Processing Considerations for Salicylic Acid-Based Polymers

2003 ◽  
Author(s):  
Eva Wagner ◽  
Kathryn Uhrich ◽  
Thomas Twardowski

This paper describes some of the processing issues for extruding salicylic acid-based polymer prodrugs into fibers for medical devices. Polymeric prodrugs, in which a drug is polymerized in a degradable polymer that delivers controlled quantity of the drug to a targeted site in the body as the device degrades, are a new approach to controlled release. Hollow fibers were produced by solution spinning. Solid fibers were formed by melt processing. The salicylic acid polymers exhibited shear-thinning behavior. The viscosity exhibited pronounced temperature dependence.

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hanjun Ryu ◽  
Hyun-moon Park ◽  
Moo-Kang Kim ◽  
Bosung Kim ◽  
Hyoun Seok Myoung ◽  
...  

AbstractSelf-powered implantable devices have the potential to extend device operation time inside the body and reduce the necessity for high-risk repeated surgery. Without the technological innovation of in vivo energy harvesters driven by biomechanical energy, energy harvesters are insufficient and inconvenient to power titanium-packaged implantable medical devices. Here, we report on a commercial coin battery-sized high-performance inertia-driven triboelectric nanogenerator (I-TENG) based on body motion and gravity. We demonstrate that the enclosed five-stacked I-TENG converts mechanical energy into electricity at 4.9 μW/cm3 (root-mean-square output). In a preclinical test, we show that the device successfully harvests energy using real-time output voltage data monitored via Bluetooth and demonstrate the ability to charge a lithium-ion battery. Furthermore, we successfully integrate a cardiac pacemaker with the I-TENG, and confirm the ventricle pacing and sensing operation mode of the self-rechargeable cardiac pacemaker system. This proof-of-concept device may lead to the development of new self-rechargeable implantable medical devices.


Author(s):  
A.V. DUNAEV

The work is aimed at developing a new approach to assessing adaptive changes in microcirculatory tissue systems when various loads are exerted on the body (sports or physiological stresses), based on the analysis of oscillations in microcirculatory blood flow and tissue oxygen saturation, measured by laser Doppler flowmetry (LDF) and tissue reflectance oximetry (TRO). The study involved eight healthy volunteers aged 21–49 years. Measurements were taken on the palmar surface of the middle finger of the right hand and the medial surface of the lower part of the forearm. The rhythmic oscillations of LDF and TRO were studied using wavelet analysis. Data analysis revealed resonant and synchronized oscillations in the LDF and TRO signals in the myogenic range as an adaptive change as a result of a reaction to physical activity and psychoemotional stress.


Author(s):  
L. Saeednia ◽  
A. Usta ◽  
R. Asmatulu

Hydrogels are the promising classes of polymeric drug delivery systems with the controlled release rates. Among them, injectable thermosensitive hydrogels with transition temperature around the body temperature have been wildly considered. Chitosan is one of the most abundant natural polymers, and its biocompatibility and biodegradability makes it a favorable thermosensitive hydrogel that has been attracted much attention in biomedical field worldwide. In this work, a thermosensitive and injectable hydrogel was prepared using chitosan and β-glycerophosphate (β-GP) incorporated with an antibacterial drug (gentamycin). This drug loaded hydrogel is liquid at room temperature, and becomes more solidified gel when heated to the body temperature. Adding β-GP into chitosan and drug molecules and heating the overall solution makes the whole homogenous liquid into gel through a 3D network formation. The gelation time was found to be a function of temperature and concentration of β-GP. This thermosensitive chitosan based hydrogel system was characterized using FTIR and visual observation to determine the chemical structure and morphology. The results confirmed that chitosan/(β-GP) hydrogels could be a promising controlled-release drug delivery system for many deadly diseases.


2016 ◽  
Vol 30 (1) ◽  
pp. e12410 ◽  
Author(s):  
Paulo Rowilson Cunha ◽  
Nabila Scabine Pessotti ◽  
Camila Bonati Mattos ◽  
Ana Flavia Salai

Author(s):  
E Ashare ◽  
T. W. Brooks ◽  
D. W. Swenson

2019 ◽  
Vol 28 (2) ◽  
pp. 179-196
Author(s):  
Olga Beloborodova ◽  
Pim Verhulst

Play is usually regarded as the starting point of Beckett's late theatre, introducing a radically new approach to the body and language that set a benchmark for subsequent plays such as Not I, That Time and Footfalls. Building on Krapp's Last Tape and Happy Days, Play dehumanizes its characters by means of the audiovisual technologies that Beckett was experimenting with at the time. In this process, his human subjects are increasingly reduced to mechanical devices or mouthpieces for the conveyance of speech, instead of represented as recognizable and sentient beings of flesh and blood. The nonhuman aspect of Play is enhanced by its foregrounding of Beckett's long-standing fascination with the mineral, with the characters' faces being ‘so lost to age and aspect as to seem almost part of the urns’. Whereas, separately, the influence of radio, television and cinema on Play has received some critical attention, and James Knowlson, Claire Lozier, Mark Nixon, Jean-Michel Rabaté and Conor Carville, among others, have noted Beckett's fascination with the sculptural arts and the inorganic, this paper aims to merge those two strands by discussing the docufilm Les statues meurent aussi (1953) as a potential but overlooked source of inspiration. By combining the technological and the sculptural in Play, Beckett stages a ‘mineral mechanics’ verging closely on the nonhuman without being fully dehumanized, as characters continue to laugh and hiccup, barely retaining a trace of their humanity. This oscillation from the human to the nonhuman and vice versa is clearly traceable in the genesis of the text, as well as its French translation (Comédie). The result, Play's iconic stage image, is marked by the familiar Beckettian trope of in-betweenness: between life and death, between the organic and the mineral, between the natural and the technological.


PEDIATRICS ◽  
1974 ◽  
Vol 54 (6) ◽  
pp. 713-717
Author(s):  
Gerhard Levy ◽  
Sumner J. Yaffe

The apparent volume of distribution (Vd) of salicylate was determined in 11 children, 4 months to 16 years old, who had ingested from about 36 to over 340 mg of salicylic acid (mainly as aspirin) per kilogram of body weight. Vd was calculated from the amount of salicylate in the body at a given time (as determined by the amount of total salicylates excreted in the urine and, where applicable, removed in peritoneal dialysis fluid after that time) and the concentration of salicylate in the plasma at the same time. This method of calculation is ideal for the nonlinearly eliminated salicylic acid and does not require any assumptions with respect to the nature of the pharmacokinetic model for salicylate distribution. The Vd for salicylate in the children ranged from 162 to 345 ml/kg and was larger at the higher doses. Plots of salicylate concentration in plasma versus amount of drug in the body were usually linear for a given patient, showing that Vd remained relatively constant over the time course of elimination of the drug in the patients studied. This indicates that a given plasma salicylate concentration in children who have ingested large doses reflects a larger amount of salicylate in the body than the same plasma concentration in children who ingested smaller doses of the drug. These observations help to rationalize and emphasize the usefulness of the Done nomogram (which involves estimation of the theoretical zero time plasma salicylate concentration by back extrapolation) for assessing the severity of salicylate intoxication.


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