Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

Ultrafast nonlinear optical properties and excited-state dynamics of Soret-band excited D-π-D porphyrins

Herein, we report results from our studies on the ultrafast nonlinear optical (NLO) properties and excited-state dynamics in three different porphyrin molecules designed in D-π-D fashion (phenothiazine-porphyrin-phenothiazine) and with two different central metal ions [Zn(II) and Cu(II)]. We have performed extensive target analysis of the femtosecond transient absorption data obtained conveying the true exited state/species spectra of each process with respective lifetimes along with microscopic rate constants of each excited state. The obtained life time values were in the range of 250–500 fs, 20–142 ps, 1.5–6.2 ns and 0.1–1.23 μs and have been associated from relaxation with the Sn, Hot S1 (to S1), S1, and T1 states. Furthermore, the third-order nonlinear (NLO) coefficients [two-photon absorption (TPA) and nonlinear refractive index (n2)] of CPPHT and ZPPHT exhibited superior values compared to HPPHT recorded with ~50 fs, 1 kHz repetition rate pulses at a wavelength of 800 nm. The magnitude of the TPA coefficients of these molecules was compared with some of the recently reported porphyrin moieties and were found to be superior. The time-resolved degenerate four-wave mixing (DFWM) measurements confirmed a large magnitude and an ultrafast response of the χ(3) in these molecules suggesting potential photonic and all-optical switching applications

Comparative photophysical and femtosecond third-order nonlinear optical properties of novel imidazole substituted metal phthalocyanines

Two novel phenanthro [9,10-d]imidazole substituted metal phthalocyanines, ImCuPc and ImZnPc, have been synthesized and their potential as photosensitizers has been investigated through optical, electrochemical, and ultrafast nonlinear optical (NLO) studies, including their excited state dynamics. The absorption as well as emission spectra of both the title compounds exhibited negligible Stokes shift in different solvents. The molecules depicted a broad Soret band due to the incorporation of phenanthro[9,10-d]imidazole moiety while the Q-bands were characteristic to their metal phthalocyanine group. DFT studies elucidated the HOMO-LUMO (4.99–2.90 eV) levels of these molecules with their energy optimized structures generated using DFT, TD-DFT analysis. The fs-TAS spectra of both the molecules exhibited contribution from singlet-singlet excited state absorption followed by transition to triplet states via intersystem crossing, ISC. The lifetimes calculated from obtained kinetics at specific wavelengths using global fitting demonstrated slow singlet to triplet state intersystem crossing in ImCuPc (decay rate of 1.6 × 108 s−1) and ImZnPc (decay rate of 1.4 × 108s−1). The ns-TAS studies established long lived triplet states in both the molecules with ImCuPc depicting a slightly higher triplet lifetime of ~1.4 μs over ImZnPc with a triplet lifetime of ~1.2 μs The triplet quantum yields (φT) were calculated to be 0.51 for ImCuPc while it was 0.27 for ImZnPc suggesting ImCuPc to be a better photosensitizer (PS) over ImZnPc. We believe the intramolecular D-π-A interaction is stronger in ImCuPc resulting in higher triplet yield. Third-order NLO studies performed at a non-resonant excitation of 800 nm (~50 fs, 1 kHz pulses) demonstrated ImZnPc had a larger two-photon absorption cross-section (994 GM), possibly due to heavy atom effect, while ImCuPc was found to possess superior n2 (3.7 × 10−15 cm2/W). The slightly superior nonlinear optical (NLO) performance of ImCuPc over ImZnPc could also possibly be due to lower energy gap and Copper's open 3d shells as opposed to full 3d shell in Zinc which overlaps with Pc 2p shells making it more active

Influence of Si3N4 on the Dry Sliding Wear Characteristics of Stir-Cast Cu-10Sn/xSi3N4 Metal Matrix Composite for Bearing Applications

Bronze metal matrix composites (MMCs) are futuristic materials that may find applications in automobile, aviation, and marine industries, specifically for propellers in submarines, bearings, and bushings for defence purposes. The present investigation studied the effect of Si3N4 (5, 10, 15 wt%) ceramic particles on the physical, metallurgical, and tribological behaviour of Cu-10Sn/Si3N4 MMCs. Cast rods of three composites and a base alloy were fabricated using the liquid metallurgy route. The microstructural characterisation for the cast samples was conducted using FESEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), XRD (X-ray diffraction), and TEM (Transmission Electron Microscope), which revealed that the Cu-10Sn alloy reinforced with 5 wt% of Si3N4 had homogeneous distribution and perfect bonding of the Si3N4 with the bronze MMC. The dry sliding wear test was performed by varying parameters such as the applied load (10, 20, 30 N) and sliding velocity (1, 2, 3 m/s). The specific wear rate (SWR) increased against an increased load. However, the SWR and coefficient of friction decreased and then increased against an increasing sliding velocity due to tribolayer formation. The primary wear mechanism observed at low and high loads was severe delamination. In contrast, the wear mechanism was adhesion wear at high and low velocities. Amongst the researched samples, Cu-10Sn/5 wt% Si3N4 composites revealed the least SWR at a load of 10 N and sliding velocity of 2 m/s and hence can be recommended for manufacturing bearings and bushings in the automobile and defence industry

Influence of Si₃N₄ on the Dry Sliding Wear Characteristics of Stir-Cast Cu-10Sn/xSi₃N₄ Metal Matrix Composite for Bearing Applications

Bronze metal matrix composites (MMCs) are futuristic materials that may find applications in automobile, aviation, and marine industries, specifically for propellers in submarines, bearings, and bushings for defence purposes. The present investigation studied the effect of Si3N4 (5, 10, 15 wt%) ceramic particles on the physical, metallurgical, and tribological behaviour of Cu-10Sn/Si3N4 MMCs. Cast rods of three composites and a base alloy were fabricated using the liquid metallurgy route. The microstructural characterisation for the cast samples was conducted using FESEM (Field Emission Scanning Electron Microscope), EDS (Energy Dispersive Spectroscopy), XRD (X-ray diffraction), and TEM (Transmission Electron Microscope), which revealed that the Cu-10Sn alloy reinforced with 5 wt% of Si3N4 had homogeneous distribution and perfect bonding of the Si3N4 with the bronze MMC. The dry sliding wear test was performed by varying parameters such as the applied load (10, 20, 30 N) and sliding velocity (1, 2, 3 m/s). The specific wear rate (SWR) increased against an increased load. However, the SWR and coefficient of friction decreased and then increased against an increasing sliding velocity due to tribolayer formation. The primary wear mechanism observed at low and high loads was severe delamination. In contrast, the wear mechanism was adhesion wear at high and low velocities. Amongst the researched samples, Cu-10Sn/5 wt% Si3N4 composites revealed the least SWR at a load of 10 N and sliding velocity of 2 m/s and hence can be recommended for manufacturing bearings and bushings in the automobile and defence industry

Solution processable deep-red phosphorescent Pt(II) complex: direct conversion from its Pt(IV) species via a base promoted reduction

Color purity is a critical prerequisite for full color displays. Creation of deep-red phosphorescent materials with high PLQYs is particularly challenging because of “energy gap law”. Simultaneously achieving high yielding solution-processable Pt(II) complexes further complicates this challenge. In this report, we developed a high-yielding synthetic route to a solution processable/deep-red Pt(II) complex with a rigid tetradentate structure, in which we identified octahedral Pt(IV) as a major side product formed under the standard complexation conditions. We managed to effectively transform the octahedral Pt(IV) into a luminescent deep-red square planar Pt(II) complex through a base promoted reduction. We found the Pt(II) complex has high solution and blend film PLQYs. X-ray crystal structure and DFT calculations of the Pt(II) complex showed that perpendicular orientation of molecular dipoles enhanced the luminescence properties. In neat films, there was no luminescence enhancement due to interdigitation of the attached hexyloxy tails, preventing strong Pt∙∙∙Pt interactions in the solid state. Solution processed OLEDs based on the Pt(II) complex showed a low turn-on voltage of 3.3 V (at 1 cd/m2) with a maximum brightness of 2,000 cd/m2 and a maximum EQE of ≈6% (4% at 100 cd/m2). A narrow electroluminescence with a full-width-at-half-maximum of ≈50 nm was observed with a peak at 623 nm, and provided a deep-red emission with 1931 CIE co-ordinates of (0.65, 0.35). Transient electroluminescence measurements were used to investigate the EQE roll-off of the OLEDs