Crystallization of smooth amorphous calcium phosphate microspheres to core-shell hydroxyapatite microspheres.

Calcium phosphates (Ca-P) represent a significant class of biological minerals found in natural hard tissues. Crystallization through phase transformation of a metastable precursor is an effective strategy to guide the growth of crystalline Ca-P with exceptional functionality. Despite extensive research on Ca-P, the exact process during the crystallization of amorphous particles to hydroxyapatite (HA) remains elusive. Herein, pure HA microspheres with a core-shell structure are crystallized via dissolution and re-crystallization of smooth amorphous calcium phosphate (ACP) microspheres. The transformation is initiated with the increase of the hydrothermal treatment time in the presence of sodium trimetaphosphate and l-glutamic. The underlying mechanisms along with the kinetics of such transformation are explored. Nanocrystalline areas are formed on the smooth ACP microspheres and crystallization advances via nanometre-sized clusters formed by directional arrangement of nanocrystalline whiskers. Our findings shed light on a crucial but unclear stage in the genesis of HA crystals, specifically under the conditions of hydrothermal synthesis.

Initial solution pH value for the construction of a 3D hydroxyapatite via the trisodium citrate-assisted hydrothermal route.

In this study, a trisodium citrate (TSC)-assisted hydrothermal method is utilized to prepare three-dimensional hydroxyapatite (3D HA). Understanding the role of TSC in the preparation of 3D HA crystals may provide valuable methods to design advanced biomaterials. As one of the indexes of solution supersaturation, the initial pH (ipH) value can not only directly affect the nucleation rate, but also affect the growth of HA crystals. In this work, the effect of the ipH on the microstructure, particle size distribution, and specific surface area of the 3D HA is explored. Results showed that the morphology of 3D HA transformed from a bundle to a dumbbell ball and then a dumbbell with an increase in the ipH. A corresponding mechanism of such a structural evolution was proposed, providing inspiration for the fabrication of innovative 3D HA structures with enhanced biological functionality and performance.

High-purity La3-xTe4 Material with Superior Thermoelectric Performance Synthesized via Te-vapor Transport and Solid-State Diffusion.

La3-xTe4 is a very promising high-temperature candidate applied in next-generation Radioisotope Thermoelectric Generators (RTGs). Conventional synthesis of such materials is based on the mechanochemical method, which makes the sample difficult to purify due to the high-energy ball milling. In this report, a novel synthetic method is developed, which utilizes Te-vapor transport and solid-phase diffusion to efficiently produce the RE3-xTe4 phases (RE = La, Ce, Pr, Nd). Notably, this method obviates the requirement for high-energy ball-milling instruments, conventionally indispensable in the mechanochemical syntheses. For as-synthesized La2.74Te4 material, a high figure of merit of 1.5 is achieved at 1073 K, owning to the reduced electronic thermal conductivity with metal impurities well eliminated.

Mg-Defect Compensation to Realize High Performance at Room Temperature in Mg3Bi2-Based Thermoelectric Single Crystals.

Mg3Bi2-based materials are a very promising substitute for current commercial Bi2Te3 thermoelectric alloys. The successful growth of Mg3Bi2-based single crystals with high room-temperature performance is especially significant for practical applications. Previous studies indicated that the effective suppression of Mg defects in Mg3Bi2-based materials was crucial for high performance, which was usually realized by applying excessive Mg during syntheses. However, utilization of excessive Mg generates Mg-rich phases between the crystalline boundaries and is unfavorable for the long-term stability of the materials. Here, bulk single crystals with a low-content Mg component such as Mg3.1Bi1.49Sb0.5Te0.01 were successfully grown. For compensating Mg defects, Li was chosen as the additional electron dopant. The results indicate that Li is a very effective electron compensator when low-concentration doping is applied. For high-concentration doping, Mg atoms in the lattice are substituted by Li, leading to decreased electron concentration again. This strategy is very significant for improving the room-temperature performance of Mg3Bi2-based materials. As a result, a record-high figure of merit of 1.05 at 300 K is achieved for Mg3+xLi0.003Bi1.49Sb0.5Te0.01 single crystals.

MSR405: Inhibiting Neuroinflammation after Spinal Cord Injury in Rats.

The treatment of spinal cord injury (SCI) is often ineffective. Additionally, SCI-induced inflammation leads to secondary injury. Current anti-inflammatory hydrophilic drugs fail to reach the nerve injury site due to the blood-brain barrier. Here, we synthesized MSR405, a new lipophilic unsaturated fatty acid derivative of Radix Isatidis and investigated its therapeutic effect in SCI model rats. Furthermore, we systematically investigated its structure, toxicity, anti-inflammatory effect, and the underlying mechanism. MSR405 was injected into the abdominal cavity of the Sprague Dawley SCI model rats, and the effect on their behavioral scores and pathology was estimated to assess the status of neurological inflammation. Our data show that MSR405 treatment significantly improved the motor function of SCI rats, and markedly suppressed the associated neuroinflammation. Moreover, MSR405 could attenuate LPS-induced inflammatory response in BV2 cells (Mouse microglia cells) in vitro. Mechanistically, MSR405 inhibits proinflammatory cytokines, supporting the anti-inflammatory response. Additionally, MSR405 can significantly block the TLR4/NF-κB signaling pathway and nitric oxide production. In summary, MSR405 reduces inflammation in SCI rats through the TLR4/NF-κB signal cascade and can inhibit neuroinflammation after spinal cord injury.

Cation Substitution and Size Effects in Ca2ZnSb2 and Yb2MnSb2: Crystal and Electronic Structures and Thermoelectric Properties.

Zintl compounds often feature complex structural fragments and small band gaps, favoring promising thermoelectric properties. In this work, a new phase Ca2ZnSb2 is synthesized and characterized to be a LiGaGe-type structure. It is isotypic to Yb2MnSb2 with half vacancies at transition metal sites and undergoes a phase transition to Ca9Zn4+xSb9 after annealing. Interestingly, Ca2ZnSb2 and Yb2MnSb2 are amenable to diverse doping mechanisms at different sites. Here, by substituting smaller Li on cation sites, two novel layered compounds Ca1.84(1)Li0.16(1)Zn0.84(1)Sb2 and Yb1.82(1)Li0.18(1)Mn0.96(1)Sb2 with the P63/mmc space group are discovered, which can be viewed as derivatives of LiGaGe type. Despite having lower occupancy, the structural stability is improved compared with the prototype compounds owing to the reduced interlayered distances. Besides, the band structure analyses demonstrate that the bands near the Fermi level are mainly governed by the interlayered interaction. Due to the highly disordered structure, Yb1.82Li0.18Mn0.96Sb2 features ultralow thermal conductivity from 0.79 to 0.47 W·m-1·K-1 among the testing range; in addition, a remarkable Seebeck coefficient of 270.77 µV·K-1 at 723 K is observed. The discovery of the Ca2ZnSb2 phase enriches the 2-1-2 map, and the size effect induced by cations provides new ideas for material designing.

Room-Temperature Ferromagnetism in Mg1-xMn2+xAs2 with Layered Structure.

A series of Mg/Mn mixed intermetallic compounds Mg1-xMn2+xAs2 (x = 0.17, 0.48, 0.69) were synthesized by using metal flux reactions. Single-crystal X-ray diffraction measurements indicated that CaAl2Si2-type phases with Mn and Mg atoms located on the cation sites (Wickoff site: 1a) were obtained. The special structure of these Mg1-xMn2+xAs2 compounds corresponded to unique magnetic behavior, which led to increased divergence between zero-field-cooling (ZFC) and field-cooling magnetic susceptibilities with decreasing temperature. The small magnetic hysteresis loop measured at 300 K for Mg0.31(2)Mn2.69As2 revealed its room-temperature ferromagnetism, and its ZFC exchange bias behavior at low temperatures indicated the existence of both ferromagnetic (FM) and antiferromagnetic (AFM) interactions. Spin-polarized density functional theory calculations were also performed to verify the magnetic ground state, and these were consistent with the experimental results.

Effect of Graphene on Modified Asphalt Microstructures Based on Atomic Force Microscopy.

Atomic force microscopy (AFM) was used to explore the effects of graphene modifier on the microstructure of asphalt. The morphologies of the before- and after-aged base asphalt and modified asphalt were performed and compared with analysis. The formation mechanism of asphaltic "bee structures" and the influence mechanism of graphene on asphalt were discussed from the classical theory of material science (phase transformation theory and diffusion theory). The results show that graphene facilitates the nucleation of "bee structures", resulting in an increasing number and decreasing volume of "bee structures" in modified asphalt. Additionally, the anti-aging performance of the modified asphalt improved significantly because of graphene incorporation.

Enhanced Thermoelectric Performance of LiZnSb-Alloyed CaZn0.4Ag0.2Sb by Band Engineering.

LiZnSb is a Zintl phase that has been predicted to be a good material in thermoelectric applications for a long time. However, experimental work indicated that the synthesized LiZnSb materials were p type, and their maximum zT value is only 0.08 at 525 K. CaZn0.4Ag0.2Sb, which belongs to the LiGaGe structure type and is also closely associated with the LiZnSb structure, did show high zT plateaus in a wide range of temperature, with the mixed transition metal Zn/Ag sites regulated. By comparing their crystallographic and electronic band structures, it is evident that the interlayered distances in both compounds have a great effect on the regulation of the corresponding electrical transport properties. When alloying CaZn0.4Ag0.2Sb with LiZnSb, solid solutions form within a specific range, which led to a marked enhancement in the Seebeck coefficient through the orbital alignment and carrier concentration optimization. In addition, a low thermal conductivity was obtained owing to the reduced electronic component. With the above optimization, a maximum zT value of ∼1.3 can be realized for (CaZn0.4Ag0.2Sb)0.87(LiZnSb)0.13 at 873 K, more than twice that of the pristine CaZn0.4Ag0.2Sb and about 10-fold compared to that of LiZnSb. This work may shed new light on the optimization of thermoelectric properties based on Zintl phases, for which the crystal structures are usually very complicated and a direct correlation between the structures and properties is difficult to make.

Sr9Mg4.45(1)Bi9 and Sr9Mg4.42(1)Sb9: Mg-Containing Zintl Phases with Low Thermal Conductivity.

Zintl phases with nominal 9-4-9 formulas are very interesting for their potential applications as thermoelectric materials. However, the formation of such phases usually requires divalent transition metals, for example, Zn, Mn, and Cd, which are covalently bonded to the pnictogen atoms. In this report, for the first time, two Mg-containing compounds with such structures as Sr9Mg4.45(1)Bi9 and Sr9Mg4.42(1)Sb9 were synthesized and their structures were determined by the single-crystal X-ray diffraction method. Both title compounds crystallize in the orthorhombic space group Pnma and are isostructural with Ca9Mn4.41(1)Sb9, which features complex polyanion structures compared to the classical 9-4-9 phases. For Sr9Mg4.45(1)Bi9, its low thermal conductivity, combined with its high electrical conductivity and moderate Seebeck coefficient, leads to a decent figure of merit of 0.57 at 773 K, which obviously prevails in the unoptimized 9-4-9 phases. The discovery of such Mg-containing 9-4-9 phases is very significant, as the discovery not only enriches the structure map of the well-known 9-4-9 family but also provides very valuable thermoelectric candidates surely deserving of more in-depth investigation.

Spin filtering controller induced by phase transitions in fluorographane.

The electronic and transport properties of fluorographane (C2HF) nanoribbons, i.e., bare (B-C2HF) and hydrogen-passivated (H-C2HF) C2HF nanoribbons, are extensively investigated using first-principles calculations. The results indicate that edge states are present in all the B-C2HF nanoribbons, which are not allowed in the H-C2HF nanoribbons regardless of the directions. The spin splitting phenomenon of band structure only appears in the zigzag direction. This behavior mainly originates from the dehydrogenation operation, which leads to sp2 hybridization at the edge. The H-C2HF nanoribbons are semiconductors with wide band gaps. However, the band gap of B-C2HF nanoribbons is significantly reduced. Remarkably, the phase transition can be induced by the changes in the magnetic coupling at the nanoribbon edges. In addition, the B-C2HF nanoribbons along the zigzag direction show optimal conductivity, which is consistent with the band structures. Furthermore, a perfect spin filtering controller can be achieved by changing the magnetization direction of the edge C atoms. These results may serve as a useful reference for the application of C2HF nanoribbons in spintronic devices.

Germanium Crystalline Nanomaterials for Li-Ion Storage Prepared by Decomposing LiZnGe in Air.

Germanium nanomaterials are important for their potential applications in many fields. However, current synthetic technologies usually involve either high-cost explosive reagents or complicated facilities, which make the mass production especially challenging. In this report, a method was developed to synthesize nano-Ge materials conveniently, realized by decomposing LiZnGe in air at room temperature. The process is nontoxic, inexpensive, and, most of all, very suitable for large-scale production in combination with ball milling. The as-prepared Ge nanomaterials are crystalline whose structures can be flexibly tuned through the ball milling syntheses. As the lithium-ion battery anode, such Ge nanomaterials exhibited long-term cycle ability with high specific capacity as well as excellent rate performance. These results not only provided a very efficient way to prepare nano-Ge in lab or even promising industry production but also suggested a universal method in synthesizing the tetrels elemental nanomaterials.

Exploring New Zintl Phases in the 9-4-9 Family via Al Substitution. Synthesis, Structure, and Physical Properties of Ae9Mn4-xAlxSb9 (Ae = Ca, Yb, Eu).

Three new quaternary Zintl phases with the "9-4-9" formula, Ae9Mn4-xAlxSb9 (Ae = Ca, Yb, Eu), have been synthesized using Pb as the metal flux, and their crystal structures have been established by single-crystal X-ray diffraction. Both Ca9Mn2.91(4)Al1.09Sb9 and Yb9Mn3.59(6)Al0.41Sb9 are isostructural with Ca9Mn4Bi9, and they crystallize in the orthorhombic space group Pbam with unit cell dimensions of a = 12.4571(8), 12.2884(16) Å, b = 22.1352(16), 22.024(3) Å, and c = 4.6012(3), 4.6187(6) Å, respectively. Their anionic structures can be viewed as infinite ribbons based on corner-shared tetrahedrons. Also, Eu9Mn2.87(4)Al1.13Sb9 has the space group Cmca and a = 9.4883(7) Å, b = 23.6895(18) Å, and c = 24.4845(19) Å. The structural relationships between Ca9Mn2.91(4)Al1.09Sb9 and Eu9Mn2.87(4)Al1.13Sb9 are compared and discussed as well. The successful Al3+ substitution provides additional electrons to the compounds to achieve structural stability. Magnetic susceptibility and electrical resistivity measurements, performed on single crystals of Eu9Mn2.87(4)Al1.13Sb9, indicate complex magnetic properties and semiconductor behavior. The physical properties of Yb9Mn3.59(6)Al0.41Sb9 are similar to those observed for Yb9Mn4.18(2)Sb9.

Noble-metal-free tungsten oxide/carbon (WOx/C) hybrid manowires for highly efficient hydrogen evolution.

Developing active, stable, and low-cost electrocatalysts to generate hydrogen is a great challenge in the fields of chemistry and energy. Nonprecious metal catalysts comprised of inexpensive and earth-abundant transition metals are regarded as a promising substitute for noble metal catalysts used in hydrogen evolution reaction (HER), but are still practically unfeasible mainly due to unsatisfactory activity and durability. Here we report a facile two-step preparation method for WOx nanowires with high concentration of oxygen vacancies (OVs) via calcination of W-polydopamine compound precursors. The resulting hybrid material possesses a uniform and ultralong 1D nanowires structure and a rough and raised surface, which can effectively improve the specific surface area. The products exhibit excellent performance for H2 generation: the required overpotentials for 1 and 10 mA cm-2 are 18 and 108 mV, the Tafel slope is 46 mV/decade, and the electrochemically active surface area is estimated to be ∼77.0 m2 g-1. After 1000 cycles, the catalyst works well without significant current density drop. Our experimental results verified metallic transition metal oxides as superior non-Pt electrocatalysts for practical hydrogen evolution reactions.

Thermoelectric properties of Bi1-xSnxCuSeO solid solutions.

We report the enhanced thermoelectric properties of p-type BiCuSeO by tin doping on bismuth sites. Powder X-ray diffraction analysis and Hall measurements indicated effective tin doping in all samples. We found that the doping efficiency of Sn is lower than expected, as seen from the measured carrier concentration. First-principles calculations indicate that the Sn lone pair modifies the band structure at the Fermi level, with the consequent effect observed in the electrical transport and Seebeck coefficient measurements. An enhanced thermoelectric power factor of ∼2.5 µW cm-1 K-2 was reached at 773 K. No significant effect of Sn doping on the thermal conductivity was found; a thermoelectric figure of merit value (ZT) of 0.3 at 773 K is achieved for Bi0.9Sn0.1CuSeO, which is more than twice that of the pristine BiCuSeO.

Sr14Sn3As12 and Eu14Sn3As12: enantiomorph-like Zintl compounds.

Two new chiral Zintl compounds, Sr14Sn3As12 and Eu14Sn3As12, were synthesized from tin-flux reactions, and the structures were determined by using single-crystal X-ray diffraction. Both compounds crystallize in the trigonal space group R3 (No. 146, Z = 3) with the anion structures containing various units: dumbbell-shaped [Sn2As6](12-) dimers, [SnAs3](7-) triangular pyramids, and isolated As(3-) anions. Very interestingly, these two compounds exhibit opposite chirality in the observed crystal structures, resembling enantiomorphs. Detailed structure analyses suggest possible steric effects among the anion clusters, and on the basis of the calculated electronic structures, substantial electron lone pairs exist on the anions of both compounds, which may provide a hint to understanding the origination of chirality in these intermetallic compounds.

iPSC-MSCs Combined with Low-Dose Rapamycin Induced Islet Allograft Tolerance Through Suppressing Th1 and Enhancing Regulatory T-Cell Differentiation.

Mesenchymal stem cell (MSC) differentiation is dramatically reduced after long-term in vitro culture, which limits their application. MSCs derived from induced pluripotent stem cells (iPSCs-MSCs) represent a novel source of MSCs. In this study, we investigated the therapeutic effect of iPSC-MSCs on diabetic mice. Streptozocin-induced diabetic mice transplanted with 400 islets alone or with 1×10(6) iPSC-MSCs were examined following rapamycin injection (0.1 mg/kg/day, i.p., from days 0 to 9) after transplantation. Our results showed that iPSC-MSCs combined with rapamycin significantly prolonged islet allograft survival in the diabetic mice; 50% of recipients exhibited long-term survival (>100 days). Histopathological analysis revealed that iPSC-MSCs combined with rapamycin preserved the graft effectively, inhibited inflammatory cell infiltration, and resulted in substantial release of insulin. Flow cytometry results showed that the proportion of CD4(+) and CD8(+) T cells was significantly reduced, and the number of T regulatory cells increased in the spleen and lymph nodes in the iPSC-MSCs combined with the rapamycin group compared with the rapamycin-alone group. Production of the Th1 proinflammatory cytokines interleukin-2 (IL-2) and interferon-γ was reduced, and secretion of the anti-inflammatory cytokines IL-10 and transforming growth factor-ß was enhanced compared with the rapamycin group, as determined using enzyme-linked immunosorbent assays. Transwell separation significantly weakened the immunosuppressive effects of iPSC-MSCs on the proliferation of Con A-treated splenic T cells, which indicated that the combined treatment exerted immunosuppressive effects through cell-cell contact and regulation of cytokine production. Taken together, these findings highlight the potential application of iPSC-MSCs in islet transplantation.

MiR-152 regulates metastases of non-small cell lung cancer cells by targeting neuropilin-1.

MicroRNAs (miRNAs) are a class of small non-coding RNAs that have been suggested to play critical roles in tumorigenesis. Recently, miR-152 was reported to be dysregulated in some human cancers. However, the function and mechanism of miR-152 in non-small cell lung cancer (NSCLC) is still unclear. In the present study, our findings showed that the expression of miR-152 was significantly down-regulated and neuropilin-1 was up-regulated in the NSCLC specimens. Moreover, the levels of miR-152 and neuropilin-1 were inversely correlated. Bioinformatics analyses and luciferase reporter assay showed that miR-152 targeted the 3'-UTR of neuropilin-1 mRNA to inhibit its translation. Furthermore, overexpression of miR-152 inhibited neuropilin-1 mediated cell invasiveness, while down-regulated expression of miR-152 increased neuropilin-1 mediated cell invasiveness in NSCLC cells. Together, these findings indicated that miR-152 suppression in NSCLC cells might promote neuropilin-1 mediated cancer metastasis and suggested a new therapeutic application of miR-152 in the treatment of NSCLC.

Structural variability versus structural flexibility. A case study of Eu9Cd4+xSb9 and Ca9Mn4+xSb9 (x ≈ (1)/2).

The focus of this article is on the synthesis and structural characterization of the new ternary antimonides Eu(9)Cd(4+x)Sb(9) and Ca(9)Mn(4+x)Sb(9) (x ≈ (1)/2). Although these compounds have analogous chemical makeup and formulas, which may suggest isotypism, they actually belong to two different structure types. Eu(9)Cd(4.45(1))Sb(9) is isostructural with the previously reported Eu(9)Zn(4.5)Sb(9) (Pbam), and its structure has unit cell parameters a = 12.9178(11) Å, b = 23.025(2) Å, and c = 4.7767(4) Å. Ca(9)Mn(4.41(1))Sb(9) crystallizes in the orthorhombic space group Pnma with unit cell dimensions a = 12.490(2) Å, b = 4.6292(8) Å, and c = 44.197(8) Å and constitutes a new structure type. The two structures are compared and contrasted, and the structural relationships are discussed. Exploratory work aimed at the arsenic-based analogues of either type led to the identification of Ca(9)Zn(4.46(1))As(9), forming with the latter structure [a = 11.855(2) Å, b = 4.2747(8) Å, and c = 41.440(8) Å]. Differential thermal analysis and electrical resistivity measurements, performed on single crystals of Ca(9)Zn(4+x)As(9), indicate high thermal stability and semiconducting behavior. Magnetic susceptibility measurements on Eu(9)Cd(4+x)Sb(9) samples confirm the expected Eu(2+) ([Xe]4f(7)) ground state.

Synthesis, structure and bonding, optical properties of Ba4MTrQ6 (M=Cu, Ag; Tr=Ga, In; Q=S, Se).

Four new quaternary chalcogenides, Ba4AgGaS6 (1), Ba4AgGaSe6 (2), Ba4CuInS6 (3), and Ba4AgInS6 (4), were synthesized by solid-state reactions and their structures were characterized through single-crystal X-ray diffraction. In spite of their similar chemical compositions, the flexible arrangement between the transition metals and the triel atoms leads to subtle differences in their polyanion structures. All structures feature similar [MTrQ6](8-) 1D polyanionic chains (M=Cu, Ag; Tr=Ga, In; Q=S, Se), which are constructed from corner-sharing MQ4 or TrQ4 tetrahedra. However, the transition metals and triels are mixed in 1, 2, and 3, but they occupy independent crystallographic sites in 4. As a result, compounds 1-3 belong to the known Ba2CoS3 (Pnma No. 62) or Ba2 MnS3 (Pnma No. 62) class, whereas 4 crystallizes in its own structural type within the monoclinic P21/c (No. 14) space group. The structural relationship among these new phases was also studied with the aid of DFT calculations and related optical properties are presented as well.