Publications by authors named "Chia-Min Lin"

26 Publications

  • Page 1 of 1

Nonthermal plasma-activated water: A comprehensive review of this new tool for enhanced food safety and quality.

Compr Rev Food Sci Food Saf 2021 01 23;20(1):583-626. Epub 2020 Nov 23.

Department of Food Safety/Hygiene and Risk Management, College of Medicine, National Cheng Kung University, Tainan, 701, Taiwan.

Nonthermal plasma (NTP) is an advanced technology that has gained extensive attention because of its capacity for decontaminating food from both biological and chemical sources. Plasma-activated water (PAW), a product of NTP's reaction with water containing a rich diversity of highly reactive oxygen species (ROS) and reactive nitrogen species (RNS), is now being considered as the primary reactive chemical component in food decontamination. Despite exciting developments in this field recently, at present there is no comprehensive review specifically focusing on the comprehensive effects of PAW on food safety and quality. Although PAW applications in biological decontamination have been extensively evaluated, a complete analysis of the most recent developments in PAW technology (e.g., PAW combined with other treatments, and PAW applications in chemical degradation and as curing agents) is nevertheless lacking. Therefore, this review focuses on PAW applications for enhanced food safety (both biological and chemical safeties) according to the latest studies. Further, the subsequent effects on food quality (chemical, physical, and sensory properties) are discussed in detail. In addition, several recent trends of PAW developments, such as curing agents, thawing media, preservation of aquatic products, and the synergistic effects of PAW in combination with other traditional treatments, are also presented. Finally, this review outlines several limitations presented by PAW treatment, suggesting several future research directions and challenges that may hinder the translation of these technologies into real-life applications.
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http://dx.doi.org/10.1111/1541-4337.12667DOI Listing
January 2021

The Antibacterial Efficacy and Mechanism of Plasma-Activated Water Against Enteritidis (ATCC 13076) on Shell Eggs.

Foods 2020 Oct 19;9(10). Epub 2020 Oct 19.

Department of Seafood Science, National Kaohsiung University of Science and Technology, Kaohsiung 811, Taiwan.

Eggs are one of the most commonly consumed food items. Currently, chlorine washing is the most common method used to sanitize shell eggs. However, chlorine could react with organic matters to form a potential carcinogen, trihalomethanes, which can have a negative impact on human health. Plasma-activated water (PAW) has been demonstrated to inactivate microorganisms effectively without compromising the sensory qualities of shell eggs. For this study, various amounts (250, 500, 750, or 1000 mL) of PAW were generated by using one or two plasma jet(s) at 60 watts for 20 min with an air flow rate at 6 or 10 standard liters per minute (slm). After being inoculated with 7.0 log CFU Enteritidis, one shell egg was placed into PAW for 30, 60, or 90 s with 1 or 2 acting plasma jet(s). When 2 plasma jets were used in a large amount of water (1000 mL), populations of . Enteritidis were reduced from 7.92 log CFU/egg to 2.84 CFU/egg after 60 s of treatment. In addition, concentrations of ozone, hydrogen peroxide, nitrate, and nitrite in the PAW were correlated with the levels of antibacterial efficacy. The highest concentrations of ozone (1.22 ppm) and nitrate (55.5 ppm) were obtained with a larger water amount and lower air flow rate. High oxidation reduction potential (ORP) and low pH values were obtained with longer activation time, more plasma jet, and a lower air flow rate. Electron paramagnetic resonance (EPR) analyses demonstrated that reactive oxygen species (ROS) were generated in the PAW. The observation under the scanning electron microscope (SEM) revealed that bacterial cells were swollen, or even erupted after treatment with PAW. These results indicate that the bacterial cells lost control of cell permeability after the PAW treatment. This study shows that PAW is effective against S. Enteritidis on shell eggs in a large amount of water. Ozone, nitrate, and ROS could be the main causes for the inactivation of bacterial cells.
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http://dx.doi.org/10.3390/foods9101491DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7603095PMC
October 2020

Electronic structure and anisotropic compression of OsB to 358 GPa.

J Phys Condens Matter 2020 Jun 9;32(40):405703. Epub 2020 Jun 9.

Department of Physics, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.

High pressure study on ultra-hard transition-metal boride OsB was carried out in a diamond anvil cell under isothermal and non-hydrostatic compression with platinum as an x-ray pressure standard. The ambient-pressure hexagonal phase of OsB is found to be stable with a volume compression V/V = 0.670 ± 0.009 at the maximum pressure of 358 ± 7 GPa. Anisotropic compression behavior is observed in OsB to the highest pressure, with the c-axis being the least compressible. The measured equation of state using the 3rd-order Birch-Murnaghan fit reveals a bulk modulus K = 397 GPa and its first pressure derivative [Formula: see text] = 4.0. The experimental lattice parameters and bulk modulus at ambient conditions also agree well with our density-functional-theory (DFT) calculations within an error margin of ∼1%. DFT results indicate that OsB becomes more ductile under compression, with a strong anisotropy in the axial bulk modulus persisting to the highest pressure. DFT further enables the studies of charge distribution and electronic structure at high pressure. The pressure-enhanced electron density and repulsion along the Os and B bonds result in a high incompressibility along the crystal c-axis. Our work helps to elucidate the fundamental properties of OsB under ultrahigh pressure for potential applications in extreme environments.
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http://dx.doi.org/10.1088/1361-648X/ab9ae9DOI Listing
June 2020

Experimental and Computational Studies on Superhard Material Rhenium Diboride under Ultrahigh Pressures.

Materials (Basel) 2020 Apr 3;13(7). Epub 2020 Apr 3.

Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA.

An emerging class of superhard materials for extreme environment applications are compounds formed by heavy transition metals with light elements. In this work, ultrahigh pressure experiments on transition metal rhenium diboride () were carried out in a diamond anvil cell under isothermal and non-hydrostatic compression. Two independent high-pressure experiments were carried out on for the first time up to a pressure of 241 GPa (volume compression = 0.731 ± 0.004), with platinum as an internal pressure standard in X-ray diffraction studies. The hexagonal phase of was stable under highest pressure, and the anisotropy between the -axis and -axis compression increases with pressure to 241 GPa. The measured equation of state (EOS) above the yield stress of is well represented by the bulk modulus = 364 GPa and its first pressure derivative = 3.53. Corresponding density-functional-theory (DFT) simulations of the EOS and elastic constants agreed well with the experimental data. DFT results indicated that becomes more ductile with enhanced tendency towards metallic bonding under compression. The DFT results also showed strong crystal anisotropy up to the maximum pressure under study. The pressure-enhanced electron density distribution along the and bond direction renders the material highly incompressible along the -axis. Our study helps to establish the fundamental basis for anisotropic compression of under ultrahigh pressures.
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http://dx.doi.org/10.3390/ma13071657DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7178289PMC
April 2020

The Optimization of Plasma-Activated Water Treatments to Inactivate Enteritidis (ATCC 13076) on Shell Eggs.

Foods 2019 Oct 21;8(10). Epub 2019 Oct 21.

Department of Seafood Science, National Kaohsiung University of Science and Technology, Kaohsiung 811, Taiwan.

Egg is a regularly consumed food item. Currently, chlorinated water washing is the most common practice used to disinfect eggs, but this process has a negative environmental impact. A new physical technique, plasma-activated water (PAW), has been demonstrated to possess effective antibacterial activities without long-term chemical residue. In this study, air PAW was used to inactivate enterica serovar Enteritidis on shell eggs. Different combinations of activation parameters, including water sources (reverse osmotic (RO) water, tap water), power (40 W, 50 W, 60 W) and activation time (10 min, 20 min, 30 min), were evaluated. The oxidation-reduction potential (ORP) and pH values of each combination were measured, and their antibacterial activity was tested in a bacterial suspension. Higher antibacterial activities, higher ORP values, and lower pH values were obtained with higher power, longer activation time, and lower water hardness. The antibacterial activities of PAW decreased rapidly by increasing the storage time both at room and refrigeration temperatures. Afterwards, RO water was pre-activated for 20 min at 60 W, and then the eggs inoculated with were placed into PAW for 30 s, 60 s, 90 s, or 120 s with a plasma on-site treatment in the water. More than a 4 log reduction was obtained with 60-s and 120-s treatments. The results showed that the freshness indexes of the eggs treated with PAW were similar to those of the untreated controls and better than those of the eggs treated with commercial processes. In addition, observation under a scanning electron microscope also showed less surface damage of the cuticle on the PAW-treated eggs than on the commercially treated eggs. The results of this study indicate that PAW could be an effective antibacterial agent with less damage to the freshness of shell eggs than commercial methods.
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http://dx.doi.org/10.3390/foods8100520DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836110PMC
October 2019

Using Dicyclopentadiene-Derived Polyarylates as Epoxy Curing Agents To Achieve High and Low Dielectric Epoxy Thermosets.

ACS Omega 2018 Apr 18;3(4):4295-4305. Epub 2018 Apr 18.

Department of Cosmeceutics, China Medical University, Taichung 40402, Taiwan.

To achieve high- and low-dielectric epoxy thermosets, four dicyclopentadiene-derived polyarylates (26-P, 26-M, 236-P, and 236-M) were prepared from 2,6-dimethyl (or 2,3,6-trimethyl) phenol-dicyclopentadiene adduct with terephthaloyl (or isophthaloyl) chloride by high-temperature solution polymerization. The resulting polyarylates, exhibiting active ester linkages (Ph-O-(C=O)-) are found to be reactive toward a commercial dicyclopentadiene phenol epoxy (HP7200) in the presence of some lone-pair electron-containing compounds. Five compounds including 4-dimethylaminopyridine (DMAP), imidazole, 2-methylimidazole, triphenylphosphine, and triphenylimidazole have been evaluated as a catalyst for the curing reactions. We found that DMAP, with the smallest p among them, is the best catalyst according to differential scanning calorimetry, infrared, and thermal analyses. The thermal and dielectric properties of the polyarylate/HP7200 thermosets are evaluated. We found that they exhibit a high characteristic (e.g., is 238 °C for DMAP-catalyzed, 236-P/HP7200 thermoset). Furthermore, because of the hydrophobic methyl and cycloaliphatic moieties, and the secondary hydroxyl-free structure, polyarylate/HP7200 thermosets show a relative low-dielectric constant of around 2.75 U. The detailed structure-properties relationship is discussed in this work.
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http://dx.doi.org/10.1021/acsomega.8b00256DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6641589PMC
April 2018

The effect of vacuum packaging on histamine changes of milkfish sticks at various storage temperatures.

J Food Drug Anal 2017 Oct 14;25(4):812-818. Epub 2017 Feb 14.

Department of Seafood Science, National Kaohsiung Marine University, Kaohsiung, 811, Taiwan, ROC. Electronic address:

The effects of polyethylene packaging (PEP) (in air) and vacuum packaging (VP) on the histamine related quality of milkfish sticks stored at different temperatures (-20°C, 4°C, 15°C, and 25°C) were studied. The results showed that the aerobic plate count (APC), pH, total volatile basic nitrogen (TVBN), and histamine contents increased as storage time increased when the PEP and VP samples were stored at 25°C. At below 15°C, the APC, TVBN, pH, and histamine levels in PEP and VP samples were retarded, but the VP samples had considerably lower levels of APC, TVBN, and histamine than PEP samples. Once the frozen fish samples stored at -20°C for 2 months were thawed and stored at 25°C, VP retarded the increase of histamine in milkfish sticks as compared to PEP. In summary, this result suggested the milkfish sticks packed with VP and stored below 4°C could prevent deterioration of product quality and extend shelf-life.
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http://dx.doi.org/10.1016/j.jfda.2016.12.009DOI Listing
October 2017

Evaluation of the prebiotic effects of citrus pectin hydrolysate.

J Food Drug Anal 2017 Jul 13;25(3):550-558. Epub 2017 Feb 13.

Department of Food Science, National Pingtung University of Science and Technology, 1, Hsueh Fu Road, Nei-Pu Township, Pingtung 91201, Taiwan, ROC. Electronic address:

Citrus pectin enzyme hydrolysate (PEH) of different hydrolysis time intervals (6 hours, PEH-6; 12 hours, PEH-12; 24 hours, PEH-24; or 48 hours, PEH-48) or concentrations (1%, 2%, and 4%) was tested for its growth stimulation effect on two probiotics, Bifidobacterium bifidum and Lactobacillus acidophilus. Higher monosaccharide concentrations and smaller molecular weights of PEHs were obtained by prolonging the hydrolysis time. In addition, higher PEH concentrations resulted in significantly higher (p < 0.05) probiotic populations, pH reduction, and increase in total titratable acidity than the glucose-free MRS negative control. Furthermore, significantly higher populations in the low pH environment and longer survival time in nonfat milk (p < 0.05) were observed when the two probiotics were incubated in media supplemented with 2% PEH-24, than in glucose and the negative control. In comparison with other prebiotics, addition of 2% PEH-24 resulted in a more significant increase in the probiotic population (p < 0.05) than in the commercial prebiotics. This study demonstrated that PEH derived from citrus pectin could be an effective prebiotic to enhance the growth, fermentation, acid tolerance, and survival in nonfat milk for the tested probiotics.
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http://dx.doi.org/10.1016/j.jfda.2016.11.014DOI Listing
July 2017

Effects of Short Forest Bathing Program on Autonomic Nervous System Activity and Mood States in Middle-Aged and Elderly Individuals.

Int J Environ Res Public Health 2017 08 9;14(8). Epub 2017 Aug 9.

Department of Tourism and Leisure Management, Yuanpei University of Medical Technology, Hsinchu 30015, Taiwan.

The present study investigated changes in autonomic nervous system activity and emotions after a short (2 h) forest bathing program in the Xitou Nature Education Area (XNEA), Taiwan. One hundred and twenty-eight (60.0 ± 7.44 years) middle-aged and elderly participants were recruited. Physiological responses, pulse rate, systolic and diastolic blood pressure, heart rate variability (HRV), and psychological indices were measured before and after the program. We observed that pulse rate, systolic and diastolic blood pressure were significantly lower after the program, which indicated physiological benefits from stress recovery. The Profile of Mood States negative mood subscale scores of "tension-anxiety", "anger-hostility", "fatigue-inertia", "depression-dejection", and "confusion-bewilderment" were significantly lower, whereas the positive mood subscale score of "vigor-activity" was higher. Furthermore, participants exhibited significantly lower anxiety levels according to the State-Trait Anxiety Inventory. However, changes in sympathetic and parasympathetic nerve activity were nonsignificant. Our study determined that the short forest bathing program is a promising therapeutic method for enhancing heart rate and blood pressure functions as well as an effective psychological relaxation strategy for middle-aged and elderly individuals.
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http://dx.doi.org/10.3390/ijerph14080897DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579495PMC
August 2017

Histamine production by Raoultella ornithinolytica in mahi-mahi meat at various storage temperatures.

J Food Drug Anal 2016 04 2;24(2):305-310. Epub 2015 Jan 2.

Department of Seafood Science, National Kaohsiung Marine University, Kaohsiung 811, Taiwan. Electronic address:

Mahi-mahi meat was inoculated with Raoultella ornithinolytica at 5.0 log CFU/g and stored at -20°C, 4°C, 15°C, 25°C, or 37°C to investigate bacterial growth and formation of total volatile base nitrogen and histamine in mahi-mahi meat. R. ornithinolytica grew rapidly in samples stored at temperature above 15°C. The histamine contents quickly increased to higher than 50 mg/100 g in samples stored at 25°C and 37°C within 12 hours as well as those stored at 15°C within 48 hours. The total volatile base nitrogen contents increased to higher than the index level (30 mg/100 g) for fish decomposition at 25°C within 48 hours and 37°C within 24 hours. However, bacterial growth and histamine formation were controlled by cold storage of the samples at 4°C or below. Once the frozen mahi-mahi samples stored at -20°C for 2 months were thawed and stored at 25°C after 24 hours, histamine started to accumulate rapidly (>50 mg/100 g of fish).
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http://dx.doi.org/10.1016/j.jfda.2014.06.010DOI Listing
April 2016

Freeform microstructure linear light emitter design for a natural light illumination system.

Appl Opt 2015 Oct;54(28):E159-64

The major factors of an illuminative environment are a high rendering index and uniformity. The natural light illumination system (NLIS) is used to guide sunlight for indoor illumination. The NLIS consists of three subsystems: collecting, transmitting, and emitting. Nowadays, a variety of light emitters are available for different illuminative environments. This paper proposes a linear microstructure to diffuse parallel light for indoor illumination. To increase uniformity and promote the illuminative area, the light emitter includes two microstructures for the distribution of light. Finally, the proposed light emitter gives illuminance uniformity and efficiency of 0.55% and 74.18%, respectively.
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http://dx.doi.org/10.1364/AO.54.00E159DOI Listing
October 2015

The histamine content of dried flying fish products in Taiwan and the isolation of halotolerant histamine-forming bacteria.

J Food Drug Anal 2015 Jun 2;23(2):335-342. Epub 2015 Jan 2.

Department of Seafood Science, National Kaohsiung Marine University, Kaohsiung City, Taiwan. Electronic address:

Thirty dried flying fish products were purchased from fishing village stores in Taiwan and tested to detect the presence of histamine and histamine-forming bacteria. Except for histamine and cadaverine, the average content of various biogenic amines in the tested samples was less than 3.5 mg/100 g. Eight (26.6%) dried flying fish samples had histamine levels greater than the United States Food and Drug Administration guideline of 5 mg/100 g for scombroid fish and/or scombroid products, whereas four (13.3%) samples contained more than the hazard action level of 50 mg/100 g. One histamine-producing bacterial isolate was identified as Staphylococcus xylosus by 16S rDNA sequencing with polymerase chain reaction amplification. This isolate was capable of producing 507.8 ppm of histamine in trypticase soy broth supplemented with 1.0% l-histidine (TSBH). The S. xylosus isolate was a halotolerant bacterium that had a consistent ability to produce more than 300 ppm of histamine at 3% sodium chloride concentration in TSBH medium after 72 hours.
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http://dx.doi.org/10.1016/j.jfda.2014.10.009DOI Listing
June 2015

Innovative design of light collimator based on a freeform microlens array.

Appl Opt 2014 Oct;53(29):H35-43

In developing a daylighting system, the overall system efficiency is crucial. In the daylighting system, whether the light propagates parallel strongly affects the efficiency. In this paper, we simulate a multicurvature lens to collimate rays propagated from different angles. We describe a method based on a freeform microlens array, which increases transmission efficiency. Results show that with the freeform microlens array collimator, the light propagates provide at least 50.26% parallel and the efficiency increases by 24.76%, enhancing the core values of the daylighting system in building illumination.
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http://dx.doi.org/10.1364/AO.53.000H35DOI Listing
October 2014

Determination and frying loss of histamine in striped marlin fillets implicated in a foodborne poisoning.

J Food Prot 2013 May;76(5):860-6

Department of Food Science, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan, Republic of China.

An incident of foodborne poisoning causing illness in 67 victims due to ingestion of fried fish fillets occurred in June 2011, in southern Taiwan. Of the five suspected fish fillets, one fried sample contained 62.0 mg/100 g and one raw sample contained 89.6 mg/100 g histamine, levels which are greater than the potential hazard action level (50 mg/100 g) in most illness cases. Given the allergy-like symptoms of the victims and the high histamine content in the suspected fish samples, this foodborne poisoning was strongly suspected to be caused by histamine intoxication. Five histamine-producing bacterial strains capable of producing 59 to 562 ppm of histamine in Trypticase soy broth supplemented with 1.0% L-histidine were identified as Enterobacter aerogenes (two strains), Raoultella ornithinolytica (two strains), and Morganella morganii (one strain). The degradation loss of histamine in suspected raw fillets was 28% after they were fried at 170°C for 5 min.
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http://dx.doi.org/10.4315/0362-028X.JFP-12-298DOI Listing
May 2013

Effect of salt concentrations and drying methods on the quality and formation of histamine in dried milkfish (Chanos chanos).

Food Chem 2012 Nov 12;135(2):839-44. Epub 2012 May 12.

Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan, ROC.

The effects of salt concentrations (0-15.0%) and drying methods on the quality of dried milkfish were studied. The results showed that the levels of aerobic plate counts, total coliform, water activity, moisture contents, total volatile basic nitrogen (TVBN) and thiobarbituric acid (TBA) of the dried milkfish samples prepared with the same drying method decreased with increased salt concentrations. The samples prepared with the cold-air drying method had better quality in term of lower TVBN and TBA values than those of samples prepared with other drying methods. The histamine contents in all samples, except two, prepared with various salt concentrations by different drying methods were less than 1.9 mg/100 g. Two unsalted samples prepared with hot-air drying at 35 °C and sun drying methods were found to contain histamine at levels of 249.7 and 67.4 mg/100 g, respectively, which were higher than the potential hazard level of 50 mg/100 g.
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http://dx.doi.org/10.1016/j.foodchem.2012.05.035DOI Listing
November 2012

A cone-shaped 3D carbon nanotube probe for neural recording.

Biosens Bioelectron 2010 Sep 20;26(1):220-7. Epub 2010 Jun 20.

Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan.

A novel cone-shaped 3D carbon nanotube (CNT) probe is proposed as an electrode for applications in neural recording. The electrode consists of CNTs synthesized on the cone-shaped Si (cs-Si) tip by catalytic thermal chemical vapor deposition (CVD). This probe exhibits a larger CNT surface area with the same footprint area and higher spatial resolution of neural recording compared to planar-type CNT electrodes. An approach to improve CNT characteristics by O(2) plasma treatment to modify the CNT surface will be also presented. Electrochemical characterization of O(2) plasma-treated 3D CNT (OT-CNT) probes revealed low impedance per unit area (∼64.5 Ω mm(-2)) at 1 kHz and high specific capacitance per unit area (∼2.5 mF cm(-2)). Furthermore, the OT-CNT probes were employed to record the neural signals of a crayfish nerve cord. Our findings suggest that OT-CNT probes have potential advantages as high spatial resolution and superb electrochemical properties which are suitable for neural recording applications.
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http://dx.doi.org/10.1016/j.bios.2010.06.015DOI Listing
September 2010

A lab-on-a-chip platform for studying the subcellular functional proteome of neuronal axons.

Lab Chip 2010 Mar 23;10(5):647-53. Epub 2009 Dec 23.

Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, Taiwan, Republic of China.

Axons are long, slender processes extending from the cell bodies of neurons and play diverse and crucial roles in the development and function of nervous systems. Here, we describe the development of a chip device that can be used to produce large quantities of axons for proteomic and RNA analyses. On the chip surface, bundles of axons of rat hippocampal neurons in culture are guided to grow in areas distinct and distant from where their cell bodies reside. Fluorescence immunocytochemical studies have confirmed that the areas where these axons are guided to grow are occupied exclusively by axons and not by neuronal somatodendrites or astroglial cells. These axon-occupied parts are easily separated from the remainder of the chip and collected by breaking the chip along the well-positioned linear grooves made on the backside. One- and two-dimensional gel electrophoresis and Western blotting analyses reveal that the axons and whole cells differ in their protein compositions. RT-PCR analyses also indicate that the axons contain only a subset of neuronal RNAs. Furthermore, the chip device could be easily modified to address other issues concerning neuronal axons, such as the molecular composition of the axon substructure, the growth cone and shaft, the degeneration and regeneration processes associated with injured axons and the effects of extrinsic molecules, such as axon guidance cues and cell adhesion molecules, on the axon. With these diverse applications, the chip device described here will serve as a powerful platform for studying the functional proteome of neuronal axons.
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http://dx.doi.org/10.1039/b918217aDOI Listing
March 2010

Batch-fabricated flexible carbon nanotubes' photosensor array.

Nanotechnology 2009 Nov 21;20(46):465502. Epub 2009 Oct 21.

Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu 30013, Taiwan.

This study reports a flexible carbon nanotubes' (fCNTs) photosensor for light detection. The fCNTs photosensor is batch-fabricated using micromachining processes. In this device, CNTs (carbon nanotubes) are embedded into the flexible Parylene-C film using a batch micromachining process. Through this fabrication process, CNTs act as the component for light detection, and Parylene-C provides the flexibility of the device. In application, the fCNTs photosensor is implemented. The photocurrent response measurements indicate that the presented fCNTs photosensor operated as a function of heterostructure interface, pressure, light intensity and bias voltage under red laser illumination. The quantum efficiency of the fabricated fCNTs device is about 0.063% at atmospheric pressure, and becomes 1.93% in a vacuum of 3 mTorr. Thus, the presented fCNTs device has the potential for photosensor application. The position detection of a light source using the fCNTs photosensor array has also been demonstrated.
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http://dx.doi.org/10.1088/0957-4484/20/46/465502DOI Listing
November 2009

Flexible carbon nanotubes electrode for neural recording.

Biosens Bioelectron 2009 May 20;24(9):2791-7. Epub 2009 Feb 20.

Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu 30013, Taiwan.

This paper demonstrates a novel flexible carbon nanotubes (CNTs) electrode array for neural recording. In this device, the CNTs electrode arrays are partially embedded into the flexible Parylene-C film using a batch microfabrication process. Through this fabrication process, the CNTs can be exposed to increase the total sensing area of an electrode. Thus, the flexible CNTs electrode of low impedance is realized. In application, the flexible CNTs electrode has been employed to record the neural signal of a crayfish nerve cord for in vitro recording. The measurements demonstrate the superior performance of the presented flexible CNTs electrode with low impedance (11.07 kohms at 1 kHz) and high peak-to-peak amplitude action potential (about 410 microV). In addition, the signal-to-noise ratio (SNR) of the presented flexible CNTs electrode is about 257, whereas the SNR of the reference (a pair of Teflon-coated silver wires) is only 79. The simultaneous recording of the flexible CNTs electrode array is also demonstrated. Moreover, the flexible CNTs electrode has been employed to successfully record the spontaneous spikes from the crayfish nerve cord. The amplitude of the spontaneous peak-to-peak response is about 25 microV.
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http://dx.doi.org/10.1016/j.bios.2009.02.005DOI Listing
May 2009

Foodborne disease outbreaks caused by sucrose-nonfermenting and beta-galactosidase-deficient variants of Vibrio cholerae.

Int J Food Microbiol 2008 Feb 28;122(1-2):148-55. Epub 2007 Nov 28.

The Central Region Laboratory, Center of Research and Diagnostics, Centers for Disease Control, Taichung City 40855, Taiwan.

We reported four foodborne disease outbreaks in Taiwan caused by sucrose-nonfermenting and by beta-galactosidase-deficient variants of non-O1, non-O139 Vibrio cholerae. The sucrose-nonfermenting vibrios collected from three outbreaks were biochemically identified to be V. mimicus and the beta-galactosidase-deficient vibrios from an outbreak to be V. alginolyticus. However, molecular methods including DNA-DNA hybridization, fatty acid profile analysis, and sequence analysis of 16S rRNA, oriC, pyrH, recA, and rpoA indicated that these vibrios should be V. cholerae. These V. cholerae variants carried two hemolysin genes, hlyA and hlx, but contained neither cholera toxin gene, ctx, V. mimicus hemolysin gene, vmh, nor thermo-directed hemolysin, tdh. The sucrose-nonfermenting variants of V. cholerae shared a high level of genetic relatedness; they could derive from a common clone. In our record from 1995 to date, this was the first time that V. cholerae variants were discovered as etiologic agents for foodborne disease outbreaks in Taiwan.
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http://dx.doi.org/10.1016/j.ijfoodmicro.2007.11.061DOI Listing
February 2008

Development of thermal surrogate microorganisms in ground beef for in-plant critical control point validation studies.

J Food Prot 2007 Apr;70(4):952-7

Center for Food Safety, University of Georgia, Griffin, Georgia 30223-1797, USA.

In search of a suitable surrogate microorganism for in-plant critical control point validation, we compared the rates of thermal inactivation of three bacteria, Enterococcus faecium B2354, Pediococcus parvulus HP, and Pediococcus acidilactici LP, to those of Listeria monocytogenes and Salmonella. Ground beef samples containing 4 and 12% fat were inoculated with E. faecium, L. monocytogenes, and Salmonella Senftenberg 775W and heated at 58, 62, 65, or 68 degrees C. The decimal reduction times (D-values) for E. faecium B2354 in 4 and 12% fat ground beef were 4.4 to 17.7 and 3.6 to 14.6 times greater, respectively, than those for L. monocytogenes or Salmonella Senftenberg 775W at all temperatures tested, with the greatest differences in D-values occurring at 58 and 62 degrees C. Higher fat content protected bacteria from thermal inactivation in general, especially at temperatures lower than 68 degrees C. The heat resistance in a broth medium at 62degrees C of two food-grade bacteria, P. parvulus HP and P. acidilactici LP, was compared with that of the three strains under study. The D-values of P. parvulus HP and P. acidilactici LP were lower than those of E. faecium B2354 but 4.1 and 2.5 times greater, respectively, than those of Salmonella Senftenberg 775W, the most resistant pathogen. These results indicate that thermal treatments of ground beef at 58 to 68 degrees C that kill E. faecium B2354 will also kill Salmonella and L. monocytogenes, and the two Pediococcus isolates may serve as alternate surrogates for validation studies when a less heat-resistant surrogate is desired. However, additional studies in ground beef are needed with the Pediococcus strains in the desired temperature range intended for validation purposes.
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http://dx.doi.org/10.4315/0362-028x-70.4.952DOI Listing
April 2007

Comparison of media and sampling locations for isolation of Listeria monocytogenes in queso fresco cheese.

J Food Prot 2006 Sep;69(9):2151-6

Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.

Listeriosis associated with Hispanic-style soft cheese is an ongoing public health concern. Although rapid detection methods based on molecular and immunological technologies have been applied successfully for detecting Listeria monocytogenes in foods, obtaining isolates of the pathogen is a critical procedure for epidemiologic studies and regulatory analysis. Oxford agar, a medium recommended by the U.S. Food and Drug Administration Bacteriological Analytical Manual (BAM) to isolate L. monocytogenes from cheese, is unable to differentiate L. monocytogenes from other Listeria species. Hence, two selective isolation media, L. monocytogenes blood agar (LMBA) and Rapid 'L. mono agar (RLMA), were compared with Oxford agar for isolating L. monocytogenes from cheese. Queso fresco cheese was inoculated at 10(0) or 10(1) CFU/g with a five-strain mixture of L. monocytogenes or with the five-strain L. monocytogenes mixture and Listeria innocua. Cheese samples were stored at 21, 12, and 4 degrees C and Listeria counts were determined at 3, 7, and 10 days; 7, 10, 14, 21 days; and 2, 4, 8, and 12 weeks postinoculation, respectively. Surface and interior cheese samples as well as liquid exudate produced during storage were assayed individually to determine differences in Listeria contamination at different sampling locations. L. monocytogenes was more easily differentiated from L. innocua on RLMA than LMBA and Oxford agar. Similar L. monocytogenes counts (ca. 10(4) CFU/g) were obtained on the last sampling day on the surface and interior of cheese samples (P > 0.05) for all storage temperatures and both initial inoculation levels, but smaller cell numbers were detected in the exudate produced during storage. In addition, simultaneous inoculation of L. innocua with L. monocytogenes did not affect the final L. monocytogenes counts in the cheese. The amount of exudate released from the cheese and decrease of pH correlated with storage temperature. More exudate was produced and a greater decrease of pH occurred at 21 degrees C than at 12 or 4 degrees C. Our results indicate that RLMA is a suitable medium for isolating L. monocytogenes from queso fresco cheese. Higher counts of L. monocytogenes were obtained from surface and interior samples of cheese than from the exudate of the cheese during storage. In addition, pH may be a useful indicator of improperly stored queso fresco cheese.
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http://dx.doi.org/10.4315/0362-028x-69.9.2151DOI Listing
September 2006

Cross-contamination between processing equipment and deli meats by Listeria monocytogenes.

J Food Prot 2006 Jan;69(1):71-9

Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.

Contamination of luncheon meats by Listeria monocytogenes has resulted in outbreaks of listeriosis and major product recalls. Listeriae can survive on processing equipment such as meat slicers which serve as a potential contamination source. This study was conducted to determine (i) the dynamics of cross-contamination of L. monocytogenes from a commercial slicer and associated equipment onto sliced meat products, (ii) the influence of sample size on the efficacy of the BAX-PCR and U.S. Department of Agriculture-Food Safety and Inspection Service enrichment culture assays to detect L. monocytogenes on deli meat, and (iii) the fate of L. monocytogenes on sliced deli meats of different types during refrigerated storage. Three types of deli meats, uncured oven-roasted turkey, salami, and bologna containing sodium diacetate and potassium lactate, were tested. A five-strain mixture of L. monocytogenes was inoculated at ca.10(3) CFU onto the blade of a commercial slicer. Five consecutive meat slices were packed per package, then vacuum sealed, stored at 4 degrees C, and sampled at 1 and 30 days postslicing. Two sample sizes, 25 g and contents of the entire package of meat, were assayed. Total numbers of L. monocytogenes-positive samples, including the two sample sizes and two sampling times, were 80, 9, and 3 for turkey, salami, and bologna, respectively. A higher percentage of turkey meat samples were L. monocytogenes positive when contents of the entire package were assayed than when the 25-g sample was assayed (12.5 and 7.5%, respectively). Lower inoculum populations of ca. 10(1) or 10(2) CFU of L. monocytogenes on the slicer blade were used for an additional evaluation of oven-roasted turkey using two additional sampling times of 60 and 90 days postslicing. L. monocytogenes-positive samples were not detected until 60 days postslicing, and more positive samples were detected at 90 days than at 60 days postslicing. When BAX-PCR and enrichment culture assays were compared, 12, 8, and 2 L. monocytogenes-positive samples were detected by both the enrichment culture and BAX-PCR, BAX-PCR only, and enrichment culture only assays, respectively. The number of L. monocytogenes-positive samples and L. monocytogenes counts increased during storage of turkey meat but decreased for salami and bologna. Significantly more turkey samples were L. monocytogenes positive when the contents of the entire package were sampled than when 25 g was sampled. Our results indicate that L. monocytogenes can be transferred from a contaminated slicer onto meats and can survive or grow better on uncured oven-roasted turkey than on salami or bologna with preservatives. Higher L. monocytogenes cell numbers inoculated on the slicer blade resulted in more L. monocytogenes-positive sliced meat samples. In addition, the BAX-PCR assay was better than the enrichment culture assay at detecting L. monocytogenes on turkey meat (P < 0.05).
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http://dx.doi.org/10.4315/0362-028x-69.1.71DOI Listing
January 2006

A comparison of hand washing techniques to remove Escherichia coli and caliciviruses under natural or artificial fingernails.

J Food Prot 2003 Dec;66(12):2296-301

Center for Food Safety, University of Georgia, 1109 Experiment Street, Griffin, Georgia 30223-1797, USA.

Compared with other parts of the hand, the area beneath fingernails harbors the most microorganisms and is most difficult to clean. Artificial fingernails, which are usually long and polished, reportedly harbor higher microbial populations than natural nails. Hence, the efficacy of different hand washing methods for removing microbes from natural and artificial fingernails was evaluated. Strains of nonpathogenic Escherichia coli JM109 and feline calicivirus (FCV) strain F9 were used as bacterial and viral indicators, respectively. Volunteers with artificial or natural nails were artificially contaminated with ground beef containing E. coli JM109 or artificial feces containing FCV. Volunteers washed their hands with tap water, regular liquid soap, antibacterial liquid soap, alcohol-based hand sanitizer gel, regular liquid soap followed by alcohol gel, or regular liquid soap plus a nailbrush. The greatest reduction of inoculated microbial populations was obtained by washing with liquid soap plus a nailbrush, and the least reduction was obtained by rubbing hands with alcohol gel. Lower but not significantly different (P > 0.05) reductions of E. coli and FCV counts were obtained from beneath artificial than from natural fingernails. However, significantly (P < or = 0.05) higher E. coli and FCV counts were recovered from hands with artificial nails than from natural nails before and after hand washing. In addition, microbial cell numbers were correlated with fingernail length, with greater numbers beneath fingernails with longer nails. These results indicate that best practices for fingernail sanitation of food handlers are to maintain short fingernails and scrub fingernails with soap and a nailbrush when washing hands.
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http://dx.doi.org/10.4315/0362-028x-66.12.2296DOI Listing
December 2003

Inactivation of Escherichia coli O157:H7, Salmonella enteritidis, and Listeria monocytogenes on apples, oranges, and tomatoes by lactic acid with hydrogen peroxide.

J Food Prot 2002 Jan;65(1):100-5

Center for Food Safety, University of Georgia, Griffin 30223-1797, USA.

The objective of this study was to develop a practical and effective method for inactivating or substantially reducing Escherichia coli O157:H7, Salmonella Enteritidis, and Listeria monocytogenes on apples, oranges, and tomatoes. Apples, oranges, and tomatoes were spot-inoculated with five-strain mixtures of E. coli O157:H7, Salmonella Enteritidis, and L. monocytogenes near the stem end and were submerged in sterile deionized water containing 1.5% lactic acid plus 1.5% hydrogen peroxide for 15 min at 40 degrees C. Inoculated samples treated with sterile deionized water at the same temperature and for the same duration served as controls. The bacterial pathogens on fruits subjected to the chemical treatment were reduced by >5.0 log10 CFU per fruit, whereas washing in deionized water decreased the pathogens by only 1.5 to 2.0 log10 CFU per fruit. Furthermore, substantial populations of the pathogens survived in the control wash water, whereas no E. coli O157:H7, Salmonella Enteritidis, or L. monocytogenes cells were detected in the chemical treatment solution. The sensory and qualitative characteristics of apples treated with the chemical wash solution were not adversely affected by the treatment. It was found that the treatment developed in this study could effectively be used to kill E. coli O157:H7, Salmonella Enteritidis, and L. monocytogenes on apples, oranges, and tomatoes at the processing or packaging level.
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http://dx.doi.org/10.4315/0362-028x-65.1.100DOI Listing
January 2002

Transfer of Salmonella montevideo onto the Interior Surfaces of Tomatoes by Cutting .

J Food Prot 1997 Jul;60(7):858-862

Food Science and Human Nutrition Department, University of Florida, Gainesville, Florida 32611-0370, USA.

Salmonella contamination of precut watermelon, tomatoes, and cantaloupes was responsible for several outbreaks of salmonellosis. To better understand the relationship between bacterial doses and their transfer onto cut surfaces by using a knife, rifampicin-resistant Salmonella montevideo at 7, 70, 700, or 7,000 CFU in Butterfield's buffer (BPB) or tryptic soy broth (TSB) was added to the stem scars of tomatoes. Tomatoes were cut from the stem scar to blossom end using a sterilized knife. After stem scars were aseptically removed, cut surfaces were placed on tryptic soy agar-rifampicin (TSA-RIF) plates or processed by a broth enrichment method to determine if S. montevideo had been transferred to the cut surface. S. montevideo was recovered in a dose-related fashion using both methods. A higher recovery rate was obtained with bacterial inocula in TSB than in BPB, and also with broth enrichment rather than the direct plating method. The distribution of the transferred S. montevideo on the cut surface of contaminated and noncontaminated tomatoes with a knife was related to the inoculum dose added to the stem scars. S. montevideo colonies were found to cluster at the stem scar region with the lower inoculum dose. However, when a higher inoculum dose was used, the colonies spread from the stem scar region to the center and bottom of cut tomatoes, or they were transferred to another uninoculated tomato by the contaminated knife. Therefore, the safety operation criteria recommended by FDA to wash fruits before cutting, to use clean and sanitized utensils and surfaces when preparing cut fruits, and to store the cut fruits below 7°C should be followed in preparing tomato slices to minimize salmonellosis outbreaks caused by this product.
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http://dx.doi.org/10.4315/0362-028X-60.7.858DOI Listing
July 1997