A solvable model for excitonic complexes in one dimension

It is known experimentally that stable few-body clusters containing negatively-charged electrons (e) and positively-charged holes (h) can exist in low-dimensional semiconductor nanostructures. In addition to the familiar exciton (e+h), three-body 'charged excitons' (2e+h and 2h+e) have also been observed. Much less is known about the properties of such charged excitons since three-body problems are generally very difficult to solve, even numerically. Here we introduce a simple model, which can be considered as an extended Calogero model, to calculate analytically the energy spectra for both a charged exciton and a neutral exciton in a one-dimensional nanostructure, such as a finite-length quantum wire. Apart from its physical motivation, the model is of mathematical interest in that it can be related to the Heun (or Heine) equation and, as shown explicitly, highly accurate, closed form solutions can be obtained.Comment: 14 pages, 3 figures, To appear in J. Math. Phy

McStas and Mantid integration

McStas and Mantid are two well established software frameworks within the neutron scattering community. McStas has been primarily used for simulating the neutron transport of instruments, while Mantid has been primarily used for data reduction. We report here the status of our work done on the interoperability between the instrument simulation software McStas and the data reduction software Mantid. This provides a demonstration of how to successfully link together two software that otherwise have been developed independently, and in particular here show how this has been achieved for an instrument simulation software and a data reduction software. This paper will also provide examples of some of the expected future enhanced analysis that can be achieved from combining accurate instrument and sample simulations with software for correcting raw data. In the case of this work for raw data collected at large scale neutron facilities.Comment: 17 pages, 12 figures, POSTPRINT with proofs of article submitted to Journal of Neutron Researc

Building solids inside nano-space: from confined amorphous through confined solvate to confined ‘metastable’ polymorph

The nanocrystallisation of complex molecules inside mesoporous hosts and control over the resulting structure is a significant challenge. To date the largest organic molecule crystallised inside the nano-pores is a known pharmaceutical intermediate – ROY (259.3 g mol1). In this work we demonstrate smart manipulation of the phase of a larger confined pharmaceutical – indomethacin (IMC, 357.8 g mol1), a substance with known conformational flexibility and complex polymorphic behaviour. We show the detailed structural analysis and the control of solid state transformations of encapsulated molecules inside the pores of mesoscopic cellular foam (MCF, pore size ca. 29 nm) and controlled pore glass (CPG, pore size ca. 55 nm). Starting from confined amorphous IMC we drive crystallisation into a confined methanol solvate, which upon vacuum drying leads to the stabilised rare form V of IMC inside the MCF host. In contrast to the pure form, encapsulated form V does not transform into a more stable polymorph upon heating. The size of the constraining pores and the drug concentration within the pores determine whether the amorphous state of the drug is stabilised or it recrystallises into confined nanocrystals. The work presents, in a critical manner, an application of complementary techniques (DSC, PXRD, solid-state NMR, N2 adsorption) to confirm unambiguously the phase transitions under confinement and offers a comprehensive strategy towards the formation and control of nano-crystalline encapsulated organic solids

Bayesian probability theory applied to the space group problem in powder diffraction

Abstract. Crystal structure determination from powder diffraction data has become a viable option for molecules with less than 50 non-hydrogen atoms in the asymmetric unit and this includes the majority of compounds of pharmaceutical interes

Quality of life in chronic inflammatory demyelinating polyneuropathy patients treated with subcutaneous immunoglobulin

Background: Subcutaneous immunoglobulin (SCIG) is effective treatment of chronic inflammatory demyelinating polyneuropathy (CIDP). Quality of life (QoL) increases following switch from intravenous administration to SCIG, but its correlation with clinical functioning is sparsely studied. Aims of the study: The aim of this study is to evaluate the correlation between QoL and clinical functioning in CIDP patients treated with SCIG. Methods: Danish patients with CIDP with a disease duration &lt;10 years and currently treated with SCIG were eligible for inclusion. QoL was assessed with EQ-5D-5L and disability by the Overall Disability Sum Score (ODSS) and Rasch-built Overall Disability Scale (RODS). Gait performance was evaluated by a 40-meter-walk test (40-MWT) and a 6-spot-step test (6-SST) along with assessment of muscle strength (Medical Research Council score [MRC]). Correlations between QoL and the measured scores were calculated. Results: Of 92 eligible patients, 44 were included. QoL on the visual analogue scale (VAS) was 65% (range: 15-90) of the level of healthy controls (P =.03) and correlated to impaired gait function by 40-MWT and 6-SST. QoL correlated to RODS and ODSS, whereas there was no correlation with the MRC score. Conclusions: In SCIG treated CIDP patients QoL is reduced and correlates to gait performance and disability.</p

Association Between MScanFit Motor Unit Number Estimation and Clinical Function and Response to Immunoglobulin Therapy in Chronic Inflammatory Demyelinating Polyneuropathy

Background and Aims: Loss of motor units in chronic inflammatory demyelinating polyneuropathy is difficult to assess by conventional nerve conduction due to collateral innervation. We aimed to assess the association between a motor unit number estimate (MUNE) derived from the compound muscle action potential (CMAP) scan using MScanFit and hand function and the clinical response to intravenous immunoglobulin (IVIG). Methods: Forty-nine CIDP patients and 52 control subjects were included. CMAP scan recordings were obtained from the right abductor pollicis brevis muscle. The primary outcome was the correlation between MUNE and the duration of the nine-hole-peg test (9-HPT) at baseline and the change in the duration of the 9-HPT following treatment with IVIG. Secondary outcomes were grip strength, 10-m-walk test, six-spot-step test, medical research council sum score, inflammatory neuropathy cause and treatment sensory sum score, overall neuropathy limitations scale, and the Rasch-built overall disability scale (R-ODS). Results: MScanFit analysis suggested both loss of motor units (reduced MUNE (p = 0.022) and N50 (p &lt; 0.0001)) and collateral reinnervation (increased median amplitude (p &lt; 0.0001) and size of the largest unit (p &lt; 0.0001)) in CIDP patients compared to controls. In CIDP patients, there was a statistically significant correlation between MUNE and the duration of the 9-HPT (Spearman's r = −0.342; p = 0.016). Further, patients with a low MUNE had the largest reduction in the duration of the 9-HPT following IVIG treatment (r = −0.577; p = 0.043). MUNE also correlated significantly with R-ODS (r = −0.722; p = 0.007). Interpretation: MScanFit MUNE could be a useful method for assessing motor axonal loss in CIDP, which correlates with the clinical function and treatment response.</p

Changes in axonal and clinical function during intravenous and subcutaneous immunoglobulin therapy in chronic inflammatory demyelinating polyneuropathy

BACKGROUND AND AIMS: Intravenous immunoglobulin (IVIg) has a rapid clinical effect which cannot be explained by remyelination during each treatment cycle in patients with chronic inflammatory demyelinating polyneuropathy (CIDP). This study aimed to investigate axonal membrane properties during the IVIg treatment cycle and their potential correlation with clinically relevant functional measurements.METHODS: Motor nerve excitability testing (NET) of the median nerve was performed before and 4 and 18 days after initiation of an IVIg treatment cycle in 13 treatment-naïve (early) CIDP patients and 24 CIDP patients with long term (late) IVIg treatment, 12 CIDP patients treated with subcutaneous immunoglobulin (SCIg) and 55 healthy controls. Clinical function was measured extensively using the Six Spot Step test, 10-Meter Walk test, 9-Hole Peg test, grip strength, MRC sum score, Overall Neuropathy Limitations Score and Patient Global Impression of Change.RESULTS: Superexcitability and S2 accommodation decreased significantly in the early treatment group from baseline to day 4 and returned to baseline levels at day 18, suggesting temporary depolarization of the axonal membrane. A similar trend was observed for the late IVIg group. Substantial clinical improvement was observed in both early and late IVIg groups during the entire treatment cycle. No statistically significant correlation was found between clinical and NET changes. No change was found in NET or clinical function in the SCIg group or controls.INTERPRETATION: NET suggested temporary depolarization of the axonal membrane during IVIg treatment in treatment naïve CIDP patients. The relation to clinical improvement, however, remains speculative.</p