Understanding how stars form in molecular clouds is one of the ongoing research areas in astrophysics. Star formation is the fundamental process to which our current understanding remains incomplete due to the complex...Understanding how stars form in molecular clouds is one of the ongoing research areas in astrophysics. Star formation is the fundamental process to which our current understanding remains incomplete due to the complexity of the physics that drives their formation within molecular clouds. In this article theoretical modelling of the lowest possible mass of the cloud needed for collapse and the core accretion rate has been presented for the molecular cloud collapsing under its gravity. In many of previous studies the critical mass of star forming cloud under its gravity has been modelled using kinetic energy and gravitational potential energy. However, we test the effect of thermodynamic efficiency factor together with other physical processes in describing the critical mass, and controlling or triggering the rate of mass falling onto the central core. Assuming that, the ratio of radiation luminosity to gravitational energy released per unit time of the collapsing MC is less than unity. Following this conceptual framework we have formulated the critical mass and the core accretion rate of the self-gravitating molecular cloud.展开更多
The liquid-liquid extraction method using reverse micelles can simultaneously extract lipid and protein of oilseeds,which have become increasingly popular in recent years.However,there are few studies on mass transfer...The liquid-liquid extraction method using reverse micelles can simultaneously extract lipid and protein of oilseeds,which have become increasingly popular in recent years.However,there are few studies on mass transfer processes and models,which are helpful to better control the extraction process of oils and proteins.In this paper,mass transfer process of peanut protein extracted by bis(2-ethylhexyl)sodium sulfosuccinate(AOT)/isooctane reverse micelles was investigated.The effects of stirring speed(0,70,140,and 210 r/min),temperature of extraction(30,35,40,45,and 50℃),peanut flour particle size(0.355,0.450,0.600,and 0.900 mm)and solidliquid ratio(0.010,0.0125,0.015,0.0175,and 0.020 g/mL)on extraction rate were examined.The results showed that extraction rate increased with temperature rising,particle size reduction as well as solid-liquid ratio increase respectively,while little effect of stirring speed(P>0.05)was observed.The apparent activation energy of extraction process was calculated as 10.02 kJ/mol and Arrhenius constant(A)was 1.91 by Arrhenius equation.There was a linear relationship between reaction rate constant and the square of the inverse of initial particle radius(1/r_(0)^(2))(P<0.05).This phenomenon and this shrinking core model were anastomosed.In brief,the extraction process was controlled by the diffusion of protein from the virgin zone interface of particle through the reacted zone and it was in line with the first order reaction.Mass transfer kinetics of peanut protein extracted by reverse micelles was established and it was verified by experimental results.The results provide an important theoretical guidance for industrial production of peanut protein separation and purification.展开更多
Rock sampling with traditional coring method would cause initial damage to rock samples induced by in-situ stress relief during coring.To solve this problem,a damage-free coring method is proposed in this paper.The pr...Rock sampling with traditional coring method would cause initial damage to rock samples induced by in-situ stress relief during coring.To solve this problem,a damage-free coring method is proposed in this paper.The proposed coring scheme is numerically modeled first,and then it is verified by comparative laboratory tests using rock samples both obtained by conventional coring method and the proposed damage-free coring method.The result indicates that the in-situ stresses in sampling area could be reduced by 30%-50% through drilling a certain number of destressing holes around the whole sampling area.The spacing between adjacent destressing holes is about 10 cm.The average uniaxial compressive strength（UCS） of rock samples obtained by the damage-free coring method in Jinping II hydropower station with overburden depth of 1 900 m is higher than that of samples obtained by the conventional coring method with the same depth by 5%-15% and an average of 8%.In addition,the effectiveness of damage-free coring method can also be verified by acoustic emission（AE） monitoring.The AE events monitored during uniaxial compression test of damage-free coring samples is fewer than that of conventional coring samples at the primarily loading phase.展开更多
Definitive diagnosis of parotid gland masses is required optimal management planning and for prognosis. There is controversy over whether fine needle aspiration cytology(FNAC) or ultrasound guided core biopsy(USCB) sh...Definitive diagnosis of parotid gland masses is required optimal management planning and for prognosis. There is controversy over whether fine needle aspiration cytology(FNAC) or ultrasound guided core biopsy(USCB) should be the standard for obtaining a biopsy. The aim of this review is to assess the current evidence available to assess the benefits of each technique and also to assess the use of intra-operative frozen section(IOFS). Literature searches were performed using pubmed and google scholar. The literature has been reviewed and the evidence is presented. FNAC is an accepted and widely used technique. It has been shown to have variable diagnostic capabilities depending on centres and experience of staff. USCB has a highly consistent diagnostic accuracy and can help with tumour grading and staging. However, the technique is more invasive and there is a question regarding potential for seeding. Furthermore, USCB is less likely to be offered as part of a one-stop clinic. IOFS has no role as a first line diagnostic technique but may be reserved as an adjunct or for lesions not amenable to percutaneous biopsy. On balance, USCB seems to be the method of choice. The current evidence suggests it has superior diagnostic potential and is safe. With time, USCB is likely to supplant FNAC as the biopsy technique of choice, replicating that which has occurred already in other areas of medicine such a breast practice.展开更多
AIM To compare the accuracy of endoscopic ultra-sonography(EUS) 19 G core biopsies and 22 G core biopsies in diagnosing the correct etiology for a solid mass.METHODS Articles were searched in Medline, Pub Med, and Ovi...AIM To compare the accuracy of endoscopic ultra-sonography(EUS) 19 G core biopsies and 22 G core biopsies in diagnosing the correct etiology for a solid mass.METHODS Articles were searched in Medline, Pub Med, and Ovid journals. Pooling was conducted by both fixed and random effects models. RESULTS Initial search identified 4460 reference articles for 19 G and 22 G, of these 670 relevant articles were selected and reviewed. Data was extracted from 6 studies for 19G(n = 289) and 16 studies for 22G(n = 592) which met the inclusion criteria. EUS 19 G core biopsies had a pooled sensitivity of 91.6%(95%CI: 87.1-95.0) and pooled specificity of 95.9%(95%CI: 88.6-99.2), whereas EUS 22 G had a pooled sensitivity of 83.3%(95%CI: 79.7-86.6) and pooled specificity of 64.3%(95%CI: 54.7-73.1). The positive likelihood ratio of EUS 19 G core biopsies was 9.08(95%CI: 1.12-73.66) and EUS 22 G core biopsies was 1.99(95%CI: 1.09-3.66).The negative likelihood ratio of EUS 19 G core biopsies was 0.12(95%CI: 0.07-0.24) and EUS 22 G core biopsies was 0.25(95%CI: 0.14-0.41). The diagnostic odds ratio was 84.74(95%CI: 18.31-392.26) for 19 G core biopsies and 10.55(95% CI: 3.29-33.87) for 22 G needles. CONCLUSION EUS 19 G core biopsies have an excellent diagnostic value and seem to be better than EUS 22 G biopsies in detecting the correct etiology for a solid mass.展开更多
文摘Understanding how stars form in molecular clouds is one of the ongoing research areas in astrophysics. Star formation is the fundamental process to which our current understanding remains incomplete due to the complexity of the physics that drives their formation within molecular clouds. In this article theoretical modelling of the lowest possible mass of the cloud needed for collapse and the core accretion rate has been presented for the molecular cloud collapsing under its gravity. In many of previous studies the critical mass of star forming cloud under its gravity has been modelled using kinetic energy and gravitational potential energy. However, we test the effect of thermodynamic efficiency factor together with other physical processes in describing the critical mass, and controlling or triggering the rate of mass falling onto the central core. Assuming that, the ratio of radiation luminosity to gravitational energy released per unit time of the collapsing MC is less than unity. Following this conceptual framework we have formulated the critical mass and the core accretion rate of the self-gravitating molecular cloud.
基金This study was supported by the National Natural Science Foundation of China(No.U21A20270 and 32202079)Postdoctoral Science and Technology Project of Henan,Grant No.HN2022046+2 种基金Science and Technology Project of Henan Province(232103810064)the Innovative Funds Plan of Henan University of Technology(2021ZKCJ03)the Key Scientific Research Projects of Colleges and Universities of Henan(23A550012).
文摘The liquid-liquid extraction method using reverse micelles can simultaneously extract lipid and protein of oilseeds,which have become increasingly popular in recent years.However,there are few studies on mass transfer processes and models,which are helpful to better control the extraction process of oils and proteins.In this paper,mass transfer process of peanut protein extracted by bis(2-ethylhexyl)sodium sulfosuccinate(AOT)/isooctane reverse micelles was investigated.The effects of stirring speed(0,70,140,and 210 r/min),temperature of extraction(30,35,40,45,and 50℃),peanut flour particle size(0.355,0.450,0.600,and 0.900 mm)and solidliquid ratio(0.010,0.0125,0.015,0.0175,and 0.020 g/mL)on extraction rate were examined.The results showed that extraction rate increased with temperature rising,particle size reduction as well as solid-liquid ratio increase respectively,while little effect of stirring speed(P>0.05)was observed.The apparent activation energy of extraction process was calculated as 10.02 kJ/mol and Arrhenius constant(A)was 1.91 by Arrhenius equation.There was a linear relationship between reaction rate constant and the square of the inverse of initial particle radius(1/r_(0)^(2))(P<0.05).This phenomenon and this shrinking core model were anastomosed.In brief,the extraction process was controlled by the diffusion of protein from the virgin zone interface of particle through the reacted zone and it was in line with the first order reaction.Mass transfer kinetics of peanut protein extracted by reverse micelles was established and it was verified by experimental results.The results provide an important theoretical guidance for industrial production of peanut protein separation and purification.
基金Supported by the National Basic Research Program of China (973 Program) (2010CB732003)the National Natural Science Foundation of China (51009013,50909077)
文摘Rock sampling with traditional coring method would cause initial damage to rock samples induced by in-situ stress relief during coring.To solve this problem,a damage-free coring method is proposed in this paper.The proposed coring scheme is numerically modeled first,and then it is verified by comparative laboratory tests using rock samples both obtained by conventional coring method and the proposed damage-free coring method.The result indicates that the in-situ stresses in sampling area could be reduced by 30%-50% through drilling a certain number of destressing holes around the whole sampling area.The spacing between adjacent destressing holes is about 10 cm.The average uniaxial compressive strength（UCS） of rock samples obtained by the damage-free coring method in Jinping II hydropower station with overburden depth of 1 900 m is higher than that of samples obtained by the conventional coring method with the same depth by 5%-15% and an average of 8%.In addition,the effectiveness of damage-free coring method can also be verified by acoustic emission（AE） monitoring.The AE events monitored during uniaxial compression test of damage-free coring samples is fewer than that of conventional coring samples at the primarily loading phase.
文摘Definitive diagnosis of parotid gland masses is required optimal management planning and for prognosis. There is controversy over whether fine needle aspiration cytology(FNAC) or ultrasound guided core biopsy(USCB) should be the standard for obtaining a biopsy. The aim of this review is to assess the current evidence available to assess the benefits of each technique and also to assess the use of intra-operative frozen section(IOFS). Literature searches were performed using pubmed and google scholar. The literature has been reviewed and the evidence is presented. FNAC is an accepted and widely used technique. It has been shown to have variable diagnostic capabilities depending on centres and experience of staff. USCB has a highly consistent diagnostic accuracy and can help with tumour grading and staging. However, the technique is more invasive and there is a question regarding potential for seeding. Furthermore, USCB is less likely to be offered as part of a one-stop clinic. IOFS has no role as a first line diagnostic technique but may be reserved as an adjunct or for lesions not amenable to percutaneous biopsy. On balance, USCB seems to be the method of choice. The current evidence suggests it has superior diagnostic potential and is safe. With time, USCB is likely to supplant FNAC as the biopsy technique of choice, replicating that which has occurred already in other areas of medicine such a breast practice.
文摘AIM To compare the accuracy of endoscopic ultra-sonography(EUS) 19 G core biopsies and 22 G core biopsies in diagnosing the correct etiology for a solid mass.METHODS Articles were searched in Medline, Pub Med, and Ovid journals. Pooling was conducted by both fixed and random effects models. RESULTS Initial search identified 4460 reference articles for 19 G and 22 G, of these 670 relevant articles were selected and reviewed. Data was extracted from 6 studies for 19G(n = 289) and 16 studies for 22G(n = 592) which met the inclusion criteria. EUS 19 G core biopsies had a pooled sensitivity of 91.6%(95%CI: 87.1-95.0) and pooled specificity of 95.9%(95%CI: 88.6-99.2), whereas EUS 22 G had a pooled sensitivity of 83.3%(95%CI: 79.7-86.6) and pooled specificity of 64.3%(95%CI: 54.7-73.1). The positive likelihood ratio of EUS 19 G core biopsies was 9.08(95%CI: 1.12-73.66) and EUS 22 G core biopsies was 1.99(95%CI: 1.09-3.66).The negative likelihood ratio of EUS 19 G core biopsies was 0.12(95%CI: 0.07-0.24) and EUS 22 G core biopsies was 0.25(95%CI: 0.14-0.41). The diagnostic odds ratio was 84.74(95%CI: 18.31-392.26) for 19 G core biopsies and 10.55(95% CI: 3.29-33.87) for 22 G needles. CONCLUSION EUS 19 G core biopsies have an excellent diagnostic value and seem to be better than EUS 22 G biopsies in detecting the correct etiology for a solid mass.
