Ligand-based charge-transfer luminescence in ionic cyclometalated iridium(III) complexes bearing a pyrene-functionalized bipyridine ligand: a joint theoretical and experimental study.

Two new heteroleptic iridium(III) complexes [Ir(ppy)(2)(pyr(2)bpy)][PF(6)] ([1a][PF(6)]) and [Ir(dfppy)(2)(pyr(2)bpy)][PF(6)] ([2a][PF(6)]), where Hppy = 2-phenylpyridine, Hdfppy = 2-(3,5-difluorophenyl)pyridine, and pyr(2)bpy = 5,5'-bis(pyren-1-yl)-2,2'-bipyridine, have been synthesized and fully characterized. The single-crystal structures of pyr(2)bpy and the complexes 4{[1a][PF(6)]}·2CH(2)Cl(2)·9H(2)O and [2a][PF(6)]·0.25CH(2)Cl(2)·H(2)O have been determined. The effect of the pyrene substituents on the electronic properties is investigated through a comprehensive photophysical and theoretical study on the two complexes in comparison to reference complexes without substituents on the ancillary ligand ([1][PF(6)] and [2][PF(6)]) and by making absorption and luminescence titrations of ligand pyr(2)bpy. Both theory and experiment show that the intense and broad band appearing in the 400-500 nm region of the absorption spectra of [1a][PF(6)] and [2a][PF(6)] is due to intramolecular charge-transfer (ICT) transitions from the pyrene substituents to the bipyridine ligand. [1a][PF(6)] and [2a][PF(6)] exhibit luminescence bands centered above 650 nm, attributed to a charge-transfer triplet state located on the pyr(2)bpy ligand, lying at lower energy than the strongly emitting Ir-ppy→bpy triplet states of the complexes lacking the pyrene fragments. Such luminescence, detected both at room temperature and 77 K, shows that the appendage of luminophoric moieties to luminescent Ir-based centers may further widen the emission tuneability of this exploited class of luminescent materials through purely electrostatic effects exerted on a properly designed N^N ancillary ligand.

Physical activity and its correlates in children: a cross-sectional study (the GINIplus & LISAplus studies).

BACKGROUND: Physical inactivity among children is an increasing problem that adversely affects children's health. A better understanding of factors which affect physical activity (PA) will help create effective interventions aimed at raising the activity levels of children. This cross-sectional study examined the associations of PA with individual (biological, social, behavioral, psychological) and environmental (East vs. West Germany, rural vs. urban regions) characteristics in children. METHODS: Information on PA and potential correlates was collected from 1843 girls and 1997 boys using questionnaires during the 10-year follow-up of two prospective birth cohort studies (GINIplus and LISAplus). Study regions represent urban and rural sites as well as East and West of Germany. Logistic regression modeling was applied to examine cross-sectional associations between individual as well as environmental factors and PA levels. RESULTS: Five of fourteen variables were significantly associated with PA. Among children aged 10, girls tended to be less active than boys, especially with respect to vigorous PA (OR = 0.72 for summer). Children who were not a member of a sports club showed a substantially reduced amount of PA in winter (OR = 0.15). Rural environments promote moderate PA, particularly in winter (OR = 1.88), whereas an increased time outdoors primarily promotes moderate PA in summer (OR = 12.41). Children with abnormal emotional symptoms exhibited reduced physical activity, particularly in winter (OR = 0.60). BMI, puberty, parental BMI, parental education, household income, siblings, TV/PC consumption, and method of arriving school, were not associated with PA. CONCLUSIONS: When considering correlates of PA from several domains simultaneously, only few factors (sex, sports club membership, physical environment, time outdoors, and emotional symptoms) appear to be relevant. Although the causality needs to be ascertained in longitudinal studies, variables which cannot be modified should be used to identify risk groups while modifiable variables, such as sports club activities, may be addressed in intervention programs.

MoveApps: a serverless no-code analysis platform for animal tracking data.

BACKGROUND: Bio-logging and animal tracking datasets continuously grow in volume and complexity, documenting animal behaviour and ecology in unprecedented extent and detail, but greatly increasing the challenge of extracting knowledge from the data obtained. A large variety of analysis methods are being developed, many of which in effect are inaccessible to potential users, because they remain unpublished, depend on proprietary software or require significant coding skills. RESULTS: We developed MoveApps, an open analysis platform for animal tracking data, to make sophisticated analytical tools accessible to a global community of movement ecologists and wildlife managers. As part of the Movebank ecosystem, MoveApps allows users to design and share workflows composed of analysis modules (Apps) that access and analyse tracking data. Users browse Apps, build workflows, customise parameters, execute analyses and access results through an intuitive web-based interface. Apps, coded in R or other programming languages, have been developed by the MoveApps team and can be contributed by anyone developing analysis code. They become available to all user of the platform. To allow long-term and cross-system reproducibility, Apps have public source code and are compiled and run in Docker containers that form the basis of a serverless cloud computing system. To support reproducible science and help contributors document and benefit from their efforts, workflows of Apps can be shared, published and archived with DOIs in the Movebank Data Repository. The platform was beta launched in spring 2021 and currently contains 49 Apps that are used by 316 registered users. We illustrate its use through two workflows that (1) provide a daily report on active tag deployments and (2) segment and map migratory movements. CONCLUSIONS: The MoveApps platform is meant to empower the community to supply, exchange and use analysis code in an intuitive environment that allows fast and traceable results and feedback. By bringing together analytical experts developing movement analysis methods and code with those in need of tools to explore, answer questions and inform decisions based on data they collect, we intend to increase the pace of knowledge generation and integration to match the huge growth rate in bio-logging data acquisition.

Use of Convolutional Neural Nets and Transfer Learning for Prediction of Surgical Site Infection from Color Images.

One of the greatest concerns in post-operative care is the infection of the surgical wound. Such infections are a particular concern in global health and low-resource areas, where microbial antibiotic resistance is often common. In order to help address this problem, there is a great interest in developing simple tools for early detection of surgical wounds. Motivated by this need, we describe the development of two Convolutional Neural Net (CNN) models designed to detect an infection in a surgical wound using a color image taken from a mobile device. These models were developed using image data collected from a clinical study with 572 women in Rural Rwanda, who underwent Cesarean section surgery and had photos taken approximately 10 days after surgery. Infected wounds (N=62) were diagnosed by a trained doctor through a physical exam. In our model development, we observed a trade-off between AUC accuracy and sensitivity, and we chose to optimize for sensitivity, to match its use as a screening tool. Our naïve CNN model, with a limited number of convolutions and parameters, achieved median AUC = 0.655, true positive rate sensitivity = 0.75, specificity = 0.58, classification accuracy = 0.86. The second CNN model, developed with transfer learning using the Resnet50 architecture, produced a median AUC = 0.639 sensitivity = 0.92, specificity = 0.18, and classification accuracy 0.82. We discuss the specific training and optimization methods used to compensate for significant class imbalance and maximize sensitivity.

The Use of Mobile Thermal Imaging and Deep Learning for Prediction of Surgical Site Infection.

The ability to detect surgical site infections (SSI) is a critical need for healthcare worldwide, but is especially important in low-income countries, where there is limited access to health facilities and trained clinical staff. In this paper, we present a new method of predicting SSI using a thermal image collected with a smart phone. Machine learning algorithms were developed using images collected as part of a clinical study that included 530 women in rural Rwanda who underwent cesarean section surgery. Thermal images were collected approximately 10 days after surgery, in conjunction with an examination by a trained doctor to determine the status of the wound (infected or not). Of the 530 women, 30 were found to have infected wounds. The data were used to develop two Convolutional Neural Net (CNN) models, with special care taken to avoid overfitting and address the problem of class imbalance in binary classification. The first model, a 6-layer naïve CNN model, demonstrated a median accuracy of AUC=0.84 with sensitivity=71% and specificity=87%. The transfer learning CNN model demonstrated a median accuracy of AUC=0.90 with sensitivity =95% and specificity=84%. To our knowledge, this is the first successful demonstration of a machine learning algorithm to predict surgical infection using thermal images alone.Clinical Relevance- This work establishes a promising new method for automated detection of surgical site infection.

Effect of different handgrip angles on work distribution during hand cycling at submaximal power levels.

The effect of different handle angles on work distribution during hand cycling was determined. Able-bodied subjects performed hand cycling at 20% of maximum power level (mean (SD) power level: 90.0 (25.8) W) at a cadence of 70 rpm using handle angles of +/-30 degrees, +/-15 degrees and 0 degrees. The handle angle had a significant effect on work during the pull down (p < 0.001) and lift up (p = 0.005) sector, whereby the highest work was performed with handle angles of +30 degrees and -15 degrees respectively. The cycle sector had a significant effect on work (p < 0.001) and significantly (p = 0.002) higher work was performed in the pull down sector (25% higher than mean work over one cycle) as compared to the lift up sector (30% lower than mean work over one cycle). Therefore, a fixed handle angle of +30 degrees is suggested to be optimal for power generation. The results of this study help to optimise the handbike-user interface. A more pronated handle angle compared to the one conventionally used was found to improve the performance of hand cycling and thereby the mobility of disabled people.

Platelet activation increases in patients undergoing vascular surgery.

BACKGROUND: Platelets are a major contributor to atherothrombosis and may contribute to the heightened risk of perioperative cardiovascular events. We sought to examine changes in platelet activity in subjects undergoing vascular surgery. METHODS: Platelet activity in 18 patients (median age 74, 45% female) undergoing non-emergent open vascular surgery was assessed by light transmission aggregometry in response to saline, epinephrine and adenosine-5 diphosphate (ADP), and by flow cytometric analysis of monocyte-platelet aggregation (MPA). Platelet activity was assessed preoperatively (T1), 1-hour into the operation (T2), 1-hour (T3), 24-hours (T4) and 48-hours post-operatively (T5). Data were compared using the Wilcoxon Signed Ranks Test. Continuous variables are summarized as medians and (interquartile, IQR) ranges. RESULTS: Spontaneous platelet aggregation increased transiently during the surgical period (T1-5.8% [2.4, 10.8], T2-13.5% [9.3, 26.5], T3-7.5% [3.3, 17], T4-10.0% [7.3, 16.3], T5-7.25% [4.5, 29.9], P=0.002). Similar trends in perioperative platelet activity were noted for platelet aggregation in response to epinephrine (P=0.035) and ADP (P=0.036). Using flow cytometry, we found an increase in MPA during the perioperative period (P=0.047), which was most significant between T1 and T3 (P=0.005). CONCLUSIONS: Platelet activity increases significantly during and following open vascular surgery. This data may help explain the pathophysiology of increased thrombotic risk during the perioperative period of vascular surgery.

Red emitting [Ir(C

2,2':6',2''-Terpyridine (tpy), 4'-(4-HOC6H4)-2,2':6',2''-terpyridine (1), 4'-(4-MeOC6H4)-2,2':6',2''-terpyridine (2), 4'-(4-MeSC6H4)-2,2':6',2''-terpyridine (3), 4'-(4-H2NC6H4)-2,2':6',2''-terpyridine (4) and 4'-(4-pyridyl)-2,2':6',2''-terpyridine (4) act as N^N chelates in complexes of the type [Ir(C^N)2(N^N)][PF6] in which the cyclometallating ligand, C^N, is derived from 2-phenylpyridine (Hppy) or 3,5-dimethyl-1-phenyl-1H-pyrazole (Hdmppz). The single crystal structures of eight complexes have been determined, and in each iridium(III) complex cation, the non-coordinated pyridine ring of the tpy unit is involved in a face-to-face π-stacking interaction with the cyclometallated ring of an adjacent ligand. Solution NMR spectra of the [Ir(ppy)2(N^N)](+) complexes are consistent with the presence of a non-classical hydrogen bond between the non-coordinated N-donor of the tpy domain and a CH unit of one pyridine ring of an adjacent ppy(-) ligand; the presence of the N···HC interaction was confirmed in one of the solid-state structures. The pendant pyridine ring of the coordinated tpy undergoes hindered rotation on the NMR timescale at 295 K. In CH2Cl2, the complexes are orange or red emitters, with λ(max)(em) in the range 580 to 642 nm; photoluminescence quantum yields (PLQY) are <10%, and lifetimes range from 54 to 136 ns. N-Methylation of the pendant 4'-(4-pyridyl) group in [Ir(dmppz)2(pytpy)][PF6] essentially quenches the emission. Light-emitting electrochemical cells (LECs) have been fabricated in a thin film configuration; the emission spectra of the LECs are red-shifted with respect to the PL spectra of the corresponding complex in thin film configuration. For the device incorporating [Ir(ppy)2(pytpy)][PF6], the PL to EL red-shift is extremely large and this is indicative of a different emitting state being involved. The most efficient devices used [Ir(ppy)2(1)][PF6], [Ir(ppy)2(2)][PF6] or [Ir(ppy)2(3)][PF6] in the emissive layer; the devices exhibited rapid turn-on times, but showed relatively low efficiencies in accordance with the solid state photoluminescence quantum yields.

Chloride ion impact on materials for light-emitting electrochemical cells.

Small quantities of Cl(-) ions result in dramatic reductions in the performance of ionic transition metal complexes in light-emitting electrochemical cells. Strong ion-pairing between aromatic protons and chloride has been established in both the solid state and solution. X-ray structural determination of 2{[Ir(ppy)2(bpy)][Cl]}·2CH2Cl2·[H3O]·Cl reveals the unusual nature of an impurity encountered in the preparation of [Ir(ppy)2(bpy)][PF6].

Tuning the photophysical properties of cationic iridium(III) complexes containing cyclometallated 1-(2,4-difluorophenyl)-1H-pyrazole through functionalized 2,2'-bipyridine ligands: blue but not blue enough.

Four new heteroleptic iridium(III) complexes in the family [Ir(dfppz)(2)(N^N)](+), where Hdfppz = 1-(2,4-difluorophenyl)-1H-pyrazole and N^N = 6-phenyl-2,2'-bipyridine (1), 4,4'-(di-tert-butyl)-6-phenyl-2,2'-bipyridine (2), 4,4'-(di-tert-butyl)-6,6'-diphenyl-2,2'-bipyridine (3) and 4,4'-bis(dimethylamino)-2,2'-bipyridine (4), have been synthesized as the hexafluoridophosphate salts and fully characterized. Single crystal structures of ligand 3 and the precursor [Ir(2)(dfppz)(4)(µ-Cl)(2)] have been determined, along with the structures of the complexes 4{[Ir(dfppz)(2)(1)][PF(6)]}·3CH(2)Cl(2), [Ir(dfppz)(2)(3)][PF(6)]·CH(2)Cl(2) and [Ir(dfppz)(2)(4)][PF(6)]·CH(2)Cl(2). The role of inter- and intramolecular face-to-face π-stacking in the solid state is discussed. In the [Ir(dfppz)(2)(N^N)](+) (N^N = 1-3) cations, the phenyl substituent in ligands 1, 2 or 3 undergoes hindered rotation on the NMR timescale at 298 K in solution and the systems have been studied by variable temperature NMR spectroscopy. Acetonitrile solutions of [Ir(dfppz)(2)(N^N)][PF(6)] (N^N = 1-3) exhibit similar absorption spectra arising from ligand-based transitions; absorption intensity is enhanced on going to [Ir(dfppz)(2)(4)][PF(6)] and the spectrum extends further into the visible region. Acetonitrile solutions of the complexes are blue emitters with λ(em) = 517, 505, 501 and 493 nm for N^N = 1, 2, 3 and 4, respectively (λ(exc) = 280-310 nm). The redox behaviours of [Ir(dfppz)(2)(N^N)][PF(6)] (N^N = 1-3) are similar, and the introduction of the electron-donating NMe(2) substituents onto the N^N ligand shifts the metal-centred oxidation to less positive potentials. Theoretical calculations predict a mixed metal-to-ligand/ligand-to-ligand charge transfer (MLCT/LLCT) character for the emitting triplet state in agreement with the broad and unstructured character of the emission bands. The NMe(2) substituents enlarge the HOMO-LUMO gap and blue-shifts the emission of [Ir(dfppz)(2)(4)](+) that is centred on the ancillary ligand. These complexes, when processed into a thin film and sandwiched between two electrodes, lead to very low voltage operating electroluminescent devices. No additional components are needed, which demonstrates their electron and hole transport abilities in conjunction with the luminescent properties.