Exploring the solid state phase transition in dl-norvaline with terahertz spectroscopy.

dl-Norvaline is a molecular crystal at room temperature and it undergoes a phase transition when cooled below 190 K. This phase transition is believed to be Martensitic, thus making it of particular interest for molecular machines. In this paper we investigate this phase transition by measuring its terahertz (THz) spectrum over a range of temperatures. Temperature-dependent THz time-domain spectroscopy (THz-TDS) measurements reveal that the transition temperature (Tß→α) is 190 K. The influence of nucleation seeds was analyzed by determining the Tß→α of molecular crystals with varying grain size. Grains of 5 µm or less result in a lower transition temperature (Tß→α = 180 K) compared to larger grains of 125-250 µm (Tß→α = 190 K). Additionally, we gain insight into the physical process of the phase transition via temperature-dependent THz-TDS spectra of doped and mixed molecular crystals. The addition of molecular dopants, which differ from dl-norvaline only at the end of the side chain which resides in the hydrophobic layers of the crystal, decreases Tß→α. This is consistent with a solid-solid phase transition in which the unit cell shifts along this hydrophobic layer, and it leads us to believe that the phase transition in dl-norvaline is Martensitic in nature.

Terahertz spectroscopic polarimetry of generalized anisotropic media composed of Archimedean spiral arrays: Experiments and simulations.

Terahertz time-domain spectroscopic polarimetry has been used to measure the polarization state of all spectral components in a broadband THz pulse upon transmission through generalized anisotropic media consisting of two-dimensional arrays of lithographically defined Archimedean spirals. The technique allows a full determination of the frequency-dependent, complex-valued transmission matrix and eigenpolarizations of the spiral arrays. Measurements were made on a series of spiral array orientations. The frequency-dependent transmission matrix elements as well as the eigenpolarizations were determined, and the eigenpolarizations were found be to elliptically corotating, as expected from their symmetry. Numerical simulations are in quantitative agreement with measured spectra.

Effect of the nasal airflow inducing manoeuvre on olfaction and quality of life after laryngectomy.

OBJECTIVE: To assess the effectiveness of the nasal airflow inducing manoeuvre or 'polite yawn' technique in improving olfaction and quality of life in laryngectomised patients. METHODS: Using a prospective study design, 42 patients scheduled to undergo laryngectomy at a tertiary care centre were subjected to olfaction testing before surgery and two weeks following the surgery. The nasal airflow inducing manoeuvre was taught, and the olfaction test was repeated with the patient performing the nasal airflow inducing manoeuvre. Quality of life was assessed using the Appetite, Hunger and Sensory Perception questionnaire with calculation of scores after the patient had learnt the nasal airflow inducing manoeuvre. RESULTS: There was a significant reduction in the composite olfaction score, from a mean (standard deviation) baseline value of 4.01 (1.39) to 0.44 (0.51), two weeks after surgery (p < 0.001). After practising the nasal airflow inducing manoeuvre, the olfaction scores increased to 3.05 (1.32) (p < 0.001). Appetite, Hunger and Sensory Perception questionnaire scores ranged from 52 to 110 (normal range, 29-145), suggesting an improvement in the quality of life of patients. CONCLUSION: The nasal airflow inducing manoeuvre, an inexpensive, simple, patient-friendly manoeuvre, can be used in the olfaction rehabilitation of patients undergoing laryngectomy.

Extraordinarily long-ranged structural relaxation in defective achiral carbon nanotubes.

We present a systematic ab initio density functional theory-based study which demonstrates that even one of the simplest defects in single-wall carbon nanotubes, the reconstructed monovacancy (a pentagonal ring and a single dangling bond known as a 5-1db defect), leads to extraordinarily long-ranged structural distortions. We show that relaxation due to reconstruction can only be modeled accurately through a careful selection of boundary conditions and an appropriately long nanotube fragment.

Terahertz spectroscopy of enantiopure and racemic polycrystalline valine.

Experimental and computational THz (or far-infrared) spectra of polycrystalline valine samples are reported. The experimental spectra have been measured using THz time-domain spectroscopy. Spectra of the pure enantiomers, both D and L, as well as the dl racemate have been taken at room temperature and low temperature (78 K). The spectra of the pure D and L enantiomers are essentially identical, and they are markedly different from the DL racemate. In addition, a temperature-dependent study of L-valine was undertaken in which the absorption maxima were found to red shift as a function of increasing temperature. The vibrational absorption spectra (frequencies and intensities) were calculated using the harmonic approximation with the Perdew-Burke-Ernzerhof (PBE) functional, localized atomic orbital basis sets, and periodic boundary conditions. The calculated and experimental spectra are in good qualitative agreement. A general method of quantifying the degree to which a calculated mode is intermolecular versus intramolecular is demonstrated, with the intermolecular motions further separated into translational versus rotational/librational motion. This allows straightforward comparison of spectra calculated using different basis sets or other constraints.

Morphology control of nickel nanoparticles prepared in situ within silica aerogels produced by novel ambient pressure drying.

Silica aerogels are low density solids with high surface area and high porosity which are ideal supports for catalyst materials. The main challenge in aerogel production is the drying process, which must remove liquid from the pores of the wet gel while maintaining the solid network. In this work, the synthesis of silica aerogels and nickel-doped silica aerogels by a low energy budget process is demonstrated. Silica aerogels are produced by ambient drying using ammonium bicarbonate, rather than a conventional low surface tension solvent. Heating dissociates the ammonium bicarbonate, so generating CO2 and NH3 within the pores of the wet gel which prevents pore collapse during drying. Nickel-doped aerogels were produced by reducing nickel ions within pre-synthesised silica aerogels. The morphology of the resulting nickel particles-spheres, wires and chains-could be controlled through an appropriate choice of synthesis conditions. Materials were characterized using nitrogen adsorption/desorption isotherms, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis and X-ray diffraction. The surface area of undoped aerogel is found to increase with the concentration of ammonium bicarbonate salts from 360 to 530 m2 g-1, and that of nickel-doped silica aerogel varies from 240 to 310 m2 g-1 with nickel doping conditions.

Bioinspired Synthesis of Monolithic and Layered Aerogels.

Aerogels are the least dense and most porous materials known to man, with potential applications from lightweight superinsulators to smart energy materials. To date their use has been seriously hampered by their synthesis methods, which are laborious and expensive. Taking inspiration from the life cycle of the damselfly, a novel ambient pressure-drying approach is demonstrated in which instead of employing low-surface-tension organic solvents to prevent pore collapse during drying, sodium bicarbonate solution is used to generate pore-supporting carbon dioxide in situ, significantly reducing energy, time, and cost in aerogel production. The generic applicability of this readily scalable new approach is demonstrated through the production of granules, monoliths, and layered solids with a number of precursor materials.

Synthesis and Characterisation of Reduced Graphene Oxide/Bismuth Composite for Electrodes in Electrochemical Energy Storage Devices.

A reduced graphene oxide/bismuth (rGO/Bi) composite was synthesized for the first time using a polyol process at a low reaction temperature and with a short reaction time (60 °C and 3 hours, respectively). The as-prepared sample is structured with 20-50 nm diameter bismuth particles distributed on the rGO sheets. The rGO/Bi composite displays a combination of capacitive and battery-like charge storage, achieving a specific capacity value of 773 C g-1 at a current density of 0.2 A g-1 when charged to 1 V. The material not only has good power density but also shows moderate stability in cycling tests with current densities as high as 5 A g-1 . The relatively high abundance and low price of bismuth make this rGO/Bi material a promising candidate for use in electrode materials in future energy storage devices.

Successful outcomes following neurorehabilitation in military traumatic brain injury patients in the United Kingdom.

BACKGROUND: The Defence Medical Rehabilitation Centre Headley Court is the UK military rehabilitation unit. A pilot study identified the Mayo-Portland Adaptability Inventory-4 (MPAI-4) as the most appropriate rehabilitation outcome measure in young military patients with acquired brain injury. METHODS: MPAI-4 scores were prospectively recorded for patients on admission and discharge. At 4 months, independent living and employment status were recorded. Inclusion criteria were all new admissions with traumatic brain injury (TBI). Before injury, all patients were fully employed and lived independently. RESULTS: In a 3-year period from April 2011, there were 91 TBI patients with complete admission-discharge episodes: by US Department of Defense criteria, 21 were mild, 35 were moderate, and 35 were severe. There was a significant positive relationship between TBI severity and MPAI-4 score on admission (χ = 12.77, df = 2, p = 0.0017).Median age was 27 years, and median duration of admission was 63 days. Employment and independent living status were available for 79 patients at 4 months. Seventy-three patients (92%) were in community-based employment, with 64 (81%) employed in a competitive or transitional work; 6 (8%) were unemployed or in sheltered work. Sixty-nine (87%) were living independently, and 10 (13%) were living with support in their own home, with no one requiring institutional care.Complete MPAI-4 scores were available for 79 patients. There were statistically and clinically significant improvements in MPAI-4 scores between admission and discharge for the overall group: median admission T score was 40.0 (95% confidence interval, 36.0-42.0) and on discharge was 31.0 (95% confidence interval, 27.0-36.0), a nine-point change (Z = 6.53, p < 0.0001). These improvements with rehabilitation were sustained when patients were subdivided by TBI severity or MPAI-4 limitations. CONCLUSION: This study demonstrates significant functional improvements in military TBI patients following intensive inpatient multidisciplinary rehabilitation, which includes substantial vocational rehabilitation. At 4 months, 92% were employed, and 87% were living independently. LEVEL OF EVIDENCE: Therapeutic study, level V; prognostic/epidemiologic study, level IV.

The efficacy of dynamic slow motion video endoscopy as a test of eustachian tube function.

OBJECTIVE: To assess the efficacy of dynamic slow motion video endoscopy as a test of eustachian tube function based on its correlation with the eustachian tube swallow test. METHOD: The eustachian tube swallow test and dynamic slow motion video endoscopy were performed on 100 clinically normal middle ears of adults undergoing rigid nasal endoscopy for various indications. The dynamic slow motion video endoscopy findings were interpreted by three observers who were blind to the results of the eustachian tube swallow test, and the findings of both techniques were compared. RESULTS: There was a statistically significant correlation between the dynamic slow motion video endoscopy and eustachian tube swallow test results for some of the more lenient criteria. Five of the 100 eustachian tubes had a floppy medial cartilaginous lamina which appeared to contribute to the eustachian tube dysfunction. CONCLUSION: Dynamic slow motion video endoscopy appeared to over-diagnose eustachian tube dysfunction when used as a standalone test of eustachian tube function. However, when used in combination with other tests of eustachian tube function, it can provide valuable information regarding the structural and functional status of the pharyngeal end of the eustachian tube.

Intermolecular vibrations in hydrophobic amino acid crystals: experiments and calculations.

Intermolecular vibrations of amino acid crystals occur in the THz, or far-infrared, region of the electromagnetic spectrum. We have measured the THz and Raman spectra of DL-leucine as well as two polymorphs of DL-valine, the spectroscopic properties of which have not previously been compared. Theoretical modeling of intermolecular vibrations in hydrophobic amino acids is challenging because the van der Waals interactions between molecules are not accounted for in standard density functional theory. Therefore, to calculate the vibrational modes, we used a recently developed approach that includes these nonlocal electron correlation forces. We discuss methods for comparing results from different theoretical models using metrics other than calculated vibrational frequency and intensity, and we also report a new approach enabling concise comparison of vibrational modes that involve complicated mixtures of inter- and intramolecular displacements.

Unusual presentation of entomophthoromycosis.

Rhinoentomophthoromycosis caused by Conidiobolus sp commonly presents as a chronic granulomatous lesion that affects the rhinofacial subcutaneous tissue. We present an 18-year-old girl who presented with progressive bilateral proptosis and loss of vision since 2 weeks. Biopsy and fungal cultures confirmed diagnosis of Conidiobolus sp infection of the paranasal sinuses bilaterally with orbital extension and blindness. The clinical picture was complicated by the presence of sputum-positive cavitatory pulmonary tuberculosis, which was diagnosed at the same time. To our knowledge, this is the first such case to be reported from India. We also discuss the management of entomophthoromycosis. Despite many reports of success, there remains no consensus on the treatment of Conidiobolus infections of the nose and the paranasal sinuses with antifungal agents.

Successful use of recombinant activated coagulation factor VII in a patient with massive hemoptysis from a penetrating thoracic injury.

Acute massive hemoptysis is a rare complication of pulmonary injury and contusion, and it is particularly difficult to manage in the nontertiary care setting. Recombinant activated coagulation factor VII (rFVIIa) is a prothrombotic drug that is increasingly being used to treat coagulopathy in massively exsanguinating trauma patients. We report a case in which recombinant activated coagulation factor VII successfully controlled massive hemoptysis and improved ventilation from a severe pulmonary contusion in a noncoagulopathic patient who suffered a penetrating thoracic injury in a military setting in Afghanistan.

Risk-taking behaviour of young women in Australia: screening for health-risk behaviours.

Healthy risk-taking is a normal part of adolescence. Young people who participate in multiple risk-taking increase the chance of damaging their health. There appears to be a growing range and prevalence of health-risk behaviours among young women, notably in their use of alcohol and marijuana. Research suggests that such health-risk behaviours may be related to psychological factors such as stress and depression. General practitioners have a central role in identifying and preventing health-risk behaviours and associated mental health problems in young people. Comprehensive assessment includes a series of screening questions about home, education (or employment), activities, drugs, sexuality and suicide for young people, known as the HEADSS technique.