Chitosan derivatives as promising green corrosion inhibitors for carbon steel in acidic environment: Inhibition performance and interfacial adsorption mechanism.

Among the biodegradable polysaccharide, chitosan is widely present in the cell membranes of bacteria and algae and in the cell walls of higher plants. As a promising biopolymer, chitosan has great potential as eco-friendly corrosion inhibitor. Herein, two synthetic chitosan derivatives (N-phenylthiourea chitosan (CS-PT), N-phenyl-O-benzylthiourea chitosan (CS-PT-Bn)) were investigated as high-efficient acidic corrosion inhibitors to deal with the corrosion issue of carbon steel. The anti-corrosion property of the chitosan derivatives was explored by electrochemical tests, surface characterization and theoretical calculations. The experimental results indicate that both CS-PT and CS-PT-Bn present high-efficient inhibition performance with the inhibition efficiency of 98.4% and 98.5% at the concentration of 100 mg/L, respectively. Their adsorption mechanism at steel/solution interface is revealed by quantum chemical calculations, molecular dynamics (MD) and GFN-xTB calculations. It is found that CS-PT and CS-PT-Bn adsorb at the steel/solution interface by forming Fe-N and Fe-S bonds. Compared to CS-PT molecule, the introduction of benzyl group endows CS-PT-Bn molecule with stronger electrostatic effect and hydrophobicity, which favors the interfacial adsorption of CS-PT-Bn molecule on carbon steel surface.

In-depth unveiling the interfacial adsorption mechanism of triazine derivatives as corrosion inhibitors for carbon steel in carbon dioxide saturated oilfield produced water.

In this work, two triazine derivatives (BTT-1 and BTT-2) were synthesized by the simple one-step condensation of three components and used as high-efficient corrosion inhibitors to deal with the corrosion issue of carbon steel (CS) in petroleum industry. Electrochemical tests indicate that both BTT-1 and BTT-2 present superior inhibition performance with the inhibition efficiency of 97.9 % and 98.4 % at a low concentration of 0.18 mM, respectively. Quantum chemical calculations reveal that compared to BTT-1 molecule with a butyl chain, the introduction of benzyl group endows BTT-2 molecule with more adsorption sites, which favors the adsorption of BTT-2 molecule on CS surface. Furthermore, the GFN-xTB calculations demonstrate that BTT-1 and BTT-2 could adsorb on CS surface through the formation of Fe-N and Fe-S bonds. Compared to BTT-1, BTT-2 exhibits stronger adsorption on CS surface by forming more and shorter bonds with a more negative adsorption energy, which accounts for the better inhibitive performance of BTT-2.

[Systematic review of the epidemiological characteristics of inhalation injury in burn patients in China].

Objective: To study the epidemiological characteristics of inhalation injury in burn patients in China. Methods: The systematic review method was performed. Chinese Journal Full-text Database, Wanfang Database, and Chinese Biomedical Literature Database were searched with the Chinese search terms of ", , ", and PubMed and Embase were searched with the search terms of "burns, inhalation injury" to retrieve the collected retrospective studies on the epidemiological characteristics of inhalation injury in burn patients in China from the establishment of each database to January 2019. Data were extracted from the included articles, including the first author, study institution, study period, study subjects, number of burn patients, incidence of inhalation injury, and gender, age, causes of injury, mortality, and causes of death in patients with inhalation injury. Results: A total of 24 articles were included in this study with the first authors being from multiple research institutions across the country. The articles reported single or multi-center epidemiological studies with statistics on the incidence of inhalation injury in burn patients or severe burn patients admitted to key burn treatment institutions in many provinces/cities in China from 1958 to 2016. The number of burn patients included was 103-64 320 cases in the studies, and the incidence of inhalation injury in hospitalized burn patients ranged from 4.89% to 11.28%, with no obvious trend. The incidence of inhalation injury in severe burn patients was still high, from 19.09% to 32.38% as most articles reported. The number of men with inhalation injury was larger than that of women, with a male-to-female ratio of 1.61 ∶1.00-4.95 ∶1.00; young and middle-aged people were the high-risk population, and flame burn was the main cause of injury. The mortality of patients with inhalation injury was 5.17%-58.67%, of which the mortality was 5.17%-24.75% since 2000, in accordance with reports from hospitals in various regions that the mortality in the later period decreased significantly compared with the previous period. The causes of death in patients with inhalation injury included upper respiratory tract obstruction, sepsis, respiratory failure, and severe pulmonary infection. Conclusions: From 1958 to 2016, there is no obvious trend in the incidence of inhalation injury among burn patients in China; the incidence of inhalation injury is high in young and middle-aged males, and the main cause of inhalation injury is flame burn. The mortality of inhalation injury generally decreased since 2000 compared with the previous period.

Effective corrosion inhibition of mild steel by eco-friendly thiourea functionalized glucosamine derivatives in acidic solution.

In the view of environmental protection and sustainable development, the application of green effective inhibitors for metal corrosion in industry field is of great significance. In this work, two thiourea functionalized glucosamine derivatives, 5-hydroxy-1-phenyl-4-(1,2,3,4-tetrahydroxybutyl)imidazolidine-2-thione (GA-1) and 1-phenyl-3-(2,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-3-yl)thiourea (GA-2), were synthesized as eco-friendly corrosion inhibitors for mild steel (MS) in 1 M HCl solution, and their inhibition performance were evaluated by electrochemical tests and surface analyses. The electrochemical tests and surface analyses indicate that both GA-1 and GA-2 have high inhibition performance. Especially for GA-2, the inhibition efficiency reaches 97.7% with a concentration of 0.64 mM. Theoretical calculations were also conducted to elucidate the adsorption mechanism of GA-1 and GA-2 on MS surface.

Inhibitive and adsorption behavior of thiadiazole derivatives on carbon steel corrosion in CO2-saturated oilfield produced water: Effect of substituent group on efficiency.

Three thiadiazole derivatives with different substituent groups, 2-(benzylthio)-5-methyl-1,3,4-thiadiazole(BMT), 2-(benzylthio)-5-(butylthio)-1,3,4-thiadiazole(BBT), and 5-(benzylthio)-1,3,4-thiadiazole-2-thiol(BTT), were synthesized and studied as the corrosion inhibitors for N80 carbon steel in CO2-saturated oilfield produced water. It is found that the synthesized thiadiazole derivatives could effectively inhibit the corrosion of N80 carbon steel by chemisorption. The corrosion inhibition performance of the organic compounds is in the order: BTT > BBT > BMT. The theoretical calculations indicate that the tautomeric transformation from thiol-BTT to thione-BTT may be responsible for the high inhibition performance of BTT.

[Morphological and pathological changes of larynx after severe laryngeal burn in dogs and their relationship with laryngostenosis].

Objective: To investigate the morphological and pathological changes of the larynx after severe laryngeal burn in dogs and their relationship with laryngostenosis. Methods: Eighteen healthy, male beagle dogs were assigned into control group, immediately after injury group, and 2, 4, 6, and 8 weeks after injury groups according to the random number table, with 3 dogs in each group. Dogs of injury group inhaled saturated steam through mouth for 5 seconds to reproduce severe laryngeal burn. Tracheotomy and intubation were performed immediately after injury, and 400 000 U/d penicillin was intravenously infused for 1 week. The feeding, activity, and vocalization of dogs in each group after injury were observed until they were sacrificed. Immediately after injury and 2, 4, 6, and 8 weeks after injury, the laryngeal morphology of the dogs in corresponding time point groups were observed by endoscope. After the observation, the dogs in each injury group were sacrificed, and the laryngeal tissue was taken. The epiglottis, glottis, and cricoid cartilage were collected to make full-thickness tissue slice, respectively, and their pathological changes were observed with hematoxylin and eosin staining. The dogs of control group were not specially treated, and their life activities, laryngeal morphological and pathological changes were observed. Results: (1) The dogs of control group had normal feeding, activities, and vocalization. All the dogs in injury group survived until they were sacrificed, and their feeding, activities, and vocalization were obviously reduced after injury compared with those of control group. The dogs of 2, 4, 6 and 8 weeks after injury groups ate and moved normally 2 weeks after injury but vocalized abnormally in frequency and volume compared with those of control group, which lasted until they were sacrificed. (2) The dog's laryngeal mucosa in control group was complete and pink, without obvious exudation. The laryngeal mucosa of the dog in immediately after injury group was pale and edematous, with obvious exudation, local ulceration, necrosis, and exfoliation, and dilated microvessels on the surface. The laryngeal mucosa of the dogs in 2 weeks after injury group was pale, edematous, and oozed less than that of immediately after injury group, and the glottis was blocked by an obviously extruding mass. The paleness and edema of laryngeal mucosa were significantly reduced in the dogs of 4 weeks after injury group compared with those of 2 weeks after injury group, without dilated microvessel, and the glottic extruding mass was obviously smaller than that of 2 weeks after injury group. The sizes of glottic mass were similar between the dogs of 6 and 8 weeks after injury groups, which were obviously smaller than that in 4 weeks after injury group. (3) In the dogs of control group, the epithelial cells of epiglottis, glottis, and cricoid cartilage were normal in morphology, the proper glands were visible in the intrinsic layer, and the muscle fibers and the chondrocytes were normal in morphology. In the dogs of immediately after injury group, large sheets of epiglottis epidermis exfoliated, the epithelial cells were swollen and necrotic, the intrinsic glands were atrophic and necrotic, and the chondrocytes were degenerated and necrotic. The epidermis of the glottis partially exfoliated, the epithelial cells were swollen and necrotic, the intrinsic glands were atrophic and necrotic, the muscle fibers were partially atrophic and fractured, and the vacuolar chondrocytes were visible. The cricoid cartilage epidermis was ablated, the epithelial cells were swollen, the intrinsic layer and submucosal layer were slightly edematous, and the morphological structure of glands, chondrocytes, and muscle fibers were normal. In the dogs of 2 weeks after injury group, the epiglottis epidermis was completely restored, a small amount of glands in the intrinsic layer were repaired, and obsolete necrotic chondrocytes and new chondrocytes could be seen. A large number of fibroblasts, new capillaries, and inflammatory cells infiltration were observed in the epidermis of glottis, and intrinsic layer glands were repaired. The cricoid cartilage epidermis was repaired intactly, and there was no edema in the intrinsic layer. In the dogs of 4 weeks after injury group, the epiglottis intrinsic layer glands were further repaired compared with those of 2 weeks after injury group, and new chondrocytes were seen in the submucosa of the glottis. The condition of cricoid cartilage was consistent with that of control group. The dog's epiglottis, glottis, and cricoid cartilage were similar between the 6 and 8 weeks after injury groups, and no significant change was observed compared with those of 4 weeks after injury group. Conclusions: The morphological changes of larynx after severe laryngeal burn in dogs include mucosa detachment and necrosis, and mass blocking glottis. Pathological changes include epidermis shedding and necrosis, gland atrophy and necrosis, vascular congestion and embolism, chondrocytes degeneration, necrosis and proliferation, even local granulation tissue formation and cartilaginous metaplasia. These results may be the cause of laryngostenosis after laryngeal burn.

Revealing homogeneous plastic deformation in dendrite-reinforced Ti-based metallic glass composites under tension.

The tensile plastic deformation of dendrite-reinforced Ti-based metallic glass composites (MGCs) was investigated. It was found that there is a critical normalized strain-hardening rate (NSHR) that determines the plastic stability of MGCs: if the NSHR is larger than the critical value, the plastic deformation of the MGCs will be stable, i.e. the necking and strain localization can be effectively suppressed, resulting in homogeneous plastic elongation. In addition, dendrite-reinforce MGCs are verified as being intrinsically ductile, and can be used as good coatings for improving the surface properties of pure titanium or titanium alloys. These findings are helpful in designing, producing, and using MGCs with improved performance properties.

[The clinicopathological associations between TGF-ß1 and papillary thyroid carcinoma: a Meta-analysis.]

Objective:To comprehensively evaluate the association between the positive expression rate of transforming growth factor beta 1 (TGF-ß1) and papillary thyroid carcinoma (PTC) by using Meta-analysis.Method:Search the CNKI, Wan fang, VIP and PubMed database for accumulating papers studying on the relationship between the positive expression of TGF-ß1 and PTC in Chinese and English. Revman 5.3 was used to analyze the included trials.Result:A total of 6 studies comprising 617 samples was included in the meta-analysis. The TGF-ß1 were found in 243 patients (64.63%) of 376 PTC patients, and the total positive expression rate is 46.19%. Performing the subgroup analysis according to age, gender, lymphatic metastasis and TNM, the results showed that there was a significant association between the positive expression rate of TGF-ß1 and lymphatic metastasis (OR=5.44, 95%CI3.31-8.93,P <0.000 01).Conclusion:This meta-analysis confirmed significant associations between the expression of TGF-ß1 and PTC with lymph node metastasis. TGF-ß1 may be used as a predictive factor for prognosis of PTC with lymph node metastasis.

[Influence of covering of auto-crosslinked sodium hyaluronate gel in combination with xenogenic acellular dermal matrix on healing of full-thickness skin defect wound in pig].

OBJECTIVE: To explore the influence of covering of auto-crosslinked sodium hyaluronate gel in combination with xenogenic acellular dermal matrix (ADM) on healing of full-thickness skin defect wound in pig. METHODS: Totally four 10 cm×10 cm full-thickness skin defect wounds were reproduced symmetrically on both sides of spine on the back of each one of the six Chinese experimental minipigs. After autologous microskin grafting, the 4 wounds in each pig were divided into 4 groups according to the random number table, with 6 wounds in each group. Wounds in allogenic skin group (AS) were covered by full-thickness skin from one (not the recipient) of the 6 pigs; wounds in xenogenic skin group (XS) were covered by full-thickness skin of sheep; wounds in xenogenic ADM group (XA) were covered by ADM of sheep; wounds in combination group (C) were covered by ADM of sheep combined with auto-crosslinked sodium hyaluronate gel. The wounds were bound up with pressure, and the dressing was changed once every 7 days. On post surgery day (PSD) 7, 14, 21, 28, 35, and 42 when changing dressing, the condition of wounds and the exfoliation of the covering on microskin were observed, and the complete exfoliation time of the covering was recorded. On PSD 28, 35, and 42, the wound healing rate was calculated. Data were processed with one-way analysis of variance and SNK test. RESULTS: (1) On PSD 7, no fluid appeared under the covering of wounds in groups AS and C, while plenty of fluid appeared under the covering of wounds in groups XS and XA. From PSD 14 to 35, most of the full-thickness skin of pig in group AS did not exfoliate. All the full-thickness skin of sheep in group XS exfoliated, leaving a lot of crusts on the surface of the wounds on PSD 14. Most of the ADM of sheep in group XA separated from the wound with the crusts turning dry and exfoliating on PSD 14. All the ADM of sheep exfoliated with most of the wounds healed in group C on PSD 35. On PSD 42, all the full-thickness skin of pig in group AS exfoliated, leaving most of the wounds unhealed; all the crusts exfoliated and the majority of wounds were healed in group XS and XA group; all the wounds in group C were healed. (2) Compared with that in group C[(32.7±3.3) d], the complete exfoliation time of the covering was obviously shorter in group XS[(15.2±4.8) d]and group XA[(22.2±6.3) d], with P values below 0.05, while the complete exfoliation time of the covering in group AS[(44.8±2.7) d]was obviously longer (P<0.05). (3) On PSD 28, 35, and 42, the wound healing rates in groups XS and XA[(21.2±2.6)%, (51.4±2.4)%, (89.6±2.8)%, and (23.7±3.4)%, (53.6±6.3)%, (91.3±4.9)%, respectively]were obviously lower than those in group C[(35.1±3.4)%, (62.1±6.7)%, (98.8±1.0)%, respectively, with P values below 0.05]. On PSD 42, the wound healing rate in group AS[(44.0±3.8)%]was significantly lower than the rates in the other 3 groups (with P values below 0.05). CONCLUSIONS: Auto-crosslinked sodium hyaluronate gel combined with ADM of sheep used as covering of microskin grafts on full-thickness wound in pig can lengthen the persistence time of ADM of sheep on the wound, as well as promote wound healing.