Synthesis, Structure, and Properties of 2O-BaPtO3, a Phase Derived from Hexagonal Perovskite.

We have made the compound 2O-BaPtO3 by high-pressure, high-temperature synthesis, determined its structure, and tested its catalytic activity. Compounds of the same stoichiometry have been reported and tentatively identified as hexagonal perovskites, and although no structural model was ever established, 2O-BaPtO3 is clearly different and, to the best of our knowledge, unique. It features continuous chains of face-sharing PtO6 octahedra, like the well-known 2H hexagonal perovskite type, but with a staggered offset between the chains that breaks hexagonal symmetry and disrupts the close-packed array of A = Ba and X = O that is a defining characteristic of ABX3 perovskites. We investigated this structure and its stability vs the conventional 2H form using X-ray and neutron diffraction, X-ray absorption spectroscopy, and ab initio calculations. Catalytic testing of 2O-BaPtO3 showed that it is active for hydrogen evolution.

Structural Properties of Some Vacancy-Ordered Platinum Halide Perovskites.

The structural changes that accompany the dehydration of Na2PtX6·6H2O (X = Cl, Br) were studied using in situ variable temperature synchrotron X-ray diffraction. The two hexahydrates are isostructural, containing isolated PtX6 octahedra separated by Na cations. Removal of the water results in the formation of the anhydrous vacancy ordered double perovskites Na2PtX6. The Na cation is too small for the cuboctahedron site of the parent cubic structure, resulting in cooperative tilting of the PtX6 octahedra and lowering of the symmetry. Replacing Na with a larger alkali metal (K, Rb, or Cs) invariably enabled the isolation of the anhydrous hexahalide, and we found no evidence that these readily hydrated. For all cations, other than Na, it was possible to observe the archetypical cubic structure, although for the two potassium salts K2PtBr6 and K2PtI6, this was only observed above a critical temperature of 175 and 460 K, respectively. As these two samples were cooled, symmetry lowering was observed, yielding a tetragonal structure initially and ultimately a monoclinic structure: Fm3̅m → P4/mnc → P21/n. These phase transitions are associated with the onset of long-range cooperative tilting of the PtX6 octahedra described using the Glazer tilt notation as a0a0a0 → a0a0c+ → a-a-c+.

Do hospitals that participate in COVID-19 research differ from non-trial hospitals? A cross-sectional study of US hospitals.

OBJECTIVES: To compare hospitals that did and did not participate in clinical trials evaluating potential inpatient COVID-19 therapeutics. METHODS: We conducted a cross-sectional study of hospitals participating in trials that were registered on clinicaltrials.gov between April and August 2020. Using the 2019 RAND Hospital Dataset and 2019 American Community Survey, we used logistic regression modeling to compare hospital-level traits including demographic features between trial and non-trial hospitals. RESULTS: We included 488 hospitals that were participating in 298 interventional trials and 4232 non-participating hospitals. After controlling for demographic and other hospital traits, we found that teaching status (OR 2.11, 95% CI 1.52-2.95), higher patient acuity (OR 7.48, 4.39, 13.1), and location in the Northeast (OR 1.83, 95% CI 1.18, 2.85) and in wealthier counties (OR: 1.32, 95% CI 1.16-1.51) were associated with increased odds of trial participation, while being in counties with more White residents was associated with reduced odds (OR 0.98, 95% CI 0.98-0.99). CONCLUSIONS: Hospitals participating and not participating in COVID-19 inpatient treatment clinical trials differed in many ways, resulting in important implications for the generalizability of trial data.

Real-time transcription polymerase chain reaction cycle threshold values as criteria for utilization of incidental COVID-19 positive lung donors.

Shortage of organ donors is an ongoing limiting factor in lung transplantation (LT). Despite increasing prevalence of asymptomatic COVID-19 infection, positive COVID-19 testing from a potential donor remains a contraindication at many LT centers. In this report, we present the outcomes of LT utilizing an algorithm based on donor clinical presentation, and COVID-19 real-time reverse transcription polymerase chain reaction (RT-PCR) with cycle threshold (Ct) values evaluation. The Ct value threshold for organ acceptance was >35. A total of 8 COVID-positive donors were included. No donor-to-recipient transmissions of COVID-19 were observed. Short-term outcomes were comparable to those reported in pre-COVID literature. Survival-to-date is 100% with median POD of 161 days. Our findings support the safety and efficacy of utilizing our algorithm including Ct value threshold for selection of donors with incidental COVID-19 positive testing.

MR imaging biomarkers in HCC: outcomes correlation in liver transplant listed patients.

PURPOSE: To determine hepatocellular carcinoma (HCC) magnetic resonance imaging (MRI) biomarkers that enable the prediction of delisting from tumor progression versus successful transplantation in patients listed for orthotopic liver transplantation (OLT). METHODS: With IRB approval and HIPPA compliance, patients with HCC awaiting OLT who were delisted due to HCC progression from 2006 to 2015 were identified. Patients with adequate MR images for review were subsequently matched with a cohort of patients successfully bridged to OLT in the same time period. Matching considered the tumor stage and the dominant treatment strategy adopted to bridge the patient to OLT. Potential MRI features were evaluated by univariable and multivariable analysis using a conditional logistic model. RESULTS: There were 53 patients included in each cohort. On uni-variable analysis, significant unfavorable MR imaging features included T2 hyperintensity (odds ratio [OR], 19.0), infiltrative border (OR, 7.50), lobulated shape (OR, 4.5), T1 hypointensity (OR, 3.0), heterogeneous arterial enhancement (OR, 7.0), and corona venous enhancement (OR, 4.0). A significant favorable MR imaging feature was the presence of intralesional fat (OR = .36). The best multivariable logistic prediction model derived from the above notable features included only T1 and T2 signal intensity, border definition, and absence of intra-lesional fat as significant variables, with an area under the receiver operating characteristic curve (AUC) of .86 in the prediction of delisting. CONCLUSION: Select MR imaging features of HCC at presentation before any treatment are significantly associated with the risk of tumor progression regardless of tumor stage and treatment strategy in patients awaiting liver transplantation.

Elephant seals time their long-distance migrations using a map sense.

Many marine animals migrate between foraging areas and reproductive sites, often timing the return migration with extreme precision. In theory, the decision to return should reflect energy acquisition at foraging areas, energetic costs associated with transit, and timing arrival for successful reproduction. For long-distance migrations to be successful, animals must integrate 'map' information to assess where they are relative to their reproductive site as well as 'calendar' information to know when to initiate the return migration given their distance from home1. Elephant seals, Mirounga angustirostris, migrate thousands of kilometers from reproductive sites to open ocean foraging areas (Figure 1A), yet return within a narrow window of time to specific beaches2. Each year, pregnant female elephant seals undertake a ∼240-day, 10,000 km foraging migration across the Northeast Pacific Ocean before returning to their breeding beaches, where they give birth 5 days after arriving2. We found that the seals' abilities to adjust the timing of their return migration is based on the perception of space and time, which further elucidates the mechanisms behind their astonishing navigational feats3.

Prognostic implications of pre-existing medical comorbidity in Takotsubo cardiomyopathy.

Takotsubo cardiomyopathy (TC) is associated with significant short-term morbidity and mortality. Several risk factors for poor outcomes have been identified; however, the prognostic implications of pre-existing comorbidity in TC are poorly delineated. We sought to assess the association of aggregate pre-existing comorbidity with short-term outcomes in TC. We performed a retrospective observational study of adult subjects diagnosed with TC at two academic tertiary care hospitals between 2005 and 2018. Overall burden of medical comorbidity was estimated using the Charlson comorbidity index (CCI). Multivariable logistic regression was used to test for independent association of CCI with 30-day mortality and severe shock at index presentation. Multivariable poisson regression was performed to assess the association of CCI with duration of hospitalization. Five-hundred and thirty-eight subjects were diagnosed with TC during the study period. The median CCI score of all subjects was 2 (IQR 1-4). Among subjects with physical triggers of TC, the median CCI score was 2 (IQR 1-4) compared to a median CCI score of 1 (IQR 0-1) in subjects with non-physical triggers of TC (P < 0.001). Seventy-six (14%) subjects died within 30 days of index diagnosis and 185 (34%) subjects experienced severe shock. The median duration of hospitalization was 7 days (IQR 3-14 days). In multivariable logistic regression, CCI was not associated with 30-day mortality or severe shock. In multivariable Poisson regression, CCI (IRR 1.17, 95% CI 1.16-1.18, P < 0.001) was associated with duration of hospitalization. Increased burden of pre-existing medical comorbidity was not independently associated with 30-day mortality or severe shock at index presentation, but was associated with increased duration of hospitalization after diagnosis of TC.

Structural and Magnetic Studies of ABO4-Type Ruthenium and Osmium Oxides.

Oxides of the form ABO4 with A = K, Rb, Cs and B = Ru and Os have been synthesized and characterized by diffraction and magnetic techniques. For A = K the oxides adopted the tetragonal (I41/a) scheelite structure. RbOsO4, which crystallizes as a scheelite at room temperature, underwent a continuous phase transition to I41/amd near 550 K. RbRuO4 and CsOsO4 were found to crystallize in the orthorhombic (Pnma) pseudoscheelite structure, and both displayed discontinuous phase transitions to I41/a at high temperatures. CsOsO4 was determined to undergo a phase transition to a P21/c structure below 140 K. CsRuO4 crystallizes with a baryte-type structure at room temperature. Upon heating CsRuO4 a first order phase transition to the scheelite structure in I41/a is observed at 400 K. A continuous phase transition is observed to P212121 below 140 K. DC magnetic susceptibility data is consistent with long-range antiferromagnetic ordering at low temperatures for all compounds except for CsOsO4, which is paramagnetic to 2 K. The effective magnetic moments are in agreement with the spin only values for an S = 1/2 quantum magnet. Effective magnetic moments calculated for Os compounds were lower than their Ru counterparts, reflective of an enhanced spin orbit coupling effect. A magnetic structure is proposed for RbRuO4 consisting of predominately antiferromagnetic (AFM) ordering along the 001 direction, with canting of spins in the 100 plane. A small ordered magnetic moment of 0.77 µB was determined.

Hydrothermal Liquefaction of α-O-4 Aryl Ether Linkages in Lignin.

By using lignin model compounds with relevant key characteristic structural features, the reaction pathways of α-O-4 aryl ether linkages under hydrothermal conditions are elucidated. Experimental results and computational modeling suggest that the α-O-4 linkages in lignin undergo catalyzed hydrolysis and elimination to give phenolic and alkenylbenzene derivatives as major products in subcritical water. The decreased relative permittivity of water at these high temperatures and pressures facilitates the elimination reactions. The alkyl group on the α-carbon and the methoxy groups on the phenyl rings both have positive effects on the rate of conversion of α-O-4 linkages in native lignin.

Percutaneous thermal ablation of subcapsular hepatocellular carcinomas: influence of tumor-surface contact and protrusion on therapeutic efficacy and safety.

PURPOSE: To evaluate therapeutic efficacy and complication of percutaneous thermal ablation of subcapsular hepatocellular carcinomas (HCCs), and how these may be influenced by the degree of tumor to liver surface contact and tumor protrusion from liver surface. MATERIALS AND METHODS: Our retrospective study was approved by the Institutional Review Board. Between January 2006 and December 2013, 290 patients (82 women, 208 men; mean age, 64.5 years; range, 33-89 years) with 474 subcapsular (within 1 cm to the liver surface) HCCs (mean size, 23.7 mm; range, 6-71 mm) underwent percutaneous thermal ablation. The HCCs were divided into surface contact group (n = 243) and non-surface contact group (n = 231). The former was further subdivided into exophytic and non-exophytic HCCs. Technical success, primary technique efficacy, local tumor progression (LTP), and secondary technique efficacy rates were analyzed and compared by the chi-square test or Fisher exact test. Prognostic factors for LTP and secondary technique efficacy were assessed using the Cox regression model. Major complications were also assessed. RESULTS: With median follow-up of 15 months (range, 1-87 months), technical success and primary technique efficacy were 98.7% and 95.7% % in the non-surface contact group; 96.4% and 94.0% in the non-exophytic group; and 100% and 94.7% in the exophytic group (p > 0.05). Tumor size > 3 cm was a significant predictor for LTP, but not for secondary efficacy. Overall major complication rate was 3.8% (24/624) and was not different among the three groups. CONCLUSION: Subcapsular HCCs can be effectively treated with thermal ablation techniques. Degree of tumor-surface contact including moderate protrusion does not appear to limit feasibility or procedure effectiveness. KEY POINTS: • Subcapsular HCCs can be effectively treated with thermal therapy when proper image-guided technique and assistive techniques are applied. • Degree of tumor surface contact including moderate protrusion does not appear to limit feasibility or procedure effectiveness. • Major complications after percutaneous thermal ablation of subcapsular HCCs such as tumor seeding can be minimized by avoiding breach of the tumor capsule exposed to the peritoneal surface and use of tract ablation.

Structural and magnetic studies of KOsO4, a 5d1 quantum magnet oxide.

The quantum magnet KOsO4 has been characterized by a combination of X-ray and neutron diffraction techniques. The tetrahedrally coordinated Os7+ 5d1S = 1/2 cations were determined to order antiferromagnetically along the c axis below 35 K. A miniscule ordered magnetic moment of 0.46(18) µB was determined per Os7+ cation.

Impact of Hypothyroidism and Heart Failure on Hospitalization Risk.

BACKGROUND: Prior studies suggest that the relationship between hypothyroidism and mortality is dependent on underlying cardiovascular risk. Little is known about the association of hypothyroidism with hospitalization risk, and how these associations are modified by cardiovascular status. METHODS: This study examined the association of thyroid status, defined by serum thyrotropin (TSH), with hospitalization risk among patients who received care at a large university-based tertiary care center between 1990 and 2015. Thyroid status was categorized as hypothyroidism versus euthyroidism (TSH >4.7 vs. 0.3-4.7 mIU/L, respectively). The relationship between thyroid status and hospitalization risk stratified by cardiovascular status was examined using multivariable Cox models. RESULTS: Among 52,856 patients who met eligibility criteria, 49,791 (94.2%) had euthyroidism and 3065 (5.8%) had hypothyroidism. In analyses stratified by congestive heart failure (CHF) status, compared to euthyroidism, hypothyroidism was associated with higher risk of hospitalization in those with CHF but slightly lower risk in those without CHF (adjusted hazard ratio [aHRs] = 1.86 [confidence interval (CI) 1.17-2.94] and HR = 0.95 [CI 0.92-0.99], respectively; p = 0.006). In sensitivity analyses accounting for death as a competing event, underlying coronary artery disease modified the hypothyroidism-hospitalization relationship, such that stronger associations were observed among those with versus without coronary artery disease. In competing risk analyses, hypothyroidism was associated with higher versus lower risk of hospitalization among those with versus without cerebrovascular disease, respectively. CONCLUSIONS: Hypothyroidism is associated with higher hospitalization risk among patients with underlying cardiovascular disease. Future studies are needed to determine whether correction of thyroid status with replacement therapy ameliorates hospitalization risk in this population.

Biodegradable Polycarbonate Iongels for Electrophysiology Measurements.

In recent years, gels based on ionic liquids incorporated into polymer matrices, namely iongels, have emerged as long-term contact media for cutaneous electrophysiology. Iongels possess high ionic conductivity and negligible vapor pressure and can be designed on demand. In spite of the extensive efforts devoted to the preparation of biodegradable ionic liquids, the investigations related to the preparation of iongels based on biodegradable polymers remain scarce. In this work, biodegradable polycarbonate-based iongels are prepared by ring-opening polymerization of N-substituted eight ring membered cyclic carbonate monomers in the presence of imidazolium lactate ionic liquid. Our iongels are able to take up 10⁻30 wt % of ionic liquid and become softer materials by increasing the amount of free ionic liquid. Rheological measurements showed that the cross-over point between the storage modulus G' and loss modulus G″ occurs at lower angular frequencies when the loading of free ionic liquid increases. These gels are able to take up to 30 wt % of the ionic liquid and the ionic conductivity of these gels increased up to 5 × 10-4 S·cm-1 at 25 °C as the amount of free ionic liquid increased. Additionally, we assess the biodegradation studies of the iongels by immersing them in water. The iongels decrease the impedance with the human skin to levels that are similar to commercial Ag/AgCl electrodes, allowing an accurate physiologic signals recording. The low toxicity and biodegradability of polycarbonate-based iongels make these materials highly attractive for cutaneous electrophysiology applications.

Factors Associated With Discordance Between Preoperative Parathyroid 4-Dimensional Computed Tomographic Scans and Intraoperative Findings During Parathyroidectomy.

IMPORTANCE: Parathyroid 4-dimensional computed tomographic scans (4D-CTs) have emerged as an accurate and cost-effective initial localization study for patients with primary hyperparathyroidism. However, potential limitations and factors affecting the accuracy of preoperative 4D-CTs remain poorly defined. OBJECTIVES: To characterize factors associated with missed parathyroid lesions on preoperative 4D-CTs and to investigate patterns of commonly observed errors. DESIGN, SETTING, AND PARTICIPANTS: A prospectively accrued patient database was analyzed from September 1, 2011, through October 31, 2016. The study was performed in a tertiary referral center. Consecutive patients with primary hyperparathyroidism undergoing preoperative 4D-CTs and subsequent parathyroidectomy were included in the study. MAIN OUTCOMES AND MEASURES: Discordance between preoperative 4D-CTs and intraoperative findings in the number and location of abnormal parathyroid lesions. RESULTS: Of 411 patients studied (mean [SD] age, 59 [14] years; 325 [79.1%] female), 123 (29.9%) had discordance between preoperative 4D-CTs and intraoperative findings. Among the 411 patients, 75 (18.2%) had major discordance, including incorrectly localized adenoma on the contralateral side of the neck, missed double adenoma, and absence of any abnormal lesion detected on 4D-CTs. Compared with concordant cases, discordant cases had higher frequencies of multigland disease (66.7% [82 of 123] vs 24.3% [70 of 288], P < .001) and multinodular goiter or thyroid nodule (40.7% [50 of 123] vs 29.2% [84 of 288], P = .02). Missed parathyroid lesions were smaller (mean [SD], 0.86 [0.29] vs 1.24 [0.50] cm; P < .001) and were more likely to be in the inferior position (65.4% [87 of 133] vs 38.1% [177 of 465], P < .001). Parathyroid lesion size of 10 mm or less (odds ratio [OR], 4.37; 95% CI, 2.24-8.54), multigland disease (OR, 7.63; 95% CI, 3.49-16.69), multinodular goiter or thyroid nodule (OR, 1.82; 95% CI, 1.01-3.28), and parathyroid lesion in the inferior position (OR, 6.82; 95% CI, 3.10-14.99) were independently associated with discordant 4D-CT results. CONCLUSIONS AND RELEVANCE: Multigland disease was most strongly associated with discordance between preoperative 4D-CTs and intraoperative findings, followed by parathyroid lesion in the inferior position and parathyroid lesion size of 10 mm or less. Awareness of these potential pitfalls may allow surgeons to better leverage this new localization technique in preoperative planning and intraoperative troubleshooting.

Broad Spectrum Macromolecular Antimicrobials with Biofilm Disruption Capability and In Vivo Efficacy.

In this study, antimicrobial polymers are synthesized by the organocatalytic ring-opening polymerization of an eight-membered heterocyclic carbonate monomer that is subsequently quaternized with methyl iodide. These polymers demonstrate activity against clinically relevant Gram-positive Staphylococcus epidermidis and Staphylococcus aureus, Gram-negative Escherichia coli and Pseudomonas aeruginosa, and fungus Candida albicans with fast killing kinetics. Importantly, the polymer efficiently inhibits biofilm growth and lyses existing biofilm, leading to a reduction in biomass and cell viability. In addition, the macromolecular antimicrobial is less likely to induce resistance as it acts via a membrane-lytic mechanism. The polymer is not cytotoxic toward mammalian cells with LD50 of 99.0 ± 11.6 mg kg-1 in mice through i.v. injection. In an S. aureus blood stream infection mouse model, the polymer removes bacteria from the blood more rapidly than the antibiotic Augmentin. At the effective dose, the polymer treatment does not damage liver and kidney tissues or functions. In addition, blood electrolyte balance remains unchanged after the treatment. The low cost of starting materials, ease of synthesis, nontoxicity, broad spectrum activity with fast killing kinetics, and in vivo antimicrobial activity make these macromolecular antimicrobials ideal candidates for prevention of sepsis and treatment of infections.

Unravelling Some of the Key Transformations in the Hydrothermal Liquefaction of Lignin.

Using both experimental and computational methods, focusing on intermediates and model compounds, some of the main features of the reaction mechanisms that operate during the hydrothermal processing of lignin were elucidated. Key reaction pathways and their connection to different structural features of lignin were proposed. Under neutral conditions, subcritical water was demonstrated to act as a bifunctional acid/base catalyst for the dissection of lignin structures. In a complex web of mutually dependent interactions, guaiacyl units within lignin were shown to significantly affect overall lignin reactivity.

Preparation of Biodegradable Cationic Polycarbonates and Hydrogels through the Direct Polymerization of Quaternized Cyclic Carbonates.

Polymers exhibiting both antimicrobial and biodegradable properties are of great interest for next generation materials in healthcare. Among those, cationic polycarbonates are one of the most promising classes of materials because of their biodegradability, low toxicity, and biocompatibility. They are typically prepared by a chemical postmodification after the polymer has been synthesized. The main problem with the latter is the challenges of ensuring and verifying complete quaternization within the polymer structure. Herein, we report the first example of synthesizing and polymerizing charged aliphatic cyclic carbonates with three different alkane pendant groups (N-methyl, N-butyl, and N-hexyl) by ring-opening polymerization (ROP). These charged eight-membered cyclic carbonates displayed extraordinary reactivity and were even polymerizable in polar solvents (e.g., DMSO) and in catalyst free conditions that are generally unobtainable for other ring opening polymerization processes. A computational study was carried out and the findings were in agreement with the experimental data in regards to the dramatic increase in reactivity of the charged monomer over their neutral analogs. Furthermore, a series of hydrogels were prepared using the different charged eight-membered cyclic carbonates, and we found it to have a significant impact on the hydrogels' ability to swell and degrade in water. Finally, the hydrogels demonstrated antibacterial activity against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). These materials could be ideal candidates for biologically relevant applications where cationic structure is required.