Alumanyl-Samarium(II): Synthesis, Characterization, and Reactivity Studies.

Metal-metal bonded species involving lanthanides are intriguing but rare. The recently reported salt metathesis reaction of an Al anion and SmI2(thf)2 yields novel heterometallic compound possessing two distinctive Al-Sm bonds. Although the Al-Sm bonds were considerably long [3.518(1) and 3.543(1) Å], DFT calculations indicated polar character of the Alδ--Smδ+ bonds. This is the first example of lanthanide species containing X-type Al ligands. Reactivity studies have demonstrated that the introduction of Sm(II) produces unique reactivity. The reaction with carbodiimide led to an insertion of carbodiimide into the Al-Sm bonds and reductive coupling of carbodiimide to create an oxalamidinate moiety, facilitated by Sm(II). Exposure of the Al-Sm-Al complex toward ethylene furnished a Sm(II) salt of anionic aluminacyclopropane that was spontaneously isomerized to a 1,4-dialuminacyclohexane derivative. The important role of Sm(II) to facilitate the ring expansion through an alkyl-relay mechanism was elucidated by DFT calculations.

[2+2+1+1] Cycloaddition for de novo Synthesis of Densely Functionalized Phenols.

A unique benzannulation strategy for regioselective de novo synthesis of densely functionalized phenols is described. Through metal-mediated formal [2+2+1+1] cycloaddition of two different alkynes and two molecules of CO, a series of densely functionalized phenols were obtained. The benzannulation strategy allows efficient regioselective installation up to five different substituents on a phenol ring. The resulting phenols have a substitution pattern different from those obtained from Dötz and Danheiser benzannulations.

Asymmetric Synthesis of Remotely Chiral Naphthols and Naphthylamines via Naphthoquinone Methides.

Quinone methides are well-established intermediates in asymmetric synthesis. In contrast, their extended analogues with the carbonyl and methide units distributed across two different rings have not been exploited in asymmetric synthesis. Herein, we achieved the first asymmetric process involving such intermediates. Specifically, the use of suitable chiral phosphoric acids enabled in situ generation of 2-naphthoquinone 8-methides and the corresponding aza counterparts for mild one-pot asymmetric nucleophilic addition. These processes provided rapid access to a wide range of previously less accessible remotely chiral naphthols and naphthylamines with both high efficiency and excellent enantioselectivity. Control experiment and DFT calculations provided important insights into the reaction mechanism, which likely involves two phosphoric acid molecules in the enantiodetermining transition states. This work serves as a proof of concept for the exploitation of new types of extended quinone methides as versatile intermediates for asymmetric synthesis, thus providing a new platform for the efficient construction of remote benzylic stereogenic centers of aromatic compounds.

Device-assisted continuous ambulatory peritoneal dialysis: A single-centre experience.

BACKGROUND: Peritoneal dialysis (PD) patients with impaired hand-eye function require helper assistance. Our centre developed a connection device that assists patients with impaired hand-eye function to perform PD exchange themselves, but the clinical outcomes in these patients have not been investigated. METHODS: We retrospectively reviewed patients who had device-assisted continuous ambulatory peritoneal dialysis (CAPD) during 2007-2016 and compared their clinical outcomes with age- and sex-matched patients receiving helper-assisted CAPD. RESULTS: One hundred seventy-two patients (86 each in the device- and helper-assisted CAPD groups) were followed for 29.9 (19.4-43.3) months. The device- and helper-assisted groups had comparable peritonitis rates (0.489 and 0.504 episode per patient-year, respectively, p = 0.814), with no difference in the distribution of causative organisms and the organism-specific peritonitis rates. The device-assisted group showed similar peritonitis-free survival compared with the helper-assisted group (2.58 (1.85-3.31) vs. 1.78 (0.68-2.88) years, p = 0.363) and time-to-PD discontinuation (6.27 (3.65-8.90) vs. 4.35 (3.48-5.22) years, p = 0.677). The median patient survival was similar between the two groups (3.89 (2.22-5.55) vs. 3.81 (3.27-4.36) years in the device- and helper-assisted groups, respectively, p = 0.505). CONCLUSION: Device-assisted CAPD confers comparable outcomes as helper-assisted CAPD and is a viable option in PD patients with impaired hand-eye function.

Al-Sc Bonded Complexes: Synthesis, Structure, and Reaction with Benzene in the Presence of Alkyl Halide.

An alumanyl anion possessing N,N'-bis(2,6-diisopropylphenyl)-1,3-propanediamine ligand was synthesized and characterized. Transmetalation of this Al anion with diaminoscandium chloride precursors afforded the corresponding Al-Sc complexes possessing an unprecedented Al-Sc bond. The Al-Sc[N(SiMe3)2] complex underwent intramolecular C-H cleavage to form a bridged dinuclear complex with µ-hydrido and µ-methylene ligands. The Al-Sc(NiPr2)2 complex reacted with benzene in the presence of alkyl bromide to furnish a 1,4-dialuminated cyclohexadiene product with a concomitant formation of the alkyl-alkyl coupled product. Although the latter product seems to form through the radical mechanism, DFT calculations revealed an ionic mechanism involving bimetallic reaction pathways to react with alkyl bromide and benzene, which provides new insight into the chemistry of metal-metal bonded compounds.

Transition Metal-Free Regio- and Stereo-Selective trans Hydroboration of 1,3-Diynes: A Phosphine-Catalyzed Access to (E)-1-Boryl-1,3-Enynes.

We report a transition metal-free, regio- and stereo-selective, phosphine-catalyzed method for the trans hydroboration of 1,3-diynes with pinacolborane that affords (E)-1-boryl-1,3-enynes. The reaction proceeds with excellent selectivity for boron addition to the external carbon of the 1,3-diyne framework as unambiguously established by NMR and X-ray crystallographic studies. The reaction displays a broad substrate scope including unsymmetrical diynes to generate products in high yield (up to 95 %). Experimental and theoretical studies suggest that phosphine attack on the alkyne is a key process in the catalytic cycle.

TROPOspheric Monitoring Instrument observations of total column water vapour: Algorithm and validation.

In this paper, we present the total column water vapour (TCWV) retrieval for the TROPOspheric Monitoring Instrument (TROPOMI) observations in the visible blue spectral band. The TROPOMI TCWV algorithm is being optimized and validated in the framework of the Sentinel 5 Precursor Product Algorithm Laboratory (S5P-PAL) project from the European Space Agency (ESA). The retrieval was first developed to retrieve TCWV from the Global Ozone Monitoring Experiment 2 (GOME-2). We have optimized the settings of the retrieval to adapt it for TROPOMI observations. The TROPOMI TCWV algorithm follows the typical two step approach, using spectral fit retrieval of slant columns, and conversion of the slant columns to vertical columns using air mass factors (AMFs). An iterative optimization algorithm is developed to dynamically find the optimal a priori water vapour profile for the AMF calculation. Further optimizations on the spectral retrieval, air mass factor calculations as well as a new surface albedo retrieval approach are implemented. The TCWV retrieval algorithm is applied to TROPOMI observations from May 2018 to May 2021. The results are validated by comparing them to ERA5 reanalysis data, GOME-2, MODerate resolution Imaging Spectroradiometer (MODIS) and Special Sensor Microwave Imager Sounder (SSMIS) satellite observations. TCWV derived from TROPOMI observations agree well with the other data sets with Pearson correlation coefficient (R) ranging from 0.96 to 0.99. The mean bias between TROPOMI and ERA5 data is -1.24 kg m-2 for measurements over land and 0.73 kg m-2 for measurements over water. The comparison to MODIS observations show similar results with small dry bias of 1.51,kg m-2 for measurements over land and a small wet bias of 1.25 kg m-2 for measurements over water. Slightly larger dry bias of 1.98 kg m-2 for measurements over land and 1.74 kg m-2 for measurements over water are found when compared to GOME-2 obserations. Compared to SSMIS data over water, TROPOMI observations are bias low by 3.25 kg m-2. The small discrepancies found between TROPOMI and reference data sets are related to the differences in measurement technique, measurement time, surface albedo issue, as well as cloud and aerosol contamination. This study demonstrates that the algorithm can provide stable and consistent results on a global scale and can be applied to generate operational TCWV products from TROPOMI and the forthcoming Copernicus missions Sentinel-4 and Sentinel-5. We have also demonstrated the capability of retrieving fine scale water vapour structures in a case study over the Amazon. This indicates that the TROPOMI data set is also useful for local and regional climate studies.

Optical Sensors and Sensing, 2019: introduction to the joint feature issue.

This joint feature issue of Optics Express and Applied Optics highlights contributions from authors who presented their latest research at the OSA Optical Sensors and Sensing Congress, held in San Jose, California, USA from 25-27 June 2019. The joint feature issue comprises 6 contributed papers, which expand upon their respective conference proceedings. The published papers introduced here cover a range of timely research topics in optics and photonics for active open-path sensing, radiometry, and adaptive optics and fiber devices.

First observation of tropospheric nitrogen dioxide from the Environmental Trace Gases Monitoring Instrument onboard the GaoFen-5 satellite.

The Environmental Trace Gases Monitoring Instrument (EMI) is the first Chinese satellite-borne UV-Vis spectrometer aiming to measure the distribution of atmospheric trace gases on a global scale. The EMI instrument onboard the GaoFen-5 satellite was launched on 9 May 2018. In this paper, we present the tropospheric nitrogen dioxide (NO2) vertical column density (VCD) retrieval algorithm dedicated to EMI measurement. We report the first successful retrieval of tropospheric NO2 VCD from the EMI instrument. Our retrieval improved the original EMI NO2 prototype algorithm by modifying the settings of the spectral fit and air mass factor calculations to account for the on-orbit instrumental performance changes. The retrieved EMI NO2 VCDs generally show good spatiotemporal agreement with the satellite-borne Ozone Monitoring Instrument and TROPOspheric Monitoring Instrument (correlation coefficient R of ~0.9, bias < 50%). A comparison with ground-based MAX-DOAS (Multi-Axis Differential Optical Absorption Spectroscopy) observations also shows good correlation with an R of 0.82. The results indicate that the EMI NO2 retrieval algorithm derives reliable and precise results, and this algorithm can feasibly produce stable operational products that can contribute to global air pollution monitoring.

Optical Sensors and Sensing 2019: introduction to the joint feature issue.

This joint feature issue of Optics Express and Applied Optics highlights contributions from authors who presented their latest research at the OSA Optical Sensors and Sensing Congress, held in San Jose, California, USA, from 25-27 June 2019. The joint feature issue comprises six contributed papers, which expand upon their respective conference proceedings. The published papers introduced here cover a range of timely research topics in optics and photonics for active open-path sensing, radiometry, and adaptive optics and fiber devices.

Multi-layer solar radiative transfer considering the vertical variation of inherent microphysical properties of clouds.

A multi-layer solar radiative transfer (RT) scheme is proposed to deal with the vertical variation of inherent microphysical properties of clouds in this study. The exponential expressions are used to represent the vertical variation of optical properties caused by inhomogeneous microphysical properties. A perturbation method, coupled with the Eddington approximation, is used to solve the RT equation. In order to have a more accurate estimation of reflectance/transmittance for every single layer, the optical properties are adjusted following the theory of delta scaling in the proposed scheme. In addition, a modified adding method based on Chandrasekhar's invariance principle is introduced to solve the multi-layer RT. The accuracy of the proposed scheme is investigated by comparing the reflectance/absorptance to the benchmark for two double-layer cases, and each layer with vertically inhomogeneous optical properties. Results show that the bias related to vertically inhomogeneous optical properties reaches 13.8 % for reflectance and 29.2 % for absorptance while the bias of the proposed scheme is only -0.8 % for reflectance and 1.7 % for absorptance. We also apply the proposed scheme as well as the conventional Eddington approximation to the CanadianClimate Center RT model which handle RT in CanAM4. The calculations are performed in the following four solar wavenumber bands 2500-4200, 4200-8400, 8400-14500 and 14500-50000 cm -1. The result also shows that the proposed scheme also improved the accuracy in both flux and heating rate calculation by taking the vertical variation of inherent microphysical properties into account. The proposed scheme is approximately three times more computationally expensive compared to the Eddington approximation when we only consider the algorithm itself. The computational time is doubled compared to the Eddington approximation when we take the complete radiative transfer process into account. Due to its accuracy and efficiency, the proposed scheme is suitable to improve the RT calculations regarding the vertical variation of inherent microphysical properties in climate models.

Factors affecting patient-reported outcomes after red blood cell transfusion in medical patients.

BACKGROUND: Physical variables like mortality or cardiac events were used to evaluate the requirement of red blood cell (RBC) transfusion. However, patient-reported outcomes (PROs) of blood transfusion recipients were seldom assessed. The health-related quality of life (HRQoL) of patients before and after RBC transfusion was compared in this study. STUDY DESIGN AND METHODS: The study period was February to June 2016. Standardized generic and anemia symptom-specific HRQoL instruments were administered to patients receiving RBC transfusion in the medical unit of a single center. The primary outcome was the change in HRQoL scores on Days 1 and 7 posttransfusion from baseline values on the day of transfusion (Day 0). Multiple linear regression analysis was performed to study the effect of transfusion strategy and other factors on PRO. RESULTS: The analysis included 99 general medical patients. The median (interquartile range) pretransfusion hemoglobin level was 72 (66-78) g/L. Two or more units of RBCs were prescribed to 45 patients (45%) on Day 0. Functional Assessment of Cancer Therapy-Anemia Subscale improved significantly on Days 1 and 7 by effect sizes of 0.41 and 0.38, respectively (p < 0.001). Regression analysis showed that lower baseline HRQoL scores were associated with better PRO on both Day 1 and Day 7 (p < 0.001). Transfusion trigger and number of RBC units transfused did not affect the change in HRQoL. CONCLUSION: Worse pretransfusion HRQoL is a predictor of improvement in PRO after blood transfusion. There is no evidence that a restrictive transfusion or single-unit policy jeopardizes PRO.

On the summertime air quality and related photochemical processes in the megacity Shanghai, China.

Summertime surface ozone (O3) and related secondary formation of fine particles are the major air quality concerns in the megacity of Shanghai. We performed mobile Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) measurements to investigate the spatial distribution of on-road nitrogen dioxide (NO2) concentrations along the Inner Ring Elevated Road (IRER) in Shanghai. The observations show a ratio of 4 between CE-DOAS averaged on-road NO2 and the in-situ ambient measurements, illustrating the strong impact of vehicle emissions over the urban area. The air mass transport analysis suggests that the observed episodic ozone events arise from both the abundance of volatile organic compounds (VOCs) precursors in the sampled plume and the regional transport of ozone-rich air masses. Analysis of the sources of PM2.5 shows that the secondary heterogeneous gas-to-particle conversion of sulfate and nitrate from sulfur dioxide (SO2) and nitrogen oxides (NOx) is the largest source of PM2.5 contributing 44.8±9.2% of the total PM2.5. Ozone-related photochemical formation of fine particles is estimated to contribute about 22.5±11.9% of the total PM2.5, which is strongly facilitated by solar radiation in summer. According to our results, nitrous acid (HONO) is the major precursor of hydroxyl radicals (OH) accounting for 40% to 80% of the total OH production during daytime. A significant correlation is found between the HONO levels in the early morning and the daily O3 and PM2.5 levels. The summertime measurements indicate that the photolytic reaction of HONO after sunrise increased the abundance of daytime OH and oxidative capacity, resulting in an enhancement of ground level ozone and secondary organic aerosol formation. This study provides quantitative information to better understand photochemical formation of ozone and fine particles in Shanghai during summertime, which is useful for designing collaborative strategies to mitigate emissions of precursor pollutants.

Spatial and seasonal heterogeneity of atmospheric particles induced reactive oxygen species in urban areas and the role of water-soluble metals.

Adverse health effects are associated with exposure to atmospheric particulate matter (PM), which carry various chemical constituents and induce both exogenous and endogenous oxidative stress. This study investigated the spatial and seasonal variability of PM-induced ROS at four sites with different characteristics in Hong Kong. Cytotoxicity, exogenous and endogenous ROS was determined on a dose and time dependent analysis. Large spatial variation of ROS was observed with fine PM at urban site showing highest ROS levels while coarse PM at traffic site ranks the top. No consistent seasonal difference was observed for ROS levels among all sites. The highly heterogeneous distribution of PM-induced ROS demonstrates the differential capability of PM to produce oxidative stress, and the need to use appropriate metrics as surrogates of exposure instead of PM mass in epidemiologic studies. Several transition metals were found associated with ROS by different degree illustrating the complexity of mechanisms involved.

Relationship of serum brain-derived neurotrophic factor (BDNF) and health-related lifestyle in healthy human subjects.

The associations between serum brain-derived neurotrophic factor (BDNF) levels and several health-related lifestyle factors were evaluated in 85 healthy human subjects. Results showed that the frequency of fruit intake, exercise and television watching were associated with serum BDNF level. There was a higher serum BDNF level from the group with fruit intake five to six times per week. Subjects with moderate frequency of exercise (1-30 times of 30 min exercise per month) showed higher serum BDNF level than the group with exercise more than 30 times per month. There was a significant positive correlation between serum BDNF and the daily average watching television time in the younger age group (18-35). The result of this study supports the need for larger studies with different health-related lifestyle in healthy subjects or subjects with disorders.