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result(s) for
"Zhao, Kan"
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Transcriptome Sequences Resolve Deep Relationships of the Grape Family
2013
Previous phylogenetic studies of the grape family (Vitaceae) yielded poorly resolved deep relationships, thus impeding our understanding of the evolution of the family. Next-generation sequencing now offers access to protein coding sequences very easily, quickly and cost-effectively. To improve upon earlier work, we extracted 417 orthologous single-copy nuclear genes from the transcriptomes of 15 species of the Vitaceae, covering its phylogenetic diversity. The resulting transcriptome phylogeny provides robust support for the deep relationships, showing the phylogenetic utility of transcriptome data for plants over a time scale at least since the mid-Cretaceous. The pros and cons of transcriptome data for phylogenetic inference in plants are also evaluated.
Journal Article
Asian summer monsoon variability across Termination II and implications for ice age terminations
2025
The detailed anatomy of Termination I (TI) is well depicted, but whether changes across Termination II (TII) resemble TI remains controversial. Here we present high-resolution Asian monsoon records covering TII using Shima Cave stalagmites from China. Correlating marine and ice-core records to our U/Th-dated records via millennial-scale variabilities, we find an initial CO
2
rise from 139 ± 1 ka BP concordant with boreal summer insolation increase, which was followed by a major rise phase of CO
2
between 135.7 ± 1 and 129 ± 1 ka BP. The major rise phases of CO
2
were comparable during TI and TII, but the initial CO
2
rise before TII was distinct from CO
2
behavior before TI, likely forced by the Earth’s internal variabilities, in particular an ice-sheet collapse event and a 50% reduction in southern hemisphere dust flux. Here, we show that ~4000–5000-year-long gradual changes in CO
2
, along with insolation rise, preconditioned glacial terminations, supporting the “tipping point” theory.
U/Th-dated Asian monsoon records from Shima Cave, covering 142–122 ka BP, constrain the timing of a CO
2
rise at ~139 ka BP caused by millennial-scale variabilities, which, along with increasing orbital solar radiation, prepare for the end of ice age.
Journal Article
A high-resolution stalagmite record of the Holocene East Asian monsoon from Mt Shennongjia, central China
2010
High-resolution oxygen isotope (δ18O) profiles of six stalagmites from Sanbao Cave in Hubei province, central China, established with 1413 oxygen isotope data and 65 230Th ages, provide a continuous history of East Asian Summer Monsoon (EASM) intensity for the period from 13—0.2 thousand years before present (ky BP, relative to AD 1950). The δ 18O record includes four distinct stages in the evolution of the EASM: (1) an abrupt transition (~11.5 ky BP) into the Holocene; (2) a period of gradual increase in monsoon intensity (11.5—9.5 ky BP); (3) the maximum humid period (9.5—6.5 ky BP); and (4) a period of gradual decline in monsoon intensity (6.5—0.2 ky BP). Comparison of Sanbao with regional records of comparable resolution reveals that the timing of the beginning and end of the Holocene Optimum (as defined by the minimum in δ18 O) was similar in the Indian and East Asian monsoon systems. This supports the idea that shifts in the monsoon tied to shifts in the mean position of the Inter-Tropical Convergence Zone (ITCZ) may control monsoon intensity throughout the entire low-latitude region of Asia on orbital timescales. This observation also supports the idea that the fluctuations in δ18 O recorded across southern Asia reflect broad changes in the monsoon, as opposed to local meteoric precipitation. The EASM records from Sanbao largely follow orbital-scale insolation changes, yet exhibit similar variability to Greenland ice core δ18O on millennial to centennial scales during the early to middle Holocene (r = 0.94).
Journal Article
Evidence for solar cycles in a late Holocene speleothem record from Dongge Cave, China
2014
The association between solar activity and Asian monsoon (AM) remains unclear. Here we evaluate the possible connection between them based on a precisely-dated, high-resolution speleothem oxygen isotope record from Dongge Cave, southwest China during the past 4.2 thousand years (ka). Without being adjusted chronologically to the solar signal, our record shows a distinct peak-to-peak correlation with cosmogenic nuclide
14
C, total solar irradiance (TSI) and sunspot number (SN) at multi-decadal to centennial timescales. Further cross-wavelet analyses between our calcite δ
18
O and atmospheric
14
C show statistically strong coherence at three typical periodicities of ~80, 200 and 340 years, suggesting important roles of solar activities in modulating AM changes at those timescales. Our result has further indicated a better correlation between our calcite δ
18
O record and atmospheric
14
C than between our record and TSI. This better correlation may imply that the Sun–monsoon connection is dominated most likely by cosmic rays and oceanic circulation (both associated to atmospheric
14
C), instead of the direct solar heating (TSI).
Journal Article
Continental shelf area inundation drove reduced temperature seasonality in East Asia during the last deglaciation
2025
East Asia (EA) has experienced a decreasing trend in the summer-to-winter temperature difference (temperature seasonality) in the context of ongoing global warming. However, the impacts of natural external forcing remain unclear. The last deglaciation, marked by substantial global warming, provides a paleoclimate context for understanding the roles of natural forcing in EA temperature seasonality changes. Here, using transient simulations (iTraCE), we demonstrate that EA experienced greater winter warming compared to summer during the last deglaciation, supported by paleo-climatic reconstructions. Sensitivity experiments indicate that the inundation of continental shelf area due to rising sea-level played a critical role in driving these differential warming trends. Further quantifications highlight the contributions of greater heat capacity instead of reduced surface albedo of the expanded ocean area. Resulting atmospheric responses expanded the seasonality change to EA landmass by cloud‒radiation feedback and temperature advection processes. These findings provide insight into the potential climatic impacts of sea-level rise under ongoing global warming.
Journal Article
High-Precision Time-Frequency Signal Simultaneous Transfer System via a WDM-Based Fiber Link
by
Zhao, Kan
,
Zhang, Shougang
,
Quan, Honglei
in
Communications systems
,
Computer networks
,
Crosstalk
2021
In this paper, we demonstrate a wavelength division multiplexing (WDM)-based system for simultaneously delivering ultra-stable optical frequency reference, 10 GHz microwave frequency reference, and a one pulse per second (1 PPS) time signal via a 50 km fiber network. For each signal, a unique noise cancellation technique is used to maintain their precision. After being compensated, the transfer frequency instability in terms of the overlapping Allan deviation (OADEV) for the optical frequency achieves 2 × 10−17/s and scales down to 2 × 10−20/10,000 s, which for the 10 GHz microwave reference, approaches 4 × 10−15/s and decreases to 1.4 × 10−17/10,000 s, and the time uncertainty of the 1 PPS time signal along the system is 2.08 ps. In this scheme, specific channels of WDM are, respectively, occupied for different signals to avoid the possible crosstalk interference effect between the transmitted reference signals. To estimate the performance of the above scheme, which is also demonstrated in this 50 km link independent of these signals, the results are similar to that in the case of simultaneous delivery. This work shows that the WDM-based system is a promising method for building a nationwide time and frequency fiber transfer system with a communication optical network.
Journal Article
miR-30a downregulation aggravates pressure overload-induced cardiomyocyte hypertrophy
by
Ning, Wenhu
,
Ren, Zhongqiao
,
Zhao, Kan
in
3' Untranslated Regions
,
Animals
,
Atrial Natriuretic Factor - genetics
2013
miRNAs play an important role in the pathogenesis of cardiac hypertrophy and dysfunction. However, little is known about how miR-30a regulates cardiomyocyte hypertrophy. In the study, Male C57BL/6 mice were subjected to thoracic aortic constriction, and hearts were harvested at 3 weeks. We assayed miR-30a expression level by real-time PCR and defined the molecular mechanisms of miR-30a-mediated cardiomyocyte hypertrophy. We found that myocardial expression of miR-30a was decreased in mouse models of hypertrophy and in H9c2 cells treated with phenylephrine. MiR-30a inhibition markedly increased mRNA expression of cardiac hypertrophy markers such as atrial natriuretic factor and brain natriuretic peptide in H9c2, and cell size was increased after miR-30a inhibitor treatment. Downregulated miR-30a activated autophagy by inhibiting beclin-1 expression in H9c2 cell. More important, autophagy inhibition suppressed miR-30a inhibitor-induced cardiomyocyte hypertrophy. Together, our data demonstrated that downregulated miR-30a aggravates pressure overload-induced cardiomyocyte hypertrophy by activating autophagy, thus offering a new target for the therapy of cardiomyocyte hypertrophy.
Journal Article
Magnetic Evolution of Carrier Doping and Spin Dynamics in Diluted Magnetic Semiconductors (Ba,Na)(Zn,Mn)2As2
by
Sheng, Qi
,
Gu, Bo
,
Jin, Changqing
in
Asymmetry
,
Curie temperature
,
diluted magnetic semiconductor
2025
The investigation of novel diluted magnetic semiconductors (DMSs) provides a promising platform for studying magnetism and transport characteristics, with significant implications for spintronics. DMSs based on BaZn2As2 are particularly noteworthy due to their high Curie temperature (TC) of 260 K, diverse magnetic states, and potential for multilayer heterojunctions. This study investigates the magnetic evolution of carrier doping and spin dynamics in the asperomagnet (Ba,Na)(Zn,Mn)2As2, utilizing a combination of magnetization measurements, ac susceptibility, and muon spin rotation (µSR). Key findings include the following: (1) lower transition temperatures and coercive forces in (Ba,Na)(Zn,Mn)2As2 compared to the ferromagnet (Ba,K)(Zn,Mn)2As2; (2) a dynamic fluctuation peak around the transition temperature observed in both the ac susceptibility and longitudinal field (LF) µSR; and (3) the coexistence of static and dynamic states at low temperatures, exhibiting spin-glass-like characteristics. This study, to the best of our knowledge, may represent the first investigation of asperomagnetic order utilizing µSR techniques. It enhances the understanding of magnetic interactions in BaZn2As2-based systems and provides valuable insights into the exploration of high TC DMSs.
Journal Article
Doping Effects on Magnetic and Electronic Transport Properties in (Ba1−xRbx)(Zn1−yMny)2As2 (0.1 ≤ x, y ≤ 0.25)
by
Gu, Bo
,
Jin, Changqing
,
Zhao, Kan
in
carrier concentration
,
Carrier density
,
colossal magnetoresistance
2025
Diluted magnetic semiconductors (DMSs) represent a significant area of interest for research and applications in spintronics. Recently, DMSs derived from BaZn2As2 have garnered significant interest due to the record Curie temperature (TC) of 260 K. However, the influence of doping on their magnetic evolution and transport characteristics has not been thoroughly investigated. This study aims to fill this gap through susceptibility and magnetization measurements, electric transport analysis, and muon spin relaxation and rotation (µSR) measurements on (Ba1−xRbx)(Zn1−yMny)2As2 (0.1 ≤ x, y ≤ 0.25, BRZMA). Key findings include the following: (1) BRZMA showed a maximum TC of 138 K, much lower than (Ba,K)(Zn,Mn)2As, because of a reduced carrier concentration. (2) A substantial electromagnetic coupling is evidenced by a negative magnetoresistance of up to 34% observed in optimally doped BRZMA. (3) A 100% static magnetic ordered volume fraction is achieved in the low-temperature region, indicating a homogeneous magnet. (4) Furthermore, a systematic and innovative methodology has been initially proposed, characterized by clear step-by-step instructions aimed at enhancing TC, grounded in robust experimental findings. The findings presented provide valuable insights into the spin–charge interplay concerning magnetic and electronic transport properties. Furthermore, they offer clear direction for the investigation of higher TC DMSs.
Journal Article
Post-translational cleavage of HMW-GS Dy10 allele improves the cookie-making quality in common wheat (Triticum aestivum)
2021
Wheat is a major staple food crop worldwide because of the unique properties of wheat flour. High molecular weight glutenin subunits (HMW-GSs), which are among the most critical determinants of wheat flour quality, are responsible for the formation of glutenin polymeric structures via interchain disulfide bonds. We herein describe the identification of a new HMW-GS
Dy10
allele (
Dy10-m619SN
)
.
The amino acid substitution (serine-to-asparagine) encoded in this allele resulted in a partial post-translational cleavage that produced two new peptides. These new peptides disrupted the interactions among gluten proteins because of the associated changes to the number of available cysteine residues for interchain disulfide bonds. Consequently,
Dy10-m619SN
expression decreased the size of glutenin polymers and weakened glutens, which resulted in wheat dough with improved cookie-making quality, without changes to the glutenin-to-gliadin ratio. In this study, we clarified the post-translational processing of HMW-GSs and revealed a new genetic resource useful for wheat breeding.
Journal Article