RESUMEN
The metastable and thermodynamically favored phases of CuFeS2 are shown to be alternatively synthesized during partial cation exchange of hexagonal Cu2S using various phosphorus-containing ligands. Transmission electron microscopy and energy dispersive spectroscopy mapping confirm the retention of the particle morphology and the approximate CuFeS2 stoichiometry. Powder X-ray diffraction patterns and refinements indicate that the resulting phase mixtures of metastable wurtzite-like CuFeS2 versus tetragonal chalcopyrite are correlated with the Tolman electronic parameter of the tertiary phosphorus-based ligand used during the cation exchange. Strong L-type donors lead to the chalcopyrite phase and weak donors to the wurtzite-like phase. To our knowledge, this is the first demonstration of phase control in nanoparticle synthesis using solely L-type donors.
RESUMEN
A series of strontium vanadium oxide-hydride phases prepared by utilizing a low-temperature synthesis strategy in which oxide ions in Sr(n+1)V(n)O(3n+1) (n=∞, 1, 2) phases are topochemically replaced by hydride ions to form SrVO2H, Sr2VO3H, and Sr3V2O5H2, respectively. These new phases contain sheets or chains of apex-linked V(3+)O4 squares stacked with SrH layers/chains, such that the n=∞ member, SrVO2H, can be considered to be analogous to "infinite-layer" phases, such as Sr(1-x)Ca(x)CuO2 (the parent phase of the high-T(c) cuprate superconductors), but with a d(2) electron count. All three oxide-hydride phases exhibit strong antiferromagnetic coupling, with SrVO2H exhibiting an antiferromagnetic ordering temperature, T(N)>300â K. The strong antiferromagnetic couplings are surprising given they appear to arise from π-type magnetic exchange.
RESUMEN
BACKGROUND: The Shar Pei is a common dog breed with a distinctive appearance caused by hyaluronosis that has been linked with several health conditions. Anonymised primary-care veterinary clinical records were explored to extract data on the demography, common disorders and mortality of Shar Pei in the UK in 2013. RESULTS: The study population of 455,557 dogs included 1913 (0.42%) Shar Pei. The mean adult bodyweight was 22.26 kg. The most prevalent fine-level precision disorders were entropion (prevalence 17.88%, 95% CI: 16.16-19.59), otitis externa (16.36%, 95% CI: 14.70-18.02), ear disorders (6.69%, 95% CI: 5.57-7.81), aggression (5.23%, 95% CI: 4.23-6.22), and pyoderma (4.29%, 95% CI: 3.38-5.19). The most prevalent disorder groups were ophthalmologic (prevalence = 22.27%, 95% CI: 20.40-24.13), dermatological (21.01%, 95% CI: 19.19-22.84), aural (18.66%, 95% CI: 16.92-20.41), traumatic injury (7.53%, 95% CI: 6.35-8.71) and behavioural (7.21%, 95% CI: 6.05-8.37). The median longevity of 190 Shar Pei that died during the study period was 7.28 years (IQR 5.04-10.05, range 0.04-15.04). Of 184 deaths with a recorded method of death, 157 (85.33%) deaths involved euthanasia and 27 (14.67%) deaths were unassisted. Among 136 (71.58%) deaths with a recorded biomedical cause of death, the most common causes of death at group level precision were neoplasia (15.44%, 95% CI: 9.37-21.51), renal disorders (13.24%, 95% CI: 7.54-18.93), and behavioural disorders (11.03%, 95% CI: 5.76-16.29). CONCLUSIONS: Almost one fifth of Shar Pei receive veterinary care each year for entropion, a condition linked strongly with the extreme conformation of thickened and folded skin and bristly hair that characterises the Shar Pei breed. Several other common disorders are also linked to hyaluronosis. Current UK legislation can help support efforts to avoid breeding or acquiring animals with extreme conformations and to promote adequate veterinary care for already-owned animals with extreme conformations.
The Shar Pei dog breed is instantly recognisable by their copious loose folded skin and bristly coat, with Shar Pei translating from Chinese as 'sand paper skin'. Although originally a fighting, hunting and guarding dog in China, the Shar Pei breed was re-invented in the US as a companion animal in the late 1970s where a more wrinkled and heavy-set American 'meat mouth' variety replaced the traditional 'bone mouth' variety originally popular in China. However, the underlying disease of hyaluronosis that causes the characteristic extreme appearance of the Shar Pei has also been linked with several other health problems in the breed such as in-turned eyelids (entropion) and ear disease. Using anonymised veterinary clinical records collected within the VetCompass Programme at the Royal Veterinary College (RVC), Shar Pei made up 0.4% of all dogs in the UK in 2013 and had an average adult bodyweight of 22 kg. The most common specific disorders diagnosed in Shar Pei were in-turned eyelids (17.88%), ear infection (16.36%), ear problems (6.69%), aggression (5.23%), and skin infection (4.29%). Among the 30 most common specific disorders, females were more likely to show in-turned eyelids and conjunctivitis, while males were more likely to show aggression and infected paws. Once the disorders were grouped, the most common disorder groups were eye disorders (22.27%), skin (21.01%), ear (18.66%), traumatic injury (7.53%), and behavioural (7.21%). The average lifespan of Shar Pei was 7.28 years. The most common causes of death were cancer (15.44%,), kidney disorders (13.24%), and behavioural disorders (11.03%). This study highlights that almost one fifth of the breed receive veterinary care each year for in-turned eyelids that can lead to extreme pain and are linked to the thickened and folded skin that humans find so appealing in this breed. Current UK legislation can help support concerted efforts from all animal welfare stakeholders to avoid breeding or acquiring animals with these and other extreme conformations and to promote adequate veterinary care for already-owned animals with extreme conformations.
RESUMEN
The capacity of fluorescent colloidal semiconductor nanocrystals for commercial application has led to the development of nanocrystals with nontoxic constituent elements as replacements for the currently available Cd- and Pb-containing systems. CuInS2 is a good candidate material because of its direct band gap in the near-infrared spectral region and large optical absorption coefficient. The ternary nature, flexible stoichiometry, and different crystal structures of CuInS2 lead to a range of optoelectronic properties, which have been challenging to elucidate. In this Perspective, the optoelectronic properties of CuInS2 nanocrystals are described and what is known of their origin is discussed. We begin with an overview of their synthesis, structure, and mechanism of formation. A complete discussion of the tunable luminescence properties and the radiative decay mechanism of this system is then presented. Finally, progress toward application of these "green" nanocrystals is summarized.