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Despite the continuous increase in capacity, lithium-ion intercalation batteries are approaching their performance limits. As a result, research is intensifying on next-generation battery technologies. The use of a lithium metal anode promises the highest theoretical energy density and enables use of lithium-free or novel high-energy cathodes. However, the lithium metal anode suffers from poor morphological stability and Coulombic efficiency during cycling, especially in liquid electrolytes. In contrast to solid electrolytes, liquid electrolytes have the advantage of high ionic conductivity and good wetting of the anode, despite the lithium metal volume change during cycling. Rapid capacity fade due to inhomogeneous deposition and dissolution of lithium is the main hindrance to the successful utilization of the lithium metal anode in combination with liquid electrolytes. In this perspective, we discuss how experimental and theoretical insights can provide possible pathways for reversible cycling of two-dimensional lithium metal. Therefore, we discuss improvements in the understanding of lithium metal nucleation, deposition, and stripping on the nanoscale. As the solid-electrolyte interphase (SEI) plays a key role in the lithium morphology, we discuss how the proper SEI design might allow stable cycling. We highlight recent advances in conventional and (localized) highly concentrated electrolytes in view of their respective SEIs. We also discuss artificial interphases and three-dimensional host frameworks, which show prospects of mitigating morphological instabilities and suppressing large shape change on the electrode level.

BACKGROUND: Although the painful shoulder is one of the most common dysfunctions of the locomotor apparatus, and is frequently treated both at primary healthcare centres and by specialists, little evidence has been reported to support or refute the effectiveness of the treatments most commonly applied. According to the bibliography reviewed, physiotherapy, which is the most common action taken to alleviate this problem, has not yet been proven to be effective, because of the small size of sample groups and the lack of methodological rigor in the papers published on the subject. No reviews have been made to assess the effectiveness of acupuncture in treating this complaint, but in recent years controlled randomised studies have been made and these demonstrate an increasing use of acupuncture to treat pathologies of the soft tissues of the shoulder. In this study, we seek to evaluate the effectiveness of physiotherapy applied jointly with acupuncture, compared with physiotherapy applied with a TENS-placebo, in the treatment of painful shoulder caused by subacromial syndrome (rotator cuff tendinitis and subacromial bursitis). METHODS/DESIGN: Randomised controlled multicentre study with blind evaluation by an independent observer and blind, independent analysis. A study will be made of 465 patients referred to the rehabilitation services at participating healthcare centres, belonging to the regional public health systems of Andalusia and Murcia, these patients presenting symptoms of painful shoulder and a diagnosis of subacromial syndrome (rotator cuff tendinitis and subacromial bursitis). The patients will be randomised into two groups: 1) experimental (acupuncture + physiotherapy); 2) control (TENS-placebo + physiotherapy); the administration of rescue medication will also be allowed. The treatment period will have a duration of three weeks. The main result variable will be the change produced on Constant's Shoulder Function Assessment (SFA) Scale; as secondary variables, we will record the changes in diurnal pain intensity on a visual analogue scale (VAS), nocturnal pain intensity on the VAS, doses of non-steroid anti-inflammatory drugs (NSAIDs) taken during the study period, credibility scale for the treatment, degree of improvement perceived by the patient and degree of improvement perceived by the evaluator. A follow up examination will be made at 3, 6 and 12 months after the study period has ended. Two types of population will be considered for analysis: per protocol and per intention to treat. DISCUSSION: The discussion will take into account the limitations of the study, together with considerations such as the choice of a simple, safe method to treat this shoulder complaint, the choice of the control group, and the blinding of the patients, evaluators and those responsible for carrying out the final analysis. [ABSTRACT FROM AUTHOR]

Through the actuation of vibronic modes in cell-membrane-associated aminocyanines, using near-infrared light, a distinct type of molecular mechanical action can be exploited to rapidly kill cells by necrosis. Vibronic-driven action (VDA) is distinct from both photodynamic therapy and photothermal therapy as its mechanical effect on the cell membrane is not abrogated by inhibitors of reactive oxygen species and it does not induce thermal killing. Subpicosecond concerted whole-molecule vibrations of VDA-induced mechanical disruption can be achieved using very low concentrations (500 nM) of aminocyanines or low doses of light (12 J cm -2 , 80 mW cm -2 for 2.5 min), resulting in complete eradication of human melanoma cells in vitro. Also, 50% tumour-free efficacy in mouse models for melanoma was achieved. The molecules that destroy cell membranes through VDA have been termed molecular jackhammers because they undergo concerted whole-molecule vibrations. Given that a cell is unlikely to develop resistance to such molecular mechanical forces, molecular jackhammers present an alternative modality for inducing cancer cell death., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

The solid-electrolyte interphase (SEI) critically governs the performance of rechargeable batteries. An ideal SEI is expected to be electrically insulative to prevent persistently parasitic reactions between the electrode and the electrolyte and ionically conductive to facilitate Faradaic reactions of the electrode. However, the true nature of the electrical properties of the SEI remains hitherto unclear due to the lack of a direct characterization method. Here we use in situ bias transmission electron microscopy to directly measure the electrical properties of SEIs formed on copper and lithium substrates. We reveal that SEIs show a voltage-dependent differential conductance. A higher rate of differential conductance induces a thicker SEI with an intricate topographic feature, leading to an inferior Coulombic efficiency and cycling stability in Li∣∣Cu and Li∣∣LiNi 0.8 Mn 0.1 Co 0.1 O 2 cells. Our work provides insight into the targeted design of the SEI with desired characteristics towards better battery performance.

The unique electrical properties of carbon nanotubes (CNTs) are highly desired in many technological applications. Unfortunately, in practice, the electrical conductivity of most CNTs and their assemblies has fallen short of expectations. One reason for this poor performance is that electrical resistance develops at the interface between carbon nanomaterials and metal surfaces when traditional metal-metal type contacts are employed. Here, a method for overcoming this resistance using covalent bond formation between open-ended CNTs and Cu surfaces is investigated experimentally and supported by theoretical calculations. The open-ended CNTs are vertically oriented compared to the substrate and have carboxylic functional groups that react with aminophenyl groups (linkers) grafted on metal surfaces. The covalent bond formation, crosslinking carboxylic and amine, via amide bond formation occurs at 120 °C. The covalent bonding nature of the aminophenyl linker is demonstrated theoretically using (100), (110), and (111) Cu surfaces, and bridge-like bond formation between carbon and two adjacent Cu atoms is revealed. The electrical conductivity calculated for a single intramolecular-type junction supports covalent bond formation between Cu and CNTs. Experimentally, the robustness of the covalent bonding between vertically oriented CNTs is tested by exposing CNTs on Cu to sonication, which reveals that CNTs remain fixed to the Cu supports. Since bonding CNTs to metals was performed at low temperatures, the reported method of covalent bond formation is expected to facilitate the application of CNTs in multiple fields, including electronics., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We evaluate the fullerene C 60 binding effect; through the metal (Al) and through the ligand (Pc,TPP), on the photophysical and charge transport properties of M-porphyrin(TPP)/phthalocyanine(Pc) (M = Al(III), Zn(II)). We perform density functional theory (DFT) and time-dependent DFT calculations for the macrocycle-C 60 dyads, showing that all systems studied are thermodynamically favorable. The C 60 binding effect on the absorption spectrum is a red-shift of the Q and Soret (B) bands of TPPs and Pcs. The Pc-dyads show longer λ for Q bands (673 nm) than those with TPP (568 nm). AlTPP-C 60 and ZnTPP-C 60 show a more favorable electron injection to TiO 2 than the analogs Pcs, and the regeneration of the dye is preferred in AlTPP-C 60 and AlPc-C 60 . Zero-bias conductance is computed (10 -4 -10 -7  G 0 ) for the dyads using molecular junctions with Au(111)-based electrodes. When a bias voltage of around 0.6 V up to 1 V is applied, an increase in current is obtained for AlTPP-C 60 (10 -7 A), ZnTPP-C 60 (10 -7  A), and AlPc-C 60 (10 -8 A). Although there is not a unique trend in the behavior of the dyads, Pcs have better photophysical properties than TPPs and the latter are better in the charge transport. We conclude that AlTPP(ZnTPP)-C 60 dyads are an excellent alternative for designing new materials for dye-sensitized solar cells or optoelectronic devices., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Aqueous Zn batteries promise high energy density but suffer from Zn dendritic growth and poor low-temperature performance. Here, we overcome both challenges by using an eutectic 7.6 m ZnCl 2 aqueous electrolyte with 0.05 m SnCl 2 additive, which in situ forms a zincophilic/zincophobic Sn/Zn 5 (OH) 8 Cl 2 ⋅H 2 O bilayer interphase and enables low temperature operation. Zincophilic Sn decreases Zn plating/stripping overpotential and promotes uniform Zn plating, while zincophobic Zn 5 (OH) 8 Cl 2 ⋅H 2 O top-layer suppresses Zn dendrite growth. The eutectic electrolyte has a high ionic conductivity of ≈0.8 mS cm -1 even at -70 °C due to the distortion of hydrogen bond network by solvated Zn 2+ and Cl - . The eutectic electrolyte enables Zn∥Ti half-cell a high Coulombic efficiency (CE) of >99.7 % for 200 cycles and Zn∥Zn cell steady charge/discharge for 500 h with a low overpotential of 8 mV at 3 mA cm -2 . Practically, Zn∥VOPO 4 batteries maintain >95 % capacity with a CE of >99.9 % for 200 cycles at -50 °C, and retain ≈30 % capacity at -70 °C of that at 20 °C., (© 2021 Wiley-VCH GmbH.)

Present Li-ion battery (LIB) technology requires strong improvements in performance, energy capacity, charging-time, and cost to expand their application to e-mobility and grid storage. Li-metal is one of the most promising materials to replace commercial anodes such as graphite because of its 10 times higher specific capacity. However, Li-metal has high reactivity with commercial liquid electrolytes; thus, new solid materials are proposed to replace liquid electrolytes when Li-metal anodes are used. We present a theoretical analysis of the charging process in a full nanobattery, containing a LiCoO2 cathode, a Li7P2S8I solid-state electrolyte (SSE), a Li-metal anode as well as Al and Cu collectors for the cathode and anode, respectively. In addition, we added a Li3P/Li2S film as a solid electrolyte interphase (SEI) layer between the Li-anode and SSE. Thus, we focus this study on the SEI and SSE. We simulated the charging of the nanobattery with an external voltage by applying an electric field. We estimated temperature profiles within the nanobattery and analyzed Li-ion transport through the SSE and SEI. We observed a slight temperature rise at the SEI due to reactions forming PS3- and P2S74- fragments at the interfaces; however, this temperature profile changes due to the charging current under the presence of the external electric field ε = 0.75 V Å-1. Without the external field, the calculated open-circuit voltage (OCV) was 3.86 V for the battery, which is within the range of values of commercial cobalt-based LIBs. This voltage implies a spontaneous fall of available Li-ions from the anode to the cathode (during discharge). The charge of this nanobattery requires overcoming the OCV plus an additional voltage that determines the charging current. Thus, we applied an external potential able to neutralize the OCV, plus an additional 1.6 V to induce the transport of Li+ from the cathode up to the anode. Several interesting details about Li+ transport paths through the SSE and SEI are discussed.

An ab initio molecular dynamics study of an electrochemical interface between a solid-state-electrolyte Li 0.29 La 0.57 TiO 3 and Li-metal is performed to analyze interphase formation and evolution when external electric fields of 0, 0.5, 1.0 and 2.0 V Å -1 are applied. From this electrochemical stability analysis, it was concluded that lithium-oxide (Li 2 O) and lanthanum-oxide (La 2 O 3 ) phases were formed at the electrolyte/anode interphase. As the electric field increased, oxygen from the electrolyte diffused through the Li-metal anode, increasing the amount of O from deeper crystallographic planes of the electrolyte that reacted with Li and La. A strong reduction of Ti was expected from their Bader charge variation from +3.5 in the bulk to +2.5 at the interface. Due to the loss of Li atoms from the anode to form Li-oxide at the interphase, vacancies were created on the Li-metal, causing anode structure amorphization near the Li-oxide phase and keeping the rest of the anode structure as BCC. Therefore, the interface was unstable because of the continuous Li-oxide and La-oxide formation and growth, which were more pronounced when increasing the external electric field., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Lithium-metal is a desired material for anodes of Li-ion and beyond Li-ion batteries because of its large theoretical specific capacity of 3860 mA h g -1 (the highest known so far), low density, and extremely low potential. Unfortunately, there are several problems that restrict the practical application of lithium-metal anodes, such as the formation of dendrites and reactivity with electrolytes. We present here a study of lithium dendrite formation on a Li-metal anode covered by a cracked solid electrolyte interface (SEI) of LiF in contact with a typical liquid electrolyte composed of 1 M LiPF 6 salt solvated in ethylene carbonate. The study uses classical molecular dynamics on a model nanobattery. We tested three ways to charge the nanobattery: (1) constant current at a rate of one Li + per 0.4 ps, (2) pulse train 10 Li + per 4 ps, and (3) constant number ions in the electrolyte: one Li + enters the electrolyte from the cathode as one Li + exits the electrolyte to the anode. We found that although the SEI does not interfere with the lithiation, the mere presence of a crack in the SEI boosts and guides dendrite formation at temperatures between 325 K and 410.7 K at any C-rate, being more favorable at 325 K than at 410.7 K. On the other hand, we find that a higher C-rate (2.2C) favors the lithium dendrite formation compared to a lower C-rate (1.6C). Thus the battery could store more energy in a safe way at a lower C-rate., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Visualization of the halobenzene σ-hole region of molecules (PhX, X = Cl, Br, I) was conducted to investigate the nature of the σ-hole present between covalently bonded elements of groups IVB-VIIB (known as halogen bonding for group VIIB) and corresponding negative sites, such as Lewis base lone electron pairs, π-electrons, or anions. The σ-hole consists of a region of poor electron density and often relatively positive electrostatic potential surrounding the outermost portion of the halogen atom along the A-X bond axis. In this work, molecular electrostatic potential (MEP) isosurfaces for PhX obtained from ab initio calculations are examined to determine the σ-hole in 3D, showing the surfaces of corresponding positive and negative regions. Surfaces were mapped for isopotentials of PhX molecules as low as 0.003 V and scaled up by factors of 10 up to 3 V. The σ-hole is revealed as a positive region exposed underneath a predominantly negative MEP isosurface. As isopotential values move away from zero, this hole grows in radius; conversely, its presence completely fades as potential approaches zero with increasing distance from the molecule. This technique can also be used to compare behaviors of neutral molecules and their ionic counterparts like the case of neutral PF 6 (not observed experimentally) and the hexafluorophosphate anion, PF 6 - , a typical counter-ion in commercial Li-ion batteries. The pnictogen halide PF 5 features similar MEP trends as the neutral PF 6 , which features reactive sites, shown as negative potential caps, at specific points in the molecule, similar to those of PF 5 . The portrayal of MEP behavior in iso-surfaces at specific and practical values of chemical interest is crucial when defining lump parameter sets for Coulombic force fields for molecular dynamics simulations to be used in systems that go from biological macromolecules to crystal engineering to devices to final products. Active chemical sites can be described by the MEP function, V(r), more proficiently than just wavefunctions or electron densities that intrinsically contain the same information, and this is fully enhanced when color-coding electron densities on isopotential surfaces are shown. Graphical abstract The hidden features of orbital holes depicted by iso-potentials.

Due to recent advances in the field of microelectronics, the growth in microelectronics applications, and the exponentially increasing demand for microelectronic devices in the power sector, it is important to study the behavior of silicon at the nanoscale, given that nanoclusters of silicon could be used to design a new kind of lithium-ion batteries with strongly enhanced performance. Here, molecular dynamics was employed to calculate the self-diffusion coefficients of silicon clusters at room temperature and at a temperature approaching the melting point of silicon, complementing experimental efforts in this field. Silicon clusters of the same spherical geometry and size but with different vacancy fractions were studied using molecular dynamics using the Tersoff potential in order to estimate phase changes and self-diffusion coefficients. At 300 K, the self-diffusion coefficient was found to vary non-monotonically: the self-diffusion coefficient at a vacancy fraction of 7.5% is half than the vacancy at a fraction of 0%, while the self-diffusion coefficient at a vacancy fraction of 20% is two orders of magnitude larger than that at a vacancy fraction of 0%. However, there is only a marginal monotonic increase in the self-diffusion coefficient values with vacancy fraction at 2000 K. The results of this investigation of vacancy-mediated self-diffusion could aid attempts to improve diffusion control, which is crucial to nanocluster applications in various devices, and the results also provide insight into how the temperature, energy, pressure, and phase changes of the silicon clusters depend on vacancy fraction. This may ultimately allow the design and selection of materials for thermoelectric and optoelectronic devices and thermal transducers to be optimized. Our results also indicated that the findings we obtained for the clusters are independent of the particular random vacancy distribution considered and the heating rate applied to the clusters. Graphical Abstract Silicon nanoparticles (SNP) are among the best options to choose from for the design of devices for renewable energies; SNP based material performance can be effectively tailored by controling the vacancy, temperature and other properties of the SNP.

To facilitate the development of new materials for use in batteries, it is necessary to develop ab initio full-electron computational techniques for modeling potential new battery materials. Here, we tested density functional theory procedures that are accurate enough to obtain the energetics of a zinc/copper voltaic cell. We found the magnitude of the zero-point energy correction to be 0.01-0.2 kcal/mol per atom or molecule and the magnitude of the dispersion correction to be 0.1-0.6 kcal/mol per atom or molecule for Zn n , (H 2 O) n , [Formula: see text], [Formula: see text], and Cu n . Counterpoise correction significantly affected the values of ∆[Formula: see text], ∆[Formula: see text], and ∆E solv by 1.0-3.1 kcal/mol per atom or molecule at the B3PW91/6-31G(d) level of theory, but by only 0.04-0.4 kcal/mol per atom or molecule at the B3PW91/cc-pVTZ level of theory. The application of B3PW91/6-31G(d) yielded results that differed from macroscopic experimental values by 0.1-7.1 kcal/mol per atom or molecule, whereas applying B3PW91/cc-pVTZ produced results that differed from macroscopic experimental values by 0.1-4.8 kcal/mol per atom or molecule, with the smallest differences occurring for reactions with a small macroscopic experimental ∆E and the largest differences occurring for reactions with a large macroscopic experimental ∆E, implying size consistency.

Rechargeable lithium-ion batteries require a vigorous improvement if we want to use them massively for high energy applications. Silicon and metal lithium anodes are excellent alternatives because of their large theoretical capacity when compared to graphite used in practically all rechargeable Li-ion batteries. However, several problems need to be addressed satisfactorily before a major fabrication effort can be launched; for instance, the growth of lithium dendrites is one of the most important to take care due to safety issues. In this work we attempt to predict the mechanism of dendrite growth by simulating possible behaviors of charge distributions in the anode of an already cracked solid electrolyte interphase of a nanobattery, which is under the application of an external field representing the charging of the battery; thus, elucidating the conditions for dendrite growth. The extremely slow drift velocity of the Li-ions of ∼1 mm per hour in a typical commercial Li-ion battery, makes the growth of a dendrite take a few hours; however, once a Li-ion arrives at an active site of the anode, it takes an extremely short time of ∼1 ps to react. This large difference in time-scales allows us to perform the molecular dynamics simulation of the ions at much larger drift velocities, so we can have valuable results in reasonable computational times. The conditions before the growth are assumed and conditions that do not lead to the growth are ignored. We performed molecular dynamics simulations of a pre-lithiated silicon anode with a Li : Si ratio of 21 : 5, corresponding to a fully charged battery. We simulate the dendrite growth by testing a few charge distributions in a nanosized square representing a crack of the solid electrolyte interphase, which is where the electrolyte solution comes into direct contact with the LiSi alloy anode. Depending on the selected charge distributions for such an anode surface, the dendrites grow during the simulation when an external field is applied. We found that dendrites grow when strong deviations of charge distributions take place on the surface of the crack. Results from this work are important in finding ways to constrain lithium dendrite growth using tailored coatings or pre-coatings covering the LiSi alloy anode., Competing Interests: The authors declare that there is no conflict of interests regarding the publication of this article., (This journal is © The Royal Society of Chemistry.)

This Review focuses on research oriented toward elucidation of the various aspects that determine adsorption of CO 2 in metal-organic frameworks and its separation from gas mixtures found in industrial processes. It includes theoretical, experimental, and combined approaches able to characterize the materials, investigate the adsorption/desorption/reaction properties of the adsorbates inside such environments, screen and design new materials, and analyze additional factors such as material regenerability, stability, effects of impurities, and cost among several factors that influence the effectiveness of the separations. CO 2 adsorption, separations, and membranes are reviewed followed by an analysis of the effects of stability, impurities, and process operation conditions on practical applications.

Rechargeable lithium-ion batteries are the most popular devices for energy storage but still a lot of research needs to be done to improve their cycling and storage capacity. Silicon has been proposed as an anode material because of its large theoretical capacity of ∼3600 mAh/g. Therefore, focus is needed on the lithiation process of silicon anodes where it is known that the anode increases its volume more than 300%, producing cracking and other damages. We performed molecular dynamics atomistic simulations to study the swelling, alloying, and amorphization of a silicon nanocrystal anode in a full nanobattery model during the first charging cycle. A dissolved salt of lithium hexafluorophosphate in ethylene carbonate was chosen as the electrolyte solution and lithium cobalt oxide as cathode. External electric fields are applied to emulate the charging, causing the migration of the Li-ions from the cathode to the anode, by drifting through the electrolyte solution, thus converting pristine Si gradually into Li 14 Si 5 when fully lithiated. When the electric field is applied to the nanobattery, the temperature never exceeds 360 K due to a temperature control imposed resembling a cooling mechanism. The volume of the anode increases with the amorphization of the silicon as the external field is applied by creating a layer of LiSi alloy between the electrolyte and the silicon nanocrystal and then, at the arrival of more Li-ions changing to an alloy, where the drift velocity of Li-ions is greater than the velocity in the initial nanocrystal structure. Charge neutrality is maintained by concerted complementary reduction-oxidation reactions at the anode and cathode, respectively. In addition, the nanobattery model developed here can be used to study charge mobility, current density, conductance and resistivity, among several other properties of several candidate materials for rechargeable batteries and constitutes the initial point for further studies on the formation of the solid electrolyte interphase in the anode. Graphical Abstract Nanobattery: LiCoO 2 cathode, electrolyte solution of 1M Li + PF 6 - in ethylene carbonate, and Si crystal anode, which changes its volume due to lithiation during the first charge.

Coating silicon particles with a suitable thin film has appeared as a possible solution to accommodate the swelling of silicon upon lithiation and its posterior cracking and pulverization during cycling of Li-ion batteries. In particular, aluminum alkoxide (alucone) films have been recently deposited over Si anodes, and the lithiation and electrochemical behavior of the system have been characterized. However, some questions remain regarding the lithium molecular migration mechanisms through the film and the electronic properties of the alucone film. Here we use density functional theory, ab initio molecular dynamics simulations, and Green's function theory to examine the film formation, lithiation, and reactivity in contact with an electrolyte solution. It is found that the film is composed of Al-O complexes with 3-O or 4-O coordination. During lithiation, Li atoms bind very strongly to the O atoms in the most energetically favorable sites. After the film is irreversibly saturated with Li atoms, it becomes electronically conductive. The ethylene carbonate molecules in liquid phase are found to be reduced at the surface of the Li-saturated alucone film following similar electron transfer mechanisms as found previously for lithiated silicon anodes. The theoretical results are in agreement with those from morphology and electrochemical analyses.

In order to determine how actinide atoms are dressed when solvated in water, density functional theory calculations have been carried out to study the equilibrium structure of uranium plutonium and thorium salts (UO2(2+), PuO2(2+), Pu(4+), and Th(4+)) both in vacuum as well as in solution represented by a conductor-like polarizable continuum model. This information is of paramount importance for the development of sensitive nanosensors. Both UO2(2+) and PuO2(2+) ions show coordination number of 4-5 with counterions replacing one or two water molecules from the first coordination shell. On the other hand, Pu(4+), has a coordination number of 8 both when completely solvated and also in the presence of chloride and nitrate ions with counterions replacing water molecules in the first shell. Nitrates were found to bind more strongly to Pu(IV) than chloride anions. In the case of the Th(IV) ion, the coordination number was found to be 9 or 10 in the presence of chlorides. Moreover, the Pu(IV) ion shows greater affinity for chlorides than the Th(IV) ion. Adding dispersion and ZPE corrections to the binding energy does not alter the trends in relative stability of several conformers because of error cancelations. All structures and energetics of these complexes are reported.

Mycobacterium tuberculosis pyrazinamidase (PZAse) is a key enzyme to activate the pro-drug pyrazinamide (PZA). PZAse is a metalloenzyme that coordinates in vitro different divalent metal cofactors in the metal coordination site (MCS). Several metals including Co(2+), Mn(2+), and Zn(2+) are able to reactivate the metal-depleted PZAse in vitro. We use quantum mechanical calculations to investigate the Zn(2+), Fe(2+), and Mn(2+) metal cofactor effects on the local MCS structure, metal-ligand or metal-residue binding energy, and charge distribution. Results suggest that the major metal-dependent changes occur in the metal-ligand binding energy and charge distribution. Zn(2+) shows the highest binding energy to the ligands (residues). In addition, Zn(2+) and Mn(2+) within the PZAse MCS highly polarize the O-H bond of coordinated water molecules in comparison with Fe(2+). This suggests that the coordination of Zn(2+) or Mn(2+) to the PZAse protein facilitates the deprotonation of coordinated water to generate a nucleophile for catalysis as in carboxypeptidase A. Because metal ion binding is relevant to enzymatic reaction, identification of the metal binding event is important. The infrared vibrational mode shift of the C═Nε (His) bond from the M. tuberculosis MCS is the best IR probe to metal complexation.

The detection of uranium is very important, especially in water and, more importantly, in the form of uranyl ion (UO₂)²⁺, which is one of its most abundant moieties. Here, we report analyses and simulations of uranyl in water using ab initio modified force fields for water with improved parameters and charges of uranyl. We use a TIP4P model, which allows us to obtain accurate water properties such as the boiling point and the second and third shells of water molecules in the radial distribution function thanks to a fictitious charge that corrects the 3-point models by reproducing the exact dipole moment of the water molecule. We also introduced non-bonded interaction parameters for the water-uranyl intermolecular force field. Special care was taken in testing the effect of a range of uranyl charges on the structure of uranyl-water complexes. Atomic charges of the solvated ion in water were obtained using density functional theory (DFT) calculations taking into account the presence of nitrate ions in the solution, forming a neutral ensemble. DFT-based force fields were calculated in such a way that water properties, such as the boiling point or the pair distribution function stand. Finally, molecular dynamics simulations of a water box containing uranyl cations and nitrate anions are performed at room temperature. The three peaks in the oxygen-oxygen radial distribution function for water were found to be kept in the presence of uranyl thanks to the improvement of interaction parameters and charges. Also, we found three shells of water molecules surrounding the uranyl ion instead of two as was previously thought.

Because of the potential importance of carbon nanotubes (CNT) in renewable energy and other fields, molecular orbital ab initio calculations are used to study the relation between mechanical and electronic properties of such structures. We estimate a modulus of elasticity of 1.3 TPa and find out that the mechanism of CNT structure deformation is dependent on their chirality. Armchair and chiral nanotubes have ductile deformation fracture while zigzag have both ductile and brittle; on the other hand armchair nanotubes fracture and form two caps while chiral nanotubes adopt a helical-structure conformation. In addition, the energy gap between occupied and unoccupied molecular orbitals increases when nanotubes are under plastic deformation. This strong coupling between mechanical and electrical properties can be used to tune CNT mechanically to specific electronic bandgaps, affecting directly their electromagnetic absorption properties.

We calculate the interactions of two atomic layer deposition (ALD) reactants, trimethylaluminium (TMA) and tetrakis(ethylmethylamino) hafnium (TEMAH) with the hydroxylated Ga-face of GaN clusters when aluminum oxide and hafnium oxide, respectively, are being deposited. The GaN clusters are suitable as testbeds for the actual Ga-face on practical GaN nanocrystals of importance not only in electronics but for several other applications in nanotechnology. We find that TMA spontaneously interacts with hydroxylated GaN; however it does not follow the atomic layer deposition reaction path unless there is an excess in potential energy introduced in the clusters at the beginning of the optimization, for instance, using larger bond lengths of various bonds in the initial structures. TEMAH also does not interact with hydroxylated GaN, unless there is an excess in potential energy. The formation of a Ga-N(CH3)(CH2CH3) bond during the ALD of HfO2 using TEMAH as the reactant without breaking the Hf-N bond could be the key part of the mechanism behind the formation of an interface layer at the HfO2/GaN interface.

Mechanical and thermal properties of polyvinyl alcohol (PVA) are characterized and analyzed using in situ X-ray photoelectron spectroscopy (XPS) and quantum chemistry calculations. It is found that the carbon peaks-commonly used as the reference for spectroscopic analysis-shift under mechanical and thermal stretching. Results also indicate that, at different temperatures and among the various functional groups present in PVA, the carbon in the C-O group is the most stable. Computational calculations showed that Hartree-Fock/10-31G (d) reproduces the binding energy of core carbon electrons with an accuracy of 95%, which is enough to characterize bonds, allowing the results of the spectroscopic analysis to be corroborated.

This is a preliminary cross multidisciplinary theoretical-computational approach for the design of a drug delivery system based on immunoconjugated carbon nanotube against HER2- overexpressing cancer cells. This drug delivery system allows the release of an encapsulated cytotoxic cocktail in a controlled manner under pulsed radio frequency (RF) irradiation. Our effort is focused on the computational aided design of a high affinity bispecific anti-HER2 antibody and an opening mechanism of the carbon nanotube (CNT) based cytotoxic carrier for controlling multiple drug release. We study the main interactions between the antibody and the antigen by a computational scanning mutagenesis approach of trastuzumab and pertuzumab fragment antigen binding (Fab) structures in order to enhance their binding affinity. Then, each Fab fragments is joined by a polypeptide linker which should be stable enough to avoid the "open form" of antibody. On the other hand, we also conjugate the engineered antibody to functionalized CNTs (f-CNTs), which encapsulate the inhibitors of the HER2/PI3K/Akt/mTOR signaling pathway. We take advantage of the fact that f-CNT converts the RF radiation absorption into heat release. A pulsed laser at 13.45 MHz increments the temperature around 40 °C for triggering the nano-caps destabilization, which allows the switching of the opening mechanism of the drug carrier. Nano-caps will be a dual pH/temperature responsive in order to take advantage of lysosome characteristic (acidic pH) and heat release from the carrier. Nano-caps are functionalized with organic amide moieties, which hydrolyze quickly at an acidic pH into primary amines, and protonated amines generate repulsion interactions with other charged species, which trigger the cytotoxics release.

Poly(ethylene glycol) (PEG) functionalization of carbon nanotubes (CNTs) is widely used to render CNTs suitable as vectors for targeted drug delivery. One recently described PEGylated version uses an oxidized single-walled carbon nanotube called a hydrophilic carbon cluster (HCC). The resulting geometric dimension of the hybrid PEG-CNT or PEG-HCC is an important factor determining its ability to permeate the cellular membrane and to maintain its blood circulation. Molecular dynamics (MD) simulations were performed to estimate the maximum length and width dimensions for a PEGylated single-walled carbon nanotube in water solution as a model for the PEG-HCC. We ensured maximum PEGylation by functionalizing each carbon atom in a CNT ring with an elongated PEG molecule, avoiding overlapping between PEGs attached to different CNT rings. We suggest that maximum PEGylation is important to achieve an optimal drug delivery platform.

Electronic properties of Fe(2-10) clusters and their ions are described by an all-electron ab initio density functional theory computational analysis using the Handy's OPTX exchange and the gradient-corrected correlation functional of Perdew, Burke and Ernzerhof with a triple-zeta valence basis set plus polarization functions. Ground state structures, magnetic moments, dissociation energies, binding energies, IR vibrational spectra, vertical and adiabatic ionization energies, and electron affinities are reported. Two possible states for Fe(2) which are separated by 81.54 meV are described as possible Fe(2), while the septet (ground state) yields an accurate bond distance (error of 0.02 Å); the nonet yields a precise vibrational frequency (error of 10.1 cm(-1)). Fe(2) binding energy (0.05 eV/atom error) more closely resembles experimental data than any other previously reported computational methods. In addition, the Fe(6) is found to be the most stable cluster within our set being analyzed.

We perform molecular dynamics simulations to analyze the wrapping process of a single-stranded (ss) DNA around a gapped CNT immersed in a bath of water. We observe the formation of a stable molecular junction with the ssDNA adopting a helical or circular conformation around one CNT electrode and a linear conformation around the opposite electrode. We find that DNA undergoes several conformational changes during equilibration of the self-assembled molecular junction. This process would allow a higher yield of successful CNT-DNA interconnections, which constitutes a novel structure of interest in chemical and biological sensing at the single-molecule level.

Molecular simulations leading to sensors for the detection of explosive compounds require force field parameters that can reproduce the mechanical and vibrational properties of energetic materials. We developed precise harmonic force fields for alanine polypeptides and glycine oligopeptides using the FUERZA procedure that uses the Hessian tensor (obtained from ab initio calculations) to calculate precise parameters. In this work, we used the same procedure to calculate generalized force field parameters of several nitro compounds. We found a linear relationship between force constant and bond distance. The average angle in the nitro compounds was 116°, excluding the 90° angle of the carbon atoms in the octanitrocubane. The calculated parameters permitted the accurate molecular modeling of nitro compounds containing many functional groups. Results were acceptable when compared with others obtained using methods that are specific for one type of molecule, and much better than others obtained using methods that are too general (these ignore the chemical effects of surrounding atoms on the bonding and therefore the bond strength, which affects the mechanical and vibrational properties of the whole molecule).

An understanding of why adenine (A) pairs with thymine (T) and cytosine (C) with guanine (G) in DNA is very useful in the design of sensors and other related devices. We report the use of dissociation energies, geometries and molecular electrostatic potentials (MEPs) to justify the canonical (AT and CG) Watson-Crick pairs. We also analyze all mismatches in both configurations-cis and trans-with respect to their glycoside bonds. As expected, we found that the most stable pair configuration corresponds to CG, providing an energy criterion for that preferred configuration. The reason why A gets together with T is much more difficult to explain as the energy of this pair is smaller than the energy of some other mismatched pairs. We tested MEPs to see if they could shed light on this problem. Interestingly, MEPs yield a unique pattern (shape) for the two canonical cases but different shapes for the mismatches. A tunnel of positive potential surrounded by a negative one is found interconnecting the three H-bonds of CG and the two of AT. This MEP tunnel, assisted partially by energetics and geometrical criteria, unambiguously determine a distinctive feature of the affinity between A and T as well as that between G and C.

We perform an ab initio analysis of the photoisomerization of the protonated Schiff base of retinal (PSB-retinal) from 11-cis to 11-trans rotating the C10-C11=C12-C13 dihedral angle from 0° (cis) to -180° (trans). We find that the retinal molecule shows the lowest rotational barrier (0.22 eV) when its charge state is zero as compared to the barrier for the protonated molecule which is ∼0.89 eV. We conclude that rotation most likely takes place in the excited state of the deprotonated retinal. The addition of a proton creates a much larger barrier implying a switching behavior of retinal that might be useful for several applications in molecular electronics. All conformations of the retinal compound absorb in the green region with small shifts following the dihedral angle rotation; however, the Schiff base of retinal (SB-retinal) at trans-conformation absorbs in the violet region. The rotation of the dihedral angle around the C11=C12 π-bond affects the absorption energy of the retinal and the binding energy of the SB-retinal with the proton at the N-Schiff; the binding energy is slightly lower at the trans-SB-retinal than at other conformations of the retinal.

A high sensitivity and selectivity sensor is proposed using graphene ribbons which are able to read molecular vibrations and molecular electrostatic potentials, acting as an amplifier and as a transducer converting molecular signals into current-voltage quantities of standard electronics. Two sensing mechanisms are used to demonstrate the concept using ab initio density functional methods. By using the terahertz region of the spectrum, we can characterize modes when single molecules are adsorbed on the ribbon surface. Characteristic modes can be obtained and used as fingerprints, which can be transduced into current by applying a voltage along the ribbons. On the other hand, the fully delocalized frontier molecular orbitals of graphene ribbons, commonly denominated plasmons in larger solid state structures, are extremely sensitive to any moiety approach; once plasmons are in contact with an "agent" (actually its molecular potential), the transport through the ribbons acting as electrodes catching the signals is strongly affected.

Molecules that resemble a semiconductor diode depletion zone are those with an intrinsic electric dipole, which were suggested as potential electronic devices. However, so far, no single molecule has met such a goal because any electron donor-acceptor linker strongly diminishes any possibility of diode behavior. We find an intrinsic diode behavior in polypeptides such as poly(L-alanine) and polyglycine in alpha-helix conformation, explained in terms of molecular orbital theory using ab initio methods. The application of an antiparallel electric field with respect to the molecular dipole yields a gradual increase in current through the junction because the valence and conduction orbitals approach each other reducing their gap as the bias increases. However, a parallel field makes the gap energy increase, avoiding the pass of the electrons.

We demonstrate the switchability of the molecular conductivity of a citrate. This was made possible through mechanical stretching of two conformers of such citrate capped on and linked between gold nanoparticles (AuNPs) self-assembled as a film. On the basis of experimental results, theoretical analysis was conducted using the density function theory and Green's function to study the electron flux in the backbone. We found that the molecular conductivity depended on the pathways of electrons that were controlled by the applied mechanical stress. Under stress, we could tune the conductivity up and down for as much as 10-fold. The mechanochemistry behind this phenomenon is an alternative branch of chemistry.

The reduction in oxygen on bimetallic tips X(S)Pt(3) (X(S) = Co(3), Ni(3), Pt(6), Co(3)Pt(3)) in aqueous acid medium is studied. It is found that a locally neutral neighborhood of an active site in the bimetallic tip as well as adduct hydration assist in the protonation. It is concluded that metallic tips of Pt, Co(3)Pt, and Co are comparable in performance for the oxygen reduction reaction. For an adduct, the larger the bonding energy of the Pt(3)-island to the (X(S)) substrate, the more charged the oxygen molecule becomes for different levels of protonation. Furthermore, if a hydroxyl OOH group is formed as a result of protonation, the interaction of the cation with O(2) decreases with increasing level of hydration.

The fabrication of graphene nanoribbons from carbon nanotubes (CNTs) treated with potassium permanganate in a concentrated sulfuric acid solution has been reported by Kosynkin et al. [Nature (London) 458, 872 (2009)]. Here we report ab initio density functional theory calculations of such unzipping process. We find that the unzipping starts with the potassium permanganate attacking one of the internal C-C bonds of the CNT, stretching and breaking it. The created defect weakens neighboring bonds along the length of the CNT, making them energetically prone to be attacked too.

In this theoretical-experimental approach, we show using ab initio calculations behavior consistent with the activation of 7-dehydrocholesterol, provitamin D(3), as an initial reactant toward ultraviolet-activated reactions of vitamin D(3). We find using molecular orbital theory that a conformation between the provitamin and the vitamin shows higher conductance than those of the reactant and product. We also find experimental evidence of this electrical character by directly measuring current-voltage characteristics on irradiated and nonirradiated samples of the provitamin. The activation of the provitamin D(3) is characterized with an increase in current during the irradiation.

We calculate the transverse current through double-stranded DNA nucleotides using ab initio techniques in order to establish a protocol to recognize the type and sequence of double-stranded DNA nucleotides. The distinct current-voltage features between nucleotides are used as signatures for their characterization and sequencing. Extended bulk gold electrodes as well as extensions of the DNA backbones are tested as contacts for the electron transport, yielding currents 2 orders of magnitude larger for the former. The addition of Na or H positive counterions improves the signal levels, thus leading to a better discrimination, especially when sodium cations are added.

The frequency response of triangular DNA origami is obtained at room temperature. The sample shows a high impedance at low frequencies, e.g., at zero frequency 20 Gohms, which decreases almost linearly with the logarithm of the frequency reaching a low and flat value at 100 kHz where the impedance turns from capacitive to resistive, concluding that DNA can be used for transmission of signals at frequencies larger than 100 kHz. It is also found that characteristics of DNA cannot be completely disentangled from the characteristics of the substrate on which it is deposited, making the design of molecular circuits more challenging than the design of circuits with present lumped devices; this is a natural feature at the nanoscale.

The temperature dependences of the current-voltage characteristics of a sample of triangular DNA origami deposited in a 100 nm gap between platinum electrodes are measured using a probe station. Below 240 K, the sample shows high impedance, similar to that of the substrate. Near room temperature the current shows exponential behavior with respect to the inverse of temperature. Sweep times of 1 s do not yield a steady state; however sweep times of 450 s for the bias voltage secure a steady state. The thermionic emission and hopping conduction models yield similar barriers of approximately 0.7 eV at low voltages. For high voltages, the hopping conduction mechanism yields a barrier of 0.9 eV and the thermionic emission yields 1.1 eV. The experimental data set suggests that the dominant conduction mechanism is hopping in the range 280-320 K. The results are consistent with theoretical and experimental estimates of the barrier for related molecules.

A sensor model based on the porphyrin nucleus of the soluble guanylate cyclase enzyme is modeled and tested with nitric oxide and carbon monoxide. Molecular oxygen is tested as a possible interferer. Geometries and electronic structures of the model are assessed by density functional theory. Vibrational circular dichroism (VCD), infrared, and Raman spectra are obtained for the iron complexes uncoordinated and coordinated with the gas moieties. The sensor is capable of detecting the ligands to different extents. Carbon monoxide is less detectable than nitric oxide due to the adopted position of the molecule in the sensor; carbon oxide is aligned with the iron atom, while nitric oxide and molecular oxygens bend with an angle detectable by the VCD. It is suggested that pollutants may be detected and measured with the proposed biosensors.

Using ab initio density functional theory methods, the optimized structure of the single-, double-, and triple-layered graphene nanoribbons with different stacking orders and edges is calculated along with their Raman spectrums. For each case studied, graphene is found to be a potential source of vibrational signals in the terahertz region of the spectrum when molecules or another layer are adsorbed in the surface; this effect is independent of the hydrogen presence at the edges, and the stacking order. The visible low-frequency modes increase with the addition of graphene layers, and the number of modes may be influenced by the type of edges. The monolayer shows better performance due to the lower number of vibrational modes. The nanoribbon with fewer modes at the terahertz range is used to show a potential application of graphene acting as a sensor of single molecules.

Objective: Evaluate the efficacy of acupuncture associated with physiotherapy for patients with painful shoulder., Methods: In a multicentre controlled randomized study, participants were recruited with a clinical diagnosis of unilateral subacromial syndrome from six rehabilitation medicine departments belonging to the Public Health System in two Spanish regions. All participants received 15 sessions of physiotherapy during the 3 weeks that the treatment lasted and were randomized to additionally receive, once a week, acupuncture or mock TENS (transcutaneous electrical nerve stimulation). The primary outcome measure was the change in the Constant-Murley Score (CMS) for functional assessment of the shoulder, at 4 weeks after randomization. This study is registered as an International Standard Randomized Controlled Trial, number ISRCTN28687220., Results: A total of 425 patients were recruited. The mean score (s.d.) on the CMS had increased by 16.6 (15.6) points among the acupuncture group, compared with 10.6 (13.5) points in the control group, and the mean difference between the two groups was statistically significant (6.0 points; 95% CI 3.2, 8.8 points; P < 0.001). By the end of the treatment, 53% of the patients in the acupuncture group had decreased their consumption of analgesics, compared with a corresponding 30% among the control group (P < 0.001)., Conclusions: Single-point acupuncture in association with physiotherapy improves shoulder function and alleviates pain, compared with physiotherapy as the sole treatment. This improvement is accompanied by a reduction in the consumption of analgesic medicaments.

We study the local reactivity of molecular oxygen with bimetallic substrates of a platinum trimer island supported on nanotips of CoPt, Pt, Co, Ni, and Fe. Because of the reduced interatomic distances and varying interaction strengths with the substrates, the supported island interaction with oxygen can be tuned from stronger to weaker relative to the interaction of a freestanding island with oxygen despite that there is no well-behaved trend with the binding energy of the island to the substrates.

1 microm double-stranded DNA molecules are immobilized between pairs of gold and pairs of platinum microelectrodes with gaps of 0.4 and 1 microm, respectively, and their electrical characteristics are determined under the application of constant and sinusoidal bias voltages. Due to their extremely high impedance for constant voltage bias, the samples of DNA are excellent insulators; however, their impedances show strong frequency dependence in the range of 10 Hz-7.5 MHz. Favorable response in the gold electrodes is attributed to the higher ability of DNA molecules to bridge the narrower gold electrode gaps in contrast to that in the wider platinum junctions.

Molecular potentials are unreadable and unaddressable by any present technology. It is known that the proper assembly of molecules can implement an entire numerical processing system based on digital or even analogical computation. In turn, the outputs of this molecular processing unit need to be amplified in order to be useful. We have developed a nanomicrointerface to read information encoded in molecular level potentials and to amplify this signal to microelectronic levels. The amplification is performed by making the output molecular potential slightly twist the torsional angle between two rings of a pyridazine, 3,6-bis(phenylethynyl) (aza-OPE) molecule, requiring only fractions of kcal/mol energies. In addition, even if the signal from the molecular potentials is not enough to turn the ring or even if the angles are the same for different combinations of outputs, still the current output yields results that resemble the device as a field effect transistor, providing the possibility to reduce channel lengths to the range of just 1 or 2 nm. The slight change in the torsional angle yields readable changes in the current through the aza-OPE biased by an external applied voltage. Using ab initio methods, we computationally demonstrate the amplification of molecular potential signals into currents that can be read by standard circuits.

We have demonstrated a qualitative relation between the electric characteristics and binding affinity of a complex receptor-ligand; a large binding affinity correlates with a large charge transfer. This allows us to analyze binding interactions of any complex using small computational resources with acceptable reliability of the results.

We develop an ab initio procedure for materials participating in electron transfer reactions, to consider biatomic backgrounds (e.g., substrates, catalysts, electrodes), thus the precise effects of the continuum and long-range interactions as well as the effects of the discrete and local nature of the chemistry can be combined to study molecules under such biatomic backgrounds. We test this new procedure by studying the reactivity of molecular oxygen on bimetallic clusters of platinum and cobalt. The reaction of molecular oxygen on the surface of the L1(2) phase of Co(3)Pt yields three distinct chemisorbed precursors, two of which are energetically almost degenerate. One precursor is formed across a bridge site with the molecule parallel to the surface, the second one is formed at the bridge with the molecule again parallel to the surface, and the third is formed in the threefold fcc hollow site, with the molecule slightly tilted in a top-hollow-bridge geometry.

We test a few ways to improve atomization energies of CHON molecules and found that the best way to do it is simply by correcting the atom energies of the participating atoms. Extraordinary improvement on the average errors is obtained. For the HF/6-31G** level of theory an average error of 271.2 kcal/mol on 115 molecules is improved to 6.7 kcal/mol simply by correcting the atomic energy of the four chon atoms. The corrections to density functional methods allow us to reach a chemical accuracy of 2 kcal/mol.