Inhibition of SLC26A4 regulated by electroacupuncture suppresses the progression of myocardial ischemia-reperfusion injury

Introduction:Myocardial ischemia-reperfusion(IR)injury has received widespread attention due to its damaging effects.Electroacupuncture(EA)pretreatment has preventive effects on myocardial IR injury.SLC26A4 is a Na+independent anion reverse transporter and has not been reported in myocardial IR injury.Objectives:Tofind potential genes that may be regulated by EA and explore the role of this gene in myocardial IR injury.Methods:RNA sequencing and bioinformatics analysis were performed to obtain the differentially expressed genes in the myocardial tissue of IR rats with EA pretreatment.Myocardial infarction size was detected by TTC staining.Serum CK,creatinine kinase-myocardial band,Cardiac troponin I,and lactate dehydrogenase levels were determined by ELISA.The effect of SLC26A4 on cardiomyocyte apoptosis was explored by TUNEL staining and western blotting.The effects of SLC26A4 on inflammation were determined by HE staining,ELISA,and real-time PCR.The effect of SLC26A4 on the NF-κB pathway was determined by western blotting.Results:SLC26A4 was up-regulated in IR rats but downregulated in IR rats with EA pretreatment.Compared with IR rats,those with SLC26A4 knockdown exhibited improved cardiac function according to decreased myocardial infarction size,reduced serum LDH/CK/CK-MB/cTnI levels,and elevated left ventricular ejection fraction and fractional shortening.SLC26A4 silencing inhibited myocardial inflammation,cell apoptosis,phosphorylation,and nuclear translocation of NF-κB p65.Conclusion:SLC26A4 exhibited promoting effects on myocardial IR injury,while the SLC26A4 knockdown had an inhibitory effect on the NF-κB pathway.These results further unveil the role of SLC26A4 in IR injury.

Transcriptional Features of Cattle Visceral and Subcutaneous Adipose Tissues: A Study of RNA-seq

Visceral and subcutaneous are the two major types of bovine adipose tissues, and they show metabolic and functional differences according to their distribution, exploring the transcriptional features of visceral and subcutaneous adipose tissues is necessary. In the present study, we conducted RNA-seq analysis to compare the transcriptome between visceral (great omental) and subcutaneous (backfat) adipose tissues from Chinese Simmental cattle and validate them by qRT-PCR. We found that 5864 genes were differentially expressed between two tissues, including 2979 up-regulated and 2885 down-regulated in visceral adipose tissue. Functional analysis revealed a variety of differentially expressed genes (DEGs) involved in lipid metabolism and immune response processes. This may provide valuable information to further our understanding of the complexity of gene regulation governing the physiology of different fat depots. This work highlighted potential genes regulating lipid metabolism and immune responses;it may contribute to a better understanding of the metabolic and functional differences between visceral and subcutaneous adipose tissues.

基于巯基改性磺化海泡石与聚(2,5-苯并咪唑)原位复合的宽温域用质子交换膜

天然海泡石经微波辅助酸活化和巯基偶联剂改性得到磺化海泡石,然后原位合成制备燃料电池宽温域用聚(2,5-苯并咪唑)/磺化海泡石(ABPBI/S-Sep)复合质子交换膜。研究了海泡石改性前后结构变化,以及S-Sep粒子的加入对复合膜的微观形貌、结构、力学性能、吸水固酸能力以及高、低温下质子传导性能的影响。研究发现,海泡石粒子经微波辅助酸活化处理后产生了解纤维化,磺化改性提高了其与聚合物相容性;S-Sep纤维状粒子均匀分散在ABPBI基体中可诱导聚合物分子链取向排列,从而提高复合膜的力学性能,其特有的纳米通道结构及高比表面积显著提高了复合膜的吸水率和固酸能力。在相似磷酸(PA)掺杂水平下,复合膜在40~180℃宽温域下的质子传导率和峰值功率密度均高于ABPBI膜,并且磷酸掺杂水平为1.85的复合膜在90℃以下,60%和98%RH时质子传导性能以及80℃、0%RH时单电池性能均与Nafion 212相当,表明低磷酸掺杂水平下的S-Sep改性ABPBI复合膜具备从低温到高温且不控制湿度的宽温域使用优势,可拓展基于PA掺杂聚苯并咪唑类膜材料的使用温度范围。

低温燃料电池用聚(2,5-苯并咪唑)/磺化海泡石复合质子交换膜的制备与性能

采用原位法制备了一种适用于低温燃料电池的新型聚(2,5-苯并咪唑)/磺化海泡石(ABPBI/S-Sep)复合质子交换膜。对海泡石酸活化和磺化改性前后的化学结构、亲水性和分散性以及复合膜的形貌、吸水率、磷酸掺杂水平与质子传导率等性能进行了表征和测试。结果显示,所制备的S-Sep粒子在ABPBI聚合物基体中分散均匀,并能促进聚合物分子链的规整排布;与纯ABPBI膜相比,S-Sep粒子的添加显著增强了复合膜对水和磷酸的吸收和保留能力,且在相同或相近磷酸掺杂水平下,ABPBI/S-Sep复合膜的质子传导率显著提高。在40～90℃温度范围内,饱和湿度98%RH时复合膜的质子传导率与Nafion 212相当;在低湿度60%RH时,高磷酸掺杂水平的ABPBI/S-Sep复合膜质子传导率略低于98%RH的结果,但显著优于Nafion 212的质子传导性能。不同温湿度环境下的质子传导率结果表明S-Sep改性ABPBI复合膜具备低温环境使用的特点,可替代Nafion类全氟磺酸膜应用于低温质子交换膜燃料电池。

Separation and determination of acetyl-glutamine enantiomers by HPLC–MS and its application in pharmacokinetic study

A high-performance liquid chromatography coupled with mass spectrometry(HPLC–MS) method was established for the separation and determination of acetyl-glutamine enantiomers(acetylL-glutamine and acetylD-glutamine) simultaneously. Baseline separation was achieved on Chiralpak AD-H column(250 mm ×4.6 mm, 5 μm). n-Hexane(containing 0.1% acetic acid) and ethanol(75:25, v/v) were used as mobile phase at a flow rate of 0.6 m L/min. The detection was operated in the negative ion mode with an ESI source. [M-H]-m/z187.0540 for enantiomers and [M-H]-m/z 179.0240 for aspirin(IS) were selected as detecting ions. The linear range of the calibration curve for each enantiomer was 0.05–40 μg/m L. The precision of this method at concentrations of 0.5–20 μg/m L was within 7.23%, and the accuracy was 99.81%–107.81%. The precision at LOQ(0.05 μg/m L) was between 16.28% and 17.56%, which was poor than that at QC levels. The average extraction recovery was higher than 85% for both enantiomers at QC levels. The pharmacokinetics of enantiomers was found to be stereoselective. There was not chiral inversion in vivo or in vitro between enantiomers.

Dealumination kinetics of composite ZSM-5/mordenite zeolite during steam treatment: An in-situ DRIFTS study

To get a better understanding of structural deactivation of ZSM-5/MOR during the catalytic cracking of n-heptane in the steam atmosphere, a comprehensive mechanism of hydrothermal dealumination was proposed through in-situ diffuse reflectance Fourier transform infrared spectroscopy(DRIFTS) in this work. The mechanism can be divided into two steps: firstly, the hydrolysis of four Al\\O bonds, and secondly, the self-healing of Si\\OH bonds accompanied with partial condensation of the extra-framework Al species. Accordingly, the kinetics of dealumination process has also been fully discussed. In the IR spectra, the range of 3450–3850 cm^(-1) could be deconvolved to distinguish the hydroxyl groups on the different position and calculate the consumption of each hydroxyl group during the reaction. Based on results from the in-situ DRIFTS, the kinetics of dealumination was hence developed and also in well agreement with the kinetics of deactivation of ZSM/MOR catalysts during the reaction in the presence of little coke deposits.

Continuous use of fitness apps and shaping factors among college students: A mixed-method investigation

Objective:This current study pursued an exploration of the psychological mechanism that determines college students'continuance intention to use fitness apps.Methods:This current study adopted a mixed methods research that composed two distinct phases.Study 1 was quantitative research that helped to identify determinants of Chinese college students'continuance intention to use.A self-reported questionnaire was completed by 379 college students to ascertain their user experience.Study 2 was qualitative research.A semi-structured interview was conducted with a sample of 10 college students.Study 2 can be seen as a follow-up study and it pursued an in-depth understanding on how college students use fitness apps in the everyday life and their views towards study 1's major findings.Results:The results revealed that five factors(confirmed usefulness,confirmed ease of use,satisfaction,fitness achievement and social connection)were found to significantly and positively affect college students'continuous intention to use fitness apps.Entertainment did not show obvious impact.In the interview,college students reported that even if they don't obtain entertainment from fitness apps,they will still push themselves to use them,because they have a very specific goal when using fitness apps,which is to achieve health and fitness.Conclusion:These findings indicated that successful fitness apps should make users feel convenient to use and indeed improves the fitness user's efficiency.Besides,people are more eager to get the information with strong credibility with the negligible effort.This implies more efforts should be made to design apps that can provide high-quality services.Moreover,if apps designers can pay more attention to protecting the personal information and data,it will inspire more people to use social connection functions.

Increased summer electric power demand in Beijing driven by preceding spring tropical North Atlantic warming

本文利用北京市电力负荷资料,北京市站点观测温度资料,CN05.1温度资料,ERA5大气再分析资料及ERSST v3b海表温度资料,发现3-4月副热带北大西洋海温异常和北京市夏季电力呈很好的正相关关系,并揭示了副热带北大西洋海温异常影响北京市夏季电力的可能物理机制.春季副热带北大西洋海温异常偏暖,热带中太平洋出现东风异常并持续至夏季,太平洋信风增强,热带中东太平洋冷水上翻增强,通过Bjerkness正反馈机制激发了La Nina事件.La Nina事件时,西北太平洋反气旋环流异常,将低纬度暖湿气流输送至北京地区,引起北京市夏季温度增高,电力负荷需求增加.反之亦然.研究结果可为北京市夏季电力负荷需求的季节预测提供新的科学依据和线索.

Path of the Information Asymmetry of Asset Backed Securitization—Information Game Analysis of Embedded Block Chain Technology

In recent years, the rapid innovation and development of financial industry has made financial enterprises have a lot of information. However, the large amount of information is tampered with and fragmented, which cannot be shared. With the constant innovation of science and technology, it is the most effective way to solve the information lag and asymmetry of financial products. This article aims to start from the problem of asymmetric information of financial products, the analysis of the emerging block chain technology applied in the financial sector, and with the development of asset securitization information known as the typical scenario for the first time, a concrete analysis information game process, and discuss about the application of chain blocks in securitization feasibility.

Clinical Experience in the Treatment of Vitiligo by the Method of Invigorating Qi,Promoting Blood Circulation and Detoxification

Studies have shown that traditional Chinese medicines have clear curative effects in the treatment of vitiligo with few side effects.Through literature research and clinical observation,the study summarized the etiology and pathogenesis of vitiligo in traditional Chinese medicine as"deficiency,toxin,and stasis",formulated the method of invigorating qi,promoting blood circulation and detoxification,and prescribed Fuse Hexue Jiawei Decoction for the treatment of vitiligo.

碳点的研究进展及壳聚糖为原料的微波法制备

碳点(carbon dots,CDs)是一类具有显著特点的多功能新兴零维碳家族纳米材料,由于其优越的光学性能、良好的生物相容性、特有的表面功能化等,成为当今国际科技界研究热点之一.以生物质原料为前驱体制备CDs,因成本低廉、合成方法绿色环保,引起了广泛的关注.本文归纳了CDs领域的最新研究进展,包括采用不同的前驱体分子、掺杂杂原子元素、合成方法、合成条件及所制备CDs的性能特点与适宜的应用领域;简述了目前对CDs的分类、纳米结构和光电子机理等方面的认知;介绍了微波技术的特点及在制备CDs中的应用,根据已有的研究结果,阐明了微波法制备工艺可靠、方法简单易行;讨论了壳聚糖作为前驱体原料的优势所在:(1)壳聚糖(chitosan,CTS)由几丁质脱乙酰化获得,几丁质则来源于废弃虾蟹壳,属于第二大天然可再生资源;(2)与其他天然有机分子作为前驱体相比,CTS分子结构含氮和氧,可以用作单一含碳、氮、氧元素的分子原料.氮原子掺杂可显著改善CDs发光性质,氧掺杂有利于CDs界面湿润,增加相容性.本文强调了壳聚糖-微波法-碳点这一产业链模式化对应的原料丰富易得、制备工艺可靠、后处理操作简单易行的特性.最后,提出了面临的挑战与未来大规模应用的展望.

Graphene as adsorbent for highly efficient extraction of modified nucleosides in urine prior to liquid chromatography-tandem mass spectrometry analysis

RNA modifications have been involved in numerous biological processes, and aberrations of these modifications are tightly associated with various diseases including cancer. Herein, we developed graphenebased solid-phase extraction and robust ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) combined with stable isotope-dilution for simultaneous enrichment and accurate determination of 17 modified nucleosides in human urine. We found graphene could effectively adsorb various modified nucleosides in human urine samples. With this method, we identified and quantified these modified nucleosides in urine samples collected from lung cancer patients and healthy controls.We revealed that the levels of 12 modified nucleosides were all diminished in urine from lung cancer patients, compared with healthy controls. It is worth noting that we demonstrated, for the first time, the presence of 5,2-O-dimethyluridine(m~5U_m) in human urine. Together, we established a robust analytical method for simultaneous determinations of 17 modified nucleosides in human urine, and our results revealed a close correlation between the concentrations of urinary modified nucleosides and the occurrence of lung cancer, implying the potential applications of these modified nucleosides as noninvasive biomarkers for the early detection of lung cancer. Moreover, this study will stimulate future investigations on the regulatory roles of RNA modifications in the initiation and progression of lung cancer.

Adverse Effect of Nonalcoholic Fatty Liver Disease on the Therapeutic Response in Patients with Chronic Hepatitis B

Background and Aims:The impact of nonalcoholic fatty liver disease(NAFLD)on the treatment outcome of chronic hepatitis B(CHB)is undefined and deserves an in-depth investigation.Methods:Histologically-proven CHB receiving first-line antiviral regimens as initial therapy was enrolled and grouped by the concurrence of NAFLD,and followed up at six monthly intervals.Therapeutic response related data were recorded and compared at multiple time points.Kaplan-Meier and Cox regression analyses were utilized to estimate the impact of NAFLD on complete virological response(CVR).Results:We enrolled 267 patients(CHB:164;CHB with NAFLD:103)with comparable follow-up durations.They were also comparable in baseline HBV DNA levels and HBeAg positivity.Patients with concomitant NAFLD showed less significant decline in HBV DNA,qHBsAg,pgRNA,and liver enzyme levels over time;moreover,their cumulative incidences of CVR were significantly lower and that of low-level viremia(LLV)were significantly higher at 6,12,18,24 months.First CVR of CHB was delayed with the presence NAFLD(11.0 vs.7.0 months,p<0.001)and further prolonged with higher grade of liver steatosis(Grade 2–3 vs.1:13.0 vs.9.0 months).On multivariate analysis,HBeAg positivity(HR:0.650,p=0.036),grade of steatosis(G2[HR:0.447,p=0.004];G3[HR:0.085,p=0.002])and HBV DNA(log10 IU/mL)(HR:0.687,p<0.001)were significantly associated with delayed CVR,whereas grade of necroinflammation(HR:1.758,p<0.001)accelerated the CVR.Conclusions:In CHB patients receiving initial antiviral therapy,NAFLD was associated with higher levels of HBV DNA,pgRNA,and liver enzymes,and higher incidence of LLV and delayed CVR.

Immunogenicity of mucosal COVID-19 vaccine candidates based on the highly attenuated vesicular stomatitis virus vector(VSV_(MT))in golden syrian hamster

COVID-19 is caused by coronavirus SARS-CoV-2.Current systemic vaccines generally pro-vide limited protection against viral replication and shedding within the airway.Recombinant VSV(rVSV)is an effective vector which inducing potent and comprehensive immunities.Currently,there are two clinical trials investigating COVID-19vaccines based on VSV vectors.These vaccines were developed with spike protein of WA1 which administrated intramuscularly.Although intranasal route is ideal for activating mucosal immunity with VSV vector,safety is of concern.Thus,a highly attenuated rVSV with three amino acids mutations in matrix protein(VSV_(MT))was developed to construct safe mucosal vaccines against multiple SARS-CoV-2 variants of concern.It demonstrated that spike protein mutant lacking 21 amino acids in its cytoplasmic domain could rescue rVSV efficiently.VSV_(MT) indicated improved safeness compared with wild-type VSV as the vector encoding SARS-CoV-2 spike protein.With a single-dosed intranasal inoculation of rVSV_(ΔGMT)-S_(Δ21),potent SARS-CoV-2specific neutraliza-tion antibodies could be stimulated in animals,particularly in term of mucosal and cellular immunity.Strikingly,the chimeric VSV encoding S_(Δ21) of Delta-variant can induce more potent immune responses compared with those encoding S_(Δ21) of Omicron-or WA1-strain.VSV_(MT) is a promising platform to develop a mucosal vaccine for countering COVID-19.

In vivo antioxidant activity of rabbiteye blueberry(Vaccinium ashei cv.'Brightwell')anthocyanin extracts

Blueberries are rich in phenolic compounds including anthocyanins which are closely related to biological health functions.The purpose of this study was to investigate the antioxidant activity of blueberry anthocyanins extracted from'Brightwell'rabbiteye blueberries in mice.After one week of adaptation,C57BL/6J healthy male mice were divided into different groups that were administered with 100,400,or 800 mg/kg blueberry anthocyanin extract(BAE),and sacrificed at different time points(0.1,0.5,1,2,4,8,or 12 h).The plasma,eyeball,intestine,liver,and adipose tissues were collected to compare their antioxidant activity,including total antioxidant capacity(T-AOC),superoxide dismutase(SOD)activity and glutathione-peroxidase(GSH-PX/GPX)content,and the oxidative stress marker malondialdehyde(MDA)level.The results showed that blueberry anthocyanins had positive concentration-dependent antioxidant activity in vivo.The greater the concentration of BAE,the higher the T-AOC value,but the lower the MDA level.The enzyme activity of SOD,the content of GSH-PX,and messenger RNA(mRNA)levels of Cu,Zn-SOD,Mn-SOD,and GPX all confirmed that BAE played an antioxidant role after digestion in mice by improving their antioxidant defense.The in vivo antioxidant activity of BAE indicated that blueberry anthocyanins could be developed into functional foods or nutraceuticals with the aim of preventing or treating oxidative stress-related diseases.

Pan-cancer analysis of DNA epigenetic modifications by hydrophilic interaction liquid chromatography-tandem mass spectrometry

Accumulating evidence in recent years indicates that DNA methylation(5-methyl-2-deoxycytidine,5-mdC) and hydroxymethylation(5-hydroxymethyl-2-deoxycytidine, 5-hmd C) have been implicated in various biological processes, and the aberrations of these DNA cytosine modifications is tightly associated with cancer. N6-methyl-2-deoxyadenosine(m~6dA), as a newly discovered epigenetic modification in genome of mammals, has been demonstrated to play vital regulatory roles in tumorigenesis. However, the content information of m~6dA in human tumor tissues is still limited and pan-cancer analysis of these DNA epigenetic modifications is lacked. Herein, we developed a sensitive and robust stable isotopediluted hydrophilic interaction liquid chromatography-tandem mass spectrometry(HILIC-MS/MS) method for accurate quantification of m~6dA, 5-mdC and 5-hmdC in genomic DNA from 82 pairs of human tumor tissues and matched tumor-adjacent normal tissues. The types of tumors included esophagus cancer, lung cancer, breast cancer, liver cancer, pancreatic cancer, gastric cancer, stromal tumor and colorectal cancer.Compared to the normal tissues, we revealed the level of m6dA was increased in tumor tissues of esophagus cancer, lung cancer and liver cancer, whereas the level of m~6dA was diminished in tumor tissues of pancreatic cancer and gastric cancer;while the contents of 5-mdC and 5-hmdC exhibited significant decrease in tumor tissues of most types of cancer. It is worth noting that we revealed, for the first time,the content of genomic m~6dA in pancreatic cancer, stromal tumor and colorectal cancer. The significant changes of these DNA epigenetic modifications indicate they may serve as indicators of cancers. In addition, this study will benefit for better understanding of the regulatory roles of these DNA epigenetic modifications in cancers.

The north-east North Atlantic Tripole implicated as a predictor of the August precipitation decadal variability over north China

Monthly precipitation over north China in August(NCAP)is the second highest in the year,and it is important to understand its driving mechanisms to facilitate reliable forecasting.The NCAP displays a significant decadal variability of a cycle about 10-year and negatively correlates with the July north-east North Atlantic Tripole(NAT)over the decadal timescales.This study shows that the Eurasian decadal teleconnection(EAT)acts as a bridge that links the July NAT with NCAP decadal variability.This coupled ocean–atmosphere bridge(COAB)mechanism,through which the July NAT influences the decadal variability of NCAP,can be summarized as follows.The cumulative effect of the NAT drives the EAT to adjust atmospheric circulation over north China and the surrounding regions,and so regulates precipitation in north China by influencing local water vapor transport.When the July NAT is in a negative(positive)phase,the EAT pattern has a positive(negative)pattern,which promotes(weakens)the transmission of water vapor from the sea in the south-east to north China,thus increasing(decreasing)NCAP over decadal timescales.The decadal NCAP model established based on the July NAT can effectively predict the NCAP decadal variability,illustrating that the July NAT can be implicated as a predictor of the NCAP decadal variability.

Synoptic Climate Settings and Moisture Supply for the Extreme Heavy Snowfall in Northern China during 6–8 November 2021

A record-breaking extreme heavy snowfall(EHS)event hit northern China during 6–8 November 2021,with two maximum snowfall centers in North China(NC)and Northeast China(NEC),which inflicted severe socioeconomic impacts.This paper compares the differences in the synoptic processes and moisture supply associated with the EHS event in NC and NEC,as well as the atmospheric circulation anomalies before the event,to provide a reference for better prediction and forecasting of EHS in northern China.Synoptic analyses show that a positively tilted,inverted 500-hPa trough channeled cold-air outbreaks into NC,while dynamic updrafts along the front below the trough promoted moisture convergence over this region.In NEC,the dynamic updraft south of the frontogenesis region firstly triggered a low-level Yellow–Bohai Sea cyclone,which then converged with the 500-hPa trough to ultimately form an NEC cold vortex.Calculation of the vorticity tendency indicates that absolute vorticity advection was a better indicator than absolute vorticity divergence for the movement of the trough/ridge at the synoptic scale.Moreover,NOAA’s HYSPLIT(Hybrid Single-Particle Lagrangian Integrated Trajectory)model results reveal that the moisture for the EHS over NC mainly originated from the mid-to-low levels over the Asian–African region and the Eurasian mid-to-high latitudes,accounting for 32%and 31%,respectively.In contrast,the source of water vapor for the EHS over NEC was mainly the Eurasian mid-to-high latitudes and East Asia,with contributions of 38%and 28%,respectively.The findings of this study shed some fresh light on the distinctive contributions of different moisture sources to local precipitation.Further analyses of the atmospheric circulation anomalies in October reveal that a phase shift in the Arctic Oscillation related to the weakening of the polar vortex could have served as a useful indicator for the cold-air outbreaks in this EHS event.

戈壁中新乳齿象(Miomastodon gobiensis)头骨的发现及生物地层学分布

玛姆象科是象型类两个基本分支之一.然而由于发现材料的限制,学术界对早期欧亚大陆玛姆象类的解剖学特征及系统演化所知甚少.来自甘肃临夏盆地老沟地点的一件中新乳齿象头骨,是目前发现的第一件中新乳齿象头骨,也是欧亚大陆发现的第二件早-中中新世玛姆象科头骨,另外一件是发现于法国的苏黎世轭齿象(Zygolophodon turicensis),但保存不佳,因此,该标本对研究玛姆象类在早-中中新世的演化具有重要意义.新发现的标本颊齿轭型化程度比经典的苏黎世轭齿象(Zygolophodon turicensis)稍低,例如,齿脊比较粗壮,压缩齿谷,主齿柱新月嵴粗,侧视高度达齿谷的一半,牙齿釉质层厚.因此可归入之前在内蒙古通古尔中中新世报道过下颌的戈壁中新乳齿象(Miomastodon gobiensis).该头骨具有玛姆象类中的独特的衍征,例如,眼眶位置比苏黎世轭齿象靠后,且略偏向头顶.后一特征与豕脊齿象类相近,它的外鼻孔位置非常靠后,开口偏向上方,这些特征说明中新乳齿象在玛姆象科中具有独特的演化地位.中新乳齿象具有较显著的时代意义,早期较原始的同心中新乳齿象的时代为早中新世晚期到中中新世早期,约17~14 Ma;后期较进步的戈壁中新乳齿象的时代为中中新世晚期,在13.7~11.8 Ma左右.