Low-Frequency Sonophoresis as an Active Approach to Potentiate the Transdermal Delivery of Agomelatine-Loaded Novasomes: Design, Optimization, and Pharmacokinetic Profiling in Rabbits

: Skin being the largest external organ, offers an enticing procedure for transdermal drug delivery, so the drug needs to rise above the outermost layer of the skin, i.e., stratum corneum. Small molecular drug entities obeying the Lipinski rule, i.e., drugs having a molecular weight less than 500Da, high lipophilicity, and optimum polarity, are favored enough to be used on the skin as therapeutics. Skin's barrier action properties prevent the transport of macromolecules at pre-determined therapeutic rates. Notable advancement in macromolecules' transdermal delivery occurred in recent years. Scientists have opted for liposomes, the use of electroporation or, low-frequency ultrasound techniques. Some of these have shown better delivery of macromolecules at clinically beneficial rates. These physical technologies involve complex mechanisms, which may irreversibly incur skin damage. Majorly, two types of lipid-based formulations, including Solid Lipid Nanoparticles (SLNs) and Nanostructured Lipid Carriers (NLCs) are widely investigated as a transdermal delivery system. In this review, the concepts, mechanisms, and applications of Nanostructured Lipid Carriers that are considered feasible for transporting macromolecules via transdermal delivery system are thoroughly reviewed and presented along with their clinical perspective.

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Low Frequency Vibration Isolation Through an Active-on-Active Approach: Coupling Effects

Journal of Vibration and Acoustics ◽

10.1115/1.4000477 ◽

2009 ◽

Vol 131 (6) ◽

Cited By ~ 2

Author(s):

Qiao Sun ◽

Robert A. Wolkow ◽

Mark Salomons

Keyword(s):

Vibration Isolation ◽

Low Frequency ◽

Noise Cancellation ◽

Frequency Noise ◽

Active Stage ◽

Coupling Effects ◽

Active Approach ◽

Low Frequency Vibration ◽

Wide Range ◽

Coupling Characteristics

The extreme sensitivity of a scanning probe microscope demands an exceptional noise cancellation device that could effectively cut off a wide range of vibration noise. Existing commercial devices, although excellent in canceling high frequency noise, commonly leave low frequency vibration unattenuated. We design an add-on active stage that can function together with a standalone existing active stage. The objective is to provide a higher level of noise cancellation by lowering the overall system cut-off frequency. This study is concerned with the theoretical aspects of the coupling characteristics involved in stacking independently designed stages together to form a two-stage isolator. Whether an add-on stage would pose a stability threat to the existing stage needs to be addressed. In addition, we explore the use of coupling effects to optimize the performance of the overall system.

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Design Optimization of Aircraft Engine-Mount Systems

14th Biennial Conference on Mechanical Vibration and Noise: Vibration and Control of Mechanical Systems ◽

10.1115/detc1993-0227 ◽

1993 ◽

Author(s):

Hashem Ashrafiuon

Keyword(s):

Design Optimization ◽

Vibration Isolation ◽

Optimization Problems ◽

Three Dimensional ◽

Low Frequency ◽

Aircraft Engine ◽

Variable Metric ◽

Design Variables ◽

Engine Mount ◽

Optimization Search

Abstract Design optimization of aircraft engine-mount systems for vibration isolation is presented. The engine is modeled as a rigid body connected to a flexible base representing the nacelle. The base is modeled with mass and stiffness matrices and structural damping using finite element modeling. The mounts are modeled as three-dimensional springs with hysteresis damping. The objective is to select the stiffness coefficients and orientation angles of the individual mounts to minimize the transmitted forces from the engine to the base. Meanwhile, the mounts have to be stiff enough not allowing engine deflection to exceed its limits under static and low frequency loadings. It is shown that with an optimal system the transmitted forces may be reduced significantly particularly when mount orientation angles are also treated as design variables. The optimization problems are solved using a Constraint Variable Metric approach. The closed form derivatives of the engine vibrational amplitudes with respect to design variables are derived in order to achieve a more effective optimization search technique.

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