Frozen Research Articles

無容器プロセスを用いたFe-Cu二相分離合金の凝固過程と微細構造

無容器プロセスを用いたFe-Cu二相分離合金の凝固過程と微細構造

Frozen in a tube

Frozen in a tube

SYSTEMATIZATION OF PHYSICAL PROPERTIES POLYTHERMS OF METALLIC MELTS

The analysis of the research results of temperature dependences of the kinematic viscosity, electrical resistivity, surface tension and density of liquid steels and alloys during heating and the subsequent cooling was performed. The identifi ed characteristics formed the basis for systematization of physical properties polytherms of steels and alloys. It was established that the changes occur in the melt structure during heating up to certain critical temperatures. As a result, the cooling polytherms acquire a diff erent view, more close to equilibrium classical patterns and do not coincide with heating polytherms. The branching of the temperature dependences of the physical properties or hysteresis of polytherms is irreversible only when heating up to a temperature not lower than the critical ones. If these conditions are not met the partial or full return to the primary structure of melt can occur and it has an impact on the value of the polytherms hysteresis. Therefore, the hysteresis value, along with the data on the properties, is a qualitative characteristic of the melt structure and its deviations from the equilibrium and micro homogeneous state. The uniformity of distribution of alloying elements atoms into micro groups or clusters indicates the equilibrium of the structure and uniformity of clusters distribution, diff erent in structure in the melt volume, refl ects its structural micro-homogeneity. In the process of studying the properties of multicomponent metal materials it was found that after melting the change of melt properties at isothermal holding is a typical pattern of damped oscillations. With the increase of temperature the damping mode approaches the aperiodic one, and the relaxation time decreases. The processes responsible for kinetics of isothermal change in the melt properties occur at the micro level. Non-equilibrium industrial metal typically contains inclusions from the initial materials in the form of undissolved particles of graphite in the cast iron, association and aggregation of carbides, nitrides, etc. Bringing such melt into equilibrium state requires a lot of time, normally much more than for the diff usion transfer of atoms within the disbalanced zones. The more complex is the chemical and structural interactions of solid metal, the greater is the separation between the equilibrium and the obtained melt. In such system the new correlations are formed and broken most intensely. In this case the cooperative processes of interaction of new spatial and temporal structures with inherited from the initial materials take place occur, which is refl ected by oscillating dependences of the properties of metal melts. The information about the state of the melt prior to solidifi cation enables a scientifi c foundation for temperature and time regimes of smelting of steel and alloys. Such melt preparation aff ects its capacity for supercooling, the crystallization rate and the formation of eutectic reinforcing phases, elements segregation, dendrites structure and zonal structure of castings, and in general – the quality and effi ciency of steel production.

Discussion on applying an analytical method to optimize the anti-freeze design parameters for underground water pipelines in seasonally frozen areas

Adopting the quasi-three-dimensional (Quasi-3D) numerical method to optimize the anti-freeze design parameters of an underground pipeline usually involves heavy numerical calculations. Here, the fitting formulae between the safe conveyance distance (SCD) of a water pipeline and six influencing factors are established based on the lowest water temperature (LWT) along the pipeline axis direction. With reference to the current widely used anti-freeze design approaches for underground pipelines in seasonally frozen areas, this paper first analyzes the feasibility of applying the maximum frozen penetration (MFP) instead of the mean annual ground surface temperature (MAGST) and soil water content (SWC) to calculate the SCD. The results show that the SCD depends on the buried depth if the MFP is fixed and the variation of the MAGST and SWC combination does not significantly change the SCD. A comprehensive formula for the SCD is established based on the relationships between the SCD and several primary influencing factors and the interaction among them. This formula involves five easy-to-access parameters: the MFP, buried depth, pipeline diameter, flow velocity, and inlet water temperature. A comparison between the analytical method and the numerical results based on the Quasi-3D method indicates that the two methods are in good agreement overall. The analytic method can be used to optimize the anti-freeze design parameters of underground water pipelines in seasonally frozen areas under the condition of a 1.5 safety coefficient.

Calculation method for thickness of discontinuous boundary layer of engineering pavement

The boundary layer is a buffer layer of water and heat exchange between the atmosphere and permafrost. Based on the atmospheric boundary layer and heat transfer theory, we established a method for determining the boundary layer thickness of engineering pavement (asphalt and sand pavement) in permafrost region. The boundary layer can be divided into the Boundary Layer Above Surface (BLAS) and the Boundary Layer Below Surface (BLBS) . From in-situ monitoring data, the thickness of BLAS was determined through the laminar thickness, and the thickness of BLBS was determined through ground temperature, the heat conduction function, and the mean attenuation function ( α ) . For asphalt pavement, the BLAS thickness varied between 2.90 and 4.31 mm and that of BLBS varied between 28.00 and 45.38 cm. For sand pavement, the BLAS thickness varied between 2.55 and 3.29 mm and that of BLBS varied between 15.00 and 46.44 cm. The thickness varied with freezing and thawing processes. The boundary layer calculation method described in this paper can provide a relatively stable boundary for temperature field analysis.

The preparation of human serum based reference materials for alpha-fetoprotein assay through quantity value transmission from multiple analysis systems

Objective To prepare the frozen human serum pools for AFP reference materials through quantity value transmission from several analysis systems. Methods Method establishment. According to the requirement of preparation for the national standard materials, the studies of homogeneity and stability of frozen human serum pools for AFP reference materials were carried out. The commutability of prepared AFP reference materials and WHO AFP 72/225 reference material were assessed.By use of four automated chemiluminescence analysis systems, the prepared reference materials and different dilutions of WHO reference material 72/225 were tested in the same run.The values of prepared AFP reference materials were assigned by comparing these results and the uncertainty was evaluated. Results The three levels of AFP reference materials were tested to be homogeneous. The long term stability had been observed at -80 ℃ for 14 months.The different dilutions of WHO AFP 72/225 reference material and three levels of prepared reference materials were commutable with patient serum samples among the four analysis systems.Through multiple system quantity value transmission and total uncertainty evaluation, the assigned values (IU/ml) of three levels of AFP reference materials were 23.0±3.0, 93.2±7.2, (26.1±2.4)×102 respectively. Conclusions The three levels of AFP reference materials were homogeneous and stable in accordance with requirement of preparation for national standard materials.The assigned values were reliable.The materials showed accepted commutability across 4 analytical systems.These materials had been approved as the national certified reference materials.These reference materials could be applied for the calibration or calibration verification of clinical analytical systems and the external quality assessment schemes for clinical laboratories.(Chin J Lab Med, 2016, 39: 930-935) Key words: alpha-fetoproteins; Reference standards; Reference values

Investigation and analysis of internal quality control on clinical chemistry, clinical immunology and clinical hematology of mutual recognition laboratories in 142 medical institutions in Beijing

Objective To investigate the internal quality control (IQC) on clinical chemistry, clinical immunology and clinical hematology in mutual recognition laboratories in medical institutions in Beijing. Methods By means of questionnaire survey and on-site investigation, fresh frozen serum and whole blood samples with assigned values by reference method were measured to investigate the status of IQC on clinical chemistry, clinical immunology and clinical hematology in 142 mutual recognition laboratories in medical institutions of Beijing, and results were analyzed. Results 142 copies of questionnaireson clinical chemistry, clinical immunology and clinical hematology were send out and 120, 97, and 101 laboratories returned the questionnaires respectively .The information feedback rate was 84.5%, 68.3% and 71.1% respectively.All the questionnaires were effective. Questionnaires survey results showed that more than 50% laboratories set up quality control goals and the most of the goals were probability for error detection (Ped) 95%, probability for false rejection(Pfr)5%; About 70% laboratories usecd the same quality control plan for different tests ; The most frequently used quality control rules are 12s/13s/22s. On-site investigation showed that , take the results of clinical chemistry for example, based on the desirable biological variation and WS/T 403-2012 , most of the tests can't meet the quality control goalsunder the existing quality control condition. Conclusion Clinical laboratories should consider their actual situations, assess their own quality levels that they can reach , set reasonable quality standards for themselves , and make appropriate individualized quality control plan. (Chin J Lab Med, 2016, 39: 922-929) Key words: Clinical chemistry tests; Immunologic tests; Hematologic tests; Quality control

Antioxidative Effect of Dietary Tea Catechins on the Quality of Enulsified Pork Meatballs under Refrigeration

After meat products are heated and placed in storage, the lipid contained inside undergoes oxidation, which causes the meat to become malodorous and reduces its acceptability in the market. In this study, catechin was added to emulsified pork meatballs in the hope of reducing lipid oxidation. The influence that catechin additions at different concentrations (0, 400 and 800 ppm) have on the pH value, color, texture profiles, microbial testing, sensory analysis, thiobarbituric acid reactive substance value, and antioxidant capacity of the emulsified pork meatball is investigated in this study. The test results on lipid oxidation indicated that after 15 days of refrigerated storage at 4°C, oxidation in the control group was 2.46 mg malondialdehyde equal (MDA eq.)/kg meatball. The 400 ppm and 800 ppm of catechin-treated groups yielded 0.56 and 0.31 mg MDA eq./kg, respectively, which were significantly lower than the control group. The results were similar after 90 days of frozen storage at -20°C, where the 400 ppm and 800 ppm of catechin-treated groups yielded 0.60 and 0.25 mg MDA eq./kg, respectively, which were significantly lower than the oxidation level in the control group (1.39 mg MDA eq./kg). Regarding the antioxidant capacity tests, the meatballs that were treated with 400 ppm and 800 ppm of catechin displayed a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity of 1.31 and 1.97 mg of ascorbic acid/g, respectively, whereas the total antioxidant capacity was 2.63 and 4.53 mg of Trolox/g, respectively. The results of both groups were significantly higher than the DPPH radical scavenging capacity (0.07 mg as ascorbic acid/g) and the total antioxidant capacity (0.36 mg as Trolox/g) of the control group. After 90 days of frozen storage at -20°C, the antioxidant capacity of catechin-treated groups were still higher than the control group. The mentioned results indicate that adding catechin to emulsified pork meatballs inhibits lipid oxidation and can help boost the quality and functionality of these emulsified pork meatball products.

Expression and clinical significance of microRNA-126-3p in breast carcinomas with different immunohistochemical profiling

Objective To investigate the expression of microRNA (miRNA, miR)-126-3p in breast carcinomas with four different immunohistochemical profiling and their relevance to clinicopathologic features. Methods The expression of miR-126-3p was detected by real-time fluorescent quantitative polymerase chain reaction (FQ-PCR) in 67 paired frozen breast carcinomas tissues and further detected by TMA-ISH in 140 cases of formalin fixed paraffin-embedded (FFPE) breast carcinomas tissues. Results MiR-126-3p expression level was lower in carcinoma tissues than that in paired para-cancerous tissues, and lowest in triple-negative breast cancer (TNBC) immune phenotype without significant difference using FQ-PCR method. The results of TMA-ISH showed that miR-126-3p was mainly expressed in stroma of tumor tissue, and its expression level was higher in tumor tissue than that in breast fibroadenomas (χ2=21.48, P<0.01). Triple-negative breast cancers in stroma showed the lowest miR-126-3p expression level (high expression rate of 60%), and human epidermal growth factor receptor-2 (Her-2) over-expressed group showed the highest expression level (high expression rate of 91.3%) within four subtypes, which had the significant differences (χ2=6.26; P<0.05). Furthermore, strong miR-126-3p expression was significantly associated with Her-2 expression (χ2=5.73, P<0.05). Conclusion There was a difference in the miR-126-3p expression in breast tumor between different immune phenotypes, which may be used as a potential individual diagnostic and drug target for breast cancer patients. Key words: Breast carcinoma; MicroRNA-126-3p; Human epidermal growth factor receptor-2 over-expression

Condensed-matter physics: Frozen bismuth superconducts.

Condensed-matter physics: Frozen bismuth superconducts.

Titanium wire mesh and impact bone allograft in treating acetabular bone defects in revision total hip arthroplasty

Objective To investigate the method and efficacy in treating acetabular bone defects by the use of titanium wire mesh and impact bone allograft in revision total hip arthroplasty. Methods Twenty-two patients (22 hips) with acetabular bone defects in revision total hip arthroplasty were treated with wire mesh and impact bone allograft from January 2008 to December 2013. There were 7 males and 15 females in the present study. The average age of the patients at the surgery was 64.8 (37-78) years. According to Paprosky classification, there were 9 cases of type IIA, 4 cases of IIB, 7 cases of IIC and 2 cases of IIIB. Twenty cases with aseptic loosen and 2 with periprosthetic infection were underwent revision surgery. Deep frozen cancellous bone allograft was sterilized and morselized to particles with the size of 7 to 10 mm. After removal of loosed acetabular component, the bone grafts were impacted into the acetabular defects area to restore the bone quantity. Titanium wire mesh with appropriate diameter was chosen to fix on impacted bone graft and fixed acetabulum with screws. Polyethylene cup was cemented in the mesh wire with proper position. Harris hip score system was used to evaluate the hip joint function. The AP pelvis X-ray was taken at 1 week, 3 months, 12 months and annually thereafter postoperatively to evaluate the rotation center, fusion of the bone graft and loosening of cup. Results All patients were followed up with the average period 5.1 years (3-7 years). The average Harris hip score before revision was 43.75±13.45, while the score was 85.33±7.84 at last follow-up (t=7.930, P=0.000). The average height of hip rotation center of surgical side was 3.49±0.77 cm before surgery, while its height at last follow-up was 2.22±0.22 cm (t=4.390, P=0.005). The distance between hip rotation center and the base of acetabulum was 3.54±0.45 cm before surgery, while its value was 3.52± 0.76 cm at last follow-up. All the bone grafts came to infusion with the average time 12 months (9-15 months). There was no case with cup migration more than 4 mm or rotation greater than 5° at last follow-up. One patient had the symptom of sciatic nerve injury. No case was with infection or dislocation. Conclusion In the treatment of acetabular bone defects, wire mesh and impact bone allograft with cemented cup in revision total hip arthroplasty can reconstruct hip rotation center and the acetabular bone quantity effectively. Satisfied early-midterm curative effects could be acquired by using this method. Key words: Arthroplasty, replacement, hip; Reoperation; Acetabulum; Bone transplantation; Transplantation, homologous; Surgical mesh

The influence of human umbilical cord mesenchymal stem cells transplantation into vitreous cavity of diabetic rats on retinal morphology and the expression level of glial fibrillary acidic protein and rhodopsin

Objective To observe the influence of human umbilical cord mesenchymal stem cells (hUCMSC) transplantation into vitreous cavity of diabetic rats on the retinal morphology, and the expression of glial fibrillary acidic protein (GFAP) and rhodopsin (RHO). Methods 78 male Sprague-Dawley rats were used. 70 rats were injected with streptozotocin by tail vein injection at a dose of 40 mg/kg to establish the diabetes mellitus model, and another 8 rats were injected with 0.1 mol/L pH 4.0 citric acid buffer at the same dose as the normal control group. After 6 weeks of modeling, 10 rats were taken as the control group of diabetic model. hUCMSC suspension was injected into the right eye vitreous cavity of the remaining 60 rats, and the same volume of Dulbecco′s modified Eagle/F12 medium was injected into the left vitreous cavity as control eyes. 1, 2 and 4 weeks after transplantation, follow-up experiments were performed. The experimental eyes were labeled as U1, U2, and U4 groups, while the control eyes were recorded as D1, D2, D4, and each group consisted of 20 eyes. After paraffin section and hematoxylin-eosin staining, the structure of the retina was observed by optical microscopy and the thickness of the outer nuclear layer and the inner nuclear layer (INL) were measured. The distribution and migration of hUCMSC in rat retina were observed by frozen section-tissue immunofluorescence assay. The mRNA and protein expression of GFAP and RHO in the retina were detected by real-time quantitative polymerase chain reaction (PCR) and Western blot assays. Results The results of optical microscope observation showed the normal structure of retina in normal control group. The retinal nerve fiber layer (NFL) was thinned and the number of retinal ganglion cells (RGC) in the control group of diabetic rats was decreased. The decreased number and disorder arrangement of RGC were observed as well in U1, D1 rats. The RGC number of U2, U4, D2, D4 rats was gradually decreased. Compared with D4 group, the thickness of INL in U4 group was significantly increased (P<0.05). Tissue immunofluorescence assay showed that hUCMSC were distributed along the inner limiting membrane in the retina of the U1 group, while the number of hUCMSC in the U2 group was gradually decreased, mainly in the NFL and ganglion cell layers. Real-time PCR and Western blot data indicated that the relative expression of GFAP mRNA and protein in the diabetic retina was significantly increased, and the relative expression of RHO mRNA and protein decreased gradually in the diabetic model group and the D1, D2, D4 groups. Compared with D2 and D4 groups, the mRNA and protein expression of GFAP in U2 and U4 groups were decreased, and the relative expression of RHO mRNA and protein were all increased (P<0.01). Conclusion hUCMSC could migrate and integrate into the retina, after the transplantation into the vitreous cavity of diabetic rats, which reduced the expression of GFAP, but enhanced the expression of RHO. Key words: Diabetic retinopathy/therapy; Mesenchymal stem cell transplantation; Rhodopsin; Animal experimentation

Evaluation of clinical effects of two elution test methods for neonatal ABO hemolytic disease detection

Objective To compare the clinical application efficacy of frozen elution test and improved thermal elution test (papain-treated erythrocyte micro-column gel-card method) for neonatal ABO hemolytic disease detection, in order to select a laboratory diagnostic method with the best sensitivity and specificity in neonatal ABO hemolytic disease detection. Methods From October to December 2015, a total of 194 whole blood samples for neonatal ABO hemolytic disease detection were collected in this study. Frozen elution test and improved thermal elution test were used to detect all the samples for neonatal ABO hemolytic disease detection, respectively. The positive detection rate, specificity and sensitivity of these 2 methods for neonatal ABO hemolytic disease detection were calculated, and the positive detection rate of the 2 methods for neonatal ABO hemolytic disease detection was compared by Chi-square test. Results The positive detection rate of frozen elution test for neonatal ABO hemolytic disease detection was 57.7% (112/194), which was higher than that of 45.9% (89/194) of improved thermal elution test, and the difference of positive detection rates in these 2 methods was statistically significant (χ2=5.46, P<0.05). The sensitivity of the frozen elution test for neonatal ABO hemolytic disease detection was 92.3% (72/78), which was higher than that of 76.9% (60/78) of improved thermal elution test. The specificity of the 2 methods was both 98.3% (57/58). Conclusions Frozen elution test and improved thermal elution test were both with high specificity for neonatal ABO hemolytic disease detection. However, the sensitivity of frozen elution test is higher and more suitable for the clinical application of this project. Key words: Infant, newborn; Erythroblastosis, fetal; ABO blood-group system; Elution test

Transmembrane delivery and oxygen-dependent degradation mediated by trans-activator-oxygen-dependent degradation fused motif

OBJECTIVE To evaluate transmembrane activity of trans-activator(TAT) protein transduction domain and effect of oxygen-dependent degradation(ODD) domain under different oxygen tension microenvironments in vitro and in vivo.METHODS An enhanced green fluorescent protein(EGFP) fusion protein conjugate with TAT and ODD was constructed,expressed and purified via a series of molecular biological procedures.EGFP and TAT-EGFP were also prepared following similar manipulation.To assay the cell-permeability and hypoxia-targeting stability in vitro,various tumor cell lines including H1299,A549 and MDA-MB-231 were cultured with different EGFP fusion proteins under 20% and 1% oxygen tension conditions,respectively.The treated cells were fixed and then directly observed by fluorescence microscope.To evaluate the oxygen-dependent stability and the profile of distribution of TAT-ODD-EGFP in vivo,male BALB/c mice were iv given EGFP,TAT-EGFP and TAT-ODD-EGFP 10 mg·kg-1.Animals were executed to harvest organs,including the heart,liver,spleen,lung,kidney,intestine,and brain at 1,6 and 12 h after treatment.The frozen sections were prepared for assay by fluorescence microscope.RESULTSTAT-EGFP could be effectively delivered into and stabilized in the different cell lines in vitro and all tissues of mice were observed in vivo.Like TAT-EGFP,TAT-ODD-EGFP could be transformed into cells by TAT,but its stability was oxygen-dependent because of its degradation property from ODD under different oxygen tensions.CONCLUSION TAT can deliver its fusion proteins into cells and animal tissues effectively.TAT fusion protein conjugates with ODD was stabilized in hypoxic cells and tissues,but it was degrades quickly in normoxia because of ODD′s function.TAT-ODD domain can be used in the targeted transduction of anti-tumor proteins into hypoxic tumor tissues.

Cold storage as a method for the long-term preservation of tropical dissolved organic carbon (DOC)

Fluvial fluxes of dissolved organic carbon (DOC) may represent an important loss for terrestrial carbon stores in the tropics. However, there is currently limited guidance on the preservation of tropical water samples for DOC analysis. Commonly employed preservation techniques such as freezing or acidification can limit degradation but may also alter sample properties, complicating DOC analysis. We examined the effects of cold storage at 4 °C on DOC concentration and quality in water samples collected from a tropical peat catchment. Samples were stored in the dark at 4 °C for periods of 6–12 weeks. Freeze/thaw experiments were also made. Mean DOC concentrations in samples stored for six weeks at 4 °C were 6.1 % greater than in samples stored at ambient room temperature (33 °C) over the same period. Changes in DOC concentrations, in two sample sets, during cold storage were 2.25 ± 2.9 mg L-1 (8 %) to 2.69 ± 1.4 mg L-1 (11 %) over a 12-week period. Freeze/thaw resulted in alterations in the optical properties of samples, and this in turn altered the calculated DOC concentrations by an average of 10.9 %. We conclude that cold storage at 4 °C is an acceptable preservation method for tropical DOC water samples, for moderate time periods, and is preferable to freezing or storage at ambient temperatures.

CM247LC 초내열합금에서 일방향응고에 따른 응고조직 변화

CM247LC 초내열합금에서 일방향응고에 따른 응고조직 변화

Novel usage of fresh frozen plasma in hereditary angioedema.

Hereditary angioedema (HAE) is a rare and potentially life threatening autosomal dominant disease characterized by recurrent episodes of cutaneous and mucosal oedema. It results from reduced expression or loss of function of CI-esterase inhibitors (C1-INH). As opposed to the more common histamine-mediated angioedema, HAE does not respond well to conventional treatments with anti-histamines, steroids and adrenaline. Early recognition and timely intervention with the correct treatment are crucial particularly preventing airway obstruction. New disease specific treatment including plasma derived or recombinant C1-INH, ecallantide and icatibant have recently emerged and its appropriate use can reduce HAE-associated mortality and morbidity. However due to its costs, these disease specific treatments have yet to reach Malaysia. Despite that no randomized clinical trial on FFP has been performed, its efficacy in treating acute attacks of HAE is only demonstrated in case studies. This case report illustrates the successful treatment of acute HAE episode with FFP in a Malaysian government hospital setting.

Assessment of Quality Attributes and Steviosides of Stevia rebaudiana Leaves Subjected to Different Drying Methods

Stevia is a plant of great scientific interest due to its high sweetening power and its health benefits giving birth many researches related to changes of this quality by applying a conservation process. Therefore, the objective of this study was to evaluate the influence of different drying techniques (convection, vacuum, microwave, infrared, shade and freeze drying) on proximal analysis, vitamins C and E, fatty acid and amino acid profiles and steviosides from Stevia leaves. Stevioside was the main sweetener found in fresh sample and showed significant increase in all treatments, although convective was the less aggressive treatment (7.45% DM) followed by vacuum (7.02% DM). Stevia leaves may be used as a nutritional complement besides its sweetening power.

Finland's Economic Freeze

Finland's Economic Freeze

Effect of perioperative infection factor on apoptosis in hippocampal neurons after surgery in mice

Objective To evaluate the effect of the perioperative infection factor on apoptosis in hippocampal neurons after surgery in mice. Methods Ninety-six healthy male C57BL/6 mice, aged 8-10 weeks, weighing 20-25 g, were divided into 4 groups (n=24 each) using a random number table: control group (group C), surgery group (group S), infection group (group I) and infection + surgery group (group I+ S). Open reduction and internal fixation was performed after tibial fracture was induced in S and I+ S groups.In I and I+ S groups, lipopolysaccharide 100 μg/kg was injected intraperitoneally at 1 day and 2 h before surgery and 1, 2 and 3 days after surgery once a day for 5 consecutive days.At 1 and 3 days after surgery, 12 mice in each group were selected to perform the contextual fear conditioning test, and the rate of time spent freezing was recorded to evaluate the cognitive function.At 1 day after surgery, venous blood samples were collected for determination of concentrations of adrenocorticotrophin in serum and corticosterone in plasma.After the contextual fear conditioning test, the mice were sacrificed, and the hippocampi were removed to detect the neuronal apoptosis and expression of activated caspase-3, activated poly(ADP-ribose) polymerase-1, Bax and Bcl-2.The apoptosis index and ratio of Bax to Bcl-2 were calculated. Results Compared with group C, the rate of time spent freezing was significantly decreased (P 0.05). Compared with group S, the rate of time spent freezing was significantly decreased, the concentrations of adrenocorticotrophin in plasma and corticosterone in serum were increased, the apoptosis index and Bax/Bcl-2 ratio were increased, and the expression of activated caspase-3 and poly(ADP-ribose) polymerase-1 was up-regulated in group I+ S(P<0.01). Conclusion The mechanism by which perioperative infection factor aggravates postoperative cognitive dysfunction is related to induction of apoptosis in hippocampal neurons through enhancing stress responses in mice. Key words: Bacterial infections; Intraoperative period; Postoperative complications; Cognition disorders; Apoptosis; Hippocampus; Neurons