Facile in situ growth of ZnO nanosheets standing on Ni foam as binder-free anodes for lithium ion batteries

ZnO has attracted increasing attention as an anode for lithium ion batteries. However, the application of such anode materials remains restricted by their poor conductivity and large volume changes during the charge/discharge process. Herein, we report a simple hydrothermal method to synthesize ZnO nanosheets with a large surface area standing on a Ni foam framework, which is applied as a binder-free anode for lithium ion batteries. ZnO nanosheets were grown in situ on Ni foam, resulting in enhanced conductivity and enough space to buffer the volume changes of the battery. The ZnO nanosheets@Ni foam anode showed a high specific capacity (1507 mA h g⁻¹ at 0.2 A g⁻¹), good capacity retention (1292 mA h g⁻¹ after 45 cycles), and superior rate capacity, which are better than those of ZnO nanomaterial-based anodes reported previously. Moreover, other transition metal oxides, such as Fe₂O₃ and NiO were also formed in situ on Ni foam with perfect standing nanosheets structures by this hydrothermal method, confirming the universality and efficiency of this synthetic route.

ZnO nanosheets@Ni foam anode showed a high specific capacity, good capacity retention and superior rate capacity. Moreover, other transition metal oxides were also similarly formed on Ni foam, confirming the universality and efficiency of the synthetic route.     

A DFT prediction of two-dimensional MB3 (M = V,Nb, and Ta) monolayers as excellent anode materials for lithium-ion batteries

Transition metal borides (MBenes) have recently drawn great attention due to their excellent electrochemical performance as anode materials for lithium-ion batteries (LIBs). Using the structural search code and first-principles calculations, we identify a group of the MB₃ monolayers (M = V, Nb and Ta) consisting of multiple MB₄ units interpenetrating with each other. The MB₃ monolayers with non-chemically active surfaces are stable and have metal-like conduction. As the anode materials for Li-ion storage, the low diffusion barrier, high theoretical capacity, and suitable average open circuit voltage indicate that the MB₃ monolayers have excellent electrochemical performance, due to the B₃ chain exposed on the surface improving the Li atoms'' direct adsorption. In addition, the adsorbed Li-ions are in an ordered hierarchical arrangement and the substrate structure remains intact at room temperature, which ensures excellent cycling performance. This work provides a novel idea for designing high-performance anode materials for LIBs.

The boron-exposed MB₃ monolayers (M = V, Nb and Ta) formed by interpenetrating MB₄ units have high Li-ion capacities.     

Surface adsorption of nitrosourea on pristine and doped (Al,Ga and In) boron nitride nanosheets as anticancer drug carriers: the DFT and COSMO insights

To minimize the side effects of chemotherapeutic drugs and enhance the effectiveness of cancer treatment, it is necessary to find a suitable drug delivery carrier for anticancer drugs. Recently nanomaterials are extensively being studied as drug vehicles and transport drugs in tumor cells. Using DFT calculations, the adsorption behavior with electronic sensitivity and reactivity of pristine and doped (Al, Ga and In)-BNNS towards the nitrosourea (NU) drug has been investigated in gas as well as water media. Our calculations showed that the NU drug is physically adsorbed on the pristine BNNS with −0.49 and −0.26 eV by transferring little amount of charge of about 0.033e and 0.046e in gas and water media in the most stable complex. But after replacing one of the central B atoms with an Al or Ga or In atom, the sensitivity of the doped BNNS remarkably enhances towards the NU drug molecules. The NU drug prefers to be chemically adsorbed on the BN(Al)NS, BN(Ga)NS and BN(In)NS by −1.28, −1.58 and −3.06 eV in the gas phase and −1.34, −1.23 and −3.65 eV in water media in the most stable complexes respectively. The large destabilization of LUMO energies after the adsorption of the NU drug on the BN(Al)NS, BN(Ga)NS and BN(In)NS significantly reduces their E_g from 4.37 to 0.69, 4.37 to 1.04 and 4.33 to 0.66 eV in the S1 complex respectively. The reduction of E_g of doped BNNS by the NU drug greatly enhances the electrical conductivity which can be converted to an electrical signal. Therefore, this doped BNNS can be used as a fascinating electronic sensor for the detection of NU drug molecules. Furthermore the work function of the doped BNNS was largely affected by the NU drug adsorption about 47.3%, 39.3% and 40.4% in the gas phase and 41.3%, 36.6% and 31.6% in water media in the S1 complex of NU/BN(Al)NS, NU/BN(Ga)NS and NU/BN(In)NS respectively. Thus, the doped BNNS may be used as a Ф type sensor for NU drug molecules.

Doped (Al, Ga and In)-BNNS can be used as fascinating drug carriers for the NU drug.     

Alginic acid aquagel as a template and carbon source in the synthesis of Li4Ti5O12/C nanocomposites for application as anodes in Li-ion batteries

We report here a simple process for the synthesis of Li₄Ti₅O₁₂(LTO)/carbon nanocomposites by a one-pot method using an alginic acid aquagel as a template and carbon source, and lithium acetate and TiO₂ nanoparticles as precursors to the LTO phase. The carbon content can be tuned by adjusting the relative amount of alginic acid. The obtained materials consist of nanosized primary particles of LTO (30 nm) forming micron-sized aggregates covered by well-dispersed carbon (from 3 to 19 wt%). The homogeneous dispersion of carbon over the particles improves the electrochemical performance of LTO electrodes such as rate capability (>95 mA h g⁻¹ at 40C) and cycling performance (>98% of retention after 500 cycles at 5C), even with only 3% of carbon black additive in the electrode formulation. With a simple and easily up-scalable synthesis, the LTO/carbon nanocomposites of this study are promising candidates as anode materials for practical application in lithium-ion batteries.

We report here a simple process for the synthesis of Li₄Ti₅O₁₂(LTO)/carbon nanocomposites by a one-pot method using an alginic acid aquagel as a template and carbon source, and lithium acetate and TiO₂ nanoparticles as precursors to the LTO phase.     

Ge nanowires on top of a Ge substrate for applications in anodes of Li and Na ion batteries: a first-principles study

In this study, density functional theory (DFT) was used to research the adsorption and diffusion features of Li and Na on Ge nanowires on top of a Ge substrate. The adsorption energies at different positions are 0.71–1.28 eV for Na and −2.96–−2.13 eV for Li. The adsorption energies can be further reduced by surface modification with one or two P atoms. In particular, the sidewall of the Ge nanowire modified by two P atoms is most favorable to adsorb Li/Na. In addition, we used the nudged elastic band (NEB) method to study the diffusion pathways of Li/Na on the sidewall of Ge NW and the Ge substrate and computed their energy barriers. When Li or Na diffuses across the Ge NW, the energy barrier is 0.65 or 0.79 eV, indicating that the Ge NW can be applied to anodes in lithium and sodium ion batteries. Finally, the insertion of more lithium and sodium atoms into the Ge NW would cause volume expansion and the average length of Ge–Ge bonds to increase. This work will contribute to studying the adsorption and diffusion of Li and Na on nanowires with a substrate and the volume expansion caused by the insertion of Li/Na into the nanowires. Additionally, it provides guidance for designing Ge anodes for sodium ion batteries.

(a) The energy curves along the D–E pathway for the Li/Na diffusion; the side-view of the trajectories of (b) Li and (c) Na diffusion across the Ge NW.     

Crystal structure of vyacheslavite,U(PO4)(OH), solved from natural nanocrystal: a precession electron diffraction tomography (PEDT) study and DFT calculations

The crystal structure of the U(iv)-phosphate mineral vyacheslavite has been solved from precession electron diffraction tomography (PEDT) data from the natural nano-crystal and further refined using density-functional theory (DFT) calculations. Vyacheslavite is orthorhombic, with the space group Cmca, with a ≈ 6.96 Å, b ≈ 9.07 Å and c ≈ 12.27 Å, V ≈ 775 ų (obtained from PEDT data at 100 K), Z = 8. Its structure is a complex heteropolyhedral framework consisting of sheets of UO₇(OH) and PO₄ polyhedra, running parallel to (001), interconnected by additional PO₄ polyhedra. There is an (OH) group associated with the U(iv) polyhedron. The question of H₂O presence within the small cavities of the framework has been addressed by the DFT calculations, which have proved that vyacheslavite does not contain any significant amount of H₂O at room temperature.

The crystal structure of the U(iv)-phosphate mineral vyacheslavite has been solved from precession electron diffraction tomography (PEDT) data from the natural nano-crystal and further refined using density-functional theory (DFT) calculations.     

Exploring the potentials of Ti3N2 and Ti3N2X2 (X = O,F, OH) monolayers as anodes for Li or non-Li ion batteries from first-principles calculations

The electronic properties and different metal ion (Li, Na, Mg) storage capabilities of the two-dimensional (2D) Ti₃N₂ monolayer and its Ti₃N₂X₂ derivatives (X = O, F, and OH) as anode materials in rechargeable batteries have been systematically investigated by density functional theory (DFT) computations. Results show that the bare Ti₃N₂ and terminated monolayers in their most stable configurations are all metallic before and after metal ion adsorption. The relatively low diffusion barriers on the bare Ti₃N₂ monolayer were also confirmed, which implies faster charge and discharge rates. With respect to storage capacity, a high theoretical capacity of 1874 mA h g⁻¹ can be provided by the Ti₃N₂ monolayer for Mg due to its multilayer adsorption and two-electron reaction. The existence of functional groups is proven to be unfavorable to metal ion migration and will decrease the corresponding storage capacities, which should be avoided in experiments as much as possible. These excellent performances suggest that the bare Ti₃N₂ is a promising anode material for Li-ion or non-Li-ion batteries.

The electronic properties and metal ion (Li, Na, Mg) storage capabilities of the two-dimensional Ti₃N₂ monolayer and its Ti₃N₂X₂ derivatives (X = O, F, OH) as anode materials in rechargeable batteries are investigated by DFT computations.     

Comprehensive study on the degradation of ochratoxin A in water by spectroscopic techniques and DFT calculations

Ochratoxin A (OTA) is one of the most important dietary risk factors and is classified as a possible carcinogen to humans. Assessing the conditions to remove it from foodstuffs in a simple and effective way is of the utmost importance. OTA behaviour in water in the pH range 1.0–12.5 was elucidated to investigate the conditions for irreversible toxicity inactivation of OTA. The results indicate that four forms, from neutral to trianionic, intervene depending on the pH. pK_a1,2 were rigorously established by independent spectroscopic techniques to overcome the scarcity of literature. Then, Density Functional Theory (DFT) calculations were used to determine the most probable degradation mechanism and this was confirmed by fluorescence spectroscopy. At pH 12.5, hydrolyzation of the lactone ring starts in less than one hour, but only after two hours does the degradation process lead to fragmentation. After one week this process is not yet completed. The reaction products occurring upon re-acidification were also investigated. OTA degradation is still reversible if acidic conditions are promptly restored, yielding again a hazardous molecule. However, degradation becomes irreversible after fragmentation. This finding suggests proceeding with due caution if a base is exploited to remove the toxin.

The OTA degradation process becomes irreversible only if, following hydrolyzation of the lactone ring, the molecule fragments.     

Cleaved protein S (PS), total PS,free PS,and activated protein C cofactor activity as risk factors for venous thromboembolism

BACKGROUND: Although hereditary protein S (PS) deficiency is clearly associated with venous thromboembolism (VTE), the importance of low PS concentrations as a risk factor for VTE in other patients is still a matter of debate. To clarify this issue, we designed a case-control study to evaluate the role of different molecular forms of plasma PS. METHODS: We quantified plasma cleaved, total, and free PS and activated protein C (APC) cofactor activity in 87 VTE patients and 174 controls matched for age, sex, and hormonal treatment. Free PS was measured by ELISA or by enzyme-linked ligand sorbent assay (ELSA). Cleaved and total PS were measured by ELISA. RESULTS: In controls, the mean (SD) concentration of circulating cleaved PS was 39 (14) nmol/L, corresponding to 10% (3.5%) of total PS. Concentrations of cleaved PS and total PS were not significantly different in patients with VTE compared with controls. However, in our population, low free PS measured by ELISA or ELSA, as well as APC cofactor activity values were significantly associated with VTE with odds ratios (95% confidence intervals) of 2.9 (1.3-6.3), 2.5 (1.1-5.6), and 2.9 (1.3-6.4), respectively, in multivariate analyses. CONCLUSION: Phenotypic low PS detected by APC cofactor activity assay or by an assay specific for free PS should be considered a risk factor for VTE.     

Role of complement receptors 1 and 2 (CD35 and CD21), C3, C4, and C5 in survival by mice of Staphylococcus aureus bacteremia

Complement-mediated opsonization and phagocytosis of encapsulated serotype 5 Staphylococcus aureus are essential to host defense. We describe the effects of complement depletion and deficiencies of C4, C5, and complement receptors 1 and 2 on mouse survival after intravenous exposure to S aureus. Depletion of complement proteins in C57BL/6 mice with the use of cobra-venom factor decreased survival compared with that of controls after the induction of bacteremia with mucoid (90% mortality), encapsulated (73%), and unencapsulated (59%) S aureus strains. In this model complement is even more important in the control of infection with encapsulated S aureus (80% of clinical isolates) than in the control of infection by unencapsulated strains. C4-deficient mice demonstrated similar mortality from bacteremia caused by encapsulated S aureus compared with controls, suggesting that in the unimmunized animal the alternative complement pathway contributes more to control of bacteremia caused by encapsulated S aureus than the classical complement pathway or mannan-binding lectin pathway. C5-deficient mice (B10.D2-H2(d) H2-T18(c) Hc(0)/oSnJ) showed similar mortality when subjected to bacteremia caused by encapsulated S aureus compared with C5-sufficient (B10.D2-Hc(1) H2(d) H2-T18(c)/nSnJ) mice, suggesting that in this model the anaphylatoxin C5a and the late complement cascade are not critical to survival of bacteremia induced with the use of these strains. However, C5-deficient mice depleted of C3 with the use of cobra-venom factor had 60% decreased survival compared with untreated C5-deficient mice with bacteremia induced by encapsulated S aureus, suggesting that in this model C3 is more critical than C5 in controlling S aureus bacteremia. Complement receptor 1 (CD35) is the primary receptor for the opsonin C3b. Mice deficient in CD35/CD21 showed a 67% decrease in survival compared with normal mice, suggesting that CD35/CD21 is of major importance in the control of S aureus-induced bacteremia.     

Relationship between vitamin status (A, B1, B2, B6, and C), clinical features and nutritional habits in a population of old people (author's transl)

112 patients in a medical ward were examined clinically and biochemically with regard to their vitamin status (plasma vitamin A, plasma vitamin C, blood glutathione reductase, vitamin B1, vitamin B2, N-methyl nicotinic acid amide and pyridoxic acid excretion). The nutritional habits were assessed by means of a questionnaire. The results of these two examinations were correlated with the clinical findings. The assessment of the vitamin B2 status showed a deficiency in 8 cases and a marginal vitamin B2 supply in a further 4 cases. The thiamine intake was insufficient in 43 cases and marginal in 42 cases. The biochemical assessment of vitamins C, B1 and PP indicated a deficiency of these vitamins. Dermatological signs pointed to a deficiency of vitamins A and B2. There was a significant correlation between the plasma vitamin A level and the serum iron level. The importance of milk and vegetables in the diet is stressed and also the association between milk consumption and the serum cholesterol level.     

Biomimetic heterobimetallic architecture of Ni(ii) and Fe(ii) for CO2 hydrogenation in aqueous media. A DFT study

In this work, density functional theory has been employed to design a heterobimetallic catalyst of Ni(ii) and Fe(ii) for the effective CO₂ hydrogenation to HCOOH. Based on computational results, our newly designed catalyst is found to be effective for such conversion reactions with free energy as low as 14.13 kcal mol⁻¹ for the rate determining step. Such a low value of free energy indicates that the NiFe heterobimetallic catalyst can prove to be very efficient for the above said conversion. Moreover, the effects of ligand substitutions at the active metal center and the effects due to various spin states are also explored, and can serve as a great tool for the rational design of NiFe catalyst for CO₂ hydrogenation.

The hydrogenation of CO₂ by our newly designed [NiFe] heterobimetallic catalyst inspired by the active site of [NiFe] hydrogenase.     

A combined crystallography and DFT study on ring-shaped Cucurbit[n]urils: structures,surface character,and host–guest recognition

A combined crystallography and DFT study of cucurbit[n]urils (n = 5–8, 10) was carried out, and PBE0 was certified to be the most rational density functional method for optimization task. Steric hindrance and electronic effect of the hindered lone pair electrons in cucurbit[n]urils were qualitatively measured by bond order analysis, lone pair electron (LP) visualization and electrostatic potential (ESP) study. Together with energy decomposition analysis of some selected host–guest systems, we quantitatively verified the effect of size/cavity and noncovalent interaction in host–guest recognition. This solid study revealed that lone pairs electrons affect not only on host–guest identification mode but also on geometry stability, which pave the avenue for further sophisticated applications.

A combined crystallography and DFT study of CB[n]s (n = 5–8, 10) was carried out. Through wavefunction analysis, how the hindered lone pair electrons affect on structures, electrostatics potential distribution and host–guest recognition were disclosed.