4,244 research outputs found
Evaluation of advanced combustion concepts for dry NO sub x suppression with coal-derived, gaseous fuels
The emissions performance of a rich lean combustor (developed for liquid fuels) was determined for combustion of simulated coal gases ranging in heating value from 167 to 244 Btu/scf (7.0 to 10.3 MJ/NCM). The 244 Btu/scf gas is typical of the product gas from an oxygen blown gasifier, while the 167 Btu/scf gas is similar to that from an air blown gasifier. NOx performance of the rich lean combustor did not meet program goals with the 244 Btu/scf gas because of high thermal NOx, similar to levels expected from conventional lean burning combustors. The NOx emissions are attributed to inadequate fuel air mixing in the rich stage resulting from the design of the large central fuel nozzle delivering 71% of the total gas flow. NOx yield from ammonia injected into the fuel gas decreased rapidly with increasing ammonia level, and is projected to be less than 10% at NH3 levels of 0.5% or higher. NOx generation from NH3 is significant at ammonia concentrations significantly less than 0.5%. These levels may occur depending on fuel gas cleanup system design. CO emissions, combustion efficiency, smoke and other operational performance parameters were satisfactory. A test was completed with a catalytic combustor concept with petroleum distillate fuel. Reactor stage NOx emissions were low (1.4g NOx/kg fuel). CO emissions and combustion efficiency were satisfactory. Airflow split instabilities occurred which eventually led to test termination
Self Concept and Achievement Among Elementary Students in an Experimental Program
Problem: The main purpose of this study was to investigate the direction and degree of relationship between self concept and academic achievement among elementary students in an experimental program. A second purpose was to determine the amount and direction of change in the teachers\u27 perception of the students.
Procedure: The research population was selected from students and staff in the Carl Ben Eielson and Nathan Twining Elementary Schools, in Grand Forks, North Dakota during the 1971-72 school year. These schools were participating in an experimental project, entitled Human Awareness through Self Enhancing Education (HATSEE), which was designed to enhance self concept and attitudes of students and staff.
The sources of data for this study were the Self Appraisal Inventory, the School Sentiment Index, the Class Play, the What Would You Do?, the Iowa Test of Basic Skills, and the Ideal Child Checklist. These instruments were administered to the research population early in the fall and late in the spring of the school year.
The statistical procedures employed in this study consisted of Pearson product-moment correlations, canonical correlations, and related t tests. The .01 and .05 levels were used for interpreting and evaluating the significance of the findings.
Findings: 1. There was a significant difference among students between initial testing and retesting of self concept, on the variables peer (SAI), family, school, general, composite (SAI), peer (SSI), composite (SSI), and Class Play in third grade; school in fourth grade; peer (SAI), family, composite (SAI), subject, and Class Play in fifth grade; learning in sixth grade; structure in seventh grade; and structure in eighth grade.
2. There was a significant difference among students between initial testing and retesting of academic achievement, on the variables reading, language, arithmetic, and composite in third grade; reading in fourth grade; vocabulary and composite in fifth grade; and reading in sixth grade.
3. There was a significant positive canonical correlation between self concept and academic achievement on the initial tests for grades three, five, six, seven, and eight.
4. There was a significant positive canonical correlation between self concept and academic achievement on the retests for grades four, five, six, seven, and eight.
5. There was a significant difference between initial testing and retesting of the teachers\u27 perception of the students, on the characteristics affectionate, remember well, guessing, self sufficient, never bored, talkative, and conforming. The remaining 59 characteristics were nonsignificant .
Conclusions: 1. During the school year the greatest changes in school self concept occurred at the third and fifth grade level. The significant changes in self concept were negative for third grade except for the Class Play and negative for fifth grade except for the family variable.
2. Significant changes in self concept for grades three, four, and five were indicated primarily by the Self Appraisal Inventory and the Class Play. The significant changes in self concept for grades six, seven, and eight were indicated primarily by the School Sentiment Index.
3. In grades three, four, and five there was an increasing number of positive, but not necessarily significant, t values on the self concept variables corresponding to the students increase in age. The same trend occurs with grades six, seven, and eight.
4. The adjusted t values for all the variables of the Iowa Test of Basic Skills were positive for grades three and five, but generally negative for grades four, six, seven, and eight.
5. On both the initial tests and retests the significant zero- order correlations between the ten self concept and five achievement variables were positive except for learning.
6. On both the initial tests and retests the zero-order correlations seem to indicate that the school scale on the Self Appraisal Inventory is the best single self concept predictor of academic achievement as measured by the Iowa Test of Basic Skills.
7. The teachers as a group changed very little, as measured by the Ideal Child Checklist, in their perception of desirable and undesirable characteristics of students
Mechanisms of Nanosecond Pulsed Electric Field (NsPEF)-Induced Cell Death in Cells and Tumors
The evolution of pulse power technology from high power physics to biology and medicine places nanosecond pulsed electric fields (nsPEFs) in positions for in vitro and in vivo applications as non-ligand agonists that not only bypass plasma membrane receptors for induction of intracellular signaling pathways, but also bypass intracellular oncogenic impasses to induce cell death by regulated mechanisms. Based on work reviewed here, a likely scenario for cell and tumor demise includes nsPEF-induced permeabilization of the plasma membrane, Ca2+ influx, dissipation of the mitochondrial membrane potential, which is likely due to events beyond permeabilization of the inner mitochondrial membrane, cytochrome c release and activation of caspase-dependent and -independent cell death mechanisms. In vivo, nsPEF-treated orthotopic rat N1-S1 hepatocellular carcinoma tumors exhibit caspase-9 and caspase-3 positive and –negative tumor cells, indicating intrinsic apoptotic and non-apoptotic cell death. Interestingly, after N1-S1 tumor ablation and clearance, rats are resistant to challenge injections of the same N1-S1 tumor cells, indicating a protective, vaccine-like effect that appears to be due to innate and/ or adaptive immune responses that are under further investigation. This provides additional impetus to further develop nsPEF ablation as a cancer therapy
Cell Responses Without Receptors and Ligands, Using Nanosecond Pulsed Electric Fields (nsPEFs)
Stephen J Beebe Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk VA, USAThe plasma membrane is a lipid bilayer that surrounds and shelters the living structural and metabolic systems within cells. That membrane is replete with transmembrane proteins with and without ligand binding sites, oligosaccharides, and glycolipids on the cell exterior. Information transfer across this structure is closely controlled to maintain homeostasis and regulate cell responses to external stimuli. The plasma membrane is contiguous with the endoplasmic reticulum (ER) and nuclear membranes. A number of proteins form ER–mitochondria junctions, allowing interorganelle communications, especially for calcium transport. Transport mechanisms across these membranes include nongated channels or pores; single-gated channels for ion transport; carrier molecules for facilitated diffusion; and pumps for active transport of ions and macromolecules. During the activation of these transport systems, "pores" are formed through protein structures that transiently connect the intracellular and extracellular milieu. These pores are nanoscale structures with diameters of 0.2−4.0 nm. However, there can also be maligned movements of molecules across the plasma membranes. Staphylococcus aureus protein α-toxin and Streptococcus pyogenes protein streptolysin O both create pores that allow unsolicited molecular transfer across membranes that disrupts vital functions. Cytotoxic T-cells permeabilize the invading cell membranes with perforin, creating pores through which granzymes can induce apoptosis. These pores have a lumen of 5–30 nm with the majority at 13–20 nm.
Bioelectrics in Basic Science and Medicine: Impact of Electric Fields on Cellular Structures and Functions
Bioelectrics is a new interdisciplinary field that investigates electric field effects on cell membranes and other cellular components. It incorporates four main technologies, including electroporation, nanosecond pulsed electric fields, picosecond pulsed electric fields and cold plasmas. The parent technology in Bioelectrics is electroporation, which uses milli- and/or micro-second electric pulses to permeabilize cells and tissues, for delivery of membrane impermeable molecules. It is now being used for electro-gene delivery, with vascular endothelial growth factor, for revascularization in wound healing and cardiovascular and peripheral vascular disease. Plasmids expressing IL-12 are being delivered for immune system activation in melanoma treatment, now in phase II clinical trials. DNA vaccine delivery by electroporation is also being investigated. More recently, electroporation has been extended to include nanosecond pulsed electric fields (nsPEFs), a pulse power technology that was originally designed for military applications. It stores intense levels of electric energy, and then unleashes nanosecond bursts of instantaneous power into cells and tissues, creating unique intracellular conditions of high power and low, non-thermal energy. It is presently being used for cancer ablation of skin and internal tumors, and for platelet activation for wound healing in injury and diabetes. An extension of nsPEFs is to make the pulses even shorter, using picosecond pulsed electric fields. This is being developed as an imaging system to detect cancer and other aberrant tissues, using an antenna. The fourth technology is cold plasmas or ionized gasses, a fourth state of matter. Applications of these ionized gases are being developed for decontaminating wounds, water, food and surfaces. Other possible applications that are of specific interest, but not yet fully investigated, and/or developed, are pain control, fat ablation and decontamination of indwelling catheters. This review will outline some applications of Bioelectrics, with greatest focus on nsPEF effects on cells in vitro and tumors in vivo
Applications for Pulse Power using Nanosecond Pulsed Electric Fields (nsPEFs) in Cell Biology and Cancer Treatment
Real-world comparison of probe vehicle emissions and fuel consumption using diesel and 5 % biodiesel (B5) blend.
An instrumented EURO I Ford Mondeo was used to perform a real-world comparison of vehicle exhaust (carbon dioxide, carbon monoxide, hydrocarbons and oxides of nitrogen) emissions and fuel consumption for diesel and 5% biodiesel in diesel blend (B5) fuels. Data were collected on multiple replicates of three standardised on-road journeys: (1) A simple urban route; (2) A combined urban/inter-urban route; and, (3) An urban route subject to significant traffic management. At the total journey measurement level, data collected here indicate that replacing diesel with a B5 substitute could result in significant increases in both NOx emissions (8-13%) and fuel consumption (7-8%). However, statistical analysis of probe vehicle data demonstrated the limitations of comparisons based on such total journey measurements, i.e., methods analogous to those used in conventional dynamometer/drive cycle fuel comparison studies. Here, methods based on the comparison of speed/acceleration emissions and fuel consumption maps are presented. Significant variations across the speed/acceleration surface indicated that direct emission and fuel consumption impacts were highly dependent on the journey/drive cycle employed. The emission and fuel consumption maps were used both as descriptive tools to characterise impacts and predictive tools to estimate journey-specific emission and fuel consumption effects
Letter from Beebe Thompson
Letter concerning recommendation for position in Domestic Science at Utah Agricultural College
Nanosecond Pulsed Electric Fields: A New Stimulus to Activate Intracellular Signaling
When new technologies are introduced into the sci-entific community, controversy is expected and both ex-citement and disappointment enrich the lives of those who initiate the new ideas. It becomes the mission of the “inventors ” to embrace the burden of proof to estab-lish their ideas and convince the skeptics and disbeliev-ers who will undoubtedly temper their enthusiasm and test their patience. While open mindedness is generally a scientific motto, those who review patents, manuscripts, and grants do not always readily practice it, even when the evidence is convincingly presented; old ideas and concepts often die hard. So it has been and still is in many instances as engineers, physicists, biologists, and physicians pursue innovative ideas and novel technolo-gies. So what is “Bioelectrics”? It is the application of ultra-short pulsed electric fields to biological cells, tissues, and organs. More specifically, it is the analysis of how these bi-ological systems respond to high electric fields (10–100 s of kV/cm) when applied with nanosecond (1–300) dura-tions. Compressing electrical energy by means of pulsed power techniques allows the generation of ultrashort (bil-lionth of a second) electrical pulses [1]. Because the pulses are so short the energy density is quite low and there-fore nonthermal. However, the power is extremely high generating billions of watts. This can be compared to a coal power plant, which generates less than billion watts, but does it continuously. For example, for a 10 ns, 40 kV, 10Ω pulse generator, the power provided by the pulse is 160MW, however, the energy is only 1.6 J. Depositing thi
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