Friction-formed liquid droplets.

The formation of nanoscale liquid droplets by friction of a solid is observed in real-time. This is achieved using a newly developed in situ transmission electron microscope (TEM) triboprobe capable of applying multiple reciprocating wear cycles to a nanoscale surface. Dynamical imaging of the nanoscale cyclic rubbing of a focused-ion-beam (FIB) processed Al alloy by diamond shows that the generation of nanoscale wear particles is followed by a phase separation to form liquid Ga nanodroplets and liquid bridges. The transformation of a two-body system to a four-body solid-liquid system within the reciprocating wear track significantly alters the local dynamical friction and wear processes. Moving liquid bridges are observed in situ to play a key role at the sliding nanocontact, interacting strongly with the highly mobile nanoparticle debris. In situ imaging demonstrates that both static and moving liquid droplets exhibit asymmetric menisci due to nanoscale surface roughness. Nanodroplet kinetics are furthermore dependent on local frictional temperature, with solid-like surface nanofilaments forming on cooling. TEM nanotribology opens up new avenues for the real-time quantification of cyclic friction, wear and dynamic solid-liquid nanomechanics, which will have widespread applications in many areas of nanoscience and nanotechnology.

Optometrists referrals for glaucoma assessment: a prospective survey of clinical data and outcomes.

AIM: The aim of this study is to determine the outcomes following referral for glaucoma from routine optometric practice and the positive predictive value (PPV). METHODS: A prospective study of 441 referrals for glaucoma in the Portsmouth area was performed over 6 months. A positive outcome was defined when the patient had the diagnosis of glaucoma made or if there was a high index of suspicion of glaucoma requiring follow-up. The PPV was determined from positive outcome number/referral number. RESULTS: The overall PPV was 0.37 (95% confidence interval 0.33-0.42). Open-angle glaucoma (OAG) was confirmed in 33 (7%) patients. A diagnosis of ocular hypertension was made in 49 (11%) patients and glaucoma suspect in 92 (21%) referrals. Two-thirds of optometrists recorded all 3 assessments: fields, intraocular pressure (IOP) and disc appearance, a figure representing 293 referrals (PPV 0.37). However the greatest referral accuracy was seen when only discs and IOPs were recorded (PPV 0.47). When all three tests were given as reasons for suspicion for glaucoma, the PPV was 0.71. The number of patients diagnosed with OAG from Portsea Island during the study period was 7, whereas the expected number of diagnosed patients was 29. CONCLUSION: Wider use of perimetry by optometrists and increased reporting of all three tests has not led to an increase in PPV. There remain a considerable number of undiagnosed patients with glaucoma in the population.

The formation of carbon nanostructures by in situ TEM mechanical nanoscale fatigue and fracture of carbon thin films.

A technique to quantify in real time the microstructural changes occurring during mechanical nanoscale fatigue of ultrathin surface coatings has been developed. Cyclic nanoscale loading, with amplitudes less than 100 nm, is achieved with a mechanical probe miniaturized to fit inside a transmission electron microscope (TEM). The TEM tribological probe can be used for nanofriction and nanofatigue testing, with 3D control of the loading direction and simultaneous TEM imaging of the nano-objects. It is demonstrated that fracture of 10-20 nm thick amorphous carbon films on sharp gold asperities, by a single nanoscale shear impact, results in the formation of <10 nm diameter amorphous carbon filaments. Failure of the same carbon films after cyclic nanofatigue, however, results in the formation of carbon nanostructures with a significant degree of graphitic ordering, including a carbon onion.

Nitrous oxide inhalation anaesthesia in the presence of intraocular gas can cause irreversible blindness.

Nitrous oxide inhalation sedation is frequently used in dental and other surgical procedures. We report the case of a patient with intraocular gas who developed sudden elevation in intraocular pressure and blindness as a result of nitrous oxide anaesthesia. All medical and dental personnel administering nitrous oxide inhalation should be aware that this is contraindicated in patients with intraocular gas.