In this paper an evaluation of the influence of luminance L* at the L*a*b* color space during color segmentation is presented. A comparative study is made between the behavior of segmentation in color images using onl...In this paper an evaluation of the influence of luminance L* at the L*a*b* color space during color segmentation is presented. A comparative study is made between the behavior of segmentation in color images using only the Euclidean metric of a* and b* and an adaptive color similarity function defined as a product of Gaussian functions in a modified HSI color space. For the evaluation synthetic images were particularly designed to accurately assess the performance of the color segmentation. The testing system can be used either to explore the behavior of a similarity function (or metric) in different color spaces or to explore different metrics (or similarity functions) in the same color space. From the results is obtained that the color parameters a* and b* are not independent of the luminance parameter L* as one might initially assume.展开更多
Herein,we present the electrocatalytic four-electron hydrogenation of oxalic acid into glycolic acid using black TiO_(2)as an electrocatalyst.Oxalic acid is an abundant compound found in several sources of organic was...Herein,we present the electrocatalytic four-electron hydrogenation of oxalic acid into glycolic acid using black TiO_(2)as an electrocatalyst.Oxalic acid is an abundant compound found in several sources of organic waste.The results showed a high selectivity of black TiO_(2)toward glycolic acid,with the formation of glyoxylic acid being the rate-limiting step (glyoxylic acid is the two-electron intermediate).The highest Faradaic efficiency (FE) of 69.6%±8.3% was achieved at 10.2 mA cm^(-2)in 4 h of electrolysis using an H-type cell operated at room temperature,with 50.2%±3.8% of oxalic acid conversion (degradation kinetic constant k=0.0042±0.0001 min-1),58.8%±7.0%of reaction yield and 1.2±0.18 g L-1of glycolic acid production.A theoretical model of black TiO_(2)coming from anatase TiO_(2)was implemented by introducing Ti3+defects,which gave black TiO_(2)the theoretical capability to easily transform oxalic acid into glycolic acid as experimentally observed.The reaction mechanism was supported and described in detail by density functional theory calculations,which revealed that surface Ti^(3+)states were the main catalytic sites.This is the first time that a detailed step-by-step mechanism at the atomic level has been proposed for this electrocatalytic reaction,which represents a valuable contribution to the understanding of this process of high energy/environmental interest.This is also the first time that black TiO_(2)has been used as an electrocatalyst for this sustainable process.展开更多
Due to a complex geological and biotic history,the Isthmus of Tehuantepec(IT),has been long recognized as a driver for the evolutionary divergence of numerous lowland and highland taxa.Widely distributed in the lowlan...Due to a complex geological and biotic history,the Isthmus of Tehuantepec(IT),has been long recognized as a driver for the evolutionary divergence of numerous lowland and highland taxa.Widely distributed in the lowlands of the American continent,the White-Tipped Dove(Leptotila verreauxi)is a polytypic species with 13 recognized subspecies.Four of these have been recorded in Mexico,and the distribution of three abuts at the IT,suggesting a contact zone.To estimate phylogenetic patterns,divergence times and genetic differentiation,we examined two mt DNA(ND2 and COI)and one n DNA(β-fibint 7)markers.We also used correlative ecological niche models(ENM)to assess whether ecological differences across the IT may have acted as a biogeographical boundary.We estimated paleodistributions during the Middle Holocene,Last Glacial Maximum and Last Interglacial,to evaluate the influence of climate changes on the distribution and demographic changes.Our results showed genetically distinct lineages that diverged approximately 2.5 million years ago.Climatic and ecological factors may have played a dual role in promoting differentiation,but also in the formation of a secondary contact zone in the southern IT.Our ecological niche comparisons indicated that the ecological niche of sympatric lineages at the IT are not identical,suggesting niches divergence;in addition,environmental niche models across the region indicated no abrupt biogeographic barriers,but the presence of regions with low suitability.These results suggest that genetic differentiation originated by a vicariant event probably related to environmental factors,favored the evolution of different ecological niches.Also,the absence of a biogeographic barrier but the presence of less suitable areas in the contact regions,suggest that secondary contact zones may be also maintained by climatic factors for the eastern group,but also by biotic interactions for the western group.展开更多
The present study aimed to evaluate multi-element concentrations(Al,As,Ca,Cd,Co,Cr,Cu,Fe,Mg,Mn,Mo,Ni,Pb,Sr)in suspended particulate material(SPM)collected from Ensenada de La Paz(ELP)lagoon,Baja California Sur,Mexico ...The present study aimed to evaluate multi-element concentrations(Al,As,Ca,Cd,Co,Cr,Cu,Fe,Mg,Mn,Mo,Ni,Pb,Sr)in suspended particulate material(SPM)collected from Ensenada de La Paz(ELP)lagoon,Baja California Sur,Mexico in two different periods(September and May)to comprehend their origin,geochemical behavior,mass transfer and associated ecotoxicological risks.The 24 hr variation coefficient of volumetric SPM levels were found to be 51.7%in September and 40.5%in May,signifying the effects of oceanic waters.The calculated enrichment factor(EF)values for all the studied elements were of higher magnitude because of the high surface area and oxide nature of SPM,and in this study,Mo had the highest EF of 46.77 probably due to its origin from continental weathering.From the ecotoxicological perspective,the integrated toxic risk index revealed low toxic risk to the benthic community.However,the mean-ERM-Quotient calculated using the particulate concentrations of As,Cd,Cr,Cu,Ni,Pb indicated 9%probability of toxicity to biota.The comprehensive geochemical and ecotoxicological assessment of particulate metal concentrations in the ELP lagoon signify low to moderate contamination.展开更多
The forest industry operates in a dynamic and global market where change and competition are the rule rather than the exception. The color of wood is one of the most attractive features for the modem wood industry. Ev...The forest industry operates in a dynamic and global market where change and competition are the rule rather than the exception. The color of wood is one of the most attractive features for the modem wood industry. Even when wood is chosen for its structural qualities, attractive and decorative colors are usually an important factor. In many applications, particularly in furniture, decorative products, decorative veneers and flooring, accurate matching of the color of different samples is required. Wood attributes and properties are important because they have a direct bearing on market opportunities and consumer acceptance for many types of manufactured wood products. The aim of this review is to identify causes of wood discoloration and advances in drying technology to overcome this problem. Wood discoloration is a complex phenomenon, mainly affected by heat, light, physiological and biochemical reactions, as well as from attack by microorganisms.展开更多
Background: Liver recurrence after resection of colorectal liver metastases(CRLM) is frequent. Repeat hepatectomy has been shown to have satisfactory perioperative results. However, the long-term outcomes and the bene...Background: Liver recurrence after resection of colorectal liver metastases(CRLM) is frequent. Repeat hepatectomy has been shown to have satisfactory perioperative results. However, the long-term outcomes and the benefts for patients with early recurrence have not been clarifed. The aim of this study was to compare the short-and long-term outcomes of patients undergoing single hepatectomy and repeat hepatectomy for CRLM. Additionally, the oncological outcomes of patients with early( ≤ 6 months) and late recurrence who underwent repeat hepatectomy were compared. Methods: Consecutive adult patients undergoing hepatectomy for CRLM between June 20 0 0 and February 2020 were included and divided into two groups: single hepatectomy and repeat hepatectomy. Results: A total of 709 patients were included: 649 in the single hepatectomy group and 60 in the repeat hepatectomy group. Patients in the repeat hepatectomy group underwent more cycles of preoperative chemotherapy [4(3-6) vs. 3(2-4), P = 0.003]. Patients in the single hepatectomy group more frequently underwent major hepatectomies(34.5% vs. 16.7%, P = 0.004) and had a greater number of lesions resected(2.9 ± 3.6 vs. 1.9 ± 1.8, P = 0.011). There was no increase in operative time, estimated blood loss, length of hospital stay, complications, or mortality in the repeat hepatectomy group. There were no differences in overall survival( P = 0.626) and disease-free survival( P = 0.579) between the two groups. Similarly, for patients underwent repeat hepatectomy, no difference was observed between the early and late recurrence groups in terms of overall survival( P = 0.771) or disease-free survival( P = 0.350). Conclusions: Repeat hepatectomy is feasible and safe, with similar short-and long-term outcomes when compared to single hepatectomy. Surgical treatment of early liver recurrence offers similar oncological outcomes to those obtained for late recurrence.展开更多
Colletotrichum gloeosporioides is the causal agent of anthracnose disease in fruits and vegetables, representing a global problem. The use of biocontrol agents has proved effective against fungal diseases in a wide va...Colletotrichum gloeosporioides is the causal agent of anthracnose disease in fruits and vegetables, representing a global problem. The use of biocontrol agents has proved effective against fungal diseases in a wide variety of products. In this work, the antifungal activity of Wickerhamomyces anomalus against C. gloeosporioides isolated from contaminated avocados was evaluated. The antagonism and volatile compound inhibition were measured on Petri dishes. In the mixed cultures, the mycelia damage was observed by scanning electron microscope （SEM）. Chitinase and glucanase production by the antagonism was quantified by the reducing sugars method, and biofilm formation was evaluated with 1% crystal violet. The yeast W. anomalus could reduce the growth of C. gloeosporioides up to 65% by direct antagonism and 10% by volatile compounds. The antagonist did not allow the conidia germination and mycelia growth in any of the tested formulations. SEM showed mycelial damage caused by W. anomalus. The antagonist showed adhesion to the mycelium by a polysaccharide biofilm. The presence of mycelium stimulated the hydrolytic enzyme production with the maximal activity of 21.4 U/mg for chitinases at 24 h and 10 U/mg for glucanases at 60 h. These results showed that W. anomalus used together different mechanisms to express its antifungal activity against C. gloeosporioides. This study might be the first report for this phytopathogen isolated from avocado fruits, which could represent an opportunity to establish biocontrol of diseases for this agricultural product.展开更多
The Late Pleistocene littoral ridges of southern South America,especially those of the north of Argentinean Patagonia,contain remains of mollusk shells with bioerosion traces.Eleven sites from marine isotope stages(2 ...The Late Pleistocene littoral ridges of southern South America,especially those of the north of Argentinean Patagonia,contain remains of mollusk shells with bioerosion traces.Eleven sites from marine isotope stages(2 from MIS 7,4 from MIS 5 e)and five sites from modern beaches from northern Río Negro Province,with 40 taxa(17 bivalves and 23 gastropods)were analyzed,in the area between west of Baliza San Matías and Las Grutas(41°S).Three ichnogenera were identified in deposits of MIS 7:Entobia,Gastrochaenolites(Domichnia)and Oichnus(Praedichnia)with one ichnospecies(G.torpedo).Six ichnogenera were identified in deposits of MIS 5 e:Entobia,Meandropolydora,Pinaceocladichnus,Iramena,Caulostrepsis and Oichnus with one ichnospecies(O.simplex).Seven ichnogenera were identified from modern beaches:Entobia,Meandropolydora,Iramena,Caulostrepsis,Pinaceocladichnus,Gastrochaenolites(Domichnia)and Oichnus(Praedicnia),with two ichnospecies(O.simplex and O.paraboloides).On this basis,it is inferred that Pleistocene benthic communities were constituted from cheilostome bryzoans and polychaete annelids,together with drilling bivalves,predatory gastropods and overall warm-water species of mollusks.Of these,Chama iudicai was found on Plicatula gibbosa from MIS 7 and MIS 5 e.The record of warm temperature species suggests a higher sea surface temperature(SST)than the present one and/or the influence of the warm southward Brazilian Current affecting the waters of Golfo San Matías.On the modern beaches surveyed,there is an increase in polychaete annelids,cheilostome bryzoans,temperate-cold species and drilling bivalves,as well as sandy substrate species,which together with an increase of Gastrochaenolites and Caulostrepsis,suggest a colder climate due to the greater influence of the Malvinas Current during the Holocene.展开更多
Objective:To ascertain the antibiotic susceptibility patterns of Escherichia coli recovered from blood culture specimens in Calabar.Nigeria.Methods:The study was retrospective in nature and was carried out at Universi...Objective:To ascertain the antibiotic susceptibility patterns of Escherichia coli recovered from blood culture specimens in Calabar.Nigeria.Methods:The study was retrospective in nature and was carried out at University of Calabar Teaching Hospital(UCTH) Calabar.Data generated from blood culture specimens over a five year period(Feb.2004-Feb.2009) was compiled, relevant information such as age,sex,organism recovered and antibiotic susceptibility patterns were obtained from patients records.Samples were collected,transported,stored and processed using standard laboratory procedures.Data obtained was analysed using Epi Info 6 statistical software.Results:Escherichia coli was responsible for 15.3%(31/203) of the blood infections being the third most common microorganism encountered.The community acquired(CA) isolates of the organism were significantly less resistant(P【0.05),compared to the nosocomial(NC) isolates against ampicillin.cloxacillin,amoxicillin,tetracycline,co-trimoxazole.chloramphenicol and erythromycin.The sensitivity of both the NC and CA isolates of Escherichia coli to amikacin, augmentin,ofloxacin,ciprofloxacin,ceftazidime,cefuroxime,ceftriaxone and rifampicin was generally high(80-100%) with no significant difference(P】0.05).Majority(】95.0%) of the NC isolates of Escherichia coli were resistant to six of the antibiotics tested.Conclusions:Control mechanisms for hospital acquired infections should be stepped up so as lo limit the spread of the highly resistant bacterial strains.Also the sale and consumption of antibiotics by the public need to be regulated.展开更多
The purpose of this study was to analyzed the outcome in patients with acute obstruction of the left colonrectal cancer who was treated by double tube intraoperative levage methods.Methods Between 1999 and 2003,62 pat...The purpose of this study was to analyzed the outcome in patients with acute obstruction of the left colonrectal cancer who was treated by double tube intraoperative levage methods.Methods Between 1999 and 2003,62 patients with acute obstruction for cancer underwent surgery.The patients were divided into two groups at random,31 patients were treated with double tube intraoperative lavage,resection,and primary anastomosis.31 patients were treated with traditional resection,and after 1～2 month,Ⅱ stage anastomosis.Results In double tube intraoperative lavage,No case occurred anastomotic leakage.The patients got a satisfactory recovery post-operatively.Conclusion It was concluded that one-satge emergency surgery for left obstrucing colonic cancers is safe with the regard of double tube intraoperative lavage methods.6 refs,1 tab.展开更多
Objective To study microsurgical effectiveness Foerster-Dandy’s endoscope-assisted operation for treatment of spasmodic torticollis. Methods 183 cases of spasmodic torticollis patients were treated by microsurgical m...Objective To study microsurgical effectiveness Foerster-Dandy’s endoscope-assisted operation for treatment of spasmodic torticollis. Methods 183 cases of spasmodic torticollis patients were treated by microsurgical modified Foerster-Dandy’s operation from July 2001 to June 2009,which was randomly展开更多
Objective To study the mechanism of myocardial dielectric property changes in radio frequency during hypothermic preservation and explore myocardial viability evaluative method. Methods Hybrid young pigs ( 20 - 30 kg)...Objective To study the mechanism of myocardial dielectric property changes in radio frequency during hypothermic preservation and explore myocardial viability evaluative method. Methods Hybrid young pigs ( 20 - 30 kg) were used in the experiment. Heart arrest was in-展开更多
Objective To investigate the role of endothelin(ET) in the proliferation and collagen synthesis of human scar-derived fibroblasts and the moduktion of its antagonists such as nitric oxide(NO), tetrandrine ( Tet). Meth...Objective To investigate the role of endothelin(ET) in the proliferation and collagen synthesis of human scar-derived fibroblasts and the moduktion of its antagonists such as nitric oxide(NO), tetrandrine ( Tet). Methods With the cultured fibroblasts from the scarring tissue, the cell pdiferation was determined by[3H]-TdR incorporation, while the collagen synthesis was evaluated by[3H]-proline incorporation. Results The ET-1 was significantly increasing the proliferation and collagen synthesis of human scar-derived fibroblasts. The values of [3H]-TdR absorption in the 2.5 ng/ml,25 ng/ml and 100 ng/ml of ET-1 groups were 1.8 times,4 times and 4.9 times more than in the control group, respectively(P【0. 01),while the values of the [3H]-proline incorporation were 1.1 times,3.1 times and 3.8 times respectively(P【0.01). The fibroblasts, treated with 50 μg/ml of S-nitroso-N-acetyl penicillamine(SNAP), were no detectable effect on the basal level of DNA synthesis,but produced decreasing effect on the展开更多
Compare the effects of locomotion therapy and pelvis traction therapy to treat Ⅰ～Ⅱ° thoracolumbar compression fracture.Methods Ninety-two cases with Ⅰ～Ⅱ° thoracolumbar compression fracture were selecte...Compare the effects of locomotion therapy and pelvis traction therapy to treat Ⅰ～Ⅱ° thoracolumbar compression fracture.Methods Ninety-two cases with Ⅰ～Ⅱ° thoracolumbar compression fracture were selected and divided into 2 groups with locomotion therapy and pelvis traction thepapy respectively.Results Thoracolumbar height was measured according to X-ray results after 1 year follow-up.The height was (17.2±2.3)mm preoperatively and (24.4±3.1)mm postoperatively in locomotion therapy group while (16.8±2.6)mm preoperatively and (23.9±2.7)mm postoperatively in the pelvis traction therapy group.Conclusion There is no significant difference between effects on two groups.5 refs.展开更多
To explore the influence of aprotinin on the mRNA expression of P-selectin and ICAM-1 in lung tissue after ischemic reperfusion.Methods Thirty New Zealand white rabbits were randomly divided into 3 groups:control grou...To explore the influence of aprotinin on the mRNA expression of P-selectin and ICAM-1 in lung tissue after ischemic reperfusion.Methods Thirty New Zealand white rabbits were randomly divided into 3 groups:control group,LPD group and aprotinin group.In situ rabbit lung preservation model was established.In control group,the left lower lung lobe was stored at 10℃ in a specially made lung preservation container for 2 hours and reperfused for another 2 hours.In LPD group and aprotinin group,the left lower lobe was perfused with LPD solution or aprotinin containing LPD solution,respectively,after left lung hilus was clamped.The other procedures were the same as those in control group.The lung tissue was harvested at different time intervals including preclamping lung hilus,2 hours after clamping and 2 hours after reperfusion.The mRNA expression of ICAM-1 and P-selectin in the lung tissue was detected with RT-PCR technique.Results The contents of mRNA of P-selectin at 2 hours after reperfusion in control group and LPD group were significant higher than pre-ischemia and 2 hours after champing the left lung hilus.There was no such significant difference in aprotinin group.The mRNA expression of P-selectin in aprotinin group at 2 hours after reperfusion was significantly lower than that in control group and LPD group.The ICAM-1 mRNA expression at 2 hours after Ischemia and 2 hours after reperfusion in control group and LPD group was significantly higher than the pre-ischemia and its was significantly higher than that in aprotinin group.Conclusion Aprotinin can inhibit the upregulation of the mRNA expression of P selectin and ICAM-1 after ischemia reperfusion in the lung tissue,so the addition of aprotinin in LPD solution may reduce the ischemia reperfusion injury in lung tissue.5 refs,1 tab.展开更多
This research presents the influence of copper(Cu) concentration on the properties of copper zinc tin sulfide(CZTS) nanoparticles(NPs) synthesized by a colloidal method, employing oleylamine as an organic solvent. Fro...This research presents the influence of copper(Cu) concentration on the properties of copper zinc tin sulfide(CZTS) nanoparticles(NPs) synthesized by a colloidal method, employing oleylamine as an organic solvent. From the structural analysis, a pure phase of CZTS was obtained at an optimized molar ratio of 1.8:1.1:1:4,and secondary phases were observed as the Cu concentration increased. The increment of the NPs size from 15 to50 nm was noticed as a function of Cu concentration.Importantly, the optical bandgap energy was tuned from1.35 to 1.68 eV with respect to Cu concentration. The sample synthesized at the molar ratio of 1.8:1.1:1:4 showed a pure phase CZTS with desired elemental composition and bandgap. Furthermore, CZTS thin films were prepared by a doctor-blade method using synthesized NPs followed by annealing under a sulfur/nitrogen atmosphere. The annealed CZTS film showed a significant improvement in the morphological, electrical and optoelectronic properties.Thus, the annealed CZTS film can be efficiently used as an absorber layer in low-cost thin film solar cells.展开更多
Objective To summarize the experience of management in the living related small bowel transplantation for One patient with short gut syndrome and resection of right colon with complication of ileus-colon anastomosis f...Objective To summarize the experience of management in the living related small bowel transplantation for One patient with short gut syndrome and resection of right colon with complication of ileus-colon anastomosis fistulas. Methods One patient with almost all small bowel and right colon reseeted for embolism of superior mesenteric artery underwent the living related small bowel transplantation.展开更多
Mayamontana coccolobae Castellano,Trappe and Lodge is described for the first time from Mexico and the second time worldwide.It is characterized by the orange,subhypogeous basidiomata and the wrinkled subglobose spore...Mayamontana coccolobae Castellano,Trappe and Lodge is described for the first time from Mexico and the second time worldwide.It is characterized by the orange,subhypogeous basidiomata and the wrinkled subglobose spores with conspicuous hilar appendix.It is not a very common species in the region and is recorded from disturbed lowland forest and urban gardens.Mayamontana coccolobae was only known from the type locality but now extends its geographical distribution to southeast Mexico.展开更多
The occurrence of seven endocrine-disrupting compounds(EDCs)in four urban rivers on the southern border of Mexico was studied in this work.The selected EDCs were 17b-estradiol(E2),estriol(E3),17aethinylestradiol(EE2),...The occurrence of seven endocrine-disrupting compounds(EDCs)in four urban rivers on the southern border of Mexico was studied in this work.The selected EDCs were 17b-estradiol(E2),estriol(E3),17aethinylestradiol(EE2),bisphenol A(BPA),bisphenol F(BPF),4-nonylphenol(4NP)and 4-tert-octylphenol(4TOP).Water samples from the Coatan,Texcuyuapan,Cahoacan,and Coatancito rivers were collected at three different sites on each river and processed by solid phase extraction(SPE).The samples were analyzed by gas chromatography triple quadrupole tandem mass spectrometry(GC-MS/MS)and compounds of interest were identified by dynamic mass reaction monitoring mode(dMRM).Among the target EDCs,E2,BPA,and 4NP were detected in all water samples,with BPA being the most abundant ranging from 4.22 up to 127.96 ng/L.Correlation tests showed significant positive associations between estrogens and BPA,as well as the correlation between alkylphenols and BPA,suggesting common origin emission sources,which were identified as discharges of untreated municipal wastewater.Finally,the estimation of RQ and EEQ values indicated that the presence of E2,E3,EE2,and BPA in all sampled points represents a high risk for aquatic life in these sites,mainly for Texcuyuapan River,where the aquatic organisms may be susceptible to endocrine disruption by chronic exposure to detected compounds.展开更多
This study reports radiological deformities in the vertebral column of six fishes viz,Scomberomorus commerson,Chanos chanos,Sillago sihama,Pampus chinensis,Rastrelliger kanagurta and Netuma thalassina that were collec...This study reports radiological deformities in the vertebral column of six fishes viz,Scomberomorus commerson,Chanos chanos,Sillago sihama,Pampus chinensis,Rastrelliger kanagurta and Netuma thalassina that were collected from the Coromandel coast,Bay of Bengal.Four main different types of vertebral column deformities were found:(i)whole body kypho-lordo-kyphosis(Sillago sihama,Rastrelliger kanagurta,Netuma thalassina);(ii)tail region kypho-lordosis(Scomberomorus commerson);(iii)tail region lordo-kyphosis(Chanos chanos);(iv)platyspondyly(Pampus chinensis).Seven types of vertebra body deformities,describing the pathology of single vertebrae,were present;reduced intervertebral space,compression,fusion,compresion&fusion,fusion center,dorsal wedge-shaped and compressed&dorsal wed-shaped.The present documentation of deformities in six different species that are also very different with regard to habitat,diet and swimming activity may suggest that fish deformities are widespread in the study area.展开更多
文摘In this paper an evaluation of the influence of luminance L* at the L*a*b* color space during color segmentation is presented. A comparative study is made between the behavior of segmentation in color images using only the Euclidean metric of a* and b* and an adaptive color similarity function defined as a product of Gaussian functions in a modified HSI color space. For the evaluation synthetic images were particularly designed to accurately assess the performance of the color segmentation. The testing system can be used either to explore the behavior of a similarity function (or metric) in different color spaces or to explore different metrics (or similarity functions) in the same color space. From the results is obtained that the color parameters a* and b* are not independent of the luminance parameter L* as one might initially assume.
基金DGAPA (Dirección General de Asuntos del Personal Acadé-mico) under Projects No. IA103521, IA209223 and IN111722Supercomputing Department of the Universidad Nacional Autónoma de México for the computing resources under Projects No. LANCAD-UNAM-DGTIC-427 and LANCAD-UNAM-DGTIC-370CONAHCYT-México for their postdoctoral fellowships。
文摘Herein,we present the electrocatalytic four-electron hydrogenation of oxalic acid into glycolic acid using black TiO_(2)as an electrocatalyst.Oxalic acid is an abundant compound found in several sources of organic waste.The results showed a high selectivity of black TiO_(2)toward glycolic acid,with the formation of glyoxylic acid being the rate-limiting step (glyoxylic acid is the two-electron intermediate).The highest Faradaic efficiency (FE) of 69.6%±8.3% was achieved at 10.2 mA cm^(-2)in 4 h of electrolysis using an H-type cell operated at room temperature,with 50.2%±3.8% of oxalic acid conversion (degradation kinetic constant k=0.0042±0.0001 min-1),58.8%±7.0%of reaction yield and 1.2±0.18 g L-1of glycolic acid production.A theoretical model of black TiO_(2)coming from anatase TiO_(2)was implemented by introducing Ti3+defects,which gave black TiO_(2)the theoretical capability to easily transform oxalic acid into glycolic acid as experimentally observed.The reaction mechanism was supported and described in detail by density functional theory calculations,which revealed that surface Ti^(3+)states were the main catalytic sites.This is the first time that a detailed step-by-step mechanism at the atomic level has been proposed for this electrocatalytic reaction,which represents a valuable contribution to the understanding of this process of high energy/environmental interest.This is also the first time that black TiO_(2)has been used as an electrocatalyst for this sustainable process.
基金the financial support for this study by PAPIIT-UNAM grant(IN222817)to LAS-Gthe Fran?ois Vuilleumier Fund for Neotropical Bird Research from the Neotropical Ornithological Society(NOS)awarded to OJE-C。
文摘Due to a complex geological and biotic history,the Isthmus of Tehuantepec(IT),has been long recognized as a driver for the evolutionary divergence of numerous lowland and highland taxa.Widely distributed in the lowlands of the American continent,the White-Tipped Dove(Leptotila verreauxi)is a polytypic species with 13 recognized subspecies.Four of these have been recorded in Mexico,and the distribution of three abuts at the IT,suggesting a contact zone.To estimate phylogenetic patterns,divergence times and genetic differentiation,we examined two mt DNA(ND2 and COI)and one n DNA(β-fibint 7)markers.We also used correlative ecological niche models(ENM)to assess whether ecological differences across the IT may have acted as a biogeographical boundary.We estimated paleodistributions during the Middle Holocene,Last Glacial Maximum and Last Interglacial,to evaluate the influence of climate changes on the distribution and demographic changes.Our results showed genetically distinct lineages that diverged approximately 2.5 million years ago.Climatic and ecological factors may have played a dual role in promoting differentiation,but also in the formation of a secondary contact zone in the southern IT.Our ecological niche comparisons indicated that the ecological niche of sympatric lineages at the IT are not identical,suggesting niches divergence;in addition,environmental niche models across the region indicated no abrupt biogeographic barriers,but the presence of regions with low suitability.These results suggest that genetic differentiation originated by a vicariant event probably related to environmental factors,favored the evolution of different ecological niches.Also,the absence of a biogeographic barrier but the presence of less suitable areas in the contact regions,suggest that secondary contact zones may be also maintained by climatic factors for the eastern group,but also by biotic interactions for the western group.
基金support of the CONACYTFORDECYT-PRONACES/6364/2020 projectthe funding granted by SIP projects 20181094 and 20196679。
文摘The present study aimed to evaluate multi-element concentrations(Al,As,Ca,Cd,Co,Cr,Cu,Fe,Mg,Mn,Mo,Ni,Pb,Sr)in suspended particulate material(SPM)collected from Ensenada de La Paz(ELP)lagoon,Baja California Sur,Mexico in two different periods(September and May)to comprehend their origin,geochemical behavior,mass transfer and associated ecotoxicological risks.The 24 hr variation coefficient of volumetric SPM levels were found to be 51.7%in September and 40.5%in May,signifying the effects of oceanic waters.The calculated enrichment factor(EF)values for all the studied elements were of higher magnitude because of the high surface area and oxide nature of SPM,and in this study,Mo had the highest EF of 46.77 probably due to its origin from continental weathering.From the ecotoxicological perspective,the integrated toxic risk index revealed low toxic risk to the benthic community.However,the mean-ERM-Quotient calculated using the particulate concentrations of As,Cd,Cr,Cu,Ni,Pb indicated 9%probability of toxicity to biota.The comprehensive geochemical and ecotoxicological assessment of particulate metal concentrations in the ELP lagoon signify low to moderate contamination.
文摘The forest industry operates in a dynamic and global market where change and competition are the rule rather than the exception. The color of wood is one of the most attractive features for the modem wood industry. Even when wood is chosen for its structural qualities, attractive and decorative colors are usually an important factor. In many applications, particularly in furniture, decorative products, decorative veneers and flooring, accurate matching of the color of different samples is required. Wood attributes and properties are important because they have a direct bearing on market opportunities and consumer acceptance for many types of manufactured wood products. The aim of this review is to identify causes of wood discoloration and advances in drying technology to overcome this problem. Wood discoloration is a complex phenomenon, mainly affected by heat, light, physiological and biochemical reactions, as well as from attack by microorganisms.
文摘Background: Liver recurrence after resection of colorectal liver metastases(CRLM) is frequent. Repeat hepatectomy has been shown to have satisfactory perioperative results. However, the long-term outcomes and the benefts for patients with early recurrence have not been clarifed. The aim of this study was to compare the short-and long-term outcomes of patients undergoing single hepatectomy and repeat hepatectomy for CRLM. Additionally, the oncological outcomes of patients with early( ≤ 6 months) and late recurrence who underwent repeat hepatectomy were compared. Methods: Consecutive adult patients undergoing hepatectomy for CRLM between June 20 0 0 and February 2020 were included and divided into two groups: single hepatectomy and repeat hepatectomy. Results: A total of 709 patients were included: 649 in the single hepatectomy group and 60 in the repeat hepatectomy group. Patients in the repeat hepatectomy group underwent more cycles of preoperative chemotherapy [4(3-6) vs. 3(2-4), P = 0.003]. Patients in the single hepatectomy group more frequently underwent major hepatectomies(34.5% vs. 16.7%, P = 0.004) and had a greater number of lesions resected(2.9 ± 3.6 vs. 1.9 ± 1.8, P = 0.011). There was no increase in operative time, estimated blood loss, length of hospital stay, complications, or mortality in the repeat hepatectomy group. There were no differences in overall survival( P = 0.626) and disease-free survival( P = 0.579) between the two groups. Similarly, for patients underwent repeat hepatectomy, no difference was observed between the early and late recurrence groups in terms of overall survival( P = 0.771) or disease-free survival( P = 0.350). Conclusions: Repeat hepatectomy is feasible and safe, with similar short-and long-term outcomes when compared to single hepatectomy. Surgical treatment of early liver recurrence offers similar oncological outcomes to those obtained for late recurrence.
文摘Colletotrichum gloeosporioides is the causal agent of anthracnose disease in fruits and vegetables, representing a global problem. The use of biocontrol agents has proved effective against fungal diseases in a wide variety of products. In this work, the antifungal activity of Wickerhamomyces anomalus against C. gloeosporioides isolated from contaminated avocados was evaluated. The antagonism and volatile compound inhibition were measured on Petri dishes. In the mixed cultures, the mycelia damage was observed by scanning electron microscope （SEM）. Chitinase and glucanase production by the antagonism was quantified by the reducing sugars method, and biofilm formation was evaluated with 1% crystal violet. The yeast W. anomalus could reduce the growth of C. gloeosporioides up to 65% by direct antagonism and 10% by volatile compounds. The antagonist did not allow the conidia germination and mycelia growth in any of the tested formulations. SEM showed mycelial damage caused by W. anomalus. The antagonist showed adhesion to the mycelium by a polysaccharide biofilm. The presence of mycelium stimulated the hydrolytic enzyme production with the maximal activity of 21.4 U/mg for chitinases at 24 h and 10 U/mg for glucanases at 60 h. These results showed that W. anomalus used together different mechanisms to express its antifungal activity against C. gloeosporioides. This study might be the first report for this phytopathogen isolated from avocado fruits, which could represent an opportunity to establish biocontrol of diseases for this agricultural product.
文摘The Late Pleistocene littoral ridges of southern South America,especially those of the north of Argentinean Patagonia,contain remains of mollusk shells with bioerosion traces.Eleven sites from marine isotope stages(2 from MIS 7,4 from MIS 5 e)and five sites from modern beaches from northern Río Negro Province,with 40 taxa(17 bivalves and 23 gastropods)were analyzed,in the area between west of Baliza San Matías and Las Grutas(41°S).Three ichnogenera were identified in deposits of MIS 7:Entobia,Gastrochaenolites(Domichnia)and Oichnus(Praedichnia)with one ichnospecies(G.torpedo).Six ichnogenera were identified in deposits of MIS 5 e:Entobia,Meandropolydora,Pinaceocladichnus,Iramena,Caulostrepsis and Oichnus with one ichnospecies(O.simplex).Seven ichnogenera were identified from modern beaches:Entobia,Meandropolydora,Iramena,Caulostrepsis,Pinaceocladichnus,Gastrochaenolites(Domichnia)and Oichnus(Praedicnia),with two ichnospecies(O.simplex and O.paraboloides).On this basis,it is inferred that Pleistocene benthic communities were constituted from cheilostome bryzoans and polychaete annelids,together with drilling bivalves,predatory gastropods and overall warm-water species of mollusks.Of these,Chama iudicai was found on Plicatula gibbosa from MIS 7 and MIS 5 e.The record of warm temperature species suggests a higher sea surface temperature(SST)than the present one and/or the influence of the warm southward Brazilian Current affecting the waters of Golfo San Matías.On the modern beaches surveyed,there is an increase in polychaete annelids,cheilostome bryzoans,temperate-cold species and drilling bivalves,as well as sandy substrate species,which together with an increase of Gastrochaenolites and Caulostrepsis,suggest a colder climate due to the greater influence of the Malvinas Current during the Holocene.
文摘Objective:To ascertain the antibiotic susceptibility patterns of Escherichia coli recovered from blood culture specimens in Calabar.Nigeria.Methods:The study was retrospective in nature and was carried out at University of Calabar Teaching Hospital(UCTH) Calabar.Data generated from blood culture specimens over a five year period(Feb.2004-Feb.2009) was compiled, relevant information such as age,sex,organism recovered and antibiotic susceptibility patterns were obtained from patients records.Samples were collected,transported,stored and processed using standard laboratory procedures.Data obtained was analysed using Epi Info 6 statistical software.Results:Escherichia coli was responsible for 15.3%(31/203) of the blood infections being the third most common microorganism encountered.The community acquired(CA) isolates of the organism were significantly less resistant(P【0.05),compared to the nosocomial(NC) isolates against ampicillin.cloxacillin,amoxicillin,tetracycline,co-trimoxazole.chloramphenicol and erythromycin.The sensitivity of both the NC and CA isolates of Escherichia coli to amikacin, augmentin,ofloxacin,ciprofloxacin,ceftazidime,cefuroxime,ceftriaxone and rifampicin was generally high(80-100%) with no significant difference(P】0.05).Majority(】95.0%) of the NC isolates of Escherichia coli were resistant to six of the antibiotics tested.Conclusions:Control mechanisms for hospital acquired infections should be stepped up so as lo limit the spread of the highly resistant bacterial strains.Also the sale and consumption of antibiotics by the public need to be regulated.
文摘The purpose of this study was to analyzed the outcome in patients with acute obstruction of the left colonrectal cancer who was treated by double tube intraoperative levage methods.Methods Between 1999 and 2003,62 patients with acute obstruction for cancer underwent surgery.The patients were divided into two groups at random,31 patients were treated with double tube intraoperative lavage,resection,and primary anastomosis.31 patients were treated with traditional resection,and after 1～2 month,Ⅱ stage anastomosis.Results In double tube intraoperative lavage,No case occurred anastomotic leakage.The patients got a satisfactory recovery post-operatively.Conclusion It was concluded that one-satge emergency surgery for left obstrucing colonic cancers is safe with the regard of double tube intraoperative lavage methods.6 refs,1 tab.
文摘Objective To study microsurgical effectiveness Foerster-Dandy’s endoscope-assisted operation for treatment of spasmodic torticollis. Methods 183 cases of spasmodic torticollis patients were treated by microsurgical modified Foerster-Dandy’s operation from July 2001 to June 2009,which was randomly
文摘Objective To study the mechanism of myocardial dielectric property changes in radio frequency during hypothermic preservation and explore myocardial viability evaluative method. Methods Hybrid young pigs ( 20 - 30 kg) were used in the experiment. Heart arrest was in-
文摘Objective To investigate the role of endothelin(ET) in the proliferation and collagen synthesis of human scar-derived fibroblasts and the moduktion of its antagonists such as nitric oxide(NO), tetrandrine ( Tet). Methods With the cultured fibroblasts from the scarring tissue, the cell pdiferation was determined by[3H]-TdR incorporation, while the collagen synthesis was evaluated by[3H]-proline incorporation. Results The ET-1 was significantly increasing the proliferation and collagen synthesis of human scar-derived fibroblasts. The values of [3H]-TdR absorption in the 2.5 ng/ml,25 ng/ml and 100 ng/ml of ET-1 groups were 1.8 times,4 times and 4.9 times more than in the control group, respectively(P【0. 01),while the values of the [3H]-proline incorporation were 1.1 times,3.1 times and 3.8 times respectively(P【0.01). The fibroblasts, treated with 50 μg/ml of S-nitroso-N-acetyl penicillamine(SNAP), were no detectable effect on the basal level of DNA synthesis,but produced decreasing effect on the
文摘Compare the effects of locomotion therapy and pelvis traction therapy to treat Ⅰ～Ⅱ° thoracolumbar compression fracture.Methods Ninety-two cases with Ⅰ～Ⅱ° thoracolumbar compression fracture were selected and divided into 2 groups with locomotion therapy and pelvis traction thepapy respectively.Results Thoracolumbar height was measured according to X-ray results after 1 year follow-up.The height was (17.2±2.3)mm preoperatively and (24.4±3.1)mm postoperatively in locomotion therapy group while (16.8±2.6)mm preoperatively and (23.9±2.7)mm postoperatively in the pelvis traction therapy group.Conclusion There is no significant difference between effects on two groups.5 refs.
文摘To explore the influence of aprotinin on the mRNA expression of P-selectin and ICAM-1 in lung tissue after ischemic reperfusion.Methods Thirty New Zealand white rabbits were randomly divided into 3 groups:control group,LPD group and aprotinin group.In situ rabbit lung preservation model was established.In control group,the left lower lung lobe was stored at 10℃ in a specially made lung preservation container for 2 hours and reperfused for another 2 hours.In LPD group and aprotinin group,the left lower lobe was perfused with LPD solution or aprotinin containing LPD solution,respectively,after left lung hilus was clamped.The other procedures were the same as those in control group.The lung tissue was harvested at different time intervals including preclamping lung hilus,2 hours after clamping and 2 hours after reperfusion.The mRNA expression of ICAM-1 and P-selectin in the lung tissue was detected with RT-PCR technique.Results The contents of mRNA of P-selectin at 2 hours after reperfusion in control group and LPD group were significant higher than pre-ischemia and 2 hours after champing the left lung hilus.There was no such significant difference in aprotinin group.The mRNA expression of P-selectin in aprotinin group at 2 hours after reperfusion was significantly lower than that in control group and LPD group.The ICAM-1 mRNA expression at 2 hours after Ischemia and 2 hours after reperfusion in control group and LPD group was significantly higher than the pre-ischemia and its was significantly higher than that in aprotinin group.Conclusion Aprotinin can inhibit the upregulation of the mRNA expression of P selectin and ICAM-1 after ischemia reperfusion in the lung tissue,so the addition of aprotinin in LPD solution may reduce the ischemia reperfusion injury in lung tissue.5 refs,1 tab.
基金financially supported by the Mexican Center of Innovation in Solar Energy-CeMIE-Sol(No.P-55)。
文摘This research presents the influence of copper(Cu) concentration on the properties of copper zinc tin sulfide(CZTS) nanoparticles(NPs) synthesized by a colloidal method, employing oleylamine as an organic solvent. From the structural analysis, a pure phase of CZTS was obtained at an optimized molar ratio of 1.8:1.1:1:4,and secondary phases were observed as the Cu concentration increased. The increment of the NPs size from 15 to50 nm was noticed as a function of Cu concentration.Importantly, the optical bandgap energy was tuned from1.35 to 1.68 eV with respect to Cu concentration. The sample synthesized at the molar ratio of 1.8:1.1:1:4 showed a pure phase CZTS with desired elemental composition and bandgap. Furthermore, CZTS thin films were prepared by a doctor-blade method using synthesized NPs followed by annealing under a sulfur/nitrogen atmosphere. The annealed CZTS film showed a significant improvement in the morphological, electrical and optoelectronic properties.Thus, the annealed CZTS film can be efficiently used as an absorber layer in low-cost thin film solar cells.
文摘Objective To summarize the experience of management in the living related small bowel transplantation for One patient with short gut syndrome and resection of right colon with complication of ileus-colon anastomosis fistulas. Methods One patient with almost all small bowel and right colon reseeted for embolism of superior mesenteric artery underwent the living related small bowel transplantation.
文摘Mayamontana coccolobae Castellano,Trappe and Lodge is described for the first time from Mexico and the second time worldwide.It is characterized by the orange,subhypogeous basidiomata and the wrinkled subglobose spores with conspicuous hilar appendix.It is not a very common species in the region and is recorded from disturbed lowland forest and urban gardens.Mayamontana coccolobae was only known from the type locality but now extends its geographical distribution to southeast Mexico.
基金the Universidad Politecnica de Tapachula(UPTap)and Centro de Investigaciones Químicas,Universidad Autonoma del Estado de Morelos for all facilities granted to carry out this work.The first author Lopez-Velazquez(CVU 736037)thanks the Consejo Nacional de HumanidadesCiencias y Tecnologías(CONAHCYT)and the program Estancias Posdoctorales por Mexico-Continuidad 2022(1)for the funding granted.We also thank Kevin G.Duque Olivera for his support during the sampling seasons.
文摘The occurrence of seven endocrine-disrupting compounds(EDCs)in four urban rivers on the southern border of Mexico was studied in this work.The selected EDCs were 17b-estradiol(E2),estriol(E3),17aethinylestradiol(EE2),bisphenol A(BPA),bisphenol F(BPF),4-nonylphenol(4NP)and 4-tert-octylphenol(4TOP).Water samples from the Coatan,Texcuyuapan,Cahoacan,and Coatancito rivers were collected at three different sites on each river and processed by solid phase extraction(SPE).The samples were analyzed by gas chromatography triple quadrupole tandem mass spectrometry(GC-MS/MS)and compounds of interest were identified by dynamic mass reaction monitoring mode(dMRM).Among the target EDCs,E2,BPA,and 4NP were detected in all water samples,with BPA being the most abundant ranging from 4.22 up to 127.96 ng/L.Correlation tests showed significant positive associations between estrogens and BPA,as well as the correlation between alkylphenols and BPA,suggesting common origin emission sources,which were identified as discharges of untreated municipal wastewater.Finally,the estimation of RQ and EEQ values indicated that the presence of E2,E3,EE2,and BPA in all sampled points represents a high risk for aquatic life in these sites,mainly for Texcuyuapan River,where the aquatic organisms may be susceptible to endocrine disruption by chronic exposure to detected compounds.
文摘This study reports radiological deformities in the vertebral column of six fishes viz,Scomberomorus commerson,Chanos chanos,Sillago sihama,Pampus chinensis,Rastrelliger kanagurta and Netuma thalassina that were collected from the Coromandel coast,Bay of Bengal.Four main different types of vertebral column deformities were found:(i)whole body kypho-lordo-kyphosis(Sillago sihama,Rastrelliger kanagurta,Netuma thalassina);(ii)tail region kypho-lordosis(Scomberomorus commerson);(iii)tail region lordo-kyphosis(Chanos chanos);(iv)platyspondyly(Pampus chinensis).Seven types of vertebra body deformities,describing the pathology of single vertebrae,were present;reduced intervertebral space,compression,fusion,compresion&fusion,fusion center,dorsal wedge-shaped and compressed&dorsal wed-shaped.The present documentation of deformities in six different species that are also very different with regard to habitat,diet and swimming activity may suggest that fish deformities are widespread in the study area.
