Resistencia a la corrosión y citotoxicidad de los aceros inoxidables expuestos a soluciones de cloruro / Corrosion resistance and cytotoxicity of stainless steels exposed to chloride solutions / Resistência à corrosão e citotoxicidade de aços inoxidáveis expostos a soluções de cloretos

Objetivo: Analizar la resistencia a la corrosión por picaduras de aceros inoxidables AISI 304 y AISI 420 en un medio que contiene cloruros (solu-ción de NaCl al 0,9 y 3,5%, en masa), así como su citotoxicidad, in vitro, en muestras con y sin corrosión por picaduras. Método: Estudio experimental. Se utilizaron técnicas de polarización potenciodinámica cíclica (PPC) para caracterizar el alcance y la forma del ataque corrosivo a las muestras. Se utilizó el método de difusión en agar y evaluación de la viabilidad de la línea celular NCTC clon 929 (CCIAL 020) para evaluar la citotoxicidad de las muestras de acero con y sin picaduras. Resultados: El acero AISI 304 presentó una resistencia a la corrosión superior al acero AISI 420. Los valores de potencial de picadura disminuyeron para ambos aceros cuando aumentó la concentración de cloruros en la solución agresiva. Hubo toxicidad celular moderada (grado 3 ­ ISO 10993-5) en todas las muestras. Conclusión: Los resultados corroboraron las recomendaciones para evitar la inmersión innecesaria de instrumentos en soluciones salinas. La citotoxicidad moderada de estos aceros desaconseja su uso en dispositivos implantables, reservándolos solo para instrumentos quirúrgicos. (AU)

Objective: To analyze the pitting corrosion resistance of AISI 304 and AISI 420 stainless steels in chloride-containing medium (0.9 and 3.5% NaCl solution, by weight), as well as their cytotoxicity,in vitro, in samples with and without pitting corrosion. Method: This is an experimental study. Cyclic potentiodynamic polarization (CPP) techniques were used to characterize the extent and shape of the corrosive attack on the samples. The agar diffusion and viability evaluation method of the NCTC clone 929 cell line (CCIAL 020) was used to evaluate the cytotoxicity of samples of steels with and without pitting. Results: The AISI 304 steel showed superior corrosion resistance to the AISI 420 steel. The values of the pitting potentials decreased for both steels when the chloride concentration in the aggressive solution was increased. There was moderate cell toxicity (grade 3 ­ ISO 10993-5) in all samples. Conclusions: The results corroborated the recommendations to avoid unnecessary immersion of the instruments in saline solutions. Moderate cytotoxicity to these steels contraindicates their use in implantable devices, only in surgical instruments. (AU)

Objetivo: Analisar a resistência à corrosão por pites dos aços inoxidáveis AISI 304 e AISI 420 em meio contendo cloretos (solução de NaCl a 0,9 e 3,5%, em massa), assim como sua citotoxicidade,in vitro, em amostras com e sem corrosão por pites. Método: Estudo experimental. Utilizaram-se téc-nicas de polarização potenciodinâmica cíclica (PPC) para caracterizar extensão e forma do ataque corrosivo nas amostras. O método de difusão em ágar e avaliação da viabilidade da linhagem celular NCTC clone 929 (CCIAL 020) foi empregado para avaliar a citotoxicidade de amostras dos aços com e sem pites. Resultados: O aço AISI 304 apresentou resistência à corrosão superior ao aço AISI 420. Os valores dos potenciais de pite caíram para ambos os aços quando se aumentou a concentração de cloretos na solução agressiva. Houve moderada toxicidade celular (grau 3 ­ ISO 10993-5) em todas as amostras. Conclusão: Os resultados corroboraram as recomendações para evitar a imersão desnecessária dos instrumentais em soluções salinas. A citotoxicidade moderada para esses aços contraindica seu uso em dispositivos implantáveis, apenas em instrumentos cirúrgicos. (AU)

Application of machine learning in key properties of medical metal materials / 中国组织工程研究

BACKGROUND:The combination of machine learning and medical metal materials can make up for the inefficiency and high cost of traditional experiments and computational simulations,and quickly and accurately predict the characteristics of metal materials by analyzing large amounts of data,optimize material design and performance,and improve the safety and efficiency of medical applications. OBJECTIVE:To summarize the research progress and shortcomings of machine learning in the characteristics of medical materials. METHODS:The first author searched CNKI,PubMed,X-MOL,and Web of Science databases by computer to search all relevant articles from January 2013 to April 2023.The Chinese search terms were"machine learning of medical metal materials,medical titanium alloy,medical magnesium alloy,medical metal material properties".The English search terms were"machine learning medical metal materials,medical stainless steel alloy,medical cobalt-chromium alloy,medical titanium alloy,medical magnesium alloy".Finally,70 relevant articles were included for a summary. RESULTS AND CONCLUSION:(1)The introduction of machine learning as a material design methodology has opened up new paradigms for material science research as the accessibility of large amounts of data generated by traditional experimental and computational simulation methods increases.(2)The machine learning workflow is divided into four main parts:data collection and preprocessing,feature engineering,model selection and training,and model evaluation,each of which is indispensable.(3)Medical metal materials are categorized into:stainless steel co-base alloys,cobalt-chromium alloys,titanium alloys,and magnesium alloys.For stainless steel co-base alloy,machine learning predicts its mechanical properties,to improve the generalization ability of machine learning.For cobalt-chromium alloy,machine learning predicts its mechanical properties,and it can conclude that cobalt-chromium alloy is the optimal material for hip implants.For titanium alloy,machine learning predicts its mechanical properties,and it can select the implant with the best mechanical properties.For magnesium alloy,machine learning predicts its corrosion resistance and mechanical properties;the ensemble model can accurately predict the mechanical properties of magnesium alloys,and the random forest model can predict the optimal elemental contents of magnesium alloys as vascular stents.(4)Machine learning has deficiencies in the field of medical materials.For example,the model is relatively lagging;the data failed to be standardized,and the generalization is low.To solve such problems,we should make full use of deep learning and segmentation algorithm technology,use unified standard data,and improve the model to increase the generalization ability.

Antibacterial properties of silver nanoparticle-coated stainless steel prepared via active screen plasma surface modification in vitro / 中国组织工程研究

BACKGROUND:Most of the silver coating materials prepared using active screen plasma technology in the past do not involve the nanotechnology field.The formed silver coating is in a"thin film"form,which is coated on the surface of the substrate,and the distribution of silver particles on the surface is uneven.Its long-term antibacterial ability is challenged. OBJECTIVE:To prepare nano silver coatings capable of being"buried"within stainless steel(SS)substrates using active screen plasma surface modification(ASPSM)and to observe antibacterial activity. METHODS:The nano-silver coating was prepared by ASPSM technique on stainless steel substrate.Three groups of coating samples were prepared by adjusting the bombardment time(1,2,and 4 hours),which were denoted as 1 h-Ag-ASPSM@SS,2 h-Ag-ASPSM@SS and 4 h-Ag-ASPSM@SS,respectively.The antibacterial activity of the coatings was analyzed by antibacterial ring test and Gram staining.The antibiotic coating samples of gentamicin combined with vancomycin were prepared by using stainless steel as substrate and were recorded as ACNs.Stainless steel,2 h-Ag-ASPSM@SS,and ACNs were inserted into Staphylococcus aureus or Pseudomonas aeruginosa suspension,respectively.The long-acting(84 days)antibacterial activity of the samples was analyzed by coating plate method.Bone marrow mesenchymal stem cells were co-cultured with stainless steel,2 h-Ag-ASPSM@SS,and ACNs,respectively.CCK-8 assay,dead/alive staining,and lactate dehydrogenase activity of cell supernatant were detected.Stainless steel,2 h-Ag-ASPSM@SS,and ACNs were taken after continuous exposure to Staphylococcus aureus suspension for 12 weeks.The amount of residual viable bacteria on the surface of the material was evaluated by spread plate method.Vancomycin drug sensitive disk method was used to evaluate the resistance of residual live bacteria on the surface of materials. RESULTS AND CONCLUSION:(1)With increasing bombardment time,the diameter of nano silver on the sample surface and the silver content in the coating gradually increased.Among them,the 2 h-Ag-ASPSM@SS exhibited the highest surface silver content while forming uniformly spherical nanoparticles.(2)Antibacterial ring test and Gram staining results demonstrated that compared with 1 h-Ag-ASPSM@SS and 4 h-Ag-ASPSM@SS,the 2 h-Ag-ASPSM@SS exhibited better inhibitory effect on Staphylococcus aureus and pseudomonas aeruginosa.After co-culturing with bacteria for 42 and 84 days,the number of viable bacteria on the spread plate method was significantly lower in the 2 h-Ag-ASPSM@SS group compared to the stainless steel and ACNs groups.After co-culturing with Staphylococcus aureus for 84 days and Pseudomonas aeruginosa for 42 days,the number of viable bacteria on the surface of the eluate from the ACNs group was higher than that of the stainless steel group.(3)CCK-8 assay,live/dead staining and lactate dehydrogenase activity of cell supernatant displayed that 2 h-Ag-ASPSM@SS did not have obvious cytotoxicity.ACNs showed obvious cytotoxicity.(4)After co-culture with Staphylococcus aureus for 12 weeks,the residual viable bacteria on the surface of 2 h-Ag-ASPSM@SS group was less than that of stainless steel group,and the residual viable bacteria on the surface of the ACNs group was more than that of stainless steel group.Compared with the stainless steel group,the sensitivity to vancomycin was significantly decreased in the ACNs group(P＜0.001),and there was no significant change in sensitivity to vancomycin in 2 h-Ag-ASPSM@SS group(P＞0.05).(5)The above results indicate that the silver nanoparticle coated stainless steel greatly improves the deposition efficiency of silver nanoparticles on the stainless steel surface and has long-lasting antibacterial properties and good cell compatibility.

Comparison of three kinds of palmar approach plate implantation for treatment of unstable distal radius fractures / 中国组织工程研究

BACKGROUND:In the past,it was necessary to cut off the pronator quadratus muscle in the treatment of distal radius fractures.Failure to repair the pronator quadratus muscle can lead to a series of complications. OBJECTIVE:To explore the clinical efficacy of different methods of preserving the pronator quadratus muscle combined with a palmar steel plate in the treatment of distal radius fractures. METHODS:Clinical data of 66 patients with distal radius fractures were retrospectively included,divided into the traditional Henry approach group(group A),the split brachioradialis tendon approach group(group B),and the posterior pronator quadratus muscle approach group(group C),with 22 patients in each group.Postoperative internal fixation,fracture healing,and postoperative complications were observed in the three groups.The visual analog scale score of postoperative wrist pain and forearm rotation angle were compared among the three groups.The Dienst Joint Scale was used to evaluate the wrist function of patients. RESULTS AND CONCLUSION:(1)The surgical time,intraoperative blood loss,and fracture healing time of groups B and C were significantly lower than those of group A(P<0.01).There was no significant difference in intraoperative blood loss and fracture healing time between groups B and C,but the surgical time was shorter in group B.(2)The anteroposterior and lateral wrist X-ray examination 3 days and 1 and 3 months after surgery exhibited that there were no significant differences in radial height,palm angle,and ulnar deviation angle among the three groups(P>0.05).No significant difference was detected in various indicators during the same phase among the three groups(P>0.05).(3)At a follow-up of 12 months after surgery,there were no significant differences in visual analog scale scores and forearm rotation angle among the three groups.However,the evaluation results at 1 and 3 months after surgery demonstrated significant differences in visual analog scale scores and forearm rotation angle among the three groups(P<0.05).Among them,group C had a lower visual analog scale score and a larger forearm rotation angle.(4)According to the Dienst joint scoring standard,the excellent and good rate of wrist joint function evaluation was 86%(19/22),91%(20/22),and 95%(21/22)in groups A,B,and C,respectively 12 months after surgery.(5)All patients did not experience any postoperative vascular or neurological damage or surgical site infection.Group A had three cases of tendon irritation,two cases of traumatic arthritis,and two cases of carpal tunnel syndrome.In group B,tendon irritation occurred in 1 case and joint stiffness in 1 case.There was 1 case of traumatic arthritis and 1 case of carpal tunnel syndrome in group C.(6)It is suggested that different surgical methods for treating distal radius fractures have achieved good clinical results.Placing a steel plate under the pronator muscle can alleviate early postoperative pain,promote early activity,and restore normal life.The brachioradialis tendon approach has more advantages in exposing intraoperative fractures and can shorten the surgical time.

Reverse design of a new type of low-profile lateral malleolus steel plate assisted by computer bioengineering technology / 中国组织工程研究

BACKGROUND:Poor incision healing and infection often occur in elderly patients with lateral malleolar fractures after traditional lateral plate fixation.With the application of engineering software in medicine,a new type of plate placed posterolateral can be designed to solve the above-described problems. OBJECTIVE:To design a new type of posterior lateral low-profile steel plate with the aid of medical bioengineering software,based on the 3D CT data of the distance between the top of the lateral ankle fracture line to the anterior starting point(ACD),the distance between the top of the fracture line to the tip of the lateral ankle(CTD),the distance between the top of the fracture line to the posterior edge of the fracture line(PCD)and the angle between the anterior and posterior lateral sides of the distal fibula(CA). METHODS:Thirty cases of unstable lateral malleolar fracture and normal ankle were taken for CT scanning and three-dimensional reconstruction.The ACD,CTD,and PCD values in patients with lateral malleolar fracture were measured by 3-matic software,and the characteristics of lateral malleolar fracture line were plotted and described.The mimics software was used to measure the value of CA in the normal ankle joint.Based on the data measured above,3-matic software and solidworks software were used to design the low-profile steel plate and the thickness of the steel plate and the direction of the nail path were constructed.In Geomagic Studio software,fine surface,automatic surface,and fitting surface were used to generate the prototype of the low-profile steel plate,and then 3D printing was performed.After making a posterolateral incision of the lateral malleolus,the peroneus longus and brevis tendons were removed,and the prototype of the 3D-printed steel plate was placed behind the fibula to test its size and fit to the bone surface. RESULTS AND CONCLUSION:(1)The mean of ACD was(2.97±0.03)cm,and the variation was 5.23.The mean of PCD was(3.17±0.11)cm,and the variation was 17.60.The mean of CTD was(4.52±0.07)cm,and the variation was 8.60.(2)The fracture line of the lateral malleolus was drawn with an inverted"V"shape.The mean of CA between anterior and posterior lateral surfaces of the distal fibula was(103.20±1.94)°.At the midpoint section of the upper and lower vertices of the anterior edge of the distal fibula,the angle of the anterior and posterior lateral sides(CA)of the distal fibula was(78.50±1.78)°.(3)By using 3-matic,Solidworks,and Geomagic Studio software,a new type of posterior lateral low-profile steel could be successfully designed.Three to four holes were reserved for the screw holes at the proximal end of the plate with screw directions from back to front,and three screw holes were reserved on the inner and outer sides at the far end.The direction of the inner three holes could be from back to front,and the outer three screw holes needed to be biased towards the inner side,with an angle of 9.72°-13.28°.(4)It is indicated that the variability of the ACD position on the anterior lateral fracture line of the lateral malleolus is relatively small,while the variability of the posterior lateral PCD position is relatively large.The angle between the anterolateral and posterolateral sides of the lateral ankle fracture block shows a decreasing trend,with a smaller variation in the proximal angle and a larger variation in the distal angle.Based on three-dimensional CT reconstruction data of the external ankle,with the help of computer bioengineering software and the use of reverse design concept,a new type of low-profile lateral malleolus steel plate with a good fit can be quickly and conveniently designed to provide a valuable reference for the design of internal fixation devices.

Design and finite element analysis of a new type of plate for hyperextension varus tibial plateau fractures / 中国组织工程研究

BACKGROUND:There is currently no anatomic locking plate suitable for the anteromedial platform,so the medial locking plate of the tibial plateau is usually placed forward to fix anteromedial compression fractures caused by hyperextension varus injury.Due to the inability of the locking screw to achieve vertical fixation of the fracture line,coupled with the influence of the patellar ligament,the clinical results are still unsatisfactory. OBJECTIVE:To compare the biomechanical performance of a new type of plate with traditional internal fixation methods in treating hyperextension varus tibial plateau fractures through finite element analysis. METHODS:CT data of 20 cases of hyperextension varus tibial plateau fractures were collected,and their morphological characteristics,such as medial posterior tibial slope,the medial articular fracture angle,surface area,and anterior cortical height were measured.A 24-year-old male volunteer with a height of 175 cm and a weight of 65 kg was selected,and his tibial CT data were imported into Mimics 21.0 software to generate a 3D model.Then,internal fixation models were imported into SolidWorks 2017 software.New type of plate,medial locking plate,posterior medial locking plate,and 6.5 mm hollow screws fixed data models were established based on the measured morphological data.Ansys 17.0 software was used to load stress on the four fixation models and compare their biomechanical performance. RESULTS AND CONCLUSION:(1)With the increase of axial load,the peak stresses of different internal fixation models approximately increased proportionally.At 500 N,the peak stress values were as follows:screw group(6.973 7 MPa)<new steel plate group(14.733 MPa)<medial locking plate group(16.445 MPa)<posterior medial locking plate group(25.199 MPa).(2)The peak stresses of the fracture block were as follows:at 500 N,screw group(3.657 9 MPa)<new steel plate group(4.510 8 MPa)<medial locking plate group(5.225 9 MPa)<posterior medial locking plate group(6.181 2 MPa).(3)With the increase of axial load,the displacement of the fracture block and internal fixation approximately increased proportionally,and the displacement distribution characteristics showed no significant changes.At 500 N,the steel plate displacement values were as follows:new steel plate group(1.030 7 mm)<medial locking plate group(1.503 mm)<screw group(2.096 5 mm)<posterior medial locking plate group(2.258 2 mm).At 500 N,the fracture block displacement values were as follows:new steel plate group(0.212 8 mm)<medial locking plate group(0.311 54 mm)<screw group(0.427 79 mm)<posterior medial locking plate group(0.454 98 mm).(4)It is concluded that in the treatment of hyperextension varus tibial plateau fractures,the stability and mechanics of the new steel plate are superior to traditional internal fixation methods.

Survey on occupational injury among workers in a steel enterprise / 预防医学

Objective @#To investigate the prevalence of occupational injury and identify its influencing factors among workers in a steel enterprise in Gansu Province, so as to provide insights into prevention of occupational injury among steel workers. @*Methods@#Workers were sampled from a steel enterprise in Gansu Province using a cluster sampling method from January to March 2022, and participants' demographics, occupational history and occupational injury were collected using questionnaire surveys. The type of job and site and type of injury were analyzed among workers with occupational injuries, and factors affecting workers' occupational injuries were identified using a multivariable logistic regression model. @*Results@#A total of 12 089 questionnaires were allocated and 10 725 valid questionnaires were recovered, with an effective recovery rate of 88.71%. The respondents included 9 412 males (87.77%) and 1 312 females (12.23%), and had a median age of 36.00 (interquartile range, 15.00) years. Junior college and above was the predominant educational level (6 056 workers, 56.47%), and the respondents had a median length of service of 10 (interquartile range, 11) years. The prevalence of occupational injury was 5.25% among respondents. Overhaul worker was the main type of job (11.90%), and object strike was the predominant type of occupational injury (18.25%), while the lower limb was the predominant site of injury (27.82%). Multivariable logistic regression analysis identified men (OR=2.464, 95%CI: 1.580-3.843), age (30 to 39 years, OR=2.561, 95%CI: 1.643-3.993; 40 to 49 years, OR=5.197, 95%CI: 2.679-10.079; 50 years and older, OR=10.620, 95%CI: 6.788-16.615), exposure to high temperature (OR=1.400, 95%CI: 1.165-1.683), operating equipment failure (OR=1.291, 95%CI: 1.048-1.591), absence of personal safety protection equipment (OR=1.555, 95%CI: 1.064-2.273) and safety behavior scores (OR=0.967, 95%CI: 0.937-0.996) as factors affecting occupational injuries among workers in a steel enterprise. @*Conclusions@#Men and overhaul workers are at a high risk of occupational injuries in this steel enterprise. Objectstrike is the predominant type of injury and lower limb is the main site of injury. The risk of occupational injuries is affected by gender, age, working environments, equipment status and safety behaviors.

Insertion torque, flexural strength and surface alterations of stainless steel and titanium alloy orthodontic mini-implants: an in vitro study

ABSTRACT Objective: This study aimed to compare the insertion torque (IT), flexural strength (FS) and surface alterations between stainless steel (SS-MIs) and titanium alloy (Ti-MIs) orthodontic mini-implants. Methods: Twenty-four MIs (2 x 10 mm; SS-MIs, n = 12; Ti-MIs, n = 12) were inserted on artificial bone blocks of 20 lb/ft3 (20 PCF) and 40 lb/ft3 (40 PCF) density. The maximum IT was recorded using a digital torque meter. FS was evaluated at 2, 3 and 4 mm-deflection. Surface topography and chemical composition of MIs were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). General linear and mixed models were used to assess the effect of the MI type, bone density and deflection on the evaluated outcomes. Results: The IT of Ti-MIs was 1.1 Ncm greater than that obtained for the SS-MIs (p= 0.018). The IT for MIs inserted in 40 PCF test blocks was 5.4 Ncm greater than that for those inserted in 20 PCF test blocks (p < 0.001). SS-MIs inserted in higher density bone (40 PCF) had significantly higher flexural strength than the other groups, at 2 mm (98.7 ± 5.1 Ncm), 3 mm (112.0 ± 3.9 Ncm) and 4 mm (120.0 ± 3.4 Ncm) of deflection (p< 0.001). SEM evidenced fractures in the Ti-MIs. EDS revealed incorporation of 18% of C and 2.06% of O in the loaded SS-MIs, and 3.91% of C in the loaded Ti-MIs. Conclusions: Based on the findings of this in vitro study, it seems that SS-MIs offer sufficient stability and exhibit greater mechanical strength, compared to Ti-MIs when inserted into higher density bone.

RESUMO Objetivo: O objetivo deste estudo foi comparar o torque de inserção (TI), a resistência flexural (RF) e as alterações de superfície em mini-implantes ortodônticos de aço inoxidável (MIs-Ai) e de liga de titânio (MIs-Ti). Métodos: Vinte e quatro MIs (2 x 10 mm; MIs-Ai, n = 12; MIs-Ti, n = 12) foram inseridos em blocos de osso artificial de densidades de 20 lb/ft3 (20 PCF) e 40 lb/ft3 (40 PCF). O torque máximo de inserção foi registrado por meio de um torquímetro digital. A resistência flexural foi avaliada nas deflexões de 2, 3 e 4 mm. Topografia de superfície e composição química dos MIs foram avaliadas por Microscopia Eletrônica de Varredura (MEV) e Espectroscopia de Energia Dispersiva de Raios X (EDS). Modelos lineares gerais e mistos foram utilizados para avaliar o efeito do tipo de MI, da densidade óssea e da deflexão nos desfechos avaliados. Resultados: O TI dos MIs-Ti foi 1,1 Ncm maior do que o obtido para os MIs-Ai (P = 0,018). O TI para MIs inseridos em blocos de teste de 40 PCF foi 5,4 Ncm maior do que para aqueles inseridos em blocos de teste 20 PCF (p < 0,001). MIs-Ai inseridos em osso de maior densidade (40 PCF) apresentaram resistência flexural significativamente maior do que outros grupos, em deflexões de 2 mm (98,7 ± 5,1 Ncm), 3 mm (112,0 ± 3,9 Ncm) e 4 mm (120,0 ± 3,4 Ncm) (p < 0,001). A MEV evidenciou fraturas nos MIs-Ti. A EDS revelou incorporação de 18% de C e 2,06% de O nos MIs-Ai e 3,91% de C nos MIs-Ti, ambos submetidos a testes mecânicos. Conclusões: Com base nos resultados desse estudo in vitro, os MIs-Ai aparentam oferecer adequada estabilidade e maior resistência mecânica, em comparação aos MIs-Ti, quando inseridos em osso de maior densidade.

Treatment of pediatric femur fractures with flexible stainless steel intramedullary nail / Tratamento de fraturas do fêmur pediátrico com haste intramedular flexível de aço inoxidável

ABSTRACT Objectives: To identify the characteristics of patients and femur fractures treated with a stainless steel intramedullary nail (ESIN) in children under 15 years of age. Know the results of using the ESIN of related steel in the service. Methods: Retrospective study with review of hospital records and organization of data in spreadsheets. Result: 24 cases were identified, 17 male cases and 7 female cases. A minimum age of 4 years and a maximum of 11 years were observed (average of 7 years). The 3 most common trauma mechanisms were being run over (n:8, 33%) and falling from a height (n:8, 3%). The most common location of the fractures was in the mid-diaphyseal region (n: 20, 88%), only one case presented a bilateral femur fracture. The most common associated trauma was traumatic brain injury. The observation period observed several months between 2 and 5. With regard to complications, 3 cases were observed (12.5%) being bursitis, vicious construction and loss of reduction. Conclusion: Steel HIF shows similar good results. As the study includes the retrospective profile, the absence of a group and the small sample size. Level of Evidence IV, Case series.

RESUMO Objetivos: Identificar as características dos pacientes e das fraturas de fêmur tratadas com haste intramedular flexível (HIF) de aço inoxidável em menores de 15 anos. A partir disso, conhecer os resultados relacionados ao uso da HIF de aço inoxidável no serviço. Métodos: Estudo retrospectivo, com revisão de prontuários hospitalares e organização dos dados em planilhas. Resultado: Identificados 24 casos, sendo 17 do gênero masculino e sete do gênero feminino. Foram observadas idade mínima de 4 anos e máxima de 11 anos (média de 7 anos). Os mecanismos de trauma mais comuns foram atropelamento (n: 8, 33%) e queda de altura (n: 8, 33%). A localização mais comum das fraturas foi na região médio diafisária (n: 20, 88%), apenas um caso apresentou fratura de fêmur bilateral. O trauma associado mais comum foi traumatismo crânio-encefálico. O período de consolidação observado variou entre 2 e 5 meses. No que se refere a complicações, foram observados três casos (12,5%), sendo estes: bursite, consolidação viciosa e perda de redução. Conclusão: A HIF de aço apresenta bons resultados, semelhantes aos das hastes de titânio. As limitações do estudo incluem o perfil retrospectivo, a ausência de grupo controle e o número pequeno da amostra. Nível de evidência IV, Série de casos.

Biological control of foodborne pathogens by lacticacid bacteria: A focus on juice processing industries

Abstract The use of lactic acid bacteria (LAB) in foods as biocontrol agents against foodborne pathogens has become increasingly known. Under the premise that controlling the adhesion of microorganisms to food contact surfaces is an essential step for meeting the goals of food processing, the aim of this work was to investigate the inhibitory and anti-biofilm effectiveness of Lactobacillus rhamnosus GG (ATCC 53103) and Lactobacillus casei (ATCC 393) against Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes. Lactobacillus strains (108UFCCFU/ml) and pathogens (104UFCCFU/ml) were evaluated to monitor LAB anti-adhesive and antibiofilm effect, in two main scenarios: (i) co-adhesion and (ii) pathogen incorporation to stainless steel surfaces with a protective biofilm of Lactobacillus cells. In (i) the predominant effect was observed in L. rhamnosus against S. enterica and L. monocytogenes, whereas in (ii) both LAB significantly reduced the number of pathogenic adherent cells. The effect of pre-established LAB biofilms was more successful in displacing the three pathogens than when they were evaluated under co-adhesion. These findings show that both LAB can be considered good candidates to prevent or inhibit the adhesion and colonization of L. monocytogenes, S. enterica and E. coli O157:H7 on surfaces and conditions of relevance for juice processing industries, offering alternatives for improving the safety and quality of fruit-based products.

Resumen Existe un creciente interés en el uso de bacterias ácido lácticas (BAL) como agentes de biocontrol frente a patógenos de transmisión alimentaria. Bajo la premisa de que el control de la adhesión de microorganismos a superficies de contacto con alimentos es el paso esencial para evitar su contaminación, el objetivo de este trabajo fue investigar la efectividad inhibitoria y antibiofilm de Lactobacillus rhamnosus GG (ATCC 53103) y Lactobacillus casei (ATCC 393) frente a Escherichia coli O157:H7, Salmonella enterica y Listeria monocytogenes. A fin de cumplir con el objetivo propuesto, las cepas de Lactobacillus (108UFCUFC/ml) y los patógenos (104UFCUFC/ml) se ensayaron en 2 escenarios: (1) coadhesión, y (2) incorporación de los patógenos a las superficies de acero inoxidable con un biofilm preformado de Lactobacillus. En (1), el efecto predominante se observó con L. rhamnosus frente a S. enterica y L. monocytogenes, mientras que en (2), ambas BAL redujeron significativamente el número de células patógenas adheridas. En función de estos resultados, concluimos que el efecto de un biofilm preformado de ambas BAL fue más exitoso en el desplazamiento de los 3 patógenos que en coadhesión. Ambas BAL pueden considerarse buenas candidatas para mitigar la adhesión y colonización de L. monocytogenes, S. enterica y E. coli O157:H7 en superficies en condiciones de relevancia para la industria procesadora de jugos, y, de esta manera, ofrecer alternativas para mejorar la seguridad y calidad de los alimentos a base de frutas.

EFFECT ON FINANCIAL PERFORMANCE ANALYSIS WITH SPECIAL REFERENCE TO SALEM STEEL PLANT AT SALEM

The present study aims to identify the ?nancial strengths and weaknesses of the salem steel plant by properly establishing relationships between the items of the balance sheet and pro?t and loss account. The study covers Salem Steel Plant, a special steels unit of Steel Authority of India Ltd, pioneered the supply of wider width stainless steel sheets / coils in India. The study has been undertaken for the period of twelve years from 2011-12 to 2020-21and the necessary data have been obtained from SAIL database. The liquidity position was strong in case of both the selected companies thereby re?ecting the ability of the companies to pay short-term obligations on due dates and they relied more on external funds in terms of long-term borrowings thereby providing a lower degree of protection to the creditors. The study will help investors to identify the nature of SAIL industry and will also help to take decision regarding investment.

Three-dimensional printed 316L stainless steel cardiovascular stent's electrolytic polishing and its mechanical properties / 生物医学工程学杂志

The interventional therapy of vascular stent implantation is a popular treatment method for cardiovascular stenosis and blockage. However, traditional stent manufacturing methods such as laser cutting are complex and cannot easily manufacture complex structures such as bifurcated stents, while three-dimensional (3D) printing technology provides a new method for manufacturing stents with complex structure and personalized designs. In this paper, a cardiovascular stent was designed, and printed using selective laser melting technology and 316L stainless steel powder of 0-10 µm size. Electrolytic polishing was performed to improve the surface quality of the printed vascular stent, and the expansion behavior of the polished stent was assessed by balloon inflation. The results showed that the newly designed cardiovascular stent could be manufactured by 3D printing technology. Electrolytic polishing removed the attached powder and reduced the surface roughness Ra from 1.36 µm to 0.82 µm. The axial shortening rate of the polished bracket was 4.23% when the outside diameter was expanded from 2.42 mm to 3.63 mm under the pressure of the balloon, and the radial rebound rate was 2.48% after unloading. The radial force of polished stent was 8.32 N. The 3D printed vascular stent can remove the surface powder through electrolytic polishing to improve the surface quality, and show good dilatation performance and radial support performance, which provides a reference for the practical application of 3D printed vascular stent.

Efficacy of micro steel plate and Kirschner needle oblique and transverse internal fixation of adjacent metacarpal bone in the treatment of metacarpal diaphyseal oblique fracture / 中国骨伤

OBJECTIVE@#To compare the clinical efficacy of micro steel plate and Kirschner needle oblique and transverse internal fixation of adjacent metacarpal bone in the treatment of metacarpal diaphyseal oblique fracture.@*METHODS@#Fifty-nine patients with metacarpal diaphyseal oblique fractures admitted between January 2018 and September 2021 were selected as the study subjects and divided into the observation group (29 cases) and the control group (30 cases) based on different internal fixation methods. The observation group was treated with Kirschner wire oblique and transverse internal fixation of adjacent metacarpal bones, while the control group was treated with micro steel plate internal fixation. Postoperative complications, operation time, incision length, fracture healing time, treatment cost, and metacarpophalangeal function were compared between the two groups.@*RESULTS@#No incision or Kirschner wire infections occurred in the 59 patients, except for one in the observation group. No fixation loosening, rupture, or loss of fracture reduction occurred in any of the patients. The operation time and incision length in the observation group were (20.5±4.2) min and (1.6±0.2) cm, respectively, which were significantly shorter than those in the control group (30.8±5.6) min and (4.3±0.8) cm (P<0.05). The treatment cost and fracture healing time in the observation group were (3 804.5±300.8) yuan and (7.2±1.1) weeks, respectively, which were significantly lower than those in the control group (9 906.9±860.6) yuan and (9.3±1.7) weeks (P<0.05). The excellent and good rate of metacarpophalangeal joint function in the observation group was significantly higher than that in the control group at 1, 2, and 3 months after operation (P<0.05), but there was no significant difference between the two groups at 6 months after operation (P>0.05).@*CONCLUSION@#Micro steel plate internal fixation and Kirschner wire oblique and transverse internal fixation of adjacent metacarpal bones are both viable surgical methods for treating metacarpal diaphyseal oblique fractures. However, the latter has the advantages of causing less surgical trauma, shorter operation time, better fracture healing, lower cost of fixation materials, and no need for secondary incision and removal of internal fixation.

Effect of lag screw and support plate through axillary approach for the treatment of Ideberg typeⅡscapular pelvis fracture / 中国骨伤

OBJECTIVE@#To analyze the effect of lag screw and support plate through axillary approach for the treatment of Ideberg typeⅡscapular pelvis fracture.@*METHODS@#From January 2016 to June 2021, 26 patients with Ideberg typeⅡglenoid fractures were treated with trans-axillary lag screw combined with supporting plate, including 15 males and 11 females. The age ranged from 21 to 75 years, with an average of (43.12±6.56) years old. The Constant-Murley Shoulder joint Scale and University of California at Los Angeles (UCLA) score were used to evaluate the function and clinical efficacy of shoulder joint.@*RESULTS@#All patients were followed up, and the duration ranged from 19 to 42 months, with an average of (30.6±10.5) months. One year after surgery, the Constant-Murley score increased from preoperative 34.9±2.5(ranged, from 28 to 47) to 87.2±6.8(ranged, from 70 to 95). The UCLA score improved from preoperative 17.9±1.7(9 to 25) to 33.1±2.3(29 to 35). Seventeen patients got an excellent result, with 7 good, and 2 fair. None of the patients had infection, screw, and plate loosening, fracture, and other complications after surgery. Two patients had different degrees of Chronic pain in the shoulder during the follow-up period.@*CONCLUSION@#The treatment of Ideberg typeⅡscapular glenoid fractures through axillary approach with lag screws and supporting steel plates has the advantages of convenient exposure, direct visual restoration of the normal anatomical shape of the scapular glenoid, selection of suitable positions for screw and steel plate placement, achieving better treatment results, and fewer complications. It is an effective and reliable surgical method.

A method for sensitivity analysis of deviation factor for geometric correction of cone-beam CT system / 南方医科大学学报

OBJECTIVE@#To propose a sensitivity test method for geometric correction position deviation of cone-beam CT systems.@*METHODS@#We proposed the definition of center deviation and its derivation. We analyzed the influence of the variation of the three-dimensional spatial center of the steel ball point, the projection center and the size of the steel ball point on the deviation of geometric parameters and the reconstructed image results by calculating the geometric correction parameters based on the Noo analytical method using the FDK reconstruction algorithm for image reconstruction.@*RESULTS@#The radius of the steel ball point was within 3 mm. The deviation of the center of the calibration parameter was within the order of magnitude and negligible. A 10% Gaussian perturbation of a single pixel in the 3D spatial coordinates of the steel ball point produced a deviation of about 3 pixel sizes, while the same Gaussian perturbation of the 2D projection coordinates of the steel ball point produced a deviation of about 2 pixel sizes.@*CONCLUSION@#The geometric correction is more sensitive to the deviation generated by the three-dimensional spatial coordinates of the steel ball point with limited sensitivity to the deviation generated by the two-dimensional projection coordinates of the steel ball point. The deviation sensitivity of a small diameter steel ball point can be ignored.

Treatment with a proximal femoral locking plate versus a proximal femoral anti-rotation intramedullary nail for femoral intertrochanteric fractures in older adult patients / 中国基层医药

Objective:To investigate the efficacy of a proximal femoral locking plate (LPFP) versus a proximal femoral anti-rotation intramedullary nail (PFNA) in the treatment of femoral intertrochanteric fractures in older adult patients. Methods:A total of 130 older adult patients with femoral intertrochanteric fractures who received treatment in Linghu People's Hospital of Huzhou from May 2017 to June 2020 were included in this study. They were randomly assigned to undergo treatment with either a PFNA (observation group, n = 65) or an LPFP (control group, n = 65). Intraoperative blood loss, incision length, operative time, and time to fracture healing were determined in each group. At 1, 3, and 6 months after surgery, the Harris hip score was used to evaluate hip joint recovery. Coxa vara, incision infection, and internal fixation loosening were compared between the two groups. Results:Intraoperative blood loss in the observation group was less than that in the control group [(189.26 ± 48.15) mL vs. (96.47 ± 40.21) mL, t = -11.93, P < 0.001]. Incision length, operative time, and time to fracture healing in the observation group were significantly shorter than those in the control group [(4.03 ± 1.48) cm vs. (12.16 ± 1.55) cm, (72.13 ± 28.75) minutes vs. (120.34 ± 29.01) minutes, (9.89 ± 1.52) weeks vs. (13.63 ± 1.74) weeks, t = -30.59, -9.52, -13.05, all P < 0.001]. At 1 month after surgery, there was no significant difference in Harris hip score between the two groups ( t = 1.28, P > 0.05). At 3 and 6 months after surgery, the Harris hip score gradually increased in the control and observation groups ( F = 13.44, 8.26, both P < 0.001). At 3 and 6 months after surgery, Harris hip scores in the observation group were significantly higher than those in the control group [(85.17 ± 4.29) points vs. (79.50 ± 4.12) points, (95.30 ± 1.04) points vs. (87.69 ± 1.25) points, t = 7.69, 37.73, both P < 0.001]. The incidence of complications in the observation group was significantly lower than that in the control group [1.54% (1/65) vs. 10.77% (7/65), χ2 = 4.80, P = 0.029). Conclusion:Compared with LPFP, PFNA can effectively reduce intraoperative blood loss in older adult patients with femoral intertrochanteric fractures, accelerate the progress of fracture healing, promote the recovery of the hip joint, and has fewer complications. Therefore, PFNA is worthy of popularization.

Modified application of interface screw in femoral side during anterior cruciate ligament reconstruction / 中国骨伤

OBJECTIVE@#To compare clinical effects of the improved interface screw fixation of femoral end of anterior cruciate ligament with classic femoral lateral loop plate fixation.@*METHODS@#A retrospective analysis of 65 patients who underwent arthroscopic anterior cruciate ligament reconstruction from January 2019 to September 2021 were performed. According to the different fixation methods of the femoral side, 35 patients were divided into loop plate fixation(loop plate group), including 27 males and 8 females, aged from 18 to 50 years old with an average of (35.00±7.60) years old;30 patients in interface screw fixation(interface screw group), including 20 males and 10 females, aged from 18 to 50 years old with an average of (32.00±8.50) years old. Hospital stay, hospital expenses, operation time, complications, C-reactive protein at 1, 3, 6 days after operation, and postoperative Lysholm score and International Knee Documentation Committee(IKDC) score at 18 months were compared between two groups.@*RESULTS@#All patients were successfully operated, and obtained follow-up from 18 to 36 months with an average of (25.16±4.50) months. Anterior drawer test and Lachman test of all patients turned to negative. There were no statistical differences in hospital stay, hospital expenses and complications between two groups(P>0.05);operation time in loop plate group was (74.00±6.84) min, and (91.67±6.34) min in interface screw group, and had difference between two groups(P<0.05). C-reactive protein on the 1st and 3rd day after operation was (40.00±10.10), (20.00±8.23) mg·L-1 in loop plate group, and (60.00±8.93), (30.00±8.66) mg·L-1 in interface nail group, had statistical difference between two groups (P<0.05);while there was no difference in C-reactive protein on the 6th day after operation(P>0.05). At 18 months after operation, Lysholm and IKDC scores showed no significant difference between two groups (P>0.05). In loop plate group, medullary enlargement on coronal and sagittal views were (2.75±0.19) mm, (1.55±0.25) mm, and (2.81±0.22) mm, (1.61±0.20) mm in interface screw group, and had statistical difference between two groups(P<0.05).@*CONCLUSION@#In the reconstruction of anterior cruciate ligament, the common interface screw on the femoral side is changed to the sheath interface screw, and intramedullary screw is changed to the compression and fixation of tendon from outside to inside of joint. Although the operation procedure is relatively complicated and operation time is slightly longer, it has advantages of no residual metal foreign body after operation, and clinical effect is no different from classical loop plate suspension fixation, which is still a good choice.

Comparison of clinical effects of two methods for treatment of ankle fracture involving lower tibiofibular syndesmosis with triangular ligament injury / 中国综合临床

Objective:To compare the clinical effects of two methods for the treatment of ankle fracture involving lower tibiofibular syndesmosis with triangular ligament injury.Methods:From January 2019 to November 2022, the data of patients with Weber B and C-type ankle fractures involving lower tibiofibular syndesmosis with triangular ligament injury in Tangshan Second Hospital were analyzed. The patients were divided into observation group (45 cases) and control group (39 cases) according to the principle of comparability between the groups of gender, age, injury cause and injury site, Both the treatment of lower tibiofibular syndesmosis and triangular ligament injury with loop steel plate and the treatment of lower tibiofibular syndesmosis injury with loop steel plate, as well as the full layer repair of triangular ligament with wire anchor nail, were used for treatment. Record and compare the fracture healing time, surgical time, surgical cost, American Orthopedic Foot and Ankle Society (AOFAS) score, Visual Analogue Scale (VAS) score, Tibiofibular Clear Space (TFCS) score Medial clear space (MCS), etc.Results:The fracture healing time in the observation group was (4.36±1.26) months, while the fracture healing time in the control group was (4.08±1.35) months. There was no statistically significant difference between the two groups (t=0.978, P=0.331). The observation group had a surgical time of (85.72±14.54) minutes, while the control group had a surgical time of (109.76±14.02); Observation group surgery cost (37 048±2 299.53) Font: ( t=0.978 p=0.331) Delete ( t=7.706 p<0.001) Delete: yuan, control group surgery cost (39 040.22±2 306.02); The differences between the two groups were statistically significant (t-values were 7.71 and 3.95, respectively, P<0.001). The AOFAS score of the observation group was (81.18±3.77) points, while the AOFAS score of the control group was (81.26±3.91) points; The VAS score of the observation group was 0.90±0.38 points, while the VAS score of the control group was 0.87±0.39 points. There was no statistically significant difference between the two groups ( t=0.09, P=0.926; t=0.39, P=0.698). The observation group had a MCS of (3.46±0.25) mm, while the control group had a MCS of (3.53±0.26) mm; The observation group had TFCS (3.49±0.24) mm, while the control group had TFCS (3.47±0.26) mm. There was no statistically significant difference between the two groups ( t=1.24, P=0.217; t=0.21, P=0.833). Conclusions:Although the patients with ankle fracture involving lower tibiofibular syndesmosis and triangular ligament injury can obtain satisfactory clinical results only by using the looped steel plate or the looped steel plate combined with the cable anchor, the application of the looped steel plate alone can reduce the treatment cost of patients, reduce the difficulty of surgery, and reduce the risk of iatrogenic injury of patients.

Influencing factors of sleep disorders of employees of a steel enterprise / 环境与职业医学

Background Steel workers are exposed to occupational hazardous factors such as dust, noise, and heat, and often work in shifts, making them prone to sleep disorders. Objective To explore potential influencing factors of sleep disorders among workers in a steel enterprise in Gansu Province, and provide a basis for reducing the risk of sleep disorders among them. Methods From January to March 2022, a self-made questionnaire combined with the Pittsburgh Sleep Quality Index (PSQI) were used to investigate the employees of a steel enterprise in Gansu Province. According to their PSQI scores, they were divided into a normal sleep group and a sleep disorder group. The general demographic variables of the two groups were balanced by 1∶1 propensity score matching (PSM). Multiple logistic regression was used to analyze the contributing factors of sleep disorders. Restricted cubic spline (RCS) model was used to analyze potential dose-response relationship between weekly working hours and sleep disorders. Results The prevalence of sleep disorders in the steel workers was 48.06% (6029/12544). After PSM, 5847 pairs were successfully matched, and the distributions of matched variables were well balanced between the two groups. The results of multiple logistic regression showed that hypertension (OR=1.39, 95%CI: 1.24, 1.56), diabetes mellitus (OR=1.34, 95%CI: 1.07, 1.66), three-shift system (OR=1.26, 95%CI: 1.12, 1.41), dust exposure (OR=1.14, 95%CI: 1.01, 1.29), noise exposure (OR=1.23, 95%CI: 1.09, 1.39), heat exposure (OR=1.16, 95%CI: 1.04, 1.29), and work injury (OR=1.22, 95%CI: 1.02, 1.46) increased the risk of sleep disorders. Compared with workers with < 10 years of service, those with 10-20 years (OR=1.31, 95%CI: 1.19, 1.44), 20-30 years (OR=1.34, 95%CI: 1.19, 1.52), and ≥30 years of service (OR=1.35, 95%CI: 1.19, 1.53) had a higher risk of sleep disorders. Compared with non-exercise workers, the risk of developing sleep disorders was lower in workers with occasional exercise (OR=0.61, 95%CI: 0.56, 0.66) and regular exercise (OR=0.55, 95%CI: 0.49, 0.62). The RCS model showed that the weekly working hours and sleep disorders in the steel workers showed a nonlinear dose-response relationship (P<0.05 for overall trend, P<0.05 for nonlinear test). The relationship between weekly working hours and sleep disorders showed a "U" shaped distribution, with a significant increase in the risk of sleep disorders when the weekly working hours exceeded 49 h. Conclusion The non-occupational influencing factors of sleep disorders of employees in the steel enterprise include hypertension, diabetes, physical exercise, and occupational influencing factors include length of service, weekly working hours, shifts, dust exposure, noise exposure, heat exposure, and work injuries. It is recommended to consider both occupational and non-occupational factors to formulate appropriate sleep disorder prevention and control measures for steel employees to reduce the risk of sleep disorders.

Mechanical Properties of Mini-Implants Used in Extra-Radicular Anchorage

ABSTRACT Objective: To evaluate the mechanical properties of mini-implants (MIs) manufactured from stainless steel and compare them with conventional titanium-aluminum-vanadium alloy MIs. Material and Methods: The following groups were formed: G1 (n=24), 8×1.5 mm steel MIs; G2 (n=24), 12×2.0 mm steel MIs; and G3 (n=24), 10×1.5 mm titanium MIs. The 72 MIs were inserted in the infra zygomatic crest region of the maxilla and retromolar trigone in the jaw of 10 pigs. Pull-out, insertion torque, fracture and percussion tests were performed in order to measure the tensile strength, primary stability and fracture strength of MIs. A digital torque gauge was used to measure insertion and fracture torque, a universal mechanical testing machine was used for pull-out testing and a periotest device was used to measure the micromovement of MIs. For morphological and MI component evaluation, scanning electron microscopy (SEM) was performed. D'Agostino & Pearson, Kruskal-Wallis, and Dunn post-hoc and normality tests were used. Results: G2 insertion and fracture torques were significantly higher than G1 and G3 insertion and fracture torques (p<0.05). The pull-out and percussion tests presented similar values among the groups. SEM revealed that the fracture point was predominantly on the fourth thread for steel MIs (G1 and G2) and on the seventh thread for titanium-aluminum-vanadium MIs (G3). Conclusion: The mechanical properties of stainless steel MIs are superior to those of titanium-aluminum-vanadium alloy MIs.