Red Green Research Articles

Robust RPPG Method Based on Reference Signal Envelope to Improve Wave Morphology

Remote physiological monitoring has become increasingly important in improving quality of life, with remote photoplethysmography (RPPG) being a popular choice. This paper introduces an envelope–based method for RPPG channels to improve wave morphology of the collected signal based on the reference signal from finger PPG. Using a model consistent with physiological and optical principles, the authors divided the signal into linear superpositions, comprising pulse, constant, and disturbance components. The correlation coefficients were used to calculate a linear combination of Red–Green–Blue (RGB) channels to approximate the envelope shape of the reference PPG signal. Experiments with different light intensities and stability were designed to compare the envelope approximation ability and robustness of the proposed method with some common methods. Analysis of variance demonstrated the stable performance of the envelopment–based approach in most cases. Additionally, it improved the morphology of the Green (G) channel, including changing trends and directions, adjusting wave sizes, reducing noise, and reinforcing details of the single waveform. The envelope–based linear model approach has the ability to flexibly improve RPPG signals, which helps RPPG play a full role in many fields such as medicine.

Assessing thermal imagery integration into object detection methods on air-based collection platforms

Object detection models commonly focus on utilizing the visible spectrum via Red–Green–Blue (RGB) imagery. Due to various limitations with this approach in low visibility settings, there is growing interest in fusing RGB with thermal Long Wave Infrared (LWIR) (7.5–13.5 µm) images to increase object detection performance. However, we still lack baseline performance metrics evaluating RGB, LWIR and RGB-LWIR fused object detection machine learning models, especially from air-based platforms. This study undertakes such an evaluation, finding that a blended RGB-LWIR model generally exhibits superior performance compared to independent RGB or LWIR approaches. For example, an RGB-LWIR blend only performs 1–5% behind the RGB approach in predictive power across various altitudes and periods of clear visibility. Yet, RGB fusion with a thermal signature overlay provides edge redundancy and edge emphasis, both which are vital in supporting edge detection machine learning algorithms (especially in low visibility environments). This approach has the ability to improve object detection performance for a range of use cases in industrial, consumer, government, and military applications. This research greatly contributes to the study of multispectral object detection by quantifying key factors affecting model performance from drone platforms (including distance, time-of-day and sensor type). Finally, this research additionally contributes a novel open labeled training dataset of 6300 images for RGB, LWIR, and RGB-LWIR fused imagery, collected from air-based platforms, enabling further multispectral machine-driven object detection research.

Control System for Indoor Safety Measures Using a Faster R-CNN Architecture

This paper presents a control system for indoor safety measures using a Faster R-CNN (Region-based Convolutional Neural Network) architecture. The proposed system aims to ensure the safety of occupants in indoor environments by detecting and recognizing potential safety hazards in real time, such as capacity control, social distancing, or mask use. Using deep learning techniques, the system detects these situations to be controlled, notifying the person in charge of the company if any of these are violated. The proposed system was tested in a real teaching environment at Rey Juan Carlos University, using Raspberry Pi 4 as a hardware platform together with an Intel Neural Stick board and a pair of PiCamera RGB (Red Green Blue) cameras to capture images of the environment and a Faster R-CNN architecture to detect and classify objects within the images. To evaluate the performance of the system, a dataset of indoor images was collected and annotated for object detection and classification. The system was trained using this dataset, and its performance was evaluated based on precision, recall, and F1 score. The results show that the proposed system achieved a high level of accuracy in detecting and classifying potential safety hazards in indoor environments. The proposed system includes an efficiently implemented software infrastructure to be launched on a low-cost hardware platform, which is affordable for any company, regardless of size or revenue, and it has the potential to be integrated into existing safety systems in indoor environments such as hospitals, warehouses, and factories, to provide real-time monitoring and alerts for safety hazards. Future work will focus on enhancing the system’s robustness and scalability to larger indoor environments with more complex safety hazards.

Removal of the Basic and Diazo Dyes from Aqueous Solution by the Frustules of Halamphora cf. salinicola (Bacillariophyta)

Industrial wastes with hazardous dyes serve as a major source of water pollution, which is considered to have an enormous impact on public health. In this study, an eco-friendly adsorbent, the porous siliceous frustules extracted from the diatom species Halamphora cf. salinicola, grown under laboratory conditions, has been identified. The porous architecture and negative surface charge under a pH of 7, provided by the various functional groups via Si–O, N–H, and O–H on these surfaces, revealed by SEM, the N2 adsorption/desorption isotherm, Zeta-potential measurement, and ATR-FTIR, respectively, made the frustules an efficient mean of removal of the diazo and basic dyes from the aqueous solutions, 74.9%, 94.02%, and 99.81% against Congo Red (CR), Crystal Violet (CV), and Malachite Green (MG), respectively. The maximum adsorption capacities were calculated from isotherms, as follows: 13.04 mg g−1, 41.97 mg g−1, and 33.19 mg g−1 against CR, CV, and MG, respectively. Kinetic and isotherm models showed a higher correlation to Pore diffusion and Sips models for CR, and Pseudo-Second Order and Freundlich models for CV and MG. Therefore, the cleaned frustules of the thermal spring-originated diatom strain Halamphora cf. salinicola could be used as a novel adsorbent of a biological origin against anionic and basic dyes.

The Use of Colour Indicator as a Smart Packaging for Monitoring Spoilage Fillet Catin Fish (Pangasius Sp.) In Room Temperature

The purpose of this research was to manufacture smart packaging made from pH color indicators Methyl Orange (MO), Methyl Red (MR), and Bromocressol Green (BCG) and analyze the best indicators in responding to the decline of quality fillet of Pangasius spp. Sensitivity indicators were tested with simulated gas amin issued by NH4OH for 30 minutes. They tested the color change of indicator in field trials conducted with sensitivity to the decline of quality fillet fish Pangasius sp. every 3 hours for 15 hours. Further tests were done on the fish to find the time of fish freshness with the pH, TPC, and organoleptic (SNI 2346:2006). The research results showed that all indicators could be used as packaging materials for smart packaging that decline the quality of pangasius sp. indicator made of BCG responds better than the others. Test results of testing indicators sensitivity with NH4OH showed that all indicators could be used as indicators. The results of testing the sensitivity indicator against the decline of the quality of the pangasius sp. fillets showed that the limit of the freshness of the fish used in this research is over 6th hours to 9th hour of storage where at the 9th, the color of the indicator changed, MO from pink to yellowish-orange, MM from deep red to yellowish-orange and BCG from pale yellow to blue. At 9 hours of storage, the results of RGB of MO, MR, and BCG are 190.00±0.46, 165.07±0.78 and 0.70±238.04 accordance with the decline of the quality of the fish assessed from the test results of pH value (7.54), TPC (5.74 X 10 6) and the organoleptic value of appearance (5.0), smell (4.5) and texture (5.0). In conclusion, indicators made of MO, MR, and BCG can be used as smart packaging to detect the deterioration of Pangasius sp., and indicators made of BCG can respond better than indicators of MO and MR.

Construction of alkalized MXene-supported CoFe2O4/CS composites with super-strong adsorption capacity to remove toxic dyes from aqueous solution

Owing to the unique surface microstructure, plentiful active sites and rich functional groups, two-dimensional transition metal carbide/nitride (MXene) is getting more and more attention in the field of pollutant removal. Now, we design a new magnetic adsorbent with CoFe2O4/chitosan (CS) composite supported onto alkalized MXene (alk-MXene) sheet using a facile hydrothermal and self-assembly technique. The structure and surface properties of the as-synthesized alk-MXene/CoFe2O4/CS composites are characterized by XRD, SEM, FTIR, TGA, BET and XPS. Batch experiments on adsorbing Congo Red (CR), Rhodamine B (RhB) and Malachite Green (MG) dyes are carried out, where the introduction of CoFe2O4/CS into alk-MXene can greatly enhance the adsorption capacity for cationic and anionic dyes. Notably, it is concluded that 24 h is a more suitable etching time to improve the adsorption performance of the composite during the synthesis process. An ultra-high adsorption capacity of S1 achieves up to 2095.9, 1333.9 and 537.6 mg g−1 for CR, RhB and MG dyes, respectively. The influence factors (etching time, pH values, contact time, initiate concentration and temperature) on the adsorption behaviors are discussed, where spontaneous and endothermic adsorption nature is confirmed. Analyses of the adsorption mechanism indicate that the synergistic effects of electrostatic interaction, π-π interaction and hydrogen bonding lead to superior adsorption abilities of the alk-MXene/CoFe2O4/CS composites. In a word, with the specific consideration on the advantages of MXene, CoFe2O4 and CS, this study offers a new track to obtain the MXene-based magnetic adsorbents with the simultaneous and high-efficiency removal of cationic and anionic dyes from the aqueous solutions.

Tectomer-Mediated Optical Nanosensors for Tyramine Determination.

The development of optical sensors for in situ testing has become of great interest in the rapid diagnostics industry. We report here the development of simple, low-cost optical nanosensors for the semi-quantitative detection or naked-eye detection of tyramine (a biogenic amine whose production is commonly associated with food spoilage) when coupled to Au(III)/tectomer films deposited on polylactic acid (PLA) supports. Tectomers are two-dimensional oligoglycine self-assemblies, whose terminal amino groups enable both the immobilization of Au(III) and its adhesion to PLA. Upon exposure to tyramine, a non-enzymatic redox reaction takes place in which Au(III) in the tectomer matrix is reduced by tyramine to gold nanoparticles, whose reddish-purple color depends on the tyramine concentration and can be identified by measuring the RGB coordinates (Red-Green-Blue coordinates) using a smartphone color recognition app. Moreover, a more accurate quantification of tyramine in the range from 0.048 to 10 μM could be performed by measuring the reflectance of the sensing layers and the absorbance of the characteristic 550 nm plasmon band of the gold nanoparticles. The relative standard deviation (RSD) of the method was 4.2% (n = 5) with a limit of detection (LOD) of 0.014 μM. A remarkable selectivity was achieved for tyramine detection in the presence of other biogenic amines, especially histamine. This methodology, based on the optical properties of Au(III)/tectomer hybrid coatings, is promising for its application in food quality control and smart food packaging.

Average daily intake of artificially food color additives by school children in Saudi Arabia

Food safety is related to nutritional risk in children. This study is to determine the types of artificial food color additives (AFCAs) daily intake by school children aged 6 to 17 years for ten AFCAs. Sunset Yellow (E110), Tartrazine (E102), Carmoisine (E122), Brilliant Blue (E133), Allura Red (E129), Black PN (E151), Indigo Carmine (E132), and Fast Green (E143) were identified using 24 h food consumption questionnaire, including the two unapproved AFCAs, Red 2G (E128) and Erythrosine (E127) in 839 food products. These food products are distributed into nine categories, containing juices and drinks, ice cream, cakes, jelly, chocolates, candy, chips, biscuits, and chewing gum. Results showed that the artificial food colors, Carmoisine (32.3 %) and Sunset Yellow (30.1 %) were the most highly consumed AFCAs by school children, whereas Erythrosine (0.05 %) was consumed the least. Therefore, Sunset Yellow was highly consumed (30.1 %) and detected in high amounts by high performance liquid chromatography, (HPLC) 34.2 %. The average daily intake (ADI) of AFCAs decreased with age to varying degrees in both sexes. In comparison to the Food and Agriculture Organization and World Health Organization, acceptable daily intakes, most permitted colors exceeded their acceptable daily intakes (ADIs) in the 6–11 years of age groups, and most permitted colors were within the recommended ADIs in the 12–17 years of age group. The average daily intake of AFCAs by school children decreased with age. Therefore, further studies are required to gain information about the possible negative health effects of high intake of these AFCAs on the test population.

A Simple but Effective Combination of pH Indicators for Plant Tissue Culture

The use of pH indicators provides a simple, semi-quantitative visual method for quickly assessing pH changes in tissue culture media; however, pH indicators are rarely used in routine plant tissue culture media. In this study, chlorophenol red, bromocresol purple, and bromocresol green were tested to assess their functionality in the growth medium for plant shoot cultures. In addition, a combination of bromocresol green and bromocresol purple was tested to determine if they would widen the observable colour change to better assess pH changes in the medium. Varying the ratio of bromocresol green to bromocresol purple alters the pH at which the colour changes from blue to green to yellow, with a 1:3 ratio providing a useful pH range of 5-6.5, while a 1:1 ratio provides a useful pH range of 4.5-6. All the pH indicators showed no toxic side effects for the plant species tested in this study and were able to be autoclaved to ensure media sterility. The addition of these pH indicators to quickly assess media pH in large tissue culture collections can aid in routine maintenance. These pH indicators can be used as a 'traffic light' system, with blue indicating a high pH, green a normal pH, and yellow a low pH in the media.

Automatic counting of rapeseed inflorescences using deep learning method and UAV RGB imagery.

Flowering is a crucial developing stage for rapeseed (Brassica napus L.) plants. Flowers develop on the main and branch inflorescences of rapeseed plants and then grow into siliques. The seed yield of rapeseed heavily depends on the total flower numbers per area throughout the whole flowering period. The number of rapeseed inflorescences can reflect the richness of rapeseed flowers and provide useful information for yield prediction. To count rapeseed inflorescences automatically, we transferred the counting problem to a detection task. Then, we developed a low-cost approach for counting rapeseed inflorescences using YOLOv5 with the Convolutional Block Attention Module (CBAM) based on unmanned aerial vehicle (UAV) Red-Green-Blue (RGB) imagery. Moreover, we constructed a Rapeseed Inflorescence Benchmark (RIB) to verify the effectiveness of our model. The RIB dataset captured by DJI Phantom 4 Pro V2.0, including 165 plot images and 60,000 manual labels, is to be released. Experimental results showed that indicators R2 for counting and the mean Average Precision (mAP) for location were over 0.96 and 92%, respectively. Compared with Faster R-CNN, YOLOv4, CenterNet, and TasselNetV2+, the proposed method achieved state-of-the-art counting performance on RIB and had advantages in location accuracy. The counting results revealed a quantitative dynamic change in the number of rapeseed inflorescences in the time dimension. Furthermore, a significant positive correlation between the actual crop yield and the automatically obtained rapeseed inflorescence total number on a field plot level was identified. Thus, a set of UAV- assisted methods for better determination of the flower richness was developed, which can greatly support the breeding of high-yield rapeseed varieties.

Energy Savings in Buildings Based on Image Depth Sensors for Human Activity Recognition

A smart city is a city that binds together technology, society, and government to enable the existence of a smart economy, smart mobility, smart environment, smart living, smart people, and smart governance in order to reduce the environmental impact of cities and improve life quality. The first step to achieve a fully connected smart city is to start with smaller modules such as smart homes and smart buildings with energy management systems. Buildings are responsible for a third of the total energy consumption; moreover, heating, ventilation, and air conditioning (HVAC) systems account for more than half of the residential energy consumption in the United States. Even though connected thermostats are widely available, they are not used as intended since most people do not have the expertise to control this device to reduce energy consumption. It is commonly set according to their thermal comfort needs; therefore, unnecessary energy consumption is often caused by wasteful behaviors and the estimated energy saving is not reached. Most studies in the thermal comfort domain to date have relied on simple activity diaries to estimate metabolic rate and fixed values of clothing parameters for strategies to set the connected thermostat’s setpoints because of the difficulty in tracking those variables. Therefore, this paper proposes a strategy to save energy by dynamically changing the setpoint of a connected thermostat by human activity recognition based on computer vision preserving the occupant’s thermal comfort. With the use of a depth sensor in conjunction with an RGB (Red–Green–Blue) camera, a methodology is proposed to eliminate the most common challenges in computer vision: background clutter, partial occlusion, changes in scale, viewpoint, lighting, and appearance on human detection. Moreover, a Recurrent Neural Network (RNN) is implemented for human activity recognition (HAR) because of its data’s sequential characteristics, in combination with physiological parameters identification to estimate a dynamic metabolic rate. Finally, a strategy for dynamic setpoints based on the metabolic rate, predicted mean vote (PMV) parameter and the air temperature is simulated using EnergyPlus™ to evaluate the energy consumption in comparison with the expected energy consumption with fixed value setpoints. This work contributes with a strategy to reduce energy consumption up to 15% in buildings with connected thermostats from the successful implementation of the proposed method.

Food Image Segmentation Using Multi-Modal Imaging Sensors with Color and Thermal Data

Sensor-based food intake monitoring has become one of the fastest-growing fields in dietary assessment. Researchers are exploring imaging-sensor-based food detection, food recognition, and food portion size estimation. A major problem that is still being tackled in this field is the segmentation of regions of food when multiple food items are present, mainly when similar-looking foods (similar in color and/or texture) are present. Food image segmentation is a relatively under-explored area compared with other fields. This paper proposes a novel approach to food imaging consisting of two imaging sensors: color (Red-Green-Blue) and thermal. Furthermore, we propose a multi-modal four-Dimensional (RGB-T) image segmentation using a k-means clustering algorithm to segment regions of similar-looking food items in multiple combinations of hot, cold, and warm (at room temperature) foods. Six food combinations of two food items each were used to capture RGB and thermal image data. RGB and thermal data were superimposed to form a combined RGB-T image and three sets of data (RGB, thermal, and RGB-T) were tested. A bootstrapped optimization of within-cluster sum of squares (WSS) was employed to determine the optimal number of clusters for each case. The combined RGB-T data achieved better results compared with RGB and thermal data, used individually. The mean ± standard deviation (std. dev.) of the F1 score for RGB-T data was 0.87 ± 0.1 compared with 0.66 ± 0.13 and 0.64 ± 0.39, for RGB and Thermal data, respectively.

Investigating Metals and Metalloids in Soil at Micrometric Scale Using µ-XRF Spectroscopy—A Case Study

Micrometric 2D mapping of distinct elements was performed in distinct soil grain-size fractions of a sample using the micro-X-ray Fluorescence (µ-XRF) technique. The sample was collected in the vicinity of São Domingos, an old mine of massive sulphide minerals located in the Portuguese Iberian Pyrite Belt. As expected, elemental high-grade concentrations of distinct metals and metalloids in the dependence of the existent natural geochemical anomaly were detected. Clustering and k-means statistical analysis were developed considering Red–Green–Blue (RGB) pixel proportions in the produced 2D micrometric image maps, allowing for the identification of elemental spatial distributions at 2D. The results evidence how elemental composition varies significantly at the micrometric scale per grain-size class, and how chemical elements present irregular spatial distributions in the direct dependence of distinct mineral spatial distributions. Due to this fact, elemental composition is more differentiated in coarser grain-size classes, whereas griding-milled fraction does not always represent the average of all partial grain-size fractions. Despite the complexity of the performed analysis, the achieved results evidence the suitability of µ-XRF to characterize natural, heterogeneous, granular soils samples at the micrometric scale, being a very promising investigation technique of high resolution.

Precision silviculture: use of UAVs and comparison of deep learning models for the identification and segmentation of tree crowns in pine crops

ABSTRACT The monitoring of trees is crucial for the management of large areas of forest cultivations, but this process may be costly. However, remotely sensed data offers a solution to automate this process. In this work, we used two neural network methods named You Only Look Once (YOLO) and Mask R-CNN to overcome the challenging tasks of counting, detecting, and segmenting high dimensional Red–Green–Blue (RGB) images taken from unmanned aerial vehicles (UAVs). We present a processing framework, which is suitable to generate accurate predictions for the aforementioned tasks using a reasonable amount of labeled data. We compared our method using forest stands of different ages and densities. For counting, YOLO overestimates 8.5% of the detected trees on average, whereas Mask R-CNN overestimates a 4.7% of the trees. For the detection task, YOLO obtains a precision of 0.72 and a recall of 0.68 on average, while Mask R-CNN obtains a precision of 0.82 and a recall of 0.80. In segmentation, YOLO overestimates a 13.5% of the predicted area on average, whereas Mask R-CNN overestimates a 9.2%. The proposed methods present a cost-effective solution for forest monitoring using RGB images and have been successfully used to monitor acres of pine cultivations.

Cerebral achromatopsia

AbstractChromatic sensitivity was assessed in patients with pregeniculate and postgeniculate lesions. We examine changes in central vision along at foveal fixation and in each of the four paracentral quadrants of the visual field using the Colour Assessment and Diagnosis (CAD) test, a dynamic luminance contrast masking technique that isolates the use of Red / Green (RG) and Yellow / Blue (YB) colour signals. Because the extraction of colour signals in early visual processing involves opponent mechanisms, subjects with congenital RG loss of sensitivity exhibit symmetric increase in thresholds towards the long wavelength (“red”) and middle wavelength (“green”) regions of the spectrum locus. This is also frequently the case with acquired loss of chromatic sensitivity as a result of retinal or optic nerve disease. The findings from this study represent an exception to this rule. The patients investigated showed a marked asymmetry in colour thresholds. The study reveals how discrete, localized damage to visual pathways can cause selective loss of visual function and how the latter varies with retinal topography.The 36 pregeniculate patients investigated exhibited impairment in both RG and YB. Loss of colour vision was symmetrical for both RG and YB discrimination. Some pregeniculate patients exhibited substantial loss of colour vision in areas where perimetric loss was largely absent. All quadrants revealed similar symmetric loss of colour sensitivity.In 23 patients with postgeniculate lesions, patients with pre‐striate damage exhibited symmetric loss of chromatic sensitivity which affected either one or both chromatic mechanisms. Striate or extra‐striate lesions tended to exhibit general loss of colour vision within the area identified by visual field testing. More specific chromatic loss was associated with less impaired areas that were often normal on perimetric testing. Some patients with striate or extra‐striate lesions presented with asymmetric chromatic loss for one or more colour categories. When striate or extra‐striate lesions were also accompanied by underlying pre‐striate damage, chromatic sensitivity loss was always symmetric.The findings from this study show that the loss of chromatic sensitivity in cerebral achromatopsia depends strongly on the exact location and extent of the lesion with significant variation over the visual field. The same subject can exhibit loss of chromatic sensitivity that is either RG or YB specific, but also, spatially localized, non‐opponent loss of sensitivity for primary colours.

Loss of colour vision in patients at risk of developing diabetes

AbstractRecent studies carried out in diabetic patients with no more than moderate maculopathy revealed that over 70% had significant losses of both Yellow/Blue (YB) and Red/Green (RG) colour vision (https://doi.org/10.1111/j.1755-3768.2012.F073.x). The purpose of this study was to investigate whether clinically ‘normal’ subjects, identified as being at ‘risk’ of developing diabetes show significant changes in rod‐ and cone‐mediated rapid flicker sensitivity as well as RG and YB colour vision.Three groups of subjects were recruited; a normal subject group (n = 40), a ‘high‐risk’ group (n = 150) and subjects diagnosed with diabetes (n = 23). The inclusion criteria for ‘high‐risk’ group required 3 or more recognized risk factors for diabetes (e.g., age > 45, HbA1C >5.7, high blood pressure, smoking history, high BMI, family history of diabetes, FPG levels >100 mg/dL). All subjects had full ophthalmic assessment and their RG and YB colour vision, Functional Contrast Sensitivity (FCS), Visual Acuity (VA) and Rod‐ and Cone‐mediated flicker sensitivity were measured using AVOT tests (https://researchcentres.city.ac.uk/applied-vision/avot).Consistent with previous findings, the diabetic group show significant loss of both RG and YB colour vision. Our findings show that these subjects also exhibit higher thresholds for rod and cone mediated vision. In addition, the ‘high‐risk’ group who are clinically classified as ‘normal’, also show significant loss of colour vision and rod and cone sensitivity. The latter group, do not, however, show significant differences in either VA or FCS. These findings suggest that accurate assessment of colour vision and rod‐ and cone‐ mediated rapid flicker sensitivity qualify as important risk factors in prediabetic screening.

Changes in visual function associated with hydroxychloroquine retinal toxicity

AbstractIntroduction: Non‐infectious inflammatory diseases, such as systemic lupus erythematosus, rheumatoid arthritis, dermatomyositis, antiphospholipid antibody syndrome and others cause significant morbidity and are treated with immunosuppression. Hydroxychloroquine (HCQ) sulfate is used as a second line immunosuppressant and has many advantages over other agents. These include increased life expectancy, reduced risk of neoplasia, reduced risk of diabetes and hypercholesterolaemia. HCQ is safe in pregnancy. After more than 5 years of treatment, HCQ can cause a degenerative maculopathy characterized by loss of parafoveal photoreceptors and RPE cells, leading to a ring‐like visual field defect. Current detection of early retinal toxicity relies on central visual field testing, optical coherence tomography (OCT) scan and fundus autofluorescence. The reason for the parafoveal predilection for retinopathy is not understood. HCQ is concentrated in melanin‐containing cells, and there is increased melanin concentration in the macular RPE cells. A hypothesis is that HCQ concentrated in the macular RPE cells leads to toxicity, with macular pigment protecting the fovea but leaving a ring of potentially vulnerable tissue in the parafoveal region. We were interested to investigate parafoveal function in patients with mild HCQ maculopathy and report the results of detailed macular function assessment of red/green (RG) and yellow / blue (YB) colour vision and rod‐ and cone‐mediated rapid flicker sensitivity.Methods: Two patients with confirmed early hydroxychloroquine maculopathy participated in the study. RG and YB colour thresholds were measured with the Colour Assessment and Diagnosis (CAD) test. Cone and rod‐mediated rapid flicker sensitivity was also measured in both central and paracentral vision using the Flicker‐Plus test. Both patients had taken HCQ for more than 15 years and had paracentral scotomas on 10–2 field test and loss of the parafoveal outer nuclear layer and ellipsoid layer, confirming the presence of maculopathy. To test the hypothesis of parafoveal toxicity risk, 20 short wavelength (BAF) and infrared wavelength (IRAF) autofluorescence images were reviewed. The BAF images are surrogate markers of the macular pigment and the IRAF the melanin concentration. Normalized maps of the difference between BAF and IRAF were calculated to investigate the possibility of a ring of vulnerable tissue.Results: Both patients had normal RG, but abnormal YB colour thresholds. One subject had normal cone flicker thresholds, but the rod flicker thresholds were raised in all quadrants in both eyes. The second subject had significantly elevated rod thresholds and elevated cone flicker thresholds in both eyes. Of note is that the degree of retinopathy in the second patient was greater than in the first. The areas of greatest threshold elevation correlated with the areas of greatest field loss and anatomical disruption on OCT.Conclusion: These new findings show that hydroxychloroquine retinopathy affects preferentially both YB colour vision and rod‐mediated flicker sensitivity. The cone‐mediated flicker sensitivity is also affected in more advanced disease. A model for the anatomical location of the toxicity will be presented, based on the hypothesis outlined above.

The value of colour assessment in diagnostic dilemmas

AbstractBackground: When the goal of clinical assessment is to segment, divide, and classify cases into neat discrete boxes it can often be frustrating to encounter cases which do not fit standard diagnosis algorithms. However, such diagnostic dilemmas often provide a valuable insight into the boundaries of current clinical procedures and the potential value psychophysical assessment can provide when used in conjunction with standard diagnosis algorithms. We present such a case involving localized retinal dysfunction that is not fully consistent with signs of either autoimmune retinopathy or occult maculopathy.Methods: Specific visual function loss was investigated in a health 32‐year‐old male with suspected localized retinal dysfunction, affecting the central retina. Blood tests and electro‐diagnostics were carried out after the patient presented with acute onset ‘foggy’ central vision. The working diagnosis from this initial visit was autoimmune retinopathy and oral steroids were prescribed. Following no change in symptoms a year after initially presenting, the patient was referred to City, University of London for bespoke assessments of specific visual functions. These included assessments of central and peripheral red / green (RG) and yellow / blue (YB) colour vision, mesopic visual acuity (VA), functional contrast sensitivity (FCS), rod‐ and cone‐mediated flicker sensitivity, and pupil responses measured using both rod‐ and cone‐enhanced stimuli.Results: The loss of vision affected primarily the central 20° with a mean VA of 6/36 in each eye. Fundus images, fluorescein angiography, and full field electroretinograms (ERGs) were normal, but pattern and focal ERGs were undetectable indicating localized dysfunction in central vision with OCT images showing a disrupted ellipsoid zone in each eye. The patient's mean corpuscular volume was 69 femtoliters, with red cell indices suggestive of thalassemia. Testing at City, University of London confirmed a loss of VA and FCS in the central 10° field, although both VA and FCS depended strongly on light level and were less affected with negative contrast stimuli. A loss of RG and YB colour vision was also measured centrally. Outside the central 10° field EA had almost normal colour and spatial vision. Rod‐ and cone‐mediated, flicker thresholds were elevated, with cone thresholds 10‐fold higher than normal. Pre‐stimulus pupil size, constriction amplitudes and latencies were normal with both centrally presented and peripheral stimuli.Conclusions: Psychophysical measurements in a patient with presumed autoimmune maculopathy showed atypical macular dysfunction that appears to preferentially affect negative contrast stimuli. Despite damage to the retinal mechanisms involved in spatial vision and light adaptation pupil responses remained unaffected. This unusual case highlights the importance of detailed phenotyping in understanding unknown aetiology.

Colour‐related, binocular interactions in patients with dyschromatopsia

AbstractWe report findings of monocular and binocular assessments of colour vision and thresholds for rod‐ and cone‐mediated sensitivity in two young patients (P1 and P2) diagnosed with monocular dyschromatopsia. Altered, monocular, colour perception with no clear diagnosis was reported in each patient based on results from a number of clinical visual assessment tests carried out over several years. Electrodiagnostic tests also revealed reduced Yellow / Blue (YB) chromatic sensitivity in P1. Both patients exhibited unexpected binocular interactions of colour signals. This abstract focuses mostly on the results obtained in P1, but similar results using the same visual assessment tests will also be presented for P2.P1 experienced visual discomfort, often manifested as differences between monocular and binocular viewing, noise‐like appearance of uniform fields and colours over the field, when viewed monocularly with either eye. As a result of these reports, we re‐examined P1's visual deficits using the Colour Assessment and Diagnosis (CAD) and the Flicker‐Plus (FP) tests (http://www.city-occupational.co.uk/). The FP test measures rod‐ and cone‐mediated rapid flicker sensitivity centrally (along the direction of gaze) and at 6 deg eccentricity in each of the four quadrants.Colour Vision. P1 shows significant loss of YB colour vision when tested monocularly in the right eye, but normal red‐green (RG) and YB colour vision in the left eye. When tested binocularly, P1 continues to show the same loss of YB colour vision observed when using only the right eye. These results were unexpected since P1 shows ‘normal’ binocular summation for both colour and flicker sensitivity, even when the thresholds are above the normal range.Rod‐ / Cone‐sensitivity. The patient's cone‐mediated, flicker sensitivity at all five locations investigated (under binocular viewing) was normal (with flicker detection thresholds, often under 2%), but only for the cone‐enhanced condition. When tested with rod‐enhanced stimuli, P1 shows much reduced sensitivity with larger thresholds in the periphery, but only in binocular viewing. Such responses have not been observed previously.In conclusion, P1 shows loss of YB colour vision in the right eye and also significant loss of rod‐mediated sensitivity at each of the five locations investigated. The patient's cone mediated thresholds, at every location tested, were consistently below the mean expected for normal trichromats, both binocularly and with each eye. The YB colour vision measured binocularly remained severely abnormal with thresholds similar to the right eye, in spite of normal colour vision in the left eye. Preliminary observations also suggest that the patient's colour and rapid flicker sensitivity can be affected by fatigue and other factors.Although patient, P2, varied significantly to P1 in monocular thresholds, a similar binocular, inhibitory interaction between the two eyes was observed when processing colour signals. These observations and the unusual interactions between signals derived from the two eyes point towards abnormal central processing of colour signals.

High-efficiency adsorption removal of CR and MG dyes using AlOOH fibers embedded with porous CoFe2O4 nanoparticles

Owing to the toxicity and difficulty in degradation, how to the effective separation for the residual dyes in the aqueous solution is still an issue with great challenge in the area of environmental protection. Now, to high-efficiency removal of organic dyes from the aqueous solution, we design a unique AlOOH/CoFe2O4 adsorbent with porous CoFe2O4 nanoparticles embedded on the AlOOH fibers using a simple hydrothermal technique and calcination process. The structural properties and surface characteristics of the AlOOH/CoFe2O4 composites are detailedly analyzed by XRD, FTIR, XPS, TEM and SEM. Here, the high SBET and specific porous structure are beneficial to improve the adsorption performance of AlOOH/CoFe2O4 adsorbents. Especially, when the molar ratio of AlOOH to CoFe2O4 in the AlOOH/CoFe2O4 fibers is 1:1, an optimal performance on adsorbing anionic Congo red (CR) and cationic methyl green (MG) dyes can be obtained at pH = 6.29, where the corresponding maximum adsorption capacities reach up to 565.0 and 423.7 mg g−1, respectively. Factors leading to the change in the ability of adsorbing CR and MG dyes are systematically discussed, including contact time, temperature, initial concentrations, and pH values of the solutions. Meanwhile, the uptake of CR and MG dyes can best conform to Langmuir isotherm model and pseudo-second-order adsorption kinetics. The thermodynamic analysis verifies that the dye adsorption process is spontaneous and endothermic. Moreover, from the point view of practical application, the good reusability further makes the as-synthesized magnetic AlOOH/CoFe2O4 composite be a perfect adsorbent with efficiently removing both anionic and cationic dyes from aqueous solutions.