In Situ Real-Time Observation of Photoinduced Nanoscale Azo-Polymer Motions Using High-Speed Atomic Force Microscopy Combined with an Inverted Optical Microscope.

High-speed atomic force microscopy (HS-AFM) is an indispensable technique in the field of biology owing to its imaging capability with high spatiotemporal resolution. Furthermore, recent developments established tip-scan stand-alone HS-AFM combined with an optical microscope, drastically improving its versatility. It has considerable potential to contribute to not only biology but also various research fields. A great candidate is a photoactive material, such as an azo-polymer, which is important for optical applications because of its unique nanoscale motion under light irradiation. Here, we demonstrate the in situ observation of nanoscale azo-polymer motion by combining tip-scan HS-AFM with an optical system, allowing HS-AFM observations precisely aligned with a focused laser position. We observed the dynamic evolution of unique morphologies in azo-polymer films. Moreover, real-time topographic line profile analyses facilitated precise investigations of the morphological changes. This important demonstration would pave the way for the application of HS-AFM in a wide range of research fields.

Aligned Conjugated Polymer Nanofiber Networks in an Elastomer Matrix for High-Performance Printed Stretchable Electronics.

Conjugated polymer films are promising in wearable X-ray detection. However, achieving optimal film microstructure possessing good electrical and detection performance under large deformation via scalable printing remains challenging. Herein, we report bar-coated high-performance stretchable films based on a conjugated polymer P(TDPP-Se) and elastomer SEBS blend by optimizing the solution-processing conditions. The moderate preaggregation in solution and prolonged growth dynamics from a solvent mixture with limited dissolving capacity is critical to forming aligned P(TDPP-Se) chains/crystalline nanofibers in the SEBS phase with enhanced π-π stacking for charge transport and stress dissipation. The film shows a large elongation at break of >400% and high mobilities of 5.29 cm2 V-1 s-1 at 0% strain and 1.66 cm2 V-1 s-1 over 500 stretch-release cycles at 50% strain, enabling good X-ray imaging with a high sensitivity of 1501.52 µC Gyair-1 cm-2. Our work provides a morphology control strategy toward high-performance conjugated polymer film-based stretchable electronics.

A New Planar Potentiometric Sensor for In Situ Measurements.

A new construction of a potentiometric sensor was introduced for the first time. It relies on the use of two membranes instead of one, as in the well-known coated-disc electrode. For this purpose, a new electrode body was constructed, including not one, but two glassy carbon discs covered with an ion-selective membrane. This solution allows for the sensor properties to be enhanced without using additional materials (layers or additives) on the membrane. The new construction is particularly useful for in situ measurements in environmental samples. Two ion-selective polymeric membranes were used, namely H+ and K+-selective membranes, to confirm the universality of the idea. The tests conducted included chronopotentiometric tests, electrochemical impedance spectroscopy, and potentiometric measurements. The electrical and analytical parameters of the sensors were evaluated and compared for all tested electrodes to evaluate the properties of the planar electrode versus previously known constructions. Research has shown that the application of two membranes instead of one allows for the resistance of an electrode to be lowered and for the electrical capacitance to be elevated. Improving the electrical properties of an electrode resulted in the enhancement of its analytical properties. The pH measurement range of the planar electrode is 2-11, which is much wider in contrast to that of the single-membrane electrode. The linear range of the K+-selective planar electrode is wider than that of the coated-disc electrode and equals 10-6 to 10-1 M. The response time turned out to be a few seconds shorter, and the potential drift was smaller due to the application of an additional membrane in the electrode construction. This research creates a new opportunity to design robust potentiometric sensors, as the presented construction is universal and can be used to obtain electrodes selective to various ions.

Operando Nuclear Magnetic Resonance (NMR) Studies of a Trickle-bed Reactor Using D-T2 Correlations.

Catalytic conversions in fine-chemical and pharmaceutical production are increasingly performed in trickle-bed rectors. Optimisation of these processes is usually based on end of pipe measurement made at specific residence times. This process is both time-consuming and the data sometimes challenging to interpret. In the present work, operando nuclear magnetic resonance (NMR) techniques both at the scale of the whole bed (global) and spatially resolved within the bed (local) are used to gain new insights into the catalytic conversion process under reaction conditions. Spatially resolved spectroscopic and diffusion-T2-relaxation (D-T2) methods interrogate local differences in chemical conversion and selectivity, and mass transport (molecular self-diffusion) respectively, thereby providing valuable information for process simulation models. This capability is demonstrated using the continuous flow three phase (gas-liquid-solid) hydrogenation of benzonitrile over a fixed bed of 0.5 wt% Pd/Al2O3 catalyst pellets yielding toluene and benzylamine. Global 1H spectroscopic and D-T2 were used to monitor chemical conversion and the approach to steady state; these were subsequently followed by spatially resolved 1H spectra and spatially resolved D-T2 correlations to examine the local differences in axial conversion and selectivity of the catalyst bed packing. At steady-state a global conversion of 63% was achieved with 65% and 25% selectivity to benzylamine and toluene respectively. Heterogeneities in the local (axial) conversion and selectivity differed by 31% along the total catalyst bed length. These techniques should be applicable to many three-phase heterogeneous catalytic systems provided that the T2 relaxation time of the reactants and products is not prohibitively small.

In Situ Observations of Halogenated Gases at the Shangdianzi Background Station and Emission Estimates for Northern China.

Halogenated gases include ozone-depleting substances and greenhouse gases, such as chlorofluorocarbons, halons, hydrochlorofluorocarbons, hydrofluorocarbons, and perfluorinated gases. In situ atmospheric observations of major halogenated gases were conducted at the Shangdianzi (SDZ) background station, China, from October 2020 to September 2021 using ODS5-pro, a newly developed measurement system. The measurement time series of 36 halogenated gases showed occasional pollution events, where background conditions represented 25% (CH2Cl2) to 81% (CF3Cl, CFC-13) of the measurements. The annual mean background mole fractions of most species at SDZ were consistent with those obtained at the Mace Head station in Ireland. The background conditions were distinguished from pollution events, and the enhanced mole fractions were used to estimate the emissions of four categories of fluorinated gases (F-gases) from northern China using a tracer ratio method. The CO2-equivalent (CO2-equiv) emission of F-gases from northern China reached 181 ± 18 Tg year-1 during 2020-2021. Among the four categories of F-gases estimated, SF6 accounted for the highest proportion of CO2-equiv emissions (24%), followed by HFC-23 (22%), HFC-125 (17%), HFC-134a (13%), NF3 (10%), CF4 (5.9%), HFC-143a (3.9%), HFC-32 (3.4%), and HFC-152a (0.2%).

In Situ Probing the Mass Transport Property Inside an Imitated Three-Dimensional Porous Bioelectrode.

Three-dimensional porous materials have been demonstrated as the most successful bioelectrodes in bioelectrochemical systems due to their high specific surface area and abundant adhesion regions for electroactive bacteria. However, the pore clogging potentially limits the mass transfer process inside the electrode due to the unreasonable structure design and long-term operation. The investigation of mass transport behavior in the porous scaffolds is of great significance for designing the electrode structure and optimizing bioelectrochemical system performance. To in situ characterize the mass transport behavior in the orderly pore structure, model electrodes with 100 copper wires (10 × 10) are constructed to imitate a three-dimensional porous structure (pore size: ∼150 µm) commonly employed in bioelectrodes. The poor proton effective diffusion coefficient solidly demonstrates that the mass transport inside the three-dimensional porous electrode is critically inhibited, leading not only to a progressive change and sparse biomass in the biofilm development process but also to biofilm acidification due to serious proton accumulation. It finally results in sluggish bacterial metabolic activity and a decreased electrocatalytic capacity. The interior space of porous electrodes cannot be adequately utilized, resulting in the inability to fully exploit the advantages of their abundant surface area. Consequently, the construction of gradient porous electrodes with small inner and large outer pores to enhance mass transport is a feasible proposal for enhancing performance. The proposed methodology of establishing model electrodes combined with the in situ detection technique within porous electrodes is crucial for acquiring various types of physicochemical information inside the bioelectrode, such as biofilm growth situation, biochemical reaction conditions, as well as mass transfer characteristics. More importantly, the work provides a fundamental basis for designing highly efficient bioelectrodes.

Optical Measurement of the Stoichiometry of Thin-Film Compounds Synthetized From Multilayers: Example of Cu(In,Ga)Se2.

The properties of centimeter-sized thin-film compound semiconductors depend upon the morphology and chemical composition of the multiple submicrometer-thick elemental and alloy precursor layers from which they are synthesized. The challenge is to characterize the individual precursor layers over these length scales during a multistep synthesis without altering or contaminating them. Conventional electron and X-ray-based morphological and compositional techniques are invasive, require preparation, and are thus incompatible with in-line synthesis processes. In a proof-of-concept study, we applied confocal laser scanning microscopy (CLSM) as a noninvasive optical imaging technique, which measures three-dimensional surface profiles with nanoscale resolution, to this challenge. Using an array of microdots containing Cu(In,Ga)Se2 semiconductor layers for solar cells as an example, we performed CLSM correlative studies to quantify morphological and layer thickness changes during four stages of a thin-film compound synthesis. Using simple assumptions, we measured the micrometer-scale spatially resolved chemical composition of stacked precursor layers to predict the final material phases formed and predict relative device performance. The high spatial resolution, coupled with the ability to measure sizeable areas without influencing the synthesis at high speed, makes CLSM an excellent prospect for research and quality control tool for thin films.

Assessment of Electromagnetic Field Exposure on European Roads: A Comprehensive In Situ Measurement Campaign.

The rapid evolution of wireless communication technologies (such as fifth-generation (5G) cellular networks) in the last years has allowed connecting different objects (from wearable electronics to vehicles) and people through communication networks, and at the same time, has led to widespread deployment of base stations. Along with this growth, questions about the potential adverse effects on human health due to electromagnetic fields (EMFs) from base station antennas have also been raised. In this paper, we focus on the assessment of EMFs in automobiles during short (between cities) and long (between countries) trips on several European roads. Comprehensive measurement campaigns were carried out in several European countries: Austria, Bulgaria, Croatia, Hungary, Italy, Slovenia, and the Republic of Serbia. The results show that the median total electric field is 0.23-0.24 V/m in Bulgaria, Croatia, Hungary, Italy, and the Republic of Serbia. In Austria and Slovenia, the median is 0.28-0.31 V/m. Austria demonstrated the highest value for the total electric field, at 17.4 V/m.

In-Mould OCT Sensors Combined with Piezo-Actuated Positioning Devices for Compensating for Displacement in Injection Overmoulding of Optoelectronic Parts.

When overmoulding optoelectronic devices with optical elements, precise alignment of the overmoulded part and the mould is of great importance. However, mould-integrated positioning sensors and actuators are not yet available as standard components. As a solution, we present a mould-integrated optical coherence tomography (OCT) device that is combined with a piezo-driven mechatronic actuator, which is capable of performing the necessary displacement correction. Because of the complex geometric structure optoelectronic devices may have, a 3D imaging method was preferable, so OCT was chosen. It is shown that the overall concept leads to sufficient alignment accuracy and, apart from compensating for the in-plane position error, provides valuable additional information about the sample both before and after the injection process. The increased alignment accuracy leads to better energy efficiency, improved overall performance and less scrap parts, and thus even a zero-waste production process might be feasible.

Temperature-dependent resistance of carbon nanotube fibers.

Carbon nanotube fibers are highly recommended in the field of temperature sensor application owing to their excellent electrical conductivity and thermal conductivity. Here, this work demonstrated the rapid thermal response behaviour of CNT fibers fabricated by floating catalyst CVD method, which was measured by anin situtechnique based on the CNT film electric heater with excellent electrothermal response properties. The temperature dependences of resistance and structure were both explored. Experimental investigation indicates that the reduction in the inter-CNT interspace in the fibers caused by thermally driven actuation was dominantly responsible for the decrease of the fibers resistance during the heating process. Especially, the heated fibers showed 7.2% decrease in electrical resistance at the applied square-wave voltage of 8 V, and good temperature sensitivity (-0.15% °C-1). The as-prepared CNT fibers also featured a rapid and reversible electrical resistance response behaviour when exposed to external heating stimulation. Additionally, with the increment of temperature and twist-degree, the generated contraction actuation increased, which endowed the CNT fibers with more decrease in electrical resistance. These observations further suggested that the temperature-dependent conduction behavior of the CNT fibers with a high reversibility and repeatability was strongly correlated with their structure response to heat stimulation. As a consequence, the temperature-conduction behavior described here may be applied in other CNT-structured fibers and facilitated the improvement in their temperature-sensing applications.

A Fiber-Integrated CRDS Sensor for In-Situ Measurement of Dissolved Carbon Dioxide in Seawater.

Research on carbon dioxide (CO2) geological and biogeochemical cycles in the ocean is important to support the geoscience study. Continuous in-situ measurement of dissolved CO2 is critically needed. However, the time and spatial resolution are being restricted due to the challenges of very high submarine pressure and quite low efficiency in water-gas separation, which, therefore, are emerging the main barriers to deep sea investigation. We develop a fiber-integrated sensor based on cavity ring-down spectroscopy for in-situ CO2 measurement. Furthermore, a fast concentration retrieval model using exponential fit is proposed at non-equilibrium condition. The in-situ dissolved CO2 measurement achieves 10 times faster than conventional methods, where an equilibrium condition is needed. As a proof of principle, near-coast in-situ CO2 measurement was implemented in Sanya City, Haina, China, obtaining an effective dissolved CO2 concentration of ~950 ppm. The experimental results prove the feasibly for fast dissolved gas measurement, which would benefit the ocean investigation with more detailed scientific data.

Artificial oxygen carrier improves fatigue resistance in slow muscle but not in fast muscle in a rat in situ model.

The effects of liposome-encapsulated hemoglobin with high O2 affinity (h-LEH), an artificial O2 carrier in skeletal muscle, were studied by in situ fatigue resistance test in fast-type plantaris (PLT) and slow-type soleus (SOL) muscles with or without ischemia in the rat. The distal tendons of PLT and SOL muscles were isolated in situ and individually attached to the force transducers to record the developed tension in response to stimuli (80 Hz tetanus train, 1.5 minutes) to the ipsilateral sciatic nerve. The fatigue resistance test (five sets separated by 2-minute rests) was evaluated in terms of tension attenuation (fatigue) from the initial to the last tension (A) during each set, attenuation of the initial (B) or last tension (C) in each set, as compared to the first set in the presence or absence of ischemia or h-LEH (10 mL/kg). While ischemia significantly enhanced fatigue only in PLT, h-LEH showed no effect regardless of the perfusion pattern (normal/ischemia) or muscle-type (PLT/SOL) during each set (A). In parameter (B), set-by-set fatigue development was observed in PLT, whereas h-LEH-SOL showed a trend of advanced fatigue resistance. Such trends became clear in the parameter C (last tension), because h-LEH-SOL exerted, rather than decreased, the tension enhancement regardless of the presence or absence of ischemia, whereas there were no h-LEH effects in PLT. In addition, faster recovery of the nicotinamide adenine dinucleotide content in the muscle after 10 minutes of all fatigue tests was observed in h-LEH-SOL, while saline-SOL still showed a significantly higher value than that of control. These results suggested that additional O2 supply by h-LEH may accelerate the tricarboxylic acid cycle/electron transport chain in slow-type aerobic SOL muscle containing abundant mitochondria and contribute to the faster removal of muscle fatigue substances such as lactate.

In-Situ Measurement of Electrical-Heating-Induced Magnetic Field for an Atomic Magnetometer.

Electrical heating elements, which are widely used to heat the vapor cell of ultrasensitive atomic magnetometers, inevitably produce a magnetic field interference. In this paper, we propose a novel measurement method of the amplitude of electrical-heating-induced magnetic field for an atomic magnetometer. In contrast to conventional methods, this method can be implemented in the atomic magnetometer itself without the need for extra magnetometers. It can distinguish between different sources of magnetic fields sensed by the atomic magnetometer, and measure the three-axis components of the magnetic field generated by the electrical heater and the temperature sensor. The experimental results demonstrate that the measurement uncertainty of the heater's magnetic field is less than 0.2 nT along the x-axis, 1.0 nT along the y-axis, and 0.4 nT along the z-axis. The measurement uncertainty of the temperature sensor's magnetic field is less than 0.02 nT along all three axes. This method has the advantage of measuring the in-situ magnetic field, so it is especially suitable for miniaturized and chip-scale atomic magnetometers, where the cell is extremely small and in close proximity to the heater and the temperature sensor.

Nanowire Length, Density, and Crystalline Quality Retrieved from a Single Optical Spectrum.

We propose spectral domain attenuated reflectometry (SDAR) for fast characterization of nanomaterial growth. The method is demonstrated here for zinc oxide (ZnO) nanowires (NWs) which are grown vertically in random forest fashion showing that it is not limited to well-ordered NWs. We show how SDAR can provide, on the basis of a single measured spectrum, simultaneous information on nanowire length, nanowire density (through nanowire/air filling ratio), and crystalline quality (through band gap). The robustness of the proposed method is assessed first through comparison with information obtained from SEM and XRD taken as reference. In SDAR, the process for fast extraction of NW thickness and filling ratio values  makes use of the interference pattern contrast and the spectral periodicity in the reflection response which involve a best fit of the measured spectra with simple theoretical modeling based on the effective medium approach, achieved with a mean square error down to 0.1%. The results also suggest the existence of either 2 or 3 layers of different effective refractive index, hence providing insight on possible growth mechanisms.

Crystallographic characterization of steel microstructure using neutron diffraction.

Applications of neutron diffraction to microstructure evaluation of steel investigated by a project commissioned by the Innovative Structural Materials Association are summarized. The volume fraction of austenite (γ) for a 1.5Mn-1.5Si-0.2C steel was measured by various techniques including backscatter electron diffraction (EBSD) and X-ray diffraction. It is recommended to measure volume fraction and texture simultaneously using neutron diffraction. The γ reverse transformation was in situ monitored using dilatometry, EBSD, X-ray diffraction and neutron diffraction. The γ reversion kinetics showed excellent agreements between dilatometry and neutron diffraction, whereas the γ formation started at higher temperatures in EBSD and X-ray diffraction measurements. Such discrepancy is attributed to the change in chemical compositions at the specimen surface by heating; Mn and C concentrations were decreased with heating. Phase transformations from γ upon cooling were monitored, which enabled us to elucidate the changes in lattice parameters of ferrite (α) and γ affected by not only thermal contraction but also transformation strains, thermal misfit strains and carbon enrichment in γ in the above hypoeutectoid steel. Pearlitic transformation started after the carbon enrichment reached approximately 0.76 mass% and contributed to diffraction line broadening. Martensitic transformation with or without ausforming at 700°C was monitored for a medium carbon low alloyed steel. Dislocation density after ausforming was determined using the convolutional multiple whole profile fitting method for 10 s time-sliced data. The changes in γ and martensite lattice parameters upon quenching were tracked and new insights on internal stresses and the axial ratio of martensite were obtained.

Development of a Cost-Effective Optical Sensor for Continuous Monitoring of Turbidity and Suspended Particulate Matter in Marine Environment.

A cost-effective optical sensor for continuous in-situ monitoring of turbidity and suspended particulate matter concentration (SPM), with a production cost in raw materials less than 20 €, is presented for marine or fluvial applications. The sensor uses an infrared LED and three photodetectors with three different positions related to the light source-135º, 90º and 0º-resulting in three different types of light detection: backscattering, nephelometry and transmitted light, respectively. This design allows monitoring in any type of environment, offering a wide dynamic range and accuracy for low and high turbidity or SPM values. An ultraviolet emitter-receiver pair is also used to differentiate organic and inorganic matter through the differences in absorption at different wavelengths. The optical transducers are built in a watertight structure with a radial configuration where a printed circuit board with the electronic signal coupling is assembled. An in-lab calibration of the sensor was made to establish a relation between suspended particulate matter (SPM) or the turbidity (NTU) to the photodetectors' electrical output value in Volts. Two different sizes of seashore sand were used (180 µm and 350 µm) to evaluate the particle size susceptibility. The sensor was tested in a fluvial environment to evaluate SPM change during sediment transport caused by rain, and a real test of 22 days continuous in-situ monitoring was realized to evaluate its performance in a tidal area. The monitoring results were analysed, showing the SPM change during tidal cycles as well as the influence of the external light and biofouling problems.

A Novel Frequency Domain Impedance Sensor with a Perforated Cylinder Coaxial Design for In-Situ Measuring Soil Matric Potential.

Soil matric potential is an important parameter for agricultural and environmental research and applications. In this study, we developed a novel sensor to determine fast and in-situ the soil matric potential. The probe of the soil matric potential sensor comprises a perforated coaxial stainless steel cylinder filled with a porous material (gypsum). With a pre-determined gypsum water retention curve, the probe can determine the gypsum matric potential through measuring its water content. The matric potential of soil surrounding the probe is inferred by the reading of the sensor after the soil reaches a hydraulic equilibrium with the gypsum. The sensor was calibrated by determining the gypsum water retention curve using a pressure plate method and tested in three soil samples with different textures. The results showed that the novel sensor can determine the water retention curves of the three soil samples from saturated to dry when combined with a soil water content sensor. The novel sensor can respond fast to the changes of the soil matric potential due to its small volume. Future research could explore the application for agriculture field crop irrigation.

On-line soft sensing in upstream bioprocessing.

This review provides an overview and a critical discussion of novel possibilities of applying soft sensors for on-line monitoring and control of industrial bioprocesses. Focus is on bio-product formation in the upstream process but also the integration with other parts of the process is addressed. The term soft sensor is used for the combination of analytical hardware data (from sensors, analytical devices, instruments and actuators) with mathematical models that create new real-time information about the process. In particular, the review assesses these possibilities from an industrial perspective, including sensor performance, information value and production economy. The capabilities of existing analytical on-line techniques are scrutinized in view of their usefulness in soft sensor setups and in relation to typical needs in bioprocessing in general. The review concludes with specific recommendations for further development of soft sensors for the monitoring and control of upstream bioprocessing.

A Non-Contact Measuring System for In-Situ Surface Characterization Based on Laser Confocal Microscopy.

The characterization of surface topographic features on a component is typically quantified using two-dimensional roughness descriptors which are captured by off-line desktop instruments. Ideally any measurement system should be integrated into the manufacturing process to provide in-situ measurement and real-time feedback. A non-contact in-situ surface topography measuring system is proposed in this paper. The proposed system utilizes a laser confocal sensor in both lateral and vertical scanning modes to measure the height of the target features. The roughness parameters are calculated in the developed data processing software according to ISO 4287. To reduce the inherent disadvantage of confocal microscopy, e.g., scattering noise at steep angles and background noise from specular reflection from the optical elements, the developed system has been calibrated and a linear correction factor has been applied in this study. A particular challenge identified for this work is the in-situ measurement of features generated by a robotized surface finishing system. The proposed system was integrated onto a robotic arm with the measuring distance and angle adjusted during measurement based on a CAD model of the component in question. Experimental data confirms the capability of this system to measure the surface roughness within the Ra range of 0.2⁻7 µm (bandwidth λc/λs of 300), with a relative accuracy of 5%.

A Novel Dielectric Tomography System for In-Situ Tracking Three-Dimensional Soil Water Dynamics.

In this study, we developed a novel dielectric tomography system for in-situ tracking three-dimensional (3D) soil water dynamics. The system was designed to control a single dielectric tube sensor that automatically lowered in a PVC tube array installed in-situ to determine the water content of a soil profile, which eliminated probe-to-probe uncertainties and labor costs. Two tests for evaluating the novel system were conducted (i) to analyze and correct the positional error of the probe due to out-of-step errors of stepper motors, and (ii) to track and visualize 3D soil water temporal variations in a soil tank with heterogenetic bulk densities and initial water contents under drip irrigation. The results show that the positioning correcting algorithm combined with starting point alignment can minimize the positioning error of the probe during the 3D tomography. The single drip emitter test illustrated spatial and temporal variations of soil water content due to heterogeneous soil properties in vertical and horizontal directions around the access tube array. Based on these data, 3D distributions of soil water dynamics were visualized. The developed tomography system has potential application to be extended to the local scale in a greenhouse or the large scale in an agricultural field. Future research should explore the performance for agricultural crop irrigation or for modeling and validating soil water flow or hydrological process under either steady state or non-steady state condition.