There are two different physiological mechanisms that cause blood to circulate around the human body during cardiopulmonary resuscitation. The "cardiac pump" generates blood flow by squeezing blood out of the heart as the sternum is depressed. The "thoracic pump" generates flow by forcing blood out of the heart and the great vessels as the intrathoracic pressure rises due to chest compression. To date, all CPR techniques try to circulate blood during cardiac arrest by exploiting elite; the cardiac pump or the thoracic pump mechanism of blood flow. No mechanical CPR device thus far invented has tried to exploit both mechanisms at the same time. We hypothesize that a combination of the cardiac and thoracic pump mechanisms of blood flow should generate more blood flow than either alone. We have thus invented a device that performs simultaneous sterno-thoracic cardiopulmonary resuscitation (SST-CPR). Our SST-CPR device augments blood flow to the vital organs by performing cardiac and thoracic compression simultaneously using two components. A piston provides direct sternal compression, squeezing blood out of the heart directly ("cardiac pump"). A thoracic strap and back supporting structure create circumferential thoracic constriction ("thoracic pump"). Simultaneous compression and constriction are performed by pushing the compressing piston, which directly compresses the heart and increases intrathoracic pressure by constricting the thorax. Mechanical tests have been performed. Tests have also been performed to measure hemodynamic parameters in vivo. The device has been designed to allow variation in the relative contribution of either the cardiac or thoracic pump during CPR, thus allowing better understand of the relative importance of each mechanism during CPR.

The use of phosphine gas requires that respiratory protection be used if exposures exceed the OSHA permissible exposure limit. As with other chemical exposures limits many of the references used to establish occupational health guidelines date back to the 1930’s and 1940’s. This is quite common and is the case with phosphine gas. Initial planning for fumigations involving magnesium phosphide requires that a hazard assessment be performed. Expected worker exposures based on previous monitoring or test data was not readily available. Many current practices and procedures for fumigations are based on recommendations from applicators who used the product in the 1950’s and 60’s. Unfortunately, many of the recommendations were based on personal opinion and experience rather than actual exposure monitoring data. Not until the 1980's were comprehensive applicator exposure assessments being conducted for different tasks involving magnesium phosphide. As a result, it is necessary to generate current applicator exposure data and compare the data to current occupational exposure limits for phosphine gas.

Helicoidal fiber structures are essential to shell structures of many animals, such arthropods and human bones. Despite prior studies, limited research exists to quantify the mechanical behavior of helicoidal fiber structures with respect to the architecture of the fibers and matrices. The objective of this research is to use an integrated experimental and modeling approach to study the mechanical performance of helicoidal fiber structures under compressive and shear loadings. First, bioinspired helicoidal fiber specimens are created using 3D printed fiber cores and epoxy matrices. Load-displacement curves are collected for the helicoidal fiber specimens under monotonic torsional and compressive loadings to illustrate the composite failure process. Then, microscopic characterization is performed to reveal the fracture mechanisms in helicoidal fiber structures under normal and shear stresses. Finally, finite element analysis is performed to detail the mechanical response of the composites with respect to different design parameters to optimize material design. This bio-inspired study provides insights to the mechanical behavior of helicoidal fiber structures and potential hints for the development of high performance fiber-reinforced composites.

A novel amphiphilic core-corona hyperbranched polymer, composed of 3-ethyl-3-(hydroxylmethyl) oxetane (EHMO) and PEGylated EHMO (EHMOPEG), was synthesized through cationic ring opening polymerization. Nuclear Magnetic Resonance spectroscopy (NMR), Dynamic Light Scattering (DLS), and Fourier Transform Infrared spectroscopy (FTIR) were used to characterize the polymer structure and degree of branching. It was found that the degree of branching (DOB) of the polymer was affected by the weight % ratios of EHMO/EHMOPEG used in polymerization. As the weight % ratio of EHMO/ EHMOPEG decreased, the DOB was observed to increase. Polymeric particles based on the synthesized polymer were prepared using the O/W (Oil in Water) solvent emulsion method and evaluated for drug delivery. Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS) were used to characterize the size and shape of the particles. The obtained particles were found to be spherical in shape and have a narrow size distribution. Camptothecin (CPT) was used as the model drug for drug encapsulation and controlled release studies. The loading and encapsulation efficiencies of the particles ranged between 60% and 80%. Cytotoxicity studies carried out with human skin fibroblasts indicated that as the weight % ratio of the EHMO/ EHMOPEG decreased the biocompatibility of the polymer increased. In vitro drug release studies showed that the CPT could be released over an extended period of time. The efficacy of the drug released from the particles was demonstrated by the MTT assay on HN12 cells. The results showed that the cellular activity decreased as the amount of drug released from the particles increased over a span of 72 hours. The synthesized polymer represents a new family of hyperbranched macromolecule with potential for drug delivery.

A novel nanofiber scaffold was fabricated and characterized as a potential antimicrobial wound dressing. Half generation polyamidoamine (PAMAM) dendrimer G3.5 was covalently conjugated to gelatin. Gelatin alone or with gelatin-dendrimer conjugates was electrospun into nanofiber scaffolds. Gelatin is a derivative of natural collagen, and it is biocompatible, non-toxic and inexpensive, making it a desirable component in a wound dressing. Dendrimers are synthetic polymers comprising of a central core, internal branches and reactive surface groups. They provide a structurally controlled architecture for drug release. Silver was incorporated into the scaffold in situ due to its broad spectrum of antimicrobial properties. The scaffolds were further crosslinked by photo curable PEG-diacrylate in solution or vapor to gain structure stability. The fabricated scaffolds with various compositions displayed a wide range of structure characteristics and properties in terms of fiber morphology, swelling and degradation, mechanical properties, antimicrobial activity and silver release kinetics. The scaffolds showed a similar fiber structure and morphology. It was found that the fiber diameter of the scaffolds containing silver was greater than scaffolds without silver. The porosity of the crosslinked scaffolds ranged from 67.56% to 90.42% and also exhibited a high capacity of swelling and adsorption. The results of the antimicrobial assay showed that scaffolds containing silver could effectively inhibit growth of bacteria at the end of 48 h. In vitro silver release studies demonstrated that silver could be released in a controlled manner over an extended period of time.

The oral buccal mucosa is a promising absorption site for drug administration because it is permeable, highly vascularized and allows ease of administration. Although there are many platforms that have been used for drug delivery, nanofiber scaffolds as a platform for local or systemic drug delivery through the oral mucosa have not been fully explored. In this thesis, we fabricated a biocompatible electrospun gelatin nanofiber scaffold for local drug delivery at the oral mucosa. To stabilize the electrospun gelatin nanofibers and allow non-invasive incorporation of therapeutics into the scaffold, photo-reactive polyethylene-glycol (PEG)-diacrylate was employed to crosslink the scaffold to form semi-interpenetrating networks (sIPNs). The crosslinking parameters including concentration of PEG-diacrylate, amount of photoinitiator, and crosslinking incubation time of the scaffold were systematically investigated. The resulting scaffolds were characterized in terms of their morphology, tensile properties, porosity, swelling and degradation. The results confirmed that gelatin electrospun nanofiber scaffolds after being photo-crosslinked with PEG-diacrylate retain fiber morphology and show improved structural stability and mechanical properties. The mucoadhesiveness of the sIPN nanofiber scaffold was confirmed. Nystatin, a drug to treat fungal infections such as candidiasis was loaded to the sIPN nanofiber scaffold. Its release kinetics was also studied.

The purpose of this study was to build a helical axis algorithm capable of detecting changes in the helical axis intersection of the tibia and femur in human knees. This algorithm was designed and tested using three models: a multiplanar rigid body model, a mathematical model, and a cylinder model. The multiplanar rigid body model closely mimics knee movement without supporting ligamentous structures, thus the movement was unconstrained. In this model kinematic position data were collected using both MotionMonitor™ (MotionMonitor™ Version 7.7, Innovative Sports Training, Chicago, IL) and Vicon Nexus 1.3 software system (Oxford Metrics Group, Oxford, UK). To test the algorithm under more controlled conditions and eliminate kinematic collection errors, a mathematical model was used. The cylinder model was used to obtain constrained movement data using MotionMonitor™. The results from the two models using a kinematic collection system were inconclusive due to the large errors in the collection process. The mathematical model validated the helical axis algorithm. Statistical analysis of kinematic data showed good correlation between the data but the errors from this data were to large to be useful in a clinical setting. Further research is needed to use the helical axis to model the tibial and femoral rotation on the meniscus.

In 2004, the National Collegiate Athletic Association reported ankle sprain as the most frequent injury in soccer, basketball, and volleyball players. Further research found an increased likelihood with fatigue. Measuring fatigue during functional activities has been a longstanding problem. In this study, changes in ankle biomechanics were measured using a tri-axial accelerometer embedded in the shoe as subjects (n=12) performed a fatiguing activity. Data were collected from the accelerometer and from established devices that are considered the industry gold standard. Several kinetic and kinematic accelerometer derived variables were highly correlated with these standards (r2>0.90) and were associated with changes in fatigue. The tri-axial accelerometer in this configuration may be suitable for monitoring fatigue during the performance of functional activities.

Breathing is a vital function intrinsic to the survival of any human being. In preterm infants it is an important indicator of maturation and feeding competency, which is a hallmark for hospital release. The recommended method of measurement of infant respiration is the use of thermistors. Accurate event detection within thermistor generated signals relies heavily upon effective noise reduction, specifically baseline drift removal. Baseline drift originates from several sensor-based factors, including thermistor placement within the sensor and in relation to the infant nares. This work compares four methods for baseline drift removal using the same event detection algorithm. The methods compared were a linear spline subtraction, a cubic spline subtraction, a neural network baseline approximation, and a double differentiation of the thermistor signal. The method yielding the highest event detection rate was shown to be the double differentiation method, which serves to attenuate the baseline drift to zero without approximating and subtracting it.

The eyes are acoustically continuous with the brain and inner ear tissues in regard to matched impedances, based on tissue densities, thus, vibration of one site will be reflected in all sites. With this being the case, the vibrational energy response of the eye due to an external source can be used to determine a correlation or draw a conclusion concerning the vibrational energy response of the brain would be. And since there is a correlation between the vibrational energies, any changes in the acoustical energy in the eye can possibly be used to determine the changes in acoustical energy in the brain. Such an assertion was tested using the eye/balloon model, in which frequency specific tones can be used to analyze the vibrational response of the eye and the coupled brain. Changes in the intracranial pressure via the vibrational response induce changes in the intraocular pressure via the vibrational principle. Further, the model supports the observation that vibration delivered to the eye can be perceived as sound, if of sufficient intensity, resulting in an eye audiogram similar in degree to that obtained conventionally by bone conduction on the mastoid or forehead. The literature is suggestive that there is no positive correlation between IOP and ICP in terms of pressure, but there is a correlation when acoustical response is measured. This supports the possibility of measuring the changes in acoustical properties on the eye and within the cranium due to any external disruptions. The eye can therefore be considered an acoustical window to the brain and inner ear.