• Nuclear Engineering and Technology
• /
• v.40 no.1
• /
• pp.1-8
• /
• 2008

One of the major current challenges to nuclear energy lies in its competitiveness. To stay competitive the industry needs to reduce maintenance and fuel cycle costs, while enhancing safety features. Extended burnup is one of the methods applied to meet these objectives However, there are a number of potential fuel failure causes related to increased burnup, as follows: l) Corrosion of zirconium alloy cladding and the water chemistry parameters that enhance corrosion; 2) Dimensional changes of zirconium alloy components, 3) Stresses that challenge zirconium alloy ductility and the effect of hydrogen (H) pickup and redistribution as it affects ductility, 4) Fuel rod internal pressure, 5) Pellet-cladding interactions (PCI) and 6) pellet-cladding mechanical interactions (PCMI). This paper discusses current and potential failure mechanisms of these failure mechanisms.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.193-193
• /
• 2002

Methylmercury causes severe central nervous system disorders. Despite the efforts of many researchers, the mechanisms involved in methylmercury toxicity and the defense against this toxicity remain unknown. We focused on the fact that drug resistance is sometimes involved in elevation of the concentration of the intracellular target of the drug. (omitted)

• Archives of Plastic Surgery
• /
• v.41 no.6
• /
• pp.630-637
• /
• 2014

A long nose with a drooping tip is a major aesthetic problem. It creates a negative and aged appearance and looks worse when smiling. In order to rectify this problem, the underlying anatomical causes should be understood and corrected simultaneously to optimize surgical outcomes. The causes of a drooping tip of a long nose are generally classified into two mechanisms. Static causes usually result from malposition and incorrect innate shape of the nasal structure: the nasal septum, upper and lower lateral cartilages, and the ligaments in between. The dynamic causes result from the facial expression muscles, the depressor septi nasi muscle, and the levator labii superioris alaeque nasi muscle. The depressor septi nasi depresses the nasal tip and the levator labii superioris alaeque nasi pulls the alar base upwards. Many surgical methods have been introduced, but partial approaches to correct such deformities generally do not satisfy East Asians, making the problem more challenging to surgeons. Typically, East Asians have thick nasal tip soft tissue and skin, and a depressed columella and alar bases. The authors suggest that multifactorial approaches to static and dynamic factors along with ancillary causes should be considered for correcting the drooping tip of the long noses of East Asians.

• Asian Pacific Journal of Cancer Prevention
• /
• v.15 no.10
• /
• pp.4125-4128
• /
• 2014

The median ages at death from cancers between 1985 and 2005 were calculated to demonstrate that inherent anticancer mechanisms may be a common pathway for different cancers. Seventy-eight patients with gastric, liver and lung cancers, were recruited in the solid cancer group. The leukemia group consisted of 31 patients with three main types of leukemia. The controls were 100 healthy individuals. The samples were typed using an HLA-DR/DQ PCR-SSP typing kit. The results showed that the median ages at death from all causes were 64.7 years in 1985 and 70.1 years in 2005. The range of the median ages at death from all cancers was similar to the corresponding value for deaths attributed to all causes. The frequency of $DRB1^*03$ was 9.6% in the solid cancer group and 3.0% in the control group (p<0.05). The frequency of $DRB1^*04$ in the leukemia group were significantly lower than that of the control (p<0.05). $DRB1^*13$ and $DRB1^*06$ frequencies in the leukemia group were significantly higher than those of the controls (p<0.05). It is suggested that inherent anti-cancer mechanisms may be a common pathway for different cancers and are associated with the immune system and HLA.

• Toxicological Research
• /
• v.17
• /
• pp.117-125
• /
• 2001

Envenoming by Russells viper causes a broad spectrum of renal impairment. Renal failure is an important complication in patients bitten by Russells viper. Experimental work in animals and in vitro has elucidated pathophysiological mechanisms that contribute to life threatening complications and have suggested possibilities for therapeutic intervention. The evidence in experimental animals regarding mechanisms of venom action in relation to changes in either extrarenal or intrarenal factors is presented. The cardiovascular system and renal hemodynamics are affected by venom. Reductions of renal function including renal hemodynamics are associated directly with changes in general circulation during envenomation. Possible endogenous mechanisms for releasing the hormone inducing renal vasoconstriction after envenomation are evident. Hormonal factor such as the catecholamine, prostaglandin and renin angiotensin systems induce these changes. Direct nephrotoxicity of venom action is studied in the isolated per-fused kidney. Characteristic polarization of the cell membrane, changes of mitochondrial activity and Na-K ATPase in renal tubular cells are observed. Changes in renal function and the cardiovascular system are observed of ter envenomation and are reversed by the administration of Russells viper antivenom (purified equine immunoglobulin, $Fab_2$ fragment). The neutralizing effects are more efficient when the intravenous injection of antivenom is given within 30 min after the envenomation.

• Proceedings of the KWS Conference
• /
• 2002.10a
• /
• pp.675-680
• /
• 2002

Cracking and bulging in welded and internally lined pressure vessels that work in thermal-mechanical cycling service have been well known problems in the petrochemical, power and nuclear industries. However, published literature and industry surveys show that similar problems have been occurring during the last 50 years. A better understanding of the causes of cracking and bulging causes is needed to improve the reliability of these pressure vessels. This study attempts to add information required for increasing the knowledge and fundamental understanding required. Typical examples of this problem are the coke drums in the delayed coking units refinery process. This case was selected for experimental work, field study and results comparison. Delayed coking units are among the refinery units that have higher economical yields. To shut down these units represents a high negative economical impact in refinery operations. Also, the maintenance costs associated with repairs are commonly very high. Cracking and bulging occurrences in the coke drums, most often at the weld areas, characterize the history of the operation of delayed coking units. To design and operate more robust coke drums with fewer problems, an improved metallurgical understanding of the cracking and bulging mechanisms is required. A methodology that is based field experience revision and metallurgical analyses for the screening of the most important variables, and subsequent finite element analyses to verify hypotheses and to rank the variables according to their impact on the coke drum lives has been developed. This indicated approach provides useful information for increasing coke drum reliability. The results of this work not only order the most important variables according to their impact in the life of the vessels, but also permit estimation of the life spans of coke drums. In conclusion, the current work shows that coke drums may fail as a combination of thermal fatigue and other degradation mechanisms such as: corrosion at high and low temperatures, detrimental metallurgical transformations and plastic deformation. It was also found that FEA is a very valuable tool for understanding cracking and bulging mechanisms in these services and for ranking the design, fabrication, operation and maintenance variables that affect coke drum reliability.

• The Journal of Korean Medicine
• /
• v.42 no.2
• /
• pp.72-81
• /
• 2021

Objectives: We compared research characteristics of western medicine, Chinese medicine and Korean medicine on causes, mechanisms, types, treatments and prevention of psoriasis. Methods: For western medicine, "Psoriasis" was used as keyword on Pubmed, for Chinese medicine, "銀屑病" and "中医" on CNKI (China National Knowledge Infrastructure" and for Korean medicine, "건선" on OASIS. Keyword searches were done for papers and books published after 2010. For Chinese medicine, there were more in-depth searches done for "從血論 (血熱, 血瘀, 血燥)" and "陽虛症". Results: Western medicine puts an emphasis on the foci, and approaches it from molecular and genetic levels based on molecular biology; while it views psoriasis as a disease with multiple possible causes, it ultimately sees it as an inflammation that is immunity-mediated. Western medicine seeks to suppress cytokine in order to prevent and eliminate inflammation at each stage of treatment While they are effective short-term, psoriasis recurs shortly after. Chinese and Korean medicines categorize psoriasis as an internal comprehensive systemic diseases that encompasses the patient's physical and mental characteristics, and defines it as a disease that has many causes and mechanisms such as "血熱, 血瘀, 血燥" and "陽虛". They use herbal medicine, acupuncture, and lifestyle interventions to improve the overall health of the patient in addition to treating psoriasis. Treatments are effective, but it takes relatively longer to see results, and can recur. Conclusion: In order for more progress to happen on psoriasis treatment, each branch of medicine must exchange knowledge and information more frequently.

• Sleep Medicine and Psychophysiology
• /
• v.1 no.1
• /
• pp.3-8
• /
• 1994

With the recent development of sleep medicine, insomnia has been perceived as a disease from a simple symptom. As there are various causes in a disease, proper treatment according to each cause is necessary for a more effective treatment In general, insomnia is classified into five categrories of physical, physiological, psychological, psychiatric and pharmacological aspects. However, such categorizations are often insufficient in treating insomnia. Furthermore understanding of the developmental mechanisms of insomnia is required. The function of sleep is developed and maintained through the balance of the reciprocal forces of sleep and arousal. These forces are contantly regulated by what is called a circadian rhythm. Sleep is induced by this rhythm which is affected by factors such as awakening time in the morning, amount of intellectual function, amount and time length of physical exercise and sunlight Insomnia could develop when this rhythm is delayed and leads to a "forbidden zone" which is a very difficult period for inducing sleep about two to four hours before the routine bedtime. Whereas sleep gradually develops in line with the circardian rhythm, arousal can occur very abruptly by any cause triggered by emotional discomfort or anxiety. Such characteristic and emotional factors as perfectionism, separation anxiety, secondary gain, insecurity, and negative cognition may provoke the inner anxiety and fear for insomnia, which can lead acute insomnia to a chronic one. As chronic insomnia is developed by multiple causes and factors, integrated approaches through analysis of above mentioned factors will be more effective in the treatment of insomnia than a simple administration of hypnotics.

• Clinical and Experimental Pediatrics
• /
• v.56 no.12
• /
• pp.505-513
• /
• 2013

Because the prevalence of allergic diseases has significantly increased in recent years, understanding the causes and mechanisms of these disorders is of high importance, and intense investigations are ongoing. Current knowledge pinpoints immune tolerance mechanisms as indispensable for healthy immune response to allergens in daily life. It is evident that development and maintenance of allergen-specific T cell tolerance is of vital importance for a healthy immune response to allergens. Such tolerance can be gained spontaneously by dose-dependent exposures to allergens in nature or by allergen-specific immunotherapy. Allergen-specific immunotherapy induces regulatory T cells with the capacity to secrete interleukin-10 and transforming growth factor-${\beta}$, limits activation of effector cells of allergic inflammation (such as mast cells and basophils), and switches antibody isotype from IgE to the noninflammatory type IgG4. Although allergen-specific immunotherapy is the only method of tolerance induction in allergic individuals, several factors, such as long duration of treatment, compliance problems, and life-threatening side effects, have limited widespread applicability of this immunomodulatory treatment. To overcome these limitations, current research focuses on the introduction of allergens in more efficient and safer ways. Defining the endotypes and phenotypes of allergic diseases might provide the ability to select ideal patients, and novel biomarkers might ensure new custom-tailored therapy modalities.

• Journal of Microbiology and Biotechnology
• /
• v.29 no.7
• /
• pp.1014-1021
• /
• 2019

In the bacterial community, unicellular organisms act together as a multicellular being. Bacteria interact within the community and programmed cell death (PCD) in prokaryotes is a sort of altruistic action that enables the whole population to thrive. Genetically, encoded cell death pathways are triggered by DNA damage or nutrient starvation. Given the environmental and bacterial diversity, different PCD mechanisms are operated. Still, their biochemical and physiological aspects remain unrevealed. There are three main pathways; thymineless death, apoptosis-like death, and toxin-antitoxin systems. The discovery of PCD in bacteria has revealed the possibility of developing new antibiotics. In this review, the molecular and physiological characteristics of the three types of PCD and their development potential as antibacterial agents are addressed.