Doping-enhanced robustness of anomaly-related magnetoresistance in WTe_(2±α)flakes

We study systematically the negative magnetoresistance(MR)effect in WTe_(2±α)flakes with different thicknesses and doping concentrations.The negative MR is sensitive to the relative orientation between electrical-/magnetic-field and crystallographic orientation of WTe_(2±α).The analysis proves that the negative MR originates from chiral anomaly and is anisotropic.Maximum entropy mobility spectrum is used to analyze the electron and hole concentrations in the flake samples.It is found that the negative MR observed in WTe_(2±α)flakes with low doping concentration is small,and the high doping concentration is large.The doping-induced disorder obviously inhibits the positive MR,so the negative MR can be more easily observed.In a word,we introduce disorder to suppress positive MR by doping,and successfully obtain the negative MR in WTe_(2±α)flakes with different thicknesses and doping concentrations,which indicates that the chiral anomaly effect in WTe_(2)is robust.

Combining Posterolateral Lumbar Fusion and Posterior Lumber Interbody Fusion Surgery for Treating Three-Level Lumber Spondylolysis and Single-Level Spondylolisthesis: Case Report

Lumbar spondylolysis is a relatively common condition that can cause a variety of clinical manifestations related to the lumbar spine. However, multi-level lumbar spondylolysis is rare and accounts for less than 6% of lumbar spondylolysis. We report a case of three-level lumbar spondylolysis with single-level spondylolisthesis. A 47-year-old woman presented to us with low back pain for 9 years that progressively worsened and the pain was exacerbated with standing and walking. She was diagnosed with three-level lumbar spondylolysis at L3-5 and spondylolisthesis at L4. We performed posterolateral lumber fusion (PLF) and posterior lumbar interbody fusion (PLIF) surgery for her. During the same period, pain recovery and fusion rate of the patient were evaluated after surgery. The results were favorable and proved the efficacy of combining PLF and PLIF technique for treatment for three-level lumbar spondylolysis and single-level spondylolisthesis.

Sign reversal of anisotropic magnetoresistance and anomalous thickness-dependent resistivity in Sr_(2)CrWO_(6)/SrTiO_(3) films

High-quality Sr_(2)CrWO_(6)(SCWO) films have been grown on SrTiO_(3)(STO) substrate by pulsed laser deposition under low oxygen pressure. With decrease of the film thickness, a drastic conductivity increase is observed. The Hall measurements show that the thicker the film, the lower the carrier density. An extrinsic mechanism of charge doping due to the dominance of oxygen vacancies at SCWO/STO interfaces is proposed. The distribution and gradient of carrier concentration in SCWO films are considered to be related to this phenomenon. Resistivity behavior observed in these films is found to follow the variable range hopping model. It is revealed that with increase of the film thickness, the extent of disorder in the lattice increases, which gives a clear evidence of disorder-induced localization charge carriers in these films.Magnetoresistance measurements show that there is a negative magnetoresistance in SCWO films, which is considered to be caused by the magnetic scattering of magnetic elements Cr^(3+) and W^(5+). In addition, a sign reversal of anisotropic magnetoresistance(AMR) in SCWO film is observed for the first time, when the temperature varies across a characteristic value, T_(M). Magnetization-temperature measurements demonstrate that this AMR sign reversal is caused by the direction transition of easy axis of magnetization from the in-plane ferromagnetic order at T > T_(M) to the out-of-plane at T < T_(M).

微米阵列结构聚合物薄膜的制备及其对细胞三维培养的影响

二维(Two-dimensional,2D)细胞实验模型是目前研究人类疾病的细胞过程和药物筛选的主流方法。然而,生物细胞的生长受到众多因素的影响,传统的2D细胞培养在精确再现三维组织内细胞的功能方面存在一些障碍。与2D细胞培养相比,三维(Three-dimensional,3D)细胞培养体系注重细胞间的接触及细胞-基质间的接触,更接近于生物体的生长环境,更适合于药物筛选、细胞培植等研究。文中通过纳米压印技术制备了不同结构微米阵列聚合物薄膜,并将其应用于293T细胞的培养,通过调节薄膜表面结构、表面接触角成功实现了对生物细胞生长形貌的调控。利用扫描电镜等方法,对比了聚合物薄膜不同微结构、不同表面润湿性对细胞生长形貌的影响,重点关注细胞团的形态变化。结果表明,细胞在亲水性10μm柱形阵列薄膜上呈现三维生长状态,这种薄膜可能更适用于制备生物细胞3D培养基;疏水性3μm柱形阵列薄膜适用于体积小、表皮硬的组织细胞的3D培养,对于体积较大的细胞效果差。另外,对于疏水性较强的薄膜,细胞倾向于球状生长,而亲水性较强的薄膜则易贴壁生长。研究结果为微结构薄膜在生物细胞3D培养方面的应用作了初步探索。

The Genome of Artemisia annua Provides Insight into the Evolution of Asteraceae Family and Artemisinin Biosynthesis

Artemisia annua, commonly known as sweet wormwood or Qinghao, is a shrub native to China and has long been used for medicinal purposes. A. annua is now cultivated globally as the only natural source of a potent anti-malarial compound, artemisinin. Here, we report a high-quality draft assembly of the 1.74-gigabase genome of A. annua, which is highly heterozygous, rich in repetitive sequences, and contains 63 226 protein-coding genes, one of the largest numbers among the sequenced plant species. We found that, as one of a few sequenced genomes in the Asteraceae, the A. annua genome contains a large number of genes specific to this large angiosperm clade. Notably, the expansion and functional diversification of genes encoding enzymes involved in terpene biosynthesis are consistent with the evolution of the artemi- sinin biosynthetic pathway. We further revealed by transcriptome profiling that A. annua has evolved the sophisticated transcriptional regulatory networks underlying artemisinin biosynthesis. Based on compre- hensive genomic and transcriptomic analyses we generated transgenic A. annua lines producing high levels of artemisinin, which are now ready for large-scale production and thereby will help meet the chal- lenge of increasing global demand of artemisinin.

Sedimentary and evolutionary characteristics of Sinian in the Tarim Basin

Analysis of Sinian outcrops in the peripheral regions of the Tarim Basin,drilling and seismic data within the Tarim Basin,and combined with previous studies,distribution of Sinian strata,tectonic setting,sedimentary system and lithofacies palaeogeography were well discussed.Results showed that three sedimentary systems were developed in the Sinian System of the Tarim Basin,i.e.the clastic sedimentary system,the clastic-carbonate mixed sedimentary system,and the carbonate sedimentary system,vertical sedimentary characteristics evolved from the clastic sedimentary system to the carbonate sedimentary system.These three sedimentary systems were corresponded to three transgression-regression cycles in the Sinian.The marine transgression during the initial period of the Early Sinian(ZSQI)resulted in development of the clastic sedimentary system in the lower part of the Lower Sinian;the transgression during the late period of the Early Sinian(ZSQII)led to formation of the clastic-carbonate mixed sedimentary system in the upper part of the Lower Sinian;the transgression during the initial period of the Late Sinian(ZSQIII)resulted in development of carbonate sedimentary system in the Upper Sinian.Three regressions resulted in formation of three unconformities,which were on the middle part of the Lower Sinian,the top of the Lower Sinian and the top of the Upper Sinian respectively.Due to breakup of Rodinia supercontinent in the Neoproterozoic,the Tarim Basin was in the continental rifting evolutionary process.In the Sinian,the basin experienced evolutionary processes of intra-cratonic depression and passive continental margin,thus characteristic of the lithofacies palaeogeography was characterized by uplifts in the south and depressions in the north.In the Early Sinian,the Tarim Basin developed the Bachu-Tazhong-Tadongnan uplift and the Tabei residual ancient land,and the shore-shelf sedimentary environment in the north as well as the shore-shelf-bathyal sedimentary environment in the southwest.In the Late Sinian,the Tabei residual ancient land disappeared;the basin developed the tidal flat sedimentary environment in the north and the neritic sedimentary environment of the passive continental margin in the southwest.