The enormous repetitive Antarctic krill genome reveals environmental adaptations and population insights.

Antarctic krill (Euphausia superba) is Earth's most abundant wild animal, and its enormous biomass is vital to the Southern Ocean ecosystem. Here, we report a 48.01-Gb chromosome-level Antarctic krill genome, whose large genome size appears to have resulted from inter-genic transposable element expansions. Our assembly reveals the molecular architecture of the Antarctic krill circadian clock and uncovers expanded gene families associated with molting and energy metabolism, providing insights into adaptations to the cold and highly seasonal Antarctic environment. Population-level genome re-sequencing from four geographical sites around the Antarctic continent reveals no clear population structure but highlights natural selection associated with environmental variables. An apparent drastic reduction in krill population size 10 mya and a subsequent rebound 100 thousand years ago coincides with climate change events. Our findings uncover the genomic basis of Antarctic krill adaptations to the Southern Ocean and provide valuable resources for future Antarctic research.

Cytidine diphosphate diacylglycerol synthase is essential for mitochondrial structure and energy production in Arabidopsis thaliana.

Cytidine diphosphate diacylglycerol (CDP-DAG), an important intermediate for glycerolipid biosynthesis, is synthesized under the catalytic activity of CDP-DAG synthase (CDS) to produce anionic phosphoglycerolipids such as phosphatidylglycerol (PG) and cardiolipin (CL). Previous studies showed that Arabidopsis CDSs are encoded by a small gene family, termed CDS1-CDS5, the members of which are integral membrane proteins in endoplasmic reticulum (ER) and in plastids. However, the details on how CDP-DAG is provided for mitochondrial membrane-specific phosphoglycerolipids are missing. Here we present the identification of a mitochondrion-specific CDS, designated CDS6. Enzymatic activity of CDS6 was demonstrated by the complementation of CL synthesis in the yeast CDS-deficient tam41Δ mutant. The Arabidopsis cds6 mutant lacking CDS6 activity showed decreased mitochondrial PG and CL biosynthesis capacity, a severe growth deficiency finally leading to plant death. These defects were rescued partly by complementation with CDS6 or supplementation with PG and CL. The ultrastructure of mitochondria in cds6 was abnormal, missing the structures of cristae. The degradation of triacylglycerol (TAG) in lipid droplets and starch in chloroplasts in the cds6 mutant was impaired. The expression of most differentially expressed genes involved in the mitochondrial electron transport chain was upregulated, suggesting an energy-demanding stage in cds6. Furthermore, the contents of polar glycerolipids in cds6 were dramatically altered. In addition, cds6 seedlings lost the capacity for cell proliferation and showed a higher oxidase activity. Thus, CDS6 is indispensable for the biosynthesis of PG and CL in mitochondria, which is critical for establishing mitochondrial structure, TAG degradation, energy production and seedling development.

Characteristics of broadband OPCPA based on DKDP crystals with different deuterations for the SEL-100 PW laser system.

We present the performances of a broadband optical parametric chirped pulse amplification (OPCPA) using partially deuterated potassium dihydrogen phosphate (DKDP) crystals with deuteration levels of 70% and 98%. When pumped by a Nd:glass double frequency laser, the OPCPA system using the 98% deuterated DKDP crystal achieves a broad bandwidth of 189 nm (full width at 1/e2 maximum) from 836 nm to 1025 nm. For the DKDP crystal with length of 43 mm, the pump-to-signal conversion efficiency reaches 28.4% and the compressed pulse duration is 13.7 fs. For a 70% deuterated DKDP crystal with a length of 30 mm, the amplified spectrum ranges from 846-1021 nm, the compressed pulse duration is 15.7 fs, and the conversion efficiency is 25.5%. These results demonstrate the potential of DKDP crystals with higher deuteration as promising nonlinear crystals for use as final amplifiers in 100 Petawatt (PW) laser systems, supporting compression pulse duration shorter than 15 fs.

Caspase-3-Triggered Intracellular Gadolinium Nanoparticle Formation for T1-Weighted Magnetic Resonance Imaging of Apoptosis In Vivo.

Apoptosis, with a hallmark of upregulated protease Caspase-3, has been frequently imaged with various probes to reveal the therapeutic efficiencies of different drugs. However, activatable molecular probes with programmable self-assembling behaviors that enable enhanced T1-weighted magnetic resonance imaging (MRI) of apoptosis remain scarce. Herein, taking advantage of a CBT-Cys click reaction, we rationally designed a Caspase-3-activatable self-assembling probe Ac-Asp-Glu-Val-Asp-Cys(StBu)-Lys(DOTA(Gd))-CBT (DEVDCS-Gd-CBT) for apoptosis imaging in vivo. After Caspase-3 cleavage in apoptotic cells, DEVDCS-Gd-CBT underwent CBT-Cys click reaction to form a cyclic dimer, which self-assembled into Gd nanoparticles. With this probe, enhanced T1-weighted MR images of apoptosis were achieved at low magnetic fields in vitro, in cis-dichlorodiamineplatinum-induced apoptotic cells and in tail-amputation-simulated apoptotic zebrafish. We anticipate that the smart probe DEVDCS-Gd-CBT could be applied for T1-weighted MRI of apoptosis-related diseases in the clinic in the future.

Research on the pre-pulses caused by post-pulses in the optical parametric chirped-pulse amplifier.

Pre-pulses caused by the post-pulses in the optical parametric chirped-pulse amplifier were comprehensively studied for the first time, including the underlying mechanism for the delay-shift of pre-pulses, the intensity variation of pre-pulses affected by the initial delay of post-pulses and the pump energy, and also the nonlinear beat noise. The simulation and measurement confirmed that the high-order dispersion of the pulse stretcher was the main cause for the delay-shift of pre-pulses, which should be similar with the chirped-pulse amplifiers. The intensity of pre-pulses would decrease significantly as the initial delay of post-pulses increased, but would increase with the growth of pump energy. Moreover, the temporal position of the nonlinear beat noise in the experiment was successfully predicted by our simulation. This work could help us better understand the pre-pulses in OPCPA and provide helpful guidance for designing high-contrast laser systems.

Ultra-broad bandwidth low-dispersion mirror with smooth dispersion and high laser damage resistance.

Low-dispersion mirrors (LDMs), which require a broad bandwidth, low dispersion, and high damage threshold, are essential optics in ultra-intense and ultra-short laser devices. Bragg mirrors and chirped LDMs do not satisfy these requirements simultaneously. We propose a novel LDM (NLDM) based on the hump-like structure and quarter wavelength optical thickness (QWOT) structure to achieve a broad bandwidth, smooth dispersion, and high robustness. The spectral and dispersion characteristics of the two structures compensate for each other, which makes up for the deficiency that the dispersion bandwidth of the sinusoidal modulation structure cannot be broadened. Based on this structure, the LDM can achieve a design bandwidth of 240 nm and support the transmission of sub-11-fs pulses. The accuracy of the NLDM is experimentally evaluated. The structure shows the potential for broad-spectrum laser damage performance due to the low electric field intensity. The NLDM improves the mirror performance and paves the way for a new generation of ultra-intense and ultra-short laser devices.

Highly stable, flexible delivery of microjoule-level ultrafast pulses in vacuumized anti-resonant hollow-core fibers for active synchronization.

We demonstrate the stable and flexible light delivery of multi-microjoule, sub-200-fs pulses over a ∼10-m-long vacuumized anti-resonant hollow-core fiber (AR-HCF), which was successfully used for high-performance pulse synchronization. Compared with the pulse train launched into the AR-HCF, the transmitted pulse train out of the fiber exhibits excellent stabilities in pulse power and spectrum, with pointing stability largely improved. The walk-off between the fiber-delivery and the other free-space-propagation pulse trains, in an open loop, was measured to be <6 fs root mean square (rms) over 90 minutes, corresponding to a relative optical-path variation of <2 × 10-7. This walk-off can be further suppressed to ∼2 fs rms simply by using an active control loop, highlighting the great application potentials of this AR-HCF setup in large-scale laser and accelerator facilities.

Delay-shift and asymmetric broadening of pre-pulses by post-pulses in a petawatt laser facility.

The temporal contrast of high-peak-power lasers is usually limited by pre-pulses, which are generally produced by post-pulses due to the nonlinearity of the active medium. The reason for the conversion between pre-pulse and post-pulse is now well known, but the mechanisms for the delay-shift and asymmetric broadening of the newly generated pre-pulse are not yet clear. In this work, a novel, to the best of our knowledge, numerical model combining the nonlinear Schrödinger equation and the Frantz-Nodvik equation is proposed to investigate the underlying mechanisms for the "distortion" of the pre-pulse. Numerical results show that the gain characteristics of Ti:sapphire amplifiers can only make a minor change on the temporal profile of the pre-pulse, but the high-order dispersion is the main cause for the delay-shift and asymmetric broadening of the pre-pulse, and the effects are more significant for the initial post-pulse with a relatively larger delay.

Transcriptome analyses reveal the effects of mixed saline-alkali stress on indoleacetic acid and cytokinins in Malus hupehensis Rehd. leaves.

Saline-alkali stress is a universal abiotic stress factor limiting fruit tree cultivation worldwide. Apple (Malus×domestica Borkh.) is one of the fruits with the largest yields worldwide. Tea crabapple (Malus hupehensis Rehd. var. pingyiensis Jiang) is a type of common apple rootstock in China. Because facultative apomixis occurs in this species, it is often used in molecular research. The present study investigated the molecular mechanism of the response of indoleacetic acid (IAA) and cytokinins [zeatin, trans-zeatin riboside (tZR), isopentenyladenine (iP), and isopentenyladenosine (iPA)] to mixed saline-alkali stress (MSAS) in tea crabapple leaves. The endogenous hormone content of tea crabapple leaves under MSAS was measured, and the expression of stress response-related genes was analyzed by RNA sequencing. The results showed that the concentration of IAA was initially higher and then lower than that in the control, whereas the concentration of zeatin, tZR, iP, and iPA was higher than that in the control. A total of 1262 differentially expressed genes were identified in the three comparison groups. Further analyses suggested that IAA and cytokinin biosynthetic genes were mostly upregulated in tea crabapple leaves, indicating that auxin and cytokinin signaling pathway regulation occurred in response to MSAS. These findings suggest that IAA and cytokinins play an important role in the response of tea crabapple to MSAS. Supplementary Information: The online version contains supplementary material available at 10.1007/s12298-022-01275-4.

Angular dispersion compensation for ultra-broadband pulses by using a cascaded prism and hollow-core fiber configuration.

In this paper, we report that the angular dispersion of the output pulses in a nonlinear process can be efficiently compensated by using a cascaded prism(s) and short hollow-core fiber (HCF) configuration. Here, the prism(s) is used to suppress the angular dispersion and transform it into spatial chirp, while the HCF is used for removing this spatial chirp and the residual angular dispersion, which can also significantly improve the beam quality. The feasibility of this novel method is numerically and experimentally investigated with the ultra-broadband idler pulses centered at 1250 nm wavelength and generated by an LBO crystal based non-collinear optical parametric amplifier. The proof-of-principle experiment shows that the angular dispersion can be effectively removed and ultra-broadband idler pulses with good spectral quality and spatial profile can be obtained. The total transmission efficiency in the experiment is around 67% and the measured M x2 and M y2 can reach 1.12 and 1.04, respectively. To the best of our knowledge, this is the first reported ultra-broadband angular dispersion compensation scheme combining prism(s) and HCF, which can remarkably eliminate the angular dispersion while simultaneously possesses high efficiency, good spectral and beam spatial quality.

Suppressing scattering-induced nanosecond pre-pulses in Ti:sapphire multi-pass amplifiers.

In this Letter, we experimentally investigate a new kind of nanosecond pre-pulse, which originates from the bidirectional scattering of crystals in traditional Ti:sapphire multi-pass amplifiers. The experimental results demonstrate that the intensity of scattering-induced pre-pulses is very sensitive to the scattering angle, and the delay time between the pre-pulse and the main pulse is an integer multiple of the light path in each pass of the amplifier. An optimized multi-pass amplifier configuration is proposed, for what is believed to be the first time, to suppress the scattering-induced pre-pulses. The contrast ratio between pre-pulses and the main pulse is enhanced by more than two orders of magnitude, reaching a level of 10-10. This novel multi-pass amplifier configuration is very simple and economical, and provides an effective solution for the temporal contrast enhancement in the nanosecond range.

Investigation and suppression of pre-pulses on nanosecond time scale in the SULF-1PW laser.

It is of crucial significance to investigate and suppress pre-pulses on nanosecond time scale because the intense pre-plasma generated by them may have enough time to expand and, thus, cause fatal impact on laser-matter interactions. In this research, we analyze the potential origins of pre-pulses on nanosecond time scale in a typical Ti:sapphire chirped pulse amplification laser system. Based on the analysis, the initial status of these generated pre-pulses in the SULF-1PW laser is measured and investigated. Then different measures, including fine control on the time synchronization and the replacement for the Ti:sapphire, are adopted in the SULF-1PW laser to suppress these pre-pulses with respective origins, which can promote the energy ratio between the main pulse and these pre-pulses by 2-3 orders of magnitude. This research not only improves the temporal contrast of the SULF-1PW laser on nanosecond time scale but also provides beneficial guidance for the design and construction of similar laser facilities.

Coordinated Adsorption and Catalytic Conversion of Polysulfides Enabled by Perovskite Bimetallic Hydroxide Nanocages for Lithium-Sulfur Batteries.

Catalysis is an effective remedy for the fast capacity decay of lithium-sulfur batteries induced by the shuttling of lithium polysulfides (LiPSs), but too strong adsorption ability of many catalysts toward LiPSs increases the risk of catalyst passivation and restricts the diffusion of LiPSs for conversion. Herein, perovskite bimetallic hydroxide (CoSn(OH)6 ) nanocages are prepared, which are further wrapped by reduced graphene oxide (rGO) as the catalytic host for sulfur. Because of the coordinated valence state of Co and Sn and the intrinsic defect of the perovskite structure, such bimetallic hydroxide delivers moderate adsorption ability and enhanced catalytic activity toward LiPS conversion. Coupled with the hollow structure and the wrapped rGO as double physical barriers, the redox reaction kinetics, and sulfur utilization are effectively improved with such a host. The assembled battery delivers a good rate performance with a high capacity of 644 mAh g-1 at 2 C and long stability with a capacity decay of 0.068% per cycle over 600 cycles at 1 C. Even with a higher sulfur loading of 3.2 mg cm-2 and a low electrolyte/sulfur ratio of 5 µL mg-1 , the battery still shows high sulfur utilization and good cycling stability.

Performance improvement of a nonlinear temporal filter by using cascaded femtosecond optical parametric amplification.

In this paper, we report that the conversion efficiency and spectrum of femtosecond optical parametric amplification (fs-OPA) can be significantly enhanced by employing a compact cascaded femtosecond OPA (CF-OPA) scheme with the self-compensation of the temporal walk-off between two nonlinear gain media. Correspondingly, the gain related temporal contrast can also be improved. The feasibility of the CF-OPA method using three cascaded BBO crystals is numerically and experimentally analyzed. Moreover, by replacing the conventional fs-OPA with the CF-OPA and optimizing the design, the performance of a nonlinear temporal filter combining cross-polarized wave generation and fs-OPA is comprehensively improved. The experimental results demonstrate the superiority of the CF-OPA scheme, which can generate high-performance cleaned pulses at 1 kHz repetition rate with energy of 340µJ, energy fluctuation below 0.9% (RMS), spectral width of 97 nm (FWHM), Fourier-transform-limited pulse width of 12 fs and temporal contrast better than 10-12. To the best of our knowledge, this is the first reported temporal walk-off self-compensated quasi-collinear CF-OPA geometry adopting three cascaded BBO crystals, which can be easily generalized to other wavelengths or nonlinear crystals. The above nonlinear temporal filter with a CF-OPA scheme has the rarest comprehensive parameters, which can provide excellent seed pulses for PW and 10 PW class femtosecond laser systems.

Numerical analysis of the DKDP-based high-energy optical parametric chirped pulse amplifier for a 100 PW class laser.

An optical parametric chirped pulse amplifier (OPCPA) based on a large-aperture DKDP crystal and pumped by a 10 kJ level Nd:glass laser can serve as the final amplifier for a 100 PW level laser. A comprehensive numerical investigation on such a high-energy OPCPA is presented in this work. The effects on the efficiency-bandwidth product induced by the deuteration level, absorption loss, temperature variation, and optimization of zero-phase-mismatch wavelength (ZPMW) are analyzed in detail. Based on the analysis above, a three-dimensional numerical simulation taking into account the effects of pumping depletion, diffraction, and walk-off shows that, by optimization of ZPMW, broadband (over 210 nm spectral width in FWHM) and high efficiency (${\gt}37\%$) amplification can be realized in the DKDP crystal even with a moderate deuteration level of 70%, which can relax the requirement of a high deuteration level in a large-aperture DKDP crystal. The numerical analysis can provide meaningful guidance for the design and construction of 100 PW class laser systems.

The Application of Low-Frequency Transition in the Assessment of the Second-Order Zeeman Frequency Shift.

Second-order Zeeman frequency shift is one of the major systematic factors affecting the frequency uncertainty performance of cesium atomic fountain clock. Second-order Zeeman frequency shift is calculated by experimentally measuring the central frequency of the (1,1) or (-1,-1) magnetically sensitive Ramsey transition. The low-frequency transition method can be used to measure the magnetic field strength and to predict the central fringe of (1,1) or (-1,-1) magnetically sensitive Ramsey transition. In this paper, we deduce the formula for magnetic field measurement using the low-frequency transition method and measured the magnetic field distribution of 4 cm inside the Ramsey cavity and 32 cm along the flight region experimentally. The result shows that the magnetic field fluctuation is less than 1 nT. The influence of low-frequency pulse signal duration on the accuracy of magnetic field measurement is studied and the optimal low-frequency pulse signal duration is determined. The central fringe of (-1,-1) magnetically sensitive Ramsey transition can be predicted by using a numerical integrating of the magnetic field "map". Comparing the predicted central fringe with that identified by Ramsey method, the frequency difference between these two is, at most, a fringe width of 0.3. We apply the experimentally measured central frequency of the (-1,-1) Ramsey transition to the Breit-Rabi formula, and the second-order Zeeman frequency shift is calculated as 131.03 × 10-15, with the uncertainty of 0.10 × 10-15.

Clinicopathologic comparisons of IgA nephropathy and IgA vasculitis nephropathy in children: a ten-year single-center experience.

BACKGROUND: To investigate the similarities and differences of renal clinical and renal pathology between IgA nephropathy (IgAN) and IgA vasculitis nephritis (IgAVN) in children. METHODS: A total of 237 children with IgAN and 190 children with IgAVN were included. The general conditions, clinical characteristics, final diagnosis, clinical and pathological classification of the children were intercepted at the time of admission, and the retrospective comparative analysis was carried out. RESULTS: The results showed that the median course of disease in IgAN group was longer than that in IgAVN group (p = 0.02). Patients with IgAN had a significantly higher duration of infection than the patients with IgAVN (p = 0.03). The white blood cell count (WBC), hemoglobin (HGB) in IgAN group were significantly lower than that in IgAVN group (p = 0.02). The serum creatinine in IgAN group was higher than that in IgAVN group (p = 0.02). Patients with IgAN and IgAVN had statistically significant differences in pathological typing between clinical types: hematuria and proteinuria, nephrotic syndrome and chronic nephritis (p = 0.004). DISCUSSION: The clinical manifestations of IgAN and IgAVN were similar, but the onset of IgAN was hidden and the clinical manifestations were relatively serious. Renal pathology was mainly glomerulosclerosis and renal tubular atrophy. IgAVN was characterized by acute onset and good renal function. Renal pathology was dominated by endothelial hyperplasia and crescent formation. These differences did not support the hypothesis that the two diseases are the same.

Simultaneous measurement of the absolute and relative time delay of a tiled-aperture coherent beam combination via the double-humped spectral beam interferometry.

Coherent beam combination (CBC) is a promising technology for achieving several hundred petawatts and even EW-level lasers. However, the measurement of the synchronization error and the time jitter of CBC is one of key technical issues, especially in the few-cycle PW-level laser facilities. In this paper, we demonstrate that the absolute time delay (ATD) and the relative time delay (RTD) for a tiled-aperture CBC can simultaneously be measured by using the double-humped spectral beam interferometry. The experimental study also was demonstrated. A root-mean-square deviation of approximately λ/38 (70 as) and a combining efficiency of 87.3% at 1 Hz closed feedback loop was obtained, respectively. Due to the wide adjustment range and a vast resisting beam energy disturbance capacity, this technique provide an effective and practical solution for measuring simultaneously the ATD and the RTD in the few-cycle PW-level laser pulses CBC.

Investigation of the temporal contrast evolution in a 10-PW-level Ti:sapphire laser facility.

We have theoretically and experimentally investigated the evolution of the temporal contrast in a 10-PW-level Ti:sapphire laser in the Shanghai Superintense Ultrafast Laser Facility (SULF). The effects induced by the grism pair, spectral shaping filter, and increase in gain on the temporal contrast were investigated. First, it was found that the energy loss of clean seed pulses in the grism pair is a major factor in contrast degradation. Because of the low transmission efficiency of the grism pair (~10%), the temporal contrast is degraded by one order of magnitude. Second, the spectral shaping filter in the regenerative amplifier degrades the temporal contrast by increasing the intracavity loss. Finally, as the amplified spontaneous emission pedestal experiences gain more than the main pulse in Ti:sapphire amplifiers, particularly during saturated amplification, the temporal contrast will further deteriorate as the gain increases in multi-stage Ti:sapphire amplifiers. In addition, the effect on the temporal contrast induced by the extraction during pumping technique in large-aperture Ti:sapphire amplifiers has been considered. According to the investigations described above, the design of the SULF can be further improved. It is predicted that a temporal contrast of over 10-11 can be achieved at a peak power of 10 PW following the improvements. The investigations conducted in this study can provide guidelines for improving the temporal contrast in ultrahigh-peak-power Ti:sapphire lasers.

Tunable defect modes of one-dimensional photonic crystals containing a Dirac semimetal-based metamaterial defect layer.

The transmission properties of one-dimensional photonic crystals (PCs) containing a metamaterial (MM) defect layer are investigated using the transfer matrix method. The MM is composed of alternating layers of a dielectric material and a Dirac semimetal (DS) material. Numerical results show that the defective PCs possess a tunable defect mode, which is significantly dependent on the Fermi level of the DS as well as the structural parameters of the MM defect layer. The defect mode properties under different incident angles for TE and TM polarizations are also studied. Such defective structures have potential applications in tunable filters and sensors in terahertz regions.