• Asian-Australasian Journal of Animal Sciences
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• 제5권1호
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• pp.55-61
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• 1992

To determine the effect of time after feeding on distribution of particle size of digesta in the gastrointestinal tract, 16 sheep given orchardgrass first cut hay were slaughtered at 2, 8, 16 and 24 hours after feeding and digesta in diverse sites of the tract were sieved into four fractions of particle size larger than $1180{\mu}m$, 300-1180, 45-300 and less than 45. Following results were obtained: 1) In the reticulo-rumen, the proportion of particles larger than $1180{\mu}m$ decreased with the time after feeding, while the other particle size fractions did not change with time after feeding. 2) In the post-ruminal alimentary tract, the proportion of particles larger than $1180{\mu}m$ was significantly smaller than that in the reticulo-rumen and distribution of fractions of every particle size stayed consistently at about the same level irrespective of the time after feeding. 3) In the cecum, the fraction of particle size less than $45{\mu}m$ appeared to be selectively retained when the passage rate was considered.

• Asian-Australasian Journal of Animal Sciences
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• 제22권9호
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• pp.1256-1266
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• 2009

Effects of particle size and physical effective fibre (peNDF) of rice straw in diets on chewing activities, feed intake, flow, site and extent of digestion and rumen fermentation in goats were investigated. A 4${\times}$4 Latin square design was employed using 4 mature Liuyang black goats fitted with permanent ruminal, duodenal, and terminal ileal fistulae. During each of the 4 periods, goats were offered 1 of 4 diets that were similar in nutritional content but varied in particle sizes and peNDF through alteration of the theoretical cut length of rice straw (10, 20, 40, and 80 mm, respectively). Dietary peNDF contents were determined using a sieve for particle separation above 8 mm, and were 17.4, 20.9, 22.5 and 25.4%, respectively. Results showed that increasing the particle size and peNDF significantly (p<0.05) increased the time spent on rumination and chewing activities, duodenal starch digestibility and ruminal pH, and decreased ruminal starch digestibility and $NH_{3}$-N concentration. Intake and total tract digestibility of nutrients (i.e. dry matter, organic matter, and starch) and ruminal fermentation were not affected by the dietary particle size and peNDF. Increased particle size and peNDF did not affect ruminal fibre digestibility, but had a great impact on the intestinal and total tract fibre digestibility. The study suggested that rice straw particle size or dietary peNDF was the important influential factor for chewing activity, intestinal fibre and starch digestibility, and ruminal pH, but had minimal impact on feed intake, duodenal and ileal flow, ruminal and total tract digestibility, and ruminal fermentation.

• 한국화재소방학회논문지
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• 제33권6호
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• pp.95-104
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• 2019

화재 시 발생하는 연기는 가스상 물질과 이들을 흡착한 미연탄소 등의 입자상 물질로 이루어져 있다. 연기 중 가스상 물질의 흡입에 의한 인체피해는 대부분 단기적으로 이루어지는 데 비하여 입자상 물질의 흡입에 의한 피해는 가스상의 흡착상태에 따라서 상대적으로 장기적으로 이루어진다. 입자상 물질이 호흡기벽에 침착하여 호흡기 및 순환기 계통에 영향을 미치는 것과 관련하여, 침착되는 연기입자의 양과 호흡기 내 침착위치는 인체피해 산정의 중요한 요소인데, 이들은 연소조건에 영향을 받는 크기 및 농도 등 입자상태와 함께 호흡조건에 영향을 받는다. 이 연구에서는 화재 시 발생하는 연기의 흡입에 의한 인체피해 연구와 관련된 호흡기 내 연기입자 침착특성 파악을 위하여 연료종류, 연소조건 및 호흡조건에 따라 호흡기 내 영역별로 침착되는 연기입자의 입경에 따른 개수 및 질량 농도를 구하였다. 또한 각 조건별로 흡입연기의 일정기간 동안 호흡기 내 질량 침착량을 대기환경 미세먼지 기준치와 비교 분석하였다.

• Journal of Microbiology and Biotechnology
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• 제25권10호
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• pp.1714-1727
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• 2015

This work describes a new strategy for optimal design of Multiplex-PCR primer sequences. The process is based on the Particle Swarm Optimization-Simplex algorithm (Mult-PSOS). Diverging from previous solutions centered on heuristic tools, the Mult-PSOS is selfconfigured because it does not require the definition of the algorithm's initial search parameters. The successful performance of this method was validated in vitro using Multiplex-PCR assays. For this validation, seven gene sequences of the most prevalent bacteria implicated in urinary tract infections were taken as DNA targets. The in vitro tests confirmed the good performance of the Mult-PSOS, with respect to infectious disease diagnosis, in the rapid and efficient selection of the optimal oligonucleotide sequences for Multiplex-PCRs. The predicted sequences allowed the adequate amplification of all amplicons in a single step (with the correct amount of DNA template and primers), reducing significantly the need for trial and error experiments. In addition, owing to its independence from the initial selection of the heuristic constants, the Mult-PSOS can be employed by non-expert users in computational techniques or in primer design problems.

• Asian-Australasian Journal of Animal Sciences
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• 제13권9호
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• pp.1219-1227
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• 2000

Rumination behavior, in vivo digestibility of cell wall constituents, particle size reduction in the rumen, and retention time in the digestive tract of sheep were examined using rice and oat straw as roughage sources. The in sacco digestibility, rumen fermentation, and microbial population and internal adenosine 5-triphosphate (ATP) content were also determined under feeding conditions of high-roughage and high-concentrate diets. Chewing number and time in rumination behavior were higher with rice straw than with oat straw, while the in sacco and in vivo DMD of rice straw were consistently lower than those of oat straw. Rice straw also showed higher frequency of thinner and longer particles in the rumen contents and lower retention time in the whole digestive tract as compared to those of oat straw. Rice straw was more effective to maintain the ruminal pH than oat straw, being reflected in higher internal ATP content of large-type protozoa on the high- concentrate diet. Changes in the ruminal microflora by shifting from the low- to the high- concentrate diet were also different between rice and oat straw.

• Journal of Pharmaceutical Investigation
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• 제38권2호
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• pp.127-134
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• 2008

Peroral administration is the most convenient one for the administration of pharmaceutically active compounds. Most of poorly water-soluble drugs administered via the oral route, however, remain poorly available due to their precipitation in the gastrointestinal (GI) tract and low permeability through intestinal mucosa. In this study, one of drug delivery carriers, lipid nanoparticles (LNPs) were designed in order to reduce side effects and improve solubility and stability in GI tract of the poorly water soluble drugs. However, plain LNPs are generally unstable in the GI tract and susceptible to the action of acids, bile salts and enzymes. Accordingly, the surface of LNPs was modified with polyethylene glycol (PEG) for the purpose of improving solubility and GI stability of paclitaxel (PTX) in vitro. PEG-modified LNPs containing PTX was prepared by spontaneous emulsification and solvent evaporation (SESE) method and characterized for mean particle diameter, entrapping efficiency, zeta potential value and in vitro GI stability. Mean particle diameter and zeta potential value of PEG-modified LNP containing PTX showed approximately 86.9 nm and -22.9 mV, respectively. PTX entrapping efficiency was about 70.5% determined by UV/VIS spectrophotometer. Futhermore, change of particle diameter of PTX-loaded PEG-LNPs in simulated GI fluids and bile fluid was evaluated as a criteria of GI stability. Particle diameter of PTX-loaded PEG-LNPs were preserved under 200 nm for 6 hrs in simulated GI fluids and bile fluid at $37^{\circ}C$ when DSPE-mPEG2000 was added to formulation of LNPs above 4 mole ratio. As a result, PEG-modified LNPs improved stability of plain LNPs that would aggregate in simulated GI fluids and bile solution. These results indicate that LNPs modified with biocompatible and nontoxic polymer such as PEG might be useful for enhancement of GI stability of poorly water-soluble drugs and they might affect PTX absorption affirmatively in gastrointestinal mucosa.

• 한국대기환경학회지
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• 제19권5호
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• pp.551-560
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• 2003

Particle deposition in human lungs was investigated theoretically by using asymmetric five-lobe lung model. The volumes of each of the five lobes were different, thereby forming an asymmetric lung structure. The tidal volume and flow rate of each lobe were scaled according to lobar volume. The total and regional deposition with various breathing patterns were calculated by means of tracking volume segments and accounting for particle loss during inhalation and exhalation. The deposition fractions were obtained for each airway generation and lung lobe, and dominant deposition mechanisms were investigated for different size particles. Results show that the tidal volume and flow rate have a characteristic influence on particle deposition. The total deposition fraction increases with an increase in tidal volume for all particle sizes. However, flow rate has dichotomous effects: a higher flow rate results in a sharp increase in deposition for large size particles, but decreases deposition for small size particles. Deposition distribution within the lung shifts proximally with higher flow rate whereas deposition peak shifts to the deeper lung region with larger tidal volume. Deposition fraction in each lobe was proportional to its volume. Among the three main deposition mechanisms, diffusion was dominant for particles < 0.5 ${\mu}{\textrm}{m}$ whereas sedimentation and impaction were most influential for larger size particles. Impaction was particularly dominant for particles> 8 ${\mu}{\textrm}{m}$. The results may prove to be useful for estimating deposition dose of inhaled pollutant particles at various breathing conditions.

• Asian-Australasian Journal of Animal Sciences
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• 제5권1호
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• pp.13-18
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• 1992

Three cattle, a sheep and a goat were slaughtered to determine the distribution of digesta particles and mean size of digesta particles. Aliquot samples of digesta in the diverse sites of the digestive tracts were fractionated by a wet sieving technique. Fractionated particles were analyzed by the magnetic grid analyzer system constructed by authors. Results showed that the proportion of particles in digesta was similar among the omasum, abomasums cecum, colon and rectum, but that for the reticulo-ruminal digesta was different from the others. The pattern of the mass base frequency distribution of particles was also similar in the post-ruminal digesta. Average Heywood's diameter (the diameter equivalent to that of a circle with equal area to a projected area of a given particle) was about 1.2 mm in the reticulo-ruminal digesta and decreased to 0.65 mm for cattle or to about 0.35 mm for sheep and goat in the omasal digesta. Average Heywood's diameter was about the same in the post-ruminal digesta. It is concluded that mean particle size and particle distribution in digesta of the rectum or feces reflect those in digesta of the omasum.

• 한국대기환경학회지
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• 제15권5호
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• pp.657-665
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• 1999

Particulate matter produced by diesel engines is of concern to cngine manufactures because of its environmental impact. The majority of diesel particles are in the range of smaller than 1 ${\mu}{\textrm}{m}$. Because of their tiny volume, ultrafine diesel particles contribute very little to the total mass concentration which is currently regulated for automobile emissions. Ultrafinc particles are known to have deleterious effects upon human health cspecially because they penetrate deeply human respiratory tract and have negative effects on the health. In this study, the engine exhaust gas was diluted in a dilution tunnel and the particle size distribution was measured using the scanning mobility particel sizer system. Measurements of the number and the mass concentrations of the diesel exhaust were made under different engine ooperating conditions. The dilution sampling system provided a common basis for collection of the exhaust by cooling and diluting the source emission prior to the measurement. The measurement results showed that the particle size distributions of the exhaust from the diesel vehicles equipment with either heavy-duty or lignt-duty diesel engines, were similar in the particle size range of 0.08~0.2${\mu}{\textrm}{m}$.

• 한국패류학회지
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• 제14권2호
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• pp.149-159
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• 1998

In order to observe the anticellulolytic localization in the epithelia of the digestive tract such as esophagus, crop, and intestine of a Korean land snail N. samarangae, a cytochemical method and a immunogold labelling method were applied. For the cytochemical study on the cellulase activity, Benedict reaction method applied. And for the immunocytochemical study, the rabbit serum immunoglobuins (IgG) was obtained from the rabbits injected with cellulase which was extracted from body fluid of the snail. The digestive tract tissues of N. samarangae were fixed with 4% paraformaldehyde and 2% OsO4 and embedded in Lowicryl K4M at -40$^{\circ}C$ under UV light (360 nm). The thin sections were loaded on the nickel grids and stained with the serum IgG and protein A-gold complex (particle size: 10 nm). Observations were undertaken with transmission electron microscope (Jeol, JEM-1010). The epithelium of the digestive tract was consisted of five types of cells. In the cytochemical study, the reaction products were found along the periphery of the vacuoles derived from the Bebedict reaction. In the immunocytochemical study, the protein-A gold particles were selectively labelled in Type 1, Type 3 and Type 4 cells in intestinal tissue. membranes of rER, in the surrounding cytoplasm of the rER and secretory granules, and in the apical cytoplasm of the cells. On the material being secreted from the apical cytoplasm was also labelled with the immunogold particles. The all results obtained throughtout present study suggest that the intestinal epithelium of the snail N. samarangae seretes cellulase as one of digestive enzymes.