In situ studies of a platform for metastable inorganic crystal growth and materials discovery

Rapid shifts in the energy, technological, and environmental demands of materials science call for focused and efficient expansion of the library of functional inorganic compounds. To achieve the requisite efficiency, we need a materials discovery and optimization paradigm that can rapidly reveal all possible compounds for a given reaction and composition space. Here we provide such a paradigm via in situ X-ray diffraction measurements spanning solid, liquid flux, and recrystallization processes. We identify four new ternary sulfides from reactive salt fluxes in a matter of hours, simultaneously revealing routes for ex situ synthesis and crystal growth. Changing the flux chemistry, here accomplished by increasing sulfur content, permits comparison of the allowable crystalline building blocks in each reaction space. The speed and structural information inherent to this method of in situ synthesis provide an experimental complement to computational efforts to predict new compounds and uncover routes to targeted materials by design.Discovering new materials is a crucial step to address large-scale problems of energy conversion, storage, and transmission and other technological needs whether seeking bulk phases or thin films. Dense inorganic materials are desired for their tunable transport, magnetism, optical absorption, and stability, but their existence in general cannot be predicted with the near certainty of that of metastable organic and organometallic compounds. Whereas the desire to efficiently locate and assemble inorganic materials is great, it is hindered by traditional solid-state synthetic methods—at high temperatures often only the energy-minimum thermodynamic product is obtained. To strive toward an arena where metastable compounds can be discovered rapidly and made systematically, here we conduct reactions within liquid fluxes and use in situ monitoring to capture signatures of new phases, even when they quickly dissolve in the melt.Convective liquid fluxes (salts, metals, or oxides) can serve as reaction media that aid diffusion and enable rapid formation of compounds at temperatures far below their melting points (1–6). The flux can be nonreactive or reactive; in the latter case the flux itself becomes incorporated into the product (7, 8). This well-established approach has demonstrated the prolific discovery of novel inorganic materials grown out of low-melting fluxes, from oxides and other chalcogenides (9–12), to pnictides (13, 14), to intermetallics (15), many of which cannot be attained by direct combinations of the elements. Despite the variety of metastable phases formed in these reactions, the classical approach is to predetermine a given set of reaction conditions (e.g., time, temperature, and heating and cooling rates) and wait for completion to isolate and identify the formed compounds. It is not possible to observe how the reaction system itself has arrived at the isolated compound, whether the crystalline material formed on heating, on cooling, or on soaking at the given high temperature, nor it is possible to know whether any intermediates were present and, if so, their influence on product formation. This lack of awareness (“blind synthesis”) hinders our ability to identify the new materials or to devise successful synthetic processes for desired and targeted materials. If we are to develop a predictive understanding of synthesis and to more quickly discover new materials, we will greatly benefit from the input of much higher levels of detail in how syntheses proceed.We show here that in situ synchrotron X-ray diffraction maps of metastable inorganic compound formation in inorganic fluxes reveal complex real-time phase relationships and permit rapid access to new inorganic materials that would be missed using classical approaches. Specifically, we have discovered heretofore unknown phases in systems with simple elemental compositions of Cu and Sn with molten polysulfide salts K₂S₃ and K₂S₅ (melting points 302 °C and 206 °C, respectively) as paradigmatic representatives. Complex copper sulfides have been identified as possible earth-abundant photovoltaics (16) and are a source of exotic charge-density-wave materials, whereas tin chalcogenides form the basis for Cu₂ZnSnS₄ (CZTS) semiconductors (17) and exhibit ion exchange properties useful for heavy metal waste capture (18). We observe a complex phase space: In all but one of our reactions we observe additional crystalline phases in situ that are not present by the end of the reaction (as would be recovered ex situ). Both families of ternary compounds can exhibit a variety of coordinations by sulfur, and the range of properties is accordingly large: In just one of our Cu-containing reactions we found a previously undiscovered 1D metal (K₃Cu₄S₄) similar to heavy-metal capture materials and observed a different 2D metal (K₃Cu₈S₆) and a layered semiconductor (KCu₃S₂).Our approach can be combined with previous work that probes the formation and stabilization of inorganic materials from liquid media, using structural and spectroscopic data (19, 20). Within a given reaction, we can use temperature as a variable to probe the relationships among phases with the goal of understanding how the structures may be constructed from similar building units. Additionally, in situ studies of crystallization have been shown to be effective at probing the kinetics of oxide and sulfide formation, typically from aqueous solutions (21–23).The in situ technique we describe here provides rapid diffraction signatures of all crystalline phases formed during processing, including metastable intermediates. Reactions are performed in under 2 h (compared with typical flux reactions on the order of days), but time resolution of the data can be on the order of seconds. This is a route to efficient exploration of composition–temperature spaces that might be predicted to house novel compounds with favorable properties by first-principles (24) or data-mining calculations (25). Because new structure types cannot be easily predicted by computational theory, the approach described here is a necessary experimental tool in now-budding efforts to understand, validate, and expand the materials genome.A schematic of the in situ capillary furnace used to investigate phase formation during flux reactions is shown in Fig. 1A. The sample tubes, 0.7 mm in diameter, were sealed under vacuum, heated using a resistive coil, and continuously rastered through the synchrotron X-ray beam to maintain uninterrupted X-ray exposure of the sample as it melted and flowed within the tube.Open in a separate windowFig. 1.Schematic of in situ X-ray diffraction experiment and data analysis. (A) The in situ setup for collecting X-ray diffraction data from melting polysulfide fluxes. The sample tube diameter is 0.7 mm. Two-dimensional patterns are integrated and the 1D data can be fitted using Rietveld refinements to give individual contributions to the diffraction patterns in B. Upon heating, diffraction data are collected continuously, giving the set of patterns in C. These data are divided into regions with distinct phase contributions. A single pattern from each region is shown in D–F, with contributions to each pattern identified.For each reaction, the accompanying series of raw diffraction patterns provide a real-time monitor of the reaction progress and, to a first approximation, the number of phase formation and dissolution events. The X-ray diffraction pattern from a combination of Cu and K₂S₃ before heating is shown in Fig. 1B and fitted with a Rietveld refinement that confirms the contributions from both reagents. The diffraction patterns collected continuously while heating and cooling this reaction mixture are shown in Fig. 1C. Wholesale changes in the diffraction patterns indicate that the reaction pathway proceeded in a series of steps (color coded in Fig. 1C). First, signatures of the reagent metal and polysulfide appeared (blue region), which all resemble the refined pattern in Fig. 1B. Upon heating, low-Q peaks appeared in the diffraction data (red region). This real-time information (before any analysis) revealed that more complex ternary K–Cu–S phases were forming.Continued heating led to the disappearance of all Bragg peaks (gray region in Fig. 1C). At this point the ternary sulfides dissolved completely into the molten polysulfide salt flux. After cooling, low-Q peaks again signified the presence of ternary phases (violet region in Fig. 1C). Random variations in peak heights in adjacent patterns provided a morphological clue: The product on cooling formed as large sulfide crystals, leading to sharp diffraction spots rather than powder-averaged rings.Systematic least-squares refinements account for all crystalline phases present. Phase transformations and amorphous regions (defined by the absence of Bragg peaks) can also be observed in real time by visual inspection. Representative diffraction patterns and their least-squares refinements from each of the four temperature regimes in Fig. 1C are shown in Fig. 1 D–F. Data in Fig. 1D were taken at 320 °C upon heating and the reaction contained two ternary phases: KCu₃S₂ and the previously unknown phase K₃Cu₄S₄.At the time of the experiment, contributions to the diffraction pattern that do not match known compounds are considered unknown phases to be solved. Three options to identify new phases are as follows:

• i)Deduce structure by chemical analogy to known compounds. This can be accomplished manually or aided by computational tools such as the “Structure Predictor” of the Materials Project (26, 27).
• ii)Grow larger single crystals of compounds that crystallize out of a melt. In the present case, elemental analysis and single-crystal diffraction were used in this study to identify K₄Sn₂S₆ from crystals grown ex situ based on information provided by the in situ experiments.
• iii)Solve structure from powder diffraction, using computational packages such as FOX (28).

In the case of the experiment with data shown in Fig. 1D, the unknown phase K₃Cu₄S₄ was identified by option i: comparison of the isostructural phase Na₃Cu₄S₄.The diffraction pattern at 600 °C in Fig. 1E, taken from the gray region in Fig. 1B, has no Bragg peaks and represents the amorphous polysulfide melt after dissolution of KCu₃S₂ and K₃Cu₄S₄. A diffraction pattern from cooling at 50 °C is shown in Fig. 1F to contain the 2D metallic compound K₃Cu₈S₆ and the recrystallized flux K₂S₃. Because K₃Cu₈S₆ grew as large crystals, not a powder, Le Bail full-profile fitting (disregarding peak heights but refining peak profiles and peak locations constrained by unit cell symmetry) is shown in Fig. 1F to account for all peak contributions rather than the Rietveld method (29).The last step in diffraction analysis is to refine every powder pattern sequentially. Using the four diffraction patterns in Fig. 1 D–F and their refined phase contributions as anchors, we performed automated least-squares refinements to the ∼200 diffraction patterns to record the reaction progression as a function of time and temperature and form a “reaction map.” In this manner we identified phase fractions and points of crystallization, melting, and dissolution of all crystalline phases present during in situ reactions of Cu and Sn in fluxes of K₂S₃ and K₂S₅. The resulting panoramic reaction maps are shown in Fig. 2 and discussed subsequently.Open in a separate windowFig. 2.Reaction maps obtained from sequential refinements to in situ diffraction data. (A) Reactions of Cu + K₂S₃ lead to formation of KCu₃S₂ and the new phase K₃Cu₄S₄ on heating. These dissolve into the melt upon heating, and K₃Cu₈S₆ crystallizes upon cooling. A similar phase progression occurs for Cu + 5K₂S₃ (B), with KCu₃S₂ also forming on cooling. Reactions of Cu + K₂S₅ (C) and Cu + 5K₂S₅ (D) produce the layered phase KCu₄S₃. Reactions of Sn + K₂S₃ (E) produce SnS and the new phase K₆Sn₂S₇ on heating. No ternary phases are observed for Sn + 5K₂S₃ (F). The lowest-melting reaction Sn + K₂S₅ (G) reveals formation of the new phase K₅Sn₂S₈ from a melt upon heating. K₄Sn₂S₆ and K₂Sn₂S₅ crystallize concurrently upon cooling. For Sn + 5K₂S₅ (H), the progression is similar but K₂Sn₂S₅ is absent.     

癌症患者同伴支持量表的汉化及信效度检验

目的 汉化癌症患者同伴支持量表,并检验其信效度。方法 通过正译、回译、文化调试和预调查对原量表进行汉化,形成中文版癌症患者同伴支持量表。于2021年3月—6月选取长沙市2所三级甲等医院的128例青年癌症患者进行问卷调查,分析量表的信效度;2021年7月—2022年3月选取该2所医院招募的241例患者进行问卷调查,用于验证性因子分析。结果 中文版癌症患者同伴支持量表包括3个维度、11个条目。量表水平的内容效度指数为0.948,条目水平的内容效度指数为0.714～1.000。探索性因子分析提取出3个公因子,各条目因子载荷为0.535～0.872,累计方差贡献率为69.64%,方程拟合良好。量表总的Cronbach’s α系数为0.923,折半信度为0.860。验证性因子分析结果 显示,模型拟合度良好。结论 中文版癌症患者同伴支持量表的信效度良好,适用于青年癌症患者同伴支持感的评估。     

Synthesis,Characterization, and Biological Evaluation of 99mTc(CO)3‐Labeled Peptides for Potential Use as Tumor Targeted Radiopharmaceuticals

During the past decade, several peptides containing Arg‐Gly‐Asp sequence have been conjugated with different chelating agents for labeling with various radionuclides for the diagnosis of tumor development. In this study, we report the synthesis of two tetrapeptides (Asp‐Gly‐Arg‐His and Asp‐Gly‐Arg‐Cys) and one hexapeptide [Asp‐Gly‐Arg‐D‐Tyr‐Lys‐His] by changing the amino acid sequence of the Arg‐Gly‐Asp motif. Peptide synthesis was initiated from aspartic acid. Aspartic acid placed at C‐terminal end of the peptide chain can be conjugated with different drug molecules facilitating their transport to the site of action. The peptides were synthesized in excellent yield and labeled using freshly prepared [^99mTc(CO)₃(H₂O)₃]⁺ intermediate. A complexation yield of over 97% was achieved under mild conditions even at low ligand concentrations of 10^?2 m . Radiolabeled peptides were characterized by HPLC and were found to be substantially stable in saline, in His solution as well as in rat serum and tissue (kidney, liver) homogenates. Internalization studies using Ehrlich ascites carcinoma cell line showed rapid and significant internalization (30–35% at 30 min of incubation attaining maximum value of about 40–60% after 2–4 h incubation). A good percentage of quick internalization was also observed in α_vβ₃‐receptor‐positive B16F10 mouse melanoma cell line (14–16% after 30 min of incubation and 25–30% after 2–4 h incubation). Imaging and biodistribution studies were performed in Swiss albino mice bearing Ehrlich ascites tumor in right thigh. Radiolabeled peptides exhibited fast blood clearance and rapid elimination through the urinary systems. ^99mTc(CO)₃‐tetra‐Pep2 exhibited remarkable localization at tumor site (1.15%, 1.17%, and 1.37% ID/g at 2, 4, and 6 h p.i., respectively) which could be due to slow clearance of the radiolabeled peptide from blood in comparison with the other two radiolabeled peptides. However, ^99mTc(CO)₃‐hexa‐Pep exhibited the highest tumor to muscle and tumor to blood ratios among the three. The preliminary results with these amino acid–based peptides are encouraging enough to carry out further experiments for targeting tumor.     

CCR9 signaling in dendritic cells drives the differentiation of Foxp3+ Tregs and suppresses the allergic IgE response in the gut

The chemokine receptor CCR9 and its only known ligand CCL25 play an important role in gut inflammation and autoimmune colitis. The function of CCR9-CCL25 in the migration of immune cells is well characterized. However, its role in the immune cell differentiation is mostly not known. Using dextran sodium sulfate (DSS)-induced gut inflammation model, we showed that CCR9⁺ dendritic cells (DCs) specifically CD11b⁻CD103⁺ DCs were significantly increased in the gut-associated lymphoid tissues (GALT) compared to control mice. These CCR9⁺ DCs express lower MHC II and CD86 molecules and had regulatory surface markers (FasL and latency-associated peptide, LAP) in the GALT. In the presence of CCL25, CCR9⁺ DCs promoted in vitro differentiation of Foxp3⁺ regulatory CD4⁺ T cells (Tregs). CCL25-induced differentiation of Tregs was due to intrinsic signaling in the DCs but not through CD4⁺ T cells, which was driven by the production of thymic stromal lymphopoietin (TSLP) and not IL-10. Furthermore, adoptive transfer of CCR9⁺ DCs in C57BL/6 mice promoted Tregs but reduced the Th17 cells in the GALT, and also suppressed the OVA-specific gut-allergic response. Our results suggest CCR9⁺ DCs have a regulatory function and may provide a new cellular therapeutic strategy to control gut inflammation and allergic immune reaction.     

The effect of mutation in the stem of the MicroROSE thermometer on its thermosensing ability: insights from molecular dynamics simulation studies

A large number of bacteria have been found to govern virulence and heat shock responses using temperature sensing RNAs known as RNA thermometers (RNATs). They repress translation initiation by base pairing to the Shine–Dalgarno (SD) sequence at low temperature. Increasing the temperature induces the RNA duplex to unfold and expose the SD sequence for translation. A prime example is the ROSE thermometer module known to regulate the production of the ROSE heat shock protein in Bradyrhizobium japonicum. The unfolding of a 29-nucleotide long MicroROSE RNA element which forms a critical component encompassing the SD sequence, and three mutants that differ from it by deletion of a guanine nucleotide or mutations near the SD and stem regions have been studied using high temperature molecular dynamics simulations. The simulations reveal the progressive manner in which a biologically functional RNA thermometer unfolds. Our simulations reveal that deletion of the highly conserved G10 residue, opposite to the SD region leads to the formation of a stable RNA helix that has lost its thermosensing ability. Mutations of bases A5 → U5 and U25 → A25 near the stem increase the thermosensing ability due to the allosteric effect which leads to a global destabilization effect on the structure. The temperature-dependant regulation of this thermometer has been investigated by estimation of differences in the unfolding paths by calculating individual residue fluctuation, stacking energy, the contact map plot and the lifetime dynamics plot of non-Watson–Crick hydrogen bonds at three different temperatures. Results reveal that partial unfolding at higher temperature starts from the hairpin tetra loop end and terminates at the stem region through the SD associated region. Two canonical hydrogen bonds between U9–A22 and four non-canonical hydrogen bonds between G10–G21 and U6–U24 around the internal loop play an important role in partial melting of the RNA helix. These results demonstrate how small alterations in RNA structure can regulate gene expression and illuminate the molecular basis of the function of an important bacterial regulatory motif.

Mutation induced thermosensing ability of MicroROSE thermometer.     

三维重建射频损伤区域观察猪舌根射频损伤体积与射频能量及时间的关系

目的：目前临床进行隧道法舌根射频治疗时,其作用参数的设置仍缺乏统一的标准,故通过计算机三维重建射频损伤区域,分析猪舌根射频损伤体积与射频能量、时间的关系,从中得出应用舌根隧道法射频治疗的最佳作用能级和作用时间。 方法：实验于2006-06/2007-05在上海交通大学耳鼻喉科研究所完成。将36只实验用猪以射频作用能级1,2,3,4,5,6随机分成6组,每组6头猪,各个猪舌的作用时间分别设置为2,5,10,15,20,25s。用Coblation射频发生仪及Reflex55刀头进行猪舌根射频操作。射频作用后的舌根组织行连续冰冻切片,苏木精-伊红染色后,进行序列组织切片的全貌二维图像采集,对拟重建的结构进行边界提取和图像分割。将提取分割图像导入Image-Pro Solution图像处理软件,利用3D Constructor插件进行三维重建,并根据设定参数进行体积计算。用SPSS10.0统计学软件对所测数据进行统计学分析。 结果：①作用能级固定时,舌根组织射频损伤体积随时间延长而增大,符合Logarithmic回归曲线。②作用时间固定时,舌根组织射频损伤体积随能级增大而增大,符合直线回归。③射频损伤体积随能量增大而增加亦符合Logarithmic回归曲线。④Coblation射频治疗系统在能级6时,在作用10s之前,损伤体积随作用时间增加而迅速增加,其后变化趋势平缓,超过20s后损伤体积无显著增加。 结论：①舌根区域射频治疗时,舌根组织射频损伤体积与时间或能量呈Logarithmic曲线相关,与能级呈直线相关。②Coblation射频治疗系统在能级6时,最佳作用时间范围为10-20s。     

Education initiative improves the evidence‐based use of metoclopramide following morphine administration in the emergency department

Objective: We aimed to evaluate a multifaceted education initiative designed to reduce the prophylactic use of metoclopramide. Methods: This was a pre‐ and post‐intervention trial undertaken in a single ED. All ED doctors and nurses were targeted. The intervention comprised a specifically designed, 19‐slide ‘e‐learning module’, accessible via the ED intranet, supplemented by in‐service training and a range of reminder techniques (posters, emails and drug room flyers). The primary end‐point was the proportion of patients administered metoclopramide prophylactically with their initial morphine dose. Data were collected on random samples of patients who received morphine, using explicit medical chart review. Results: Both pre‐ and post‐intervention periods were of 3 month duration. The charts of 146 cases were reviewed in each period. In the post‐intervention period: ? The proportion of patients administered metoclopramide prophylactically decreased from 22.6% to 4.1% (difference 18.5% [95% CI 10.3–26.7], P < 0.001) ? The proportion of patients administered metoclopramide appropriately (for known morphine sensitivity, established nausea and rescue anti‐emesis) rose marginally from 28.8% to 32.9% (difference 4.1% [95% CI ?7.2–15.4], P = 0.53) ? There was a 12.7% decrease in the number of ampoules of metoclopramide issued to the ED without a concurrent rise in the issue of other anti‐emetic drugs Conclusion: The education initiative resulted in a significant improvement in the evidence‐based use of metoclopramide.     

Neurohydatidosis

Early and non‐invasive evaluation of hydatid infestation of brain and spine is of paramount importance, especially in endemic areas. We present a spectrum of imaging findings in neurohydatidosis with a brief review of literature.