Concrete is widely used in building construction, civil engineering, roads, bridges, etc., but concrete cracking remains a major issue in the engineering industry. To develop an effective and feasible concrete repair technology, this study combined microbial and microencapsulation technologies to prepare a multi-layer compound microcapsule using the piercing method. The formulation and drying method of microcapsules were optimized by taking their embedding rate and mechanical properties as evaluation criteria. The calcium transcrystallization process of microcapsules and the crystal form of products were characterized and compared with the calcium transcrystallization process in free cells. Finally, the effects of microcapsule incorporation on mechanical properties, impermeability, and self-healing performance of concrete specimens were then tested. The results showed that the air-dried multi-layer compound microcapsules, formulated with 1.0% wet cells of Bacillus cereus, 1.5% calcium chloride, 3.0% sodium alginate, 5.0% nutrients, 6.0% glycerol, 0.6% chitosan, and 2.0% urea, achieved an embedding rate of 95.3%, a rupture force of 60.0 N and a hardness of 150.8 N. These microcapsules can transform from a solid state to a flowing colloidal state when the microorganisms inside undergo a calcium formation reaction. Both the microcapsules and free cells produced stable calcite crystal forms of calcium carbonate through the calcium conversion reaction, with the microcapsules producing more uniform-sized particles, which are more conducive to accumulation in cracks, thereby enhancing the stability of repair. When microcapsules were incorporated into the concrete specimen at a content of 0.45%, the flexural strength of the specimen increased by 17.3%, and the compressive strength increased by 12.3%. In the water impermeability test, specimens with microcapsules demonstrated better impermeability compensation for the cement concrete than those with free cells. The self-healing effect of cracks proved that multi-layer compound microcapsules could completely repair cracks up to 0.7 mm wide, and a repair rate of 95% for 0.8 mm wide cracks. In this study, a multi-layer compound microcapsule was developed to protect microorganisms in concrete and provide nutrients required for their growth, which provided a new idea for microbial induced calcium carbonate precipitation in concrete crack repair.
Construction Materials ; Capsules/chemistry* ; Bacillus cereus/metabolism* ; Alginates/chemistry*

Objective: In order to understand the dust concentration in the workplace of dust exposure enterprises in Shenxian. To evaluate the degree of occupational hazard factors of dust exposure enterprises. And provide basis for the formulation of occupational protection standards and management system of dust exposure enterprises. Methods: In February 2022, the dust concentration monitoring data of 89 dust exposure enterprises from 2017 to 2020 by the Shenxian Center for Disease Control and Prevention were collected, and the qualified rates of dust concentration detection of dust exposure enterprises in different years, dust types and enterprise sizes were analyzed. Results: A total of 89 dust enterprises were monitored from 2017 to 2020, 2132 dust samples were collected, and 1818 qualified samples were taken, with a total qualified rate of 85.3%. From 2017 to 2020, the dust detection qualified rates showed a year-by-year increase trend, 78.7% (447/568), 84.1% (471/560), 88.6% (418/472) and 90.6% (482/532), respectively, with statistically significant differences (χ(2)=36.27, P=0.003). The differences in the qualified rates of dust detection samples of silicon dust (66.1%, 41/62), grain dust (86.7%, 1549/1786), cotton dust (84.1%, 106/126) and wood dust (77.2%, 122/158) were statistically significant (χ(2)=29.66, P=0.002). The qualified rate of dust samples in large and medium-sized enterprises (95.1%, 1194/1256) was higher than that of small-sized enterprises (71.2%, 624/876), and the difference was statistically significant (χ(2)=1584.40, P=0.001) . Conclusion: The qualified rate of dust concentration monitoring results of dust exposure enterprises in Shenxian showed an increase trend year by year, while the pualified rate of dust concentration monitoring in small-sized enterprises was low, and the occupational hazard of silica dust was still severe.
Dust ; Silicon ; Wood ; Workplace

Occupational disease hazards in plywood manufacturing mainly include wood dust, formaldehyde, phenol, ammonia, noise, terpene, microorganisms, etc. The exposure is complex with multiple factors accompanied or coexisted. In the production process, these factors are exceeded, and mass occupational disease hazard events occurred among workers. Exposure to wood dust, formaldehyde, terpene, etc., put workers at increased risk of cancer. This article provides a review of this issue in order to provide a scientific basis for the prevention and control of occupational disease hazards in plywood manufacturing.
Humans ; Wood/chemistry* ; Occupational Diseases/chemically induced* ; Formaldehyde/adverse effects* ; Terpenes ; Dust ; Occupational Exposure/adverse effects*

Concrete is the most widely used modern building material. It is easy to crack under the action of stress, which makes the concrete structure permeable, affecting the durability and integrity of the structure, and thus shortening its service life. Microbial in-situ remediation technology is a low cost, effective and green way for concrete crack repairing. Due to its excellent biocompatibility, service life elongation, economic losses and environmental pollution reduction, microbial in-situ remediation technology has been intensively investigated. Bacillus has attracted much attention because of its excellent biomineralization ability, extremely strong environmental tolerance and long-term survival ability of its spores. In order to promote the research, development and large-scale application of microbial in-situ healing of concrete, the paper reviews the mechanism of spore-based in-situ healing of concrete, the survival of spores exposed in concrete, the influence of spores and external additives on the mechanical properties of concrete, progress in research and development of healing agent as well as healing effects. Moreover, future research focuses such as improving the survival ability of spores in the harsh environment of concrete, reducing the influence of external additives on the mechanical properties of concrete, and strengthening the healing effect of actual field applications are also summarized.
Bacillus ; Calcium Carbonate ; Construction Materials ; Spores, Bacterial ; Technology

Dermoscopy ; Diagnosis, Differential ; Face ; Humans ; Nevus, Pigmented ; Skin Neoplasms/diagnostic imaging* ; Wood

Dissolving pulp consists of high purity cellulose and is widely used to as raw materials for the production of regenerated cellulose fiber, cellulose ester and cellulose ether. The characteristic of dissolving pulp affects greatly the production and processing performance of subsequent products. The α-cellulose content, hemicellulose content, pulp viscosity, ash, transition metal ion content, fiber morphology, molecular weight distribution of cellulose and the reactivity are the important properties. Because of its green, mild and high efficiency, the application of enzymes in improving the properties of dissolving pulp has a promising application prospect and has been researched significantly. In this review, the main properties of dissolving pulp are presented first, followed by a recommendation of the enzymes to improve these properties. The application and current research of cellulase and xylanase in improving the properties of dissolving pulp are emphasized. The main problems and the future research areas in improving the properties of dissolving pulp by enzymes are revealed. Finally, the technology prospects in this field are proposed.
Cellulase ; Molecular Weight ; Viscosity ; Wood

In order to confirm the tradition that bolting Saposhnikoviae Radix could not be used as medicine,the content of four chromone components in the cortex and wood of Saposhnikoviae Radix was analyzed by high performance liquid chromatography( HPLC),and the chemical fingerprints were established,12 common peaks were calibrated. The similarity analysis found that the similarity between batches was 0. 115-0. 995,it indicates that the cortex and wood of Saposhnikoviae Radix have certain differences. On this basis,systematic clustering analysis,principal component analysis and orthogonal partial least squares discriminant analysis were carried out with the content of four chromone components and whether they met the pharmacopoeia criteria as the original variables. The results showed that the content of the four components in the cortex of Saposhnikoviae Radix was much higher than that in the wood,and the four components detected were able to distinguish the cortex and the wood of Saposhnikoviae Radix. The results of the study reveal the tradition that bolting Saposhnikoviae Radix should not be used as medicine dut to decreased quality.
Apiaceae/chemistry* ; Chromatography, High Pressure Liquid ; Drugs, Chinese Herbal/chemistry* ; Ketones/analysis* ; Plant Roots/chemistry* ; Wood/chemistry*

Agarwood is a traditional and precious medicinal material and natural spice in China and other southeast Asian countries.As the head of all spices,agarwood has many pharmacological activities such as analgesia,antidiarrheal,anti-inflammatory and antibacterial effects. Due to its high price and scarce resources,there were just a few previous studies on it,mainly focusing on the chemical compositions of the agarwood essential oil and solvent extract mixture. The components of agarwood oils obtained by supercritical extraction and steam distillation were analyzed by using Gas Chromatography-Mass Spectrometer( GC-MS),and then the agarwood oils compositions and contents were compared between the traditional extraction method and the recently emerging supercritical extraction method. Antioxidant experiments of scavenging DPPH,ABTS,hydroxyl radical,total reducing power and MIC experiments of five kinds of tester strains such as staphylococcus aureus were combined to illustrate the differences between these two kinds of agarwood oils in terms of antioxidant and bacteriostatic activities. The results showed that the main components of agarwood oil were sesquiterpenoids( 68. 68%) in steam distillation extraction method,but sesquiterpenoids( 23. 78%) and chromones( 29. 42%) in supercritical extraction method. Fourteen common components included benzyl acetone,α-santalol,γ-eudesmol,agarospirol and guaiol etc. The antioxidant activity and inhibitory MIC of agarwood oils in supercritical extraction method were better than those in steam distillation method,and the inhibitory effect of agarwood oil on the growth of bacillus subtilis was found for the first time.
Anti-Bacterial Agents/pharmacology* ; Antioxidants/pharmacology* ; China ; Distillation/methods* ; Oils, Volatile/pharmacology* ; Plant Oils/pharmacology* ; Steam ; Thymelaeaceae/chemistry* ; Wood/chemistry*

Radon is a naturally occurring radioactive material formed by the slow decay of uranium and thorium found in the earth's crust or construction materials. Internal exposure to radon accounts for about half of the natural background radiation dose to which humans are exposed annually. Radon is a carcinogen and is the second leading cause of lung cancer following smoking. An association between radon and lung cancer has been consistently reported in epidemiological studies on mine workers and the general population with indoor radon exposure. However, associations have not been clearly established between radon and other diseases, such as leukemia and thyroid cancer. Radiation doses are assessed by applying specific dose conversion coefficients according to the source (e.g., radon or thoron) and form of exposure (e.g., internal or external). However, regardless of the source or form of exposure, the effects of a given estimated dose on human health are identical, assuming that individuals have the same sensitivity to radiation. Recently, radiation exceeding the annual dose limit of the general population (1 mSv/yr) was detected in bed mattresses produced by D company due to the use of a monazite-based anion powder containing uranium and thorium. This has sparked concerns about the health hazards for mattress users caused by radiation exposure. In light of this event, this study presents scientific information about the assessment of radon and thoron exposure and its human implications for human health, which have emerged as a recent topic of interest and debate in society.
Background Radiation ; Beds ; Carcinogens ; Construction Materials ; Epidemiologic Studies ; Humans ; Korea ; Leukemia ; Lung Neoplasms ; Miners ; Radiation Exposure ; Radon ; Smoke ; Smoking ; Thorium ; Thyroid Neoplasms ; Uranium

Two sesquiterpenes were isolated from the agarwood originating from Gyrinops salicifolia with various chromatographic techniques, and their structures were determined as 12-hydroxy-dihydrocyperolone(1) and(rel)-4β,5β,7β-eremophil-9-en-12,8α-olide(2), through a combined analysis of physicochemical properties and spectroscopic evidence. Compound 1 was a new compound. Compound 2 showed cytotoxicities against K562 and BEL-7401 cell lines, with IC_(50) values of(17.85±0.04) and(21.82±0.07) mg·L~(-1), respectively [taxol as positive control, with IC_(50) values of(1.97±0.11) and(6.31±0.08) mg·L~(-1)].
Antineoplastic Agents, Phytogenic ; isolation & purification ; pharmacology ; Cell Line, Tumor ; Humans ; Molecular Structure ; Phytochemicals ; isolation & purification ; pharmacology ; Sesquiterpenes ; isolation & purification ; pharmacology ; Thymelaeaceae ; chemistry ; Wood ; chemistry