A new multi-residue method based on solid-phase extraction (SPE) with centrifugation was developed for determination and quantitation of 67 pesticides in water samples. Two SPE cartridges were tested: Chromabond C18 a...A new multi-residue method based on solid-phase extraction (SPE) with centrifugation was developed for determination and quantitation of 67 pesticides in water samples. Two SPE cartridges were tested: Chromabond C18 and Oasis HLB. Parameters that influence the extraction efficiency such as the eluent volume, the sample loading volume, the addition of organic solvent to water sample, sorbent drying and elute concentration were optimized. The innovation of this work was the examination of the use of a centrifugation technique in both the drying and elution steps. When combined with centrifugation, the volume of the elution solvent was reduced to 2 mL and the time for sorbent drying decreased also to 10 min under vacuum. Under the optimized conditions, this method showed good recoveries higher than 65% - 68% for the 67 analyzed pesticides using the C18 and HLB cartridges with relative standard deviations lower than 9.7% - 12.3%. Limits of quantification were between 2 and 20 ng.L–1. The simplicity of the described method, use of less of organic solvent, short procedure time, and good recoveries demonstrate the advantages of this environmentally friendly approach for routine analysis of numerous samples.展开更多
A total of 18 ejaculates were collected, once per week, from six fertile stallions for three consecutive weeks in October and November, to compare motility over time between extenders using four semen processing treat...A total of 18 ejaculates were collected, once per week, from six fertile stallions for three consecutive weeks in October and November, to compare motility over time between extenders using four semen processing treatments. Four total aliquots of semen were used. Two aliquots of each semen collection were extended in either INRA96 or an experimental proprietary milk-based extender Walworth （WW） extender, and each was designed for multi-day storage of fresh chilled semen. Each aliquot was divided again, and either centrifuged at 600 μg for 10 min without cushion, or not centrifuged and extended to a final concentration of 25 × 10^6 spermatozoa/mL. The treatments evaluated were INRA96 without centrifugation （INRA-NC） or with centrifugation （INRA-C）, and Walworth extender without centrifugation （WW-NC） or with centrifugation （WW-C）. Total and progressive motility were measured using Sperm Vision~ CASA at 0, 24, 48 and 72 h post-collection. Samples were stored at 4 ℃. No differences were found between extenders in progressive （P = 0.13） or total motility （P = 0.14） over the four different time points without centrifugation. However, ejaculates processed in INRA-C group had the greater total and progressive motility （P 〈 0.05） over the four time points than ejaculates in the WW-C group. It was found that centrifugation and re-suspension of stallion semen in INRA96 improved the longevity of fresh chilled semen. However, when not using centrifugation, the Walworth extender proved to be as effective for maintaining spermatozoa motility across all time points as 1NRA96 , and may be an alternative for use in the equine breeding industry.展开更多
In the present paper we have observed the effect of discontinuous gradient two-step Percoll centrifugation on depleting mature T lymphocytes from normal bone marrow. The pre-/post-Percoll percentage of CD34+, and Leu4...In the present paper we have observed the effect of discontinuous gradient two-step Percoll centrifugation on depleting mature T lymphocytes from normal bone marrow. The pre-/post-Percoll percentage of CD34+, and Leu4+ cells in MNC was counted by using APAAP technique. As the two-step Percoll centrifugation is simple,and time saving, and decreases the incidence of contamination of cultured cells as well,This technique may be of value in serum-free culture of hematopoietic cells and immunological studies.展开更多
Background： Direct ZN （Ziehl-Neelsen） sputum smear microscopy for diagnosis of TB （tuberculosis） has low sensitivity, especially in TB/HIV co-infected patients. Sputum concentration by bleach （NaOCI） with sedim...Background： Direct ZN （Ziehl-Neelsen） sputum smear microscopy for diagnosis of TB （tuberculosis） has low sensitivity, especially in TB/HIV co-infected patients. Sputum concentration by bleach （NaOCI） with sedimentation has been used to increase the sensitivity of sputum smear microscopy in many settings but with varying results. Objective： To determine whether bleach plus centrifugation significantly improves the detection of AFB （acid-fast bacilli） in ZN smear-negative sputum specimens. Methods： Three hundred and seventy sputum specimens were collected from new TB suspects attending a Nairobi referral district hospital and processed for direct microscopy using ZN technique and culture on Lowenstein Jensen Media. All smear-negative specimens were treated with 3.5% bleach and left to stand for 30 min before centrifugation. The bleach treated smears were processed and examined using ZN technique. Results： Of the 370 specimens, 200 （54%） were positive culture. The number of sputum samples that were smear-positive by direct ZN was 138 （37.2%）, with a sensitivity of 66%. After treatment of direct ZN smear-negative specimens with 3.5% bleach and centrifugation, the total number of AFB smear-positive samples increased to 171 with an increase in sensitivity of 66% to 81.1% （15.1%）. Conclusion： In this study, bleach with centrifugation significantly increased the yield of sputum smear microscopy. Further evaluation of these techniques in routine programmes is required especially in settings where the burden of TB/HIV is high.展开更多
Background： Density gradient centrifugation was reported as a technique of semen preparation in assisted reproductive techniques in humans and animals. This technique was found to be efficient in improving semen qual...Background： Density gradient centrifugation was reported as a technique of semen preparation in assisted reproductive techniques in humans and animals. This technique was found to be efficient in improving semen quality after harmful techniques such as cryopreservation. Recently a modified technique, single layer centrifugation,was proposed as a technique providing a large amount of high quality spermatozoa, and this treatment was performed before conservation. Single layer centrifugation has been studied prevalently in stallions and in boars,but limited data were available for bulls. Occasionally bulls are known to experience a transient reduction in semen quality, thus techniques that allow improvement in semen quality could be applied in this context. The aim of this study was the evaluation of single layer and double layer centrifugation by the use of iodixanol, compared with conventional centrifugation and non-centrifuged semen, on the sperm characteristics during the cryopreservation process in bulls with normal and poor semen quality.Results： Single layer centrifugation and double layer centrifugation both significantly increased the percentage of normal spermatozoa and decreased the percentage of non-sperm cells in poor quality samples, while both were ineffective in those of normal quality. Sperm characteristics in poor quality samples increased after single layer centrifugation and double layer centrifugation, reaching values similar to those recorded in normal samples, and this trend is maintained after equilibration and after cryopreservation. On the other hand, SLC and DLC resulted in a consistent reduction in the spermatozoa recovered, and this resulted in a reduction of the absolute amount of spermatozoa cryopreserved in the normal samples, without a clear improvement in sperm characteristics in this type of sample.Conclusions： These data suggested that both SLC and DLC could be performed in practice, but their application should be limited to the cases in which the quality of the spermatozoa recovered is more important than the total amount of spermatozoa.展开更多
A significant number of stallions produce low quality ejaculates with high sensibility to chilling. Single Layer Centrifugation (SLC) with Andro-coll-ETM has been presented as an efficient method of selecting good qua...A significant number of stallions produce low quality ejaculates with high sensibility to chilling. Single Layer Centrifugation (SLC) with Andro-coll-ETM has been presented as an efficient method of selecting good quality spermatozoa. In the current study, changes in sperm quality (motility, viability, acrosome integrity and DNA damage) occurring during storage at 5?C for a maximum of 72 h, were investigated. For that, one ejaculate from 12 stallions was split in two aliquots: control and SLC-selected. Both aliquots were chilled and stored at 5?C and spermatozoa were evaluated for motility, viability and acrosome integrity at 24, 48 and 72 h post collection. DNA damage was evaluated at 48 h post collection using the comet assay. In the SLC-selected aliquots, there was a significant improvement in terms of progressive motility (0 h: P = 0.005;24 h: P 0.05). SLC with Androcoll-ETM improved semen quality prolonging sperm longevity of chilled semen (P = 0.012). This positive effect was more evident in ejaculates most sensitive to chilling that had a sharp decrease in motility in the first 24 h of refrigeration and for all ejaculates at 72 h post-chilling. Therefore, this method reveals to be a useful technique for selecting spermatozoa and maintain sperm quality during storage.展开更多
This study used specularite, a high-gradient magnetic separation concentrate, as a raw material in reverse flotation.An iron concentrate with a grade of 65.1 wt% and a recovery rate of 75.31% were obtained.A centrifug...This study used specularite, a high-gradient magnetic separation concentrate, as a raw material in reverse flotation.An iron concentrate with a grade of 65.1 wt% and a recovery rate of 75.31% were obtained.A centrifugal concentrator served as the deep purification equipment for the preparation of iron oxide red pigments, and its optimal rotating drum speed, feed concentration, and other conditions were determined.Under optimal conditions, a high-purity iron oxide concentrate with a grade of 69.38 wt% and a recovery rate of 80.89% were obtained and used as a raw material for preparing iron oxide red pigment.Calcining with sulfuric acid produced iron red pigments with different hues.Simultaneously, middlings with a grade of 60.20 wt% and a recovery rate of 17.51% were obtained and could be used in blast furnace ironmaking.High-value utilization of specularite beneficiation products was thus achieved.展开更多
We investigated whether an ordinary centrifuge can achieve the standard centrifugal effect required according to specifications for infectious disease screening using the Abbott i2000.Samples were collected and centri...We investigated whether an ordinary centrifuge can achieve the standard centrifugal effect required according to specifications for infectious disease screening using the Abbott i2000.Samples were collected and centrifuged following a standard operating procedure(SOP).They were then divided into three groups according to the results of the initial screening tests:a negative group,weak-positive group,and positive group.Twenty negative samples and all weak-positive and positive samples were re-analyzed.Two tubes for each re-analyzed sample were centrifuged simultaneously,one for 10 min at 10000x g,per recommendations,and one for 10 min at 2750^g.No significant difference was found between the groups using different centrifugal forces.There was a strong correlation in the quantitative values between the two conditions of centrifugation.Consistency analysis showed a Cronbach's alpha>0.8 for detection of Treponema pallidum,human immunodeficiency virus(HIV),hepatitis C virus(HCV),and hepatitis B surface antigen in the three groups(negative group,weak-positive group,and positive group)under different centrifugation conditions.Strong consistency was found under different centrifugal conditions,regardless of the initial testing results.In conclusion,we conducted centrifugation steps in duplicate,according to infectious disease screening protocols.Our study showed that all samples should be centrifuged using a recommended relative centrifugal force after a proper clotting time,as in the standard operating procedure of our laboratory.In this way,we were able to obtain the same results using an ordinary centrifuge as those obtained using a high-speed centrifuge,such as the Abbott i2000.展开更多
The study aimed to investigate the effects of centrifugation of stallion semen on progressive sperm motility over a 72-hour period;and determine if the protein marker,precursor of A-kinase anchor protein 4(pro-AKAP4),...The study aimed to investigate the effects of centrifugation of stallion semen on progressive sperm motility over a 72-hour period;and determine if the protein marker,precursor of A-kinase anchor protein 4(pro-AKAP4),may be maintained at a higher level over time when compared to non-centrifuged samples.Pro-AKAP4 has been studied for its function in stabilizing the structure of spermatozoa and its use as a marker for fertilizing capacity of spermatozoa.Semen collections were obtained from four fertile,commercially used Standardbred stallions collected three times each.Semen samples were diluted to a final concentration of 50 million total cells per milliliter.One extended aliquot of semen from each collection was used for the non-centrifuged treatment,and one extended aliquot of semen was centrifuged at 750×g for 10 min.The supernatant from the centrifuged sample was then removed with a 10 mL plastic transfer pipette,and the spermatozoa cell pellet was suspended in fresh extender to a final concentration of 50 million total cells per milliliter.Both centrifuged and non-centrifuged samples from each collection were stored in Equine Express II stallion semen shipping containers for 72 h and fresh ice packs were added to each container every 24 h.Both progressive sperm motility and levels of pro-AKAP4 were determined at times 0,12,24,48 and 72 h after collection.Differences were found between stallions,times and treatments with the main finding being that pro-AKAP4 concentration in centrifuged samples was maintained at a much higher level over the 72-hour period studied.展开更多
Objective:Sperm preparation techniques and cryopreservation are widely used in assisted reproductive techniques(ART).How to improve the quality of sperm management is a matter of great concern.Phospholipase C-zeta(PLC...Objective:Sperm preparation techniques and cryopreservation are widely used in assisted reproductive techniques(ART).How to improve the quality of sperm management is a matter of great concern.Phospholipase C-zeta(PLCζ)is considered a sperm-specific agent that activates oocyte activation and thus playing a crucial role in male fertility.However,the potential mechanisms by which semen processing and cryopreservation on PLCζcontribute to keyhole have not been addressed.Methods:In this study,semen samples were taken from have not been addressed 10 normozoospermic men.Each semen sample was assigned to the following groups:density gradient centrifugation(DGC)as control,microfluidic sorting,and cryopreservation.Sperm parameters of molity,viability,membrane integrity,and intracellular ROS were evaluated during sperm preparation and cryopreservation.The expression of PLCζin human sperm was determined by immunofluorescence and western blotting.Results:The results showed that molity,viability,and membrane integrity decreased in cryopreservation group.Intracellular ROS were also significantly increased compared to the the control group.There was no significant difference between DGC and microfluidic sorting group.Our investigation revealed that total levels of PLCζwere comparable between DGC and microfluidic sorting,but there were significantly reduced levels of PLCζafter cryopreservation as quantified by both immunofluorescenceand immunoblotting.PLCζimmunofluorescence in sperm revealed different PLCζlocalization patterns around the acrosomal(Ac),equatorial(Eq),post-acrosomal(PA)areas of sperm heads,and their combination.The predominant patterns of PLCζlocalization in DGC were similar to that of microfluidic sorting,with strong,with staining.In contrast,PLCζstaining in freeze-thawed sperm was considerably weaker fluorescence intensity.Conclusion:This study clarified the mechanism of sperm preparation and cryopreservation underlying effect on sperm characteristic,accompanied with PLCζexpresion.We demonstrated that microfluidic sorting provides a highly efficient preparation method for clinical selection of PLCζ-expressing sperm comparable to DGC gene expression.It is suggested that the cryopreservation of sperm has a significant detrimental effect on PLCζ.展开更多
The pre-analytical steps in blood-based liquid biopsy,involving sample collection techniques and storage conditions,play a critical role in ensuring the integrity and reliability of collected samples.These steps have ...The pre-analytical steps in blood-based liquid biopsy,involving sample collection techniques and storage conditions,play a critical role in ensuring the integrity and reliability of collected samples.These steps have a directly impact on the accuracy and reliability of test results and are therefore of utmost importance.Mass spectrometry(MS)-based proteomics is an exceptionally powerful tool in the field of liquid biopsy.It enables the comprehensive analysis of the protein content within biological specimens,providing valuable insights into the underlying mechanisms and pathogenesis of diseases.In this study,we aim to explore the variations in the protein landscape between serum and plasma specimens and evaluate the impact of delayed centrifugation on LC/MS-analyzed protein profiles.We seek to provide recommendations on optimal pre-analytical protocols for MS-based proteomics studies.This will enhance the accuracy and reliability of liquid biopsy for precision medicine,ultimately leading to improved patient outcomes.展开更多
In this study,synthetic wastewater containing 110μg/L arsenate(As(V)),0-20 mg/L fulvic acid(FA),and 0-12.3 mg/L phosphate was treated with 3 mg/L Fe3+.The mechanisms of FA and phosphate effects on As(V)removal by fer...In this study,synthetic wastewater containing 110μg/L arsenate(As(V)),0-20 mg/L fulvic acid(FA),and 0-12.3 mg/L phosphate was treated with 3 mg/L Fe3+.The mechanisms of FA and phosphate effects on As(V)removal by ferric chloride were determined using 0.22-10μm pore-size filtration,Zetasizer analysis,and in situ flow through cell ATR-FTIR.The results showed that up to 20mg/L FA had almost no effect on the solubility of ferric hydroxide precipitates and adsorption of As(V)by the precipitates.When FA concentration increased from 0 to 20 mg/L,the adsorption of FA led to higher negative zeta potential of the precipitates and the strong electrostatic repulsion between the precipitates decreased the particle size of ferric hydroxide flocs fromlarger than 10μmto smaller than 1μm.In the presence of 5-20 mg/L FA,46%-63%As(V)was adsorbed onto the flocs with particle size in the range of 0.45-1μm.On the other hand,phosphate did not affect the size of ferric hydroxide flocs and significantly increased the dissolved As(V)concentration because it competed with As(V)for adsorption sites on ferric hydroxide precipitates.The addition of 5mg/L cationic organic flocculant significantly reduced the effect of FA on As(V)removal,but did not reduce the effect of phosphate on As(V)removal.The findings of this study will help develop effective arsenic treatment techniques and predict the mobility of arsenic in the environment.展开更多
Discovery of spermatozoa during the 17^(th) century led to developing technologies for semen analysis in the early 1900s,and then,standard techniques were implemented during the 20^(th) century.Semen analysis has a pi...Discovery of spermatozoa during the 17^(th) century led to developing technologies for semen analysis in the early 1900s,and then,standard techniques were implemented during the 20^(th) century.Semen analysis has a pivotal role in the male infertility evaluation,and azoospermia is an important finding.Azoospermia is identified in 15%of infertile men.However,the accurate laboratory assessment of azoospermia poses certain technical challenges.Laboratories currently perform semen assessment with great variability;thus,a standard method should be used.Planning suitable management and determining the cause of infertility require a precise evaluation of azoospermia.This review aims to address the definition of azoospermia and highlight laboratory methods in the assessments of azoospermia.Basic methods such as centrifugation,repeat pellet analysis,and staining and advanced methods such as genetic testing and biomarkers have been discussed.These methods have helped in standardizing the protocol for accurate azoospermia assessments with less variability.展开更多
This study established a method using gas chromatography-electrostatic field Orbitrap high-resolution mass spectrometry(Orbitrap GC-MS)for the simultaneous determination of 70 organic pollutants across 4 categories:or...This study established a method using gas chromatography-electrostatic field Orbitrap high-resolution mass spectrometry(Orbitrap GC-MS)for the simultaneous determination of 70 organic pollutants across 4 categories:organochlorine pesticides(OCPs),polycyclic aromatic hydrocarbons(PAHs),polychlorinated biphenyls(PCBs),and phthalates(PAEs)in infant cereal-based supplementary foods.Techniques integrating cryogenic centrifugation and lipid and protein adsorbent(LPAS)purification were employed.The precise mass numbers of target compounds were determined by Orbitrap GC-MS in full-scan mode(Full MS),which effectively minimized matrix interferences in these foods.Method validation on rice flour samples demonstrated that the 70 compounds exhibited excellent linearity within their respective mass concentration ranges,with correlation coefficients all exceeding 0.995.The detection limits for this method ranged 0.10–1.00μg/kg,while the quantification limits varied 0.3–3.0μg/kg,meeting the established detection requirements.The average spike recovery of the 70 compounds at 3 spiked levels(5,20,and 100μg/kg)ranged 75.3%–119.3%,with relative standard deviations ranging 1.8%–10.8%.Both inter-day and intra-day precision demonstrated relative standard deviation values below 15%.This method was applied to analyze 100 samples of commercial infant cereal-based supplementary food,revealing the presence of PAEs and PAHs in 12.0%of the samples.Notably,no OCPs or PCBs were detected.The detected concentrations of benzo[a]pyrene(Ba P)and dibutyl phthalate(DBP)were(4.2±0.1)and(1.8±0.3)μg/kg,respectively.This method is straightforward,highly sensitive,and suitable for the rapid screening and confirmation of 70 organic pollutants in infant cereal-based supplementary foods.展开更多
Objective:How to increase the long-term retention rate of autologous fat grafting has been widely discussed.This study aimed to evaluate long-term fat graft retention rates for the most widely used fat processing meth...Objective:How to increase the long-term retention rate of autologous fat grafting has been widely discussed.This study aimed to evaluate long-term fat graft retention rates for the most widely used fat processing methods in the area of facial esthetic surgery,including centrifugation,filtration,and sedimentation,using three-dimensional(3D)imaging.Data Sources:PubMed,Embase,Wiley/Cochrane Library,and Web of Science databases were comprehensively searched from inception to July 2018 according to the guidelines of the American Society of Plastic Surgeons Fat Graft Task Force Assessment Methodology.Study Selection:Articles were screened using predetermined inclusion and exclusion criteria.Data collected included patient characteristics,follow-up devices,fat grafting techniques,and clinical outcomes.Patient cohorts were pooled,and fat graft retention rates were calculated.Complications were summarized according to different clinical characteristics.Results:Of 77 articles,10 clinical studies met the inclusion criteria and reported quantified measurement outcomes with 3D imaging which provide precise volumetric data with approximately 2%standard deviation compared to real volumes.Data of 515 patients were included.Fat grafting retention varied from 21%to 82%.We found filtration and centrifugation techniques could result in better retention outcomes.However,retention varied within each processing technique,with no significant difference among the 3 techniques.Twenty-two complications were reported among 515 patients,including donor-site hematoma(1 case),mild postoperative erythema(2 cases),mild volumetric asymmetries(2 cases),chronic edema(2 cases),overcorrection(2 cases),skin irregularity(6 cases),and headache or dysesthesia(7 cases).Conclusions:Filtration and centrifugation techniques may result in better fat grafting retention outcomes than gravity sedimentation;however,more accurate statistical evidence is needed.Controversies continue to exist with respect to the performance of the different fat-processing techniques in fat graft retention.展开更多
Objective:Density gradient centrifugation(DGC),swim up(SU),or a combination of DGC and SU is used to prepare sperm for infertility treatments using assisted reproductive technologies(ARTs).This study aimed to investig...Objective:Density gradient centrifugation(DGC),swim up(SU),or a combination of DGC and SU is used to prepare sperm for infertility treatments using assisted reproductive technologies(ARTs).This study aimed to investigate the efficiency of a new device for detecting sperm DGC.Methods:Sperm samples were collected from 119 males who required semen analysis at three differentin vitro fertilization(IVF)centers(71 samples from Center A,28 samples from Center B,and 20 samples from Center C).Semen samples were divided into two groups for DGC:(1)a normal centrifugation tube and(2)a specially designed RC-Tube.The sperm concentration,motility,and DNA fragmentation index(DFI)were assessed using DGC.Sperm concentration and motility were assessed using a MAKLER counting chamber.Sperm DFI was measured and analyzed using flow cytometry using a DFI Kit.Results:There were no significant differences in sperm concentrations recovered following DGC between the two groups(31.1%±1.7%vs.28.8%±1.3%).Sperm motility was not significantly different following the DGC procedure in both groups(77.6%±1.6%.vs.75.8%±1.6%).The percentage of sperm DFI was also not significantly different following DGC between the two groups(10.4%±1.0%vs.10.5%±1.0%).Conclusions:The newly designed RC-Tube is efficient for sperm DGC and can be used to simplify sperm preparation for infertility treatment.展开更多
Objective:The purpose of this study was to evaluate the sperm motility and DNA integrity at different temperatures to analyze whether the sperms are suitable on the second day for insemination of in vitro matured oocy...Objective:The purpose of this study was to evaluate the sperm motility and DNA integrity at different temperatures to analyze whether the sperms are suitable on the second day for insemination of in vitro matured oocytes by intra-cytoplasmic sperm injection(ICSI)following density gradient centrifugation(DGC)and swim-up(SU)procedures.Methods:Semen samples were collected from 30 outpatients who visited the Center for Reproductive Medicine for semen analyses.Following sperm selection by DGC and SU procedures,the liquified semen samples were divided into three groups and incubated at 4,25,and 37°C,respectively.Following incubation for 24,48,and 72 hours,the sperm motility and sperm DNA fragmentation index(DFI)were analyzed.Results:Following the combination of DGC and SU procedures,the sperm motility(91.8%±8.6%vs.50.8%±13.1%)and DFI(5.1%±7.9%vs.13.0%±11.6%)were significantly improved(P<0.01)compared to those without any treatment.The sperm motility of the 3 groups significantly declined(P<0.05)post-incubation compared to that of the groups prior incubation.However,sperm motility significantly increased(76.9%±10.4%)(P<0.05)at 25°C compared to that of the other 2 groups(53.5%±11.0%and 47.6%±10.2%).Sperm DFI significantly increased(P<0.05)at 37°C following incubation for 24 and 72 hours in comparison to that of the other 2 groups.However,the sperm DFI did not significantly increase when the sperm samples were incubated at 4(5.7%±5.9%)and 25°C(6.8%±5.6%)for 24 hours compared to that before incubation(5.1%±7.9%).Conclusions:These results indicate that the sperm quality,in terms of motility and DFI,can be efficiently improved by DGC in combination with SU.Following which,the sperm samples can be incubated at 25°C and be used on the second day for insemination of in vitro matured oocytes by ICSI.展开更多
Cavitation is an unavoidable phenomenon in the operation of centrifugal pumps.Prolonged cavitation can cause significant damage to the components of the flow channel,and in severe cases,it may even interfere with the ...Cavitation is an unavoidable phenomenon in the operation of centrifugal pumps.Prolonged cavitation can cause significant damage to the components of the flow channel,and in severe cases,it may even interfere with the normal energy exchange processes within the pump.Therefore,effective monitoring of cavitation in centrifugal pumps is crucial.This article presents a study that approaches the issue from an acoustic perspective,using experimental methods to gather and analyze acoustic data at the inlet and outlet of centrifugal pumps across various flow rates,with hydrophones as the primary measuring instruments.Results show that flow rate significantly affects noise levels in both non-cavitation and mild cavitation stages,with noise increasing as the flow rate rises.As the cavitation margin(NPSHa)decreases,inlet and outlet noise trends diverge:inlet noise drops sharply,while outlet noise initially increases before sharply decreasing.Both exhibit a distinct zone of abrupt change,where NPSHa values offer earlier cavitation detection than traditional methods.The noise at the pump’s inlet and outlet primarily consists of discrete and broadband noise,with most energy concentrated at discrete frequencies—shaft frequency(24 Hz),blade frequency(144 Hz),and their harmonics.As NPSHa decreases,the inlet’s discrete and broadband noise frequencies decline,while they increase at the outlet.Monitoring changes in these spectrum characteristics provides an additional means of predicting cavitation onset.展开更多
A centrifugal pump with a specific speed ns=67 is considered in this study to investigate the impact of blade cutting(at the outlet edge)on the fluid-induced noise,while keeping all the other geometric parameters unch...A centrifugal pump with a specific speed ns=67 is considered in this study to investigate the impact of blade cutting(at the outlet edge)on the fluid-induced noise,while keeping all the other geometric parameters unchanged.The required unsteady numerical calculations are conducted by applying the RNG k-εturbulence model with the volute dipole being used as the sound source.The results indicate that the internal pressure energy of the centrifugal pump essentially depends on the blade passing frequency and its low-frequency harmonic frequency.Moreover,the pressure pulsation distribution directly affects the noise caused by the centrifugal pump.The sound pressure inside and outside the centrifugal pump and the sound power at the blade passing frequency gradually decrease increasing cutting distance of the impeller blades.When the cutting percentage is 1.21%,that is,the clearance ratio between impeller blade and tongue is 8.57%,the comprehensive performance of the centrifugal pump is the best.展开更多
The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,...The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,experience one-way cyclic tensile loads at inclinations ranging from 0°(horizontal)to 90°(vertical).However,the combined effects of cyclic loading and load inclination remain inadequately understood.This study presents findings from centrifuge tests conducted on rough rigid piles installed in dense sand samples.The results demonstrate that load inclinations significantly influence both cyclic response and ultimate capacity of the piles.Based on the observed cyclic response characteristics,the vertical cyclic load amplitude should not exceed 25%of the ultimate bearing capacity to maintain pile stability.A power expression(with exponent m values ranging from 0.055 to 0.065)is proposed for predicting cumulative pile displacement under unidirectional cyclic loading at inclinations from 0°to 60°.The cyclic response exhibits reduced sensitivity to horizontal cyclic load magnitude,with m-value increasing from 0.06 to 0.14 as load magnitude increases from 0.3 to 0.9.For piles maintaining stability under oblique cyclic loading,the average normalized secant stiffness exceeds 1 and increases with decreasing inclination,indicating enhanced pile stiffness under cyclic loading.For load inclinations below 30°,pile stiffness can be determined using logarithmic function.展开更多
文摘A new multi-residue method based on solid-phase extraction (SPE) with centrifugation was developed for determination and quantitation of 67 pesticides in water samples. Two SPE cartridges were tested: Chromabond C18 and Oasis HLB. Parameters that influence the extraction efficiency such as the eluent volume, the sample loading volume, the addition of organic solvent to water sample, sorbent drying and elute concentration were optimized. The innovation of this work was the examination of the use of a centrifugation technique in both the drying and elution steps. When combined with centrifugation, the volume of the elution solvent was reduced to 2 mL and the time for sorbent drying decreased also to 10 min under vacuum. Under the optimized conditions, this method showed good recoveries higher than 65% - 68% for the 67 analyzed pesticides using the C18 and HLB cartridges with relative standard deviations lower than 9.7% - 12.3%. Limits of quantification were between 2 and 20 ng.L–1. The simplicity of the described method, use of less of organic solvent, short procedure time, and good recoveries demonstrate the advantages of this environmentally friendly approach for routine analysis of numerous samples.
文摘A total of 18 ejaculates were collected, once per week, from six fertile stallions for three consecutive weeks in October and November, to compare motility over time between extenders using four semen processing treatments. Four total aliquots of semen were used. Two aliquots of each semen collection were extended in either INRA96 or an experimental proprietary milk-based extender Walworth （WW） extender, and each was designed for multi-day storage of fresh chilled semen. Each aliquot was divided again, and either centrifuged at 600 μg for 10 min without cushion, or not centrifuged and extended to a final concentration of 25 × 10^6 spermatozoa/mL. The treatments evaluated were INRA96 without centrifugation （INRA-NC） or with centrifugation （INRA-C）, and Walworth extender without centrifugation （WW-NC） or with centrifugation （WW-C）. Total and progressive motility were measured using Sperm Vision~ CASA at 0, 24, 48 and 72 h post-collection. Samples were stored at 4 ℃. No differences were found between extenders in progressive （P = 0.13） or total motility （P = 0.14） over the four different time points without centrifugation. However, ejaculates processed in INRA-C group had the greater total and progressive motility （P 〈 0.05） over the four time points than ejaculates in the WW-C group. It was found that centrifugation and re-suspension of stallion semen in INRA96 improved the longevity of fresh chilled semen. However, when not using centrifugation, the Walworth extender proved to be as effective for maintaining spermatozoa motility across all time points as 1NRA96 , and may be an alternative for use in the equine breeding industry.
文摘In the present paper we have observed the effect of discontinuous gradient two-step Percoll centrifugation on depleting mature T lymphocytes from normal bone marrow. The pre-/post-Percoll percentage of CD34+, and Leu4+ cells in MNC was counted by using APAAP technique. As the two-step Percoll centrifugation is simple,and time saving, and decreases the incidence of contamination of cultured cells as well,This technique may be of value in serum-free culture of hematopoietic cells and immunological studies.
文摘Background： Direct ZN （Ziehl-Neelsen） sputum smear microscopy for diagnosis of TB （tuberculosis） has low sensitivity, especially in TB/HIV co-infected patients. Sputum concentration by bleach （NaOCI） with sedimentation has been used to increase the sensitivity of sputum smear microscopy in many settings but with varying results. Objective： To determine whether bleach plus centrifugation significantly improves the detection of AFB （acid-fast bacilli） in ZN smear-negative sputum specimens. Methods： Three hundred and seventy sputum specimens were collected from new TB suspects attending a Nairobi referral district hospital and processed for direct microscopy using ZN technique and culture on Lowenstein Jensen Media. All smear-negative specimens were treated with 3.5% bleach and left to stand for 30 min before centrifugation. The bleach treated smears were processed and examined using ZN technique. Results： Of the 370 specimens, 200 （54%） were positive culture. The number of sputum samples that were smear-positive by direct ZN was 138 （37.2%）, with a sensitivity of 66%. After treatment of direct ZN smear-negative specimens with 3.5% bleach and centrifugation, the total number of AFB smear-positive samples increased to 171 with an increase in sensitivity of 66% to 81.1% （15.1%）. Conclusion： In this study, bleach with centrifugation significantly increased the yield of sputum smear microscopy. Further evaluation of these techniques in routine programmes is required especially in settings where the burden of TB/HIV is high.
基金supported by a grant from Regione Abruzzo (P.O. FSE Abruzzo 2007 – 2013, Action 4, Type 4.1)the Provincial Breeders Federation of Trento, especially Dr. Claudio Valorz, for their support
文摘Background： Density gradient centrifugation was reported as a technique of semen preparation in assisted reproductive techniques in humans and animals. This technique was found to be efficient in improving semen quality after harmful techniques such as cryopreservation. Recently a modified technique, single layer centrifugation,was proposed as a technique providing a large amount of high quality spermatozoa, and this treatment was performed before conservation. Single layer centrifugation has been studied prevalently in stallions and in boars,but limited data were available for bulls. Occasionally bulls are known to experience a transient reduction in semen quality, thus techniques that allow improvement in semen quality could be applied in this context. The aim of this study was the evaluation of single layer and double layer centrifugation by the use of iodixanol, compared with conventional centrifugation and non-centrifuged semen, on the sperm characteristics during the cryopreservation process in bulls with normal and poor semen quality.Results： Single layer centrifugation and double layer centrifugation both significantly increased the percentage of normal spermatozoa and decreased the percentage of non-sperm cells in poor quality samples, while both were ineffective in those of normal quality. Sperm characteristics in poor quality samples increased after single layer centrifugation and double layer centrifugation, reaching values similar to those recorded in normal samples, and this trend is maintained after equilibration and after cryopreservation. On the other hand, SLC and DLC resulted in a consistent reduction in the spermatozoa recovered, and this resulted in a reduction of the absolute amount of spermatozoa cryopreserved in the normal samples, without a clear improvement in sperm characteristics in this type of sample.Conclusions： These data suggested that both SLC and DLC could be performed in practice, but their application should be limited to the cases in which the quality of the spermatozoa recovered is more important than the total amount of spermatozoa.
基金partially financed by Projects PTDC/CVT/108456/2008(FCT)and COMPETE:FCOMP-01-0124-FEDER-009565(FEDER),“Development of methods to increase the fertilizing ability of chilled and frozen stallion semen:a multidisciplinary ap-proach”.
文摘A significant number of stallions produce low quality ejaculates with high sensibility to chilling. Single Layer Centrifugation (SLC) with Andro-coll-ETM has been presented as an efficient method of selecting good quality spermatozoa. In the current study, changes in sperm quality (motility, viability, acrosome integrity and DNA damage) occurring during storage at 5?C for a maximum of 72 h, were investigated. For that, one ejaculate from 12 stallions was split in two aliquots: control and SLC-selected. Both aliquots were chilled and stored at 5?C and spermatozoa were evaluated for motility, viability and acrosome integrity at 24, 48 and 72 h post collection. DNA damage was evaluated at 48 h post collection using the comet assay. In the SLC-selected aliquots, there was a significant improvement in terms of progressive motility (0 h: P = 0.005;24 h: P 0.05). SLC with Androcoll-ETM improved semen quality prolonging sperm longevity of chilled semen (P = 0.012). This positive effect was more evident in ejaculates most sensitive to chilling that had a sharp decrease in motility in the first 24 h of refrigeration and for all ejaculates at 72 h post-chilling. Therefore, this method reveals to be a useful technique for selecting spermatozoa and maintain sperm quality during storage.
基金jointly funded by the National Natural Science Foundation of China (No.51304181)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences (No.QYZDJ-SSW-JSC021)the Key Research Program of Chinese Academy of Sciences (No.ZDRW-ZS-2018-1)。
文摘This study used specularite, a high-gradient magnetic separation concentrate, as a raw material in reverse flotation.An iron concentrate with a grade of 65.1 wt% and a recovery rate of 75.31% were obtained.A centrifugal concentrator served as the deep purification equipment for the preparation of iron oxide red pigments, and its optimal rotating drum speed, feed concentration, and other conditions were determined.Under optimal conditions, a high-purity iron oxide concentrate with a grade of 69.38 wt% and a recovery rate of 80.89% were obtained and used as a raw material for preparing iron oxide red pigment.Calcining with sulfuric acid produced iron red pigments with different hues.Simultaneously, middlings with a grade of 60.20 wt% and a recovery rate of 17.51% were obtained and could be used in blast furnace ironmaking.High-value utilization of specularite beneficiation products was thus achieved.
文摘We investigated whether an ordinary centrifuge can achieve the standard centrifugal effect required according to specifications for infectious disease screening using the Abbott i2000.Samples were collected and centrifuged following a standard operating procedure(SOP).They were then divided into three groups according to the results of the initial screening tests:a negative group,weak-positive group,and positive group.Twenty negative samples and all weak-positive and positive samples were re-analyzed.Two tubes for each re-analyzed sample were centrifuged simultaneously,one for 10 min at 10000x g,per recommendations,and one for 10 min at 2750^g.No significant difference was found between the groups using different centrifugal forces.There was a strong correlation in the quantitative values between the two conditions of centrifugation.Consistency analysis showed a Cronbach's alpha>0.8 for detection of Treponema pallidum,human immunodeficiency virus(HIV),hepatitis C virus(HCV),and hepatitis B surface antigen in the three groups(negative group,weak-positive group,and positive group)under different centrifugation conditions.Strong consistency was found under different centrifugal conditions,regardless of the initial testing results.In conclusion,we conducted centrifugation steps in duplicate,according to infectious disease screening protocols.Our study showed that all samples should be centrifuged using a recommended relative centrifugal force after a proper clotting time,as in the standard operating procedure of our laboratory.In this way,we were able to obtain the same results using an ordinary centrifuge as those obtained using a high-speed centrifuge,such as the Abbott i2000.
文摘The study aimed to investigate the effects of centrifugation of stallion semen on progressive sperm motility over a 72-hour period;and determine if the protein marker,precursor of A-kinase anchor protein 4(pro-AKAP4),may be maintained at a higher level over time when compared to non-centrifuged samples.Pro-AKAP4 has been studied for its function in stabilizing the structure of spermatozoa and its use as a marker for fertilizing capacity of spermatozoa.Semen collections were obtained from four fertile,commercially used Standardbred stallions collected three times each.Semen samples were diluted to a final concentration of 50 million total cells per milliliter.One extended aliquot of semen from each collection was used for the non-centrifuged treatment,and one extended aliquot of semen was centrifuged at 750×g for 10 min.The supernatant from the centrifuged sample was then removed with a 10 mL plastic transfer pipette,and the spermatozoa cell pellet was suspended in fresh extender to a final concentration of 50 million total cells per milliliter.Both centrifuged and non-centrifuged samples from each collection were stored in Equine Express II stallion semen shipping containers for 72 h and fresh ice packs were added to each container every 24 h.Both progressive sperm motility and levels of pro-AKAP4 were determined at times 0,12,24,48 and 72 h after collection.Differences were found between stallions,times and treatments with the main finding being that pro-AKAP4 concentration in centrifuged samples was maintained at a much higher level over the 72-hour period studied.
基金Grant sponsor:the Science and Technology Projects of Quanzhou,grant number:2019N085Sgrant sponsor:Startup Fund for Scientific Research,Fujian Medical University,grant number:2018QH1100
文摘Objective:Sperm preparation techniques and cryopreservation are widely used in assisted reproductive techniques(ART).How to improve the quality of sperm management is a matter of great concern.Phospholipase C-zeta(PLCζ)is considered a sperm-specific agent that activates oocyte activation and thus playing a crucial role in male fertility.However,the potential mechanisms by which semen processing and cryopreservation on PLCζcontribute to keyhole have not been addressed.Methods:In this study,semen samples were taken from have not been addressed 10 normozoospermic men.Each semen sample was assigned to the following groups:density gradient centrifugation(DGC)as control,microfluidic sorting,and cryopreservation.Sperm parameters of molity,viability,membrane integrity,and intracellular ROS were evaluated during sperm preparation and cryopreservation.The expression of PLCζin human sperm was determined by immunofluorescence and western blotting.Results:The results showed that molity,viability,and membrane integrity decreased in cryopreservation group.Intracellular ROS were also significantly increased compared to the the control group.There was no significant difference between DGC and microfluidic sorting group.Our investigation revealed that total levels of PLCζwere comparable between DGC and microfluidic sorting,but there were significantly reduced levels of PLCζafter cryopreservation as quantified by both immunofluorescenceand immunoblotting.PLCζimmunofluorescence in sperm revealed different PLCζlocalization patterns around the acrosomal(Ac),equatorial(Eq),post-acrosomal(PA)areas of sperm heads,and their combination.The predominant patterns of PLCζlocalization in DGC were similar to that of microfluidic sorting,with strong,with staining.In contrast,PLCζstaining in freeze-thawed sperm was considerably weaker fluorescence intensity.Conclusion:This study clarified the mechanism of sperm preparation and cryopreservation underlying effect on sperm characteristic,accompanied with PLCζexpresion.We demonstrated that microfluidic sorting provides a highly efficient preparation method for clinical selection of PLCζ-expressing sperm comparable to DGC gene expression.It is suggested that the cryopreservation of sperm has a significant detrimental effect on PLCζ.
基金the financial support from the National Natural Science Foundation of China(22274029 for C.Zhu)the Science and Technology Commission of Shanghai Municipality(22ZR1412000 for C.Zhu22140900700 and 23ZR1411300 for Q.Yao).
文摘The pre-analytical steps in blood-based liquid biopsy,involving sample collection techniques and storage conditions,play a critical role in ensuring the integrity and reliability of collected samples.These steps have a directly impact on the accuracy and reliability of test results and are therefore of utmost importance.Mass spectrometry(MS)-based proteomics is an exceptionally powerful tool in the field of liquid biopsy.It enables the comprehensive analysis of the protein content within biological specimens,providing valuable insights into the underlying mechanisms and pathogenesis of diseases.In this study,we aim to explore the variations in the protein landscape between serum and plasma specimens and evaluate the impact of delayed centrifugation on LC/MS-analyzed protein profiles.We seek to provide recommendations on optimal pre-analytical protocols for MS-based proteomics studies.This will enhance the accuracy and reliability of liquid biopsy for precision medicine,ultimately leading to improved patient outcomes.
基金financially supported by the New Jersey Department of Environmental ProtectionUS EPA。
文摘In this study,synthetic wastewater containing 110μg/L arsenate(As(V)),0-20 mg/L fulvic acid(FA),and 0-12.3 mg/L phosphate was treated with 3 mg/L Fe3+.The mechanisms of FA and phosphate effects on As(V)removal by ferric chloride were determined using 0.22-10μm pore-size filtration,Zetasizer analysis,and in situ flow through cell ATR-FTIR.The results showed that up to 20mg/L FA had almost no effect on the solubility of ferric hydroxide precipitates and adsorption of As(V)by the precipitates.When FA concentration increased from 0 to 20 mg/L,the adsorption of FA led to higher negative zeta potential of the precipitates and the strong electrostatic repulsion between the precipitates decreased the particle size of ferric hydroxide flocs fromlarger than 10μmto smaller than 1μm.In the presence of 5-20 mg/L FA,46%-63%As(V)was adsorbed onto the flocs with particle size in the range of 0.45-1μm.On the other hand,phosphate did not affect the size of ferric hydroxide flocs and significantly increased the dissolved As(V)concentration because it competed with As(V)for adsorption sites on ferric hydroxide precipitates.The addition of 5mg/L cationic organic flocculant significantly reduced the effect of FA on As(V)removal,but did not reduce the effect of phosphate on As(V)removal.The findings of this study will help develop effective arsenic treatment techniques and predict the mobility of arsenic in the environment.
文摘Discovery of spermatozoa during the 17^(th) century led to developing technologies for semen analysis in the early 1900s,and then,standard techniques were implemented during the 20^(th) century.Semen analysis has a pivotal role in the male infertility evaluation,and azoospermia is an important finding.Azoospermia is identified in 15%of infertile men.However,the accurate laboratory assessment of azoospermia poses certain technical challenges.Laboratories currently perform semen assessment with great variability;thus,a standard method should be used.Planning suitable management and determining the cause of infertility require a precise evaluation of azoospermia.This review aims to address the definition of azoospermia and highlight laboratory methods in the assessments of azoospermia.Basic methods such as centrifugation,repeat pellet analysis,and staining and advanced methods such as genetic testing and biomarkers have been discussed.These methods have helped in standardizing the protocol for accurate azoospermia assessments with less variability.
基金funded by National Key Research and Development Program for Young Scientists of China(2022YFF1102900)Hebei Province High-level Talent Funding Project(C20221009)。
文摘This study established a method using gas chromatography-electrostatic field Orbitrap high-resolution mass spectrometry(Orbitrap GC-MS)for the simultaneous determination of 70 organic pollutants across 4 categories:organochlorine pesticides(OCPs),polycyclic aromatic hydrocarbons(PAHs),polychlorinated biphenyls(PCBs),and phthalates(PAEs)in infant cereal-based supplementary foods.Techniques integrating cryogenic centrifugation and lipid and protein adsorbent(LPAS)purification were employed.The precise mass numbers of target compounds were determined by Orbitrap GC-MS in full-scan mode(Full MS),which effectively minimized matrix interferences in these foods.Method validation on rice flour samples demonstrated that the 70 compounds exhibited excellent linearity within their respective mass concentration ranges,with correlation coefficients all exceeding 0.995.The detection limits for this method ranged 0.10–1.00μg/kg,while the quantification limits varied 0.3–3.0μg/kg,meeting the established detection requirements.The average spike recovery of the 70 compounds at 3 spiked levels(5,20,and 100μg/kg)ranged 75.3%–119.3%,with relative standard deviations ranging 1.8%–10.8%.Both inter-day and intra-day precision demonstrated relative standard deviation values below 15%.This method was applied to analyze 100 samples of commercial infant cereal-based supplementary food,revealing the presence of PAEs and PAHs in 12.0%of the samples.Notably,no OCPs or PCBs were detected.The detected concentrations of benzo[a]pyrene(Ba P)and dibutyl phthalate(DBP)were(4.2±0.1)and(1.8±0.3)μg/kg,respectively.This method is straightforward,highly sensitive,and suitable for the rapid screening and confirmation of 70 organic pollutants in infant cereal-based supplementary foods.
文摘Objective:How to increase the long-term retention rate of autologous fat grafting has been widely discussed.This study aimed to evaluate long-term fat graft retention rates for the most widely used fat processing methods in the area of facial esthetic surgery,including centrifugation,filtration,and sedimentation,using three-dimensional(3D)imaging.Data Sources:PubMed,Embase,Wiley/Cochrane Library,and Web of Science databases were comprehensively searched from inception to July 2018 according to the guidelines of the American Society of Plastic Surgeons Fat Graft Task Force Assessment Methodology.Study Selection:Articles were screened using predetermined inclusion and exclusion criteria.Data collected included patient characteristics,follow-up devices,fat grafting techniques,and clinical outcomes.Patient cohorts were pooled,and fat graft retention rates were calculated.Complications were summarized according to different clinical characteristics.Results:Of 77 articles,10 clinical studies met the inclusion criteria and reported quantified measurement outcomes with 3D imaging which provide precise volumetric data with approximately 2%standard deviation compared to real volumes.Data of 515 patients were included.Fat grafting retention varied from 21%to 82%.We found filtration and centrifugation techniques could result in better retention outcomes.However,retention varied within each processing technique,with no significant difference among the 3 techniques.Twenty-two complications were reported among 515 patients,including donor-site hematoma(1 case),mild postoperative erythema(2 cases),mild volumetric asymmetries(2 cases),chronic edema(2 cases),overcorrection(2 cases),skin irregularity(6 cases),and headache or dysesthesia(7 cases).Conclusions:Filtration and centrifugation techniques may result in better fat grafting retention outcomes than gravity sedimentation;however,more accurate statistical evidence is needed.Controversies continue to exist with respect to the performance of the different fat-processing techniques in fat graft retention.
基金the National Key R&D Program of China(2017YFC1002003)to Z.L.and R.C.C.
文摘Objective:Density gradient centrifugation(DGC),swim up(SU),or a combination of DGC and SU is used to prepare sperm for infertility treatments using assisted reproductive technologies(ARTs).This study aimed to investigate the efficiency of a new device for detecting sperm DGC.Methods:Sperm samples were collected from 119 males who required semen analysis at three differentin vitro fertilization(IVF)centers(71 samples from Center A,28 samples from Center B,and 20 samples from Center C).Semen samples were divided into two groups for DGC:(1)a normal centrifugation tube and(2)a specially designed RC-Tube.The sperm concentration,motility,and DNA fragmentation index(DFI)were assessed using DGC.Sperm concentration and motility were assessed using a MAKLER counting chamber.Sperm DFI was measured and analyzed using flow cytometry using a DFI Kit.Results:There were no significant differences in sperm concentrations recovered following DGC between the two groups(31.1%±1.7%vs.28.8%±1.3%).Sperm motility was not significantly different following the DGC procedure in both groups(77.6%±1.6%.vs.75.8%±1.6%).The percentage of sperm DFI was also not significantly different following DGC between the two groups(10.4%±1.0%vs.10.5%±1.0%).Conclusions:The newly designed RC-Tube is efficient for sperm DGC and can be used to simplify sperm preparation for infertility treatment.
基金Ministry of Science and Technology of China,National Key R&D Program of China(No.2017YFC1002003 and No.2017YFC1001601)
文摘Objective:The purpose of this study was to evaluate the sperm motility and DNA integrity at different temperatures to analyze whether the sperms are suitable on the second day for insemination of in vitro matured oocytes by intra-cytoplasmic sperm injection(ICSI)following density gradient centrifugation(DGC)and swim-up(SU)procedures.Methods:Semen samples were collected from 30 outpatients who visited the Center for Reproductive Medicine for semen analyses.Following sperm selection by DGC and SU procedures,the liquified semen samples were divided into three groups and incubated at 4,25,and 37°C,respectively.Following incubation for 24,48,and 72 hours,the sperm motility and sperm DNA fragmentation index(DFI)were analyzed.Results:Following the combination of DGC and SU procedures,the sperm motility(91.8%±8.6%vs.50.8%±13.1%)and DFI(5.1%±7.9%vs.13.0%±11.6%)were significantly improved(P<0.01)compared to those without any treatment.The sperm motility of the 3 groups significantly declined(P<0.05)post-incubation compared to that of the groups prior incubation.However,sperm motility significantly increased(76.9%±10.4%)(P<0.05)at 25°C compared to that of the other 2 groups(53.5%±11.0%and 47.6%±10.2%).Sperm DFI significantly increased(P<0.05)at 37°C following incubation for 24 and 72 hours in comparison to that of the other 2 groups.However,the sperm DFI did not significantly increase when the sperm samples were incubated at 4(5.7%±5.9%)and 25°C(6.8%±5.6%)for 24 hours compared to that before incubation(5.1%±7.9%).Conclusions:These results indicate that the sperm quality,in terms of motility and DFI,can be efficiently improved by DGC in combination with SU.Following which,the sperm samples can be incubated at 25°C and be used on the second day for insemination of in vitro matured oocytes by ICSI.
基金supported by the National Natural Science Foundation of China(Research Project No.52169018).
文摘Cavitation is an unavoidable phenomenon in the operation of centrifugal pumps.Prolonged cavitation can cause significant damage to the components of the flow channel,and in severe cases,it may even interfere with the normal energy exchange processes within the pump.Therefore,effective monitoring of cavitation in centrifugal pumps is crucial.This article presents a study that approaches the issue from an acoustic perspective,using experimental methods to gather and analyze acoustic data at the inlet and outlet of centrifugal pumps across various flow rates,with hydrophones as the primary measuring instruments.Results show that flow rate significantly affects noise levels in both non-cavitation and mild cavitation stages,with noise increasing as the flow rate rises.As the cavitation margin(NPSHa)decreases,inlet and outlet noise trends diverge:inlet noise drops sharply,while outlet noise initially increases before sharply decreasing.Both exhibit a distinct zone of abrupt change,where NPSHa values offer earlier cavitation detection than traditional methods.The noise at the pump’s inlet and outlet primarily consists of discrete and broadband noise,with most energy concentrated at discrete frequencies—shaft frequency(24 Hz),blade frequency(144 Hz),and their harmonics.As NPSHa decreases,the inlet’s discrete and broadband noise frequencies decline,while they increase at the outlet.Monitoring changes in these spectrum characteristics provides an additional means of predicting cavitation onset.
文摘A centrifugal pump with a specific speed ns=67 is considered in this study to investigate the impact of blade cutting(at the outlet edge)on the fluid-induced noise,while keeping all the other geometric parameters unchanged.The required unsteady numerical calculations are conducted by applying the RNG k-εturbulence model with the volute dipole being used as the sound source.The results indicate that the internal pressure energy of the centrifugal pump essentially depends on the blade passing frequency and its low-frequency harmonic frequency.Moreover,the pressure pulsation distribution directly affects the noise caused by the centrifugal pump.The sound pressure inside and outside the centrifugal pump and the sound power at the blade passing frequency gradually decrease increasing cutting distance of the impeller blades.When the cutting percentage is 1.21%,that is,the clearance ratio between impeller blade and tongue is 8.57%,the comprehensive performance of the centrifugal pump is the best.
基金supported by Fundamental Research Funds for the Central Universities(Grant No.B200202050)Open Funds of Key Laboratory of Navigation Structure。
文摘The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,experience one-way cyclic tensile loads at inclinations ranging from 0°(horizontal)to 90°(vertical).However,the combined effects of cyclic loading and load inclination remain inadequately understood.This study presents findings from centrifuge tests conducted on rough rigid piles installed in dense sand samples.The results demonstrate that load inclinations significantly influence both cyclic response and ultimate capacity of the piles.Based on the observed cyclic response characteristics,the vertical cyclic load amplitude should not exceed 25%of the ultimate bearing capacity to maintain pile stability.A power expression(with exponent m values ranging from 0.055 to 0.065)is proposed for predicting cumulative pile displacement under unidirectional cyclic loading at inclinations from 0°to 60°.The cyclic response exhibits reduced sensitivity to horizontal cyclic load magnitude,with m-value increasing from 0.06 to 0.14 as load magnitude increases from 0.3 to 0.9.For piles maintaining stability under oblique cyclic loading,the average normalized secant stiffness exceeds 1 and increases with decreasing inclination,indicating enhanced pile stiffness under cyclic loading.For load inclinations below 30°,pile stiffness can be determined using logarithmic function.
