Boundary behaviour of the unique solution to a singular Dirichlet problem with a convection term

AbstractBy Karamata regular variation theory and constructing comparison functions, we derive that the boundary behaviour of the unique solution to a singular Dirichlet problem −Δu=b(x)g(u)+λ|∇u|q, u>0, x∈Ω, u|∂Ω=0, which is independent of λ|∇uλ|q, where Ω is a bounded domain with smooth boundary in RN, λ∈R, q∈(0,2], lims→0+g(s)=+∞, and b is non-negative on Ω, which may be vanishing on the boundary

Reduced Brain Activity in the Right Putamen as an Early Predictor for Treatment Response in Drug-Naive, First-Episode Schizophrenia

Antipsychotic medications can have a significant effect on brain function after only several days of treatment. It is unclear whether such an acute effect can serve as an early predictor for treatment response in schizophrenia. Thirty-two patients with drug-naive, first-episode schizophrenia and 32 healthy controls underwent resting-state functional magnetic resonance imaging. Patients were treated with olanzapine and were scanned at baseline and 1 week of treatment. Healthy controls were scanned once at baseline. Symptom severity was assessed within the patient group using the Positive and Negative Syndrome Scale (PANSS) at three time points (baseline, 1 week of treatment, and 8 weeks of treatment). The fractional amplitude of low frequency fluctuation (fALFF) and support vector regression (SVR) methods were used to analyze the data. Compared with the control group, the patient group showed increased levels of fALFF in the bilateral putamen at baseline. After 1 week of olanzapine treatment, the patient group showed decreased levels of fALFF in the right putamen relative to those at baseline. The SVR analysis found a significantly positive relationship between the reduction in fALFF after 1 week of treatment and the improvement in positive symptoms after 8 weeks of treatment (r = 0.431, p = 0.014). The present study provides evidence that early reduction and normalization of fALFF in the right putamen may serve as a predictor for treatment response in patients with schizophrenia

Enhanced baseline activity in the left ventromedial putamen predicts individual treatment response in drug-naive, first-episode schizophrenia: Results from two independent study samples

BACKGROUND: Antipsychotic medications are the common treatment for schizophrenia. However, reliable biomarkers that can predict individual treatment response are still lacking. The present study aimed to examine whether baseline putamen activity can predict individual treatment response in schizophrenia. METHODS: Two independent samples of patients with drug-naive, first-episode schizophrenia (32 patients in sample 1 and 44 in sample 2) and matched healthy controls underwent resting-state functional magnetic resonance imaging (fMRI) at baseline. Patients were treated with olanzapine for 8 weeks; symptom severity was assessed using the Positive and Negative Syndrome Scale (PANSS) at baseline and week 8. Fractional amplitude of low frequency fluctuation (fALFF) and pattern classification techniques were used to analyze the data. FINDINGS: Univariate analysis shows an elevated pre-treatment fALFF in the left ventromedial putamen in both patient samples compared to healthy controls (p\u27s \u3c 0.001). The support vector regression (SVR) analysis suggests a positive relationship between baseline pre-treatment fALFF in the left ventromedial putamen and improvement in positive symptom at week 8 in each patient group using a cross-validated method (r=0.452, p=.002; r=0.511, p=.003, respectively). INTERPRETATION: Our study suggests that elevated pre-treatment mean fALFF in the left ventromedial putamen may predict individual therapeutic response to olanzapine treatment in drug-naive, first-episode patients with schizophrenia. Future studies are needed to confirm whether this finding is generalizable to patients with schizophrenia treated with other antipsychotic medications. FUND: The National Key RandD Program of China and the National Natural Science Foundation of China

Disrupted asymmetry of inter- and intra-hemispheric functional connectivity in patients with drug-naive, first-episode schizophrenia and their unaffected siblings

BACKGROUND: Lack of normal asymmetry in the brain has been reported in patients with schizophrenia. However, it remains unclear whether disrupted asymmetry originates from inter-hemispheric functional connectivity (FC) and/or intra-hemispheric FC in this patient population. METHODS: Forty-four patients with drug-naive, first-episode schizophrenia, 42 unaffected siblings, and 44 healthy controls underwent resting-state functional magnetic resonance imaging (fMRI) scan. The parameter of asymmetry (PAS) and support vector machine (SVM) were used to analyze the data. Patients were treated with olanzapine for 8 weeks. FINDINGS: Compared with healthy controls, patients showed lower PAS scores in the left middle temporal gyrus (MTG)/inferior temporal gyrus (ITG), left posterior cingulate cortex (PCC)/precuneus and left angular gyrus, and higher PAS scores in the left precentral gyrus/postcentral gyrus. Unaffected siblings also showed lower PAS scores in the left MTG/ITG and left PCC/precuneus relative to healthy controls. Further, SVM analysis showed that a combination of the PAS scores in these two clusters in patients at baseline was able to predict clinical response after 8weeks of olanzapine treatment with 77.27% sensitivity, 72.73% specificity, and 75.00% accuracy. INTERPRETATION: The present study suggests disrupted asymmetry of inter- and intra-hemispheric FC in drug-naive, first-episode schizophrenia; in addition, a reduced asymmetry of inter-hemispheric FC in the left MTG/ITG and left PCC/precuneus may serve as an endophenotype for schizophrenia, and may have clinical utility to predict response to olanzapine treatment. FUND: The National Key RandD Program of China and the National Natural Science Foundation of China

Influence of nitrogen on corrosion behaviour of high nitrogen martensitic stainless steels manufactured by pressurized metallurgy

Effect of nitrogen on microstructure and corrosion behaviour of high nitrogen martensitic stainless steels manufactured by pressurized metallurgy was investigated by microscopy, electrochemical and spectroscopy analyses. Results indicated that increasing nitrogen content significantly enhanced the corrosion properties of martensitic stainless steels, while excess nitrogen deteriorated the corrosion resistance. The impacts of increased nitrogen content could be summarized as three aspects: the change of precipitation content and conversion of main precipitates from MC to MN; the enhanced protection performance of passive film by enrichment of Cr, especially CrO and CrN; the improved repassivation ability by increased nitrogen content in solid solution

Study on the mechanism of excellent strength and toughness combination of a high nitrogen martensitic stainless steel treated by Q-C-P-T process

In this study, a high nitrogen martensitic stainless bearing steel with ultra-high strength and excellent toughness combination treated by quenching-cryogenic cooling-partitioning-tempering (Q-C-P-T) process was obtained. The yield strength, ultimate tensile strength, uniform elongation and the impact energy of the sample after partitioning at 200 °C for 1 h followed by tempering at 400 °C for 1 h are up to 2034 MPa, 2217 MPa, 5.83% and 58.73 J respectively. The microstructure characterization shows that the interstitial atoms of C and N in martensite diffuse into adjacent austenite during the partitioning process, resulting in the high stability of austenite. Strain-induced martensitic transformation was suppressed in maximum, effectively avoiding the formation of hard martensite enriched in C/N and dimensional instability caused by volume expansion of martensitic transformation, which is crucial for bearing steels. And nano-scale precipitates in the martensite matrix effectively compensate for the strength loss of the martensite caused by lower solid solution of carbon and nitrogen, thus obtaining excellent comprehensive mechanical properties. This work paves a new way for the development of advanced bearing steels

Investigation on Microbiologically Influenced Corrosion Behavior of CrCoNi Medium-Entropy Alloy by Pseudomonas Aeruginosa

The CrCoNi medium-entropy alloy (MEA) has excellent strength and toughness, and can be used as the basis for the development of promising engineering alloys in the future. However, microbiologically influenced corrosion (MIC) of CrCoNi MEA has rarely been reported. Especially, pseudomonas aeruginosa (P. aeruginosa) is the typical bacteria associated with MIC, which is widely distributed in the ocean and soil. It can form biofilm on the surface of steel and accelerate the corrosion of carbon steels and stainless steels (SSs). In this study, the electrochemical experiments such as open current potential (OCP), linear polarization resistance (LPR), electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS) and cyclic polarization (CP) were used to investigate the MIC behavior of CrCoNi MEA caused by P. aeruginosa, in comparison with 316L SS. Surface analysis techniques such as FESEM and CLSM were used to observe the P. aeruginosa biofilm and pitting morphology on the coupon surface. The results show that P. aeruginosa could form an uneven biofilm on the surface of CrCoNi MEA coupons. The P. aeruginosa accelerated the corrosion rate of CrCoNi MEA, which was demonstrated by a negative shift of open circuit potential, a decrease of polarization resistance and charge transfer resistance, and an increase of corrosion current density in P. aeruginosa medium. The P. aeruginosa biofilm could destroy the passive film of the CrCoNi MEA coupons, which led to the maximum pit depth of the coupons exposed in P. aeruginosa medium (4.8 mu m) for 14 d much deeper than that in sterile medium (2.3 mu m). Compared with 316L SS, CrCoNi had higher open circuit potential, lower corrosion current density and corrosion rate, and higher repairability of passive film. Meanwhile, the maximum pit depth on the CrCoNi MEA coupons in P aeruginosa medium was shallower than that of 316L SS (5.8 mu m)