Theoretical and Experimental Study on the Performance of Hermetic Diaphragm Squeeze Film Dampers for Gas-Lubricated Bearings

Low damping characteristics have always been a key sticking points in the development of gas bearings.The application of squeeze film dampers can significantly improve the damping performance of gas lubricated bearings.This paper proposed a novel hermetic diaphragm squeeze film damper(HDSFD)for oil-free turbomachinery supported by gas lubricated bearings.Several types of HDSFDs with symmetrical structure were proposed for good damping performance.By considering the compressibility of the damper fluid,based on hydraulic fluid mechanics theory,a dynamic model of HDSFDs under medium is proposed,which successfully reflects the frequency dependence of force coefficients.Based on the dynamic model,the effects of damper fluid viscosity,bulk modulus of damper fluid,thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were analyzed.An experimental test rig was assembled and series of experimental studies on HDSFDs were conducted.The damper fluid transverse flow is added to the existing HDSFD concept,which aims to make the dynamic force coefficients independent of frequency.Although the force coefficient is still frequency dependent,the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid supply.The results serve as a benchmark for the calibration of analytical tools under development.

Effects of mesenchymal stem cell on dopaminergic neurons,motor and memory functions in animal models of Parkinson's disease:a systematic review and meta-analysis

Parkinson’s disease is chara cterized by the loss of dopaminergic neurons in the substantia nigra pars com pacta,and although restoring striatal dopamine levels may improve symptoms,no treatment can cure or reve rse the disease itself.Stem cell therapy has a regenerative effect and is being actively studied as a candidate for the treatment of Parkinson’s disease.Mesenchymal stem cells are considered a promising option due to fewer ethical concerns,a lower risk of immune rejection,and a lower risk of teratogenicity.We performed a meta-analysis to evaluate the therapeutic effects of mesenchymal stem cells and their derivatives on motor function,memory,and preservation of dopamine rgic neurons in a Parkinson’s disease animal model.We searched bibliographic databases(PubMed/MEDLINE,Embase,CENTRAL,Scopus,and Web of Science)to identify articles and included only pee r-reviewed in vivo interve ntional animal studies published in any language through J une 28,2023.The study utilized the random-effect model to estimate the 95%confidence intervals(CI)of the standard mean differences(SMD)between the treatment and control groups.We use the systematic review center for laboratory animal expe rimentation’s risk of bias tool and the collaborative approach to meta-analysis and review of animal studies checklist for study quality assessment.A total of 33studies with data from 840 Parkinson’s disease model animals were included in the meta-analysis.Treatment with mesenchymal stem cells significantly improved motor function as assessed by the amphetamine-induced rotational test.Among the stem cell types,the bone marrow MSCs with neurotrophic factor group showed la rgest effect size(SMD[95%CI]=-6.21[-9.50 to-2.93],P=0.0001,I^(2)=0.0%).The stem cell treatment group had significantly more tyrosine hydroxylase positive dopamine rgic neurons in the striatum([95%CI]=1.04[0.59 to 1.49],P=0.0001,I^(2)=65.1%)and substantia nigra(SMD[95%CI]=1.38[0.89 to 1.87],P=0.0001,I^(2)=75.3%),indicating a protective effect on dopaminergic neurons.Subgroup analysis of the amphetamine-induced rotation test showed a significant reduction only in the intracranial-striatum route(SMD[95%CI]=-2.59[-3.25 to-1.94],P=0.0001,I^(2)=74.4%).The memory test showed significant improvement only in the intravenous route(SMD[95%CI]=4.80[1.84 to 7.76],P=0.027,I^(2)=79.6%).Mesenchymal stem cells have been shown to positively impact motor function and memory function and protect dopaminergic neurons in preclinical models of Parkinson’s disease.Further research is required to determine the optimal stem cell types,modifications,transplanted cell numbe rs,and delivery methods for these protocols.

Advances in viral encephalitis:Viral transmission,host immunity,and experimental animal models

Viral infections have led to many public health crises and pandemics in the last few centuries.Neurotropic virus infection-induced viral encephalitis(VE),especially the symptomatic inflammation of the meninges and brain parenchyma,has attracted growing attention due to its high mortality and disability rates.Understanding the infectious routes of neurotropic viruses and the mechanism underlying the host immune response is critical to reduce viral spread and improve antiviral therapy outcomes.In this review,we summarize the common categories of neurotropic viruses,viral transmission routes in the body,host immune responses,and experimental animal models used for VE study to gain a deeper understanding of recent progress in the pathogenic and immunological mechanisms under neurotropic viral infection.This review should provide valuable resources and perspectives on how to cope with pandemic infections.

Preclinical in vivo research of magnesium-based implants for fracture treatment: A systematic review of animal model selection and study design

Background:Degradable magnesium implants are promising for clinical fracture treatment,providing less stress-shielding mechanical support and superior bone-strengthening benefits to traditional materials.The quality of preclinical research is essential for developing Mg implants;however,there are considerable variations in the model selection and study design in published studies,posing challenges for safe and effective clinical translation of lab discoveries.Objective:The purpose of this systematic review is to investigate the current progress on in vivo research of Mg implants for fracture treatment,focusing on model selection,Mg materials,implant design,methodological and analyzing techniques,aiming to provide comprehensive guidance for future preclinical research.Materials and methods:Pub Med and Embase online databases were searched to identify researches investigating Mg implants in animal models of fracture from 1960 to December 2019,using a combination of keywords:magnesium and fracture.Eligible studies were included without language restriction.Data extraction was conducted for qualitative analysis.Meta-analysis was not performed due to extensive heterogeneities among studies.Results:Twenty studies published from 2014 to 2019 were included.Publication information,animal model,methodological quality,implants preparation,and evaluation techniques were extracted.The methodological assessment revealed low to high risk of bias among studies.Both rodent and non-rodent species were selected,and the anatomical sites for inducing fractures included both cranial-facial and limb bones.Pure Mg and alloys with or without surface modification were evaluated,covering implant designs of both intra-medullary and extra-medullary fixation.Radiological and histological evaluations were commonly conducted.Conclusions:Published in vivo evidence confirmed the role of Mg-based implants in promoting fracture healing.However,considering heterogeneity in animal selection,implant preparation,and evaluation methods,there still lacks a standardized reference model.By analyzing the information extracted from included studies,the systematic review may facilitate planning and conducting preclinical research with translational perspective.

Standardization of experimental animals temporal bone sections

Preparation of the temporal bone for light microscopy is an important step in histological studies of the inner ear. Due to the complexity of structures of the inner ear, it is difficult to measure or compare structures of interest without a commonly accepted standardized measure of temporal bone sections. Therefore, standardization of temporal bone sections is very important for histological assessment of sensory hair cells and peripheral ganglion neurons in the cochlear and vestibular systems. The standardized temporal bone sectioning is oriented to a plane parallel to the outer and internal auditory canals. Sections are collected from the epitympanum to the hypotympanum to reveal layers in the order of the crista ampullaris of the superior and lateral semicircular canals, macula utriculi and macula sacculi, superior vestibular ganglion neurons, macula of saccule and inferior vestibular ganglion neurons, cochlear modiolus, endolymphatic duct and endolymphatic sac, and finally the crista ampullaris of the posterior semicircular canal. Moreover, technical details of preparing for temporal bone sectioning including fixation, decalcification, whole temporal bone staining, embedding penetration, and embedding orientation are also discussed.

An Experimental Study of Bulge-Forming Polycarbonate (PC)Semisphere Shell Parts

In this paper, a new bulge-forming technology is described to manufacture a polycarbonate semisphere shell. Some experiments have been done, and the experimental results show that this technique is feasible to form polycarbonate part. But the wall thickness distribution of the bulged specimen by this method is not so even.

Clinical and Experimental Study on Effect of Garlicin in Treating Angina Pectorls

Objective: To observe the effect and mechanism of Garlicin in treating coronary heart disease (CHD) with angina pectoris. Methods: Clinical study: 55 patients were selected and randomized into the Garlicin group and the nitroglycerin group. To Garlicin group, 60 mg of Garlicin was given by adding in 5% glucose solution for intravenous dripping once per day, the therapeutic course

An Experimental Study on Atmospheric Pressure Glow Discharge in Different Gases

Usually, the electrical breakdown of dielectric barrier discharge (DBD) at atmo-spheric pressure leads to a filamentary non-homogeneous discharge. However, it is also possible to obtain a diffuse DBD in homogeneous form, called atmospheric pressure glow discharge (APGD). We obtained a uniform APGD in helium and in the mixture of argon with alcohol, and studied the electrical characteristics of helium APGD. It is found that the relationship between discharge current and source frequency is different depending on the difference in gas gap when the applied voltage is kept constant. The discharge current shows an increasing trend with the increased frequency when gas gap is 0.8 cm, but the discharge current tends to decrease with the increased frequency when the gas gap increases. The discharge current always increases with the increased applied voltage when the source frequency is kept constant. We also observed a glow-like discharge in nitrogen at atmospheric pressure.

Animal experimental studies using small intestine endoscope

AIM To assess the feasibility and safety of a novel enteroscope,negative-pressure suction endoscope in examining the small intestine of a porcine model.METHODS In vitro experiments in small intestinal loops from 20pigs and in vivo experiments in 20 living pigs were conducted.RESULTS In in vitro experiments,a negative pressure of>0.06MPa was necessary for optimal visualization of the intestine,and this pressure did not cause gross or histological damage to the mucosa.For satisfactory examination of the small intestine in vivo,higher negative pressure(>1.00 MPa)was required.Despite this higher pressure,the small intestine did not show any gross or microscopic damage in the suctioned areas.The average time of examination in the living animals was 60±7.67 min.The animals did not experience any apparent ill effects from the procedure.CONCLUSION Small intestine endoscope was safely performed within a reasonable time period and enabled complete visualization of the intestine in most cases.

Numerical and Experimental Study of the 3D Effect on Connecting Arm of Vertical Axis Tidal Current Turbine

Vertical axis tidal current turbine is a promising device to extract energy from ocean current. One of the important components of the turbine is the connecting arm, which can bring about a significant effect on the pressure distribution along the span of the turbine blade, herein we call it 3D effect. However, so far the effect is rarely reported in the research, moreover, in numerical simulation. In the present study, a 3D numerical model of the turbine with the connecting arm was developed by using FLUENT software compiling the UDF（User Defined Function） command. The simulation results show that the pressure distribution along the span of blade with the connecting arm model is significantly different from those without the connecting arm. To facilitate the validation of numerical model, the laboratory experiment has been carried out by using three different types of NACA aerofoil connecting arm and circle section connecting arm. And results show that the turbine with NACA0012 connecting arm has the best start-up performance which is 0.346 m/s and the peak point of power conversion coefficient is around 0.33. A further study has been performed and a conclusion is drawn that the aerofoil and thickness of connecting arm are the most important factors on the power conversion coefficient of the vertical axis tidal current turbine.

Preparation of Filling Porous Osteoconduction Materials and Its Animal Experiment Study

Titanium rods were processed into implant samples with cavity and groove in which was filled with HAP/β-TCP porous osteoconduction composite materials in order to increase the mechanical stability of the implant in vivo.The phase compositions of the composite was characterized by X-ray diffraction （XRD） and scanning electron microscopy（SEM）.Histological evaluation showed that the biogradable composite could enhanced the ability of new bone formation.The composite can conduct new bone tissue growing into the cavities gradually after implanted into animal,and then achieve mechanical fixation.The filling biogradable compound exhibited excellent biocompatibility,which combined with the new bone tissues tightly without inflammation and loosing.

Retrieval,reporting and methodological characteristics for systematic reviews/meta-analyses of animal models:a meta-epidemiological study

The study aimed to analyze the reporting and methodological quality of systematic reviews(SRs)/meta-analyses(MAs)of animal models to provide references for later studies and avoid the waste of medical resources.EMBASE and MEDLINE databases were searched from inception to November 2017,with no language restriction.Two reviewers selected inclusion dependently and extracted the basic characteristics.Review Manager 5.3,stata 12.0,and SPSS 21 software were used to conduct analyses.A total of 46 SRs/MAs were included.The results showed that the English databases with high retrieval frequency are PubMed/MEDLINE,EMBASE,and Web of Science.67.31%(31/46)of the articles reported the search strategy in the full text or the appendix.65.22%(30/46)reported the literature screening flow diagram,and only 19.57%(9/46)reported the number of works of literature retrieved in each database.60.87%(28/46)illustrated supplement retrieval.Through 2 subgroup analyses,it was found that there were no significant differences in the quality of reports of PRISMA items.But referring to the methodological quality or reporting of PRESS items,SCI was better than that of non-SCI,while there seemed a source of funding to have no significant impact on the methodological quality or the items of PRESS.The results of PRESS,AMSTAR 2,and PRISMA were correlated,and the correlation between PRISMA and AMSTAR 2 was strong.These results demonstrated that search strategies of animal model SRs/MAs are still not enough comprehensive,report specification and methodological quality still need to be ameliorated.To show users the scientificity and rigor of the study,future research should focus on these various guidelines like PRESS,PRISMA,and AMSTAR 2 checklists that have been issued,it can help to increase the value of research and improve the utilization of medical resources.

An Experimental Study of Thermophysical Properties for Quinary High-Entropy NiFeCoCrCu/Al Alloys

Two quinary high-entropy alloys （HEAs） with equiatomic concentrations formed by doping either Cu or A1 elements into the quaternary NiFeCoCr alloy are produced by arc melting and spray casting techniques. Their entropy of fusion, thermal expansion coefficient and thermal diffusivity are experimentally investigated with differential scanning cMorimetry, dilatometry and laser flash methods. The NiFeCoCrCu HEAs contain a face- centered cubic high-entropy phase plus a minor interdendritic （Cu） phase and display a lower entropy of fasion and the Vickers hardness. The NiFeCoCrAl HEAs consist of two body-centered cubie high-entropy phases with coarse dendritic structures and show higher entropy of fusion and the Vickers hardness. Both the thermal expansion coefficient and the thermal diffusivity of the former Cu-doped alloy are signitieantly larger than those of the latter At-doped M1oy. Although the temperature dependence of thermal diffusivity is similar for both HEAs, it is peculiar that the thermal expansion curve of the NiFeCoCrAl alloy exhibits an inflexion at temperatures of 860-912 K.

PROTECTIVE EFFECT OF SHENG MAI SAN ON ADRIAMYCIN-INDUCED CARDIOTOXICITY——AN EXPERIMENTAL STUDY

By measuring the contents of lipid-bound sialic acid (LSA), malonyldialdehyde (MDA), activities of glutathione peroxidase (GSH-px) and superoxide dismutase (SOD) of the myocardial cells, it has been shown that Sheng Mai San can protect the myocardial cells from the adriamycin-induced cardiotoxicity ultrastructrally, inhibit their metabolism of lipid-bound sialic acid and improve the scavenging ability of myocardial cells for semiquinoid free radicals.

An Experimental Study on Somatostatin Receptors in the Brains of Hepatic Encephalopathy Rats

The present study was undertaken to evaluate the effect of somatostatin (SS) receptor,a brain-gut peptide receptor which is capable of inhibiting central neurons, on the pathogenesis of hepatic encephalopathy (HE).By means of radioligand binding assay, SS receptors in crude synaptosomal membrane of rat brains were investigated in a rat model of HE induced by partial hepatectomy following carbon tetrachloride intoxication and in controls. Binding to SS receptor was studied using125 I-SS as radiolgand Scatchard analysis of binding data was linear, yielding a dissociation constant (Kd) of 3.99 ±0.22 nmol/L and a maximal binding capacity (Bmax) of 238± 14.2 fmol/mg of protein in HE rats.Only increased Bmax values were observed (P< 0.005),while the Kd values were statistically unchanged (P>0.50),in HE rats as compared with those in controls.The results suggest that the changes of SS receptors in brains play a significant role in the pathogenesis of HE.The mechanism of HE induced by the alterations of SS receptors in the brains was discussed in this paper.

Clinical application of full automatic animal experimental cabin of normobaric/hypobaric hypoxia and high carbon dioxide

To explore the feasibility of the full automatic animal experimental cabin to establish the animal models in normobaric/hypobaric hypoxic and high carbon dioxide environment. Methods： Sixty SPF-class male DS rats were divided into 2 groups, 20 for normobaric, hypoxic conditions and the other 40 for hypobaric, hypoxic conditions. For each group, the pulmonary arterial pressure and carotid arterial pressure indicators of rats were examined by using the physiological multi-detector, and the pulmonary vascular changes in the structure were observed. Results： The normobaric/hypobaric hypoxic with high carbon dioxide environment can promote the formation of pulmonary hypertension and accelerate changes in pulmonary vascular remodeling, and promote the right ventricular hypertrophy. Conclusion： Clinical applications showed that the animal experimental cabin has observed and controlled accurately. The result was safe, reliable and reproducible. The cabin can successfully establish the pulmonary hypertension model in normobaric/hypobaric hypoxic with high carbon dioxide environment, and in order to study the physiological mechanism of a variety of circulation and respiratory diseases caused by lack of oxygen, which provided an experimental technology platform for clinical research.

Congratulations to the new journal: Animal Models andExperimental Medicine

I would like to extend my best congratulations to all concerned for the publication of the inaugural issue of Animal Models and Experimental Medicine (AMEM), an English journal published jointly by the Chinese Association for Laboratory Animal Sciences (CALAS) and the Institute of Laboratory Animal Sciences of Chinese Academy of Medical Sciences & Peking Union Medical College. Basic medical research has been at the forefront of science and technology development. Essential to that, laboratory animal science is of foundamental importance in biomedical research, providing key advantages in understanding mechanisms of health and disease without posting actual risks to human beings.

Ideas for Hypertensive Experimental Study Prevented and Treated by TCM

Hypertensive ex—perimental studies pre—vented and treated byTCM are matured re|e—rant studies of westernmedicine for reference,such as the hypotensiveeffect and elucidating itstherapeutic mechanism.Comprehension in allliteratures,most simpleherbs and compound

Announcing the launch of a new journal: Animal Models andExperimental Medicine

In the Chinese Year of the Dog,we are pleased to present to you the first issue of the new journal we have organized:Animal Models and Experimental Medicine(AMEM).Why do we need a new journal in this area?Laboratory animal sciences is an emerging interdisciplinary subject,which integrates theories and methods from many disciplines,including biology,medicine,pharmacy,veterinary,bioengineering,biomedical engineering,etc.In recent years,many outstanding papers based on laboratory animals have been published around the world,highlighting how laboratory animal sciences has,among other things,provided systematic biological materials and pertinent technologies for the development of related disciplines;integration into many frontier disciplines;development of new disciplines such as comparative medicine,experimental animal medicine,and comparative biology;and supported development in fields such as life sciences,medicine,food,environment and aerospace.However,there are very few specialized journals in this field,and their impact is very limited.Therefore,it is urgent to establish a professional English-language journal to meet the need of all researchers in this important field.

Effect of Intrahepatic Arterial Delivery of Sorafenib on Normal Liver Tissue of Rabbit:An Experimental Study

Objective:To assess the safety,feasibility and eluting efficiency of intrahepatic arterial delivery of sorafenib on normal liver tissue of rabbit.Methods:24 New Zealand rabbits were randomly divided into three groups:group I(Lipiodol-sorafenid),group II(Lipiodol)and group III(Sorafenib).Group I and II were treated by transcatheter selective hepatic arterial embolization with emulsions of lipiodol and sorafenib or with only lipiodol,while group III was given hepatic arterial infusion with sorafenib.Sorafenib concentration in plasma was determined by HPLC(high performance liquid chromatography)in 0 min,20 min,1h,2h,4h,8h,16h,32h and 48h respectively.The breathing rate,heart rate,rectal temperature and body weight were measured,as well the blood routine test and the function of liver,kidney,and heart.Two animals of each group were respectively killed in the 3rd day,1st,3rd and 6th week after treatment.Histopathologic study was done to liver,heart,kinney,lung,brain,gall bladder and intestine.Result:①The peak sorafenib concentration(Cmax)and AUC(Area under curve)in plasma in group I was 2.46±0.101μg/ml and 945.72±52.3μg/mL.min respectively,while in group III which was 3.78±0.180 ug/ml and 546.98±21.1μg/mL.min.Compared with group III,the Cmax and AUC of group I had a significant statistics difference(p<0.05).②The breathing rate,heart rate,rectal temperature and AST/ALT,WBC,NEU%of group I and group III has a significant statistics difference(p<0.05)in the 3rd day.③CK,CK-MB,DB,Cr,BUN,RBC,PLT in plasma did not change in all group.④Local necrosis was seen in group I and group II in the 3rd day and 1st week,but they did not seem to be different.Group III showed no necrosis.Granulation tissue with bile duty,portal vein and microfossils hyperplasia were seen in local necrosis area in the 3rd week.No pathological changes were found in brain,heart,kidney,intestine and gallbladder.Conclusion:TAE with emulsions of lipiodol and sorafenib is feasible,safe and has some slow-release effect.