Numerical analysis of a hydraulic gear micro motor

Alberto Flores-Márquez,Fernando Velázquez-Villegas,Gabriel Ascanio 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

This study investigates the critical parameters that have the most impact on the structural capacity of hydraulic gear micro motors,namely, motor configuration, output torque, and speed. Seven different motor configurations were evaluated in terms of output speed and torque, which depend on the number and size of gears. During motor operation, reactive loads generated by drag forces, viscous damping forces, and oil pocketing within two adjacent teeth in contact were numerically calculated. Stress analysis using the finite element method was also performed to evaluate the structure of the aforementioned gear motor configurations. The results demonstrated that the structural capacity of a hydraulic motor does not necessarily increase when using larger gears or by increasing the number of gears. Reactive loads increase as rotational speed and gear size increase. Higher lubricant pressure is also required to attain the required output torque and velocity.

Isomerase Activity of Candida rugosa Lipase in the Optimized Conversion of Racemic Ibuprofen to (S)-Ibuprofen

Saideh S. Mortazavi,David Chavez-Flores,James M. Salvador 한국생물공학회 2016 Biotechnology and Bioprocess Engineering Vol.21 No.5

The Candida rugosa lipase catalyzed Dynamic Kinetic Resolution of racemic ibuprofen methyl ester produced (S)-ibuprofen in over 90% yield within 72 h at pH 7.6. The best concentration of various buffers for these reactions ranged from 0.2 to 0.5 M. The commercial lipase was found to be acidic altering the final pH of the reaction mixtures. Dimethylformamide co-solvent maintained the reaction pH better than dimethylsulfoxide. Lower concentrations of ibuprofen methyl ester and higher stirring rates led to faster conversions. The minimal amount of lipase needed was 20 mg/mL buffer. Reaction of (R)-ibuprofen methyl ester under the optimized conditions excluding the lipase led to no racemization, indicating that the conversion of (R)-ibuprofen methyl ester to (S)-ibuprofen is catalyzed by the enzyme, thus, indicating Candida rugosa lipase possess Isomerase activity.

Nutraceutical effects of bioactive peptides obtained from Pterophylla beltrani (Bolivar & Bolivar) protein isolates

Laura Jenet Montiel-Aguilar,Jorge Ariel Torres-Castillo,Rocío Rodríguez-Servin,Adiel Berenice López-Flores,Víctor Eustorgio Aguirre-Arzola,Gerardo Méndez-Zamora,Sugey Ramona Sinagawa-García 한국응용곤충학회 2020 Journal of Asia-Pacific Entomology Vol.23 No.3

Edible insects have been important sources of food proteins for human consumption and animal feed. In this study, a protein isolate from Pterophylla beltrani Bolivar & Bolivar, 1942 (Orthoptera: Tettigoniidae) was enzymatically processed and its nutraceutical properties were evaluated. Protein isolates were obtained from an insect flour and then was hydrolyzed for 5 h with a sequential process using pepsin and trypsin-chymotrypsin to simulate the gastric intestinal fluids. To evaluate the effect of peptide molecular size on nutraceutical properties, the peptides obtained from Total hydrolyzed (TH) were fractionated by ultrafiltration (UF) with 10 kDa and 3 kDa UF membranes giving fractions (F) with different molecular size (F < 3KDa, F < 10KDa and F > 10KDa). The inhibition assay of Angiotensin-Converting Enzyme (ACE) showed that the best treatment (P < 0.05) was the (TH) with an IC50 value of 0.5 mg/mL while the F < 3KDa was the lowest (P < 0.05) with an IC50 of 1.44 mg/mL, and the peptide size had no effect. However, an α-amylase inhibition was observed with an increase of the IC50 value between TH, F > 10KDa and F < 10KDa although no significative difference (P > 0.05) was found between the TH and F < 3KDa with IC50 of 0.48 and 0.68 mg/mL, respectively. In antioxidant activity, significant differences (P < 0.05) were observed between TH and UF fractions where the best response was in the F < 3KDa. In conclusion, P. beltrani proteins isolate are a source of bioactive peptide, and these could be considered as potential edible insect and sustainable food with nutraceutical effects.

Analysis of Cyp2b1 gene expression in the rat liver and brain by multiplex PCR

America Vanoye-Carlo,Gabriel Gutiérrez-Ospina,Jaime Marcial-Quino,Saúl Gómez-Manzo,Itzhel Garcia-Torres,Ignacio De la Mora-De la Mora,Sergio Enríquez-Flores,Sara T. Méndez,Bryan V. Phillips-Farfán,Ped 대한독성 유전단백체 학회 2015 Molecular & cellular toxicology Vol.11 No.4

The CYP2B6 enzyme is involved in the metabolism of environmental toxins and endogenous compounds. The expression and activity of the cyp2b6 gene is important for the brain’s ability to detoxify harmful compounds. In rats, the Cyp2b1 gene is homologous to the human Cyp2b6 gene and has an isoform, Cyp2b2, with nearly the same sequence. Although the distinction between them is fundamental, most studies report global changes in CYP2B enzymes due to the complexity of the techniques to detect both genes separately. We instrumented a semi-quantitative technique combining multiplex end point RT-PCR with restriction enzyme assays, allowing us to establish a relatively simple, reproducible and affordable method to distinguish Cyp2b1 gene expression from Cyp2b2. Using this technique, we showed differential Cyp2b1 expression after phenobarbital and ethanol induction in the brain and liver and detected increased Cyp2b1 expression after ethanol treatment in the brain striatum that had not been detected before.

International comparison CCQM-K82: methane in air at ambient level (1800 to 2200) nmol/mol

Flores, Edgar,Viallon, Joë,le,Choteau, Tiphaine,Moussay, Philippe,I Wielgosz, Robert,Kang, Namgoo,Moon Kim, Byung,Zalewska, Ewelina,(A M H) van der Veen, Adriaan,Konopelko, Leonid,Wu, Hai,Han, Qia IOP 2015 Metrologia Vol.52 No.-

<P>The CCQM-K82 comparison was designed to evaluate the degrees of equivalence of NMI capabilities for methane in air primary reference mixtures in the range (1800 to 2200) nmol/mol. The balance gas for the standards was either scrubbed dry real air or synthetic air.</P> <P> CH<SUB>4</SUB> in air standards have been produced by a number of laboratories for many years, with more recent developments focused on standards at atmospheric measurement concentrations and aimed at obtaining agreement between independently produced standards. A comparison of the differences in primary gas standards for methane in air was previously performed in 2003 (CCQM-P41 Greenhouse gases. 1 and 2) with a standard deviation of results around the reference value of 30 nmol/mol and 10 nmol/mol for a more limited set of standards. This can be contrasted with the level of agreement required from field laboratories routinely measuring atmospheric methane levels, set by Data Quality Objectives (DQO) established by the World Meteorological Organization (WMO) to reflect the scientifically desirable level of compatibility for CH<SUB>4</SUB> measurements at the global scale, currently set at 2 nmol/mol (1 sigma).</P> <P> The measurements of this key comparison took place from May 2012 to June 2012.</P> <P> Eight laboratories took part in this comparison coordinated by the BIPM and NIST. Key comparison reference values were calculated based on Cavity Ring Down Spectroscopy Measurements performed at the BIPM, combined with participant's gravimetric values to identify a consistent set of standards. Regression analysis allowed predicted values for each standard to be calculated which acted as the KCRVs. In this comparison reported standard uncertainties by participants ranged from 0.50 nmol/mol to 2.4 nmol/mol and the uncertainties of individual KCRVs ranged from 0.68 nmol/mol to 0.71 nmol/mol.</P> <P> The standard deviation of the ensemble of standards about the KCRV value was 1.70 nmol/mol. This represents a greater than tenfold improvement in the level of compatibility of methane in air standards compared to that demonstrated in 2003. Further improvements in the compatibility of standards will require improved methods and uncertainties for the measurement of trace level methane in balance gases. </P> <P><B>Main text.</B> To reach the main text of this paper, click on <A HREF='http://www.bipm.org/utils/common/pdf/final_reports/QM/K82/CCQM-K82.pdf'>Final Report</A>. Note that this text is that which appears in Appendix B of the BIPM key comparison database <A HREF='http://kcdb.bipm.org/'>kcdb.bipm.org/</A>.</P> <P>The final report has been peer-reviewed and approved for publication by CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>

Flexural and tensile properties of a glass fiber-reinforced ultra-high-strength concrete: an experimental, micromechanical and numerical study

M. Jason Roth,Thomas R. Slawson,Omar G. Flores 사단법인 한국계산역학회 2010 Computers and Concrete, An International Journal Vol.7 No.2

The focus of this research effort was characterization of the flexural and tensile properties of a specific ultra-high-strength, fiber-reinforced concrete material. The material exhibited a mean unconfined compressive strength of approximately 140 MPa and was reinforced with short, randomly distributed alkali resistant glass fibers. As a part of the study, coupled experimental, analytical and numerical investigations were performed. Flexural and direct tension tests were first conducted to experimentally characterize material behavior. Following experimentation, a micromechanically-based analytical model was utilized to calculate the material’s tensile failure response, which was compared to the experimental results. Lastly, to investigate the relationship between the tensile failure and flexural response, a numerical analysis of the flexural experiments was performed utilizing the experimentally developed tensile failure function. Results of the experimental, analytical and numerical investigations are presented herein.

Low Wavenumber Raman Modes and Plasmon Resonance in Cd Nanoparticles Obtained in Extract of Opuntia ficus-indica Plant

M. Cortez-Valadez,L. P. Ramírez-Rodríguez,J.-G. Bocarando-Chacon,M. FLORES-ACOSTA,S. VELUMANI,R. Ramírez-Bon 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2015 NANO Vol.10 No.7

"Cadmium colloidal crystalline nanoparticles were obtained by a simple green synthesis method employing the plant extract of Opuntia ficus-indica. The plant extract reduces the Cd ions and stabilizes the size of cadmium colloidal particles at the nanometric level. The size and morphology of agglomerates of nanoparticles of about 100 nm were analyzed by field-emission scanning electron microscopy (FESEM). The size, shape and crystalline structure of the Cd nanoparticles were determined from TEM analysis. The results show that Cd nanoparticles with hexagonal crystalline structure and average size 2–3 nm were obtained by this green synthesis method. The optical absorption spectrum of the colloidal solution containing the cadmium nanoparticles displays an optical absorption band centered at 236 nm, which was attributed to the plasmon resonance of the Cd colloidal nanoparticles. Mie theory for colloidal systems was applied to reproduce theoretically the plasmon resonance absorption data of the Cd colloidal nanoparticles. Furthermore, the Raman spectrum of powder from dried samples after reduction of cadmium ions, displays a low wavenumber vibration mode centered at 114 cm-1, assigned to the Cd nanoparticles. Density functional theory (DFT) calculations at local spin density approximation (LSDA) level were performed to determine the structure and vibrational properties of small clusters of cadmium consisting of 3–10 atoms. Radial breathing modes with frequencies between 90 cm-1 and 120 cm-1 were found to be the most active Raman modes of the low-energy Cdn clusters."

Comparing the Chemical Biology of NO and HNO

Wilmarie Flores-Santana,Christopher Switzer,Lisa A. Ridnour,Debashree Basudhar,Daniele Mancardi,Sonia Donzelli,Douglas D. Thomas,Katrina M. Miranda,Jon M. Fukuto,David A. Wink 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.8

For the past couple of decades nitric oxide (NO) and nitroxyl (HNO) have been extensively studied due to the important role they play in many physiological and/or pharmacological processes. Many researchers have reported important signaling pathways as well as mechanisms of action of these species, showing direct and indirect effects depending on the environment. Both NO and HNO can react with, among others, metals, proteins, thiols and heme proteins via unique and distinct chemistry leading to improvement of some clinical conditions. Understanding the basic chemistry of NO and HNO and distinguishing their mechanisms of action as well as methods of detection are crucial for understanding the current and potential clinical applications. In this review, we summarize some of the most important findings regarding NO and HNO chemistry, revealing some of the possible mechanisms of their beneficial actions.

Design and experimental evaluation of a mixed-mode continuous solar dryer for plaster molds

K. M. Aguilar-Castro,J. J. Flores-Prieto,M. E. Baltazar-Lopez,E. V. Macias-Melo 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9

This work aimed to develop and evaluate a mixed-mode continuous solar dryer for plaster molds for the local craft ceramics industry to reduce the drying time during the pottery manufacturing process. This novel design reduces time and movements in the manufacturing line. Indirect solar energy is used to complement direct solar energy; such a combination allows the continuous drying process to meet the energy requirements and optimize solar energy expenses. The experimental results show that the average evaporation rate is 0.7 kg/hr,the average energy consumption is 2.57 MJ/kg-H2O-evaporated, and the drying time is 4 days. The actual drying time represents 20% to 29% of the total foregoing time employed by Morelos-México craft potters. This finding indicates that the dryer continuously works using 66.4% indirect and 33.6% direct solar energy, thereby entailing lower expenses than traditional continuous drying processes.

Antibacterial phytocomplexes and compounds from Psychotria sycophylla (Rubiaceae) against drug-resistant bacteria

Olive M. F. Demgne,Judith Flore Tchuissang Mbougnia,Armel Jackson Seukep,Armelle Tsafack Mbaveng,Mathieu Tene,Paul Nayim,Brice E. N. Wamba,Michel-Gael F. Guefack,Veronique Penlap Beng,Pierre Tane,Vict 경희대학교 융합한의과학연구소 2022 Oriental Pharmacy and Experimental Medicine Vol.22 No.4

In this study, we examined the antibacterial and antibiotic-resistance reversal properties of methanol (MeOH) and ethyl acetate (EtOAc) extracts and compounds from Psychotria sycophylla aerial parts against drug-resistant bacteria. The tests were performed using the microdilution method. The mechanisms of action were investigated on growth kinetic and proton pumps of Escherichia coli. The structures of isolated compounds including oleanolic acid (1), ursolic acid (2), lupeol (3), betulinic acid (4), β-sitosterol glucoside (5), and stigmasterol (6), were established based on nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometry (ESI–MS). The extracts displayed noteworthy antibacterial activities, with recorded minimal inhibitory concentrations (MIC) ranging from 4 to 1024 μg/mL. Significant activities (MIC < 100 μg/ mL) were obtained with the MeOH extract against Providencia stuartii PS2636 and Staphylococcus aureus MRSA9 (MIC of 16 μg/mL) as well as the EtOAc extract against S. aureus MRSA3 (MIC of 32 μg/mL) and Enterobacter aerogenes EA27 (MIC of 4 μg/mL). MeOH extract displayed a broad-spectrum antibacterial activity, acting against 21 out of 22 studied bacteria. The MICs of compounds (1–6) varied from 16 to 256 μg/mL. Oleanolic acid (1) appeared to be the most effective, preventing the growth of 100% of studied bacteria. The MeOH extract significantly enhanced the efficacy of conventional antibiotics against selected multidrug-resistant Gram-negative bacteria. The mechanistic investigations showed interference of MeOH with bacterial growth kinetic (by extending the lag phase) and inhibition of proton pumps. The current study provides a strong experimental baseline to consider P. sycophylla extracts and compounds as potent antibacterial natural products.