Gold nanoparticles are produced in some plants when soluble gold is present in the growth medium nutrients. Release and recovery of this gold by pyrolysis can sinter the particles, and enzymatic digestion is proposed ...
详细信息
ISBN:
(纸本)081691012X
Gold nanoparticles are produced in some plants when soluble gold is present in the growth medium nutrients. Release and recovery of this gold by pyrolysis can sinter the particles, and enzymatic digestion is proposed as an alternative. Brassica juncea grown on soil containing low levels of gold, copper and silver (22-48 mg Au kg-1, 44-45 mg Cu kg-1 and 0-31 mg Ag kg -1 respectively) contained gold at weight concentrations circa 1000 ppm dry matter. 55-60 wt% of the dried plant matter was solubilised by enzymatic digestion, but 50-60% of the gold initially present was lost to solution during the digestion. XANES analysis shows that gold is present in the plant in approximately equal quantities in the metallic (Auo) and oxidized (Au+1) states. The gold lost during digestion is thought to be gold present in the plant in a soluble form (Au+1).
Mathematical models are often used in system identification applications. The dynamics of most systems, however, change over time and the sources of these changes cannot always be directly determined or measured. To m...
详细信息
Short duration, fast rise time ultra-wideband (UWB) electromagnetic pulses (“nanopulses”) are generated by numerous electronic devices in use today. Moreover, many new technologies involving nanopulses are under dev...
Short duration, fast rise time ultra-wideband (UWB) electromagnetic pulses (“nanopulses”) are generated by numerous electronic devices in use today. Moreover, many new technologies involving nanopulses are under development and expected to become widely available soon. Study of nanopulse bioeffects is needed to probe their useful range in possible biomedical and biotechnological applications, and to ensure human safety. In this work we develop a computational approach to investigate electromagnetic fields in biological cells exposed to nanopulses. The simulation is based on a z-transformation of the electric displacement and a second-order Taylor approximation of a Cole–Cole expression for the frequency dependence of the dielectric properties of tissues, useful for converting from the frequency domain to the time domain. Maxwell’s equations are then calculated using the finite difference time domain method (FdTd), coupled with a perfectly matched layer to eliminate reflections from the boundary. Numerical results for a biological cell model are presented anddiscussed.
作者:
ERIC L. SEVIGNYJONATHAN P. CAULKINSEric L. Sevigny
is a Ph.D. student in the Graduate School of Public and International Affairs at the University of Pittsburgh. Mr. Sevigny's research interests lie in the area of drug policy with an emphasis on enforcement sanctioning international control and treatment/harm reduction. His previous experience includes substance abuse counseling and substance abuse treatment needs research of special populations including prisoners the homeless and adolescents. Mr. Sevigny received a B.A. in Psychology from Middlebury College. Jonathan P. Caulkins
Ph.D. is Professor of Operations Research and Public Policy at Carnegie Mellon University's Heinz School of Public Policy. Dr. Caulkins specializes in mathematical modeling and systems analysis of social policy problems with a particular focus on issues pertaining to drugs crime violence and prevention. Dr. Caulkins has also published on airline operations sulfur dioxide pollution trading markets Internet-based advertising flexible manufacturing systems and personnel performance evaluation among other topics. At RAND he has been a consultant visiting scientist codirector of RAND's Drug Policy Research Center (1994–1996) and founding director of RAND's Pittsburgh office (1999–2001). Dr. Caulkins received a B.S. and M.S. in Systems Science from Washington University and an S.M. in Electrical Engineering and Computer Science and Ph.D. in Operations Research both from M.I.T.
Research Summary: drug policy reformers anddefenders contest the extent to which low-level drug offenders are being sent to prison and for how long. Using data from the Survey of Inmates in Federal and State Correcti...
详细信息
Research Summary: drug policy reformers anddefenders contest the extent to which low-level drug offenders are being sent to prison and for how long. Using data from the Survey of Inmates in Federal and State Correctional Facilities, 1997 (BJS, 2000), we assess the seriousness of incarcerateddrug offenders along dimensions of dangerousness, culpability, and harm—specifically, functional role anddrug group participation, type and amount of drugs, firearms involvement, and criminal conviction and arrest history. We find that only about 1.6% of federal and 5.7% of state inmates can be described as “unambiguously low-level.” Alternatively, not many are “kingpins.” Rather, most fall into a middle spectrum representing different degrees of seriousness that depend on what factors are emphasized. Policy Implications: Our findings dampen hopes of dramatically reducing prison populations by getting out of prison those who are unambiguously low-level drug offenders. They simply do not represent the majority of incarcerateddrug offenders. In particular, most played some role in distribution, so eliminating prison terms for users (decriminalization) would not have affected many now in prison. Indeed, if decriminalization increaseddemand, it could plausibly increase prison populations by increasing the number of suppliers still subject to imprisonment. On the other hand, “drug courier exceptions” to sentencing laws that apply to minor role offenders possessing large quantities could have a greater prison reduction impact.
The content of dimethylallylamine was determined using glacial acetic acid as solvent, acetic-formic mixture as an anhydrite, perchloric acid-glacial acetic acid as titrant, and 1% crystal violet in acetic acid as ind...
详细信息
The content of dimethylallylamine was determined using glacial acetic acid as solvent, acetic-formic mixture as an anhydrite, perchloric acid-glacial acetic acid as titrant, and 1% crystal violet in acetic acid as indicator in the presence of methylamine anddimethylamine The influences of inert constituents and water on the titration were investigated, and a complete analytical method was determined. The results showed that the determination error of total amines increased with water increasing, while the effect of water on the determination of dimethylallylamine was little when the amount of water was within 5%, the relative error was generally within 1%, and that the end-point was acutely when about 10% chloroform was added. Compared with gas chromatography, this method is simple, convenient and accurate.
dynamic programming (dP) is a principled way to design optimal controllers for certain classes of nonlinear systems;unfortunately, dP is computationally very expensive. The Reinforcement Learning methods known as Adap...
详细信息
dynamic programming (dP) is a principled way to design optimal controllers for certain classes of nonlinear systems;unfortunately, dP is computationally very expensive. The Reinforcement Learning methods known as Adaptive Critics (AC) provide computationally feasible means for performing approximate dynamic programming (AdP). The term 'adaptive ' in A C refers to the critic 's improved estimations of the Value Function used by dP. To apply dP, the user must craft a Utility function that embodies all the problem-specific design specifications/criteria. Model Reference Adaptive Control methods have been successfully used in the control community to effect on-line redesign of a controller in response to variations in plant parameters, with the idea that the resulting closed loop system dynamics will mimic those of a Reference Model. The work reported here 1) uses a reference model in AdP as the key information input to the Utility function, and 2) uses AdP off-line to design the desired controller. Future work will extend this to on-line application. This method is demonstrated for a hypersonic shaped airplane called LoFL YTE®;its handling characteristics are natively a little "hotter" than a pilot woulddesire. A control augmentation subsystem is designed using AdP to make the plane "feel like " a better behaved one, as specified by a Reference Model. The number of inputs to the successfully designed controller are among the largest seen in the literature to date.
A fourth-order compact finite difference scheme is developed for solving the 1-d Pennes' bioheat transfer equation. Numerical results show that the scheme is more accurate than the Crank-Nicholson scheme.
ISBN:
(纸本)1932415041
A fourth-order compact finite difference scheme is developed for solving the 1-d Pennes' bioheat transfer equation. Numerical results show that the scheme is more accurate than the Crank-Nicholson scheme.
We describe a computer model of intracranial pressure (ICP) dynamics that evaluates clinical treatment options for elevated ICP during traumatic brain injury (TBI). The model uses fluid volumes as primary state variab...
详细信息
We describe a computer model of intracranial pressure (ICP) dynamics that evaluates clinical treatment options for elevated ICP during traumatic brain injury (TBI). The model uses fluid volumes as primary state variables and explicitly models fluid flows as well as the resistance, compliance, and pressure associated with each intra- and extracranial compartment (arteries and arterioles, capillary bed, veins, venous sinus, ventricles, and brain parenchyma). The model evaluates clinical events and therapies such as intraand extra-parenchymal hemorrhage, cerebral edema, cerebrospinal fluiddrainage, mannitol administration, head elevation, and mild hyperventilation. The model is able to replicate observed clinical behavior in many cases, including elevated ICP associated with severe cerebral edema following subdural, epidural, or intraparenchymal hematoma. The model also mimics cerebrovascular regulatory mechanisms that are activatedduring TBI.
暂无评论