Infrared laser spectroscopy of isolated biomolecules in superfluid helium nanodroplets

The focus of this thesis is the identification and structural characterization of iso- lated biomolecules in superfluid helium nanodroplets. We have recently developed structural tools for studying isolated biomolecules, including nucleic acid bases (NABs) (cytosine, guanine, uracil, thymine, and adenine), their mono-hydrated complexes and other biologically important molecules, using high resolution infrared laser spectroscopy. The structural tool called vibrational transition moment angle (VTMA) has been developed for measuring the angle between the permanent dipole moment and transition dipole directions in these species and provides unambiguous structural determinations for many systems. This is a very powerful technique, especially for larger systems, be- cause relatively low level ab initio calculations are able to predict the correct VTMA, when the calculated and experimental vibrational frequencies do not agree. Another powerful tool for structural determination is used to determine the dipole moments of various isomers by measuring the intensity of a particular band as a function of direct current electric field. We have applied these new techniques to the study of the isolated biomolecules, such as tautomerism of NABs, their nonplanarities, energetics, and the intermolecular interactions in the hydrated NABs. These results provide benchmarks for the evaluation of ab initio calculations being carried out on these systems

Highly Sensitive Hydrazine Chemical Sensor Based on CNT-PdPt Nanocomposites

Bimetallic PdPt nanoparticles were prepared using the chemical reduction method. The PdPt nanoparticles were successfully deposited on thiolated carbon nanotubes (CNTs) to form a CNT-PdPt nanocomposite as an electron mediator for the fabrication of a hydrazine sensor. The PdPt nanoparticles had an average particle size of 2.3 nm and were well dispersed on the surfaces of the CNTs in the prepared CNT-PdPt nanocomposite, as demonstrated using transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Based on X-ray photoelectron spectroscopy (XPS) results, the estimated proportions of Pd and Pt in the CNT-PdPt nanocomposite were approximately 3.0% and 3.2%, respectively. A fabricated chemical sensor based on CNT-PdPt was found to exhibit better amperometric activity with respect to the hydrazine oxidation reaction than CNT-Pd, CNT-Pt, and commercial Pd/C and Pt/C catalysts. This sensor exhibited a linear range of 0.55–1,200 μM and a detection limit of 0.28 μM (S/N = 3) with a fast response time (within 5 s). Furthermore, the sensor could be used repeatedly for the consecutive detection of hydrazine with good reusability and storage stability. These properties demonstrate that the CNT-PdPt nanocomposite is a promising electron mediator for the fabrication of amperometric hydrazine sensors

Learning Curve Associated with Complications in Biportal Endoscopic Spinal Surgery: Challenges and Strategies

Study DesignDescriptions of technical strategies to overcome pitfalls associated with early learning periods in biportal endoscopic spinal surgery (BESS).PurposeTo introduce BESS for lumbar spinal diseases (LSDs) and to inform certain challenges to be overcome in mastering the technique.Overview of LiteratureBESS has shown superior benefits including excellent magnification, a wider range of view by dynamic handling of an endoscope and instruments. Clinical reports, however, have not yet been very revealing for its new introduction into minimally invasive spine surgery.MethodsTo evaluate the learning curve for BESS, the procedures for various LSDs by one surgeon were analyzed in the view of shortening of the operating times and reduction of complications. Reviewing of recorded procedures helped in finding the reasons and the implemented solutions.ResultsThe 68 cases included 25 for lumbar disc herniation (LDH), 3 for revision for recurred LDH, 39 for lumbar spinal stenosis (LSS) and 1 for synovial cyst. The operation time for the total cases averaged 83.7±33.6 minutes. According to diagnosis, it was 68.2±23.7 minutes for LDH. After the 14th case of LDH, it was nearly constant and close to the average time. One level of LSS needed 110.4±34.4 minutes. Prolonged operation times even in some later cases of LSS were mainly from struggling against blurred vision due to epidural bleeding. There were 7 cases of complications (10.3%) including 2 cases of dural tear, 1 case of root injury, and 4 cases of incomplete decompression on postoperative magnetic resonance imaging. There was no case of symptomatic hematoma or wound infection.ConclusionsBESS seemed to have a relatively short learning curve period. The overall complication rate in early learning period was 10.3%. These could be avoided by magnified regional views on an endoscope and a clear surgical field by controlling epidural bleeding

Feasibility and Safety of Extensive Upper Abdominal Surgery in Elderly Patients with Advanced Epithelial Ovarian Cancer

We performed a retrospective study to evaluate the feasibility and safety of extensive upper abdominal surgery (EUAS) in elderly (≥65 yr) patients with advanced ovarian cancer. Records of patients with advanced epithelial ovarian cancer who received surgery at our institution between January 2001 and June 2005 were reviewed. A total of 137 patients including 32 (20.9%) elderly patients were identified. Co-morbidities were present in 37.5% of the elderly patients. Optimal cytoreduction was feasible in 87.5% of the elderly while 95.2% of young patients were optimally debulked (P=0.237). Among 77 patients who received one or more EUAS procedures, 16 (20.8%) were elderly. Within the cohort, the complication profile was not significantly different between the young and the elderly, except for pleural effusion and pneumothorax (P=0.028). Elderly patients who received 2 or more EUAS procedures, when compared to those 1 or less EUAS procedure, had significantly longer operation times (P=0.009), greater blood loss (P=0.002) and more intraoperative transfusions (P=0.030). EUAS procedures are feasible in elderly patients with good general condition. However, cautious peri-operative care should be given to this group because of their vulnerability to pulmonary complications and multiple EUAS procedures

Survival outcomes of hepatic resection compared with transarterial chemoembolization or sorafenib for hepatocellular carcinoma with portal vein tumor thrombosis

Background/Aims:Treating hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT) remains controversial. We compared the outcomes of hepatic resection (HR), transarterial chemoembolization (TACE), and sorafenib therapy as treatments for HCC with PVTT. Methods:Patients diagnosed as HCC with PVTT between January 2000 and December 2011 who received treatment with sorafenib, HR, or TACE were included. Patients with main PVTT, superior mesenteric vein tumor thrombosis, or Child-Turcotte-Pugh (CTP) class C were excluded. The records of 172 patients were analyzed retrospectively. HR, TACE, and sorafenib treatment were performed is 40, 80, and 52 patients respectively. PVTT was classified as either involving the segmental branch (type I) or extending to involve the right or left portal vein (type II). Results:The median survival time was significantly longer in the HR group (19.9 months) than in the TACE and sorafenib groups (6.6 and 6.2 months, respectively; both p<0.001), and did not differ significantly between the latter two groups (p=0.698). Among patients with CTP class A, type I PVTT or unilobar-involved HCC, the median survival time was longer in the HR group than in the TACE and sorafenib groups (p=0.006). In univariate analyses, the initial treatment method, tumor size, PVTT type, involved lobe, CTP class, and presence of cirrhosis or ascites were correlated with overall survival. The significant prognostic factors for overall survival in Cox proportional-hazards regression analysis were initial treatment method (HR vs. TACE: hazard ratio=1.750, p=0.036; HR vs. sorafenib: hazard ratio=2.262, p=0.006), involved lobe (hazard ratio=1.705, p=0.008), PVTT type (hazard ratio=1.617, p=0.013), and CTP class (hazard ratio=1.712, p=0.012). Conclusions:Compared with TACE or sorafenib, HR may prolong the survival of patients with HCC in cases of CTP class A, type I PVTT or unilobar-involved HCC

STUDIES OF HYDRATED NUCLEIC ACID BASE CLUSTER CONFORMERS SOLVATED IN HELIUM NANODROPLETS: VIBRATIONAL TRANSITION MOMENT ANGLES (VTMAS) MEASUREMENTS.

Author Institution: Department of Chemistry, University of North CarolinaMultiple isomers of nucleic acid base (NAB)-water complexes formed in superfluid helium nanodroplets are studied by high resolution infrared laser spectroscopy. The identification and structural characterization of several tautomeric biomolecule-water complexes (e.g. uracil-water, cytosine-water, adenine-water, and etc.) will be presented. We describe here a tool, which aids in the assignment of each vibrational band by measuring the direction of the vibrational transition moment for the corresponding band. High level ab initio calculations are used to obtain theoretical VTMAs for comparison with experimental values

Specific Solvent Produces Specific Phase Ni Nanoparticles: A Pulsed Laser Ablation in Solvents

In this paper, we present a simple and controllable preparation of face centered cubic (fcc) and hexagonal close-packed (hcp) Ni nanoparticles by a pulsed Nd:YAG laser ablation method in the following four solvents: deionized water, methanol, hexane, and acetonitrile. We generated Ni/NiO, fcc, and/or hcp Ni nanoparticles by primary ablation to a Ni plate submerged in various solvents, followed by secondary ablation to the colloidal solutions. Interestingly, the phases of Ni nanoparticles prepared via a pulsed laser ablation in liquid (PLAL) show a strong dependence on the solvents used in the ablation processes. Ni/NiO, pure fcc, and a mixture of fcc and hcp Ni nanoparticles were generated in DI water, methanol, and hexane or acetonitrile, respectively. After secondary ablation, however, pure fcc Ni nanoparticles were generated in methanol and hexane, while pure hcp Ni was formed in acetonitrile. We think that the solvent dependence on the phase of Ni nanocrystals is related to the specific heat of solvents which plays an important role kinetically and thermodynamically in the process of cooling the plasma plume where the nanoparticles nucleate and coalesce to a specific phase. The Ni nanoparticles prepared from PLAL were analyzed by X-ray diffraction (XRD) measurement, X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), high resolution-transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED), and fast Fourier transform (FFT) analysis