Publications by authors named "Dennis Tran"

4 Publications

  • Page 1 of 1

Application of spin-ratio scaled MP2 for the prediction of intermolecular interactions in chemical systems.

Phys Chem Chem Phys 2017 Nov;19(42):28936-28942

School of Chemistry, Monash University, 17 Rainforest Walk, Clayton, VIC 3800, Australia.

Accurate prediction of intermolecular interactions plays a pivotal role in many areas of chemistry and biology including (but not limited to) the design of pharmaceuticals, solid electrolytes and food additives. Here we present the application of the recently developed spin-ratio scaled MP2 method (termed SRS-MP2) to six different datasets covering a wide range of interaction types from strong hydrogen bonding to van der Waals dispersion and π-π stacking. The method achieves a remarkably low mean absolute error of 1.6 kJ mol across all interaction types including semi-Coulombic systems such as organic ionic salts. The new SRS-MP2 method offers high level of accuracy for studying intermolecular interactions commonly found in molecular systems of chemical and biological relevance without the need for including additional terms in the formulation. This finding represents a new paradigm in the development of wavefunction-based methods for intermolecular interactions.
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November 2017

Gait Training in Patients Discharged to a Skilled Nursing Facility Following Total Joint Arthroplasty.

Geriatr Orthop Surg Rehabil 2016 Mar;7(1):33-8

Division of Adult Reconstruction, Department of Orthopaedic Surgery, NYU Hospital for Joint Diseases, NYU Langone Medical Center, New York, NY, USA.

Background: Expenditures for postacute care in total joint arthroplasty (TJA) have risen dramatically over recent decades. Therefore, efforts are underway to better identify cost savings in postacute rehabilitation centers, such as skilled nursing facilities (SNFs). The primary purpose of this study was to analyze gait training achievements in post-TJA patients in the interval between hospital discharge and the patients' first 4 days at the SNF. Identification of potential losses in therapeutic progress may lead the way for improved patient care, outcomes, and cost savings. Our hypothesis is that patients discharged to an SNF will have a decline in gait achievements upon transfer from the hospital.

Methods: A total of 68 patients who underwent TJA were included. The total distance ambulated during physical therapy (PT) was recorded for the last day of hospital therapy and the first 4 days at the SNF as well as the reported visual analog scale (VAS) pain scores.

Results: There was a 73% decline in distance ambulated on SNF day 0 (Hospital: 138.6 ft vs SNF: 37.9 ft; P < .001) and a 50% decline on SNF day 1 (Hospital: 103.0 ft; SNF vs 51.1 ft; P < .001) compared to the last hospital session. There were no significant differences in distance walked on SNF days 3 and 4 relative to the last hospital session. The VAS pain scores did not significantly differ on SNF days 0 and 1 compared to the last hospital day but began to significantly decline on SNF day 3 (Hospital: 4.9; SNF: 3.3; P = .02) and day 4 (Hospital: 3.9; SNF: 2.3; P = .03).

Conclusion: There was a significant decline in ambulatory proficiency in post-TJA patients on the day of and the day following hospital discharge to an SNF. These deficits cannot be attributed to heightened pain levels. Early and progressive ambulation is a recognized component of appropriate PT following TJA. This study therefore highlights the transition from hospital to SNF as a crucial and novel target for improvement in post-TJA care.
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March 2016

Comparative Analysis of Calcium Silicate-based Root Filling Materials Using an Open Apex Model.

J Endod 2016 Apr 27;42(4):654-8. Epub 2016 Feb 27.

Department of Endodontics, Texas A&M University Baylor College of Dentistry, Dallas, Texas.

Introduction: Many new calcium silicate-based root filling materials have emerged in the market; however, their performance in the orthograde obturation of an open apex has not been evaluated. The purpose of this study was to compare the marginal adaptation of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK), NeoMTA Plus (Avalon Biomed Inc, Bradenton, FL), and Endosequence BC RRM-Fast Set Putty (BC RRM-FS; Brasseler USA, Savannah, GA) after orthograde placement in roots with open apices.

Methods: Palatal roots of maxillary molars were instrumented to create divergent open apices and divided into 4 groups for orthograde obturation: ProRoot MTA, NeoMTA Plus, BC RRM-FS, and BC RRM-FS + BC Sealer. Using a scanning electron microscope, the quality of material adaptation at the anatomic apex was evaluated by 5 blinded examiners; 3 mm of the root end was sectioned, and gap distance was measured at the material-dentin interface. Statistical analyses were performed using the Kruskal-Wallis test.

Results: There were no significant differences in marginal adaptation among the 4 groups at the level of the anatomic apex (P = .175). BC RRM-FS + BC Sealer had a significantly smaller gap size after 3-mm root end resection compared with the other 3 groups (P < .01). No differences were observed among the other 3 materials.

Conclusions: All materials showed comparable marginal adaptation at the anatomic apex when used for orthograde obturation of open apices. Application of BC Sealer before the delivery of BC RRM-FS Putty enhanced the quality of adaptation coronal to the apex.
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April 2016

Nuclear magnetic resonance methods for metabolic fluxomics.

Methods Mol Biol 2013 ;985:335-51

Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA.

Fluxomics, through its core methodology of metabolic flux analysis (MFA), enables quantification of carbon traffic through cellular biochemical pathways. Isotope labeling experiments aid MFA by providing information on intracellular fluxes, especially through parallel and cyclic pathways. Nuclear magnetic resonance (NMR) and mass spectrometry (MS) are two complementary methods to measure abundances of isotopomers generated in these experiments. 2-D [(13)C, (1)H] heteronuclear correlation NMR spectra can detect (13)C isotopes coupled to protons and thus noninvasively separate molecules and atoms with a specific isotopic content from a mixture of molecular species. Furthermore, the fine structures of the peaks in these spectra can reveal scalar couplings between chemically bonded carbon atoms in the sample, from which isotopomer abundances can be quantified. This chapter introduces methods for NMR sample preparation and spectral acquisition of 2-D [(13)C, (1)H] correlation maps, followed by a detailed presentation of methods to process the spectra and quantify isotopomer abundances. We explain the use of the software NMRViewJ for spectral visualization and processing, as well as MATLAB scripts developed by us for peak extraction, deconvolution of overlapping peaklets, and isotopomer abundance quantification. Finally, we discuss the applications of NMR-derived isotopomer data toward quantitatively understanding metabolic pathways.
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July 2013