scholarly journals Nanodispersions of TiO2 in Water for Removing Acrylic Films Used in Conservation

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3966
Author(s):  
Giulia Giuntoli ◽  
Marta Bini ◽  
Benedetta Ciuffi ◽  
Barbara Salvadori ◽  
Giovanni Baldi ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Polymeric Films ◽  
Polydispersity Index ◽  
Photocatalytic Properties ◽  
Nanoparticle Size ◽  
Sem Images

The influence of a nanodispersion of TiO2 in water (nanoparticle size: 40 nm, polydispersity index: 0.25), brushed on a Paraloid film and subjected to UV–Vis irradiation was evaluated. The TiO2 nanodispersions showed a tendency to reduce the molecular weight of Paraloid due to its photocatalytic properties. FTIR and GPC analyses and SEM images suggested the degradation of the polymer, while chromatic variations of the films were scarcely detected. This study is very remarkable in the perspective of using this material for the removal of polymeric films used in conservation.

scholarly journals Molecular Weight Dependence of Spreading Rates of Ultrathin Polymeric Films

1998 ◽  
Vol 80 (24) ◽  
pp. 5377-5380 ◽  
Author(s):  
M. P. Valignat ◽  
G. Oshanin ◽  
S. Villette ◽  
A. M. Cazabat ◽  
M. Moreau
Keyword(s):  
Molecular Weight ◽  
Polymeric Films ◽  
Molecular Weight Dependence ◽  
Spreading Rates

scholarly journals A Water-Soluble Polysaccharide from the Fruit Bodies ofBulgaria inquinans(Fries) and Its Anti-Malarial Activity

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Hongtao Bi ◽  
Han Han ◽  
Zonghong Li ◽  
Weihua Ni ◽  
Yan Chen ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Immune Function ◽  
Lymphocyte Proliferation ◽  
Water Soluble ◽  
Polydispersity Index ◽  
Immune Competence ◽  
Suppressive Activity ◽  
Macrophage Phagocytosis ◽  
Immunological Tests ◽  
Soluble Polysaccharide

A water-soluble polysaccharide (BIWS-4b) was purified from the fruit bodies ofBulgaria inquinans(Fries). It is composed of mannose (27.2%), glucose (15.5%) and galactose (57.3%). Its molecular weight was estimated to be 7.4 kDa (polydispersity index, Mw/Mn: 1.35). Structural analyses indicated that BIWS-4b mainly contains (1→6)-linked, (1→5)-linked and (1→5,6)-linkedβ-Galfunits; (1→4)-linked and non-reducing terminalβ-Glcpunits; and (1→2)-linked, (1→6)-linked, (1→2,6)-linked and non-reducing terminalα-Manpunits. When examined by the 4-day method and in a prophylactic assay in mice, BIWS-4b exhibited markedly suppressive activity against malaria while enhancing the activity of artesunate. Immunological tests indicated that BIWS-4b significantly enhanced macrophage phagocytosis and splenic lymphocyte proliferation in malaria-bearing mice and normal mice. The anti-malarial activity of BIWS-4b might be intermediated by enhancing immune competence and restoring artesunate-suppressed immune function. Thus, BIWS-4b is a potential adjuvant of anti-malaria drugs.

Evaluation of polydispersity index Mw/Mn by quasielastic light scattering

1987 ◽  
Vol 52 (5) ◽  
pp. 1235-1245 ◽  
Author(s):  
Petr Štěpánek ◽  
Zdeněk Tuzar ◽  
Čestmír Koňák
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Decay Time ◽  
Sampling Time ◽  
Polydispersity Index ◽  
New Method ◽  
Molecular Weights ◽  
Quasielastic Light Scattering ◽  
Good Agreement

The response of quasielastic light scattering to the polydispersity of scattering objects has been investigated. A new method of the polydispersity index determination has been suggested, suitable for the range 1.02 ⪬ Mw/Mn ⪬ 2.0 and consisting in the measurement of the dependence of the apparent decay time on the correlator sampling time. The polydispersity index can be determined by comparing these dependences with the theoretical ones obtained using correlation curves simulated for various values of the polydispersity index, assuming lognormal and Schulz-Zimm distributions of molecular weights. The test measurements on polystyrene standards having molecular weights in the range 9 103 – 20.6 106 give polydispersity index values Mw/Mn that are in a good agreement with those given by the manufacturer. The polydispersity index for polystyrene having the molecular weight Mw = 20.6 106 thus determined was Mw/Mn = 1.35.

Engineering of Stable Recombinant Bacteria for Production of Chiral Medium-Chain-Length Poly-3-Hydroxyalkanoates

1999 ◽  
Vol 65 (8) ◽  
pp. 3265-3271 ◽  
Author(s):  
Maria A. Prieto ◽  
Michele B. Kellerhals ◽  
Gian B. Bozzato ◽  
Dragan Radnovic ◽  
Bernard Witholt ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Chain Length ◽  
Expression System ◽  
Average Molecular Weight ◽  
Polydispersity Index ◽  
Recombinant Bacteria ◽  
E Coli ◽  
Medium Chain ◽  
Medium Chain Length ◽  
Pha Production

ABSTRACT In order to scale up medium-chain-length polyhydroxyalkanoate (mcl-PHA) production in recombinant microorganisms, we generated and investigated different recombinant bacteria containing a stable regulated expression system for phaC1, which encodes one of the mcl-PHA polymerases of Pseudomonas oleovorans. We used the mini-Tn5 system as a tool to constructEscherichia coli 193MC1 and P. oleovoransPOMC1, which had stable antibiotic resistance and PHA production phenotypes when they were cultured in a bioreactor in the absence of antibiotic selection. The molecular weight and the polydispersity index of the polymer varied, depending on the inducer level. E. coli 193MC1 produced considerably shorter polyesters thanP. oleovorans produced; the weight average molecular weight ranged from 67,000 to 70,000, and the polydispersity index was 2.7. Lower amounts of inducer added to the media shifted the molecular weight to a higher value and resulted in a broader molecular mass distribution. In addition, we found that E. coli 193MC1 incorporated exclusively the R configuration of the 3-hydroxyoctanoate monomer into the polymer, which corroborated the enantioselectivity of the PhaC1 polymerase enzyme.

scholarly journals Influence of Ionic Liquids Assisted Synthesis on Morphology and Photocatalytic Properties of Bi4O5Br2

Proceedings ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 26
Author(s):  
Patrycja Wilczewska ◽  
Aleksandra Bielicka-Giełdoń ◽  
Agnieszka Fiszka Borzyszkowska ◽  
Aleksandra Pieczyńska ◽  
Ewa Maria Siedlecka
Keyword(s):  
Ionic Liquids ◽  
Photoelectron Spectroscopy ◽  
Photocatalytic Properties ◽  
X Ray Diffraction ◽  
Sem Images ◽  
New Thought ◽  
X Ray ◽  
Chromium Vi ◽  
Ft Ir ◽  
Adsorption Desorption

A series of Bi4O5Br2 photocatalysts were prepared via an innovation method of synthesis with ionic liquids (ILs). The crystal structures were investigated by X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). The Field Emission Scanning Electron Microscope (FE-SEM) images illustrated the unique structure of prepared photocatalysts. The photocatalysts were also characterized by N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectra (UV-vis/DRS) and photoluminescence spectra (PL). The role of ILs in synthesis of Bi4O5Br2 on morphology and photocatalytic properties were investigated. Rhodamine B, 5-fluorouracil and chromium (VI) were used as the model micropollutants to evaluated adsorption capacity, photooxidation and photoreduction ability of prepared Bi4O5Br2 under artificial solar light. This work provided a new thought for enhanced photocatalytic activity of bismuth oxybromide photocatalysts.

Sequential Extraction of Lignin from Sugarcane Bagasse: Characterization and Application in the Pb(II) Adsorption

2019 ◽  
Vol 13 (4) ◽  
pp. 550-556 ◽  
Author(s):  
Ni Liu ◽  
Shuangfei Wang ◽  
Hongxiang Zhu ◽  
Xinliang Liu
Keyword(s):  
Molecular Weight ◽  
Sequential Extraction ◽  
Adsorption Property ◽  
Hydroxyl Group ◽  
Sem Images ◽  
Surface Areas ◽  
Lignin Fraction ◽  
Bet Analysis ◽  
Sequential Extraction Method ◽  
L1 And L2

Lignin was extracted from bagasse by sequential extraction method. The crude lignin was divided into three fractions by molecular weight and chemical functionality (Lignin fractions L1 and L2 were recovered with diethyl ether and methanol solubility respectively, with the L3 part remaining), and the properties of each were analyzed before being applied to Pb(II) adsorption. The results indicated that the L2 fraction has the largest molecular weight due to self-condensation. The weight of the aliphatic hydroxyl group of L2 is 4.63 times of L1 and 1.65 times of crude lignin. Scanning electron microscopy (SEM) images and Brunauer-Emmett-Teller (BET) analysis show that the surface of L2 and L3 are porous with surface areas of 2.8304 m2/g and 10.7530 m2/g, respectively. The characteristics of structure and morphology for the L2 and L3 fractions display better adsorption property than crude lignin and L1 fractions, with adsorption capacities of approximately 6.46 mg/g and 7.56 mg/g. This research confirmed that each lignin fraction possessed different chemical and physical characteristics, and the L2 fraction has good solubility and adsorption properties, which provide the basis for lignin modification applied to lead Pb(II) adsorption.

Preparation of cellulose acetate films with controlled porosity

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Rodolfo-Fabian Estrada ◽  
Carlos Alvarez-Gayosso ◽  
Victor M. Castaño
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Cellulose Acetate ◽  
Hot Water ◽  
Polymeric Films ◽  
Water Mixture ◽  
Controlled Porosity ◽  
Ice Water ◽  
High Molecular Weight Poly ◽  
Scanning Electron

AbstractPorous polymeric films were obtained by immersing a solution of cellulose acetate and high molecular weight poly(acrylic acid) into an ice-water mixture. The films, the porosity of which can be controlled (reversibly) by immersion into hot water for varying periods of time, were characterized by IR spectroscopy and lowvacuum scanning electron microscopy.

scholarly journals Synthesis of Poly(N-fluoroalkyl benzamide) with Controlled Molecular Weight and Polydispersity Index

2007 ◽  
Vol 39 (8) ◽  
pp. 777-782 ◽  
Author(s):  
Kaoru Ohshimizu ◽  
Yuji Shibasaki ◽  
Mitsuru Ueda
Keyword(s):  
Molecular Weight ◽  
Polydispersity Index
Sign in / Sign up

Export Citation Format

Share Document