1.Multiple applications of metal-organic framework materials in bone tissue engineering and orthopedic disease treatment
Yunxiang LIU ; Xiaoyu ZHANG ; Hao LI ; Rong ZHANG ; Liping LI ; Chongwei CHEN
Chinese Journal of Tissue Engineering Research 2025;29(10):2151-2161
BACKGROUND:Metal-organic frameworks exhibited great potential for bone tissue engineering and bone disease treatment because of its unique merits including tunable porosity,a large specific surface area,good biocompatibility,and easy structure modification. OBJECTIVE:To review the advancements,application,strengths,and weaknesses of metal-organic framework materials in bone repair,arthritis,bone infection,and bone tumors,offering guidance and strategies for future research. METHODS:Web of Science,PubMed,and CNKI databases were searched using Chinese and English keywords"metal-organic frameworks,MOFs,orthopedics,bone repair,bone regeneration,orthopaedic applications,bone tissue engineering,bone infection,arthritis,bone tumor,osteosarcoma"for related literature published from 2015 to 2023.Following initial screening based on inclusion and exclusion criteria,72 articles were finally included for review. RESULTS AND CONCLUSION:(1)During bone repair,metal ions of metal-organic frameworks can induce bone formation by activating specific signaling pathways,which include stimulating osteogenic gene expression,inhibiting osteoclasts,encouraging blood vessel formation,and speeding up bone mineralization.Hence,metal-organic frameworks with metals like calcium,strontium,cobalt,copper,and magnesium ions show significant potential in enhancing bone implant performance.(2)Metal-organic framework materials,especially zinc/cobalt-based metal-organic frameworks,exhibit enzyme-like activities and promote cartilage regeneration by scavenging reactive oxygen species.Compared with natural enzymes,it has the advantages of not easy inactivation and better stability.(3)Zinc-based metal-organic framework materials characterized with wide band gaps,efficient separation and migration of photogenerated carriers,and high stability,the enhancement of photocatalytic activity results from enhancing the excited electron-hole widely used for the eradication of bacteria and tumor cells.(4)Bimetallic metal-organic frameworks,the doping of additional metals,showed critical advantages in optimizing structural performance,such as zinc/magnesium-based metal-organic framework 74 offering increased stability for durable antibacterial activity,and the light absorption capacity and photocatalytic efficiency of tantalum/zirconium-based metal-organic framework greatly improved and thus enhancing the radiation therapy.(5)However,metal-organic framework materials still face challenges in clinical applications,such as the uncertainty of drug release,in vivo safety,and potential immune responses from long-term presence.
2.Establishment of a method for detecting the potency of recombinant human coagulation factor Ⅶa for injection
Rong WU ; Liping WANG ; Jinye LANG ; Yue ZHU ; Jing ZHOU ; Xun LIU ; Jing NI ; Shunbo ZHOU ; Yaling DING
Chinese Journal of Blood Transfusion 2025;38(3):415-420
[Objective] To establish a method for detecting the potency of recombinant human coagulation factor Ⅶa for injection. [Methods] By adding the sample and factor Ⅶ deficient plasma to the sample cup and activating the reaction with prothrombin time assay reagent (PT reagent), the coagulation time of the sample was determined by the change in magnetic bead swing amplitude in the sample cup. The logarithm of coagulation time was inversely proportional to the logarithm of human factor Ⅶa potency. [Results] Under the experimental conditions, the specificity of the methodology was evaluated through spiked recovery, and the recovery rates ranged from 90.0% to 110.0%. Within the range from 0.125 to 1.000 IU/mL, there was a good linear response between the potency and coagulation time of the standard and sample, with correlation coefficients r>0.99. As for the accuracy and repeatability, the recovery rates of various concentrations detected in the stock solution were 101.0%, 100.0% and 112.0%, respectively, with RSD values of 2.6%, 4.0% and 0.0%, respectively. The recovery rates of various concentrations in finished product testing were 104.0%, 94.7% and 112.0%, respectively, with RSD values of 1.9%, 2.4% and 0.0%, respectively. As for the intermediate precision, the RSD were 4.5% and 3.7%, respectively. After treated with sample diluent, the sample was tested at room temperature for 6 hours and still exhibited relatively stable biological activity. [Conclusion] This detection method is accurate, stable, easy to operate and highly automated, and is suitable for detecting the potency of recombinant human coagulation factor Ⅶa for Injection.
3.Measles, rubella, and mumps antibody seroprevalence among the children aged 18 years and younger in Karamay City, Xinjiang Uygur Autonomous Region
Meili WU ; Xia LI ; Ling ZUO ; Liping RONG ; Jing WANG ; Feng WANG
Shanghai Journal of Preventive Medicine 2025;37(3):239-243
ObjectiveTo understand the measles, rubella, and mumps antibody seroprevalence among the children aged 18 years and younger in Karamay City, and to evaluate the effectiveness of vaccination. MethodsA stratified whole cluster random sampling method was used to investigate the antibody seroprevalence of measles, rubella, and mumps among the healthy children aged 18 years and younger in Karamay City, and to further analyze the positive antibody rates and the geometric mean concentration (GMC) of antibodies. ResultsA total of 620 people were investigated, and the positive rates of IgG to measles, rubella, and mumps were 72.74%,62.26%, and 86.45%, respectively, with a GMC of308.94 mIU·mL-1, 21.81 mIU·mL-1, and 249.10 U·mL-1. There were statistically significant differences in the positive rates of antibodies to measles, rubella, and mumps among different age groups (χ2measles=76.707, P<0.001; χ2rubella=60.804, P<0.001; χ2mumps=35.407, P<0.001). The differences in positive rates were statistically significant among individuals with different intervals from the time of their last dose vaccination (χ2measles=60.533, P<0.001; χ2rubella=46.331, P<0.001; χ2mumps=22.825, P<0.001). ConclusionThe antibody levels of measles, rubella and mumps among the people aged 18 years and younger in Karamay City are found to be low. Two doses of measles-mumps-rubella (MMR) vaccine should be given to children born before 2020, and if necessary, supplementary immunization with MMR vaccine should be carried out before they are enrolled in nursery and kindergarten. Additionally, regular population-based antibody surveillance should be conducted to promptly identify the people with weak immunity, which is conducive to effectively reducing and controlling the epidemic situation of measles, rubella and mumps in schools.
4.Effectiveness of free fascia lata flap assisted by indocyanine green angiography in treatment of Myerson type Ⅱ and Ⅲ chronic Achilles tendon ruptures.
Liping GUO ; Rong ZHOU ; Jihui JU ; Guangzhe JIN ; Liang YANG ; Chao GENG
Chinese Journal of Reparative and Reconstructive Surgery 2025;39(5):620-627
OBJECTIVE:
To investigate of effectiveness of free fascia lata flap assisted by indocyanine green angiography (ICGA) in treatment of Myerson type Ⅱ and Ⅲ chronic Achilles tendon ruptures.
METHODS:
A clinical data of 14 patients with Myerson type Ⅱ and Ⅲ chronic Achilles tendon ruptures between March 2020 and June 2024 was retrospectively analyzed. All Achilles tendon defects were repaired with the free fascia lata assisted by ICGA during operation. There were 12 males and 2 females with an average age of 45.4 years (range, 26-71 years). The causes of Achilles tendon rupture included sports injury in 10 cases, Achilles tendon-related tendinopathy in 3 cases, and glass laceration injury in 1 case. The time from Achilles tendon rupture to operation was 4-40 weeks (median, 4.5 weeks). Preoperative MRI examination showed that the defect length of the Achilles tendon was 2-5 cm (mean, 3.2 cm). The operation time and intraoperative blood loss were recorded. The color Doppler ultrasound (CDU) and MRI were taken to observe the foot blood vessels and the tendon healing. The visual analogue scale (VAS) score, American Orthopaedic Foot and Ankle Society (AOFAS) score, Achilles Tendon rupture score (ATRS), and range of motion of the ankle joint were used to estimate the pain and function of ankle joint.
RESULTS:
All operations of the 14 patients were successfully completed. The operation time ranged from 3.00 to 4.50 hours (mean, 3.60 hours). The intraoperative blood loss ranged from 10 to 50 mL (mean, 36.4 mL). After operation, 1 patient had exudation at the recipient site, which healed after dressing change; the other incisions healed by first intention. All incisions at the donor sites healed by first intention. All patients were followed up 6-36 months (mean, 11.4 months). The CDU of the foot at 1 month after operation showed that the blood flow signal of the perforating vessels of the fascia lata flap was clear. The ankle MRI at 2 months after operation showed the good continuity of the Achilles tendon. No complication such as the Achilles tendon re-rupture, ankle stiffness, or scar contracture occurred during follow-up. Compared with preoperative score, the AOFAS score, ATRS score, and plantar flexion range of motion significantly increased at 1, 3, and 6 months after operation ( P<0.05), while the VAS score and dorsiflexion range of motion significantly decreased ( P<0.05). The AOFAS score, ATRS score, and VAS score at 3 and 6 months further improved when compared with those at 1 month ( P<0.05); however, there was no significant difference in the range of motion of the ankle joint ( P>0.05). There was no significant difference in above indicators between 3 and 6 months after operation ( P>0.05).
CONCLUSION
The treatment of Myerson type Ⅱ and Ⅲ chronic Achilles tendon ruptures with free fascia lata flaps under the guidance of ICGA has the advantages of precise design, fast healing, and a wide range of adaptability.
Humans
;
Achilles Tendon/diagnostic imaging*
;
Male
;
Female
;
Adult
;
Middle Aged
;
Retrospective Studies
;
Indocyanine Green
;
Rupture/surgery*
;
Aged
;
Fascia Lata/transplantation*
;
Angiography/methods*
;
Free Tissue Flaps/blood supply*
;
Plastic Surgery Procedures/methods*
;
Tendon Injuries/diagnostic imaging*
;
Treatment Outcome
;
Chronic Disease
5.Effectiveness of three-dimensional printing-assisted vascularized fibular graft for repairing metatarsal defects.
Rong ZHOU ; Jihui JU ; Liang YANG ; Liping GUO ; Yucheng LIU ; Chao GENG ; Zhongzheng LIU ; Zefeng NIU ; Shuai DONG
Chinese Journal of Reparative and Reconstructive Surgery 2025;39(11):1447-1451
OBJECITVE:
To investigate the effectiveness of three-dimensional (3D) printing-assisted vascularized fibular graft for repairing metatarsal defects.
METHODS:
Between November 2021 and February 2024, 11 patients with varying degrees of metatarsal defects caused by trauma were treated. There were 10 males and 1 female, aged 22-67 years, with a mean age of 51.2 years. The defect locations were as follows: the first metatarsal in 4 cases, the fifth metatarsal in 2 cases, the first and the second metatarsals in 1 case, the first to third metatarsals in 1 case, the third and the fourth metatarsals in 1 case, the third to fifth metatarsals in 1 case, and the first to fifth metatarsals in 1 case. The preoperative American Orthopaedic Foot & Ankle Society (AOFAS) score was 67.0 (48.5, 72.5). Based on 3D-printed bilateral feet models and mirrored healthy-side foot arch angles for preoperative planning and design, the vascularized fibular graft was performed to repair the metatarsal defects. At last follow-up, the medial and lateral longitudinal arches of bilateral feet were measured on weight-bearing X-ray films, and functional assessment was conducted using the AOFAS score.
RESULTS:
All operations were successfully completed, with an operation time ranging from 180 to 465 minutes (mean, 246.8 minutes). All incisions healed by first intention, with no occurrence of osteomyelitis. All patients were followed up 6-22 months (mean, 10 months). X-ray film reviews showed bone graft healing in all cases, with a healing time of 3-6 months (mean, 5 months). All patients underwent internal fixator removal at 6-12 months after operation. At last follow-up, no significant difference was observed in the medial and lateral longitudinal arches between the healthy and affected feet ( P>0.05). The AOFAS score of the affected foot was 78.0 (73.5, 84.0), showing a significant improvement compared to the preoperative score ( P<0.05). The effectiveness was rated as excellent in 1 case, good in 7 cases, fair in 2 cases, and poor in 1 case. Linear scarring remained at the donor site, with no functional impairment in adjacent joint movement.
CONCLUSION
3D printing-assisted vascularized fibular graft for repairing metatarsal defects can effectively restore the physiological angle of the foot arch, facilitate the recovery of weight-bearing alignment, promote good bone healing, and yield satisfactory clinical outcomes.
Humans
;
Printing, Three-Dimensional
;
Middle Aged
;
Male
;
Fibula/blood supply*
;
Female
;
Metatarsal Bones/injuries*
;
Adult
;
Bone Transplantation/methods*
;
Aged
;
Plastic Surgery Procedures/methods*
;
Young Adult
;
Treatment Outcome
6.Effect of Qufu Shengji ointment combined with ulinastatin on postoperative wound healing and inflammatory factor levels in perianal surgery
Ming LU ; Ke WU ; Liping MO ; Guihong RONG ; Bo CHEN ; Haining HUANG ; Bingfen QIN
China Pharmacist 2024;27(1):117-124
Objective To investigate the effect of Qufu Shengji ointment combined with ulinastatin in the treatment of wound healing after perianal surgery and its effect on the level of inflammatory factors.Methods Patients who underwent perianal surgery in Guilin Hospital of Integrated Traditional Chinese and Western Medicine from July 2020 to January 2022 were randomly divided into control group and test group.The patients in both groups were treated with conventional debridement therapy and ulinastatin,and the test group was treated with Qufu Shengji ointment.The wound healing efficacy,TCM symptom score,inflammatory factor level,growth factor level and treatment safety of the two groups were compared.Results A total of 116 patients were included in the study,including 58 patients in the test group and 58 in the control group.The total effective rate of the test group(91.38%)was higher than that of the control group(75.86%),and the difference was statistically significant(P<0.05).After treatment,the TCM syndrome score levels of interleukin-17A(IL-17A),C-reactive protein(CRP)and serum amyloid A(SAA)in the test group were lower than those in the control group(P<0.05).The levels of vascular endothelial growth factor receptor 1(VEGFR1),fibroblast growth factor receptor(FGFR)and transforming growth factor-β1(TGF-β1)were higher than those in the control group(P<0.05).The anal function index was higher than that of the control group(P<0.05).The incidence of adverse reactions between the two groups was 13.79%and 8.62%,respectively,and the difference was not statistically significant(P>0.05).Conclusion The effect of Qufu Shengji ointment combined with ulinastatin in the treatment of wound healing after perianal surgery is significant,which can improve the TCM syndrome,reduce inflammatory factors,and upregulate growth factors,and has good safety.
7.Treatment status of tyrosine kinase inhibitor for newly-diagnosed chronic myeloid leukemia: a domestic multi-centre retrospective real-world study
Xiaoshuai ZHANG ; Bingcheng LIU ; Xin DU ; Yanli ZHANG ; Na XU ; Xiaoli LIU ; Weiming LI ; Hai LIN ; Rong LIANG ; Chunyan CHEN ; Jian HUANG ; Yunfan YANG ; Huanling ZHU ; Ling PAN ; Xiaodong WANG ; Guohui LI ; Zhuogang LIU ; Yanqing ZHANG ; Zhenfang LIU ; Jianda HU ; Chunshui LIU ; Fei LI ; Wei YANG ; Li MENG ; Yanqiu HAN ; Li'e LIN ; Zhenyu ZHAO ; Chuanqing TU ; Caifeng ZHENG ; Yanliang BAI ; Zeping ZHOU ; Suning CHEN ; Huiying QIU ; Lijie YANG ; Xiuli SUN ; Hui SUN ; Li ZHOU ; Zelin LIU ; Danyu WANG ; Jianxin GUO ; Liping PANG ; Qingshu ZENG ; Xiaohui SUO ; Weihua ZHANG ; Yuanjun ZHENG ; Qian JIANG
Chinese Journal of Hematology 2024;45(3):215-224
Objective:To retrospectively analyze the treatment status of tyrosine kinase inhibitors (TKI) in newly diagnosed patients with chronic myeloid leukemia (CML) in China.Methods:Data of chronic phase (CP) and accelerated phase (AP) CML patients diagnosed from January 2006 to December 2022 from 77 centers, ≥18 years old, and receiving initial imatinib, nilotinib, dasatinib or flumatinib-therapy within 6 months after diagnosis in China with complete data were retrospectively interrogated. The choice of initial TKI, current TKI medications, treatment switch and reasons, treatment responses and outcomes as well as the variables associated with them were analyzed.Results:6 893 patients in CP ( n=6 453, 93.6%) or AP ( n=440, 6.4%) receiving initial imatinib ( n=4 906, 71.2%), nilotinib ( n=1 157, 16.8%), dasatinib ( n=298, 4.3%) or flumatinib ( n=532, 7.2%) -therapy. With the median follow-up of 43 ( IQR 22-75) months, 1 581 (22.9%) patients switched TKI due to resistance ( n=1 055, 15.3%), intolerance ( n=248, 3.6%), pursuit of better efficacy ( n=168, 2.4%), economic or other reasons ( n=110, 1.6%). The frequency of switching TKI in AP patients was significantly-higher than that in CP patients (44.1% vs 21.5%, P<0.001), and more AP patients switched TKI due to resistance than CP patients (75.3% vs 66.1%, P=0.011). Multi-variable analyses showed that male, lower HGB concentration and ELTS intermediate/high-risk cohort were associated with lower cytogenetic and molecular responses rate and poor outcomes in CP patients; higher WBC count and initial the second-generation TKI treatment, the higher response rates; Ph + ACA at diagnosis, poor PFS. However, Sokal intermediate/high-risk cohort was only significantly-associated with lower CCyR and MMR rates and the poor PFS. Lower HGB concentration and larger spleen size were significantly-associated with the lower cytogenetic and molecular response rates in AP patients; initial the second-generation TKI treatment, the higher treatment response rates; lower PLT count, higher blasts and Ph + ACA, poorer TFS; Ph + ACA, poorer OS. Conclusion:At present, the vast majority of newly-diagnosed CML-CP or AP patients could benefit from TKI treatment in the long term with the good treatment responses and survival outcomes.
8.Measurement and evaluation of personal attenuation rating before and after the training of the noise-exposed workers wearing foam earplugs
Jing LIU ; Xian WANG ; Rong ZHANG ; Youhong BAO ; Kaifeng GU ; Liping PAN
Chinese Journal of Industrial Hygiene and Occupational Diseases 2024;42(8):589-593
Objective:To measure and compare the difference of personal attenuation rating (PAR) of the workers wearing foam earplugs before and after the training, and to evaluate the effect of ear protector wearing training on the noise protection.Methods:In February 2023, 94 workers exposed to noise in a machinery manufacturing factory were selected as subjects. The production noise in the workplace was measured and subjects were trained to wear earplugs. The PAR values of wearing 3M 1110 foam test earplugs were measured and recorded before and after the training by using the fit testing of hearing protection device. The differences between the actual PAR values with nominal values and the noise attenuation values in related standards were compared, and the protective effect of hearing protection device before and after training was evaluated.Results:The average age of the subjects was (36.76±11.48) years old, the average length of service was (16.34±11.64) years, and the average exposure time to noise was (15.67±11.64) years. The noise detection results of the subjects' posts were ranged from 80.1 to 94.3 dB (A). The results of subjects wore 3M 1110 foam test earplugs for fit testing showed that the binaural PAR value after training was (19.3±6.4) dB (A), which was significantly higher than that before training (11.1±7.4) dB (A) ( t=13.31, P<0.001). After training, 11 people (11.70%) could reach the corrected noise reduction value (NRR value), 26 people (27.66%) could reach the standard of single noise reduction value (SNR value) ×0.6, and 84 people (89.36%) could reach the standard of (NRR-7) /2. The under protection rate of hearing protectors after training (7.45%) was significantly lower than that before training (45.74%), and the difference of different protection levels before and after training was statistically significant (χ 2=40.83, P<0.001) . Conclusion:It is suggested that enterprises should use the fit testing instead of nominal value estimation to evaluate the noise reduction effect of hearing protection device. Special training on the selection and use of hearing protection device should be strengthened, so as to ensure that workers wear them correctly and improve the protective effect of hearing protection device.
9.Tenecteplase versus alteplase in treatment of acute ST-segment elevation myocardial infarction: A randomized non-inferiority trial
Xingshan ZHAO ; Yidan ZHU ; Zheng ZHANG ; Guizhou TAO ; Haiyan XU ; Guanchang CHENG ; Wen GAO ; Liping MA ; Liping QI ; Xiaoyan YAN ; Haibo WANG ; Qingde XIA ; Yuwang YANG ; Wanke LI ; Juwen RONG ; Limei WANG ; Yutian DING ; Qiang GUO ; Wanjun DANG ; Chen YAO ; Qin YANG ; Runlin GAO ; Yangfeng WU ; Shubin QIAO
Chinese Medical Journal 2024;137(3):312-319
Background::A phase II trial on recombinant human tenecteplase tissue-type plasminogen activator (rhTNK-tPA) has previously shown its preliminary efficacy in ST elevation myocardial infarction (STEMI) patients. This study was designed as a pivotal postmarketing trial to compare its efficacy and safety with rrecombinant human tissue-type plasminogen activator alteplase (rt-PA) in Chinese patients with STEMI.Methods::In this multicenter, randomized, open-label, non-inferiority trial, patients with acute STEMI were randomly assigned (1:1) to receive an intravenous bolus of 16 mg rhTNK-tPA or an intravenous bolus of 8 mg rt-PA followed by an infusion of 42 mg in 90 min. The primary endpoint was recanalization defined by thrombolysis in myocardial infarction (TIMI) flow grade 2 or 3. The secondary endpoint was clinically justified recanalization. Other endpoints included 30-day major adverse cardiovascular and cerebrovascular events (MACCEs) and safety endpoints.Results::From July 2016 to September 2019, 767 eligible patients were randomly assigned to receive rhTNK-tPA ( n = 384) or rt-PA ( n = 383). Among them, 369 patients had coronary angiography data on TIMI flow, and 711 patients had data on clinically justified recanalization. Both used a –15% difference as the non-inferiority efficacy margin. In comparison to rt-PA, both the proportion of patients with TIMI grade 2 or 3 flow (78.3% [148/189] vs. 81.7% [147/180]; differences: –3.4%; 95% confidence interval [CI]: –11.5%, 4.8%) and clinically justified recanalization (85.4% [305/357] vs. 85.9% [304/354]; difference: –0.5%; 95% CI: –5.6%, 4.7%) in the rhTNK-tPA group were non-inferior. The occurrence of 30-day MACCEs (10.2% [39/384] vs. 11.0% [42/383]; hazard ratio: 0.96; 95% CI: 0.61, 1.50) did not differ significantly between groups. No safety outcomes significantly differed between groups. Conclusion::rhTNK-tPA was non-inferior to rt-PA in the effect of improving recanalization of the infarct-related artery, a validated surrogate of clinical outcomes, among Chinese patients with acute STEMI.Trial registration::www.ClinicalTrials.gov (No. NCT02835534).
10.Measurement and evaluation of personal attenuation rating before and after the training of the noise-exposed workers wearing foam earplugs
Jing LIU ; Xian WANG ; Rong ZHANG ; Youhong BAO ; Kaifeng GU ; Liping PAN
Chinese Journal of Industrial Hygiene and Occupational Diseases 2024;42(8):589-593
Objective:To measure and compare the difference of personal attenuation rating (PAR) of the workers wearing foam earplugs before and after the training, and to evaluate the effect of ear protector wearing training on the noise protection.Methods:In February 2023, 94 workers exposed to noise in a machinery manufacturing factory were selected as subjects. The production noise in the workplace was measured and subjects were trained to wear earplugs. The PAR values of wearing 3M 1110 foam test earplugs were measured and recorded before and after the training by using the fit testing of hearing protection device. The differences between the actual PAR values with nominal values and the noise attenuation values in related standards were compared, and the protective effect of hearing protection device before and after training was evaluated.Results:The average age of the subjects was (36.76±11.48) years old, the average length of service was (16.34±11.64) years, and the average exposure time to noise was (15.67±11.64) years. The noise detection results of the subjects' posts were ranged from 80.1 to 94.3 dB (A). The results of subjects wore 3M 1110 foam test earplugs for fit testing showed that the binaural PAR value after training was (19.3±6.4) dB (A), which was significantly higher than that before training (11.1±7.4) dB (A) ( t=13.31, P<0.001). After training, 11 people (11.70%) could reach the corrected noise reduction value (NRR value), 26 people (27.66%) could reach the standard of single noise reduction value (SNR value) ×0.6, and 84 people (89.36%) could reach the standard of (NRR-7) /2. The under protection rate of hearing protectors after training (7.45%) was significantly lower than that before training (45.74%), and the difference of different protection levels before and after training was statistically significant (χ 2=40.83, P<0.001) . Conclusion:It is suggested that enterprises should use the fit testing instead of nominal value estimation to evaluate the noise reduction effect of hearing protection device. Special training on the selection and use of hearing protection device should be strengthened, so as to ensure that workers wear them correctly and improve the protective effect of hearing protection device.

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