A detailed analysis of online pharmacy characteristics to inform safe usage by patients

Background: Evidence suggests that consumers potentially put themselves at risk when purchasing medicines on-line. Whilst logos provided by regulators may provide some level of reassurance there may be other indicators which could be used by consumers to identify those websites which may be safely used. Objectives: Identify characteristics of on-line pharmacies which are related to whether websites are regulated or non-regulated and those characteristics which could be used by patients to increase the likelihood of accessing regulated sites. Setting: Online pharmacies which supply diazepam, fluoxetine and simvastatin. Methods: Using piloted search terms via Google and Yahoo search engines, identified websites were screened for regulatory status, adherence to regulatory standards, administrative requirements, clinical assessment requirements and additional details deemed to be of relevance to a user. Characteristics of regulated and non-regulated (defined as those with an absence of a correctly linked regulatory logo) websites were compared to identify differences which could be used to improve patient safety. Main outcome measure: Regulatory status, adherence to regulatory standards, quality of information provision, barriers to medicines access. Results: 113 websites sold diazepam, fluoxetine and simvastatin; were identified within the first 100 results. Less than quarter were found to be regulated online pharmacies. 80 websites were willing to sell the medication without a prescription. The unregulated internet pharmacy websites (defined as those with an absence of a correctly linked regulatory logo) were found to adhere more closely to the clinical criteria, were less significantly likely to disclose a contact name and address, telephone number of the pharmacy or demand a prescription prior to sale (P\0.05, Fisher’s Exact). Conclusions: The three prescription-only medicines which are liable to abuse, have potentially serious interactions and require counselling to ensure patient safety are readily available via the internet. When purchasing medicines via this route UK consumers should be made aware of the importance of regulatory logos and additionally should ensure that the seller can be meaningfully contacted by the contact details provided. The provision of clinical information should not be used alone as an indication of the seller’s provenance

Interaction of gas molecules with Ti-benzene complexes

Using first-principles calculations based on gradient corrected density functional theory, we have studied the interaction of NH3, H2, and O2 with Ti-benzene complexes [Ti(Bz)2 and Ti2(Bz)2]. The energy barriers as the gas molecules approach the Ti-benzene complexes as well as the geometries of the ground state of these interacting complexes were obtained by starting with several initial configurations. While NH3 and H2 were found to physisorb on the Ti(Bz)2 complex, the O2 reacts with it strongly leading to dissociative chemisorption of the oxygen molecule. In contrast all the gas molecules react with the Ti2(Bz)2 complex. These studies indicate that the reaction of certain, but not all, gas molecules can be used to probe the equilibrium geometries of organometallic complexes. Under special conditions, such as high pressure, the Ti atom intercalated between benzene molecules in Ti(Bz)2 and the Ti2(Bz)2 complexes could store hydrogen in chemisorbed states. The results are compared to available experimental data

Ferromagnetism in Cr-doped GaN: A first-principles calculation

Electronic structure, energy bands, and magnetic properties of Cr-doped GaN have been calculated from first principles using a 32 atom supercell within the frame work of linearized muffin-tin orbital tight binding method and gradient-corrected density-functional theory. The coupling between Cr atoms is found to be ferromagnetic with a magnetic moment of 2.69μB at each Cr site. The magnetic moments of Ga and N sites are rather small, namely, 0.025μB and −0.025μB, respectively, yielding a total moment of 6μB per supercell. Parallel calculations done on small clusters of Cr-doped GaN also yield similar results indicating that magnetic coupling between Cr atoms results from a local phenomenon. These results are consistent with the recent experimental discovery of ferromagnetism in Cr-doped GaN single crystals

Magnetism in ZnO nanowire with Fe/Co codoping: First-principles density functional calculations

Using first-principles density functional calculations, at both generalized gradient approximation (GGA) and GGA+U levels we have investigated the electronic structure and magnetic properties of Fe/Co codoped ZnO nanowire. Here we have addressed some of the key issues such as, the preferable sites that Fe/Co can occupy, the coupling mechanism, and role of defects in coupling. We found that the spin alignment between the transition-metal atoms depends on their location. When Fe and Co atoms are nearest neighbors on the outer surface of the nanowire along [0001] direction is the lowest energy configuration with ferrimagnetic (FiM) ground state. At GGA level of description ferromagnetic ordering is observed when impurity atoms sit at surface and subsurface interface forming Fe-O-Co magnetic path, however at GGA+Ulevel of description antiferromagnetic superexchange interaction dominates and all configuration leads to FiM ground state. GGA+U are found to give more realistic description of electronics structure of Fe/Co codoped ZnO nanowire. Interestingly Fe-VO-Co defect configurations formed by removing the O atom from Fe-O-Co magnetic path are ferromagnetic when Fe-Co separation is less than 2.596 at GGA and 2.801 Å at GGA+U irrespective of the location of transition ions. We have also found that Co atom has a tendency to form clusters around Fe atom leading to inhomogeneous doping concentrations. O vacancy is found to be crucial in case of promoting ferromagnetism in this system. Two competing factors are the Ruderman-Kittel-Kasuya-Yosida (RKKY) type of exchange interaction in bulk environment due to O vacancy and direct exchange interaction of carriers due to Fe-VO-Codefect configuration on the surface

Origin of the anomalous magnetic behavior of the Fe13+ cluster

By using density functional theory, we show that the exceptionally low value of the total magnetic moment of Fe13+ observed in an experiment [Phys. Rev. Lett. 108, 057201 (2012)] is not due to antiferromagnetic coupling between the spins of the core and surface atoms as hypothesized but is due to the symmetry-driven quenching of the local spin moments of all atoms with the largest quenching observed for the central atom. Our study of Fe12+, Fe13+, Fe14+, and their neutral parents reveals that the total magnetic moment of Fe13+ decreases by 9μB with respect to that of neutral Fe13, whereas, the changes are 1μB and 3μB for Fe12+ and Fe14+, respectively

Electronic structure and chemical bonding of 3d-metal dimers ScX, X=Sc-Zn

The electronic and geometrical structures of the ground and excited states of the homonuclear Sc2, mixed ScTi, ScV, ScCr, ScMn, ScFe, ScCo, ScNi, ScCu, and ScZn 3d-metal dimers and their anions have been calculated using the density functional theory with generalized gradient approximation for the exchange-correlation potential. The ground states of the neutral dimers are found to be 5Σ−u (Sc2), 6Σ+ (ScTi), 7Σ+ (ScV), 4Σ+ (ScCr), 3Σ+ (ScMn), 2Δ(ScFe), 1Σ+ (ScCo), 2Σ+ (ScNi), 3Δ(ScCu), and 4Σ+ (ScZn). A natural bond analysis reveals an antiferrimagnetic spin coupling in the ground states of ScCr, ScMn, and ScFe. This is due to the electron transfer from Sc to the opposite atom and specific bond formations. While each dimer has a unique chemical bonding pattern, most curious is the localization of two 4s electrons at both atomic sites in the ground 5Σ−u state of Sc2, which leads to formation of two lone pairs and the bonding scheme: (3d+3d)3α(4s+4s)1β. No appreciable sd hybridization is found for the ground states of the ScX dimers except for ScNi. Even though the electron affinities of the ScX dimers are relatively low and do not exceed 1 eV, each ScX− (except ScCo−) possesses at least two states stable towards detachment of an extra electron

Electronic structure of chromium oxides, CrOn- and CrOn (n=1-5) from photoelectron spectroscopy and density functional theory calculations

The electronic structure of CrO−n and CrOn (n=1–5) was investigated using anion photoelectron spectroscopy and density functional theory. Photoelectron spectra of CrO−n were obtained at several photon energies and yielded electron affinities, vibrational and electronic structure information about the neutral CrOn species. Density functional theory calculations were carried out for both the neutrals and anions and were used to interpret the experimental spectra. Several low-lying electronic states of CrO were observed and assigned from photodetachment of the CrO− ground state(6∑+) and an excited state (4∏), which is only 0.1 eV higher. The main spectral features of CrO−2 were interpreted based on a C2v CrO−2 (4B1). A very weak Cr(O2)− isomer was also observed with lower electron binding energies. Relatively simple and vibrationally resolved spectra were observed for CrO−3, which was determined to be D3h. The CrO3 neutral was calculated to be C3v with the Cr atom slightly out of the plane of the three O atoms. The spectrum of CrO−4 revealed a very high electron binding energy. Several isomers of CrO−4 were predicted and the ground state has a distorted tetrahedral structure (C2) without any O–O bonding. Only one stable structure was predicted forCrO−5 with a superoxo O2 bonded to a C3v CrO3