The relationship between the structure and the properties of a drug or material is a key concept of chemistry. Knowledge of the three-dimensional structure is considered to be of such...

When calculating derivatives of structure factors, there is one particular term (the derivatives of the atomic form factors) that will always be zero in the case of tabulated spherical atomic form factors. What happens if the form factors are non-spherical? The assumption that this particular term is very close to zero is generally made in non-spherical refinements (for example, implementations of Hirshfeld atom refinement or transferable aspherical atom models), unless the form factors are refinable parameters (for example multipole modelling). To evaluate this general approximation for one specific method, a numerical differentiation was implemented within the NoSpherA2 framework to calculate the derivatives of the structure factors in a Hirshfeld atom refinement directly as accurately as possible, thus bypassing the approximation altogether. Comparing wR 2 factors and atomic parameters, along with their uncertainties from the approximate and numerically differentiating refinements, it turns out that the impact of this approximation on the final crystallographic model is indeed negligible.

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Messy play helps to develop a child's sensory integration, however, some children avoid this type of provision. This article is based on research that aimed to find out how this aversion can be overcome.

In the field of crystallography, some crystals are not made of a single component but are instead twinned.In these cases, the observed intensities at some points in the lattice will be far larger than predictions. If we find the rotation associated to the twinned component, we can model this twin and improve our agreement with observations. In this report, we explore many routes to improve the process of identifying twins: Generation of fake data for better understanding and accurate testing. The representation of a rotation as defined by an axis and angle. The representation of a rotation as a quaternion. Using lattice points which must be equidistant from the origin to create our viable rotations. An algorithm focused on restricted possibilities. An exploration of 2D lattices for which twinning is mathematically impossible. We find that there is much to be investigated in the field of twinning.

A 47-year-old lady presented with a 6-year history of increasing refractory seizures and scoliosis despite trials of multiple anti-epileptic drugs(AEDs). She described seizures of temporal lobe(TLE) semiology provoked mainly by music which evoked elation. These musicogenic reflex seizures (MRS) were occurring up to twice weekly.CT and MRI brain, paraspinal EMG, and routine EEG were unremarkable. Provoked EEG captured a gen- eralised seizure with focal left mid-anterior temporal focus with rapid bilateral spreading within 2 minutes of playing a piece of music and lasted for 90 seconds, followed by a prolonged post-ictal phase. Auto- antibody screen revealed persistently elevated and rising serum GAD-Ab(glutamic acid decarboxylase antibodies) at 11618 U/mL with GAD positive on CSF testing. CT body, PET and transvaginal ultrasound revealed no significant abnormalities. Plasmapheresis was trialled with some effect.We present a rare case of GAD-Ab mediated MRS. MRS are well described, with 9% mediated by GAD-Ab. This mechanistically accounts for the limbic MRS semiology. We highlight the importance of GAD-Ab screening for refractory new onset TLE in an adult, with high serum GAD-Ab titre (≥2000 U/mL) and evidence of intrathecal synthesis. Unlike other immune-mediated epilepsies, GAD-Ab-mediated epilepsy responds poorly to AEDs and may require immunosuppression with rituximab or cyclophosphamide.References1. Kaplan, 2003; Falip et al., 2018, 2019; Tseng et al., 2018; Dade et al., 2020; Jesus-Ribeiro et al., 2020anishadoshi@doctors.org.uk|ABN Bursary

A variety of peripheral nerve disorders can be seen in association with lymphomas. We present a case of a 68-year-old female who presented with ten days history of rapid onset ascending paresthesias followed by unsteadiness. Neurological examination was remarkable for truncal ataxia with wide-based gait, large fiber sensory impairment (proprioception/vibration). There was some evidence of autonomic instability given labile blood pressure and tachycardia. MRI head and spine were unremarkable, as was the CSF. She was initially treated as acute ataxic variant of GBS with IVIG; however, there was continued clinical deterioration. Electrophysiology three weeks after symptom onset showed minimally delayed F waves, with normal sensory and motor NCS. Nerve Ultrasound revealed pronounced enlargement of C6 nerve root which was confirmed later with MRI of brachial plexus showing thickening and some enhancement of roots and trunks. Subsequent CT CAP and PET scan showed mediastinal, hilar and supraclavicular lymphadenopathy, though no PET uptake in the region of dorsal root ganglion. Biopsy of the right supra- clavicular node was consistent with an anaplastic large cell lymphoma.Atypical presentations of acute neuropathy can be attributed to GBS; however, they should include evalu- ation of a paraneoplastic process which can have similar acute presentations. This case also demonstrates the importance of nerve ultrasound which can be significantly abnormal in sensory neuronopathy with relatively normal electrophysiological testing.s_hasan_s@yahoo.com

In the field of crystallography, some crystals are not made of a single component but are instead twinned.In these cases, the observed intensities at some points in the lattice will be far larger than predictions. If we find the rotation associated to the twinned component, we can model this twin and improve our agreement with observations. In this report, we explore many routes to improve the process of identifying twins: Generation of fake data for better understanding and accurate testing. The representation of a rotation as defined by an axis and angle. The representation of a rotation as a quaternion. Using lattice points which must be equidistant from the origin to create our viable rotations. An algorithm focused on restricted possibilities. An exploration of 2D lattices for which twinning is mathematically impossible. We find that there is much to be investigated in the field of twinning.