Small Working Volume Research Articles

In-plane absolute micro-displacement measurement based on a pixelated metasurface

In-plane micro-displacement measurement is a critical requirement in many engineering fields. In this work, we present a measurement system based on pixelated metasurface to achieve high-precision, absolute in-plane micro-displacement measurement within limited measurement space. By exploiting the wavelength selectivity of pixelated metasurface, the composite frequency light source is reflected to the camera, forming images containing features. Subsequently, a displacement ruler is established to obtain linear displacement values. The designed device achieves resolution as low as sub-micrometer levels for in-plane micro-displacement, with measurement errors within 0.5 and 1.3 μm for single-step displacements of 10 and 5 μm, respectively. The measurement scheme also exhibits good measurement stability over extended durations. The proposed scheme achieves absolute correspondence between displacement and reference values through visual images, and the system operates within a very small working volume. Therefore, it holds promise for application in engineering scenarios where absolute traceability of the target position is required and the measurement space is limited.

Ultrasensitive dopamine detection with graphene aptasensor multitransistor arrays

Detecting physiological levels of neurotransmitters in biological samples can advance our understanding of brain disorders and lead to improved diagnostics and therapeutics. However, neurotransmitter sensors for real-world applications must reliably detect low concentrations of target analytes from small volume working samples. Herein, a platform for robust and ultrasensitive detection of dopamine, an essential neurotransmitter that underlies several brain disorders, based on graphene multitransistor arrays (gMTAs) functionalized with a selective DNA aptamer is presented. High-yield scalable methodologies optimized at the wafer level were employed to integrate multiple graphene transistors on small-size chips (4.5 × 4.5 mm). The multiple sensor array configuration permits independent and simultaneous replicate measurements of the same sample that produce robust average data, reducing sources of measurement variability. This procedure allowed sensitive and reproducible dopamine detection in ultra-low concentrations from small volume samples across physiological buffers and high ionic strength complex biological samples. The obtained limit-of-detection was 1 aM (10–18) with dynamic detection ranges spanning 10 orders of magnitude up to 100 µM (10–8), and a 22 mV/decade peak sensitivity in artificial cerebral spinal fluid. Dopamine detection in dopamine-depleted brain homogenates spiked with dopamine was also possible with a LOD of 1 aM, overcoming sensitivity losses typically observed in ion-sensitive sensors in complex biological samples. Furthermore, we show that our gMTAs platform can detect minimal changes in dopamine concentrations in small working volume samples (2 µL) of cerebral spinal fluid samples obtained from a mouse model of Parkinson’s Disease. The platform presented in this work can lead the way to graphene-based neurotransmitter sensors suitable for real-world academic and pre-clinical pharmaceutical research as well as clinical diagnosis.

Phenotypic and transcriptional changes in Escherichia coli K12 in response to simulated microgravity on the EagleStat, a new 2D microgravity analog for bacterial studies.

Understanding the impacts of microgravity on bacteria is vital for successful long duration space missions. In this environment, bacteria have been shown to become more virulent, more resistant to antibiotics and to regulate biofilm formation. Since the study of these phenomena under true microgravity is cost- and time challenging, the use of ground-based analogs might allow researchers to test hypotheses before planning and executing experiments in the space environment. We designed and developed a 2D clinostat with capabilities robust enough for bacterial studies to allow for multiple simultaneous replicates of treatment and control conditions, thus permitting the generation of growth curves, in a single run. We used computational fluid dynamics (CFD), biofilm growth measurement and differential gene expression analysis on Escherichia coli cultures grown to late exponential phase (24 h) to validate the system's ability to simulate microgravity conditions. The CFD model with a rotational speed of 8 rpm projected cells growing homogeneously distributed along the tube, while the static condition showed the accumulation of the cells at the bottom of the container. These results were empirically validated with cultures on nutrient broth. Additionally, crystal violet assays showed that higher biofilm biomass grew on the internal walls of the gravity control tubes, compared to the simulated microgravity treatment. In contrast, when cells from both treatments were grown under standard conditions, those exposed to simulated microgravity formed significantly more biofilms than their gravity counterparts. Consistent with this result, transcriptome analysis showed the upregulation of several gene families related to biofilm formation and development such as cells adhesion, aggregation and regulation of cell motility, which provides a potential transcriptional explanation for the differential phenotype observed. Our results show that when operated under parameters for simulated microgravity, our 2D clinostat creates conditions that maintain a proportion of the cells in a constant free-falling state, consistent with the effect of microgravity. Also, the high-throughput nature of our instrument facilitates, significantly, bacterial experiments that require multiple sampling timepoints and small working volumes, making this new instrument extremely efficient.

A millisecond passive micromixer with low flow rate, low sample consumption and easy fabrication

Fast mixing of small volumes of solutions in microfluidic devices is essential for an accurate control and observation of the dynamics of a reaction in biological or chemical studies. It is often, however, a challenging task, as the Reynolds number (Re) in microscopic devices is typically < 100. In this report, we detail a novel mixer based on the “staggered herring bone” (SHB) pattern and “split-recombination” strategies with an optimized geometry, the periodic rotation of the flow structure can be controlled and recombined in a way that the vortices and phase shifts of the flow induce intertwined lamellar structures, thus increasing the contact surface and enhancing mixing. The optimization improves the mixing while using a low flow rate, hence a small volume for mixing and moderate pressure drops. The performances of the patterns were first simulated using COMSOL Multiphysics under different operating conditions. The simulation indicates that at very low flow rate (1–12 µL·min−1) and Re (3.3–40), as well as a very small working volume (~ 3 nL), a very good mixing (~ 98%) can be achieved in the ms time range (4.5–78 ms). The most promising design was then visualized experimentally, showing results that are consistent with the outcomes of the simulations. Importantly, the devices were fabricated using a classical soft-lithography method, as opposed to additive manufacturing often used to generate complex mixing structures. This new device minimizes the sample consumption and could therefore be applied for studies using precious samples.

H-infinity optimised control of external inertial actuators for higher precision robotic machining

ABSTRACT Serial-link industrial robots that feature small footprints and large working volumes have been used widely in various applications. However, their low-stiffness-induced vibration hinders application in precision robotic machining processes. In robotic milling, the spindle may experience chatter, leading to unsatisfactory surface finishes. Moreover, the chatter frequency varies, depending on the robot pose and its underlying stiffness and inertia characteristics, which is likely to be outside of the controlled robot system bandwidth. One solution is to use inertial actuators close to the source of excitation on the robot to generate forces that counteract the vibration. This paper advances matters by employing optimised H ∞ control strategies for improved effectiveness and robustness to perform active vibration suppression. The strategies are independent of tool paths and take account of different robot poses, hence the variability of the robot dynamic characteristics. Performance is assessed against that of standard velocity feedback controllers in eccentric mass experiments and milling tests. The experimental results show that within a relatively large work-plane (500 mm × 500 mm), H ∞ controllers greatly improve machining capability and reduce machining errors by up to 85%.

An Assessment of UAV Photogrammetry Based on GNSS Positioning Technology for Its Availability

There is a growing need for fusion and convergence technology between UAV (Unmanned Aerial Vehicle)s, which is attracting attention as a new growth engine for spatial information in the future. This need bolsters research efforts to make use of UAV and location positioning technologies based on their fusion and convergence in various fields. Therefore, this study set out to assess georeferencing method techniques based on RTK (Real Time Kinematic), PPK (Post Processed Kinematic), and GCP (Ground Control Point), which are types of UAV photogrammetry based on GNSS (Global Navigation Satellite System) positioning technology on the basis of fusion and convergence between UAVs, whose utilization began in survey, architecture, forestry, and disaster prevention, and location positioning technologies in location accuracy, work time, and accessibility of final results (mapping). The study also aimed to propose a technique of UAV photogrammetry based on GNSS positioning technologies capable of offering options according to areas of application, including UAV-based aerial photogrammetry, disaster prevention in agriculture, inspection of construction and structures, and forest survey. These techniques were applied to a research lot of approximately 0.6 Km2, and their outcomes were analyzed. The analysis results show that RTK and PPK had all of their operations automated and were thus able to reduce work time and GCP volume in the field. They could, however, cause problems with checking survey outcomes or testing their accuracy, except for the georeferencing approach based on GCP. These outcomes were arranged according to the survey methods: RTK will be applicable to areas where its real-time application is possible; PPK will be applicable to areas characterized by faster work times, small volume of indoor work, and medium-level accuracy in the field; and the GCP-based georeferencing technique will be applicable to areas that require a lot of work time and high accuracy. The findings of the study provide information about appropriate techniques and their advantages and disadvantages for each area of application. The study also offered a set of criteria to apply UAV photogrammetry techniques to the environment, ecology, and disaster prevention as well as spatial imagery information, thus considerably improving the efficiency of related jobs.

Intestinal fermentation in vitro models to study food-induced gut microbiota shift: an updated review.

In vitro gut fermentation models were firstly introduced in nutrition and applied microbiology research back in the 1990s. These models have improved greatly during time, mainly over the resemblance to the complexity of digestion stages, the replication of experimental conditions, the multitude of ecological parameters to assay. The state of the science is that the most competitive models shall include a complex gut microbiota, small working volumes, distinct interconnected compartments and rigorous bio-chemical and ecological settings, controlled by a computer, as well as a free-hands accessibility, not to contaminate the mock microbiota. These models are a useful tool to study the impact of a given diet compound, e.g. prebiotics, on the human gut microbiota. The principal application is to focus on the shift of the core microbial groups and selected species together with their metabolites, assaying their diversity, richness and abundance in the community over time. Besides, it is possible to study how a compound is digested, which metabolic pathways are triggered, and the type and quantity of microbial metabolites produced. Further prospective should focus on challenges with pathogens as well as on ecology of gut syndromes. In this minireview an updated presentation of the most used intestinal models is presented, basing on their concept, technical features, as well as on research applications.

HIGHER UTILISATION OF AGRICULTURAL MECHANISATION THROUGH ORGANISING MACHINE RING ASSOCIATIONS

During the 1990s, turbulent processes emerged in the Balkans, conflictss, economic crises, where most affected was agricultural production and farmers. During that period, there were still large factories, the so-called Agricultural-Industrial Combines, which had 70% of the arable land. At the time of the transition, most of those plants collapsed economically, agricultural machinery was sold at auction, the land was divided into tenders, the areas were shrunk and a process was gradually started in which everyone wanted to be a farmer. Agricultural machinery, although purchased new, with insufficient number of effective working hours during the year had a high cost per machine working hour. It has emerged as a result of large service outages, overhaul, and maintenance of tractors on the one hand, but also small agricultural parcels and small production on the other. High costs contribute to high production prices of the agricultural product. Although small farmers have a small volume of work, they still buy and purchase new propulsion machines, the purchase of which made them even more indebted, instead of organizing and jointly procuring what they need and thus enabling rational agricultural production. Therefore, through this scientific paper, we have analyzed everything that farmers can get, and what to lose if they are organized in tractor cooperatives (machine rings). Through surveys and recording the actual situation on the ground, we gained a realistic picture of the situation with our farms, and what it should be like.

Voltammetric Label‐free Detection of DNA Hypermethylation Using Polypyrrole‐modified Microelectrode Array

AbstractAn alternative strategy for the label‐free electrochemical detection of DNA hypermethylation using a microelectrode array as an oligodinucleotide (ODN) detector is presented. It relies on the oligonucleotide dependent electrostatic affinity interaction firstly with unmethylated ODN and then follow‐up with methylated DNA. The methylated cytosine status is quantified by monitoring the relative change in the exchange current at the ODN‐detector before and after the bisulfite treated DNA samples. This novel aproach displays unique advantages such as small working volumes of the analytes, low damage to DNA samples, easy integration of oligonucleides on the detector and signal evaluation.

At-line raman spectroscopy and design of experiments for robust monitoring and control of miniature bioreactor cultures.

The biopharmaceutical industry is moving toward a more quality by design (QbD) approach that seeks to increase product and process understanding and process control. Miniature bioreactor systems offer a high-throughput method enabling the assessment of numerous process variables in a controlled environment. However, the number of off/at-line samples that can be taken is restricted due to the small working volume of each vessel. This limitation may be resolved through the use of Raman spectroscopy due to its ability to obtain multianalyte data from small sample volumes fast. It can, however, be challenging to implement this technique for this application due to the complexity of the sample matrix and that analytes are often present in low concentration. Here, we present a design of experiments (DOE) approach to generate samples for calibrating robust multivariate predictive models measuring glucose, lactate, ammonium, viable cell concentration (VCC) and product concentration, for unclarified cell culture that improves the daily monitoring of each miniature bioreactor vessel. Furthermore, we demonstrate how the output of the glucose and VCC models can be used to control the glucose and main nutrient feed rate within miniature bioreactor cultures to within qualified critical limits set for larger scale vessels. The DOE approach used to generate the calibration sample set is shown to result in models more robust to process changes than by simply using samples taken from the "typical" process. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2740, 2019.

CoMiniGut-a small volume in vitro colon model for the screening of gut microbial fermentation processes.

Driven by the growing recognition of the influence of the gut microbiota (GM) on human health and disease, there is a rapidly increasing interest in understanding how dietary components, pharmaceuticals and pre- and probiotics influence GM. In vitro colon models represent an attractive tool for this purpose. With the dual objective of facilitating the investigation of rare and expensive compounds, as well as an increased throughput, we have developed a prototype in vitro parallel gut microbial fermentation screening tool with a working volume of only 5 ml consisting of five parallel reactor units that can be expanded with multiples of five to increase throughput. This allows e.g., the investigation of interpersonal variations in gut microbial dynamics and the acquisition of larger data sets with enhanced statistical inference. The functionality of the in vitro colon model, Copenhagen MiniGut (CoMiniGut) was first demonstrated in experiments with two common prebiotics using the oligosaccharide inulin and the disaccharide lactulose at 1% (w/v). We then investigated fermentation of the scarce and expensive human milk oligosaccharides (HMOs) 3-Fucosyllactose, 3-Sialyllactose, 6-Sialyllactose and the more common Fructooligosaccharide in fermentations with infant gut microbial communities. Investigations of microbial community composition dynamics in the CoMiniGut reactors by MiSeq-based 16S rRNA gene amplicon high throughput sequencing showed excellent experimental reproducibility and allowed us to extract significant differences in gut microbial composition after 24 h of fermentation for all investigated substrates and fecal donors. Furthermore, short chain fatty acids (SCFAs) were quantified for all treatments and donors. Fermentations with inulin and lactulose showed that inulin leads to a microbiota dominated by obligate anaerobes, with high relative abundance of Bacteroidetes, while the more easily fermented lactulose leads to higher relative abundance of Proteobacteria. The subsequent study on the influence of HMOs on two infant GM communities, revealed the strongest bifidogenic effect for 3′SL for both infants. Inter-individual differences of infant GM, especially with regards to the occurrence of Bacteroidetes and differences in bifidobacterial species composition, correlated with varying degrees of HMO utilization foremost of 6′SL and 3′FL, indicating species and strain related differences in HMO utilization which was also reflected in SCFAs concentrations, with 3′SL and 6′SL resulting in significantly higher butyrate production compared to 3′FL. In conclusion, the increased throughput of CoMiniGut strengthens experimental conclusions through elimination of statistical interferences originating from low number of repetitions. Its small working volume moreover allows the investigation of rare and expensive bioactives.

An FBG Optical Approach to Thermal Expansion Measurements under Hydrostatic Pressure.

We report on an optical technique for measuring thermal expansion and magnetostriction at cryogenic temperatures and under applied hydrostatic pressures of 2.0 GPa. Optical fiber Bragg gratings inside a clamp-type pressure chamber are used to measure the strain in a millimeter-sized sample of CeRhIn. We describe the simultaneous measurement of two Bragg gratings in a single optical fiber using an optical sensing instrument capable of resolving changes in length on the order of . Our results demonstrate the possibility of performing high-resolution thermal expansion measurements under hydrostatic pressure, a capability previously hindered by the small working volumes typical of pressure cells.

МETALLURGY CENTER XI – XII CENTURES IN VYSHGOROD HISTORICAL AND CULTURAL RESERVE (BASED ON THE MATERIALS OF ARCHAEOLOGICAL EXCAVATIONS, 1989)

For the first time, the author introduces materials for production complexes that were discovered during archaeological excavations in 1989 in the western part of the Vyshgorod post (Nizhny Dorohozhichi tract). The author states that their re-interpretation allows tracing almost all the basic stages of iron production and processing. This re-interpretation is essential because today there is no consensus among leading national specialists in the field of identifying a specific set of features that would be able to confidently interpret heat engineering devices and correlate them with the individual stages of iron production and processing. The analysis of the existing ceramic complex allowed the author to conclude on the dating of the production complexes in the second half of the XI - the first half of the XII century. Dwellings in which smith metallurgists kept their instruments are also dated, indicating their synchronicity. The author notes that almost all workshops were moved to the periphery because of the fire danger - they were located in the western (near the big ravine) and northeast suburbs of the metallurgical centre. It is emphasized that pits for burning coal were arranged near the raw hollows. The author once again refutes the hypothesis about the separation of metallurgical and blacksmithing crafts and the exclusively rural nature of the metal industry, as opposed to the urban nature of metalworking. It is noted that the vast majority of metallurgical furnaces had a relatively simple construction and relatively low production capacity, due to their small working volume. It is established that the range of metal products, which was presented among the materials of the excavations, is generally traditional for the ancient city. These are household items, handicrafts and agricultural implements, elements of the rider's weapons and equipment. The resident of one of the dwellings specialized in the manufacture of knives. However, as the author states, there were no metallographic analyzes that would determine the technological features of the Vyshgorod metal products from the 1989 excavations.

Modular Classification of Endoscopic Endonasal Transsphenoidal Approaches to Sellar Region: Anatomic Quantitative Study

Endoscopic visualization does not necessarily correspond to an adequate working space. The need for balancing invasiveness and adequacy of sellar tumor exposure has recently led to the description of multiple endoscopic endonasal transsphenoidal approaches. Comparative anatomic data on these variants are lacking. We sought to quantitatively compare endoscopic endonasal transsphenoidal approaches to the sella and parasellar region, using the concept of "surgical pyramid." Four endoscopic transsphenoidal approaches were performed in 10 injected specimens: 1) hemisphenoidotomy; 2) transrostral; 3) extended transrostral (with superior turbinectomy); and 4) extended transrostral with posterior ethmoidectomy. ApproachViewer software (part of GTx-Eyes II, University Health Network, Toronto, Canada) with a dedicated navigation system was used to quantify the surgical pyramid volume, as well as exposure of sellar and parasellar areas. Statistical analyses were performed with Friedman's tests and Nemenyi's procedure. Hemisphenoidotomy provided limited exposure of the sellar area and a small working volume. Atransrostral approach was necessary to expose the entire sella. Exposure of lateral parasellar areas required superior turbinectomy or posterior ethmoidectomy. The differences between each of the modules was statistically significant. The present study validates, from an anatomic point of view, a modular classification of endoscopic endonasal transsphenoidal approaches to the sellar region.

HEART RATE VARIABILITY IN UNTRAINED YOUNG MEN UNDER DIFFERENT POWER LOADING MODES

Aim: to study features of variability of a rhythm of heart at unexercised young men under the influence of power loadings in the conditions of application of certain training modes in the course of long occupations by athleticism. Patients and methods: 40 young men participated in inspections at the age of 19–20 years, not having contraindications for occupations with burdenings. Research of indicators of training loading of both groups used by representatives in the course of occupations conducted a method of definition of an index of training loading in athleticism. For determination of values of indicators of the statistical and spectral analysis of a rhythm of heart the Polar RS800CX cardiomonitor was used. Control of studied indicators at rest and after power loading carried out for 3 months of occupations by athleticism with an interval in 1 month. Results: use in the course of occupations by athleticism of power loadings with large volume of work and low intensity considerably increases activity of the central mechanisms of neurohumoral regulation of a rhythm of heart due to decrease in parasympathetic activation of autonomous nervous system on sinusovy knot of heart, than loading of high intensity with a small volume of work. Conclusions: the result of long-term adaptation to occupations by athleticism, in the conditions of different modes of loading, is characterized by existence of an ekonomization of functioning of cardiovascular system of the unexercised contingent.

Inkjet printing biomaterials for tissue engineering: bioprinting

Inkjet printing offers controlled placement of both biological and synthetic materials. The precision, control and small working volumes associated with inkjet printing are advantageous where biological materials such as proteins, enzymes and cells can incur high costs. This review is primarily technology focused and divides bioprinting into three categories of interest: proteins, cells and scaffolds and demonstrates that the logistical hurdles and material formulation requirements remain a common denominator to the advancement of the field into commercial applications and three-dimensional (3-D) constructs. A variety of cell types printed using thermal, piezoelectric and electrostatic actuation mechanisms yield 80–95% cell viability. Transient membrane damage is reported for cells printed using a thermal printer. Protein deposition by thermal and piezoelectric printing results in reversible deformation leading to an increased need for the addition of ink modifiers. The fluid characteristics and the drop substrate interactions are identified as crucial with regards to future applications. The current approaches to scaffold matrix selection with regards to the complex criterion require fluid and solid phases and a controlled phase change while maintaining the criterion for printing vary from chemical gelation, physical gelation mechanisms (e.g. thermo reversible gels) and tandem gelation.

Coarse and fine motion simulator between a magnetically levitated robot and an industrial robot

Magnetically levitated robots are widely employed for non-contact manipulation that presents a great promise for using in the various special environments such as in a dust-free room, in a vacuum, in a flammable atmosphere, and in vivo. Meanwhile, they have a disadvantage of small working volume corresponding to the allowable air gap between the levitated object and the electromagnets. In some cases, to construct a combination of a magnetically levitated robot (which can generate a fine motion) and an industrial robot (which can generate a coarse motion and has a comparatively large working envelope) seems an effective way to expand the whole operational working space. On that premise, we are developing an experimental system and simulator for collaborative work between a magnetically levitated robot and an industrial robot. This paper presents the system concept and the configuration of the simulator, and the result of a preliminary simulation experiment which has been performed to evaluate mainly two elements: the numerical magnetically levitated robot model and the numerical industrial robot model.

Is It Safer and More Beneficial to Work Heart Failure Patients Harder? An Editorial Commentary

Is It Safer and More Beneficial to Work Heart Failure Patients Harder? An Editorial Commentary

A NIR luminescent copolymer based on platinum porphyrin as high permeable dissolved oxygen sensor for microbioreactors

Microbioreactors with multioptical sensors have become increasingly important because of their small working volumes, high degree of parallelization and the available robotics. A novel hydrophobic luminescent copolymer P(Pt‐TPP‐TFEMA) along with reference P(Pt‐TPP‐EMA) containing the pendant group of 5,10,15,20‐tetraphenylporphyrin (TPP) moiety as low‐cost dissolved oxygen (DO) chemosensor film for high‐throughput microbioreactors is designed. Its sensor film exhibits fast response to DO with good stability and fatigue resistance, being capable of applying as a low‐cost DO indicator for high‐throughput bioprocess measurement. Results show that the quenching response of DO increases with the enhancement in the copolymeric hydrophobicity using the presented hybrid fluorinated ethyl methacrylate. Furthermore, the long emission band at 650 nm of chromophore TPP with large Stoke's shift about 250 nm brings several advantages, such as low scattering, deep penetration, and minimal interferences of absorption and fluorescence from the fermentation system, which shows high‐promising application in bioprocess monitoring. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2743–2752, 2013

Analytical evaluation of BEA zeolite for the pre-concentration of polycyclic aromatic hydrocarbons and their subsequent chromatographic analysis in water samples

The analytical performance of BEA – a commercial zeolite – is evaluated for the pre-concentration of fifteen Environmental Protection Agency – polycyclic aromatic hydrocarbons and their subsequent HPLC analysis in tap and lake water samples. The pre-concentration factors obtained with BEA have led to a method with excellent analytical figures of merit. One milliliter aliquots were sufficient to obtain excellent precision of measurements at the parts-per-trillion concentration level with relative standard deviations varying from 4.1% (dibenzo[a,h]anthracene) to 13.4% (pyrene). The limits of detection were excellent as well and varied between 1.1 (anthracene) and 49.9ngL−1 (indeno[1,2,3-cd]pyrene). The recovery values of all the studied compounds meet the criterion for regulated polycyclic aromatic hydrocarbons, which mandates relative standard deviations equal or lower than 25%. The small volume of organic solvents (100μL per sample) and amount of BEA (2mg per sample) makes sample pre-concentration environmentally friendly and cost effective. The extraction procedure is well suited for numerous samples as the small working volume (1mL) facilitates the implementation of simultaneous sample extraction. These are attractive features when routine monitoring of numerous samples is contemplated.