High Dilution Ratio Research Articles

An in vitro study of coagulation evaluation in obstetric hemorrhage for pregnancy-induced hypertension with coagulation and platelet function analyzer

ABSTRACT This study aimed to establish in vitro hemodilution and resupplementation assays for obstetric hemorrhage in pregnancy-induced hypertension (PIH) and to monitor the coagulation function dynamically using a coagulation and platelet function analyzer. Forty-seven singleton pregnant women were divided into normal (n = 24) and PIH (n = 23) groups. Peripheral blood samples were used to construct the assays, and the activated clotting time (ACT), clotting rate (CR), and platelet function index (PF) were measured. The results showed that the baseline ACT was higher in the PIH group (p < 0.01). Hemodilution assays showed decreased ACT and increased CR and PF, with ACT changes significantly lower in the PIH group (p < 0.05). CR changed most in both groups at lower dilution ratios (35% to 50%), while ACT changed most at a higher dilution ratio (75%). In the resupplementation assay, ACT exhibited the most significant response. The analyzer effectively detected differences between pregnant women with and without PIH. Thus, we need to pay more attention to the changes of ACT in the actual clinical application to assess the coagulation status of parturients.

Effect of foaming agents and dilution ratio on physicochemical and bioactive compounds profile of dried palmyra pulp

The study was carried out to observe the effect of glycerol monostearate (1.0 %, 2.0 %, and 3.0 %), soy protein isolate (0.5 %, 1.0 %, and 1.5 %) and dilution ratio (1:1, 1:1.5) on foam characteristics at whipping time of 4 min. All the samples were incorporated with 0.5 % methyl cellulose (MC) as foam stabiliser and 5 % maltodextrin (MD) as drying aid. The effect of different drying air temperatures (60 °C and 70 °C) at foam thickness of 4 mm on phytochemical, biochemical and functional quality attributes was studied. The efficacy of artificial neural network (ANN) on foam-mat drying kinetics was tested. Foam expansion of the palmyra pulp increased to 108 % when added with 2 % GMS and diluted to 1:1.5. The increase was even more up to 138 % when the same diluted pulp was added with 1.5 % SPI. On the contrary, the foam retention and the foam stability were reduced at a higher dilution ratio. GMS (2 %) or SPI (1 %), each diluted at a 1:1 ratio, exhibited better foaming and colour characteristics. Drying was faster in pulp foamed with SPI (1 %) than in pulp incorporated with GMS (2 %). Non-foamed pulp showed lower drying rates and produced a compact sheet-like mat with a relatively harder and sticky texture. Effective moisture diffusivity values ranged from 1.820 × 10−8 to 2.721 × 10−8 (m2/min) and increased with an increase in the drying temperature. The tansig transfer function of ANN modelling could best predict the moisture ratio with drying time for all the foamed and non-foamed samples. Quality analysis showed that the palmyra pulp foamed with 0.5 % MC, 5 %, MD, and 1 % SPI, diluted at a 1:1 ratio, whipped for 4 min, and dried at 70 °C with foam thickness of 4 mm could produce the powder with best quality attributes. The developed powder was found to possess 79.341 ± 0.998 mg GAE/100 g of total phenolic content, 72.669 ± 0.964 % of antioxidant activity, 60.526 ± 0.975 mg/100 g of ascorbic acid content, 35.287 ± 0.973 % of reducing sugar, 15661 ± 192 µg/100 g of β-carotene with water absorption and hygroscopicity of 2.374 ± 0.827 g/g and 38.487 ± 1.020 % respectively.

Early-stage analysis on developing different oat (Avena sativa L) added value fractions by ultrasound-assisted three-phase partition (UATPP): Effect of variables on yield and environmental impacts

This research explores an oat refinery using an ultrasound-assisted three-phase partition (UATPP) to obtain three value-added fractions (oil, protein, and fiber). Ultrasound-assisted pretreatment (time), salt (weight %), and butanol (volume %) were assessed against the mass extracted (weight %) at the different fractions by response surface methodology (RSM) and environmental impacts critical for the planetary boundaries framework by life cycle assessment (LCA). Experimental results showed an acceptable regression for predicting the different fractions and their environmental effects. The protein-rich phase (wt %) varied from 4.5 to 15.3 %, where the effect of salt (wt %) and butanol (vol %) was significant, while crude protein content (65–78 %) was affected by ultrasound pretreatment (time) and salt (wt %). The oil-rich phase extracted was between 5 and 8.6 % wt, showing a typical oat's fatty acid profile: oleic (38.18–42.81%), linoleic acid (25.51–33.86 %), and palmitic acid (20.25–23.54%). For this phase, the interaction of butanol with salt (wt %) and ultrasound pretreatment (min) was significant. The fiber-rich phase showed significance with salt (wt %) and ultrasound pretreatment ranging from 66.3 to 78.8 wt %. Moreover, their rheological characteristics (G′ and G″) seemed to change by the variation in oil content, like oat flour and starches. The optimization of the process to maximize protein and oil gave the following conditions: 15 min of ultrasound pretreatment, 4.5 salt (wt %), and 50 butanol (vol %). Regarding LCA, butanol manufacture was a hot spot on environmental indicators such as global warming (kg CO2 eq·kg−1), marine eutrophication (kg P·kg−1), freshwater eutrophication (kg N·kg−1), and freshwater consumption (m3·kg−1). Land use (m2·kg−1) impacts were mainly caused by running UATTP at high dilution ratios (typical at the lab scale). Activities such as solvent reduction and recirculation were found critical to minimize environmental impacts. This analysis can aid in foreseeing potential processing and environmental implications at an early stage of development, allowing better holistic decisions.

Vanadium-Doped Mesoporous Bioactive Glass Promotes Osteogenic Differentiation of rBMSCs via the WNT/β-Catenin Signaling Pathway.

Pentavalent vanadium [V(V)] has been studied as bioactive ions to improve the bone defect repair; however, its osteogenic promotion mechanism is still not fully understood so far. In this study, a V-doped mesoporous bioactive glass (V-MBG) was prepared, and its effects on osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs) and potential signaling pathways were investigated. The physicochemical characterization revealed that the incorporation of V slightly reduced the specific surface area and increased the mesoporous pore size, and the abundant mesopores of V-MBG were beneficial to the sustained dissolution of V(V) ions as well as calcium, silicon, and phosphorus ions. Cell proliferation results indicated that the high dilution ratio (>16) V-MBG extract markedly promoted the proliferation of rBMSCs compared with the control group and the same dilution ratio MBG extract. Compared with the same dilution ratio MBG extract, diluted V-MBG extracts markedly promoted the secretion of alkaline phosphatase (ALP) and osteocalcin (OCN) protein at day 7 but insignificantly stimulated the runt-related transcription factor 2 (RUNX2) and vascular endothelial growth factor (VEGF) protein synthesis. In depth, the diluted V-MBG extracts remarkably up-regulated the expression of WNT/β-catenin pathway direct target genes, including WNT3a, β-catenin, and AXIN2 genes in contrast to the same dilution ratio MBG extracts, suggesting that the released V(V) ions might promote osteogenic differentiation of rBMSCs via the WNT/β-catenin signaling pathway.

Comprehensive influence of uncertainty propagation of chemical kinetic parameters on laminar flame speed prediction: a case study of dimethyl ether

The uncertainties existing in the parameters of chemical kinetic models have a non-negligible influence on the model predictions. It is necessary to conduct a quantitative uncertainty analysis to explore the influence of each parameter on chemical mechanism predictions. To comprehensively consider the effect of the uncertainties of reaction rate parameters, thermodynamic parameters, and transport parameters on model predictions, local sensitivity analysis, local-sensitivity-based uncertainty analysis (LSUA), and random-sampling high dimensional model representation (RS-HDMR) method were coupled to investigate the uncertainty propagation of the chemical kinetic parameters to the calculated laminar flame speed of dimethyl ether under a wide range of conditions using a detailed mechanism. First, the uncertainty analysis was conducted using the local sensitivity analysis and the LSUA method under a wide range of operating conditions to identify the important operating conditions and chemical kinetic parameters. It is found that the prediction uncertainty of laminar flame speed is more obvious under the conditions of high dilution ratio, high pressure, and large equivalence ratio than that under other conditions. According to the results of LSUA, the prediction uncertainty is mainly from the reaction rate coefficients and thermodynamic data. Then, the uncertainty propagation from the significant parameters to the calculated laminar flame speed under important conditions was analysed using the RS-HDMR method. To reduce the huge computational cost of the RS-HDMR method, the backpropagation artificial neural network was employed. The RS-HDMR results indicate that the reaction H + O2 = O + OH has the highest sensitivity coefficient under the whole investigated conditions, which is different from the results using the LSUA method. The non-linear relationship between the rate coefficient and the predicted laminar flame speed is responsible for the discrepancy. Furthermore, it is found that the sensitivity coefficient of the input parameters strongly depends on the operating conditions.

High sperm concentration during cryopreservation decreases post-thaw motility percentage without compromising in vitro fertilization outcomes in common carp

To avoid mechanical compression of spermatozoa during the cryopreservation, a high dilution ratio with the cryoprotective medium is applied. Due to this, the sample volume increases, which entails increased cryobank capacity. Moreover, the high volume of cryomedias does not allow to fertilize of large volumes of eggs in practical artificial reproduction of common carp aquaculture. The current study demonstrated that reasonable lowering of dilution rates might still be effective for carp sperm cryobanking —elevation of spermatozoa concentration up to 13 × 109 spz mL−1 resulted in a significant decrease in post-thaw sperm motility percentage to 20% compared with 39% in 0.5 × 109 spz mL−1. Nevertheless, no significant differences in sperm kinetic parameters (VCL and LIN) were found in this case. The fertilization outcome (embryo development and hatching rates) was similar after applying thawed sperm samples with “optimal” (2.2–2.4 × 109 spz mL−1) and “sub-optimal” (11.0–13.0 × 109 spz mL−1) concentrations (sperm/egg ratio at fertilization was in the range of 0.3–4.5 × 105 spz/egg). Thus, applying a low dilution rate such as one part of sperm to one of the cryoprotective mediums is favorable for decreasing cryo-storage space and the sperm volume needed to fertilize big egg numbers. The experiment also shows that the 4.5 × 105 spz/egg ratio is not sufficient for good fertilization, and it is necessary to use higher sperm concentrations per egg or improve the method of fertilization.

Effects of laser remelting on microstructural characteristics of Ni-WC composite coatings produced by laser hot wire cladding

The work presented in this paper focused on the effects of laser remelting with varied laser energy densities from 800 J/mm to 1400 J/mm on the phase transformation and microstructural characteristics in the tungsten carbide nickel-based matrix composite (Ni-WC) tracks obtained by laser hot wire cladding. The microstructures of the as-deposited tracks fabricated by laser hot-wire deposition were mainly composed of spherical residual carbons, eutectic Ni/Ni3B, retained WC/W2C particles and the granular in situ W2C particles formed in the interdendritic regions of primary (Ni,Fe) dendrites. When the low laser energy densities of 800 J/mm and 1000 J/mm were applied, the dispersive W2C particles in the as-deposited tracks were dissolved, and the WC particles were successfully in situ synthesized and uniformly distributed in the remelted tracks. When the laser energy density was increased to 1200 J/mm, the feather-like M6C(Ni2W4C) carbides homogeneously precipitated in the remelted tracks. When the laser energy density was further increased to 1400 J/mm, the dissolution degree of the ex-situ WC/W2C particles was significantly increased, resulting in a remelted track with a relative low volume fraction of retained ceramic particles and a high dilution ratio of the base metal. In addition, the dendritic M6C(Fe3W3C) carbides were precipitated around the retained particles, and the eutectic M6C(Fe3W3C) carbides in the herringbone morphology were uniformly distributed in the matrix of the track remelted by a high laser energy density of 1400 J/mm. These experimental results confirmed that the homogenization of the in situ synthesized reinforcements in the tracks could be well realized by laser hot wire cladding and the subsequent laser remelting. The coatings remelted by the low energy densities (800 J/mm and 1000 J/mm) possessed higher wear resistance than that of the as-deposited coating, but the wear performance of the remelted coatings was decreased when the laser energy densities were increased to 1200 J/mm and 1400 J/mm.

An updated empirical correlation formalism for laminar flame speeds: Application to a TRFE gasoline surrogate in highly diluted conditions

In order to comply with present and future stringent environmental policies, engine manufacturers have to improve engine design and control to achieve combustion with high dilution ratios. The use of CFD simulations with complex combustion chemistry remains prohibitive, and alternatives to assess quickly the laminar flame speeds at local grid cell conditions (temperature, pressure, equivalence ratio, and dilution ratio) are desired, such as empirical correlations. Whereas these correlations should ideally be obtained from experimental measurements, comprehensively validated kinetic models can help extend databases to conditions that cannot be achieved practically. Hence, the present study proposed a reduced kinetic mechanism, containing 593 species and 3698 reactions, for one gasoline surrogate, namely Toluene Reference Fuel with Ethanol addition (TRFE). It is obtained by first compiling sub-mechanisms from the literature for the four components (isooctane, n-heptane, toluene, and ethanol) with updates of some key rate constants, and then is reduced for 1-D flame speed computations. The model was first validated against recent experimental laminar flame speed measurements of TRFE/air/diluent mixtures for various temperatures, pressures, equivalence ratios, and dilution ratios and then employed to extend the experimental database for the TRFE surrogate to higher dilution ratios and temperatures. A new formalism, including new mathematical expressions for the reference and dilution terms, and the temperature exponent are proposed. This new formalism exhibits improved abilities in fitting the laminar flame speeds, especially at high dilution ratios and in very fuel-lean and fuel-rich conditions. A new mathematical correlation based on these formulas was developed, whose correlation parameters were obtained by fitting both experimental data and mechanism predictions. Regardless of the conditions, the present correlation is observed to show overall good agreements with available experimental data in the literature for laminar flame speeds and their dependence on equivalence ratio, temperature, pressure, and dilution. Results show that the effect of dilution in reducing flame speeds is not linear and depends on the equivalence ratio. A parameter μ is defined in the correlation formulas to evaluate the dilution effectiveness of the diluent, which is found to be composition-specific and possibly follows a linear mixing rule for diluent mixtures.

Laser hot-wire cladding of Ni/WC composite coatings with a tubular cored wire

Ni/WC composite coatings were successfully prepared on carbon steel by the method of laser hot-wire cladding with a tubular cored wire. The processing characteristics, phases compositions, microstructural evolution, and wear resistance of the coatings were systematically investigated. A high-speed camera was used to investigate the wire transfer behaviors under various processing parameters which included the laser power of 1000 W, wire feeding speed of 4 mm/s, laser scanning speed of 2 mm/s, and different preheating currents (0∼100A). Three typical wire transfer modes including wire stubbing transfer (0∼50A), wire plunging transfer (55∼80A), and wire fusing transfer mode (90∼100A) were obtained. The coating microstructure was mainly consisted of the retained particles, Ni-dendrites, Ni/Ni3B eutectic structure, and various kinds of precipitations including WC, W2C and M6C (M = Fe, Ni, W) carbides. It was found that the wire transfer mode was a critical factor of influencing the geometrical and microstructural characteristics of the coatings. The WC particles could be generated in the coatings when the lower dilution degree (0.8∼1.2 %) was obtained under the wire stubbing transfer mode. When the wire plunging transfer was produced as the total energy input was increased, the homogeneously distributed W2C particles could preferentially be precipitated in the coatings with a relatively low dilution (1.9∼7.9 %). The M6C carbides were mainly formed in the coatings with a high dilution ratio (12.1∼13.9 %) fabricated under the wire fusing transfer mode. The coatings fabricated under wire plunging transfer mode exhibited higher wear resistance which was about 31∼51 times higher than that of substrate.

Modeling short fiber deformation in dilute suspension: Fiber deposition process

A new process to align short fibers into a preform for composite applications has been developed. The short fibers are dispersed in a fluid at a high dilution ratio. During fluid extraction, the fibers decelerate with respect to the fluid velocity and are subjected to significant forces that provide the mechanism to align the fibers. In this study, a model that describes the motion and deformation of a flexible elastic fiber in low Reynolds number flow is formulated. The governing equations are described and forces acting on the fiber are estimated. The numerical implementation of the model is described, and its numerical performance is evaluated. Several validation checks are performed to determine if the model is capturing the experimentally observed phenomena and if the estimated parameters provide reasonable quantitative agreement with experimental observations. The model is then applied to several simple examples such as the evaluation of bending stress (moment) and the associated fiber deformation (buckling behavior) versus the results observed in the process. The effect of fiber boundary condition is demonstrated. It is shown that the model can describe the buckling-like slow folding of the misaligned fiber. Finally, the model utility is demonstrated by a simple parametric study which explores the influence of process parameters on the fiber alignment process.

A study on autoignition characteristics of H2-O2 mixtures with diluents of Ar/N2 in rapid compression machine for argon power cycle engines

The autoignition features of H2-O2 are crucial for Argon Power Cycle (APC) engines to understand the abnormal combustion in spark-ignition mode and to realize stable ignition in compression-ignition mode. A well-validated H2-O2 mechanism is a cornerstone to all hydrocarbon reaction kinetics emphasizing its importance in fundamental research. Here measurements of the ignition delay times of H2-O2 mixtures have been conducted in a rapid compression machine at 1.0, 3.0, and 5.0 MPa, 903 ~ 1042 K, with excess oxygen ratio of 1.0, 2.0, and 4.0, dilution ratio of 70%, 80%, and 90%, with argon ratio in the diluent of 50%, 60%, 70%, and 75%. 394 data points and 85 data sets were consequently obtained. A comprehensive comparison between 17 selected literature mechanisms was then performed. Results show that the ignition delay time of H2 is very sensitive to the temperature, especially near the ignition limit. The argon ratio in the diluent has a remarkable effect on the ignition delay. High pressure accelerates the autoignition, while both a high dilution ratio and a high excess oxygen ratio inhibit the autoignition. This research work suggests that a combination of highly diluted and ultra-lean combustion may inhibit knock in APC engines. H + O2 (+M) = HO2 (+M) and H + O2 = O + OH are the most sensitive reactions at 1.0 MPa over 950 K, while 2OH (+M) = H2O2 (+M) and H + H2O2 = H2 + HO2 are the most sensitive reactions at both 3.0 and 5.0 MPa.

Initiation characteristics of spark-ignited premixed hydrogen-oxygen flames with diluents of argon/nitrogen/carbon dioxide

The spark-ignition features of premixed H2 under Ar–O2 atmospheres are essential for the development of high-efficiency and zero-emission Argon Power Cycle engines. Therefore, constant-volume combustion vessel experiments are conducted at an initial temperature of 287 K, initial pressures of 0.1, 0.3, and 0.5 MPa, with diluents of Ar/N2/CO2. Excess oxygen ratio, defined as the ratio of O2 supplied to the O2 needed for stoichiometric combustion, ranges from 1.0 to 4.7. Dilution ratios, defined as the molar fractions of diluents in the diluent-O2 mixture, were separately 70%, 79%, and 88%. Results show that both high dilution ratios and high excess oxygen ratios lengthen the flame-initiation periods. With excess oxygen ratio of 3.3, when Ar dilution ratio increases from 79% to 88%, the flame-initiation period rises by a factor of five to ten. With Ar diluent ratio of 79%, when excess oxygen ratio increases from 2.5 to 4.7, the flame-initiation period rises from under 10 ms to over 60 ms. Both the application of Ar as the diluent and high initial pressures extend the flammability limits. With Ar dilution ratio of 79% and pressure no less than 0.3 MPa, the flammability limit on excess oxygen ratio is over 4.7. Furthermore, Ar can additionally shorten the flame-initiation periods. At 0.1 MPa, excess oxygen ratio of 2.5, when diluents are respectively Ar, N2, and CO2, the flame-initiation periods are 10, 19, and 41 ms. The research reveals that a spark-ignition Argon Power Cycle engine running with ultra-lean and highly diluted mixtures may be feasible.

Particle number emissions from light-duty gasoline vehicles in Beijing, China

Humans are more likely to be exposed to ultrafine particles (UFPs) emitted by light-duty gasoline vehicles (LDGVs) in urban road traffic, which can cause serious bodily harm. In this study, we conducted on-road measurement of the Particle Number (PN) emissions from 18 China-3, China-4, and China-5 LDGVs on representative roads in Beijing. To clarify the impact of key parameters (standards, driving conditions, and technology) on the PN emissions, we conducted a comprehensive analysis of the emission results. We found the PN emission factors (EFs) of port fuel injection (PFI) vehicles have declined considerably under stricter standards. Furthermore, we found the average EF of China-5 LDGVs with gasoline direct injection (GDI) was 10 times that of PFI vehicles, and the PN EFs of PFI vehicles increase as the age of the engine increases (R2 = 0.59). In different operating conditions, the PN EFs of all test vehicles under highway driving conditions were lower than those under non-highway driving conditions (6.5%–82.0%). The PN EFs of PFI LDGVs going uphill are 1.4–2.8 times those when going downhill. The PN EFs of LDGVs under start-up were 18–47% higher than under hot-running. PN emissions were high under positive engine power and increased with vehicle specific power. The dilution ratio has a significant impact on the test results, especially in a higher vehicle specific power interval, indicating that a high dilution ratio may lead to deviation of test values. Further research needs to determine the optimal dilution ratio to minimize test deviation. This study provides important data support for PN emission control. The optimal upper limit of the primary dilution ratio should be further studied and specified as a standard.

Design and optimization of passivation layers and emitter layers in silicon heterojunction solar cells

&lt;sec&gt;Silicon heterojunction (SHJ) solar cells have attracted much attention in the international photovoltaic market due to their high efficiencies and low costs. The quality of amorphous silicon/crystalline silicon (a-Si:H/c-Si) interfaces of SHJ solar cells has a key influence on the device performance. Therefore, the carrier recombination rate of a-Si:H/c-Si interface needs to be effectively controlled. In addition, as the important component of SHJ solar cells, the p-type emitter must meet the requirements for high conductivity, high light transmittance, and energy band matching with c-Si. The research contents and the relevant achievements of this paper include the following aspects. &lt;/sec&gt;&lt;sec&gt;Firstly, in order to reduce the surface defects and realize the energy band alignment of a-Si:H/c-Si interface, the effect of passivation layer on passivation effect is studied. An ultra-thin buffer layer deposited by a low power and a high hydrogen dilution ratio is inserted between the conventional passivation layer and c-Si to improve the passivation effect and broaden the process window of passivation layer. The effects of the buffer layer thickness and hydrogen dilution ratio on passivation quality are further studied, and the best experimental conditions of buffer layer are obtained. The experimental results show that the sample with double-layered passivation layer is more stable than the conventional passivation layer. The minority carrier lifetime of the sample with single conventional passivation layer is 3.8 ms and the &lt;i&gt;iV&lt;/i&gt;&lt;sub&gt;OC&lt;/sub&gt; is 712 mV, while the minority carrier lifetime of the sample with double-layered passivation layer is 4.197 ms and the &lt;i&gt;iV&lt;/i&gt;&lt;sub&gt;OC&lt;/sub&gt; is 726 mV.&lt;/sec&gt;&lt;sec&gt;Secondly, for the p-type emitters of silicon heterojunction solar cells, the effects of doping level on the photoelectric properties of p-type hydrogenated nanocrystalline silicon (nc-Si:H) thin films are studied. On this basis, the p&lt;sup&gt;++&lt;/sup&gt;-nc-Si:H/p-nc-Si:H double-layer emitter with wide band gap and high conductivity is designed and fabricated. By analyzing the optical and electrical properties of different emitters, it is found that p-nc-Si:H has good electrical and optical properties. Owing to the high doping efficiency of nc-Si, a small amount of doping can obtain high conductivity. Lightly doped p-nc-Si:H provides a better contact with the passivation layer, while heavily doped p&lt;sup&gt;++&lt;/sup&gt;-nc-Si:H can not only provide enough built-in electric field, but also improve the contact characteristics of p/ITO, thus enhancing the output characteristics of the cell. At the same time, the deposition of p-nc-Si:H layer with high hydrogen dilution ratio can also implement the hydrogen plasma treatment on the passivation layer, the reduction of the dangling bonds on the surface of the c-Si, the enhancement of the chemical passivation effect, and thus improving the open circuit voltage of the cell. &lt;/sec&gt;&lt;sec&gt;Finally, a silicon heterojunction solar cell with an efficiency of 20.96% is obtained based on the commercial czochralski silicon wafer, with an open circuit voltage of 710 mV, a short circuit current density of 39.88 mA/cm&lt;sup&gt;2&lt;/sup&gt; and filling factor of 74.02%.&lt;/sec&gt;

Particle size measurement of electronic cigarette aerosol with a cascade impactor

Measuring the aerosol particle size of electronic cigarettes can be particularly challenging due to the volatile and dynamic nature of these aerosols. In particular, electronic cigarette aerosol particle size measurements may be convoluted by evaporation due to the high dilution ratios and coagulation when there are long residence times between sampling and measurement. To address these measurement issues, we have developed a particle size measurement system using a low flow cascade impactor with a sampling system that is capable of generating a puff on an e-cigarette and directly introducing the aerosol into the inlet flow of the impactor. The system has been used to investigate factors that may affect the aerosol size distribution, including puffing conditions, carrier composition and device construction. It was found that decreasing the puff flow rate from 2 to 0.5 L/min at a constant puff duration of 5 s, the mass median aerodynamic diameter (MMAD) of the aerosol size distribution increased from 0.5 to 1.1 µm. Increasing the mass delivery from 0.67 to 6 mg/5 s puff also resulted in increasing MMAD from 0.48 to 0.87 µm. Furthermore, the addition of a small amount of glycerin (1% by weight) to a propylene glycol based flavor formulation caused a decrease in the MMAD, while the other factors studied did not have a significant effect on the MMAD.Copyright © 2020 American Association for Aerosol Research

A lattice model on the rate of in vivo site-specific DNA-protein interactions

We develop a lattice model of site-specific DNA-protein interactions under in vivo conditions where DNA is modelled as a self-avoiding random walk that is embedded in a cubic lattice box resembling the living cell. The protein molecule searches for its cognate site on DNA via a combination of three dimensional (3D) and one dimensional (1D) random walks. Hopping and intersegmental transfers occur depending on the conformational state of DNA. Results show that the search acceleration ratio (= search time in pure 3D route/search time in 3D and 1D routes) asymptotically increases towards a limiting value as the dilution factor of DNA (= volume of the cell/the volume of DNA) tends towards infinity. When the dilution ratio is low, then hopping and intersegmental transfers significantly enhance the search efficiency over pure sliding. At high dilution ratio, hopping does not enhance the search efficiency much since under such situation DNA will be in a relaxed conformation that favors only sliding. In the absence of hopping and intersegmental transfers, there exists an optimum sliding time at which the search acceleration ratio attains a maximum in line with the current theoretical results. However, existence of such optimum sliding length disappears in the presence of hopping. When the DNA is confined in a small volume inside the cell resembling a natural cell system, then there exists an optimum dilution and compression ratios (= total cell volume/volume in which DNA is confined) at which the search acceleration factor attains a maximum especially in the presence of hopping and intersegmental transfers. These optimum values are consistent with the values observed in the Escherichia coli cell system. In the absence of confinement of DNA, position of the specific binding site on the genomic DNA significantly influences the search acceleration. However, such position dependent changes in the search acceleration ratio will be nullified in the presence of hopping and intersegmental transfers especially when the DNA is confined in a small volume that is embedded in an outer cell.

Laser Surface Alloying of Austenitic 316L Steel with Boron and Some Metallic Elements: Microstructure.

Austenitic 316L steel is known for its good oxidation resistance and corrosion behavior. However, the poor wear protection is its substantial disadvantage. In this study, laser surface alloying with boron and some metallic elements was used in order to form the surface layers of improved wear behavior. The microstructure was studied using OM, SEM, XRD, and EDS techniques. The laser-alloyed layers consisted of the only re-melted zone (MZ). The hard ceramic phases (Fe2B, Cr2B, Ni2B, or Ni3B borides) occurred in a soft austenitic matrix. The relatively high overlapping (86%) resulted in a uniform thickness and homogeneous microstructure of the layers. All the laser-alloyed layers were free from defects, such as microcracks or gas pores, due to the use of relatively high dilution ratios (above 0.37). The heat-affected zone (HAZ) wasn’t visible in the microstructure because of the extended stability of austenite up to room temperature and no possibility to change this structure during fast cooling. The use of the mixtures of boron and selected metallic elements as the alloying materials caused the diminished laser beam power in order to obtain the layers of acceptable quality. The thickness of laser-alloyed layers (308–432 μm) was significantly higher than that produced using diffusion boriding techniques.

Purifying effect of biochar-zeolite constructed wetlands on arsenic-containing biogas slurry in large-scale pig farms

To explore the purifying effect of vertical subsurface flow constructed wetlands (CWs) on arsenic-containing biogas slurry in pig farms under natural conditions in the field, vertical subsurface flow CWs with water spinach-Pennisetum sinese as the core was constructed in this study. Under the condition of biogas slurry with different dilution ratios (2, 4, 6; v/v) was fed to the wetlands and different substrates (biochar and zeolite) were added to the wetlands, respectively, the removal efficiency of the pollutants in biogas slurry by CWs were investigated. The enrichment of arsenic (As) in wetland substrates and three wetland plants (water spinach, green Pennisetum sinese and purple Pennisetum sinese) was analyzed. The results showed that, the removal rate of ammonia nitrogen (NH4+-N) in biogas slurry at low dilution ratio was always higher in the CWs, while that of total phosphorus (TP), chemical oxygen demand (COD) and As was higher in biogas slurry at high dilution ratio at first and then was just the opposite. The addition of zeolite and biochar could enhance the decontamination effect of CWs. Zeolite had better removal effect on NH4+-N, TP and COD, while biochar showed better removal effect on As. At low dilution ratio, the enrichment of As was high in the wetland sediments and three wetland plants. Adding biochar and zeolite increased the enrichment and absorption of As by sediments, water spinach and purple Pennisetum sinese, which was more significant by adding zeolite than biochar. However, they slightly reduced the absorption of As by green Pennisetum sinese. The detailed effluent quality assessment showed TP and NH4+-N to be significant pollution factors. The CWs treated with zeolite showed a higher purifying effect, while the CWs added without the two substrates had a lower purifying effect. This study provides a theoretical basis for the practical application of CWs in livestock and poultry wastewater treatment.

Microstructural evolution of laser-clad 75Cr3C2+25(80Ni20Cr) powder on Inconel 718 superalloy

Abstract Nickel-based superalloys such as Inconel 718 are widely used in the aerospace industry. The surface properties of Inconel 718 can be improved by the addition of chromium carbide–nickel chromium powder. In this study, 75Cr3C2+25(80Ni20Cr) powder was clad on annealed Inconel 718 superalloy by using a pulsed Nd:YAG laser. The aim of this research is to investigate the effect of laser process parameters such as pulse width, laser frequency and scanning speed on the microstructure and microhardness of the clad samples. It is found that the increasing pulse width and laser frequency or decreasing scanning speed can increase the heat input and the resultant dilution ratio. The clad zone of the samples with a high dilution ratio consists of eutectic structure (γ and Cr7C3). However, the clad zone of specimens with a low dilution ratio is composed of a hypereutectic structure of Cr7C3+(γ+Cr7C3). This microstructure leads to the significant increase in the hardness value in comparison with the specimens with a high dilution ratio, due to the presence of proeutectic Cr7C3 carbides in the hypereutectic structure. The maximum hardness value of the clad zone is found to increase almost 2.5 times that for the substrate in the annealed condition. However, the austenitic and Laves phases are formed in the partially mixed zone. This zone is rather narrow, approximately 30 μm. The grain coarsening occurs in the heat-affected zone of all the deposited specimens. The hardness values of the partially mixed and heat-affected zones are lower than that for the clad zone.

Cow manure anaerobic fermentation effluent treatment by oxygen-based membrane aerated biofilm reactor

After cow manure undergoes anaerobic fermentation process, it still contains several pollutants such as nitrogen, phosphorus, and organic matter. If not treated properly, these pollutants would cause secondary pollution. Membrane-aerated biofilm reactor (MABR) has been widely used to handle the wastewater with high concentration contaminants. In this study, MABR was utilized to treat the cow manure anaerobic fermentation effluence (CMAFE). In order to avoid incomplete biofilm being affected by high concentration of CMAFE, a gradient dilution of CMAFE was employed. The removal rates of NH4+-N and COD were achieved up to 90% and 85%, respectively, in different dilution ratios. RDA demonstrated that NH4+-N removal was in a full-nitrification process in higher dilution ratio (Stage 1 and 2) but in short-nitrification in lower dilution ratio (Stage 4). The gradient dilution did not affect the biofilm growth. The Inner biofilm contained higher amounts of extracellular polymeric substance (EPS) than the Outer biofilm, which reduced the impact of high-concentration CMAFE on the internal aerobic bacteria, especially nitrifying bacteria. Concerning bacteria abundance, a significant modification occurred in the biofilm compared to raw sludge, demonstrating that MABR had a great potential in CMAFE treatment.