BACKGROUND:The elastic modulus of traditional solid titanium alloy implants is higher than that of human bone,and the resulting"stress shielding"phenomenon may affect the osseointegration of implants.Simultaneously,the wettability of 3D printed titanium alloy surface needs to be improved.OBJECTIVE:To prepare hydrophilic Gyroid implants with excellent biomechanical properties.METHODS:The 3D models of Gyroid implant,solid implant,mandibular bone and crown were established,and the mechanical properties of different implants were analyzed by finite element analysis.The Gyroid structure implant model was imported into the 3D printer to make the Gyroid structure implant materialized,and then the hydrophilic Gyroid structure implant with excellent mechanical properties and surface activity was prepared by sandblasting acid etching and ultraviolet functionalization.The morphology and hydrophilicity of 3D printed Ti6Al4V specimens before and after surface modification were analyzed by scanning electron microscopy and contact angle test.RESULTS AND CONCLUSION:(1)The finite element analysis results showed that under the vertical average bite force,the Gyroid structure could uniformly disperse the load acting on the implant into the entire structure.The load on the solid structure implant could only be dispersed on its outer surface and concentrated in the neck.The maximum equivalent stress of the Gyroid structure implant was 200.67 MPa,which did not exceed 50%of the yield strength of Ti6Al4V material.The maximum equivalent stress of the Gyroid structure implant on the surrounding bone tissue was 24.27 MPa,which was slightly higher than the maximum equivalent stress of the solid structure implant 17.32 MPa,and in the range of 20-60 MPa.The stimulation effect of the Gyroid structure implant on new bone formation was better than that of the solid structure implant.(2)The 3D printing technology could materialize the Gyroid structure implant model.Scanning electron microscopy showed that there were many unmelted spherical metal particles on the surface of the 3D printed Ti6Al4V specimens.After sandblasting and acid etching,a micron-scale mesh pore structure was formed on the surface,and no protruding metal particles were seen.The surface morphology of the superimposed UV functional treatment group was basically consistent with that after sandblasting and acid etching.The contact angle test results showed that the surface hydrophilicity of the specimens treated with ultraviolet functionalization plus sandblasting and acid etching was better than that of the sandblasting and acid etching and non-surface treatment groups.(3)The sandblasting and acid etching technology can remove the weakly connected metal particles on the 3D printed specimen and improve the similarity between the solid model and the design model.On this basis,the ultraviolet functionalization treatment can significantly improve the hydrophilicity of the 3D printed Gyroid structure implant surface without affecting its structure.

BACKGROUND:Porous structures based on triple periodic minimal surfaces are one of the most promising orthopedic biostructures,among which the Gyroid structure is characterized by high specific surface area,high permeability,and zero mean curvature.OBJECTIVE:To screen the wall thickness interval of TC4 bionic bone scaffolds with 4 mm single-cell Gyroid structure matching the elastic modulus range of cancellous bone of the mandible through finite element analysis combined with mechanical compression test testing.METHODS:The finite element model of the 4 mm single-cell Gyroid structure with different wall thickths(0.1,0.2,0.3,0.4,0.5,0.6,0.7,and 0.8 mm)was established.The equivalent elastic modulus of the Gyroid structure was analyzed,and the wall thickness interval of the Gyroid structure matching the elastic modulus range of the maxillary resinous bone was selected with different wall thicknesses of 0.2,0.3,0.4,0.5,0.6,and 0.7 mm,respectively.According to finite element analysis screening results,the material selected was Ti6Al4V.Selective laser melting was used to prepare 3D printed Gyroid structure specimens.The surface treatment was carried out by large-grained sand blasting and acid etching.The elastic modulus and compressive strength of the specimen were tested by mechanical compression experiment.RESULTS AND CONCLUSION:(1)The finite element analysis results showed that the equivalent elastic modulus of the Gyroid structure increased with the increase of wall thickness,and the equivalent elastic modulus of the Gyroid structure with wall thickness of 0.2-0.7 mm was within the range of the elastic modulus of the spongy bone of the mandible(1.5-4.0 GPa),which was used for 3D printing of the Gyroid structure specimen.(2)The mechanical compression test results showed that the elastic modulus and compressive strength of the Gyroid structural specimen increased with the increase of wall thickness,and the elastic modulus of the Gyroid structural specimen with wall thickness of 0.3-0.5 mm was within the range of the elastic modulus of the cancellous bone of the mandible.The compressive strength of the Gyroid specimen with 0.3-0.7 mm wall thickness was consistent with the mechanical properties of the mandible.(3)The results show that the Gyroid structure of 0.3-0.5 mm wall thickness is compatible with the range of elastic modulus of the mandible.

Objective With the gradual advancement of China's lunar exploration program and the construction plan for lunar bases,the technology of docking and assembling mobile lunar modules has become an important means for long-term habitation of lunar mobile modules and the construction of lunar bases in the future.Therefore,the design of flexible docking structures between lunar modules has become an urgent problem to be solved.Methods To address the issue of precise docking of mobile lunar modules on the lunar surface,which is severely affected by the uneven terrain and settlement,this paper proposes a flexible docking segment structure composed of a skin and a skeleton.Results The structure deforms to meet the large tolerance docking range required between lunar mobile modules.In terms of skin design,the docking segment structure uses a variety of composite materials to form a flexible skin to cope with the lunar surface environment problems such as radiation,wide temperature variations,and high-speed meteoroid impacts.In terms of skeleton design,a corrugated skeleton structure scheme is presented.Conclusion Based on Ansys and Adams software,static and dynamic simulation analyses of the skeleton structure were conducted,verifying the feasibility of this structure as a flexible docking structure between lunar modules.

S-methyl-L-cysteine sulfoxide (SMCO) is a non-protein sulfur-containing amino acid with a variety of functions. There are few reports on the enzymes catalyzing the biosynthesis of SMCO from S-methyl-L-cysteine (SMC). In this study, the flavin-containing monooxygenase gene derived from Schizosaccharomyces pombe (spfmo) was heterologously expressed in Escherichia coli BL21(DE3) and the enzymatic properties of the expressed protein were analyzed. The optimum catalytic conditions of the recombinant SpFMO were 30 ℃ and pH 8.0, under which the enzyme activity reached 72.77 U/g. An appropriate amount of Mg²⁺ improved the enzyme activity. The enzyme kinetic analysis showed that the K_m and k_cat/K_m of SpFMO on the substrate SMC were 23.89 μmol/L and 61.71 L/(min·mmol), respectively. Under the optimal reaction conditions, the yield of SMCO synthesized from SMC catalyzed by SpFMO was 12.31% within 9 h. This study provides reference for the enzymatic synthesis of SMCO.
Schizosaccharomyces/genetics* ; Escherichia coli/metabolism* ; Recombinant Proteins/metabolism* ; Cysteine/biosynthesis* ; Mixed Function Oxygenases/metabolism* ; Schizosaccharomyces pombe Proteins/metabolism* ; Oxygenases/metabolism* ; Kinetics

Porcine hemagglutinating encephalomyelitis virus(PHEV)is one of the coronaviruses susceptible to swine populations.The non-structural protein 2(NS2)encoded by its genome is fre-quently deleted during the epidemic transmission of the virus,but its biological significance re-mains unclear.In order to explore the structure and function of the NS2 protein,this study utilized platforms such as ProtParam,TMHMM,NetPhos3.1,and ExPASy to analyze its physicochemical properties,spatial structure,genetic evolution,and post-translational modification characteristics.Meanwhile,the NS2 protein was expressed in eukaryotes and transcriptome sequencing was per-formed to clarify the biological processes it participates in.The results showed that the NS2 protein consists of 233 amino acids,with a molecular weight of 26.735 kDa,and a half-life of approximately 30 hours in mammals.It includes 13 phosphorylation sites,2 N-glycosylation sites,and 1 O-glyco-sylation site,with no signal peptide and strong hydrophilicity.The a-helix accounts for the highest proportion in NS2(43.78％),followed by random coils(36.05％).The homology of the NS2 pro-tein between the epidemic strains PHEV-CC14 and PHEV-JL/2008 in Northeast China is 99.57％.The NS2 protein is widely involved in the regulation of nerve-related functions,such as axon guid-ance and synaptic development.This study preliminarily clarified the biological function of the NS2 protein,providing a new perspective for understanding the pathogenic mechanism of PHEV.

Porcine hemagglutinating encephalomyelitis virus(PHEV)is one of the coronaviruses susceptible to swine populations.The non-structural protein 2(NS2)encoded by its genome is fre-quently deleted during the epidemic transmission of the virus,but its biological significance re-mains unclear.In order to explore the structure and function of the NS2 protein,this study utilized platforms such as ProtParam,TMHMM,NetPhos3.1,and ExPASy to analyze its physicochemical properties,spatial structure,genetic evolution,and post-translational modification characteristics.Meanwhile,the NS2 protein was expressed in eukaryotes and transcriptome sequencing was per-formed to clarify the biological processes it participates in.The results showed that the NS2 protein consists of 233 amino acids,with a molecular weight of 26.735 kDa,and a half-life of approximately 30 hours in mammals.It includes 13 phosphorylation sites,2 N-glycosylation sites,and 1 O-glyco-sylation site,with no signal peptide and strong hydrophilicity.The a-helix accounts for the highest proportion in NS2(43.78％),followed by random coils(36.05％).The homology of the NS2 pro-tein between the epidemic strains PHEV-CC14 and PHEV-JL/2008 in Northeast China is 99.57％.The NS2 protein is widely involved in the regulation of nerve-related functions,such as axon guid-ance and synaptic development.This study preliminarily clarified the biological function of the NS2 protein,providing a new perspective for understanding the pathogenic mechanism of PHEV.

BACKGROUND:The elastic modulus of traditional solid titanium alloy implants is higher than that of human bone,and the resulting"stress shielding"phenomenon may affect the osseointegration of implants.Simultaneously,the wettability of 3D printed titanium alloy surface needs to be improved.OBJECTIVE:To prepare hydrophilic Gyroid implants with excellent biomechanical properties.METHODS:The 3D models of Gyroid implant,solid implant,mandibular bone and crown were established,and the mechanical properties of different implants were analyzed by finite element analysis.The Gyroid structure implant model was imported into the 3D printer to make the Gyroid structure implant materialized,and then the hydrophilic Gyroid structure implant with excellent mechanical properties and surface activity was prepared by sandblasting acid etching and ultraviolet functionalization.The morphology and hydrophilicity of 3D printed Ti6Al4V specimens before and after surface modification were analyzed by scanning electron microscopy and contact angle test.RESULTS AND CONCLUSION:(1)The finite element analysis results showed that under the vertical average bite force,the Gyroid structure could uniformly disperse the load acting on the implant into the entire structure.The load on the solid structure implant could only be dispersed on its outer surface and concentrated in the neck.The maximum equivalent stress of the Gyroid structure implant was 200.67 MPa,which did not exceed 50%of the yield strength of Ti6Al4V material.The maximum equivalent stress of the Gyroid structure implant on the surrounding bone tissue was 24.27 MPa,which was slightly higher than the maximum equivalent stress of the solid structure implant 17.32 MPa,and in the range of 20-60 MPa.The stimulation effect of the Gyroid structure implant on new bone formation was better than that of the solid structure implant.(2)The 3D printing technology could materialize the Gyroid structure implant model.Scanning electron microscopy showed that there were many unmelted spherical metal particles on the surface of the 3D printed Ti6Al4V specimens.After sandblasting and acid etching,a micron-scale mesh pore structure was formed on the surface,and no protruding metal particles were seen.The surface morphology of the superimposed UV functional treatment group was basically consistent with that after sandblasting and acid etching.The contact angle test results showed that the surface hydrophilicity of the specimens treated with ultraviolet functionalization plus sandblasting and acid etching was better than that of the sandblasting and acid etching and non-surface treatment groups.(3)The sandblasting and acid etching technology can remove the weakly connected metal particles on the 3D printed specimen and improve the similarity between the solid model and the design model.On this basis,the ultraviolet functionalization treatment can significantly improve the hydrophilicity of the 3D printed Gyroid structure implant surface without affecting its structure.

BACKGROUND:Porous structures based on triple periodic minimal surfaces are one of the most promising orthopedic biostructures,among which the Gyroid structure is characterized by high specific surface area,high permeability,and zero mean curvature.OBJECTIVE:To screen the wall thickness interval of TC4 bionic bone scaffolds with 4 mm single-cell Gyroid structure matching the elastic modulus range of cancellous bone of the mandible through finite element analysis combined with mechanical compression test testing.METHODS:The finite element model of the 4 mm single-cell Gyroid structure with different wall thickths(0.1,0.2,0.3,0.4,0.5,0.6,0.7,and 0.8 mm)was established.The equivalent elastic modulus of the Gyroid structure was analyzed,and the wall thickness interval of the Gyroid structure matching the elastic modulus range of the maxillary resinous bone was selected with different wall thicknesses of 0.2,0.3,0.4,0.5,0.6,and 0.7 mm,respectively.According to finite element analysis screening results,the material selected was Ti6Al4V.Selective laser melting was used to prepare 3D printed Gyroid structure specimens.The surface treatment was carried out by large-grained sand blasting and acid etching.The elastic modulus and compressive strength of the specimen were tested by mechanical compression experiment.RESULTS AND CONCLUSION:(1)The finite element analysis results showed that the equivalent elastic modulus of the Gyroid structure increased with the increase of wall thickness,and the equivalent elastic modulus of the Gyroid structure with wall thickness of 0.2-0.7 mm was within the range of the elastic modulus of the spongy bone of the mandible(1.5-4.0 GPa),which was used for 3D printing of the Gyroid structure specimen.(2)The mechanical compression test results showed that the elastic modulus and compressive strength of the Gyroid structural specimen increased with the increase of wall thickness,and the elastic modulus of the Gyroid structural specimen with wall thickness of 0.3-0.5 mm was within the range of the elastic modulus of the cancellous bone of the mandible.The compressive strength of the Gyroid specimen with 0.3-0.7 mm wall thickness was consistent with the mechanical properties of the mandible.(3)The results show that the Gyroid structure of 0.3-0.5 mm wall thickness is compatible with the range of elastic modulus of the mandible.

A colon-specific drug delivery system has great potential for the oral administration of colorectal cancer. However, the uncontrollable in vivo fate of liposomes makes their effectiveness for colonic location, and intratumoral accumulation remains unsatisfactory. Here, an oral colon-specific drug delivery system (CBS-CS@Lipo/Oxp/MTZ) was constructed by covalently conjugating Clostridium butyricum spores (CBS) with drugs loaded chitosan (CS)-coated liposomes, where the model chemotherapy drug oxaliplatin (Oxp) and anti-anaerobic bacteria agent metronidazole (MTZ) were loaded. Following oral administration, CBS germinated into Clostridium butyricum (CB) and colonized in the colon. Combined with colonic specifically β-glucosidase responsive degrading of CS, dual colon-specific release of liposomes was achieved. And the accumulation of liposomes at the CRC site furtherly increased by 2.68-fold. Simultaneously, the released liposomes penetrated deep tumor tissue via the permeation enhancement effect of CS to kill localized intratumoral bacteria. Collaborating with blocking the translocation of intestinal pathogenic bacteria from lumen to tumor with the gut microbiota modulation of CB, the intratumoral pathogenic bacteria were eliminated fundamentally, blocking their recruitment to immunosuppressive cells. Furtherly, synchronized with lipopolysaccharide (LPS) released from MTZ-induced dead Fusobacterium nucleatum and the tumor-associated antigens produced by Oxp-caused immunogenic dead cells, they jointly enhanced tumor infiltration of CD8⁺ T cells and reactivated robust antitumor immunity.

Objective To investigate the effect of different premolar extraction patterns on Bolton index and occlusal relationship of skeletal Class Ⅱmalocclusion.Methods The plaster models of 62 patients with skeletal ClassⅡmalocclusion were selected and con-verted into digital models by iTeroElement scanner.Each model was simulated by the four premolar extraction pattrens,and tooth ar-rangement test was performed after tooth extraction.The Bolton index before and after tooth extraction was calculated,and the occlusal relationship after tooth arrangement was evaluated to explore its law.Results All the four premolar extraction patterns resulted in a significant decrease in the Bolton index over-all ratio in skeletal ClassⅡpatients,and compared with the extraction patterns of 4/4 and 4/5,the patterns of 5/4 and 5/5 resulted in a greater decrease in the Bolton index over-all ratio(P＜0.001).For skeletal classⅡmal-occlusion,the tooth arrangement test was conducted on the basis of establishing the neutral relationship of first molar.The average value of anterior teeth over-jet obtained by patterns of 4/4 and 4/5 was within the normal range(＜3 mm).The average value obtained by pat-terns of 5/4 and 5/5 was greater than the normal range(＞3 mm),and the difference was statistically significant(P＜0.001).Conclu-sion The premolar extraction patterns of 4/4 and 4/5 are more conducive to normalizing the Bolton index over-all ratio and establis-hing the better occlusal relationship for skeletal Class Ⅱ malocclusion.