Background and aimsStudies examining the next‐day cognitive effects of heavy alcohol consumption have produced mixed findings, which may reflect inconsistencies in definitions of ‘hangover’. Recent consensus has defined hangover as ‘mental and physical symptoms, experienced the day after a single episode of heavy drinking, starting when blood alcohol concentration (BAC) approaches zero’. In light of this, we aimed to review the literature systematically to evaluate and estimate mean effect sizes of the next‐day effects of heavy alcohol consumption on cognition.MethodsEmbase, PubMed and PsycNET databases were searched between December 2016 and May 2018 using terms based on ‘alcohol’ and ‘hangover’. Studies of experimental designs which reported the next‐day cognitive effects of heavy alcohol consumption in a ‘hangover’ group with BAC < 0.02% were reviewed. A total of 805 articles were identified. Thirty‐nine full‐text articles were screened by two independent reviewers and 19 included in the systematic review; 11 articles provided sufficient data to be included in the meta‐analysis; 1163 participants across 19 studies conducted since 1970 were included in the analysis. Data for study design, hangover severity, BAC at testing and cognitive performance were extracted and effect estimates calculated.ResultsThe systematic review suggested that sustained attention and driving abilities were impaired during hangover. Mixed results were observed for: psychomotor skills, short‐ (STM) and long‐term memory (LTM) and divided attention. The meta‐analysis revealed evidence of impairments in STM [g = 0.64, 95% confidence interval (CI) = 0.15–1.13], LTM (Hedges’ g = 0.59, 95% CI = 0.01–1.17) sustained attention (g = 0.47, 95% CI = 0.07–0.87) and psychomotor speed (Hedges’ g = 0.66, 95% CI = 0.31–1.00) during alcohol hangover.ConclusionThe research literature suggests that alcohol hangovers may involve impaired cognitive functions and performance of everyday tasks such as driving.

We report the fabrication of hybrid organic/inorganic semiconductor light-emitting devices that operate across the entire visible spectrum. The devices are based on a series of blue-, green-, and red-light-emitting polyfluorene materials that convert the emission from an array of micron-sized ultraviolet InGaN light-emitting diodes. We also demonstrate white-light-emitting versions of these hybrid devices by employing single films of carefully adjusted polyfluorene blends in which cascade energy transfer occurs between the constituent materials. The spectral and operating characteristics of the devices are described in detail. Such organic emission layer/inorganic light-emitting diode (LED) array based devices may provide a promising route to the fabrication of low-cost full-color microdisplays and other instrumentation devices.

No abstract

We present the highlights of a research programme on hybrid inorganic-organic light emitters. These devices combine recent developments in III-V nitride technology (including UV emitting micro-arrays and specifically tailored quantum wells) with conjugated polymers to access the entire visible spectrum. Two types of devices are studied, those based on down conversion of the quantum well emission by radiative transfer and those based on non-radiative resonant energy transfer. The spectral and operating characteristics of the devices are described in detail. Selectable colour micro-arrays and bar emitters are demonstrated. The nature of the non-radiative energy transfer process has also been studied and we find transfer efficiencies of up to 43% at 15 K, with a 1/R 2 dependence on the distance between quantum well and polymer layer, suggesting a plane-plane interaction. The relative importance of the non-radiative resonant energy transfer process increases with temperature to be up to 20 times more efficient, at 300 K, than the radiative transfer process.

Micropixelated blue (470 nm) and ultraviolet (370 nm) AlInGaN light emitting diode ('micro-LED') arrays have been fabricated in flip-chip format with different pixel diameters (72 microm and 30 microm at, respectively, 100 and 278 pixels/mm(2)). Each micro-LED pixel can be individually-addressed and the devices possess a specially designed n-common contact incorporated to ensure uniform current injection and consequently uniform light emission across the array. The flip-chip micro-LEDs show, per pixel, high continuous output intensity of up to 0.55 microW/microm(2) (55 W/cm(2)) at an injection current density of 10 kA/cm(2) and can sustain continuous injection current densities of up to 12 kA/cm(2) before breakdown. We also demonstrate that nanosecond pulsed output operation of these devices with per pixel onaxis average peak intensity up to 2.9 microW/microm(2) (corresponding to energy of 45pJ per 22ns optical pulse) can be achieved. We investigate the pertinent performance characteristics of these arrays for micro-projection applications, including the prospect of integrated optical pumping of organic semiconductor lasers.

We describe an optical sectioning microscopy system with no moving parts based on a micro-structured stripe-array light emitting diode (LED). By projecting arbitrary line or grid patterns onto the object, we are able to implement a variety of optical sectioning microscopy techniques such as grid-projection structured illumination and line scanning confocal microscopy, switching from one imaging technique to another without modifying the microscope setup. The micro-structured LED and driver are detailed and depth discrimination capabilities are measured and calculated.

We describe a single chip approach to time resolved fluorescence measurements based on time correlated single photon counting. Using a single complementary metal oxide silicon (CMOS) chip, bump bonded to a 4 × 16 array of AlInGaN UV micro-pixellated light-emitting diodes, a prototype integrated microsystem has been built that demonstrates fluorescence excitation and detection on a nanosecond time scale. Demonstrator on-chip measurements of lifetimes of fluorescence colloidal quantum dot samples are presented.

Using the method of photoresist reflow and inductively coupled plasma dry etching, we have fabricated microlens arrays in type-IIa natural single-crystal diamond, with diameters down to 10 µm. The surface profile of the microlenses was characterized by atomic force microscopy and was found to match well with a spherical shape, with a surface roughness of better than 1.2 nm. To characterize the optical properties of these diamond microlens arrays, a laser scanning reflection/transmission confocal microscopy technique has been developed. This technique enabled the surface profile of the microlenses to be measured simultaneously with optical parameters including focal length and spot size, opening up an application area for confocal microscopy