• Geomechanics and Engineering
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• 제13권1호
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• pp.141-159
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• 2017

A pick cutter is a rock-cutting tool used in partial-face excavation machines such as roadheaders, and its quality is a key element influencing the excavation performance and efficiency of such machines. In this study, pick cutters with hardfacing deposits applied to a tungsten carbide insert were made with aim of increasing their durability and wear resistance. They were field-tested by being installed in a roadheader and compared with conventional pick cutters under the same excavation conditions for 24 hours. The hardfaced pick cutters showed much smaller weight loss after excavation, and therefore better excavation performance, than the conventional pick cutters. In particular, the damage to and detachment (loss) of tungsten carbide inserts was minimal in the hardfaced pick cutters. A detailed inspection using scanning electron microscope-energy dispersive X-ray spectrometry and three-dimensional X-ray computed tomography scanning revealed no macro- or micro-cracks in the pick cutters. The reason for the absence of cracks may be that the heads of pick cutters are mechanically worn after the tungsten carbide inserts have been worn and damaged. However, scanning revealed the presence of voids between tungsten carbide inserts and pick cutter heads. This discovery of voids indicates the need to improve production processes in order to guarantee a higher quality of pick cutters.

• 한국가축번식학회지
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• 제19권1호
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• pp.35-41
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• 1995

본 연구는 형질전화우의 생산성 제고를 위한 일환으로서 새로운 기법인 retrovirus vector system의 이용성을 검토하고자 실시하였다. Retrovirus-producing cell은 미세주입법을 이용하여 체외생산된 1.5일(1~4-세포기) 수정란의 위란강에 주입(5~10 cells/embryo) 되었으며, 이때 사용된 retrovirus-producing cell line은 Gibbon ape leukemia virus (GaLV) envelope protein에 encapsidation되어 replication-defective retrovirus를 분비하도록 제작되었다. 주입된 유전자의 표지유전자로서 E. coli LacZ 유전자를 사용하였으며, X-gal 염색법은 발달이 유도된 상실배와 배반포 단계에 실시하여 LacZ 유전자의 발현 유무를 확인하였다. 이 실험의 결과를 요약하면 다음과 같다. 1. Virus의 infectivity를 높이기 위해 사용된 polybrene의 최저농도는 5$\mu\textrm{g}$/ml이었다. 2. Retrovirus-producing cell이 주입된 1.5일 수정란의 상실배기와 배반포기로의 발달율은 29%였다. 3. 이 때의 LacZ+ 발현율은 21%였다. 4. 본 실험에 사용된 retrovirus-producing cell은 replication-competent retroviruses를 생산해 내지않는다는 것을 확인할 수 있었다.

• 한국건축시공학회지
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• 제8권1호
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• pp.57-62
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• 2008

Twelve mortars were mixed and tested to explore the effect of gypsum on the compressive strength development and shrinkage strain of alkali-activated mortars. Powder typed sodium silicate and ground granulated blast-furnace slag were employed as alkaline activator and source material, respectively, to produce cementless mortar. The main variables investigated were alkali quality coefficient combining the concentration of activator and main compositions in source material, and the adding amount of gypsum ranged between 1 and 5% with respect to the weight of binder. Initial flow, compressive strength development, modulus of rupture, and shrinkage strain behavior of mortar specimens were measured. In addition, the hydration production of alkali-activated pastes with gypsum was traced using X-ray diffraction and energy-dispersive X-ray analysis combined with scanning electron microscope image. Test results showed that the initial flow of slag-based alkali-activated mortar was little influenced by the adding amount of gypsum. On the other hand, the effect of gypsum on the compressive strength of mortar specimens was dependent on the alkali quality coefficient, indicating that the compressive strength increased with the increase of the adding amount of gypsum until a certain limit, beyond which the strength decreased slowly. Shrinkage strain of mortar tested was little influenced by the adding amount of gypsum because no ettringite as hydration product was generated. However, the adding of gypsum had a beneficial effect on reducing the microcrack in the alkali-activated mortar.

• Asian-Australasian Journal of Animal Sciences
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• 제15권11호
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• pp.1591-1598
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• 2002

The effect of different dietary structural carbohydrate (SC) to nonstructural carbohydrate (NSC) ratios on fiber degradation, digestion, flow, apparent digestibility and rumen fluid characteristics was studied with a design using 18 wethers fitted with permanent rumen and duodenum cannulae. All sheep were divided into six groups randomly, receiving six diets with varying SC to NSC ratios. All diets contained the same proportion of wheat straw and concentrate. The dietary SC to NSC ratios were adjusted by adding cornstarch to the concentrate supplements. The duodenal and fecal flows of dry matter (DM), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HC) and cellulose (CEL) were estimated using chromium-mordanted wheat straw as a flow marker. The degradation parameters of wheat straw DM, NDF, ADF, HC and CEL were determined by incubating the ground wheat straw in nylon bags in the rumen for different periods of time. There was no effect (p>0.05) of the different dietary SC to NSC ratios on rumen pH or $NH_3$-N, but acetate, propionate and butyrate concentrations were significantly affected (p<0.05 or p<0.01) by dietary SC to NSC ratios in the rumen fluid. When the dietary SC to NSC ratio was 2.86, the highest rumen degradability of wheat straw DM, NDF, ADF and CEL was found, but the highest apparent rumen digestibilities of DM, NDF, ADF, HC and CEL occurred at a 2.64 SC to NSC ratio. However, because of compensatory digestion in the hindgut, the apparent digestibilities of DM, NDF, ADF, HC and CEL were highest when the dietary SC to NSC ratio was 2.40. In conclusion, there is a optimal range of dietary SC to NSC ratios (between 2.86 and 2.40) that is beneficial to maximize wheat straw fiber degradation and apparent digestibility.

• Asian-Australasian Journal of Animal Sciences
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• 제15권12호
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• pp.1784-1789
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• 2002

One hundred and twenty-eight growing barrows (Jiaxing Black${\times}$Duroc${\times}$Landrace) at an average BW of 20.8 kg were allocated to four treatments for 42 days, each of which was replicated four times with eight pigs per replicate and used to investigate the effects of fructooligosaccharide (FOS) on digestive enzyme activities, intestinal microflora and morphology of growing pigs. The pigs received the same basal corn-soybean meal diet and FOS was added to the basal diet at 0, 2, 4, 6 g/kg diet at the expense of corn, respectively. As compared to control, supplementation with 4 and 6 g/kg FOS significantly improved average daily gain and feed efficiency. Addition of FOS enhanced the growth of Bifidobacterium and Lactobacillus, but inhibited Clostridium and Escherichia coli in the small intestinal and proximal colonic contents. Supplementation with 4 and 6 g/kg FOS significantly improved the activities of total protease, trypsin and amylase in the small intestinal contents. However, FOS had no significant effect on the activity of lipase in the small intestinal contents as well as the digestive enzymes in pancreas. Morphological measurement of jejunal mucosa did show response to consumption of FOS. Villus height and the villus height to crypt depth ratio at the jejunal mucosa were significantly higher with 4 and 6 g/kg FOS supplementation as compared to control.

• Asian-Australasian Journal of Animal Sciences
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• 제25권3호
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• pp.393-400
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• 2012

The study was conducted to examine the effects of partially replacing soybean meal (SBM) by solid-state fermented cottonseed meal (FCSM) on growth performance, serum biochemical parameters and immune function of broilers. After inoculated with Bacillus subtilis BJ-1 for 48 h, the content of free gossypol in cottonseed meal was decreased from 0.82 to 0.21 g/kg. A total of 600, day-old male yellow-feathered broilers were randomly divided into four groups with three replicates of 50 chicks each. A corn-SBM based control diet was formulated and the experimental diets included 4, 8 or 12% FCSM, replacing SBM. Throughout the experiment, broilers fed 8% FCSM had higher (p<0.05) body weight gain than those fed 0, 4 and 12% FCSM. The feed intake in 8% FCSM group was superior (p<0.05) to other treatments from d 21 to 42. On d 21, the concentration of serum immunoglobin M in the 4% and 8% FCSM groups, as well as the content of complements (C3, C4) in 8% FCSM group were greater (p<0.05) than those in the SBM group. Besides, birds fed 8% FCSM had increased (p<0.05) serum immunoglobin M, immunoglobulin G and complement C4 levels on d 42 compared with bird fed control diet. No differences (p>0.05) were found between treatments regarding the serum biochemical parameters and the relative weights of immune organs. In conclusion, FCSM can be used in broiler diets at up to 12% of the total diet and an appropriate replacement of SBM with FCSM may improve growth performance and immunity in broilers.

• Asian-Australasian Journal of Animal Sciences
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• 제26권6호
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• pp.896-904
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• 2013

Cattle breeds have a striking effect on milk, including milk composition and technological characteristics. This study aims to compare milk composition, acidification activity, viscosity, milk dispersion system stability and casein molecular weight among three buffalo breeds in China. The technological characteristics of milk produced by three cattle breeds of river buffalo (Murrah), crossbreed 1st generation ($F_1$), crossbreed multiple generation ($F_H$, $H{\geq}3$) buffaloes were investigated. Cattle breeds showed evident effect on milk protein, fat and total solids content, but little effect on most of buffalo casein molecular weight. Milk fat, protein content and the viscosity of buffalo milk from river buffalo were lower than those of $F_1$ and $F_H$, so was the buffer capacity. The viscosity was negatively correlated to temperature and concentration. Results of stability coefficient showed that milk dispersion system had the best dynamic stability characteristics under pH 6.6 and 6 times dilution, while zeta potential of Murrah milk was slightly higher than that of hybrid offspring ($F_1$, $F_H$). SDS-PAGE results showed that buffalo ${\alpha}_s$-casein had a slightly faster mobility than standard ${\alpha}_s$-casein; while buffalo ${\beta}$-casein showed a slightly slower mobility than standard ${\beta}$-casein. There is no clear differences in molecular weight of ${\alpha}_s$-, ${\beta}$-, and ${\kappa}$-casein among Murrah, $F_1$ and $F_H$.

• Asian-Australasian Journal of Animal Sciences
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• 제22권2호
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• pp.155-161
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• 2009

Mammal microsomal glutathione transferase 1 (MGST1) can conjugate many toxic or carcinogenic substances and depress oxidative stress. In this study, Chicken MGST1 and its variants were cloned for the first time and were composed of 956 or 944 nucleotides. The 12 nt deletion in the exon 2 did not alter the GT-AG rule and the ORFs for the two MGST1 variants were the same, which both comprised 465 nucletides and encoded a peptide with 155 amino acids. It was found that the two different splice variants identified using RT-PCR expressed in all three organs investigated of Dwarf Brown Chicken, namely liver, spleen and shell gland. Moreover, the expression level of MGST1 mRNA in the liver of Dwarf Brown chickens was the highest (p<0.01), and there were no significant differences between the spleen and the shell gland. These results provide a base for studying the biological function of Chicken MGST1.

• Asian-Australasian Journal of Animal Sciences
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• 제19권8호
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• pp.1079-1084
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• 2006

To determine whether a link exists between reproductive seasonality and the structure of the melatonin receptor 1A (MTNR1A) gene, the latter was studied in nonseasonal estrous breeds (Small Tail Han and Hu ewes) and seasonal estrous breeds (Dorset, Suffolk and German Mutton Merino ewes). A large fragment of the exon 2 of the MTNR1A gene was amplified and a uniform fragment of 824 bp was obtained in 239 ewes of five breeds. The 824 bp PCR product was digested with restriction endonucleases Mnl I and Rsa I, and checked for the presence of restriction sites. The presence (allele M) or absence (allele m) of an Mnl I site at base position 605 led to three genotypes MM (236 bp/236 bp), Mm (236 bp/303 bp) and mm (303 bp/303 bp) in five sheep breeds. The presence (allele R) or absence (allele r) of a Rsa I site at base position 604 led to three genotypes RR (267 bp/267 bp), Rr (267 bp/290 bp) and rr (290 bp/290 bp) in five sheep breeds. Frequencies of MM and RR genotypes were obviously higher, and frequencies of mm and rr genotypes were obviously lower in nonseasonal estrous sheep breeds than in seasonal estrous sheep breeds. Sequencing revealed four mutations (G453T, G612A, G706A, C891T) in mm genotype compared to MM genotype and one mutation (C606T) in rr genotype compared to RR genotype. For polymorphic Mnl I and Rsa I cleavage sites, the differences of genotype distributions were very highly significant (p<0.01) between Small Tail Han ewes and seasonal estrous sheep breeds. In each group, no significant difference (p>0.05) was detected. These results preliminarily showed an association between MM, RR genotypes and nonseasonal estrus in ewes and an association between mm, rr genotypes and seasonal estrus in ewes.

• 한국작물학회지
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• 제49권2호
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• pp.73-81
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• 2004

Effects of ambient and elevated $\textrm{CO}_2$ and high temperature, and their interactions with zero and applied nitrogen supply (NN-no nitrogen and AN-applied nitrogen) were studied on soybean (Glycine max L.) in 2001. In this experiment, elevated $\textrm{CO}_2$ (650 $\mu\textrm{mol}.\textrm{mol}^{-1}$) and temperature (+$5^{\circ}$) increased total dry mass at final harvest by 125% and 119% and seed weight per plant by 57% and 105% for NN and AN plants, respectively. Although the influence of temperature and temperature x $\textrm{CO}_2$ were not significant, the influences of $\textrm{CO}_2$ concentration and temperature x $\textrm{CO}_2$ concentration were significant on total dry weight and seed weight, respectively. In particular, seed weight per plant was increased, while weight per one hundred seed weight was decreased with elevated $\textrm{CO}_2$ and temperature. The N supply increased biomass and seed weight per soybean plants. The results of this study suggest that the long-term adaptation of soybean growth at an elevated $\textrm{CO}_2$ concentration and high temperature might potentially result in a increase in dry matter production and yield.