bluuebunny/crossref_metadata_2025 huggingface dataset:
Complex Brines and Their Implications for Habitability
Authors: Renno Nilton O. , Fischer Erik , Martínez Germán , Hanley Jennifer
Published: August 2021

There is evidence that life on Earth originated in cold saline waters around scorching hydrothermal vents, and that similar conditions might exist or have existed on Mars, Europa, Ganymede, Enceladus, and other worlds. Could potentially habitable complex brines with extremely low freezing temperatures exist in the shallow subsurface of these frigid worlds? Earth, Mars, and carbonaceous chondrites have similar bulk elemental abundances, but while the Earth is depleted in the most volatile elements, the Icy Worlds of the outer solar system are expected to be rich in them. The cooling of ionic solutions containing substances that likely exist in the Icy Worlds could form complex brines with the lowest eutectic temperature possible for the compounds available in them. Indeed, here, we show observational and theoretical evidence that even elements present in trace amounts in nature are concentrated by freeze–thaw cycles, and therefore contribute significantly to the formation of brine reservoirs that remain liquid throughout the year in some of the coldest places on Earth. This is interesting because the eutectic temperature of water–ammonia solutions can be as low as ~160 K, and significant fractions of the mass of the Icy Worlds are estimated to be water substance and ammonia. Thus, briny solutions with eutectic temperature of at least ~160 K could have formed where, historically, temperature have oscillated above and below ~160 K. We conclude that complex brines must exist in the shallow subsurface of Mars and the Icy Worlds, and that liquid saline water should be present where ice has existed, the temperature is above ~160 K, and evaporation and sublimation have been inhibited.
Fundamentals of Physics-Informed Neural Networks Applied to Solve the Reynolds Boundary Value Problem
Authors: Almqvist Andreas
Published: August 2021

This paper presents a complete derivation and design of a physics-informed neural network (PINN) applicable to solve initial and boundary value problems described by linear ordinary differential equations. The objective with this technical note is not to develop a numerical solution procedure which is more accurate and efficient than standard finite element- or finite difference-based methods, but to give a fully explicit mathematical description of a PINN and to present an application example in the context of hydrodynamic lubrication. It is, however, worth noticing that the PINN developed herein, contrary to FEM and FDM, is a meshless method and that training does not require big data which is typical in machine learning.
Wear-Resistant TiC Strengthening CoCrNi-Based High-Entropy Alloy Composite
Authors: Cai Yanlin , Tong Yonggang , Hu Yongle , Huang Hongfeng , Zhang Xiancheng , Hua Manyu , Xu Shan , Mei Yongbing , Ma Chengbiao , Li Zhifeng
Published: August 2021

In order to improve the wear resistance of CoCrNi alloy, TiC was introduced into the alloy and wear-resistant CoCrNi/(TiC)x composites were designed. The effects of TiC contents on the microstructure, mechanical properties, and wear resistance of CoCrNi matrix were investigated, respectively. It was found that the TiC produced dissolution and precipitation process in CoCrNi alloy, and a large number of needled and blocky TiC particles were precipitated in the composites. The compressive yield strength of CoCrNi/(TiC)x composites increased with the increasing TiC content. Compared with the CoCrNi alloy, the yield strength of CoCrNi/(TiC)x composites increased from 108 to 1371 MPa, and the corresponding strengthening mechanism contributed to the second phase strengthening. The wear resistance of CoCrNi/(TiC)x composites was also greatly improved due to the strengthening of TiC. Compared with the CoCrNi alloy, the specific wear rate of CoCrNi/(TiC)1.0 alloy was reduced by about 77%. The wear resistance of CoCrNi/(TiC)x composites was enhanced with the increasing content of TiC addition.
Mesoscale Mechanisms in Viscoplastic Deformation of Metals and Their Applications to Constitutive Models
Authors: Huang Wen Lai , Zhang Lin , Chen Kaiguo , Lu Guo
Published: August 2021

Deformation of metals has attracted great interest for a long time. However, the constitutive models for viscoplastic deformation at high strain rates are still under intensive development, and more physical mechanisms are expected to be involved. In this work, we employ the newly-proposed methodology of mesoscience to identify the mechanisms governing the mesoscale complexity of collective dislocations, and then apply them to improving constitutive models. Through analyzing the competing effects of various processes on the mesoscale behavior, we have recognized two competing mechanisms governing the mesoscale complex behavior of dislocations, i.e., maximization of the rate of plastic work, and minimization of the elastic energy. Relevant understandings have also been discussed. Extremal expressions have been proposed for these two mesoscale mechanisms, respectively, and a stability condition for mesoscale structures has been established through a recently-proposed mathematical technique, considering the compromise between the two competing mechanisms. Such a stability condition, as an additional constraint, has been employed subsequently to close a two-phase model mimicking the practical dislocation cells, and thus to take into account the heterogeneous distributions of dislocations. This scheme has been exemplified in three increasingly complicated constitutive models, and improves the agreements of their results with experimental ones.
Nuclear Radiation Shielding Characteristics of Some Natural Rocks by Using EPICS2017 Library
Authors: Al-Buriahi Mohammed Sultan , Sayyed M. I. , Bantan Rashad A. R. , Al-Hadeethi Yas
Published: August 2021

Radiation leakage is a serious problem in various technological applications. In this paper, radiation shielding characteristics of some natural rocks are elucidated. Mass attenuation coefficients (µ/ρ) of these rocks are obtained at different photon energies with the help of the EPICS2017 library. The obtained µ/ρ values are confirmed via the theoretical XCOM program by determining the correlation factor and relative deviation between both of these methods. Then, effective atomic number (Zeff), absorption length (MFP), and half value layer (HVL) are evaluated by applying the µ/ρ values. The maximum μ/ρ values of the natural rocks were observed at 0.37 MeV. At this energy, the Zeff values of the natural rocks were 16.23, 16.97, 17.28, 10.43, and 16.65 for olivine basalt, jet black granite, limestone, sandstone, and dolerite, respectively. It is noted that the radiation shielding features of the selected natural rocks are higher than that of conventional concrete and comparable with those of commercial glasses. Therefore, the present rocks can be used in various radiation shielding applications, and they have many advantages for being clean and low-cost products. In addition, we found that the EPICS2017 library is useful in determining the radiation shielding parameters for the rocks and may be used for further calculations for other rocks and construction building materials.
The Curing Kinetics of E-Glass Fiber/Epoxy Resin Prepreg and the Bending Properties of Its Products
Authors: Zhu Lvtao , Wang Zhenxing , Rahman Mahfuz Bin , Shen Wei , Zhu Chengyan
Published: August 2021

The curing kinetics can influence the final macroscopic properties, particularly the three-point bending of the fiber-reinforced composite materials. In this research, the curing kinetics of commercially available glass fiber/epoxy resin prepregs were studied by non-isothermal differential scanning calorimetry (DSC). The curing kinetic parameters were obtained by fitting and the apparent activation energy Ea of the prepreg, the pre-exponent factor, and the reaction order value obtained. A phenomenological nth-order curing reaction kinetic model was established according to Kissinger equation and Crane equation. Furthermore, the optimal curing temperature of the prepregs was obtained by the T-β extrapolation method. A vacuum hot pressing technique was applied to prepare composite laminates. The pre-curing, curing, and post-curing temperatures were 116, 130, and 153 °C respectively. In addition, three-point bending was used to test the specimens’ fracture behavior, and the surface morphology was analyzed. The results show that the differences in the mechanical properties of the samples are relatively small, indicating that the process settings are reasonable.
Investigating Optimal Confinement Behaviour of Low-Strength Concrete through Quantitative and Analytical Approaches
Authors: Ali Mujahid , Abbas Sheraz , Salah Bashir , Akhter Javed , Saleem Waqas , Haruna Sani , Room Shah , Abdulkadir Isyaka
Published: August 2021

Reinforced concrete is used worldwide in the construction industry. In past eras, extensive research has been conducted and has clearly shown the performance of stress–strain behaviour and ductility design for high-, standard-, and normal-strength concrete (NSC) in axial compression. Limited research has been conducted on the experimental and analytical investigation of low-strength concrete (LSC) confinement behaviour under axial compression and relative ductility. Meanwhile, analytical equations are not investigated experimentally for the confinement behaviour of LSC by transverse reinforcement. The current study experimentally investigates the concrete confinement behaviour under axial compression and relative ductility of NSC and LSC using volumetric transverse reinforcement (VTR), and comparison with several analytical models such as Mander, Kent, and Park, and Saatcioglu. In this study, a total of 44 reinforced-column specimens at a length of 18 in with a cross-section of 7 in × 7 in were used for uniaxial monotonic loading of NSC and LSC. Three columns of each set were confined with 2 in, 4 in, 6 in, and 8 in c/c lateral ties spacing. The experimental results show that the central concrete stresses are significantly affected by decreasing the spacing between the transverse steel. In the case of the LSC, the core stresses are double the central stress of NSC. However, increasing the VTR, the capacity and the ductility of NSC and LSC increases. Reducing the spacing between the ties from 8 in to 2 in center to center can affect the concrete column’s strength by 60% in LSC, but 25% in the NSC. The VTR and the spacing between the ties greatly affected the LSC compared to NSC. It was found that the relative ductility of the confined column samples was almost twice that of the unrestrained column samples. Regarding different models, the Manders model best represents the performance before the ultimate strength, whereas Kent and Park represents post-peak behaviour.
An Engineering Zirconia Ceramic Made of Baddeleyite
Authors: Rodaev Vyacheslav V. , Zhigachev Andrey O. , Tyurin Alexander I. , Razlivalova Svetlana S. , Korenkov Viktor V. , Golovin Yuri I.
Published: August 2021

Wet high-energy milling and uniaxial pressing are used to fabricate CaO-stabilized tetragonal zirconia polycrystalline ceramic (Ca-TZP) with decent mechanical characteristics, i.e., a hardness of 11.5 GPa, Young’s modulus of 230 GPa, and fracture toughness of 13 MPa·m0.5. The effect of CaO concentration and the sintering temperature on phase composition and mechanical characteristics of CaO-stabilized zirconia ceramic made of baddeleyite is investigated.
Further Increasing the Accuracy of Characterization of a Thin Dielectric or Semiconductor Film on a Substrate from Its Interference Transmittance Spectrum
Authors: Minkov Dorian , Marquez Emilio , Angelov George , Gavrilov Gavril , Ruano Susana , Saugar Elias
Published: August 2021

Three means are investigated for further increasing the accuracy of the characterization of a thin film on a substrate, from the transmittance spectrum T(λ) of the specimen, based on the envelope method. Firstly, it is demonstrated that the accuracy of characterization, of the average film thickness d¯ and the thickness non-uniformity ∆d over the illuminated area, increases, employing a simple dual transformation utilizing the product T(λ)xs(λ), where Tsm(λ) is the smoothed spectrum of T(λ) and xs(λ) is the substrate absorbance. Secondly, an approach is proposed for selecting an interval of wavelengths, so that using envelope points only from this interval provides the most accurate characterization of d¯ and ∆d, as this approach is applicable no matter whether the substrate is transparent or non-transparent. Thirdly, the refractive index n(λ) and the extinction coefficient k(λ) are computed, employing curve fitting by polynomials of the optimized degree of 1/λ, instead of by previously used either polynomial of the optimized degree of λ or a two-term exponential of λ. An algorithm is developed, applying these three means, and implemented, to characterize a-Si and As98Te2 thin films. Record high accuracy within 0.1% is achieved in the computation of d¯ and n(λ) of these films.
Novel Methods in Multiple Criteria Decision-Making Process (MCRAT and RAPS)—Application in the Mining Industry
Authors: Urošević Katarina , Gligorić Zoran , Miljanović Igor , Beljić Čedomir , Gligorić Miloš
Published: August 2021

Multiple criteria decision making (MCDM) is a supporting tool which is widely spread in different areas of science and industry. Many researchers have confirmed that MCDM methods can be useful for selecting the best solution in many different problems. In this paper, two novel methods are presented and applied on existing decision-making processes in the mining industry. The first method is multiple criteria ranking by alternative trace (MCRAT) and the second is ranking alternatives by perimeter similarity (RAPS). These two novel methods are demonstrated in decision-making problems and compared with the ranking of the same alternatives by other MCDM methods. The mining process often includes drilling and blasting operations as the most common activities for exploitation of raw materials. For optimal blasting design it is important to select the most suitable parameters for the blasting pattern and respect characteristics of the working environment and production conditions. By applying novel methods, how to successfully select the most proper blasting pattern respecting all conditions that must be satisfied for economic aspects and the safety of employees and the environment is presented.
Optimization of the Real-Time Response to Roadside Incidents through Heuristic and Linear Programming
Authors: Buil Roman , de Armas Jesica , Riera Daniel , Orozco Sandra
Published: August 2021

This paper presents a solution for a real-world roadside assistance problem. Roadside incidents can happen at any time. Depending on the type of incident, a specific resource from the roadside assistance company can be sent on site. The problem of allocating resources to these road-side incidents can be stated as a multi-objective function and a large set of constraints, including priorities and preferences, resource capacities and skills, calendars, and extra hours. The request from the client is to a have real-time response and to attempt to use only open source tools. The optimization objectives to consider are the minimization of the operational costs and the minimization of the time to arrive to each incident. In this work, an innovative approach to near-optimally solving this problem in real-time is proposed, combining a heuristic approach and linear programming. The results show the great potential of this approach: operational costs were reduced by 19%, the use of external providers was reduced to half, and the productivity of the resources owned by the client was significantly increased.
A Dynamic Multi-Objective Duopoly Game with Capital Accumulation and Pollution
Authors: Crettez Bertrand , Hayek Naila , Kort Peter M.
Published: August 2021

This paper studies a discrete-time dynamic duopoly game with homogenous goods. Both firms have to decide on investment where investment increases production capacity so that they are able to put a larger quantity on the market. The downside, however, is that a larger quantity raises pollution. The firms have multiple objectives in the sense that each one maximizes the discounted profit stream and appreciates a clean environment as well. We obtain some surprising results. First, where it is known from the continuous-time differential game literature that firms invest more under a feedback information structure compared to an open-loop one, we detect scenarios where the opposite holds. Second, in a feedback Nash equilibrium, capital stock is more sensitive to environmental appreciation than in the open-loop case.
An Improved High-Dimensional Kriging Surrogate Modeling Method through Principal Component Dimension Reduction
Authors: Li Yaohui , Shi Junjun , Yin Zhifeng , Shen Jingfang , Wu Yizhong , Wang Shuting
Published: August 2021

The Kriging surrogate model in complex simulation problems uses as few expensive objectives as possible to establish a global or local approximate interpolation. However, due to the inversion of the covariance correlation matrix and the solving of Kriging-related parameters, the Kriging approximation process for high-dimensional problems is time consuming and even impossible to construct. For this reason, a high-dimensional Kriging modeling method through principal component dimension reduction (HDKM-PCDR) is proposed by considering the correlation parameters and the design variables of a Kriging model. It uses PCDR to transform a high-dimensional correlation parameter vector in Kriging into low-dimensional one, which is used to reconstruct a new correlation function. In this way, time consumption of correlation parameter optimization and correlation function matrix construction in the Kriging modeling process is greatly reduced. Compared with the original Kriging method and the high-dimensional Kriging modeling method based on partial least squares, the proposed method can achieve faster modeling efficiency under the premise of meeting certain accuracy requirements.
Effect of Hot Band on Texture Evolution and Plastic Anisotropy in Aluminium Alloys
Authors: Sidor Jurij J.
Published: August 2021

This contribution presents the evolution of crystallographic texture during thermomechanical processing of Al alloys. It is shown that the nature of crystallographic changes involved in deformation and recrystallization is strongly affected by the variety of initial (pre-rolling) state of a given metallic system. Four hot rolled Al strips of identical chemical composition and different textures were subjected to further thermomechanical processing with equal technological characteristics. Although the pre-rolling textures were first destroyed by the deformation, while annealing accounted for further qualitative and quantitative crystallographic changes in the investigated polycrystalline systems, it seems that there is still a great influence of the hot band texture on the texture dependent properties. Various qualitative and quantitative texture characteristics of annealed sheets ensured diverse Lanford value curves, which is a direct consequence of the crystallographic features developed in the hot bands. The Cube-dominated hot band ensured a strong V-shaped profile after cold rolling and subsequent recrystallization, whereas it was shown that a weak pre-rolling texture is more advantageous in terms of both normal and planar anisotropy.
Ground Structures-Based Topology Optimization of a Morphing Wing Using a Metaheuristic Algorithm
Authors: Winyangkul Seksan , Wansaseub Kittinan , Sleesongsom Suwin , Panagant Natee , Kumar Sumit , Bureerat Sujin , Pholdee Nantiwat
Published: August 2021

This paper presents multi-objective topology and sizing optimization of a morphing wing structure. The purpose of this paper is to design a new aircraft wing structure with a tapered shape for ribs, spars, and skins including a torsion beam for external actuating torques, which is anticipated to modify the aeroelastic characteristic of the aircraft wing using multi-objective optimization. Two multi-objective topology optimization problems are proposed employing ground element structures with high- and low-grid resolutions. The design problem is to minimize mass, maximize difference of lift effectiveness, and maximize the buckling factor of an aircraft wing subject to aeroelastic and structural constraints including lift effectiveness, critical speed, and buckling factors. The design variables include aircraft wing structure dimensions and thickness distribution. The proposed optimization problems are solved by an efficient multi-objective metaheuristic algorithm while the results are compared and discussed. The Pareto optimal fronts obtained for all tests were compared based on a hypervolume metric. The objective function values for Case I and Case II at 10 selected optimal solutions exhibit a range of structural mass as 115.3216–411.6250 kg, 125.0137–440.5869 kg, lift effectiveness as 1.0514–1.1451, 1.0834–1.1639 and bucking factor as 38.895–1133.1864 Hz, 158.1264–1844.4355 Hz, respectively. The best results reveal unconventional aircraft wing structures that can be manufactured using additive manufacturing. This research is expected to serve as a foundation for future research into multi-objective topology optimization of morphing wing structures based on the ground element framework.
Correction: Torres et al. Leaching Chalcopyrite with High MnO2 and Chloride Concentrations. Metals 2020, 10, 107
Authors: Torres David , Ayala Luís , Jeldres Ricardo I. , Cerecedo-Sáenz Eduardo , Salinas-Rodríguez Eleazar , Robles Pedro , Toro Norman
Published: August 2021

The authors wish to make the following corrections to this paper [...]
Pool Boiling Performance of Multilayer Micromeshes for Commercial High-Power Cooling
Authors: Tang Kairui , Bai Jingjing , Chen Siyu , Zhang Shiwei , Li Jie , Sun Yalong , Chen Gong
Published: August 2021

With the rapid development of electronics, thermal management has become one of the most crucial issues. Intense research has focused on surface modifications used to enhance heat transfer. In this study, multilayer copper micromeshes (MCMs) are developed for commercial compact electronic cooling. Boiling heat transfer performance, including critical heat flux (CHF), heat transfer coefficients (HTCs), and the onset of nucleate boiling (ONB), are investigated. The effect of micromesh layers on the boiling performance is studied, and the bubbling characteristics are analyzed. In the study, MCM-5 shows the highest critical heat flux (CHF) of 207.5 W/cm2 and an HTC of 16.5 W(cm2·K) because of its abundant micropores serving as nucleate sites, and outstanding capillary wicking capability. In addition, MCMs are compared with other surface structures in the literature and perform with high competitiveness and potential in commercial applications for high-power cooling.
Modelling Renal Filtration and Reabsorption Processes in a Human Glomerulus and Proximal Tubule Microphysiological System
Authors: Zhang Stephanie Y. , Mahler Gretchen J.
Published: August 2021

Kidney microphysiological systems (MPS) serve as potentially valuable preclinical instruments in probing mechanisms of renal clearance and osmoregulation. Current kidney MPS models target regions of the nephron, such as the glomerulus and proximal tubule (PCT), but fail to incorporate multiple filtration and absorption interfaces. Here, we describe a novel, partially open glomerulus and PCT microdevice that integrates filtration and absorption in a single MPS. The system equalizes pressure on each side of the PCT that operates with one side “closed” by recirculating into the bloodstream, and the other “opened” by exiting as primary filtrate. This design precisely controls the internal fluid dynamics and prevents loss of all fluid to the open side. Through this feature, an in vitro human glomerulus and proximal tubule MPS was constructed to filter human serum albumin and reabsorb glucose for seven days of operation. For proof-of-concept experiments, three human-derived cell types—conditionally immortalized human podocytes (CIHP-1), human umbilical vein endothelial cells (HUVECs), and human proximal tubule cells (HK-2)—were adapted into a common serum-free medium prior to being seeded into the three-component MPS (T-junction splitter, glomerular housing unit, and parallel proximal tubule barrier model). This system was optimized geometrically (tubing length, tubing internal diameter, and inlet flow rate) using in silico computational modeling. The prototype tri-culture MPS successfully filtered blood serum protein and generated albumin filtration in a physiologically realistic manner, while the device cultured only with proximal tubule cells did not. This glomerulus and proximal convoluted tubule MPS is a potential prototype for the human kidney used in both human-relevant testing and examining pharmacokinetic interactions.
Connection between the Gut Microbiota of Largemouth Bass (Micropterus salmoides) and Microbiota of the Pond Culture Environment
Authors: Liu Qianfu , Lai Zini , Gao Yuan , Wang Chao , Zeng Yanyi , Liu Erchun , Mai Yongzhan , Yang Wanling , Li Haiyan
Published: August 2021

The vital role of the gut microbiota in fish growth, development, immunity, and health has been largely confirmed. However, the interaction between environmental microbiota and the gut microbiota of aquaculture species remains unclear. Therefore, we analyzed the gut microbiota of largemouth bass (Micropterus salmoides) collected from subtropical ponds in southern China, as well as the pond water and aquatic sediment microbiota, using high-throughput sequencing of the 16S rRNA gene. Our results demonstrated significant differences in the compositions of pond water, sediment, and the gut microbiota of largemouth bass. Moreover, these compositions changed throughout the culture period. Only approximately 1% of the bacterial species in the pond sediment and gut microbiota were exchanged. However, the bacterial proportion of the gut microbiota from pond water microbiota was approximately 7% in samples collected in June and August, which increased markedly to 73% in October. Similarly, the proportion of bacteria in the pond water microbiota from the gut microbiota was approximately 12% in June and August, which increased to 45% in October. The study findings provide basic information for understanding the interactions between environmental microbiota and the gut microbiota of cultured fish, which may contribute to improved pond culture practices for largemouth bass.
Smartphone-Assisted Colorimetric Detection of Glutathione and Glutathione Reductase Activity in Human Serum and Mouse Liver Using Hemin/G-Quadruplex DNAzyme
Authors: Lai Yufen , Li Mengyan , Liao Xiaofei , Zou Li
Published: August 2021

Abnormal levels of reduced glutathione (GSH) and glutathione reductase (GR) are usually related to a variety of diseases, so it is of great significance to determine the GSH concentration and GR activity. We herein develop a smartphone-assisted colorimetric biosensor for the detection of GSH and GR activity in human serum and mouse liver using hemin/G-quadruplex DNAzyme. Firstly, an obvious color change from colorless to green can be observed, owing to the high peroxidase-like activity of hemin/G-quadruplex DNAzyme toward 2,2′-azino-bis(3-ethylbenzothiozoline-6-sulfonic acid) (ABTS). With the addition of GSH or GR, the H2O2-mediated oxidation of ABTS catalyzed by hemin/G-quadruplex DNAzyme is significantly inhibited, resulting in remarkable color fading. Therefore, the detection of GSH and GR activity can be achieved by observing the color transition or measuring the absorbance at 420 nm. The detection limit was estimated to be as low as 0.1 μM and 10 μU/mL for GSH and GR, respectively. More interestingly, the RGB values of the sensing system can be identified by the smartphone application (APP, color collect), which makes it an ideal format for on-site determination and point-of-care testing (POCT). In addition, the proposed method shows excellent selectivity and acceptable applicability for the determination of GSH concentration and GR activity in human serum samples and mouse liver tissues, which might hold great application potential in clinical diagnosis and drug screening.
Cellular NADH and NADPH Conformation as a Real-Time Fluorescence-Based Metabolic Indicator under Pressurized Conditions
Authors: Heidelman Martin , Dhakal Bibek , Gikunda Millicent , Silva Kalinga Pavan Thushara , Risal Laxmi , Rodriguez Andrew I. , Abe Fumiyoshi , Urayama Paul
Published: August 2021

Cellular conformation of reduced pyridine nucleotides NADH and NADPH sensed using autofluorescence spectroscopy is presented as a real-time metabolic indicator under pressurized conditions. The approach provides information on the role of pressure in energy metabolism and antioxidant defense with applications in agriculture and food technologies. Here, we use spectral phasor analysis on UV-excited autofluorescence from Saccharomyces cerevisiae (baker’s yeast) to assess the involvement of one or multiple NADH- or NADPH-linked pathways based on the presence of two-component spectral behavior during a metabolic response. To demonstrate metabolic monitoring under pressure, we first present the autofluorescence response to cyanide (a respiratory inhibitor) at 32 MPa. Although ambient and high-pressure responses remain similar, pressure itself also induces a response that is consistent with a change in cellular redox state and ROS production. Next, as an example of an autofluorescence response altered by pressurization, we investigate the response to ethanol at ambient, 12 MPa, and 30 MPa pressure. Ethanol (another respiratory inhibitor) and cyanide induce similar responses at ambient pressure. The onset of non-two-component spectral behavior upon pressurization suggests a change in the mechanism of ethanol action. Overall, results point to new avenues of investigation in piezophysiology by providing a way of visualizing metabolism and mitochondrial function under pressurized conditions.
Chemical Constitution and Antimicrobial Activity of Kombucha Fermented Beverage
Authors: Al-Mohammadi Abdul-Raouf , Ismaiel Ahmed A. , Ibrahim Rehab A. , Moustafa Ahmed H. , Abou Zeid Azza , Enan Gamal
Published: August 2021

Kombucha is a traditional beverage of sweetened black tea fermented with a symbiotic association of acetic acid bacteria and yeasts. In this study, kombucha fermented beverage (KFB) appeared to include nine chemical groups (alcohols, acids, lactones, condensed heterocyclic compounds, antibiotics, esters, aldehydes, fatty acids, and alkaloids) of many bioactive metabolites, as elucidated by gas chromatography–mass spectrometry (GC-MS) and IR spectra. The fermented metabolic components of KFB seem collectively to act in a synergistic action giving rise to the antimicrobial activity. Four types of kombucha preparations (fermented, neutralized, heat-treated and unfermented) were demonstrated with respect to their antimicrobial activity against some pathogenic bacterial and fungal strains using agar well diffusion assay. KFB exerted the strongest antimicrobial activities when compared with neutralized and heat-treated kombucha beverages (NKB and HKB). Staphylococcus aureus ATCC6538 (S. aureus) and Escherichia coli ATCC11229 (E. coli) were the organisms most susceptible to the antimicrobial activity of kombucha beverage preparations. Finally, the KFB preparation showed remarkable inhibitory activity against S. aureus and E. coli bacteria in a brain heart infusion broth and in some Egyptian fruit juices (apple, guava, strawberry, and tomato). These data reveal that kombucha is not only a prophylactic agent, but also appears to be promising as a safe alternative biopreservative, offering protection against pathogenic bacteria and fungi.
Graphene Oxide and Reduced Graphene Oxide Nanoflakes Coated with Glycol Chitosan, Propylene Glycol Alginate, and Polydopamine: Characterization and Cytotoxicity in Human Chondrocytes
Authors: Vannozzi Lorenzo , Catalano Enrico , Telkhozhayeva Madina , Teblum Eti , Yarmolenko Alina , Avraham Efrat Shawat , Konar Rajashree , Nessim Gilbert Daniel , Ricotti Leonardo
Published: August 2021

Recently, graphene and its derivatives have been extensively investigated for their interesting properties in many biomedical fields, including tissue engineering and regenerative medicine. Nonetheless, graphene oxide (GO) and reduced GO (rGO) are still under investigation for improving their dispersibility in aqueous solutions and their safety in different cell types. This work explores the interaction of GO and rGO with different polymeric dispersants, such as glycol chitosan (GC), propylene glycol alginate (PGA), and polydopamine (PDA), and their effects on human chondrocytes. GO was synthesized using Hummer’s method, followed by a sonication-assisted liquid-phase exfoliation (LPE) process, drying, and thermal reduction to obtain rGO. The flakes of GO and rGO exhibited an average lateral size of 8.8 ± 4.6 and 18.3 ± 8.5 µm, respectively. Their dispersibility and colloidal stability were investigated in the presence of the polymeric surfactants, resulting in an improvement in the suspension stability in terms of average size and polydispersity index over 1 h, in particular for PDA. Furthermore, cytotoxic effects induced by coated and uncoated GO and rGO on human chondrocytes at different concentrations (12.5, 25, 50 and 100 µg/mL) were assessed through LDH assay. Results showed a concentration-dependent response, and the presence of PGA contributed to statistically decreasing the difference in the LDH activity with respect to the control. These results open the way to a potentially safer use of these nanomaterials in the fields of cartilage tissue engineering and regenerative medicine.
Synthesis of Biomimetic Melanin-Like Multifunctional Nanoparticles for pH Responsive Magnetic Resonance Imaging and Photothermal Therapy
Authors: Qu Jing , Guillory Devin , Cheah Pohlee , Tian Bin , Zheng Jie , Liu Yongjian , Cates Courtney , Janorkar Amol V. , Zhao Yongfeng
Published: August 2021

The design and development of multifunctional nanoparticles have attracted great interest in biomedical research. This study aims to prepare pH-responsive melanin-like nanoparticles for T1-weighted magnetic resonance imaging (MRI) and photothermal therapy. The new multifunctional nanoparticles (amino-Fe-PDANPs) are synthesized by copolymerization of dopamine and its derivative amino-N-[2-(diethylamino) ethyl]-3,4-dihydroxy-benzenepropanamide (N-Dopa) at room temperature. The size of nanoparticles can be controlled by NaOH concentration. The incorporation of N-Dopa is characterized by NMR and FT-IR. From transmission electron microscopy (TEM), the nanoparticles exhibit excellent dispersion stability in water and are spherical in shape. The MRI measurement has demonstrated that amino-Fe-PDANPs have a significant signal enhancement in responding to the acidic solution. Confirmed by the photothermal study, the nanoparticles exhibit a high photothermal conversion efficiency. The melanin-like multifunctional nanoparticles integrate both diagnosis and therapeutic functionalities, indicating the potential for theranostic application.
Optimized Planar Microwave Antenna for Nitrogen Vacancy Center Based Sensing Applications
Authors: Opaluch Oliver Roman , Oshnik Nimba , Nelz Richard , Neu Elke
Published: August 2021

Individual nitrogen vacancy (NV) color centers in diamond are versatile, spin-based quantum sensors. Coherently controlling the spin of NV centers using microwaves in a typical frequency range between 2.5 and 3.5 GHz is necessary for sensing applications. In this work, we present a stripline-based, planar, Ω-shaped microwave antenna that enables one to reliably manipulate NV spins. We found an optimal antenna design using finite integral simulations. We fabricated our antennas on low-cost, transparent glass substrate. We created highly uniform microwave fields in areas of roughly 400 × 400 μm2 while realizing high Rabi frequencies of up to 10 MHz in an ensemble of NV centers.
Laser Scribing Fabrication of Graphitic Carbon Biosensors for Label-Free Detection of Interleukin-6
Authors: Tan Pei Shee , Vaughan Eoghan , Islam Jahidul , Burke Niall , Iacopino Daniela , Tierney Joanna B.
Published: August 2021

Interleukin-6 (IL-6) is an important immuno-modulating cytokine playing a pivotal role in inflammatory processes in disease induction and progression. As IL-6 serves as an important indicator of disease state, it is of paramount importance to develop low cost, fast and sensitive improved methods of detection. Here we present an electrochemical immunosensor platform based on the use of highly porous graphitic carbon electrodes fabricated by direct laser writing of commercial polyimide tapes and chemically modified with capture IL-6 antibodies. The unique porous and 3D morphology, as well as the high density of edge planes of the graphitic carbon electrodes, resulted in a fast heterogeneous electron transfer (HET) rate, k0 = 0.13 cm/s. The resulting immunosensor showed a linear response to log of concentration in the working range of 10 to 500 pg/mL, and low limit of detection (LOD) of 5.1 pg/mL IL-6 in phosphate buffer saline. The total test time was approximately 90 min, faster than the time required for ELISA testing. Moreover, the assay did not require additional sample pre-concentration or labelling steps. The immunosensor shelf-life was long, with stable results obtained after 6 weeks of storage at 4 °C, and the selectivity was high, as no response was obtained in the presence of another inflammatory cytokine, Interlukin-4. These results show that laser-fabricated graphitic carbon electrodes can be used as selective and sensitive electrochemical immunosensors and offer a viable option for rapid and low-cost biomarker detection for point-of-care analysis.
Temperature-Dependent Superplasticity and Strengthening in CoNiCrFeMn High Entropy Alloy Nanowires Using Atomistic Simulations
Authors: Tripathi Pawan Kumar , Chiu Yu-Chen , Bhowmick Somnath , Lo Yu-Chieh
Published: August 2021

High strength and ductility, often mutually exclusive properties of a structural material, are also responsible for damage tolerance. At low temperatures, due to high surface energy, single element metallic nanowires such as Ag usually transform into a more preferred phase via nucleation and propagation of partial dislocation through the nanowire, enabling superplasticity. In high entropy alloy (HEA) CoNiCrFeMn nanowires, the motion of the partial dislocation is hindered by the friction due to difference in the lattice parameter of the constituent atoms which is responsible for the hardening and lowering the ductility. In this study, we have examined the temperature-dependent superplasticity of single component Ag and multicomponent CoNiCrFeMn HEA nanowires using molecular dynamics simulations. The results demonstrate that Ag nanowires exhibit apparent temperature-dependent superplasticity at cryogenic temperature due to (110) to (100) cross-section reorientation behavior. Interestingly, HEA nanowires can perform exceptional strength-ductility trade-offs at cryogenic temperatures. Even at high temperatures, HEA nanowires can still maintain good flow stress and ductility prior to failure. Mechanical properties of HEA nanowires are better than Ag nanowires due to synergistic interactions of deformation twinning, FCC-HCP phase transformation, and the special reorientation of the cross-section. Further examination reveals that simultaneous activation of twining induced plasticity and transformation induced plasticity are responsible for the plasticity at different stages and temperatures. These findings could be very useful for designing nanowires at different temperatures with high stability and superior mechanical properties in the semiconductor industry.
Dietary Protein Intake and Transition between Frailty States in Octogenarians Living in New Zealand
Authors: Teh Ruth , Mendonça Nuno , Muru-Lanning Marama , MacDonell Sue , Robinson Louise , Kerse Ngaire
Published: August 2021

Adequate nutritional status may influence progression to frailty. The purpose of this study is to determine the prevalence of frailty and examine the relationship between dietary protein intake and the transition between frailty states and mortality in advanced age. We used data from a longitudinal cohort study of Māori (80–90 years) and non-Māori (85 years). Dietary assessments (24-h multiple pass dietary recalls) were completed at the second year of follow-up (wave 2 and forms the baseline in this study). Frailty was defined using the Fried Frailty criteria. Multi-state modelling examined the association of protein intake and transitions between frailty states and death over four years. Over three quarters of participants were pre-frail or frail at baseline (62% and 16%, respectively). Those who were frail had a higher co-morbidity (p < 0.05), where frailty state changed, 44% showed a worsening of frailty status (robust → pre-frail or pre-frail → frail). Those with higher protein intake (g/kg body weight/day) were less likely to transition from robust to pre-frail [Hazard Ratio (95% Confidence Interval): 0.28 (0.08–0.91)] but also from pre-frail to robust [0.24 (0.06–0.93)]. Increased protein intake was associated with lower risk of transitioning from pre-frailty to death [0.19 (0.04–0.80)], and this association was moderated by energy intake [0.22 (0.03–1.71)]. Higher protein intake in this sample of octogenarians was associated with both better and worse outcomes.
Bone Mineral Density Changes during Weight Regain following Weight Loss with and without Exercise
Authors: Serra Monica C. , Ryan Alice S.
Published: August 2021

The purpose of this study was to compare changes in bone mineral density (BMD) over a 6 month follow up (period of weight regain) in overweight, postmenopausal women having previously completed a 6 month weight loss (WL) intervention with and without aerobic exercise (AEX). Women (BMI > 25 kg/m2) underwent VO2max and DEXA scans at baseline, after 6 months of WL or AEX + WL, and at 12 months ad libitum follow up. Both groups lost ~9% body weight from 0 to 6 months and regained ~2% from 6 to 12 months, while losing ~4% of appendicular lean mass (ALM) across the 12-month study duration. VO2max increased 10% from 0 to 6 months and declined 12% from 6 to 12 months for AEX + WL, with no changes for WL. Total body (p < 0.01) and total femur (p = 0.03) BMD decreased similar between groups across time (combined groups: 0–6 months: total body: −1.2% and total femur: −1.2%; 6–12 months: total body: −0.26% and total femur: −0.09%). Less ALM loss and greater VO2max increases during the WL phase were associated with attenuated BMD loss at various anatomical sites during periods of weight regain (6–12 months) p’s < 0.05). Results suggest that BMD loss may continue following WL, despite weight regain. Further, this study adds to the literature by suggesting that preventing declines in muscle quality and function during WL may attenuate the loss of BMD during weight regain. Future studies are needed to identify mechanisms underlying WL-induced bone loss so that effective practices can be designed to minimize the loss of BMD during WL and weight maintenance in older women.
Nutrition in the Intensive Care Unit—A Narrative Review
Authors: Hill Aileen , Elke Gunnar , Weimann Arved
Published: August 2021

Background: While consent exists, that nutritional status has prognostic impact in the critically ill, the optimal feeding strategy has been a matter of debate. Methods: Narrative review of the recent evidence and international guideline recommendations focusing on basic principles of nutrition in the ICU and the treatment of specific patient groups. Covered topics are: the importance and diagnosis of malnutrition in the ICU, the optimal timing and route of nutrition, energy and protein requirements, the supplementation of specific nutrients, as well as monitoring and complications of a Medical Nutrition Therapy (MNT). Furthermore, this review summarizes the available evidence to optimize the MNT of patients grouped by primarily affected organ system. Results: Due to the considerable heterogeneity of the critically ill, MNT should be carefully adapted to the individual patient with special focus on phase of critical illness, metabolic tolerance, leading symptoms, and comorbidities. Conclusion: MNT in the ICU is complex and requiring an interdisciplinary approach and frequent reevaluation. The impact of personalized and disease-specific MNT on patient-centered clinical outcomes remains to be elucidated.
Comparison of Two Real-Time PCR Assays Targeting Ribosomal Sequences for the Identification of Cystoisospora belli in Human Stool Samples
Authors: Blohm Martin , Hahn Andreas , Hagen Ralf Matthias , Eberhardt Kirsten Alexandra , Rohde Holger , Leboulle Gérard , Feldt Torsten , Sarfo Fred Stephen , Di Cristanziano Veronica , Frickmann Hagen , Loderstädt Ulrike
Published: August 2021

Cystoisospora (C.) belli is a coccidian parasite associated with acute or chronic gastroenteritis in immunocompromised patients. Dissatisfactory sensitivity of microscopy as the diagnostic standard approach has been described. Here, we comparatively evaluated two real-time PCRs targeting ribosomal RNA gene sequences of C. belli in stool in a test comparison without a reference standard applying latent class analysis. Therefore, 1000 stool samples from Ghanaian HIV (human immunodeficiency virus) patients (n = 905) as well as military returnees from the tropics (n = 95) were assessed by both assays in parallel. After the exclusion of 33 samples showing PCR inhibition, 29 and 33 positive results were recorded with the 5.8S rRNA gene/ITS-2 sequence PCR and the ITS-2 sequence PCR, respectively, resulting in an accuracy-adjusted prevalence of 3.2%. Nearly perfect agreement between both assays was indicated by Fleiss’ kappa of 0.933 with sensitivity and specificity of 92.8% and 100% as well as 100% and 99.8% for the 5.8S rRNA gene/ITS-2 sequence PCR and the ITS-2 sequence PCR, respectively. Both assays proved to be suitable for the diagnosis of C. belli in human stool samples with slightly better sensitivity of the ITS-2 sequence assay, while the 5.8S rRNA gene/ITS-2 sequence PCR may be considered for confirmatory testing.
Formulation and Evaluation of Helichrysum italicum Essential Oil-Based Topical Formulations for Wound Healing in Diabetic Rats
Authors: Andjić Marijana , Božin Biljana , Draginić Nevena , Kočović Aleksandar , Jeremić Jovana N. , Tomović Marina , Milojević Šamanović Andjela , Kladar Nebojša , Čapo Ivan , Jakovljević Vladimir , Bradić Jovana V.
Published: August 2021

As proper wound management is crucial to reducing morbidity and improving quality of life, this study evaluated for the first time the wound healing potential of H. italicum essential oil (HIEO) prepared in the form of ointment and gel in streptozotocin-induced diabetic wound models in rats. After creating full-thickness cutaneous wounds, forty-eight diabetic rats were divided into six groups: (1) negative control; (2) positive control; (3) ointment base; (4) gel base; (5) 0.5% HIEO ointment (6) 0.5% HIEO gel. Wound healing potential was determined by the percentage of wound contraction, hydroxyproline content, redox status, and histological observation. A significant decrease in the wound size was observed in animals treated with HIEO formulations compared with other groups. The HIEO groups also showed a higher level of total hydroxyproline content, and more pronounced restitution of adnexal structures with only the underlying muscle defect indicating the incision site. Hence, our results legitimate the traditional data of the pro-healing effect of HIEO because HIEO in both formulations such as gel and ointment exhibited the significant wound repairing effect in the incision wound model.