French, Christopher E

2016-11-01

Effective degradation of cellulose requires multiple classes of enzyme working together. However, naturally occurring cellulases with multiple catalytic domains seem to be rather rare in known cellulose-degrading organisms. A fusion protein made from Cellulomonas fimi exo- and endo- glucanases, Cex and CenA which improves breakdown of cellulose is described. A homologous carbohydrate binding module (CBM-2) present in both glucanases was fused to give a fusion protein CxnA. CxnA or unfused constructs (Cex+CenA, Cex, or CenA) were expressed in Escherichia coli and Citrobacter freundii. The latter recombinant strains were cultured at the expense of cellulose filter paper. The expressed CxnA had both exo- and endo- glucanase activities. It was also exported to the supernatant as were the non-fused proteins. In addition, the hybrid CBM from the fusion could bind to microcrystalline cellulose. Growth of C. freundii expressing CxnA was superior to that of cells expressing the unfused proteins. Physical degradation of filter paper was also faster with the cells expressing fusion protein than the other constructs. Our results show that fusion proteins with multiple catalytic domains can improve the efficiency of cellulose degradation. Such fusion proteins could potentially substitute cloning of multiple enzymes as well as improving product yields. Copyright © 2016 Elsevier Inc. All rights reserved.

Analysis of heating effect on the process of high deposition rate microcrystalline silicon

International Nuclear Information System (INIS)

Xiao-Dan, Zhang; He, Zhang; Chang-Chun, Wei; Jian, Sun; Guo-Fu, Hou; Shao-Zhen, Xiong; Xin-Hua, Geng; Ying, Zhao

2010-01-01

A possible heating effect on the process of high deposition rate microcrystalline silicon has been studied. It includes the discharge time-accumulating heating effect, discharge power, inter-electrode distance, and total gas flow rate induced heating effect. It is found that the heating effects mentioned above are in some ways quite similar to and in other ways very different from each other. However, all of them will directly or indirectly cause the increase of the substrate surface temperature during the process of depositing microcrystalline silicon thin films, which will affect the properties of the materials with increasing time. This phenomenon is very serious for the high deposition rate of microcrystalline silicon thin films because of the high input power and the relatively small inter-electrode distance needed. Through analysis of the heating effects occurring in the process of depositing microcrystalline silicon, it is proposed that the discharge power and the heating temperature should be as low as possible, and the total gas flow rate and the inter-electrode distance should be suitable so that device-grade high quality deposition rate microcrystalline silicon thin films can be fabricated

Studies on the physicochemical and functional properties of ...

African Journals Online (AJOL)

This study was aimed at developing pharmaceutical grade microcrystalline cellulose from Khaya grandifolia wood flakes as a tablet excipient. The microcrystalline cellulose coded KG-MCC, was obtained from Khaya grandifolia wood flakes by a two-stage sodium hydroxide delignification process followed by sodium ...

Binary PVA bio-nanocomposites containing cellulose nanocrystals extracted from different natural sources: part I.

Science.gov (United States)

Fortunati, E; Puglia, D; Luzi, F; Santulli, C; Kenny, J M; Torre, L

2013-09-12

PVA bio-nanocomposites reinforced with cellulose nanocrystals (CNC) extracted from commercial microcrystalline cellulose (MCC) and from two types of natural fibres, Phormium tenax and Flax of the Belinka variety, were produced by solvent casting in water. Morphological, thermal, mechanical and transparency properties were studied while the respective efficiency of the extraction process of CNC from the three sources was evaluated. The effect of CNC types and content on PVA properties and water absorption capacity were also evaluated. Natural fibres offered higher levels of extraction efficiency when compared with MCC hydrolysis yield. Thermal analysis proved that CNC promotes the crystallization of the PVA matrix, while improving its plastic response. It was also clarified that all PVA/CNC systems remain transparent due to CNC dispersion at the nanoscale, while being all saturated after the first 18-24h of water absorption. Copyright © 2013 Elsevier Ltd. All rights reserved.

Rational design of a high-strength bone scaffold platform based on in situ hybridization of bacterial cellulose/nano-hydroxyapatite framework and silk fibroin reinforcing phase.

Science.gov (United States)

Jiang, Pei; Ran, Jiabing; Yan, Pan; Zheng, Lingyue; Shen, Xinyu; Tong, Hua

2018-02-01

Bacterial cellulose/hydroxyapatite (BC/HAp) composite had favourable bioaffinity but its poor mechanical strength limited its widespread applications in bone tissue engineering (BTE). Silk fibroin, which possesses special crystalline structure, has been widely used as organic reinforcing material, and different SFs have different amino acid sequences, which exhibit different bioaffinity and mechanical properties. In this regard, bacterial cellulose-Antheraea yamamai silk fibroin/hydroxyapatite (BC-AYSF/HAp), bacterial cellulose-Bombyx mori silk fibroin/hydroxyapatite (BC-BMSF/HAp), and BC/HAp nano-composites were synthesized via a novel in situ hybridization method. Compared with BC/HAp and BC-BMSF/HAp, the BC-AYSF/HAp exhibited better interpenetration, which may benefit for the transportation of nutrients and wastes, the adhesion of cells as well. Additionally, the BC-AYSF/HAp also presented superior thermal stability than the other two composites revealed by differential thermal analysis (DTA) and thermogravimetric analysis (TGA). Compression testing indicated that the mechanical strength of BC-BMSF/HAp was greatly reinforced compared with BC/HAp and was even a little higher than that of BC-AYSF/HAp. Tensile testing showed that BC-AYSF/HAp possesses extraordinary mechanical properties with a higher elastic modulus at low strain and higher fracture strength simultaneously than the other two composites. In vitro cell culture exhibited that MC3T3-E1 cells on the BC-AYSF/HAp membrane took on higher proliferative potential than those on the BC-BMSF/HAp membrane. These results suggested that compared with BC-BMSF/HAp, the BC-AYSF/HAp composite was more appropriate as an ideal bone scaffold platform or biomedical membrane to be used in BTE.

Licuri fibers characterization after treatment to produce cellulose nanocrystals; Caracterizacao da fibra de licuri apos tratamento para producao de nanocristais de celulose

Energy Technology Data Exchange (ETDEWEB)

Castro, E.G.; Oliveira, J.C.; Miranda, C.S.; Jose, N.M., E-mail: elyane_casft@msn.com [Universidade Federal da Bahia (GECIM/UFBA), Salvador, BA (Brazil). Programa de Pos-Graduacao em Engenharia Quimica. Grupo de Energia e Ciencias dos Materiais

2014-07-01

Cellulose nanocrystals have been widely studied in the materials area due to their high aspect ratio, which is directly related to a good performance as mechanical reinforcement. Obtaining this nanocrystals from commercial bleached pulps, as eucalyptus, or microcrystalline cellulose is well studied. Trying to find new extraction sources, exploring better the huge variety of Brazil’s natural fibers and giving the opportunity of development to small communities, the present work verifies the influence of two bleaching methodologies, sodium hypochlorite or hydrogen peroxide, on licuri fibers. Previous washing and mercerization steps were performed before bleaching. The product of each step was analysed by: DSC, TGA, XRD, SEM and FTIR. The yield of each step was also calculated. (author)

Morphology and mechanical properties of poly(β-hydroxybutyrate)/poly(ε-caprolactone) blends controlled with cellulosic particles.

Science.gov (United States)

Chen, Jianxiang; Wang, Yuankun; Yin, Zeren; Tam, Kam C; Wu, Defeng

2017-10-15

The rigid microcrystalline cellulose (MCC) particles and semi-rigid ethyl cellulose (EC) were used to control phase morphology and mechanical properties of immiscible poly(β-hydroxybutyrate) (PHB)/poly(ε-caprolactone) (PCL) blends. The interfacial properties were evaluated by the fiber retraction and contact angle methods MCC is incompatible with PHB and PCL, and dispersed independently in the two polymer phases in their blends. However, EC is more compatible with the two polymers, with a higher affinity for PCL. And EC prefers locating in PCL domains and at the phase interface. Selective localization of MCC and EC affects the mechanical properties and phase structure of PHB/PCL blends strongly. For the co-continuous samples, the presence of MCC and EC improves both the tensile and impact strengths. For the 'sea-island' ones, however, the changes of strengths depends strongly on the phase adhesion. This work will help focus efforts on moderating structure and properties of immiscible polymer blends using cellulose particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cellulose-polyhydroxylated fatty acid ester-based bioplastics with tuning properties: Acylation via a mixed anhydride system.

Science.gov (United States)

Heredia-Guerrero, José A; Goldoni, Luca; Benítez, José J; Davis, Alexander; Ceseracciu, Luca; Cingolani, Roberto; Bayer, Ilker S; Heinze, Thomas; Koschella, Andreas; Heredia, Antonio; Athanassiou, Athanassia

2017-10-01

The synthesis of microcrystalline cellulose (MCC) and 9,10,16-hydroxyhexadecanoic (aleuritic) acid ester-based bioplastics was investigated through acylation in a mixed anhydride (trifluoroacetic acid (TFA)/trifluoroacetic acid anhydride (TFAA)), chloroform co-solvent system. The effects of chemical interactions and the molar ratio of aleuritic acid to the anhydroglucose unit (AGU) of cellulose were investigated. The degree of substitution (DS) of new polymers were characterized by two-dimensional solution-state NMR and ranged from 0.51 to 2.60. The chemical analysis by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) confirmed the presence of aleuritate groups in the structure induces the formation of new H-bond networks. The tensile analysis and the contact angle measurement confirmed the ductile behavior and the hydrophobicity of the prepared bioplastics. By increasing the aleuritate amounts, the glass transition temperature decreased and the solubility of bioplastic films in most common solvents was improved. Furthermore, this new polymer exhibits similar properties compared to commercial cellulose derivatives. Copyright © 2017 Elsevier Ltd. All rights reserved.

Studies on Hydrotreating Process of Microcrystalline Wax Produced from Marine Belayim Crude Oil

International Nuclear Information System (INIS)

EI Karashi, S.; Marawan, H.

2004-01-01

Abstract Microcrystalline wax was produced from solvent dewaxing process of vacuum residue raffinate produced from Marine Belayim origin. The untreated microcrystalline wax contains trace amounts of sulfur, oxygen, nitrogen and organometallic compounds as well as heavy aromatics which affect the properties of wax applications in pharmaceutical and technical fields . Microcrystalline wax hydrotreating process was studied using digital controlled unit and Ni O-MoO 3 / Al 2 O 3 catalyst, where operating parameters that controlled the efficiency of the hydrotreated wax were studied separately at different values including reactor temperature, reactor pressure, liquid hourly space velocity and hydrogen to hydrocarbon ratio . Hydrotreated microcrystalline wax at operating conditions (temperature 300 degree C, pressure 73 kg/cm 2 , LHS V 0.52 h-l and H 2 /HC ratio 266.6 Nm 3 /m 3 ) has the best quality to be used as food grade wax

Cellulose hydrolysis by Trichoderma reesei cellulases: studies on adsorption, sugar production and synergism of cellobiohydrolase I,II and endoglucanase II

Energy Technology Data Exchange (ETDEWEB)

Medve, J.

1997-02-01

Three major cellulases have been purified by ion-exchange chromatography in an FPLC system. Microcrystalline cellulose (Avicel) was hydrolyzed by the single enzymes and by equimolar mixtures of CBH I-CBH II and CBH I-EG II. Enzyme adsorption was followed indirectly by selectively quantifying the enzymes in the supernatant by ion-exchange chromatography in an FPLC system. The (synergistic) production of small, soluble sugars (glucose, cellobiose and cellotriose) by the enzymes was followed by HPLC. 76 refs

Crystallographic snapshot of cellulose synthesis and membrane translocation.

Science.gov (United States)

Morgan, Jacob L W; Strumillo, Joanna; Zimmer, Jochen

2013-01-10

Cellulose, the most abundant biological macromolecule, is an extracellular, linear polymer of glucose molecules. It represents an essential component of plant cell walls but is also found in algae and bacteria. In bacteria, cellulose production frequently correlates with the formation of biofilms, a sessile, multicellular growth form. Cellulose synthesis and transport across the inner bacterial membrane is mediated by a complex of the membrane-integrated catalytic BcsA subunit and the membrane-anchored, periplasmic BcsB protein. Here we present the crystal structure of a complex of BcsA and BcsB from Rhodobacter sphaeroides containing a translocating polysaccharide. The structure of the BcsA-BcsB translocation intermediate reveals the architecture of the cellulose synthase, demonstrates how BcsA forms a cellulose-conducting channel, and suggests a model for the coupling of cellulose synthesis and translocation in which the nascent polysaccharide is extended by one glucose molecule at a time.

Performance of Platinum Nanoparticles / Multiwalled Carbon Nanotubes / Bacterial Cellulose Composite as Anode Catalyst for Proton Exchange Membrane Fuel Cells

Directory of Open Access Journals (Sweden)

Henry Fonda Aritonang

2017-05-01

Full Text Available Highly dispersed platinum (Pt nanoparticles / multiwalled carbon nanotubes (MWCNTs on bacterial cellulose (BC as anode catalysts for proton exchange membrane fuel cells (PEMFC were prepared with various precursors and their electro-catalytic activities towards hydrogen oxidation at 70 oC under non-humidified conditions. The composite was prepared by deposition of Pt nanoparticles and MWCNTs on BC gel by impregnation method using a water solution of metal precursors and MWCNTs followed by reducing reaction using a hydrogen gas. The composite was characterized by using TEM (transmission electron microscopy, EDS (energy dispersive spectroscopy, and XRD (X-ray diffractometry techniques. TEM images and XRD patterns both lead to the observation of spherical metallic Pt nanoparticles with mean diameter of 3-11 nm well impregnated into the BC fibrils. Preliminary tests on a single cell indicate that renewable BC is a good prospect to be explored as a membrane in fuel cell field. Copyright © 2017 BCREC Group. All rights reserved Received: 21st November 2016; Revised: 26th February 2017; Accepted: 27th February 2017 How to Cite: Aritonang, H.F., Kamu, V.S., Ciptati, C., Onggo, D., Radiman, C.L. (2017. Performance of Platinum Nanoparticles / Multiwalled Carbon Nanotubes / Bacterial Cellulose Composite as Anode Catalyst for Proton Exchange Membrane Fuel Cells. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2: 287-292 (doi:10.9767/bcrec.12.2.803.287-292 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.803.287-292

Esophageal replacement by hydroxylated bacterial cellulose patch in a rabbit model.

Science.gov (United States)

Zhu, Changlai; Liu, Fang; Qian, Wenbo; Wang, Yingjie; You, Qingsheng; Zhang, Tianyi; Li, Feng

2015-01-01

To repair esophageal defects by hydroxylated and kombucha-synthesized bacterial cellulose (HKBC) patch in a rabbit model. Semicircular esophageal defects 1 cm in length of the cervical esophagus were initially created in 18 Japanese big-ear rabbits and then repaired with HKBC patch grafts. The clinical outcomes including survival rate, weight change, food intake, and hematological and radiologic evaluation were observed. After X-ray evaluation, the rabbits were sacrificed sequentially at 1, 3, and 6 months for histopathologic analysis with light microscopy and scanning electron microscopy. Survival rate during the first month was 88.9% (n = 16). Two rabbits died from anastomotic leakage during the entire follow-up. Postoperatively, feeding function and body weight were gradually restored in the surviving animals. No hematological abnormalities were found, and no obvious anastomotic leakage, stenosis, or obstruction was observed under X-ray examination. The histopathologic results showed a progressive regeneration of the esophagus in the graft area, where the neo-esophagus tissue had characteristics similar to native esophageal tissue after 3 months of surgery. HKBC is beneficial for esophageal tissue regeneration and may be a promising material for esophageal reconstruction.

Using a cellulose derivative as a stabilizing agent of ceramic suspensions

International Nuclear Information System (INIS)

Cerrutti, Bianca M.; Frollini, Elisabete

2009-01-01

Cellulose is the most abundant natural polymer, but its application has been hampered by its poor solubility, which is restricted to a few solvents. Nevertheless, it may be chemically modified to produce derivatives that are soluble in organic solvents, and most important, in water. Carboxymethylcellulose (CMC), one of the most versatile of such derivatives, is highly soluble in water. This allows its use in the pharmaceutical, food, paint, and adhesive industries. In this study, CMC was prepared by reaction of low average molecular weight microcrystalline cellulose and monochloroacetic acid as the etherifying agent in a highly alkaline medium. The degree of substitution of CMC, obtained by 1 HNMR spectroscopy was 0.7. CMC was found to induce the stabilization of aqueous alumina suspensions, yielding a decrease in both viscosity and particle size, while increasing the zeta potential. These results demonstrate that CMC, a derivative from a natural polymer, may be successfully used as a stabilizing agent of aqueous ceramic suspension instead of the polymers derived from raw fossil materials currently used. (author)

Biotemplated preparation of CdS nanoparticles/bacterial cellulose hybrid nanofibers for photocatalysis application

International Nuclear Information System (INIS)

Yang, Jiazhi; Yu, Junwei; Fan, Jun; Sun, Dongping; Tang, Weihua; Yang, Xuejie

2011-01-01

In this work, we describe a novel facile and effective strategy to prepare micrometer-long hybrid nanofibers by deposition of CdS nanoparticles onto the substrate of hydrated bacterial cellulose nanofibers (BCF). Hexagonal phase CdS nanocrystals were achieved via a simple hydrothermal reaction between CdCl 2 and thiourea at relatively low temperature. The prepared pristine BCF and the CdS/BCF hybrid nanofibers were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results reveal that the CdS nanoparticles were homogeneously deposited on the BCF surface and stabilized via coordination effect. The CdS/BCF hybrid nanofibers demonstrated high-efficiency photocatalysis with 82% methyl orange (MO) degradation after 90 min irradiation and good recyclability. The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts.

Biotemplated preparation of CdS nanoparticles/bacterial cellulose hybrid nanofibers for photocatalysis application.

Science.gov (United States)

Yang, Jiazhi; Yu, Junwei; Fan, Jun; Sun, Dongping; Tang, Weihua; Yang, Xuejie

2011-05-15

In this work, we describe a novel facile and effective strategy to prepare micrometer-long hybrid nanofibers by deposition of CdS nanoparticles onto the substrate of hydrated bacterial cellulose nanofibers (BCF). Hexagonal phase CdS nanocrystals were achieved via a simple hydrothermal reaction between CdCl(2) and thiourea at relatively low temperature. The prepared pristine BCF and the CdS/BCF hybrid nanofibers were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results reveal that the CdS nanoparticles were homogeneously deposited on the BCF surface and stabilized via coordination effect. The CdS/BCF hybrid nanofibers demonstrated high-efficiency photocatalysis with 82% methyl orange (MO) degradation after 90 min irradiation and good recyclability. The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts. Copyright © 2011 Elsevier B.V. All rights reserved.

Biotemplated preparation of CdS nanoparticles/bacterial cellulose hybrid nanofibers for photocatalysis application

Energy Technology Data Exchange (ETDEWEB)

Yang, Jiazhi; Yu, Junwei [Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology, Nanjing 210094 (China); Fan, Jun [School of Environment, Nanjing University, Nanjing 210093 (China); Sun, Dongping [Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology, Nanjing 210094 (China); Tang, Weihua [Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology, Nanjing 210094 (China); Yang, Xuejie [Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education), Nanjing University of Science and Technology, Nanjing 210094 (China)

2011-05-15

In this work, we describe a novel facile and effective strategy to prepare micrometer-long hybrid nanofibers by deposition of CdS nanoparticles onto the substrate of hydrated bacterial cellulose nanofibers (BCF). Hexagonal phase CdS nanocrystals were achieved via a simple hydrothermal reaction between CdCl{sub 2} and thiourea at relatively low temperature. The prepared pristine BCF and the CdS/BCF hybrid nanofibers were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV-vis absorption spectroscopy (UV-vis), and X-ray photoelectron spectroscopy (XPS). The results reveal that the CdS nanoparticles were homogeneously deposited on the BCF surface and stabilized via coordination effect. The CdS/BCF hybrid nanofibers demonstrated high-efficiency photocatalysis with 82% methyl orange (MO) degradation after 90 min irradiation and good recyclability. The results indicate that the CdS/BCF hybrid nanofibers are promising candidate as robust visible light responsive photocatalysts.

Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis

Directory of Open Access Journals (Sweden)

Demirci Ali

2009-07-01

Full Text Available Abstract Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD, field emission scanning electron microscopy (FESEM, thermogravimetric analysis (TGA, and dynamic mechanical analysis (DMA. Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L that was 2.5-fold greater than the control (2.82 g/L. The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93% and similar crystal size (5.2 nm to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to

A terahertz time-domain study on the estimation of opto-mechanical properties of pharmaceutical tablets using the Hashin-Shtrikman bounds for refractive index: a case study of microcrystalline cellulose and starch acetate compacts

Science.gov (United States)

Bawuah, Prince; Peiponen, Kai-Erik

2016-06-01

This work highlights the use of Hashin-Shtrikman (H-S) bounds in the prediction and verification of the effective refractive index, the height and the Young's modulus of given training sets of pharmaceutical compacts using the measured time delay of a THz pulse traversing the compacts. Set A consisted of 13 microcrystalline cellulose (MCC) compacts whereas set B was made up of 5 starch acetate (SA) compacts. MCC is a typical ingredient of many pharmaceutical tablets. In the case of the MCC compacts, tight and closely matched bounds were obtained between the experimental, the calculated upper, lower bound values for the effective refractive index, and the height values. This promising outcome has shown the high possibility of utilizing H-S bounds in the verification and prediction of the decision level of useful parameters, which can serve as a quality check for pharmaceutical tablets. For the SA compacts, although less tight bounds were observed, the experimental values for the effective refractive index and the Young's modulus were closely matched with the upper and the lower bounds, respectively. We therefore speculate based on the above observations that the MCC tablets contain an almost evenly distributed spherically shaped air voids whereas in the SA compacts, this assumption might not necessary be true.

Pembuatan Selulosa Mikrokristal dan Ekstrak Etanol Daun Nanas (Ananas Comosus (L.) Merr.) yang Diformulasikan Menjadi Sediaan Tablet

OpenAIRE

Kaban, Vera Estefania

2016-01-01

Background: The leaves of pineapple (Ananas comosus(L.) Merr.) including waste containing cellulose, can be isolate and made into a crystalline form. Microcrystalline cellulose is an additional ingredient that is often use in the manufacture of tablets by direct compression methods. Purpose: The aims of this study was isolated and characterize the microcrystalline cellulose and ethanol extract from pineapple leaves was formulated into dosage tablet. Methods: Dried material powder was ex...

Synergy of Diflubenzuron Baiting and NHA Dusting on Mortality of Reticulitermes flavipes

Science.gov (United States)

F. III Green; R.A. Arango; G.R. Esenther; M.G. Rojas; J. Morales-Ramos

2013-01-01

The ability of N’N-naphthaloylhydroxylamine (NHA) to cause mortality in Reticulitermes flavipes workers pretreated with the chitin synthesis inhibitor diflubenzuron was tested by adding two NHA dusted workers to 100 (2:100) pretreated workers fed either pure microcrystalline alpha-cellulose or diflubenzuron (0.25%) treated microcrystalline cellulose...

Salmonella biofilm formation on Aspergillus niger involves cellulose--chitin interactions.

Directory of Open Access Journals (Sweden)

Maria T Brandl

Full Text Available Salmonella cycles between host and nonhost environments, where it can become an active member of complex microbial communities. The role of fungi in the environmental adaptation of enteric pathogens remains relatively unexplored. We have discovered that S. enterica Typhimurium rapidly attaches to and forms biofilms on the hyphae of the common fungus, Aspergillus niger. Several Salmonella enterica serovars displayed a similar interaction, whereas other bacterial species were unable to bind to the fungus. Bacterial attachment to chitin, a major constituent of fungal cell walls, mirrored this specificity. Pre-incubation of S. Typhimurium with N-acetylglucosamine, the monomeric component of chitin, reduced binding to chitin beads by as much as 727-fold and inhibited attachment to A. niger hyphae considerably. A cellulose-deficient mutant of S. Typhimurium failed to attach to chitin beads and to the fungus. Complementation of this mutant with the cellulose operon restored binding to chitin beads to 79% of that of the parental strain and allowed for attachment and biofilm formation on A. niger, indicating that cellulose is involved in bacterial attachment to the fungus via the chitin component of its cell wall. In contrast to cellulose, S. Typhimurium curli fimbriae were not required for attachment and biofilm development on the hyphae but were critical for its stability. Our results suggest that cellulose-chitin interactions are required for the production of mixed Salmonella-A. niger biofilms, and support the hypothesis that encounters with chitinaceous alternate hosts may contribute to the ecological success of human pathogens.

Dietary fructans, but not cellulose, decrease triglyceride accumulation in the liver of obese Zucker fa/fa rats.

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Daubioul, Catherine; Rousseau, Nicolas; Demeure, Roger; Gallez, Bernard; Taper, Henryk; Declerck, Barbara; Delzenne, Nathalie

2002-05-01

This study was designed to compare the effects of dietary supplementation with nondigestible carbohydrates, differing in fermentability by colonic bacteria, on hepatic steatosis in growing obese Zucker rats. Male Zucker fa/fa rats were divided into three groups: a control group that received the basal diet, a fructan group that received 10 g highly fermented Synergy 1/100 g diet and a cellulose group that received 10 g poorly fermented Vivapur Microcrystalline cellulose/100 g diet. Rats consuming fructan had a lower energy intake, a lower body weight and less triacylglycerol accumulation in the liver as assessed in vivo by nuclear magnetic resonance (NMR) spectroscopy, and ex vivo by biochemical and histochemical analysis compared with the control and/or cellulose groups. The high fermentation of fructans compared with cellulose was reflected by greater cecal contents and by a twofold greater propionate concentration in the portal vein of rats fed fructan compared with those fed cellulose. By measuring the capacity of hepatocytes isolated from liver of Zucker rats to synthesize triglycerides or total lipids from different precursors, we showed that propionate, at the concentrations measured in the portal vein of rats treated with fructan, selectively decreased the incorporation of acetate into total lipids, a phenomenon that could contribute, along with the lower energy intake, to less triglyceride accumulation in the liver of obese Zucker rats fed dietary fructans.

Cellulose nanomaterials as green nanoreinforcements for polymer nanocomposites

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Dufresne, Alain

2017-12-01

Unexpected and attractive properties can be observed when decreasing the size of a material down to the nanoscale. Cellulose is no exception to the rule. In addition, the highly reactive surface of cellulose resulting from the high density of hydroxyl groups is exacerbated at this scale. Different forms of cellulose nanomaterials, resulting from a top-down deconstruction strategy (cellulose nanocrystals, cellulose nanofibrils) or bottom-up strategy (bacterial cellulose), are potentially useful for a large number of industrial applications. These include the paper and cardboard industry, use as reinforcing filler in polymer nanocomposites, the basis for low-density foams, additives in adhesives and paints, as well as a wide variety of filtration, electronic, food, hygiene, cosmetic and medical products. This paper focuses on the use of cellulose nanomaterials as a filler for the preparation of polymer nanocomposites. Impressive mechanical properties can be obtained for these materials. They obviously depend on the type of nanomaterial used, but the crucial point is the processing technique. The emphasis is on the melt processing of such nanocomposite materials, which has not yet been properly resolved and remains a challenge. This article is part of a discussion meeting issue `New horizons for cellulose nanotechnology'.

Preparation and physical properties of tara gum film reinforced with cellulose nanocrystals.

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Ma, Qianyun; Hu, Dongying; Wang, Lijuan

2016-05-01

Cellulose nanocrystals (CNC) prepared from microcrystalline cellulose were blended in tara gum solution to prepare nanocomposite films. The morphology, crystallinity, and thermal properties of the CNC and films were evaluated by using transmission electron microscopy, X-ray diffractometry, and thermogravimetric analysis, respectively. The resultant CNC was rod-shaped with diameters of around 8.6 nm. The effect of CNC content on physical and thermal properties of films was studied. The composite film tensile strength increased from 27.86 to 65.73 MPa, elastic modulus increased from 160.98 MPa to 882.49 MPa and the contact angle increased from 55.8° to 98.7° with increasing CNC content from 0 to 6 wt%. However, CNC addition increased the thermal stability slightly and CNC content above 6 wt% decreased the tensile strength by CNC aggregation in the matrix. The nanocomposite film containing 6 wt% CNC possessed the highest light transmittance, mechanical properties, and lowest oxygen permeability. CNC addition is a suitable method to modify tara gum matrix polymer properties. Copyright © 2016 Elsevier B.V. All rights reserved.

Fabrication of antimicrobial bacterial cellulose-Ag/AgCl nanocomposite using bacteria as versatile biofactory

Energy Technology Data Exchange (ETDEWEB)

Liu Chuang [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China); Yang Dong; Wang Yuangui [Tianjin University, Department of Biochemical Engineering and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology (China); Shi Jiafu; Jiang Zhongyi, E-mail: zhyjiang@tju.edu.cn [Tianjin University, Key Laboratory for Green Technology, School of Chemical Engineering and Technology (China)

2012-08-15

In nature, a number of nanocomposites are formed through biomineralization-relevant processes under mild conditions. In the present study, a total 'biologic' route to fabricate nanocomposite is reported. Non-pathogenic bacteria, Gluconacetobacter xylinum, was utilized as a versatile biofactory, which produced biopolymer bacterial cellulose (BC) and induced the formation of Ag/AgCl nanoparticles, yielding BC-Ag/AgCl nanocomposite. Scanning electron microscopy revealed that nanoparticles with average size of 17.4 nm were randomly embedded into the BC network; transmission electron microscopy and X-ray diffraction confirmed that the nanoparticles were mixtures of face-centered cubic silver and silver chloride nanoparticles. Moreover, the content of silver in the BC nanocomposite is around 0.05 wt%, determined by atomic absorption spectrometry and X-ray photoelectron spectroscopy analysis. The entire process of nanocomposite fabrication was conducted at ambient environment without utilizing toxic agents or producing hazardous products, which is not only environmentally friendly but also with less chances to generate harmful products to human bodies as biomedical materials. The resultant nanocomposite displayed the desirable activity in inhibiting bacterial growth of both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli microorganisms on agar plate and in liquid culture, indicating the potential of the material as antimicrobial wound dressing materials. This work demonstrated the feasibility of using microorganism to fabricate nanocomposite, especially for biomedical materials.

A monolithic functional film of nanotubes/cellulose/ionic liquid for high performance supercapacitors

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Basiricò, Lucia; Lanzara, Giulia

2014-12-01

A novel monolithic, pre-fabricated, fully functional film made of a nanostructured free-standing layer is presented for a new and competitive class of easy-to-assemble flexible supercapacitors whose design is in-between the all solid state and the traditional liquid electrolyte. The film is made of two vertically aligned multi-walled carbon nanotube (VANT) electrodes that store ions, embedded-in, and monolithically interspaced by a solution of microcrystalline cellulose in a room temperature ionic liquid (RTIL) electrolyte (1-ethyl-3-methylimidazolium acetate-EMIM Ac). The fine tuning of VANTs length and electrolyte/cellulose amount leads, in a sole and continuous block, to ions storage and physical separation between the electrodes without the need of the additional separator layer that is typically used in supercapacitors. Thus, physical discontinuities that can induce disturbances to ions mobility, are fully eliminated significantly reducing the equivalent series resistance and increasing the knee frequency, hence outclassing the best supercapacitors based on VANTs and non-aqueous electrolytes. The excellent electrochemical response can also be addressed to the chosen electrolyte that, not only has the advantage of leading to a significantly simpler and more affordable fabrication procedure, but has higher ionic conductivity, lower viscosity and higher ions mobility than other electrolytes capable of dissolving cellulose.

Relationship between defect density and charge carrier transport in amorphous and microcrystalline silicon

International Nuclear Information System (INIS)

Astakhov, Oleksandr; Carius, Reinhard; Finger, Friedhelm; Petrusenko, Yuri; Borysenko, Valery; Barankov, Dmytro

2009-01-01

The influence of dangling-bond defects and the position of the Fermi level on the charge carrier transport properties in undoped and phosphorous doped thin-film silicon with structure compositions all the way from highly crystalline to amorphous is investigated. The dangling-bond density is varied reproducibly over several orders of magnitude by electron bombardment and subsequent annealing. The defects are investigated by electron-spin-resonance and photoconductivity spectroscopies. Comparing intrinsic amorphous and microcrystalline silicon, it is found that the relationship between defect density and photoconductivity is different in both undoped materials, while a similar strong influence of the position of the Fermi level on photoconductivity via the charge carrier lifetime is found in the doped materials. The latter allows a quantitative determination of the value of the transport gap energy in microcrystalline silicon. The photoconductivity in intrinsic microcrystalline silicon is, on one hand, considerably less affected by the bombardment but, on the other hand, does not generally recover with annealing of the defects and is independent from the spin density which itself can be annealed back to the as-deposited level. For amorphous silicon and material prepared close to the crystalline growth regime, the results for nonequilibrium transport fit perfectly to a recombination model based on direct capture into neutral dangling bonds over a wide range of defect densities. For the heterogeneous microcrystalline silicon, this model fails completely. The application of photoconductivity spectroscopy in the constant photocurrent mode (CPM) is explored for the entire structure composition range over a wide variation in defect densities. For amorphous silicon previously reported linear correlation between the spin density and the subgap absorption is confirmed for defect densities below 10 18 cm -3 . Beyond this defect level, a sublinear relation is found i.e., not

Preparation and Characterization of Polyvinyl Alcohol-Chitosan Composite Films Reinforced with Cellulose Nanofiber

Science.gov (United States)

Choo, Kaiwen; Ching, Yern Chee; Chuah, Cheng Hock; Julai, Sabariah; Liou, Nai-Shang

2016-01-01

In this study microcrystalline cellulose (MCC) was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The treated cellulose slurry was mechanically homogenized to form a transparent dispersion which consisted of individual cellulose nanofibers with uniform widths of 3–4 nm. Bio-nanocomposite films were then prepared from a polyvinyl alcohol (PVA)-chitosan (CS) polymeric blend with different TEMPO-oxidized cellulose nanofiber (TOCN) contents (0, 0.5, 1.0 and 1.5 wt %) via the solution casting method. The characterizations of pure PVA/CS and PVA/CS/TOCN films were performed in terms of field emission scanning electron microscopy (FESEM), tensile tests, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results from FESEM analysis justified that low loading levels of TOCNs were dispersed uniformly and homogeneously in the PVA-CS blend matrix. The tensile strength and thermal stability of the films were increased with the increased loading levels of TOCNs to a maximum level. The thermal study indicated a slight improvement of the thermal stability upon the reinforcement of TOCNs. As evidenced by the FTIR and XRD, PVA and CS were considered miscible and compatible owing to hydrogen bonding interaction. These analyses also revealed the good dispersion of TOCNs within the PVA/CS polymer matrix. The improved properties due to the reinforcement of TOCNs can be highly beneficial in numerous applications. PMID:28773763

Bacterial cellulose synthesis mechanism of facultative anaerobe Enterobacter sp. FY-07.

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Ji, Kaihua; Wang, Wei; Zeng, Bing; Chen, Sibin; Zhao, Qianqian; Chen, Yueqing; Li, Guoqiang; Ma, Ting

2016-02-25

Enterobacter sp. FY-07 can produce bacterial cellulose (BC) under aerobic and anaerobic conditions. Three potential BC synthesis gene clusters (bcsI, bcsII and bcsIII) of Enterobacter sp. FY-07 have been predicted using genome sequencing and comparative genome analysis, in which bcsIII was confirmed as the main contributor to BC synthesis by gene knockout and functional reconstitution methods. Protein homology, gene arrangement and gene constitution analysis indicated that bcsIII had high identity to the bcsI operon of Enterobacter sp. 638; however, its arrangement and composition were same as those of BC synthesizing operon of G. xylinum ATCC53582 except for the flanking sequences. According to the BC biosynthesizing process, oxygen is not directly involved in the reactions of BC synthesis, however, energy is required to activate intermediate metabolites and synthesize the activator, c-di-GMP. Comparative transcriptome and metabolite quantitative analysis demonstrated that under anaerobic conditions genes involved in the TCA cycle were downregulated, however, genes in the nitrate reduction and gluconeogenesis pathways were upregulated, especially, genes in three pyruvate metabolism pathways. These results suggested that Enterobacter sp. FY-07 could produce energy efficiently under anaerobic conditions to meet the requirement of BC biosynthesis.

[Microcrystalline cellulose and their flow -- morphological properties modifications as an effective excpients in tablet formulation technology containing lattice established API and also dry plant extract].

Science.gov (United States)

Zgoda, Marian Mikołaj; Nachajski, Michał Jakub; Kołodziejczyk, Michał Krzysztof

2009-01-01

The production technology of powder cellulose (Arbocel) and microcrystaline cellulose (Vivapur) and their application in the composition of direct compression tablet mass was provided. The function of silicified microcrystaline cellulose type Prosolv in the direct compression process of dry plant extract was discussed. An analysis of the chemical structure of cellulose fiber (Vitacel) enabled determining its properties and applications in the manufacture of diet supplement, pharmaceutical and food products.

Grafting of bacterial polyhydroxybutyrate (PHB) onto cellulose via in situ reactive extrusion with dicumyl peroxide.

Science.gov (United States)

Wei, Liqing; McDonald, Armando G; Stark, Nicole M

2015-03-09

Polyhydroxybutyrate (PHB) was grafted onto cellulose fiber by dicumyl peroxide (DCP) radical initiation via in situ reactive extrusion. The yield of the grafted (cellulose-g-PHB) copolymer was recorded and grafting efficiency was found to be dependent on the reaction time and DCP concentration. The grafting mechanism was investigated by electron spin resonance (ESR) analysis and showed the presence of radicals produced by DCP radical initiation. The grafted copolymer structure was determined by nuclear magnetic resonance (NMR) spectroscopy. Scanning electronic microscopy (SEM) showed that the cellulose-g-PHB copolymer formed a continuous phase between the surfaces of cellulose and PHB as compared to cellulose-PHB blends. The relative crystallinity of cellulose and PHB were quantified from Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) results, while the absolute degree of crystallinity was evaluated by differential scanning calorimetry (DSC). The reduction of crystallinity indicated the grafting reaction occurred not just in the amorphous region but also slightly in crystalline regions of both cellulose and PHB. The smaller crystal sizes suggested the brittleness of PHB was decreased. Thermogravimetric analysis (TGA) showed that the grafted copolymer was stabilized relative to PHB. By varying the reaction parameters the compositions (%PHB and %cellulose) of resultant cellulose-g-PHB copolymer are expected to be manipulated to obtain tunable properties.

Biosynthesis of Bacterial Cellulose/Carboxylic Multi-Walled Carbon Nanotubes for Enzymatic Biofuel Cell Application

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Pengfei Lv

2016-03-01

Full Text Available Novel nanocomposites comprised of bacterial cellulose (BC with carboxylic multi-walled carbon nanotubes (c-MWCNTs incorporated into the BC matrix were prepared through a simple method of biosynthesis. The biocathode and bioanode for the enzyme biological fuel cell (EBFC were prepared using BC/c-MWCNTs composite injected by laccase (Lac and glucose oxidase (GOD with the aid of glutaraldehyde (GA crosslinking. Biosynthesis of BC/c-MWCNTs composite was characterized by digital photos, scanning electron microscope (SEM, and Fourier Transform Infrared (FTIR. The experimental results indicated the successful incorporation of c-MWCNTs into the BC. The electrochemical and biofuel performance were evaluated by cyclic voltammetry (CV and linear sweep voltammetry (LSV. The power density and current density of EBFCs were recorded at 32.98 µW/cm3 and 0.29 mA/cm3, respectively. Additionally, the EBFCs also showed acceptable stability. Preliminary tests on double cells indicated that renewable BC have great potential in the application field of EBFCs.

Novel keratin modified bacterial cellulose nanocomposite production and characterization for skin tissue engineering.

Science.gov (United States)

Keskin, Zalike; Sendemir Urkmez, Aylin; Hames, E Esin

2017-06-01

As it is known that bacterial cellulose (BC) is a biocompatible and natural biopolymer due to which it has a large set of biomedical applications. But still it lacks some desired properties, which limits its uses in many other applications. Therefore, the properties of BC need to be boosted up to an acceptable level. Here in this study for the first time, a new natural nanocomposite was produced by the incorporating keratin (isolated from human hair) to the BC (produced by Acetobacter xylinum) to enhance dermal fibroblast cells' attachment. Two different approaches were used in BC based nanocomposite production: in situ and post modifications. BC/keratin nanocomposites were characterized using SEM, FTIR, EDX, XRD, DSC and XPS analyses. Both production methods have yielded successful results for production of BC based nanocomposite-containing keratin. In vitro cell culture experiments performed with human skin keratinocytes and human skin fibroblast cells indicate the potential of the novel BC/keratin nanocomposites for use in skin tissue engineering. Copyright © 2017 Elsevier B.V. All rights reserved.

Bacterial-cellulose-derived carbon nanofiber@MnO₂ and nitrogen-doped carbon nanofiber electrode materials: an asymmetric supercapacitor with high energy and power density.

Science.gov (United States)

Chen, Li-Feng; Huang, Zhi-Hong; Liang, Hai-Wei; Guan, Qing-Fang; Yu, Shu-Hong

2013-09-14

A new kind of high-performance asymmetric supercapacitor is designed with pyrolyzed bacterial cellulose (p-BC)-coated MnO₂ as a positive electrode material and nitrogen-doped p-BC as a negative electrode material via an easy, efficient, large-scale, and green fabrication approach. The optimal asymmetric device possesses an excellent supercapacitive behavior with quite high energy and power density. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Post-deposition thermal annealing studies of hydrogenated microcrystalline silicon deposited at 40 deg. C

International Nuclear Information System (INIS)

Bronsveld, P.C.P.; Wagt, H.J. van der; Rath, J.K.; Schropp, R.E.I.; Beyer, W.

2007-01-01

Post-deposition thermal annealing studies, including gas effusion measurements, measurements of infrared absorption versus annealing state, cross-sectional transmission electron microscopy (X-TEM) and atomic force microscopy (AFM), are used for structural characterization of hydrogenated amorphous and microcrystalline silicon films, prepared by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) at low substrate temperature (T S ). Such films are of interest for application in thin semiconductor devices deposited on cheap plastics. For T S ∼ 40 deg. C, H-evolution shows rather complicated spectra for (near-) microcrystalline material, with hydrogen effusion maxima seen at ∼ 200-250 deg. C, 380 deg. C and ∼ 450-500 deg. C, while for the amorphous material typical spectra for good-quality dense material are found. Effusion experiments of implanted He demonstrate for the microcrystalline material the presence of a rather open (void-rich) structure. A similar tendency can be concluded from Ne effusion experiments. Fourier Transform infrared (FTIR) spectra of stepwise annealed samples show Si-H bond rupture already at annealing temperatures of 150 deg. C. Combined AFM/X-TEM studies reveal a columnar microstructure for all of these (near-) microcrystalline materials, of which the open structure is the most probable explanation of the shift of the H-effusion maximum in (near-) microcrystalline material to lower temperature

Production of Bacterial Cellulose by Gluconacetobacter hansenii Using Corn Steep Liquor As Nutrient Sources

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Andrea F. S. Costa

2017-10-01

Full Text Available Cellulose is mainly produced by plants, although many bacteria, especially those belonging to the genus Gluconacetobacter, produce a very peculiar form of cellulose with mechanical and structural properties that can be exploited in numerous applications. However, the production cost of bacterial cellulose (BC is very high to the use of expensive culture media, poor yields, downstream processing, and operating costs. Thus, the purpose of this work was to evaluate the use of industrial residues as nutrients for the production of BC by Gluconacetobacter hansenii UCP1619. BC pellicles were synthesized using the Hestrin–Schramm (HS medium and alternative media formulated with different carbon (sugarcane molasses and acetylated glucose and nitrogen sources [yeast extract, peptone, and corn steep liquor (CSL]. A jeans laundry was also tested. None of the tested sources (beside CSL worked as carbon and nutrient substitute. The alternative medium formulated with 1.5% glucose and 2.5% CSL led to the highest yield in terms of dry and hydrated mass. The BC mass produced in the alternative culture medium corresponded to 73% of that achieved with the HS culture medium. The BC pellicles demonstrated a high concentration of microfibrils and nanofibrils forming a homogenous, compact, and three-dimensional structure. The biopolymer produced in the alternative medium had greater thermal stability, as degradation began at 240°C, while degradation of the biopolymer produced in the HS medium began at 195°C. Both biopolymers exhibited high crystallinity. The mechanical tensile test revealed the maximum breaking strength and the elongation of the break of hydrated and dry pellicles. The dry BC film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film. The dry film supported up to 48 MPa of the breaking strength and exhibited greater than 96.98% stiffness in comparison with the hydrated film

Plasma deposition of microcrystalline silicon solar cells. Looking beyond the glass

Energy Technology Data Exchange (ETDEWEB)

Donker, M.N. van den

2006-07-01

Microcrystalline silicon emerged in the past decade as highly interesting material for application in efficient and stable thin film silicon solar cells. It consists of nanometer-sized crystallites embedded in a micrometer-sized columnar structure, which gradually evolves during the SiH{sub 4} based deposition process starting from an amorphous incubation layer. Understanding of and control over this transient and multi-scale growth process is essential in the route towards low-cost microcrystalline silicon solar cells. This thesis presents an experimental study on the technologically relevant high rate (5-10 Aa s{sup -1}) parallel plate plasma deposition process of state-of-the-art microcrystalline silicon solar cells. The objective of the work was to explore and understand the physical limits of the plasma deposition process as well as to develop diagnostics suitable for process control in eventual solar cell production. Among the developed non-invasive process diagnostics were a pyrometer, an optical spectrometer, a mass spectrometer and a voltage probe. Complete thin film silicon solar cells and modules were deposited and characterized. (orig.)

Assessing the impact of lyophilization process in production of implants based on the bacterial cellulose using Raman spectroscopy method

International Nuclear Information System (INIS)

Timchenko, E V; Timchenko, P E; Pisareva, E V; Vlasov, M Yu; Revin, V V; Klenova, N A; Asadova, A A

2017-01-01

In this article we present the research results of lyophilization process influence on the composition of hybrid materials based on the bacterial cellulose (BC) using Raman spectroscopy method. As an object of research was used BC, as well as hybrids based on it, comprising the various combinations of hydroxyapatite (HAP) and collagen. Our studies showed that during the lyophilization process changes the ratio of the individual components. It was found that for samples hybrid based on BC with addition of HAP occurs increase of PO 4 3- peak intensity in the region 956 cm -1 with decreasing width, which indicates a change in the degree of HAP crystallinity. (paper)

Assessing the impact of lyophilization process in production of implants based on the bacterial cellulose using Raman spectroscopy method

Science.gov (United States)

Timchenko, E. V.; Timchenko, P. E.; Pisareva, E. V.; Vlasov, M. Yu; Revin, V. V.; Klenova, N. A.; Asadova, A. A.

2017-01-01

In this article we present the research results of lyophilization process influence on the composition of hybrid materials based on the bacterial cellulose (BC) using Raman spectroscopy method. As an object of research was used BC, as well as hybrids based on it, comprising the various combinations of hydroxyapatite (HAP) and collagen. Our studies showed that during the lyophilization process changes the ratio of the individual components. It was found that for samples hybrid based on BC with addition of HAP occurs increase of PO4 3- peak intensity in the region 956 cm-1 with decreasing width, which indicates a change in the degree of HAP crystallinity.

Enzymatic Cellulose Palmitate Synthesis Using Immobilized Lipase

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Anna Roosdiana

2017-06-01

Full Text Available Bacterial cellulose can be modified by esterification using palmitic acid and Mucor miehei  lipase  as catalyst. The purpose of this research was to determine the optimum conditions of esterification reaction of cellulose and palmitic acid . The esterification reaction was carried out at the time variation  of  6, 12, 18, 24 and 30 hours and the mass ratio of cellulose: palmitic acid (1: 11: 2, 1: 3, 1: 4, 1: 5,1:6 at 50 °C. The   cellulose palmitate  was examined  its  physical and chemical properties by using FTIR spectrophotometer, XRD, bubble point test and saponification  apparatus. The results showed that the optimum reaction time of esterification reaction of cellulose and palmitic acid occurred within 24 hours and the mass ratio of cellulose: palmitic acid was 1: 3 resulting in DS of  0.376 with  swelling index of 187 %, crystallinity index of 61.95%,  and Φ porous of 2.40 μm. Identification of functional groups using FTIR spectrophotometer showed that C=O ester group  was observed at 1737.74 cm-1 and strengthened  by  the appearance of C-O ester peak at 1280 cm-1. The conclusion of this study is reaction time and reactant ratio influence significantly the DS of cellulose ester.

Bacterial cellulose production by Gluconacetobacter xylinus by employing alternative culture media.

Science.gov (United States)

Jozala, Angela Faustino; Pértile, Renata Aparecida Nedel; dos Santos, Carolina Alves; de Carvalho Santos-Ebinuma, Valéria; Seckler, Marcelo Martins; Gama, Francisco Miguel; Pessoa, Adalberto

2015-02-01

Bacterial cellulose (BC) is used in different fields as a biological material due to its unique properties. Despite there being many BC applications, there still remain many problems associated with bioprocess technology, such as increasing productivity and decreasing production cost. New technologies that use waste from the food industry as raw materials for culture media promote economic advantages because they reduce environmental pollution and stimulate new research for science sustainability. For this reason, BC production requires optimized conditions to increase its application. The main objective of this study was to evaluate BC production by Gluconacetobacter xylinus using industry waste, namely, rotten fruits and milk whey, as culture media. Furthermore, the structure of BC produced at different conditions was also determined. The culture media employed in this study were composed of rotten fruit collected from the disposal of free markets, milk whey from a local industrial disposal, and their combination, and Hestrin and Schramm media was used as standard culture media. Although all culture media studied produced BC, the highest BC yield-60 mg/mL-was achieved with the rotten fruit culture. Thus, the results showed that rotten fruit can be used for BC production. This culture media can be considered as a profitable alternative to generate high-value products. In addition, it combines environmental concern with sustainable processes that can promote also the reduction of production cost.

Production of bacterial cellulose using different carbon sources and culture media.

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Mohammadkazemi, Faranak; Azin, Mehrdad; Ashori, Alireza

2015-03-06

In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) have been studied. BC nanofibers were synthesized using Gluconacetobacter xylinus strain PTCC 1734. Media used were Hestrin-Schramm (H), Yamanaka (Y), and Zhou (Z). Five different carbon sources, namely date syrup, glucose, mannitol, sucrose, and food-grade sucrose were used in these media. All the produced BC pellicles were characterized in terms of dry weight production, biomass yield, thermal stability, crystallinity and morphology by thermogravimetric analysis (TGA), x-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The obtained results showed that mannitol lead to the highest yield, followed by sucrose. The highest production efficiency of mannitol might be due to the nitrogen source, which plays an important role. The maximum improvement on the thermal stability of the composites was achieved when mannitol was used in H medium. In addition, the crystallinity was higher in BC formed in H medium compared to other media. FE-SEM micrographs illustrated that the BC pellicles, synthesized in the culture media H and Z, were stable, unlike those in medium Y that were unstable. The micrographs of BC produced in media containing mannitol and sucrose provided evidence of the strong interfacial adhesion between the BC fibers without noticeable aggregates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Double network bacterial cellulose hydrogel to build a biology-device interface

Science.gov (United States)

Shi, Zhijun; Li, Ying; Chen, Xiuli; Han, Hongwei; Yang, Guang

2013-12-01

Establishing a biology-device interface might enable the interaction between microelectronics and biotechnology. In this study, electroactive hydrogels have been produced using bacterial cellulose (BC) and conducting polymer (CP) deposited on the BC hydrogel surface to cover the BC fibers. The structures of these composites thus have double networks, one of which is a layer of electroactive hydrogels combined with BC and CP. The electroconductivity provides the composites with capabilities for voltage and current response, and the BC hydrogel layer provides good biocompatibility, biodegradability, bioadhesion and mass transport properties. Such a system might allow selective biological functions such as molecular recognition and specific catalysis and also for probing the detailed genetic and molecular mechanisms of life. A BC-CP composite hydrogel could then lead to a biology-device interface. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) are used here to study the composite hydrogels' electroactive property. BC-PAni and BC-PPy respond to voltage changes. This provides a mechanism to amplify electrochemical signals for analysis or detection. BC hydrogels were found to be able to support the growth, spreading and migration of human normal skin fibroblasts without causing any cytotoxic effect on the cells in the cell culture. These double network BC-CP hydrogels are biphasic Janus hydrogels which integrate electroactivity with biocompatibility, and might provide a biology-device interface to produce implantable devices for personalized and regenerative medicine.

Cellulose Nanocrystals Obtained from Cynara Cardunculus and Their Application in the Paper Industry

Directory of Open Access Journals (Sweden)

Valentina Coccia

2014-08-01

Full Text Available Biorefinery aims at designing new virtuous and high-efficiency energy chains, achieving the combined production of biofuels (e.g., bioethanol and biobased products. This emerging philosophy can represent an important opportunity for the industrial world, exploiting a new kind of nano-smart biomaterials in their production chains. This paper will present the lab experience carried out by the Biomass Research Centre (CRB in extracting cellulose nanocrystals (NCC from a pretreated (via Steam Explosion fraction of Cynara cardunculus. This is a very common and invasive arboreal variety in central Italy. The NCC extraction methodology allows the separation of the crystalline content of cellulose. Such a procedure has been considered in the literature with the exception of one step in which the conditions have been optimized by CRB Lab. This procedure has been applied for the production of NCC from both Cynara cardunculus and microcrystalline cellulose (MCC. The paper will discuss some of the results achieved using the obtained nanocrystals as reinforcing filler in a paper sheet; it was found that the tensile strength increased from 3.69 kg/15 mm to 3.98 kg/15 mm, the durability behavior (measured by bending number changed from the value 95 to the value 141, and the barrier properties (measured by Gurley porosity were improved, increasing from 38 s to 45 s.

The preparation by extrusion/spheronization and the properties of pellets containing drugs, microcrystalline cellulose and glyceryl monostearate.

Science.gov (United States)

Chatchawalsaisin, Jittima; Podczeck, Fridrun; Newton, J Michael

2005-01-01

Pellets have been prepared by extrusion and spheronization containing microcrystalline cellulose (MCC) and four model drugs with decreasing order of solubility, paracetamol (P), diclofenac sodium (D), ibuprofen (IB) and indomethacin (IN) at a 10% level with and without the addition of a range of levels of glyceryl monostearate (GMS). The drugs differed in their response to extrusion in that all formulations containing the drug D had a 'steady state' extrusion profile whereas the other three drugs exhibited 'forced flow' indicating the possibility of water migration during the process of ram extrusion. The presence of GMS did not influence this effect. The drug D also required consistently less water to function than the other three drugs. In spite of these differences in extrusion performance, it was possible to prepare satisfactory pellets from formulations of all the drugs with 0, 30 and 60% GMS combined with 90, 60 or 30% of MCC at a range of water levels. It was also possible to prepare pellets containing the drug D with 70, 80 and 90% GMS, with corresponding quantities of 20, 10 and 0% of MCC. It was also possible to prepare the pellet formulations by dispersing the drugs in molten GMS, grinding and processing this with MCC and water. Such systems retained the processing characteristics of the composition made by the blending of the powder. The presence of GMS in all cases reduced the quantity of water required for the process to function. The steady state or the mean of the range of the forces observed during forced flow, were dependent on the composition and the quantity of water added. The surface of the extrudate appeared smooth and measurements of surface roughness established that the value of the rugosity R(a) for any of the extrudates did not exceed 6 microm. The extrudate diameter was found to increase with the quantity of GMS in the formulation. The pellets produced were all within a relatively narrow size range (three sieve fractions of a root two

In vitro behaviors of rat mesenchymal stem cells on bacterial celluloses with different moduli

International Nuclear Information System (INIS)

Taokaew, Siriporn; Phisalaphong, Muenduen; Zhang Newby, Bi-min

2014-01-01

Compressive moduli of bacteria-synthesized cellulose (BC) were altered by two drying techniques: ambient-air drying and freeze drying. While no significant differences in dry weight were found, their cross-sectional structures and thickness varied greatly. Freeze dried BCs had loose cross-sectional structures and a thickness of ∼ 4.7 mm, whereas air dried BCs had more compacted cross-sectional structures and a thickness of ∼ 0.1 mm. The compressive moduli of the rehydrated freeze dried and rehydrated air dried BCs were measured to be 21.06 ± 0.22 kPa and 90.09 ± 21.07 kPa, respectively. When rat mesenchymal stem cells (rMSCs) were seeded on these BCs, they maintained a round morphology in the first 3 days of cultivation. More spread-out morphology and considerable proliferation on freeze dried BCs were observed in 7 days, but not on air-dried BCs. The cells were further grown for 3 weeks in the absence and presence of differentiation agents. Without using any differentiation agents, no detectable differentiation was noticed for rMSCs further cultivated on both types of BC. With differentiation inducing agents, chondrogenic differentiation, visualized by histological staining, was observed in some area of the rehydrated freeze dried BCs; while osteogenic differentiation was noticed on the stiffer rehydrated air dried BCs. - Graphical abstract: In the presence of induction agents, rat mesenchymal stem cells (rMSCs) preferentially differentiated into osteocytes on stiffer air dried BC films. - Highlights: • Bacterial cellulose (BC) sheets with different moduli generated by drying differently • Air-dried BC exhibited a modulus similar to that of bone. • Freeze-dried BC showed a modulus in the range of that of muscle. • Air-dried BC promoted the differentiation of rMSCs into osteocytes. • Freeze-dried BC promoted the differentiation of rMSCs into chondrocytes

In vitro behaviors of rat mesenchymal stem cells on bacterial celluloses with different moduli

Energy Technology Data Exchange (ETDEWEB)

Taokaew, Siriporn [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325-3906 (United States); Phisalaphong, Muenduen [Department of Chemical Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330 (Thailand); Zhang Newby, Bi-min, E-mail: bimin@uakron.edu [Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325-3906 (United States)

2014-05-01

Compressive moduli of bacteria-synthesized cellulose (BC) were altered by two drying techniques: ambient-air drying and freeze drying. While no significant differences in dry weight were found, their cross-sectional structures and thickness varied greatly. Freeze dried BCs had loose cross-sectional structures and a thickness of ∼ 4.7 mm, whereas air dried BCs had more compacted cross-sectional structures and a thickness of ∼ 0.1 mm. The compressive moduli of the rehydrated freeze dried and rehydrated air dried BCs were measured to be 21.06 ± 0.22 kPa and 90.09 ± 21.07 kPa, respectively. When rat mesenchymal stem cells (rMSCs) were seeded on these BCs, they maintained a round morphology in the first 3 days of cultivation. More spread-out morphology and considerable proliferation on freeze dried BCs were observed in 7 days, but not on air-dried BCs. The cells were further grown for 3 weeks in the absence and presence of differentiation agents. Without using any differentiation agents, no detectable differentiation was noticed for rMSCs further cultivated on both types of BC. With differentiation inducing agents, chondrogenic differentiation, visualized by histological staining, was observed in some area of the rehydrated freeze dried BCs; while osteogenic differentiation was noticed on the stiffer rehydrated air dried BCs. - Graphical abstract: In the presence of induction agents, rat mesenchymal stem cells (rMSCs) preferentially differentiated into osteocytes on stiffer air dried BC films. - Highlights: • Bacterial cellulose (BC) sheets with different moduli generated by drying differently • Air-dried BC exhibited a modulus similar to that of bone. • Freeze-dried BC showed a modulus in the range of that of muscle. • Air-dried BC promoted the differentiation of rMSCs into osteocytes. • Freeze-dried BC promoted the differentiation of rMSCs into chondrocytes.

The ability of retention, drug release and rheological properties of nanogel bioadhesives based on cellulose derivatives.

Science.gov (United States)

Keshavarz, M; Kaffashi, B

2014-12-01

The rheological and drug release behavior of biopolymer nanocomposite gels based on the cellulose derivatives, formulated as the bioadhesive drug delivery platforms, were investigated. The bioadhesive gel is composed of the microcrystalline cellulose, sodium carboxymethyl cellulose and phosphate buffered saline (pH = 7.4 at 20 °C) as the dissolution and release medium. The reinforcing nanofillers such as MMT-clay, fumed porous silica and porous starch were used as additives in the nanogel bioadhesive. The constant steady state viscosities of this nanogels upon incorporation of various nanofillers into the systems is the sign of structural stability. Hence, this system is suitable for use in the controlled drug delivery systems in contact with the biological tissues. Based on the rheological measurements, the shear flow properties (i.e. zero shear viscosity and yield stress) were influenced by the concentration of polymers and nanoparticles. The results indicate that the nonlinear rheological data are fitted properly by the Giesekus model. Furthermore, the results showed that the nonlinear viscoelastic parameters (λ and α) are highly affected by the biogel and nanoparticles concentrations. Finally, the drug release was measured, and the results indicated that the biopolymer-clay nanocomposites have appropriate release pattern as the release is better controlled compared to the other nanogel formulations.

Morphological structure of Gluconacetobacter xylinus cellulose and cellulose-based organic-inorganic composite materials

Science.gov (United States)

Smyslov, R. Yu; Ezdakova, K. V.; Kopitsa, G. P.; Khripunov, A. K.; Bugrov, A. N.; Tkachenko, A. A.; Angelov, B.; Pipich, V.; Szekely, N. K.; Baranchikov, A. E.; Latysheva, E.; Chetverikov, Yu O.; Haramus, V.

2017-05-01

Scanning electron microscopy, ultra-small-angle neutron scattering (USANS), small-angle neutron and X-ray scattering (SANS and SAXS), as well as low-temperature nitrogen adsorption, were used in the studies of micro- and mesostructure of polymer matrix prepared from air-dry preliminarily disintegrated cellulose nano-gel film (synthesized by Gluconacetobacter xylinus) and the composites based on this bacterial cellulose. The composites included ZrO2 nanoparticles, Tb3+ in the form of low molecular weight salt and of metal-polymer complex with poly(vinylpyrrolydone)-poly(methacryloyl-o-aminobenzoic acid) copolymer. The combined analysis of the data obtained allowed revealing three levels of fractal organization in mesostructure of G. xylinus cellulose and its composites. It was shown that both the composition and an aggregation state of dopants have a significant impact on the structural characteristics of the organic-inorganic composites. The composites containing Tb3+ ions demonstrate efficient luminescence; its intensity is an order of magnitude higher in the case of the composites with the metal-polymer complex. It was found that there is the optimal content of ZrO2 nanoparticles in composites resulting in increased Tb3+ luminescence.

Preparation and characterization of mucinated cellulose microparticles for therapeutic and drug delivery purposes.

Science.gov (United States)

Builders, Philip F; Ibekwe, Nneka; Okpako, Larry C; Attama, Anthony A; Kunle, Olobayo O

2009-05-01

Mucinated cellulose microparticles were generated by mixing equal concentrations of colloidal dispersions of porcine mucin (Mc) and microcrystalline cellulose (MCC). The hybrid polymer was recovered by precipitating at controlled temperature and pH conditions using acetone. Some physicochemical, functional and thermal properties of the hybrid polymer were determined and compared with those of Mc and MCC. The new polymer Mc-MCC had swelling and moisture sorption profiles that were different from those of Mc and MCC in buffer solutions with different pH values and relative humidity, respectively. The mucoadhesive property of the new polymer was similar to that of Mc. The scanning electron micrographs (SEMs) showed that the microparticles generated from the hybridization were similar to those of MCC, but with larger and denser particles. The Fourier Transform Infrared (FT-IR) spectrum and Differential Scanning Calorimeter (DSC) thermogram of the hybrid polymer were characteristically different from those of Mc and MCC. The presence of new peaks in the FT-IR spectrum and distinct cold crystallization exotherm, which were absent in both Mc and MCC, confirms the formation of a new polymer type with synergistic physicochemical and functional properties.

Structural characterization of cellulosic materials using x-ray and neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Penttila, P.

2013-11-01

Cellulosic biomass can be used as a feedstock for sustainable production of biofuels and various other products. A complete utilization of the raw material requires understanding on its structural aspects and their role in the various processes. In this thesis, x-ray and neutron scattering methods were applied to study the structure of various cellulosic materials and how they are affected in different processes. The obtained results were reviewed in the context of a model for the cellulose nanostructure. The dimensions of cellulose crystallites and the crystallinity were determined with wide-angle x-ray scattering (WAXS), whereas the nanoscale fibrillar structure of cellulose was characterized with small-angle x-ray and neutron scattering (SAXS and SANS). The properties determined with the small-angle scattering methods included specific surface areas and distances characteristic of the packing of cellulose microfibrils. Also other physical characterization methods, such as x-ray microtomography, infrared spectroscopy, and solid-state NMR were utilized in this work. In the analysis of the results, a comprehensive understanding of the structural changes throughout a range of length scales was aimed at. Pretreatment of birch sawdust by pressurized hot water extraction was observed to increase the crystal width of cellulose, as determined with WAXS, even though the cellulose crystallinity was slightly decreased. A denser packing of microfibrils caused by the removal of hemicelluloses and lignin in the extraction was evidenced by SAXS. This resulted in the opening of new pores between the microfibril bundles and an increase of the specific surface area. Enzymatic hydrolysis of microcrystalline cellulose (MCC) did not lead to differences in the average crystallinity or crystal size of the hydrolysis residues, which was explained to be caused by limitations due to the large size of the enzymes as compared to the pores inside the fibril aggregates. The SAXS intensities

Fabrication and characterization of regenerated cellulose films obtained from oil palm empty fruit bunch

Science.gov (United States)

Nor Amalini, A.; Melina Cheah, M. Y.; Wan Rosli, W. D.; Hayati, S.; Mohamad Haafiz, M. K.

2017-12-01

Development of regenerated cellulose (RC) derived from underutilized cellulosic biomass has recently gained attention as potential petroleum-based polymer replacers. The objective of this current work is to evaluate the properties of RC films obtained from oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC) through environmental process. The RC films were fabricated by using different amounts of OPEFB-MCC (4, 6 and 8 %) and 1-butyl-3-methylimidazolium chloride (BMIMCl) was used as green OPEFB-MCC dissolving medium. The resultant RC films were then characterized by means of Fourier transform infrared (FTIR) spectroscopy, mechanical, thermal and morphological properties by using tensile test, differential scanning colorimetry (DSC), and scanning electron microscopy (SEM) respectively. Increase in OPEFB-MCC amounts from 4 to 8 % enhanced the tensile strength and elongation at break of RC by 101 and 78 %, respectively, indicating stronger and more flexible films were formed. It is interesting to note that the Tg (101-154 °C) and Tm(130-187 °C) were found shifted to higher temperature with higher proportions of OPEFB-MCC in RC films. Meanwhile, FTIR analysis showed no new peak presented in RC films, suggesting that BMIMCl is a non-derivatizing solvent to OPEFB-MCC. Conspicuous changes in the spectra of RC films compared to OPEFB-MCC at 3200-3600 cm-1, 1430 cm-1, 1162 cm-1, 1111 cm-1, 1020-1040 cm-1 and 896 cm-1 were associated with transformation of cellulose I to cellulose II structure or/and decrease in crystallinity occurred after regeneration process. SEM micrographs of the RC films revealed that higher OPEFB-MCC contents exhibited smoother and more homogeneous surfaces morphology. Overall, OPEFB-MCC exhibited good film forming ability for RC production and may offer potential application in various industries including food packaging, medical goods and electronic devices.

Fermentation Tecniques and Applications of Bacterial Cellulose: a Review Técnicas de fermentación y aplicaciones de la celulosa bacteriana: una revisión

Directory of Open Access Journals (Sweden)

Luz Dary Carreño Pineda

2012-12-01

Full Text Available Bacterial cellulose is a polymer obtained by fermentation with microorganismsfrom Acetobacter, Rhizobium, Agrobacterium and Sarcina genera. Amongthem, Acetobacter xylinum is the most efficient specie. This polymer hasthe same chemical composition of plant cellulose, but its conformation andphysicochemical properties are different, making it attractive for several applications, especially in the areas of food, separation processes, catalysis andhealth, due to its biocompatibility. However, the main problem is the production in mass that is constrained by low yield. It is therefore necessaryto develop some alternatives. This paper presents a review about synthesis,production, properties and principal applications of bacterial cellulose, as wellas some alternatives to reduce the difficulties for process scaling.La celulosa bacteriana es un polímero obtenido por fermentación con microrganismosde los géneros Acetobacter, Rhizobium, Agrobacterium y Sarcina, delas cuales la especie más eficiente es la Acetobacter Xylinum. Este polímero presenta la misma estructura química de la celulosa de origen vegetal, pero difiereen su conformación y propiedades fisicoquímicas, lo que lo hace atractivo para diversas aplicaciones, especialmente en las áreas de alimentos, procesosde separación, catálisis y en medicina, gracias a su biocompatibilidad. Sin embargo, el principal problema es la producción a gran escala limitada por losbajos rendimientos, lo que genera la necesidad de desarrollar alternativas que permitan disminuir o eliminar las causas de esta limitación. En este artículo se hace una revisión acerca de la síntesis, producción, propiedades y principales aplicaciones de la celulosa bacteriana, así como de algunas alternativas estudiadas para disminuir los inconvenientes en el escalamiento del proceso.

Cellulose Degradation by Cellulose-Clearing and Non-Cellulose-Clearing Brown-Rot Fungi

OpenAIRE

Highley, Terry L.

1980-01-01

Cellulose degradation by four cellulose-clearing brown-rot fungi in the Coniophoraceae—Coniophora prasinoides, C. puteana, Leucogyrophana arizonica, and L. olivascens—is compared with that of a non-cellulose-clearing brown-rot fungus, Poria placenta. The cellulose- and the non-cellulose-clearing brown-rot fungi apparently employ similar mechanisms to depolymerize cellulose; most likely a nonenzymatic mechanism is involved.

Conductivity-Dependent Strain Response of Carbon Nanotube Treated Bacterial Nanocellulose

Directory of Open Access Journals (Sweden)

S. Farjana

2013-01-01

Full Text Available This paper reports the strain sensitivity of flexible, electrically conductive, and nanostructured cellulose which was prepared by modification of bacterial cellulose with double-walled carbon nanotubes (DWCNTs and multiwalled carbon nanotubes (MWCNTs. The electrical conductivity depends on the modifying agent and its dispersion process. The conductivity of the samples obtained from bacterial cellulose (BNC pellicles modified with DWCNT was in the range from 0.034 S·cm−1 to 0.39 S·cm−1, and for BNC pellicles modified with MWCNTs it was from 0.12 S·cm−1 to 1.6 S·cm−1. The strain-induced electromechanical response, resistance versus strain, was monitored during the application of tensile force in order to study the sensitivity of the modified nanocellulose. A maximum gauge factor of 252 was found from the highest conductive sample treated by MWCNT. It has been observed that the sensitivity of the sample depends on the conductivity of the modified cellulose.

Impregnation of silver sulfadiazine into bacterial cellulose for antimicrobial and biocompatible wound dressing

International Nuclear Information System (INIS)

Luan, Jiabin; Wu, Jian; Zheng, Yudong; Wang, Guojie; Guo, Jia; Ding, Xun; Song, Wenhui

2012-01-01

Silver sulfadiazine (SSD) is a useful antimicrobial agent for wound treatment. However, recent findings indicate that conventional SSD cream has several drawbacks for use in treatments. Bacterial cellulose (BC) is a promising material for wound dressing due to its outstanding properties of holding water, strength and degradability. Unfortunately, BC itself exhibits no antimicrobial activity. A combination of SSD and BC is envisaged to form a new class of wound dressing with both antimicrobial activity and biocompatibility, which has not been reported to date. To achieve antimicrobial activity, SSD particles were impregnated into BC by immersing BC into SSD suspension after ultrasonication, namely SSD–BC. Parameters influencing SSD–BC impregnation were systematically studied. Optimized conditions of sonication time for no less than 90 min and the proper pH value between 6.6 and 9.0 were suggested. The absorption of SSD onto the BC nanofibrous network was revealed by XRD and SEM analyses. The SSD–BC membranes exhibited significant antimicrobial activities against Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus evaluated by the disc diffusion method. In addition, the favorable biocompatibility of SSD–BC was verified by MTT colorimetry, epidermal cell counting method and optical microscopy. The results demonstrate the potential of SSD–BC membranes as a new class of antimicrobial and biocompatible wound dressing. (paper)

Mechanical and thermal properties of bacterial-cellulose-fibre-reinforced Mater-Bi(®) bionanocomposite.

Science.gov (United States)

Nainggolan, Hamonangan; Gea, Saharman; Bilotti, Emiliano; Peijs, Ton; Hutagalung, Sabar D

2013-01-01

The effects of the addition of fibres of bacterial cellulose (FBC) to commercial starch of Mater-Bi(®) have been investigated. FBC produced by cultivating Acetobacter xylinum for 21 days in glucose-based medium were purified by sodium hydroxide 2.5 wt % and sodium hypochlorite 2.5 wt % overnight, consecutively. To obtain water-free BC nanofibres, the pellicles were freeze dried at a pressure of 130 mbar at a cooling rate of 10 °C min(-1). Both Mater-Bi and FBC were blended by using a mini twin-screw extruder at 160 °C for 10 min at a rotor speed of 50 rpm. Tensile tests were performed according to ASTM D638 to measure the Young's modulus, tensile strength and elongation at break. A field emission scanning electron microscope was used to observe the morphology at an accelerating voltage of 10 kV. The crystallinity (T c) and melting temperature (T m) were measured by DSC. Results showed a significant improvement in mechanical and thermal properties in accordance with the addition of FBC into Mater-Bi. FBC is easily incorporated in Mater-Bi matrix and produces homogeneous Mater-Bi/FBC composite. The crystallinity of the Mater-Bi/FBC composites decrease in relation to the increase in the volume fraction of FBC.

Mechanical and thermal properties of bacterial-cellulose-fibre-reinforced Mater-Bi® bionanocomposite

Directory of Open Access Journals (Sweden)

Hamonangan Nainggolan

2013-05-01

Full Text Available The effects of the addition of fibres of bacterial cellulose (FBC to commercial starch of Mater-Bi® have been investigated. FBC produced by cultivating Acetobacter xylinum for 21 days in glucose-based medium were purified by sodium hydroxide 2.5 wt % and sodium hypochlorite 2.5 wt % overnight, consecutively. To obtain water-free BC nanofibres, the pellicles were freeze dried at a pressure of 130 mbar at a cooling rate of 10 °C min−1. Both Mater-Bi and FBC were blended by using a mini twin-screw extruder at 160 °C for 10 min at a rotor speed of 50 rpm. Tensile tests were performed according to ASTM D638 to measure the Young’s modulus, tensile strength and elongation at break. A field emission scanning electron microscope was used to observe the morphology at an accelerating voltage of 10 kV. The crystallinity (Tc and melting temperature (Tm were measured by DSC. Results showed a significant improvement in mechanical and thermal properties in accordance with the addition of FBC into Mater-Bi. FBC is easily incorporated in Mater-Bi matrix and produces homogeneous Mater-Bi/FBC composite. The crystallinity of the Mater-Bi/FBC composites decrease in relation to the increase in the volume fraction of FBC.

Enriched glucose and dextrin mannitol-based media modulates fibroblast behavior on bacterial cellulose membranes

Energy Technology Data Exchange (ETDEWEB)

Stumpf, Taisa R.; Pértile, Renata A.N. [Integrated Technologies Laboratory, Department of Chemical and Food Engineering (Brazil); Rambo, Carlos R., E-mail: rambo@intelab.ufsc.br [Department of Electrical Engineering, Federal University of Santa Catarina, Florianópolis 88040-900 (Brazil); Porto, Luismar M. [Integrated Technologies Laboratory, Department of Chemical and Food Engineering (Brazil)

2013-12-01

Bacterial cellulose (BC) produced by Gluconacetobacter hansenii is a suitable biopolymer for biomedical applications. In order to modulate the properties of BC and expand its use as substrate for tissue engineering mainly in the form of biomembranes, glucose or dextrin were added into a BC fermentation mannitol-based medium (BCGl and BCDe, respectively) under static culture conditions. SEM images showed effects on fiber density and porosity on both sides of the BC membranes. Both enriched media decreased the BET surface area, water holding capacity, and rehydration rate. Fourier transform infrared (attenuated total reflectance mode) spectroscopy (FTIR-ATR) analysis revealed no change in the chemical structure of BC. L929 fibroblast cells were seeded on all BC-based membranes and evaluated in aspects of cell adhesion, proliferation and morphology. BCG1 membranes showed the highest biological performance and hold promise for the use in tissue engineering applications. - Highlights: • Glucose and dextrin were used to modify culture media for BC production. • Microarchitecture of BC was different depending on the enriching agent. • Fibroblasts adhered on the surface of BC modified microarchitectures. • Fibroblasts adhered on glucose modified BC exhibited healthy cell morphology.

Enriched glucose and dextrin mannitol-based media modulates fibroblast behavior on bacterial cellulose membranes

International Nuclear Information System (INIS)

Stumpf, Taisa R.; Pértile, Renata A.N.; Rambo, Carlos R.; Porto, Luismar M.

2013-01-01

Bacterial cellulose (BC) produced by Gluconacetobacter hansenii is a suitable biopolymer for biomedical applications. In order to modulate the properties of BC and expand its use as substrate for tissue engineering mainly in the form of biomembranes, glucose or dextrin were added into a BC fermentation mannitol-based medium (BCGl and BCDe, respectively) under static culture conditions. SEM images showed effects on fiber density and porosity on both sides of the BC membranes. Both enriched media decreased the BET surface area, water holding capacity, and rehydration rate. Fourier transform infrared (attenuated total reflectance mode) spectroscopy (FTIR-ATR) analysis revealed no change in the chemical structure of BC. L929 fibroblast cells were seeded on all BC-based membranes and evaluated in aspects of cell adhesion, proliferation and morphology. BCG1 membranes showed the highest biological performance and hold promise for the use in tissue engineering applications. - Highlights: • Glucose and dextrin were used to modify culture media for BC production. • Microarchitecture of BC was different depending on the enriching agent. • Fibroblasts adhered on the surface of BC modified microarchitectures. • Fibroblasts adhered on glucose modified BC exhibited healthy cell morphology

PLLA-grafted cellulose nanocrystals: Role of the CNC content and grafting on the PLA bionanocomposite film properties.

Science.gov (United States)

Lizundia, Erlantz; Fortunati, Elena; Dominici, Franco; Vilas, José Luis; León, Luis Manuel; Armentano, Ilaria; Torre, Luigi; Kenny, Josè M

2016-05-20

Cellulose nanocrystals (CNC), extracted from microcrystalline cellulose by acid hydrolysis, were grafted by ring opening polymerization of L-Lactide initiated from the hydroxyl groups available at their surface and two different CNC:L-lactide ratios (20:80 and 5:95) were obtained. The resulting CNC-g-PLLA nanohybrids were incorporated in poly(lactic acid) (PLA) matrix by an optimized extrusion process at two different content (1 wt.% and 3 wt.%) and obtained bionanocomposite films were characterized by thermal, mechanical, optical and morphological properties. Thermal analysis showed CNC grafted with the higher ratio of lactide play a significant role as a nucleating agent. Moreover, they contribute to a significant increase in the crystallization rate of PLA, and the best efficiency was revealed with 3 wt.% of CNC-g-PLLA. This effect was confirmed by the increased in Young's modulus, suggesting the CNC graft ratio and content contribute significantly to the good dispersion in the matrix, positively affecting the final bionanocomposite properties. Copyright © 2016 Elsevier Ltd. All rights reserved.

The microbial ecology of anaerobic cellulose degradation in municipal waste landfill sites: evidence of a role for fibrobacters.

Science.gov (United States)

McDonald, James E; Houghton, James N I; Rooks, David J; Allison, Heather E; McCarthy, Alan J

2012-04-01

Cellulose is reputedly the most abundant organic polymer in the biosphere, yet despite the fundamental role of cellulolytic microorganisms in global carbon cycling and as potential sources of novel enzymes for biotechnology, their identity and ecology is not well established. Cellulose is a major component of landfill waste and its degradation is therefore a key feature of the anaerobic microbial decomposition process. Here, we targeted a number of taxa containing known cellulolytic anaerobes (members of the bacterial genus Fibrobacter, lineages of Clostridium clusters I, III, IV and XIV, and anaerobic fungi of the Neocallimastigales) in landfill leachate and colonized cellulose 'baits' via PCR and quantitative PCR (qPCR). Fibrobacter spp. and Clostridium clusters III, IV and XIV were detected in almost all leachate samples and cluster III and XIV clostridia were the most abundant (1-6% and 1-17% of total bacterial 16S rRNA gene copies respectively). Two landfill leachate microcosms were constructed to specifically assess those microbial communities that colonize and degrade cellulose substrates in situ. Scanning electron microscopy (SEM) of colonized cotton revealed extensive cellulose degradation in one microcosm, and Fibrobacter spp. and Clostridium cluster III represented 29% and 17%, respectively, of total bacterial 16S rRNA gene copies in the biofilm. Visible cellulose degradation was not observed in the second microcosm, and this correlated with negligible relative abundances of Clostridium cluster III and Fibrobacter spp. (≤ 0.1%), providing the first evidence that the novel fibrobacters recently detected in landfill sites and other non-gut environments colonize and degrade cellulose substrates in situ. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Carrier mobilities in microcrystalline silicon films

International Nuclear Information System (INIS)

Bronger, T.; Carius, R.

2007-01-01

For a better understanding of electronic transport mechanisms in thin-film silicon solar cell quality films, we have investigated the Hall mobility for electrons in microcrystalline/amorphous silicon over a range of crystallinities and doping concentrations. We find that Hall mobility increases with increasing doping concentration in accordance with earlier measurements. With increasing amorphous fraction, the measured mobility decreases suggesting a negative influence of the additional disorder. The results suggest a differential mobility model in which mobility depends on the energy level of the carriers that contribute to the electrical current

Biotechnological applications of bacterial cellulases

Czech Academy of Sciences Publication Activity Database

Menéndez, E.; García-Fraile, Paula; Rivas, R.

2015-01-01

Roč. 2, č. 3 (2015), s. 163-182 ISSN 2306-5354 R&D Projects: GA MŠk(CZ) EE2.3.30.0003 Institutional support: RVO:61388971 Keywords : Biotechnological applications * Bacterial cellulases * Cellulose degradation Subject RIV: EE - Microbiology, Virology

The atomic hydrogen flux during microcrystalline silicon solar cell deposition

NARCIS (Netherlands)

Sanden, van de M.C.M.; Dingemans, G.; van den Donker, M.N.; Hrunski, D.; Gordijn, A.; Kessels, W.M.M.

2009-01-01

Etch product detection by in situ optical emission spectroscopy is used to detect the phase transition from amorphous to microcrystalline silicon. In this contribution it is demonstrated that a calibrated version of this technique can be used to determine the absolute hydrogen flux under

Some historical remarks on microcrystalline arthritis (gout and chondrocalcinosis

Directory of Open Access Journals (Sweden)

G. Pasero

2012-01-01

Full Text Available The history of microcrystalline arthritis only began in 1961 when Daniel McCarty and Joseph Lee Hollander demonstrated the presence of sodium monourate crystals in the synovial fluid of gouty patients. However, gout is a historical disease, thanks to the descriptions of Hippocrates, Caelius Aurelianus, Soranus of Ephesus and Araeteus of Cappadocia. The relationship between hyperuricemia and gout was first documented in the nineteenth century by Alfred Baring Garrod, who demonstrated deposits of uric acid crystals on a linen thread held dipped in acidified blood (the so-called “thread method”. Gout has always been considered a prerogative of the moneyed classes (arthritis divitum, and history is full of famous gouty personalities, including kings, emperors, popes, commanders, politicians, artists, writers, philosophers and scientists. Another form of microcrystalline arthritis, chondrocalcinosis, was identified as being a rheumatic disorder different from gout in the 1960s. As a specific clinical entity, it was first identified in 1958 by Dušan Žitnˇan and Štefan Sit’aj in a few Slovak families.

Multiscale Modulation of Nanocrystalline Cellulose Hydrogel via Nanocarbon Hybridization for 3D Neuronal Bilayer Formation.

Science.gov (United States)

Kim, Dongyoon; Park, Subeom; Jo, Insu; Kim, Seong-Min; Kang, Dong Hee; Cho, Sung-Pyo; Park, Jong Bo; Hong, Byung Hee; Yoon, Myung-Han

2017-07-01

Bacterial biopolymers have drawn much attention owing to their unconventional three-dimensional structures and interesting functions, which are closely integrated with bacterial physiology. The nongenetic modulation of bacterial (Acetobacter xylinum) cellulose synthesis via nanocarbon hybridization, and its application to the emulation of layered neuronal tissue, is reported. The controlled dispersion of graphene oxide (GO) nanoflakes into bacterial cellulose (BC) culture media not only induces structural changes within a crystalline cellulose nanofibril, but also modulates their 3D collective association, leading to substantial reduction in Young's modulus (≈50%) and clear definition of water-hydrogel interfaces. Furthermore, real-time investigation of 3D neuronal networks constructed in this GO-incorporated BC hydrogel with broken chiral nematic ordering revealed the vertical locomotion of growth cones, the accelerated neurite outgrowth (≈100 µm per day) with reduced backward travel length, and the efficient formation of synaptic connectivity with distinct axonal bifurcation abundancy at the ≈750 µm outgrowth from a cell body. In comparison with the pristine BC, GO-BC supports the formation of well-defined neuronal bilayer networks with flattened interfacial profiles and vertical axonal outgrowth, apparently emulating the neuronal development in vivo. We envisioned that our findings may contribute to various applications of engineered BC hydrogel to fundamental neurobiology studies and neural engineering. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cellulose supplementation early in life ameliorates colitis in adult mice.

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Dorottya Nagy-Szakal

Full Text Available Decreased consumption of dietary fibers, such as cellulose, has been proposed to promote the emergence of inflammatory bowel diseases (IBD: Crohn disease [CD] and ulcerative colitis [UC] where intestinal microbes are recognized to play an etiologic role. However, it is not known if transient fiber consumption during critical developmental periods may prevent consecutive intestinal inflammation. The incidence of IBD peaks in young adulthood indicating that pediatric environmental exposures may be important in the etiology of this disease group. We studied the effects of transient dietary cellulose supplementation on dextran sulfate sodium (DSS colitis susceptibility during the pediatric period in mice. Cellulose supplementation stimulated substantial shifts in the colonic mucosal microbiome. Several bacterial taxa decreased in relative abundance (e.g., Coriobacteriaceae [p = 0.001], and other taxa increased in abundance (e.g., Peptostreptococcaceae [p = 0.008] and Clostridiaceae [p = 0.048]. Some of these shifts persisted for 10 days following the cessation of cellulose supplementation. The changes in the gut microbiome were associated with transient trophic and anticolitic effects 10 days following the cessation of a cellulose-enriched diet, but these changes diminished by 40 days following reversal to a low cellulose diet. These findings emphasize the transient protective effect of dietary cellulose in the mammalian large bowel and highlight the potential role of dietary fibers in amelioration of intestinal inflammation.

Cellulose Supplementation Early in Life Ameliorates Colitis in Adult Mice

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Nagy-Szakal, Dorottya; Hollister, Emily B.; Luna, Ruth Ann; Szigeti, Reka; Tatevian, Nina; Smith, C. Wayne; Versalovic, James; Kellermayer, Richard

2013-01-01

Decreased consumption of dietary fibers, such as cellulose, has been proposed to promote the emergence of inflammatory bowel diseases (IBD: Crohn disease [CD] and ulcerative colitis [UC]) where intestinal microbes are recognized to play an etiologic role. However, it is not known if transient fiber consumption during critical developmental periods may prevent consecutive intestinal inflammation. The incidence of IBD peaks in young adulthood indicating that pediatric environmental exposures may be important in the etiology of this disease group. We studied the effects of transient dietary cellulose supplementation on dextran sulfate sodium (DSS) colitis susceptibility during the pediatric period in mice. Cellulose supplementation stimulated substantial shifts in the colonic mucosal microbiome. Several bacterial taxa decreased in relative abundance (e.g., Coriobacteriaceae [p = 0.001]), and other taxa increased in abundance (e.g., Peptostreptococcaceae [p = 0.008] and Clostridiaceae [p = 0.048]). Some of these shifts persisted for 10 days following the cessation of cellulose supplementation. The changes in the gut microbiome were associated with transient trophic and anticolitic effects 10 days following the cessation of a cellulose-enriched diet, but these changes diminished by 40 days following reversal to a low cellulose diet. These findings emphasize the transient protective effect of dietary cellulose in the mammalian large bowel and highlight the potential role of dietary fibers in amelioration of intestinal inflammation. PMID:23437211

Effects of alternative energy sources on bacterial cellulose characteristics produced by Komagataeibacter medellinensis.

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Molina-Ramírez, Carlos; Enciso, Carla; Torres-Taborda, Mabel; Zuluaga, Robin; Gañán, Piedad; Rojas, Orlando J; Castro, Cristina

2018-05-27

Bacterial cellulose (BC) was produced by Komagataeibacter medellinensis using Hestrin and Schramm modified medium in the presence of alternative energy sources (AES), such as ethanol and acetic acid, to explore the effect of AES on the characteristics and properties of the resulting BC. In this study, the physicochemical and structural characteristics of the obtained BC were determined using Fourier-transform infrared spectroscopy, X-ray diffraction spectrometry, thermogravimetric analysis, and mechanical testing analysis. Ethanol and acetic acid (at 0.1 wt%) were proven to improve the BC yield by K. medellinensis by 279% and 222%, respectively. However, the crystallinity index (%), the degree of polymerization, and maximum rate of degradation temperatures decreased by 9.2%, 36%, and 4.96%, respectively, by the addition of ethanol and by 7.2%, 27%, and 4.21%, respectively, by the addition of acetic acid. The significance of this work, lies on the fact that there is not any report about how BC properties change when substances like ethanol or acetic acid are added to culture medium, and which is the mechanism that provokes those changes, that in our case we could demonstrate the relationship of a higher BC production rate (provoked by ethanol and acetic acid adding) and changes in BC properties. Copyright © 2018 Elsevier B.V. All rights reserved.

Cellulose as an Architectural Element in Spatially Structured Escherichia coli Biofilms

Science.gov (United States)

Serra, Diego O.; Richter, Anja M.

2013-01-01

Morphological form in multicellular aggregates emerges from the interplay of genetic constitution and environmental signals. Bacterial macrocolony biofilms, which form intricate three-dimensional structures, such as large and often radially oriented ridges, concentric rings, and elaborate wrinkles, provide a unique opportunity to understand this interplay of “nature and nurture” in morphogenesis at the molecular level. Macrocolony morphology depends on self-produced extracellular matrix components. In Escherichia coli, these are stationary phase-induced amyloid curli fibers and cellulose. While the widely used “domesticated” E. coli K-12 laboratory strains are unable to generate cellulose, we could restore cellulose production and macrocolony morphology of E. coli K-12 strain W3110 by “repairing” a single chromosomal SNP in the bcs operon. Using scanning electron and fluorescence microscopy, cellulose filaments, sheets and nanocomposites with curli fibers were localized in situ at cellular resolution within the physiologically two-layered macrocolony biofilms of this “de-domesticated” strain. As an architectural element, cellulose confers cohesion and elasticity, i.e., tissue-like properties that—together with the cell-encasing curli fiber network and geometrical constraints in a growing colony—explain the formation of long and high ridges and elaborate wrinkles of wild-type macrocolonies. In contrast, a biofilm matrix consisting of the curli fiber network only is brittle and breaks into a pattern of concentric dome-shaped rings separated by deep crevices. These studies now set the stage for clarifying how regulatory networks and in particular c-di-GMP signaling operate in the three-dimensional space of highly structured and “tissue-like” bacterial biofilms. PMID:24097954

Characterization of TEMPO-oxidized bacterial cellulose scaffolds for tissue engineering applications

International Nuclear Information System (INIS)

Luo, Honglin; Xiong, Guangyao; Hu, Da; Ren, Kaijing; Yao, Fanglian; Zhu, Yong; Gao, Chuan; Wan, Yizao

2013-01-01

Introduction of active groups on the surface of bacterial cellulose (BC) nanofibers is one of the promising routes of tailoring the performance of BC scaffolds for tissue engineering. This paper reported the introduction of aldehyde groups to BC nanofibers by 2,2,6,6-tetramethylpyperidine-1-oxy radical (TEMPO)-mediated oxidation and evaluation of the potential of the TEMPO-oxidized BC as tissue engineering scaffolds. Periodate oxidation was also conducted for comparison. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses were carried out to determine the existence of aldehyde groups on BC nanofibers and the crystallinity. In addition, properties relevant to scaffold applications such as morphology, fiber diameter, mechanical properties, and in vitro degradation were characterized. The results indicated that periodate oxidation could introduce free aldehyde to BC nanofibers and the free aldehyde groups on the TEMPO-oxidized BC tended to transfer to acetal groups. It was also found that the advantageous 3D structure of BC scaffolds remained unchanged and that no significant changes in morphology, fiber diameter, tensile structure and in vitro degradation were found after TEMPO-mediated oxidation while significant differences were observed upon periodate oxidation. The present study revealed that TEMPO-oxidation could impart BC scaffolds with new functions while did not degrade their intrinsic advantages. - Highlights: • TEMPO-mediated oxidation on BC scaffold for tissue engineering use was conducted. • TEMPO-mediated oxidation did not degrade the intrinsic advantages of BC scaffold. • TEMPO-mediated oxidation could impart BC scaffold with new functional groups. • Feasibility of TEMPO-oxidized BC as tissue engineering scaffold was confirmed

Role of Fimbriae, Flagella and Cellulose on the Attachment of Salmonella Typhimurium ATCC 14028 to Plant Cell Wall Models.

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Michelle S F Tan

Full Text Available Cases of foodborne disease caused by Salmonella are frequently associated with the consumption of minimally processed produce. Bacterial cell surface components are known to be important for the attachment of bacterial pathogens to fresh produce. The role of these extracellular structures in Salmonella attachment to plant cell walls has not been investigated in detail. We investigated the role of flagella, fimbriae and cellulose on the attachment of Salmonella Typhimurium ATCC 14028 and a range of isogenic deletion mutants (ΔfliC fljB, ΔbcsA, ΔcsgA, ΔcsgA bcsA and ΔcsgD to bacterial cellulose (BC-based plant cell wall models [BC-Pectin (BCP, BC-Xyloglucan (BCX and BC-Pectin-Xyloglucan (BCPX] after growth at different temperatures (28°C and 37°C. We found that all three cell surface components were produced at 28°C but only the flagella was produced at 37°C. Flagella appeared to be most important for attachment (reduction of up to 1.5 log CFU/cm2 although both cellulose and fimbriae also aided in attachment. The csgD deletion mutant, which lacks both cellulose and fimbriae, showed significantly higher attachment as compared to wild type cells at 37°C. This may be due to the increased expression of flagella-related genes which are also indirectly regulated by the csgD gene. Our study suggests that bacterial attachment to plant cell walls is a complex process involving many factors. Although flagella, cellulose and fimbriae all aid in attachment, these structures are not the only mechanism as no strain was completely defective in its attachment.

Bacterial cellulose of Gluconoacetobacter hansenii as a potential bioadsorption agent for its green environment applications.

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Mohite, Bhavna V; Patil, Satish V

2014-01-01

Bacterial cellulose (BC) is an interesting biopolymer produced by bacteria having superior properties. BC produced by Gluconoacetobacter hansenii (strain NCIM 2529) under shaking condition and explored for its applications in dye removal and bioadsorption of protein and heavy metals. Purity of BC was confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) analysis. BC removed azo dye and Aniline blue (400 mg/L) with 80% efficiency within 60 min. The adsorption and elution of Bovine serum albumin (BSA) and heavy metals like lead, cadmium and nickel (Pb(2+), Cd(2+) and Ni(2+)) was achieved with BC which confirms the exclusion ability with reusability. The BSA adsorption quantity was increased with increase in protein concentration with more than 90% adsorption and elution ratio. The effect of pH and temperature on BSA adsorption has been investigated. Bioadsorption (82%) and elution ratio (92%) of BC for Pb(2+) was more when compared with Cd(2+) (41 and 67%) and Ni(2+) (33 and 85%), respectively. BC was also explored as soil conditioner to increase the water-holding capacity and porosity of soil. The results elucidated the significance of BC as renewable effective ecofriendly bioadsorption agent.

Flexible, highly graphitized carbon aerogels based on bacterial cellulose/lignin: Catalyst-free synthesis and its application in energy storage devices

KAUST Repository

Xu, Xuezhu

2015-04-15

Currently, most carbon aerogels are based on carbon nanotubes (CNTs) or graphene, which are produced through a catalyst-assisted chemical vapor deposition method. Biomass based organic aerogels and carbon aerogels, featuring low cost, high scalability, and small environmental footprint, represent an important new research direction in (carbon) aerogel development. Cellulose and lignin are the two most abundant natural polymers in the world, and the aerogels based on them are very promising. Classic silicon aerogels and available organic resorcinol-formaldehyde (RF) or lignin-resorcinol-formaldehyde (LRF) aerogels are brittle and fragile; toughening of the aerogels is highly desired to expand their applications. This study reports the first attempt to toughen the intrinsically brittle LRF aerogel and carbon aerogel using bacterial cellulose. The facile process is catalyst-free and cost-effective. The toughened carbon aerogels, consisting of blackberry-like, core-shell structured, and highly graphitized carbon nanofibers, are able to undergo at least 20% reversible compressive deformation. Due to their unique nanostructure and large mesopore population, the carbon materials exhibit an areal capacitance higher than most of the reported values in the literature. This property makes them suitable candidates for flexible solid-state energy storage devices. Besides energy storage, the conductive interconnected nanoporous structure can also find applications in oil/water separation, catalyst supports, sensors, and so forth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bioactive 3D-Shaped Wound Dressings Synthesized from Bacterial Cellulose: Effect on Cell Adhesion of Polyvinyl Alcohol Integrated In Situ

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Marlon Osorio

2017-01-01

Full Text Available We investigated wound dressing composites comprising fibrils of bacterial cellulose (BC grown by fermentation in the presence of polyvinyl alcohol (PVA followed by physical crosslinking. The reference biointerface, neat BC, favoured adhesion of fibroblasts owing to size exclusion effects. Furthermore, it resisted migration across the biomaterial. Such effects were minimized in the case of PVA/BC membranes. Therefore, the latter are suggested in cases where cell adhesion is to be avoided, for instance, in the design of interactive wound dressings with facile exudate control. The bioactivity and other properties of the membranes were related to their morphology and structure and considered those of collagen fibres. Bioactive materials were produced by simple 3D templating of BC during growth and proposed for burn and skin ulcer treatment.

Formulation and Evaluation of Ascorbic acid Tablets by Direct ...

African Journals Online (AJOL)

PURPOSE: To evaluate the tableting properties of microcrystalline starch (MCS) used as a direct compression excipient in the formulation of ascorbic acid tablets and to compare with the properties of tablets produced using microcrystalline cellulose (MCC). METHODS: MCS was obtained by partial hydrolysis of cassava ( ...

How does cellulosome composition influence deconstruction of lignocellulosic substrates in Clostridium (Ruminiclostridium) thermocellum DSM 1313?

Science.gov (United States)

Yoav, Shahar; Barak, Yoav; Shamshoum, Melina; Borovok, Ilya; Lamed, Raphael; Dassa, Bareket; Hadar, Yitzhak; Morag, Ely; Bayer, Edward A

2017-01-01

Bioethanol production processes involve enzymatic hydrolysis of pretreated lignocellulosic biomass into fermentable sugars. Due to the relatively high cost of enzyme production, the development of potent and cost-effective cellulolytic cocktails is critical for increasing the cost-effectiveness of bioethanol production. In this context, the multi-protein cellulolytic complex of Clostridium ( Ruminiclostridium ) thermocellum, the cellulosome, was studied here. C. thermocellum is known to assemble cellulosomes of various subunit (enzyme) compositions, in response to the available carbon source. In the current study, different carbon sources were used, and their influence on both cellulosomal composition and the resultant activity was investigated. Glucose, cellobiose, microcrystalline cellulose, alkaline-pretreated switchgrass, alkaline-pretreated corn stover, and dilute acid-pretreated corn stover were used as sole carbon sources in the growth media of C. thermocellum strain DSM 1313. The purified cellulosomes were compared for their activity on selected cellulosic substrates. Interestingly, cellulosomes derived from cells grown on lignocellulosic biomass showed no advantage in hydrolyzing the original carbon source used for their production. Instead, microcrystalline cellulose- and glucose-derived cellulosomes were equal or superior in their capacity to deconstruct lignocellulosic biomass. Mass spectrometry analysis revealed differential composition of catalytic and structural subunits (scaffoldins) in the different cellulosome samples. The most abundant catalytic subunits in all cellulosome types include Cel48S, Cel9K, Cel9Q, Cel9R, and Cel5G. Microcrystalline cellulose- and glucose-derived cellulosome samples showed higher endoglucanase-to-exoglucanase ratios and higher catalytic subunit-per-scaffoldin ratios compared to lignocellulose-derived cellulosome types. The results reported here highlight the finding that cellulosomes derived from cells grown on glucose

Preparation and characterization of transparent PMMA-cellulose-based nanocomposites.

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Kiziltas, Esra Erbas; Kiziltas, Alper; Bollin, Shannon C; Gardner, Douglas J

2015-01-01

Nanocomposites of polymethylmethacrylate (PMMA) and cellulose were made by a solution casting method using acetone as the solvent. The nanofiber networks were prepared using three different types of cellulose nanofibers: (i) nanofibrillated cellulose (NFC), (ii) cellulose nanocrystals (CNC) and (iii) bacterial cellulose from nata de coca (NDC). The loading of cellulose nanofibrils in the PMMA varied between 0.25 and 0.5 wt%. The mechanical properties of the composites were evaluated using a dynamic mechanical thermal analyzer (DMTA). The flexural modulus of the nanocomposites reinforced with NDC at the 0.5 wt% loading level increased 23% compared to that of pure PMMA. The NFC composite also exhibited a slightly increased flexural strength around 60 MPa while PMMA had a flexural strength of 57 MPa. The addition of NDC increased the storage modulus (11%) compared to neat PMMA at room temperature while the storage modulus of PPMA/CNC nanocomposite containing 0.25 and 0.5 wt% cellulose increased about 46% and 260% to that of the pure PMMA at the glass transition temperature, respectively. Thermogravimetric analysis (TGA) indicated that there was no significant change in thermal stability of the composites. The UV-vis transmittance of the CNF nanocomposites decreased by 9% and 27% with the addition of 0.25 wt% CNC and NDC, respectively. This work is intended to spur research and development activity for application of CNF reinforced PMMA nanocomposites in applications such as: packaging, flexible screens, optically transparent films and light-weight transparent materials for ballistic protection. Copyright © 2015 Elsevier Ltd. All rights reserved.

Two-component self-assembly with solvent leading to "wet" and microcrystalline organogel fibers.

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Löfman, Miika; Lahtinen, Manu; Rissanen, Kari; Sievänen, Elina

2015-01-15

The microcrystalline fibers of N-(2-aminoethyl)-3α-hydroxy-5β-cholan-24-amide 1 provided a useful model system for studying the complex relationship between morphology, experimental parameters, solvent, and the phenomenon of organogelation. The presence of solvents in the solid forms of 1 along with crystallization behavior suggested solvate formation and polymorphic behavior. Forty solid state- and xerogel samples of 1 formed in organic solvents and in three categories of experimental conditions were analyzed with single crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), Raman microscopy, and attenuated total reflection Fourier-transform infrared spectroscopy (ATR FTIR). Two polymorphs and four isostructural aromatic solvates of 1 were found among some unknown forms in the samples. Single crystal X-ray structures of one polymorph and bromobenzene solvate were obtained, the latter from a xerogel. Multiple crystal forms could be present in a sample, and their contributions to gelation were estimated taking the experimental conditions into account. Gelator 1 could act as a variable component gelator, either alone or in combination with an aromatic solvent. The research brings new insight into the structures of microcrystalline organogel fibers, linking solvate/inclusion crystal formation with microcrystalline fibers of an organogelator for the first time. Copyright © 2014 Elsevier Inc. All rights reserved.

Properties of amorphous and microcrystalline superconductors

International Nuclear Information System (INIS)

Johnson, W.L.; Poon, S.J.

1975-01-01

Results of x-ray diffraction, electrical resistivity, critical field(H/sub c2/) and transport measurements are presented and discussed for bulk amorphous and microcrystalline transition metal alloys (Au--La, Nb--Rh, Nb--Ni--Rh, and Pd--Zr) obtained by liquid quenching. The transition temperature of the alloys is in the range 1.5 to 4.7 0 K. The J/sub c/--H/sub c2/--T/sub c/ relations are rather simple for this class of material and are compared with the theories of type II superconductors. The high resistance of bulk metallic glass to radiation damage might render them suitable for magnetic field applications in high radiation environments

Microcrystalline silicon, grain boundaries and role of oxygen

Czech Academy of Sciences Publication Activity Database

Kočka, Jan; Stuchlíková, The-Ha; Ledinský, Martin; Stuchlík, Jiří; Mates, Tomáš; Fejfar, Antonín

2009-01-01

Roč. 93, č. 8 (2009), s. 1444-1447 ISSN 0927-0248 R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR KAN400100701; GA ČR(CZ) GD202/05/H003; GA MŠk LC510; GA AV ČR IAA1010413 Institutional research plan: CEZ:AV0Z10100521 Keywords : microcrystalline silicon * grain boundaries * electronic transport * hydrogen * oxygen Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.858, year: 2009

Patterning of hydrogenated microcrystalline silicon growth by magnetic field

Czech Academy of Sciences Publication Activity Database

Fejfar, Antonín; Stuchlík, Jiří; Mates, Tomáš; Ledinský, Martin; Honda, Shinya; Kočka, Jan

2005-01-01

Roč. 87, č. 1 (2005), 011901/1-011901/3 ISSN 0003-6951 R&D Projects: GA AV ČR(CZ) IAA1010316; GA AV ČR(CZ) IAA1010413; GA ČR(CZ) GD202/05/H003 Institutional research plan: CEZ:AV0Z10100521 Keywords : hydrogenated microcrystalline silicon * magnetic field growth Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.127, year: 2005

Cellulose nanocrystals as templates for cetyltrimethylammonium bromide mediated synthesis of Ag nanoparticles and their novel use in PLA films.

Science.gov (United States)

Yalcinkaya, E E; Puglia, D; Fortunati, E; Bertoglio, F; Bruni, G; Visai, L; Kenny, J M

2017-02-10

In the present paper, we reported how cellulose nanocrystals (CNC) from microcrystalline cellulose have the capacity to assist in the synthesis of metallic nanoparticles chains. A cationic surfactant, cetyltrimethylammonium bromide (CTAB), was used as modifier for CNC surface. Silver nanoparticles were synthesized on CNC, and nanoparticle density and size were optimized by varying concentrations of nitrate and reducing agents, and the reduction time. The experimental conditions were optimized for the synthesis and the resulting Ag grafted CNC (Ag-g-CNC) were characterized by means of TGA, SEM, FTIR and XRD, and then introduced in PLA matrix. PLA nanocomposite containing silver grafted cellulose nanocrystals (PLA/0.5Ag-g-1CNC) was characterized by optical and thermal analyses and the obtained data were compared with results from PLA nanocomposites containing 1% wt. of CNC (PLA/1CNC), 0.5% wt. of silver nanoparticles (PLA/0.5Ag) and hybrid system containing CNC and silver in the same amount (PLA/1CNC/0.5Ag). The results demonstrated that grafting of silver nanoparticles on CNC positively affected the thermal degradation process and cold crystallization processes of PLA matrix. Finally, the antibacterial activity of the different systems was studied at various incubation times and temperatures, showing the best performance for PLA/1CNC/0.5Ag based nanocomposite. Copyright © 2016 Elsevier Ltd. All rights reserved.

Eco-friendly biorefractory films of gelatin and TEMPO-oxidized cellulose ester for food packaging application.

Science.gov (United States)

Zhuang, Chen; Tao, Furong; Cui, Yuezhi

2017-08-01

In recent years, many types of food-packaging films and composites have been prepared using gelatin because of its good film-forming ability, non-toxic nature and cost-effectiveness. However, the relatively weak thermal stability, poor mechanical properties and easily-degradable quality limit the potential application of gelatin as a practical material. Microcrystalline cellulose (MCC), which comprises one of the most abundant biomass resources, has been regarded as a safe and reliable food additive because it has the same ingredients as the cellulose in people's daily intake. Food-packaging films with the excellent properties provided by gelatin and oxidized-cellulose represent a topic of great interest. MCC was modified by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation and chosen as the base of the macromolecule cross-linker (TMN). After modification of gelatin film by TMN, the minimum amount of free -NH 2 in solution was 4.8 × 10 -4  mol g -1 ). The thermal property obviously increased (from 322.31  o C to 352.63  o C) and was crucial for usage in the food industry. The highest water contact value 123.09° (η = 25%) indicated a better surface hydrophobicity. The higher E ab (58.88%) and lower E m (77.16%) demonstrated that a more flexible and shatter-proof material was obtained. Water vapor uptake studies suggested increased moisture absorption and greater swelling ability. The film material obtained in the present study was safe, stable, eco-friendly and biorefractory and could also be decomposed completely by the environment after disposal as a result of the properties of the ingredients gelatin and cellulose. The incorporation of a cellulosic cross-linker to gelatin-based films was an ideal choice with respect to developing a packaging for the food industry. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Fungal-type carbohydrate binding modules from the coccolithophore Emiliania huxleyi show binding affinity to cellulose and chitin.

Science.gov (United States)

Rooijakkers, Bart J M; Ikonen, Martina S; Linder, Markus B

2018-01-01

Six fungal-type cellulose binding domains were found in the genome of the coccolithophore Emiliania huxleyi and cloned and expressed in Escherichia coli. Sequence comparison indicate high similarity to fungal cellulose binding domains, raising the question of why these domains exist in coccolithophores. The proteins were tested for binding with cellulose and chitin as ligands, which resulted in the identification of two functional carbohydrate binding modules: EHUX2 and EHUX4. Compared to benchmark fungal cellulose binding domain Cel7A-CBM1 from Trichoderma reesei, these proteins showed slightly lower binding to birch and bacterial cellulose, but were more efficient chitin binders. Finally, a set of cellulose binding domains was created based on the shuffling of one well-functioning and one non-functional domain. These were characterized in order to get more information of the binding domain's sequence-function relationship, indicating characteristic differences between the molecular basis of cellulose versus chitin recognition. As previous reports have showed the presence of cellulose in coccoliths and here we find functional cellulose binding modules, a possible connection is discussed.

Fungal-type carbohydrate binding modules from the coccolithophore Emiliania huxleyi show binding affinity to cellulose and chitin.

Directory of Open Access Journals (Sweden)

Bart J M Rooijakkers

Full Text Available Six fungal-type cellulose binding domains were found in the genome of the coccolithophore Emiliania huxleyi and cloned and expressed in Escherichia coli. Sequence comparison indicate high similarity to fungal cellulose binding domains, raising the question of why these domains exist in coccolithophores. The proteins were tested for binding with cellulose and chitin as ligands, which resulted in the identification of two functional carbohydrate binding modules: EHUX2 and EHUX4. Compared to benchmark fungal cellulose binding domain Cel7A-CBM1 from Trichoderma reesei, these proteins showed slightly lower binding to birch and bacterial cellulose, but were more efficient chitin binders. Finally, a set of cellulose binding domains was created based on the shuffling of one well-functioning and one non-functional domain. These were characterized in order to get more information of the binding domain's sequence-function relationship, indicating characteristic differences between the molecular basis of cellulose versus chitin recognition. As previous reports have showed the presence of cellulose in coccoliths and here we find functional cellulose binding modules, a possible connection is discussed.

Physical properties of P and B doped microcrystalline SI:H deposited by PECVD

International Nuclear Information System (INIS)

Rubino, A.; Addonizio, M.L.; Conte, G.; Nobile, G.; Terzini, E.

1993-01-01

Boron and phosphorus doped high conductivity microcrystalline thin films were deposited in a PECVD reactor. This paper reports conductivities as high as 3 and 41 S/cm for B and P doped materials respectively on films deposited at 210 degrees C. The conductivity, as well as, the microcrystalline fraction increase for the n layer with decreasing RF power, while, for the p material, an increase of power is needed to improve the film characteristics. The conductivity prefactor, as well as, the conductivity itself as a function of the activation energy show a slope inversion for both n and p materials at an activation energy of about 40 meV and 80 meV respectively. Different possible transport mechanisms are examined in order to explain the experimental data

A novel method of producing a microcrystalline beta-sitosterol suspension in oil

DEFF Research Database (Denmark)

Christiansen, Leena I; Rantanen, Jukka T; von Bonsdorff, Anna K

2002-01-01

This paper describes a novel method of producing a microcrystalline oral suspension containing beta-sitosterol in oil for the treatment of hypercholesterolaemia. beta-Sitosterol pseudopolymorphs with different water contents were crystallized from acetone and acetone-water solutions. Structural...

Bacterial-cellulose-derived interconnected meso-microporous carbon nanofiber networks as binder-free electrodes for high-performance supercapacitors

Science.gov (United States)

Hao, Xiaodong; Wang, Jie; Ding, Bing; Wang, Ya; Chang, Zhi; Dou, Hui; Zhang, Xiaogang

2017-06-01

Bacterial cellulose (BC), a typical biomass prepared from the microbial fermentation process, has been proved that it can be an ideal platform for design of three-dimensional (3D) multifunctional nanomaterials in energy storage and conversion field. Here we developed a simple and general silica-assisted strategy for fabrication of interconnected 3D meso-microporous carbon nanofiber networks by confine nanospace pyrolysis of sustainable BC, which can be used as binder-free electrodes for high-performance supercapacitors. The synthesized carbon nanofibers exhibited the features of interconnected 3D networks architecture, large surface area (624 m2 g-1), mesopores-dominated hierarchical porosity, and high graphitization degree. The as-prepared electrode (CN-BC) displayed a maximum specific capacitance of 302 F g-1 at a current density of 0.5 A g-1, high-rate capability and good cyclicity in 6 M KOH electrolyte. This work, together with cost-effective preparation strategy to make high-value utilization of cheap biomass, should have significant implications in the green and mass-producible energy storage.

Silver nanoparticle/bacterial cellulose gel membranes for antibacterial wound dressing: investigation in vitro and in vivo

International Nuclear Information System (INIS)

Wu, Jian; Zheng, Yudong; Wen, Xiaoxiao; Lin, Qinghua; Chen, Xiaohua; Wu, Zhigu

2014-01-01

Bacterial cellulose (BC) has attracted increasing attention as a novel wound dressing material, but its antimicrobial activity, which is one of the critical skin-barrier functions in wound healing, is not sufficient for use in practical applications. To overcome such a deficiency, silver nanoparticles were generated and self-assembled on the surface of BC nanofibers, forming a stable and evenly distributed Ag nanoparticle coated BC nanofiber (AgNP-BC). The performance of AgNP-BC was systematically studied in terms of antibacterial activities, cytocompatibility and effects on wound healing. The results showed that AgNP-BC exhibited significant antibacterial activity against Staphylococcus aureus. Moreover, AgNP-BC allowed attachment, and growth of rat fibroblasts with low cytotoxicity emerged. Based on these advantages, AgNP-BC samples were applied in a second-degree rat wound model. Wound flora showed a significant reduction during the healing. The fresh epidermal and dermis thicknesses with AgNP-BC samples were 111 and 855 µm respectively, higher than 74 and 619 µm for BC groups and 57 and 473 µm for untreated control wounds. The results demonstrated that AgNP-BC could reduce inflammation and promote scald wound healing. (paper)

Electrospinning cellulose based nanofibers for sensor applications

Science.gov (United States)

Nartker, Steven

2009-12-01

Bacterial pathogens have recently become a serious threat to the food and water supply. A biosensor based on an electrochemical immunoassay has been developed for detecting food borne pathogens, such as Escherichia coli (E. coli) O157:H7. These sensors consist of several materials including, cellulose, cellulose nitrate, polyaniline and glass fibers. The current sensors have not been optimized in terms of microscale architecture and materials. The major problem associated with the current sensors is the limited concentration range of pathogens that provides a linear response on the concentration conductivity chart. Electrospinning is a process that can be used to create a patterned fiber mat design that will increase the linear range and lower the detection limit of these sensors by improving the microscale architecture. Using the electrospinning process to produce novel mats of cellulose nitrate will offer improved surface area, and the cellulose nitrate can be treated to further improve chemical interactions required for sensor activity. The macro and micro architecture of the sensor is critical to the performance of the sensors. Electrospinning technology can be used to create patterned architectures of nanofibers that will enhance sensor performance. To date electrospinning of cellulose nitrate has not been performed and optimization of the electrospinning process will provide novel materials suitable for applications such as filtration and sensing. The goal of this research is to identify and elucidate the primary materials and process factors necessary to produce cellulose nitrate nanofibers using the electrospinning process that will improve the performance of biosensors. Cellulose nitrate is readily dissolved in common organic solvents such as acetone, tetrahydrofuran (THF) and N,N dimethylformamide (DMF). These solvents can be mixed with other latent solvents such as ethanol and other alcohols to provide a solvent system with good electrospinning behavior

Charge transport properties in microcrystalline KDyFe(China)6

International Nuclear Information System (INIS)

Aubert, P.H.; Goubard, F.; Chevrot, C.; Tabuteau, A.

2007-01-01

Microcrystalline solid dysprosium(III) hexacyanoferrate(II) was synthesized by co-precipitation in aqueous solution. The resulting solid has been studied by Fourier transform infrared spectroscopy, X-ray analysis and solid state electrochemistry. The use of a cavity microelectrode was necessary to explore a wide range of time scale and minimize the (undesired) capacitive currents. Cyclic voltametric experiments were very helpful to understand the kinetic of charge transfer in such microstructure. A structure-properties relationship has been established from the crystallographic and the electrochemical properties. A square-scheme is presented to explain the unique electrochemical behavior of hexacyanoferrate containing dysprosium since this compound exhibits a second redox system. The solid presents an open channel-like morphology in which the motion of charged species occurs during the redox processes. Precisely, the electronic transfer is accompanied by a cation diffusion inside the microcrystalline structure. The size of these channels strongly suggests that the kinetic of charge transfer is limited by the cation transport into these structures. - Graphical abstract: Dy and Fe polyhedra packing in the cell of KDyFe(China) 6 .3.5H 2 O shows occluded water molecules and potassium ions forming a pseudohexagonal 2D sub-lattice connected to each other by diffusion channels

Ultrasound-assisted acid hydrolysis of cellulose to chemical building blocks: Application to furfural synthesis.

Science.gov (United States)

Santos, Daniel; Silva, Ubiratan F; Duarte, Fabio A; Bizzi, Cezar A; Flores, Erico M M; Mello, Paola A

2018-01-01

In this work, the use of ultrasound energy for the production of furanic platforms from cellulose was investigated and the synthesis of furfural was demonstrated. Several systems were evaluated, as ultrasound bath, cup horn and probe, in order to investigate microcrystalline cellulose conversion using simply a diluted acid solution and ultrasound. Several acid mixtures were evaluated for hydrolysis, as diluted solutions of HNO 3 , H 2 SO 4 , HCl and H 2 C 2 O 4 . The influence of the following parameters in the ultrasound-assisted acid hydrolysis (UAAH) were studied: sonication temperature (30 to 70°C) and ultrasound amplitude (30 to 70% for a cup horn system) for 4 to 8molL -1 HNO 3 solutions. For each evaluated condition, the products were identified by ultra-performance liquid chromatography with high-resolution time-of-flight mass spectrometry (UPLC-ToF-MS), which provide accurate information regarding the products obtained from biomass conversion. The furfural structure was confirmed by nuclear magnetic resonance ( 1 H and 13 C NMR) spectroscopy. In addition, cellulosic residues from hydrolysis reaction were characterized using scanning electron microscopy (SEM), which contributed for a better understanding of physical-chemical effects caused by ultrasound. After process optimization, a 4molL -1 HNO 3 solution, sonicated for 60min at 30°C in a cup horn system at 50% of amplitude, lead to 78% of conversion to furfural. This mild temperature condition combined to the use of a diluted acid solution represents an important contribution for the selective production of chemical building blocks using ultrasound energy. Copyright © 2017 Elsevier B.V. All rights reserved.

Fabrication and characterization of novel biomimetic PLLA/cellulose/hydroxyapatite nanocomposite for bone repair applications

Energy Technology Data Exchange (ETDEWEB)

Eftekhari, Samin [Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 (Canada); El Sawi, Ihab; Bagheri, Zahra Shaghayegh [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 (Canada); Turcotte, Ginette [Department of Chemical Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 (Canada); Bougherara, Habiba, E-mail: habiba.bougherara@ryerson.ca [Department of Mechanical and Industrial Engineering, Ryerson University, 350 Victoria Street, Toronto, ON M5B 2K3 (Canada)

2014-06-01

The purpose of this research is to develop and characterize a novel biomimetic nanocomposite that closely mimics the properties of real bone such as morphology, composition and mechanical characteristics. This novel porous nanocomposite is composed of cotton-sourced cellulose microcrystals, hydroxyapatite nanoparticles and poly L-lactide acid. A unique combination of commonly used fabrication procedures has been developed including pre-treatment of particles using a coupling agent. The effect of various weight ratios of the reinforcing agents was evaluated to assess their influence on the chemical, thermal, and mechanical properties of the nanocomposites. The prepared nanocomposites were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, differential scanning calorimetry and compression testing. Our results indicated the presence of molecular interactions between all components leading to an increase of the crystallinity of the polymer from 50% to 80%. Compression test results revealed that increasing the weight ratio of microcrystalline cellulose/poly L-lactide acid and hydroxyapatite/poly L-lactide acid from 0.1 to 0.5 enhanced the compressive yield stress from 0.127 to 2.2 MPa and The Young's modulus from 6.6 to 38 MPa, respectively. It was found that the fabricated nanocomposites are comparable with the trabecular bone from compositional, structural, and mechanical point of view. - Highlights: • Fabrication of PLLA/HA/cellulose composites that mimic the spongeous bone • Homogenous dispersion of the reinforcing agents in the PLLA matrix was attained. • More efficient interface between the PLLA and the reinforcing agents was achieved. • Preliminary in vitro biocompatibility test showed the nontoxicity of the composite. • The crystallinity, the compressive strength and modulus were investigated.

Cellulose synthase complex organization and cellulose microfibril structure.

Science.gov (United States)

Turner, Simon; Kumar, Manoj

2018-02-13

Cellulose consists of linear chains of β-1,4-linked glucose units, which are synthesized by the cellulose synthase complex (CSC). In plants, these chains associate in an ordered manner to form the cellulose microfibrils. Both the CSC and the local environment in which the individual chains coalesce to form the cellulose microfibril determine the structure and the unique physical properties of the microfibril. There are several recent reviews that cover many aspects of cellulose biosynthesis, which include trafficking of the complex to the plasma membrane and the relationship between the movement of the CSC and the underlying cortical microtubules (Bringmann et al. 2012 Trends Plant Sci. 17 , 666-674 (doi:10.1016/j.tplants.2012.06.003); Kumar & Turner 2015 Phytochemistry 112 , 91-99 (doi:10.1016/j.phytochem.2014.07.009); Schneider et al. 2016 Curr. Opin. Plant Biol. 34 , 9-16 (doi:10.1016/j.pbi.2016.07.007)). In this review, we will focus on recent advances in cellulose biosynthesis in plants, with an emphasis on our current understanding of the structure of individual catalytic subunits together with the local membrane environment where cellulose synthesis occurs. We will attempt to relate this information to our current knowledge of the structure of the cellulose microfibril and propose a model in which variations in the structure of the CSC have important implications for the structure of the cellulose microfibril produced.This article is part of a discussion meeting issue 'New horizons for cellulose nanotechnology'. © 2017 The Author(s).

Bioconversion of cellulose into electrical energy in microbial fuel cells

Science.gov (United States)

Rismani-Yazdi, Hamid

In microbial fuel cells (MFCs), bacteria generate electricity by mediating the oxidation of organic compounds and transferring the resulting electrons to an anode electrode. The first objective of this study was to test the possibility of generating electricity with rumen microorganisms as biocatalysts and cellulose as the electron donor in two-compartment MFCs. Maximum power density reached 55 mW/m2 (1.5 mA, 313 mV) with cellulose as the electron donor. Cellulose hydrolysis and electrode reduction were shown to support the production of current. The electrical current was sustained for over two months with periodic cellulose addition. Clarified rumen fluid and a soluble carbohydrate mixture, serving as the electron donors, could also sustain power output. The second objective was to analyze the composition of the bacterial communities enriched in the cellulose-fed MFCs. Denaturing gradient gel electrophoresis of PCR amplified 16S rRNA genes revealed that the microbial communities differed when different substrates were used in the MFCs. The anode-attached and the suspended consortia were shown to be different within the same MFC. Cloning and analysis of 16S rRNA gene sequences indicated that the most predominant bacteria in the anode-attached consortia were related to Clostridium spp., while Comamonas spp. was abundant in the suspended consortia. The external resistance affects the characteristic outputs of MFCs by controlling the flow of electrons from the anode to the cathode. The third objective of this study was to determine the effect of various external resistances on power output and coulombic efficiency of cellulose-fed MFCs. Four external resistances (20, 249, 480, and 1000 ohms) were tested with a systematic approach of operating parallel MFCs independently at constant circuit loads for three months. A maximum power density of 66 mWm-2 was achieved by MFCs with 20 ohms circuit load, while MFCs with 249, 480 and1000 ohms external resistances produced 57

Isolation and identification of biocellulose-producing bacterial strains from Malaysian acidic fruits.

Science.gov (United States)

Voon, W W Y; Rukayadi, Y; Meor Hussin, A S

2016-05-01

Biocellulose (BC) is pure extracellular cellulose produced by several species of micro-organisms that has numerous applications in the food, biomedical and paper industries. However, the existing biocellulose-producing bacterial strain with high yield was limited. The aim of this study was to isolate and identify the potential biocellulose-producing bacterial isolates from Malaysian acidic fruits. One hundred and ninety-three bacterial isolates were obtained from 19 local acidic fruits collected in Malaysia and screened for their ability to produce BC. A total of 15 potential bacterial isolates were then cultured in standard Hestrin-Schramm (HS) medium statically at 30°C for 2 weeks to determine the BC production. The most potent bacterial isolates were identified using 16S rRNA gene sequence analysis, morphological and biochemical characteristics. Three new and potent biocellulose-producing bacterial strains were isolated from soursop fruit and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. Stenotrophomonas maltophilia WAUPM42 was the most potent biocellulose-producing bacterial strain that produced the highest amount of BC 0·58 g l(-1) in standard HS medium. Whereas, the isolates P. vagans WAUPM45 and B. fluminensis WAUPM53 showed 0·50 and 0·52 g l(-1) of BC production, respectively. Biocellulose (BC) is pure extracellular cellulose that is formed by many micro-organisms in the presence of carbon source and acidic condition. It can replace plant-based cellulose in multifarious applications due to its unique characteristics. In this study, three potential biocellulose-producing bacterial strains were obtained from Malaysian acidic fruits and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. This study reports for the first time the new biocellulose-producing bacterial strains isolated from Malaysian acidic fruits. © 2016 The

Carrier dynamics in microcrystalline silicon studied by time-resolved terahertz spectroscopy

Czech Academy of Sciences Publication Activity Database

Fekete, Ladislav; Němec, Hynek; Kadlec, Filip; Kužel, Petr; Stuchlík, Jiří; Fejfar, Antonín; Kočka, Jan

2006-01-01

Roč. 352, - (2006), s. 2846-2849 ISSN 0022-3093 R&D Projects: GA AV ČR(CZ) KJB100100512 Institutional research plan: CEZ:AV0Z10100520 Keywords : silicon * solar cells * dielectric properties * relaxation * electric modulus * chemical vapor deposition * microcrystallinity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.362, year: 2006

Microcrystalline silicon prepared at magnetic field modified nucleation

Czech Academy of Sciences Publication Activity Database

Kočka, Jan; Mates, Tomáš; Ledinský, Martin; Stuchlíková, The-Ha; Stuchlík, Jiří; Fejfar, Antonín

2006-01-01

Roč. 352, - (2006), s. 901-905 ISSN 0022-3093 R&D Projects: GA MŽP(CZ) SM/300/1/03; GA MŽP(CZ) SN/3/172/05; GA AV ČR(CZ) IAA1010316; GA AV ČR(CZ) IAA1010413; GA MŠk(CZ) LC510 Institutional research plan: CEZ:AV0Z10100521 Keywords : amorphous semiconductors * nucleation * electrical and electronic properties * chemical vapor deposition * atomic force and scanning tunneling microscopy * microcrystallinity * optical properties Subject RIV: BM - Solid Matter Physics ; Magnet ism Impact factor: 1.362, year: 2006

Enhancement of crystallinity of cellulose produced by Escherichia coli through heterologous expression of bcsD gene from Gluconacetobacter xylinus.

Science.gov (United States)

Sajadi, Elaheh; Babaipour, Valiollah; Deldar, Ali Asghar; Yakhchali, Bagher; Fatemi, Seyed Safa-Ali

2017-09-01

To evaluate the crystallinity index of the cellulose produced by Escherichia coli Nissle 1917 after heterologous expression of the cellulose synthase subunit D (bcsD) gene of Gluconacetobacter xylinus BPR2001. The bcsD gene of G. xylinus BPR2001 was expressed in E. coli and its protein product was visualized using SDS-PAGE. FTIR analysis showed that the crystallinity index of the cellulose produced by the recombinants was 0.84, which is 17% more than that of the wild type strain. The increased crystallinity index was also confirmed by X-ray diffraction analysis. The cellulose content was not changed significantly after over-expressing the bcsD. The bcsD gene can improve the crystalline structure of the bacterial cellulose but there is not any significant difference between the amounts of cellulose produced by the recombinant and wild type E. coli Nissle 1917.

Microcrystalline thin-film solar cell deposition on moving substrates using a linear VHF-PECVD reactor and a cross-flow geometry

International Nuclear Information System (INIS)

Flikweert, A J; Zimmermann, T; Merdzhanova, T; Weigand, D; Appenzeller, W; Gordijn, A

2012-01-01

A concept for high-rate plasma deposition (PECVD) of hydrogenated microcrystalline silicon on moving substrates (dynamic deposition) is developed and evaluated. The chamber allows for substrates up to a size of 40 × 40 cm 2 . The deposition plasma is sustained between linear VHF electrodes (60 MHz) and a moving substrate. Due to the gas flow geometry and the high degree of source gas depletion, from the carrier's point of view the silane concentration varies when passing the electrodes. This is known to lead to different growth conditions which can induce transitions from microcrystalline to amorphous growth. The effect of different silane concentrations is simulated at a standard RF showerhead electrode by intentionally varying the silane concentration during deposition in static mode. This variation may decrease the layer quality of microcrystalline silicon, due to a shift of the crystallinity away from the optimum. However, adapting the input silane concentration, state-of-the-art solar cells are obtained. Microcrystalline cells (ZnO : Al/Ag back contacts) produced by the linear VHF plasma sources show an efficiency of 7.9% and 6.6% for depositions in static and dynamic mode, respectively. (paper)

Cellulose is not just cellulose

DEFF Research Database (Denmark)

Hidayat, Budi Juliman; Felby, Claus; Johansen, Katja Salomon

2012-01-01

are not regions where free cellulose ends are more abundant than in the bulk cell wall. In more severe cases cracks between fibrils form at dislocations and it is possible that the increased accessibility that these cracks give is the reason why hydrolysis of cellulose starts at these locations. If acid...... or enzymatic hydrolysis of plant cell walls is carried out simultaneously with the application of shear stress, plant cells such as fibers or tracheids break at their dislocations. At present it is not known whether specific carbohydrate binding modules (CBMs) and/or cellulases preferentially access cellulose...

HPMC supplementation reduces abdominal fat content, intestinal permeability, inflammation, and insulin resistance in diet-induced obese mice

Science.gov (United States)

Cationic hydroxyethyl cellulose (cHEC) , was fed to hamsters to determine if this new soluble fiber had an effect on hypercholesterolemia and dyslipidemia associated with cardiovascular disease. In this study, Golden Syrian hamsters were supplemented with 3-8% cHEC or microcrystalline cellulose (MC...

Development of Chitosan/Bacterial Cellulose Composite Films Containing Nanodiamonds as a Potential Flexible Platform for Wound Dressing

Directory of Open Access Journals (Sweden)

Fatemeh Ostadhossein

2015-09-01

Full Text Available Chitosan/bacterial cellulose composite films containing diamond nanoparticles (NDs with potential application as wound dressing are introduced. Microstructural studies show that NDs are uniformly dispersed in the matrix, although slight agglomeration at concentrations above 2 wt % is seen. Fourier transform infrared spectroscopy reveals formation of hydrogen bonds between NDs and the polymer matrix. X-ray diffraction analysis indicates reduced crystallinity of the polymer matrix in the presence of NDs. Approximately 3.5-fold increase in the elastic modulus of the composite film is obtained by the addition of 2 wt % NDs. The results of colorimetric analysis show that the composite films are transparent but turn to gray-like and semitransparent at high ND concentrations. Additionally, a decrease in highest occupied molecular orbital (HOMO and lowest unoccupied molecular orbital (LUMO gap is also seen, which results in a red shift and higher absorption intensity towards the visible region. Mitochondrial activity assay using L929 fibroblast cells shows that the nanocomposite films are biocompatible (>90% after 24 h incubation. Multiple lamellapodia and cell-cell interaction are shown. The results suggest that the developed films can potentially be used as a flexible platform for wound dressing.

Surface studies of microcrystalline chitosan/poly(vinyl alcohol) mixtures

Energy Technology Data Exchange (ETDEWEB)

Lewandowska, Katarzyna, E-mail: reol@chem.uni.torun.pl [Nicolaus Copernicus University, Faculty of Chemistry, Chair of Chemistry and Photochemistry of Polymers, 7 Gagarin Street, 87-100 Torun (Poland)

2012-12-15

Highlights: Black-Right-Pointing-Pointer The surface properties were investigated by AFM, SEM and FTIR. Black-Right-Pointing-Pointer The AFM images showed the lamellar structure of PVA in the blend. Black-Right-Pointing-Pointer SEM microscopy confirmed the existence of microphase separation of components. Black-Right-Pointing-Pointer FTIR analysis showed the existence of a weak interaction. - Abstract: In the present study, the surface properties of microcrystalline chitosan (MCCh), poly(vinyl alcohol) (PVA) and MCCh/PVA blends (made from acetic acid solutions with the MCCh concentration ranging from 20% to 80%) have been studied by the tapping-mode atomic force microscopy (AFM), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The changes of topography images are considered by determining the root mean square (RMS, R{sub q}) deviation in the image data. For PVA samples, the transition between adjacent lamellae occurs through holes, islands, and bicontinuous structures. The AFM images showed also the lamellar structure of PVA in the blend. The crystalline topography of MCCh/PVA film surface suggests the presence of PVA on the top surface. The FTIR spectra of film blends, in the amide I and II region of MCCh and the hydroxyl stretching bands of PVA have been analyzed. FTIR analysis showed the existence of a weak interaction of the hydroxyl or amino groups of microcrystalline chitosan with hydroxyl groups of PVA.

Surface studies of microcrystalline chitosan/poly(vinyl alcohol) mixtures

International Nuclear Information System (INIS)

Lewandowska, Katarzyna

2012-01-01

Highlights: ► The surface properties were investigated by AFM, SEM and FTIR. ► The AFM images showed the lamellar structure of PVA in the blend. ► SEM microscopy confirmed the existence of microphase separation of components. ► FTIR analysis showed the existence of a weak interaction. - Abstract: In the present study, the surface properties of microcrystalline chitosan (MCCh), poly(vinyl alcohol) (PVA) and MCCh/PVA blends (made from acetic acid solutions with the MCCh concentration ranging from 20% to 80%) have been studied by the tapping-mode atomic force microscopy (AFM), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The changes of topography images are considered by determining the root mean square (RMS, R q ) deviation in the image data. For PVA samples, the transition between adjacent lamellae occurs through holes, islands, and bicontinuous structures. The AFM images showed also the lamellar structure of PVA in the blend. The crystalline topography of MCCh/PVA film surface suggests the presence of PVA on the top surface. The FTIR spectra of film blends, in the amide I and II region of MCCh and the hydroxyl stretching bands of PVA have been analyzed. FTIR analysis showed the existence of a weak interaction of the hydroxyl or amino groups of microcrystalline chitosan with hydroxyl groups of PVA.

Simulation of the growth dynamics of amorphous and microcrystalline silicon

OpenAIRE

Bailat, Julien; Vallat-Sauvain, Evelyne; Vallat, A.; Shah, Arvind

2008-01-01

The qualitative description of the major microstructure characteristics of microcrystalline silicon is achieved through a three-dimensional discrete dynamical growth model. The model is based on three fundamental processes that determine surface morphology: (1) random deposition of particles, (2) local relaxation and (3) desorption. In this model, the incoming particle reaching the growing surface takes on a state variable representing a particular way of being incorporated into the material....

Conventional and 360 degree electron tomography of a micro-crystalline silicon solar cell

DEFF Research Database (Denmark)

Duchamp, Martial; Ramar, Amuthan; Kovács, András

2011-01-01

Bright-field (BF) and annular dark-field (ADF) electron tomography in the transmission electron microscope (TEM) are used to characterize elongated porous regions or cracks (simply referred to as cracks thereafter) in micro-crystalline silicon (μc-Si:H) solar cell. The limitations of inferring...

The Effect of Cellulose Crystal Structure and Solid-State Morphology on the Activity of Cellulases

Energy Technology Data Exchange (ETDEWEB)

Stipanovic, Arthur J [SUNY College of Environmental Science and Forestry

2014-11-17

Consistent with the US-DOE and USDA “Roadmap” objective of producing ethanol and chemicals from cellulosic feedstocks more efficiently, a three year research project entitled “The Effect of Cellulose Crystal Structure and Solid-State Morphology on the Activity of Cellulases” was initiated in early 2003 under DOE sponsorship (Project Number DE-FG02-02ER15356). A three year continuation was awarded in June 2005 for the period September 15, 2005 through September 14, 2008. The original goal of this project was to determine the effect of cellulose crystal structure, including allomorphic crystalline form (Cellulose I, II, III, IV and sub-allomorphs), relative degree of crystallinity and crystallite size, on the activity of different types of genetically engineered cellulase enzymes to provide insight into the mechanism and kinetics of cellulose digestion by “pure” enzymes rather than complex mixtures. We expected that such information would ultimately help enhance the accessibility of cellulose to enzymatic conversion processes thereby creating a more cost-effective commercial process yielding sugars for fermentation into ethanol and other chemical products. Perhaps the most significant finding of the initial project phase was that conversion of native bacterial cellulose (Cellulose I; BC-I) to the Cellulose II (BC-II) crystal form by aqueous NaOH “pretreatment” provided an increase in cellulase conversion rate approaching 2-4 fold depending on enzyme concentration and temperature, even when initial % crystallinity values were similar for both allomorphs.

Properties of cellulose derivatives produced from radiation-Modified cellulose pulps

International Nuclear Information System (INIS)

Iller, Edward; Stupinska, Halina; Starostka, Pawel

2007-01-01

The aim of project was elaboration of radiation methods for properties modification of cellulose pulps using for derivatives production. The selected cellulose pulps were exposed to an electron beam with energy 10 MeV in a linear accelerator. After irradiation pulps underwent the structural and physico-chemical investigations. The laboratory test for manufacturing carboxymethylocellulose (CMC), cellulose carbamate (CC) and cellulose acetate (CA) with cellulose pulps irradiated dose 10 and 15 kGy have been performed. Irradiation of the pulp influenced its depolimerisation degree and resulted in the drop of viscosity of CMC. However, the expected level of cellulose activation expressed as a rise of the substitution degree or increase of the active substance content in the CMC sodium salt was not observed. In the case of cellulose esters (CC, CA) formation, the action of ionising radiation on cellulose pulps with the dose 10 and 15 kGy enables obtaiment of the average values of polimerisation degree as required for CC soluble in aqueous sodium hydroxide solution. The properties of derivatives prepared by means of radiation and classic methods were compared

Evaluation of the binding effect of human serum albumin on the properties of granules.

Science.gov (United States)

Kristó, Katalin; Bajdik, János; Eros, István; Pintye-Hódi, Klára

2008-11-01

The main objective of this study was the application of a solution of human serum albumin as a granulating fluid. The properties of the granules formed were evaluated and compared with those when a conventional binder was applied in the same concentration. The powder mixture contained a soluble (mannitol) and an insoluble component (different types of cellulose). The protein solution applied exerted an appropriate aggregating effect if the system contained microcrystalline celluloses. Powdered cellulose was not suitable for the granulation with human serum albumin solution. As compared with the same concentration of the conventionally applied cellulose ethers as binder, the prepared granules exhibited a larger particle size, a significantly better compressibility, a higher breaking hardness and a favourable deformation process. These findings mainly reflect the good adhesive properties of the protein. The best compressibility and mechanical behaviour were attained on the application of the microcrystalline cellulose Vivapur type 105. This favourable behaviour may be connected with the wettability of cellulose. These results suggest that the formulation of tablets may be easier from an active agent in the serum that binds to albumin (e.g. interferon) since the amount of additives (binder) can be reduced.

N-Doped Carbon Nanofibrous Network Derived from Bacterial Cellulose for the Loading of Pt Nanoparticles for Methanol Oxidation Reaction.

Science.gov (United States)

Yuan, Fanshu; Huang, Yang; Fan, Mengmeng; Chen, Chuntao; Qian, Jieshu; Hao, Qingli; Yang, Jiazhi; Sun, Dongping

2018-02-06

The large-scale, low-cost preparation of Pt-based catalysts with high activity and durability for the methanol oxidation reaction is still challenging. The key to achieving this aim is finding suitable supporting materials. In this paper, N-doped carbon nanofibrous networks are prepared by annealing a gel containing two inexpensive and ecofriendly precursors, that is, bacterial cellulose and urea, for the loading of Pt nanoparticles. An undoped analogue is also prepared for comparison. Meanwhile, the effect of the annealing temperature on the performance of the catalysts is evaluated. The results show that the N doping and higher annealing temperature can improve the electron conductivity of the catalyst and provide more active sites for the loading of ultrafine Pt nanoparticles with a narrow size distribution. The best catalyst exhibits a remarkably high electrocatalytic activity (627 mA mg -1 ), excellent poison tolerance, and high durability. This work demonstrates an ideal Pt supporting material for the methanol oxidation reaction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

In vitro and in vivo investigation of bacterial cellulose dressing containing uniform silver sulfadiazine nanoparticles for burn wound healing

Directory of Open Access Journals (Sweden)

Xiaoxiao Wen

2015-06-01

Full Text Available Silver sulfadiazine (SSD particles in homogeneous dispersion state were prepared by an ultrasonic method and then nano- and microparticles were separated using centrifugation. SSD particles with narrow size distribution were impregnated with bacterial cellulose (BC to produce BC–SSD composite membrane used as burn wound dressing. A scanning electron microscope (SEM was used to examine the surface morphology of BC–SSD membranes. The incorporation of SSD in BC–SSD was confirmed by X-ray diffraction (XRD. Antimicrobial tests in vitro indicated that BC–SSD showed excellent antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli. The effects of BC–SSD on burn wound healing were assessed by rat models. The comparative study confirmed that the wound treated with BC–SSD showed high healing rate. The bacteria count in BC–SSD group was far less than control group. Histological analysis showed that epithelialization progressed better in wound treated with BC–SSD. These values demonstrated that the BC–SSD composite membrane could be a promising wound dressing for burn.

An Investigation of Cellulose Digesting Bacteria in the Panda Gut Microbiome

Science.gov (United States)

Lu, M.; Leung, F. C.

2014-12-01

The Giant Panda (Ailuropoda melanoleuca) diet consists primarily of bamboo leaves, stems and shoots. However, the Giant Panda lacks genes for the enzymes needed to digest cellulose, the core component of bamboo. Thus, it is hypothesized that the cellulolytic digestion necessary for maintaining the Giant Panda diet is carried out by microbial symbionts in the panda gut microbiota. Fecal microbiota is used as surrogate index for gut microbiota since the Giant Panda is listed by the World Conservation Union as a Threatened Species. Two bacterial isolates with potential cellulolytic activity were isolated from Giant Panda fecal samples and cultured on selective media CMC (carboxymethyl cellulose) agar and CMC-Congo Red agar using various methods of inoculation. After incubation, clearance zones around colonies were observed and used as qualitative assays for cellulose digestion. Polymerase chain reaction amplification of the 16S rRNA gene was completed and species identification was done based on the BLAST result of 16S rRNA sequence obtained using Sanger sequencing. Once the cellulase activity is confirmed, genomic DNA of the bacteria will be extracted and used for whole genome shotgun sequencing. Illumina next generation sequencing platform will be adopted as it yields high-throughput information, providing a better understanding of cellulose digestion and the molecular genetic pathways to renewable sources of biofuels. Researchers have identified multiple cellulose-digesting microbes in the Giant Panda gut, but few have applied such bacteria in converting cellulose into glucose to create biofuel. Cellulosic ethanol, a biofuel, is produced through the fermentation of lignocellulosic biomasses. This anaerobic process is aided by cellulose-digesting enzymes. Certain microbes, such as those present in the Giant Panda gut, can produce enzymes that cleave the glycosidic bonds of cellulose (C6H10O5) into glucose molecules (C6H12O6), which can then be fermented into ethanol

Inhibitory effect of cellulose fibers on the formation of heterocyclic aromatic amines in grilled beef patties.

Science.gov (United States)

Gibis, Monika; Weiss, Jochen

2017-08-15

Microcrystalline cellulose (MCC) or carboxymethyl cellulose (CMC) can be used as fat replacers; both are nondigestible fibers. As water-holding compounds, the impact of added CMC or MCC was studied concerning the formation of heterocyclic amines (HAAs). Low-fat patties with 0.5-3% MCC/CMC were prepared using 90% of beef and 10% of an aqueous fiber dispersion and were determined for HAA-levels after grilling. The HAAs in patties containing CMC(MCC) were found in the following concentrations; MeIQx (2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline) 0.6-2.7 (0.9-3.3)ng/g, 4,8-DiMeIQx (2-Amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline) n.d.-1.5 (n.d.-2.2)ng/g and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) 0.03-0.3 (0.06-0.2)ng/g. The patties clearly contained lower HAA-levels with increasing addition of CMC or MCC. A continuous increase of the concentrations of comutagenic harman was observed (CMC: 1.2-13.2; MCC: 5.2-11.4ng/g) for increasing levels of fibers and a slight decrease of the content of norharman for MCC (0.5-1.6ng/g). No clear tendency was found for norharman using CMC (0.3-1.1ng/g). Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation in Cellulolytic Activity of Stenotrophomonas sp. in Cellulose Nitrogen Free Mineral Medium

International Nuclear Information System (INIS)

Honey Thet Paing Htway; San San Yu; Zaw Ko Latt

2011-12-01

Three bacterial strains were isolated from rice rhizospheric soil and their nitrogen fixing activity was determined in nitrogen free mineral medium and broth with glucose and cellulose as carbon sources and they produced ammonium concentration (above 3ppm) in G-NFFMM and (2-3ppm) in C-NFMM. Moreover, their cellulolytic activity was determined by DNS mothod and strain H3 having the cellulolytic activity was selected. Then, cellulose, carboxymethyl cellulose, baggasse, pea haulm, corn stem, rice straw were used as substrates and determined its reducing sugar concentration. After detection of the cellulolytic activity, the bacteria produced the highest concentration of reducing sugar on cellulose substrate at 12 day incubation period with the reducing sugar amount of 0.12mg/ml and 0.298mg/ml on CMC substrates. In the study of argicultral wastes as substrates, the selected strain, H3, produced in the reducing sugar concentration with 0.12, 0.116,0.103 and 0.098mg/ml respectively. The selected strain was identified by biochemical characterists and 16s ribosomal DNA analysis and it was Stenotrophomonas sp.

Microcrystalline diamond cylindrical resonators with quality-factor up to 0.5 million

Energy Technology Data Exchange (ETDEWEB)

Saito, Daisuke; Yang, Chen; Lin, Liwei [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Heidari, Amir [Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616 (United States); Najar, Hadi [Department of Electrical and Computer Engineering, University of California, Davis, California 95616 (United States); Horsley, David A. [Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616 (United States); Department of Electrical and Computer Engineering, University of California, Davis, California 95616 (United States)

2016-02-01

We demonstrate high quality-factor 1.5 mm diameter batch-fabricated microcrystalline diamond cylindrical resonators (CR) with quality-factors limited by thermoelastic damping (TED) and surface loss. Resonators were fabricated 2.6 and 5.3 μm thick in-situ boron-doped microcrystalline diamond films deposited using hot filament chemical vapor deposition. The quality-factor (Q) of as-fabricated CR's was found to increase with the resonator diameter and diamond thickness. Annealing the CRs at 700 °C in a nitrogen atmosphere led to a three-fold increase in Q, a result we attribute to thinning of the diamond layer via reaction with residual O{sub 2} in the annealing furnace. Post-anneal Q exceeding 0.5 million (528 000) was measured at the 19 kHz elliptical wineglass modes, producing a ring-down time of 8.9 s. A model for Q versus diamond thickness and resonance frequency is developed including the effects of TED and surface loss. Measured quality factors are shown to agree with the predictions of this model.

An Investigation of Cellulose Digesting Bacteria in the Camel Feces Microbiome

Science.gov (United States)

Man, V.; Leung, F. C.

2015-12-01

Research Question: Is there a bacteria in camel feces that digests cellulose material and can be used for waste to energy projects? Fossil fuels are the current main resource of energy in the modern world. However, as the demand for fuel increases, biofuels have been proposed as an alternative energy source that is a more sustainable form of liquid fuel generation from living things or waste, commonly known as biofuels and ethanol. The Camelus dromedarius', also known as Arabian camel, diet consist of grass, grains, wheat and oats as well desert vegetation in their natural habitat. However, as the Arabian camel lacks the enzymes to degrade cellulose, it is hypothesized that cellulose digestion is performed by microbial symbionts in camel microbiota. Fecal samples were collected from the Camelus dromedarius in United Arab Emirates and diluted 10-7 times. The diluted sample was then streaked onto a Sodium Carboxymethyl Cellulose plate, and inoculated onto CMC and Azure-B plates. Afterwards, Congo Red was used for staining in order to identify clearance zones of single colonies that may potentially be used as a qualitative assays for cellulose digestion. Then the colonies undergo polymerase chain reaction amplification to produce amplified RNA fragments. The 16S ribosomal RNA gene is identified based on BLAST result using Sanger Sequencing. Amongst the three identified microbes: Bacillus, Staphylococcus and Escherichia coli, both Bacillus and Staphylococcus are cellulose-digesting microbes, and through the fermentation of lignocellulosic, biomasses can be converted into cellulosic ethanol (Biofuel). According to the Improvements in Life Cycle Energy Efficiency and Greenhouse Gas Emissions of Corn-Ethanol by Adam J. Liska, ""Ethanol reduces greenhouse gas emissions by 40-50% when compared directly to gasoline." The determination of bacterial communities that are capable of efficiently and effectively digesting cellulose materials requires that the bacteria be first

Bacterial Cellulose: A Robust Platform for Design of Three Dimensional Carbon-Based Functional Nanomaterials.

Science.gov (United States)

Wu, Zhen-Yu; Liang, Hai-Wei; Chen, Li-Feng; Hu, Bi-Cheng; Yu, Shu-Hong

2016-01-19

Three dimensional (3D) carbon nanomaterials exhibit great application potential in environmental protection, electrochemical energy storage and conversion, catalysis, polymer science, and advanced sensors fields. Current methods for preparing 3D carbon nanomaterials, for example, carbonization of organogels, chemical vapor deposition, and self-assembly of nanocarbon building blocks, inevitably involve some drawbacks, such as expensive and toxic precursors, complex equipment and technological requirements, and low production ability. From the viewpoint of practical application, it is highly desirable to develop a simple, cheap, and environmentally friendly way for fabricating 3D carbon nanomaterials in large scale. On the other hand, in order to extend the application scope and improve the performance of 3D carbon nanomaterials, we should explore efficient strategies to prepare diverse functional nanomaterials based on their 3D carbon structure. Recently, many researchers tend to fabricate high-performance 3D carbon-based nanomaterials from biomass, which is low cost, easy to obtain, and nontoxic to humans. Bacterial cellulose (BC), a typical biomass material, has long been used as the raw material of nata-de-coco (an indigenous dessert food of the Philippines). It consists of a polysaccharide with a β-1,4-glycosidic linkage and has a interconnected 3D porous network structure. Interestingly, the network is made up of a random assembly of cellulose nanofibers, which have a high aspect ratio with a diameter of 20-100 nm. As a result, BC has a high specific surface area. Additionally, BC hydrogels can be produced on an industrial scale via a microbial fermentation process at a very low price. Thus, it can be an ideal platform for design of 3D carbon-based functional nanomaterials. Before our work, no systematic work and summary on this topic had been reported. This Account presents the concepts and strategies of our studies on BC in the past few years, that is

Simultaneous solid phase extraction of cobalt, strontium and cesium from liquid radioactive waste using microcrystalline naphthalene

International Nuclear Information System (INIS)

Hamed, Mostafa Mohamed; Attallah, Mohamed Fathy; Metwally, Sayed Sayed

2014-01-01

Most of the procedures developed for the extraction of cobalt, strontium and cesium by solid phase extraction do not employ simultaneous extraction of them. In this study, rapid simultaneous removal of Co 2+ , Sr 2+ and Cs + on microcrystalline naphthalene as solid-phase extractant was investigated. These ions were allowed to form chelates with oxine and then adsorbed on freshly microcrystalline naphthalene from aqueous solutions. The solid phase extraction procedure (SPE) was optimized by using model solution containing Co 2+ , Sr 2+ and Cs + in batch system. The effects of different parameters such as variation in pH, reagent concentration, standing time, naphthalene solution concentration and contact time on the simultaneous removal of these ions was studied. The obtained results indicated that, sorption was found to be rapid, and the percentage removal of Co 2+ , Sr 2+ and Cs + was found to be 98, 79 and 68% within 10 min, respectively. The kinetics of the sorption process was investigated to understand the kinetic characteristics of sorption of metal chelates onto microcrystalline naphthalene. The developed procedure has been successfully applied to the removal and recovery of 60 Co and 134 Cs from liquid radioactive waste. The parameters can be used for designing a plant for treatment of wastewater economically.

INFLUENCE OF CELLULOSE POLYMERIZATION DEGREE AND CRYSTALLINITY ON KINETICS OF CELLULOSE DEGRADATION

OpenAIRE

Edita Jasiukaitytė-Grojzdek,; Matjaž Kunaver,; Ida Poljanšek

2012-01-01

Cellulose was treated in ethylene glycol with p-toluene sulfonic acid monohydrate as a catalyst at different temperatures. At the highest treatment temperature (150 °C) liquefaction of wood pulp cellulose was achieved and was dependant on cellulose polymerization degree (DP). Furthermore, the rate of amorphous cellulose weight loss was found to increase with cellulose degree of polymerization, while the rate of crystalline cellulose weight loss was reciprocal to the size of the crystallites. ...

Microcrystalline bottom cells in large area thin film silicon MICROMORPH™ solar modules

Czech Academy of Sciences Publication Activity Database

Hoetzel, J.E.; Caglar, O.; Cashmore, J.S.; Goury, C.; Kalaš, J.; Klindworth, M.; Kupich, M.; Leu, G.F.; Lindic, M.H.; Losio, P.A.; Mates, Tomáš; Mereu, B.; Roschek, T.; Sinicco, I.

2016-01-01

Roč. 157, Dec (2016), s. 178-189 ISSN 0927-0248 R&D Projects: GA MŠk LM2015087 Institutional support: RVO:68378271 Keywords : microcrystalline silicon * material quality * PECVD * Raman crystallinity * grading * micromorph Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 4.784, year: 2016

Effect of gamma irradiation on biopolymer composite films of poly(vinyl alcohol) and bacterial cellulose

Energy Technology Data Exchange (ETDEWEB)

Jipa, Iuliana Mihaela; Stroescu, Marta [University Politehnica of Bucharest, Department of Chemical Engineering, 313 Splaiul Independentei, Polizu 1-3, 060042 Bucharest (Romania); Stoica-Guzun, Anicuta, E-mail: stoica.anicuta@gmail.com [University Politehnica of Bucharest, Department of Chemical Engineering, 313 Splaiul Independentei, Polizu 1-3, 060042 Bucharest (Romania); Dobre, Tanase; Jinga, Sorin [University Politehnica of Bucharest, Department of Chemical Engineering, 313 Splaiul Independentei, Polizu 1-3, 060042 Bucharest (Romania); Zaharescu, Traian [Advanced Research Institute for Electrical Engineering, 313 Splaiul Unirii, 030138 Bucharest (Romania)

2012-05-01

Highlights: Black-Right-Pointing-Pointer The paper reports the obtaining of composite materials between PVA and BC. Black-Right-Pointing-Pointer The composite films were {gamma}-irradiated at doses up to 50 kGy. Black-Right-Pointing-Pointer The films have a good resistance, being suitable as food packaging materials. - Abstract: Composite materials containing in different ratios poly(vinyl alcohol) (PVA), bacterial cellulose (BC) and glycerol (G) as plasticizer were obtained and exposed to different {gamma} radiation doses using an irradiator GAMMATOR provided with {sup 137}Cs source. These films successively received up to 50 kGy absorbed doses at a dose rate of 0.4 kGy/h at room temperature. In order to study the chemical and structural changes during {gamma} irradiation, Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and UV-Vis spectroscopy were used. Water vapour permeability (WVP), Hunter colour parameters and hardness were also measured for the irradiated samples. Investigation revealed that WVP was not significantly affected by the irradiation. Colour measurements indicated a slight decrease of pure PVA films transparency and it made clear that all samples became more reddish and yellowish after irradiation. The samples hardness was not affected by the irradiation doses used. However, the results showed no drastic structural or chemical changes of the irradiated samples, which prove, in consequence, a good durability. These composite materials could be used as packaging materials for {gamma} irradiated products.

In Vivo Isotopic Labeling of Symbiotic Bacteria Involved in Cellulose Degradation and Nitrogen Recycling within the Gut of the Forest Cockchafer (Melolontha hippocastani).

Science.gov (United States)

Alonso-Pernas, Pol; Bartram, Stefan; Arias-Cordero, Erika M; Novoselov, Alexey L; Halty-deLeon, Lorena; Shao, Yongqi; Boland, Wilhelm

2017-01-01

The guts of insects harbor symbiotic bacterial communities. However, due to their complexity, it is challenging to relate a specific symbiotic phylotype to its corresponding function. In the present study, we focused on the forest cockchafer ( Melolontha hippocastani ), a phytophagous insect with a dual life cycle, consisting of a root-feeding larval stage and a leaf-feeding adult stage. By combining in vivo stable isotope probing (SIP) with 13 C cellulose and 15 N urea as trophic links, with Illumina MiSeq (Illumina-SIP), we unraveled bacterial networks processing recalcitrant dietary components and recycling nitrogenous waste. The bacterial communities behind these processes change between larval and adult stages. In 13 C cellulose-fed insects, the bacterial families Lachnospiraceae and Enterobacteriaceae were isotopically labeled in larvae and adults, respectively. In 15 N urea-fed insects, the genera Burkholderia and Parabacteroides were isotopically labeled in larvae and adults, respectively. Additionally, the PICRUSt-predicted metagenome suggested a possible ability to degrade hemicellulose and to produce amino acids of, respectively, 13 C cellulose- and 15 N urea labeled bacteria. The incorporation of 15 N from ingested urea back into the insect body was confirmed, in larvae and adults, by isotope ratio mass spectrometry (IRMS). Besides highlighting key bacterial symbionts of the gut of M. hippocastani , this study provides example on how Illumina-SIP with multiple trophic links can be used to target microorganisms embracing different roles within an environment.

In Vivo Isotopic Labeling of Symbiotic Bacteria Involved in Cellulose Degradation and Nitrogen Recycling within the Gut of the Forest Cockchafer (Melolontha hippocastani

Directory of Open Access Journals (Sweden)

Pol Alonso-Pernas

2017-10-01

Full Text Available The guts of insects harbor symbiotic bacterial communities. However, due to their complexity, it is challenging to relate a specific symbiotic phylotype to its corresponding function. In the present study, we focused on the forest cockchafer (Melolontha hippocastani, a phytophagous insect with a dual life cycle, consisting of a root-feeding larval stage and a leaf-feeding adult stage. By combining in vivo stable isotope probing (SIP with 13C cellulose and 15N urea as trophic links, with Illumina MiSeq (Illumina-SIP, we unraveled bacterial networks processing recalcitrant dietary components and recycling nitrogenous waste. The bacterial communities behind these processes change between larval and adult stages. In 13C cellulose-fed insects, the bacterial families Lachnospiraceae and Enterobacteriaceae were isotopically labeled in larvae and adults, respectively. In 15N urea-fed insects, the genera Burkholderia and Parabacteroides were isotopically labeled in larvae and adults, respectively. Additionally, the PICRUSt-predicted metagenome suggested a possible ability to degrade hemicellulose and to produce amino acids of, respectively, 13C cellulose- and 15N urea labeled bacteria. The incorporation of 15N from ingested urea back into the insect body was confirmed, in larvae and adults, by isotope ratio mass spectrometry (IRMS. Besides highlighting key bacterial symbionts of the gut of M. hippocastani, this study provides example on how Illumina-SIP with multiple trophic links can be used to target microorganisms embracing different roles within an environment.

Cellulose-Hemicellulose Interactions at Elevated Temperatures Increase Cellulose Recalcitrance to Biological Conversion

Energy Technology Data Exchange (ETDEWEB)

Mittal, Ashutosh [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Himmel, Michael E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kumar, Rajeev [University of California, Riverside; Oak Ridge National Laboratory; ; Smith, Micholas Dean [Oak Ridge National Laboratory; University of Tennessee; Petridis, Loukas [Oak Ridge National Laboratory; University of Tennessee; Ong, Rebecca G. [Michigan Technological University; Cai, Charles M. [University of California, Riverside; Oak Ridge National Laboratory; Balan, Venkatesh [University of Houston; Dale, Bruce E. [Michigan State University; Ragauskas, Arthur J. [Oak Ridge National Laboratory; University of Tennessee; Smith, Jeremy C. [Oak Ridge National Laboratory; University of Tennessee; Wyman, Charles E. [University of California, Riverside; Oak Ridge National Laboratory

2018-01-23

It has been previously shown that cellulose-lignin droplets' strong interactions, resulting from lignin coalescence and redisposition on cellulose surface during thermochemical pretreatments, increase cellulose recalcitrance to biological conversion, especially at commercially viable low enzyme loadings. However, information on the impact of cellulose-hemicellulose interactions on cellulose recalcitrance following relevant pretreatment conditions are scarce. Here, to investigate the effects of plausible hemicellulose precipitation and re-association with cellulose on cellulose conversion, different pretreatments were applied to pure Avicel(R) PH101 cellulose alone and Avicel mixed with model hemicellulose compounds followed by enzymatic hydrolysis of resulting solids at both low and high enzyme loadings. Solids produced by pretreatment of Avicel mixed with hemicelluloses (AMH) were found to contain about 2 to 14.6% of exogenous, precipitated hemicelluloses and showed a remarkably much lower digestibility (up to 60%) than their respective controls. However, the exogenous hemicellulosic residues that associated with Avicel following high temperature pretreatments resulted in greater losses in cellulose conversion than those formed at low temperatures, suggesting that temperature plays a strong role in the strength of cellulose-hemicellulose association. Molecular dynamics simulations of hemicellulosic xylan and cellulose were found to further support this temperature effect as the xylan-cellulose interactions were found to substantially increase at elevated temperatures. Furthermore, exogenous, precipitated hemicelluloses in pretreated AMH solids resulted in a larger drop in cellulose conversion than the delignified lignocellulosic biomass containing comparably much higher natural hemicellulose amounts. Increased cellulase loadings or supplementation of cellulase with xylanases enhanced cellulose conversion for most pretreated AMH solids; however, this approach

Chapter 1.4: Spatially Resolved Characterization of CNC-Polypropylene composite by Confocal Raman Microscopy

Science.gov (United States)

Umesh Agarwal; Ronald Sabo; Richard Reiner; Craig Clemons; Alan Rudie

2013-01-01

Raman spectroscopy was used to analyze cellulose nanocrystal (CNC)-polypropylene (PP) composites and to investigate the spatial distribution of CNCs in extruded composite filaments. Three composites were made from two forms of nanocellulose (CNCs from wood pulp and the nanoscale fraction of microcrystalline cellulose), and two of the three composites...

Cellulose utilization in forest litter and soil: identification of bacterial and fungal decomposers

Czech Academy of Sciences Publication Activity Database

Štursová, Martina; Žifčáková, Lucia; Leigh, M. B.; Burgess, R.; Baldrian, Petr

2012-01-01

Roč. 80, č. 3 (2012), s. 735-746 ISSN 0168-6496 R&D Projects: GA ČR GA526/08/0751; GA MŠk(CZ) ME10028 Institutional research plan: CEZ:AV0Z50200510 Keywords : cellobiohydrolase * decomposition * cellulose Subject RIV: EE - Microbiology, Virology Impact factor: 3.563, year: 2012

Preconcentration of uranium, thorium, zirconium, titanium, molybdenum and vanadium with oxine supported on microcrystalline naphthalene and their determinations by ICP-AES

International Nuclear Information System (INIS)

Kumar, Naveen; Kumar, Sanjay; Kumar, Vijay; Nandakishore, S.S.; Bangroo, P.N.

2013-01-01

As an effective technique for separation and preconcentration of trace elements, solid-liquid extraction with microcrystalline naphthalene has received great attention in recent years. The application of the adsorption of the metal complexes on microcrystalline naphthalene has greatly enhanced the utility of solid-liquid extraction in trace analysis. A survey of the literature revealed that single element detection techniques such as spectrophotometry, atomic absorption spectrometry, and polarography were mostly combined with this separation method. However, multi-element simultaneous detection techniques, like ICP-AES and ICP-MS were seldom used as the detectors in this solid-liquid extraction method. The aim of this work was to attempt to adopt the reagent oxine for the separation and subsequent determination of U, Th, Zr, Ti, Mo and V by ICP-AES, after adsorption of their oxinate complexes on microcrystalline naphthalene

Synthesis and characterization of amorphous cellulose from triacetate of cellulose

International Nuclear Information System (INIS)

Vega-Baudrit, Jose; Sibaja, Maria; Nikolaeva, Svetlana; Rivera A, Andrea

2014-01-01

It was carried-out a study for the synthesis and characterization of amorphous cellulose starting from cellulose triacetate. X-rays diffraction was used in order to obtain the cellulose crystallinity degree, also infrared spectroscopy FTIR was used. (author)

Raman mapping of microcrystalline silicon thin films with high spatial resolution

Czech Academy of Sciences Publication Activity Database

Ledinský, Martin; Vetushka, Aliaksi; Stuchlík, Jiří; Fejfar, Antonín; Kočka, Jan

2010-01-01

Roč. 7, 3-4 (2010), s. 704-707 ISSN 1862-6351 R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR KAN400100701; GA MŠk LC510; GA AV ČR(CZ) IAA100100902 Institutional research plan: CEZ:AV0Z10100521 Keywords : Raman * atomic force microscopy * microcrystalline silicon Subject RIV: BM - Solid Matter Physics ; Magnetism http://www3.interscience.wiley.com/journal/123277609/abstract

Characterization of microcrystalline I-layer for solar cells prepared in low temperature - plastic compatible process

KAUST Repository

Sliz, Rafal; Ahnood, Arman; Nathan, Arokia; Myllyla, Risto; Jabbour, Ghassan E.

2012-01-01

Microcrystalline silicon (mc-Si) lms deposited using a Plasma Enhanced Chemical Vapour Deposition (PECVD) process constitute an important material for manufacturing low-cost, large-area thin-lm devices, such as solar cells or thin-lm transistors

Novel proton exchange membranes based on structure-optimized poly(ether ether ketone ketone)s and nanocrystalline cellulose

Science.gov (United States)

Ni, Chuangjiang; Wei, Yingcong; Zhao, Qi; Liu, Baijun; Sun, Zhaoyan; Gu, Yan; Zhang, Mingyao; Hu, Wei

2018-03-01

Two sulfonated fluorenyl-containing poly(ether ether ketone ketone)s (SFPEEKKs) were synthesized as the matrix of composite proton exchange membranes by directly sulfonating copolymer precursors comprising non-sulfonatable fluorinated segments and sulfonatable fluorenyl-containing segments. Surface-modified nanocrystalline cellulose (NCC) was produced as the "performance-enhancing" filler by treating the microcrystalline cellulose with acid. Two families of SFPEEKK/NCC nanocomposite membranes with various NCC contents were prepared via a solution-casting procedure. Results revealed that the insertion of NCC at a suitable ratio could greatly enhance the proton conductivity of the pristine membranes. For example, the proton conductivity of SFPEEKK-60/NCC-4 (SFPEEKK with 60% fluorenyl segments in the repeating unit, and inserted with 4% NCC) composite membrane was as high as 0.245 S cm-1 at 90 °C, which was 61.2% higher than that of the corresponding pure SFPEEKK-60 membrane. This effect could be attributed to the formation of hydrogen bond networks and proton conduction paths through the interaction between -SO3H/-OH groups on the surface of NCC particles and -SO3H groups on the SFPEEKK backbones. Furthermore, the chemically modified NCC filler and the optimized chemical structure of the SFPEEKK matrix also provided good dimensional stability and mechanical properties of the obtained nanocomposites. In conclusion, these novel nanocomposites can be promising proton exchange membranes for fuel cells at moderate temperatures.

The open-circuit voltage in microcrystalline silicon solar cells of different degrees of crystallinity

International Nuclear Information System (INIS)

Nath, Madhumita; Roca i Cabarrocas, P.; Johnson, E.V.; Abramov, A.; Chatterjee, P.

2008-01-01

We have used a detailed electrical-optical computer model (ASDMP) in conjunction with the experimental characterization of microcrystalline silicon thin-film solar cells of different degrees of crystallinity (but having identical P- and N-layers) to understand the observed decrease of the open-circuit voltage with increasing crystalline fraction. In order to model all aspects of the experimental current density-voltage and quantum efficiency characteristics of cells having low (∼ 75%) and high (over 90%) crystalline fraction, we had to assume both a higher mobility gap defect density and a lower band gap for the more crystallized material. The former fact is widely known to bring down the open-circuit voltage. Our calculations also reveal that the proximity of the quasi-Fermi levels to the energy bands in the cell based on highly crystallized (and assumed to have a lower band gap) microcrystalline silicon results in higher free and trapped carrier densities in this device. The trapped hole population is particularly high at and close to the P/I interface on account of the higher inherent defect density in this region and the fact that the hole quasi-Fermi level is close to the valence band edge here. This fact results in a strong interface field, a collapse of the field in the volume, and hence a lower open-circuit voltage. Thus a combination of higher mobility gap defects and a lower band gap is probably the reason for the lower open-circuit voltage in cells based on highly crystallized microcrystalline silicon

Ultrafast carrier dynamics in microcrystalline silicon probed by time-resolved terahertz spectroscopy

Czech Academy of Sciences Publication Activity Database

Fekete, Ladislav; Kužel, Petr; Němec, Hynek; Kadlec, Filip; Deyneka, Alexander; Stuchlík, Jiří; Fejfar, Antonín

2009-01-01

Roč. 79, č. 11 (2009), 115306/1-115306/13 ISSN 1098-0121 R&D Projects: GA MŠk(CZ) LC06040; GA AV ČR(CZ) IAA100100902 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z10100521 Keywords : microcrystalline silicon * amorphous silicon * terahertz * ultrafast * photoconductivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.475, year: 2009

Approaching zero cellulose loss in cellulose nanocrystal (CNC) production: recovery and characterization of cellulosic solid residues (CSR) and CNC

Science.gov (United States)

Q.Q. Wang; J.Y. Zhu; R.S. Reiner; S.P. Verrill; U. Baxa; S.E. McNeil

2012-01-01

This study demonstrated the potential of simultaneously recovering cellulosic solid residues (CSR) and producing cellulose nanocrystals (CNCs) by strong sulfuric acid hydrolysis to minimize cellulose loss to near zero. A set of slightly milder acid hydrolysis conditions than that considered as “optimal” were used to significantly minimize the degradation of cellulose...

Radiation modification of cellulose pulps. Preparation of cellulose derivatives

International Nuclear Information System (INIS)

Iller, E.; Zimek, Z.; Stupinska, H.; Mikolajczyk, W; Starostka, P.

2005-01-01

One of the most common methods of cellulose pulp modification (activation) applied in the production process of cellulose derivatives is the treatment of the pulp with NaOH solutions leading to the formation of alkalicellulose. The product then undergoes a prolonged process of maturation by its storage under specific conditions. The goal of the process is lowering of the molecular weight of cellulose down to the level resulting from various technological requirements. The process is time-consuming and costly; besides, it requires usage of large-capacity technological vessels and produces considerable amounts of liquid waste. Therefore, many attempts have been made to limit or altogether eliminate the highly disadvantageous stage of cellulose treatment with lye. One of the alternatives proposed so far is the radiation treatment of the cellulose pulp. In the pulp exposed to an electron beam, the bonds between molecules of D-antihydroglucopiranoses loosen and the local crystalline lattice becomes destroyed. This facilitates the access of chemical reagents to the inner structure of the cellulose and, in consequence, eliminates the need for the prolonged maturation of alkalicellulose, thus reducing the consumption of chemicals by the whole process. Research aimed at the application of radiation treatment of cellulose pulp for the production of cellulose derivatives has been conducted by a number of scientific institutions including the Institute of Nuclear Chemistry and Technology, Institute of Biopolymers and Chemical Fibres, and Pulp and Paper Research Institute. For the investigations and assessment of the molecular, hypermolecular, morphologic properties and the chemical reactivity, cellulose pulps used for chemical processing, namely Alicell, Borregaard and Ketchikan, as well as paper pulps made from pine and birch wood were selected. The selected cellulose pulps were exposed to an electron beam with an energy of 10 MeV generated in a linear electron accelerator

Compressibility of tableting materials and properties of tablets with glyceryl behenate

Directory of Open Access Journals (Sweden)

Mužíková Jitka

2015-03-01

Full Text Available The paper studies the compressibility of directly compressible tableting materials with dry binders, spray-dried lactose and microcrystalline cellulose, and glyceryl dibehenate at various concentrations. Compressibility was evaluated by means of the energy profile of compression and tensile strength of tablets. Release rate of the active ingredient, salicylic acid, from the tablets was also examined. In the case of microcrystalline cellulose, a higher concentration of glyceryl dibehenate increased the strength of tablets, while this did not occur in the case of spray-dried lactose. Increasing concentration of glyceryl dibehenate prolonged the release of salicylic acid; however, no statistically significant difference was found compared to the type of the dry binder used

Glycerol as a Cheaper Carbon Source in Bacterial Cellulose (BC) Production by Gluconacetobacter Xylinus DSM46604 in Batch Fermentation System

International Nuclear Information System (INIS)

Azila Adnan; Nair, G.R.; Roslan Umar; Roslan Umar

2015-01-01

Bacterial cellulose (BC) is a polymer of glucose monomers, which has unique properties including high crystallinity and high strength. It has potential to be used in biomedical applications such as making artificial blood vessel, wound dressings, and in the paper making industry. Extensive study on BC aimed to improve BC production such as by using glycerol as a cheaper carbon source. BC was produced in shake flask culture using five different concentrations of glycerol (10, 20, 30, 40 and 50 g/ L). Using concentration of glycerol above 20 g/ L inhibited culture growth and BC production. Further experiments were performed in batch culture (3-L bioreactor) using 20 g/ L glycerol. It produced yield and productivity of 0.15 g/ g and 0.29 g/ L/ day BC, respectively. This is compared with the control medium, 50 g/ L glucose, which only gave yield and productivity of 0.05 g/ g and 0.23 g/ L/ day, respectively. Twenty g/ L of glycerol enhanced BC production by Gluconacetobacter xylinus DSM46604 in batch fermentation system. (author)

Water-Protein Hydrogen Exchange in the Micro-Crystalline Protein Crh as Observed by Solid State NMR Spectroscopy

International Nuclear Information System (INIS)

Boeckmann, Anja; Juy, Michel; Bettler, Emmanuel; Emsley, Lyndon; Galinier, Anne; Penin, Francois; Lesage, Anne

2005-01-01

We report site-resolved observation of hydrogen exchange in the micro-crystalline protein Crh. Our approach is based on the use of proton T 2 ' -selective 1 H- 13 C- 13 C correlation spectra for site-specific assignments of carbons nearby labile protein protons. We compare the proton T 2 ' selective scheme to frequency selective water observation in deuterated proteins, and discuss the impacts of deuteration on 13 C linewidths in Crh. We observe that in micro-crystalline proteins, solvent accessible hydroxyl and amino protons show comparable exchange rates with water protons as for proteins in solution, and that structural constraints, such as hydrogen bonding or solvent accessibility, more significantly reduce exchange rates

Location and limitation of cellulose production by Acetobacter xylinum established from oxygen profiles

NARCIS (Netherlands)

Verschuren, P.G.; Cardona, T.D.; Nout, M.J.R.; Gooijer, de K.D.; Heuvel, van den J.C.

2000-01-01

The static fermentation of coconut water sucrose by Acetobacter xylinum was carried out at initial pH's of 3.0, 4.0, 5.0 or 6.0. Cellulose was produced at the surface, and its production was most favourable at pH's 4.0 and 5.0. These pH values also allowed for optimal bacterial growth. Oxygen

Amorphous and microcrystalline silicon applied in very thin tandem solar cells

Energy Technology Data Exchange (ETDEWEB)

Schicho, Sandra

2011-07-28

Thin-film solar cells are fabricated by low-cost production processes, and are therefore an alternative to conventionally used wafer solar cells based on crystalline silicon. Due to the different band gaps, tandem cells that consist of amorphous (a-Si:H) and microcrystalline ({mu}c-Si:H) single junction solar cells deposited on top of each other use the solar spectrum much more efficient than single junction solar cells. The silicon layers are usually deposited on TCO (Transparent Conductive Oxide)-coated glass and metal- or plastic foils. Compared to the CdTe and CIGS based thin-film technologies, silicon thin-film solar cells have the advantage that no limitation of raw material supply is expected and no toxic elements are used. Nevertheless, the production cost per Wattpeak is the decisive factor concerning competitiveness and can be reduced by, e.g., shorter deposition times or reduced material consumption. Both cost-reducing conceptions are simultaneously achieved by reducing the a-Si:H and {mu}c-Si:H absorber layer thicknesses in a tandem device. In the work on hand, the influence of an absorber layer thickness reduction up to 77% on the photovoltaic parameters of a-Si:H/{mu}c-Si:H tandem solar cells was investigated. An industry-oriented Radio Frequency Plasma-Enhanced Chemical Vapour Deposition (RF-PECVD) system was used to deposit the solar cells on glass substrates coated with randomly structured TCO layers. The thicknesses of top and bottom cell absorber layers were varied by adjusting the deposition time. Reduced layer thicknesses lead to lower absorption and, hence, to reduced short-circuit current densities which, however, are partially balanced by higher open-circuit voltages and fill factors. Furthermore, by using very thin amorphous top cells, the light-induced degradation decreases tremendously. Accordingly, a thickness reduction of 75% led to an efficiency loss of only 21 %. By adjusting the parameters for the deposition of a-Si:H top cells, a

77 FR 25720 - Determination That GRIFULVIN V (Griseofulvin Microcrystalline) Tablets, 250 Milligrams, Was Not...

Science.gov (United States)

2012-05-01

... been discontinued from marketing for reasons other than safety or effectiveness. ANDAs that refer to... Sale for Reasons of Safety or Effectiveness AGENCY: Food and Drug Administration, HHS. ACTION: Notice... microcrystalline) tablets, 250 milligrams (mg), was not withdrawn from sale for reasons of safety or effectiveness...

Nucleation of microcrystalline silicon: on the effect of the substrate surface nature and nano-imprint topography

International Nuclear Information System (INIS)

Palmans, J; Faraz, T; Verheijen, M A; Kessels, W M M; Creatore, M

2016-01-01

The nucleation of microcrystalline silicon thin-films has been investigated for various substrate natures and topographies. An earlier nucleation onset on aluminium-doped zinc oxide compared to glass substrates has been revealed, associated with a microstructure enhancement and reduced surface energy. Both aspects resulted in a larger crystallite density, following classical nucleation theory. Additionally, the nucleation onset was (plasma deposition) condition-dependent. Therefore, surface chemistry and its interplay with the plasma have been proposed as key factors affecting nucleation and growth. As such, preliminary proof of the substrate nature’s role in microcrystalline silicon growth has been provided. Subsequently, the impact of nano-imprint lithography prepared surfaces on the initial microcrystalline silicon growth has been explored. Strong topographies, with a 5-fold surface area enhancement, led to a reduction in crystalline volume fraction of ∼20%. However, no correlation between topography and microstructure has been found. Instead, the suppressed crystallization has been partially ascribed to a reduced growth flux, limited surface diffusion and increased incubation layer thickness, originating from the surface area enhancement when transiting from flat to nanostructured surfaces. Furthermore, fundamental plasma parameters have been reviewed in relation with surface topography. Strong topographies are not expected to affect the ion-to-growth flux ratio. However, the reduced ion flux (due to increasing surface area) further limited the already weak ion energy transfer to surface processes. Additionally, the atomic hydrogen flux, i.e. the driving force for microcrystalline growth, has been found to decrease by a factor of 10 when transiting from flat to nanostructured topography. This resulted in an almost 6-fold reduction of the hydrogen-to-growth flux ratio, a much stronger effect than the ion-to-growth flux ratio. Since previous studies regarding

Characterization of Type-II Acetylated Cellulose Nanocrystals with Various Degree of Substitution and Its Compatibility in PLA Films

Directory of Open Access Journals (Sweden)

Feng Dong

2017-08-01

Full Text Available In order to decrease the self-agglomeration and improve the hydrophobic properties of type-II acetylated cellulose nanocrystals (ACNC II, various degree of substitution (DS values of ACNCs were successfully prepared by a single-step method from microcrystalline cellulose with anhydrous phosphoric acid as the solvent, and acetic anhydride as the acetylation reagent, under different reaction temperatures (20–40 °C. To thoroughly investigate the DS values of ACNC II, analyses were performed using Fourier transform infrared spectroscopy (FT-IR, 13C cross polarization-magic angle spinning (CP-MAS nuclear magnetic resonance (NMR, and X-ray photoelectron spectroscopy (XPS. At a reaction temperature of 40°C, the highest DS value was successfully obtained. XRD proved that the crystal structure of ACNC II with various DS values was maintained after acetylation. TEM showed the threadlike shape for ACNC II with various DS values. The ACNC II with various DS values was introduced into a polylactic acid (PLA matrix to produce PLA/ACNC composite films, which showed improved rheological and thermal properties. This improvement was primarily attributed to good dispersion of the ACNC II, and the interfacial compatibility between ACNC II and the PLA matrix. This study aims to analyze the compatibility of ACNC II with various DS values in the PLA matrix by microstructure, crystallization, and rheological and thermal tests.

Functional analysis of the Glucan Degradation Locus (GDL) in Caldicellulosiruptor bescii reveals essential roles of component glycoside hydrolases in plant biomass deconstruction.

Science.gov (United States)

Conway, Jonathan M; McKinley, Bennett S; Seals, Nathaniel L; Hernandez, Diana; Khatibi, Piyum A; Poudel, Suresh; Giannone, Richard J; Hettich, Robert L; Williams-Rhaesa, Amanda M; Lipscomb, Gina L; Adams, Michael W W; Kelly, Robert M

2017-10-06

The ability to hydrolyze microcrystalline cellulose is an uncommon feature in the microbial world, but one that can be exploited for conversion of lignocellulosic feedstocks into bio-based fuels and chemicals. Understanding the physiological and biochemical mechanisms by which microorganisms deconstruct cellulosic material is key to achieving this objective. The Glucan Degradation Locus (GDL) in the genomes of extremely thermophilic Caldicellulosiruptor species encodes polysaccharide lyases (PLs), unique cellulose binding proteins (tāpirins), and putative post-translational modifying enzymes, in addition to multi-domain, multi-functional glycoside hydrolases (GHs), thereby representing an alternative paradigm for plant biomass degradation, as compared to fungal or cellulosomal systems. To examine the individual and collective in vivo roles of the glycolytic enzymes, the six GHs in the GDL of Caldicellulosiruptor bescii were systematically deleted, and the extent to which the resulting mutant strains could solubilize microcrystalline cellulose (Avicel) and plant biomasses (switchgrass or poplar) was examined. Three of the GDL enzymes, Athe_1867 (CelA) (GH9-CBM3-CBM3-CBM3-GH48), Athe_1859 (GH5-CBM3-CBM3-GH44), and Athe_1857 (GH10-CBM3-CBM3-GH48), acted synergistically in vivo and accounted for 92% of naked microcellulose (Avicel) degradation. However, the relative importance of the GDL GHs varied for the plant biomass substrates tested. Furthermore, mixed cultures of mutant strains showed switchgrass solubilization depended on the secretome-bound enzymes collectively produced by the culture and not on the specific strain from which they came. These results demonstrate that certain GDL GHs are primarily responsible for the degradation of microcrystalline-containing substrates by C. bescii and provide new insights into the workings of a novel microbial mechanism for lignocellulose utilization. Importance The efficient and extensive degradation of complex

On the oxidation mechanism of microcrystalline silicon thin films studied by Fourier transform infrared spectroscopy

NARCIS (Netherlands)

Bronneberg, A. C.; Smets, A. H. M.; Creatore, M.; M. C. M. van de Sanden,

2011-01-01

Insight into the oxidation mechanism of microcrystalline silicon thin films has been obtained by means of Fourier transform infrared spectroscopy. The films were deposited by using the expanding thermal plasma and their oxidation upon air exposure was followed in time. Transmission spectra were

Thermal Infrared Spectra of Microcrystalline Sedimentary Phases: Effects of Natural Surface Roughness on Spectral Feature Shape

Science.gov (United States)

Hardgrove, C.; Rogers, A. D.

2012-03-01

Thermal infrared spectral features of common microcrystalline phases (chert, alabaster, micrite) are presented. Spectra are sensitive to mineralogy and micron-scale (~1-25 µm) surface roughness. Roughness is on the scale of the average crystal size.

Preparation and Characterization of Resorbable Bacterial Cellulose Membranes Treated by Electron Beam Irradiation for Guided Bone Regeneration

Directory of Open Access Journals (Sweden)

Sung-Jun An

2017-10-01

Full Text Available Bacterial cellulose (BC is an excellent biomaterial with many medical applications. In this study, resorbable BC membranes were prepared for guided bone regeneration (GBR using an irradiation technique for applications in the dental field. Electron beam irradiation (EI increases biodegradation by severing the glucose bonds of BC. BC membranes irradiated at 100 kGy or 300 kGy were used to determine optimal electron beam doses. Electron beam irradiated BC membranes (EI-BCMs were evaluated by scanning electron microscopy (SEM, attenuated total reflectance-Fourier transform infrared (ATR-FTIR spectroscopy, thermal gravimetric analysis (TGA, and using wet tensile strength measurements. In addition, in vitro cell studies were conducted in order to confirm the cytocompatibility of EI-BCMs. Cell viabilities of NIH3T3 cells on 100k and 300k EI-BCMs (100 kGy and 300 kGy irradiated BC membranes were significantly greater than on NI-BCMs after 3 and 7 days (p < 0.05. Bone regeneration by EI-BCMs and their biodegradabilities were also evaluated using in vivo rat calvarial defect models for 4 and 8 weeks. Histometric results showed 100k EI-BCMs exhibited significantly larger new bone area (NBA; % than 300k EI-BCMs at 8 weeks after implantation (p < 0.05. Mechanical, chemical, and biological analyses showed EI-BCMs effectively interacted with cells and promoted bone regeneration.

A Highly Flexible Supercapacitor Based on MnO2/RGO Nanosheets and Bacterial Cellulose-Filled Gel Electrolyte

Directory of Open Access Journals (Sweden)

Haojie Fei

2017-10-01

Full Text Available The flexible supercapacitors (SCs of the conventional sandwich-type structure have poor flexibility due to the large thickness of the final entire device. Herein, we have fabricated a highly flexible asymmetric SC using manganese dioxide (MnO2 and reduced graphene oxide (RGO nanosheet-piled hydrogel films and a novel bacterial cellulose (BC-filled polyacrylic acid sodium salt-Na2SO4 (BC/PAAS-Na2SO4 neutral gel electrolyte. Apart from being environmentally friendly, this BC/PAAS-Na2SO4 gel electrolyte has high viscosity and a sticky property, which enables it to combine two electrodes together. Meanwhile, the intertangling of the filled BC in the gel electrolyte hinders the decrease of the viscosity with temperature, and forms a separator to prevent the two electrodes from short-circuiting. Using these materials, the total thickness of the fabricated device does not exceed 120 μm. This SC device demonstrates high flexibility, where bending and even rolling have no obvious effect on the electrochemical performance. In addition, owing to the asymmetric configuration, the cell voltage of this flexible SC has been extended to 1.8 V, and the energy density can reach up to 11.7 Wh kg−1 at the power density of 441 W kg−1. This SC also exhibits a good cycling stability, with a capacitance retention of 85.5% over 5000 cycles.

Development and characterization of bacterial cellulose reinforced biocomposite films based on protein from buckwheat distiller's dried grains.

Science.gov (United States)

Wang, Xuejiao; Ullah, Niamat; Sun, Xuchun; Guo, Yan; Chen, Lin; Li, Zhixi; Feng, Xianchao

2017-03-01

Biocomposite films were manufactured by combining protein extracted from buckwheat distiller's dried grains with bacterial cellulose (BC). The film microstructures showed that BC is compatible with protein matrix and endows the film with high rigidity. Differential scanning calorimetry (DSC) showed that BC can promote thermal stability of the composite films. BC promoted the transition from a Newtonian to a non-Newtonian fluid and the shear thinning behavior of protein-BC solution. Fourier Transform Infrared (FTIR) spectroscopy showed the main functional groups' absorption peaks shifted to lower wavenumbers. Results of both FTIR and viscosity analysis proved the formation of intermolecular interactions through hydrogen bonds. These bonds affected film characteristics such as moisture content (MC), water solubility (WS), and water vapor permeability (WVP), which decreased with addition of BC. The WVP (6.68±0.78-5.95±0.54×10 -10 gm/Pasm 2 ) of the films were lower than other protein films. Tensile strength (TS) values of films containing 1.8% and 2.0% BC (14.98±0.97 and 15.03±2.04MPa) were significantly higher than that of pure protein films (4.26±0.66MPa). Combination of proteins extracted from a waste product and BC led to composite films with low water vapor permeability and excellent mechanical properties. Copyright © 2016 Elsevier B.V. All rights reserved.

The cellulose synthase companion proteins act non-redundantly with CELLULOSE SYNTHASE INTERACTING1/POM2 and CELLULOSE SYNTHASE 6

OpenAIRE

Endler, Anne; Schneider, Rene; Kesten, Christopher; Lampugnani, Edwin R.; Persson, Staffan

2016-01-01

Cellulose is a cell wall constituent that is essential for plant growth and development, and an important raw material for a range of industrial applications. Cellulose is synthesized at the plasma membrane by massive cellulose synthase (CesA) complexes that track along cortical microtubules in elongating cells of Arabidopsis through the activity of the protein CELLULOSE SYNTHASE INTERACTING1 (CSI1). In a recent study we identified another family of proteins that also are associated with the ...

Ionic Liquids and Cellulose: Dissolution, Chemical Modification and Preparation of New Cellulosic Materials

Science.gov (United States)

Isik, Mehmet; Sardon, Haritz; Mecerreyes, David

2014-01-01

Due to its abundance and a wide range of beneficial physical and chemical properties, cellulose has become very popular in order to produce materials for various applications. This review summarizes the recent advances in the development of new cellulose materials and technologies using ionic liquids. Dissolution of cellulose in ionic liquids has been used to develop new processing technologies, cellulose functionalization methods and new cellulose materials including blends, composites, fibers and ion gels. PMID:25000264

Preparation and Characterisation of Amorphous-silicon Photovoltaic Devices Having Microcrystalline Emitters

International Nuclear Information System (INIS)

Gutierrez, M. T.; Gandia, J. J.; Carabe, J.

1999-01-01

The present work summarises the essential aspects of the research carried out so far at CIEMAT on amorphous-silicon solar cells. The experience accumulated on the preparation and characterisation of amorphous and microcrystalline silicon has allowed to start from intrinsic (absorbent) and p- and n-type (emitters) materials not only having excellent optoelectronic properties, but enjoying certain technological advantages with respect to those developed by other groups. Among these are absorbent-layer growth rates between 5 and 10 times as fast as conventional ones and microcrystalline emitters prepared without using hydrogen. The preparation of amorphous-silicon cells has required the solution of a number of problems, such as those related to pinholes, edge leak currents and diffusion of metals into the semiconductor. Once such constraints have been overcome, it has been demonstrated not only that the amorphous-silicon technology developed at CIEMAT is valid for making solar cells, but also that the quality of the semiconductor material is good for the application according to the partial results obtained. The development of thin-film laser-scribing technology is considered essential. Additionally it has been concluded that cross contamination, originated by the fact of using a single-chamber reactor, is the basic factor limiting the quality of the cells developed at CIEMAT. The present research activity is highly focused on the solution of this problem. (Author)23 refs

Incorporation of fungal cellulases in bacterial minicellulosomes yields viable, synergistically acting celluloytic complexes

NARCIS (Netherlands)

Mingardon, F.; Chanal, A.; Lopez Contreras, A.M.; Dray, C.; Bayer, E.A.; Fierobe, H.P.

2007-01-01

Artificial designer minicellulosomes comprise a chimeric scaffoldin that displays an optional cellulose-binding module (CBM) and bacterial cohesins from divergent species which bind strongly to enzymes engineered to bear complementary dockerins. Incorporation of cellulosomal cellulases from

Electrically conductive cellulose composite

Science.gov (United States)

Evans, Barbara R.; O'Neill, Hugh M.; Woodward, Jonathan

2010-05-04

An electrically conductive cellulose composite includes a cellulose matrix and an electrically conductive carbonaceous material incorporated into the cellulose matrix. The electrical conductivity of the cellulose composite is at least 10 .mu.S/cm at 25.degree. C. The composite can be made by incorporating the electrically conductive carbonaceous material into a culture medium with a cellulose-producing organism, such as Gluconoacetobacter hansenii. The composites can be used to form electrodes, such as for use in membrane electrode assemblies for fuel cells.

Ionic Liquids and Cellulose: Dissolution, Chemical Modification and Preparation of New Cellulosic Materials

Directory of Open Access Journals (Sweden)

Mehmet Isik

2014-07-01

Full Text Available Due to its abundance and a wide range of beneficial physical and chemical properties, cellulose has become very popular in order to produce materials for various applications. This review summarizes the recent advances in the development of new cellulose materials and technologies using ionic liquids. Dissolution of cellulose in ionic liquids has been used to develop new processing technologies, cellulose functionalization methods and new cellulose materials including blends, composites, fibers and ion gels.

Synthesis, Antibacterial and Thermal Studies of Cellulose Nanocrystal Stabilized ZnO-Ag Heterostructure Nanoparticles

Directory of Open Access Journals (Sweden)

Mohd Zobir Hussein

2013-05-01

Full Text Available Synthesis of ZnO-Ag heterostructure nanoparticles was carried out by a precipitation method with cellulose nanocrystals (CNCs as a stabilizer for antimicrobial and thermal studies. ZnO-Ag nanoparticles were obtained from various weight percentages of added AgNO3 relative to Zn precursors for evaluating the best composition with enhanced functional properties. The ZnO-Ag/CNCs samples were characterized systematically by TEM, XRD, UV, TGA and DTG. From the TEM studies we observed that ZnO-Ag heterostructure nanoparticles have spherical shapes with size diameters in a 9–35 nm range. The antibacterial activities of samples were assessed against the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The CNC-stabilized ZnO-Ag exhibited greater bactericidal activity compared to cellulose-free ZnO-Ag heterostructure nanoparticles of the same particle size. The incorporation of ZnO-Ag hetreostructure nanoparticles significantly increased the thermal stability of cellulose nanocrystals.

Nanomaterials from bacterial cellulose for antimicrobial wound dressing

Science.gov (United States)

Liyaskina, E.; Revin, V.; Paramonova, E.; Nazarkina, M.; Pestov, N.; Revina, N.; Kolesnikova, S.

2017-01-01

Bacterial nanocellulose (BNC) is widely used in biomedical applications. BNC has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity. To get over this problem in the present study the BNC was saturated with antibiotic fusidic acid (FA). The subject of the experiment was BNC, produced by bacteria Gluconacetobacter sucrofermentans B-11267. The resulting biocomposites have high antibiotic activity against Staphylococcus aureus and can be used in medicine as a wound dressing. The structure of BNC was analyzed by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR).

Analysis of IV characteristics of solar cells made of hydrogenated amorphous, polymorphous and microcrystalline silicon

International Nuclear Information System (INIS)

Hamadeh, H.

2009-03-01

The IV characteristics of pin solar cells made of amorphous, polymorphous and microcrystalline silicon were investigated. The temperature dependence was measured in the temperature range between 150 K and 395 K. This range covers the most terrestrial applications condition. Using simplex procedure, the IV parameter of the cells were deduce using line fitting. It has been shown that polymorphous silicon shows electrical properties that are close to properties of microcrystalline silicon but as it is well known, polymorphous silicon shows higher absorption similar to amorphous silicon. The polymorphous silicon solar cells showed higher efficiencies, lower shunting and higher filling factors. In the above mentioned temperature range, polymorphous silicon is the better material for the manufacturing of thin film hydrogenated silicon pin solar cells. More investigations concerning the structural properties are necessary to make stronger conclusions in regards to the stability of the material, what we hope to do in the future. (author)

Fabrication of polyaniline/carboxymethyl cellulose/cellulose nanofibrous mats and their biosensing application

International Nuclear Information System (INIS)

Fu, Jiapeng; Pang, Zengyuan; Yang, Jie; Huang, Fenglin; Cai, Yibing; Wei, Qufu

2015-01-01

Graphical abstract: - Highlights: • PANI nanorods have been grown onto the surface of CMC/cellulose nanofibers for the fabrication of biosensor substrate material. • The proposed laccase biosensor exhibited a low detection limit and high sensitivity in the detection of catechol. • Hierarchical PANI/CMC/cellulose nanofibers are the promising material in the design of high-efficient biosensors. - Abstract: We report a facile approach to synthesizing and immobilizing polyaniline nanorods onto carboxymethyl cellulose (CMC)-modified cellulose nanofibers for their biosensing application. Firstly, the hierarchical PANI/CMC/cellulose nanofibers were fabricated by in situ polymerization of aniline on the CMC-modified cellulose nanofiber. Subsequently, the PANI/CMC/cellulose nanofibrous mat modified with laccase (Lac) was used as biosensor substrate material for the detection of catechol. PANI/CMC/cellulose nanofibers with highly conductive and three dimensional nanostructure were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimum conditions, the Lac/PANI/CMC/cellulose/glassy carbon electrode (GCE) exhibited a fast response time (within 8 s), a linear response range from 0.497 μM to 2.27 mM with a high sensitivity and low detection limit of 0.374 μM (3σ). The developed biosensor also displayed good repeatability, reproducibility as well as selectivity. The results indicated that the composite mat has potential application in enzyme biosensors

Fabrication of polyaniline/carboxymethyl cellulose/cellulose nanofibrous mats and their biosensing application

Energy Technology Data Exchange (ETDEWEB)

Fu, Jiapeng, E-mail: firgexiao@sina.cn; Pang, Zengyuan, E-mail: pangzengyuan1212@163.com; Yang, Jie, E-mail: young1993@126.com; Huang, Fenglin, E-mail: flhuang@jiangnan.edu.cn; Cai, Yibing, E-mail: yibingcai@jiangnan.edu.cn; Wei, Qufu, E-mail: qfwei@jiangnan.edu.cn

2015-09-15

Graphical abstract: - Highlights: • PANI nanorods have been grown onto the surface of CMC/cellulose nanofibers for the fabrication of biosensor substrate material. • The proposed laccase biosensor exhibited a low detection limit and high sensitivity in the detection of catechol. • Hierarchical PANI/CMC/cellulose nanofibers are the promising material in the design of high-efficient biosensors. - Abstract: We report a facile approach to synthesizing and immobilizing polyaniline nanorods onto carboxymethyl cellulose (CMC)-modified cellulose nanofibers for their biosensing application. Firstly, the hierarchical PANI/CMC/cellulose nanofibers were fabricated by in situ polymerization of aniline on the CMC-modified cellulose nanofiber. Subsequently, the PANI/CMC/cellulose nanofibrous mat modified with laccase (Lac) was used as biosensor substrate material for the detection of catechol. PANI/CMC/cellulose nanofibers with highly conductive and three dimensional nanostructure were characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM), Fourier transform infrared spectra (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimum conditions, the Lac/PANI/CMC/cellulose/glassy carbon electrode (GCE) exhibited a fast response time (within 8 s), a linear response range from 0.497 μM to 2.27 mM with a high sensitivity and low detection limit of 0.374 μM (3σ). The developed biosensor also displayed good repeatability, reproducibility as well as selectivity. The results indicated that the composite mat has potential application in enzyme biosensors.

High Dehumidification Performance of Amorphous Cellulose Composite Membranes prepared from Trimethylsilyl Cellulose

KAUST Repository

Puspasari, Tiara

2018-04-11

Cellulose is widely regarded as an environmentally friendly, natural and low cost material which can significantly contribute the sustainable economic growth. In this study, cellulose composite membranes were prepared via regeneration of trimethylsilyl cellulose (TMSC), an easily synthesized cellulose derivative. The amorphous hydrophilic feature of the regenerated cellulose enabled fast permeation of water vapour. The pore-free cellulose layer thickness was adjustable by the initial TMSC concentration and acted as an efficient gas barrier. As a result, a 5,000 GPU water vapour transmission rate (WVTR) at the highest ideal selectivity of 1.1 x 106 was achieved by the membranes spin coated from a 7% (w/w) TMSC solution. The membranes maintained a 4,000 GPU WVTR with selectivity of 1.1 x 104 in the mixed-gas experiments, surpassing the performances of the previously reported composite membranes. This study provides a simple way to not only produce high performance membranes but also to advance cellulose as a low-cost and sustainable membrane material for dehumidification applications.

Oyeniyi and Achor (9)

African Journals Online (AJOL)

Timothy Ademakinwa

Keywords: Microcrystalline Cellulose, Drying Techniques, Flow Properties, Compressional ... starches (Esezobo et al.,1982; Alebiowu and Itiola, .... The tablets were thereafter stored over silica gel in .... Sweet Potato and Cocoyam Starches as.

Degradation of γ-irradiated cellulose by the accumulating culture of a cellulose bacterium

International Nuclear Information System (INIS)

Namsaraev, B.B.; Kuznetsova, E.A.; Termkhitarova, N.G.

1987-01-01

Possibility of degradation of γ-irradiated cellulose by the accumulating culture of an anaerobic cellulose bacterium has been investigated. Cellulose irradiation by γ-quanta (Co 60 ) has been carried out using the RKh-30 device with 35.9 Gy/min dose rate. Radiation monitoring has been carried out by the standard ferrosulfate method. Samples have been irradiated in dry state or when water presenting with MGy. It is detected that the accumulating culture with the growth on the irradiated cellulose has a lag-phase, which duration reduces when the cellulose cleaning by flushing with distillation water. The culture has higher growth and substrate consumption rate when growing by cellulose irradiated in comparison with non-irradiated one. The economical coefficient is the same in using both the irradiated and non-irradiated cellulose. The quantity of forming reducing saccharides, organic acids, methane and carbon dioxide is the same both when cultivating by irradiated cellulose and by non-irradiated. pH of the culture liquid is shifted to the acid nature in the process of growth

Bacterial Cellulose Shifts Transcriptome and Proteome of Cultured Endothelial Cells Towards Native Differentiation.

Science.gov (United States)

Feil, Gerhard; Horres, Ralf; Schulte, Julia; Mack, Andreas F; Petzoldt, Svenja; Arnold, Caroline; Meng, Chen; Jost, Lukas; Boxleitner, Jochen; Kiessling-Wolf, Nicole; Serbest, Ender; Helm, Dominic; Kuster, Bernhard; Hartmann, Isabel; Korff, Thomas; Hahne, Hannes

2017-09-01

Preserving the native phenotype of primary cells in vitro is a complex challenge. Recently, hydrogel-based cellular matrices have evolved as alternatives to conventional cell culture techniques. We developed a bacterial cellulose-based aqueous gel-like biomaterial, dubbed Xellulin, which mimics a cellular microenvironment and seems to maintain the native phenotype of cultured and primary cells. When applied to human umbilical vein endothelial cells (HUVEC), it allowed the continuous cultivation of cell monolayers for more than one year without degradation or dedifferentiation. To investigate the impact of Xellulin on the endothelial cell phenotype in detail, we applied quantitative transcriptomics and proteomics and compared the molecular makeup of native HUVEC, HUVEC on collagen-coated Xellulin and collagen-coated cell culture plastic (polystyrene).Statistical analysis of 12,475 transcripts and 7831 proteins unveiled massive quantitative differences of the compared transcriptomes and proteomes. K -means clustering followed by network analysis showed that HUVEC on plastic upregulate transcripts and proteins controlling proliferation, cell cycle and protein biosynthesis. In contrast, HUVEC on Xellulin maintained, by and large, the expression levels of genes supporting their native biological functions and signaling networks such as integrin, receptor tyrosine kinase MAP/ERK and PI3K signaling pathways, while decreasing the expression of proliferation associated proteins. Moreover, CD34-an endothelial cell differentiation marker usually lost early during cell culture - was re-expressed within 2 weeks on Xellulin but not on plastic. And HUVEC on Xellulin showed a significantly stronger functional responsiveness to a prototypic pro-inflammatory stimulus than HUVEC on plastic.Taken together, this is one of the most comprehensive transcriptomic and proteomic studies of native and propagated HUVEC, which underscores the importance of the morphology of the cellular

Liquid crystalline solutions of cellulose in phosphoric acid for preparing cellulose yarns

NARCIS (Netherlands)

Boerstoel, H.

2006-01-01

The presen thesis describes a new process for manufacturing high tenacity and high modulus cellulose yarns. A new direct solvent for cellulose has been discovered, leading to liquid crystalline solutions. This new solvent, superphosphoric acid, rapidly dissolves cellulose. These liquid crystalline

Hydrolysis of cellulose and oil palm empty fruit bunches by using consortia of fungi isolated from the soil of Colombian high andean forest

Directory of Open Access Journals (Sweden)

Luz Aida Moya A

2012-09-01

Full Text Available Hydrolytic activity was evaluated in a mixture of supernatants produced by filamentous fungi grown individually on microcrystalline cellulose and empty fruit bunches. The strains that were used correspond to two types of isolates; the first was made from soil samples from a transect of a high andean forest of Colombia, in the Parque Natural Nacional de Los Nevados, where, based on previous studies, we selected the strains B7, B11, B11M and B19. The second isolate was obtained from a pool of oil palm empty fruit bunches (Eleaeis guinensis Jacq. in different states of decomposition on the Unipalma plantation located in the eastern plains; strains TA1 and TA2. To perform the hydrolysis of cellulose and empty fruit bunches, the previously obtained supernatants from each of the selected strains were cultivated for 300 hours in cellulose and characterized individually by endoglucanase, exoglucanase, and β-glucosidase activity. Individual supernatants were mixed at a 1:1 ratio to form consortia; and hydrolytic activity was evaluated in the substrates at two hours. The glucose concentration was determined by the 3,5-dinitrosalicylic acid (DNS method. The results show that hydrolysis of empty fruit bunch to glucose was favored by three pools of supernatants, with increases greater than 400% in comparison with the hydrolysis obtained by individual supernatants, demonstrating the potential to decompose palm empty fruit bunches; thereby contributing to the reduction of decay time of empty fruit bunches and the decrease of environmental and health problems

Fenton chemistry-based detemplation of an industrially relevant microcrystalline beta zeolite. Optimization and scaling-up studies

NARCIS (Netherlands)

Ortiz-Iniesta, Maria Jesus; Melian-Cabrera, Ignacio

A mild template removal of microcrystalline beta zeolite, based on Fenton chemistry, was optimized. Fenton detemplation was studied in terms of applicability conditions window, reaction rate and scale up. TGA and CHN elemental analysis were used to evaluate the detemplation effectiveness, while 'CP,

Chain scission and anti fungal effect of electron beam on cellulose membrane

International Nuclear Information System (INIS)

Wanichapichart, Pikul; Taweepreeda, Wirach; Nawae, Safitree; Choomgan, Pastraporn; Yasenchak, Dan

2012-01-01

Two types of bacterial cellulose (BC) membranes were produced under a modified H and S medium using sucrose as a carbon source, with (CCB) and without (SHB) coconut juice supplement. Both membranes showed similar crystallinity of 69.24 and 71.55%. After being irradiated with E-beams under oxygen limited and ambient condition, the results from water contact angle showed that only the irradiated membrane CCB was increased from 30 to 40 degrees, and irradiation under oxygen ambient condition provided the greatest value. Comparing with the control membranes, smaller water flux was the cases after electron beam irradiation which indicated a reduction of membrane pore area. However, the results from molecular weight cut off (MWCO) revealed that chain scission was greater for membrane SHB and its cut off was increased from 28,000 Da to more than 35,000 Da. FTIR analysis revealed some changes in membrane functional groups, corresponding with the above results. These changes initiated new property of cellulose membranes, an anti-fungal food wrap. - Highlights: ► Electron beam irradiation increased membrane hydrophobicity and molecular weight cut off. ► The irradiation caused chain scissoring and anti fungal property of cellulose membrane. ► FT-IR studies revealed changes in functional groups causing a decrease in membrane moisture. ► Anti fungal test of cellulose membrane showed the same shelf life as polyethylene sheet.

Nanomaterials from bacterial cellulose for antimicrobial wound dressing

International Nuclear Information System (INIS)

Liyaskina, E; Revin, V; Paramonova, E; Nazarkina, M; Pestov, N; Revina, N; Kolesnikova, S

2017-01-01

Bacterial nanocellulose (BNC) is widely used in biomedical applications. BNC has attracted increasing attention as a novel wound dressing material, but it has no antimicrobial activity. To get over this problem in the present study the BNC was saturated with antibiotic fusidic acid (FA). The subject of the experiment was BNC, produced by bacteria Gluconacetobacter sucrofermentans B-11267. The resulting biocomposites have high antibiotic activity against Staphylococcus aureus and can be used in medicine as a wound dressing. The structure of BNC was analyzed by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). (paper)

Influence of Different Lignocellulose Sources on Endo-1,4-β-Glucanase Gene Expression and Enzymatic Activity of Bacillus amyloliquefaciens B31C

Directory of Open Access Journals (Sweden)

Rosangela Di Pasqua

2014-01-01

Full Text Available Conversion of cellulose into fermentable sugars for ethanol production is currently performed by enzymatic hydrolysis catalyzed by cellulases. The cellulases are produced by a wide variety of microorganisms, playing a major role in the recycling of biomass. The endo-1,4-β-glucanase (CelB31C from Bacillus amyloliquefaciens B31C, isolated from compost and previously selected on the basis of highest cellulase activity levels among Bacillus isolated, was characterized as being a potential candidate for a biocatalyst in lignocellulose conversion for second-generation bioethanol production. The aim of this work was to evaluate the changes in production of enzymatic activity of the endo-1,4-β-glucanase (CelB31C and the expression of its gene (bglC using a carboxymethylcellulase activity assay and qRT-PCR analysis, respectively, during growth of B. amyloliquefaciens B31C on different cellulose sources: carboxymethylcellulose (CMC, pure cellulose from Arundo donax, pretreated Arundo donax biomass (Chemtex, and microcrystalline cellulose (Avicel. The results showed that both the expression of bglC gene and the enzymatic activity production are related to the type of cellulose source. The strain showed a high enzymatic activity on lignocellulosic biomass and on microcrystalline cellulose. Furthermore, the highest gene expression occurred during the exponential phase of growth, except in the presence of Avicel.

Recent Strategies in Preparation of Cellulose Nanocrystals and Cellulose Nanofibrils Derived from Raw Cellulose Materials

Directory of Open Access Journals (Sweden)

Hongxiang Xie

2018-01-01

Full Text Available The recent strategies in preparation of cellulose nanocrystals (CNCs and cellulose nanofibrils (CNFs were described. CNCs and CNFs are two types of nanocelluloses (NCs, and they possess various superior properties, such as large specific surface area, high tensile strength and stiffness, low density, and low thermal expansion coefficient. Due to various applications in biomedical engineering, food, sensor, packaging, and so on, there are many studies conducted on CNCs and CNFs. In this review, various methods of preparation of CNCs and CNFs are summarized, including mechanical, chemical, and biological methods. The methods of pretreatment of cellulose are described in view of the benefits to fibrillation.

Versatile High-Performance Regenerated Cellulose Membranes Prepared using Trimethylsilyl Cellulose as a Precursor

KAUST Repository

Puspasari, Tiara

2018-01-01

(TMSC), a highly soluble cellulose derivative, as a precursor for the fabrication of cellulose thin film composite membranes. TMSC is an attractive precursor to assemble thin cellulose films with good deposition behavior and film morphology; cumbersome

Synthesis, Characterization, and Antimicrobial Efficacy of Photomicrobicidal Cellulose Paper.

Science.gov (United States)

Carpenter, Bradley L; Scholle, Frank; Sadeghifar, Hasan; Francis, Aaron J; Boltersdorf, Jonathan; Weare, Walter W; Argyropoulos, Dimitris S; Maggard, Paul A; Ghiladi, Reza A

2015-08-10

Toward our goal of scalable, antimicrobial materials based on photodynamic inactivation, paper sheets comprised of photosensitizer-conjugated cellulose fibers were prepared using porphyrin and BODIPY photosensitizers, and characterized by spectroscopic (infrared, UV-vis diffuse reflectance, inductively coupled plasma optical emission) and physical (gel permeation chromatography, elemental, and thermal gravimetric analyses) methods. Antibacterial efficacy was evaluated against Staphylococcus aureus (ATCC-2913), vancomycin-resistant Enterococcus faecium (ATCC-2320), Acinetobacter baumannii (ATCC-19606), Pseudomonas aeruginosa (ATCC-9027), and Klebsiella pneumoniae (ATCC-2146). Our best results were achieved with a cationic porphyrin-paper conjugate, Por((+))-paper, with inactivation upon illumination (30 min, 65 ± 5 mW/cm(2), 400-700 nm) of all bacterial strains studied by 99.99+% (4 log units), regardless of taxonomic classification. Por((+))-paper also inactivated dengue-1 virus (>99.995%), influenza A (∼ 99.5%), and human adenovirus-5 (∼ 99%). These results demonstrate the potential of cellulose materials to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action.

Drug-loaded Cellulose Acetate and Cellulose Acetate Butyrate Films ...

African Journals Online (AJOL)

The purpose of this research work was to evaluate the contribution of formulation variables on release properties of matrix type ocular films containing chloramphenicol as a model drug. This study investigated the use of cellulose acetate and cellulose acetate butyrate as film-forming agents in development of ocular films.

Development of Doped Microcrystalline Silicon Oxide and its Application to Thin‑Film Silicon Solar Cells

NARCIS (Netherlands)

Lambertz, A.

2015-01-01

The aim of the present study is the development of doped microcrystalline silicon oxide (µc‑SiOx:H) alloys and its application in thin‑film silicon solar cells. The doped µc‑SiOx:H material was prepared from carbon dioxide (CO2), silane (SiH4), hydrogen (H2) gas mixtures using plasma enhanced

Strongly Enhanced Free-Exciton Luminescence in Microcrystalline CsPbBr3 Films

Science.gov (United States)

Kondo, Shin-ichi; Kakuchi, Mitsugu; Masaki, Atsushi; Saito, Tadaaki

2003-07-01

The luminescence properties of CsPbBr3 films prepared via the amorphous phase by crystallization are dominated by free-exciton emission, and only a weak trace of emission due to trapped excitons was observed, in contrast to the case of bulk CsPbBr3 crystals. In particular, the films in the microcrystalline state show by more than an order of magnitude stronger free-exciton emission than in the polycrystalline state. The enhanced free-exciton emission is suggestive of excitonic superradiance.

Implications of cellobiohydrolase glycosylation for use in biomass conversion

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Decker Stephen R

2008-05-01

Full Text Available Abstract The cellulase producing ascomycete, Trichoderma reesei (Hypocrea jecorina, is known to secrete a range of enzymes important for ethanol production from lignocellulosic biomass. It is also widely used for the commercial scale production of industrial enzymes because of its ability to produce high titers of heterologous proteins. During the secretion process, a number of post-translational events can occur, however, that impact protein function and stability. Another ascomycete, Aspergillus niger var. awamori, is also known to produce large quantities of heterologous proteins for industry. In this study, T. reesei Cel7A, a cellobiohydrolase, was expressed in A. niger var. awamori and subjected to detailed biophysical characterization. The purified recombinant enzyme contains six times the amount of N-linked glycan than the enzyme purified from a commercial T. reesei enzyme preparation. The activities of the two enzyme forms were compared using bacterial (microcrystalline and phosphoric acid swollen (amorphous cellulose as substrates. This comparison suggested that the increased level of N-glycosylation of the recombinant Cel7A (rCel7A resulted in reduced activity and increased non-productive binding on cellulose. When treated with the N-glycosidase PNGaseF, the molecular weight of the recombinant enzyme approached that of the commercial enzyme and the activity on cellulose was improved.

Effect of silane/hydrogen ratio on microcrystalline silicon thin films by remote inductively coupled plasma

Science.gov (United States)

Guo, Y. N.; Wei, D. Y.; Xiao, S. Q.; Huang, S. Y.; Zhou, H. P.; Xu, S.

2013-05-01

Hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared by remote low frequency inductively coupled plasma (ICP) chemical vapor deposition system, and the effect of silane/hydrogen ratio on the microstructure and electrical properties of μc-Si:H films was systematically investigated. As silane/hydrogen ratio increases, the crystalline volume fraction Fc decreases and the ratio of the intensity of (220) peak to that of (111) peak drops as silane flow rate is increased. The FTIR result indicates that the μc-Si:H films prepared by remote ICP have a high optical response with a low hydrogen content, which is in favor of reducing light-induced degradation effect. Furthermore, the processing window of the phase transition region for remote ICP is much wider than that for typical ICP. The photosensitivity of μc-Si:H films can exceed 100 at the transition region and this ensures the possibility of the fabrication of microcrystalline silicon thin film solar cells with a open-circuit voltage of about 700 mV.

From Cellulose Nanospheres, Nanorods to Nanofibers: Various Aspect Ratio Induced Nucleation/Reinforcing Effects on Polylactic Acid for Robust-Barrier Food Packaging.

Science.gov (United States)

Yu, Hou-Yong; Zhang, Heng; Song, Mei-Li; Zhou, Ying; Yao, Juming; Ni, Qing-Qing

2017-12-20

The traditional approach toward improving the crystallization rate as well as the mechanical and barrier properties of poly(lactic acid) (PLA) is the incorporation of nanocelluloses (NCs). Unfortunately, little study has been focused on the influence of the differences in NC morphology and dimensions on the PLA property enhancement. Here, by HCOOH/HCl hydrolysis of lyocell fibers, microcrystalline cellulose (MCC), and ginger fibers, we unveil the preparation of cellulose nanospheres (CNS), rod-like cellulose nanocrystals (CNC), and cellulose nanofibers (CNF) with different aspect ratios, respectively. All the NC surfaces were chemically modified by Fischer esterification with hydrophobic formate groups to improve the NC dispersion in the PLA matrix. This study systematically compared CNS, CNC, and CNF as reinforcing agents to induce different kinds of heterogeneous nucleation and reinforce the effects on the properties of PLA. The incorporation of three NCs can greatly improve the PLA crystallization ability, thermal stability, and mechanical strength of nanocomposites. At the same NC loading level, the PLA/CNS showed the highest crystallinity (19.8 ± 0.4%) with a smaller spherulite size (33 ± 1.5 μm), indicating that CNS, with its high specific surface area, can induce a stronger heterogeneous nucleation effect on the PLA crystallization than CNC or CNF. Instead, compared to PLA, the PLA/CNF nanocomposites gave the largest Young's modulus increase of 350 %, due to the larger aspect ratio/rigidity of CNF and their interlocking or percolation network caused by filler-matrix interfacial bonds. Furthermore, taking these factors of hydrogen bonding interaction, increased crystallinity, and interfacial tortuosity into account, the PLA/CNC nanocomposite films showed the best barrier property against water vapor and lowest migration levels in two liquid food simulates (well below 60 mg kg -1 for required overall migration in packaging) than CNS- and CNF-based films

Investigation of carrier density and mobility in microcrystalline silicon alloys using Hall effect and thermopower measurements; Untersuchung der Ladungstraegerkonzentration und -beweglichkeit in mikrokristallinen Siliziumlegierungen mit Hall-Effekt und Thermokraft

Energy Technology Data Exchange (ETDEWEB)

Sellmer, Christian

2012-08-31

The electronic properties of amorphous and microcrystalline silicon layers in thin-film solar cells significantly affect the efficiency of solar cells. An important property of the individual layer is the electronic transport, which is described by the variables conductivity, photoconductivity, mobility, and carrier concentration. In the past, individual characterization methods were typically used to determine the electronic properties. Using the combination of Hall effect, conductivity, and thermoelectric power measurements additional variables can be derived, such as the effective density of states at the valence and conduction band edge, making a more detailed description of the material possible. To systematically study the electronic properties - in particular carrier mobility and carrier concentration - various series of silicon films are prepared for this work including microcrystalline silicon layers of different doping and crystallinity and a series of silicon films where the Fermi level is moved by irradiation with high energy electrons on one and the same sample. The results show that the transition from amorphous to microcrystalline transport is relatively abrupt. If the electron transport takes place in only amorphous regions, it is marked by the sign anomaly of the Hall effect. If a continuous crystalline path exists, the electronic properties are dominated by the crystalline volume fraction. The results of the measurements of silicon layers are compared with those of microcrystalline silicon carbide samples. Silicon carbide is especially interesting for future applications in thin-film solar cells due to high transparency and high conductivity. It is shown that the effective density of states at the valence and conduction band edge as a function of temperature in p- and n-type microcrystalline silicon and silicon carbide samples largely coincide with those of crystalline silicon or silicon carbide. A square root shaped profile of the density of

Brittle Culm1, a COBRA-Like Protein, Functions in Cellulose Assembly through Binding Cellulose Microfibrils

Science.gov (United States)

Zhang, Baocai; Liu, Xiangling; Yan, Meixian; Zhang, Lanjun; Shi, Yanyun; Zhang, Mu; Qian, Qian; Li, Jiayang; Zhou, Yihua

2013-01-01

Cellulose represents the most abundant biopolymer in nature and has great economic importance. Cellulose chains pack laterally into crystalline forms, stacking into a complicated crystallographic structure. However, the mechanism of cellulose crystallization is poorly understood. Here, via functional characterization, we report that Brittle Culm1 (BC1), a COBRA-like protein in rice, modifies cellulose crystallinity. BC1 was demonstrated to be a glycosylphosphatidylinositol (GPI) anchored protein and can be released into cell walls by removal of the GPI anchor. BC1 possesses a carbohydrate-binding module (CBM) at its N-terminus. In vitro binding assays showed that this CBM interacts specifically with crystalline cellulose, and several aromatic residues in this domain are essential for binding. It was further demonstrated that cell wall-localized BC1 via the CBM and GPI anchor is one functional form of BC1. X-ray diffraction (XRD) assays revealed that mutations in BC1 and knockdown of BC1 expression decrease the crystallite width of cellulose; overexpression of BC1 and the CBM-mutated BC1s caused varied crystallinity with results that were consistent with the in vitro binding assay. Moreover, interaction between the CBM and cellulose microfibrils was largely repressed when the cell wall residues were pre-stained with two cellulose dyes. Treating wild-type and bc1 seedlings with the dyes resulted in insensitive root growth responses in bc1 plants. Combined with the evidence that BC1 and three secondary wall cellulose synthases (CESAs) function in different steps of cellulose production as revealed by genetic analysis, we conclude that BC1 modulates cellulose assembly by interacting with cellulose and affecting microfibril crystallinity. PMID:23990797

Brittle Culm1, a COBRA-like protein, functions in cellulose assembly through binding cellulose microfibrils.

Directory of Open Access Journals (Sweden)

Lifeng Liu

Full Text Available Cellulose represents the most abundant biopolymer in nature and has great economic importance. Cellulose chains pack laterally into crystalline forms, stacking into a complicated crystallographic structure. However, the mechanism of cellulose crystallization is poorly understood. Here, via functional characterization, we report that Brittle Culm1 (BC1, a COBRA-like protein in rice, modifies cellulose crystallinity. BC1 was demonstrated to be a glycosylphosphatidylinositol (GPI anchored protein and can be released into cell walls by removal of the GPI anchor. BC1 possesses a carbohydrate-binding module (CBM at its N-terminus. In vitro binding assays showed that this CBM interacts specifically with crystalline cellulose, and several aromatic residues in this domain are essential for binding. It was further demonstrated that cell wall-localized BC1 via the CBM and GPI anchor is one functional form of BC1. X-ray diffraction (XRD assays revealed that mutations in BC1 and knockdown of BC1 expression decrease the crystallite width of cellulose; overexpression of BC1 and the CBM-mutated BC1s caused varied crystallinity with results that were consistent with the in vitro binding assay. Moreover, interaction between the CBM and cellulose microfibrils was largely repressed when the cell wall residues were pre-stained with two cellulose dyes. Treating wild-type and bc1 seedlings with the dyes resulted in insensitive root growth responses in bc1 plants. Combined with the evidence that BC1 and three secondary wall cellulose synthases (CESAs function in different steps of cellulose production as revealed by genetic analysis, we conclude that BC1 modulates cellulose assembly by interacting with cellulose and affecting microfibril crystallinity.

Brittle Culm1, a COBRA-like protein, functions in cellulose assembly through binding cellulose microfibrils.

Science.gov (United States)

Liu, Lifeng; Shang-Guan, Keke; Zhang, Baocai; Liu, Xiangling; Yan, Meixian; Zhang, Lanjun; Shi, Yanyun; Zhang, Mu; Qian, Qian; Li, Jiayang; Zhou, Yihua

2013-01-01

Cellulose represents the most abundant biopolymer in nature and has great economic importance. Cellulose chains pack laterally into crystalline forms, stacking into a complicated crystallographic structure. However, the mechanism of cellulose crystallization is poorly understood. Here, via functional characterization, we report that Brittle Culm1 (BC1), a COBRA-like protein in rice, modifies cellulose crystallinity. BC1 was demonstrated to be a glycosylphosphatidylinositol (GPI) anchored protein and can be released into cell walls by removal of the GPI anchor. BC1 possesses a carbohydrate-binding module (CBM) at its N-terminus. In vitro binding assays showed that this CBM interacts specifically with crystalline cellulose, and several aromatic residues in this domain are essential for binding. It was further demonstrated that cell wall-localized BC1 via the CBM and GPI anchor is one functional form of BC1. X-ray diffraction (XRD) assays revealed that mutations in BC1 and knockdown of BC1 expression decrease the crystallite width of cellulose; overexpression of BC1 and the CBM-mutated BC1s caused varied crystallinity with results that were consistent with the in vitro binding assay. Moreover, interaction between the CBM and cellulose microfibrils was largely repressed when the cell wall residues were pre-stained with two cellulose dyes. Treating wild-type and bc1 seedlings with the dyes resulted in insensitive root growth responses in bc1 plants. Combined with the evidence that BC1 and three secondary wall cellulose synthases (CESAs) function in different steps of cellulose production as revealed by genetic analysis, we conclude that BC1 modulates cellulose assembly by interacting with cellulose and affecting microfibril crystallinity.

The magnetic properties of powdered and compacted microcrystalline permalloy

International Nuclear Information System (INIS)

Kollar, P.; Oleksakova, D.; Fuezer, J.; Kovac, J.; Roth, S.; Polanski, K.

2007-01-01

The aim of this work is to investigate the magnetic properties of powdered and compacted microcrystalline Ni-Fe (81 wt% of Ni) permalloy. It was found by investigating the influence of mechanical milling on the magnetic properties of powder samples prepared by milling of the ribbon that the alloy remains a solid solution with stable structure during the whole milling process. With decreasing particle size the rotation of magnetization vector gradually becomes dominant magnetization process and thus coercivity increases. After compaction of the powder by uniaxial hot pressing the magnetic contact between powder particles is recreated and for resulting bulk the displacement of the domain walls becomes dominant magnetization process with coercivity of 11 A/m (comparable with the coercivity of conventional permalloy)

Preliminary studies of the development of a direct compression cellulose excipient from bagasse.

Science.gov (United States)

Padmadisastra, Y; Gonda, I

1989-06-01

Bagasse is an unused by-product in cane sugar manufacture. Bagasse from sugar cane manually harvested in Indonesia was transformed to pulp by mechanical means and repeated autoclaving in 1.4% NaOH. It was then subjected to cycles of bleaching with hypochlorite and acid hydrolysis with 2.5 M HCl to produce 'microcrystalline' cellulose (MCC). Extraction of waxes by petroleum ether was necessary in order to improve the disintegration properties of tablets made from this material, DICEB III. When the bagasse-derived cellulose was reconstituted by recombining different proportions of selected sieve cuts to have a similar sieve size distribution as the commercially available MCC, Avicel PH102, it was found that the latter and DICEB III also had similar crystallinity as measured by X-ray powder diffraction (degree of crystallinity 2.8 +/- 0.2). The crystallinity and flow index were also relatively insensitive to most of the changes in the manufacturing procedure, indicating that the production process was quite robust. Directly compressed tablets were made containing 50 mg of caffeine and 500 mg of either Avicel PH102 or DICEB III to approximately the same hardness (11.6 +/- 1.1 and 13.7 +/- 0.5 kPa, respectively). They displayed similar satisfactory disintegration and dissolution behavior. However, DICEB III required greater compaction pressures than Avicel PH102, perhaps because the former was not spray dried to give spherical agglomerates of particles of uniform size as the commercial product. Rather, DICEB III consisted mainly of single irregular particles. Further work is required to improve the new excipient and to explore if the bagasse from mechanically harvested sugar cane (often contaminated by soil) could also be used for production of MCC.

Molecular cloning of cellulase genes from indigenous bacterial isolates

International Nuclear Information System (INIS)

Jong Bor Chyan; Pauline Liew Woan Ying; Mat Rasol Awang

2006-01-01

Indigenous cellulolytic bacterial isolates having high activities in degrading carboxymethyl cellulose (CMC) were isolated from local environments. Identification of these isolates were performed by molecular techniques. By using polymerase chain reaction (PCR) techniques, PCR products encoding cellulase gene were amplified from the total genomic DNAs. Purified PCR product was successfully cloned and expressed in Escherichia coli host system. The complete nucleotide sequences of the cellulase genes determined. The analysis of amino acid sequences deduced from the genes indicated that the cloned DNA fragments show high homology to those of endoglucanase genes of family GH5. All cloned genes consist of an N-terminal signal peptide, a catalytic domain of family 5 glycosyl hydrolase and a cellulose-binding domain of family III. (Author)

Homogeneous preparation of cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) from sugarcane bagasse cellulose in ionic liquid.

Science.gov (United States)

Huang, Kelin; Wang, Ben; Cao, Yan; Li, Huiquan; Wang, Jinshu; Lin, Weijiang; Mu, Chaoshi; Liao, Dankui

2011-05-25

Cellulose acetate butyrate (CAB) and cellulose acetate propionate (CAP) were prepared homogeneously in a 1-allyl-3-methylimidazolium chloride (AmimCl) ionic liquid system from sugarcane bagasse (SB). The reaction temperature, reaction time, and molar ratio of butyric (propionic) anhydride/anhydroglucose units in the cellulose affect the butyryl (B) or propionyl (P) content of CAB or CAP samples. The (13)C NMR data revealed the distribution of the substituents of CAB and CAP. The thermal stability of sugar cane bagasse cellulose was found by thermogravimetric analysis to have decreased after chemical modification. After reaction, the ionic liquid was effectively recycled and reused. This study provides a new way for high-value-added utilization of SB and realizing the objective of turning waste into wealth.

Continuous volatile fatty acid production from lignocellulosic biomass by a novel rumen-mimetic bioprocess.

Science.gov (United States)

Agematu, Hitosi; Takahashi, Takehiko; Hamano, Yoshio

2017-11-01

Lignocellulosic biomass is an attractive source of biofuels and biochemicals, being abundant in various plant sources. However, processing this type of biomass requires hydrolysis of cellulose. The proposed rumen-mimetic bioprocess consists of dry-pulverization of lignocellulosic biomass and pH-controlled continuous cultivation of ruminal bacteria using ammonium as a nitrogen source. In this study, ruminal bacteria were continuously cultivated for over 60 days and used to digest microcrystalline cellulose, rice straw, and Japanese cedar to produce volatile fatty acids (VFAs). The ruminal bacteria grew well in the chemically defined medium. The amounts of VFAs produced from 20 g of cellulose, rice straw, and Japanese cedar were 183 ± 29.7, 69.6 ± 12.2, and 21.8 ± 12.9 mmol, respectively. Each digestion completed within 24 h. The carbon yield was 60.6% when 180 mmol of VFAs was produced from 20 g of cellulose. During the cultivation, the bacteria were observed to form flocs that enfolded the feed particles. These flocs likely contain all of the bacterial species necessary to convert lignocellulosic biomass to VFAs and microbial protein symbiotically. Denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rDNA fragments revealed that the bacterial community was relatively stable after 1 week in cultivation, though it was different from the original community structure. Furthermore, sequence analysis of the DGGE bands indicates that the microbial community includes a cellulolytic bacterium, a bacterium acting synergistically with cellulolytic bacteria, and a propionate-producing bacterium, as well as other anaerobic bacteria. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

A co-production of sugars, lignosulfonates, cellulose, and cellulose nanocrystals from ball-milled woods.

Science.gov (United States)

Du, Lanxing; Wang, Jinwu; Zhang, Yang; Qi, Chusheng; Wolcott, Michael P; Yu, Zhiming

2017-08-01

This study demonstrated the technical potential for the large-scale co-production of sugars, lignosulfonates, cellulose, and cellulose nanocrystals. Ball-milled woods with two particle sizes were prepared by ball milling for 80min or 120min (BMW 80 , BMW 120 ) and then enzymatically hydrolyzed. 78.3% cellulose conversion of BMW 120 was achieved, which was three times as high as the conversion of BMW 80 . The hydrolyzed residues (HRs) were neutrally sulfonated cooking. 57.72g/L and 88.16g/L lignosulfonate concentration, respectively, were harvested from HR 80 and HR 120 , and 42.6±0.5% lignin were removed. The subsequent solid residuals were purified to produce cellulose and then this material was acid-hydrolyzed to produce cellulose nanocrystals. The BMW 120 maintained smaller particle size and aspect ratio during each step of during the multiple processes, while the average aspect ratio of its cellulose nanocrystals was larger. The crystallinity of both materials increased with each step of wet processing, reaching to 74% for the cellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of the effect of the structure of bacterial cellulose on full thickness skin wound repair on a microfluidic chip.

Science.gov (United States)

Li, Ying; Wang, Shiwen; Huang, Rong; Huang, Zhuo; Hu, Binfeng; Zheng, Wenfu; Yang, Guang; Jiang, Xingyu

2015-03-09

Bacterial cellulose (BC) is a kind of nanobiomaterial for tissue engineering. How the nanoscale structure of BC affects skin wound repair is unexplored. Here, the hierarchical structure of BC films and their different effects on skin wound healing were studied both in vitro and in vivo. The bottom side of the BC film had a larger pore size, and a looser and rougher structure than that of the top side. By using a microfluidics-based in vitro wound healing model, we revealed that the bottom side of the BC film can better promote the migration of cells to facilitate wound healing. Furthermore, the full-thickness skin wounds on Wistar rats demonstrated that, compared with gauze and the top side of the BC film, the wound covered by the bottom side of the BC film showed faster recovery rate and less inflammatory response. The results indicate that the platform based on the microfluidic chip provide a rapid, reliable, and repeatable method for wound dressing screening. As an excellent biomaterial for wound healing, the BC film displays different properties on different sides, which not only provides a method to optimize the biocompatibility of wound dressings but also paves a new way to building heterogeneous BC-based biomaterials for complex tissue engineering.

Versatile High-Performance Regenerated Cellulose Membranes Prepared using Trimethylsilyl Cellulose as a Precursor

KAUST Repository

Puspasari, Tiara

2018-05-01

Cellulose has emerged as an indispensable membrane material due to its abundant availability, low cost, fascinating physiochemical properties and environment benignancy. However, it is believed that the potential of this polymer is not fully explored yet due to its insolubility in the common organic solvents, encouraging the use of derivatization-regeneration method as a viable alternative to the direct dissolution in exotic or reactive solvents. In this work, we use trimethylsilyl cellulose (TMSC), a highly soluble cellulose derivative, as a precursor for the fabrication of cellulose thin film composite membranes. TMSC is an attractive precursor to assemble thin cellulose films with good deposition behavior and film morphology; cumbersome solvents used in the one step cellulose processing are avoided. This derivative is prepared from cellulose by the known silylation reaction. The complete transformation of TMSC back into cellulose after the membrane formation is carried out by vapor-phase acid treatment, which is simple, scalable and reproducible. This process along with the initial TMSC concentration determines the membrane sieving characteristics. Unlike the typical regenerated cellulose membranes with meso- or macropores, membranes regenerated from TMSC display micropores suitable for the selective separation of nanomolecules in aqueous and organic solvent nanofiltration. The membranes introduced in this thesis represent the first polymeric membranes ever reported for highly selective separation of similarly sized small organic molecules based on charge and size differences with outstanding fluxes. Owing to its strong hydrophilic and amorphous character, the membranes also demonstrate excellent air-dehumidification performance as compared to previously reported thin film composite membranes. Moreover, the use of TMSC enables the creation of the previously unfeasible cellulose–polydimethylsiloxane (PDMS) and cellulose–polyethyleneimine (PEI) blend membranes

Application of scanning Kelvin probe microscopy for the electrical characterization of microcrystalline silicon for photovoltaics

International Nuclear Information System (INIS)

Breymesser, A.

2000-05-01

In the last years microcrystalline silicon thin films have attracted great attention as a new photovoltaic material. With this material it is possible to combine simple and cheap low temperature deposition techniques known from amorphous silicon with the long-term stability of the photovoltaic performance like in bulk crystalline silicon solar cells. The critical point is the deposition procedure with numerous tunable parameters influencing the quality and character of the produced diode structures. Additionally there is a great uncertainty about unintentionally incorporated defects, which is not affected by the deposition parameters. Extended investigation of the material, diode and solar cell characteristics is essential in order to correlate the impact of deposition conditions with the quality of the devices. The situation is complicated due to the anisotropic and inhomogeneous character of microcrystalline silicon. Scanning Kelvin probe microscopy (SKPM) is a work function measurement method based on a scanning force microscope (SFM) and a modified Kelvin probe technique. Due to the excellent lateral resolution of the SFM work function measurements with resolutions far below the micrometer level can be carried out. Applied on doped microcrystalline silicon structures it is possible to visualize the position of the Fermi level within the band gap and the influence of the deposition conditions on it. Within this work a SKPM based on a commercially available SFM was constructed and built. Great effort was concentrated on the characterization of the SKPM experiment. On the basis of an extended knowledge about the performance investigations concentrated on cross sections of microcrystalline silicon diode structures produced by hot-wire chemical vapor deposition (HW-CVD). A pin structure for the diodes was chosen due to the low diffusion lengths within this rather defective material. The evolution of the built-in electric drift field within the intrinsic absorber is

Physicochemical analysis of cellulose from microalgae ...

African Journals Online (AJOL)

USER

2016-06-15

Jun 15, 2016 ... The extraction method of algae cellulose was a modification of ... triplicate. Characterization of cellulose. Analysis of ... The current analysis of the cellulose extracted .... Cellulose nanomaterials review: structure, properties and.

Isolation and Characterization of Two Cellulose Morphology Mutants of Gluconacetobacter hansenii ATCC23769 Producing Cellulose with Lower Crystallinity

Science.gov (United States)

Deng, Ying; Nagachar, Nivedita; Fang, Lin; Luan, Xin; Catchmark, Jeffrey M.; Tien, Ming; Kao, Teh-hui

2015-01-01

Gluconacetobacter hansenii, a Gram-negative bacterium, produces and secrets highly crystalline cellulose into growth medium, and has long been used as a model system for studying cellulose synthesis in higher plants. Cellulose synthesis involves the formation of β-1,4 glucan chains via the polymerization of glucose units by a multi-enzyme cellulose synthase complex (CSC). These glucan chains assemble into ordered structures including crystalline microfibrils. AcsA is the catalytic subunit of the cellulose synthase enzymes in the CSC, and AcsC is required for the secretion of cellulose. However, little is known about other proteins required for the assembly of crystalline cellulose. To address this question, we visually examined cellulose pellicles formed in growth media of 763 individual colonies of G. hansenii generated via Tn5 transposon insertion mutagenesis, and identified 85 that produced cellulose with altered morphologies. X-ray diffraction analysis of these 85 mutants identified two that produced cellulose with significantly lower crystallinity than wild type. The gene disrupted in one of these two mutants encoded a lysine decarboxylase and that in the other encoded an alanine racemase. Solid-state NMR analysis revealed that cellulose produced by these two mutants contained increased amounts of non-crystalline cellulose and monosaccharides associated with non-cellulosic polysaccharides as compared to the wild type. Monosaccharide analysis detected higher percentages of galactose and mannose in cellulose produced by both mutants. Field emission scanning electron microscopy showed that cellulose produced by the mutants was unevenly distributed, with some regions appearing to contain deposition of non-cellulosic polysaccharides; however, the width of the ribbon was comparable to that of normal cellulose. As both lysine decarboxylase and alanine racemase are required for the integrity of peptidoglycan, we propose a model for the role of peptidoglycan in the

Isolation and characterization of two cellulose morphology mutants of Gluconacetobacter hansenii ATCC23769 producing cellulose with lower crystallinity.

Directory of Open Access Journals (Sweden)

Ying Deng

Full Text Available Gluconacetobacter hansenii, a Gram-negative bacterium, produces and secrets highly crystalline cellulose into growth medium, and has long been used as a model system for studying cellulose synthesis in higher plants. Cellulose synthesis involves the formation of β-1,4 glucan chains via the polymerization of glucose units by a multi-enzyme cellulose synthase complex (CSC. These glucan chains assemble into ordered structures including crystalline microfibrils. AcsA is the catalytic subunit of the cellulose synthase enzymes in the CSC, and AcsC is required for the secretion of cellulose. However, little is known about other proteins required for the assembly of crystalline cellulose. To address this question, we visually examined cellulose pellicles formed in growth media of 763 individual colonies of G. hansenii generated via Tn5 transposon insertion mutagenesis, and identified 85 that produced cellulose with altered morphologies. X-ray diffraction analysis of these 85 mutants identified two that produced cellulose with significantly lower crystallinity than wild type. The gene disrupted in one of these two mutants encoded a lysine decarboxylase and that in the other encoded an alanine racemase. Solid-state NMR analysis revealed that cellulose produced by these two mutants contained increased amounts of non-crystalline cellulose and monosaccharides associated with non-cellulosic polysaccharides as compared to the wild type. Monosaccharide analysis detected higher percentages of galactose and mannose in cellulose produced by both mutants. Field emission scanning electron microscopy showed that cellulose produced by the mutants was unevenly distributed, with some regions appearing to contain deposition of non-cellulosic polysaccharides; however, the width of the ribbon was comparable to that of normal cellulose. As both lysine decarboxylase and alanine racemase are required for the integrity of peptidoglycan, we propose a model for the role of