MICAL-like Regulates Fasciclin II Membrane Cycling and Synaptic Development

Nahm, Minyeop,Park, Sunyoung,Lee, Jihye,Lee, Seungbok Korean Society for Molecular and Cellular Biology 2016 Molecules and cells Vol.39 No.10

Fasciclin II (FasII), the Drosophila ortholog of neural cell adhesion molecule (NCAM), plays a critical role in synaptic stabilization and plasticity. Although this molecule undergoes constitutive cycling at the synaptic membrane, how its membrane trafficking is regulated to ensure proper synaptic development remains poorly understood. In a genetic screen, we recovered a mutation in Drosophila mical-like that displays an increase in bouton numbers and a decrease in FasII levels at the neuromuscular junction (NMJ). Similar phenotypes were induced by presynaptic, but not postsynaptic, knockdown of mical-like expression. FasII trafficking assays revealed that the recycling of internalized FasII molecules to the cell surface was significantly impaired in mical-like-knockdown cells. Importantly, this defect correlated with an enhancement of endosomal sorting of FasII to the lysosomal degradation pathway. Similarly, synaptic vesicle exocytosis was also impaired in mical-like mutants. Together, our results identify Mical-like as a novel regulator of synaptic growth and FasII endocytic recycling.

Electronic transport and carrier concentration in conductive ZnO:Ga thin films

Nahm, C.,Shin, S.,Lee, W.,Kim, J.I.,Jung, D.R.,Kim, J.,Nam, S.,Byun, S.,Park, B. Elsevier 2013 Current Applied Physics Vol.13 No.2

Transparent and conductive Ga-doped ZnO (ZnO:Ga) films were post-annealed after sputter deposition, and their structural and electrical properties were investigated. Post-annealing led to an improvement of crystallinity along the [001] direction, but did not change lateral grain size. Therefore, carrier concentration and electron mobility of films were analyzed as a function of crystallinity. The electrical parameters were obtained with both optical reflectance based on the Drude free-electron model and the Hall method, and similar tendencies were observed within the two methods. Even though the lowest resistivity was demonstrated by the film annealed at 550 <SUP>o</SUP>C, the optimum values for carrier concentration and mobility were observed in films with different post-annealing temperatures.

Mechanical Properties Evaluation of Nano-Structured Materials in Scanning Electron Microscope

Nahm, Seung Hoon,Jang, Hoon Sik,Jeon, Sank Koo,Lee, Hak Joo Trans Tech Publications, Ltd. 2010 Materials science forum Vol.654 No.-

<P>To apply nano-structured materials in micro/nano system, understanding of the mechanical properties of nano-structured materials is required. In order to perform the mechanical test of nano-structured materials, the mechanical testing system was installed in a scanning electron microscope (SEM). The nano-manipulator was set up in the SEM, and the force sensor formed as a cantilever was mounted on the nano-manipulator. Then, the force sensor can be controlled by using the nano-manipulator. The nano-structured materials were dispersed on the transmission electron microscope (TEM) grid, and both end of the nano-structured materials were welded on the TEM grid and the tip of force sensor by exposing E-beam of the SEM. The tensile tests for carbon nanotubes, ZnO nanorods and ZnS nanowires were carried out in the SEM, respectively. The load response during the mechanical test was obtained by force sensor. The dimension of nano-structured materials was obtained by determining the configuration measured from the TEM. And, strain-stress curve was obtained after mechanical test. The elastic modulus of the nano-structured materials after the tensile tests were calculated and compared. The elastic modulus for multi-walled carbon nanotubes, ZnO nanorod and ZnS nanowire were ~0.98 TPa, ~59 and ~39 GPa, respectively.</P>

The Word Stress Rules in Korean

Nahm, Yong-Woo The Korean Society Of Phonetic Sciences And Speech 1987 말소리 Vol.11 No.-

A study on the Correlation of Peak counts between the Mechanical and the Optical Measurements in Surface Metrology

Nahm, Kie B.,Tiziani, Hans J. Optical Society of Korea 1991 한국광학회지 Vol.2 No.2

Monitoring the surface profile real time on the manufacturing line of planar products has been accomplished by employing the scattering of a laser light. The laser beam was focused onto the surface and the direction of the reflected beam was utilized to obtain the slope of the surface facet. By taking data fast enough, it was possible to obtain the microscopic surface structure. The mean roughness thus obtained agreed well with the ones found with the mechanical stylus instrument. There was discrepancy between the two results as to the number of peaks per com. A simple model based on the deconvolution of the raw data was found adequate to improve the agreement to an acceptable level.

A Study on the Reducing Pollutants in Non-Ruminant Manure by Increasing Feed Utilization

Nahm, K.H. The Korean Society of Poultry Science 2001 韓國家禽學會誌 Vol.28 No.3

가축사육이 집단화되면서 가축배설물의 축적은 집중화 현상을 초래하게 되었고 또 계속적인 분뇨 분비물의 유출은 환경공해의 요인이 되고 있으며 이는 공공의 걱정거리로 대두되고 있다. 가축분뇨 중에서 질소와 인이 환경공해요인이 되는 가장 중요한 영양소이지만 가축이나 축산시설물에서 발생되는 냄새 역시 공해의 요인이 되고 있다. 급여되는 사료의 영양소효율을 높이는 길이 환경공해를 감소시키는 방법이다. 가장 많은 실험은 닭과 돼지를 대상으로 하여 이루어졌다. 사료첨가제의 이용, 사양방법의 수정 등으로 사료중의 영양소 이용성을 높임으로서 질소와 인의 배출감소는 물론 냄새와 분의 건물함량을 줄일 수 있었다. 1) 합성아미노산 제제를 사료 중에 첨가하고 단백질 수준을 감소시켰을 때 육계의 경우 10∼27%의 질소배출을 기대할 수 있었으며 산란계의 경우 18∼35%, 돼지의 경우 62%, 돼지에서 생성되는 냄새를 9∼43%까지 감소시키는 효과를 기대 할 수 있었다. 2) 사료 중에 효소제를 첨가하였을 때 육계 분의 건물함량을 12∼15% 감소시킬 수 있었다. 3) phytase를 첨가할 경우 분으로 배설되는 인의 함량은 양계의 경우 25∼35%,돼지의 경우 9∼43%까지 감소가 가능했다. 4) 성장촉진제를 이용할 경우 돼지에서 질소의 배설 양을 5∼30% 감소시킬 수 있었으며 냄새는 53∼55%까지 감소가 가능했다. 5) 사료배합을 요구량에 가깝게 하여 급여하였을 때 양계나 양돈의 경우 질소와 인은 각각 10∼15% 감소를 기대 할 수 있었으며 돼지의 냄새는 28∼79%까지 감소가 가능했다. 6) 기별 사양을 철저히 실시함으로서 양계와 양돈의 경우 질소는 10∼33%, 인산은 10∼13%, 그리고 성장 비육돈의 경우 49∼79% 감소를 기대 할 수 있다. 7) 닭이나 돼지의 사료를 배합시 소화율이 높은 곡류를 이용하면 질소와 인의 배설을 5% 감소시킬 수 있다. Localization of livestock facilities leads to concentration of livestock wastes and subsequent leakage of pollutants into the environment, resulting in public concern about their effects. Nitrogen (N) and phosphorus (P) are the most harmful components of animal manure, but odor from the manure itself and the livestock facilities is also a problem. Improving the nutrient efficiency of the livestock helps to decrease excretion of these environmental contaminants. Pigs and chickens are the main experimental models used in studies to improve nutrient efficiency. Addition of feed supplements and modifying feeding systems to improve nutrient efficiency can result in significant decrease in the N, P, odor and dry matter (DM) weight of manure. Examples of these methods include the following. 1) Addition of synthetic amino acids and reducing protein contents resulted N reductions of 10∼27% in broilers, 18∼35% in chicks and layers, 19∼62% in pigs, and a 9∼43% reduction in odor in pigs. 2) Enzyme supplementation resulted in a 12∼15% reduction in DM weight in broiler manure. 3) Phvtase supplementation resulted in P reductions of 25∼35% in chickens and 20∼60% in pigs. 4) Use of growth promoting substances resulted in a 5∼30% reduction in N and a 53∼56% reduction in odor of pigs. 5) Formulating diets closer to requirements (diet modification) reduced N and P by 10∼15% each in chickens and pigs, and odor by 28∼ 79% in pigs. 6) Phase feeding reduced N and P excretion by chicken and pigs from 10∼33% and 10∼13% each, as well as odor in growing and finishing pigs by 49∼79%. 7) Use of highly digestible raw materials in feed reduced N and P excretion by 5% in chickens and pigs.

Causes of Nitrogen Loss during Animal Manure Analysis

Nahm, K.H. The Korean Society of Poultry Science 2001 韓國家禽學會誌 Vol.28 No.3

Since nitrogen(N) is a volatile compound affected by many environmental factors, determining the N content of manure tends to be difficult. Upon arrival in the laboratory, the manure should be moist and refrigerated. Manure samples will have variable N contents due to drying temperature, and the presence of soil in the sample will affect N content. Acidification of the sample prevents ammonia volatilization and should be done before drying. It is recommended that manure samples be pretreated with a strong oxidizing agent, KMnO$_4$, followed by digestion under reduced conditions (reduced Fe-$H_{2}$ $SO_{4}$ ), which achieves a complete recovery of both $NO_{3}$ -N and $NO_{2}$ -N without a low recovery of $NH_{4}$ -N, resulting in a more accurate determination of N content. Accuracy of results for N content determined by recently developed rapid analysis techniques in the field should be tested by comparison with results obtained at laboratories using approved standard methods. Most commonly, the Kjeldahl system is used to determine manure N content. More research is needed on the effects of species, breed, age and individuals on the nutrient contents of manure. The procedures for manure sampling on the farm, shipping and handling of the sample until it reaches the laboratory, and the methods of sampling of the manure at the laboratory must be studied. Development of animal agricultural laboratories where feed, manure, soil, and water are all analyzed by appropriate specialists is needed. 질소(N)는 그 자체가 환경적인 요인에 따라 영향을 받는 휘발성 물질이어서 가축의 분뇨(분에는 반드시 뇨가 묻어 있기 때문에 다음부터는 분이라는 말로 대치한다)중에 함유되어 있는 N의 함량을 정량하기란 무척 어렵다. 우선 가축의 분이 실험실에 도착하면 수분이 있는 상태에서 냉장고에 보관되어야 한다. 분중에 함유되어 있는 N는 건조 온도에 따라 함량에 변화를 일으키며 또 시료에 흙이 묻어 있는가에 따라서도 N의 함량 정량에 영향을 받는다. 시료를 산성화하면 암모니아의 휘발이 방해된다. 따라서 시료를 산성화시킬 때는 건조전에 이루어져야 한다. 분 분석을 위한 이상적인 분 전처리는 강산화제 ($KMnO_{4}$ )로 우선 처리 한 후 다시 환원제 (Fe- $H_{2}$ $SO_{4}$)를 처리한 상태에서 시료를 소화시키면 가장 정량하기 어려운 $NH_{4}$ -N도 같이 정량이 가능하며 질소의 전체정량이 정확히 이루어질 수 있다. 질소정량의 정확성이 야외에서 이루어질 수 있도록 최근 여러 가지의 약식분석방법이 개발되고 있지만 그 결과는 반드시 공인된 분석방법에 의하여 실험실에서 분석된 결과치와 비교되어야 한다. 실험실에서 일반적으로 질소 정량에 많이 이용되고 있는 방법은 켈달 분석방법이다. 앞으로 가축의 종류나 품종, 나이 또는 개체간에 대한 분의 영양소 함량에 관한 연구가 많이 이루어져야 한다. 또 분에 대한 농장에서의 시료 채취과정, 운반, 및 실험실에 도착한 후 처리 과정 그 다음 실험실에서 분석을 위한 시료채취과정 등에 대한 연구도 이루어져야 한다. 사료, 분뇨, 토양, 그리고 물을 함께 분석하는 동물농업의 발전을 필요하며 적당한 전문가의 이용이 필요하다.

Magnetic and structural properties of ultrathin magnetic films: Ni/Pt(111)

Nahm, T.U.,Oh, S.J. The Korean Vacuum Society 2003 Applied Science and Convergence Technology Vol.12 No.1

We have studied magnetic and structural properties of ultrathin Ni films grown on PI(lII) surface using in situ surface magneto-optic Kerr effect and X-ray photoelectron spectroscopy. Perpendicular magnetic anisotropy was absent, and longitudinal Kerr signal was only detectable for Ni films thicker than 6 monolayers. Enhancement in longitudinal Kerr signal by 30% was achieved by post-annealing at temperatures below 800K, but upon annealing at 820K, surface alloy was formed. By using core-level binding-energy shifts, the composition was determined to be Ni 70 at. %.

Doping Effect of Yb₂O₃ on Varistor Properties of ZnO-V₂O₅-MnO₂-Nb₂O₅ Ceramic Semiconductors

Nahm, Choon-Woo Materials Research Society of Korea 2019 한국재료학회지 Vol.29 No.10

This study describes the doping effect of $Yb_2O_3$ on microstructure, electrical and dielectric properties of $ZnO-V_2O_5-MnO_2-Nb_2O_5$ (ZVMN) ceramic semiconductors sintered at a temperature as low as $900^{\circ}C$. As the doping content of $Yb_2O_3$ increases, the ceramic density slightly increases from 5.50 to $5.54g/cm^3$; also, the average ZnO grain size is in the range of $5.3-5.6{\mu}m$. The switching voltage increases from 4,874 to 5,494 V/cm when the doping content of $Yb_2O_3$ is less than 0.1 mol%, whereas further doping decreases this value. The ZVMN ceramic semiconductors doped with 0.1 mol% $Yb_2O_3$ reveal an excellent nonohmic coefficient as high as 70. The donor density of ZnO gain increases in the range of $2.46-7.41{\times}10^{17}cm^{-3}$ with increasing doping content of $Yb_2O_3$ and the potential barrier height and surface state density at the grain boundaries exhibits a maximum value (1.25 eV) at 0.1 mol%. The dielectric constant (at 1 kHz) decreases from 592.7 to 501.4 until the doping content of $Yb_2O_3$ reaches 0.1 mol%, whereas further doping increases it. The value of $tan{\delta}$ increases from 0.209 to 0.268 with the doping content of $Yb_2O_3$.

The Syntactic Component in a Transformational Grammar

Nahm Sheik Park(朴南植) 서울대학교 언어교육원 1969 語學硏究 Vol.5 No.1