Influence of Additives on the Macroscopic Color and Corrosion Resistance of 6061 Aluminum Alloy Micro-Arc Oxidation Coatings.

In this study, we successfully employed the plasma electrolytic oxidation (PEO) technique to create a uniform white ceramic layer on the surface of the 6061 aluminum alloy using K2ZrF6 and Na2WO4 as colorants. A scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) and X-ray diffraction (XRD) were used to characterize the coatings, and we used an electrochemical workstation to test their corrosion protection properties. The corrosion resistance of the coatings was analyzed using potentiodynamic polarization curves. The results showed that K2ZrF6 addition whitened the coating with ZrO2 as the main phase composition, inhibiting Al substrate depletion and enhancing coating corrosion resistance. A small amount of Na2WO4 decreased the coating's L* value, successfully constructing ceramic coatings with L* (coating brightness) values ranging from 70 to 86, offering broad application prospects for decorative coatings.

Study of Coating Growth Direction of 6061 Aluminum Alloy in Soft Spark Discharge of Plasma Electrolytic Oxidation.

Conventional plasma electrolytic oxidation treatments produce oxide coatings with micron-scale discharge pores, resulting in insulation and wear and corrosion resistance far below that expected of highly dense Al2O3 coatings. The introduction of cathodic polarization during the plasma electrolytic oxidation process, especially when the applied cathode-to-anode current ratio (Rpn) is greater than 1, triggers a unique plasma discharge phenomenon known as "soft sparking". The soft spark discharge mode significantly improves the densification of the anode ceramic layer and facilitates the formation of the high-temperature α-Al2O3 phase within the coating. Although the soft spark discharge phenomenon has been known for a long time, the growth behavior of the coating under its discharge mode still needs to be studied and improved. In this paper, the growth behavior of the coating before and after soft spark discharge is investigated with the help of the micro-morphology, phase composition and element distribution of a homemade fixture. The results show that the ceramic layer grows mainly along the oxide-electrolyte direction before the soft spark discharge transformation; after the soft spark discharge, the ceramic layer grows along the oxide-substrate direction. It was also unexpectedly found that, under soft spark discharge, the silicon element only exists on the outside of the coating, which is caused by the large size and slow migration of SiO32-, which can only enter the ceramic layer and participate in the reaction through the discharge channel generated by the strong discharge. In addition, it was also found that the relative phase content of α-Al2O3 in the coating increased from 0.487 to 0.634 after 10 min of rotary spark discharge, which is an increase of 30.2% compared with that before the soft spark discharge transition. On the other hand, the relative phase content of α-Al2O3 in the coating decreased from 0.487 to 0.313 after 20 min of transfer spark discharge, which was a 55.6% decrease compared to that before the soft spark discharge transformation.

The Spontaneous Escape Behavior of Silver from Graphite-like Carbon Coatings and Its Effect on Corrosion Resistance.

Silver-doped graphite-like carbon (Ag-GLC) coatings were prepared on the surface of aluminum alloy and single-crystal silicon by magnetron sputtering under different deposition parameters. The effects of silver target current and deposition temperature, as well as of the addition of CH4 gas flow, on the spontaneous escape behavior of silver from the GLC coatings were investigated. Furthermore, the corrosion resistance of the Ag-GLC coatings were evaluated. The results showed that the spontaneous escape phenomenon of silver could take place at the GLC coating, regardless of preparation condition. These three preparation factors all had an influence on the size, number and distribution of the escaped silver particles. However, in contrast with the silver target current and the addition of CH4 gas flow, only the change in deposition temperature had a significant positive effect on the corrosion resistance of the Ag-GLC coatings. The Ag-GLC coating showed the best corrosion resistance when the deposition temperature was 500 °C, which was due to the fact that increasing the deposition temperature effectively reduced the number of silver particles escaping from the Ag-GLC coating.

Plasma Electrolytic Oxidation Coatings of a 6061 Al Alloy in an Electrolyte with the Addition of K2ZrF6.

In this study, white thermal control coatings were produced on a 6061 Al alloy using plasma electrolytic oxidation (PEO). The coatings were mainly formed by incorporating K2ZrF6. The phase composition, microstructure, thickness, and roughness of the coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), a surface roughness tester, and an eddy current thickness meter, respectively. The solar absorbance and infrared emissivity of the PEO coatings were measured using a UV-Vis-NIR spectrophotometer and FTIR spectrometer, respectively. The addition of K2ZrF6 to the trisodium phosphate electrolyte was found to significantly enhance the thickness of the white PEO coating on the Al alloy, with the coating thickness increasing in proportion to the concentration of K2ZrF6. Meanwhile, the surface roughness was observed to stabilize at a certain level as the K2ZrF6 concentration increased. At the same time, the addition of K2ZrF6 altered the growth mechanism of the coating. In the absence of K2ZrF6 in the electrolyte, the PEO coating on the Al alloy surface predominantly developed outwards. However, with the introduction of K2ZrF6, the coating's growth mode transitioned to a combination of outward and inward growth, with the proportion of inward growth progressively increasing in proportion to the concentration of K2ZrF6. The addition of K2ZrF6 substantially enhanced the adhesion of the coating to the substrate and endowed it with exceptional thermal shock resistance, as the inward growth of the coating was facilitated by the presence of K2ZrF6. In addition, the phase composition of the aluminum alloy PEO coating in the electrolyte containing K2ZrF6 was dominated by tetragonal zirconia (t-ZrO2) and monoclinic zirconia (m-ZrO2). With the increase in K2ZrF6 concentration, the L* value of the coating increased from 71.69 to 90.53. Moreover, the coating absorbance α decreased, while the emissivity ε increased. Notably, at a K2ZrF6 concentration of 15 g/L, the coating exhibited the lowest absorbance (0.16) and the highest emissivity (0.72), which are attributed to the enhanced roughness resulting from the substantial increase in coating thickness caused by the addition of K2ZrF6, as well as the presence of ZrO2 with higher emissivity within the coating.

Design of an interface heating device based on polydivinylbenzene/SiO2/Bi2WO6 and its visible light response performance for water purification.

Environmental pollution and the shortage of drinking water are the challenges that mankind is facing. Solar interface evaporation technology has been demonstrated as an important method for producing clean water, but its application to sewage still faces problems, mainly manifested in solubility and oily pollutants. Therefore, an evaporator device contains a superhydrophobic Bi2WO6 felt floating layer, a filter paper hydrophilic layer, and a copper foam/CuO photothermal layer, of which the water contact angle of the superhydrophobic felt can reach 159°. The floating layer not only has the ability to adsorb n-hexane but the Rh B degradation can also be realized under indoor/outdoor light conditions. The carrier life of Bi2WO6 is 28.8 ns. A copper foam/CuO photothermal layer prepared through a low-temperature treatment is combined with the floating and hydrophilic layer to obtain an evaporation rate of 1.53 kg m-2 h-1.

Dual-modified starch micelles as a promising nanocarrier for doxorubicin.

Natural amphiphilic polymer micelles have garnered considerable research attention as nanocarriers for delivering drugs. The objective of this study was to explore the possibility of applying biocompatible dual-modified starch micelles as drug delivery vehicles. To this end, a dual-modified corn starch polymer (SCD) was synthesized with zwitterionic sulfobetaine and deoxycholic acid; spherical micelles with an average particle size of ~200 nm were prepared through the self-assembly of SCD. The effects of dual modification on the degree of substitution, molecular structure, and functional properties of SCD were investigated. Further, doxorubicin was successfully incorporated into the micelles, and an in vitro drug release study was performed to confirm that the drug-loaded micelles displayed pH-sensitive properties with controlled and sustained release. The dissolve-diffuse-erosion-degradation release process was described according to the dynamic models of drug release for SCD micelles. The results can be used as reference information for further studies in the biotechnology and pharmaceutical domains.

An experimental investigation into the borehole drilling and strata characteristics.

Measurement while drilling is an important part of the intelligent development of coal mines. The main purpose of this paper is to comprehensively analyze the response characteristics of borehole drilling parameters and find a better method to predict rock mechanical properties based on drilling parameters. Firstly, six concrete blocks and multiple specimens were prepared with different material ratios. Next, the concrete specimens were tested for mechanical properties in the laboratory. Meanwhile, the displacement, rotation speed, torque, and sound pressure level (SPL) were observed during the drilling of the concrete blocks. Finally, the response characteristics of drilling parameters such as rotation speed, rate of penetration (ROP), torque, and SPL were analyzed. Besides, multiple prediction models of rock mechanical parameters were obtained by data analysis. The research results indicate that the drilling process can be classified into the initial stage of drilling (fast speed) and the steady stage of drilling (slow speed). The torque work ratio accounts for more than 99%, which increases with the increase in rock strength. The penetration depth per revolution and torque work ratio are significantly related to rock uniaxial compressive strength, Brazilian tensile strength, cohesion, and elastic modulus. The ROP is the best choice for estimating rock mechanical parameters. This research provides an important reference for laboratory rock mechanics parameter testing and geological features detection based on drilling parameters.

Molecular modification, structural characterization, and biological activity of xylans.

The differences in the source and structure of xylans make them have various biological activities. However, due to their inherent structural limitations, the various biological activities of xylans are far lower than those of commercial drugs. Currently, several types of molecular modification methods have been developed to address these limitations, and many derivatives with specific biological activity have been obtained. Further research on structural characteristics, structure-activity relationship and mechanism of action is of great significance for the development of xylan derivatives. Therefore, the major molecular modification methods of xylans are introduced in this paper, and the primary structure and conformation characteristics of xylans and their derivatives are summarized. In addition, the biological activity and structure-activity relationship of the modified xylans are also discussed.

Structure and properties of corn starch synthesized by using sulfobetaine and deoxycholic acid.

Novel starch polymers (sulfobetaine-starch-deoxycholic acid) were first synthesized by grafting zwitterionic sulfobetaine and deoxycholic acid onto corn starch molecules. In order to explore the mechanism of modified starch, the chemical structure, morphological properties, thermal stability, and self-assembly performance of modified corn starch were determined. Preliminary structural characterization, using NMR, demonstrated that the glucose carbon C6 was the main etherification grafting site and C2 and C3 were the esterification grafting sites. This was confirmed using FT-IR to detect the presence of a new carbonyl signal around 1739 cm-1. XRD, SEM, and PLM micrographs showed structural losses in the starch granule. Thermogravimetric analysis showed an increase in thermal stability with etherification and esterification in nature. Self-assembly performance analysis demonstrated that the polymer formed more thermodynamically stable micelles under highly diluted conditions. This work will help expand the space for starch application.

Formation and structural evolution of starch nanocrystals from waxy maize starch and waxy potato starch.

The formation and structural evolution of starch nanocrystals from waxy maize starch (WMS) and waxy potato starch (WPS) by acid hydrolysis were studied. The relative crystallinity, the short-range molecular order, and the double-helix content of WMS and WPS increased significantly during the initial stage of acid hydrolysis, indicating that acid preferentially eroded the amorphous regions of starch granules. With time, there was increased destruction of lamellar structures, causing the granules to completely disintegrate to form nanocrystals. WMS and WPS displayed different hydrolysis mechanisms. WPS was more susceptible to acid hydrolysis than WMS, and WMS exhibited an endo-corrosion pattern and WPS showed an exo-corrosion pattern. WMS nanocrystals had a parallelepiped shape, and WPS nanocrystals were round. This difference in shape is likely due to the different packing configuration of double helices in native starches.

An Efficient Approach to Prepare Water-Redispersible Starch Nanocrystals from Waxy Potato Starch.

Starch nanocrystals (SNCs) are a biodegradable polymer which has been widely studied and used in many fields. In this study, we have developed an efficient procedure for the preparation of SNCs. First, sodium hexametaphosphate (SHMP) and vinyl acetate (VAC) were used to modify waxy potato starch (WPS). Then, the modified starches were hydrolyzed with sulfuric acid to prepare SNCs. Results showed that SNCs prepared with modified starch had higher zeta potentials and better dispersion properties than the original starch. After modification, WPS still maintained its semi-crystalline structure, but the surface became rougher. SHMP-modified WPS showed a decrease in viscosity peak and an increase in gelatinization temperature. VAC-modified WPS showed increased swelling power. Additionally, SNCs prepared with VAC-modified WPS had better water redispersibility and dispersion stability than those from SHMP-modified starch-which will have broader application prospects in the field of safe and biodegradable food packaging.

Insights into the multiscale structure and pasting properties of ball-milled waxy maize and waxy rice starches.

The effects of ball-milling on the pasting properties of waxy maize starch (WMS) and waxy rice starch (WRS) were investigated from a multiscale structural view. The results confirmed that ball-milling significantly destroyed the structures of the two waxy starches (especially WMS). Specifically, ball-milling led to obvious grooves on the surface of starch granules, a decrease in crystallinity and the degree of short-range order, and a reduction in double-helix components. Meanwhile, small-angle X-ray scattering results indicated that the semicrystalline lamellae of starch were disrupted after ball-milling. Ball-milling decreased the pasting temperatures. Furthermore, ball-milled starches exhibited lower peak and breakdown viscosity and weakened tendency to retrogradation. These results implied that ball-milling induced structural changes in starch that significantly affected its pasting properties. Hence, ball-milled starch may serve as food ingredients with low pasting temperature and paste viscosity as well as high paste stability under heating/cooling and shearing.

Oxidized konjac glucomannan-cassava starch and sucrose esters as novel excipients for sustained-release matrix tablets.

A novel sustained-release matrix tablet was developed through wet granulation by using oxidized konjac glucomannan-cassava starch (OKGM-CS) and sucrose esters (SE) as excipients. OKGM-CS treated by dry heat exhibited low solubility and swelling power, indicating that it might be a potential adjuvant for sustained-release drug formulations. SE incorporation significantly decreased the porosity and swelling rates of tablets and retarded drug release. Tablets containing SE with an HLB value of 5 displayed better sustained-release performance, the cumulative release decreased from 94.36% to 83.29% and MDT increased from 4.50 h to 5.79 h. All these findings suggest the potential of OKGM-CS and SE as novel sustained-release agents for matrix tablets.

Effectiveness of AOS-iron on iron deficiency anemia in rats.

Iron deficiency anemia (IDA) is one of the most serious nutritional problems. This study aimed to evaluate the therapeutic effects of a novel agar oligosaccharide-iron complex (AOS-iron) on rats with IDA, such as iron supplementation and recovery of antioxidant ability. Eighty-four weaned male SD rats were randomly divided into a normal control group (n = 12), which was fed with a standard diet, and an anemia model group (n = 72), which was fed with an iron-deficient diet for 4 weeks to establish a model of IDA. After the model was established, the rats with IDA were divided into six groups, namely, an anemia model group, a ferrous gluconate group, a ferrous sulfate (FeSO4) group, and low-dose (LD), medium-dose (MD) and high-dose (HD) AOS-iron groups, and fed with an iron-deficient diet and different iron supplements for 4 weeks, respectively. The results showed that HD AOS-iron exerted a significant restorative effect by returning blood parameters to normal levels in rats with IDA, including hemoglobin, red blood cells, hematocrit, mean cell volume, mean cell hematocrit, mean cell hemoglobin concentration, serum iron, total iron binding capacity, transferrin saturation, and serum ferritin. A histological analysis suggested that the liver morphology in the MD and HD AOS-iron groups was similar to that in the normal group. Furthermore, MD and HD AOS-iron improved antioxidant activities in the serum and liver. In general, high-dose (the same dose as those of ferrous gluconate and FeSO4) AOS-iron exhibited the best effects in terms of iron supplementation and antioxidant activities. The present findings showed that AOS-iron might be a potential new iron supplement.

The prevalence of impaired glucose regulation in anxiety disorder patients and the relationship with hypothalamic-pituitary-adrenal axis and hypothalamic-pituitary-thyroid axis activity.

OBJECTIVE: To investigate the prevalence of impaired glucose regulation (IGR) in patients with anxiety disorders and the relationship with hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-thyroid (HPT) axes function. METHODS: From September 2013 to May 2015, a total of 646 patients with anxiety disorders who matched the criteria of the 10th revision of the International Statistical Classification of Diseases and Related Health Problems participated in our study, which was conducted in the Psychiatric Inpatient Department of the West China Hospital of Sichuan University. The results from 75-g glucose tolerance tests, and morning (8:00 am) serum cortisol (PTC), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), TT3, TT4, FT3, and FT4 levels were collected. The Hamilton Anxiety Scale was administered to assess the severity of anxiety. SPSS 17.0 software was used for statistical analysis. RESULTS: The crude prevalence of impaired glucose regulation was 24.61% in patients with anxiety disorders patients. In the 18- to 40-year age group with impaired glucose regulation (IGR), both ACTH and PTC levels were higher than the control group (P < 0.05). In the 61- to 75-year age group with IGR, the TSH level was lower and the FT4 level was higher than the control group (P < 0.05). CONCLUSION: The results herein partially confirm that the prevalence of IGR in patients with anxiety disorders is high. Impaired glucose in the younger age group is closely associated with HPA axis function, while impaired glucose in the older age group is closely associated with HPT axis alteration. Therefore, routine blood glucose and endocrine function testing in patients with anxiety disorder is of clinical importance to prevent the development of diabetes.

An enzyme-linked immunosorbent assay for monoester-type aconitic alkaloids and its application in the pharmacokinetic study of benzoylhypaconine in rats.

A new enzyme-linked immunosorbent assay (ELISA) method for quantitative determination of monoester-type aconitic alkaloids was developed. The antibodies derived from the immunogen of benzoylmesaconine (BM) could be electively affined to benzoylaconitine-type alkaloids with an ester bond (14-benzoyl-), especially to benzoylhypaconine (BH, 140.02% of cross-reactivity). The effective working range of BH was 1 ng/ml to 5 µg/ml; the lower limit of detection and the quantification were 0.35 and 0.97 ng/ml, respectively. The values of CV for intra-day and inter-day assays and recovery ratios were in acceptable ranges. The results of stability experiments were also satisfactory. This validated method was employed for pharmacokinetic study of BH in rats and the bioavailability orally administered was estimated to be 16.3%.

[Role of HPA and HPT Axis in Anxiety Disorder Complicated with Diabetes Mellitus].

OBJECTIVE: To determine the mediating role of hypothalamic-pituitary-adrenal axis (HPA) and hypothalamic-pituitary-thyroid axis (HPT) axis in anxiety disorder in patients with diabetes mellitus. METHODS: A total of 562 hospitalized patients with anxiety disorder participate in the study. Serum thyroid-stimulating hormone (TSH),total triiodothyronine (TT3),free triiodothyronine (FT3),total tetraiodothyronine (TT4),free tetraiodothyronine (FT4) ,adrenocorticotropic hormone (ACTH) and cortisol (PTC) were measured. Glucose tolerance test (OGTT) was performed,estimating insulin resistance index (HOMA IR) and insulin sensitivity index (WBISI). RESULTS: Of the participants,83 (14.8%) had diabetes. In those who were younger than 40 yr.,the diabetic patients were more likely to have abnormal FT4 and HPT ( P<0.05). The patients with diabetes were more likely to be older (OR=1.067, 95%CI:1.041-1.094, P=0.000) and have higher FT4 (OR=1.104, 95%CI:1.022-1.193, P=0.012) and PTC (OR=1.001, 95%CI:1.000-1.003, P=0.025) . Insulin resistance index increased while insulin sensitivity index decreased ( P<0.05) with abnormal PTC and HPA axis. Insulin sensitivity index decreased ( P<0.05) when ACTH,HPT axis,FT4 and TT3 were abnormal. CONCLUSION: Abnormal HPA or HPT axis mediates diabetic complications in patients with anxiety disorder. Early interventions on neuroendocrine hormone abnormality may help prevent diabetes in patients with anxiety disorder.

Inverse Association Between Serum Uric Acid Levels and Alzheimer's Disease Risk.

The association between Alzheimer's disease and uric acid levels had gained great interest in recent years, but there was still lack of definite evidence. A systematic review and meta-analysis of relevant studies was performed to comprehensively estimate the association. Relevant studies published before October 26, 2014, were searched in PubMed, Embase, and China Biology Medicine (CBM) databases. Study-specific data were combined using random-effects or fixed-effects models of meta-analysis according to between-study heterogeneity. Twenty-four studies (21 case-control and 3 cohort studies) were finally included into the meta-analysis. Those 21 case-control studies included a total of 1128 cases of Alzheimer's disease and 2498 controls without Alzheimer's disease. Those 3 cohort studies included a total of 7327 participants. Meta-analysis showed that patients with Alzheimer's disease had lower levels of uric acid than healthy controls (weighted mean difference (WMD) = -0.77 mg/dl, 95% CI -2.28 to -0.36, P = 0.0002). High serum uric acid levels were significantly associated with decreased risk of Alzheimer's disease (risk ratio (RR) = 0.66, 95% CI 0.52-0.85, P = 0.001). There was low risk of publication bias in the meta-analysis. There is an inverse association between serum uric acid levels and Alzheimer's disease. High serum uric acid level is a protective factor of Alzheimer's disease.