The health benefits associated with consumption of fresh produce have been clearly demonstrated and encouraged by international nutrition and health authorities. However, since fresh produce is usually minimally processed, increased consumption of fresh fruits and vegetables has also led to a simultaneous escalation of foodborne illness cases. According to the report by the World Health Organization (WHO), 1 in 10 people suffer from foodborne diseases and 420,000 die every year globally. In comparison to other processed foods, fresh produce can be easily contaminated by various routes at different points in the supply chain from farm to fork. This review is focused on the identification and characterization of possible sources of foodborne illnesses from chemical, biological, and physical hazards and the applicable methodologies to detect potential contaminants. Agro-chemicals (pesticides, fungicides and herbicides), natural toxins (mycotoxins and plant toxins), and heavy metals (mercury and cadmium) are the main sources of chemical hazards, which can be detected by several methods including chromatography and nano-techniques based on nanostructured materials such as noble metal nanoparticles (NMPs), quantum dots (QDs) and magnetic nanoparticles or nanotube. However, the diversity of chemical structures complicates the establishment of one standard method to differentiate the variety of chemical compounds. In addition, fresh fruits and vegetables contain high nutrient contents and moisture, which promote the growth of unwanted microorganisms including bacterial pathogens (Salmonella, E. coli O157: H7, Shigella, Listeria monocytogenes, and Bacillus cereus) and non-bacterial pathogens (norovirus and parasites). In order to detect specific pathogens in fresh produce, methods based on molecular biology such as PCR and immunology are commonly used. Finally, physical hazards including contamination by glass, metal, and gravel in food can cause serious injuries to customers. In order to decrease physical hazards, vision systems such as X-ray inspection have been adopted to detect physical contaminants in food, while exceptional handling skills by food production employees are required to prevent additional contamination.

The techniques of IVM, IVF and IVC of canine oocytes may provide useful information for gamete salvage programs and the conservation of endangered canidae. This investigation has been made to determine the efficiency of in vitro maturation (IVM) as a basic experiment to study the development of canine oocytes after in vitro fertilization (IVF). The rate of oocytes developing to the MII stage was higher in the hormone treated group (10 IU/ml hCG+eCG, 14.7%, p<0.05) than in the control group (0 IU/ml hCG+eCG, 10.0%). The monospermy and pronuclear rates of canine oocytes were investigated after caffeine treatment on IVF. Canine oocytes were fertilized in the Fert‐TALP medium supplemented with 0, 10, 20 or 30 mM caffeine (Fert I, Fert II, Fert III or Fert IV, respectively). The highest pronuclear formation rate was obtained in the Fert I for 24 h IVF (6.7%, 6/89). Therefore, it is believed that unlike in other mammals, caffeine in canine IVF does not increase the efficiency of fertilization rate, and is not an important factor.

Making use of our extended version of ¨ O p i k ′ s convection theory, we have calculated magnetic cycle periods of the sun and late type stars by using Parker's dynamo theory, where we have included the non-linear effect. We presented a relationship between the computed cycle period and spectral type to analyze observed magnetic activities of the late type stars and long-term luminosity variations. It is found that (1) the stellar magentic-cycle period increases towards the later spectral type, (2) the rapid rotation facilitates the activity-related luminosity variation of stars later than about K5, (3) differential rotation plays a critical role in determining the magnetic activity-cycle period, and (4) the non-local effect should be taken into account in order to understand the observed long-term luminosity variations.

We have analyzed Gray's observed mean line bisectors of FS, G0, G2, and G5 normal dwarf stars and interpreted them by computing theoretical line bisectors based on a two stream model. A set of perturbed models has been derived, and their detailed structures on temperature fluctuations and velocity fields are presented as a function of depth, which account for the observed bisectors. From the present study, it is found that the degree of stellar convective overshootings and temperature fluctuations in the upper atmospheres increases towards earlier spectral types. The convection cell size inferred from these models is found to increase also with the advancing earlier type. We demonstrated the usefulness of line bisector analysis as a diagnostic probe for stellar convection.

A generalization of the original ¨ O p i k ′ s cellular convection theory has been made to accomodate a rotating convective medium. With the use of the formulation, a set of rotating model envelopes of the sun and late type main sequence stars have been constructed under three different rotation periods. Their thermal structures are presented and characteristics of their convection are discussed in the context of stellar dynamo. In the present study it is noted that the rotational angular velocity increases in wards with depth, and its increase turns out to be about 6% at the bottom of the solar convection zone.

Making use of a relation proposed by Wielen (1977), a new empirical relation between Call emission flux and stellar age is derived by analyzing Wilson and Woolley's spectroscopic data (1970) of late type main sequence stars (K0-M5) and kinematic properties of those stars given by Gliese (1969). The proposed relation shows that the emission flux excess of the Call H-K lines, F ′ k + F ′ k introduced by Linsky et al. (1979) decreases with stellar age τ as τ − 0.51 , consistent with the inverse square law as noted by Skumanich (1972).

현재 의료분야에서는 방사선 차폐체로서 납(Pb)이 널리 쓰이고 있다. 하지만 납은 무게가 매우 무거워 납 치마 등의 방호복은 장시간 착용이 어려우며, 인체에 치명적인 납 중독의 위험이 상시 가지고 있다는 문제 점을 가지고 있다. 이러한 문제점을 해결하고자 납을 대체 할 수 있는 물질에 대한 많은 연구가 진행되고 있다. 현재 납의 대체물질로써 대표적인 바륨(Ba)과 요오드(I) 등은 우수한 차폐능을 가지고 있지만, 30keV 근처의 에너지 영역에서 특성 X선을 방출하는 특성을 가지고 있다. 환자나 방사선 종사자의 경우 차폐체를 인체에 접촉하고 있는 경우가 많으므로 차폐체에서 발생되는 특성 X선이 인체에 직접 조사되어 방사선 피 폭을 증가시킬 위험이 매우 높다. 본 연구에서는 바륨(Ba)과 요오드(I)등에서 발생되는 특성 X선을 제거하기에 적절한 이중구조 차폐체를 방사선 수송코드 중 하나인 FLUKA 수송코드를 개발하여 선행연구로서 진행된 MCNPX 시뮬레이션과 비 교 분석하여 이중구조 차폐체의 차폐율에 대한 신뢰성을 검증하고자 하였다. MCNPX와 FLUKA를 이용하 여 황산바륨(BaSO4)과 산화비스무스(Bi2O3)로 이루어진 다양한 두께조합의 이중구조 차폐체를 설계하였으 며, IEC61331-1에 제시된 모식도를 기하학적으로 동일하게 시뮬레이션 상에 구현하였다. 또한, 120 kVp 의 연속 X선 스펙트럼에 대한 차폐체의 투과스펙트럼과 흡수선량을 납과 비교 평가하였다. 평가결과, 0.3 mm-BaSO4/0.3 mm-Bi2O3 와 0.1 mm-BaSO4/0.5 mm-Bi2O3 구조에서는 33 keV와 37 keV의 특 성 X선을 모두 흡수하였으며, 90 keV 이상의 고에너지 X선에 대해서도 납과 거의 유사한 차폐효율을 보였 다. 또한, FLUKA의 수송코드는 33 keV 이하에서는 cut-off 가 발생하여 저에너지 X선 광자에 대한 전산모 사에 제약이 있지만, 40 keV 이상의 고에너지 영역에서 MCNPX와의 상대오차가 6 % 이내로 신뢰성이 매 우 우수하다는 것을 확인할 수 있었다.