Maximum Water Content Research Articles

Application of ultrasonic treatment for demulsification of stable water-in-oil emulsions

In this work, the prospects of using ultrasonic treatment together with a nanosized additive for destruction of stable water-in-oil emulsions of the W/O type of various compositions and properties, with 30–45 μm average diameter droplets, including those containing “gel”, are shown. The influence of such sonication parameters as power and exposure time on the separation efficiency of emulsion in batch mode has been studied. The research was carried out on ultrasonic devices of a submerged and a reactor type. It is shown that destruction above 99% of all the studied emulsions is achieved by using ultrasonic treatment with 1.0 kW power together with the addition of nanopowder AlN suspension in acetone. The exposure time comprised 0.5–3 min, the amount of the additive was equal to 4–8 %vol (depending on the composition and properties of the emulsion). The developed method of demulsification allows to obtain the oil phase with maximum water content of 0.5 wt% and the aqueous phase with maximum oil content of 46 mg L−1. Application of this approach leads to a significant decrease of oily waste formation.

黄土丘陵区坡耕地与撂荒地土壤水分对降雨的响应特征

为了揭示黄土丘陵区不同土地覆被方式下土壤含水量对不同强度降雨的响应过程，选取山西省冯家沟小流域农耕地和撂荒地为研究对象，基于2019年4-10月降雨和土壤含水量以小时为单位的观测数据，分析了土壤含水量对不同强度降雨的响应规律。结果表明：（1）小雨、中雨、大雨和暴雨对土层的影响深度分别为20、20、60 cm和60 cm，研究区降雨最主要的形式-小雨对土壤水分的补给作用较小。（2）各强度降雨过程中，除0-10 cm土层外，农耕地土壤含水量均大于撂荒地，且大雨条件下农耕地各土层土壤含水量变化较显著，而撂荒地仅0-10 cm和10-20 cm土层土壤含水量有所增加。（3）不同土层土壤含水量对降雨的响应不同，表层响应相对明显而深层相对减弱；农耕地土壤平均含水量最大值出现在50-60 cm土层，而撂荒地出现在30-40 cm土层。（4）本地区农耕地土壤含水量高于撂荒地，表明在该地区适当的作物种植有较好的储存土壤水分的作用。本研究的结果对地区水资源的高效利用和水土流失防控提供了一定的科学依据。;In order to reveal the response process of soil water content to different rainfall intensities under different land cover modes in Loess hilly region. This study selected the cultivated land and abandoned land in Fengjiagou small watershed of Shanxi Province as the research objects. Based on the observation data of rainfall and soil water content in hours from April to October 2019, the response of soil water content to different rainfall intensities was analyzed. The results showed that:(1) The influence depths of light rainfall, moderate rainfall, heavy rainfall and torrential rainfall on soil layer were 20, 20, 60 cm and 60 cm, respectively. The main form of rainfall-light rainfall had little effect on soil moisture in the study area. (2) During each rainfall intensity, except 0-10 cm soil layer, the soil water content of the cultivated land was higher than that of abandoned land, and the soil water content of each soil layer in the cultivated land changed significantly under heavy rainfall conditions, while the soil water content of abandoned land was only increased in 0-10 cm and 10-20 cm soil layers. (3) The content of soil water among soil layers had different response to rainfall, and the response of surface soil moisture was more responsive than that of the deep soil water content. The maximum average soil water content appeared in 50-60 cm soil layer in the cultivated land, while the abandoned land appeared in the 30-40 cm soil layer. (4) The soil water content of the cultivated land was higher than that of the abandoned land, indicating that appropriate crop planting in this region had a better role in storing soil moisture. The results of this study provide a scientific basis for the efficient utilization of regional water resources and the prevention and control of soil erosion.

THE IMPORTANCE OF USING MULTIPLE ANALYSES TECHNIQUES TO DETERMINE THE PHYSICAL CONDITION OF THE WATERLOGGED WOOD NEAR THE CORRODED PARTS

In this study, three samples taken from the planks of the Yenikapı 29 shipwreck were analysed. Firstly, the maximum water content (MWC) and basic density values of the samples were calculated. MWC of the IK13-1 was 164% and the MWC of the SK6-1 was 87%. Because of these low MWC values, samples could be classified as non-degraded. When the SEM images of these two samples were examined, it was understood that the IK13-1 sample was non-degraded but the SK6-1 sample was penetrated with corrosion product and could not be classified as non-degraded. With these analyses, the XRF method was used to measure the iron amounts of the samples. The iron amount of the SK6-1 was 32.3% and the corrosion accumulation in this sample was also proved with XRF. In order to avoid incorrect results, multiple analysis techniques should be used for determining the physical condition of the waterlogged wood near the corroded parts.

A Bio-Based Hydrogel Derived from Moldy Steamed Bread as Urea-Formaldehyde Loading for Slow-Release and Water-Retention Fertilizers.

In this work, a novel slow-release and water-retention nitrogen (N) fertilizer (SRWRNF) was prepared using moldy steamed bread-based starch-g-poly(acrylic acid-co-acrylic amide) (SBS-g-P(AA/AM)) as the skeleton and urea-formaldehyde oligomers (UF) incorporated as the slow-release N source by semi-interpenetrating methods. Various analysis technologies including scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry were used to characterize the structure and properties of SRWRNFs. Swelling measurements indicated that the maximum water absorbency of SBS-g-P(AA/AM)-UF samples was 104.2 g/g in distilled water. The water-retention study showed that the SBS-g-P(AA/AM)-UF improved the maximum soil water content by 15.3–17.6% while improving soil water-retention capacity. N release experiments confirmed that SBS-g-P(AA/AM)-UF enabling offered a gradual N supply in soil. In comparison to conventional urea and UF fertilizers, the maize yield of SBS-g-P(AA/AM)-UF was increased by 20.3 and 9.7%, respectively. This study implies that the SRWRNFs provide a promising feasibility for large-scale applications in agriculture.

Mechanical Properties of Furnace Slag and Coal Gangue Mixtures Stabilized by Cement and Fly Ash.

The mechanical properties and strength formation mechanism of cement–fly-ash-stabilized slag–coal gangue mixture were examined using an unconfined compressive strength test, splitting strength test, triaxial test, and scanning electron microscopy to solve the limitations of land occupation and environmental pollution that is caused by fly ash from the Xixia District thermal power plant in Yinchuan, slag from the Ningdong slag yard, and washed coal gangue. Its performance as a pavement base mixture on the road was investigated. The results demonstrated that as the slag replacement rate increased, the maximum water content increased while the maximum dry density decreased. The addition of slag reduced the unconfined compressive strength and splitting strength of the specimens; furthermore, the higher the slag substitution rate, the lower the unconfined compressive strength and splitting strength of the specimens. As the cement content increased, the specimen’s unconfined compressive strength increased. Based on the principle of considering the mechanical properties and economic concerns, the slag replacement rate in the actual construction should be ~50% and should not exceed 75%. Based on the relationship between the compressive strength and splitting strength of ordinary concrete, the relationship model between the unconfined compressive strength and splitting strength of cement–fly-ash-stabilized slag–coal gangue was established. The failure mode, stress–strain curve, peak stress, and failure criterion of these specimens were analyzed based on the triaxial test results, and the relationship formulas between the slag substitution rate, cement content, peak stress, and confining pressure were fitted. As per the SEM results, the mixture’s hydration products primarily included amorphous colloidal C-S-H, needle rod ettringite AFt, unhydrated cement clinker particles, and fly ash particles. The analysis of the mixture’s strength formation mechanism showed that the mixture’s strength was the comprehensive embodiment of all factors, such as the microaggregate effect, secondary hydration reaction, and material characteristics.

The \u2018excess gas\u2019 method for laboratory formation of methane hydrate-bearing sand: geotechnical application

Over recent years, there has been a growing interest in producing methane gas from hydrate-bearing sands (MHBS) located below the permafrost in arctic regions and offshore within continental margins. Geotechnical stability of production wellbores is one of the significant challenges during the gas extraction process. The vast majority of geotechnical investigations of MHBS have been conducted on laboratory-formed samples due to the complex procedure of undisturbed sample extraction. One of the most commonly used hydrate laboratory-formation methods is the excess-gas method. This work investigates fundamental aspects in the excess-gas formation of MHBS that are affecting the geotechnical interpretation and modeling. The work finds that (1) the measured temperature in the experimental system may be quite different from the in-sample temperature, and can reach 4 ^circC difference during thermodynamic processes. This potential difference must be considered in investigation of hydrate formation or dissociation, (2) various calculation approaches may yield different hydrate saturation values of up to tens of percentages difference in high hydrate saturations. The calculation formulas are specified together with the fundamental difference between them, (3) the water mixture method during the sample assembling is critical for homogeneous MHBS laboratory formation, in which a maximum initial water content threshold of 9.1 to 1.3 % are obtained for a minimal fraction size of 0.01 to 0.8 mm, respectively, (4) the hydrate formation duration may influence the MHBS properties, and should be rigorously estimated according to the real-time gas consumption convergence. The outcomes of this work may contribute to the integration of data sets derived from various experiments for the study of MHBS mechanical behavior.

Influence of Rock Block Content on Compaction Characteristics of Graded Coarse-Grained Fillers

The bearing capacity, stability, and durability of subgrade are affected by the compaction quality of fillers to a large extent. In this study, samples of graded coarse-grained fillers with different rock block contents were designed and prepared with the aid of an improved continuous gradation equation for coarse-grained soils. Then standard compaction tests of these samples with different water content conditions were conducted to understand the influence of rock block content on the compaction characteristics of graded coarse-grained fillers. Results show that the compaction curve peaks of graded coarse-grained fillers always increase with the rock block content. The maximum dry density of graded coarse-grained fillers increases linearly with the rock block content in approximation, while the optimal water content is the opposite. The optimal water content of graded coarse-grained fillers decreases in nonlinearity with characteristics of rapidly first and then slowly. Two empirical formulas about the rock block content were summarized for predicting the maximum dry density and optimal water content of graded coarse-grained fillers. The results of this study can provide a reference for the engineering application of graded coarse-grained fillers.

Joint Monitoring and Analysis of Sea Fog Using Dual Visibility Lidar in Ningbo, China

Visibility lidar has obvious monitoring advantages over forward scatter visibility sensors or fog droplet spectrometers; it can measure visibility information over a large area. In 2021, two visibility lidar instruments (1064 or 532 nm wavelengths) were installed in Beilun, Ningbo Zhoushan Port, to monitor sea fog. Comparing their monitoring data to those of forward scatter visibility sensors and a fog droplet spectrometer revealed that the visibility lidar instruments could obtain energy progress information section-by-section in the monitoring path, and could directly reflect sea fog changes. The 1064 nm lidar outperformed the 532 nm lidar regarding sea fog detection. The effective detection range decreased significantly with decreasing visibility; the reliability decreased in low-visibility, uneven atmospheres. In a low-visibility but uniform atmosphere, however, lidar data corresponded well with forward dispersion data. The 532 nm and 1064 nm lidar data sometimes differed at the same monitoring position owing to differing heights and particle reflection angles. During a sea fog event on May 9, 2021, the maximum droplet concentration was 14 cm−3, the maximum liquid water content was 0.21 g·m−3, and the maximum equivalent diameter was 49 μm. The formation of this sea fog was dominated by large particles.

Kernel Water Relations and Kernel Filling Traits in Maize (Zea mays L.) Are Influenced by Water-Deficit Condition in a Tropical Environment.

Water deficit is a major limiting condition for adaptation of maize in tropical environments. The aims of the current observations were to evaluate the kernel water relations for determining kernel developmental progress, rate, and duration of kernel filling, stem reserve mobilization in maize. In addition, canopy temperature, cell membrane stability, and anatomical adaptation under prolonged periods of pre- and post-anthesis water deficit in different hybrids was quantified to support observations related to kernel filling dynamics. In this context, two field experiments in two consecutive years were conducted with five levels of water regimes: control (D1), and four water deficit treatments [V10 to V13 (D2); V13 to V17 (D3); V17 to blister stage (D4); blisters to physiological maturity (D5)], on three maize hybrids (Pioneer 30B80, NK 40, and Suwan 4452) in Expt. 1. Expt. 2 had four water regimes: control (D1), three water deficit treatments [V10 to anthesis (D2); anthesis to milk stage (D3); milk to physiological maturity (D4)], and two maize hybrids (NK 40 and Suwan 4452). Water deficit imposed at different stages significantly reduced maximum kernel water content (MKWC), kernel filling duration (KFD), final kernel weight (FKW), and kernel weight ear–1 while it increased kernel water loss rate (KWLR), kernel filling rate (KFR), and stem weight depletion (SWD) across maize hybrids in both experiments. The lowest MKWC under water deficit was at D3 in both experiments, indicating that lower KFR results in lowest FKW in maize. Findings indicate that the MKWC (R2 = 0.85 and 0.41) and KFR (R2 = 0.62 and 0.37) were positively related to FKW in Expt. 1 and 2, respectively. The KFD was reduced by 5, 7, 7, and 11 days under water deficit at D3, D4 in Expt. 2 and D4, D5 in Expt. 1 as compared to control, respectively. Water deficit at D5 in Expt. 1 and D4 in Expt. 2 increased KWLR, KFR, and SWD. In Expt. 2, lower canopy temperature and electrical conductivity indicated cell membrane stability across water regimes in NK 40. Hybrid NK 40 under water deficit had significantly higher cellular adaptation by increasing the number of xylem vessel while reducing vessel diameter in leaf mid-rib and attached leaf blade. These physiological adjustments improved efficient transport of water from root to the shoot, which in addition to higher kernel water content, MKWC, KFD, KFR, and stem reserve mobilization capacity, rendered NK 40 to be better adapted to water-deficit conditions under tropical environments.

Kernel filling and desiccation in temperate maize: Breeding and environmental effects

Sowing date (SD) modifies the environmental conditions during the kernel-filling period as well as during kernel dry down after physiological maturity (PM), particularly for late-sown maize (Zea mays L.) crops that currently cover 50 % of the maize area in Argentina. The main goal of this work was to evaluate breeding effects on kernel filling and kernel desiccation traits in a set of five commercial maize hybrids released by a single breeding program between 1980 and 2016 when grown under contrasting environments in the temperate Central Pampas region. The evolution of kernel weight (KW) and kernel moisture (KM) were assessed. Maximum KW (KWMAX), maximum kernel water content (KWCMAX), kernel filling rate (KFR), kernel filling duration (KFD) and KM at silking+20 days (KMR1+20) and PM (KMPM) were computed together with husks number. Pre-PM kernel desiccation was described using an exponential decay model with k1 as the proportionality drying coefficient. For the post-PM period, kernel desiccation was modelled assuming that the change in KM in a given period is proportional to the difference between the kernel and the equilibrium moisture contents, where k2 was the corresponding proportionality drying coefficient. For KWMAX, a genetic progress of 0.26 % year −1 (p < 0.05) was estimated from 1993 to 2016. This trend was explained by the increase registered in KFD (0.32 % year−1, p < 0.01), which was partially compensated by a reduction in KFR (−0.08 % year−1, p < 0.05). No genetic progress was detected for husks number, KWCMAX, KMR1+20, KMPM, k1 and k2, but introduction of dent germplasm produced an increase in KWCMAX, KMR1+20 and KMPM and a decrease in k2. KFR and KFD as well as kernel desiccation dynamics were strongly affected by SDs. Breeding effects that extended KFD, together with the broad adoption of late sowings, promote a reduction in k2, which must be considered for the correct assessment of trade-offs between drying costs and kernel quality penalization by pests and diseases.

Modeling water potential of cover crop residues on the soil surface

Cover crops are usually planted between cash crops to protect the soil, take up residual soil nitrate, and release nitrogen (N) to subsequent crops. Following cover crop termination, residues may remain on the soil surface, where their decomposition is largely dependent on residue temperature and water potential (ψresidue). While it is possible to continuously measure residue temperature, continuous measurements of ψresidue are impractical. Thus, a practical model to estimate ψresidue would be useful for models of residue decomposition. To obtain data for a model of ψresidue for cereal rye (Secale cereale L.) and crimson clover (Trifolium incarnatum L.), we conducted studies that evaluated the effects of (1) residue stage of decomposition on water release curve; (2) relative humidity (RH) on ψresidue; (3) soil moisture on residue gravimetric water content (θg);(4) precipitation on θg; and (5) diurnal changes in RH and temperature on ψresidue. Results showed that water release curves for cereal rye and crimson clover changed as decomposition progressed, and that parameters for these curves could be estimated from residue lignin content. Both types of residues rewetted at a similar rate when exposed to high RH, but when rewetted by rainfall, cereal rye required a lower amount of rainfall than crimson clover to reach maximum water content. Results of these studies were used to develop, calibrate, and validate a model of ψresidue that requires inputs of initial water and lignin contents of the residue as well as hourly values of relative humidity, air temperature, and precipitation. Comparison of observed vs. simulated data indicated the model simulates reasonably well the observed diurnal patterns of surface ψresidue with R2=0.84. Because this model requires a small set of parameters and input variables, its use may be more practical than that of more detailed models.

Determination of Cocoa Powder Quality Produced by Small-Medium Enterprise Using Six Sigma Analysis

Cocoa powder now has become a common craft product of small-medium processing enterprises (SME) in Indonesia. Small-medium enterprises developprocessing sequence in smaller quantity compared to big company, nonetheless it must follow the national cocoa powder standard of SNI 3737:2009. The aim ofthis experiment was to evaluate the SME cocoa process production performance through Six Sigma analysis of the product to comply the standard requirements.The cocoa powder product was evaluated using three critical to quality (CTQ) parameters involving water content, color, and fineness. National standard determinedthe maximum water content value is 5%, the color is brown or Agtron number 65 and minimum fineness percentage of particle (75 µm) must be 99.5%. This resultexplain the stability process of SME which is exceeding the control limit value of non conformity product. Its process capability showing the Sigma value of2.6 with defect per million value was 126,667. The CTQ parameters which contribute to the high non-conformity are fineness 78.95% and color 21.05%. The roughcocoa powder or fineness affects the highest non-conformity related to the high fat content in cocoa cake as input process and can be revised by upgrading thepressing machine performance.

A Sensitivity Analysis of the Anisotropy of Hydraulic Conductivity to the Seepage, Deformation and Stability of Anti-dipping Layered Rock Slopes: A Case Study of the Pulang Area in Southwestern China

In this paper, in order to study the influence of anisotropy ratios and anisotropy directions on the seepage, deformations and stability of the anti-dipping layered rock slopes, Geo-studio software was used in this study for the numerical analysis of carbonaceous slate slopes on the unsaturated seepage, fluid–solid coupling, and stability theory in Pulang area. The results showed that the maximum surface water content of the layered rock slopes gradually decreased with increases of the water conductivity anisotropy ratio and decreases in the anisotropy angle of the anti-dipping layered rock slopes. In addition, the rainfall infiltration depths in the middle sections of the slopes were observed to be the most affected by the anisotropy ratio and dip angles of the rock formations. Meanwhile, the bottom sections of slopes were the least affected by the anisotropy ratio and the dip angles of the rock formations. In regard to the anti-dipping rock slopes, it was found that the anisotropy ratio and rock layer dip angles should be considered in the deformation and stability analyses. When the seepage of an anti-dipping layered slope was considered to be isotropic, the safety factors often were overestimated. As the anisotropy ratio decreases and the anti-dipping angles of the layered planes increases, the safety factors of the slopes will gradually decrease. This study provided a feasible scheme for evaluating the seepage, deformations and stability of the anti-dipping layered rock slopes in southwest China’s Pulang area.

Soybean seed growth dynamics exposed to heat and water stress during the filling period under field conditions

AbstractSoybean production can be affected by heat (HS) and water stress (WS). However, studies on effects of stresses combination under field conditions are still scarce. The objective of this study was to evaluate the impact of HS, WS and their interaction (HS × WS) during seed filling on seed weight, seed growth rate (SGR) and seed filling duration (SFD) of same phenological age pods from different canopy positions. Two soybean genotypes were exposed to four treatments during seed filling: control (irrigated plots at ambient temperature), HS (plots under temperatures &gt;32°C for 6 hr/day during 15 days), WS (plots under 25% of soil water content, during entire seed filling) and HS × WS. Stresses interaction caused similar responses to WS alone, decreasing yield and its components (seed number and weight), as well as seed weight for each canopy position (SWCP), SGR and SFD. Non‐significant effect of irrigated HS and non‐additive effects was observed in HS × WS plots, exhibiting WS a dominant effect over HS. The SWCP strongly correlated with SGR, exhibiting upper position a trend to higher SWCP than lower one. Seed maximum water content and pod weight, positively associated with SWCP, indicated seed metabolic limitations under WS and HS × WS. Our results advance in the understanding of SW determination under abiotic stresses and highlight the importance of identifying pods of same phenological age to establish accurate comparisons between seeds from different canopy positions.

UJI KINERJA DAN KELAYAKAN FINANSIAL PENGERING PATI SAGU TIPE PNEUMATIC CONVEYING RING DRYER

Sago starch drying in remote areas or difficult to reach transportation requires artificial dryers to increase the quantity and quality of the dry sago starch. The purpose of this study was to test performance, and analyze the economic value of biomass powered pneumatic conveying ring dryer (PCRD) for drying sago starch for small scale commercial. This research was conducted in two stages, namely performance testing and financial analysis. Small scale (mini) PCRD has been created for drying sago starch with a capacity of 160 kg of dry sago starch per day. The resulting moisture content varies according to variations in temperature and initial moisture content of sago starch and has met the Indonesia National Standard (SNI) No. 3729 regarding the maximum water content of sago starch (13%), except at temperature variations of 50oC and 75oC with an initial moisture content of 41% that did not meet the SNI, which was greater than 13% (14.27% and 13.23%). The drying efficiency varies between 7.339% to 9.689%. Likewise, the yield of dry sago starch that was produced varied between 65% and 73%. PCRD is very feasible to be developed into a commercial scale sago starch dryer with a Pay back value of 2.66 years to return the initial capital of Rp. 186,879,200. Keywords: drying, financial analysis, PCRD, sago starch

Analysis of Water Content on Biodiesel Crude Palm Oil (CPO) and Biodiesel Virgin Coconut Oil (VCO) as Diesel Engine Fuels

This paper is based of policy to diversify energy from renewable energy, one of the types of renewable energy is biodiesel. The purpose of this paper is to explain the water content in biodiesel with palm oil added, and the water content in biodiesel with coconut oil added, and compare the water content of the two types of biodiesel. The type of research used is the research and development method, testing the water content of the biodiesel at the Sucofindo Padang Laboratory and the Pertamina Padang Laboratory. The results showed that the water content of biodiesel with palm oil had a lower water content compared to biodiesel with coconut oil. Referring to the provisions of the Indonesian National Standard (SNI 7182:2015) that the water content in biodiesel is 0.05% as the maximum limit, while referring to Gaikindo (Association of Indonesian Automotive Industries), the maximum water content in biodiesel is 0.020% to 0.025%, then biodiesel B5, B10, B15, and B20, with palm oil added, and biodiesel B5 and B10 with coconut oil added as fuel can be used for diesel engines.

Hydrological Analysis of Extreme Rain Events in a Medium-Sized Basin

The hydrological response of a medium-sized watershed with both rural and urban characteristics was investigated through event-based modeling. Different meteorological event conditions were examined, such as events of high precipitation intensity, double hydrological peak, and mainly normal to wet antecedent moisture conditions. Analysis of the hydrometric features of the precipitation events was conducted by comparing the different rainfall time intervals, the total volume of water, and the precedent soil moisture. Parameter model calibration and validation were performed for rainfall events under similar conditions, examined in pairs, in order to verify two hydrological models, the lumped HEC-HMS (Hydrologic Engineering Center’s Hydrologic Modeling System model) and the semi-distributed HBV-light (a recent version of Hydrologiska Byråns Vattenbalansavdelning model), at the exit of six individual gauged sub-basins. Model verification was achieved by using the Nash–Sutcliffe efficiency and volume error index. Different time of concentration (Tc) formulas are better applied to the sub-watersheds with respect to the dominant land uses, classifying the Tc among the most sensitive parameters that influence the time of appearance and the magnitude of the peak modeled flow through the HEC-HMS model. The maximum water content of the soil box (FC) affects most the peak flow via the HBV-light model, whereas the MAXBAS parameter has the greatest effect on the displayed time of peak discharge. The modeling results show that the HBV-light performed better in the events that had less precipitation volume compared to their pairs. The event with the higher total precipitated water produced better results with the HEC-HMS model, whereas the rest of the two high precipitation events performed satisfactorily with both models. April to July is a flood hazard period that will be worsened with the effect of climate change. The suggested calibrated parameters for severe precipitation events can be used for the prediction of future events with similar features. The above results can be used in the water resources management of the basin.

Bioactive Functional Nanolayers of Chitosan-Lysine Surfactant with Single- and Mixed-Protein-Repellent and Antibiofilm Properties for Medical Implants.

Medical implant-associated infections resulting from biofilm formation triggered by unspecific protein adsorption are the prevailing cause of implant failure. However, implant surfaces rendered with multifunctional bioactive nanocoatings offer a promising alternative to prevent the initial attachment of bacteria and effectively interrupt biofilm formation. The need to research and develop novel and stable bioactive nanocoatings for medical implants and a comprehensive understanding of their properties in contact with the complex biological environment are crucial. In this study, we developed an aqueous stable and crosslinker-free polyelectrolyte–surfactant complex (PESC) composed of a renewable cationic polysaccharide, chitosan, a lysine-based anionic surfactant (77KS), and an amphoteric antibiotic, amoxicillin, which is widely used to treat a number of infections caused by bacteria. We successfully introduced the PESC as bioactive functional nanolayers on the “model” and “real” polydimethylsiloxane (PDMS) surfaces under dynamic and ambient conditions. Besides their high stability and improved wettability, these uniformly deposited nanolayers (thickness: 44–61 nm) with mixed charges exhibited strong repulsion toward three model blood proteins (serum albumin, fibrinogen, and γ-globulin) and their competitive interactions in the mixture in real-time, as demonstrated using a quartz crystal microbalance with dissipation (QCM-D). The functional nanolayers with a maximum negative zeta potential (ζ: −19 to −30 mV at pH 7.4), water content (1628–1810 ng cm–2), and hydration (low viscosity and elastic shear modulus) correlated with the mass, conformation, and interaction nature of proteins. In vitro antimicrobial activity testing under dynamic conditions showed that the charged nanolayers actively inhibited the growth of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria compared to unmodified PDMS. Given the ease of fabrication of multifunctional and charged biobased coatings with simultaneous protein-repellent and antimicrobial activities, the limitations of individual approaches could be overcome leading to a better and advanced design of various medical devices (e.g., catheters, prosthetics, and stents).

Influence of silt content on shear strength of sandy soil

Direct shear tests were carried out on silt standard sand specimens with four silt contents of 0%, 5%, 10%, 20% under three conditions of average maximum dry density, optimal moisture content and saturation, respectively. The effects of different contents and different states on internal friction angle and cohesion of sand specimens were studied. It is found that the internal friction angle and cohesion increase with the increase of silt content under the condition of average maximum dry density and optimal water content, and with the increase of silt content, the internal friction angle decreases and the cohesion increases in saturated state.

Development of a method for the detection of Cu2+ in the environment and live cells using a synthesized spider web-like fluorescent probe

A macrocyclic Schiff base fluorescent probe [1,2-phenylenediamine-2,6-pyridinedialdehyde macrocyclic Schiff base] (BP-MSB) based on 2,6-pyridinedialdehyde was synthesized for use in the detection of Cu2+ in environmental water samples and live cells imaging by the method of specific recognition. The free fluorescent probe BP-MSB shows strong fluorescence in DMSO/H2O. The probe shows high sensitivity and selectivity for Cu2+ through “turn-off” fluorescence response in DMSO/H2O buffer solution (pH = 6.5), with a detection limit of 0.83 nM, which is far below the maximum allowable drinking water content of 20.0 μM specified by the US Environmental Protection Agency. The BP-MSB fluorescence quenching method was used for the determination of Cu2+ in Xiang Jiang water samples and tap-water. Furthermore, addition of the same number of moles of ethylene diamine tetraacetic acid (EDTA) can realize the reversible recognition of Cu2+ by the probe BP-MSB. Most importantly, the fluorescence imaging of live cells after incubation of BP-MSB with GM12878 cells showed good imaging performance, confirming the sensitivity of the fluorescent probe BP-MSB in vivo. The probe was also used to form an analog logic gate. This probe has the advantages of good stability, simple operation and high selectivity, which provides a broad prospect for environmental monitoring, intracellular detection and practical application of POCT.