Objective:The objective of the study is to describe the work-related quality of life(WRQOL)among nurses and explore its association with performance evaluation ratings.Methods:A cross-sectional design was utilized mea...Objective:The objective of the study is to describe the work-related quality of life(WRQOL)among nurses and explore its association with performance evaluation ratings.Methods:A cross-sectional design was utilized measuring the WRQOL scale and the previous performance appraisal rating.Multistage sampling approach was utilized with nurses stratified based on their position and then systematically random sampled based on their unit assignment.Results:One hundred and eighty-two nurses were included.About half reported a high quality of work life(101;55.5%).Low scores were noted on the subscale working conditions(100;54.9%),low to average responses for home-work interface(109;59.9%),control at work(100;54.9%),and stress at work(90;49.5%).A higher proportion of nurses reported positive responses toward the areas of general well-being(113;62.1%)and job-career satisfaction(112;61.5%),than in the other subscales.There were notable differences between WRQOL ratings:(1)Head nurses had the highest perceived quality of work life,followed by nurse supervisors and charge nurses(F=6.1,P<0.01)and(2)Nurses in the pay-patient services reported lower quality of working life,while those in office and outpatient services had more positive scores(F=4.6,P<0.01).Conclusion:Only more than half of the nurses reported a high quality of work life,some of its dimensions,particularly job and career satisfaction and working conditions,appeared to vary in the perceived degree across years in service,work hours,and position.The assessment of the quality of work life may serve as an important tool to address staff burnout,absenteeism and other issues that affect job performance among health-care professionals.展开更多
Coastal vulnerability assessment using the Integrated Sensitivity, Exposure, and Adaptive Capacity to Climate Change Vulnerability Assessment (ICSEA-C-Change) tool provides a deeper understanding of the potential impa...Coastal vulnerability assessment using the Integrated Sensitivity, Exposure, and Adaptive Capacity to Climate Change Vulnerability Assessment (ICSEA-C-Change) tool provides a deeper understanding of the potential impacts of climate change on coastal zones. Vulnerability ratings were obtained using rubrics that were presented to the stakeholders during focused group discussions. Derived scores were then averaged and consolidated to come up with the overall vulnerability rating. These ratings were based on the resource and status of coastal habitats’ reliance on near-shore fishing and other quality measures like fisheries ecosystem dependency, population, and water quality of the coastal habitats in the barangays. Ratings resulted in identifying 12 barangays out of 23 that are highly vulnerable to climate change impacts such as waves, storm surges, sea level rise, increase in surface temperature, and extreme rainfall. These are Buenavista and Basicao (Pioduran), Catburawan (Ligao), Tapel, Nagas and Maramba (Oas), Talin-Talin, Pantao, Macabugos, and Tambo (Libon) and Buhatan and Villa Hermosa (Rapu-Rapu). Assessment results were highly influenced by the absence of three major marine habitats, i.e., coral reefs, seagrass/seaweeds, and mangroves in the coastal areas. Likewise, 11 barangays out of 23, which were Marigondon and Malidong (Pioduran), Maonon and Cabarian (Ligao), Badian and Cagmanaba (Oas), Apud and Rawis (Libon), and Galicia, Hamorawon, and Poblacion (Rapu-Rapu) obtained moderate vulnerability scores. This was attributed to the presence of marine habitats that although in poor state, may serve their ecological functioning when properly protected. Highly vulnerable barangays must be prioritized in coastal rehabilitation and disaster risk reduction management planning. Parameters encompassing the sensitivity and adaptive capacity of each barangay must be taken into consideration to reduce potential impacts brought by factors attributed to climate change. Vital information from the assessment will serve as basis for developing strategic plans for improving the climate change adaptation strategies of the local government units.展开更多
The study explores the yearnings of fisherfolks on their child’s education, hindrances, and factors that shape their desire as parents. Field observations and key informant interview among elder members of fisherfolk...The study explores the yearnings of fisherfolks on their child’s education, hindrances, and factors that shape their desire as parents. Field observations and key informant interview among elder members of fisherfolk communities surrounding the Albay, Ragay, and Asid Gulfs of the Bicol Region was utilized. The study revealed that the majority of the fisherfolk parents do not want their children to continue fishing as their main source of livelihood because of potential risks, hardships, and cultural factors like collectivism, close family ties, and dependence on the elders. The parents’ aspirations were shaped by their persistence over various threats, fears, personal unfulfilled dreams, and career opportunities thru education. Most of the parents desired a college education and a safe and secure profession for their children. The study deduced that these challenges can be a contributory factor for the declining number of fisherfolks surrounding the gulfs. Influencing this sector is the factor motivating fishers in their aspirations for their children’s education. The study recommends introducing strategies for fisherfolks to develop a strong sense of hope and drive in realizing their aspirations and further research on the impact of culture, the role of women and children, and fisherfolks and their success stories.展开更多
Enteral nutrition has been strongly recommended by major scientific societies for the nutritional management of patients with acute pancreatitis.Providing severe acute pancreatitis patients with enteral nutrition with...Enteral nutrition has been strongly recommended by major scientific societies for the nutritional management of patients with acute pancreatitis.Providing severe acute pancreatitis patients with enteral nutrition within the first 24-48 h of hospital admission can help improve outcomes compared to parenteral nutrition and no feeding.New research is focusing in on when and what to feed to best improve outcomes for acute pancreatitis patients.Early enteral nutrition have the potential to modulate the immune responses.Despite this consistent evidence of early enteral nutrition in patients with acute pancreatitis,clinical practice continues to vary due to individual clinician preference.Achieving the immune modulating effects of enteral nutrition heavily depend on proper placement of the feeding tube and managing any tube feeding associated complications.The current article reviews the immune modulating effects of enteral nutrition and pro-and prebiotics and suggests some practical tools that help improve the patient adherence and tolerance to the tube feeding.Proper selection of the type of the tube,close monitoring of the tube for its placement,patency and securing its proper placement and routine checking the gastric residual volume could all help improve the outcome.Using peptide-based and high medium chaintriglycerides feeding formulas help improving feeding tolerance.展开更多
Recent years have witnessed growing interest in the role of peptides in animal nutrition. Chemical, enzymatic, or microbial hydrolysis of proteins in animal by-products or plant-source feedstuffs before feeding is an ...Recent years have witnessed growing interest in the role of peptides in animal nutrition. Chemical, enzymatic, or microbial hydrolysis of proteins in animal by-products or plant-source feedstuffs before feeding is an attractive means of generating high-quality small or large peptides that have both nutritional and physiological or regulatory functions in livestock, poultry and fish. These peptides may also be formed from ingested proteins in the gastrointestinal tract, but the types of resultant peptides can vary greatly with the physiological conditions of the animals and the composition of the diets. In the small intestine, large peptides are hydrolyzed to small peptides,which are absorbed into enterocytes faster than free amino acids(AAs) to provide a more balanced pattern of AAs in the blood circulation. Some peptides of plant or animal sources also have antimicrobial, antioxidant,antihypertensive, and immunomodulatory activities. Those peptides which confer biological functions beyond their nutritional value are called bioactive peptides. They are usually 2–20 AA residues in length but may consist of >20AA residues. Inclusion of some(e.g. 2–8%) animal-protein hydrolysates(e.g., porcine intestine, porcine mucosa,salmon viscera, or poultry tissue hydrolysates) or soybean protein hydrolysates in practical corn-and soybean mealbased diets can ensure desirable rates of growth performance and feed efficiency in weanling pigs, young calves,post-hatching poultry, and fish. Thus, protein hydrolysates hold promise in optimizing the nutrition of domestic and companion animals, as well as their health(particularly gut health) and well-being.展开更多
Area Sampling Frames(ASFs) are the basis of many statistical programs around the world. To improve the accuracy,objectivity and efficiency of crop survey estimates,an automated stratification method based on geospatia...Area Sampling Frames(ASFs) are the basis of many statistical programs around the world. To improve the accuracy,objectivity and efficiency of crop survey estimates,an automated stratification method based on geospatial crop planting frequency and cultivation data is proposed. This paper investigates using 2008–2013 geospatial corn,soybean and wheat planting frequency data layers to create three corresponding single crop specific and one multi-crop specific South Dakota(SD) U.S. ASF stratifications. Corn,soybeans and wheat are three major crops in South Dakota. The crop specific ASF stratifications are developed based on crop frequency statistics derived at the primary sampling unit(PSU) level based on the Crop Frequency Data Layers. The SD corn,soybean and wheat mean planting frequency strata of the single crop stratifications are substratified by percent cultivation based on the 2013 Cultivation Layer. The three newly derived ASF stratifications provide more crop specific information when compared to the current National Agricultural Statistics Service(NASS) ASF based on percent cultivation alone. Further,a multi-crop stratification is developed based on the individual corn,soybean and wheat planting frequency data layers. It is observed that all four crop frequency based ASF stratifications consistently predict corn,soybean and wheat planting patterns well as verified by the 2014 Farm Service Agency(FSA) Common Land Unit(CLU) and 578 administrative data. This demonstrates that the new stratifications based on crop planting frequency and cultivation are crop type independent and applicable to all major crops. Further,these results indicate that the new crop specific ASF stratifications have great potential to improve ASF accuracy,efficiency and crop estimates.展开更多
Artificial neural network is a new approach to pattern recognition and classification. The model of multilayer perceptron (MLP) and back-propagation (BP) is used to train the algorithm in the artificial neural network...Artificial neural network is a new approach to pattern recognition and classification. The model of multilayer perceptron (MLP) and back-propagation (BP) is used to train the algorithm in the artificial neural network. An improved fast algorithm of the BP network was presented, which adopts a singular value decomposition (SVD) and a generalized inverse matrix. It not only increases the speed of network learning but also achieves a satisfying precision. The simulation and experiment results show the effect of improvement of BP algorithm on the classification of the surface defects of steel plate.展开更多
AIM: To investigate the effects of broccoli sprout extract(BSEx) on liver gene expression and acute liver injury in the rat.METHODS: First, the effects of BSEx on liver gene expression were examined. Male rats were di...AIM: To investigate the effects of broccoli sprout extract(BSEx) on liver gene expression and acute liver injury in the rat.METHODS: First, the effects of BSEx on liver gene expression were examined. Male rats were divided into two groups. The Control group was fed the AIN-76 diet, and the BSEx group was fed the AIN-76 diet containing BSEx. After a 10-d feeding period, rats were sacrificed and their livers were used for DNA microarray and realtime reverse transcription-polymerase chain reaction(RT-PCR) analyses. Next, the effects of BSEx on acute liver injury were examined. In experiments using acute liver injury models, 1000 mg/kg acetaminophen(APAP) or 350 mg/kg D-galactosamine(D-Gal N) was used to induce injury. These male rats were divided into four groups: Control, BSEx, Inducer(APAP or D-Gal N), and Inducer+BSEx. The feeding regimens were identical for the two analyses. Twenty-four hours following APAP administration via p.o. or D-Gal N administration via i.p., rats were sacrificed to determine serum aspartate transaminase(AST) and alanine transaminase(ALT) levels, hepatic glutathione(GSH) and thiobarbituric acid-reactive substances accumulation and glutathioneS-transferase(GST) activity. RESULTS: Microarray and real-time RT-PCR analyses revealed that BSEx upregulated the expression of genes related to detoxification and glutathione synthesis in normal rat liver. The levels of AST(70.91 ± 15.74 IU/m L vs 5614.41 ± 1997.83 IU/m L, P < 0.05) and ALT(11.78 ± 2.08 IU/m L vs 1297.71 ± 447.33 IU/m L, P < 0.05) were significantly suppressed in the APAP + BSEx group compared with the APAP group. The level of GSH(2.61 ± 0.75 nmol/g tissue vs 1.66 ± 0.59 nmol/g tissue, P < 0.05) and liver GST activity(93.19 ± 16.55 U/g tissue vs 51.90 ± 16.85 U/g tissue, P < 0.05) were significantly increased in the APAP + BSEx group compared with the APAP group. AST(4820.05 ± 3094.93 IU/m L vs 12465.63 ± 3223.97 IU/m L, P < 0.05) and ALT(1808.95 ± 1014.04 IU/m L vs 3936.46 ± 777.52 IU/m L, P < 0.05) levels were significantly suppressed in the D-Gal N + BSEx group compared with the D-Gal N group, but the levels of AST and ALT in the D-Gal N + BSEx group were higher than those in the APAP + BSEx group. The level of GST activity was significantly increased in the D-Gal N + BSEx group compared with the D-Gal N group(98.04 ± 15.75 U/g tissue vs 53.15 ± 8.14 U/g tissue, P < 0.05).CONCLUSION: We demonstrated that BSEx protected the liver from various types of xenobiotic substances through induction of detoxification enzymes and glutathione synthesis.展开更多
Embryonic stem(ES) cells are isolated from theinner cell mass of a blastocyst, and are used for the generation of gene-modified animals. In mice, the transplantation of gene-modified ES cells into recipient blastocyst...Embryonic stem(ES) cells are isolated from theinner cell mass of a blastocyst, and are used for the generation of gene-modified animals. In mice, the transplantation of gene-modified ES cells into recipient blastocysts leads to the creation of gene-targeted mice such as knock-in and knock-out mice; these gene-targeted mice contribute greatly to scientific development. Although the rat is considered a useful laboratory animal alongside the mouse, fewer genemodified rats have been produced due to the lack of robust establishment methods for rat ES cells. A new method for establishing rat ES cells using signaling inhibitors was reported in 2008. By considering the characteristics of rat ES cells, recent research has made progress in improving conditions for the stable culture of rat ES cells in order to generate gene-modified rats efficiently. In this review, we summarize several advanced methods to maintain rat ES cells and generate gene-targeted rats.展开更多
The present study initially investigates the kinetics of microwave-assisted grinding and flotation in a porphyry copper deposit.Kinetic tests were conducted on untreated and microwave-irradiated samples by varying the...The present study initially investigates the kinetics of microwave-assisted grinding and flotation in a porphyry copper deposit.Kinetic tests were conducted on untreated and microwave-irradiated samples by varying the exposure time from 15 to 150 s.Optical microscopy,energy-dispersive X-ray spectroscopy,and scanning electron microscopy were conducted to determine the mineral liberation and particle surface properties,and to perform mineralogical analyses.Results showed that the ore breakage rate constant monotonically increased by increasing the exposure time,particularly for the coarsest fraction size(400μm)due to the creation of thermal stress fractures alongside grain boundaries.Excessive irradiation time(>60 s)led to the creation of oxidized and porous surfaces along with a dramatic change in particle morphologies that result in a substantial reduction of chalcopyrite and pyrite flotation rate constants and ultimate recoveries.We concluded that MW-pretreated copper ore was ground faster than the untreated variety,but the two types have slightly similar floatabilities.展开更多
The Linz-Donawitz(LD) steelmaking process produces LD slag at a rate of about 125 kg/t. After metallic scrap recovery, the non-metallic LD slag is rejected because its physical/chemical properties are unsuitable for r...The Linz-Donawitz(LD) steelmaking process produces LD slag at a rate of about 125 kg/t. After metallic scrap recovery, the non-metallic LD slag is rejected because its physical/chemical properties are unsuitable for recycling. X-ray diffraction(XRD) studies have indicated that non-metallic LD slag contains a substantial quantity of mineral phases such as di- and tricalcium silicates. The availability of these mineral phases indicates that LD slag can be recycled by iron(Fe)-ore sintering. However, the presence of 1.2wt% phosphorus(P) in the slag renders the material unsuitable for sintering operations. Electron probe microscopic analysis(EPMA) studies indicated concentration of phosphorus in dicalcium silicate phase as calcium phosphate. The Fe-bearing phases(i.e., wustite and dicalcium ferrite) showed comparatively lower concentrations of P compared with other phases in the slag. Attempts were made to lower the P content of LD slag by adopting various beneficiation techniques. Dry high-intensity magnetic separation and jigging were performed on as-received samples with particle sizes of 6 and 3 mm. Spiral separation was conducted using samples ground to sizes of less than 1 and 0.5 mm. Among these studies, grinding to 0.5 mm followed by spiral concentration demonstrated the best results, yielding a concentrate with about 0.75wt% P and 45wt% Fe.展开更多
This paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors(CFs)in several neutron standard fields(i.e.,two standard fields with bare sources of252Cf and241Am-Be,and ...This paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors(CFs)in several neutron standard fields(i.e.,two standard fields with bare sources of252Cf and241Am-Be,and five simulated workplace fields with241Am-Be moderated sources).The calibration in standard fields with bare sources was conducted by following the recommendations of the ISO 8529 standard.The measured total neutron ambient dose equivalent rates,denoted as H*(10)tot,were analyzed to obtain direct components,denoted as H*(10)dir,using a reduced fitting method.The CF was then calculated as the ratio between the conventional true value of the neutron ambient dose equivalent rate in a free field,denoted as H*(10)FF,and the value of H*(10)dir.In contrast,in the simulated workplace neutron fields,the calibration of the neutron dose rate meter was conducted by following the ISO 12789 standard.The CF was calculated as the ratio between the values of H*(10)totmeasured by a standard instrument(i.e.,Bonner sphere spectrometer)and the neutron dose rate meter.The CF values were obtained in the range of 0.88–1.0.The standard uncertainties(k=1)of the CFs were determined to be in the range of approximately 6.6–13.1%.展开更多
Pueraria flower extract (PFE) is a hot water extract of the Kudzu flower (Pueraria thomsonii). Tea made from dried Kudzu flower is widely used inChina, and PFE is utilized as a nutritional supplement inJapan. PFE cont...Pueraria flower extract (PFE) is a hot water extract of the Kudzu flower (Pueraria thomsonii). Tea made from dried Kudzu flower is widely used inChina, and PFE is utilized as a nutritional supplement inJapan. PFE contains unique isoflavones such as 6-hydroxygenistein 6,7-di-O-glucoside (6HGDG), tectorigenin 7-O-xylosylglucoside (TGXG), and tectoridin. 6HGDG is known to be metabolized into 6-hydroxygenistein, and TGXG and tectoridin are known to be metabolized into tectorigenin in the digestive tract. Isoflavones typically mimic the effects β-estradiol has on estrogen receptors (ERs) and may influence the female genital system in the case of excessive intake. As a result, the upper limit of safe daily consumption of soy isoflavones has been enforced inJapan. In the present study, ER-binding assays were performed using the EnBio estrogen receptor/cofactor assay system to compare the estrogenic activity of 6-hydroxygenistein and tectorigenin to that of the soy isoflavone genistein. In addition, uterotrophic bioassays were performed to investigate the estrogenic effects of PFE in vivo. The ER-binding assays revealed that the ER-binding affinities of 6-hydroxygenistein and tectorigenin were approximately 0.01 - 0.04 that of genistein. Soy isoflavone products also induced an increase in uterine wet and blotted weight at doses of 500 mg/kg and 1000 mg/kg, whereas PFE did not cause adverse estrogenic effects, even at a dose of 1000 mg/kg. Based on these results, PFE does not appear to contain compounds with strong estrogenic activity or cause adverse estrogenic effects in vivo. Importantly, the results of this study confirm the safety of PFE as a food supplement.展开更多
The Dynamical-Statistical-Analog Ensemble Forecast model for landfalling tropical cyclones(TCs)precipitation(DSAEF_LTP)utilises an operational numerical weather prediction(NWP)model for the forecast track,while the pr...The Dynamical-Statistical-Analog Ensemble Forecast model for landfalling tropical cyclones(TCs)precipitation(DSAEF_LTP)utilises an operational numerical weather prediction(NWP)model for the forecast track,while the precipitation forecast is obtained by finding analog cyclones,and making a precipitation forecast from an ensemble of the analogs.This study addresses TCs that occurred from 2004 to 2019 in Southeast China with 47 TCs as training samples and 18 TCs for independent forecast experiments.Experiments use four model versions.The control experiment DSAEF_LTP_1 includes three factors including TC track,landfall season,and TC intensity to determine analogs.Versions DSAEF_LTP_2,DSAEF_LTP_3,and DSAEF_LTP_4 respectively integrate improved similarity region,improved ensemble method,and improvements in both parameters.Results show that the DSAEF_LTP model with new values of similarity region and ensemble method(DSAEF_LTP_4)performs best in the simulation experiment,while the DSAEF_LTP model with new values only of ensemble method(DSAEF_LTP_3)performs best in the forecast experiment.The reason for the difference between simulation(training sample)and forecast(independent sample)may be that the proportion of TC with typical tracks(southeast to northwest movement or landfall over Southeast China)has changed significantly between samples.Forecast performance is compared with that of three global dynamical models(ECMWF,GRAPES,and GFS)and a regional dynamical model(SMS-WARMS).The DSAEF_LTP model performs better than the dynamical models and tends to produce more false alarms in accumulated forecast precipitation above 250 mm and 100 mm.Compared with TCs without heavy precipitation or typical tracks,TCs with these characteristics are better forecasted by the DSAEF_LTP model.展开更多
Three new π-conjugated hetero aromatic materials consisting of pyridine 3a, furan 3b, and thiophene 3c have been synthesized by Knoevenagel condensation reaction. These molecules have been characterized by 1H NMR, EI...Three new π-conjugated hetero aromatic materials consisting of pyridine 3a, furan 3b, and thiophene 3c have been synthesized by Knoevenagel condensation reaction. These molecules have been characterized by 1H NMR, EI-MS and single crystal X-ray diffraction analysis. Molecule 3a crystallized under monoclinic system with space group C2/c, molecule 3b crystallized under triclinic system with space group P-1 and the molecule 3c crystalized under triclinic system with space group P-1. The optoelectronic properties of these compounds have been studied.Molecules 3a, 3b and 3c showed strong absorption maxima wavelengths at 300, 419 and 418 nm, respectively. The molar extinction coefficients (ε) of the compounds 3a, 3b and 3c suggested that molecule 3b has better ability to absorb UV light;molecule 3a has better fluorescence intensity than molecule 3b and 3c. Low energy gaps of HOMO and LUMO energy levels of these compounds suggests that these compounds may be a promising new class of lead compounds for developing high performance semiconductor materials. Compounds 3a, 3b and 3c has emissions near to blue light, a slight modification of the structures by extending conjugation may find important applications in optoelectronic devices as blue light emitters in organic light-emitting devices for the development of new generation organic semiconducting materials.展开更多
The strong photoluminescence properties of europium complexes with organic ligands attracted the attention of many researchers and found a wide range of uses in medical, industrial and biological fields. In this artic...The strong photoluminescence properties of europium complexes with organic ligands attracted the attention of many researchers and found a wide range of uses in medical, industrial and biological fields. In this article, four new Tetrakis europium complexes <b>3a</b>, <b>3b</b>, <b>3c</b> and <b>3d</b> have been prepared using 1-phenyl-4,4,4-trifluoro-1,3-butenedionato ligand and pyridinium, bipyridinium, piperazinium and piperidinium counter cations. These complexes have been characterized by negative FAB-mass. The crystal structures of <b>3a</b>, <b>3b</b>, <b>3c</b> and <b>3d</b> were determined by single crystal X-ray diffraction analysis. The complex <b>3a</b> crystallized in monoclinic form, space group <i>P</i>2<sub>1</sub>/<i>n </i><span>with four molecules in the unit cell.<i> </i>The complex <b>3b</b> crystallized in monoclinic form, space group <i>P</i>2/<i>n </i><span>with two complex molecules in the unit cell.<i> </i>The complex <b>3c</b> crystallized in monoclinic form, space group <i>C</i>2/<i>c </i><span>with sixteen molecules in the unit cell.<i> </i>The complex <b>3d</b> crystallized in monoclinic form, space group <i>P</i>2<sub>1</sub>/<i>n </i><span>with four complex molecules in the unit cell. The complex <b>3a</b> has 1,2-alternative structure, <b>3b</b> has 1,3-alternative structure, <b>3c </b>has cone like structure and <b>3d</b> has partial cone like structure. The photoluminescence properties of these complexes have been evaluated. Strong red emissions were observed in all four complexes due to <sup>5</sup>D<sub>0</sub> → <sup>7</sup>F<sub>2</sub> transition of Europium (III) ions under UV excitation. Four <i>β</i>-diketone ligands acted as strong antenna ligands and transferred the absorbed energy to europium (III) ion effectively;consequently strong red luminescence was observed.展开更多
Viologens (<i>N,N'</i>-dimethyl-4,4-bipyridinium) are advanced functional materials, found important applications in electrochromic devices, molecular machines, organic batteries, and carbohydrate oxid...Viologens (<i>N,N'</i>-dimethyl-4,4-bipyridinium) are advanced functional materials, found important applications in electrochromic devices, molecular machines, organic batteries, and carbohydrate oxidation catalysts in alkaline fuel. In this article, we investigated the design, synthesis and photophysical properties of <i>N,N'</i>-dimethyl-2,5-Bis(pyridinium)oxadiazole <b>4</b> and its precursor 2,5- Bis(pyridine)oxadiazole<b> 2</b>. The crystal structure and photophysical properties of viologen <b>4</b> and precursor <b>2</b> have been determined. The viologen molecule <b>4</b> crystallized in monoclinic form, space group <i>P</i>2<sub>1</sub>/<i>n</i> with four molecules in unit cell. Precursor molecule <b>2</b> also crystalized in monoclinic form, space group <i>C</i>2/<i>c</i> with four molecules in unit cell. From X-rd data, we found three cations in the molecular structure of viologen molecule <b>4</b>, which is unusual in viologens. In the three-dimensional molecular packing diagram of molecule <b>4</b>, the three cations and iodate anions are stabilized by C···C, C···I, N···I, N···H, H···I, N—H···I and C—H···I. The dihedral angle between planes having oxadiazole and two benzene rings are 5°and 8°, suggesting the molecule <b>4</b> is a slightly strained one. The molecular structure of precursor molecule <b>2</b> stabilized by C···C and N···H short contacts between the molecules. The molecule <b>4</b> displayed strong absorbance at 315 nm and emissions between 390 - 410 nm.展开更多
Treatment of 1,3-diphenyl-1,3-propanedione 1a with europium (III) chloride in the presence of piperidine results in the halide ligands exchange giving newly piperidinium tetrakis (1,3-diphenyl-1,3-propanedionato)europ...Treatment of 1,3-diphenyl-1,3-propanedione 1a with europium (III) chloride in the presence of piperidine results in the halide ligands exchange giving newly piperidinium tetrakis (1,3-diphenyl-1,3-propanedionato)europate(III) complex 2a. The complex was characterized by 1H-NMR, positive FAB-mass, and Elemental Analysis. The exact molecular structure of 2a was determined by single crystal X-ray diffraction with the monoclinic space group Cc (centrosymmetric, No.13). The large cavity sizes of the complex 2a facilitated the inclusion of water and benzene solvate molecules. The other two different crystals 2b, 2c having two water molecules and one benzene moleculewere obtained by the crystallization in different solvents and the exact molecular structures were determined by single crystal X-ray diffraction analysis with space groups P21/n (centrosymmetric, No.14), and P21/n (centrosymmetric, No.14), respectively. The eight coordinate structures of the complexes in the three crystals were slightly different due to the crystal packing and the existence of the solvent molecule(s). The photoluminescence studies indicated that four β-diketone ligands acted as strong antenna ligands and transferred the absorbed energy to europium (III) ion, consequently red luminescence was observed. These strong emissions wereattributed to the 5D0 → 7F2 transition of Europium (III) ions under UV excitation. The photoluminescence spectrum of the three crystals was almost same in solid as well as in solution.展开更多
文摘Objective:The objective of the study is to describe the work-related quality of life(WRQOL)among nurses and explore its association with performance evaluation ratings.Methods:A cross-sectional design was utilized measuring the WRQOL scale and the previous performance appraisal rating.Multistage sampling approach was utilized with nurses stratified based on their position and then systematically random sampled based on their unit assignment.Results:One hundred and eighty-two nurses were included.About half reported a high quality of work life(101;55.5%).Low scores were noted on the subscale working conditions(100;54.9%),low to average responses for home-work interface(109;59.9%),control at work(100;54.9%),and stress at work(90;49.5%).A higher proportion of nurses reported positive responses toward the areas of general well-being(113;62.1%)and job-career satisfaction(112;61.5%),than in the other subscales.There were notable differences between WRQOL ratings:(1)Head nurses had the highest perceived quality of work life,followed by nurse supervisors and charge nurses(F=6.1,P<0.01)and(2)Nurses in the pay-patient services reported lower quality of working life,while those in office and outpatient services had more positive scores(F=4.6,P<0.01).Conclusion:Only more than half of the nurses reported a high quality of work life,some of its dimensions,particularly job and career satisfaction and working conditions,appeared to vary in the perceived degree across years in service,work hours,and position.The assessment of the quality of work life may serve as an important tool to address staff burnout,absenteeism and other issues that affect job performance among health-care professionals.
文摘Coastal vulnerability assessment using the Integrated Sensitivity, Exposure, and Adaptive Capacity to Climate Change Vulnerability Assessment (ICSEA-C-Change) tool provides a deeper understanding of the potential impacts of climate change on coastal zones. Vulnerability ratings were obtained using rubrics that were presented to the stakeholders during focused group discussions. Derived scores were then averaged and consolidated to come up with the overall vulnerability rating. These ratings were based on the resource and status of coastal habitats’ reliance on near-shore fishing and other quality measures like fisheries ecosystem dependency, population, and water quality of the coastal habitats in the barangays. Ratings resulted in identifying 12 barangays out of 23 that are highly vulnerable to climate change impacts such as waves, storm surges, sea level rise, increase in surface temperature, and extreme rainfall. These are Buenavista and Basicao (Pioduran), Catburawan (Ligao), Tapel, Nagas and Maramba (Oas), Talin-Talin, Pantao, Macabugos, and Tambo (Libon) and Buhatan and Villa Hermosa (Rapu-Rapu). Assessment results were highly influenced by the absence of three major marine habitats, i.e., coral reefs, seagrass/seaweeds, and mangroves in the coastal areas. Likewise, 11 barangays out of 23, which were Marigondon and Malidong (Pioduran), Maonon and Cabarian (Ligao), Badian and Cagmanaba (Oas), Apud and Rawis (Libon), and Galicia, Hamorawon, and Poblacion (Rapu-Rapu) obtained moderate vulnerability scores. This was attributed to the presence of marine habitats that although in poor state, may serve their ecological functioning when properly protected. Highly vulnerable barangays must be prioritized in coastal rehabilitation and disaster risk reduction management planning. Parameters encompassing the sensitivity and adaptive capacity of each barangay must be taken into consideration to reduce potential impacts brought by factors attributed to climate change. Vital information from the assessment will serve as basis for developing strategic plans for improving the climate change adaptation strategies of the local government units.
文摘The study explores the yearnings of fisherfolks on their child’s education, hindrances, and factors that shape their desire as parents. Field observations and key informant interview among elder members of fisherfolk communities surrounding the Albay, Ragay, and Asid Gulfs of the Bicol Region was utilized. The study revealed that the majority of the fisherfolk parents do not want their children to continue fishing as their main source of livelihood because of potential risks, hardships, and cultural factors like collectivism, close family ties, and dependence on the elders. The parents’ aspirations were shaped by their persistence over various threats, fears, personal unfulfilled dreams, and career opportunities thru education. Most of the parents desired a college education and a safe and secure profession for their children. The study deduced that these challenges can be a contributory factor for the declining number of fisherfolks surrounding the gulfs. Influencing this sector is the factor motivating fishers in their aspirations for their children’s education. The study recommends introducing strategies for fisherfolks to develop a strong sense of hope and drive in realizing their aspirations and further research on the impact of culture, the role of women and children, and fisherfolks and their success stories.
文摘Enteral nutrition has been strongly recommended by major scientific societies for the nutritional management of patients with acute pancreatitis.Providing severe acute pancreatitis patients with enteral nutrition within the first 24-48 h of hospital admission can help improve outcomes compared to parenteral nutrition and no feeding.New research is focusing in on when and what to feed to best improve outcomes for acute pancreatitis patients.Early enteral nutrition have the potential to modulate the immune responses.Despite this consistent evidence of early enteral nutrition in patients with acute pancreatitis,clinical practice continues to vary due to individual clinician preference.Achieving the immune modulating effects of enteral nutrition heavily depend on proper placement of the feeding tube and managing any tube feeding associated complications.The current article reviews the immune modulating effects of enteral nutrition and pro-and prebiotics and suggests some practical tools that help improve the patient adherence and tolerance to the tube feeding.Proper selection of the type of the tube,close monitoring of the tube for its placement,patency and securing its proper placement and routine checking the gastric residual volume could all help improve the outcome.Using peptide-based and high medium chaintriglycerides feeding formulas help improving feeding tolerance.
基金supported by the National Natural Science Foundation of China(31572416,31372319,31330075 and 31110103909)Hubei Provincial Key Project for Scientific and Technical Innovation(2014ABA022)+2 种基金Hubei Hundred Talent program,Natural Science Foundation of Hubei Province(2013CFA097)Agriculture and Food Research Initiative Competitive Grants(2014-67015-21770 and 2015-67015-23276)from the USDA National Institute of Food and AgricultureTexas A&M Agri Life Research(H-8200)
文摘Recent years have witnessed growing interest in the role of peptides in animal nutrition. Chemical, enzymatic, or microbial hydrolysis of proteins in animal by-products or plant-source feedstuffs before feeding is an attractive means of generating high-quality small or large peptides that have both nutritional and physiological or regulatory functions in livestock, poultry and fish. These peptides may also be formed from ingested proteins in the gastrointestinal tract, but the types of resultant peptides can vary greatly with the physiological conditions of the animals and the composition of the diets. In the small intestine, large peptides are hydrolyzed to small peptides,which are absorbed into enterocytes faster than free amino acids(AAs) to provide a more balanced pattern of AAs in the blood circulation. Some peptides of plant or animal sources also have antimicrobial, antioxidant,antihypertensive, and immunomodulatory activities. Those peptides which confer biological functions beyond their nutritional value are called bioactive peptides. They are usually 2–20 AA residues in length but may consist of >20AA residues. Inclusion of some(e.g. 2–8%) animal-protein hydrolysates(e.g., porcine intestine, porcine mucosa,salmon viscera, or poultry tissue hydrolysates) or soybean protein hydrolysates in practical corn-and soybean mealbased diets can ensure desirable rates of growth performance and feed efficiency in weanling pigs, young calves,post-hatching poultry, and fish. Thus, protein hydrolysates hold promise in optimizing the nutrition of domestic and companion animals, as well as their health(particularly gut health) and well-being.
文摘Area Sampling Frames(ASFs) are the basis of many statistical programs around the world. To improve the accuracy,objectivity and efficiency of crop survey estimates,an automated stratification method based on geospatial crop planting frequency and cultivation data is proposed. This paper investigates using 2008–2013 geospatial corn,soybean and wheat planting frequency data layers to create three corresponding single crop specific and one multi-crop specific South Dakota(SD) U.S. ASF stratifications. Corn,soybeans and wheat are three major crops in South Dakota. The crop specific ASF stratifications are developed based on crop frequency statistics derived at the primary sampling unit(PSU) level based on the Crop Frequency Data Layers. The SD corn,soybean and wheat mean planting frequency strata of the single crop stratifications are substratified by percent cultivation based on the 2013 Cultivation Layer. The three newly derived ASF stratifications provide more crop specific information when compared to the current National Agricultural Statistics Service(NASS) ASF based on percent cultivation alone. Further,a multi-crop stratification is developed based on the individual corn,soybean and wheat planting frequency data layers. It is observed that all four crop frequency based ASF stratifications consistently predict corn,soybean and wheat planting patterns well as verified by the 2014 Farm Service Agency(FSA) Common Land Unit(CLU) and 578 administrative data. This demonstrates that the new stratifications based on crop planting frequency and cultivation are crop type independent and applicable to all major crops. Further,these results indicate that the new crop specific ASF stratifications have great potential to improve ASF accuracy,efficiency and crop estimates.
基金Item Sponsored by National Natural Science Foundation of China (60277029)
文摘Artificial neural network is a new approach to pattern recognition and classification. The model of multilayer perceptron (MLP) and back-propagation (BP) is used to train the algorithm in the artificial neural network. An improved fast algorithm of the BP network was presented, which adopts a singular value decomposition (SVD) and a generalized inverse matrix. It not only increases the speed of network learning but also achieves a satisfying precision. The simulation and experiment results show the effect of improvement of BP algorithm on the classification of the surface defects of steel plate.
文摘AIM: To investigate the effects of broccoli sprout extract(BSEx) on liver gene expression and acute liver injury in the rat.METHODS: First, the effects of BSEx on liver gene expression were examined. Male rats were divided into two groups. The Control group was fed the AIN-76 diet, and the BSEx group was fed the AIN-76 diet containing BSEx. After a 10-d feeding period, rats were sacrificed and their livers were used for DNA microarray and realtime reverse transcription-polymerase chain reaction(RT-PCR) analyses. Next, the effects of BSEx on acute liver injury were examined. In experiments using acute liver injury models, 1000 mg/kg acetaminophen(APAP) or 350 mg/kg D-galactosamine(D-Gal N) was used to induce injury. These male rats were divided into four groups: Control, BSEx, Inducer(APAP or D-Gal N), and Inducer+BSEx. The feeding regimens were identical for the two analyses. Twenty-four hours following APAP administration via p.o. or D-Gal N administration via i.p., rats were sacrificed to determine serum aspartate transaminase(AST) and alanine transaminase(ALT) levels, hepatic glutathione(GSH) and thiobarbituric acid-reactive substances accumulation and glutathioneS-transferase(GST) activity. RESULTS: Microarray and real-time RT-PCR analyses revealed that BSEx upregulated the expression of genes related to detoxification and glutathione synthesis in normal rat liver. The levels of AST(70.91 ± 15.74 IU/m L vs 5614.41 ± 1997.83 IU/m L, P < 0.05) and ALT(11.78 ± 2.08 IU/m L vs 1297.71 ± 447.33 IU/m L, P < 0.05) were significantly suppressed in the APAP + BSEx group compared with the APAP group. The level of GSH(2.61 ± 0.75 nmol/g tissue vs 1.66 ± 0.59 nmol/g tissue, P < 0.05) and liver GST activity(93.19 ± 16.55 U/g tissue vs 51.90 ± 16.85 U/g tissue, P < 0.05) were significantly increased in the APAP + BSEx group compared with the APAP group. AST(4820.05 ± 3094.93 IU/m L vs 12465.63 ± 3223.97 IU/m L, P < 0.05) and ALT(1808.95 ± 1014.04 IU/m L vs 3936.46 ± 777.52 IU/m L, P < 0.05) levels were significantly suppressed in the D-Gal N + BSEx group compared with the D-Gal N group, but the levels of AST and ALT in the D-Gal N + BSEx group were higher than those in the APAP + BSEx group. The level of GST activity was significantly increased in the D-Gal N + BSEx group compared with the D-Gal N group(98.04 ± 15.75 U/g tissue vs 53.15 ± 8.14 U/g tissue, P < 0.05).CONCLUSION: We demonstrated that BSEx protected the liver from various types of xenobiotic substances through induction of detoxification enzymes and glutathione synthesis.
文摘Embryonic stem(ES) cells are isolated from theinner cell mass of a blastocyst, and are used for the generation of gene-modified animals. In mice, the transplantation of gene-modified ES cells into recipient blastocysts leads to the creation of gene-targeted mice such as knock-in and knock-out mice; these gene-targeted mice contribute greatly to scientific development. Although the rat is considered a useful laboratory animal alongside the mouse, fewer genemodified rats have been produced due to the lack of robust establishment methods for rat ES cells. A new method for establishing rat ES cells using signaling inhibitors was reported in 2008. By considering the characteristics of rat ES cells, recent research has made progress in improving conditions for the stable culture of rat ES cells in order to generate gene-modified rats efficiently. In this review, we summarize several advanced methods to maintain rat ES cells and generate gene-targeted rats.
基金Amirkabir University of Technology(Iran)and Helmholtz Institute Freiberg for Research Technology(Germany)for supporting this research work。
文摘The present study initially investigates the kinetics of microwave-assisted grinding and flotation in a porphyry copper deposit.Kinetic tests were conducted on untreated and microwave-irradiated samples by varying the exposure time from 15 to 150 s.Optical microscopy,energy-dispersive X-ray spectroscopy,and scanning electron microscopy were conducted to determine the mineral liberation and particle surface properties,and to perform mineralogical analyses.Results showed that the ore breakage rate constant monotonically increased by increasing the exposure time,particularly for the coarsest fraction size(400μm)due to the creation of thermal stress fractures alongside grain boundaries.Excessive irradiation time(>60 s)led to the creation of oxidized and porous surfaces along with a dramatic change in particle morphologies that result in a substantial reduction of chalcopyrite and pyrite flotation rate constants and ultimate recoveries.We concluded that MW-pretreated copper ore was ground faster than the untreated variety,but the two types have slightly similar floatabilities.
基金the Research&Development Division and Management of Tata Steel Ltd.for their support and permission to publish this work
文摘The Linz-Donawitz(LD) steelmaking process produces LD slag at a rate of about 125 kg/t. After metallic scrap recovery, the non-metallic LD slag is rejected because its physical/chemical properties are unsuitable for recycling. X-ray diffraction(XRD) studies have indicated that non-metallic LD slag contains a substantial quantity of mineral phases such as di- and tricalcium silicates. The availability of these mineral phases indicates that LD slag can be recycled by iron(Fe)-ore sintering. However, the presence of 1.2wt% phosphorus(P) in the slag renders the material unsuitable for sintering operations. Electron probe microscopic analysis(EPMA) studies indicated concentration of phosphorus in dicalcium silicate phase as calcium phosphate. The Fe-bearing phases(i.e., wustite and dicalcium ferrite) showed comparatively lower concentrations of P compared with other phases in the slag. Attempts were made to lower the P content of LD slag by adopting various beneficiation techniques. Dry high-intensity magnetic separation and jigging were performed on as-received samples with particle sizes of 6 and 3 mm. Spiral separation was conducted using samples ground to sizes of less than 1 and 0.5 mm. Among these studies, grinding to 0.5 mm followed by spiral concentration demonstrated the best results, yielding a concentrate with about 0.75wt% P and 45wt% Fe.
基金by the National Foundation for Science and Technology Development of Vietnam(No.103.04-2017.37)。
文摘This paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors(CFs)in several neutron standard fields(i.e.,two standard fields with bare sources of252Cf and241Am-Be,and five simulated workplace fields with241Am-Be moderated sources).The calibration in standard fields with bare sources was conducted by following the recommendations of the ISO 8529 standard.The measured total neutron ambient dose equivalent rates,denoted as H*(10)tot,were analyzed to obtain direct components,denoted as H*(10)dir,using a reduced fitting method.The CF was then calculated as the ratio between the conventional true value of the neutron ambient dose equivalent rate in a free field,denoted as H*(10)FF,and the value of H*(10)dir.In contrast,in the simulated workplace neutron fields,the calibration of the neutron dose rate meter was conducted by following the ISO 12789 standard.The CF was calculated as the ratio between the values of H*(10)totmeasured by a standard instrument(i.e.,Bonner sphere spectrometer)and the neutron dose rate meter.The CF values were obtained in the range of 0.88–1.0.The standard uncertainties(k=1)of the CFs were determined to be in the range of approximately 6.6–13.1%.
文摘Pueraria flower extract (PFE) is a hot water extract of the Kudzu flower (Pueraria thomsonii). Tea made from dried Kudzu flower is widely used inChina, and PFE is utilized as a nutritional supplement inJapan. PFE contains unique isoflavones such as 6-hydroxygenistein 6,7-di-O-glucoside (6HGDG), tectorigenin 7-O-xylosylglucoside (TGXG), and tectoridin. 6HGDG is known to be metabolized into 6-hydroxygenistein, and TGXG and tectoridin are known to be metabolized into tectorigenin in the digestive tract. Isoflavones typically mimic the effects β-estradiol has on estrogen receptors (ERs) and may influence the female genital system in the case of excessive intake. As a result, the upper limit of safe daily consumption of soy isoflavones has been enforced inJapan. In the present study, ER-binding assays were performed using the EnBio estrogen receptor/cofactor assay system to compare the estrogenic activity of 6-hydroxygenistein and tectorigenin to that of the soy isoflavone genistein. In addition, uterotrophic bioassays were performed to investigate the estrogenic effects of PFE in vivo. The ER-binding assays revealed that the ER-binding affinities of 6-hydroxygenistein and tectorigenin were approximately 0.01 - 0.04 that of genistein. Soy isoflavone products also induced an increase in uterine wet and blotted weight at doses of 500 mg/kg and 1000 mg/kg, whereas PFE did not cause adverse estrogenic effects, even at a dose of 1000 mg/kg. Based on these results, PFE does not appear to contain compounds with strong estrogenic activity or cause adverse estrogenic effects in vivo. Importantly, the results of this study confirm the safety of PFE as a food supplement.
基金National Key R&D Program of China(2019YFC1510205)Hainan Provincial Key R&D Program of China(SQ2019KJHZ0028)National Natural Science Foundation of China(41675042)。
文摘The Dynamical-Statistical-Analog Ensemble Forecast model for landfalling tropical cyclones(TCs)precipitation(DSAEF_LTP)utilises an operational numerical weather prediction(NWP)model for the forecast track,while the precipitation forecast is obtained by finding analog cyclones,and making a precipitation forecast from an ensemble of the analogs.This study addresses TCs that occurred from 2004 to 2019 in Southeast China with 47 TCs as training samples and 18 TCs for independent forecast experiments.Experiments use four model versions.The control experiment DSAEF_LTP_1 includes three factors including TC track,landfall season,and TC intensity to determine analogs.Versions DSAEF_LTP_2,DSAEF_LTP_3,and DSAEF_LTP_4 respectively integrate improved similarity region,improved ensemble method,and improvements in both parameters.Results show that the DSAEF_LTP model with new values of similarity region and ensemble method(DSAEF_LTP_4)performs best in the simulation experiment,while the DSAEF_LTP model with new values only of ensemble method(DSAEF_LTP_3)performs best in the forecast experiment.The reason for the difference between simulation(training sample)and forecast(independent sample)may be that the proportion of TC with typical tracks(southeast to northwest movement or landfall over Southeast China)has changed significantly between samples.Forecast performance is compared with that of three global dynamical models(ECMWF,GRAPES,and GFS)and a regional dynamical model(SMS-WARMS).The DSAEF_LTP model performs better than the dynamical models and tends to produce more false alarms in accumulated forecast precipitation above 250 mm and 100 mm.Compared with TCs without heavy precipitation or typical tracks,TCs with these characteristics are better forecasted by the DSAEF_LTP model.
文摘Three new π-conjugated hetero aromatic materials consisting of pyridine 3a, furan 3b, and thiophene 3c have been synthesized by Knoevenagel condensation reaction. These molecules have been characterized by 1H NMR, EI-MS and single crystal X-ray diffraction analysis. Molecule 3a crystallized under monoclinic system with space group C2/c, molecule 3b crystallized under triclinic system with space group P-1 and the molecule 3c crystalized under triclinic system with space group P-1. The optoelectronic properties of these compounds have been studied.Molecules 3a, 3b and 3c showed strong absorption maxima wavelengths at 300, 419 and 418 nm, respectively. The molar extinction coefficients (ε) of the compounds 3a, 3b and 3c suggested that molecule 3b has better ability to absorb UV light;molecule 3a has better fluorescence intensity than molecule 3b and 3c. Low energy gaps of HOMO and LUMO energy levels of these compounds suggests that these compounds may be a promising new class of lead compounds for developing high performance semiconductor materials. Compounds 3a, 3b and 3c has emissions near to blue light, a slight modification of the structures by extending conjugation may find important applications in optoelectronic devices as blue light emitters in organic light-emitting devices for the development of new generation organic semiconducting materials.
文摘The strong photoluminescence properties of europium complexes with organic ligands attracted the attention of many researchers and found a wide range of uses in medical, industrial and biological fields. In this article, four new Tetrakis europium complexes <b>3a</b>, <b>3b</b>, <b>3c</b> and <b>3d</b> have been prepared using 1-phenyl-4,4,4-trifluoro-1,3-butenedionato ligand and pyridinium, bipyridinium, piperazinium and piperidinium counter cations. These complexes have been characterized by negative FAB-mass. The crystal structures of <b>3a</b>, <b>3b</b>, <b>3c</b> and <b>3d</b> were determined by single crystal X-ray diffraction analysis. The complex <b>3a</b> crystallized in monoclinic form, space group <i>P</i>2<sub>1</sub>/<i>n </i><span>with four molecules in the unit cell.<i> </i>The complex <b>3b</b> crystallized in monoclinic form, space group <i>P</i>2/<i>n </i><span>with two complex molecules in the unit cell.<i> </i>The complex <b>3c</b> crystallized in monoclinic form, space group <i>C</i>2/<i>c </i><span>with sixteen molecules in the unit cell.<i> </i>The complex <b>3d</b> crystallized in monoclinic form, space group <i>P</i>2<sub>1</sub>/<i>n </i><span>with four complex molecules in the unit cell. The complex <b>3a</b> has 1,2-alternative structure, <b>3b</b> has 1,3-alternative structure, <b>3c </b>has cone like structure and <b>3d</b> has partial cone like structure. The photoluminescence properties of these complexes have been evaluated. Strong red emissions were observed in all four complexes due to <sup>5</sup>D<sub>0</sub> → <sup>7</sup>F<sub>2</sub> transition of Europium (III) ions under UV excitation. Four <i>β</i>-diketone ligands acted as strong antenna ligands and transferred the absorbed energy to europium (III) ion effectively;consequently strong red luminescence was observed.
文摘Viologens (<i>N,N'</i>-dimethyl-4,4-bipyridinium) are advanced functional materials, found important applications in electrochromic devices, molecular machines, organic batteries, and carbohydrate oxidation catalysts in alkaline fuel. In this article, we investigated the design, synthesis and photophysical properties of <i>N,N'</i>-dimethyl-2,5-Bis(pyridinium)oxadiazole <b>4</b> and its precursor 2,5- Bis(pyridine)oxadiazole<b> 2</b>. The crystal structure and photophysical properties of viologen <b>4</b> and precursor <b>2</b> have been determined. The viologen molecule <b>4</b> crystallized in monoclinic form, space group <i>P</i>2<sub>1</sub>/<i>n</i> with four molecules in unit cell. Precursor molecule <b>2</b> also crystalized in monoclinic form, space group <i>C</i>2/<i>c</i> with four molecules in unit cell. From X-rd data, we found three cations in the molecular structure of viologen molecule <b>4</b>, which is unusual in viologens. In the three-dimensional molecular packing diagram of molecule <b>4</b>, the three cations and iodate anions are stabilized by C···C, C···I, N···I, N···H, H···I, N—H···I and C—H···I. The dihedral angle between planes having oxadiazole and two benzene rings are 5°and 8°, suggesting the molecule <b>4</b> is a slightly strained one. The molecular structure of precursor molecule <b>2</b> stabilized by C···C and N···H short contacts between the molecules. The molecule <b>4</b> displayed strong absorbance at 315 nm and emissions between 390 - 410 nm.
文摘Treatment of 1,3-diphenyl-1,3-propanedione 1a with europium (III) chloride in the presence of piperidine results in the halide ligands exchange giving newly piperidinium tetrakis (1,3-diphenyl-1,3-propanedionato)europate(III) complex 2a. The complex was characterized by 1H-NMR, positive FAB-mass, and Elemental Analysis. The exact molecular structure of 2a was determined by single crystal X-ray diffraction with the monoclinic space group Cc (centrosymmetric, No.13). The large cavity sizes of the complex 2a facilitated the inclusion of water and benzene solvate molecules. The other two different crystals 2b, 2c having two water molecules and one benzene moleculewere obtained by the crystallization in different solvents and the exact molecular structures were determined by single crystal X-ray diffraction analysis with space groups P21/n (centrosymmetric, No.14), and P21/n (centrosymmetric, No.14), respectively. The eight coordinate structures of the complexes in the three crystals were slightly different due to the crystal packing and the existence of the solvent molecule(s). The photoluminescence studies indicated that four β-diketone ligands acted as strong antenna ligands and transferred the absorbed energy to europium (III) ion, consequently red luminescence was observed. These strong emissions wereattributed to the 5D0 → 7F2 transition of Europium (III) ions under UV excitation. The photoluminescence spectrum of the three crystals was almost same in solid as well as in solution.
