High-Pressure-Induced Phase Transition in 2,5-Diketopiperazine: The Anisotropic Compression of N–H···O Hydrogen-Bonded Tapes

2,5-Diketopiperazine was found to undergo a high-pressure phase transition at about 11.0 GPa through in situ high-pressure synchrotron X-ray diffraction experiments. The anisotropic compression of the samples before the phase transition was discussed. The subsequent results of in situ high-pressure Raman scattering experiments illustrated that the wrinkle of the N–H···O hydrogen-bonded tapes was the major mechanism that drove this phase transition. The first-principle calculations and Hirshfeld surfaces further confirmed that the anisotropic compression of N–H···O hydrogen-bonded tapes was derived from the reduction of molecular interlayer spacing. This study demonstrated the evolutions of low-dimensional intermolecular interactions under continuous compression, which would help to understand the self-assembly of supramolecular materials

High-Pressure-Induced Planarity of the Molecular Arrangement in Maleic Anhydride

Maleic anhydride, an industrially important chemical, was investigated by conducting in situ high-pressure Raman scattering and synchrotron angle-dispersive X-ray diffraction (ADXRD) experiments at a pressure of up to 1.0 GPa. Drastic discontinuities of Raman modes at 0.5 GPa indicated that a phase transition occurred when pressure was elevated. This transformation is further discussed by analysis of the ADXRD results. The Raman spectra and X-ray diffraction patterns of the recovered samples indicated that this pressure-induced transformation is reversible. The calculated results by the first-principle method indicated that the pressure-induced planarity of molecular arrangement is the mechanism of this transition. This study shows that the pressure-induced phase transition of maleic anhydride at 0.5 GPa is derived from supramolecular rearrangements

Pressure-Induced Emission Enhancement of Carbazole: The Restriction of Intramolecular Vibration

Pressure-induced emission enhancement (PIEE), a novel phenomenon in the enhancement of the solid-state emission efficiency of fluorophores, has been arousing wide attention in recent years. However, research on PIEE is still in the early stage. To further pursue more enhanced efficiency, discovering and designing more PIEE systems would be urgently desirable and of great importance. In this Letter, we found that carbazole presented a conspicuous emission enhancement under high pressure up to 1.0 GPa. In situ high-pressure infrared spectroscopy and angle-dispersive X-ray diffraction analysis combined with Hirshfeld surface theory calculation indicated that the PIEE of carbazole was attributed to the decrease of the nonradiation vibration process. This phenomenon mainly resulted from restriction of the N–H stretching vibration by increased N–H···π interactions under high pressure. Our study puts forward a mechanism of PIEE related to the restriction of intramolecular vibration, which provided deep insight into the essential role of intermolecular interaction in fluorescence emission properties

<i>Gauche</i>–<i>trans</i> Conformational Equilibrium of Succinonitrile under High Pressure

Organic chain molecules have considerable importance because of their conformational stability, which is fundamental to their chemical stability. The phase behaviors and conformational equilibrium of simple hydrocarbons and their derivatives under extreme conditions are of interest to research because of their applications. In situ high-pressure Raman spectroscopy studies on succinonitrile up to 24 GPa at ambient temperature have been conducted to investigate its structural properties and conformational equilibria. Succinonitrile has undergone a plastic-to-crystal phase transition around 0.7 GPa. A simultaneous conversion of <i>gauche</i> to <i>trans</i> conformation has been observed. A crystal-to-crystal phase transition has subsequently occurred around 2.9 GPa. The second high-pressure phase has remained stable up to 24 GPa. These two crystal structural transitions have also been confirmed by in situ high-pressure angle-dispersive X-ray diffraction experiments. Compared with the reported low-temperature phase, the new phases under high pressure have different molecular conformations and higher densities, which can provide better understanding of the paths of conformational transitions under different extreme conditions

Pressure Tuning Dual Fluorescence of 4‑(<i>N</i>,<i>N</i>‑Dimethylamino)benzonitrile

The intramolecular charge-transfer (ICT) emission band in the dual fluorescence of the 4-(<i>N</i>,<i>N</i>-dimethylamino)­benzonitrile (DMABN) molecular crystal exhibits increase in response to compression up to 10 GPa. On the basis of Raman and angle-dispersive X-ray diffraction (ADXRD) experiments combining with computational studies, the mechanism of this phenomenon could be assigned to the change of the intramolecular geometrical conformation, especially for the decrease of the dihedral angle between the dimethylamino (NMe₂) and phenyl moieties. Meanwhile the reduction of excited-state energies and the HOMO–LUMO band gap leads to the redshifts of photoluminescence (PL) spectra and the absorption edge, respectively. Competing with the aggregation caused quenching (ACQ) effect, the planarity of molecular conformation and the slight rotation of the NMe₂ group under high pressure both could enhance the ICT process, which will contribute to the revelation of the ICT mechanism and designs of new piezochromic luminescent materials

Genetic Polymorphism of Angiotensin Converting Enzyme and Risk of Coronary Restenosis after Percutaneous Transluminal Coronary Angioplasties: Evidence from 33 Cohort Studies

<div><p>Background</p><p>In the past decade, a number of cohort studies studies have been carried out to investigate the relationship between the insertion/deletion polymorphism of the gene encoding angiotensin-converting enzyme and risk of restenosis after percutaneous transluminal coronary angioplasties in patients. However, these studies have yielded contradictory results. Genetic association studies addressing this issue are frequently hampered by insufficient power. We therefore performed a meta-analysis of the published studies to clarify this inconsistency and to establish a comprehensive picture of the relationship between ACE I/D polymorphism and post-PTCA restenosis risk.</p><p>Methods</p><p>Databases including Pubmed, EMBASE, ISI Web of Science, EBSCO, Cochrane Library databases and CNKI were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. The random-effects model was applied, addressing heterogeneity and publication bias.</p><p>Results</p><p>A total of 33 cohort studies involving 11,099 subjects were included. In a combined analysis, the OR for post-PTCA restenosis of the ACE DD genotype was 1.61 (95% CI: 1.27–2.04; <i>P</i><10⁻⁵). In the subgroup analysis by intervention, significantly increased risks were also found in PTCA-stent and PTCA-balloon for the DD genotype of the polymorphism.</p><p>Conclusions</p><p>Our meta-analysis showed that the DD genotype of ACE I/D polymorphism was significantly associated with increased risk of restenosis, particularly for PTCA-stent.</p></div

Results of meta-analysis for ACE I/D polymorphism and restenosis risk.

<p>Results of meta-analysis for ACE I/D polymorphism and restenosis risk.</p

Study selection process.

<p>Study selection process.</p

Forest plot for association between DD homozygous of ACE I/D polymorphism and coronary restenosis risk.

<p>Forest plot for association between DD homozygous of ACE I/D polymorphism and coronary restenosis risk.</p

Additional file 1 of Real-world performance of indobufen versus aspirin after percutaneous coronary intervention: insights from the ASPIRATION registry

Additional file 1: Supplemental Methods. Table S1. Comparison of baseline characteristics according to the status of follow-up. Figure S1. Temporal trend of indobufen use. Figure S2. Manifestations of aspirin intolerance. Figure S3. Comparison of ASD before and after matching. Figure S4. Distributions of propensity scores before and after matching. Figure S5. Sensitivity analysis. Figure S6. Reasons for unplanned drug discontinuation. STROBE Checklist