Hydrogen sorption in the LiH-LiF-MgB2 system

A composite material in the LiH-LiF-MgB2 system has been synthesized by high-energy ball milling. Some peaks in addition to that of the binary 2LiH-MgB2 and 2LiF-MgB2 systems are observed for the composite material by high-pressure differential scanning calorimetry (HP-DSC), indicating the formation of intermediate phases. In situ synchrotron radiation powder X-ray diffraction (SR-PXD) performed at 60 bar of H-2 and 390 degrees C shows a superposition of both reaction pathways that are typical for 2LiH-MgB2 and 2LiF-MgB2. After hydrogen absorption of the LiH-LiF-MgB2 composite the vibrational modes of LiBH4 were observed by attenuated total reflection infrared (ATR-IR) spectroscopy. The F-19 MAS NMR spectrum of the LiF-LiBH4 sample after heat treatment in hydrogen is strongly dominated by the centerband and spinning sidebands from LiF; in addition, a low-intensity resonance, very similar to that of [BF4](-) ion, is identified

Nucleation and growth of Au and Au-Pd nanoparticles at the beginning of electrochemical deposition

Gold and gold-palladium nanodeposits were obtained by pulse electrolysis in dimethylformamide with 4 x 10(-3) M HAuCl4 and in dimethyl sulfoxide solution with a mixture of 4 x 10(-3) M HAuCl4 and 4 x 10(-3) M PdCl2, respectively. Isolated gold nanoparticles of about 15 nm in diameter were found by SEM observation after 6 ms of electrochemical deposition. Three pulse and pause periods with duration of 6 ms and 300 ms respectively led to an increase in the particle size approximately two times. In case of gold-palladium deposition, no particles were detected after 10 electrochemical cycles while after 50 cycles 10-35 nm nanoparticles were found. Detailed SEM analysis of electrode surface suggested that at the beginning of electrochemical deposition the growth of gold/nucleation of gold-palladium NPs is a preference for mono-Au/bimetallic Au-Pd system

Hydrogenation Study of NaF/NaH/MgB₂ Reactive Hydride Composites

The hydrogenation of NaF/9NaH + 5MgB₂ and NaF/2NaH + 1.5MgB₂ reactive hydride composites (RHC) was studied by volumetric titration (kinetics and PCI curves), in situ synchrotron radiation powder X-ray diffraction (SR-PXD), high-pressure differential scanning calorimetry (HP-DSC), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM). A hydrogen uptake between 4.1 and 4.8 wt % was observed when the H₂ pressure was in the range between 25 and 50 bar, and the temperature was kept constant at 325 °C. PCI curves indicate a hydrogenation equilibrium pressure of 2 and 8 bar at 325 °C for NaF/9NaH + 5MgB₂ and NaF/2NaH + 1.5MgB₂, respectively. Synchrotron radiation powder X-ray diffraction revealed the formation of solid solutions of NaF–NaH after milling and a change in the reaction pathway compared to a reported nondoped 2NaH + MgB₂ reactive hydride composite. Formation of the stable side-product NaMgH₂F was found as a drawback for hydrogen storage capacity and reversibility. FT-IR indicates no hydrogen to fluorine substitution in the NaBH₄ product

Comparison of CMV ELISPOT and CMV Quantiferon\u2122 interferon-\u3b3 releasing assays in assessing risk of CMV infection in kidney transplant recipients.

Background.Assessing the CMV specific cell-mediated immunity (CMI) represents an appealing strategy to detect transplant recipients at risk of infection. In this study we compared two interferon gamma-releasing assays (IGRAs), CMV Quantiferon and CMV ELISPOT, in predicting protective CMV specific T-cell responses.Methods.221 Quantiferon and ELISPOT tests were conducted on 120 adult KTR (including 100 R+ and 20 D+/R-). As control cohort 39 adult healthy subjects (including 33 CMV seropositive and 6 CMV seronegative) were enrolled. CMV IgG serology was used as reference for both tests.Results.In CMV seropositive individuals, ELISPOT and Quantiferon provided 46% concordance with serology, 12% discordance, 18% disagreement between ELISPOT or Quantiferon with serology and 24% grey areas when one or both tests resulted weak positive. None of CMV seronegative subjects showed detectable responses in ELISPOT and Quantiferon. In transplant recipients, both ELISPOT and Quantiferon positively correlated with each other and negatively correlated to CMV DNAemia in a significant way (p-value <0.05). During the antiviral prophylaxis, all 20 D+/R- KTRs examined displayed undetectable Quantiferon and ELISPOT and there was no evidence of CMV seroconversion. The ROC statistical analysis revealed similar specificity and sensitivity in predicting detectable viremia (AUC 0.66 and 0.62 for Quantiferon and ELISPOT respectively). ELISPOT and Quantiferon values above 150 spots/200000 PBMCs and <1-6 IU IFN-g were associated with protection from CMV infection (OR 5 and 8.75 respectively).Conclusion.In transplants both tests displayed similar ability in predicting CMV infection. Both ELISPOT and Quantiferon require several ameliorations to avoid false nagative results

Diagnostic utility of human cytomegalovirus-specific T-cell response monitoring in predicting viremia in pediatric allogeneic stem-cell transplant patients

BACKGROUND: Several studies proved that virus-specific T-cells play a pivotal role in controlling cytomegalovirus (CMV) infection in adult allogeneic hematopoietic stem-cell transplant (HSCT) patients. Fewer data are available in pediatric HSCT settings, when immature and inexperienced immune system may affect antiviral immune reconstitution. METHODS: We analyzed prospectively the CMV-specific T-cell reconstitution in a cohort of 31 pediatric allogeneic HSCT recipients at 30, 60, 90, 120, 180, and 360 days after HSCT. RESULTS: Depending on donor-recipient CMV serostatus, we observed distinct patterns and kinetics of CMV-specific T-cell immune reconstitution: during the early time-points, patients displayed a severe reduction in CMV-specific T-cell recovery in both CMV seropositive donor (D+) group and CMV seronegative donor (D-) on CMV seropositive recipients (R+). From day 90 onward, statistical significant differences in the profile of T-cell immune reconstitution emerged between D+ and D-. The pattern of immune reconstitution was characterized by heterogeneous kinetics and efficiencies: we report cases of: (1) spontaneous antiviral T-cell recovery with no previous viremia, (2) immune T-cell recovery anticipated by CMV viremia, and (3) no T-cell immune reconstitution despite previous viremia episodes. CONCLUSIONS: Given the heterogeneous scenarios of antiviral T-cell immune recovery in pediatric allogeneic HSCT, we conclude that the evaluation of the antiviral immune reconstitution is a promising and appealing system for identifying patients at higher risk of CMV infection. The use of interferon-\u3b3 ELISPOT test is a valid tool for immunological monitoring and predicting CMV viremia in pediatric HSCT