Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 30
Filter
Add more filters










Publication year range
1.
Small ; 20(12): e2306563, 2024 Mar.
Article in English | MEDLINE | ID: mdl-37929642

ABSTRACT

Crystalline carbon nitride (CCN), derived from amorphous polymeric CN, is considered as a new generation of metal-free photocatalyst because of its high crystallinity. In order to further promote the photocatalytic performance of CCN, p-type MnO nanoparticles are in situ synthesized and merged with n-type CCN through a one-pot process to form p-n heterojunction. The formed interfacial electric field between the semiconductors with different work functions efficiently breaks the coulomb interaction between MnO and CCN. The prepared catalysts exhibit drastically increased photocatalytic hydrogen evolution (PHE) activity integrated with oxidation of alkyl and aryl alcohols under irradiation of visible light. In the aqueous solution of benzyl alcohol (BzOH), the hydrogen generation rate over MnO/CCN (39.58 µmol h-1) is nearly 7 times and 37 times that of pure CCN (5.76 µmol h-1) and CN (1.06 µmol h-1), respectively, combining with oxidation of BzOH to benzaldehyde. This work proposes an avenue for in situ construction of a novel 2D material-based S-scheme heterojunction and extends its application in solar energy conservation and utilization.

2.
PLoS One ; 18(1): e0280459, 2023.
Article in English | MEDLINE | ID: mdl-36656842

ABSTRACT

Designers search for memories and retrieve appropriate mental information during design brainstorming. The specific contents of retrieved memories can serve as stimuli for new ideas, or act as barriers to innovation. These contents can be divided into different categories, which are reflected in designers' creativities, and derived from individual lives and design experiences. Appropriate categorization of retrieved memory exemplars remains a fundamental research issue. This study tentatively divided retrieved memory exemplars into eight categories from brainstorming on the topic of library desk and chair design. A verification questionnaire was performed and validated the accuracy of categorization. The categorization result could be applied to design education in terms of understanding students' design performances and capabilities.


Subject(s)
Memory, Episodic , Mental Recall , Humans , Memory , Surveys and Questionnaires
3.
PLoS One ; 18(1): e0271478, 2023.
Article in English | MEDLINE | ID: mdl-36626379

ABSTRACT

In order to clarify the effects of crude bio-oil for phenol-formaldehyde resin, the phenol-formaldehyde resin with bio-oil model compounds (BMPF) were prepared by model compound method. The bonding strength and aging resistance of BMPF were determined, and their microstructure and chemical bonds were also analyzed by scanning electron microscope, Fourier transform infrared spectroscopy, and nuclear magnetic resonance analysis, respectively. The results showed that the components of crude bio-oil had various degrees of effects on the BMPF performance, and the most obvious one is the phenols. The phenols and the ketones of bio-oil had positive effects on the bonding strength. The ketones had the biggest effect on the surface smoothness of BMPF film. But all components of bio-oil could inordinately improve the aging resistance of BMPF. The structural analysis indicated that the effects of bio-oil components on the BMPF performance by changing the resin structure. The CH2 peak in FT-IR and the methylene bridges intensity in NMR of phenol-free BMPF and ketone-free BMPF were smaller, while the results of aldehyde-free BMPF and acid-free BMPF were opposite. And the influence degree of BMPF structure was basically consistent with that of BMPF performance. These results could provide a basis for the modification of phenol-formaldehyde resin by crude bio-oil.


Subject(s)
Petroleum , Spectroscopy, Fourier Transform Infrared , Phenols/chemistry
4.
Anim Sci J ; 93(1): e13769, 2022.
Article in English | MEDLINE | ID: mdl-36127314

ABSTRACT

The composition of amino acid and fatty acid has a vital function on meat quality and animal health. However, the underlying mechanism of amino acid and fatty acid metabolism in sheep during different grazing periods is still unclear. In this study, a total of 12 sheep were employed in different grazing periods. Our results showed that the composition of amino acids and fatty acids in muscle and adipose tissues was significantly altered between dry grass (DG) period and green grass (GG) period. Changes in the activities of the metabolism-related enzymes including BCKD, BCAT2, ACC, SCD, HSL, GSK3ß, p-GSK3ß, and FABP4 were observed in muscle and adipose during different grazing periods. In addition, the mRNA expression levels of ACC, FAS, SCD, HSL, LPL, and DGAT1 in muscle and adipose tissue were changed markedly in different grazing periods. Furthermore, the expression levels of mTOR and ß-catenin/PPARγ/C/EBPα pathway-related proteins were predominantly altered in muscle and adipose among DG and GG. Taken together, all investigations simplified the process of amino acid and fatty acid metabolism disorders caused by different grazing periods, and the mTOR and ß-catenin/PPARγ/C/EBPα play the essential role in this process, which provided an underlying mechanism of metabolism and meat quality.


Subject(s)
Amino Acids , Fatty Acids , Adipose Tissue/metabolism , Amino Acids/analysis , Animals , Fatty Acids/analysis , Glycogen Synthase Kinase 3 beta , Muscles/metabolism , PPAR gamma/metabolism , RNA, Messenger/metabolism , Sheep , TOR Serine-Threonine Kinases/metabolism , beta Catenin/metabolism
5.
Comput Math Methods Med ; 2022: 4614665, 2022.
Article in English | MEDLINE | ID: mdl-35936357

ABSTRACT

The decline in sheep health and meat quality caused by seasonal nutritional deficiencies has always been an important problem in the production of naturally grazing sheep. Glucose metabolism is crucial in ruminants for adequate cell function and maintenance of the body tissues and systems. However, whether glucose metabolism, especially gluconeogenesis, is affected by seasonal grazing conditions has not been fully uncovered. Thus, twelve sheep from two seasons (dry and green grass periods) in natural grazing areas of Inner Mongolia, China, were selected for this study. Their serum glucose, insulin, PC, and PEPCK levels and volatile fatty acid (gluconeogenesis material) concentrations in rumen fluid were analyzed. The expression of key enzymes including PC, PEPCK, GLUT2, and G6P of gluconeogenesis and their regulators INSR, PI3K/AKT and p53-SIRT6-Fox01 in the liver was detected by real-time PCR and western blotting. The results revealed significant variances in gluconeogenesis and its indicators and showed p53-SIRT6-Fox01 as having potential regulation in different grazing periods. This study offers new insights into the mechanism of gluconeogenesis and adaptive regulation between dry grass period and green grass period and also provides a reference for maintaining the health of sheep and meat quality despite seasonal nutritional deficiencies.


Subject(s)
Malnutrition , Sirtuins , Animals , Gluconeogenesis/physiology , Glucose , Liver/metabolism , Malnutrition/metabolism , Phosphatidylinositol 3-Kinases/metabolism , Sheep , Sirtuins/metabolism , Tumor Suppressor Protein p53/genetics
6.
PLoS One ; 17(6): e0269363, 2022.
Article in English | MEDLINE | ID: mdl-35771796

ABSTRACT

The influence of thinking flexibility on design is often underestimated by researchers in the field of design education. In this study, morphological analysis was used as a tool to develop design proposals and eye tracking technology was applied to track the attention. The feature of thinking activities in problem-solving between two groups (novice and expert) was analyzed by Heat map and Gaze plot in qualitative, and measured by indicators such as fixation and saccade in quantitative. Findings suggested that, i) Experts showed more fixation duration and fixation numbers in thinking activities, and the attention containing more AOIs was positively related to the rationality of the scheme. ii) Saccades with greater amplitude were more beneficial to the novelty of scheme. iii) Experts considered the information of each block in a balanced way, while novices tended to ignore unimportant blocks. These results will have a far-reaching impact on the development of designers' thinking and help novices to exercise creative thinking and produce high-quality designs.


Subject(s)
Eye-Tracking Technology , Saccades , Attention
7.
Polymers (Basel) ; 14(7)2022 Mar 26.
Article in English | MEDLINE | ID: mdl-35406225

ABSTRACT

The bio-oil phenol-formaldehyde (BPF) resin, prepared by using bio-oil as a substitute for phenol, has similar bonding strength but lower price to phenol-formaldehyde (PF) resin. As a common adhesive for outdoor wood, the aging performance of BPF resin is particularly important. The variations in mass, bonding strength, microstructure, atomic composition, and chemical structure of BPF resin under five aging conditions (heat treatment, water immersion, UV exposure, hydrothermal treatment, and weatherometer treatment) were characterized by scanning electron microscope, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy, respectively. Compared under five aging conditions, after aging 960 h, the mass loss of plywood and film was largest under hydrothermal treatment; the bonding strength of plywood, the surface roughness, and O/C ratio of the resin film changed most obviously under weatherometer treatment. FT-IR analysis showed that the decreased degree of peak intensity on CH2 and C-O-C characteristic peaks of BPF resin were weaker under water immersion, hydrothermal treatment, and weatherometer treatment than those of PF resin. The comparison of data between BPF and PF resins after aging 960 h showed that adding bio-oil could obviously weaken the aging effect of water but slightly enhance that of heat. The results could provide a basis for the aging resistance modification of BPF resin.

8.
ACS Appl Mater Interfaces ; 12(43): 49030-49041, 2020 Oct 28.
Article in English | MEDLINE | ID: mdl-33073568

ABSTRACT

In the 5G era, for portable electronics to operate at high performance and low power levels, the incorporation of superior electromagnetic interference (EMI) shielding materials within the packages is of critical importance. A desirable wearable EMI shielding material is one that is lightweight, structurally flexible, air-permeable, and able to self-clean. To this end, a bioinspired electroless silver plating strategy and a one-step electrodeposition method are utilized to prepare an EMI shielding fabric (CEF-NF/PDA/Ag/50-30) that possesses these desirable properties. Porous CEF-NF mats with a spatially distributed silver coating create efficient pathways for electron movement and enable a remarkable conductivity of 370 S mm-1. When tested within a frequency range of 8.2-12.4 GHz, this highly conductive fabric not only achieves an EMI shielding effectiveness (EMI SE of 101.27 dB at 5028 dB cm2 g-1) comparable to a very thin and light metal but also retains the unique properties of fabrics-being light, structurally flexible, and breathable. In addition, it exhibits a high contact angle (CA) of 156.4° with reversible surface wettability. After having been subjected to 1000 cycles of bending, the performance of the fabric only decreases minimally. This strategy potentially provides a novel way to design and manufacture an easily integrated EMI shielding fabric for flexible wearable devices.

9.
Sci Total Environ ; 734: 139233, 2020 Sep 10.
Article in English | MEDLINE | ID: mdl-32460071

ABSTRACT

Arsenic (As) poisoning and its potential reproductive functional lesions are a global environmental concern. Recent studies shown that spermiogenesis tends to be a major target process in arsenic-induced male infertility, however, the underlying mechanisms are not fully illuminated. In the present study, 32 fertility related indices including sperm motility, dynamic acrosome formation and sperm flagellum during spermiogenesis in testes were evaluated in adult male mice treated with 0, 0.2, 2, and 20 ppm As2O3 via drinking water for 180 consecutive days. The results showed that out of 32 indices, 11, 25, and 29 indicators were changed statistically by 0.2-, 2-, and 20- ppm As2O3 treatment compared to the controls (0 ppm As2O3), respectively, which reveals a significant dose-dependent relationship. For details, sperm motilities were significantly decreased by 18.85%, 32.47% and 29.53% in three As2O3 treatment groups compared to the control group. Meanwhile, the ultra-structures of acrosome formation and sperm flagellum in testes have been altered by chronic arsenic exposure. Furthermore, arsenic decreased the mRNA expressions of 11 out of 13 genes associated with acrosome biosynthesis and 11 out of 12 genes related to flagellum formation in testes, particularly, down-regulated DPY19L2, AKAP3, AKAP4, CFAP44 and SPAG16 were further confirmed at the protein levels by western blotting. Taken together, chronic arsenic exposure declines male fertility by disorganizing dynamic acrosome and flagellum formation in testes. Especially, DPY19L2, AKAP3, AKAP4, CFAP44, and SPAG16 maybe the potential targets in this process. These results may offer not only a new insight to the mechanism of arsenic-induced male reproductive toxicity, but also provide a clue for the diagnosis and therapy of arseniasis.


Subject(s)
Acrosome , A Kinase Anchor Proteins , Animals , Arsenic , Flagella , Male , Membrane Proteins , Mice , Sperm Motility , Spermatogenesis , Spermatozoa
10.
Chemosphere ; 238: 124650, 2020 Jan.
Article in English | MEDLINE | ID: mdl-31472347

ABSTRACT

Arsenic (As) has become a major problem in maintaining the environment and human health due to its wide application in the production of agriculture and industry. Many studies indicate that As can affect spermatogenesis process and lower sperm quality. However, the undergoing molecular mechanism is unclear. For this, forty-eight 8-week old adult male mice were divided into four groups of twelve each, which were administrated to 0, 0.2, 2, 20 ppm As2O3 in their drinking water respectively for six months. The results showed that As treatment reduced sperm counts and increased the sperm malformation ratio of mice. Interestingly, both the amounts of round and elongated spermatids, and the ratios of spermatids elongation were decreased significantly by As exposure. Furthermore, the structure of Chromatoid Body (CB) which presents a typical nebulous shape in round spermatids after spermatogenesis arrested, and the mRNA expression levels of gene TDRD1, TDRD6 and TDRD7 related to CB were changed by arsenic. Again, the mRNA and protein expression levels of the markers DDX25 and CRM1 in haploid periods of spermatogenesis and the associated proteins HMG2, PGK2, and H4 with DDX25 regulation were declined significantly with As treatment. Taken together; it reveals that As interferes with spermatogenesis by disorganizing the elongation of spermatids. H4, HMG2 and PGK2 are regulated by DDX25 which interacts with CRM1 and may play a vital role in spermatogenesis disorder induced by As exposure, which maybe provides one of the underlying mechanisms for As-induced male reproductive toxicity.


Subject(s)
Arsenic/toxicity , Spermatids/pathology , Spermatogenesis/drug effects , Aging , Animals , Cell Cycle Proteins/genetics , DEAD-box RNA Helicases/genetics , Gene Expression Profiling , Male , Mice , RNA, Messenger/metabolism , Spermatids/drug effects , Spermatozoa/metabolism
11.
Chinese Journal of School Health ; (12): 1015-1018, 2020.
Article in Chinese | WPRIM (Western Pacific) | ID: wpr-823167

ABSTRACT

Objective@#To explore the effect of blended health literacy education combining WeChat and participatory class among college students, and to provide references for enriching the technology of health education in college.@*Methods@#Using cluster random sampling method, 378 freshmen from 10 classes of a non-medical college in Guangzhou were selected as the research objects. The intervention group (193) was given blended health literacy education including WeChat and participatory class education, while the control group (185) recieved no intervention. The other types of health educaiton were not limited in both groups. A survey was conducted among those college students before and after the health education by applying Questionnaire on College Students’ Health Literacy.@*Results@#According to the baseline survey, there were no significant differences between the intervention group and the control group in the level of health literacy and basic situations(P>0.05). But after the intervention, the scores of health literacy and basic health concept and knowledge, health skills of three aspects were (54.34±6.03) (23.91±2.44) (12.39±2.32) respectively, and infectious diseases prevention, chronic diseases prevention, safety and first aid,health information of six health issues were(5.59±1.34) (10.17±1.57) (12.88±1.55) (6.33±1.58), higher than those in the control group, and the differences were statistically significant(t=3.50, 2.50, 3.94, 2.50, 2.79, 2.48, 2.12, P<0.05). The overall health literacy level of the intervention group was 71.5%(138/193) and the control group was 51.9%(96/185), there was significant difference between two groups(χ2=15.40, P<0.01).@*Conclusion@#Blended health literacy education improves college students’ health literacy level sbustantially, which may provide references to the technology of health literacy intervention in college.

12.
Polymers (Basel) ; 11(9)2019 Sep 09.
Article in English | MEDLINE | ID: mdl-31505829

ABSTRACT

Introducing bio-oil into phenolic foam (PF) can effectively improve the toughness of PF, but its flame retardant performance will be adversely affected and show a decrease. To offset the decrease in flame retardant performance, montmorillonite (MMT) can be added as a promising alternative to enhance the flame resistance of foams. The present work reported the effects of MMT on the chemical structure, morphological property, mechanical performance, flame resistance, and thermal stability of bio-oil phenolic foam (BPF). The Fourier transform infrared spectroscopy (FT-IR) result showed that the -OH group peaks shifted to a lower frequency after adding MMT, indicating strong hydrogen bonding between MMT and bio-oil phenolic resin (BPR) molecular chains. Additionally, when a small content of MMT (2-4 wt %) was added in the foamed composites, the microcellular structures of bio-oil phenolic foam modified by MMT (MBPFs) were more uniform and compact than that of BPF. As a result, the best performance of MBPF was obtained with the addition of 4 wt % MMT, where compressive strength and limited oxygen index (LOI) increased by 31.0% and 33.2%, respectively, and the pulverization ratio decreased by 40.6% in comparison to BPF. These tests proved that MMT can blend well with bio-oil to effectively improve the flame resistance of PF while enhancing toughness.

13.
Int J Biol Macromol ; 137: 1013-1019, 2019 Sep 15.
Article in English | MEDLINE | ID: mdl-31299251

ABSTRACT

Photophobic (white) films were prepared by mixing hydroxypropyl methylcellulose (HPMC) of different molecular weights with sodium citrate (SC). Wide angle X-ray diffractometry, small angle X-ray scattering, scanning electron microscopy, dynamic mechanical analysis, whiteness determination and texture analysis were used to investigate the effect of HPMC molecular weight on the aggregation structures and properties of HPMC film. The crystalline integrity decreased with the increased molecular weight of HPMC for these HPMC/SC films. Similar crystallinity was observed for 6HPMC/SC and 15HPMC/SC, which was larger than that of 50HPMC/SC. All the three HPMC/SC film showed surface fractal structure with similar Ds. With the increasing molecular weight of HPMC, the HPMC/SC film showed honeycomb structures with smaller holes and more compact porous structure, Tg first increased and then decreased a little, the tensile strength and elongation increased with the increasing HPMC molecular weight. 50HPMC/SC films with the smallest pores showed the largest whiteness. A new Tg' peak was observed for HPMC/SC film.


Subject(s)
Hypromellose Derivatives/chemistry , Light , Sodium Citrate/chemistry , Mechanical Phenomena , Molecular Weight
14.
Environ Pollut ; 253: 538-551, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31330346

ABSTRACT

The effect of fluoride as an ongoing topic has attracted much attentions due to the decline in overall human fertility worldwide. However, whether fluorine causes a temporary stimulus or permanent damage to the male reproductive system, as well as the mechanism of fluoride influencing spermatogenesis remained unclear. 48 adult male rats were randomly divided into four groups (twelve each). Control group received the distilled water, while the other three groups were treated with 25, 50, 100 mg/L NaF via drinking water for 8 weeks. Six rats from each group were selected randomly to detect the levels of various indices related to spermatogenesis. The remaining rats were given only distilled water and left for recovery of a period of 2 weeks. Results showed that the levels of serum CK, ALP, CHE, BUN, UA, and Cr, testis morphology and the ultrastructure of sperm acrosome and chromatoid body (CB) were significantly changed by fluoride. Interestingly, the elongated spermatid counts, spermatids elongation ratio, and mRNA expressions of Prm1/2 and MIWI, TDRD1, TDRD 6, TDRD7, PABP, and Hsp72 related to CB decreased markedly in fluoride treatment groups compared to the control. Furthermore, the expression levels of DDX25 and associated regulatory proteins like CRM1, HMG2, H4, TP2, and PGK2 were down-regulated by fluoride. After 2-weeks withdrawal period, out of the 19 altered spermatogenesis indicators, 15 indicators in 100 mg/L group and 3 indicators in 50 mg/L group still exhibited a significant change, while none showed change in 25 mg/L group. These results proved that the reversibility of fluoride toxicity is dose-dependent on the male reproductive system. Meanwhile, fluoride caused unrestored arrest during the haploid period of spermatogenesis, where reduced DDX25 and associated regulatory proteins play a crucial role in this process, which could provide the underlying insights to the toxic mechanism of fluoride induced male reproductive toxicity.


Subject(s)
DEAD-box RNA Helicases/metabolism , Fluorides/toxicity , Spermatogenesis/drug effects , Testis/enzymology , Animals , DEAD-box RNA Helicases/genetics , Drinking Water , Male , Mice, Knockout , Rats , Spermatozoa/drug effects , Testis/drug effects
15.
ACS Appl Mater Interfaces ; 11(16): 14986-14996, 2019 Apr 24.
Article in English | MEDLINE | ID: mdl-30945844

ABSTRACT

A facile and simple synthetic route is developed to prepare earth-abundant and noble metal-free hybrid photocatalysts, which are composed of graphitic carbon nitride (CN), nickel complex, and NiO x nanoparticles. Bimolecular nucleophilic substitution reaction was employed to attach a nickel complex onto a graphitic CN framework through covalent bonds to support its high loading and dispersion. NiO x nanoparticles were further incorporated into the catalysts to serve as a hole-transporting medium to improve the separation of photogenerated carriers for higher photocatalytic activity. Both yNiL/CN and yNiL/NiO x/CN exhibit superb H2 evolution activity. The optimum H2 evolution rate of the binary photocatalysts yNiL/CN reaches 303.3 µmol·h-1·g-1, whereas that of the ternary photocatalysts yNiL/NiO x/CN reaches 524.1 µmol·h-1·g-1, and the apparent quantum efficiency reaches 1.46% at 450 nm. This finding reveals that coordination of a nickel complex is significant in promoting photocatalytic performance, and the incorporation of NiO x nanoparticles as a hole-transporting medium is beneficial for separation of the photogenerated charge carriers. The novel hybrid system offers a new horizon for designing transition-metal complex-modified graphitic CN as noble metal-free and highly active photocatalysts for efficient visible light-driven hydrogen generation.

16.
Materials (Basel) ; 11(11)2018 Nov 09.
Article in English | MEDLINE | ID: mdl-30423925

ABSTRACT

Bio-oil was added as a substitute for phenol for the preparation of a foaming phenolic resin (PR), which aimed to reduce the brittleness and pulverization of phenolic foam (PF). The components of bio-oil, the chemical structure of bio-oil phenolic resin (BPR), and the mechanical performances, and the morphological and thermal properties of bio-oil phenolic foam (BPF) were investigated. The bio-oil contained a number of phenols and abundant substances with long-chain alkanes. The peaks of OH groups, CH2 groups, C=O groups, and aromatic skeletal vibration on the Fourier transform infrared (FT-IR) spectrum became wider and sharper after adding bio-oil. These suggested that the bio-oil could partially replace phenol to prepare resin and had great potential for toughening resin. When the substitute rate of bio-oil to phenol (B/P substitute rate) was between 10% and 20%, the cell sizes of BPFs were smaller and more uniform than those of PF. The compressive strength and flexural strength of BPFs with a 10⁻20% B/P substitute rate increased by 10.5⁻47.4% and 25.0⁻50.5% respectively, and their pulverization ratios decreased by 14.5⁻38.6% in comparison to PF. All BPFs maintained good flame-retardant properties, thermal stability, and thermal isolation, although the limited oxygen index (LOI) and residual masses by thermogravimetric (TG) analysis of BPFs were lower and the thermal conducticity was slightly greater than those of PF. This indicated that the bio-oil could be used as a renewable toughening agent for PF.

17.
Int J Biol Macromol ; 120(Pt A): 945-951, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30193915

ABSTRACT

Monosodium phosphate (MP), sodium citrate (SC), sodium lactate (SL) and magnesium citrate (MC) can be blended with hydroxypropyl methylcellulose (HPMC) to make photophobic (white) films at lower drying temperatures. Small angle X-ray scattering (SAXS), wide angle X-ray diffraction (XRD), scanning electron microscopy (SEM), whiteness determination, dynamic mechanical analysis (DMA) and texture analysis were adopted to study the variation of microstructures and properties. These four kinds of HPMC/salt films showed decreased crystallinity and increased compactness and smoothness of the self-similar structures in larger scale ranges. HPMC/MP, HPMC/SC and HPMC/SL film showed coarser and porous morphologies, lower mechanical parameters and higher whiteness than pure HPMC film. HPMC/MC film showed smoother morphologies, higher tensile strength, elongation and whiteness than pure HPMC film. Porous structures and more compact self-similar structures might contribute to the photophobic property of these films, and relatively smooth morphology might dominate the increasing mechanical parameters of HPMC/MC film.


Subject(s)
Hypromellose Derivatives/chemistry , Salts/chemistry , Citric Acid/chemistry , Light , Microscopy, Electron, Scanning , Organometallic Compounds/chemistry , Phosphates/chemistry , Sodium Citrate/chemistry , Sodium Lactate/chemistry , Tensile Strength/radiation effects , X-Ray Diffraction
18.
Chem Asian J ; 13(20): 3073-3083, 2018 Oct 18.
Article in English | MEDLINE | ID: mdl-30098233

ABSTRACT

In this study, a photocatalyst with a distorted skeleton and synthesized by grafting triamterene onto graphitic carbon nitride (g-C3 N4 ) frameworks was prepared. The pteridine ring of the triamterene-based nitrogen-enriched organic structure functions as a trapped electron site owing to its inductive effect. The benzene ring in triamterene plays an important role in the even dispersion of electrons by a conjugative effect. Redistribution of the intramolecular electronic potential is caused by a synergistic effect between the pteridine and benzene rings of triamterene and promotes separation and migration of the photoinduced charge carriers. After coupling with triamterene, the π electrons of g-C3 N4 are relocated; that is, the intrinsic electronic and band structures of g-C3 N4 are effectively modulated. The modified polymeric photocatalyst shows a high photocatalytic H2 evolution rate of 157.5 µmol h-1 , a value that is 4.3 times higher than the H2 evolution rate of pristine g-C3 N4 (36.8 µmol h-1 ), with an apparent quantum efficiency of 9.7 % at λ=450 nm. The incorporation of triamterene into the g-C3 N4 frameworks significantly expands its π-delocalized system by redistribution of the electronic potential, expands the visible-light absorption range, and effectively promotes the separation and migration of photoinduced charge carriers. This strategy may provide a reference for promoting charge separation of g-C3 N4 through redistribution of the electronic potential and for synthesizing novel carbon nitride based semiconductors for efficient solar energy conversion into hydrogen.

19.
J Colloid Interface Sci ; 526: 374-383, 2018 Sep 15.
Article in English | MEDLINE | ID: mdl-29751271

ABSTRACT

This work reports effective photocatalysts which are composed of carbon nitride (CN), carbon nanotubes (CNTs), MoS2 and NiS, for hydrogen evolution aiming at energy crises and environmental pollutions. The morphologies and optical properties of the photocatalysts were carefully characterized and their photocatalytic performance towards water reduction was studied afterwards. MoS2 and NiS exhibit a significant synergistic effect working as co-catalysts. Compared to MoS2/CN nanohybrid, carbon nanotubes and NiS improved the absorption of visible light and the separation of charge carriers effectively. NiS-MoS2/CNTs/CN catalyst exhibits high performance for H2 evolution and the optimized rate is 309.9 µmol·h-1·g-1 with no noble metals under visible light irradiation. The study demonstrates a non-noble metal photocatalyst system for effective generation of hydrogen with low cost.

20.
Polymers (Basel) ; 10(11)2018 Oct 24.
Article in English | MEDLINE | ID: mdl-30961108

ABSTRACT

The aging properties of phenol-formaldehyde resin modified by bio-oil (BPF) were analyzed using ultraviolet (UV) weathering. The variations on bonding strength of BPF were measured, and the changes on microstructure, atomic composition and chemical structure of BPF were characterized by using a scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and nuclear magnetic resonance (NMR), respectively. With the increase of aging time, the bonding strength decreased gradually, the resin surface became rougher and the O/C radio of resin surface increased. However, the loss rate of bonding strength of BPFs was 9.6⁻23.0% lower than that of phenol-formaldehyde resin (PF) after aging 960 h. The aging degree of BPF surfaces was smaller in comparison to PF at the same aging time. These results showed that the bio-oil had a positive effect on the anti-aging property. Analytical results revealed that with increasing the aging time, the XPS peak area of C⁻C/C⁻H decreased, while that of C=O and O⁻C=O increased. The intensity of methylene and ether bridges in NMR analysis decreased along with increasing the intensity of aldehydes, ketones, acids and esters. These results indicated that the aging mechanism of BPF was a process of the breakage of molecular chains and formation of oxygen-containing compounds.

SELECTION OF CITATIONS
SEARCH DETAIL
...