Microsatellite marker （or Simple Sequence Repeate, SSR） is a marker technology based on DNA molecular length poly morphism. It is also one of the most commonly used molecular markers. Traditional SSR marker developm...Microsatellite marker （or Simple Sequence Repeate, SSR） is a marker technology based on DNA molecular length poly morphism. It is also one of the most commonly used molecular markers. Traditional SSR marker development methods are relatively time-consuming and mostly relying on the known genome sequence information while recently developed methods of SSR marker based on RAPD, ISSR-PCR SSR, the use of hybrid options, sequence tag SSR library access and screening EST-SSR have been widely used. This paper gave an overview of the methods mentioned above for the development of SSR markers.展开更多
Carbonate reservoirs worldwide are complex in structure,diverse in form,and highly heterogeneous.Based on these characteristics,the reservoir stimulation technologies and fluid flow characteristics of carbonate reserv...Carbonate reservoirs worldwide are complex in structure,diverse in form,and highly heterogeneous.Based on these characteristics,the reservoir stimulation technologies and fluid flow characteristics of carbonate reservoirs are briefly described in this study.The development methods and EOR technologies of carbonate reservoirs are systematically summarized,the relevant mechanisms are analyzed,and the application status of oil fields is catalogued.The challenges in the development of carbonate reservoirs are discussed,and future research directions are explored.In the current development processes of carbonate reservoirs,water flooding and gas flooding remain the primary means but are often prone to channeling problems.Chemical flooding is an effective method of tertiary oil recovery,but the harsh formation conditions require high-performance chemical agents.The application of emerging technologies can enhance the oil recovery efficiency and environmental friendliness to a certain extent,which is welcome in hard-to-recover areas such as heavy oil reservoirs,but the economic cost is often high.In future research on EOR technologies,flow field control and flow channel plugging will be the potential directions of traditional development methods,and the application of nanoparticles will revolutionize the chemical EOR methods.On the basis of diversified reservoir stimulation,combined with a variety of modern data processing schemes,multichannel EOR technologies are being developed to realize the systematic,intelligent,and cost-effective development of carbonate reservoirs.展开更多
The oil oxidation characteristics of the whole temperature regions from 30 ℃ to 600 ℃ during oil reservoir air injection were revealed by experiments. The whole oil oxidation temperature regions were divided into fo...The oil oxidation characteristics of the whole temperature regions from 30 ℃ to 600 ℃ during oil reservoir air injection were revealed by experiments. The whole oil oxidation temperature regions were divided into four different parts: dissolving and inflation region, low temperature oxidation region, medium temperature oxidation region and high temperature oxidation region. The reaction mechanisms of different regions were explained. Based on the oil oxidation characteristics and filed tests results, light oil reservoirs air injection development methods were divided into two types: oxygen-reducing air flooding and air flooding;heavy oil reservoirs air injection in-situ combustion development methods were divided into two types: medium temperature in-situ combustion and high temperature in-situ combustion. When the reservoir temperature is lower than 120 ℃, oxygen-reducing air flooding should be used for light oil reservoir development. When the reservoir temperature is higher than 120 ℃, air flooding method should be used for light oil reservoir development. For a normal heavy oil reservoir, when the combustion front temperature is lower than 400 ℃, the development method is medium temperature in-situ combustion. For a heavy oil reservoir with high oil resin and asphalting contents, when the combustion front temperature is higher than 450 ℃, the development method at this condition is high temperature in-situ combustion. Ten years field tests of air injection carried out by PetroChina proved that air has advantages in technical, economical and gas source aspects compared with other gas agents for oilfield gas injection development. Air injection development can be used in low/super-low permeability light oil reservoirs, medium and high permeability light oil reservoirs and heavy oil reservoirs. Air is a very promising gas flooding agent.展开更多
The research work was carried out for establishing a new Ultra Violet (UV)— Visible spectroscopy and Reverse phase-Ultra Fast Liquid Chromatography (RP-UFLC) method for the analysis and quantification of a biosimilar...The research work was carried out for establishing a new Ultra Violet (UV)— Visible spectroscopy and Reverse phase-Ultra Fast Liquid Chromatography (RP-UFLC) method for the analysis and quantification of a biosimilar drug, Filgrastim. Filgrastim or recombinant methionyl granulocyte colony stimulating factor (rGCSF) is a glycoprotein. It has a biological action essential for proliferation and differentiation of hematopoetic and progenitor cells. The UV and RP-UFLC work was carried on a Shimadzu UV1800 Spectrophotometer and Shimadzu Prominence LC-20AD UFLC systems, respectively. The <i>λ</i><sub>max</sub> of filgrastim was found to be 215 nm. The correlation coefficient by UV spectroscopy was found to be 0.9994 for the concentration range of 1 to 3 μg/ml in double distilled water. The Reverse phase UFLC was done by using Phenomenex C4 (25 cm × 0.46 cm internal diameter) 15 μ, 300 A° analytical column. The optimized mobile phase for binary elution was Acetonitrile and double distilled water (80:20) with a flow rate of 1 ml/min. The retention time of drug was at 3.2 min. It was observed that the response of the detector was linear in the range of 5 - 15 μg/ml with correlation coefficient value of 0.999. After developing the methods, it was assured for the intended use by validation of the analytical parameters like linearity, accuracy, precision, limit of detection, limit of quantitation, ruggedness and robustness. The results of all the parameters for both the methods were found to be within the acceptance criteria as per the International Council for Harmonisation (ICH) guidelines.展开更多
Dispersed and peripheral spaces in the urban core are influenced both by the trend towards constant growth as well as social ways of life which are constantly evolving. Following a connotation, these two factors there...Dispersed and peripheral spaces in the urban core are influenced both by the trend towards constant growth as well as social ways of life which are constantly evolving. Following a connotation, these two factors therefore play a crucial role in defining the alternation of urban space--in particular, that of the centers. The main focus of this research article is on the methodology used in the survey and evaluation of ＂centralities＂ as well as their developments over the past four decades （1974-2014） in approaches to urban development that has been developed in Graz.~ The analysis has drawn on the four editions （＂evolution＂） of approaches to urban development as conceived by the city of Graz in order to examine their verbal characteristics in regard to centralities. At the same time, the analysis does not examine presentations of plans which exist in supplementary forms （e.g., explanatory reports and supplemented plans）--it restricts itself solely to the various plans set out in the STEKs.2 The highest degree of accuracy has been applied to the notion of ＂centralis＂ in approaches to urban development. The goal of the research project was to depict the modulation of the notion of ＂centrality＂ in the urban context as a space-forming dimension. Furthermore, it clearly shows the extent to which the notion of the ＂centre＂ （in the widest sense of the word） has become distanced from qualitative, spatial development and at the current time of urban development is experiencing a sort of Renaissance. In the field of ＂urban development＂, architectural references in the context of＂centrality＂ have scarcely been researched. This has led to the opening-up of a complex interdisciplinary research field. In order to make the complex architectural determinants of ＂centrality＂ more accessible to the participating disciplines, approaches to urban development have been explored in the form of a social and spatial analysis.展开更多
Linux-based Platform for Open Architecture Controller ( POAC ), a new open architecture controller and its modular developing method are discussed. POAC divides the application software of controller into the developi...Linux-based Platform for Open Architecture Controller ( POAC ), a new open architecture controller and its modular developing method are discussed. POAC divides the application software of controller into the developing system and the application system. In the developing system, PAOC abstracts a series of function modules with unified data interface and function interface. In the application system, POAC defines the model of the architecture module, realizing the interoperability and interchangeability between the architecture modules. The modular developing method entities the users to make up an application system with some architecture modules, which consist of a set of function modules. The modular developing method decreases the developing time from the standard of controller architecture to the product.展开更多
Viscous fluid flows contain abundant "physical phenomena and the viscous fluid dynamics is of wide applications in the fields of natural and engineering sciences. After the basic equations of viscousfluiddynamics...Viscous fluid flows contain abundant "physical phenomena and the viscous fluid dynamics is of wide applications in the fields of natural and engineering sciences. After the basic equations of viscousfluiddynamics (i.e., the Navier-Stokes equations) came out, one of the most important contributions to the discipline was the boundary layer (BL) theory and the BL equations presented by Prandtl展开更多
Brucellosis is a global public health issue that severely affects human health,Brucella melitensis is currently the predominant species in China.Brucella spondylitis is the primary cause of the debilitating and disabl...Brucellosis is a global public health issue that severely affects human health,Brucella melitensis is currently the predominant species in China.Brucella spondylitis is the primary cause of the debilitating and disabling complications[1].The lumbar vertebra was the most commonly affected site,followed by the thoracic,cervical,thoracolumbar,and lumbosacral segments,and back pain,fever,sweating,and fatigue were the most common symptoms[2].However,the diagnosis of Brucella spondylitis is challenging owing to its wide spectrum of clinical presentations,cross-reactions with other bacteria,and low strain isolation rate.Therefore,a timely and accurate diagnosis of spinal brucellosis is crucial for implementing an effective therapeutic plan and improving treatment outcomes.Droplet digital polymerase chain reaction(ddPCR)is widely used for low-abundance nucleic acid detection and is useful for diagnosing infectious diseases[3].Therefore,this study aimed to evaluate the ddPCR approach for the diagnosis of brucellosis with spondylitis to improve its clinical diagnostic capacity.展开更多
Aim:Method for the deternination of erythromycin ethylsuccinale(EES)by ion suppression chromatography(ISC)was developed and the influenc factors on ISC were investigated.Methods:A Zorbax SB-C18 column was used with 0....Aim:Method for the deternination of erythromycin ethylsuccinale(EES)by ion suppression chromatography(ISC)was developed and the influenc factors on ISC were investigated.Methods:A Zorbax SB-C18 column was used with 0.02mol.L^(-1)potassium dihydrogen phosphate-acetonitrile(45:55)as mobile phase,The pH and proportion of the mobile phase showed the greatest influences on retention and selectivity.Therefore,the pH of mobile was adjusted to 6.8,the bhest acetonitrile proportion was 55%.The column temperature was maintained at(300±0.5)℃.Acetonitrile was used as solvent for the sample preparation because EES is more stable in it.The flow rate was 1.2mL.min^(-1)and UV detection was performed at 210nm.Results:Under these chromatographic conditions,the main component(erythromycin A ethylsuccinate)and its related substances were separated.The calibration curve showed good linearity over the range of 0.1-1.0mg.mL^(-1),and its correlation coefficient was 0.9998.Conclusion:The method is very suitable for the analysis of erythromycin ethylsuccinate.展开更多
A rapid GC-FID method was developed to simultaneously determine residual levels of triethylamine(TEA), 1,1,3,3-tetramethylguanidine(TMG), and diisopropylamine(DIPA) in the synthetic route of an active pharmaceutical i...A rapid GC-FID method was developed to simultaneously determine residual levels of triethylamine(TEA), 1,1,3,3-tetramethylguanidine(TMG), and diisopropylamine(DIPA) in the synthetic route of an active pharmaceutical ingredient(API). Due to the severe absorption of amines on GC stationary phases,GC columns with various stationary phases were evaluated for optimal peak shape and reproducibility.The final conditions used the Agilent CP-Volamine column to resolve the three amines in 12 min. Various inlet liners were also screened to further improve the sensitivity of the analysis. The Restek Siltek~? liner was selected to achieve the desired detectability for the method. The quantitation limits were 4, 3, and 4 mg/mL for TEA, DIPA, and TMG in the presence of API, respectively. All three amines showed good linearity(r > 0.999) and recoveries(> 90%) over the concentration range of 3 to 16 mg/mL. The testing of residual amines was initially performed at the penultimate stage of the synthesis. However, this work demonstrates that TMG can act as a proton sponge to react with salicylic acid, the counter ion of the penultimate, to form a volatile component that elutes at a different retention time. Consequently, in the final method, these three amines were monitored in the final API to circumvent the matrix interference.Key parameters of the method were qualified per method validation requirements in ICH guidelines. The method was successfully applied for batch testing during development and implemented as an inprocess control procedure at manufacturing sites.展开更多
Method development has always been and will continue to be a core driving force of microbiome science, In this perspective, we argue that in the next decade, method development in microbiome analysis will be driven by...Method development has always been and will continue to be a core driving force of microbiome science, In this perspective, we argue that in the next decade, method development in microbiome analysis will be driven by three key changes in both ways of thinking and technological platforms： ① a shift from dissecting microbiota structure by sequencing to tracking microbiota state, function, and intercellular interaction via imaging; ② a shift from interrogating a consortium or population of cells to probing individual cells; and ③a shift from microbiome data analysis to microbiome data science. Some of the recent methoddevelopment efforts by Chinese microbiome scientists and their international collaborators that underlie these technological trends are highlighted here. It is our belief that the China Microbiome Initiative has the opportunity to deliver outstanding ＂Made-in-China＂ tools to the international research community, by building an ambitious, competitive, and collaborative program at the forefront of method development for microbiome science.展开更多
This study clarifies the seepage characteristics of complex fractured pressure-sensitive reservoirs,and addresses a common technological problem,that is the alteration of the permeability degree of the reservoir bed(k...This study clarifies the seepage characteristics of complex fractured pressure-sensitive reservoirs,and addresses a common technological problem,that is the alteration of the permeability degree of the reservoir bed(known to be responsible for changes in the direction and velocity of fluid flows between wells).On the basis of a new pressuresensitive equation that considers the fracture directional pressure-sensitive effect,an oil-gas-water three-phase seepage mathematical model is introduced,which can be applied to pressure-sensitive,full-tensor permeability,ultralow-permeability reservoirs with fracture-induced anisotropy.Accordingly,numerical simulations are conducted to explore the seepage laws for ultralow-permeability reservoirs.The results show that element patterns have the highest recovery percentage under a fracture angle of 45°.Accounting for the pressure-sensitive effect produces a decrease in the recovery percentage.Several patterns are considered:inverted five-seven-and nine-spot patterns and a cross-row well pattern.Finally,two strategies are introduced to counteract the rotation of the direction of the principal permeability due to the fracture directional pressure-sensitive effect.展开更多
<strong>Context:</strong> Substandard and falsified medicines are circulating in low-income countries mostly without any control. We availed a simple and not expensive UV-Vis spectroscopic method to evalua...<strong>Context:</strong> Substandard and falsified medicines are circulating in low-income countries mostly without any control. We availed a simple and not expensive UV-Vis spectroscopic method to evaluate the quality of tramadol in Kisangani before and during the Covid-19 period. <strong>Methods:</strong> For the analytical quantitative method, an experimental design was applied to set up the optimal levels of the selected factors, namely, pH of dissolution medium, type of cuvette, and wavelength. Taking into account the capsule pharmaceutical formulation within 80 - 120 μg·mL<sup>-1</sup> concentration range, we analyzed 89 tramadol samples from pharmacies and hospitals of the six Kisangani municipalities. <strong>Results:</strong> pH showed a significant effect on absorbance, whereas quartz cuvette and wavelength did not. A typical 100 μg·mL<sup>-1</sup> tramadol solution gave an absorbance of 0.64 at 272 nm. Validation highlighted a matrix effect observed with a 6% bias. A correction factor of 0.9372 allowed to improve the accuracy profile, which were then totally included within the 10% acceptance limits. Quality control revealed that 25 samples out of 89 were not compliant in terms of manufacturing license, registration status in DRC and content as well. <strong>Conclusion:</strong> This study showed that the strengthening of analytical strategy in Kisangani is a need.展开更多
A caisson breakwater is built on soft foundations after replacing the upper soft layer with sand. This paper presents a dynamic finite element method to investigate the strength degradation and associated pore pressur...A caisson breakwater is built on soft foundations after replacing the upper soft layer with sand. This paper presents a dynamic finite element method to investigate the strength degradation and associated pore pressure development of the intercalated soft layer under wave cyclic loading. By combining the undrained shear strength with the empirical formula of overconsolidation clay produced by unloading and the development model of pore pressure, the dynamic degradation law that describes the undrained shear strength as a function of cycle number and stress level is derived. Based on the proposed dynamic degradation law and M-C yield criterion, a dynamic finite element method is numerically implemented to predict changes in undrained shear strength of the intercalated soft layer by using the general-purpose FEM software ABAQUS, and the accuracy of the method is verified. The effects of cycle number and amplitude of the wave force on the degradation of the undrained shear strength of the intercalated soft layer and the associated excess pore pressure response are investigated by analyzing an overall distribution and three typical sections underneath the breakwater. By comparing the undrained shear strength distributions obtained by the static method and the quasi-static method with the undrained shear strength distributions obtained by the dynamic finite element method in the three typical sections, the superiority of the dynamic finite element method in predicting changes in undrained shear strength is demonstrated.展开更多
Generally, the sequence decision of the development and utilization of Chinese mineral resources is based on national and provincial overall plan of the mineral resources. Such plan usually cannot reflect the relative...Generally, the sequence decision of the development and utilization of Chinese mineral resources is based on national and provincial overall plan of the mineral resources. Such plan usually cannot reflect the relative size of the suitability of the development and utilization of mineral resources. To solve the problem, the paper has selected the gift condition, the market condition, the technological condition,socio-economic condition and environmental condition as the starting-points to analyze the influential factors of the priority-sequence of mineral resources' development and utilization. The above 5 conditions are further specified into 9 evaluative indicators to establish an evaluation indicator system. At last,we propose a decision model of the priority sequence based on grey relational analysis method, and figure out the observation objects by the suitability index of development. Finally, the mineral resources of a certain province in China were analyzed as an example. The calculation results indicate that silver(2.0057), coal(1.9955), zinc(1.9442), cement limestone(1.9077), solvent limestone(1.5624) and other minerals in the province are suitable for development and utilization.展开更多
The research was carried out for establishing a new reverse phase-HPLC stability indicating method for the quantification of Rucaparib. The experiment was determined on Waters HPLC instrument using 996 photo-diode arr...The research was carried out for establishing a new reverse phase-HPLC stability indicating method for the quantification of Rucaparib. The experiment was determined on Waters HPLC instrument using 996 photo-diode array detector. The separation was done by using symmetry C-18 ODS (25 cm × 0.46 cm internal diameter) 5 μm analytical column containing mobile phase of Phosphate buffer (0.02 M) and methanol [65:35% v/v] adjusted pH to 4.8 by adding dilute ortho phosphoric acid. The method was run at 1 ml·min<sup>-1</sup> at 286 nm detection. The drug was eluted at 5.484 min. After developing the method, it was assured for the intended use by validation which was done according to ICH Q2B guidelines. The analytical parameters checked were linearity, accuracy, repeatability, intermediate precision, limit of detection, limit of quantitation, ruggedness and robustness. It was observed that the response of the detector was linear in the range of 6 - 14 μg/ml with correlation coefficient of 0.999. The results of all the parameters were found to be within the acceptance criteria. The stability indicating assay method was established by using the samples generated by forced degradation process. The forced degradation was carried out by subjecting the drug to acid, alkali, thermal, oxidative and photolytic degradation and the results showed that the degradation products were successfully separated from the drug. Hence, this can be applied perfectly later for the analysis of quality of the rucaparib drug.展开更多
The aim of this study was to develop a simple and derivatization free method for the Quantification of S-Epichlorohydrin in R-Epichlorohydrin by using a gas chromatography coupled with flame ionization detector (FID)....The aim of this study was to develop a simple and derivatization free method for the Quantification of S-Epichlorohydrin in R-Epichlorohydrin by using a gas chromatography coupled with flame ionization detector (FID). Enantiopure epichlorohydrin was a valuable epoxide key starting material for preparing optically active Rivaroxaban. The enantiomeric separations of S-Epichlorohydrin and R-Epichlorohydrin were achieved on Gamaa-Dex-225 (30 meters × 0.25 mm I.D, 0.25 μm) column with a total run time of 30 min. Nitrogen was used as a carrier gas with constant pressure 25.0 psi. The critical experimental parameters such as, column selection, flow rate, injection volume and diluent were studied and optimized. Excellent correlation coeffient between peak responses and concentrations was >0.9998. The recoveries of S-Epichlorohydrin spiked in R-Epichlorohydrin were in the range from 98.2% to 102.8%. Limit of quantitation for S-Epichlorohydrin was sufficiently lower than limits specified by ICH. The method has validated as per International Conference on Harmonization (ICH) guidelines. A precise, accurate, linear and robust Gas Chromatography method was developed for the quantification of S-Epichlorohydrin in R-Epichlorohydrin for Rivaroxaban.展开更多
A rapid, accurate, and precise chiral Ultra fast liquid chromatography (UFLC) method was developed and validated for enantiomeric separation of racemic vildagliptin and <i>S</i>-vildagliptin according to t...A rapid, accurate, and precise chiral Ultra fast liquid chromatography (UFLC) method was developed and validated for enantiomeric separation of racemic vildagliptin and <i>S</i>-vildagliptin according to the guidelines of the International Conference on Harmonization (ICH). The chiral chromatographic separation was achieved with a mobile phase consisting of 20 mM borax buffer (pH 9.0 ± 0.05), ACN, and 0.1% Triethylamine (50:50:0.1, v/v/v) at a flow rate of 1 ml/min using a chiralcel OD-RH column, tris(3,5-dimethyl phenyl carbamate) (250 mm × 4.6 mm, 5 μm) column. The UFLC analysis was monitored at 210 nm. The method showed good linearity with a regression coefficient (r<sup>2</sup>) of 0.999 in the range of 1 - 12 μg/ml for <i>S</i>-vilda. The detection limit (LOD), quantitation limit (LOQ), and the average percentage recovery for <i>S</i>-vilda were found to be 0.024, 0.075 μg/mL, and 99.19% to 100.4%, respectively. The percentages of relative standard deviation (% RSD) for intra- and inter-day precision were found to be 0.346% and 0.364%, respectively. The developed method proved to be reproducible as % RSD was <2% and it had robustness within the acceptable limit. The percentage purity of pharmaceutical preparations of <i>S</i>-vilda was found to be 99.19 w/w. The proposed chiral method can be put in application for the enantiomeric purity determination of <i>S</i>-vilda formulations.展开更多
Background:Forestry management modifies the diversity,structure,and functioning of intervened forests.Timber extraction reduces tree density and basal area,leading to changes in the communities of vascular epiphytes.T...Background:Forestry management modifies the diversity,structure,and functioning of intervened forests.Timber extraction reduces tree density and basal area,leading to changes in the communities of vascular epiphytes.The objective of this study was to evaluate the diversity and biomass of vascular epiphytes in Quercus trees remaining in two pine-oak forest stands that have been subjected to two stages of the Silvicultural Development Method(release cutting,and thinning)in comparison with an unharvested old-secondary forest in southern Mexico.For each treatment,richness of epiphytes present on 60 oak trees was recorded and their dry biomass estimated.We calculated the true diversity(Hill numbers)and beta diversity using the Jaccard coefficient of similarity,and generated rank abundance curves per taxonomic epiphyte group(bromeliads,orchids,ferns and others).For each treatment,the relationships between overall diversity and epiphyte biomass to the host trees basal area were analyzed using log linear models.Results:We recorded a total of 67 species of epiphytes species belonging to 10 families hosted by five species of oaks.The greatest species richness(^(0)D)was recorded in the old-secondary forest.Fewer common(^(1)D)and dominant(^(2)D)species were recorded in the release cutting than in the other treatments.Epiphyte diversity and biomass were both slightly related to host tree basal area.Composition of epiphytes was similar(60%)among treatments,although orchids,bromeliads,and other families were more diverse in the old-secondary forest.Most bromeliad species were shared across all treatments,although orchids presented the most exclusive species in the unharvested forest.The bromeliad Tillandsia seleriana provided the greatest contribution to biomass in all treatments,followed by the orchid Camaridium densum.Generalized linear models indicated that epiphyte diversity was significantly related to treatment,and epiphyte biomass to basal area of host trees.Conclusions:Although forest management affects diversity,composition,and abundance of vascular epiphytes,most of their diversity and biomass can be maintained despite timber harvesting.This requires sparing some mature oaks during logging,as they contribute to conservation,establishment,and development of epiphytic communities,and maintaining untreated areas as a source of propagules for these communities.展开更多
文摘Microsatellite marker （or Simple Sequence Repeate, SSR） is a marker technology based on DNA molecular length poly morphism. It is also one of the most commonly used molecular markers. Traditional SSR marker development methods are relatively time-consuming and mostly relying on the known genome sequence information while recently developed methods of SSR marker based on RAPD, ISSR-PCR SSR, the use of hybrid options, sequence tag SSR library access and screening EST-SSR have been widely used. This paper gave an overview of the methods mentioned above for the development of SSR markers.
基金supported by the Innovation Project for Graduates in UPC(Grant YCX2019016)the National Natural Science Foundation of China(Nos.51774306 and 51974346)+1 种基金the Science and Technology Support Plan for Youth Innovation of University in Shandong Province under Grant 2019KJH002the Major Scientific and Technological Projects of CNPC under Grant ZD2019-183-008。
文摘Carbonate reservoirs worldwide are complex in structure,diverse in form,and highly heterogeneous.Based on these characteristics,the reservoir stimulation technologies and fluid flow characteristics of carbonate reservoirs are briefly described in this study.The development methods and EOR technologies of carbonate reservoirs are systematically summarized,the relevant mechanisms are analyzed,and the application status of oil fields is catalogued.The challenges in the development of carbonate reservoirs are discussed,and future research directions are explored.In the current development processes of carbonate reservoirs,water flooding and gas flooding remain the primary means but are often prone to channeling problems.Chemical flooding is an effective method of tertiary oil recovery,but the harsh formation conditions require high-performance chemical agents.The application of emerging technologies can enhance the oil recovery efficiency and environmental friendliness to a certain extent,which is welcome in hard-to-recover areas such as heavy oil reservoirs,but the economic cost is often high.In future research on EOR technologies,flow field control and flow channel plugging will be the potential directions of traditional development methods,and the application of nanoparticles will revolutionize the chemical EOR methods.On the basis of diversified reservoir stimulation,combined with a variety of modern data processing schemes,multichannel EOR technologies are being developed to realize the systematic,intelligent,and cost-effective development of carbonate reservoirs.
文摘The oil oxidation characteristics of the whole temperature regions from 30 ℃ to 600 ℃ during oil reservoir air injection were revealed by experiments. The whole oil oxidation temperature regions were divided into four different parts: dissolving and inflation region, low temperature oxidation region, medium temperature oxidation region and high temperature oxidation region. The reaction mechanisms of different regions were explained. Based on the oil oxidation characteristics and filed tests results, light oil reservoirs air injection development methods were divided into two types: oxygen-reducing air flooding and air flooding;heavy oil reservoirs air injection in-situ combustion development methods were divided into two types: medium temperature in-situ combustion and high temperature in-situ combustion. When the reservoir temperature is lower than 120 ℃, oxygen-reducing air flooding should be used for light oil reservoir development. When the reservoir temperature is higher than 120 ℃, air flooding method should be used for light oil reservoir development. For a normal heavy oil reservoir, when the combustion front temperature is lower than 400 ℃, the development method is medium temperature in-situ combustion. For a heavy oil reservoir with high oil resin and asphalting contents, when the combustion front temperature is higher than 450 ℃, the development method at this condition is high temperature in-situ combustion. Ten years field tests of air injection carried out by PetroChina proved that air has advantages in technical, economical and gas source aspects compared with other gas agents for oilfield gas injection development. Air injection development can be used in low/super-low permeability light oil reservoirs, medium and high permeability light oil reservoirs and heavy oil reservoirs. Air is a very promising gas flooding agent.
文摘The research work was carried out for establishing a new Ultra Violet (UV)— Visible spectroscopy and Reverse phase-Ultra Fast Liquid Chromatography (RP-UFLC) method for the analysis and quantification of a biosimilar drug, Filgrastim. Filgrastim or recombinant methionyl granulocyte colony stimulating factor (rGCSF) is a glycoprotein. It has a biological action essential for proliferation and differentiation of hematopoetic and progenitor cells. The UV and RP-UFLC work was carried on a Shimadzu UV1800 Spectrophotometer and Shimadzu Prominence LC-20AD UFLC systems, respectively. The <i>λ</i><sub>max</sub> of filgrastim was found to be 215 nm. The correlation coefficient by UV spectroscopy was found to be 0.9994 for the concentration range of 1 to 3 μg/ml in double distilled water. The Reverse phase UFLC was done by using Phenomenex C4 (25 cm × 0.46 cm internal diameter) 15 μ, 300 A° analytical column. The optimized mobile phase for binary elution was Acetonitrile and double distilled water (80:20) with a flow rate of 1 ml/min. The retention time of drug was at 3.2 min. It was observed that the response of the detector was linear in the range of 5 - 15 μg/ml with correlation coefficient value of 0.999. After developing the methods, it was assured for the intended use by validation of the analytical parameters like linearity, accuracy, precision, limit of detection, limit of quantitation, ruggedness and robustness. The results of all the parameters for both the methods were found to be within the acceptance criteria as per the International Council for Harmonisation (ICH) guidelines.
文摘Dispersed and peripheral spaces in the urban core are influenced both by the trend towards constant growth as well as social ways of life which are constantly evolving. Following a connotation, these two factors therefore play a crucial role in defining the alternation of urban space--in particular, that of the centers. The main focus of this research article is on the methodology used in the survey and evaluation of ＂centralities＂ as well as their developments over the past four decades （1974-2014） in approaches to urban development that has been developed in Graz.~ The analysis has drawn on the four editions （＂evolution＂） of approaches to urban development as conceived by the city of Graz in order to examine their verbal characteristics in regard to centralities. At the same time, the analysis does not examine presentations of plans which exist in supplementary forms （e.g., explanatory reports and supplemented plans）--it restricts itself solely to the various plans set out in the STEKs.2 The highest degree of accuracy has been applied to the notion of ＂centralis＂ in approaches to urban development. The goal of the research project was to depict the modulation of the notion of ＂centrality＂ in the urban context as a space-forming dimension. Furthermore, it clearly shows the extent to which the notion of the ＂centre＂ （in the widest sense of the word） has become distanced from qualitative, spatial development and at the current time of urban development is experiencing a sort of Renaissance. In the field of ＂urban development＂, architectural references in the context of＂centrality＂ have scarcely been researched. This has led to the opening-up of a complex interdisciplinary research field. In order to make the complex architectural determinants of ＂centrality＂ more accessible to the participating disciplines, approaches to urban development have been explored in the form of a social and spatial analysis.
基金Shanghai Science and Technology Development Foundation (995107017)
文摘Linux-based Platform for Open Architecture Controller ( POAC ), a new open architecture controller and its modular developing method are discussed. POAC divides the application software of controller into the developing system and the application system. In the developing system, PAOC abstracts a series of function modules with unified data interface and function interface. In the application system, POAC defines the model of the architecture module, realizing the interoperability and interchangeability between the architecture modules. The modular developing method entities the users to make up an application system with some architecture modules, which consist of a set of function modules. The modular developing method decreases the developing time from the standard of controller architecture to the product.
文摘Viscous fluid flows contain abundant "physical phenomena and the viscous fluid dynamics is of wide applications in the fields of natural and engineering sciences. After the basic equations of viscousfluiddynamics (i.e., the Navier-Stokes equations) came out, one of the most important contributions to the discipline was the boundary layer (BL) theory and the BL equations presented by Prandtl
基金supported by the Key Research and Development Projects of the Ningxia Hui Autonomous Region(Grant no.2022BEG03161)。
文摘Brucellosis is a global public health issue that severely affects human health,Brucella melitensis is currently the predominant species in China.Brucella spondylitis is the primary cause of the debilitating and disabling complications[1].The lumbar vertebra was the most commonly affected site,followed by the thoracic,cervical,thoracolumbar,and lumbosacral segments,and back pain,fever,sweating,and fatigue were the most common symptoms[2].However,the diagnosis of Brucella spondylitis is challenging owing to its wide spectrum of clinical presentations,cross-reactions with other bacteria,and low strain isolation rate.Therefore,a timely and accurate diagnosis of spinal brucellosis is crucial for implementing an effective therapeutic plan and improving treatment outcomes.Droplet digital polymerase chain reaction(ddPCR)is widely used for low-abundance nucleic acid detection and is useful for diagnosing infectious diseases[3].Therefore,this study aimed to evaluate the ddPCR approach for the diagnosis of brucellosis with spondylitis to improve its clinical diagnostic capacity.
文摘Aim:Method for the deternination of erythromycin ethylsuccinale(EES)by ion suppression chromatography(ISC)was developed and the influenc factors on ISC were investigated.Methods:A Zorbax SB-C18 column was used with 0.02mol.L^(-1)potassium dihydrogen phosphate-acetonitrile(45:55)as mobile phase,The pH and proportion of the mobile phase showed the greatest influences on retention and selectivity.Therefore,the pH of mobile was adjusted to 6.8,the bhest acetonitrile proportion was 55%.The column temperature was maintained at(300±0.5)℃.Acetonitrile was used as solvent for the sample preparation because EES is more stable in it.The flow rate was 1.2mL.min^(-1)and UV detection was performed at 210nm.Results:Under these chromatographic conditions,the main component(erythromycin A ethylsuccinate)and its related substances were separated.The calibration curve showed good linearity over the range of 0.1-1.0mg.mL^(-1),and its correlation coefficient was 0.9998.Conclusion:The method is very suitable for the analysis of erythromycin ethylsuccinate.
文摘A rapid GC-FID method was developed to simultaneously determine residual levels of triethylamine(TEA), 1,1,3,3-tetramethylguanidine(TMG), and diisopropylamine(DIPA) in the synthetic route of an active pharmaceutical ingredient(API). Due to the severe absorption of amines on GC stationary phases,GC columns with various stationary phases were evaluated for optimal peak shape and reproducibility.The final conditions used the Agilent CP-Volamine column to resolve the three amines in 12 min. Various inlet liners were also screened to further improve the sensitivity of the analysis. The Restek Siltek~? liner was selected to achieve the desired detectability for the method. The quantitation limits were 4, 3, and 4 mg/mL for TEA, DIPA, and TMG in the presence of API, respectively. All three amines showed good linearity(r > 0.999) and recoveries(> 90%) over the concentration range of 3 to 16 mg/mL. The testing of residual amines was initially performed at the penultimate stage of the synthesis. However, this work demonstrates that TMG can act as a proton sponge to react with salicylic acid, the counter ion of the penultimate, to form a volatile component that elutes at a different retention time. Consequently, in the final method, these three amines were monitored in the final API to circumvent the matrix interference.Key parameters of the method were qualified per method validation requirements in ICH guidelines. The method was successfully applied for batch testing during development and implemented as an inprocess control procedure at manufacturing sites.
基金We are grateful to the support from the National Natural Science Foundation of China （NSFC） （31425002, 91231205, 81430011, 61303161, 31470220, and 31327001）, and the Frontier Science Research Program, the Soil-Microbe System Function and Regulation Program, and the Science and Technology Service Network Initiative （STS） from the Chinese Academy of Sciences （CAS）.
文摘Method development has always been and will continue to be a core driving force of microbiome science, In this perspective, we argue that in the next decade, method development in microbiome analysis will be driven by three key changes in both ways of thinking and technological platforms： ① a shift from dissecting microbiota structure by sequencing to tracking microbiota state, function, and intercellular interaction via imaging; ② a shift from interrogating a consortium or population of cells to probing individual cells; and ③a shift from microbiome data analysis to microbiome data science. Some of the recent methoddevelopment efforts by Chinese microbiome scientists and their international collaborators that underlie these technological trends are highlighted here. It is our belief that the China Microbiome Initiative has the opportunity to deliver outstanding ＂Made-in-China＂ tools to the international research community, by building an ambitious, competitive, and collaborative program at the forefront of method development for microbiome science.
基金This work is financially supported by the National Natural Science Foundation Project(No.51374222)National Major Project(No.2017ZX05032004-002)+2 种基金the National Key Basic Research&Development Program(No.2015CB250905)CNPC’s Major Scientific and Technological Project(No.2017E-0405)SINOPEC Major Scientific Research Project(No.P18049-1).
文摘This study clarifies the seepage characteristics of complex fractured pressure-sensitive reservoirs,and addresses a common technological problem,that is the alteration of the permeability degree of the reservoir bed(known to be responsible for changes in the direction and velocity of fluid flows between wells).On the basis of a new pressuresensitive equation that considers the fracture directional pressure-sensitive effect,an oil-gas-water three-phase seepage mathematical model is introduced,which can be applied to pressure-sensitive,full-tensor permeability,ultralow-permeability reservoirs with fracture-induced anisotropy.Accordingly,numerical simulations are conducted to explore the seepage laws for ultralow-permeability reservoirs.The results show that element patterns have the highest recovery percentage under a fracture angle of 45°.Accounting for the pressure-sensitive effect produces a decrease in the recovery percentage.Several patterns are considered:inverted five-seven-and nine-spot patterns and a cross-row well pattern.Finally,two strategies are introduced to counteract the rotation of the direction of the principal permeability due to the fracture directional pressure-sensitive effect.
文摘<strong>Context:</strong> Substandard and falsified medicines are circulating in low-income countries mostly without any control. We availed a simple and not expensive UV-Vis spectroscopic method to evaluate the quality of tramadol in Kisangani before and during the Covid-19 period. <strong>Methods:</strong> For the analytical quantitative method, an experimental design was applied to set up the optimal levels of the selected factors, namely, pH of dissolution medium, type of cuvette, and wavelength. Taking into account the capsule pharmaceutical formulation within 80 - 120 μg·mL<sup>-1</sup> concentration range, we analyzed 89 tramadol samples from pharmacies and hospitals of the six Kisangani municipalities. <strong>Results:</strong> pH showed a significant effect on absorbance, whereas quartz cuvette and wavelength did not. A typical 100 μg·mL<sup>-1</sup> tramadol solution gave an absorbance of 0.64 at 272 nm. Validation highlighted a matrix effect observed with a 6% bias. A correction factor of 0.9372 allowed to improve the accuracy profile, which were then totally included within the 10% acceptance limits. Quality control revealed that 25 samples out of 89 were not compliant in terms of manufacturing license, registration status in DRC and content as well. <strong>Conclusion:</strong> This study showed that the strengthening of analytical strategy in Kisangani is a need.
基金financially supported by the National Natural Science Foundation of China(Grant No.51279128)the National Natural Science Fund for Innovative Research Groups Science Foundation(Grant No.51321065)the Construction Science and Technology Project of Ministry of Transport of the People’s Republic of China(Grant No.2013328224070)
文摘A caisson breakwater is built on soft foundations after replacing the upper soft layer with sand. This paper presents a dynamic finite element method to investigate the strength degradation and associated pore pressure development of the intercalated soft layer under wave cyclic loading. By combining the undrained shear strength with the empirical formula of overconsolidation clay produced by unloading and the development model of pore pressure, the dynamic degradation law that describes the undrained shear strength as a function of cycle number and stress level is derived. Based on the proposed dynamic degradation law and M-C yield criterion, a dynamic finite element method is numerically implemented to predict changes in undrained shear strength of the intercalated soft layer by using the general-purpose FEM software ABAQUS, and the accuracy of the method is verified. The effects of cycle number and amplitude of the wave force on the degradation of the undrained shear strength of the intercalated soft layer and the associated excess pore pressure response are investigated by analyzing an overall distribution and three typical sections underneath the breakwater. By comparing the undrained shear strength distributions obtained by the static method and the quasi-static method with the undrained shear strength distributions obtained by the dynamic finite element method in the three typical sections, the superiority of the dynamic finite element method in predicting changes in undrained shear strength is demonstrated.
基金Financial support from the key project of the National Natural Science Foundation of China(No.71273118)is gratefully acknowledged
文摘Generally, the sequence decision of the development and utilization of Chinese mineral resources is based on national and provincial overall plan of the mineral resources. Such plan usually cannot reflect the relative size of the suitability of the development and utilization of mineral resources. To solve the problem, the paper has selected the gift condition, the market condition, the technological condition,socio-economic condition and environmental condition as the starting-points to analyze the influential factors of the priority-sequence of mineral resources' development and utilization. The above 5 conditions are further specified into 9 evaluative indicators to establish an evaluation indicator system. At last,we propose a decision model of the priority sequence based on grey relational analysis method, and figure out the observation objects by the suitability index of development. Finally, the mineral resources of a certain province in China were analyzed as an example. The calculation results indicate that silver(2.0057), coal(1.9955), zinc(1.9442), cement limestone(1.9077), solvent limestone(1.5624) and other minerals in the province are suitable for development and utilization.
文摘The research was carried out for establishing a new reverse phase-HPLC stability indicating method for the quantification of Rucaparib. The experiment was determined on Waters HPLC instrument using 996 photo-diode array detector. The separation was done by using symmetry C-18 ODS (25 cm × 0.46 cm internal diameter) 5 μm analytical column containing mobile phase of Phosphate buffer (0.02 M) and methanol [65:35% v/v] adjusted pH to 4.8 by adding dilute ortho phosphoric acid. The method was run at 1 ml·min<sup>-1</sup> at 286 nm detection. The drug was eluted at 5.484 min. After developing the method, it was assured for the intended use by validation which was done according to ICH Q2B guidelines. The analytical parameters checked were linearity, accuracy, repeatability, intermediate precision, limit of detection, limit of quantitation, ruggedness and robustness. It was observed that the response of the detector was linear in the range of 6 - 14 μg/ml with correlation coefficient of 0.999. The results of all the parameters were found to be within the acceptance criteria. The stability indicating assay method was established by using the samples generated by forced degradation process. The forced degradation was carried out by subjecting the drug to acid, alkali, thermal, oxidative and photolytic degradation and the results showed that the degradation products were successfully separated from the drug. Hence, this can be applied perfectly later for the analysis of quality of the rucaparib drug.
文摘The aim of this study was to develop a simple and derivatization free method for the Quantification of S-Epichlorohydrin in R-Epichlorohydrin by using a gas chromatography coupled with flame ionization detector (FID). Enantiopure epichlorohydrin was a valuable epoxide key starting material for preparing optically active Rivaroxaban. The enantiomeric separations of S-Epichlorohydrin and R-Epichlorohydrin were achieved on Gamaa-Dex-225 (30 meters × 0.25 mm I.D, 0.25 μm) column with a total run time of 30 min. Nitrogen was used as a carrier gas with constant pressure 25.0 psi. The critical experimental parameters such as, column selection, flow rate, injection volume and diluent were studied and optimized. Excellent correlation coeffient between peak responses and concentrations was >0.9998. The recoveries of S-Epichlorohydrin spiked in R-Epichlorohydrin were in the range from 98.2% to 102.8%. Limit of quantitation for S-Epichlorohydrin was sufficiently lower than limits specified by ICH. The method has validated as per International Conference on Harmonization (ICH) guidelines. A precise, accurate, linear and robust Gas Chromatography method was developed for the quantification of S-Epichlorohydrin in R-Epichlorohydrin for Rivaroxaban.
文摘A rapid, accurate, and precise chiral Ultra fast liquid chromatography (UFLC) method was developed and validated for enantiomeric separation of racemic vildagliptin and <i>S</i>-vildagliptin according to the guidelines of the International Conference on Harmonization (ICH). The chiral chromatographic separation was achieved with a mobile phase consisting of 20 mM borax buffer (pH 9.0 ± 0.05), ACN, and 0.1% Triethylamine (50:50:0.1, v/v/v) at a flow rate of 1 ml/min using a chiralcel OD-RH column, tris(3,5-dimethyl phenyl carbamate) (250 mm × 4.6 mm, 5 μm) column. The UFLC analysis was monitored at 210 nm. The method showed good linearity with a regression coefficient (r<sup>2</sup>) of 0.999 in the range of 1 - 12 μg/ml for <i>S</i>-vilda. The detection limit (LOD), quantitation limit (LOQ), and the average percentage recovery for <i>S</i>-vilda were found to be 0.024, 0.075 μg/mL, and 99.19% to 100.4%, respectively. The percentages of relative standard deviation (% RSD) for intra- and inter-day precision were found to be 0.346% and 0.364%, respectively. The developed method proved to be reproducible as % RSD was <2% and it had robustness within the acceptable limit. The percentage purity of pharmaceutical preparations of <i>S</i>-vilda was found to be 99.19 w/w. The proposed chiral method can be put in application for the enantiomeric purity determination of <i>S</i>-vilda formulations.
基金This study received research funding from the Rufford Foundation(Grant No.25259-1)from federal funds allotted to ECOSUR(NRM).
文摘Background:Forestry management modifies the diversity,structure,and functioning of intervened forests.Timber extraction reduces tree density and basal area,leading to changes in the communities of vascular epiphytes.The objective of this study was to evaluate the diversity and biomass of vascular epiphytes in Quercus trees remaining in two pine-oak forest stands that have been subjected to two stages of the Silvicultural Development Method(release cutting,and thinning)in comparison with an unharvested old-secondary forest in southern Mexico.For each treatment,richness of epiphytes present on 60 oak trees was recorded and their dry biomass estimated.We calculated the true diversity(Hill numbers)and beta diversity using the Jaccard coefficient of similarity,and generated rank abundance curves per taxonomic epiphyte group(bromeliads,orchids,ferns and others).For each treatment,the relationships between overall diversity and epiphyte biomass to the host trees basal area were analyzed using log linear models.Results:We recorded a total of 67 species of epiphytes species belonging to 10 families hosted by five species of oaks.The greatest species richness(^(0)D)was recorded in the old-secondary forest.Fewer common(^(1)D)and dominant(^(2)D)species were recorded in the release cutting than in the other treatments.Epiphyte diversity and biomass were both slightly related to host tree basal area.Composition of epiphytes was similar(60%)among treatments,although orchids,bromeliads,and other families were more diverse in the old-secondary forest.Most bromeliad species were shared across all treatments,although orchids presented the most exclusive species in the unharvested forest.The bromeliad Tillandsia seleriana provided the greatest contribution to biomass in all treatments,followed by the orchid Camaridium densum.Generalized linear models indicated that epiphyte diversity was significantly related to treatment,and epiphyte biomass to basal area of host trees.Conclusions:Although forest management affects diversity,composition,and abundance of vascular epiphytes,most of their diversity and biomass can be maintained despite timber harvesting.This requires sparing some mature oaks during logging,as they contribute to conservation,establishment,and development of epiphytic communities,and maintaining untreated areas as a source of propagules for these communities.
