Direct Ink Writing of Flexible Piezoelectric Sensors

Piezoelectric poly(vinylidene fluoride-co-trifluoroethylene), or PVDF-trFE, builds up significant electrical charges on its surface when stressed. By correlating the mechanical force with the resulting electrical charges or voltages, researchers have developed flexible, broadband, and biocompatible force sensors. PVDF-trFE force sensors are traditionally fabricated via spin coating or solvent casting, which result in large waste production and experience difficulties in forming complex geometries. To tackle these challenges, I leveraged a commercial direct ink writing system (nScrypt microdispenser) to additively manufacture PVDF-trFE force sensors. I first synthesized an unprecedented piezoelectric ink that is compatible with a commercial ink writing system at Boise State University, specifically the nScrypt microdispenser, by dissolving PVDF-trFE powders into a cosolvent system consisting of methyl ethyl ketone and dimethyl sulfoxide. The ink composition and substrate surface properties were optimized simultaneously to ensure consistent and uniform printing. Postprocessing procedures, including air-drying, thermal curing, electrical poling and non-contact corona poling were then investigated to facilitate polymerization and beta phase transformation in the printed PVDF-trFE films. With the knowledge acquired from these investigations, I prototyped a piezoelectric force sensor consisting of printed PVDF-trFE films and printed silver electrodes. From justifying the methods for sensor fabrication, unprecedented prototypes of PVDF-trFE sensor arrays were investigated

Death and Dying in Assisted Living

This study examined death and dying in assisted living (AL) and the various factors that influence these processes. The study is set in a 60-bed assisted living facility outside of Atlanta, Georgia. Data collection methods included participant observation and in-depth interviews with 28 residents and 6 staff. Data were analyzed using the grounded theory approach and focused on the 18 residents who were dying and/or died during the study period. Findings show that AL residents experience a variety of dying trajectories that vary in duration and shape; for the majority of residents, hospice is an important element in their death and dying experiences. In general, death is not communicated or acknowledged formally within the facility. Responses to deaths depend largely on the nature of the relationship the deceased resident had with others. Findings have implications for how to handle death and dying in AL and to improve residents‟ experiences

Effects of long-term inputs of fertiliser and irrigation on soil carbon under grazed pasture

Objective: To investigate and quantify the effects of long-term increases in pasture production caused by variable inputs of fertiliser and irrigation on soil profile carbon under permanent grazed pasture.Funding provided by the Agricultural and Marketing Research and Development Trust, The New Zealand Ministry of Agriculture and Forestry, and Environment Canterbury

Проблема здоровьесбережения детей в современной России

Pretreatment of mixed softwoods with SO2 impregnation and steam for production of ethanol has been investigated. The optimal conditions, both for sugar yield and ethanol yield, to assess the effect of inhibitors formed in the pretreatment, have been determined. The parameters investigated were: SO2 concentration (1-6% (w/w) dry matter), temperature (190-230 degrees C) and residence time (2-15 min). After pretreatment, the material was separated into a solid residue and a filtrate. The solid residue was enzymatically hydrolysed with 2% dry matter (w/w). To investigate fermentability, the hydrolysed filtrate was fermented using Saccharomyces cerevisiae. The effects of the different parameters are described by response-surface modelling. The highest experimental sugar yield of 42.1 g per 100 g dry matter was obtained at 210 degrees C and 5.5 min residence time. Although the fermentabilities were good for all filtrates with yields greater than 90% of the yield obtained in a pure glucose reference solution, the pretreatment has a clear influence on the ethanol production rate. (C) 1998 SCI

Evaluating concentration estimation errors in ELISA microarray experiments

BACKGROUND: Enzyme-linked immunosorbent assay (ELISA) is a standard immunoassay to estimate a protein's concentration in a sample. Deploying ELISA in a microarray format permits simultaneous estimation of the concentrations of numerous proteins in a small sample. These estimates, however, are uncertain due to processing error and biological variability. Evaluating estimation error is critical to interpreting biological significance and improving the ELISA microarray process. Estimation error evaluation must be automated to realize a reliable high-throughput ELISA microarray system. In this paper, we present a statistical method based on propagation of error to evaluate concentration estimation errors in the ELISA microarray process. Although propagation of error is central to this method and the focus of this paper, it is most effective only when comparable data are available. Therefore, we briefly discuss the roles of experimental design, data screening, normalization, and statistical diagnostics when evaluating ELISA microarray concentration estimation errors. RESULTS: We use an ELISA microarray investigation of breast cancer biomarkers to illustrate the evaluation of concentration estimation errors. The illustration begins with a description of the design and resulting data, followed by a brief discussion of data screening and normalization. In our illustration, we fit a standard curve to the screened and normalized data, review the modeling diagnostics, and apply propagation of error. We summarize the results with a simple, three-panel diagnostic visualization featuring a scatterplot of the standard data with logistic standard curve and 95% confidence intervals, an annotated histogram of sample measurements, and a plot of the 95% concentration coefficient of variation, or relative error, as a function of concentration. CONCLUSIONS: This statistical method should be of value in the rapid evaluation and quality control of high-throughput ELISA microarray analyses. Applying propagation of error to a variety of ELISA microarray concentration estimation models is straightforward. Displaying the results in the three-panel layout succinctly summarizes both the standard and sample data while providing an informative critique of applicability of the fitted model, the uncertainty in concentration estimates, and the quality of both the experiment and the ELISA microarray process

Investigating neurogenic bowel in experimental spinal cord injury: where to begin?

The devastating losses following traumatic spinal cord injury (SCI) encompass the motor, sensory and autonomic nervous systems. Neurogenic bowel is a slow transit colonic dysfunction marked by constipation, rectal evacuation difficulties, decreased anorectal sensation, fecal incontinence or some combination thereof. Furthermore, neurogenic bowel is one of the most prevalent comorbidities of SCI and is recognized by afflicted individuals and caregivers as a lifelong physical and psychological challenge that profoundly affects quality of life. The restoration of post-injury control of movement has received considerable scientific scrutiny yet the daily necessity of voiding the bowel and bladder remains critically under-investigated. Subsequently, physicians and caregivers are rarely presented with consistent, evidence-based strategies to successfully address the consequences of dysregulated voiding reflexes. Neurogenic bowel is commonly believed to result from the interruption of the supraspinal control of the spinal autonomic circuits regulating the colon. In this mini-review, we discuss the clinical challenges presented by neurogenic bowel and emerging pre-clinical evidence that is revealing that SCI also initiates functional remodeling of the colonic wall concurrent with a decrease in local enteric neurons. Since the enteric input to the colonic smooth muscle is the final common pathway for functional contractions of the colon, changes to the neuromuscular interface must first be understood in order to maximize the efficacy of therapeutic interventions targeting colonic dysfunction following SCI

Latent stem and progenitor cells in the hippocampus are activated by neural excitation

The regulated production of neurons in the hippocampus throughout life underpins important brain functions such as learning and memory. Surprisingly, however, studies have so far failed to identify a resident hippocampal stem cell capable of providing the renewable source of these neurons. Here, we report that depolarizing levels of KCl produce a threefold increase in the number of neurospheres generated from the adult mouse hippocampus. Most interestingly, however, depolarizing levels of KCl led to the emergence of a small subpopulation of precursors (approximately eight per hippocampus) with the capacity to generate very large neurospheres (>250 µm in diameter). Many of these contained cells that displayed the cardinal properties of stem cells: multipotentiality and self-renewal. In contrast, the same conditions led to the opposite effect in the other main neurogenic region of the brain, the subventricular zone, in which neurosphere numbers decreased by ~40% in response to depolarizing levels of KCl. Most importantly, we also show that the latent hippocampal progenitor population can be activated in vivo in response to prolonged neural activity found in status epilepticus. This work provides the first direct evidence of a latent precursor and stem cell population in the adult hippocampus, which is able to be activated by neural activity. Because the latent population is also demonstrated to reside in the aged animal, defining the precise mechanisms that underlie its activation may provide a means to combat the cognitive deficits associated with a decline in neurogenesis