Experimental and theoretical studies of the LiBH4-LiI phase diagram

The hexagonal structure of LiBH4 at room temperature can be stabilised by substituting the BH4- anion with I-, leading to high Li-ion conductive materials. A thermodynamic description of the pseudo-binary LiBH4-LiI system is presented. The system has been explored investigating several compositions, synthetized by ball milling and subsequently annealed. X-ray diffraction and Differential Scanning Calorimetry have been exploited to determine structural and thermodynamic features of various samples. The monophasic zone of the hexagonal Li(BH4)1-x(I)x solid solution has been experimentally defined equal to 0.18 ≤ x ≤ 0.60 at 25 °C. In order to establish the formation of the hexagonal solid solution, the enthalpy of mixing was experimentally determined, converging to a value of 1800 ± 410 J mol-1. Additionally, the enthalpy of melting was acquired for samples that differ in molar fraction. By merging experimental results, literature data and ab initio theoretical calculations, the pseudo-binary LiBH4-LiI phase diagram has been assessed and evaluated across all compositions and temperature ranges by applying the CALPHAD method.

Anomalous Impact of Mechanochemical Treatment on the Na-ion Conductivity of Sodium Closo-Carbadodecaborate Probed by X-Ray Raman Scattering Spectroscopy

Solid-state sodium ion conductors are crucial for the next generation of all-solid-state sodium batteries with high capacity, low cost, and improved safety. Sodium closo-carbadodecaborate (NaCB11 H12 ) is an attractive Na-ion conductor owing to its high thermal, electrochemical, and interfacial stability. Mechanical milling has recently been shown to increase conductivity by five orders of magnitude at room temperature, making it appealing for application in all-solid-state sodium batteries. Intriguingly, milling longer than 2 h led to a significant decrease in conductivity. In this study, X-ray Raman scattering (XRS) spectroscopy is used to probe the origin of the anomalous impact of mechanical treatment on the ionic conductivity of NaCB11 H12 . The B, C, and Na K-edge XRS spectra are successfully measured for the first time, and ab initio calculations are employed to interpret the results. The experimental and computational results reveal that the decrease in ionic conductivity upon prolonged milling is due to the increased proximity of Na to the CB11 H12 cage, caused by severe distortion of the long-range structure. Overall, this work demonstrates how the XRS technique, allowing investigation of low Z elements such as C and B in the bulk, can be used to acquire valuable information on the electronic structure of solid electrolytes and battery materials in general.

Thermal Polymorphism in CsCB11H12

Thermal polymorphism in the alkali-metal salts incorporating the icosohedral monocarba-hydridoborate anion, CB₁₁H₁₂^-, results in intriguing dynamical properties leading to superionic conductivity for the lightest alkali-metal analogues, LiCB₁₁H₁₂ and NaCB₁₁H₁₂. As such, these two have been the focus of most recent CB₁₁H₁₂^- related studies, with less attention paid to the heavier alkali-metal salts, such as CsCB₁₁H₁₂. Nonetheless, it is of fundamental importance to compare the nature of the structural arrangements and interactions across the entire alkali-metal series. Thermal polymorphism in CsCB₁₁H₁₂ was investigated using a combination of techniques: X-ray powder diffraction; differential scanning calorimetry; Raman, infrared, and neutron spectroscopies; and ab initio calculations. The unexpected temperature-dependent structural behavior of anhydrous CsCB₁₁H₁₂ can be potentially justified assuming the existence of two polymorphs with similar free energies at room temperature: (i) a previously reported, ordered R3 polymorph stabilized upon drying and transforming first to R3c symmetry near 313 K and then to a similarly packed but disordered I43d polymorph near 353 K and (ii) a disordered Fm3 polymorph that initially appears from the disordered I43d polymorph near 513 K along with another disordered high-temperature P6₃mc polymorph. Quasielastic neutron scattering results indicate that the CB₁₁H₁₂^- anions in the disordered phase at 560 K are undergoing isotropic rotational diffusion, with a jump correlation frequency [1.19(9) × 10¹¹ s^-1] in line with those for the lighter-metal analogues.

Enhanced Room-Temperature Ionic Conductivity of NaCB11H12 via High-Energy Mechanical Milling

The body-centered cubic (bcc) polymorph of NaCB₁₁H₁₂ has been stabilized at room temperature by high-energy mechanical milling. Temperature-dependent electrochemical impedance spectroscopy shows an optimum at 45-min milling time, leading to an rt conductivity of 4 mS cm^-1. Mechanical milling suppresses an order-disorder phase transition in the investigated temperature range. Nevertheless, two main regimes can be identified, with two clearly distinct activation energies. Powder X-ray diffraction and ²³Na solid-state NMR reveal two different Na⁺ environments, which are partially occupied, in the bcc polymorph. The increased number of available sodium sites w.r.t. ccp polymorph raises the configurational entropy of the bcc phase, contributing to a higher ionic conductivity. Mechanical treatment does not alter the oxidative stability of NaCB₁₁H₁₂. Electrochemical test on a symmetric cell (Na|NaCB₁₁H₁₂|Na) without control of the stack pressure provides a critical current density of 0.12 mA cm^-2, able to fully charge/discharge a 120 mA h g^-1 specific capacity positive electrode at the rate of C/2.

Room-Temperature Solid-State Lithium-Ion Battery Using a LiBH4-MgO Composite Electrolyte

LiBH₄ has been widely studied as a solid-state electrolyte in Li-ion batteries working at 120 °C due to the low ionic conductivity at room temperature. In this work, by mixing with MgO, the Li-ion conductivity of LiBH₄ has been improved. The optimum composition of the mixture is 53 v/v % of MgO, showing a Li-ion conductivity of 2.86 × 10^-4 S cm^-1 at 20 °C. The formation of the composite does not affect the electrochemical stability window, which is similar to that of pure LiBH₄ (about 2.2 V vs Li⁺/Li). The mixture has been incorporated as the electrolyte in a TiS₂/Li all-solid-state Li-ion battery. A test at room temperature showed that only five cycles already resulted in cell failure. On the other hand, it was possible to form a stable solid electrolyte interphase by applying several charge/discharge cycles at 60 °C. Afterward, the battery worked at room temperature for up to 30 cycles with a capacity retention of about 80%.

Combined DFT and geometrical–topological analysis of Li-ion conductivity in complex hydrides

This work suggests that topological analysis can adequately explain the ion conductivity in complex hydrides.

Incidence of Prostate Cancer in Sicily: Results of a Multicenter Case-Findings Protocol

OBJECTIVE

To establish the incidence of prostate cancer (PCa) in Sicily in patients who entered an early detection protocol.

METHODS

From February 2002 to February 2004, 16,298 subjects aged 40-75 entered the protocol. Patients with suspicious DRE, PSA>10 ng/ml, PSA<or=2.5 ng/ml, from 2.6 to 4 ng/ml or from 4.1 to 10 ng/ml with F/T PSA of <or=15%, <or=20% and <or=25% respectively underwent needle biopsy according to an extensive protocol.

RESULTS

3266 patients were eligible for biopsy; PSA was <or=4 in 12.7% and <or=10 ng/ml in 63.9% of patients. A PCa was found in 1171 cases (36.9%) with a relationship between PCa incidence and PSA and age respectively (chi2-test, p<0.0001); 51.8% of patients with PCa had a PSA<10 and 8.8% a PSA<4 ng/ml; 49% were clinically staged as T1c. The estimated odds ratios for each age group showed increased risk for PCa in the fourth decade with PSA between 2.6 and 4 ng/ml (12.5 times higher) and in the fifth decade with PSA between 4.1 and 10 ng/ml (6.2 times higher).

CONCLUSIONS

Age and serum PSA levels are the major risk factors for PCa. On their basis it is possible to modulate the most suitable timing for early diagnosis in individual patients.

The mutational spectrum of human malignant autosomal recessive osteopetrosis

Human malignant infantile osteopetrosis (arOP; MIM 259700) is a genetically heterogeneous autosomal recessive disorder of bone metabolism, which, if untreated, has a fatal outcome. Our group, as well as others, have recently identified mutations in the ATP6i (TCIRG1) gene, encoding the a3 subunit of the vacuolar proton pump, which mediates the acidification of the bone/osteoclast interface, are responsible for a subset of this condition. By sequencing the ATP6i gene in arOP patients from 44 unrelated families with a worldwide distribution we have now established that ATP6i mutations are responsible for approximately 50% of patients affected by this disease. The vast majority of these mutations (40 out of 42 alleles, including seven deletions, two insertions, 10 nonsense substitutions and 21 mutations in splice sites) are predicted to cause severe abnormalities in the protein product and are likely to represent null alleles. In addition, we have also analysed nine unrelated arOP patients from Costa Rica, where this disease is apparently much more frequent than elsewhere. All nine Costa Rican patients bore either or both of two missense mutations (G405R and R444L) in amino acid residues which are evolutionarily conserved from yeast to humans. The identification of ATP6i gene mutations in two families allowed us for the first time to perform prenatal diagnosis: both fetuses were predicted not to be affected and two healthy babies were born. This study contributes to the determination of genetic heterogeneity of arOP and allows further delineation of the other genetic defects causing this severe condition.

The use of citalopram in an integrated approach to the treatment of eating disorders: an open study

This study investigated the efficacy and safety of citalopram in the treatment of eating disorders. Eighteen female patients gave their informed consent to enrollment in the trial: twelve with bulimia nervosa, six with anorexia nervosa according to the DSM IV criteria. They received individual systemic psychotherapy and took 20 mg/day citalopram for 8 weeks. At the beginning and end of the trial, their BMI, body fat and lean mass were checked and they completed the Eating Disorder Inventory and Binge Scale. The results showed that citalopram is effective and safe in the treatment of eating disorders: binge eating episodes and mean scores in three EDI subscales (bulimia, ineffectiveness and interoceptive awareness) significantly decreased in the bulimic patients, and mean scores in the EDI body dissatisfaction subscale significantly decreased in the anorexic patients.