Light Switch Research Articles

Recent Advances in Liquid Crystal/Polymer Composites and Their Applications in Reverse⁃mode Electrically Switchable Light⁃transmittance Controllable Films

Recent Advances in Liquid Crystal/Polymer Composites and Their Applications in Reverse⁃mode Electrically Switchable Light⁃transmittance Controllable Films

Bacterial Resistance to Disinfectants in common office areas

Introduction. The use of different chemical agents for the attenuation, treatment and control of microorganisms has been increasing, the lack of control and knowledge of these products is generating a change in the genome in microorganisms, causing resistance to normal concentrations of biocides. Objective: To carry out a systematic review on bacterial resistance to disinfectants in common office areas. Methods: Systematic review of databases; Scielo, Elsevier, Pubmed and ACS Publications research, and secondary sources such as PAHO (Pan American Health Organization) and WHO (World Health Organization), among others, using terms such as; Bacterial resistance, disinfection, occupational or professional diseases and resistance to disinfectants. Results: Enterobacter sp.: resistant to Quaternary Ammonium (QAC), halogen-based disinfectants and 37% formaldehyde; Pseudomonas aeruginosa: 71% of isolates multiresistant to antibiotics, 43% reduced susceptibility to QAC, triclosan (TC) and Benzalkonium (BAC), and 24 isolates resistant to antimicrobial agents. M. massiliense BRA 100 susceptible to orthophthaldehyde (OPA), peracetic acid (PA), and high concentrations of glutaraldehyde. Clinical isolates of multiresistant strains to antibiotics such as: MRSA, Enterococcus sp. and Pseudomonas aeruginosa, 52% and 38% strains were resistant to quaternary ammonium and phenol compounds, respectively. Conclusions: The presence of resistant microorganisms in common places such as; floors, light switches, door handles, desks and chairs, among others, enunciates a public health problem that must begin to be addressed, changing the methodologies used for disinfection, and other control and prevention measures.

Isolation of extensively drug resistant Acinetobacter baumannii from environmental surfaces inside intensive care units

Acinetobacter baumannii is a nosocomial pathogen that has emerged as a major threat in the health-care settings, particularly intensive care units (ICUs). The aim of this study was to investigate the prevalence of A. baumannii in the environment of intensive care and emergency units in 4 hospitals in Jordan. A total of 311 surface and 26 air samples were collected from 6 different ICUs and 2 emergency units. Examined high-touch surfaces included bed rails, sinks, food tables, trolley handles, ventilator inlets, blankets, sheets, door handles, light switches, bedside tables and drawers, curtains, normal saline stands and neonatal incubators. A. baumannii isolates were identified by CHROMagar and confirmed using 2 different PCR assays. All obtained isolates were characterized for their antibiotic resistance phenotypes, biofilm formation capacities and were typed by multi-locus sequence typing. Of the 337 samples, 24 A. baumannii isolates were recovered, mostly from surfaces in the internal medicine ICUs. Among the 24 isolates, 10 isolates were classified as extensively-resistant (XDR), harbored the blaOXA-23 like gene and able to form biofilms with varying capacities. ST2 was the most frequent sequence type, with all ST2 isolates classified as XDRs. Our results showed that high-touch surfaces of adult and pediatric ICUs were contaminated with XDR A. baumannii isolates. Therefore, the cleaning practices of the surfaces and equipment surrounding ICU patients should be optimized, and health-care workers should continuously wash their hands and change their gloves constantly to control the spread of this pathogen.

Light and Cation-Driven Optical Switch based on a Stilbene-Appended Terpyridine System for the Design of Molecular-Scale Logic Devices

A molecular system comprising a terpyridine moiety capable of coordinating with different cations and a photoswitchable stilbene unit has been utilized here for the fabrication of multiply configurable logic systems. Incorporation of a substituted stilbene unit into the terpyridine motif generates an intraligand charge-transfer-sensitive module whose absorption and emission spectral properties are highly sensitive to light as well as cations. On the basis of the optical response profile of the receptor in the presence of selected cations as well as light of a specific wavelength, we are able to demonstrate multiple Boolean logic functions such as INHIBIT, IMPLICATION, OR, NOR, and NAND, as well as various combinations of them. Of particular interest, we utilized the present system for the construction of security keypad locks and memory devices by maintaining a proper sequence of the stimuli and monitoring either absorption or emission spectral response at a specific wavelength as the output signal. In addition to various Boolean logic functions, the present system has also the ability to mimic fuzzy logic operations for generating an infinite-valued logic scheme depending on its emission spectral responses upon varying the concentration of cationic (Fe2+ and/or Zn2+) and anionic (CN-) inputs.

Robustness analysis framework for computations associated with building performance models and immersive virtual experiments

Building performance models (BPMs) have been used to simulate and analyze building performance during design. While extensive research efforts have made to improve the performance of BPMs, little attention has given to their robustness. Uncertainty is a crucial factor affecting the robustness of BPMs, in which such effect needs to be quantified through a suitable approach. The paper offers a robustness analysis framework for BPMs by using perturbation techniques to simulate uncertainty in input datasets. To investigate the efficacy of the framework, a generative adversarial network (GAN)-based framework was selected as a case study to analyze light switch usages in a single-occupancy office simulated using an immersive virtual environment (IVE). The robustness of the GAN was analyzed by comparing differences between a baseline (i.e., a BPM obtained from the GAN trained on a non-perturbed dataset) and BPMs obtained from the GAN trained on perturbed datasets. Overall, the robustness of the GAN significantly reduced when the training datasets were perturbed by using structured transformation techniques. The GAN remained relatively robust when the training datasets were perturbed by using an additive perturbation. Additionally, the sensitivity of the GAN involves different magnitudes corresponding to different levels of perturbed input datasets. The study suggests that the perturbation analysis is effective for investigating data uncertainty affecting the robustness of BPMs.

Junction Management for Connected and Automated Vehicles: Intersection or Roundabout?

The concept of signal-free management at road junctions is tailored for Connected and Automated Vehicles (CAVs), in which the conventional signal control is replaced by various right-of-way assignment policies. First-Come-First-Served (FCFS) is the most commonly used policy. In most proposed strategies, although the traffic signals are replaced, the organization of vehicle trajectory remains the same as that of traffic lights. As a naturally signal-free strategy, roundabout has not received enough attention. A key motivation of this study is to theoretically compare the performance of signalized intersection (I-Signal), intersection using FCFS policy (I-FCFS), roundabout using the typical major-minor priority pattern (R-MM), and roundabout adopting FCFS policy (R-FCFS) under pure CAVs environment. Queueing theory is applied to derive the theoretical formulas of the capacity and average delay of each strategy. M/G/1 model is used to model the three signal-free strategies, while M/M/1/setup model is used to capture the red-and-green light switch nature of signal control. The critical safety time gaps are the main variables and are assumed to be generally distributed in the theoretical derivation. Analytically, I-Signal has the largest capacity benefiting from the ability to separate conflict points in groups, but in some cases it will have higher delay. Among the other three signal-free strategies, R-FCFS has the highest capacity and the least average control delay, indicating that the optimization of signal-free management of CAVs based on roundabout setting is worthy of further study.

Electrochemical biosensor based on singlet oxygen generated by molecular photosensitizers

Here a sensing strategy with the integration of photosensitizer and electrochemical analysis was present. The photosensitizer, Zinc(II) tetraphenylporphyrin (ZnTCPP), was functionalized graphene oxide (GO) to form complex (ZnTCPP/GO) as the electrode material and generated singlet-oxygen (1O2) in the presence of air under light illumination. Due to the special electronic structure of 1O2, hydroquinone (HQ) could react with 1O2 to produce electrochemically-detectable products, benzoquinone (BQ). Meanwhile, the formed BQ could be reduced on the electrode, completing the redox cycling. The ZnTCPP/GO modified ITO electrode produces a stable and enhanced photocurrent signal under 420 nm irradiation in air-saturated buffer, compared with in N2-saturated buffer. On the other hand, l-glutathione (GSH) as a signalling molecule plays important role in physiological process, which was employed as model to investigated the sensing performance. Coupling with HQ oxidized by 1O2, a GSH sensor was constructed on the basis the redox cycling of HQ. A sensitive reduction of photocurrent is observed with the addition of GSH, due to the GSH could be oxidized by the generated 1O2 to form GSSG. The biosensor displayed good performance in a broad concentration range of 0–150 μM, with a lower detection limit of 1.3 μM at an S/N ratio of 3, and could be used in practical application. This work affords a platform for constructing the biosensor with 1O2 instead of enzyme via on/off light switching.

Detection of SARS-CoV-2 on Surfaces in Households of Persons with COVID-19.

SARS-CoV-2 transmission from contaminated surfaces, or fomites, has been a concern during the COVID-19 pandemic. Households have been important sites of transmission throughout the COVID-19 pandemic, but there is limited information on SARS-CoV-2 contamination of surfaces in these settings. We describe environmental detection of SARS-CoV-2 in households of persons with COVID-19 to better characterize the potential risks of fomite transmission. Ten households with ≥1 person with laboratory-confirmed COVID-19 and with ≥2 members total were enrolled in Utah, U.S.A. Nasopharyngeal and anterior nasal swabs were collected from members and tested for the presence of SARS-CoV-2 by RT-PCR. Fifteen surfaces were sampled in each household and tested for presence and viability of SARS-CoV-2. SARS-CoV-2 RNA was detected in 23 (15%) of 150 environmental swab samples, most frequently on nightstands (4/6; 67%), pillows (4/23; 17%), and light switches (3/21; 14%). Viable SARS-CoV-2 was cultured from one sample. All households with SARS-CoV-2-positive surfaces had ≥1 person who first tested positive for SARS-CoV-2 ≤ 6 days prior to environmental sampling. SARS-CoV-2 surface contamination occurred early in the course of infection when respiratory transmission is most likely, notably on surfaces in close, prolonged contact with persons with COVID-19. While fomite transmission might be possible, risk is low.

Could visual cues moderate the normative influence in promoting energy conservation? A perspective from the construal level

The socially normative influence on promoting energy conservation has received increasing support; however existing studies have largely ignored the potential impact of different visual cues in normative prompts. This current study examined the moderating role of visual cues on the normative influence in promoting energy conservation from a novel perspective of the construal level. The results of an experiment and a field study on campus show that the persuasiveness of descriptive normative appeal (i.e., what most others commonly do) tends to be more robust than injunctive appeal (i.e., what is socially approved). Moreover, there was a significant interaction effect between the construal level of visual cues and normative appeal. When presented with a high-construal-level visual cue (e.g., a light bulb with a green leaf in it), the descriptive (vs. injunctive) normative appeal could stimulate higher energy-saving intentions while both descriptive and injunctive normative appeals can positively affect actual energy-saving behavior. In contrast, when presented with a low-construal-level visual cue (e.g., an outstretched finger turning off a light switch), both descriptive and injunctive normative appeals can elicit higher energy-saving intentions; furthermore the descriptive (vs. injunctive) normative appeal is more effective in promoting actual energy-saving behavior; and, interestingly, the injunctive normative appeal could induce a negative effect. These results indicate a clear behavior-intention incongruence in response to injunctive normative appeals with different construed visual cues. Taken together, this research provides new support for the focus theory of normative conduct and the construal level theory and straightforward practical ways to promote energy conservation.

Ionic Liquid Electrolyte-Based Switchable Mirror with Fast Response and Improved Durability.

Electrochemically tunable devices based on reversible metal electrodeposition have attracted extensive attention for energy-saving smart windows, information displays, digital signage, and variable reflectance mirrors, owing to their excellent optical modulation characteristics, low operation voltage, and superb electrochemical stability. Here, we study the effects of ionic liquid (IL)-based electrolytes on electrodeposition of the reversible electrochemical mirrors (REMs) by changing the organic cations of the ILs to obtain devices with the desired spectroelectrochemical and electrodeposited properties. Spectroelectrochemical measurements and scanning electron microscopy images show that organic cations drastically affect the switching speed and cycling durability, which we proposed on the basis of the difference in the absorption energies between cations and Ag(111) surfaces. Higher adsorption energy indicates strong adhesion between organic cations and Ag(111) surfaces, and this strong adsorption would prevent aggregation and agglomeration during the nucleation of Ag nanoparticles (AgNPs), leading to a denser and more compact electrodeposited Ag film and faster switching speeds (3.3 s for coloring and 14.3 s for bleaching). These findings allow us to fabricate dynamic devices that exhibit reversibly switchable light modulation at fast switching speeds and excellent cycling stability over thousands of cycles without attenuation. The combination of rapid switching and durable cycling stability enables tunable windows, which are based on reversible electrodeposition of metal Ag and IL-based electrolytes, make REM devices a competitive and promising alternative to traditional intelligent response materials.

Effect of light switch illumination on total energy consumption

The question of the relevance of reducing energy consumption is considered. An assumption is made that in cases where indoor illuminated switches are used that control a group of lamps, currents of the order of microamperes flow in the lighting network in the switched-off mode.The regulatory documentation related to the normative indicators of illumination as well as the typical area of premises is analyzed, and on the basis of the listed data, the calculation of the minimum required luminous flux emitted by lamps is made. The normalized calculated luminous flux was divided by the luminous flux from one lamp, with the resulting ratio rounded up. This ratio is the approximate number of lamps. This number of lamps will enable to calculate the total current of the entire lighting network.The standard rates for the operating time of the lighting network are taken into account. The operating time of the lighting network in the "standby" mode is the difference between the total number of hours per day and the standard operating time of the lighting network.Knowing the power consumption and the network operation time in the "standby" mode, we can calculate the power consumption of the lighting network in the "standby" mode.

The light switch fallacy: Emergency management and recovery in an on-demand world.

Disasters typically do not abide by logical or standard rules and can be of any size or variety. But what is a disaster? How does time factor into dealing with the disaster? When will help arrive? How long will it take to recover? Why can everything not be fixed immediately? Television shows since the 1970s were instrumental in elevating public awareness of emergency service capabilities but also created a false expectation of expediency and un-implied over-exaggeration in capabilities. The speed of information from 21st century technology has created an immediacy of results expectation. People now expect the lights to come on when the switch is turned on and get impatient when that does not happen. This light switch fallacy is the expectation of what should occur in the rescue and recovery after a disaster. But the light switch cannot just be turned on, everything is solved, and life goes back to normal.

Exceptional-point-engineered cavity magnomechanics

We theoretically study the role of the exceptional point (EP) in a non-Hermitian cavity magnomechanical (CMM) system, with a tunable dissipative magnon-photon coupling. We find that the EP emerging in such a system can radically change the properties of photons and phonons. As a result, flexible on-off optical transmission, coherent switching of slow and fast lights, and enhanced mechanical cooling deep into the ground state can be achievable by approaching the EP. Detailed comparisons between this system and its Hermitian counterpart are given. Our results show that EP-assisted CMM devices can serve as tools for applications in optical communications and electromechanical switching or sensing.

Robust Photoelectric Biomolecular Switch at a Microcavity-Supported Lipid Bilayer.

Biomolecular devices based on photo-responsive proteins have been widely proposed for medical, electrical, and energy storage and production applications. Also, bacteriorhodopsin (bR) has been extensively applied in such prospective devices as a robust photo addressable proton pump. As it is a membrane protein, in principle, it should function most efficiently when reconstituted into a fully fluid lipid bilayer, but in many model membranes, lateral fluidity of the membrane and protein is sacrificed for electrochemical addressability because of the need for an electroactive surface. Here, we reported a biomolecular photoactive device based on light-activated proton pump, bR, reconstituted into highly fluidic microcavity-supported lipid bilayers (MSLBs) on functionalized gold and polydimethylsiloxane cavity array substrates. The integrity of reconstituted bR at the MSLBs along with the lipid bilayer formation was evaluated by fluorescence lifetime correlation spectroscopy, yielding a protein lateral diffusion coefficient that was dependent on the bR concentration and consistent with the Saffman–Delbrück model. The photoelectrical properties of bR-MSLBs were evaluated from the photocurrent signal generated by bR under continuous and transient light illumination. The optimal conditions for a self-sustaining photoelectrical switch were determined in terms of protein concentration, pH, and light switch frequency of activation. Overall, a significant increase in the transient current was observed for lipid bilayers containing approximately 0.3 mol % bR with a measured photo-current of 250 nA/cm2. These results demonstrate that the platforms provide an appropriate lipid environment to support the proton pump, enabling its efficient operation. The bR-reconstituted MSLB model serves both as a platform to study the protein in a highly addressable biomimetic environment and as a demonstration of reconstitution of seven-helix receptors into MSLBs, opening the prospect of reconstitution of related membrane proteins including G-protein-coupled receptors on these versatile biomimetic substrates.

Leveraging context-awareness for Internet of Things ecosystem: Representation, organization, and management of context

Present-day devices are becoming increasingly smarter than their predecessors. From a simple passive light switch to an intelligent wristwatch, great strides have been made in networking smart devices, creating an autonomous ecosystem, the so-called Internet of Things. In an increasingly information-driven world, context-awareness supports the intended applications as well as their constituent devices, making them conscious of and adaptive to the specific scenario in real-time. Moreover, heterogeneous devices in the Internet of Things ecosystem peruse disparate data formats and semantics, giving rise to interoperability and information sharing challenges. Context modeling is a core feature that facilitates interoperability and information sharing between applications. Although generic context models exist, they do not consider pertinent dimensions of context to provide a generic vocabulary, and therefore, they cannot be extended to generalize situations commonly encountered in the Internet of Things environment. An extensible, generic modeling and representation of context is required to manage pertinent context dimensions in various ecosystems by being dynamically aware of the situation. This paper presents Context Model for Internet of Things, an extensible and generic ontology-based context modeling approach that provides relevant information at the right time. This work encompasses Context Ontology for Internet of Things, an ontology-based context organization approach, which provides an abstract and overarching vocabulary that fosters knowledge reusability and sharing. The proposed model has been implemented and evaluated with a use case to validate its adaptability, effectiveness, and viability. Our evaluation based on generality, effectiveness, and consistency shows that the proposed model can effectively represent, organize, and manage the context in different Internet of Things ecosystems.

'Light up for all' - Building Knowledge on Universal Design Through Direct User Contact in Design Workshops.

For the creation of inclusive design solutions, designers require relevant knowledge about a diversity of users throughout the design process. Besides understanding users' needs and expectations, the ways in which users perceive and experience the environment contain valuable knowledge for designers. Since users' perceptions and experiences are mainly tacit by nature, they are much more difficult to communicate and therefore more difficult to externalize. Hence, more insight is needed into the ways designers can build knowledge on Universal Design through direct user contact. In a project called 'Light up for all' architecture students are asked to design a light switch and socket, elegant, usable and understandable to the greatest extent possible by everyone. Two workshops with user/experts are organized in the first stages of the design process in which students could gain insight into users' experiences and perceptions through direct contact. Three data collection techniques are used to analyze the teams' design processes: (1) a design diary, (2) observations of the workshops and (3) a focus group. By means of analyzing collected qualitative data, we have identified three different design aspects that affect designers' UD knowledge building process. First, findings give indications on values and limitations of working with selected design artefacts when externalizing users' experiences. Second, the value of stories clearly affected designers' deeper understanding about users' experiences. Finally, results show that in some situations, designers encountered contradictory information between observations and verbal conversations. These insights may help researchers to better understand designers' process of building knowledge on UD from users' experiences and perceptions, which may result in better incorporating users' experiences when designing for everyone.

A two-phase hybrid product design algorithm using learning vector quantization, design of experiments, and adaptive neuro-fuzzy interface systems to optimize geometric form in view of customers’ opinions

One of the most important characteristics of a modern product is the extent to which it meets the needs of customers to gain market share. The conceptual design methods of products based on customer requirements are often feature-based, in which several features are identified between different types of a product. According to customer demands, these features are tuned and the closest is selected as the optimum. The great variety of features of a present-day product can often make this difficult because finding these common features is very complicated or even impossible. To solve this problem, choosing the optimal design is divided into two phases: In the first phase, the main product is divided into some basic categories and according to the customers' opinion, one is selected as the category. In the second phase, the selection of common geometrical features between the members of the winning category is made. Then, the optimization process is done based on customer rating and the closest design to the mentioned rating is selected. The house light switch is used as a case study and the proposed algorithm is implemented on it. High customer satisfaction with the optimized final design, high response rate to survey forms, and the low number of incompatible data, all, indicate the suitability of the proposed algorithm with human interface characteristics, simplicity and efficiency in adapting the product to the customers' view. This method can be used for other industrial products and even for non-industrial products or services.

Thermoresponsive Nanocellulose Films as an Optical Modulation Device: Proof-of-Concept.

Flexible optoelectronic technologies are becoming increasingly important with the advent of concepts such as smart-built environments and wearable systems, where they have found applications in displays, sensing, healthcare, and energy harvesting. Parallelly, there is also a need to make these innovations environmentally sustainable by design. In the present work, we employ nanocellulose and its excellent film-forming properties as a basis to develop a green flexible photonic device for sensing applications. Cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) were used as matrix materials along with a black thermochromic pigment to prepare thermoresponsive hybrid films. Optical properties of nanocellulose films such as transparency and haze were tuned by varying pigment loading. Nearly 90% transparent CNF and CNC films could be tuned to reduce the transmission to as low as 4 and 17%, respectively. However, the films regained transparency to up to 60% when heated above the thermochromic transition temperature (31 °C). The thermoresponsive behavior of the prepared films was exploited to demonstrate an all-optical modulation device. Continuous infrared light (1300 nm) was modulated by using a 660 nm visible diode laser. The laser intensity was sufficient to cause a localized thermochromic transition in the films. The laser was pulsed at 0.3 Hz and a uniform cyclic modulation depth of 0.3 dB was achieved. The demonstrated application of functional nanocellulose hybrid films as a light switch (modulator) could be harnessed in various thermally stimulated sensing systems such as temperature monitoring, energy-saving, and anti-counterfeiting.

Double Free: A Promising Route toward Moisture-Stable Hypotoxic Hybrid Perovskites

Double Free: A Promising Route toward Moisture-Stable Hypotoxic Hybrid Perovskites

Is the Green Wave Really Green? The Risks of Rebound Effects When Implementing “Green” Policies

Traffic and transportation are main contributors to the global CO2 emissions and resulting climate change. Especially in urban areas, traffic flow is not optimal and thus offers possibilities to reduce emissions. The concept of a Green Wave, i.e., the coordinated switching of traffic lights in order to favor a single direction and reduce congestion, is often discussed as a simple mechanism to avoid breaking and accelerating, thereby reducing fuel consumption. On the other hand, making car use more attractive might also increase emissions. In this study, we use an agent-based model to investigate the benefit of a Green Wave in order to find out whether it can outweigh the effects of increased car use. We find that although the Green Wave has the potential to reduce emissions, there is also a high risk of heaving a net increase in emissions, depending on the specifics of the traffic system.