Weak Alkaline Research Articles

Design of High-Relaxivity Polyelectrolyte Nanocapsules Based on Citrate Complexes of Gadolinium(III) of Unusual Composition.

Through nuclear magnetic relaxation and pH-metry, the details of the complexation of gadolinium(III) ions with citric acid (H4L) in water and aqueous solutions of cationic polyelectrolytes are established. It is shown that the presence of poly(ethylene imine) (PEI) in solution affects magnetic relaxation behavior of gadolinium(III) complexes with citric acid (Cit) to a greater extent than polydiallyldimethylammonium chloride (PDDC). A large increase in relaxivity (up to 50 mM−1s−1) in the broad pH range (4–8) is revealed for the gadolinium(III)–citric acid–PEI system, which is particularly strong in the case of PEI with the molecular weight of 25 and 60 kDa. In weakly acidic medium (pH 3–7), the presence of PEI results in the formation of two tris-ligand associates [Gd(H2L)3]3− and [Gd(H2L)2(HL)]4−, which do not exist in aqueous medium. In weakly alkaline medium (pH 7–10), formation of ternary complexes Gd(III)–Cit–PEI with the Gd(III)–to–Cit ratio of 1:2 is evidenced. Using transmission electron microscopy (TEM) and dynamic light scattering techniques (DLS), the formation of the particles with the size of 50–100 nm possessing narrow molecular-mass distribution (PDI 0.08) is determined in the solution containing associate of PEI with tris-ligand complex [Gd(H2L)2(HL)]4−.

Degradation of unsymmetrical dimethylhydrazine in water by hybrid mesoporous TiO2 and H2O2 under vacuum ultraviolet (VUV) irradiation

In this study, mesoporous TiO2 with various hydrolysis rates were prepared and combined with H2O2 for the photodegradation of unsymmetrical dimethylhydrazine (UDMH) under VUV irradiation. Results showed that the mesoporous TiO2 synthesized by the hydrolysis in water (MT100) exhibited a good mesoporous structure and the largest specific surface area (178.85 m2 g−1). Consequently, MT100 showed the best degradation efficiency, with the rate constant (k) for VUV/MT100 and VUV/MT100/H2O2 of 0.0185 and 0.2595 min−1, respectively, which was 1.4 and 4.0 times of that of P25. The addition of H2O2 significantly enhanced the degradation efficiency by photoactivation of H2O2 and the synergistic effect. The rate constant and the mineralization rate (after a 3-h treatment) increased by 13 and 3.8 times when 40 mM H2O2 was added into VUV/MT100. The weak alkaline condition (pH = 9) would facilitate the degradation of UDMH. The ⋅OH was the key oxidizing species in VUV/MT100/H2O2. Eight intermediates were detected during the degradation and the possible pathways of UDMH degradation in VUV/MT100/H2O2 process were proposed. VUV/MT100/H2O2 provides an efficient method to degrade UDMH.

Selective Separation and Analysis of Catecholamines in Urine Based on Magnetic Solid Phase Extraction by Mercaptophenylboronic Acid Functionalized Fe3O4-NH2@Au Magnetic Nanoparticles Coupled with HPLC

A novel magnetic solid phase extraction based on mercaptophenylboronic acid (MPBA)-functionalized Fe3O4-NH2@Au nanomaterial (Fe3O4-NH2@Au-MPBA) was developed for selective separation and enrichment of catecholamines (including dopamine, norepinephrine and adrenaline). Fe3O4-NH2@Au-MPBA nanoparticles were achieved by self-assembly-anchoring MPBA molecules on the surface of Fe3O4-NH2@Au nanocomposites, which were synthesized via a facial ultrasonic auxiliary in situ reduction process. The interaction between cis-diol from catecholamines and boronic acid was reversible and could be flexibly controlled by adjusting pH value. The catecholamines could be quickly adsorbed by Fe3O4-NH2@Au-MPBA in weak alkaline solution (pH 8.0–9.0) and subsequently released in acid solution (pH 1.0–2.0). The process of adsorption and dissociation was very fast. Furthermore, the three catecholamines could be detected in urine from children by high performance liquid chromatography (HPLC) with electrochemical detector. Under optimal conditions, norepinephrine (NE), epinephrine (EP) and dopamine (DA) were separated very well from internal standard and exhibited a good linearity in the range of 2.5–500.0 ng mL−1, with correlation coefficients of r2 > 0.9907. Limits of detection (LOD) (signal to noise = 3) were 0.39, 0.27 and 0.60 ng mL−1 for NE, EP and DA, respectively. Recoveries for the spiked catecholamines were in the range of 85.4–105.2% with the relative standard deviation (RSD) < 11.5%.

Effects of pH on phosphorus form transformation in lake sediments

Abstract The pH value of lake water varies with the lake environment, which has an effect on the form of phosphorus in sediment, and then the release of sediment phosphorus. The form of phosphorus in sediments was analyzed using field sampling. The environmental conditions with pH values of 4.0, 7.0 and 10.0 were simulated indoors to estimate the effects of pH on phosphorus release from sediments and the content change of various forms of phosphorus was studied. The results showed that in Wuliangsuhai Lake, Ca-P accounted for 54.3%, which was the largest portion of the TP. Phosphorus release was favored under acidic and alkaline conditions, and the alkaline condition was more favorable. The proportion of Fe/Mn-P and Fe/Al-P in the TP decreased with an increase in the pH, while the proportion of Ca-P in the TP increased with an increase in the pH. Under the alkaline condition (pH = 10), Ca-P in the sediment increased significantly, with an increase of 22.5%. However, Fe/Mn-P and Fe/Al-P decreased significantly, with drops of 37.3% and 44.9%, respectively. Under the acidic condition (pH = 4), Fe/Mn-P and Fe/Al-P in the sediment increased significantly, and the increases were 63.1% and 37.1%, respectively. However, Ca-P decreased significantly, with a drop of 39.2%. In general, low pH promoted the release of Ca-P, and a high pH promoted the release of Fe/Mn-P and Fe/Al-P. Wuliangsuhai Lake water is characterized by weak alkaline characteristics throughout the year, and biological available phosphorus accounts for 13.3%–20.9% of the TP, with Fe/Mn-P being the dominant form. This study revealed that the risk of phosphorus release from sediments to the overlying water was greater under alkaline conditions.

Dopamine-assisted co-deposition of hydroxyapatite-functionalised nanoparticles of polydopamine on implant surfaces to promote osteogenesis in environments with high ROS levels

Environments with high reactive oxygen species (ROS) levels, which are common in patients with diseases such as diabetes, periodontitis, and osteoporosis, impair the osseointegration of implants. To address this issue, by using a one-pot dopamine-assisted co-deposition method, we constructed a three-dimensional coating of hydroxyapatite-functionalised nanoparticles of polydopamine (HA/nPDAs) on implant surfaces, where polydopamine is designed to protect cells via scavenging excessive ROS and HA facilitates osteogenesis. First, nanoparticles of polydopamine (nPDAs) were prepared by self-polymerization and assembly of dopamine under alkaline conditions, and HA/nPDAs were obtained by incubating nPDAs in simulated body fluid (SBF) due to metal chelation and ionic interactions triggered by the catechol moieties of PDA. Thereafter, HA/nPDAs with thickness of ~4 μm were constructed on titanium surfaces by immersing titanium discs in a weak alkaline solution of HA/nPDAs and dopamine through interface interactions driven by catechol chemistry. The properties of coatings (e.g., thickness, composition, hydrophilia and morphology) can be controlled by preparation conditions such as mineralization time and reactant concentration. The coatings display efficient ROS-scavenging ability, promote cell proliferation, and upregulate the activity of alkaline phosphatase and the expression of osteogenesis-related genes in environments with high or normal ROS levels, demonstrating the great promise of such coatings for osseointegration promotion, especially in the state of high ROS in diseases. This study provides a facile, efficient, mild, and universal strategy in engineering functional surfaces on any substrates for diversified applications by simple variation of co-deposited components, through taking advantages of versatile catechol chemistry and nanoparticles with stereo structure and great specific surface area.

Synergistic effect of EVA copolymer and sodium desulfurization ash on the printing performance of high volume blast furnace slag mixtures

Considering the long-term development of digital construction, a cost-effective and environmental printing material was designed with blast furnace slag as main cementitious material and sodium desulfurization ash as activator. However, weak alkaline environment lead to the insufficient 3D printability (e.g. yield stress, viscosity). Ethylene/vinyl acetate copolymer (EVA) was used to make up this defect, and it was found that there was a synergistic effect between EVA and sodium desulfurization ash (NS), which is beneficial to the improvement of the printing performance. The synergistic effect of EVA and NS was investigated in terms of fresh, hardened and microstructure properties. Experimental results show that under varying resting times and shear rates, the addition of 0.6−1.6% (i.e.by mass of binder) EVA could increase the yield stress and apparent viscosity of HVGS. Moreover, it was also found that the addition of EVA could help improve the polymerization degree of printing materials and increase the compressive strength of 28d by about 22%. To verify the practical value of the printing material, an industrial product was printed, and the maximum number of continuous printing layers can be up to 30 layers.

Hierarchically Ordered Macro-Microporous Polyoxometalate-Based Metal-Organic Framework Single Crystals.

Facile construction of ordered macroporous polyoxometalate-based metal-organic frameworks (POM@MOFs) to break the intrinsic microporous restriction is significant but remains challenging. On one hand, the POMs introduced improve the structural stability and modify the pores of MOFs, e.g., introducing functional catalytic and adsorptive units. Meanwhile, the acidic POMs severely affect the nucleation and growth of the POM@MOFs, resulting in complicated synthesis and difficult assembly control. Herein, a general approach has been developed to fabricate ordered macroporous POM@MOF single crystals, involving close-packed polystyrene (PS) nanosphere templates. The artificially selected polar solvents exerting strong solvent effect with POMs weaken the affinity between POMs and metal ions, thereby effectively stabilizing the precursors from assembly before filling into the PS template interstices. The weak alkaline carboxylate used regulates the in situ nucleation and growth of POM@MOFs through deprotonation of the ligands as well as coordinating modulation, affording a series of hierarchically cuboctahedral POM@MOF single crystals with ordered macropores (ca. 180 nm) and intrinsic micropores after template removal. The ordered macroporous structure and thinned microporous skeleton markedly improve mass diffusion properties, while the integral single-crystal lattice retains superior stability.

Evaluating of the performance of natural mineral vermiculite modified PVDF membrane for oil/water separation by membrane fouling model and XDLVO theory

A novel vermiculite nanoparticles (Verm NPs) modified poly(vinylidene fluoride) (PVDF) ultrafiltration membrane was firstly fabricated via surface coating at pH 7.2–7.3. The dense but porous modified surface formed by controlling the self-polymerization rate of dopamine at relatively weak alkalinity provided both high water flux and rejection rate of BSA, which broke the trade-off between permeability and rejection rate. The contact angle of optimal modified membrane decreased from 69.6° to 45.0°, showing the effectively enhancement of hydrophilicity. By filtrating two kinds of real oil-in-water emulsions, the stable flux of modified membrane was approximately 2 times higher than that of pristine membrane for both low and high concentration oil-in-water emulsions. In addition, the Verm-PVDF membrane also showed a higher removal efficiency of oil and total organic carbon. According to membrane fouling model analysis, the fouling behavior including adsorption, deposition, blockage of membrane pores and formation of cake layer had obviously alleviated after Verm modification for the two kinds of oil-in-water emulsions due to the formation of water layer by isomorphism substitution and surface hydroxylation of Verm NPs. Assessed by extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, Verm-PVDF membrane exhibited a higher energy barrier and an extremely strong repulsive force for foulants to overcome in low and high concentration emulsions during fouling. Overall, the improved antifouling ability and separation performance of modified membrane indicated that the inartificial Verm NPs was a robust material for pH-control membrane modification with potential application value in oil/water separation.

Alteration, uranium occurrence state, and enrichment mechanism of the Cretaceous Luohe Formation, southwestern Ordos Basin, western China

To ascertain the characteristics of mineral assemblages associated with uranium mineralization and enrichment mechanism of deep sandstone-type uranium deposits, drill-core logging, petrography and mineralogy, scanning electron microscopy (SEM), electronic probe micro analysis (EPMA), whole-rock analysis, X-ray diffraction (XRD) were used to identify the types, redox state of uranium minerals, and typical uranium-related mineral assemblages in the sandstone of the Cretaceous Luohe Formation, southwestern Ordos Basin. The results showed that the clastic grains in the gray and red uranium-bearing sandstone have undergone relatively strong alteration, while alteration of the clastic grains in the gray and red calcareous sandstone is relatively weak. The alteration minerals mainly include pyrite, anatase, kaolinite, chlorite, calcite, apatite, and feldspar. Uranium contents is highly consistent with S, P2O5, CaO, and FeO concentrations in the vertical direction and has a weak correlation with the total organic carbon. Uranium ores are mainly pitchblende and titanium-bearing uranium minerals. The Luohe Formation experienced transformation from a weak alkaline oxidation environment during the diagenetic stage to a weak acid reduction conditions in the early mineralization stage and then to a weak alkaline reduction environment in the middle–late mineralization stages. Typical alteration minerals associated with uranium ores include two types, which are formed in acid reduction and alkaline reduction redox stages, respectively. The alteration minerals related to acidic fluid process are pyrite, anatase, kaolinite, and apatite; those related to alkaline fluid mechanism consist of calcite and chlorite. Deep-seated uranium mineralization was formed by both acidic and alkaline reducing fluids, being dominated by acidic fluid conditions. In-depth investigation of the alteration and uranium ore minerals are of great scientific value to infer the fluid type of mineralization stage and reveal the enrichment mechanism of uranium deposits.

Magnetic Properties of Electrodeposited Cobalt-Platinum (CoPt) and Cobalt-Platinum-Phosphide (CoPtP) Thin Films.

CoPt and CoPtP thin films were synthesized using direct current (DC) aqueous electrodeposition from weak alkaline solutions. The basic plating solutions of binary CoPt thin films consisted of cobalt pyrophosphate [Co2P2O7] and chloroplatinic acid [H2PtCl6]. Various amounts of sodium hypophosphite [NaH2PO2] was added to deposit ternary CoPtP thin films. The film composition was adjusted by varying the several electrodeposition parameters including electrolyte composition, solution pH, and current density and correlated to their microstructure and magnetic property (i.e. coercivity and squareness). For the binary CoPt thin films, the maximum coercivities [in-plane coercivity (Hc,//) = ∼1,600 Oe, and perpendicular coercivity (Hc,⊥) = ∼2,500 Oe] were obtained from electrolytes containing 0.01 M H2PtCl6 + 0.04 M Co2P2O7 at current density (CD) of 7.5 mA cm−2. In the case of ternary CoPtP electrodeposits, the maximum coercivities (Hc,// = ∼2,600 Oe, and Hc,⊥ = ∼3,800 Oe) were achieved from baths containing 0.015 M H2PtCl6, 0.07 M Co2P2O7, 0.8 M NaH2PO2 at CD of 7.5 mA cm− 2 and solution pH 9. It was suggested that microstructure and magnetic properties are affected not only by the type of substrate but also by chemical compositions and electrodeposition conditions.

Fabrication of NiO/Mg–Al layered double hydroxide with superior performance for peroxydisulfate activation

Mg–Al Layered double hydroxides (LDH) with weak alkalinity can improve the activity and stability of transitional metal oxides for peroxydisulfate (PDS) activation. Herein, NiO supported on LDH (Ni-LDH-TP) and Ni doped LDH samples (Ni-LDH-CP and Ni-LDH-SP) were prepared by two-step precipitation and co-precipitation methods, respectively. Their structure and surface properties were characterized and their performance for PDS activation was compared using ciprofloxacin as the target pollutant. The results indicate that Ni-LDH-TP exhibited much higher activity than Ni-LDH-CP and Ni-LDH-SP due to its more surface exposed NiO. The two-step precipitation method should be a better alternative for the synthesis of Ni-LDH catalyst for PDS activation. Ni-LDH-TP exhibited high activity over a wide pH range and good reusability in the presence of bicarbonate, demonstrating its potential application in real water treatment. Activated PDS and SO4•− should be the dominant reactive species for ciprofloxacin degradation. This finding provides an effective strategy for preparing Ni-based PDS catalyst.

HYDROGEOCHEMICAL CHARACTERISTICS AND SOURCE IDENTIFICATION OF DEEP GEOTHERMAL WATER IN QINGDONG COAL MINE, HUAIBEI, ANHUI PROVINCE

The abnormal geo-temperature in coal mine is a warning factor of geological disaster. Study on the hydrogeochemistry and source of geothermal water is an effective method of prevention on mine water and heat disaster. In this study,we collected 13 samples of geothermal water and 11 samples of common groundwater from draining hole at the same depth (-585￣￣m). Based on the hydrochemistry characteristics,the hydrochemical process and sources of geothermal water were analyzed. Compared with the common groundwater,geothermal water had higher content of TDS,Ca2+,Cl-. The hydrochemical facies of geothermal water were SO4 ·Cl-Ca ·Mg type in weak alkaline environment. The chemical composition of geothermal water was dominated by both ion-exchange interaction and dissolution of silicate and evaporates. The oxidation of pyrite in coal,the geothermal water possessed fine hydrodynamic condition and the more intense ion-exchange interactions are more active than those in common groundwater. The formation of geothermal water was supplied by deep Ordovician limestone water and mixed with Taiyuan limestone water through the fracture. The mixing proportion of Ordovician limestone water was higher. The outcomes of this paper can provide guidance for mine water prevention and control.

Study on Corrosion Characteristics of Grounding Materials in High Corrosion Area

Due to the differences in the causes of corrosion, the soil corrosion characteristics in coastal mountains and coastal areas may be quite different. As a result, there are differences in the corrosion causes, corrosion status and service life of the grounding grids of the transmission line towers built in coastal areas. Based on the difference in apparent resistivity of the soil under the transmission line towers in a coastal area with high corrosion, this paper selects 12 soil samples for physical and chemical analysis. The analysis results show that there are two typical soils of acid and weak alkaline in the transmission line erection area, which are highly corrosive but with different corrosion mechanisms. Then the soil liquids of two typical soils were extracted, and the polarization curve test of carbon steel and galvanized steel, which are commonly used in the grounding grid of poles and towers, was carried out for 7 consecutive days, and the corrosion laws of carbon steel and galvanized steel were obtained. The results show that the corrosiveness of acidic soil is much greater than that of weakly alkaline soil. The corrosion rates of carbon steel and galvanized steel in acidic soil are 3.7 times and 5.2 times that of weakly alkaline soil, respectively. In addition, using the extracted soil liquid, a 30-day accelerated corrosion experiment was performed on carbon steel and galvanized steel, and an empirical formula for the change of corrosion weight with time was obtained. Combined with the surface morphology characteristics and corrosion rate after corrosion, this paper analyzed corrosion mechanism of two grounding materials. The research results of this paper provide a reference for the selection and application of grounding materials.

Iron-carbon material enhanced electrokinetic remediation of PCBs-contaminated soil

The high toxicity and persistence of polychlorinated biphenyls (PCBs) in the environment demands the development of effective remediation for PCBs-contaminated soils. In this study, electrokinetic (EK) remediation integrated with iron-carbon material (Fe/C) was established and used to remediate PCB28 (1 mg kg−1) contaminated soil under a voltage gradient of 1 V cm−1. Effects of Fe/C dosage, soil type, and remediation time were investigated. The operational condition was optimized as 4 g kg−1 Fe/C, yellow soil, and 14 d-remediation, achieving PCB28 removal efficiency of 58.6 ± 8.8% and energy utilization efficiency of 146.5. Introduction of EK-Fe/C did not significantly affect soil properties except for slight soil moisture content increase and total Fe content loss. Soil electrical conductivity exhibited an increasing trend from anode to cathode attributed to EK-induced electromigration and electroosmosis. EK accelerated the corrosion and consumption of reactive Fe0/Fe3C in Fe/C by generating acid condition. Fe/C in turn effectively prevented EK-induced soil acidification and maintained soil neutral to weak alkaline condition. A synergistic effect between EK and Fe/C was revealed by the order of PCB28 removal efficiency-EK-Fe/C (58.6 ± 8.8%) > EK (37.7 ± 1.6%) > Fe/C (6.8 ± 5.0%). This could be primarily attributed to EK and Fe/C enhanced Fenton reaction, where EK promoted Fe/C dissolution and H2O2 generation. In addition to oxidation by Fenton reaction generated ·OH, EK-mediated electrochemical oxidation, Fe/C-induced reduction and migration of Fe/C adsorbed PCBs were all significant contributors to PCB28 removal in the EK-Fe/C system. These findings suggest that the combination of EK and Fe/C is a promising technology for remediation of organics-contaminated soil.

Bamboo-Based Biofoam Adsorbents for the Adsorption of Cationic Pollutants in Wastewater: Methylene Blue and Cu(II).

Human health is being threatened by cationic pollutants in wastewater, for example, methylene blue (MB) and Cu(II). Our research team successfully fabricated biofoam adsorbents from recycled bamboo waste that removed cationic pollutants via introducing bamboo fiber sources, i.e., bamboo fiber, bamboo α-cellulose fiber, and bamboo nanocellulose fiber, into a polyurethane (PU) foam matrix. The biofoam adsorbent with 1 g of nanocellulose (PUN1) presented high removal efficiencies for MB (95.52%) and Cu(II) (100%) in low cationic pollutant concentration aqueous solutions. The biofoam adsorbent with 1 g of bamboo fiber (PUB1) also displayed excellent removal efficiency for MB (98.61%) at pH 11. Meanwhile, 100% removal of Cu(II) was obtained by PUB1 at pH 7 (initial content = 15 mg/L). Furthermore, the PUN1 sample had excellent reusability, evidenced by 61.25% removal of MB after five adsorption–desorption cycles, suggesting that PUN1 is a promising renewable adsorbent for cationic pollutants. In addition, PUB1 is a low-cost adsorbent with good adsorption efficiencies for MB in weak alkaline solutions and Cu(II) in neutral aqueous solutions.

Effects of pH on the dynamic migration of nutrient salts in the sediment of ditches in mountain rural areas

Objective As pH is a key factor affecting the migration and release of nutrients in the ditch sediment, this study, with an investigation of the dynamic changes of nutrient release and migration in the bottom mud of mountainous rural ditches under different pH conditions, is aimed to provide a theoretical basis for rural ecological environment management. Method With the bottom mud of typical mountainous rural ditches in the Dianchi Lake Basin collected, indoor simulation experiments were conducted to determine the nutrient salt content of the bottom mud and the overlying water under different pH (pH 5.5, 7.5, 9.5, 11.5) conditions under non-sterilized and sterilized treatments after which the nutrient release flux at the sediment-water interface was estimated. Result The mass fraction of total nitrogen (TN) in the bottom sludge decreased with the increase of pH. The total nitrogen release flux under the strong alkaline (pH 11.5) and acidic (pH 5.5) conditions of the non-sterilized group was 8 and 4 times of the control (pH 7.5), and its release flux in the sterilization group was 2 times of that in the control. The mass concentration and release flux of soluble total phosphorus (DTP) in the overlying water increased with the increase of pH. The release of DTP under the conditions of strong alkaline (pH 11.5) and weak alkaline (pH 9.5) in the non-sterilized group was 12 and 4 times of that in the control, respectively, and its release flux in the sterilized group was 30 and 15 times of that in the control while the non-sterilized group had higher DTP release flux than the sterilized group. RDA shows that acidic conditions promote the release of calcium-bound phosphorus (Ca-P) in sediments, and alkaline (pH≥9.5) conditions promote the release of total nitrogen, total phosphorus and iron-aluminum-bound phosphorus (Fe/Al-P). Neutral (pH 7.5) conditions have little effect on the release of nitrogen or phosphorus in the sediments. Conclusion Alkalinity (pH≥9.5) and acidity significantly promote the release of nitrogen and phosphorus nutrients in the bottom mud of mountain rural ditches, and the release amount is the smallest under neutral conditions. Also, the sterilization of the bottom sludge reduces the microbial activity at different pH levels, and prevents the migration and release of nitrogen and phosphorus in the bottom sludge of mountain and rural ditches to the overlying water. [Ch, 6 fig. 1 tab. 36 ref.]

Dynamic light scattering immunosensor based on metal-organic framework mediated gold growth strategy for the ultra-sensitive detection of alpha-fetoprotein

The ultrasensitive detection of disease-related biomarkers is critical to improving the early diagnosis, monitoring, and treatment of diseases. Herein, we reported a dynamic light scattering (DLS)-based immunosensor for the high-sensitivity detection of alpha-fetoprotein (AFP), an important biomarker in the early diagnosis of primary liver cancer. A metal–organic framework and gold nanoparticle composite ([email protected]) was designed as a low-background scattering signal probe. After its structure was decomposed in a weak alkaline solution, the numerous small-sized AuNPs (∼4 nm) were released from the MOF structure. Controllable gold in situ growth strategy without self-nucleation was then executed to increase the AuNP size. Owing to the double signal amplification of the burst release of numerous small-sized AuNPs from MOFs and the gold in situ growth for an enhanced AuNP size, the proposed DLS immunosensor was successfully applied for the ultrasensitive detection of AFP with the detection limit of 0.36 pg mL−1. The reliability of the proposed method was evaluated by analyzing 22 actual clinic serum samples, and the results were further verified by the chemiluminescence immunosensor. This work features [email protected] and the gold in situ growth amplified modulation of DLS-based signal transduction, which demonstrates the great potential as a novel bioanalytical platform for a myriad of purposes.

Exploring a molecular switch for dopamine oxidation induced by charge reversal using scanning electrochemical microscopy

Oxidation of dopamine inside synaptic vesicles has been considered as one of inducements for Parkinson's disease. Dopamine molecules are often oxidized to quinones, making damages to neurotransmission process. Thus, exploring a controllable molecular switch for dopamine oxidation would make great significance in physiology. In this work, a binary homocysteine-dodecanethiol self-assembled monolayers was constructed on gold surface as a specific molecular switch. Scanning electrochemical microscopy was adopted to investigate the switch behavior for dopamine oxidation. The results showed that the molecular switch was at the ON state in a weak alkaline solution and dopamine oxidation would occur. While, the molecular switch was at the OFF state in a weak acidic solution and dopamine oxidation would be cut off. This controllable ON-OFF phenomenon was attributed to charge reversal on the surface of self-assembled monolayer. Then, Density Functional Theory calculation was adopted to calculate the HOMO-LUMO band gap of dopamine-homocysteine cluster. The theoretical calculation exhibited that charge reversal of homocysteine could adjust the energy barrier of dopamine oxidation. This work would offer some contributions to studies of dopamine oxidation in cellular physiology.

Experimental and theoretical investigation on the inhibition performance of disulfide derivatives on cobalt corrosion in alkaline medium

Cobalt, as the barrier layer material for 14 nm copper interconnection, has been widely applied owing to its superior characteristics of low resistivity, excellent adhesion performance and blocking properties for copper. Most of the preciously developed cobalt corrosion inhibitors under weak alkaline condition are toxic, low water solubility, and limited to traditional experimental research. In this work, 3,3-dithiodipropionic acid (DDA), 2,2-dibenzamidodiphenyl disulfide (DPD) as potential corrosion inhibitors for cobalt in NH4Cl and H2O2 media under alkaline environment were investigated. Electrochemical experiments, surface morphology characterization, quantum chemical calculation and molecular dynamic simulation were combined to analyze the corrosion inhibition ability and mechanism. The experimental and theoretical results present that these disulfide derivatives can inhibit the corrosion behavior of cobalt surface effectively in ammonium-based aqueous solutions. When the concentration of inhibitors was 0.5 wt%, the corrosion inhibition efficiency of DDA, DPD reach up to 92.9%, 91.41%, respectively. Their favorable capability is attributed to the dense adsorption films following the Langmuir adsorption isotherm. Besides, these two inhibitors show excellent performance of galvanic corrosion inhibition at the Co/Cu interface, which is consistent with the shift tendency simulations for binding to Co/Cu substrates. The results of water solubility and toxicity tests indicate that DDA is more suitable for industrial applications.

Effect of water content on oxidation activity of residual coal in Goaf

In order to study the effect of water on the oxidation activity of residual coal in goaf, FTIR experiment was used to analyze the effect of water quality on the oxidation functional groups of coal under different soaking time; The experimental results show that based on the change trend of oxidation functional groups of coal in acidic and alkaline environment, the change of acidity and alkalinity of water will lead to the increase of - Oh peak area of coal sample; With the increase of soaking time of weak alkaline mine water, the content of Oh in coal sample is higher; The peak area of main oxidation functional groups of coal first increases and then decreases with the increase of soaking time.