극초단 레이저로 개질된 사파이어의 선택적 식각

M. Kaiser,M. Kumkar,R Leute,J. Schmauch,R. Priester,J. Kleiner,M. Jenne,D. Flamm,F. Zimmermann 한국레이저가공학회 2021 Laser Solutions Vol.24 No.9

단단하고 긁힘에 강한 사파이어는 가전제품 등의 다양한 고품질 응용 분야에서 선호하는 재료이다. 이러한 우수한 특성 때문에 사파이어는 가공에 있어 까다로운 재료이다. 성형된 빔과 초단파 펄스를 사용하면 에너지를 정확하게 재료에 축적하고 개질하여 열 유도 응력을 줄이고 미세 균열을 방지할 수 있다. 특히 내부 윤곽에 대해 개질된 경로를 따라 분리하는 것은 여전히 해결되지 않은 과제이다. 레이저에 의해 개질된 사파이어의 선택적 식각은 외부 윤곽은 물론 내부 윤곽, 심지어 가장 작은 관통 구멍까지 방출할 수 있는 유망한 기술이다. 베셀 형 빔 프로파일을 사용하여 전체 두께의 단결정 비정질화된 긴 개질을 단일 펄스로 달성할 수 있다. 단결정 사파이어와 달리 비정질 상에서는 30 wt% KOH 용액에서 에칭할 수 있다. 성공적인 공정 개발을 위해 1030 nm 파장에서 펄스폭, 펄스 에너지, 펄스 수, 빔의 시공간적 거리에 따른 다양한 유형의 개질 및 에칭 양상을 기본적으로 비교한다. 에칭 속도는 가공 및 에칭 조건에 따라 달라지며 10 µm/min으로 최적화된다. 윤곽 외에도 2차원으로 배열된 균열 없는 나노 구멍(직경 200 nm, 거리 5 µm)으로 구성된 나노 분리막은 1:1500의 가로세로 비율로 구현된다.

극초단 레이저로 개질된 사파이어의 선택적 에칭

M,Kaiser,M,Kumkar 한국레이저가공학회 2020 Laser Solutions Vol.23 No.3

Influence of V2O5 ion addition on the conductivity and grain growth of Ni-Zn-Cu ferrites

M. Kaiser 한국물리학회 2010 Current Applied Physics Vol.10 No.4

Polycrystalline nickel–zinc–copper ferrites with chemical formula Ni0.6+xZn0.2Cu0.2VxFe2-2xO4,(0.0 ≤ x ≤0.25) were prepared by the ceramic route. The X-ray diffraction (XRD) analysis of the samples results confirms single-phase spinel structure. Scanning electron microscopy (SEM) of the prepared ferrites reveal that vanadium addition resulted in a rapid grain growth with large pores trapped inside the grains as the vanadium concentration increases. The ac conductivity σac has been studied as a function of frequency and temperature over the temperature range (300–600 K). The results obtained for these materials reveal a semiconductor – to semimetal transition as V5+ content increases. All studies composition exhibit a transition with change in the slope of conductivity. The obtained temperature Tc is found to be decrease with the increasing vanadium content. The hopping of electrons between Fe3+and Fe2+ as well as the hole hopping between Ni3+ and Ni2+ are found to responsible for the conduction mechanism. The relation of the universal exponent s with temperature gives evidence for the presence of the correlation barrier hopping (CHB) mechanism in these compounds. The impedance technique has been used to study effect of grain and grain boundary on the electrical properties. The analysis data show only one semi-circle for all samples except for sample with x = 0.05. The results suggested that the conduction mechanism takes place predominantly through the grain in the studied samples.

A Luminous Transient Event in a Sample of <i>WISE</i>-selected Variable AGNs

Assef, R. J.,Prieto, J. L.,Stern, D.,Cutri, R. M.,Eisenhardt, P. R. M.,Graham, M. J.,Jun, H. D.,Rest, A.,Flewelling, H. A.,Kaiser, N.,Kudritzki, R.-P.,Waters, C. American Astronomical Society 2018 The Astrophysical journal Vol.866 No.1

Anti-Allergic Effects of Herbal Product from Allium cepa (Bulb)

Kaiser, P.,Youssouf, M.S.,Tasduq, S.A.,Singh, S.,Sharma, S.C.,Singh, G.D.,Gupta, V.K.,Gupta, B.D.,Johri, R.K. The Korean Society of Food Science and Nutrition 2009 Journal of medicinal food Vol.12 No.2

Allium cepa (Family Liliaceae) is a reputed Indian medicinal herb that is prescribed as an effective remedy for several ailments in the Ayurvedic system of medicine. The aim of this study was to evaluate its efficacy against various events responsible for Type I allergic reactions. A herbal fraction (ALC-02) from A. cepa (bulb) inhibited histamine release and attenuated intracellular calcium levels in Compound 48/80-induced rat peritoneal mast cells. It also prevented Compound 48/80-mediated systemic anaphylaxis while lowering histamine levels in plasma. ALC-02 suppressed carrageenan-induced rat paw edema. It inhibited eosinophil peroxidase activity and protein content in broncho alveolar lavage fluid (BALF) of ovalbumin-challenged mice. In this experiment ALC-02 also caused a substantial reduction in lipid peroxidation in BALF/lung tissue and augmented superoxide dismutase activity in lung tissue. ALC-02 suppressed erythrocytic lysis caused by Triton X-100. A significant quenching of 1,1-diphenyl-2-picrylhydrazyl radical by ALC-02 was observed. The results have shown a promising anti-allergic profile of ALC-02 that could be attributed to its potential antihistaminic, anti-inflammatory, and antioxidant activities.

Anti-Allergic Effects of Herbal Product from Allium cepa (Bulb)

P. Kaiser,M.S. Youssouf,S.A. Tasduq,S. Singh,S.C. Sharma,G.D. Singh,V.K. Gupta,B.D. Gupta,R.K. Johri 한국식품영양과학회 2009 Journal of medicinal food Vol.12 No.2

Allium cepa (Family Liliaceae) is a reputed Indian medicinal herb that is prescribed as an effective remedy for several ailments in the Ayurvedic system of medicine. The aim of this study was to evaluate its efficacy against various events responsible for Type I allergic reactions. A herbal fraction (ALC-02) from A. cepa (bulb) inhibited histamine release and attenuated intracellular calcium levels in Compound 48/80-induced rat peritoneal mast cells. It also prevented Compound 48/80-mediated systemic anaphylaxis while lowering histamine levels in plasma. ALC-02 suppressed carrageenan-induced rat paw edema. It inhibited eosinophil peroxidase activity and protein content in bronchoalveolar lavage fluid (BALF) of ovalbumin-challenged mice. In this experiment ALC-02 also caused a substantial reduction in lipid peroxidation in BALF/lung tissue and augmented superoxide dismutase activity in lung tissue. ALC-02 suppressed erythrocytic lysis caused by Triton X-100. A significant quenching of 1,1-diphenyl-2-picrylhydrazyl radical by ALC-02 was observed. The results have shown a promising anti-allergic profile of ALC-02 that could be attributed to its potential antihistaminic, anti-inflammatory, and antioxidant activities.

Magnetic Barkhausen noise analysis of stress in steel

D. M. Stewart,K. J. Stevens,A. B. Kaiser 한국물리학회 2004 Current Applied Physics Vol.4 No.2-4

When a changing magnetic eld is applied to a magnetic material, the domain walls move so domains aligned close to the elddirection grow at the expense of those that are less aligned. The movement occurs in a series of sudden jumps leading to magnetic Barkhausen noise (MBN). Analysis of MBN can provide an eective non-destructive testing technique for determining residual stress in steel. MBN measurements on AS1548-7-460R steel under applied stress show a clear asymmetry between compression andtension. MBN features show more sensitivity to compression and undergo a Villari reversal in their stress dependence at about 100MPa of tension. Measurements are also made on a welded plate of the same material. Away from the weld the results are consistentwith the expected compressive stress parallel to the weld direction. At a point near one edge of the weld, the amount and character ofthe MBN changed sharply, suggesting a concentration of stress.

Variation with temperature of the I-V characteristics of polyacetylene nanofibres

A.B.Kaiser,T.M.Iorns,J.G.Park,B.Kim,S.H.Lee,Y.W.Park 한국물리학회 2002 Current Applied Physics Vol.2 No.4

The currentvoltage (IV) characteristics of individual nanobres of doped polyacetylene show a dramatic change from verystrong nonlinearities for lightly-doped samples at low temperatures, to nearly ohmic behaviour for higher temperatures and dopinglevels. At low temperatures (below 1030 K), theIV characteristics are independent of temperature and follow the expression forZener-type tunnelling, as predicted for eld-induced tunnelling of the conjugated bond system. At higher temperatures, theIVmechanisms become important. TheIV characteristics for the most conductive sample are consistent with our calculations ofuctuation-induced tunnelling.. 2002 Elsevier Science B.V. All rights reserved.

Genetic Variation in MicroRNAs and Risk of Oral Squamous Cell Carcinoma in South Indian Population

Sushma, PS,Jamil, Kaiser,Kumar, P Uday,Satyanarayana, U,Ramakrishna, M,Triveni, B Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.17

Background: MicroRNAs (miRNAs) are small non-coding RNA molecules, implicated in several activities like initiation, progression and prognosis of various cancers. Single nucleotide polymorphisms (SNPs) in miRNA genes can lead to alteration in mRNA expression, resulting in diverse functional consequences. The aim of our study was to investigate the association of miR-149C>T and miR-196a2C>T SNPs with susceptibility to development of oral squamous cell carcinoma (OSCC) in South Indian subjects. Materials and Methods: 100 OSCC patients and 102 healthy controls from the general population were recruited for the study. Genetic analysis was performed by polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) as per a standard protocol. Results: The genotype frequencies in miR-196a2 polymorphism, of TT, CT and CC in the OSCC patients were 69%,10% and 22% respectively while for control group it was 80%, 15% and 5% respectively. The CC genotype of miR196a2 polymorphism was significantly associated with oral squamous cell carcinoma. The genotype frequencies in miR-149 polymorphisms of CC, CT and TT in the oral squamous cell carcinoma (OSCC) patients were 72%, 22% and 6% respectively and for control group 88%, 12% and 0% respectively. CT and TT genotypes of miR149 polymorphism were found to be significantly associated with OSCC (p = 0.05 and 0.07). Conclusions: Our study suggests that miR-196a2C>T and miR-149C>T polymorphisms may play crucial roles in the development of OSCC in South Indian subjects.

Beyond the average: Detecting global singular nodes from local features in complex networks

Costa, L. da F.,Rodrigues, F. A.,Hilgetag, C. C.,Kaiser, M. Editions de Physique 2009 Europhysics letters Vol.87 No.1

<P>Deviations from the average can provide valuable insights about the organization of natural systems. The present article extends this important principle to the systematic identification and analysis of singular motifs in complex networks. Six measurements quantifying different and complementary features of the connectivity around each node of a network were calculated, and multivariate statistical methods applied to identify singular nodes. The potential of the presented concepts and methodology was illustrated with respect to different types of complex real-world networks, namely the US air transportation network, the protein-protein interactions of the yeast <I>Saccharomyces cerevisiae</I> and the Roget thesaurus networks. The obtained singular motifs possessed unique functional roles in the networks. Three classic theoretical network models were also investigated, with the Barabási-Albert model resulting in singular motifs corresponding to hubs, confirming the potential of the approach. Interestingly, the number of different types of singular node motifs as well as the number of their instances were found to be considerably higher in the real-world networks than in any of the benchmark networks.</P>