Speciation of Technetium Dibutylphosphate in the Third Phase Formed in the TBP/HNO3 Solvent Extraction System.

The speciation of technetium in the nitric acid/dibutylphosphoric acid (HDBP)-n-dodecane system was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy and theoretical methods. Tetravalent technetium, produced by the hydrazine reduction of TcO4- in 3 M HNO3, was extracted by HDBP in n-dodecane (30% by volume). During extraction, the splitting of the organic phase into a heavy phase and a light phase was observed. EXAFS analysis is consistent with the presence of Tc(NO3)3(DBP)(HDBP)2 in the light phase and Tc(NO3)2(DBP)2(HDBP)2 in the heavy phase. Density functional theory calculations at the B3LYP/6-31G* level confirm the stability of the proposed species and indicate that stereoisomers -mer- and fac-Tc(NO3)3(DBP)(HDBP)2 for the light phase and cis- and trans-Tc(NO3)2(DBP)2(HDBP)2 for the heavy phase] could coexist in the system (in the n-dodecane solution). Mechanisms of formation of Tc(NO3)3(DBP)(HDBP)2 and Tc(NO3)2(DBP)2(HDBP)2 are proposed.

Structural Investigation of Technetium Dibutylphosphate Species Using X-ray Absorption Fine Structure Spectroscopy.

The speciation of Tc after the extraction of Tc(IV) from H2O and 1 M HNO3 by dibutylphosphoric acid (HDBP) in dodecane has been studied by X-ray absorption fine structure (XAFS) spectroscopy. Results show the formation of dimeric species with Tc2O2 and Tc2O units, and the formulas [Tc2O2(DBP·HDBP)4] (1) and [Tc2O(NO3)2(DBP)2(DBP·HDBP)2] (2) were, respectively, proposed for the species extracted from H2O and 1 M HNO3. The interatomic Tc-Tc distances found in the Tc2O2 and Tc2O units [2.55(3) and 3.57(4) Å, respectively] are similar to the ones found in Tc(IV) dinuclear species. It is likely that the speciation of Tc(IV) in dodecane is due to the extraction of a species with a Tc2O unit for (2) and to the redissolution of a Tc(IV)-DBP solid for (1). The XAFS results for (1) and (2) were compared to that obtained for the extraction of Tc(IV) with TBP/HDBP/dodecane from 0.5 M HNO3, (3) which highlight the formation of Tc mononuclear nitrate species {i.e., [Tc(NO3)3(DBP)] or [Tc(NO3)2(DBP·HDBP)]}. These results confirm the importance of the preparation and speciation of the Tc(IV) aqueous solutions prior to extraction and how much this influences and drives the final Tc speciation in organic extraction. These studies outline the complexity of Tc separation chemistry and provide insights into the behavior of Tc during the reprocessing of used nuclear fuel.

Understanding Proton Transfer in Non-aqueous Biopolymers based on Helical Peptides: A Quantum Mechanical Study.

Histidine (an imidazole-based amino acid) is a promising building block for short aromatic peptides containing a proton donor/acceptor moiety. Previous studies have shown that polyalanine helical peptides substituted at regular intervals with histidine residues exhibit both structural stability as well as high proton affinity and high conductivity. Here, we present first-principle calculations of non-aqueous histidine-containing 310-, α- and π-helices and show that they are able to form hydrogen-bonded networks mimicking proton wires that have the ability to shuttle protons via the Grotthuss shuttling mechanism. The formation of these wires enhances the stability of the helices, and our structural characterizations confirm that the secondary structures are conserved despite distortions of the backbones. In all cases, the helices exhibit high proton affinity and proton transfer barriers on the order of 1~4 kcal/mol. Zero-point energy calculations suggest that for these systems, ground state vibrational energy can provide enough energy to cross the proton transport energy barrier. Additionally, ab initio molecular dynamics results suggests that the protons are transported unidirectionally through the wire at a rate of approximately 2 Å every 20 fs. These results demonstrate that efficient deprotonation-controlled proton wires can be formed using non-aqueous histidine-containing helical peptides.

Prospective telehealth analysis of functional performance, frailty, quality of life, and mental health after COVID-19 hospitalization.

BACKGROUND: COVID-19 is a global pandemic with poorly understood long-term consequences. Determining the trajectory of recovery following COVID-19 hospitalization is critical for prioritizing care, allocating resources, facilitating prognosis, and informing rehabilitation. The purpose of this study was to prospectively evaluate recovery following COVID-19 hospitalization. METHODS: Participants age 18 years or older who were hospitalized for ≥24 h due to COVID-19 completed phone/video call virtual assessments (including the 10-time chair rise test) and survey forms at three time points (2-6, 12, and 18 weeks) after hospital discharge. Univariate logistic and linear regression models assessed the associations of the outcomes with primary predictors (categorical age, sex, race/ethnicity group, and categorical pre-hospitalization frailty) at baseline; the same were used to assess differences in change from week 2-6 (continuous outcomes) or outcome persistence/worsening (categorical) at last contact. RESULTS: One hundred nine adults (age 53.0 [standard deviation 13.1]; 53% female) participated including 43 (39%) age 60 or greater; 59% identified as an ethnic and/or racial minority. Over 18 weeks, the mean time to complete the 10-time chair rise test decreased (i.e., improved) by 6.0 s (95% CI: 4.1, 7.9 s; p < 0.001); this change did not differ by pre-hospital frailty, race/ethnicity group, or sex, but those age ≥ 60 had greater improvement. At weeks 2-6, 67% of participants reported a worse Clinical Frailty Scale category compared to their pre-hospitalization level, whereas 42% reported a worse frailty score at 18 weeks. Participants who did not return to pre-hospitalization levels were more likely to be female, younger, and report a pre-hospitalization category of 'very fit' or 'well'. CONCLUSIONS: We found that functional performance improved from weeks 2-6 to 18 weeks of follow-up; that incident clinical frailty developed in some individuals following COVID-19; and that age, sex, race/ethnicity, and pre-hospitalization frailty status may impact recovery from COVID-19. Notably, individuals age 60 and older were more likely than those under age 45 years to return to their pre-hospitalization status and to make greater improvements in functional performance. The results of the present study provide insight into the trajectory of recovery among a representative cohort of individuals hospitalized due to COVID-19.

Ensuring the Safety of Yellow Fever Vaccination in Travelers-The Experience at a Large U.S. Academic Medical Center in Colorado.

Background: Yellow fever (YF) virus has the potential to cause fatal outcomes among at-risk individuals visiting endemic areas. Vaccinating travelers who are at risk is necessary to prevent virus-related life-threatening complications. We lack data on the clinical features of persons seeking YF vaccination. We aim to describe the characteristics of a cohort of persons receiving the YF vaccine before travel. Methods: A retrospective analysis of 964 travelers receiving the YF vaccine (Stamaril®) from Oct 2016 to Jul 2019 was performed at the University of Colorado Hospital, U.S. Percentages, means, and standard deviations were calculated. A multivariate logistic regression model was built to evaluate the association between receiving YF vaccination less than 10 days before departure and visiting friends and relatives (VFR). Results: The average age of the subjects was 39 ± 18 years with a range of nine months to 83 years. Persons who were 60 years of age and older represented 17%. Women consisted of 52%, and most of the travelers were Caucasians (64%). Travelers reported traveling to Africa (57%) or South America (40%). The primary destinations for travelers overall were Kenya (19%), Uganda (11%), and Tanzania (11%) in Africa; and Peru (14%) and Brazil (13%) in South America. The most common reasons for travel included leisure (44%), VFR (18%), and mission trips (10%). Comorbidities included a history of hematologic disorders (4%), HIV infection (2%), and diabetes mellitus (3%). The average duration between vaccine administration and travel was 43 days. Those VFR were two times more likely to receive the YF vaccination <10 days before departure. Conclusions: Identifying the type of travel, itinerary, and underlying medical conditions allows providers to administer the YF vaccine to travelers safely. There is a need to identify strategies to improve the timing of YF vaccination among VFR travelers.

Association between maternal HIV disclosure and risk factors for perinatal transmission.

OBJECTIVE: To determine whether maternal disclosure of HIV serostatus is associated with uptake of perinatal HIV transmission prevention interventions. STUDY DESIGN: Retrospective cohort study of women living with HIV enrolled in a perinatal HIV clinic. Women who disclosed their HIV serostatus to sexual partner(s) prior to delivery were compared to non-disclosers. Multivariable logistic regression was performed. RESULTS: Of 209 women, 71.3% (N = 149) disclosed. Non-disclosers were more likely to attend <10 prenatal visits, demonstrated worse antiretroviral therapy adherence, required more time to achieve virologic suppression, and were less likely to have an undetectable viral load. On multivariable analyses, disclosure status did not remain associated with these factors. However, compared to non-disclosers, disclosers had lower odds of preterm delivery (OR: 0.43, 95% CI: 0.19-0.94) and greater odds of postpartum visit attendance (aOR: 5.10, 95% CI: 1.65-15.72). CONCLUSIONS: Non-disclosure of HIV status to sexual partner(s) during pregnancy may be a risk factor for preterm birth and poorer postpartum visit attendance.

High rates of hepatitis C virus (HCV) cure using direct-acting antivirals in HIV/HCV-coinfected patients: a real-world perspective.

OBJECTIVES: There are few data on the real-world experience of FDA-approved oral hepatitis C virus (HCV) direct-acting antiviral (DAA) drug combinations in HIV/HCV-coinfected patients. We evaluated the safety and efficacy of DAA therapies in a cohort of HIV/HCV patients in a large urban clinic in Chicago. METHODS: HIV/HCV-coinfected adults (≥18 years) enrolled in the Northwestern University Viral Hepatitis Registry between January 2013 and June 2015 were analysed. Treated patients received one of the following DAA combinations: sofosbuvir/ledipasvir, sofosbuvir/ribavirin, sofosbuvir/simeprevir or paritaprevir/ritonavir/ombitasvir/dasabuvir ±â€Šribavirin. The primary outcome was sustained virological response at 12 weeks after DAA completion (SVR12). RESULTS: Seventy-seven HIV/HCV patients were evaluated for DAA therapy. Most patients were male (62/77, 81%) and infected with HCV genotype 1 (67/77, 87%). Some 32/77 (42%) were cirrhotic and 29/77 (38%) had received prior treatment with an IFN-containing regimen. DAA therapy was more likely to be started in Caucasians than persons of other ethnicities (P = 0.01). The overall SVR12 rate was 92% in 52 patients who completed therapy and had follow-up by the end of the study: sofosbuvir/simeprevir, 32/33 (97%); sofosbuvir/ribavirin, 4/7 (57%); sofosbuvir/ledipasvir, 11/11 (100%); and paritaprevir/ritonavir/ombitasvir/dasabuvir, 1/1 (100%). Four patients relapsed after therapy with sofosbuvir/simeprevir (n = 1) or sofosbuvir/ribavirin (n = 3). Adverse events were uncommon and did not result in DAA treatment interruption or discontinuation. CONCLUSIONS: The HCV DAA combinations of sofosbuvir/ledipasvir and sofosbuvir/simeprevir were highly effective and well tolerated in this diverse population of HIV/HCV-coinfected patients, many of whom had advanced liver disease. HIV coinfection should not be considered a barrier to successful HCV treatment with DAAs.

Is maternal disclosure of HIV serostatus associated with a reduced risk of postpartum depression?

BACKGROUND: Patients with chronic diseases that include HIV infection are at increased risk of experiencing postpartum depression. In addition, social isolation has been associated with depression among women with HIV. Yet, it is unclear whether disclosure of HIV serostatus before the birth is associated with the risk of postpartum depression. OBJECTIVE: The purpose of this study was to determine whether maternal disclosure of her positive HIV serostatus before the delivery is associated with the risk of early postpartum depression. STUDY DESIGN: In this retrospective cohort study, women who received obstetric care in a specialty perinatal HIV clinic (2007-2014) were stratified by whether, before the delivery, they had disclosed their HIV serostatus to (1) their sexual partner(s) or (2) at least 1 family member aside from sexual partner(s). Postpartum depression was identified initially by a positive result on a validated depression screening tool (Patient Health Questionnaire-9 or Edinburgh Postnatal Depression Scale) at the 6-week postpartum visit and then confirmed by evaluation with a mental health professional. Postpartum depression rates were compared by disclosure status. Multivariable logistic regression was performed to identify whether disclosure to either sexual partner(s) or family members remained associated independently with postpartum depression after we controlled for potential confounders that included antenatal mental health disorders. RESULTS: Of the 215 women who received perinatal HIV care in this center and who had a documented disclosure status, 149 women (71.3%) had disclosed to their sexual partner(s), and 78 women (42.9%) had disclosed to at least 1 family member who was not a sexual partner. Although disclosure to sexual partner(s) was associated with a reduction in the proportion of women with postpartum depression (15.6% vs 25.5%), this difference did not reach statistical significance (P = .126) and remained statistically insignificant after we controlled for potential confounders (adjusted odds ratio, 0.47; 95% confidence interval, 0.15-1.41). In contrast, disclosure to family member(s) was associated with a decreased prevalence of postpartum depression (11.4% vs 24.7%; P = .03), and this difference persisted in multivariable regression (adjusted odds ratio, 0.35; 95% confidence interval, 0.13-0.95). CONCLUSION: In this cohort, maternal disclosure of HIV serostatus to family members (other than sexual partner[s]) was associated independently with a reduction in postpartum depression by more than one-half. Disclosure of HIV serostatus to a family member may be a marker for psychosocial well-being and enhanced support that affords protection against postpartum depression.

99Tc and Re incorporated into metal oxide polyoxometalates: oxidation state stability elucidated by electrochemistry and theory.

The radioactive element technetium-99 ((99)Tc, half-life = 2.1 × 10(5) years, ß(-) of 253 keV), is a major byproduct of (235)U fission in the nuclear fuel cycle. (99)Tc is also found in radioactive waste tanks and in the environment at National Lab sites and fuel reprocessing centers. Separation and storage of the long-lived (99)Tc in an appropriate and stable waste-form is an important issue that needs to be addressed. Considering metal oxide solid-state materials as potential storage matrixes for Tc, we are examining the redox speciation of Tc on the molecular level using polyoxometalates (POMs) as models. In this study we investigate the electrochemistry of Tc complexes of the monovacant Wells-Dawson isomers, α(1)-P(2)W(17)O(61)(10-) (α1) and α(2)-P(2)W(17)O(61)(10-) (α2) to identify features of metal oxide materials that can stabilize the immobile Tc(IV) oxidation state accessed from the synthesized Tc(V)O species and to interrogate other possible oxidation states available to Tc within these materials. The experimental results are consistent with density functional theory (DFT) calculations. Electrochemistry of K(7-n)H(n)[Tc(V)O(α(1)-P(2)W(17)O(61))] (Tc(V)O-α1), K(7-n)H(n)[Tc(V)O(α(2)-P(2)W(17)O(61))] (Tc(V)O-α2) and their rhenium analogues as a function of pH show that the Tc-containing derivatives are always more readily reduced than their Re analogues. Both Tc and Re are reduced more readily in the lacunary α1 site as compared to the α2 site. The DFT calculations elucidate that the highest oxidation state attainable for Re is VII while, under the same electrochemistry conditions, the highest oxidation state for Tc is VI. The M(V)→ M(IV) reduction processes for Tc(V)O-α1 are not pH dependent or only slightly pH dependent suggesting that protonation does not accompany reduction of this species unlike the M(V)O-α2 (M = (99)Tc, Re) and Re(V)O-α1 where M(V/IV) reduction process must occur hand in hand with protonation of the terminal M═O to make the π*(M═O) orbitals accessible to the addition of electrons. This result is consistent with previous extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) data that reveal that the Tc(V) is "pulled" into the -α1 framework and that may facilitate the reduction of Tc(V)O-α1 and stabilize lower Tc oxidation states. This study highlights the inequivalency of the two sites, and their impact on the chemical properties of the Tc substituted in these positions.

Photoreduction of 99Tc pertechnetate by nanometer-sized metal oxides: new strategies for formation and sequestration of low-valent technetium.

Technetium-99 ((99)Tc) (ß(-)(max): 293.7 keV; t(1/2): 2.1 × 10(5) years) is a byproduct of uranium-235 fission and comprises a large component of radioactive waste. Under aerobic conditions and in a neutral-basic environment, the pertechnetate anion ((99)TcO(4)(-)) is stable. (99)TcO(4)(-) is very soluble, migrates easily through the environment and does not sorb well onto mineral surfaces, soils, or sediments. This study moves forward a new strategy for the reduction of (99)TcO(4)(-) and the chemical incorporation of the reduced (99)Tc into a metal oxide material. This strategy employs a single material, a polyoxometalate (POM), α(2)-[P(2)W(17)O(61)](10-), that can be photoactivated in the presence of 2-propanol to transfer electrons to (99)TcO(4)(-) and incorporate the reduced (99)Tc covalently into the α(2)-framework to form the (99)Tc(V)O species, (99)Tc(V)O(α(2)-P(2)W(17)O(61))(7-). This occurs via the formation of an intermediate species that slowly converts to (99)Tc(V)O(α(2)-P(2)W(17)O(61))(7-). Extended X-ray absorption fine structure and X-ray absorption near-edge spectroscopy analysis suggests that the intermediate consists of a (99)Tc(IV) α(2)- species where the (99)Tc is likely bound to two of the four W-O oxygen atoms in the α(2)-[P(2)W(17)O(61)](10-) defect. This intermediate then oxidizes and converts to the (99)Tc(V)O(α(2)-P(2)W(17)O(61))(7-) product. The reduction and incorporation of (99)TcO(4)(-) was accomplished in a "one pot" reaction using both sunlight and UV irradiation and monitored as a function of time using multinuclear nuclear magnetic resonance and radio thin-layer chromatography. The process was further probed by the "step-wise" generation of reduced α(2)-P(2)W(17)O(61)(12-) through bulk electrolysis followed by the addition of (99)TcO(4)(-). The reduction and incorporation of ReO(4)(-), as a nonradioactive surrogate for (99)Tc, does not proceed through the intermediate species, and Re(V)O is incorporated quickly into the α(2)-[P(2)W(17)O(61)](10-) defect. These observations are consistent with the periodic trends of (99)Tc and Re. Specifically, (99)Tc is more easily reduced compared to Re. In addition to serving as models for metal oxides, POMs may also provide a suitable platform to study the molecular level dynamics and the mechanisms of the reduction and incorporation of (99)Tc into a material.

Synthesis, structure elucidation, and redox properties of 99Tc complexes of lacunary Wells-Dawson polyoxometalates: insights into molecular 99Tc-metal oxide interactions.

The isotope (99)Tc (ß(max), 293.7; half-life, 2.1 × 10(5) years) is an abundant product of uranium-235 fission in nuclear reactors and is present throughout the radioactive waste stored in underground tanks at the Hanford and Savannah River sites. Understanding and controlling the extensive redox chemistry of (99)Tc is important in identifying tunable strategies to separate (99)Tc from spent fuel and from waste tanks and, once separated, to identify and develop an appropriately stable waste form for (99)Tc. Polyoxometalates (POMs), nanometer-sized models for metal oxide solid-state materials, are used in this study to provide a molecular level understanding of the speciation and redox chemistry of incorporated (99)Tc. In this study, (99)Tc complexes of the (α(2)-P(2)W(17)O(61))(10-) and (α(1)-P(2)W(17)O(61))(10-) isomers were prepared. Ethylene glycol was used as a "transfer ligand" to minimize the formation of TcO(2)·xH(2)O. The solution structures, formulations, and purity of Tc(V)O(α(1)/α(2)-P(2)W(17)O(61))(7-) were determined by multinuclear NMR. X-ray absorption spectroscopy of the complexes is in agreement with the formulation and structures determined from (31)P and (183)W NMR. Preliminary electrochemistry results are consistent with the EXAFS results, showing a facile reduction of the Tc(V)O(α(1)-P(2)W(17)O(61))(7-) species compared to the Tc(V)O(α(2)-P(2)W(17)O(61))(7-) analog. The α(1) defect is unique in that a basic oxygen atom is positioned toward the α(1) site, and the Tc(V)O center appears to form a dative metal-metal bond with a framework W site. These attributes may lead to the assistance of protonation events that facilitate reduction. Electrochemistry comparison shows that the Re(V) analogs are about 200 mV more difficult to reduce in accordance with periodic trends.