Breaking the limits of structural and mechanical imaging of the heterogeneous structure of coal macerals

The correlation between local mechanical (elasto-plastic) and structural (composition) properties of coal presents significant fundamental and practical interest for coal processing and for the development of rheological models of coal to coke transformations. Here, we explore the relationship between the local structural, chemical composition, and mechanical properties of coal using a combination of confocal micro-Raman imaging and band excitation atomic force acoustic microscopy for a bituminous coal. This allows high resolution imaging (10s of nm) of mechanical properties of the heterogeneous (banded) architecture of coal and correlating them to the optical gap, average crystallite size, the bond-bending disorder of sp(2) aromatic double bonds, and the defect density. This methodology allows the structural and mechanical properties of coal components (lithotypes, microlithotypes, and macerals) to be understood, and related to local chemical structure, potentially allowing for knowledge-based modeling and optimization of coal utilization processes.

Adverse ophthalmic reaction in poppers users: case series of 'poppers maculopathy'

BACKGROUND

Poppers are a recreational substance of abuse belonging to the alkyl nitrite family of compounds. In the United Kingdom, where they are legal to purchase but illegal to sell for human consumption, 10% of the general population have tried them. They are considered low risk to physical and mental health. Two recent case series from France demonstrated foveal pathology in individuals associated with poppers use.

METHOD

A case series of seven patients presenting to four hospitals in the United Kingdom with visual impairment and maculopathy associated with inhalation of poppers.

RESULTS

All patients experienced visual symptoms associated with poppers use. The majority had impaired visual acuity, central scotomata, distortion, or phosphenes. Clinical signs on fundoscopy ranged from normal foveal appearance to yellow, dome-shaped lesions at the foveola. Spectral domain optical coherence tomography (SD-OCT) showed varying degrees of disruption of the presumed inner segment/outer segment (IS/OS) junction.

DISCUSSION

Although poppers have been in use for several decades, in 2007, following legislative changes, there was a change in the most commonly used compound from isobutyl nitrite to isopropyl nitrite. There were no reports of 'poppers maculopathy' before this. Poppers maculopathy may be missed if patients are not directly questioned about their use. The disruption or loss of the presumed IS/OS junction on SD-OCT are a characteristic feature. Further study of maculopathy in poppers users is now needed. Raising public awareness of the ocular risks associated with their use may be necessary.

Can ophthalmic requests for neuroimaging be improved?

AIM

To review and set guidelines for all neuroradiological referrals from the ophthalmic service in a typical UK district general hospital.

METHOD

Patients referred for diagnostic neuroimaging were identified from the radiology database over a 1-year period. A case note review was undertaken. The clinical indication for and results of neuroimaging performed were ascertained. The justification for neuroimaging was determined.

RESULTS

Of the total 31,411 patients that were seen in the eye department, 103 (0.32%) had diagnostic neuroradiological imaging performed. The indications for imaging were: suspected compressive lesion of the anterior visual pathway in 57 patients (55.3%), acquired ocular motility disturbance in 20 patients (19.4%), suspected orbital pathology in 11 patients (10.6%), cerebrovascular accident in nine patients (8.7%), and six patients (5.8%) were imaged for either headache or sinusitis. Radiological lesion detection rate was highest for cerebrovascular accident (88.8%) and lowest acquired for ocular motility disturbance (4.9%).

CONCLUSION

Ophthalmic requests for diagnostic neuroimaging were found to be unnecessary in only 9% of patients. Guidelines for the referral of ophthalmic patients for neuroimaging are discussed.