The present study was conducted to investigate the effect of different heights from liquid nitrogen (LN2) vapor on sperm motility and morphology after frozen-thawing. Two ejaculates were collected from 2 fertile Hanwoo bulls (A and B) by using artificial vagina at Hanwoo Research Institute. After collection, ejaculates were transferred to laboratory immediately and diluted with semen extender (Optixcell, France). Sperm dilutions were extended to a final concentration of 40 x 106 sperm/ml, and cooled at 4°C for 4 h and loaded to 0.5 ml straws. The straws were divided into 2 groups. Straws were placed in 3 or 9 cm of LN2 vapor for 14 min and then plunged into LN2 tank and cryopreserved until evaluation. Sperm motility and motility parameters (total motility, VSL with 25μm≥, VCL, VSL, VAP, LIN, STR, WOB, ALH and BCF) were evaluated by sperm class analysis (SCA, IVOS, Spain) after frozen-thawed. In bull A, 3cm group showed higher percentages of total motility, VSL with 25μm and VAP compared those with 9cm group (98.0 vs. 93.4%, 62.4 vs. 54.0% and 98.6 vs. 93.2%, 3 vs. 9 cm, irrespectively; p<0.001). In bull B, frozen-thawed sperm of 3cm group showed higher percentages of VSL with 25μm, VCL, VSL, VAP and BCF compared with those of 9cm group (43.5 vs. 26.0%, 123.8 vs. 111.6 μm, 62.9 vs. 57.3 μm and 81.5 vs. 72.5 μm; 3 vs. 9 cm, irrespectively; p<0.001). The viability and acrosomal integrity of spermatozoa were evaluated by Trypanblue/Giemsa staining method divided into 4 groups; live and intact acrosome (LIA), live and damaged acrosome (LDA), dead intact acrosome integrity (DIA), dead damaged acrosome (DDA). In bull A, frozen-thawed sperm of 3 and 9cm groups showed no significant difference in LIA, LDA, DIA and DDA. In bull B, 3 cm group showed higher LIA and lower DIA compared with those of 9 cm group (73.2 vs. 23.7% and 23.7 vs. 32.2%, 3 vs. 9 cm, irrespectively; p<0.001). We suspected that 3 cm vapor on LN2 vapor might be affected positively spermatozoa viability and acrosomal integrity compared with 9 cm group. In conclusion, semen freezing procedure in the present study will improve sperm quality after frozen thawing.

한우 인공수정용 액체질소 공급이 월1회로 정액과 같이 공급되고 있어 특히 고온 계절 에는 질소 탱크에 액체질소가 항상 일정하게 유지되고 있지 않은 실정이며 유통과정 중 에 외기에 노출되는 기회가 많이 있음으로써 동결정액의 품질저하가 쉽게 발생된다. 생산 후 유통과정에 발생되는 동결정액의 품질 평가 시기존방법의 단점인 스트로 폐기와 장비 구입비 및 검사 소요시간을 보완하고 동결정액의 품질 변화가 일어나는 ‒160℃ ‒35℃ 사이의 품질을 조사할 수 있게 하여 유통과정상의 소동결정액의 품질저하를 방지 하고 품질 평가를 실시하기위하여 제작하여 조사 하였다. 가축 인공 수정소에서 소동결 정액이 ‒100℃에 노출되는 기회가 56.5%, ‒35℃에 노출은 8.7%가 발생되었으며, 이러한 결과는 동결정액의 생존성을 ‒100℃에서 노출 될 때는 26.9%, ‒35℃에서 노출될 때는 ‒54.4%나 저하됨으로써 농가 인공수정 수태율 저하를 일으키는 주요한 원인이 되고 있 는 것으로 조사되었다.

PDT is an establi shed cancer treatment modali ty , This can be attributed to the attractive basic concept of PDT; the combina ti on 0[' two ther a peut ic agents, a photosensitizing drug and light, which are r elatively harmless by themselves but combined ultimately ca use more 0 1' less selective tumor destruction, The bacteriochlorophyll - derivatived photosensitizers are known to be s ta ble and hi ghly efficient‘ In this s tudy, we conducted a series of experiments to develope the ligh t induced anticancer drugs against oral cancer cell ‘ We tested the cytotoxicity of the hydroxybact eriochlorine by MTT a ssay and observed the cell death pattern (apoptosis or necrosis) after PDT by hoechst 33342 and propidium iodide s taining methods , IC50 value of the hydroxybacteriochlorine was 31,3ngjm.Q, At higher doses of hydroxybacteriochlorine () 60 ng/ 뼈) ， cancer cells died exc lus ively by nec rosis after PDT By contrast, at IC50 value, h ydroxybacteri ochlorine in duced ca ncel' cell to undergo a poptotic cell death The induction begins approximately 6 hours after PDT We investigates int racellu la r localizati on of hydroxybact eri ochl orine by ora l cancer cell via confocal laser scanning microscopy, Oral can cer cells dual-stained with hydroxybactel' iochlorine and organelle-specific fluoresc ence probes (Mi totracker, Lysotracker , ER- Trac ker) revealed an int l'acellula l' flu orescence distribution restrict ed to cytoplasmic compartments with no detectable fl uoresce nce in the nucleus Confocal images of cells containing hydroxybacteriochlorine were never overlap to mi tochondria, lysosome, endoplasmic l'eticulum when digitally overlapped with the organelle-specific flu orescence probe images of the same cells , These resul ts demonstrat ed that the hydroxybacteriochlorine may have a function as a photosens it izer and cytotoxicity hydroxybactel' ioc hlorine for oral ca ncer cell is more sensitive than head & neck cancer cell or cervical cance l' cell Ther efore PDT using hydroxybact eriochlorine is suitable treatment for oral cavity car cinoma patients.

Lanthanide tantalite (Ln= La, Nd, Sm, Dy, Er and Tm) was synthesized by a solid state reaction between mixed powders of and . The single-phase was prepared by sintering at temperatures of 1423-1673 K in air. The SEM observation showed that the particles were provided with the growth steps and the depeloped facets. The photocatalytic activity for water splitting of prepared was measured under UV light irradiation. The activity obtained was higher than that previously reported. These results suggested the crystallinity of photocatalysts correlates closely with the efficiency of water splitting.

Machinability improvement by the use of liquid nitrogen in cryogenic machining has been reported in various studies. This has been mostly attributed to the cooling effect of liquid nitrogen. However, No study has been found in discussion on whether liquid nitrogen possesses lubrication effect in cryogenic cutting. This paper presents lubrication mechanism related to chip microstructure. The friction reduction was further reflected In larger shear angle and less secondary deformation in the chip microstructures.

In this paper some physical evidences indicate that reduced friction occurs in an cryogenic machining process, in which LN2 is applied to the selected cutting zone. LN2 also reduced the tool wear rate to a great extent and elongated the tool life up to four times compared to emulsion cooling.

This paper presents some physical evidences indicating that reduced friction occurs in an cryogenic machining process, in which LN2 is applied selectively in well-controlled jets to the selected cutting zone. In machining tests, cryogenic machining reduced the force component in the feed direction, indicating that the chip slides on the tool rake face with lower friction. This study also found that the effectiveness of LN2 lubrication depends on the approach how LN2 is applied regarding cutting forces related.