Luyen Nguyen - Academia.edu (original) (raw)

Papers by Luyen Nguyen

Advances in Natural Sciences: Nanoscience and Nanotechnology, 2016

The 2006-2010 SME Development Action Plan shows a strong commitment from the government to furthe... more The 2006-2010 SME Development Action Plan shows a strong commitment from the government to further streamline business startup procedures and to encourage more enterprises to be formally established. As a first step in several reforms in this area, the government is introducing a new inter-ministerial Circular to enable more effective coordination among the three agencies responsible for the startup process, with an 1 aim to reduce the time and costs of starting a business for entrepreneurs. The Circular serves as a basis for continuing reforms, including a planned online company 2 registration system and national enterprise information database by 2009. In many provinces, authorities responsible for business startup are anticipating the Circular in order to help them make immediate reforms to their own procedures. Now in its sixth draft, the Circular still has a number of weaknesses that need to be addressed in order make the startup process as simple as possible for entrepreneurs. This bulletin discusses some of the main weaknesses and suggests ways to address them.

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2011

A new rhodamine-derived Schiff base (RS) was synthesized and its sensing property to metal ions w... more A new rhodamine-derived Schiff base (RS) was synthesized and its sensing property to metal ions was investigated by UV/vis and fluorescence spectroscopies. Addition of Hg 2+ ions to the aqueous solution of RS gave a visual color change as well as significantly fluorescent enhancement, while other ions including Pb 2+ , Cd 2+ , Cr 3+ , Zn 2+ , Cu 2+ , Fe 2+ , Co 3+ , Ni 2+ , Ca 2+ , Mg 2+ , K + and Na + ions did not induce any distinct color/spectral changes, which constituted a Hg 2+ -selective fluorescent OFF-ON chemosensor. The Hg 2+induced ring-opening of spirolactam of rhodamine in RS resulted in the dual chromo-and fluorogenic observation.

Journal of Molecular Biology, 1997

Researchers in both academia and industry have expressed strong interest in comprehending the mec... more Researchers in both academia and industry have expressed strong interest in comprehending the mechanisms responsible for enhancing the thermostability of proteins. Many and different structural principles have been postulated for the increased stability. Here, 16 families of proteins with different thermal stability were theoretically examined by comparing their respective fractional polar atom surface areas and the number and type of hydrogen bonds and salt links between explicit protein atoms. In over 80% of the families, correlations were found between the thermostability of the familial members and an increase in the number of hydrogen bonds as well as an increase in the fractional polar surface which results in added hydrogen bonding density to water. Thus increased hydrogen bonding may provide the most general explanation for thermal stability in proteins. The number of ion pairs was also found to increase with thermal stability in two-thirds of the families tested; however, their rate of addition was only about one-sixth that for internal hydrogen bonds amongst the protein atoms. The preferred residue exchanges and surface atom types useful in engineering enhanced stability were also examined.

Journal of Macroeconomics, 2007

Data Revues 01909622 V44i3 S0190962201175924, Feb 9, 2011

The propensity for spindle cell melanoma to metastasize to the lymph node is relatively low despi... more The propensity for spindle cell melanoma to metastasize to the lymph node is relatively low despite its relative thick depth. To date, there are no published reports on the sentinel lymph node (SLN) status in patients diagnosed with spindle cell melanoma and desmoplastic malignant melanoma (DMM). Our purpose was to report our experience on the SLN status in spindle cell melanoma and DMM. We undertook a retrospective database and medical record review from Oct 21, 1993 to Sept 29, 1999. At the University of California at San Francisco Melanoma Center, patients with tumor thickness greater than 1 mm or less than 1 mm with high-risk features are managed with preoperative lymphoscintigraphy, selective SLN dissection, and wide excision. Of 29 patients diagnosed with spindle cell melanoma and DMM, 28 had negative SLNs and are free of disease except for one patient who experienced splenic, bony, and brain metastases. The mean follow-up in this population was 16.5 and 11 months, respectively. Our preliminary findings show that SLNs from patients diagnosed with spindle cell melanoma and DMM only rarely harbor micrometastasis despite their relative thickness. A larger number of cases from multicenter databases may further define the true biology of SLNs in this melanoma variant.

Analytical Chemistry Research, 2015

deposition approach was established to incorporate the gold nano-flakes onto the glassy car-28 bo... more deposition approach was established to incorporate the gold nano-flakes onto the glassy car-28 bon electrode in electrochemical cells (nano-Au/GC/ECCs). Using pulsed amperometric detection (PAD) 29 without any gold oxidation for cleaning (non-oxidative PAD), the nano-Au/GC/ECCs were able to maintain 30 their activity for oxidizing of carbohydrates in a normal alkaline medium. The reproducibility of peak area 31 was about 2 relative standard deviation (RSD,%) for 6 consecutive injections. A dynamic range of carbo-32 hydrates was obtained over a concentration range of 5-80 mg L À1 and the limits of detection (LOD) were 33 of 2 mg L À1 for fructose and lactose and 1 mg L À1 for glucose and galactose. Moreover, the 34 nano-Au/GC/ECC using the non-oxidative PAD was able to combine with the internal standard method 35 for determination of lactose in fresh cow milk sample. 36 Ó 2015 Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http:// 37 creativecommons.org/licenses/by-nc-nd/4.0/).

American Journal of Analytical Chemistry, 2015

The nano-gold layer formed on the platinum rotating disk electrode (nano-Au/Pt-RD) inherited the ... more The nano-gold layer formed on the platinum rotating disk electrode (nano-Au/Pt-RD) inherited the catalytic property for Cr(VI) reduction from platinum surface and owned the good features of nano-gold such as insensitivity with hydrogen ion, high surface area, augmenting diffusion of Cr(VI) and ability for self-assembling with 4-pyridine-ethanethiol (PET) through Au←S linkages, to form PET/nano-Au/Pt-RD electrode capable of accumulating Cr(VI) from sample. The obtained PET/ nano-Au/Pt-RD electrode showed an extreme sensitivity to Cr(VI). By using this electrode, 1.09 ng•L −1 was the detection limit of differential pulse adsorptive cathodic stripping voltammetry for Cr(VI) with the accumulation time of only 2 min. Moreover, this electrode was reproducible with 3.5% RSD for 30 times of Cr(VI) accumulating and stripping. In addition, this electrode was also selective for Cr(VI) determination, which was not almost interfered by other inorganic ions.

Advances in Natural Sciences: Nanoscience and Nanotechnology, 2015

Biochemical Systematics and Ecology, 2014

Surgical Clinics of North America, 2000

authors have used FileMaker Pro (Claris Corp) to establish a database of 700 patients who have un... more authors have used FileMaker Pro (Claris Corp) to establish a database of 700 patients who have undergone sentinel lymph node (SLN) dissection since 1993. This internally developed database program runs atop a host of other software programs and is accessible through networked computers located in the clinic, the operating room, and the laboratory. Demographic data, primary tumor prognostic factors, staging information, preoperative lymphoscintigraphy, intraoperative observations, surgical pathology results, and follow-up status are some of the many elements that are chronicled for each patient, from preoperative work-up, through the diagnostic and surgical procedures, to routine follow-up visits. Prospective data entry and immediate accessibility ensure accurate and updated database.

Pharmaceutical Biology, 2014

A methanol extract of Cyperus rotundus L. (Cyperaceae) rhizomes showed inhibitory activity agains... more A methanol extract of Cyperus rotundus L. (Cyperaceae) rhizomes showed inhibitory activity against α-glucosidase and α-amylase, two enzymes involve in carbohydrate digestion. Identification of compounds from C. rotundus rhizomes responsible for the inhibition of α-glucosidase and α-amylase. Compounds were identified by a phytochemical investigation using combined chromatographic and spectroscopic methods. α-glucosidase and α-amylase inhibitory activities were evaluated by in vitro enzyme inhibition assays. A new…

Journal of the American Academy of Dermatology, 2001

Journal of Biological Chemistry, 2012

Background: Dbp2 is a member of the DEAD-box family of RNA helicases. Results: Dbp2 is a double-s... more Background: Dbp2 is a member of the DEAD-box family of RNA helicases. Results: Dbp2 is a double-stranded RNA-specific ATPase required for repression of cryptic initiation and downstream RNA quality control. Conclusion: Dbp2 functions in transcriptional fidelity as a cotranscriptional RNA chaperone. Significance: Elucidation of key RNA enzymes is central to defining the mechanisms for eukaryotic gene regulation.

Annals of Surgical Oncology, 2001

The sentinel lymph node (SLN) is the first lymph node in the regional nodal basin to receive meta... more The sentinel lymph node (SLN) is the first lymph node in the regional nodal basin to receive metastatic cells. In-transit nodes are found between the primary melanoma site and regional nodal basins. To date, this is one of the first reports on micrometastasis to in-transit nodes. Retrospective database and medical records were reviewed from October 21, 1993, to November 19. 1999. At the UCSF Melanoma Center, patients with tumor thickness > 1 mm or < 1 mm with high-risk features are managed with preoperative lymphoscintigraphy, selective SLN dissection, and wide local excision. Thirty (5%) out of 557 extremity and truncal melanoma patients had in-transit SLNs. Three patients had positive in-transit SLNs and negative SLNs in the regional nodal basin. Two patients had positive in-transit and regional SLNs. Three patients had negative in-transit SLNs but positive regional SLNs. The remaining 22 patients were negative for in-transit and regional SLNs. In-transit SLNs may harbor micrometastasis. About 10% of the time, micrometastasis may involve the in-transit and not the regional SLN. Therefore, both in-transit and regional SLNs should be harvested.

The article deals with a method for hydrochemical exploration and poorly studied areas based on t... more The article deals with a method for hydrochemical exploration and poorly studied areas based on the simulation and statistical modeling of the hydrochemical field. The peculiarity of the method is a prospecting area spotting under the following conditions: (1) the maximal ratio between river basin in the Riverhead without evident channel network and the total river basin; (2) the river network and tectonic deformations maximum; (3) presence of low-flow rate sections with relatively sharp breaks in grade of the water surface (outflow of rivers from mountainous areas onto the sub-mountain plain, extended sections of channel multi-branching). A sampling of 2-3 samples of surface water, 2-3 samples of river bed sediments, and 2-3 samples of ground water is taken at prospective sections and contiguous territories and the chemical composition determined. The geo-informational analysis and obtained data are used to determine the parameters of the model of the area under study, a predictive assessment of the hydrochemical indicators for prospective sections is carried out, and a detailed examination is planned and performed. The expected reduction in the cost of exploration compared to currently used methods is approximately 20%.