Antimicrobial Activity of Northwestern Mexican Plants Against Helicobacter pylori

Ramón E. Robles-Zepeda,Carlos A. Velázquez-Contreras,Adriana Garibay-Escobar,Juan C. Gálvez-Ruiz,Eduardo Ruiz-Bustos 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.10

Helicobacter pylori is the major etiologic agent of such gastric disorders as chronic active gastritis and gastric carcinoma. Over the past few years, the appearance of antibiotic-resistant bacteria has led to the development of better treatments, such as the use of natural products. This study evaluated the anti–H. pylori activity of 17 Mexican plants used mainly in the northwestern part of Mexico (Sonora) for the empirical treatment of gastrointestinal disorders. The anti–H. pylori activity of methanolic extracts of the plants was determined by using the broth microdilution method. The 50% minimum inhibitory concentrations ranged from less than 200 to 400 μg/mL for Castella tortuosa, Amphipterygium adstringens, Ibervillea sonorae, Pscalium decompositum, Krameria erecta, Selaginella lepidophylla, Pimpinella anisum, Marrubium vulgare, Ambrosia confertiflora, and Couterea latiflora and were greater than 800 μg/mL for Byophyllum pinnatum, Tecoma stans linnaeus, Kohleria deppena, Jatropha cuneata, Chenopodium ambrosoides, and Taxodium macronatum. Only Equisetum gigantum showed no activity against H. pylori. This study suggests the important role that these plants may have in the treatment of gastrointestinal disorders caused by H. pylori. The findings set the groundwork for further characterization and elucidation of the active compounds responsible for such activity.

Copper nanoparticles supported on biocarbon film from Sargassum spp. and its electrochemical activity in reducing CO2

Velueta D. A. Pantoja,Ramírez S. J. Figueroa,Sierra J. M.,Escobar B.,Ucán C. A. Aguilar,Rosas G. 한국탄소학회 2022 Carbon Letters Vol.32 No.6

The biocarbon (SKPH) was obtained from Sargassum spp., and it was evaluated electrochemically as support for the CO2 reduction. The biocarbon was synthesized and activated with KOH, obtaining a high surface area (1600 m2 g−1) due to the activation process. Graphitic carbon formation after pyrolysis was confirmed by Raman spectroscopy. The XRD results show that SKPH has an amorphous structure with peaks corresponding to typical amorphous carbonaceous materials. FTIR was used to determine the chemical structure of SKPH. The bands at 3426, 2981, 2851, and 1604 cm−1 correspond to O–H, C-H, and C-O stretching vibrations, respectively. Then, it compares SKPH films with different carbon films using two electrolytic systems with and without charge transfer. The SKPH film showed a capacitive behavior in the KOH, H2SO4, and, KCl systems; in the acid medium, the presence of a redox couple associated with carbon functional groups was shown. Likewise, in the [Fe(CN)6]−3 and Cu(II) systems, the charge transfer process coupled with a capacitive behavior was described, and this effect is more noticeable in the [Fe(CN)6]−3 system. Electrodeposition of copper on SKPH film showed two stages Cu(NH3)2+4 /Cu(NH3)+2 and Cu(NH3)+2/Cu in ammonia media. Hydrogen formation and the activity of CO2 are observed on SKPH film and are favored by the carbon’s surface chemistry. Cu/SKPH electrocatalyst has a catalytic effect on electrochemical reduction of CO2 and inhibition of hydrogen formation. This study showed that the SKPH film electrode responds as a capacitive material that can be used as an electrode for energy storage or as metal support.

Progressive nigrostriatal terminal dysfunction and degeneration in the engrailed1 heterozygous mouse model of Parkinson's disease

Nordstrom, U.,Beauvais, G.,Ghosh, A.,Pulikkaparambil Sasidharan, B.C.,Lundblad, M.,Fuchs, J.,Joshi, R.L.,Lipton, J.W.,Roholt, A.,Medicetty, S.,Feinstein, T.N.,Steiner, J.A.,Escobar Galvis, M.L.,Prochi Blackwell Science ; Academic Press 2015 Neurobiology of disease Vol.73 No.-

Current research on Parkinson's disease (PD) pathogenesis requires relevant animal models that mimic the gradual and progressive development of neuronal dysfunction and degeneration that characterizes the disease. Polymorphisms in engrailed 1 (En1), a homeobox transcription factor that is crucial for both the development and survival of mesencephalic dopaminergic neurons, are associated with sporadic PD. This suggests that En1 mutant mice might be a promising candidate PD model. Indeed, a mouse that lacks one En1 allele exhibits decreased mitochondrial complex I activity and progressive midbrain dopamine neuron degeneration in adulthood, both features associated with PD. We aimed to further characterize the disease-like phenotype of these En1<SUP>+/-</SUP> mice with a focus on early neurodegenerative changes that can be utilized to score efficacy of future disease modifying studies. We observed early terminal defects in the dopaminergic nigrostriatal pathway in En1<SUP>+/-</SUP> mice. Several weeks before a significant loss of dopaminergic neurons in the substantia nigra could be detected, we found that striatal terminals expressing high levels of dopaminergic neuron markers TH, VMAT2, and DAT were dystrophic and swollen. Using transmission electron microscopy, we identified electron dense bodies consistent with abnormal autophagic vacuoles in these terminal swellings. In line with these findings, we detected an up-regulation of the mTOR pathway, concurrent with a downregulation of the autophagic marker LC3B, in ventral midbrain and nigral dopaminergic neurons of the En1<SUP>+/-</SUP> mice. This supports the notion that autophagic protein degradation is reduced in the absence of one En1 allele. We imaged the nigrostriatal pathway using the CLARITY technique and observed many fragmented axons in the medial forebrain bundle of the En1<SUP>+/-</SUP> mice, consistent with axonal maintenance failure. Using in vivo electrochemistry, we found that nigrostriatal terminals in the dorsal striatum were severely deficient in dopamine release and reuptake. Our findings support a progressive retrograde degeneration of En1<SUP>+/-</SUP> nigrostriatal neurons, akin to what is suggested to occur in PD. We suggest that using the En1<SUP>+/-</SUP> mice as a model will provide further key insights into PD pathogenesis, and propose that axon terminal integrity and function can be utilized to estimate dopaminergic neuron health and efficacy of experimental PD therapies.

Optimization of the Ag/PCBM interface by a rhodamine interlayer to enhance the efficiency and stability of perovskite solar cells

Ciro, J.,Mesa, S.,Uribe, J.,Mejia-Escobar, M.,Ramirez, D.,Montoya, J.,Betancur, R.,Yoo, H. S.,Park, N. G.,Jaramillo, F. Royal Society of Chemistry 2017 Nanoscale Vol.9 No.27

<P>Effective control of the interface between the metal cathode and the electron transport layer (ETL) is critical for achieving high performance p-i-n planar heterojunction perovskite solar cells (PSCs). Several organic molecules have been explored as interlayers between the silver (Ag) electrode and the ETL for the improvement in the photovoltaic conversion efficiency (PCE) of p-i-n planar PSCs. However, the role of these organic molecules in the charge transfer at the metal/ETL interface and the chemical degradation processes of PSCs has not yet been fully understood. In this work, we systematically explore the effects of the interfacial modification of the Ag/ETL interface on PSCs using rhodamine 101 as a model molecule. By the insertion of rhodamine 101 as an interlayer between Ag and fullerene derivatives (PC60BM and PC70BM) ETLs improve the PCE as well as the stability of p-i-n planar PSCs. Atomic force microscopy (AFM) characterization reveals that rhodamine passivates the defects at the PCBM layer and reduces the band bending at the PCBM surface. In consequence, charge transfer from the PCBM towards the Ag electrode is enhanced leading to an increased fill factor (FF) resulting in a PCE up to 16.6%. Moreover, rhodamine acts as a permeation barrier hindering the penetration of moisture towards the perovskite layer as well as preventing the chemical interaction of perovskite with the Ag electrode. Interestingly, the work function of the metal cathode remains more stable due to the rhodamine incorporation. Consequently, a better alignment between the quasi-Fermi level of PCBM and the Ag work function is achieved minimizing the energy barrier for charge extraction. This work contributes to reveal the relevance of proper interfacial engineering at the metal-cathode/organic-semiconductor interface.</P>

Development of Optimal Nanocrystalline Absorption Layer for Thin Film Silicon Solar Cell Applications

C. Álvarez-Macías,J. D. Escobar-Carrasquilla,A. Dutt,E. Mon-Pérez,L. González,G. Santana 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.11

To obtain an optimum absorption layer based on hydrogenated polymorphous and nanocrystalline silicon thin films in a plasma-enhanced chemical vapor deposition, radio frequency (RF) power was varied from 25W to 100W using a mixture of dichlorosilane and hydrogen. By Raman spectroscopy, the crystalline fraction was found to be varied from 7% to 69%, and RF power value of 75W was found to be suitable with an appropriate mixture of amorphous and crystalline phases, respectively. Thickness measurements performed by profilometry were cross-checked with the value obtained from the cross-sectional scanning electron microscopy micrographs. Micrographs obtained using high-resolution transmission electron microscopy confirmed the presence of silicon nanocrystals in the range of 2–5 nm with a strong probability of confinement effect. B and gap value of 1.55 eV at 75W upheld the suitability of this particular RF power for active absorption layer, which has also shown maximum photosensitivity.

First report of Gymnosporangium clavipes Cooke & Peck affecting Crataegus mexicana var. Chapeado and C. gracilior in Mexico

Alvarado-Rosales, D.,Nieto-Lopez, E.H.,Teliz-Ortiz, D.,Ayala-Escobar, V.,Silva-Rojas, H.V.,Nieto-Angel, R.,Leyva-Mir, S.G.,Jimenez-Nieto, A.,Mendez-Inocencio, C. The Korean Society of Plant Pathology 2015 식물병연구 Vol.21 No.3

The tejocote (Crataegus spp.) is a tree considered to be native to Mexico. The aim of this study was to identify the causal agent of tejocote rust in the State of Puebla. Tejocote fruits were sampled in 2012 and 2013. The fungus was studied morphologically using light and scanning electron microscopy and molecularly using phylogenetic analysis of 18S and 28S rDNA genes. The fungus was identified as Gymnosporangium clavipes on tejocote fruits. To our knowledge, this is the first confirmed report of Gymnosporangium clavipes Cooke & Peck affecting Crataegus mexicana var. Chapeado and C. gracilior in Puebla Mexico.

Practical Implementation of an Interleaved Boost Converter using SiC Diodes for PV Applications

C.N.M. Ho,H. Breuninger,S. Pettersson,G. Escobar,L. Serpa,A. Coccia 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

The implementation of an interleaved boost converter using SiC diodes for PV applications is presented in this paper. The converter consists of two switching cells sharing the PV panel output current. Their switching patterns are synchronized with 180 degree phase shift. Each switching cell has a SiC Schottky diode and a CoolMOS switching device. The SiC diodes provide zero reverse recovery current ideally, which reduces the commutation losses of the switches. Such advantage from the SiC diodes can make the converter system achieve higher efficiency and higher power density by reducing the requirement of the cooling system. This paper presents also an optimization study of the size and efficiency of the interleaved boost converter. Based on 1) the steady-state characteristic of the topology, 2) the static and dynamic characteristics of the switching cells, 3) the loss model of the magnetic components and 4) the cooling system design, the paper provides a set of design criteria, procedures and experimental results for a 2.5 ㎾ interleaved boost converter using SiC diodes prototype.

A Comparative Performance Study of an Interleaved Boost Converter using Commercialized Si and SiC Diodes for PV Applications

C.N.M. Ho,H. Breuninger,S. Pettersson,G. Escobar,F. Canales 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

A performance comparison of an interleaved boost converter (IBC) using Si and SiC diodes for PV energy conversion systems is presented in this paper. Performance attributes under investigation include the device behavior, thermal requirement, system efficiency and power density. The interleaved boost converter is designed for sustaining the dc link voltage in the energy conversion system. Due to the absence of reverse recovery current in SiC Schottky diodes, low switching loss is generated in the diodes and the switches. This benefit causes higher system efficiency and lower cooling system design requirement. As a benefit, the volume and weight of the heatsink can be further reduced. Furthermore, behaviors of semiconductors and steady-state characteristics of IBC are discussed in the paper. The validity of the analyses is confirmed experimentally by using a 2.5 ㎾ IBC prototype with wide power and input voltage operating range.

First report of Gymnosporangium clavipes Cooke & Peck affecting Crataegus mexicana var. Chapeado and C. gracilior in Mexico

D. Alvarado-Rosales,E. H. Nieto-López,D. Téliz-Ortiz,V. Ayala-Escobar,R. Nieto-Angel,H. V. Silva-Rojas,S. G. Leyva-Mir,A. Jiménez-Nieto,C. Méndez-Inocencio 한국식물병리학회 2015 식물병연구 Vol.21 No.3

The tejocote (Crataegus spp.) is a tree considered to be native to Mexico. The aim of this study was to identify the causal agent of tejocote rust in the State of Puebla. Tejocote fruits were sampled in 2012 and 2013. The fungus was studied morphologically using light and scanning electron microscopy and molecularly using phylogenetic analysis of 18S and 28S rDNA genes. The fungus was identified as Gymnosporangium clavipes on tejocote fruits. To our knowledge, this is the first confirmed report of Gymnosporangium clavipes Cooke & Peck affecting Crataegus mexicana var. Chapeado and C. gracilior in Puebla Mexico.