FABRICATION OF NANOPOROUS CHITOSAN MEMBRANES

NANO ◽  
2010 ◽  
Vol 05 (01) ◽  
pp. 53-60 ◽  
Author(s):  
XIAOLIANG WANG ◽  
XIANG LI ◽  
ELEANOR STRIDE ◽  
MOHAN EDIRISINGHE
Keyword(s):  
Low Frequency ◽  
Drug Carriers ◽  
Structural Features ◽  
Wound Dressings ◽  
Ftir Analysis ◽  
Tissue Engineering Scaffolds ◽  
Nanoscale Structures ◽  
Low Frequency Ultrasound ◽  
Chitosan Membranes ◽  
The Stability

Naturally derived biopolymers have been widely used for biomedical applications such as drug carriers, wound dressings, and tissue engineering scaffolds. Chitosan is a typical polysaccharide of great interest due to its biocompatibility and film-formability. Chitosan membranes with controllable porous structures also have significant potential in membrane chromatography. Thus, the processing of membranes with porous nanoscale structures is of great importance, but it is also challenging and this has limited the application of these membranes to date. In this study, with the aid of a carefully selected surfactant, polyethyleneglycol stearate-40, chitosan membranes with a well controlled nanoscale structure were successfully prepared. Additional control over the membrane structure was obtained by exposing the suspension to high intensity, low frequency ultrasound. It was found that the concentration of chitosan/surfactant ratio and the ultrasound exposure conditions affect the structural features of the membranes. The stability of nanopores in the membrane was improved by intensive ultrasonication. Furthermore, the stability of the blended suspensions and the intermolecular interactions between chitosan and the surfactant were investigated using scanning electron microscope and Fourier transform infrared spectroscopy (FTIR) analysis, respectively. Hydrogen bonds and possible reaction sites for molecular interactions in the two polymers were also confirmed by FTIR analysis.

scholarly journals Effect of high power low frequency ultrasound processing on the stability of lycopene

2015 ◽  
Vol 27 ◽  
pp. 586-591 ◽  
Author(s):  
Valéria S. Oliveira ◽  
Sueli Rodrigues ◽  
Fabiano A.N. Fernandes
Keyword(s):  
High Power ◽  
Low Frequency ◽  
Low Frequency Ultrasound ◽  
The Stability ◽  
Frequency Ultrasound

Novel tissue engineering scaffolds as wound dressings loaded with Alkannins/Shikonins as active ingredients

2019 ◽  
Author(s):  
AS Arampatzis ◽  
K Theodoridis ◽  
E Aggelidou ◽  
KN Kontogiannopoulos ◽  
I Tsivintzelis ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Wound Dressings ◽  
Active Ingredients ◽  
Tissue Engineering Scaffolds

Low-frequency ultrasound and photochromotherapy in the complex treatment of patients with chronic bacterial and viral rhinosinusitis

2020 ◽  
pp. 13-23
Author(s):  
Natalya Kornova ◽  
A. Krylov
Keyword(s):  
Chronic Rhinosinusitis ◽  
Low Frequency ◽  
Chronic Tonsillitis ◽  
Complex Treatment ◽  
Resonance Imaging ◽  
X Ray ◽  
Low Frequency Ultrasound ◽  
Viral Nature ◽  
Ig G ◽  
Frequency Ultrasound

The article presents results of a study on the effectiveness of using lowfrequency ultrasound and photochromotherapy in the complex treatment of patients with chronic bacterial and viral rhinosinusitis. The study involved 69 people aged 18 to 55 years: 39 (56.83 %) women and 30 (45.11 %) men with chronic rhinosinusitis during the period of clinical exacerbation and concomitant chronic tonsillitis without exacerbation. All patients included in the study underwent X-ray examination or computed tomography and magnetic resonance imaging of the paranasal sinuses. 100 % of the patients were examined for the presence of antibodies to Human gammaherpesvirus 4 (ELISA), had study of blood serum for IgM and IgG and test to determine the avidity of Ig G antibodies to γ-herpesviruses. The obtained data indicate the effectiveness of including low-frequency ultrasound and photochromotherapy in the complex treatment of patients with chronic rhinosinusitis and concomitant chronic tonsillitis of bacterial and viral nature without exacerbation.

Application of Low‐Frequency Ultrasound for Intensified Biodiesel Production Process

2021 ◽  
pp. 59-84
Author(s):  
Mohd Razealy Anuar ◽  
Mohamed Hussein Abdurahman ◽  
Nor Irwin Basir ◽  
Ahmad Zuhairi Abdullah
Keyword(s):  
Production Process ◽  
Low Frequency ◽  
Biodiesel Production ◽  
Low Frequency Ultrasound ◽  
Frequency Ultrasound

The comparative study of high- and low-frequency ultrasound therapy on bone regeneration

2003 ◽  
Vol 29 (5) ◽  
pp. S120-S121
Author(s):  
S. Bashardoust Tajali ◽  
S. Kazemi ◽  
A. Azari ◽  
A. Shahverdi ◽  
M. Jabal Ameli
Keyword(s):  
Comparative Study ◽  
Bone Regeneration ◽  
Low Frequency ◽  
Ultrasound Therapy ◽  
Low Frequency Ultrasound ◽  
The Comparative Study ◽  
Frequency Ultrasound

Resonance in a mathematical model of baroreflex control: arterial blood pressure waves accompanying postural stress

2005 ◽  
Vol 288 (6) ◽  
pp. R1637-R1648 ◽  
Author(s):  
Peter E. Hammer ◽  
J. Philip Saul
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Blood Volume ◽  
Low Frequency ◽  
Pressure Waves ◽  
Central Blood Volume ◽  
Arterial Baroreflex ◽  
Arterial Blood ◽  
Gain Margin ◽  
The Stability

A mathematical model of the arterial baroreflex was developed and used to assess the stability of the reflex and its potential role in producing the low-frequency arterial blood pressure oscillations called Mayer waves that are commonly seen in humans and animals in response to decreased central blood volume. The model consists of an arrangement of discrete-time filters derived from published physiological studies, which is reduced to a numerical expression for the baroreflex open-loop frequency response. Model stability was assessed for two states: normal and decreased central blood volume. The state of decreased central blood volume was simulated by decreasing baroreflex parasympathetic heart rate gain and by increasing baroreflex sympathetic vaso/venomotor gains as occurs with the unloading of cardiopulmonary baroreceptors. For the normal state, the feedback system was stable by the Nyquist criterion (gain margin = 0.6), but in the hypovolemic state, the gain margin was small (0.07), and the closed-loop frequency response exhibited a sharp peak (gain of 11) at 0.07 Hz, the same frequency as that observed for arterial pressure fluctuations in a group of healthy standing subjects. These findings support the theory that stresses affecting central blood volume, including upright posture, can reduce the stability of the normally stable arterial baroreflex feedback, leading to resonance and low-frequency blood pressure waves.

scholarly journals Evolution of a narrow-band spectrum of random surface gravity waves

2003 ◽  
Vol 478 ◽  
pp. 1-10 ◽  
Author(s):  
KRISTIAN B. DYSTHE ◽  
KARSTEN TRULSEN ◽  
HARALD E. KROGSTAD ◽  
HERVÉ SOCQUET-JUGLARD
Keyword(s):  
Three Dimensional ◽  
Low Frequency ◽  
Three Dimensions ◽  
Band Spectrum ◽  
Nls Equation ◽  
Random Surface ◽  
Narrow Bandwidth ◽  
Quasi Stationary State ◽  
The Stability ◽  
Three Dimensional Simulations

Numerical simulations of the evolution of gravity wave spectra of fairly narrow bandwidth have been performed both for two and three dimensions. Simulations using the nonlinear Schrödinger (NLS) equation approximately verify the stability criteria of Alber (1978) in the two-dimensional but not in the three-dimensional case. Using a modified NLS equation (Trulsen et al. 2000) the spectra ‘relax’ towards a quasi-stationary state on a timescale (ε2ω0)−1. In this state the low-frequency face is steepened and the spectral peak is downshifted. The three-dimensional simulations show a power-law behaviour ω−4 on the high-frequency side of the (angularly integrated) spectrum.

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