1.2†W single-frequency Tm3+/Ho3+ co-doped fiber oscillator at 2050†nm.

In this Letter, a watt-level single-frequency fiber oscillator at 2050 nm was demonstrated for the first time, to the best of our knowlegde, in a linear laser cavity with a piece of an un-pumped Tm3+/Ho3+ co-doped fiber serving as a saturable absorber. With delicate optimization of mode filtering effect of the dynamic gratings formed in the saturable absorber, a maximum single-frequency laser output power of 1.2 W was achieved under a total bidirectional pump power of 5.8 W at 1570 nm, and the corresponding optical efficiency is 20.7%. This is, to the best of our knowledge, the highest power of a single-frequency fiber oscillator at the wavelength above 2 µm.

Multifunctional Modulation of High-Performance Znx Fe3-x O4 Nanoparticles by Precisely Tuning the Zinc Doping Content.

The possibility to precisely control important properties of nanoparticles (NPs) such as their size, morphology, surface charge, or doping content is crucial for enhancing the performance of existing solutions beyond the state-of-the-art and for enabling novel applications. In this work, custom-tailored Znx Fe3- x O4 NPs are synthesized at different Zn doping concentrations to augment and expand their usefulness for high-performance applications in nanomedicine. By precisely increasing the Zn2+ content in the range of 0 ≤ x ≤ 2.0, the discussed NPs can sequentially acquire valuable properties enabling magnetic resonance imaging, near-infrared (NIR) photothermal effects, NIR photocatalytic and photoelectric effects, depending on the variation of substitution position of the Zn2+ in the magnetite structure and the emergence of a ZnO/ZnFe2 O4 heterostructure at high doping concentrations. The presented work demonstrates and explainsa facile route for the synthesis and modulation of multifunctional nanomaterials with manifold roles in disease diagnostics and therapy, and provides helpful guidance in designing divalent transition metal ion-doped nanomaterials.

High-energy single-frequency pulsed fiber MOPA at 1064†nm based on a hybrid active-fiber.

We report a single-frequency pulsed Yb-doped fiber master-oscillator-power-amplifier at 1064 nm producing output with pulse energy of 0.6 mJ for a pulse width of 95 ns at a pulse repetition frequency of 5 kHz. Integral to this laser design was the application of a hybrid active-fiber, which integrated a length of heavily Yb-doped phosphosilicate fiber (with a core diameter of 50 µm) with a silica gain fiber (with core diameter of 35 µm). This was used in the power amplifier stage to both suppress stimulated Brillouin scattering and to enhance the gain saturation for improved efficiency and spectral signal to noise ratio. The seed pulses were pre-shaped so that sawtooth-like pulses were obtained after amplification, this having the effect of preventing linewidth broadening induced by self-phase modulation. A spectral linewidth of ∼15 MHz was measured at the maximum peak power of 6.3 kW.

Antiferromagnetism in Ni-Based Superconductors.

Due to the lack of any magnetic order down to 1.7 K in the parent bulk compound NdNiO2 , the recently discovered 9-15 K superconductivity in the infinite-layer Nd0.8 Sr0.2 NiO2 thin films has provided an exciting playground for unearthing new superconductivity mechanisms. Herein, the successful synthesis of a series of superconducting Nd0.8 Sr0.2 NiO2 thin films ranging from 8 to 40 nm is reported. The large exchange bias effect is observed between the superconducting Nd0.8 Sr0.2 NiO2 films and a thin ferromagnetic layer, which suggests the existence of the antiferromagnetic order. Furthermore, the existence of the antiferromagnetic order is evidenced by X-ray magnetic linear dichroism measurements. These experimental results are fundamentally critical for the current field.

An HSP90 cochaperone Ids2 maintains the stability of mitochondrial DNA and ATP synthase.

BACKGROUND: Proteostasis unbalance and mitochondrial dysfunction are two hallmarks of aging. While the chaperone folds and activates its clients, it is the cochaperone that determines the specificity of the clients. Ids2 is an HSP90's cochaperone controlling mitochondrial functions, but no in vivo clients of Ids2 have been reported yet. RESULTS: We performed a screen of the databases of HSP90 physical interactors, mitochondrial components, and mutants with respiratory defect, and identified Atp3, a subunit of the complex V ATP synthase, as a client of Ids2. Deletion of IDS2 destabilizes Atp3, and an α-helix at the middle region of Ids2 recruits Atp3 to the folding system. Shortage of Ids2 or Atp3 leads to the loss of mitochondrial DNA. The intermembrane space protease Yme1 is critical to maintaining the Atp3 protein level. Moreover, Ids2 is highly induced when cells carry out oxidative respiration. CONCLUSIONS: These findings discover a cochaperone essentially for maintaining the stability of mitochondrial DNA and the proteostasis of the electron transport chain-crosstalk between two hallmarks of aging.

Electric Field Control of the Magnetic Weyl Fermion in an Epitaxial SrRuO3 (111) Thin Film.

The magnetic Weyl fermion originates from the time reversal symmetry (TRS)-breaking in magnetic crystalline structures, where the topology and magnetism entangle with each other. Therefore, the magnetic Weyl fermion is expected to be effectively tuned by the magnetic field and electrical field, which holds promise for future topologically protected electronics. However, the electrical field control of the magnetic Weyl fermion has rarely been reported, which is prevented by the limited number of identified magnetic Weyl solids. Here, the electric field control of the magnetic Weyl fermion is demonstrated in an epitaxial SrRuO3 (111) thin film. The magnetic Weyl fermion in the SrRuO3 films is indicated by the chiral anomaly induced magnetotransport, and is verified by the observed Weyl nodes in the electronic structures characterized by the angle-resolved photoemission spectroscopy (ARPES) and first-principles calculations. Through the ionic-liquid gating experiment, the effective manipulation of the Weyl fermion by electric field is demonstrated, in terms of the sign-change of the ordinary Hall effect, the nonmonotonic tuning of the anomalous Hall effect, and the observation of the linear magnetoresistance under proper gating voltages. The work may stimulate the searching and tuning of Weyl fermions in other magnetic materials, which are promising in energy-efficient electronics.

The genus Tripterygium: A phytochemistry and pharmacological review.

The genus Tripterygium belongs to the family Celastraceae, and contains three species, i.e. Tripterygium wilfordii Hook. F, Tripterygium hypoglaucum (Levl.) Hutch. and Tripterygium regelii Sprague et Takeda. All three species are reported to have excellent medicinal properties that help to cure rheumatoid arthritis, nephrotic syndrome, systemic lupus erythematosus and widely used as a folk medicine in China. Phytochemical studies have led to discovering more than 500 secondary metabolites in this genus, including five main types: sesquiterpenoids, diterpenes, triterpenoids, flavonoids, lignans. This work provides structurally grouping statistic of 198 secondary metabolites of Tripterygium species published from 2008 to the present, as well as pharmacological knowledges in the past five years. The information will be helpful for developing the new discoveries of medicinal value related to the genus Tripterygium.

Glucose intake hampers PKA-regulated HSP90 chaperone activity.

Aging is an intricate phenomenon associated with the gradual loss of physiological functions, and both nutrient sensing and proteostasis control lifespan. Although multiple approaches have facilitated the identification of candidate genes that govern longevity, the molecular mechanisms that link aging pathways are still elusive. Here, we conducted a quantitative mass spectrometry screen and identified all phosphorylation/dephosphorylation sites on yeast proteins that significantly responded to calorie restriction, a well-established approach to extend lifespan. Functional screening of 135 potential regulators uncovered that Ids2 is activated by PP2C under CR and inactivated by PKA under glucose intake. ids2Δ or ids2 phosphomimetic cells displayed heat sensitivity and lifespan shortening. Ids2 serves as a co-chaperone to form a complex with Hsc82 or the redundant Hsp82, and phosphorylation impedes its association with chaperone HSP90. Thus, PP2C and PKA may orchestrate glucose sensing and protein folding to enable cells to maintain protein quality for sustained longevity.

Spin Direction-Controlled Electronic Band Structure in Two-Dimensional Ferromagnetic CrI3.

Manipulating physical properties using the spin degree of freedom constitutes a major part of modern condensed matter physics and is a key aspect for spintronics devices. Using the newly discovered two-dimensional van der Waals ferromagnetic CrI3 as a prototype material, we theoretically demonstrated a giant magneto band-structure (GMB) effect whereby a change of magnetization direction significantly modifies the electronic band structure. Our density functional theory calculations and model analysis reveal that rotating the magnetic moment of CrI3 from out-of-plane to in-plane causes a direct-to-indirect bandgap transition, inducing a magnetic field controlled photoluminescence. Moreover, our results show a significant change of Fermi surface with different magnetization directions, giving rise to giant anisotropic magnetoresistance. Additionally, the spin reorientation is found to modify the topological states. Given that a variety of properties are determined by band structures, our predicted GMB effect in CrI3 opens a new paradigm for spintronics applications.

Large-scale calculations of thermoelectric transport coefficients: a case study of γ-graphyne with point defects.

Defects such as vacancies and impurities could have profound effects on the transport properties of thermoelectric materials. However, it is usually quite difficult to directly calculate the thermoelectric properties of defect-containing systems via first-principles methods since a very large supercell is required. In this work, based on the linear response theory and the kernel polynomial method, we present an efficient approach that can help to calculate the thermoelectric transport coefficients of a large system containing millions of atoms at arbitrary chemical potential and temperature. As a prototype example, we consider dilute vacancies and hydrogen impurities in a large-scale γ-graphyne sheet and discuss their effects on the thermoelectric transport properties.