Magnetic susceptibilities, specific heat, and crystal structure of four S = 3/2, three-dimensional antiferromagnets

The zero-field, ac magnetic susceptibilities of single crystals of four S=3/2 trigonal salts containing the tris(1,2-diaminoethane)chromium(III) cation, [Cr(en)3]3+, and heat-capacity measurements on one of them, [Na(OH2)6][Cr(en)3]2Cl7, are reported. The crystal structures of two of them, [Na(OH2)6][Cr(en3]2Cl7 and [Na(OH)2)6][Cr(en)3]2Br6Cl, have been determined. They both belong to the trigonal P3¯cl space group, with a=11.513(2), c=15.566(6) Å; Z=2; and a=11.740(5), c=16.008(9) Å; Z=2, respectively, and contain discrete octahedral hexaquasodium (i) cations. The salt [K(OH2)6][Cr(en)3]2Cl7 appears to be isomorphous with its sodium analog, and [Cr(en)3]Cl3·3H2O belongs to the same space group. The magnetic measurements on the four salts extend over the temperature interval 60 mK to 4.2 K, and antiferromagnetic ordering is found in all of them. The zero-field-splitting energy is of the same order of magnitude as the magnetic exchange energy. The susceptibility data have been fitted with the parameters 2D/kB=-0.091(8) K, g?=1.994, g¿=1.988, and zJ/kB=-0.061(2) K for [Cr(en)3]Cl3·3H2O; 2D/kB=-0.058(8) K, g?=2.01, g¿=2.00, and zJ/kB=-0.068(4) K for [Na(OH2)6][Cr(en)3]2Cl7; 2D/kB =-0.060(8) K, g?=1.993, g¿=1.951, and zJ/kB=-0.046(4) K for [K(OH2)6][Cr(en)3]2Cl7; and 2D/kB=+0.064(8) K, g?=2.001, g¿=1.991, and zJ/kB=-0.066(4) K for [Na(OH2)6][Cr(en)3]2Br6Cl, where longitudinal (¿) and transverse (¿) refer to the unique threefold crystallographic axis. The ordering temperatures are 0.124(5), 0.116(5), 0.093(5), and 0.112(5) K, respectively. The easy axis for the chloride compounds lies parallel to the longitudinal axis, whereas the easy axis for the bromide lies in the transverse plane. Heat-capacity measurements on [Na(OH2)6][Cr(en)3]2Cl7 confirm that magnetic ordering takes place at 0.112(5) K. The heat-capacity curve and magnetic entropy calculations agree with the three-dimensional character of the ordering of an S=3/2, effective bcc magnetic lattice

Outcomes after Intensity-Modulated Compared with 3-Dimensional Conformal Radiotherapy with Chemotherapy for Squamous Cell Carcinoma of the Anal Canal

Purpose: We report our institution’s treatment techniques, disease outcomes, and complication rates after radiotherapy for the management of anal canal carcinoma with intensity-modulated radiotherapy (imrt) and concurrent chemotherapy relative to prior cases managed with 3-dimensional conformal radiotherapy (3D-crt). Methods: In a retrospective review of the medical records of 21 patients diagnosed with biopsy-proven stage i (23%), stage ii (27%), or stage iii (50%) squamous-cell carcinoma of the anal canal treated with curative chemotherapy and imrt between July 2009 and December 2014, patient outcomes were determined. Results for patients treated with 3D-crt by the same group were previously reported. The median initial radiation dose to the pelvic and inguinal nodes at risk was 45 Gy (range: 36–50.4 Gy), and the median total dose, including local anal canal primary tumour boost, was 59.4 Gy (range: 41.4–61.2 Gy). Patients received those doses over a median of 32 fractions (range: 23–34 fractions). Chemotherapy consisted of 2 cycles of concurrent fluorouracil–cisplatin (45%) or fluorouracil–mitomycin C (55%). Results: Median follow-up was 3.1 years (range: 0.38–6.4 years). The mean includes a patient who died of septic shock at 38 days. The 3-year rates of overall survival, metastasis-free survival, locoregional control, and colostomy-free survival were 95%, 100%, 100%, and 100% respectively. No patients underwent abdominoperitoneal resection after chemoradiotherapy or required diverting colostomy during or after treatment. Those outcomes compare favourably with the previously published series that used 3D-crt with or without brachytherapy in treating anal canal cancers. Of the 21 patients in the present series, 10 (48%) experienced acute grade 3, 4, or 5 toxicities related to treatment. Conclusions: The recommended use of imrt with concurrent chemotherapy as an improvement over 3D-crt for management of anal canal carcinoma achieves a high probability of local control and colostomy-free survival without excessive risk for acute or late treatment-related toxicities

Paradoxical effects of low dose MDMA on latent inhibition in the rat

The cognitive effects of MDMA ('Ecstasy') are controversial, particularly in the case of acute administration of low doses. Latent inhibition (LI) refers to the reduction in conditioning to a stimulus that has received non-reinforced pre-exposure, an effect typically abolished by amphetamines and enhanced by antipsychotics. LI enhancement has also been shown using the 5-HT reuptake blocker sertraline. In the present study, the effects of MDMA (6 mg/kg, known to increase 5-HT release) were tested using 10 and 40 pre-exposures to produce weak and strong LI in controls, respectively. MDMA (injected twice, prior to pre-exposure and conditioning) significantly enhanced LI in that the effect was clearly demonstrated after only 10 pre-exposures, when it was absent in the saline controls. On its own such a profile of action would be consistent with a procognitive effect of MDMA mediated by increased availability of 5-HT. However, paradoxically the same MDMA treatment reduced LI in the 40 pre-exposures condition. This component of action is likely attributable to MDMA's actions on catecholaminergic systems and is consistent with other evidence of its adverse effects. Moreover, there were small but significant reductions in 5-HT in medial prefrontal cortex (mPFC) and amygdala assayed 7 days post MDMA administration (2 × 6 mg/kg, 24 h apart)

On the tracks of the earliest dinosaurs: implications for the hypothesis of dinosaurian monophyly

From the record of dinosaurian skeletal remains it has been inferred that the origin and initial diversification of dinosaurs were rapid events, occupying an interval of about 5 million years in the Late Triassic. By contrast numerous reports of dinosauroid tracks imply that the emergence of dinosaurs was a more protracted affair extending through much of the Early and Middle Triassic. This study finds no convincing evidence of dinosaur tracks before the late Ladinian. Each of the three dinosaurian clades - Theropoda, Sauropodomorpha, Ornithischia - produced a unique track morphotype that appears to be an independent modification of the chirotherioid pattern attributed to stem-group archosaurs (thecodontian reptiles). The existence of three divergent track morphotypes is consistent with the concept of dinosaurian polyphyly but can be reconciled with the hypothesis of dinosaurian monophyly only by invoking many and rapid reversals in the locomotor anatomy of early dinosaurs. The origin of dinosaurs was not the correlate or consequence of any single event or process, be it global change, competitive replacement, or opportunism in the wake of mass extinction. Instead the origin of dinosaurs is envisaged as a series of three cladogenetic events over an interval of at least 10 million years and possibly as much as 25 million years. This scenario of dinosaurian polyphyly is as well-supported by fossil evidence as is the currently favoured view of dinosaurian monophyly