Normal Laboratory Environment Research Articles

High Q-factor Polymer Microring Resonators Realized by Versatile Damascene Soft Nanoimprinting Lithography.

High-quality-factor microring resonators are highly desirable in many applications. Fabricating a microring resonator typically requires delicate instruments to ensure a smooth side wall of waveguides and 100-nm critical feature size in the coupling region. In this work, we demonstrate a new method "damascene soft nanoimprinting lithography" that can create high-fidelity waveguide by simply backfill an imprinted cladding template with a high refractive index polymer core. This method can easily realize high Q-factor polymer microring resonators (e.g., ~5 x 105 around 770 nm wavelength) without the use of any expensive instruments and can be conducted in a normal lab environment. The high Q-factors can be attributed to the residual layer-free feature and controllable meniscus cross-section profile of the filled polymer core. Furthermore, the new method is compatible with different polymers, yields low fabrication defects, enables new functionalities, and allows flexible substrate. These benefits can broaden the applicability of the fabricated microring resonator.

Preparation of electrochromic thin films by humidity-controlled spin coating

• Development of humidity-controlled spin-coating system using N 2 gas. • Variation of the film thickness in presence or absence of N 2 gas. • Doubled film thickness obtained in high humidity compared to low humidity. Spin coating has been used for various applications, such as the coating of resist solutions in semiconductor processes and the fabrication of functional thin films. By rotating at a high speed, thin films can be formed by centrifugal force. Since the film thickness can be controlled by the number of rotations and time, spin coating is often used for simple experiments at the laboratory. However, in a normal laboratory environment, i.e. not a clean room, temperature and humidity can vary depending on the season, time of day, and weather. In this study, we attempted to fabricate electrochromic WO 3 thin films using a spin coater, which we set up independently, that can control humidity. Compared to the WO 3 thin film deposited directly during the rainy season in Japan, the film thickness was doubled by controlling the humidity, even when deposited under the same spin-coating conditions. The WO 3 thin films prepared by this humidity-controlled process exhibited favorable electrochromic properties. Because, especially in systems containing volatile solvents, it was possible to control the film thickness and function during deposition by controlling the humidity, and the results of this research provide a reference to develop a convenient method for obtaining functional thin films regardless of the weather or season.

Automatic digital optical heterodyne phase locking loop in the milliradian domain for spaceborne laser interferometry.

We developed a digital optical phase locking loop (OPLL) with three advantages, including high precision of phase locking, high control bandwidth up to 2.8 MHz, and automatic laser locking strategy. Spaceborne laser interferometers will be used to measure tiny displacements caused by gravitational waves in millions of kilometers range. A slave laser will be heterodyne phase locked to the incoming weak light at the end of an arm, emitting a higher power light back to the other satellite to measure pathlength variations at the picometer level. Such accuracy requires extremely precise OPLL. We report an experiment to demonstrate a digital OPLL that can automatically lock two independent free-running Nd:YAG lasers with residual phase error below 1mrad/Hz above 0.01 Hz, which is the best performance recorded for digital servos, to our knowledge. Such performance tested under a normal laboratory environment will be highly improved in a vacuum environment with temperature and vibration well controlled. Both the digital OPLL and the automatic strategy were implemented on a field programmable gate array that could be potentially used for future gravitational-wave detection. Our experiment might change the thinking of scientists who study phasemeters of gravitational-wave detection because we are aware that the digital phase locking loop used for "optical phase tracking" is differently designed from "optical phase locking."

40 GHz waveguide-integrated two-dimensional palladium diselenide photodetectors

Hybrid integration of two-dimensional (2D) materials with photonic integrated circuits can enable additional functionality in planar waveguides based on excellent optical and electrical properties of 2D materials. 2D layered palladium diselenide (PdSe2) has a narrow energy bandgap and high carrier mobility, and its stability under normal laboratory environment conditions makes it of interest for use as high-performance infrared photodetectors. In this work, we propose and experimentally demonstrate a high-speed waveguide-integrated photodetector which uses chemical vapor deposition grown PdSe2 transferred onto a silicon waveguide. At 1550 nm wavelength, the photodetector can be operated without external bias with a responsivity of 0.57 mA/W and a responsivity of 20 mA/W at 6 V bias voltage. The detector had an impulse response full-width-half-maximum pulse width of about 11 ps, corresponding to a 3-dB bandwidth of 40 GHz.

Enhancing malaria control using Lagenaria siceraria and its mediated zinc oxide nanoparticles against the vector Anopheles stephensi and its parasite Plasmodium falciparum

In many developing countries, there are certain health problems faced by the public, one among them is Malaria. This tropical disease is mainly caused by Plasmodium falciparum. It is categorized as a disaster to public health, which increases both mortality and morbidity. Numerous drugs are in practice to control this disease and their vectors. Eco-friendly control tools are required to battle against vector of this significant disease. Nanotechnology plays a major role in fighting against malaria. The present paper synthesized Zinc oxide nanoparticles (ZnO NPs) using zinc nitrate via simple green routes with the help of aqueous peel extract of Lagenaria siceraria (L. siceraria). The synthesized ZnO NPs were characterized by various biophysical methods. Moreover, the extract of L. siceraria and their mediated ZnO NPs was experimented against III instar larvae of An. stephensi. The impact of the treatment based on ZnO NPs concerning histology and morphology of mosquito larval was further observed. In the normal laboratory environment, the efficiency of predation of Poeciliareticulata (P. reticulata) against An. Stephensi larvae was found to be 44%, whereas in aqueous L. siceraria extract and its mediated ZnO NPs contaminated environment, P. reticulate showed predation efficiency of about 45.8% and 61.13% against An. Stephensi larva. L. siceraria synthesized ZnO NPs were examined against the Plasmodium falciparum CQ-sensitive strains. The L. siceraria extract and its mediated ZnO NPs showed the cytotoxic effects against HeLa cell lines with an IC50 value of 62.5 µg/mL. This study concludes that L. siceraria peel extract and L. siceraria synthesized ZnO NPs represent a valuable green option to fight against malarial vectors and parasites.

Site-specific specimen preparation for SIMS analysis of radioactive samples.

Secondary Ion Mass Spectrometry is an important technique for the study of the composition of a wide range of materials because of the exceptionally high sensitivity that allows the study of trace elements and the ability to distinguish isotopes that can be used as markers for reactions and transport processes. However, when studying nuclear materials, it is often necessary to analyse highly radioactive samples, and only rather few SIMS facilities are available in active environments. In this paper, we present a methodology using focussed ion beam milling to prepare samples from radioactive specimens that are sufficiently large to undertake SIMS mapping experiments over microstructurally significant regions, but with overall activities small enough to be readily transported and analysed by a SIMS instrument in a normal laboratory environment. Radioactive samples prepared using this methodology can also be used for correlative SIMS analysis with other analytical microscopies. SIMS results showing the distributions of deuterium in oxides on in-reactor corroded zirconium alloys are presented to demonstrate the potential of this sample preparation technique.

Highly durable antifogging coatings resistant to long-term airborne pollution and intensive UV irradiation

Antifogging coatings have tremendous application potential as they can prevent undesired fogging and blurring on transparent substrates when exposed to humid environment. However, most antifogging surfaces suffer from poor durability and tend to lose the antifogging property in the short term caused by airborne pollutant adsorption or environment weathering (e.g., UV irradiation). To address this issue, a series of zwitterionic and hydroxylated superhydrophilic coatings were prepared and their long-term antifogging properties under harsh conditions were systematically studied, including in a normal laboratory environment, under accelerated pollution test by exposing surfaces to acetic acid steam, and under UV irradiation. The prepared zwitterionic coatings showed significantly improved durability than the hydroxylated surfaces in all the test conditions, attributed to the chemical inertness and stability of the zwitterionic moieties. By incorporating zwitterionic coating and nanoscale roughness together, the longevity of antifogging surfaces can be further greatly improved, and eyeglasses treated with such nanostructured zwitterionic coating kept decent antifogging property even after storage for up to 210 days. The present nanostructured zwitterionic coatings are promising for real-world antifogging applications that can survive practical environmental fouling and weathering.

Biogenic Nanoparticles of Calcium Carbonate - Preparation and Behaviour

Calcium carbonate is one of the most widespread natural material. Biogenic calcium carbonate nanoparticles are biocompatible. Currently, they are of great interest for their possible applications, especially in medicine. The aim of this introductory experimental study is to present a simple preparation of biogenic nanoparticles of calcium carbonate from natural resources with a subsequent specific behaviour of nanoparticles in aquatic environment. Different type of shells were used for the preparation of nanoparticles. All structures were burned at 850°C and then grounded to powder. The obtained powders were left in normal laboratory environment for 2 weeks and then placed in beakers with distilled water. Subsequently, two homogenization routes were used - stirring at 1000 rpm for 5 minutes and ultrasonic stirring for 5 minutes. One part of the particles was separated at the bottom of the beaker, but small formations started to create a fractal structure on the surface of water. These formations gradually increased. Crystalline interconnected structures built up with nanoparticles were confirmed by a subsequent analysis by a scanning electron microscope. EDX analysis confirmed the presence of calcium carbonate.

Evaluate severe acute respiratory syndrome coronavirus 2 infectivity by pseudoviral particles.

Since the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection in humans in late 2019, it has rapidly spread worldwide. To identify the biological characteristics of SARS‐CoV‐2 in a normal laboratory environment (biosafety level 2 [BSL‐2]), a lentiviral‐based nucleocapsid was used to carry the spike protein of SARS‐CoV‐2 onto the surface of pseudoviral particles as a surrogate model to evaluate the infective characterization of SARS‐CoV‐2. This study indicated that SARS‐CoV‐2 has extensive tissue tropism for humans and may infect monkeys and tree shrews but not rodents. More importantly, the use of pseudoviral particles in this study allows rapid assessment of neutralizing antibodies in serum in a BSL‐2 laboratory. This study will provide a quick and easy tool for evaluating neutralizing antibodies in the serum of recovering patients and assessing the potency of candidate vaccines.

Validation of a low-cost inertial motion capture system for whole-body motion analysis

While some low-cost inertial motion capture (IMC) systems are now commercially available, generally, they have not been evaluated against gold standard optical motion capture (OMC). The objective was to validate the low-cost Neuron IMC system with OMC. Whole-body kinematics were recorded on five healthy subjects during manual handling of boxes for about 32 min while wearing 17 magnetic and inertial measurement units with Optotrak clusters serving as a reference. The kinematical model was calibrated anatomically for OMC and with poses for IMC. Local coordinate systems were aligned with angular velocities to dissociate differences due to technology or kinematical model. Descriptive statistics including the root mean square error (RMSE), coefficient of multiple correlation (CMC) and limits of agreement (LoA) were applied to the joint angle curves. The average technological error yielded 5.8° and 4.9° for RMSE, 0.87 and 0.96 for CMC and 0.4 ± 8.6° and −0.3 ± 6.0° for LoA about the frontal and transverse axes respectively, whereas the longitudinal axis yielded 10.5° for RMSE, 0.78 for CMC and 3.3 ± 13.1° for LoA. Differences due to technology and to the model contributed similarly to the total difference between IMC and OMC. For many joints and axes, RMSE stayed under 5°, CMC over 0.9 and LoA under 10°, especially for the transverse axis and lower limb. The Neuron low-cost IMC system showed potential for tracking complex human movements of long duration in a normal laboratory environment with a certain error level that may be suitable for many applications involving large IMC distribution.

BOND DURABILITY OF STEEL PLATE TO CONCRETE PRISM USING STRUCTURAL ADHESIVES AFTER EXPOSURE TO 7-YEARS IN LABORATORY ENVIRONMENT

Structural integrity and durability has long been an area of study that is critical in order to ensure structures such as buildings, bridges etc. are safe enough to stand erected for many years. The technique of bonding steel plates to the surface of concrete using epoxy adhesives system has been used on a number of structures throughout the world to enhance load transferring capability. Deterioration in strength of concrete structures due to corrosion of steel can cause premature failure in existing structures or buildings. The objective of this study is to investigate the bond performance of steel to concrete using structural epoxy system. The sample at hand was prepared and left exposed for 7 years under normal ambient laboratory environments. This study focused on the outcome of bond performances of the bonded steel plate to concrete prism under pull out load. The sample (SPECS-7) that used in this study is approximately 7 years old with the steel plates surfaces was corroded and being compared with sample (SPECS-1) tested in 2008. The maximum load and maximum extension recorded at failure by sample SPECS-7 is 76.85kN and 3.04 mm at 181.8s which shows a decrease by 7 kN or 8% and 5.70 mm to 3.04 mm or 46% compared with sample SPECS-1 respectively. The extension comparison with SPEC-1 shows a reduction from 5.70 mm to 3.04 mm which is about 46 % less. There was significant amount of corrosion developed over the years which does not show to have affected the overall performance of the bonded system. Nevertheless, there was on average a small increase in bond strength with time although the controlled sample failed at a marginally lower load

Correlation processing and its use to mitigate the effects of multipath and other interfering signals in antenna ranges

Correlation processing has previously been used in radio communication systems to measure and characterise multipath environments, but it can equally well be applied to the elimination of multipath effects. The authors review the historical development of the technique in the context of its earlier use, and the background to its implementation as a method of eliminating or at least substantially reducing, the effects of multipath in antenna ranges. Correlation processing, which can be implemented either as a one-step, real-time process or used as a post-measurement option, also suppresses the effects of coherent and non-coherent interfering signals, so that the accuracy of antenna pattern measurement is greatly improved. At centimetre and millimetre wavelengths, it is possible to make accurate measurements in a normal laboratory environment without the need for an anechoic chamber. A simple proof-of-concept practical system is described, and example results are presented to demonstrate the validity of the technique and to compare it with time gating.

Extinction measurement with open-path cavity ring-down technique of variable cavity length.

Open-path cavity ring down (OPCRD) technique with variable cavity length was developed to measure optical extinction including scattering and absorption of air in laboratory environment at 635 nm wavelength. By moving the rear cavity mirror of the ring-down cavity to change cavity length, ring-down time with different cavity lengths was experimentally obtained and the dependence of total cavity loss on cavity length was determined. The extinction coefficient of air was determined by the slope of linear dependence of total cavity loss on cavity length. The extinction coefficients of air with different particle concentrations at 635 nm wavelength were measured to be from 10.46 to 84.19 Mm-1 (ppm/m) in a normal laboratory environment. This variable-cavity-length OPCRD technique can be used for absolute extinction measurement and real-time environmental monitoring without closed-path sample cells and background measurements.

Developmental changes in hypoxic exposure and responses to anoxia in Drosophila melanogaster

Holometabolous insects undergo dramatic morphological and physiological changes during ontogeny. In particular, the larvae of many holometabolous insects are specialized to feed in soil, water or dung, inside plant structures, or inside other organisms as parasites where they may commonly experience hypoxia or anoxia. In contrast, holometabolous adults usually are winged and live with access to air. Here, we show that larval Drosophila melanogaster experience severe hypoxia in their normal laboratory environments; third instar larvae feed by tunneling into a medium without usable oxygen. Larvae move strongly in anoxia for many minutes, while adults (like most other adult insects) are quickly paralyzed. Adults survive anoxia nearly an order of magnitude longer than larvae (LT50: 8.3 versus 1 h). Plausibly, the paralysis of adults is a programmed response to reduce ATP need and enhance survival. In support of that hypothesis, larvae produce lactate at 3× greater rates than adults in anoxia. However, when immobile in anoxia, larvae and adults are similarly able to decrease their metabolic rate, to about 3% of normoxic conditions. These data suggest that Drosophila larvae and adults have been differentially selected for behavioral and metabolic responses to anoxia, with larvae exhibiting vigorous escape behavior likely enabling release from viscous anoxic media to predictably normoxic air, while the paralysis behavior of adults maximizes their chances of surviving flooding events of unpredictable duration. Developmental remodeling of behavioral and metabolic strategies to hypoxia/anoxia is a previously unrecognized major attribute of holometabolism.

Heartbeat and economic decisions: observing mental stress among proposers and responders in the ultimatum bargaining game.

The ultimatum bargaining game (UBG), a widely used method in experimental economics, clearly demonstrates that motives other than pure monetary reward play a role in human economic decision making. In this study, we explore the behaviour and physiological reactions of both responders and proposers in an ultimatum bargaining game using heart rate variability (HRV), a small and nonintrusive technology that allows observation of both sides of an interaction in a normal experimental economics laboratory environment. We find that low offers by a proposer cause signs of mental stress in both the proposer and the responder; that is, both exhibit high ratios of low to high frequency activity in the HRV spectrum.

Focal length measurement by fiber point diffraction longitudinal interferometry

A focal length measurement method by fiber point-diffraction longitudinal interferometry is proposed. By applying two different longitudinal displacements for the object point respectively and measuring the corresponding displacements of the image point, the lens focal length is derived by Newton formula. The displacements of the object point are introduced by glass plates with known refractive index and thickness. The corresponding displacements of the image point are measured interfeorometrically based on the modeling of the longitudinal interferometry of two point sources. Experiments and error analysis reveal that this method has an accuracy less than 0.15% under normal laboratory environment.

Effect of corrosion of tensile rebars and stirrups on the flexural stiffness of reinforced concrete members

This article introduces the results of experiments on 25-year-old reinforced concrete beams under the effect of service load. Two reinforced concrete beams were stored in a chloride environment and allowed to corrode, while a non-corroded control beam was stored in the normal laboratory environment. A finite macro-element model for corroded reinforced concrete, taking account of the influence of corrosion development and the reduction of the bond between longitudinal steel reinforcement and concrete, was applied to calculate the mechanical behaviour of the beams. The comparison between the theoretical calculation and the experimental results showed that, when evaluating the mechanical behaviour of corroded reinforced concrete, besides the factors of length, width of cracks due to corrosion, and the number of cross-beam-axis cracks, it is necessary to consider transverse cracks in the cross-section of the beam due to corrosion of the transverse reinforcement.

Adhesive Transfer Soft Lithography: Low-Cost and Flexible Rapid Prototyping of Microfluidic Devices

A simple and low-cost approach was proposed for prototyping PDMS based microfluidic devices by transferringadhesive film microstructures onto a flexible substrate as a mould for PDMS replicas. The microstructures were engravedon an adhesive coated film using a commercial cutting plotter and then transferred (or laminated) onto a flexiblesubstrate, allowing for engraved isolated patterns. The proposed technique was demonstrated by a hydrodynamic focusingmicrofluidic device, having splitting and re-combining sheath channels. The whole processing could be finished within 1h in a normal laboratory environment. This approach offers an easy, flexible and rapid prototyping of microfluidic andlab-on-a-chip devices to users without expertise in microfabrication. In addition, by minimizing the use of chemicals, theprocess becomes more environmentally friendly than conventional photolithography based micro-fabrication techniques.

Sequestration and autophagy of mitochondria do not cut proteins across the board

Mitochondria that acquire deleterious DNA mutations or sustain chemical damage to proteins are sequestered and cleared by autophagy, purportedly to maintain the fidelity of the remaining organelles. In PNAS, Vincow et al. demonstrate that two proteins, phosphatase and tensin homolog-induced putative kinase 1 (PINK1) and Parkin, which are mutated in forms of familial parkinsonism, promote mitochondrial autophagy (mitophagy) in vivo in Drosophila raised in a normal laboratory environment (1). Thus, mitophagy appears to be a routine and necessary housekeeping activity that may be essential for survival of certain neurons and muscle cells that die in PINK1 and Parkin mutant flies. The work also uncovers a mystery that some mitochondrial respiratory chain (RC) proteins appear to be selectively routed for autophagosomal degradation, a process generally thought to remove entire mitochondria and indiscriminately eliminate RC components.

Structural Performance and Ductility of Fiber Reinforced Polymer Concrete Bonding System Under Tropical Climates

Tropical climate combines with saltwater exposure may influence the structural performance and durability of FRP–epoxy–concrete system over long period of time. FRP being non–corrodible material has been proven to be efficient materials in rehabilitation jobs compared to steel. Reinforced concrete structures may be required to be strengthened at a later age of their service life to overcome additional loading capacity and deterioration due to environmental effect. The main objective of the current paper is to study flexural behavior of an externally bonded reinforced concrete beams using carbon FRP plate and fabrics due to exposure to natural tropical climate. The research studies the ability of reinforced concrete beams externally bonded with CFRP plate and fabrics to resist numerous environmental conditions such as tropical weather, normal laboratory environment and saltwater solution. The bonded beams are subjected experimental evaluation by performing four points load test until failure to observe the failure loads, deflection, strain, cracking behavior and the patterns of failure. Strengthening of reinforced concrete beams using CFRP plate and fabrics demonstrated significant improvement in the flexural capacity of the beams by 30% and 16%, respectively compare to control specimen without strengthening.