Ultracold field-linked tetratomic molecules

Ultracold polyatomic molecules offer intriguing new opportunities in cold chemistry, precision measurements, and quantum information processing, thanks to their rich internal structure. However, their increased complexity compared to diatomic molecules presents a formidable challenge to employ conventional cooling techniques. Here, we demonstrate a new approach to create ultracold polyatomic molecules by electroassociation in a degenerate Fermi gas of microwave-dressed polar molecules through a field-linked resonance. Starting from ground state NaK molecules, we create around $1.1\times 10^3$ tetratomic (NaK)$_2$ molecules, with a phase space density of $0.040(3)$ at a temperature of $134(3)\,\text{nK}$, more than $3000$ times colder than previously realized tetratomic molecules. We observe a maximum tetramer lifetime of $8(2)\,\text{ms}$ in free space without a notable change in the presence of an optical dipole trap, indicating these tetramers are collisionally stable. The measured binding energy and lifetime agree well with parameter-free calculations, which outlines pathways to further increase the lifetime of the tetramers. Moreover, we directly image the dissociated tetramers through microwave-field modulation to probe the anisotropy of their wave function in momentum space. Our result demonstrates a universal tool for assembling ultracold polyatomic molecules from smaller polar molecules, which is a crucial step towards Bose--Einstein condensation (BEC) of polyatomic molecules and towards a new crossover from a dipolar Bardeen-Cooper-Schrieffer (BCS) superfluid to a BEC of tetramers. Additionally, the long-lived FL state provides an ideal starting point for deterministic optical transfer to deeply bound tetramer states

Experimental Study on Rheological Properties and Strength Variation of High Concentration Cemented Unclassified Tailings Backfill

This experimental study presents the rheological properties and strength characteristics of cemented unclassified tailings backfill (CUTB). The particle size distribution and chemical properties of tailings from the Shizhuyuan lead-zinc mine were examined experimentally. A series of rheological properties and uniaxial compressive strength (UCS) tests were conducted to study the relations between the rheological properties of CUTB and two factors of cement-tailings ratio (c/t) and solid content (SD). The two-factor nonrepetitive analysis of variance (ANOVA) method was used to study the sensitivity of rheological properties to two factors of c/t and SD. Relations between UCS performance of CUTB and c/t, SD, and curing time (CT) were discussed. Results indicate that CUTB samples exhibit obvious shear thinning characteristics and the rheological process is the result of multiple rheological model composites. Yield stress and viscosity of CUTB increase with the increase of SD and c/t as quadratic. The solid content is the most important factor for the rheological properties of CUTB, followed by c/t. UCS of CUTB increases exponentially with the increase of SD and increases with c/t as quadratic. The larger the ratio of c/t, the greater the influence of the CT on the increasing strength of CUTB. The smaller the c/t, the slower the increase of the CUTB’s strength with the increase of the SD. The findings of this study can provide the efficient mix proportion of backfill slurry for the backfill mining design, so as to have better performance of the underground mining structure and reduce the cost of backfill mining

Experimental Study on Limestone Cohesive Particle Model and Crushing Simulation

This study investigates the effect of impact velocity and particle size on crushing characteristics. We use a discrete-element method simulation and construct cohesive limestone particles with internal microinterfaces and cracks for impact crushing experimentation. The simulation model follows the same process as the impact crushing experiment. Results show that, after crushing at impact velocities of 30 and 40 m/s, the simulated particle-size distribution curve matches experimental results as closely as 95%. For different particle sizes, results are more than 90% in agreement. These results indicate the feasibility of the cohesive-particle crushing simulation model. When the particle size is 15 mm, an approximate linear relationship exists on impact velocity and crushing ratio. For a constant impact velocity, the particle size of 18 mm results in the maximum crushing ratio

Mesenchymal Migration on Adhesive–Nonadhesive Alternate Surfaces in Macrophages

Abstract Mesenchymal migration usually happens on adhesive substrates, while cells adopt amoeboid migration on low/nonadhesive surfaces. Protein‐repelling reagents, e.g., poly(ethylene) glycol (PEG), are routinely employed to resist cell adhering and migrating. Contrary to these perceptions, this work discovers a unique locomotion of macrophages on adhesive–nonadhesive alternate substrates in vitro that they can overcome nonadhesive PEG gaps to reach adhesive regions in the mesenchymal mode. Adhering to extracellular matrix regions is a prerequisite for macrophages to perform further locomotion on the PEG regions. Podosomes are found highly enriched on the PEG region in macrophages and support their migration across the nonadhesive regions. Increasing podosome density through myosin IIA inhibition facilitates cell motility on adhesive–nonadhesive alternate substrates. Moreover, a developed cellular Potts model reproduces this mesenchymal migration. These findings together uncover a new migratory behavior on adhesive–nonadhesive alternate substrates in macrophages

Elevation of Extracellular Ca²⁺ Induces Store-Operated Calcium Entry via Calcium-Sensing Receptors: A Pathway Contributes to the Proliferation of Osteoblasts

<div><p>Aims</p><p>The local concentration of extracellular Ca²⁺ ([Ca²⁺]_o) in bone microenvironment is accumulated during bone remodeling. In the present study we investigated whether elevating [Ca²⁺]_o induced store-operated calcium entry (SOCE) in primary rat calvarial osteoblasts and further examined the contribution of elevating [Ca²⁺]_o to osteoblastic proliferation.</p><p>Methods</p><p>Cytosolic Ca²⁺ concentration ([Ca²⁺]_c) of primary cultured rat osteoblasts was detected by fluorescence imaging using calcium-sensitive probe fura-2/AM. Osteoblastic proliferation was estimated by cell counting, MTS assay and ATP assay. Agonists and antagonists of calcium-sensing receptors (CaSR) as well as inhibitors of phospholipase C (PLC), SOCE and voltage-gated calcium (Cav) channels were applied to study the mechanism in detail.</p><p>Results</p><p>Our data showed that elevating [Ca²⁺]_o evoked a sustained increase of [Ca²⁺]_c in a dose-dependent manner. This [Ca²⁺]_c increase was blocked by TMB-8 (Ca²⁺ release inhibitor), 2-APB and BTP-2 (both SOCE blockers), respectively, whereas not affected by Cav channels blockers nifedipine and verapamil. Furthermore, NPS2143 (a CaSR antagonist) or U73122 (a PLC inhibitor) strongly reduced the [Ca²⁺]_o-induced [Ca²⁺]_c increase. The similar responses were observed when cells were stimulated with CaSR agonist spermine. These data indicated that elevating [Ca²⁺]_o resulted in SOCE depending on the activation of CaSR and PLC in osteoblasts. In addition, high [Ca²⁺]_o significantly promoted osteoblastic proliferation, which was notably reversed by BAPTA-AM (an intracellular calcium chelator), 2-APB, BTP-2, TMB-8, NPS2143 and U73122, respectively, but not affected by Cav channels antagonists.</p><p>Conclusions</p><p>Elevating [Ca²⁺]_o induced SOCE by triggering the activation of CaSR and PLC. This process was involved in osteoblastic proliferation induced by high level of extracellular Ca²⁺ concentration.</p></div

TG induced SOCE in rat calvarial osteoblasts.

<p>(A) After calcium store depletion by a calcium pump blocker TG (1 µM) in Ca²⁺-free buffer, addition of 2 mM external Ca²⁺ resulted in obvious calcium entry; then, further removal of external Ca²⁺ caused [Ca²⁺]_c decrease to baseline, suggesting the putative response for SOCE. (C, E) [Ca²⁺]_c increase was caused by TG (1 µM) in Ca²⁺-free HBSS, followed by application of 25 µM 2-APB or 20 µM BTP-2 during the high [Ca²⁺]_c plateau induced by re-addition of 2 mM external Ca²⁺, resulting in return to baseline [Ca²⁺]_c. Statistic data of ratio of F340/F380 before and after the application of Ca²⁺ free HBSS (B), 2-APB (D) and BTP-2 (F). * showed <i>P</i><0.05. (G) 1 µM TG was added after pretreatment with 25 µM 2-APB or 20 µM BTP-2 for 15 min, then, further addition of 2 mM external Ca²⁺ had no effect on [Ca²⁺]_c change. (H) Summary of the ratio of F340/F380 at 400 s from experiments shown in (G), * showed <i>P</i><0.05.</p

[Ca²⁺]_o-induced SOCE was involved in the high [Ca²⁺]_o-induced proliferation in rat calvarial osteoblasts.

<p>(A) Osteoblasts were cultured in medium containing different levels of [Ca²⁺]_o or in a medium with 2 µM BAPTA-AM+10 mM [Ca²⁺]_o. Typical cell morphological images were captured at 0 h, 24 h and 48 h and 72 h using a 10× objective. (B) Statistic data of cell numbers from experiments shown in (A). Each group of cells were grown in triplicate dishes and counted at different time points by measuring at least five regions (1 mm×1 mm grids). *<i>P</i><0.05, compared with control group (normal DMEM medium); # <i>P</i><0.05, compared with 10 mM [Ca²⁺]_o group. (C) Summary of absorbance (A₄₉₀) in each group. Absorbance (A₄₉₀) assessed by MTS assay is proportional to the number of living cells. Osteoblasts were incubated for 72 h in culturing medium with different levels of [Ca²⁺]_o or in a medium with 2 µM BAPTA-AM+10 mM [Ca²⁺]_o (n = 7 for each case), * showed <i>P</i><0.05, compared with [Ca²⁺]_o  = 1.8 mM group; # showed <i>P</i><0.05, compared with [Ca²⁺]_o  = 10 mM group. (D) Statistic data of cell numbers in each group at different time points. Osteoblasts were cultured in medium containing 10 mM [Ca²⁺]_o alone or together with 2-APB (25 µM), BTP-2 (20 µM), TMB-8 (50 µM), NPS2143 (10 µM), U73122 (5 µM), U73343 (5 µM), nifedipine (10 µM) and verapamil (10 µM), respectively. * showed <i>P</i><0.05 in comparison with [Ca²⁺]_o  = 10 mM group. (E) Summary of absorbance (A₄₉₀) measured after culturing for 72 h in [Ca²⁺]_o = 10 mM medium alone or 2-APB (25 µM), BTP-2 (20 µM), TMB-8 (50 µM), NPS2143 (10 µM), U73122 (5 µM), U73343 (5 µM), nifedipine (10 µM) and verapamil (10 µM) (n = 7 for each case), respectively. * showed <i>P</i><0.05 compared with [Ca²⁺]_o = 10 mM group.</p

Two-Step Vapor Deposition of Self-Catalyzed Large-Size PbI2 Nanobelts for High-Performance Photodetectors

The grown lead iodide (PbI2) is usually a two-dimensional sheet with a finite size which necessitates sophisticated device metallization and the growth of quasi one-dimensional materials is still challenging. In this work, large-size (length 4 100 mm), single-crystalline and high-density PbI2 nanobelts are successfully synthesized by manipulating the microenvironment in a two-step vapor deposition process at a slow heating rate of B18 1C min 1. Firstly, PbI2 nanosheet seeds are grown by physical vapor deposition, and then PbI2 nanobelts are synthesized by a self-catalyzed vapor-liquid-solid growth mechanism, which is verified by the Pb nanoparticles on the nanobelt tips. Photoluminescence and ultraviolet-visible spectra show the uniform high-quality crystallinity of the as-prepared large-size PbI2 nanobelts with a bandgap of 2.36 eV. When configured into photodetectors with a shadow mask, the fabricated device exhibits a low dark current of 4 pA, an impressive ON/ OFF current ratio of 103-104, a photoresponsivity of 13 mA W 1, and a fast response with the rise and decay time constants of 425 and 41 ms, respectively. All these performances are comparable to those of state-of-the-art layered PbI2 nanostructure photodetectors, but the ease of synthesizing large-size PbI2 nanobelts may have a useful impact on next-generation easily-fabricated high-performance optoelectronics