scholarly journals Bacterial Cellulose: Production, Modification and Perspectives in Biomedical Applications

Nanomaterials ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1352 ◽  
Author(s):  
Gorgieva ◽  
Trček
Keyword(s):  
Bacterial Cellulose ◽  
Bone Repair ◽  
High Surface ◽  
Carbon Sources ◽  
High Surface Area ◽  
Young Modulus ◽  
High Water ◽  
Ex Situ ◽  
Bacterial Strains ◽  
High Flexibility

Abstract: Bacterial cellulose (BC) is ultrafine, nanofibrillar material with an exclusive combination of properties such as high crystallinity (84%–89%) and polymerization degree, high surface area (high aspect ratio of fibers with diameter 20–100 nm), high flexibility and tensile strength (Young modulus of 15–18 GPa), high water-holding capacity (over 100 times of its own weight), etc. Due to high purity, i.e. absence of lignin and hemicellulose, BC is considered as a non-cytotoxic, non-genotoxic and highly biocompatible material, attracting interest in diverse areas with hallmarks in medicine. The presented review summarizes the microbial aspects of BC production (bacterial strains, carbon sources and media) and versatile in situ and ex situ methods applied in BC modification, especially towards bionic design for applications in regenerative medicine, from wound healing and artificial skin, blood vessels, coverings in nerve surgery, dura mater prosthesis, arterial stent coating, cartilage and bone repair implants, etc. The paper concludes with challenges and perspectives in light of further translation in highly valuable medical products.

scholarly journals Electrochemically scrambled nanocrystals are catalytically active for CO2-to-multicarbons

2020 ◽  
Vol 117 (17) ◽  
pp. 9194-9201 ◽  
Author(s):  
Yifan Li ◽  
Dohyung Kim ◽  
Sheena Louisia ◽  
Chenlu Xie ◽  
Qiao Kong ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
High Surface ◽  
High Surface Area ◽  
High Mobility ◽  
Ex Situ ◽  
Intrinsic Activity ◽  
Air Exposure ◽  
Disordered Structures ◽  
Catalytically Active

Promotion of C–C bonds is one of the key fundamental questions in the field of CO2 electroreduction. Much progress has occurred in developing bulk-derived Cu-based electrodes for CO2-to-multicarbons (CO2-to-C2+), especially in the widely studied class of high-surface-area “oxide-derived” copper. However, fundamental understanding into the structural characteristics responsible for efficient C–C formation is restricted by the intrinsic activity of these catalysts often being comparable to polycrystalline copper foil. By closely probing a Cu nanoparticle (NP) ensemble catalyst active for CO2-to-C2+, we show that bias-induced rapid fusion or “electrochemical scrambling” of Cu NPs creates disordered structures intrinsically active for low overpotential C2+ formation, exhibiting around sevenfold enhancement in C2+ turnover over crystalline Cu. Integrating ex situ, passivated ex situ, and in situ analyses reveals that the scrambled state exhibits several structural signatures: a distinct transition to single-crystal Cu2O cubes upon air exposure, low crystallinity upon passivation, and high mobility under bias. These findings suggest that disordered copper structures facilitate C–C bond formation from CO2 and that electrochemical nanocrystal scrambling is an avenue toward creating such catalysts.

In Situ and Ex Situ Microscopic Study of Propylene Polymerization With Heterogeneous Mgcl2-Supported Ziegler-Natta Catalysts

2000 ◽  
Vol 6 (S2) ◽  
pp. 33-34
Author(s):  
V. Oleshko ◽  
P. Crozier ◽  
R. Cantrell ◽  
A. Westwood
Keyword(s):  
Large Scale ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
Light And Electron Microscopy ◽  
High Surface Area ◽  
Propylene Polymerization ◽  
Ex Situ ◽  
Co Catalysts ◽  
Ziegler Natta Catalysts

The large-scale commercial production of polyolefins by catalytic Ziegler-Natta polymerization have stimulated the development of the third, fourth and fifth generation heterogeneous catalysts comprising high surface area defective MgCl2 with TiCl4, electron donors, and AlR3-co-catalysts. In spite of intensive research over the years, the present level of understanding of the catalysts is still incomplete because of their complex composition leading to a multitude of local active site environments. The aim of this work is to provide a new insight into the process via in situ video microscopy of gas phase propylene polymerization over MgCl2-supported Ziegler-Natta catalysts combined with ex situ characterization by light and electron microscopy techniques (SEM, TEM, HRTEM, STEM, PEELS and windowless EDX). Procedures for catalyst synthesis are described elsewhere. The catalysts were stored in a dry box under a He atmosphere (<lppm H2O/O2). Samples were transferred to specimen holders in the dry box and then transferred into the microscopes under high purge N2 conditions to prevent poisoning of the catalysts by air and moisture.

scholarly journals SYNTHESIS, CHARACTERIZATION AND ANTIBACTERIAL ACTIVITY OF CUO NANOPARTICLES

2019 ◽  
pp. 17-20 ◽  
Author(s):  
PARDEEP KUMAR ◽  
AJINKYA GIRISH NENE ◽  
SANDEEP PUNIA ◽  
MANOJ KUMAR ◽  
ZAHOOR ABBAS ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Chemical Characterization ◽  
Bacterial Strains ◽  
Cuo Nps ◽  
Bacterial Infectious Disease ◽  
Physico Chemical ◽  
Physical And Chemical ◽  
Near Future

Objective: The present study was done to see the effect of biologically synthesized CuO-NPs (Copperoxide nanoparticles) on the growth of bacterial strains. Methods: Physico-chemical characterization of CuO-NPs was done by UV-Vis-spectrophotometer, XRD, FE-SEM, and EDS. The disc plate diffusion assay was used to evaluate the anti-bacterial effect of CuNPs. Results: This study has shown a promising anti-bacterial activity of biosynthesized CuO-NPs at different concentrations ranging from 10 to 100 µg/ml against Escherichia coli and Staphylococcus aureus bacteria. Conclusion: Nanoparticles (NPs) are small size particles between range 1 to 100 nm which expand their physical and chemical properties due to high surface area. The present study reveals that there may be possible utilization of biosynthesized CuO NPs for the treatment of bacterial infectious disease in near future.

Facile synthesis of high surface area zeolite-templated carbons using divinylbenzene and propylene as carbon sources

2021 ◽  
Vol 326 ◽  
pp. 111378
Author(s):  
Hiroyuki Itoi ◽  
Yuto Kasai ◽  
Keita Morishita ◽  
Ryutaro Suzuki ◽  
Yuka Gotoh ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
Carbon Sources ◽  
High Surface Area ◽  
Facile Synthesis

Ex Situ and In Situ Synthesis and Characterization of Nickel Nanoparticles on High Surface Area Silica Support

2008 ◽  
Vol 14 (S2) ◽  
pp. 282-283 ◽  
Author(s):  
R Banerjee ◽  
PA Crozier
Keyword(s):  
New Mexico ◽  
Nickel Nanoparticles ◽  
High Surface ◽  
High Surface Area ◽  
In Situ Synthesis ◽  
Ex Situ ◽  
Synthesis And Characterization ◽  
Silica Support

Extended abstract of a paper presented at Microscopy and Microanalysis 2008 in Albuquerque, New Mexico, USA, August 3 – August 7, 2008

In situ and ex situ Moessbauer spectroscopy studies of iron phthalocyanine adsorbed on high surface area carbon

1983 ◽  
Vol 87 (6) ◽  
pp. 932-943 ◽  
Author(s):  
D. A. Scherson ◽  
S. B. Yao ◽  
E. B. Yeager ◽  
J. Eldridge ◽  
M. E. Kordesch ◽  
...  
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Ex Situ ◽  
Iron Phthalocyanine ◽  
Moessbauer Spectroscopy ◽  
Spectroscopy Studies

scholarly journals Electrospinning Nanofibres Of Pullulan Extracted From Phylloplane Fungus, Aureobasidium Pullulans

2020 ◽  
Author(s):  
Komal Saraf ◽  
N Vigneshwaran
Keyword(s):  
Surface Area ◽  
Aureobasidium Pullulans ◽  
High Surface ◽  
Polymer Concentration ◽  
Carbon Sources ◽  
High Surface Area ◽  
Angle Measurement ◽  
Electrospinning Process ◽  
Bet Surface Area ◽  
Poly Vinyl Alcohol

Abstract Aureobasidium pullulans isolated from the phylloplane of Peltophorum tree, produced pullulan, an extracellular polysaccharide. It was grown on three different carbon sources, sucrose, wheat bran and cotton stalk dust, for maximizing the pullulan yield. A. pullulans (67.4 gL-1) had the highest yield followed by A. pullulans MTCC 1991 (63.68 gL-1). Pullulan was characterized by X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET) surface area analyzer, DSC and NMR. Electrospinning of pullulan blended with poly (vinyl alcohol) (PVA) produced bead-less nanofibres. The optimized parameters for electrospinning were 25 kV applied voltage, 0.5 mL/h flow rate, 18% polymer concentration (pullulan + PVA) and 150 mm tip-to-collector distance. The pullulan nanofibre was characterized by SEM, AFM, BET, contact angle measurement, DSC and CIE color space analyzer. A maximum surface area of 183.4 m2/g while the minimum nanofibre diameter (79 ± 19 nm by SEM) was obtained for the electrospun mat of commercial pullulan + 40% PVA. This work signifies the importance of pullulan extracted from an isolate of Peltopohorum tree for conversion to high surface area nanofibres by electrospinning process.

scholarly journals Electrospinning Nanofibres of Pullulan Extracted From Phylloplane Fungus, Aureobasidium Pullulans

2020 ◽  
Author(s):  
Komal Saraf ◽  
N Vigneshwaran
Keyword(s):  
Surface Area ◽  
Aureobasidium Pullulans ◽  
High Surface ◽  
Polymer Concentration ◽  
Carbon Sources ◽  
High Surface Area ◽  
Angle Measurement ◽  
Electrospinning Process ◽  
Bet Surface Area ◽  
Poly Vinyl Alcohol

Abstract Aureobasidium pullulans isolated from the phylloplane of Peltophorum tree, produced pullulan, 24 an extracellular polysaccharide. It was grown on three different carbon sources, sucrose, wheat 25 bran and cotton stalk dust, for maximizing the pullulan yield. A. pullulans (67.4 gL-1) had the 26 highest yield followed by A. pullulans MTCC 1991 (63.68 gL-1). Pullulan was characterized by 27 X-ray diffractometer (XRD), Brunauer-Emmett-Teller (BET) surface area analyzer, DSC and NMR. 28 Electrospinning of pullulan blended with poly (vinyl alcohol) (PVA) produced bead-less 29 nanofibres. The optimized parameters for electrospinning were 25 kV applied voltage, 0.5 mL/h 30 flow rate, 18% polymer concentration (pullulan + PVA) and 150 mm tip-to-collector distance. 31 The pullulan nanofibre was characterized by SEM, AFM, BET, contact angle measurement, DSC 32 and CIE color space analyzer. A maximum surface area of 183.4 m2/g while the minimum 33 nanofibre diameter (79 ± 19 nm by SEM) was obtained for the electrospun mat of commercial 34 pullulan + 40% PVA. This work signifies the importance of pullulan extracted from an isolate of 35 Peltopohorum tree for conversion to high surface area nanofibres by electrospinning process.

Synthesis and Characterization of Strontium Cerium Mixed Oxide Nanoparticles Using Plant Extract

2019 ◽  
Vol 17 (12) ◽  
pp. 924-937
Author(s):  
K. Kasirajan ◽  
M. Karunakaran
Keyword(s):  
Ionic Liquid ◽  
Surface Area ◽  
Plant Extract ◽  
Mixed Oxide ◽  
Metal Ion ◽  
High Surface ◽  
High Surface Area ◽  
Octadecenoic Acid ◽  
Band Gap Energy ◽  
Bacterial Strains

Green synthesis of nanomaterials is an emphasis of recent developments. Herein, a facile and eco-friendly method for the synthesis of SrO–CeO2 mixed oxide NPs using ionic liquid (IL) assisted an ethanolic solution of Pedalium murex (PM) plant extract. NPs synthesized at room temperature using an ionic liquid (IL) as a mediator for the nucleation and growth process. SrO–CeO2 mixed oxide NPs system displaying nano rod like structure with 10–15 nm and high surface area that are confirmed by XRD, and SEM studies. GC-MS spectroscopy confirms the presence of N-Hexadecanoic acid (29%), 6-Octadecenoic acid, (Z) present in the plant extract that are capable to convert the corresponding metal ion precursor to SrO–CeO2 mixed oxide NPs. In FTIR the Ce–O and SrCO3 stretching bands were observed at 451 and 856 cm–1 respectively. Raman spectroscopy give stretching frequency at 457 and 159 cm–1 that proofs the presence of CeO2 and SrO present in the mixed oxide. The band gap energy of the SrO–CeO2 mixed oxide NPs was estimated as 3.17 eV from the UV-DRS spectroscopy. The anti-bacterial studies performed against a set of bacterial strains the result showed that SrO–CeO2 mixed oxide NPs more susceptible for gram negative (G–) bacteria then gram positive (G+) bacteria. A unique feature of the antioxidant behavior of NPs reduces the concentration of DPPH radical up to 89%. The toxicology behavior of SrO–CeO2 mixed oxide NPs found due to the high oxygen site vacancies, ROS formation, smallest particle size and higher surface area.

scholarly journals Atomic Layer Deposition of ZnO on Mesoporous Silica: Insights into Growth Behavior of ZnO via In-Situ Thermogravimetric Analysis

Nanomaterials ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 981 ◽  
Author(s):  
Piyush Ingale ◽  
Kristian Knemeyer ◽  
Mar Piernavieja Hermida ◽  
Raoul Naumann d’Alnoncourt ◽  
Arne Thomas ◽  
...  
Keyword(s):  
Thermogravimetric Analysis ◽  
Atomic Layer Deposition ◽  
Reaction Mechanisms ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Layer ◽  
Ex Situ ◽  
Direct Access ◽  
Layer Deposition

ZnO is a remarkable material with many applications in electronics and catalysis. Atomic layer deposition (ALD) of ZnO on flat substrates is an industrially applied and well-known process. Various studies describe the growth of ZnO layers on flat substrates. However, the growth characteristics and reaction mechanisms of atomic layer deposition of ZnO on mesoporous powders have not been well studied. This study investigates the ZnO ALD process based on diethylzinc (DEZn) and water with silica powder as substrate. In-situ thermogravimetric analysis gives direct access to the growth rates and reaction mechanisms of this process. Ex-situ analytics, e.g., N2 sorption analysis, XRD, XRF, HRTEM, and STEM-EDX mapping, confirm deposition of homogenous and thin films of ZnO on SiO2. In summary, this study offers new insights into the fundamentals of an ALD process on high surface area powders.

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