Improving Suturing Skills for Surgical Residents and Advancing Prosthesis Control for Amputees.

Proper suturing technique is one of the most important skills a surgical resident should acquire. However, current methods for teaching it rely on subjective performance evaluations. An instrumented training apparatus for abdominal closure could be used to define objective assessments that directly relate to closure quality. I identify a synthetic material that models abdominal fascia using porcine and cadaveric data and design a means to mount the material so that it mimics abdominal closure. Digital images are used to quantify material deformations and provide real-time objective measures regarding the effect of suture placement and tension in the abdominal tissue. In parallel, I develop a finite element model of abdominal fascia and its closure with suture to deduce stresses in the material and forces in the sutures. I find that despite uniform suture spacing, the forces in suture are unevenly distributed along the closure. These findings motivate the development of a surgical learning tool that objectively relays information about suture placement and tension. In a second body of work, I address the development of a novel interface between an amputee’s peripheral nervous system and a motorized prosthetic device. Conventional myoelectric control cannot produce a sufficient number of independent signals for actuation of modern computerized upper limb prostheses. A compact construct involving grafted muscle surgically prepared at the end of a transected peripheral nerve is envisioned for transducing a nervous signal with fine specificity and sensitivity. Up to 20 such constructs can be prepared in a human arm, and epimysial electrodes on each construct can be used to relay signals encoding 20 independent channels of motor intent. I develop a means of evaluating this construct in awake rats, and demonstrate that the transduced signals suffer minimal crosstalk and are correlated with gait. A decoder is able to reconstruct data produced by motion tracking, and I show that adjacent constructs placed proximal to one another provide the same signals as anatomically intact muscle-nerve antagonist-pair analogs. The correlation between the signals transduced, the walking kinematics, and analogous out of phase activation obtained from adjacent constructs indicates that this technology holds promise for human translation.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147635/1/danursu_1.pd

Synthesis of ultrafine gahnite (ZnAI20 4) nanocrystals by coprecipitation method

Nanocrystalline zinc aluminate ZnAl20 4 has been obtained by coprecipitation method at two different temperatures (800°C and 900°C). The precursors used in coprecipitation synthesis of ZnAECE were zinc nitrate hexahydrate and aluminum nitrate nonahydrate. As a basic source sodium hydroxide was used. The obtained samples were analyzed by X-ray diffraction (XRD) and by energy dispersive spectroscopy (EDAX). Optical properties of nanocrystalline zinc aluminate were also determined by UV/VIS/NIR spectroscopy. The band gap for sample obtained at 800°C was 3,88 eV while for sample obtained at 900°C was 3,97 eV

A low cost linear parabolic concentrator system-photoreactor for photocatalytic processes that uses natural solar light

PdS/CdS based photocatalysts exhibit high efficiency in water splitting reaction. Due to the fact that the band gap value of CdS is 2.4 eV, the photocatalytic process may be performed using visible light at temperatures between 20 and 80°C. From our previous work we noticed that the yield of water splitting process, using this type of photocatalysts increases with the increase of temperature from 20 to 60°C. To increase the temperature of the photocatalystsuspension at higher values than the environment temperature, an irradiance greater than 1000 W/m2 is needed. In this paper we present the design and construction of an inexpensive solar collector –photoreactorassembly, by which the optimal temperature of photocatalystsuspension can be maintained,even in low solar irradiance conditions