Effect of Different Acidic Agents on Surface Roughness of Feldspathic Porcelain

Objectives: The aim of this study was to evaluate the effect of different acidic agents on surface roughness of feldspathic porcelain. Materials and Methods: In this study, totally 60 disc shaped Noritake and Ceramco 3 feldspathic porcelain were used. The samples were divided into five groups and immersed in five acidic agents (coke, orange juice, lemonade, mineral water and black-carrot juice). After 168 hours, the specimens were evaluated surface roughness with profilometer. Results: The results showed that the highest surface roughness value (4.46 ± 2.9 μm) was identified in lemonade at Noritake porcelain and the lowest surface roughness value (1.06 ± 0.56 μm) was identified in mineral water at Ceramco 3 porcelain. The result of two-way analysis of variance test showed that there were no statistically significant differences between acidic agents on surface roughness of feldspathic porcelain (p > 0.05). Conclusions: The obtained data presented that the acidic drinks affected the surface roughness of feldspathic porcelain.

Modified DTPA， EDTA Ligands and Their Paramagnetic Metal Complexes as Contrast Agents for MRI

Six new aminocarboxylic ligands were synthesized by reactions of EDTA (ethylenediaminetetraacetic acid) dianhydride or DTPA (dlethylenetriaminepenta-acetic acid) dianhydride and ethyl ester of serine,threonine and tyrosine. Their paramagnetic metal complexes were also synthesized.All ligands and paramagnetic metal complexes were characterized by IR spectra,IH NMR and elemental analyses.Relaxivity study showed that the metal complexes had higher relaxation effectiveness as compared to corresponding unmodified metal complexes. Imaging study of gadolinium complex of tyrosine ethyl ester modified DTPA in mice demonstrated that this metal complex could apparently increase the signal intensity of MR images.

Solvent extraction and separation of light rare earth elements (La, Pr and Nd) in the presence of lactic acid as a complexing agent by Cyanex 272 in kerosene and the effect of citric acid,acetic acid and Titriplex Ⅲ as auxiliary agents

At present, the use of rare earth elements（REEs） has become an inevitable necessity in many modern industries. In general, liquid extraction is the best commercial method for extracting REEs due to its ability to control high volumes of liquids with electrical load. With the aim of improving a separation technology that would be superior to the existing extraction systems, the extraction behaviors of La（Ⅲ）,Pr（Ⅲ）, and Nd（Ⅲ） from an HCI medium with Cyanex 272 in the presence of the complexing agent lactic acid（HLac） and auxiliary agents citric acid（H3 Cit）, acetic acid（HAc）, and Titriplex Ⅲ have been reported.The effect of pH and lactic acid concentration has been examined. The use of lactic acid as a complexing agent leading to a high extraction of REEs with Cyanex 272 at pH = 5 was compared with systems without lactic acid. The results show that the use of acetic acid along with lactic acid leads to an increase in the extraction percentage of LREEs. While use of citric acid and Titriplex Ⅲ reduces the extraction percentage of LREEs. Finally, the presence of Titriplex Ⅲ together with lactic acid could lead to an increase in the separation factor of Pr and Nd.

Chlorine poisoning caused by improper mixing of household disinfectants during the COVID-19 pandemic:Case series

BACKGROUND Misuse of disinfectants during the coronavirus disease 2019 pandemic has led to several poisoning incidents.However,there are few clinical case reports on poisoning caused by improper mixing of household disinfectants.AIM To summarize the clinical characteristics and treatment effects of chlorine poisoning caused by improper mixing of hypochlorite bleach with acidic cleaning agents.METHODS We retrospectively analyzed baseline and clinical data,clinical symptoms,and treatment methods of seven patients with chlorine poisoning who were admitted to the National Army Poisoning Treatment Center.RESULTS Among the seven patients,the average poisoning time(exposure to admission)was 57 h(4-240 h).All patients were involved in cleaning bathrooms.Chest computed tomography scans revealed bilateral lung effusions or inflammatory changes in five patients.The partial pressure of oxygen decreased in six patients,and respiratory failure occurred in one.Five patients had different degrees of increase in white blood cell count.Humidified oxygen therapy,non-invasive mechanical ventilation,anti-inflammatory corticosteroids,antioxidants,and antibiotics were administered for treatment.The average length of hospital stay was 7 d(4-9 d).All seven patients recovered and were discharged.CONCLUSION Improper mixing of household disinfectants may cause damage to the respiratory system due to chlorine poisoning.Corticosteroids may improve lung exudation in severe cases,and symptomatic supportive treatment should be performed early.

Environmentally relevant concentrations of aminopolycarboxylate chelating agents mobilize Cd from humic acid

Although Cd is a pollutant of public health relevance,many dietary sources from which it can be absorbed into human tissues remain unknown.While it is well established that the biogeochemical cycle of Cd involves its complexation with environment-derived ligands（e.g.,humic acids,HAs） and anthropogenic ones（e.g.,chelating agents,CAs）,the interaction of Cd with both of these ligands is less well understood.To gain insight,a HA–Cd complex was injected on a size-exclusion chromatography（SEC） column coupled on-line with a flame atomic absorption spectrometer（FAAS） using 10 mmol/L Tris buffer（pH 8.0） as the mobile phase.This approach allowed us to observe the intact HA–Cd complex and the retention behavior of Cd as a function of 2–20 μmol/L concentrations of ethylenediaminetetraacetic acid（EDTA）,diethylenetriaminepentaacetic acid（DTPA） or methylglycinediacetic acid（MGDA） that were added to the mobile phase.An increase of the retention time of Cd was indicative of a partial or complete abstraction of Cd from HA.Our results revealed that all CAs abstracted Cd from the HA–Cd complex at concentrations of 5 μmol/L,while MGDA and DTPA were effective at 2 μmol/L.The bioavailability of some of the on-column formed CA–Cd complexes explains the previously reported increased accumulation of Cd in periphyton in the ecosystem downstream of wastewater treatment plants.In addition,our results imply that the use of effluents which contain CAs and Cd for the irrigation of food crops can introduce Cd into the food supply and compromise food safety.

Modification of methyl oleate for silicon-based biological lubricating base oil

A new kind of silicon-based biological lubricating base oil with good viscosity-temperature behavior,viscosity index,thermostability,oxidation stability and wear resistance performance was synthesized as a derivative of methyl oleate.Trimethylsilylation reaction was introduced to further improve methyl oleate oxidation stability and lubricity after epoxidation and open-ring reactions.The order of effectiveness of acid binding agent was N,N-diisopropylethylamine(DIEA) > pyridine > diethylamine > triethylamine,and the effects of various parameters on the trimethylsilylation reaction as well as on the silicon-oxygen bond stability and reaction yield were studied.A maximum yield of 34.54%was achieved at hydroxyl/trimethyl chlorosilane/DIEA molar ratio of1:1.25:1,reaction temperature 40℃,reaction time 1.5 h.

An easily recoverable thermo-sensitive polyelectrolyte as draw agent for forward osmosis process

As a potential solution to the crises of energy and resources, forward osmosis(FO) has been limited by the development of draw agents. An ideal draw agent should be able to generate high osmotic pressure and can be easily recovered. In this study, a thermo-sensitive polyelectrolyte of poly(N-isopropylacrylamide-co-acrylic acid)(PNA)is developed as an efficient draw agent, and two easy and simple methods are proposed to effectively recover the polyelectrolytes. After adjusting the pH value of polyelectrolyte solutions to around 6.0, the polyelectrolyte can generate relatively high osmotic pressure, and induce average water fluxes of 2.09 and 2.95 L·m^(-2)·h^(-1) during12 h FO processes when the polyelectrolyte concentrations are 0.20 and 0.38 g·ml^(-1) respectively. After acidifying and heating to 70 °C, the PNA-10 polyelectrolyte can aggregate together because of hydrophobic association and separate from water, so it can be easily recovered by either simple centrifugation or gravitational sedimentation. The recovery ratios of PNA-10 polyelectrolyte in both methods are as high as 89%, and the recovered polyelectrolytes can be reused with almost the same FO performance as fresh ones. The results in this study provide valuable guidance for designing efficient and easily recoverable draw agents for FO processes.

Ovalbumin-stabilized gold nanoclusters with ascorbic acid as reducing agent for detection of serum copper

Ovalbumin-stabilized gold nanoclusters （OVA@AuNCs） were prepared with ascorbic acid as a reducing agent. This strategy could realize the synthesis of water-soluble OVA@AuNCs within 20 min. The asprepared fluorescent probe showed a red fluorescence emission at 630 nm. Moreover, the properties of the OVA@AuNCs were characterized by transmission electron microscope, dynamic light scattering, ultraviolet-visible spectroscopy, fluorescent spectroscopy. Based on the surface electron density decrease-induced fluorescence quenching mechanism, the OVA@AuNCs provided high sensitivity and selectivity for sensing copper ions. A good linear relationship was obtained between the fluorescence intensity of OVA@AuNCs and the concentration of copper ions in the range of 5.0-100.0pumol/L （R2z0.999） with a detection limit of 640 nmol/L. Furthermore, the rat serum copper contents were determined by using the OVA@AuNCs based assay, indicating great potential of fluorescent probes for application in biological and clinical analysis.