Search

Background Cryptococcal meningitis (CM) remains a leading cause of death in HIV-infected patients, despite advances in CM diagnostic and therapeutic strategies. This study was performed with the aim to develop and validate a novel scoring model to predict mortality risk in HIV-infected patients with CM (HIV/CM). Methods Data on HIV/CM inpatients were obtained from a Multicenter Cohort study in China. Independent risk factors associated with mortality were identified based on data from 2013 to 2017, and a novel scoring model for mortality risk prediction was established. The bootstrapping statistical method was used for internal validation. External validation was performed using data from 2018 to 2020. Results We found that six predictors, including age, stiff neck, impaired consciousness, intracranial pressure, CD4+ T-cell count, and urea levels, were associated with poor prognosis in HIV/CM patients. The novel scoring model could effectively identify HIV/CM patients at high risk of death on admission (area under curve 0.876; p Conclusions Our developed scoring model of six variables is simple, convenient, and accurate for screening high-risk patients with HIV/CM, which may be a useful tool for physicians to assess prognosis in HIV/CM inpatients.

Objective To study the long-term efficacy of cytoreduction surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal carcinomatosis from colorectal cancer. Methods The clinical data were collected of 103 patients with peritoneal carcinomatosis (PC) from colorectal cancer undergoing CRS with HIPEC in the Department of General Surgery of the First Medical Center of Chinese PLA General Hospital from January 1, 2012 to May 31, 2013, and divided into colonic group (n=60) and rectal group (n=43) according to the origin position of peritoneal cancer. The surgical status of patients (whether combined with other organ resection, number of stoma, peritoneal carcinomatosis index (PCI), completeness of cytoreduction (CC) score, transfusion, etc.) and the short-term complications and long-term survival after operation in the both groups were compared. Kaplan-meier method was used to draw the survival curve of patients, and log-rank method was employed to compare the survival differences between the two groups. Results There was no significant difference in the surgical data between the two groups (PCI, CC score, hepatectomy, number of anastomosed stoma, transfusion, etc., P>0.05). The follow-up time of the 103 patients was (28.43±15.65) months, median survival time (OS) was 26.3 months, median disease free survival time (DFS) was 17.7 months, median recurrence to time of death (TTD) was 18.3 months. The 3-year and 5-year survival rate were 35.9% and 8.7%, respectively. The patients' survival was better in colonic group than in rectal group (OS: 28.5 months vs. 19.7 months; DFS: 21.1 months vs. 13.6 months; TTD: 22.3 months vs. 12.1months; 3-year survival rate: 48.3% vs. 18.6%; 5-year survival rate: 15.0% vs. 0, P

Background: The optimal timing for initiation of antiretroviral therapy (ART) in HIV-positive patients with cryptococcal meningitis (CM) has not, as yet, been compellingly elucidated, as research data concerning mortality risk and the occurrence of immune reconstitution inflammatory syndrome (IRIS) in this population remains inconsistent and controversial.Method: The present multicenter randomized clinical trial was conducted in China in patients who presented with confirmed HIV/CM, and who were ART-naïve. Subjects were randomized and stratified into either an early-ART group (ART initiated 2–5 weeks after initiation of antifungal therapy), or a deferred-ART group (ART initiated 5 weeks after initiation of antifungal therapy). Intention-to-treat, and per-protocol analyses of data for these groups were conducted for this study.Result: The probability of survival was found to not be statistically different between patients who started ART between 2–5 weeks of CM therapy initiation (14/47, 29.8%) vs. those initiating ART until 5 weeks after CM therapy initiation (10/55, 18.2%) (p = 0.144). However, initiating ART within 4 weeks after the diagnosis and antifungal treatment of CM resulted in a higher mortality compared with deferring ART initiation until 6 weeks (p = 0.042). The incidence of IRIS did not differ significantly between the early-ART group and the deferred-ART group (6.4 and 7.3%, respectively; p = 0.872). The percentage of patients with severe (grade 3 or 4) adverse events was high in both treatment arms (55.3% in the early-ART group and 41.8% in the deferred-ART group; p=0.183), and there were significantly more grade 4 adverse events in the early-ART group (20 vs. 13; p = 0.042).Conclusion: Although ART initiation from 2 to 5 weeks after initiation of antifungal therapy was not significantly associated with high cumulative mortality or IRIS event rates in HIV/CM patients compared with ART initiation 5 weeks after initiation of antifungal therapy, we found that initiating ART within 4 weeks after CM antifungal treatment resulted in a higher mortality compared with deferring ART initiation until 6 weeks. In addition, we observed that there were significantly more grade 4 adverse events in the early-ART group. Our results support the deferred initiation of ART in HIV-associated CM.Clinical Trials Registration:www.ClinicalTrials.gov, identifier: ChiCTR1900021195.

Pitting corrosion occurred on a tee-pipe joined to main-pipes for seawater tank-washing system of a tanker after sea-trial of only one month. The tee-pipe was made of AISI 316 L stainless steel and the internal wall was required to be passivated. On-site inspection indicated that corrosion-pits were presented in the specified areas on the internal wall of bottom of tee-pipe which can easily retain seawater, and mostly concentrated on the outsides of weld ends. The morphology features of corrosion-pits and the high concentration chlorine in corrosion products located inside the corrosion-pits and on the internal wall of tee-pipe in vicinity of pit-clusters suggested that the damage was due to pitting-corrosion in chloride-containing seawater. Visual and SEM observations revealed that grinding marks occurred on the internal wall of the ends of tee-pipe close to the weld. Grinding operation on the ends of tee-pipe before welding destroyed the integrity of passive film, even locally removed off the passive film. When the affected area was exposed to the seawater containing chloride, the defective areas on passive film could promote the localized corrosion, pitting corrosion. Furthermore, the area with imperfect passive film acted as an anode, whereas the area with perfect passive film acted as a cathode leading to preferential attack at the ground region. The rate of localized attack was very fast in a system with a large cathode and a small anode to lead to pitting failure after a short service time of one month.

Objective To investigate the predictive value of preoperative neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio in surgical site infection (SSI) following radical resection for rectal cancer. Methods Retrospective analysis of clinical data was performed about 298 patients undergoing radical resection of rectal cancer in the Chinese PLA General Hospital from January 2015 to February 2018. According to whether SSI occurred 30 days after surgery, patients were divided into SSI group (n=20) and control group (n=278). Gender, age, preoperative neoadjuvant chemoradiation, surgical procedure, T stage, and preoperative neutrophil count, lymphocyte count, platelet count, neutrophil-lymphocyte ratio (NLR), platelet-lymphocyte ratio (PLR), albumin, and hemoglobin level were compared between the two groups. Subgroup analysis was performed in the SSI group according to laparotomy and minimally invasive surgery. Gender, age, preoperative neoadjuvant chemoradiation (CRT), T stage, and preoperative neutrophil count, lymphocyte count, platelet count, NLR, PLR, albumin, and hemoglobin level were compared between two the subgroups. The predictive value of preoperative NLR and preoperative PLR in surgical site infection following radical resection for rectal cancer were analyzed by receiver operating characteristic (ROC) curve. Results The ratio of male to female in the SSI group is higher than control group (19/1 vs. 178/100, P=0.005). There was no significant difference in other demographic and clinical data such as age, non-restorative operation ratio, minimally invasive surgery ratio, neoadjuvant CRT ratio, T stage, preoperative albumin and preoperative hemoglobin between the two groups (P>0.05). There was no significant difference in preoperative neutrophils count [(3.96±1.03)×109/L vs. (3.62±1.28)×109/L, P=0.245], lymphocytes count [(1.47±0.45)×109/L vs. (1.71±0.64)×109/L, P=0.103] and platelets count [(249.10±57.42)×109/L vs. (230.21±68.53)×109/L, P=0.231] between the two groups. Preoperative NLR in the SSI group was significantly higher than that in the control group (2.77±0.52 vs. 2.39±1.23, P=0.010). Preoperative PLR in the SSI group was higher than that in the control group (184.46±69.54 vs. 152.93±73.82, P=0.065), but the difference was not statistically significant. In the SSI group, the age of the laparotomy subgroup was significantly lower than that of the minimally invasive surgery subgroup (49.20±5.54 vs. 61.87±10.24, P=0.018). There was no significant difference in gender, non-restorative operation ratio, neoadjuvant CRT ratio, T stage, preoperative neutrophil count, lymphocyte count, platelet count, NLR, PLR, albumin, and hemoglobin level between two the subgroups (P>0.05). ROC curve analysis showed that AUC of preoperative NLR in prediction of SSI following radical resection for rectal cancer was 0.711(95%CI 0.643-0.779). When the optimal cut off point was 2.13, its sensitivity and specificity was 95.0% and 51.4%, respectively. AUC of preoperative PLR in prediction of SSI following radical resection for rectal cancer was 0.665(95% CI 0.553-0.777). When the optimal cut off point was 150.69, its sensitivity and specificity was 75.0% and 59.7%. Conclusion Preoperative NLR and PLR have predictive value for SSI following radical resection for rectal cancer. DOI: 10.11855/j.issn.0577-7402.2019.03.10

A truck diesel engine fuel-injection pump fork assembly failed after service of 50703 km. Fuel-injection pump fork assembly was constituted of the fork at the side of air-compressor pump, the intermediate transition block and the fork at the side of high-pressure oil-pump. General inspection in site indicated that the intermediate transition block fractured into four pieces. Fractographic analysis indicated that the block cracked due to fatigue. Four cracks occurred at respective U-shaped groove on the block and originated from the electro-discharge machined (EDMed) fillet root of U-shaped groove, where high stress concentration was caused by the geometry design. A remelted layer of about 5–20 μm was observed on the EDMed U-shaped groove surface. A lot of micro-cracks were presented within the remelted layer, which acted as stress raisers and led to a considerable reduction in fatigue strength of material. The cracks and surface imperfections associated with the remelted layer provided sites for fatigue crack initiation and subsequence propagation into the substrate material, which ultimately caused fatigue fracture of block. A finite element model of the block predicted that the highest stress concentration areas coincided with the first fracture zones and the maximum stress gradient direction was in agreement with the crack initiating direction.

Backgrounds: A respiratory epidemic defined as coronavirus disease 2019 (COVID-19) is becoming unstoppable and has been declared a pandemic. Patients with cancer are more likely to develop COVID-19. Based on our experience during the pandemic period, we propose some surgery strategies for gastric cancer patients under the COVID-19 situation. Methods We defined the ‘COVID-19’ period as occurring between 2020-01-20 and 2020-03-20. All the enrolled patients were divided into two groups, pre-COVID-19 group (PCG) and COVID-19 group (CG). A total of 109 patients with gastric cancer were enrolled in this study. Results The waiting times before admission increased by 4 days in CG(PCG:4.5 [IQR: 2, 7.8] vs. CG:8.0 [IQR: 2,20]; P = 0.006). More patients had performed chest CT scan besides abdominal CT before admission during COVID-19 period(PCG:22[32%]vs. CG:30[73%], p = 0.001). After admission, during COVID period, the waiting time before surgery was longer(3[IQR: 2,5] vs. 7[IQR: 5,9]; P

Background The coronavirus disease 2019 (COVID-19) has been declared a global pandemic by the World Health Organization. Patients with cancer are more likely to incur poor clinical outcomes. Due to the prevailing pandemic, we propose some surgical strategies for gastric cancer patients. Methods The ‘COVID-19’ period was defined as occurring between 2020 and 01-20 and 2020-03-20. The enrolled patients were divided into two groups, pre-COVID-19 group (PCG) and COVID-19 group (CG). A total of 109 patients with gastric cancer were enrolled in this study. Results The waiting time before admission increased by 4 days in the CG (PCG: 4.5 [IQR: 2, 7.8] vs. CG: 8.0 [IQR: 2,20]; p = 0.006). More patients had performed chest CT scans besides abdominal CT before admission during the COVID-19 period (PCG: 22 [32%] vs. CG: 30 [73%], p = 0.001). After admission during the COVID period, the waiting time before surgery was longer (PCG: 3[IQR: 2,5] vs. CG: 7[IQR: 5,9]; p p = 0.021), and hospital stay period after surgery was longer (7[IQR: 6,8] vs.9[IQR:7,11]; p p = 0.006). Conclusion This study provides an opportunity for our surgical colleagues to reflect on their own services and any contingency plans they may have to tackle the COVID-19 crisis.

Background ： A respiratory epidemic defined as coronavirus disease 2019 ( COVID-19 ) is becoming unstoppable and has been declared a pandemic. Patients with cancer are more likely to develop COVID-19. Based on our experience during the pandemic period, we propose some surgery strategies for gastric cancer patients under the COVID-19 situation. Methods ： We defined the ‘COVID-19’ period as occurring between 2020-01-20 and 2020-03-20. All the enrolled patients were divided into two groups, pre-COVID-19 group (PCG) and COVID-19 group (CG). A total of 109 patients with gastric cancer were enrolled in this study. Results ： The waiting times before admission increased by 4 days in CG(PCG:4.5 [IQR: 2, 7.8] vs. CG:8.0 [IQR: 2,20]; P = 0.006). More patients had performed chest CT scan besides abdominal CT before admission during COVID-19 period(PCG:22[32%]vs. CG:30[73%], p=0.001). After admission, during COVID period, the waiting time before surgery was longer(3[IQR: 2,5] vs. 7[IQR: 5,9]; P < 0.001),more laparoscopic surgery were performed(PCG: 51[75%] vs. CG: 38[92%],p=0.021), and hospital stay after surgery was longer (7[IQR: 6,8] vs.9[IQR:7,11] ; P < 0.001). The total cost of hospitalization increased during COVID period, (9.22[IQR:7.82,10.97] vs. 10.42[IQR:8.99,12.57]; p=0.006). Conclusion ： Since no data is available yet on the impact of COVID-19 on gastric cancer patients,our own experience with COVID-19 in gastric cancer surgery has hopefully provided an opportunity for colleagues to reflect on their own service and any contingency plans they have to tackle the crisis. Keywords: gastric cancer; coronavirus disease 2019; COVID-19; retrospective analysis; real-world data.

Background: Currently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread globally, causing an unprecedented pandemic However, there is st

A truck engine crankshaft fractured during the service. The fracture occurred on the crankshaft big-end on which the timing-gear and the flywheel flange were coupled and the fracture location was just situated at the assembling gap between them. The short cracks inclined at about 45° to the shaft axis initiated from the surface of the crankshaft journal at the timing-gear side and mainly extended to the timing-gear side, leading to a zigzag cracking morphology on the journal surface. A complicated ratchet or star-shaped pattern of fracture typical of multiple fatigue cracks occurred on the fracture surface. The journal surface was locally induction-hardened. The surface hardness and the effective case depth on the hardened journal at the flywheel flange side corresponded to the specification. At the timing-gear side the surface hardness on the hardened journal was much lower than the specified lower limit and a low hardness region of 0.4 mm occurred on the most-surface of the hardened journal within which the hardness values were lower than the specified lower limit. The low surface hardness on the induction-hardened journal made fatigue resistance of the crankshaft decrease to lead to initiation and propagation of fatigue cracks in the weaker region. The assembling gap at which the fracture occurred was structure stress concentration site of the assembly constituted of the crankshaft, the timing-gear and the flywheel flange, equivalent to the deep notch. The excessive tightening of the timing-gear on the journal surface also contributed for the increasing of stress concentration. The fatigue crack origins were easy to initiate due to large stress concentration.

A cylindrical spiral gear, part of a locomotive axle assembly, cracked ten days after it had been press-fit onto a shaft, after which it sat in place as other repairs were made. Workers at the locomotive shop reported hearing a sound, and upon inspecting the gear, found a crack extending radially from the bore to the surface of one of the tooth flanks. The crack runs the entire width of the bore, passing through an oil hole in the hub, across the spoke plate and out to the tip of one of the teeth. Design requirements call for the gear teeth to be carburized, while the remaining surfaces, protected by an anti-carburizing coating, stay unchanged. Based on extensive testing, including metallographic examination, microstructural analysis, microhardness testing, and spectroscopy, the oil hole was not protected as required, evidenced by the presence of a case layer. This oversight combined with the observation of intergranular fracture surfaces and the presence of secondary microcracks in the case layer point to hydrogen embrittlement as the primary cause of failure. It is likely that hydrogen absorption occurred during the gas carburizing process.

A bulk-ship was not working normally when anchoring to wait for entering port. Inspection in site found that the intermediate shaft fractured. The intermediate shaft had accumulatively serviced for 43,000 h before fractured. Fractographic investigation indicated that the multiple origins fatigue fracture was the dominant failure mechanism of the shaft. The cracking propagated on two fracture planes at approximately ± 45° with respect to the shaft axis. The material of failed shaft was found to be a low carbon steel of type ASTM 1020, rather than the specified the medium carbon steel of type ASTM 1035. The average values of yield strength and ultimate strength of shaft material were respectively 16% and 20% lower than the lower limit of technical specification due to low carbon content, as a result of the decreased fatigue strength of shaft material. The fracture occurred at the fillet root of flange connected to the propeller-shaft, where high stress concentration was caused by geometry design. Deep circumferential machining grooves were present on the fillet root of flange for additive stress concentration. The inhomogeneities acted as potential sites for fatigue crack initiation. The low fatigue strength of shaft material promoted initiation and propagation of fatigue cracks in the weaker region under the reversed torsion loading. The static strength analysis of intermediate shaft was performed to assess the design implications. The measured average ultimate strength of failed intermediate shaft was 12% lower than the lower limit in Rule for Classification of Sea-going Steel Ships issued by China Classification Society. The safety factor of the failed intermediate shaft is lower than the permitted one.

A worn backup-roller in rolling mill was repaired by hardfacing technology. The routine flaw detection after machining revealed that randomly distributed circumferential short cracks occurred on the surface of repaired roller. Sectional observation throughout hardfacing region showed that intensively distributed transverse short cracks were also present inside the outer layer of hardfacing region. Detailed metallographic analysis and fractographic investigation indicate that the transverse short cracks are crystallization cracks, caused by hot-cracking. General excessive element of P in the outer layer and the segregation of impurity elements P, S within the interdendritic space and at the grain boundary are metallurgical factors responsible for hot-cracking. Occurrence of the bending load on the roller, resulting from the great self-weight of roller, is mechanical factor leading to forming transverse crystallization cracks.

The longitudinal cracking took place on the head of an injector nozzle-valve used truck diesel engine during the engine trial test. The fatigue fracture is the dominant failure mechanism of the nozzle-valve. A lot of ovoid and elongated dents were found on the cone of internal cavity of nozzle-valve and the dents were associated to debonding of the ovoid compound inclusions composed of calcium aluminate and MnS, and MnS stringers on the surface from the matrix. Debonding of inclusions was most likely to occur in the process of the carburization-heating of the nozzle-valve. Due to non-coherence between the inclusions and the matrix, debonding of inclusions maybe took place during the process of operating under the action of alternative operational load on the nozzle-valve cone. The size of these dents was enlarged further owing to the cavitation damage during the operating. The crack origin was just initiated from a large ovoid dent appearing at the seal interface between the nozzle-valve cone and the needle-valve, which acted as stress raiser. The edge of the large ovoid dent at the specific location was subjected to two kinds of stresses in the operating, the circumferential tensile stress resulting from the internal pressure of fuel-oil and the circumferential tensile stress resulting from the contact load between the nozzle-valve cone and the needle-valve. Under the action of the alternative superimposing stress, the fatigue crack initiated from the edge of the large dent and propagated outward along the radial to lead to longitudinal cracking throughout the entire wall thickness of nozzle-valve. The upper cone of nozzle-valve had been almost carburized throughout, which would strongly embrittle the cone with thin wall thickness to promote crack propagation.

Several electronic unit pumps (EUPs) used in the truck diesel engine failed during the trial tests. All the failures occurred at the same location, the fifth thread root on the outer diameter of oil-outlet of EUP. Two typical failed EUPs were analyzed to assess failure causes. Fractographic investigation shows that the fatigue fracture was the dominant failure mechanism of two EUPs. Crack origins of the failed EUPs initiated from the fillet root of the step in the internal hole of oil-outlet and propagated toward the fifth thread root on the outer diameter of oil-outlet. Over-small radius of the root fillet caused a high notch effect, and the presence of porous structure and network nitrides on the nitrided internal hole surface created a “metallurgical stress concentration.” Under the action of the great contact force between the plug and the side wall of internal hole of oil-outlet resulting from the press-fitting the plug, the crack initiated easily at the fillet root. The fillet root of step in the internal hole was almost in the same level with the fifth thread root on the outer diameter of oil-outlet. The fifth thread on the outer diameter of oil-outlet was just corresponding to the first engaged thread inside the nut of oil-pipe matched with the threaded portion of the outer diameter of oil-outlet. This resulted in a maximum axial tensile load on the fifth thread due to pre-tightening the nut of oil-pipe. The crack propagated rapidly toward the fifth thread on the outer diameter under the great axial tensile load to lead to premature fatigue failure of EUP.

The bolts assembled on a tuning-wheel of a marine diesel engine were found fractured and loose in service of only 70 days. The damage and fractography features of the bolts were investigated to identify the failure sequence and the failure causes or modes. The crack origins were from the diameter surface of the bolts, and reverse bending and rotating bending fatigue fractures were the dominant failure modes. Various manufacturing defects, such as tight radii of transition fillet between the shanks and the threaded sections of bolts, poor surface roughness, and machined threads rather than cold-rolled threads, were found on the fractured bolts, which created a high stress concentration. A few bolts were loose in the first place during service, the overall stress state of the bolts changed to lead to a non-uniform distribution of load on the bolts. Some bolts had to sustain a great load, which was sufficient to cause fatigue crack initiation at the defective regions of bolts in such a short time period. Unsuitable installation procedures allowed for the possibility of low preload on the bolts leading to bolt loosening when subjected to vibrational loads during service. Additionally, bolt loosening could occur due to severe loading conditions. The bolts on the wheel failed in succession due to poor bolt manufacture and installation.

Background Asymptomatic cryptococcal antigenemia is a state of cryptococcal infection commonly seen in immunocompromised HIV-infected persons. Without early intervention, a proportion of HIV-infected persons with cryptococcal antigenemia may go on to develop cryptococcosis, especially cryptococcal meningitis, which is associated with high mortality. The benefits of antifungal intervention and optimal therapeutic intervention regimens for HIV-infected persons with cryptococcal antigenemia remain controversial. We therefore designed the present study in order to investigate the necessity of, and the optimal regimens for antifungal intervention in the clinical management of cryptococcal antigenemia in HIV-infected populations. Methods/design This study will be an open-labeled, multi-center, prospective, randomized controlled trial, and 450 eligible participants will be randomized into a control arm and 2 intervention arms at a 1:1:1 ratio, with 150 subjects in each arm. Participants in the control arm will not receive antifungal treatment during the study period. Participants in intervention arm 1 will receive oral fluconazole 800 mg/day for 2 weeks, followed by 400 mg/day for 8 weeks and 200 mg/day for 42 weeks, and participants in intervention arm 2 will receive oral fluconazole 400 mg/day for 52 weeks. The primary outcome is the incidence of CM among the 3 groups during the study period. The secondary outcomes include the differences in all-cause mortality, proportion of patients reverting to blood CrAg negativity, change of CrAg titers, and adverse events among the 3 groups during the follow-up period. Discussion We envisage that the results of this study will reveal the necessity of, and the optimal therapeutic regimens for, antifungal intervention in clinical management of HIV-infected patients with cryptococcal antigenemia. Trial registration The study was registered as one of the 12 clinical trials under a general project at the Chinese Clinical Trial Registry on February 1, 2019, and the registration number of the general project is ChiCTR1900021195.

Hoop brittle fracture took place on several tapered roller bearing inner rings during assembling with the intermediate shaft. All the cracking took place on the laser marking area on the small head end of inner ring representative of product identification. Detailed metallurgical analysis revealed that two kinds of metallurgical defects mainly occurred on the small head end of cracked inner rings: (1) several of deep and narrow near-surface micro-grooves resulting from laser marking were distributed dispersively on the small head end of inner ring, (2) the thermal softening resulting from grinding burn occurred on the small head end of inner ring, causing decrease in surface hardness as well as development of tensile stress. The crack origins were all located on the overlapping zone of the laser marking area and grinding burn area. Cracks initiated from the micro-grooves and propagated toward the inner along the axial under the action of assembly stress. The presence of the near-surface micro-grooves as sharp notches on the laser-marked small head end was mainly responsible for the fracture failure of inner rings. The occurrence of the thermal softening layer due to grinding burn on the small end of inner ring, consequently leading to decreasing in the surface hardness and resultant low tensile strength, promoted the crack initiation and propagation.

Two locomotive diesel engine injector nozzles fractured during service. The fractured injector nozzles are fabricated with 18CrNi8 steel, and the external and the internal surfaces of injector nozzles are required to be carburized. Visual inspections indicate that the fracture occurred just at the transition fillet root between the large excircle and the secondary excircle of injector nozzle. Fractographic investigation indicates that the crack origin is situated at the oil-filled groove with a thin wall thickness and the brittle intergranular fracture is the main failure mode of the two injector nozzles. Metallurgical examinations show that case depths through the entire wall thickness are present at the fracture regions. The brittle microstructure typical of carburized layer was produced in the fracture regions, which was confirmed by the occurrence of intergranular micro-cracks. The presence of case depth through the entire wall thickness in the fracture region made the toughness at the region decrease intensely. The crack initiated at the weakened location and propagated from the internal surface toward the external surface under the impact of the oiling pressure with high-frequency pulsation to lead to transverse brittle fracture of the two injector nozzles. Additionally, the presence of many brittle Al2O3 complex inclusions in the vicinity of the fracture region induced tensile stress in the matrix around inclusions and the stress concentration around the inclusions to promote initiation of the crack.

In drawing area, aiming at the problems of drawing breadth and angle cannot be adjusted individually and not convenient to carry, a kind of multi-functional folding drawing board is designed by us. The appearance of the multi-functional folding drawing board is kind of drawing board, some light materials like basswood and rigid plastics are used in main structure of the drawing board to make it light and convenient to carry. The main structure can be folded and it is suitable for A1 and A2 drawings. In the designing procedure, dip angle adjusted mechanism by worm wheel and gear, magnetic pull-in mechanism, leading rail, slide-way, drawer, tool library, paper bag and horn locks are applied based on modularity designing theory. Finite element analysis of key components of drawing board is analyzed.

A locomotive turbocharger assembly suffered from destruction during a trial operating for 120 h. The damaged components include worm-housing, impeller blades and impeller-cover, main-shaft, bearing-sleeve, and main-shaft bolts. Fracture, deformation, and wear to varying degrees occurred on the components. The damage and fractography features on the failed components were investigated to identify the troublemaker in this incident and the root cause of turbocharger destruction. The investigation indicates that thread stripping on the wall of bolt holes on the flange at the inlet end of worm-housing induced the destruction of the whole turbocharger assembly. The specified material of worm-housing is gray cast iron (HT 250) and the specified low limit of tensile strength is 250 MPa. Unexpectedly, the tensile strength of the failed worm-housing material is about 70% of the specified low limit. The low strength of worm-housing material is mainly responsible for thread stripping of the bolt holes on the flange. The carbon content of worm-housing material exceeds the specified upper limit. Excessive graphite and long and thick graphite flakes in the worm-housing material resulting from high carbon content or maybe from unsuitable foundry practices led to low hardness and low strength of worm-housing material.

Failure of any component in a vehicle, even a small part, may result in an out of control vehicle and possible catastrophic accident. In this paper, two case studies regarding the failure of truck diesel engine connecting-rods are presented. Fatigue is the dominant failure mode of the two connecting-rods. The occurrence of an abnormal load in operation and the presence of a thick decarburization layer on the external surface of the rod-body are, respectively, responsible for the fatigue failure of the two connecting-rods.

This paper studied the lightweight ceramsite, thickener and waterproofing agent dosage on the influence of the foam concrete water absorption and strength, and further researched into the amount of foaming agent on the influence of the density and strength. The results show that adding 20% ceramic, 0.03% thickening agent and 1% waterproof agent prepared the best performance of foam concrete.

Cracks were found in the weld metal (WM) of weld-section of side shell of drilling-well oil storage ship when performing post weld radiographic examination. The cracks were subjected to detailed metallographic analysis and the fracture surfaces were observed visually and using SEM. The results indicate that the cracks were embedded in middle of multiple beads of WM. The fracture surface reveals the dendritic solidification structure of WM, which contains impurity element sulfur and other alloy elements (Ti, Al, and O) originating from the filler core of welding wire. The embedded cracks are a type of weld hot crack, the solidification crack. The failure mechanism is identified to be welding hot cracking.

The Hong Run petrochemical oil depot is located in a saline area in the north of Weifang, where the contents of chloride and sulfate in this area are very high. Due to the rigorous environmental conditions, concrete with 50 years durability and C40 strength grade was prepared. A kind of corrosion resistance concrete with high performance superfine mineral powder and high performance pumping agent was developed to adapt to the conditions in saline areas. The chloride-penetration resistance ability was investigated by the test of chloride ion rapid electric transport (ASTM C1202). The concrete compressive strength and mortar expansion rate under continuous immersion in four different corrosion solutions was studied. The results showed that the chloride-penetration grade is very low. The compressive strength is high and the mortar expansion rate lower than 0.1%.

Longitudinal cracking and transverse fracture took place on a diesel engine piston-pin used in a truck during service. The banded texture throughout the whole length of the longitudinal fracture is presented in the middle region of the longitudinal fracture. The longitudinal crack originated from the banded texture and propagated toward the internal hole surface and the external circle surface of the piston-pin. Metallographic and chemical inspections of the piston-pin material away from the crack origin reveal all the parameters to be acceptable. Subsequent metallographic examinations were performed on the smoothed longitudinal fracture surface. These reveal the presence of the longitudinal inclusion clusters of 25 mm long mainly consisting of calcium aluminate, associated with the banded texture on the longitudinal fracture. Under the integrated action of structure stress and service stress, the crack propagated along the longitudinal first, and then propagating along the transverse by fatigue under the alternative service load. The appearance of longitudinal inclusion clusters of excess size in the crack origin zone is mainly responsible for the failure of piston-pin.

Multimedia technology in the field of education and teaching has made great achievements. It is also used widely in the area of sport. However, multimedia technology in the teaching of basketball tactics is still in the initial stage. The paper is to study the application of multimedia technology in teaching basketball tactics, and to make "basic tactics of basketball teaching" Multimedia CAI Courseware. The Study shows that it is possible to use multimedia technology in basketball tactics, and it is bound to help improve basic tactics of basketball teaching.

ion: The rebound is a basketball skills: A skill of two sides’ players striving for the rebound when the shot missed. In a basketball game, grabbing the more rebounds always means winning the game. Taking the rebounds will have more opportunities to beat the rivals. The rebounds are combined with defensive rebound and offensive rebound. And the offensive rebound will encourage the players on the court and bring more enthusiasms to the fans. This paper analyzes how to strive for offensive rebounds in the basketball game, and provide a consultation for the coaches to grab the win. Key words: Strive for ,Offensive Rebounds, Basketball Game, Theoretical Study

With the development of economy and the progress of the society, computer multimedia technology emerges, as the times require. Computer multimedia enrich people's lives. For us, it not only provides a better visual experience and auditory enjoyment , but also plays an supporting role powerfully in solving the complicated work . The purpose of this paper is to study the application of multimedia technology in sports test and to explore the significance of promoting sports fair by multimedia technology.

A locomotive diesel engine cardan-shaft fractured when trial test for 360 h. Fractographic investigation reveals that the failure mechanism of cardan-shaft is multiple origins fatigue fracture. The crack origins are situated on the external circle surface of the transition fillet root of the splined portion, which acts as a stress concentrator. The macro-structure segregation and corresponding inhomogeneous microstructure are presented in cardan-shaft material. And the presence of more ferrite and abnormal Widmannstatten structure ferrite in core microstructure led to the low core hardness (below the minimum value required). Therefore, the estimated fatigue endurance limit of the cardan-shaft material is lower than the expected value by approximately 20%. Along with the stress concentrator in transition fillet, the fatigue crack initiated and propagated under the torsion load and the axial tensile load, ultimately leading to premature fatigue fracture of cardan-shaft. The defective forging and the heat treatment processes should be responsible for the occurrence of defective microstructure and the consequence of low core hardness.

Circumferential cracking occurred on the spoke plate of a statically placed marine gear. Fractographic investigation indicates that two independent crack origins are present on the fracture surface. Intergranular fracture mode was mostly found in slow crack propagation region and the intergranular facets associated with ductile shearing. Metallographic observation reveals that a type of macro casting defect, spot-segregation, is generally present on the gear material. Large size macro spot-segregation defect zones just appear in two crack origin regions. Appearance of the large spot-segregation zones in the core of spoke plate supplies the favorable metallurgical condition for hydrogen-induced fracture: presence of excessive impurities of S, P and then appearance of abnormal microstructure of upper-bainite susceptible to hydrogen embrittlement. From the evidences it is concluded that the gear failed due to the hydrogen embrittlement. The possible source for hydrogen was introduced during melting and casting operating.

A galvanized washer used for a locomotive impeller broke into three pieces after an accumulative service of 4–5 h. The washer is fabricated from 42CrMo steel and the fracture surfaces reveal intergranular fracture morphology with microvoid coalescence observed on the facets. Microstructure observation indicates the presence of a severely banded microstructure mainly consisting of untempered martensite and bainite. The average hardness of the failed washer is HRC 59.1. The hardness value is much higher than specified (HBW 260-300) and is in the range of hydrogen embrittlement susceptibility. The significant number of elongated MnS inclusions acting as traps of hydrogen are present in the martensite regions. The delayed fracture associated with the predominance of intergranular fracture micromechanism and the high hardness level and the presence of microstructure susceptible for the hydrogen embrittlement strongly suggest the hydrogen embrittlement being the mostly possible failure mechanism. The likely sources for hydrogen entrapment are the electro-galvanizing process and acid-pickling before galvanizing. The hydrogen was retained in the washer due to absence of baking treatment to remove it or insufficient baking. The incorrect heat treatment process before galvanizing resulting in the high hardness level of the washer is mainly responsible for the occurrence of hydrogen embrittlement on the washer.

To develop molecular catalysts for the generation of dioxygen, the photophysical properties of cobalt complexes of boradiazaindacene (BODIPY) derivatives were studied. It is found that the intramolecular energy transfer due to d–π interaction between boradiazaindacene (BODIPY) and the cobalt central in aqua-cobalt complexes, which was confirmed by DFT calculation, leads to the quenched fluorescence emission being recovered completely. The effect of link spacers (benzyl groups) on the intramolecular d–π interaction was discussed. Results show that cobalt complexes of BODIPY derivatives can be photo-sensitizers and a good blue LED light driven precatalyst for the oxidation of water. The dioxygen generation was further confirmed by the photooxidization of 1,5-dihydroxylnaphthalene (DHN) catalyzed by cobalt complexes using water as the oxygen source. This will give a new path to design photo-active complexes to be used as PDT in hypoxic environments.

The wear damage occurred on the two mating pistons, interior piston and exterior piston used for a marine exhaust valve. Visual and SEM observations indicate that the heavy wear marks and wear strips with flaky spalling occurred on the contact surfaces of both pistons. The primary failure mode is the adhesive wear accompanied by little fatigue wear. Metallurgical observations reveal that a white etching layer (WEL) is presented beneath the seriously worn surfaces. XRD analysis indicates that the amount of austenite on the unworn or the lightly worn surfaces of both pistons is in a high level. During operation, the metastable austenite would transform to the martensite under the friction stress, which results in a volume expansion. The clearance between mating pistons would become small to make the friction force on the contact surfaces increase. And the increased friction force induced the concentrated frictional heating. Inadequate lubrication oil cannot bring frictional energy away in time so that the located surface temperature would exceed critical temperature (Ac 3 ). This temperature rise is high enough for austenitization and under such high temperature, the instantaneous hardness of located contact surfaces is low to lead to the occurrence of adhesion wear. Subsequent γ → α ′ transformation would occur as the bulk of the piston rapidly conducts heat away from the piston surfaces to form a WEL on the seriously worn surface. The micro-crack formation inside the WEL and subsequent propagating would lead to the occurrence of spalling.

A cylindrical spiral gear of locomotive axle gearbox failed after standing in site for 10 days. The failed gear had been assembled with the spiral gear-shaft. Inspection in site found that cracking occurred on the spoke plate between the shaft bore and the oil-pressed hole. The gear teeth are required to be carburized, but the surfaces of the shaft bore and the oil-pressed hole of gear are surface-coated to prevent carburizing. The crack initiated from the surface of oil-pressed hole and propagated along the radial of the oil-pressed hole. Metallurgical examination reveals that anti-carburizing measure was not conducted on the surface of oil-pressed hole as the specification. A simplified evaluation of the maximum hoop tensile on the wall of oil-pressed hole subjected to internal pressure for swelling bore is far insufficient to lead to brittle fracture. Delayed fracture of gear, the predominance of intergranular fracture micro-mechanism, and the presence of several secondary micro-cracks in the depth of case layer on the oil-pressed hole surface are a clear indication of hydrogen embrittlement. Hydrogen absorption occurred during gas carburizing process.

Spraying oil occurred abruptly during a duration test of diesel engine injector for around 26 h and a crack was found on the outer periphery of injector. SEM observation indicates that multiple origins and high cyclic fatigue fracture is the dominant failure mechanism of the injector. Fracture initiated on the electro-discharge machining (EDM) wall of the transverse oil hole of the injector and propagated under cyclic load (alternative oil pressure). Metallurgical examination indicates that a lot of radial micro-cracks are presented within the remelted layer on the EMD wall of the transverse oil hole. In this paper the reasons for this failure were discussed by fracture analysis and metallographic examination results and the stress analysis of the oil holes under the operation oil pressure of 160 MPa. The discharge energy in EMD process should be controlled to reduce the crack density and depth within the remelted layer induced by EDM process and to avoid multiple fatigue-crack initiation. Chamfer probably the orifice of the transverse oil hole intersecting with the wall of the center oil hole to decrease stress concentration degree at the orifice of transverse hole.

This paper present a failure analysis of box-like link-plate. The failed link-plate is fabricated from 42CrMo steel and the surface of internal hole is demanded to be induction-hardened. Metallographic analyses, tensile test and fractography investigation were conducted in order to determine the causes of failure. The strength and toughness levels of link-plate material are below what is expected. A number of fisheyes were found on the tensile fracture surfaces and a lot of non-metallic inclusions are presented in the centre of fisheyes. Two axial cracks were found on the surface of internal hole of link-plate when performing flaw detection after finishing induction-hardening operating on the surface of internal hole. Radial extending depth of two cracks just corresponds to the depth of induction-hardened layer. Intergranular fracture is predominant micromechanism of the crack in link-plate. Evidences indicate that the failure of link-plate is due to hydrogen. The possible source for hydrogen was introduced during melting and casting process. A great number of non-metallic inclusions in the link-plate material acted as traps of hydrogen.