Department Seminar Speakers - 2010
- Dr. Tirandai Hemraj-Benny (QCC, CUNY)
- December 3, 2010
- Title: "Investigating Fundamental Properties of Single-Walled Carbon Nanotubes"
- Abstract: Allotropes of carbon include diamond, graphite and single-walled carbon nanotubes (SWNTs). SWNTs are widely known at a fundamental research point of view for their unique structural, electronic and mechanical properties. However, before they can reach their full potential in practical and affordable applications, in areas such as biological, electronics and materials, issues such as solubility, de-bundling and homogeneity of nanotube type need to be resolved. To address issues of de-bundling, an initial understanding of the oxidation process of SWNTs by nitric acid treatment was investigated. The resulting surface functionalities were systematically identified by Mid-IR spectroscopy. In addition, studies were conducted to understand the coordination of metal nanoparticles onto un-functionalized SWNTs. The integration of one-dimensional nanotubes with zero-dimensional nanoparticles (NPs) to form hybrid structures have shown to have great potential applications. In this study, we specifically investigated the growth of palladium and silver nanoparticles onto raw, pristine SWNTs. The SWNT-NP hybrid systems were characterized by High Resolution Transmission Electron microscopy (HR-TEM), Energy Dispersive X-ray Spectroscopy (EDX), UV-Vis and Infrared Spectroscopy.
- Dr. Klaus Grohmann (Professor (Emeritus), Hunter College)
- November 12, 2010
- Title: "The RCM Approach to 3,4-Benz-1,6-Methano-  and -annulene and 1,5-Bisdehydroannulene Revisited"
- Abstract: As part of our research on unusual annulenes, we have been been in¬terested in the effect of mono-benz-annelation on the aromatic¬ity/antiaromaticity of bridged annulenes such as 2 and elusive an¬nulenes such as 1,5-bisdehydr annulene 3. In this presentation a new synthesis of 3,4-benz-1,6 methanoannulene 2 is dis-cussed. This synthesis starts from the readily available 3,4-benz-1,3,5-cycloheptatriene-1,6-dialdehyde 1, has a Ring Closing Olefin Metathesis (RCM) as a key step, and is applicable to other ring sizes. X-ray and NMR data characterize 2 as a paratropic sys¬tem with a slightly reduced paramagnetic ring current relative to the parent 1,6-methanoannulene that was first reported by the Vogel group. Progress in our synthesis of 3,4-annelated 1,5 bisdehydrannulene 3 will also be presented.
- Prof. Linda C. Rourke (John Jay College)
- October 8, 2010
- Title: "Blood, Sweat, Tears…and other Physical Evidence"
- Abstract: In the last fifteen years, the popularization of forensic science by the media has resulted in many misconceptions by the public. This phenomenon has been called the CSI Effect and has had repercussions throughout the field of criminal justice. This presentation will use case examples to emphasize the necessity of a strong science foundation in the field of forensic science and describe the academic curriculum necessary to prepare for a career in this discipline.
- Dr. Elise Champeil (John Jay College)
- April 30, 2010
- Title: "Identification and quantitation of 3,4-methylenedioxy-N-methylamphetamine (MDMA, ecstasy) in human urine by 1H NMR spectroscopy. Application to five cases of intoxication"
- Abstract: Drug testing in urine is a common technique used today. Current methods of testing urine for drugs and their metabolites include HPLC, GC-MS, or immunoassay analysis. These methods all have their drawbacks. Recently, nuclear magnetic resonance, (NMR), has emerged as a means of analyzing drugs and drug metabolites in urine. There is literature precedence describing the use of NMR spectroscopy to identify compounds in urine from intoxication. There are many benefits to using NMR spectroscopy: NMR is non-destructive and samples can be analyzed as many times as desired. There is also little sample preparation required.
3,4-methylenedioxy-N-methylamphetamine, more commonly called MDMA or “ecstasy”, is a synthetic drug similar in structure to methamphetamine.
In this project, we investigated the practicality of using NMR spectroscopy to detect and quantify the presence of 3,4-methylenedioxy-N-methylamphetamine (MDMA or ecstasy) in human urine.
We first established a calibration curve with spiked samples of real urine. To determine the standard deviation, seven independent urine samples spiked with the different compounds at a concentration of 0.05mg/mL were run. Variance (S2) and standard deviation (S) of the measurements were calculated.
As for the LOD, the very nature of NMR makes it impossible to determine as it depends on the amount of scans used for the experiment. In this study we have limited the experimental time to overnight experiments, allowing a quantification in the 0.01 mg/mL concentrations range.
Following this, real urine samples from MDMA users were analyzed. The real samples were collected following an IRB approved protocol. Five different samples were collected. This presentation discusses the spectra of the urine obtained from these 5 volunteers. Figure one shows the spectrum of the first sample. Surimposed in gray is the spectrum of MDMA spiked urine (0.50 mg/mL). All peaks for the protons of MDMA are clearly visible.
These results suggest the 1H NMR spectroscopy could provide a convenient tool for the rapid detection of MDMA in human urine. This method presents the advantage of a rapid diagnosis with little of urine needed and no sample preparation. Furthermore, samples were analyzed within 20-30 minutes. The NMR method should be useful in rapidly confirming the diagnosis of poisoning.
The limitation of using NMR for the identification of MDMA is that at lower concentrations, the presence of small amounts of metabolites or other therapeutic agents can interfere. In that case, the quantification procedure can be difficult.
- Dr. Wilma Saffran (Queens College, CUNY)
- March 26, 2010
- Title: "Genotoxic Changes Induced by DNA Interstrand Crosslinks"
- Abstract: DNA interstrand crosslinks (ICLs) are extremely cytotoxic to proliferating cells, and for this reason crosslinking agents are widely used in cancer chemotherapy. Psoralens are photoreactive crosslinking agents that form ICLs in the presence of near UV light, and are used in the treatment of psoriasis. ICLs can be repaired, but require the interactions of several DNA repair pathways; the repair process can produce genotoxic effects, such as DNA mutations and rearrangements. These genetic changes can lead to cancer, and psoralen phototherapy has been found to induce skin cancer in psoriasis patients. In the yeast Saccharomyces cerevisiae psoralen ICLs require three DNA repair pathways. Nucleotide excision repair is error-free, but acts on single strands and cannot fully repair ICLs. Repair of these double strand lesions must be completed by additional pathways. Homologous recombination repairs double strand damage, but produces DNA rearrangements. Post-replication repair can bypass lesions, but is error-prone and generates mutations. Repair-proficient yeast cells repair ICLs with low levels of mutations and DNA rearrangements. Deficiencies in any of the DNA repair pathways increase the levels of genotoxic effects. Loss of homologous recombination increases the incidence of mutations and of deletions. In the absence of post-replication repair the mutation frequency is lower but deletions and other rearrangements are increased.