TTCP-DCPA-β-TCP-PHA계 골 시멘트

김형준,최성철,석준원,Rainer Telle 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.1

본 연구에서는 Tetracalcium Phosphate(TTCP), Dicalcium Phosphate Anhydrate(DCPA)계 골 시멘트에 $\beta$-tricalcium Phosphate (TCP)와 Precipitated Hydroxy Apatite(PHA)를 첨가하였을 때, 골시멘트의 초기 응결시간과 강도에 미치는 영향 및 in vitro test후의 표면 미세구조의 변화를 관찰하고자 하였다. 골 시멘트에 사용된 TTCP와 $\beta$-TCP는 약 3-5$mu extrm{m}$으로 합성후 분쇄하였으며, DCPA는 0.9$\mu\textrm{m}$, 그리고 PHA는 4$\mu\textrm{m}$의 평균 입경을 가졌다. 각각의 조성으로 배합된 시멘트는 Vicat건에 의한 초기응결시간 측정과 압축강도 시험을 행하였고, 의사체액내에 침적 후 침전 생성물을 x-선 회절 분석과 주사전자현미경을 이용하여 분석, 관찰 하였다. 초기 응결시간은 $\beta$-TCP나 PHA의 존재 유무와 함량의 증가에 따라 크게 좌우되지 않았으나, 분말 : 액상의 비에 영향을 받았으며, 특히 PHA가 함유되는 경우 PHA의 비표면적으로 인하여 응결에 요구되는 액상의 양은 PHA가 없는 경우에 비하여 2배 이상 되었다. $\beta$-TCP PHA의 첨가로 인해 압축강도는 낮아졌고, 이는 수화 생성물인 HAP의 생성 정도가 낮았기 때문이었다. 이는 x-선 회절 분석과 주사전자 현미경 관찰을 통하여 확인할 수 있었다. 본 연구로부터 TTCP-DCPA계 골 시멘트에 $\beta$-TCP나 PHA의 첨가는 기계적 물성과 생체 반응성 향상에 효과적이지 못하다는 것을 확인 할 수 있었다. The effect of $\beta$-TCP and PHA as additives on initial setting time, compressive strength and surface micro-structure after in vitro test of bone cement in TTCP and DCPA system was investigated. The median particle sizes of TTCP, $\beta$-TCP, DCPA and PHA for bone cement were about 3, 5, 0.9 and 4${\mu}{\textrm}{m}$, respectively. Initial setting time and compressive strength of bone cement with various composition was measured by Vicat test and Universal Testing Machine, and surface morphology and crystalline phases of bone cements were observed and analyzed by SEM and x-ray diffractometer. Initial setting time was not affected by composition but by powder/liquid ratio, and cement with PHA required double amount of solution for paste as much as one without PHA, especially. It was thought that $\beta$-TCP and PHA in bone cements was not related to setting reaction. Thus, the addition of $\beta$-TCP and PHA in bone cements decreased compressive strength and inhabited HAP from being produced on surface in vitro test. In conclusion, it was not expected that $\beta$-TCP and PHA in TTCP-DCPD bone cements enhanced the strength and bioacitivity.

The Growth of One-Dimensional Single-Crystalline AlN Nanostructures by HVPE and Their Field Emission Properties

Byeun, Yun-Ki,Telle, Rainer,Jung, Se-Hyuk,Choi, Sung-Churl,Hwang, Hak-In WILEY-VCH Verlag 2010 CHEMICAL VAPOR DEPOSITION -WEINHEIM- Vol.16 No.1

<P>Single-crystalline AlN nanostructures, such as thin films, nanoneedles, nanocolumns, and nanowires, depending on the controlled gas-flow ratio, are synthesized by halide vapor-phase epitaxy (HVPE). In comparison with a typical vapor/liquid/solid (VLS) mechanism for the growth of nanowires, well-aligned AlN nanorod arrays with diameters below 20 nm are grown on a catalyst-free Si substrate though a vapor/solid (VS) mechanism. Their structural and optical properties are measured by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL). In particular, AlN nanorods exhibit an excellent field emission property with a low turn-on field of 2.25 V µm<SUP>−1</SUP>. The field enhancement factor is estimated to be about 784 due to well-aligned, needle-shaped, AlN nanorods.</P> <B>Graphic Abstract</B> <P>Halide vapor-phase epitaxy system to grow 1-dimensional single crystalline AlN nanostructures has been developed in this work. The needle shaped AlN nanorod array exhibit on excellent field emission property with a low turn-on field of 2.25 V/µm. This technique may provide great advances in optoelectronics and field emission nanodevices.</P>

Maximum matching width: New characterizations and a fast algorithm for dominating set

Jeong, Jisu,Sæther, Sigve Hortemo,Telle, Jan Arne Elsevier 2018 Discrete applied mathematics Vol.248 No.-

<P><B>Abstract</B></P> <P>A graph of treewidth k has a representation by subtrees of a ternary tree, with subtrees of adjacent vertices sharing a tree node, and any tree node sharing at most k + 1 subtrees. Likewise for branchwidth, but with a shift to the edges of the tree rather than the nodes. In this paper we show that the mm-width of a graph – maximum matching width – combines aspects of both these representations, targeting tree nodes for adjacency and tree edges for the parameter value. The proof of this new characterization of mm-width is based on a definition of canonical minimum vertex covers of bipartite graphs. We show that these behave in a monotone way along branch decompositions over the vertex set of a graph.</P> <P>We use these representations to compare mm-width with treewidth and branchwidth, and also to give another new characterization of mm-width, by subgraphs of chordal graphs. We prove that given a graph G and a branch decomposition of maximum matching width k we can solve the Minimum Dominating Set Problem in time <SUP> O ∗ </SUP> ( <SUP> 8 k </SUP> ) , thereby beating <SUP> O ∗ </SUP> ( <SUP> 3 tw ( G ) </SUP> ) whenever tw ( G ) > <SUB> log 3 </SUB> 8 × k ≈ 1 . 893 k . Note that mmw ( G ) ≤ tw ( G ) + 1 ≤ 3 mmw ( G ) and these inequalities are tight. Given only the graph G and using the best known algorithms to find decompositions, maximum matching width will be better for Minimum Dominating Set whenever tw ( G ) > 1 . 549 × mmw ( G ) .</P>

A width parameter useful for chordal and co-comparability graphs

Kang, Dong Yeap,Kwon, O-joung,Strømme, Torstein J.F.,Telle, Jan Arne Elsevier 2017 Theoretical computer science Vol.704 No.-

<P><B>Abstract</B></P> <P>Belmonte and Vatshelle (TCS 2013) used mim-width, a graph width parameter bounded on interval graphs and permutation graphs, to explain existing algorithms for many domination-type problems on those graph classes. We investigate new graph classes of bounded mim-width, strictly extending interval graphs and permutation graphs. The graphs <SUB> K t </SUB> ⊟ <SUB> K t </SUB> and <SUB> K t </SUB> ⊟ <SUB> S t </SUB> are graphs obtained from the disjoint union of two cliques of size <I>t</I>, and one clique of size <I>t</I> and one independent set of size <I>t</I> respectively, by adding a perfect matching. We prove that:<UL> <LI> interval graphs are ( <SUB> K 3 </SUB> ⊟ <SUB> S 3 </SUB> ) -free chordal graphs; and ( <SUB> K t </SUB> ⊟ <SUB> S t </SUB> ) -free chordal graphs have mim-width at most t − 1 , </LI> <LI> permutation graphs are ( <SUB> K 3 </SUB> ⊟ <SUB> K 3 </SUB> ) -free co-comparability graphs; and ( <SUB> K t </SUB> ⊟ <SUB> K t </SUB> ) -free co-comparability graphs have mim-width at most t − 1 , </LI> <LI> chordal graphs and co-comparability graphs have unbounded mim-width in general. </LI> </UL> We obtain several algorithmic consequences; for instance, while <SMALL>MINIMUM DOMINATING SET</SMALL> is NP-complete on chordal graphs, it can be solved in time <SUP> n O ( t ) </SUP> on ( <SUB> K t </SUB> ⊟ <SUB> S t </SUB> ) -free chordal graphs. The third statement strengthens a result of Belmonte and Vatshelle stating that either those classes do not have constant mim-width or a decomposition with constant mim-width cannot be computed in polynomial time unless P = N P .</P> <P>We generalize these ideas to bigger graph classes. We introduce a new width parameter <I>sim-width</I>, of stronger modeling power than mim-width, by making a small change in the definition of mim-width. We prove that chordal graphs and co-comparability graphs have sim-width at most 1. We investigate a way to bound mim-width for graphs of bounded sim-width by excluding <SUB> K t </SUB> ⊟ <SUB> K t </SUB> and <SUB> K t </SUB> ⊟ <SUB> S t </SUB> as induced minors or induced subgraphs, and give algorithmic consequences. Lastly, we show that circle graphs have unbounded sim-width, and thus also unbounded mim-width.</P>

Risk Factors for Mortality in Hospitalized Patients with COVID-19: An Overview in a Mexican Population

( Arturo Cortés-tellés ),( Stephanie López-romero ),( Roberto Mancilla-ceballos ),( Diana Lizbeth Ortíz-farías ),( Nelda Núñez-caamal ),( Esperanza Figueroa-hurtado ) 대한결핵 및 호흡기학회 2020 Tuberculosis and Respiratory Diseases Vol.83 No.-

Background: Currently, Mexico ranks third worldwide in mortality due to coronavirus disease pandemic 2019 (COVID-19) and reliable information is scarce, with the available data focused on epidemiological characteristics. This study aimed to identify the risk factors associated with mortality and outcomes in hospitalized Mexican patients with COVID-19. Methods: We prospectively assessed patients admitted to a COVID-19 reference center in southeast Mexico between March 28 and June 30, 2020. Mortality was defined as survivors or non-survivors and univariate and multivariate logistic regression analyses were performed to explore the association of the clinical characteristics and laboratory parameters with mortality. Results: We included 200 patients with a mean age of 55 years, 69% were men and 72% had at least one chronic comorbidity. Eighty-six patients required invasive mechanical ventilation (IMV) with an overall mortality rate of 82.5%. Only 51% of the patients with IMV were admitted to the intensive care unit (ICU), with a survival rate of 27.3%, but only 7.2% for patients without ICU admissions (p=0.014). The multivariate analysis found that a neutrophil-to-lymphocyte ratio ≥9 (odds ratio [OR], 4.64; 95% confidence interval [CI], 2.05-10.53) albumin <3.5 g/dL (OR, 3.76; 95% CI, 1.56-9.07), lactate dehydrogenase (LDH) level ≥725 U/L (OR, 5.45; 95% CI, 2.36-12.57), and IMV (OR, 64.7; 95% CI, 15.20-275.39) were independent risk factors associated with mortality. Conclusion: Neutrophil-to-lymphocyte ratio, LDH, albumin, and IMV were independent risk factors for mortality in Mexican patients with COVID-19. Also, the availability of ICU resources is invaluable for better outcomes in critically ill patients. Our results could provide clinical information for timely decision-making in low-and-middle income countries to overcome the pandemic.

Self-rated ability to follow instructions for four mental states described in yoga texts

Raghavendra Bhat Ramachandra,Shirley Telles,Nagendra Rama Rao Hongasandra 셀메드 세포교정의약학회 2012 TANG Vol.2 No.3

There were no studies available measuring the ability to follow instructions for meditation. Hence, the present study was planned to assess the ability to follow instructions for the four mental states viz., cancalata (random thinking), ekagrata (non-meditative concentration), dharana (focused meditation) and dhyana (defocused meditation or effortless meditation) described in yoga texts. Sixty male volunteers with ages ranging from 18 to 31 years (group mean age ± S.D., 22.78 ± 2.73) participated in the study. They were assessed using a visual analog scale immediately after each of the four states on four different days. The results showed that following dharana, scores on the visual analog scale were significantly lower compared to those related to cancalata, ekagrata and dhyana. Hence, dharana is the most difficult of the four states.

An Algorithm to Obtain Boat Engine RPM from Passive Sonar Signals Based on DEMON Processing and Wavelets Packets Transform

Guillermo Kemper,David Ponce,Joel Telles,Christian del Carpio 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

The detection of the engine rotational speed in revolutions per minute (RPM) is of great importance to estimate the speed of boats. This value can be obtained from the fundamental frequency component of acquired sonar signals. However, detection can often be seriously afected by noise and distortion introduced by the underwater environment. Several methods have been proposed for fundamental component detection, but they do not specifcally take advantage of the passive sonar signal characteristics to improve the performance of the process. In this context, the proposed algorithm uses DEMON processing applied to wavelets packets subbands to exploit the characterization of the sonar signal in the time and frequency domains. The algorithm involves signal segmentation, wavelet packet decomposition, subband envelope cross-correlation and fundamental component detection from the power spectrum. The method was applied in passive sonar signals acquired in navigation and also obtained by simulation. The performance of the proposed algorithm was evaluated with signals of diferent SNR values that were also corrupted by a simulated multipath underwater channel. The signals were evaluated by both the experienced sonar operators and the proposed algorithm. The results obtained were very satisfactory for RPM detection and are detailed at the end of this document.

Effect of poly-L-arginine in inhibiting scrapie prion protein of cultured cells

Waqas, M.,Lee, H. M.,Kim, J.,Telling, G.,Kim, J. K.,Kim, D. H.,Ryou, C. Springer Science + Business Media 2017 MOLECULAR AND CELLULAR BIOCHEMISTRY - Vol.428 No.1

<P>Biological effect of poly-L-arginine (PLR), the linear homopolymer comprised of L-arginine, was investigated to determine the activity of suppressing prions. PLR decreased the level of scrapie prion protein (PrPSc) in cultured cells permanently infected with prions in a concentration-dependent manner. The PrPSc inhibition efficacy of PLR was greater than that of another prion-suppressant poly-L-lysine (PLK) in a molecular mass-dependent fashion. The effective concentration of PLR to inhibit prions was achieved safely below the cytotoxic concentrations, and overall cytotoxicity of PLR was similar to that of PLK. PLR did not alter the cellular prion protein -(PrPC) level and was unable to change the states of preformed recombinant PrP aggregates and PrPSc from prion-infected cells. These data eliminate the possibility that the action mechanism of PLR is through removal of PrPC and pre-existing PrPSc. However, PLR formed complexes with plasminogen that stimulates prion propagation via conversion of PrPC to the misfolded isoform, PrPSc. The plasminogen-PLR complex demonstrated the greater positive surface charge values than the similar complex with PLK, raising the possibility that PLR interferes with the role of cofactor for PrPSc generation better than PLK.</P>

THE OCCURRENCE AND GEOLOGICAL SETTING OF CRETACEOUS DINOSAURS, MOSASAURS, PLESIOSAURS, AND TURTLES FROM ANGOLA

Louis L. Jacobs,Octavio Mateus,Michael J. Polcyn,Anne S. Schulp,Miguel Telles Antunes,Maria Luisa Morais,Tatiana da Silva Tavares 한국고생물학회 2006 고생물학회지 Vol.22 No.1

아프리카 사하라 지역에 척추동물화석을 배태한 백악기 지층의 노출은 매우 적다. 왜냐하면 대륙의 상당 부분을 선캄브리아기 변성암 육괴가 넓게 분포하고 있을 뿐 아니라 젊은 시대의 지층들과 식물들이 이들 백악기 지층을 덮고 있기 때문이다. 그러나 백악기 해성층과 육성층이 넓게 발달한 지역이 앙골라 해안과 내륙 사이에서 발견되었다. 앙골라의 주변부는 곤드와나 대륙이 갈라지면서 남대서양이 확장되는 것과 관련되어 형성되었다. 백악기 퇴적층은 해양지각의 덮고 있어 시대는 매우 제한적이며 가장 오래된 지층은 지자기대 (magnetozone) M3 (대략 128Ma, Barremian) 보다 오래되지 않았다. 얕은 해양퇴적 환경은 해안가에 드러나 있지만 내륙으로 점점 육성퇴적 환경이 증가한다. 상어화석이외에는 앙골라에서 척추화석이 거의 발견되지 않았었다. 예외적인 화석은 앙골라 북부에서 산출된 후기 Turonian 모사사우루스 Angolasaurus bacagei와 Tylosaurus iembeensis이다. 이들 화석은 가장 초창기에 진화된 모사사우루스들이기 때문에 중요하다. 최근 야외조사를 통해 새로운 Angolasaurus의 머리뼈뿐만 아니라 상어, 물고기, 수장룡, 새로운 거북의 머리뼈, 앙골라에서는 처음 발견되는 용각류의 앞다리가 발견되었다. 앙골라 남부에는 백악기에서 팔레오세 경계까지 퇴적된 해양퇴적층이 발견된다. Vertebrate-bearing fossiliferous outcrops of Cretaceous age in sub-Saharan Africa are rare because of younger superficial deposits, vegetation cover, and the widespread occurrence of Precambrian metamorphic plateau basement comprising much of the continent. However, one area of extensive marine and nonmarine Cretaceous exposures is found between the plateau and the coast in Angola. The Angolan margin was formed in conjunction with the breakup of Gondwana and subsequent growth of the South Atlantic. Cretaceous deposits are constrained in age by the emplacement of oceanic crust, which began no later than magnetozone M3 (approximately 128 Ma, Barremian). Shallow marine facies are exposed in sea cliffs but equivalent facies become increasingly terrestrial inland. Few vertebrate fossils have been described from Angola aside from sharks. Notable exceptions are the late Turonian mosasaurs Angolasaurus bocagei and Tylosaurus iembeensis from northern Angola. Those taxa are significant because they are among the earliest derived mosasaurs. Recent field work led to the discovery of a new skull of Angolasaursus as well as sharks, fish, plesiosaurs, the skull of a new taxon of turtle, additional mosasaurs, and the articulated forelimb of a sauropod dinosaur, the first reported dinosaur from Angola. In southern Angola, marine sediments spanning the Cretaceous-Paleogene boundary are found.

Elastodynamic analysis by a frequency-domain FEM-BEM iterative coupling procedure

Soares, Delfim Jr.,Goncalves, Kleber A.,de Faria Telles, Jose Claudio Techno-Press 2015 Coupled systems mechanics Vol.4 No.3

This paper presents a coupled FEM-BEM strategy for the numerical analysis of elastodynamic problems where infinite-domain models and complex heterogeneous media are involved, rendering a configuration in which neither the Finite Element Method (FEM) nor the Boundary Element Method (BEM) is most appropriate for the numerical analysis. In this case, the coupling of these methodologies is recommended, allowing exploring their respective advantages. Here, frequency domain analyses are focused and an iterative FEM-BEM coupling technique is considered. In this iterative coupling, each sub-domain of the model is solved separately, and the variables at the common interfaces are iteratively updated, until convergence is achieved. A relaxation parameter is introduced into the coupling algorithm and an expression for its optimal value is deduced. The iterative FEM-BEM coupling technique allows independent discretizations to be efficiently employed for both finite and boundary element methods, without any requirement of matching nodes at the common interfaces. In addition, it leads to smaller and better-conditioned systems of equations (different solvers, suitable for each sub-domain, may be employed), which do not need to be treated (inverted, triangularized etc.) at each iterative step, providing an accurate and efficient methodology.