Evaluation of thermally and chemically reduced graphene oxide films as counter electrodes on dye-sensitized solar cells

Rodriguez-Perez, Manuel,Villanueva-Cab, Julio,Pal, Umapada Techno-Press 2017 Advances in nano research Vol.5 No.3

Graphene oxide (GO) was prepared by modified Hummer's method to produce reduced graphene oxide (RGO) following standard thermal and chemical reduction processes. Prepared RGO colloids were utilized to fabricate RGO films over glass and FTO coated glass substrates through drop-coating. A systematic study was performed to evaluate the effect of reduction degree on the optical and electrical properties of the RGO film. We demonstrate that both the reduction process (thermal and chemical) produce RGO films of similar optical and electrical behaviors. However, the RGO films fabricated using chemically reduced GO colloid render better performance in dye sensitized solar cells (DSSCs), when they are used as counter electrodes (CEs). It has been demonstrated that RGO films of optimum thicknesses fabricated using RGO colloids prepared using lower concentration of hydrazine reducer have better catalytic performance in DSSCs due to a better catalytic interaction with redox couple. The better catalytic performance of the RGO films fabricated at optimal hydrazine concentration is associated to their higher available surface area and lower grain boundaries.

Bioanode of Polyurethane/Graphite/Polypyrrole Composite in Microbial Fuel Cells

Pedro Perez-Rodriguez,Víctor M. Ovando-Medina,Silvia Y. Martinez-Amador,Jose A. Rodriguez-de la Garza 한국생물공학회 2016 Biotechnology and Bioprocess Engineering Vol.21 No.2

Polyurethane (PU) foams were coated with graphite, and pyrrole monomer was subsequently polymerized onto its surface by chemical oxidization to obtain nanostructured polyurethane/graphite/polypyrrole (PU/Graph/PPy) composites, which were used for anaerobic microorganisms grown and tested as anodes in microbial fuel cells (MFC) using municipal wastewater as fuel. The effects of oxidizing agent type (ammonium persulfate and FeCl3) used in pyrrole polymerization on the performance of electrodes in MFC were studied. Composites were characterized by Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and by the four-point probes to determine conductivity. It was observed from SEM analysis that globular nanostructures of PPy were formed onto PU surface with average diameters between 120 and 450 nm, which are typical of aqueous polymerization of pyrrole monomer. The highest output power density observed in MFCs was 305.5 mW/m3 for the composite synthesized using FeCl3 as the oxidant, and 128.6 mW/m3 using the composite obtained with ammonium persulfate as oxidizing; the corresponding chemical oxygen demand (COD) removal were 48.2 and 45.5%, respectively. The calculated coulombic efficiency for PU/Graph/PPy composite obtained with FeCl3 as oxidant was of 9.4%. Internal resistance of MFC using the composite obtained with FeCl3 as oxidant was determined by linear sweep voltammetry (LSV) and the variable resistance (VR) methods, giving 4.8 and 2.9 kΩ, respectively, with average maximum power density of 237.5 mW/m3.

A Radial Hybrid Estimation of Distribution Algorithm for the Vehicle Routing Problem with Time Windows

Ricardo Perez-Rodriguez 대한산업공학회 2021 Industrial Engineeering & Management Systems Vol.20 No.2

The vehicle routing environment has been widely studied under different approaches. It is due to its practical characteristic that makes its research interesting. Therefore, the vehicle-scheduling problem continues being attracted to develop new evolutionary algorithms. In this paper, we propose a new estimation of distribution algorithm coupled with a radial probability function. The aforementioned radial function comes from the hydrogen element. Continuous values, for the solution representation, are used in this research. Each value represents the distance, in picometers, between the electron and the core of the hydrogen atom. The representation, elected in this research, is suitable to integrate the radial probability distribution as a probability model. This approach is proposed in order to build a competitive estimation of distribution algorithm for the vehicle routing problem with time windows. The key point is to exploit the radial probability distribution to construct offspring, and to tackle the inconvenient of the estimation of distribution algorithms, i.e., lack of diversity of the solutions and poor ability of exploitation. In addition, this paper omits to use permutation-based representation as other recent estimation of distribution algorithms. Various instances and numerical experiments are presented to illustrate, and to validate this novel research. The results, obtained from this research, permits to conclude that using radial probability distributions is an emerging field to develop new and efficient EDAs.

Vitamin D and its effects on cardiovascular diseases: a comprehensive review

( Nonanzit Perez-hernandez ),( Gad Aptilon-duque ),( Maria Cristina Nostroza-hernandez ),( Gilberto Vargas-alarcon ),( Jose Manuel Rodriguez-perez ),( Ruben Blachman-braun ) 대한내과학회 2016 The Korean Journal of Internal Medicine Vol.31 No.6

Vitamin D is a molecule that is actively involved in multiple metabolic pathways. It is mostly known for its implications related to calcium metabolism. It has also been determined that it actively participates in the cardiovascular system, influencing blood pressure, coronary artery disease and other vascular diseases, such as heart failure and atrial fibrillation. Furthermore, it has been established that this vitamin is extensively involved in the regulation of both the renin angiotensin aldosterone system and the immune system. In this review, we present the different vitamin D metabolic pathways associated with the cardiovascular pathophysiology, and we include studies in animal and human models, as well as some of the controversies found in the literature. This review also incorporates an overview of the implications in the molecular biology and public health fields.

Effect of recombinant baculovirus expressing CrV1 protein from Cotesia rubecula bracovirus against Pieris rapae in insecticidal toxicity

Lihua Wei,Miguel A. PEREZ-RODRIGUEZ,Mario A. RODRIGUEZ-PEREZ 한국곤충학회 2016 Entomological Research Vol.46 No.3

Baculoviruses can be genetically engineered to express foreign genes; thus, their lethal potency and host range can be improved to produce more virulent bioinsecticides. Polydnavirus (PDV) genes have insecticidal bioactivities and could enhance the pathogenicity of the baculoviruses to control insect pests. The CrV1 gene from Cotesia rubecula polydnavirus is responsible for depolymerization of actin cytoskeleton in hemocytes, disabling its spread on foreign object surfaces. In this study, we tested the efficacy of the recombinant baculovirus (AcMNPV‐CrV1) under p10 promoter against second instar P. rapae larvae. The expression of the CrV1 gene in P. rapae larvae was verified with reverse transcription–polymerase chain reaction (RT‐PCR). AcMNPV‐CrV1 showed a significantly lower median lethal concentration (LC50) and shorter median lethal time (LT50) as compared with the AcMNPV wild‐type virus. These results suggested that the expression of CrV1 protein could successfully improve the insecticidal toxicity of baculovirus.

Oral findings and its association with prenatal and perinatal factors in newborns

Perez-Aguirre, Brenda,Soto-Barreras, Uriel,Loyola-Rodriguez, Juan Pablo,Reyes-Macias, Juan Francisco,Santos-Diaz, Miguel Angel,Loyola-Leyva, Alejandra,Garcia-Cortes, Obed The Korean Pediatric Society 2018 Clinical and Experimental Pediatrics (CEP) Vol.61 No.9

Purpose: This study aimed to determine the frequency of abnormalities in the newborn oral cavity and to evaluate the association with prenatal and perinatal factors. Methods: This cross-sectional study evaluated 2,216 newborns. Oral findings were assessed in the first 24 hours of life using visual examination. Sex, weight, length, gestational age, and medical disorders at birth were recorded. Maternal demographic and medical information was also obtained. Results: The most common oral findings were Bohn's nodules, Epstein's pearls, and dental lamina cysts. Other intraoral findings included odontogenic cysts, ankyloglossia, and natal teeth, among others. In logistic regression analyses, folic acid consumption during pregnancy was significantly associated with Bohn's nodules (odds ratio [OR], 1.79; 95% confidence interval [CI], 1.23-2.55; P=0.002), Epstein's pearls (OR, 1.63; 95% CI, 1.14-2.33; P=0.007), and dental lamina cysts (OR, 1.45; 95% CI, 1.02-2.05; P=0.038). Moreover, preterm births were negatively associated with prevalence of Bohn's nodules (OR, 0.63; 95% CI, 0.50-0.80; $P{\leq}0.0001$). Comparison between newborns with and without oral inclusion cysts showed that maternal folic acid and iron intake were significantly different (P<0.05). Conclusion: Maternal folic acid and iron intake were associated with the prevalence of oral inclusion cysts.

Oral findings and its association with prenatal and perinatal factors in newborns

Brenda Perez-Aguirre,Uriel Soto-Barreras,Juan Pablo Loyola-Rodriguez,Juan Francisco Reyes-Macias,Miguel Angel Santos-Diaz,Alejandra Loyola-Leyva,Obed Garcia-Cortes 대한소아청소년과학회 2018 Clinical and Experimental Pediatrics (CEP) Vol.61 No.9

Purpose: This study aimed to determine the frequency of abnormalities in the newborn oral cavity and to evaluate the association with prenatal and perinatal factors. Methods: This cross-sectional study evaluated 2,216 newborns. Oral findings were assessed in the first 24 hours of life using visual examination. Sex, weight, length, gestational age, and medical disorders at birth were recorded. Maternal demographic and medical information was also obtained. Results: The most common oral findings were Bohn’s nodules, Epstein’s pearls, and dental lamina cysts. Other intraoral findings included odontogenic cysts, ankyloglossia, and natal teeth, among others. In logistic regression analyses, folic acid consumption during pregnancy was significantly associated with Bohn’s nodules (odds ratio [OR], 1.79; 95% confidence interval [CI], 1.23–2.55; P=0.002), Epstein’s pearls (OR, 1.63; 95% CI, 1.14–2.33; P=0.007), and dental lamina cysts (OR, 1.45; 95% CI, 1.02–2.05; P=0.038). Moreover, preterm births were negatively associated with prevalence of Bohn’s nodules (OR, 0.63; 95% CI, 0.50–0.80; P≤0.0001). Comparison between newborns with and without oral inclusion cysts showed that maternal folic acid and iron intake were significantly different (P<0.05). Conclusion: Maternal folic acid and iron intake were associated with the prevalence of oral inclusion cysts.

Phnological Behavivor of Avocado (Persea Americana L.) in the North-Center Coast of Venezuela

Mercedes M. Perez,Luis A. Avilan,Enio R. Soto,Carlos Marin,Margot Rodriguez,Jose Ruiz 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-

Antioxidant Capacity of Crude Extracts from Clones of Banana and Plane Species

Antonio J. Rodriguez-Malaver,Elizabeth M. Perez-P?ez,Nayalet Padilla,Gerardo Medina-Ram?ez,Juan Davila 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.4

Banana and plane are the most important fruits in world trade, behind citric plants. In this work we studiedthe antioxidant capacity of banana and plane varieties of fruits obtained from interspecies crossed varieties of Musa acumi-nataand Musa balbisiana, named Harton plane, Cavendish banana, and Manzano banana. With this purpose we evaluatedbanana and plane crude extracts using the ferrous ion oxidation with xylenol orange method, the thiobarbituric acid method,determination of antioxidant activity, and effect on superoxide anion and hydroxyl radical and the radicals generated by ul-traviolet light. The experiments showed that all extracts have the capacity to decrease the concentrations of lipid hydroper-oxides and malondialdehyde, produced in the lipid peroxidation process, in a manner comparable to that of other widely stud-ied antioxidants like melatonin and vitamin E. Moreover, all extracts had the capacity to inhibit the generation of superoxideanion, hydroxyl radical, and the radicals generated by ultraviolet light. When antioxidant activity was calculated, a value wasfound that was equivalent to a concentration of uric acid between 0.20 and 0.30 mM at the highest concentration of extractused, with uric acid being a potent antioxidant at 1 mM.

Inverse behavior of IL-23R and IL-17RA in chronic and aggressive periodontitis

Ruiz-Gutierrez, Alondra del Carmen,Rodriguez-Montano, Ruth,Pita-Lopez, Maria Luisa,Zamora-Perez, Ana Lourdes,Guerrero-Velazquez, Celia Korean Academy of Periodontology 2021 Journal of Periodontal & Implant Science Vol.51 No.4

Purpose: Periodontitis is associated with a dysbiosis of periodontopathic bacteria, which stimulate the interleukin (IL)-23/IL-17 axis that plays an essential role in the immunopathogenesis of this disease, leading to alveolar bone destruction through receptor activator of nuclear factor κB ligand (RANKL). IL-23 receptor mRNA (IL-23R) has been identified in periodontitis, and IL-17 receptor A mRNA (IL-17RA) and its protein have not yet been evaluated in patients with periodontitis. In this study was measure IL-23R and IL-17RA in gingival tissue (GT) from patients with generalized chronic periodontitis (GCP) and generalized aggressive periodontitis (GAP) and to explore correlations with clinical parameters. Methods: We included 16 healthy subjects (HS), 18 patients with GCP, and 14 with GAP. GT samples were collected during periodontal surgery. Both IL-23R and IL-17RA were detected by enzyme-linked immunosorbent assay. Results: The results were analyzed with Mann-Whitney U test and Spearman' rank correlation coefficients using SPSS version 25.0. We found lower IL-23R levels in patients with GCP and GAP than in HS. Contrarily, we observed higher IL-17RA levels in GCP and GAP patients than in HS. Moreover, we found negative correlations between IL-23R in GT and probing depth and clinical attachment loss (CAL). Likewise, a positive correlation of IL-17RA in GT with CAL was found. Conclusions: The results of these findings suggest that the reverse behavior between IL-23R and IL-17RA in periodontitis patients may also be involved with the activation of RANKL, which promotes alveolar bone loss.