It is very limited that the benefit of perioperative chemotherapy in early non-small cell lung cancer (NSCLC), and the 5-year survival rate is only 5% higher than surgery. Antibodies that block programmed cell death protein 1/programmed death-ligand 1 significantly improve the survival of advanced NSCLC. The value of immunotherapy in early NSCLC is also being explored. This paper firstly summarized and analyzed the progress of immunotherapy in the perioperative period of NSCLC. Secondly, the safety and feasibility of surgical resection after neoadjuvant immunotherapy were discussed. Finally, the clinical value of different therapeutic efficacy prediction indicators was summarized, in order to clarify the current status of immunotherapy in the perioperative period, so as to improve the clinical benefits of early NSCLC patients.

This article systematically analyzed the historical evolution of the origin， scientific name， producing area， quality evaluation， harvesting and processing， and other aspects of Quisqualis Fructus by consulting the ancient materia medica， medical books， prescription books， local literature and combining with the modern literature and standards， summarized and explored the development rules of its medicinal properties and efficacy along with their underlying causes， in order to provide support for the development and utilization of famous classical formulas containing this herb. According to the textual research， Shijunzi was first recorded as Liuqiuzi in Nanfang Caomuzhuang of the Jin dynasty， and the name of Shijunzi was first used in Kaibao Bencao of the Song dynasty， which has been consistently used throughout subsequent dynasties， and there were also aliases such as Junziren， Sijunzi， and Dujilizi. The mainstream source of Quisqualis Fructus used in the past dynasties has been the dried mature fruits of Quisqualis indica， a plant belonging to the family Combretaceae. In modern times， its variety Q. indica var. villosa has also been recorded as the medicinal material of Quisqualis Fructus. In 2007， the Flora of China（English edition） designated Q. indica var. villosa as a synonym of Q. indica. Today， the accepted name of Shijunzi is updated to Combretum indicum. According to ancient herbal records， the producing areas of Quisqualis Fructus were Guangdong， Hong Kong， Macao， Guangxi， Hainan， Sichuan and Fujian， and then gradually expanded to Yunnan， Taiwan， Jiangxi and Guizhou. Since the Song dynasty， two major production regions have gradually emerged in Sichuan， Chongqing and Fujian. Currently， it is primarily cultivated in Chongqing， Guangxi and other areas， with Chongqing yielding the highest output. Since modern times， superior quality has been defined by large size， a purple-black surface， plump grains， and a yellowish-white kernel. According to ancient herbal records， the harvesting period of Quisqualis Fructus was the July and August of the lunar calendar， mostly used raw after shelling or with the shell intact， it underwent processing methods such as cleaning， slicing， mixing， steaming， roasting， stewing， and frying. Currently， the harvesting period is autumn， followed by sun-drying or low-heat drying， with processing methods including cleaning， stir-frying， and stewing. In ancient and modern literature， the records of the properties， functions and indications of Quisqualis Fructus are basically the same， that is， sweet in taste， warm in nature， predominantly non-toxic， belonging to the spleen and stomach meridians. It possesses effects of insecticide， decontamination and invigorating spleen for ascariasis， enterobiasis， abdominal pain due to worm accumulation and infantile malnutrition.The contraindications for use primarily include avoiding consumption by individuals without parasitic infestations， limiting use for those with spleen-stomach deficiency-cold， refraining from drinking hot tea during medication， and avoiding excessive intake. Based on the textual research， it is suggested that the dried mature fruits of Q. indica should be used as the medicinal material for the development of famous classical formulas containing Quisqualis Fructus. Processing methods may be chosen according to prescription requirements， and the raw products is recommended for medicinal use if not specified.

ObjectiveTo integrate network pharmacology prediction with multi-level experimental verification methods， and to explore in depth the therapeutic efficacy and potential mechanism of luteolin in treating gout. MethodsDatabases were used to obtain potential pharmacodynamic targets of luteolin. Protein-protein interaction （PPI） network construction and network pharmacology analysis techniques were used to screen key core targets of luteolin in gout treatment. Further biological function enrichment analysis and signaling pathway analysis were performed on these targets. Molecular docking simulation was used to calculate the binding energy between luteolin and potential core targets， clarifying the strength of their interactions. In the in vivo experiment for hyperuricemia， 48 mice were randomly divided into a blank group， a model group， an allopurinol group （5 mg·kg^-1）， and low-dose （10 mg·kg^-1）， medium-dose （30 mg·kg^-1）， and high-dose （90 mg·kg^-1） luteolin groups. For the first three days， the blank and model groups were gavaged with an equal volume of normal saline， while the allopurinol group and luteolin groups were gavaged with corresponding drugs. From day 4 onwards， modeling was performed by intraperitoneal injection at 12：00 daily （normal saline for the blank group， and oxonic acid potassium-hypoxanthine mixture for other groups， with 300 mg·kg^-1 for each group）. Gavage intervention was administered at 18：00 daily （normal saline for the blank/model groups， and corresponding drugs for the treatment groups） until day 7. After sampling， levels of serum uric acid （UA）， alanine aminotransferase （ALT）， and aspartate aminotransferase （AST） were measured. Levels of xanthine oxidase （XO） in the liver and kidney， ATP-binding cassette transporter G2 （ABCG2） and malondialdehyde （MDA） in the kidney， and superoxide dismutase （SOD） in the liver were determined. Renal HE staining was also performed. In the pharmacodynamic study of gouty arthritis， 36 rats were randomly divided into a blank group， a model group， a colchicine group （0.315 mg·kg^-1）， and low-dose （7 mg·kg^-1）， medium-dose （21 mg·kg^-1）， and high-dose （63 mg·kg^-1） luteolin groups. The model was established by vertically injecting 100 µL of 25 g·L^-1 monosodium urate suspension into the posterior lateral aspect of the right ankle joint （the blank group was injected with an equal volume of normal saline）， with repeated injections every two days for reinforcement. From day 2 after modeling， daily gavage administration was performed （normal saline for the blank/model groups， and corresponding drugs for the treatment groups） for a total of 16 days. During the experiment， ankle swelling and pain threshold were measured regularly. After sampling， levels of serum tumor necrosis factor-α （TNF-α）， interleukin-6 （IL-6）， and interleukin-1β （IL-1β） were determined. Ankle joints were subjected to HE， Masson， and safranin O-fast green staining， and HE staining was also performed on ankle synovial tissue and various organs. Western blot was used to determine the expression levels of key proteins in gout-related signaling pathways. ResultsNetwork pharmacology analysis predicted that luteolin may regulate over 20 core targets， such as XO， ABCG2， nuclear factor erythroid 2-related factor 2 （Nrf2）， and SOD， through acting on signaling pathways including NF-κB， phosphoinositide 3-kinase/protein kinase B （PI3K/Akt）， and ABC transporters， thereby affecting uric acid metabolism and inflammatory responses. In the hyperuricemia model， compared with the blank group， the model group showed significantly increased serum UA level， liver and kidney XO activity， renal ABCG2 expression， and liver SOD activity （P<0.01）. Compared with the model group， the high-dose luteolin group significantly reduced serum UA level （P<0.01）， inhibited liver and kidney XO activity （P<0.01）， and significantly increased renal ABCG2 expression and liver SOD activity （P<0.01）， effectively alleviating renal oxidative stress damage and improving renal histopathological status. In the gouty arthritis model， compared with the blank group， the model group showed significant ankle swelling， decreased pain threshold， and significantly increased levels of IL-6， IL-1β， and TNF-α in serum and synovial tissue （P<0.01）. The high-dose luteolin group significantly reduced ankle swelling， prolonged hot plate pain threshold， effectively decreased the levels of the above inflammatory factors in serum and synovial tissue （P<0.01）， and significantly improved ankle pathological damage， showing good analgesic and anti-inflammatory effects. Western blot results further confirmed that luteolin significantly upregulated Nrf2 protein expression and downregulated XO and nucleotide-binding oligomerization domain （NOD）-like receptor protein 3 （NLRP3） expression in animals. ConclusionLuteolin can improve symptoms of hyperuricemia and gouty arthritis， and its potential mechanism may be related to inhibiting XO activity， increasing ABCG2 and SOD levels， and regulating Nrf2-mediated oxidative stress-related pathways.

ObjectiveThis paper aims to observe the syndrome improvement and negative antigen conversion rate of Qingxuan Daozhi formula in the treatment of influenza in children （heat accumulation in the lung and stomach syndrome）. MethodsThrough a multi-center randomized controlled methodology design，confirmed influenza cases were collected from October 2022 to April 2023 in the pediatrics department of eight hospitals，such as Dongfang Hospital of Beijing University of Chinese Medicine. A total of 180 children with influenza and heat accumulation in the lung and stomach syndrome conforming to the standard were recruited through the clinic. The sick children meeting the inclusion criteria were randomly divided into groups by a block-randomized method. The children in the experimental group were treated with Qingxuan Daozhi formula for five days，and those in the control group were treated with Oseltamivir Phosphate Granules for five days. The primary efficacy indicator was the negative conversion rate of influenza antigen detection. Secondary efficacy indicators were the Canadian acute respiratory illness and flu scale （CARIFS） and the incidence of complications，severe cases， and critical cases. Follow-up observation was conducted on the day of enrollment，48 hours after medication，72 hours after medication， and （6+1） d after medication. ResultsOne hundred and eighty participants were randomly assigned to the experimental group （90 cases） or the control group （90 cases）. All participants were followed up during the study. Comparison of influenza antigen detection results in the primary efficacy indicators showed that the average time of negative influenza antigen conversion in the experimental group was （5.29±1.25） d，and that in the control group was （5.40±1.68） d，without a statistically significant difference. After five days of intervention，52 cases in the experimental group and 51 cases in the control group converted to negative，without a statistically significant difference. CARIFS score results in the secondary efficacy indicators showed that during 72 hours after intervention，there were statistically significant differences between the experimental group and the control group in three dimensions， including headache，muscle soreness， and the need for extra care （P<0.05）. On the （6+1） days after the intervention，the differences in both the experimental group and the control group were statistically significant in 10 dimensions， including sore throat，bad sleep，uncomfortable feeling，poor spirit and fatigue，crying more than usual，the need for extra care，symptom，function，influence on parents，and total score （P<0.05）. The comparison results within the group in the dimensional scores of symptom， function， and influence on parents，as well as the CARIFS total score showed that with the delay of follow-up time，scores of both groups decreased significantly，with a statistically significant difference （P<0.01）. Inter-group comparison results showed that the mean score of the experimental group was higher than that of the control group at the time of enrollment. With the progress of intervention，the score of the experimental group was significantly decreased compared with that of the control group. At the end of follow-up，the mean score of the experimental group was lower than that of the control group，with no statistically significant difference. In terms of the incidence of complications，severe cases， and critical cases， there were no complications，severe cases， and critical cases in the two groups，without a statistically significant difference. ConclusionThe symptom improvement effect and negative antigen conversion rate of Qingxuan Daozhi formula in the treatment of influenza in children （heat accumulation in the lung and stomach syndrome） are not inferior to Oseltamivir Phosphate granules， and children's acceptance is better. It can be more widely used in clinical treatment of influenza in children （heat accumulation in the lung and stomach syndrome）.

[Objective] To investigate the implementation of emergency transfusion strategy of uncrossmatched type O suspended RBCs based on the single-center clinical practice, which is "emergency transfusion is initiated by the authorized doctor of the emergency department, and no more than 4 U of type O uncrossmatched suspended RBCs are issued within 15 minutes in the transfusion department"(referred as the Practice), so as to provide reference for blood management. [Methods] A retrospective analysis of the information of patients who received uncrossmatched type O suspended RBCs in West China Hospital of Sichuan University from August 2019 to April 2024 was conducted. The analysis included reasons for emergency blood transfusion, time of receiving transfusion application and blood distribution, total bilirubin, indirect bilirubin, lactate dehydrogenase before and after transfusion, blood group of patients, and disease outcome. [Results] From August 2019 to April 2024, 39 cases applied for emergency transfusion of type O suspended RBCs, and a total of 90 U uncrossmatched suspended RBCs were transfused. All patients were Rh(D) positive, including 14 cases of blood group A, 6 cases of blood group B, 16 cases of blood group O, 2 cases of blood group AB, one case of undetermined blood group, and 2 cases with positive antibody screening. The main cause of emergency transfusion of type O suspended RBCs was traffic accident, accounting for 46% (18/39), with a mortality rate at 51.28% (20/39). The cause of death was primary injury, and no adverse reactions were reported. There was no significant difference in total bilirubin (TBIL), indirect bilirubin (IBIL) and lactate dehydrogenase (LDH) before and after blood transfusion (P>0.05). The median duration from admission to receiving transfusion application was 30.20 minutes, and 5.30 minutes from receipt of the application to blood distribution. [Conclusion] The single-center based Practice is safe, but there is room for optimization before the link of blood transfusion application sent to the transfusion department when applying for emergency transfusion of type O suspended RBCs.

ObjectiveTo investigate the inhibitory effect of Biejia Decoction Pill on the proliferation， migration， and aerobic glycolysis of hepatocellular carcinoma （HCC） using cell experiments， as well as related mechanisms. MethodsHuman liver cancer cell line Huh7 was selected， and Sprague-Dawley rats were randomly divided into blank serum group， inhibitor group， and high-， middle-， and low-dose Biejia Decoction Pill groups. Rat serum containing the drug was prepared for the incubation of Huh7 cells. CCK8 assay and scratch assay were used to explore the effect of Biejia Decoction Pill on the proliferation and migration of HCC cells； glycolytic rate-limiting enzymes and metabolites were measured to explore the effect of Biejia Decoction Pill on aerobic glycolysis of liver cancer cells； RT-qPCR and Western blot were used to explore the effect of Biejia Decoction Pill on the mRNA expression， related proteins， and phosphorylation of the protein kinase B （AKT）/mammalian target of rapamycin （mTOR） signaling pathway. A one-way analysis of variance was used for comparison between multiple groups， and the least significant difference t-test or the Dunnett’s T3 test were used for further comparison between two groups. ResultsCompared with the blank serum group， the Biejia Decoction Pill groups had significant reductions in OD value， migration rate during different periods of time， glycolytic rate-limiting enzymes （hexokinase， phosphofructokinase， pyruvate kinase）， and glycolytic metabolites （pyruvate， lactic acid， ATP） （all P<0.05）. RT-qPCR results showed that compared with the blank serum group， the high-， middle-， and low-dose Biejia Decoction Pill groups had a significant reduction in the mRNA expression level of mTOR， and the high- and low-dose Biejia Decoction Pill groups had a significant reduction in the mRNA expression level of AKT （all P<0.05）. Western blot results showed that compared with the blank serum group， the high-， middle-， and low-dose Biejia Decoction Pill groups had significant reductions in the expression levels of mTOR-related proteins and phosphorylated proteins， and the high- and middle-dose Biejia Decoction Pill groups had significant reductions in the expression levels of AKT-related proteins and phosphorylated proteins （all P<0.05）. ConclusionThis study preliminarily verifies that the serum containing Bijia Decoction Pill can inhibit the aerobic glycolysis of human hepatoma Huh7 cells， thereby inhibiting their proliferation and migration， possibly by inhibiting the expression of the proteins related to the AKT/mTOR signaling pathway.

BACKGROUND:With the continuous progress of science and technology,the introduction of new technologies and methods will bring more possibilities and new breakthroughs for the application of shape memory alloys in the fields of assistive and rehabilitation. OBJECTIVE:To review the application status of shape memory alloys in assistive and rehabilitation equipment,discuss their main methods,techniques and results,summarize and put forward suggestions,hoping that shape memory alloys can be continuously optimized and bring more new changes for the development of assistive and rehabilitation equipment. METHODS:WanFang,PubMed,and Web of Science databases were searched by computer."Shape memory alloys,application progress,orthodontics,orthopedic,prosthesis,rehabilitation,properties,implantation,mechanical properties,nickel-titanium memory alloys,actuation"were used as Chinese search terms."Shape memory alloys,application,orthodontics,orthopedic,prosthetics,rehabilitation,properties,implant,drive,progress,prostheses"were used as English search terms.Finally,91 articles were included for review. RESULTS AND CONCLUSION:(1)Shape memory alloy has the characteristics of corrosion resistance,wear resistance,biocompatibility,fatigue resistance,kink resistance and other properties.Compared with other traditional materials(stainless steel,titanium alloy,cobalt-chromium alloy,etc.),shape memory alloy has lower elastic modulus and no biological toxicity,which is suitable for long-term implantation as an implant prosthesis.Due to its shape memory effect and excellent mechanical properties,it is mainly used as a driving element or as a bridge connecting the device and the human body in artificial limbs,orthoses and rehabilitation equipment.(2)The use of shape memory alloy drive elements can reduce the weight of the device,eliminate noise,easy to operate,easy to carry,better assist joint movement;compared with the use of pneumatic,hydraulic,and electrical drive methods of the device,it has obvious advantages.(3)In addition,shape memory alloy can produce permanent and stable stress during deformation.Compared with stainless steel,titanium alloy and aluminum alloy,shape memory alloy has a higher material recovery rate and does not need to be replaced and adjusted frequently,so it is more practical in the correction of deformity.(4)At present,shape memory alloy is most commonly used in orthosis,and the best clinical application effect is in stapes prosthesis.However,due to the limitations of technology and cost,shape memory alloys are rarely used in artificial limbs and rehabilitation equipment,and there is a lack of large sample size studies on the application effect.(5)Although shape memory alloys have been developed in the field of auxiliary and rehabilitation,there are still many problems:it is difficult to accurately control the shape memory alloys;the cooling speed of shape memory alloy is slow;the deformation speed of shape memory alloy cannot be controlled;there is a lack of comparative research and expert consensus on shape memory alloys with different properties;shape memory alloys are costly and expensive.(6)In the future,attention should be paid to the development of new shape memory alloys,increase comparative research,and use new technologies and methods(such as 4D printing)to solve the existing problems,so as to develop high-performance assistive devices and rehabilitation equipment.

ObjectiveTo explore effect of Xianlian Jiedu prescription on the recurrence of colorectal cancer （CRC） and investigate the related mechanisms. MethodsA postoperative recurrence model was established in 25 Balb/c mice by injecting CT26 cells subcutaneously into the armpit， followed by surgical removal of 99% of the subcutaneous tumor. The mice were randomly divided into model group， low-dose Xianlian Jiedu prescription （XLJDP-L） group （6.45 g·kg^-1·d^-1）， medium-dose Xianlian Jiedu prescription （XLJDP-M） group （12.9 g·kg^-1·d^-1）， high-dose Xianlian Jiedu prescription （XLJDP-H） group （25.8 g·kg^-1·d^-1）， and 5-fluorouracil （5-FU） group （1×10^-3 g·kg^-1·d^-1）. The mice were euthanized after 14 days of continuous intervention， and recurrent tumor tissue was harvested. Hematoxylin and eosin （HE） staining was used to observe pathological and morphological changes in the recurrent tumor tissue. Immunohistochemistry （IHC） was employed to assess the expression of proliferating cell nuclear antigen （Ki67）， vascular endothelial growth factor （VEGF）， and platelet-endothelial cell adhesion molecule （CD31） in recurrent tumor tissue. The Western blot was used to detect the protein expression levels of angiopoietin-2 （ANG-2）， VEGF， phosphorylated-protein kinase B （p-Akt）， protein kinase B （Akt）， phosphorylated-phosphatidylinositol 3-kinase （p-PI3K）， and phosphatidylinositol 3-kinase （PI3K） in recurrent tumor tissue. ResultsBefore treatment， there were no statistical differences in tumor volume， tumor weight， and body mass among the XLJDP-L， XLJDP-M， and XLJDP-H groups and the 5-FU group compared to the model group， indicating model stability. After treatment， compared with those in the model group， the tumor volume and tumor weight in the XLJDP-L， XLJDP-M， and XLJDP-H groups and the 5-FU group were significantly reduced （P<0.01）， showing dose dependency. Meanwhile， there were no significant differences in body weight among the XLJDP-L， XLJDP-M， and XLJDP-H groups and the 5-FU group compared to the model group. HE staining showed that compared with that in the model group， tumor tissue in the XLJDP-L， XLJDP-M， and XLJDP-H groups and the 5-FU group had loosely arranged cells， increased intercellular spaces， small and shriveled nuclei， light staining， fewer mitotic figures and atypical nuclei， and increased necrotic areas. IHC showed that compared with those of the model group， the positive rates of Ki67， VEGF， and CD31 in the recurrent tumor tissue of the XLJDP-L， XLJDP-M， and XLJDP-H groups and the 5-FU group were significantly reduced （P<0.01） in a dose-dependent manner. Western blot results showed that compared with those of the model group， the protein expression levels of ANG-2 and VEGF in the recurrent tumor tissue of the XLJDP-L， XLJDP-M， and XLJDP-H groups and the 5-FU group were significantly downregulated （P<0.05， P<0.01）， and the p-Akt/Akt and p-PI3K/PI3K ratios were significantly decreased in a dose-dependent manner （P<0.05， P<0.01）. ConclusionXianlian Jiedu prescription significantly inhibits the recurrence of CRC in mice after subcutaneous tumor surgery. The mechanism may involve regulating the PI3K/Akt pathway and downregulating key angiogenic proteins such as ANG-2， VEGF， and CD31.

BACKGROUND:Currently,numerous experiments delve into the intricate anatomy and biomechanical behavior of distinct segments of the supraspinatus muscle.However,the impact of shoulder joint stress resulting from damage to various regions of this muscle remains a scarcely explored domain.Understanding the repercussions of supraspinatus muscle injuries across different regions on the stress distribution and magnitude of articular cartilage and the glenoid is crucial for providing some theoretical support for clinical diagnosis and treatment. OBJECTIVE:To ascertain the maximum stress values by simulating different degrees of supraspinatus muscle rupture on the humeral cartilage surface,glenoid lip,and glenoid cartilage joint surface using three-dimensional finite element software. METHODS:Normal and healthy shoulder joint CT or MRI scans were processed through Mimics and Geomagic to extract molds.Subsequently,models were constructed via Solidworks.Varying degrees of supraspinatus muscle damage were simulated for each model to mimic fractures in different regions.Finally,Ansys,mechanical software,was employed for three-dimensional finite element biomechanical analysis,calculating stress values for the humeral cartilage surface,glenoid lip,and glenoid cartilage joint surface. RESULTS AND CONCLUSION:(1)With worsening degrees of supraspinatus muscle injury,the stress on the shoulder joint cartilage surface and glenoid lip escalated.(2)Among various regions,the anterior part of the supraspinatus muscle exhibited paramount significance.(3)While supraspinatus muscle fractures of differing degrees impacted the magnitude of cartilage stress on the glenoid labial surface,the stress distribution remained constant.(4)It is indicated that during the initial stages of horizontal abduction of the shoulder joint,the anterior region assumes a pivotal role,followed by the posterior deep region.Injury to the anterior part of the supraspinatus muscle leads to a significant surge in stress within the shoulder joint's soft tissue,potentially causing damage to the top of the glenoid lip and the anterior part of the glenoid cartilage.

Objective To analyze the elevated blood pressure status and its influencing factors among manufacturing workers in Foshan City. Methods A total of 565 795 manufacturing workers who underwent occupational medical examinations in Foshan City from 2017 to 2023 were included. Data of workers were obtained from the Guangdong Provincial Key Occupational Disease Monitoring and Management Platform. The influencing factors of elevated blood pressure were analyzed using descriptive epidemiological methods. Results A total of 89 526 cases of elevated blood pressure were detected among the 565 795 workers, with a detection rate of 15.82%. From 2017 to 2023, the annual detection rate of elevated blood pressure was 14.11%, 15.00%, 14.69%, 15.94%, 17.00%, 16.90%, and 16.68%, respectively, showing an overall upward trend (P<0.01). The top three industries with the highest detection rates of elevated blood pressure were instrument and meter manufacturing; wood processing and the manufacture of wood, bamboo, rattan, palm, and straw products; as well as agricultural and sideline food processing. Binary logistic regression analysis showed that male workers had a higher risk of elevated blood pressure than female workers (P<0.01). The risk of elevated blood pressure in workers increased with age, years of occupational hazard exposure, and duration of dust exposure (all P<0.05). Workers exposed to noise for more than three years had a higher risk of elevated blood pressure than those without noise exposure (P<0.05). The risk of elevated blood pressure among workers in Nanhai, Shunde, and Gaoming districts was higher than that in Chancheng District (all P<0.01). Workers originating from Northeast and Northwest China had a higher risk of elevated blood pressure than those from North China (all P<0.05). Workers from smaller-scale enterprises had higher risk of elevated blood pressure (all P<0.01). Conclusion Targeted blood pressure health interventions in Foshan City should be strengthened for male manufacturing workers who are older, have longer working years, and originate from Northeast and Northwest China. The development of exemplary health enterprises should be promoted, particularly among micro- and small-sized enterprises and key industries. Enhanced occupational health management is especially needed for positions with high intensity noise exposure and high concentration dust exposure.