A high-Ti 6061 alloy was rolled with strains up to 0. 8 - 2. 0 and at 350 - 550 ℃ . Microstructures that developed during deformation and subsequent solution heat treatment (SHT) were observed by using optical and transmission electron microscopy. Microstructure evolution during SHT depends mainly on the initial rolling temperature,and it was found that the higher this temperature is,the coarser the grains are. After rolling at 400 ℃ ,well-defined cells and subgrains were formed, which induced further sites for recrystallization nucleation during subsequent SHT. The recrystallization mechanism was found to be subgrain rotation,with a final grain size smaller than 200 μm. Increasing the rolling temperature to 500 ℃ results in a low density of dislocations distributed uniformly in the deformed matrix and fewer nucleation sites during subsequent SHT. The recrystallization mechanism is grain boundary bulging,while the final grain size approaches several millimeters. Finally,a hot forming process of high-Ti 6061 alloy for inhibiting grain coarsening was proposed,and verified by experiments.
Background: We have previously demonstrated a negative relationship between the prevalence of Helicobacter pylori and gastro‐oesophageal reflux disease (GERD). Aim: To study the effects of H. pylori infection on the severity of GERD. Methods: Ethnic Chinese patients with frequent heartburn and/or endoscopic oesophagitis were studied. Endoscopic examination was performed to assess the severity of oesophagitis (modified Savary–Miller grading) and the presence of hiatus hernia. Biopsies were taken for rapid urease testing and confirmation of Barrett’s oesophagus. Risk factors which may affect the severity of oesophagitis (age, sex, smoking, drinking, diabetes mellitus, hiatus hernia, H. pylori status and body mass index) were evaluated by a multiple regression model. The cagA status of H. pylori infected GERD and age‐and‐sex matched controls were determined by Western blot. Age‐and‐sex matched non‐reflux patients were recruited as controls for comparison. Results: Two hundred and twenty‐five patients with GERD were studied, of whom 77 (34%) were infected with H. pylori . Oesophagitis and Barrett’s oesophagus were found in 140 patients (62%) and six patients (3%), respectively. H. pylori infected patients had significantly less severe oesophagitis compared to the uninfected group ( P =0.022). All patients with Barrett’s oesophagus were uninfected. Factors that predicted severe oesophagitis included age over 60 years ( P < 0.001) and hiatus hernia ( P < 0.001). H. pylori infection was the only factor that showed a negative correlation with severe oesophagitis ( P =0.011). The prevalence of the cagA positive strain in endoscopy‐negative GERD, erosive oesophagitis and control subjects was 70, 76 and 78%, respectively ( P =0.75). Conclusions: H. pylori infection is associated with milder GERD.
Background : We have previously shown that ranitidine bismuth citrate (RBC)‐based triple therapy is comparable to proton pump inhibitor‐based triple therapy in eradicating Helicobacter pylori infection. Aim : To test the efficacy of different combinations of antimicrobials with RBC in the treatment of H. pylori infection. Methods : Dyspeptic patients with H. pylori infection were prospectively randomized to receive one of the following regimens: (i) RBC 400 mg, amoxycillin 1 g, clarithromycin 500 mg [RAC]; (ii) RBC 400 mg, metronidazole 400 mg, clarithromycin 500 mg [RMC]; (iii) RBC 400 mg, metronidazole 400 mg, tetracycline 1 g [RMT] (all given twice daily for 1 week); or (iv) RBC 400 mg plus clarithromycin 500 mg twice daily for 2 weeks [RC‐2]. Endoscopy (rapid urease test and culture) and 13 C‐urea breath test (UBT) were performed before randomization. Four weeks after finishing medication, the 13 C‐UBT was repeated in all cases and endoscopy was offered to patients with peptic ulcers. Results : Four hundred patients were randomized but in two (one in the RAC group and one in the RMC group) H. pylori infection was not confirmed. Successful eradication of H. pylori (intention‐to‐treat analysis and 95% CI) of RAC (86% [79–93%]), RMC (90% [84–96%]), RMT (79% [71–87%]) and RC‐2 (82% [75–90%]) were comparable, with a trend favouring clarithromycin‐containing triple therapy regimens. Among 276 isolates tested for antibiotic sensitivity, primary resistance to metronidazole, clarithromycin and amoxycillin was found in 56%, 2% and 0.4%, respectively. When given RMC or RMT, patients infected by metronidazole‐resistant H. pylori had success in eradicating H. pylori similar to patients infected by metronidazole‐sensitive H. pylori . Conclusion : One‐week RBC triple therapy is effective in curing H. pylori infection.
Vision transformers (ViTs) have achieved remarkable performance in various computer vision tasks. However, intensive memory and computation requirements impede ViTs from running on resource-constrained edge devices. Due to the non-normally distributed values after Softmax and GeLU, post-training quantization on ViTs results in severe accuracy degradation. Moreover, conventional methods fail to address the high channel-wise variance in LayerNorm. To reduce the quantization loss and improve classification accuracy, we propose a two-scaled post-training quantization scheme for vision transformer (TSPTQ-ViT). We design the value-aware two-scaled scaling factors (V-2SF) specialized for post-Softmax and post-GeLU values, which leverage the bit sparsity in non-normal distribution to save bit-widths. In addition, the outlier-aware two-scaled scaling factors (O-2SF) are introduced to LayerNorm, alleviating the dominant impacts from outlier values. Our experimental results show that the proposed methods reach near-lossless accuracy drops (<0.5%) on the ImageNet classification task under 8-bit fully quantized ViTs.
The development of non-equilibrium segregation of boron at grain boundaries in Fe-40%Ni alloy during continuous cooling process was experimentally observed with boronParticle Tracking Autoradiography (PTA) and Transmission Electron Microscopy(TEM). The samples with 10ppm boron were cooled at 2℃/s to 1040, 980, 920,860, 780 and 640℃ respectively after pre-heat treatment of 1150℃ for 15min witha Gleeble-1500 heat simulating machine, then water quenched to room temperature.The width of segregation layer and boron depletion zone, rich factor and other pc-rameters were measured by a special image analysis system. The experimental resultsof PTA show that the grain boundary segregation of boron during cooling process is adynamic process and the development of the non-equilibrium segregation experiencesthree stages: first increases rapidly from 1150 to 1040℃, then gently from 1040 to860℃, and rapidly again from 860℃ to 640℃. The width of boron depletion zoneincreases from about 11μm at 1040℃ to 26μm at 640℃. TEM observation showsthat boron precipitates exist at grain boundaries when the samples are cooled to below860℃. The experimental phenomena are briefly discussed.
Testing results shows that alloying with Ce and Y improves the hardness and softens temperature of cold worked Cu-Cr-Zr alloys obviously, while the conductivity was fluctuant with the variation of RE content. Observation and analysis indicate that micro-dosage RE elements helps to refine microstructure and morphology of Cu-Cr-Zr-RE alloys, suppress microstructure coarsening and improves homogeneous level of Cu-Cr-Zr alloys. Alloying with 0.01% Ce causes about 1% IACS increment of conductivity, and reduces about 2%～3.5% IACS conductivity after alloying with 0.03%～0.04% RE (Ce or Ce+Y) for Cu-Cr-Zr alloys. The microstructure of as-cast Cu-Cr-Zr alloy is refined after alloying with 0.01% Ce while the plasticity is improved slightly. Alloying with 0.01%～0.04% RE improves the softening temperature of deformed Cu-Cr-Zr alloys about 20～40 K; hardness is also improved about 20～35 HV. Test data indicate that alloying with Ce+Y raises softening temperature and hardness of Cu-Cr-Zr alloys more notably than alloying with pure Ce.
The effect of TiO2 addition to the stainless steel slag glass-ceramics was studied.Different mass percentages of TiO2 were added to four samples of the parent glass made from stainless steel slag and cullet.The temperatures of nucleation and crystallization were determined by differential scanning calorimetry（DSC）.According to Xray diffraction（XRD） and scanning electron microscopy（SEM） analysis,adding TiO2 refined grains and restricted the formation of the akermanite phase by capturing Ca2+ to form the perovskite phase.Diopside was the main crystal phase of the glass-ceramics.The bending strength and Vickers hardness increased with the addition of TiO2.The optimal amount of TiO2 was 7 mass%,and the highest bending strength and Vickers hardness were 144.6 MPa and6.26 GPa,respectively.
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