Physical and tribological diagnostic of Ti-(Carbon Nitrides) and Ti-Nb-(Carbon Nitrides) coatings

J. C. Caicedo,W. Aperador,H. H. Caicedo 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.2

Electrochemical, mechanical and tribological properties of Ti-C-N and Ti-Nb-C-N coatings deposited onto Si (100) and AISI 4140steel substrates were determined in this work. Introduction of Nb in the ternary Ti C-N film was evaluated via Quantitative elementalconcentration depth profile by glow discharge optical emission spectroscopy (GDOES) and the morphology via scanning electron microscopy(SEM) were observed for the layers before the tests. The morphological surface was analyzed via AFM. Mechanical and tribologicalproperties for both coatings were obtained by mean of nanoindentation measurements throughload versus displacement method,and scratch test using the critical load criterion, respectively. The failure modes from scratch test were observed via optical microscopy. Nanoindentation results reaching the elastic-plastic behavior of the TiCN and Ti-Nb-C-N coatings with inclusion of Nb (TiNbCN), indicatednot only the hardness and elastic modulus but also the critical load for the adhesive failure increase when increasing r.f negativebias voltage. An improvement of hardness and critical load around 60% and 28% for TiCN as well as 26% and 31% for TiNbCN, respectively,was associated to an increasing in the r.f negative bias voltage from 0 V to -100 V.

Effects of Steroid Hormone in Avian Follicles

Caicedo Rivas, R.E.,Nieto, M. Paz-Calderon,Kamiyoshi, M. Asian Australasian Association of Animal Productio 2016 Animal Bioscience Vol.29 No.4

The aim of the present study was to examine the effects of testosterone (T) and estradiol-$17{\beta}$ ($E_2$) on the production of progesterone ($P_4$) by granulosa cells, and of the $E_2$ on the production of $P_4$ and T by theca internal cells. In the first experiment, granulosa cells isolated from the largest ($F_1$) and third largest ($F_3$) preovulatory follicle were incubated for 4 h in short-term culture system, $P_4$ production by granulosa cells of both $F_1$ and $F_3$ was increased in a dose-dependent manner by ovine luteinizing hormone (oLH), but not T or $E_2$. In the second experiment, $F_1$ and $F_3$ granulosa cells cultured for 48 h in the developed monolayer culture system were recultured for an additional 48 h with increasing doses of various physiological active substances existing in the ovary, including T and $E_2$. Basal $P_4$ production for 48 h during 48 to 96 h of the cultured was about nine fold greater by $F_1$ granulosa cells than by $F_3$ granulosa cells. In substances examined oLH, chicken vasoactive intestinal polypeptide (cVIP) and T, but not $E_2$, stimulated in a dose-dependent manner $P_4$ production in both $F_1$ and $F_3$ granulosa cells. In addition, when the time course of $P_4$ production by $F_1$ granulosa cells in response to oLH, cVIP, T and $E_2$ was examined for 48 h during 48 to 96 h of culture, although $E_2$ had no effect on $P_4$ production by granulosa cells of $F_1$ during the period from 48 to 96 h of culture, $P_4$ production with oLH was found to be increased at 4 h of the culture, with a maximal 9.14 fold level at 6 h. By contrast, $P_4$ production with cVIP and T increased significantly (p<0.05) from 8 and 12 h of the culture, respectively, with maximal 6.50 fold response at 12 h and 6, 48 fold responses at 36 h. Furthermore, when $F_1$ granulosa cells were precultured with $E_2$ for various times before 4 h culture with oLH at 96 h of culture, the increase in $P_4$ production in response to oLH with a dose-related manner was only found at a pretreatment time of more than 12 h. In the third experiment, theca internal cells of $F_1$, $F_2$ and the largest third to fifth preovulatory follicles ($F_{3-5}$) were incubated for 4 h in short-term culture system with increasing doses of $E_2$. The production of $P_4$ and T by theca internal cells were increased with the addition of $E_2$ of $10^{-6}M$. These increases were greater in smaller follicles. These results indicate that, in granulosa cells of the hen, T may have a direct stimulatory action in the long term on $P_4$ production, and on $E_2$ in long-term action which may enhance the sensitivity to LH for $P_4$ production, and thus, in theca internal cells, $E_2$ in short term action may stimulate the production of $P_4$ and T.

The Quingliu 清流 Seediq Indigenous Community Cultural Revitalization: Wushe Incident Dark-Eco Tourism Perspectives and Strategies

CAICEDO Diego Felipe 한국외국어대학교 대만연구센터 2023 대만연구 Vol.- No.23

The aim of this paper is to analyze the Quingliu Memorial Museum and the Wushe Incident sites as examples of dark tourism and difficult cultural heritage in Taiwan, while also exploring prospects on ecotourism. My objective was to first relate the memorial sites with dark tourism theoretical perspectives, to later analyze the site’s historical value for the local communities in identity reinforcement. Finally, on my findings I consider potential opportunities for the memorial and the community to develop strategies that are connected with ecological aims that are strongly attached in coherence with the locals. I suggest that by strengthening the interaction between the community and tourists within four interconnected themes (human impact-anthropo, ecology and biodiversity, Quingliu in conflict/peace, and indigenous cultures and identity.This approach could resurface the historical importance of the site into new arenas of sustainability, conservation, education, healing trauma, identity reinforcement and economic development. This research was articulated using a qualitative methodology that consisted on text-film analysis and ethnographic fieldwork conducted between 2020 and 2021. (168詞)

Role of Active and Inactive Cytotoxic Immune Response in Human Immunodeficiency Virus Dynamics

Hernan Dario Toro Zapata,Angelica Graciela Caicedo Casso,Derdei Bichara,이선미 질병관리본부 2014 Osong Public Health and Research Persptectives Vol.5 No.1

Objectives: Mathematical models can be helpful to understand the complex dynamics of human immunodeficiency virus infection within a host. Most of work has studied the interactions of host responses and virus in the presence of active cytotoxic immune cells, which decay to zero when there is no virus. However, recent research highlights that cytotoxic immune cells can be inactive but never be depleted. Methods: We propose a mathematical model to investigate the human immunodeficiency virus dynamics in the presence of both active and inactive cytotoxic immune cells within a host.We explore the impact of the immune responses on the dynamics of human immunodeficiency virus infection under different disease stages. Results: Standard mathematical and numerical analyses are presented for this new model. Specifically, the basic reproduction number is computed and local and global stability analyses are discussed. Conclusion: Our results can give helpful insights when designing more effective drug schedules in the presence of active and inactive immune responses.

A probabilistic approach for estimating water permeability in pressure-driven membranes

Boateng, Linkel K.,Madarshahian, Ramin,Yoon, Yeomin,Caicedo, Juan M.,Flora, Joseph R. V. Springer-Verlag 2016 JOURNAL OF MOLECULAR MODELING Vol.22 No.8

Young capillary vessels rejuvenate aged pancreatic islets

Almaca, Joana,Molina, Judith,Arrojo e Drigo, Rafael,Abdulreda, Midhat H.,Jeon, Won Bae,Berggren, Per-Olof,Caicedo, Alejandro,Nam, Hong Gil National Academy of Sciences 2014 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.111 No.49

<P><B>Significance</B></P><P>The regulation of blood glucose is a homeostatic process that declines with age, but it is unknown whether this disturbance is a consequence of intrinsic dysfunction of the regulatory organ, the pancreatic islet. In marked contrast to the widely held notion that the insulin-producing pancreatic beta cell loses function with wear and tear, and thus causes age-related disturbances in glucose homeostasis, we show that mouse and human beta cells are fully functional at advanced age. The pancreatic islet as an organ, however, is threatened by vascular senescence. Replacing the islet vasculature in aged islet grafts rejuvenates the islet and fully restores glucose homeostasis, indicating that islet blood vessels should be targeted to mitigate frail glucose homeostasis associated with aging.</P><P>Pancreatic islets secrete hormones that play a key role in regulating blood glucose levels (glycemia). Age-dependent impairment of islet function and concomitant dysregulation of glycemia are major health threats in aged populations. However, the major causes of the age-dependent decline of islet function are still disputed. Here we demonstrate that aging of pancreatic islets in mice and humans is notably associated with inflammation and fibrosis of islet blood vessels but does not affect glucose sensing and the insulin secretory capacity of islet beta cells. Accordingly, when transplanted into the anterior chamber of the eye of young mice with diabetes, islets from old mice are revascularized with healthy blood vessels, show strong islet cell proliferation, and fully restore control of glycemia. Our results indicate that beta cell function does not decline with age and suggest that islet function is threatened by an age-dependent impairment of islet vascular function. Strategies to mitigate age-dependent dysregulation in glycemia should therefore target systemic and/or local inflammation and fibrosis of the aged islet vasculature.</P>

Real-time detection of acetylcholine release from the human endocrine pancreas

Rodriguez-Diaz, Rayner,Dando, Robin,Huang, Y Anthony,Berggren, Per-Olof,Roper, Stephen D,Caicedo, Alejandro Nature Publishing Group, a division of Macmillan P 2012 Nature protocols Vol.7 No.6

Neurons, sensory cells and endocrine cells secrete neurotransmitters and hormones to communicate with other cells and to coordinate organ and system function. Validation that a substance is used as an extracellular signaling molecule by a given cell requires a direct demonstration of its secretion. In this protocol we describe the use of biosensor cells to detect neurotransmitter release from endocrine cells in real-time. Chinese hamster ovary cells expressing the muscarinic acetylcholine (ACh) receptor M3 were used as ACh biosensors to record ACh release from human pancreatic islets. We show how ACh biosensors loaded with the Ca<SUP>2+</SUP> indicator Fura-2 and pressed against isolated human pancreatic islets allow the detection of ACh release. The biosensor approach is simple; the Ca<SUP>2+</SUP> signal generated in the biosensor cell reflects the presence (release) of a neurotransmitter. The technique is versatile because biosensor cells expressing a variety of receptors can be used in many applications. The protocol takes ?? h.

Innervation Patterns of Autonomic Axons in the Human Endocrine Pancreas

Rodriguez-Diaz, Rayner,Abdulreda, Midhat ,H.,Formoso, Alexander ,L.,Gans, Itai,Ricordi, Camillo,Berggren, Per-Olof,Caicedo, Alejandro Elsevier 2011 Cell metabolism Vol.14 No.1

<P><B>Summary</B></P><P>The autonomic nervous system regulates hormone secretion from the endocrine pancreas, the islets of Langerhans, thus impacting glucose metabolism. The parasympathetic and sympathetic nerves innervate the pancreatic islet, but the precise innervation patterns are unknown, particularly in human. Here we demonstrate that the innervation of human islets is different from that of mouse islets and does not conform to existing models of autonomic control of islet function. By visualizing axons in three dimensions and quantifying axonal densities and contacts within pancreatic islets, we found that, unlike mouse endocrine cells, human endocrine cells are sparsely contacted by autonomic axons. Few parasympathetic cholinergic axons penetrate the human islet, and the invading sympathetic fibers preferentially innervate smooth muscle cells of blood vessels located within the islet. Thus, rather than modulating endocrine cell function directly, sympathetic nerves may regulate hormone secretion in human islets by controlling local blood flow or by acting on islet regions located downstream.</P> <P><B>Highlights</B></P><P>► Detailed quantitative analysis of the innervation of mouse and human islets ► Human endocrine cells are sparsely innervated ► Sympathetic axons innervate vascular smooth muscle cells deep inside human islets ► Autonomic control of human islets may use unique mechanisms</P>

Spatial and temporal coordination of insulin granule exocytosis in intact human pancreatic islets

Almaç,a, J.,Liang, T.,Gaisano, H. Y.,Nam, H. G.,Berggren, P. O.,Caicedo, A. Springer Science + Business Media 2015 Diabetologia Vol.58 No.12

Measurement of Ratios of νμ Charged-Current Cross Sections on C, Fe, and Pb to CH at Neutrino Energies 2-20 GeV

Tice, B. G.,Datta, M.,Mousseau, J.,Aliaga, L.,Altinok, O.,Barrios Sazo, M. G.,Betancourt, M.,Bodek, A.,Bravar, A.,Brooks, W. K.,Budd, H.,Bustamante, M. J.,Butkevich, A.,Martinez Caicedo, D. A.,Castrom American Physical Society 2014 Physical Review Letters Vol.112 No.23