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This paper is to determine an initial value for a time-fractional diffusion-wave equation from the final time data. The regularity of the weak solution for the direct problem is improved. The existence and uniqueness of a weak solution for the adjoint problem are proved by using the Fourier method. The Tikhonov regularization method is applied for finding a stable approximate solution. In order to get the minimizer of the Tikhonov regularization functional, we propose a conjugate gradient algorithm based on the strict deductions of the sensitive problem and the adjoint problem. Four numerical examples in one-dimensional and two-dimensional cases are provided to show the effectiveness and stability of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Aim: To investigate the role of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging (DWI) in correcting distortion and evaluating head and neck masses. Materials and methods: Both PROPELLER and echo planar diffusion weighted imaging (EP-DWI) with different b values were performed using 3 T MRI in 50 patients with solid masses of the head and neck. Distortion severity of 50 masses with both DWI techniques and different b values was qualitatively scored and compared. The apparent diffusion coefficient (ADC) values of the 45 masses, in which the distortion scores with both DWI techniques were ≥2, were measured and calculated. The mean ADC value of each DWI sequence between benign and malignant masses was compared. Results: The mean distortion scores of PROPELLER DWIs were significantly higher than EP-DWIs (3.87 versus 1.96, and 3.88 versus 2.00, with b values of 1000 and 500 s/mm2, respectively, p < 0.001), indicating distortion of the mass on PROPELLER DWIs was much less than that on EP-DWIs. With either PROPELLER or EP-DWI, the mean ADC value of 24 malignant tumours was significantly lower than that of 21 benign masses (p < 0.001). Conclusion: Severe distortion of head and neck masses can be reduced significantly using PROPELLER DWI. Moreover, PROPELLER DWI plays an important role in differentiating malignancies from benign masses. [Copyright &y& Elsevier]

To investigate the value of orbital magnetic resonance imaging (MRI) features in predicting the efficacy of intravenous chemotherapy (IVC) for patients with retinoblastoma (RB). The pretreatment clinical and MRI data of 100 eyes from 80 RB patients who underwent IVC were collected retrospectively. There were 59 eyes in the effective group and 41 eyes in the ineffective group, and the baseline data of the two groups were compared statistically. Three radiologists reviewed and evaluated each lesion independently based on 25 MRI features. The predictive values of the MRI features for IVC efficacy were assessed by multi-factor logistic regression analysis, and their odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. Receiver operating characteristic curves (ROCs) with the area under the curve (AUC) were used to determine the predictive abilities. A predictive model was constructed by integrating all independent predictors visualised by the nomogram. RESULTS: There were no statistically significant differences in sex or age between the effective and ineffective groups. The results of multivariate regression analysis showed that laterality, margin, and anterior eye segment enhancement were identified as independent factors that could predict IVC efficacy. The predictive model combining these three features was constructed, and it had an AUC of 0.732 (95% CI: 0.633, 0.831, p <0.01), a sensitivity of 71.2%, and a specificity of 70.7%. CONCLUSION: The data demonstrate that the orbital MRI features can be used to predict IVC efficiency before RB patients are treated. • Value of orbital MRI in predicting the efficacy of IVC for RB were analyzed. • Laterality, margin, and AES enhancement could predict IVC efficacy. • Calcification yielded a poor predictive ability. [ABSTRACT FROM AUTHOR]

The influence of iron on the formation of Al–Mn–Fe intermetallic compounds (IMCs) has been investigated in the solidification of Mg–9Al-0.7Zn-0.2Mn (wt.%, AZ91) with iron contents ranging from ∼0.001 to > 0.01 wt.% Fe. Four Al–Mn–Fe IMCs formed depending on the Fe-content and location in the crucible: B2–Al(Fe,Mn), Al 8 Mn 5 , Al 11 Mn 4 and, at the bottom of crucibles, Al 5 Fe 2. The four IMCs nucleated and grew on one another, producing multiphase particles. These usually contained numerous orientations that were all interrelated through simple orientation relationships that are discussed in terms of the similarities between the IMC crystal structures. The iron content affected the IMC phase fractions and the multiphase particle morphology. At low iron content, the Fe-rich B2 phase was encapsulated by a low-Fe Al 8 Mn 5 shell. With increasing iron content, the Fe-rich phases (B2 and Al 5 Fe 2) gradually became in direct contact with the α-Mg. The threshold Fe:Mn content for adequate corrosion performance is found to correlate approximately to where B2–Al(Fe,Mn) first becomes exposed to the α-Mg matrix. • Al–Mn–Fe IMCs nucleate on each other with interrelated orientation relationships. • Al 8 Mn 5 and Al 11 Mn 4 grow to fully or partially cover the Fe-rich B2–Al(Fe,Mn) core. • B2–Al(Fe,Mn) become in direct contact with α-Mg as Fe content increases. • Threshold Fe:Mn for corrosion correlates to B2–Al(Fe,Mn) becoming exposed to α-Mg. [ABSTRACT FROM AUTHOR]

Aim: To evaluate the efficacy of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) in reducing ocular motion artefacts and improving image quality of orbital magnetic resonance imaging (MRI) at 3 T using an eye surface coil.Materials and Methods: Forty-six patients underwent orbital 3 T MRI using an eye surface coil. The pre-contrast axial T2-wighted (W) PROPELLER and T1 fluid-attenuated inversion recovery (FLAIR) PROPELLER imaging were performed on 21 patients, and conventional T2W and T1W imaging were performed on 25 patients. The ocular motion artefacts, delineation of anatomical structures, depiction of lesions, and image quality were evaluated independently by two radiologists using a five-point scale. The signal-to-noise ratios (SNRs) of anatomical structures and lesions were measured.Results: The interobserver agreement was good to excellent (kappa values from 0.79 to 0.91). PROPELLER sequences had higher scoring than the conventional sequences in all cases (p<0.05). PROPELLER images showed fewer motion artefacts, higher image quality, and more clear delineation of anatomical structures and lesions than the non-PROPELLER images. T2W PROPELLER images produced higher SNRs in lens, vitreous body, lacrimal gland, and lesions than conventional T2W images (p<0.05). T1 FLAIR PROPELLER images showed lower SNRs in lens, vitreous body, medial rectus, lateral rectus, temporalis, and posterior half of optic nerve than conventional T1W images (p<0.05).Conclusion: PROPELLER can effectively reduce ocular motion artefacts and improve image quality, which plays an important role in clearly delineating anatomical structures and lesions on orbital 3 T MRI using an eye surface coil. [ABSTRACT FROM AUTHOR]

Aim To evaluate the value of 3 T Periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) DUO diffusion-weighted MRI (DW-MRI) in differentiating sinonasal lymphomas from carcinomas. Materials and methods PROPELLER DUO DW-MRI was performed in 23 patients with sinonasal lymphomas and 28 patients with carcinomas histologically confirmed at 3 T MRI. Apparent diffusion coefficients (ADCs) were obtained with two different b-values (b = 0 and 700 s/mm 2 , b = 0 and 1000 s/mm 2 ) and two different regions of interest (ROIs) sampling strategies [whole section (WS), partial section (PS)], respectively. Difference in ADCs between sinonasal lymphomas and carcinomas was evaluated using the independent samples t -test or Mann–Whitney U -test. The utility of ADC thresholds for discriminating between them was evaluated by receiver operating characteristic analysis. Results ADCs of sinonasal lymphomas (WS ADC b0,700 , 0.838 × 10 −3 mm 2 /s) were significantly ( p < 0.001) lower than those of carcinomas (WS ADC b0,700 , 1.396 × 10 −3 mm 2 /s). Using a WS ADC b0,700 value of 1.040 × 10 −3 mm 2 /s as the threshold value effectively differentiated sinonasal lymphomas from carcinomas with 100% sensitivity, 82.1% specificity, and 82.1% positive and 100% negative predictive values and 90.2% accuracy (b = 0, 700 s/mm 2 ). There was no significant difference in diagnostic ability between different b-values settings ( p > 0.05) and different sampling strategies of ROIs ( p > 0.05), respectively. Additionally, there was significant differences in the ADCs between diffuse large B-cell lymphomas and natural killer (NK)/T-cell lymphomas ( p < 0.05). Conclusion PROPELLER DUO DW-MRI can effectively differentiate sinonasal lymphomas from carcinomas. [ABSTRACT FROM AUTHOR]

Aim: To investigate the clinical effectiveness, complications, and optimal duration of use of covered retrievable expandable metallic stents in the management of cuff-related tracheal stenosis. Materials and methods: Twenty-one patients with cuff-related tracheal stenosis, Meyer–Cotton grade II (29%) and III (71%), who underwent fluoroscopically guided placement of covered retrievable expandable metallic stents were studied. Sixty-four-section computed tomography (CT) and bronchovideoscopy were performed prior to stent insertion, 1 month after stent insertion, in the case of stent-related complications, and after stent removal. Clinical manifestations, Hugh–Jones classification, and forced expiratory volume in 1 s (FEV1) were used to evaluate respiratory function before and after stent insertion and removal. The diameter of the stricture and FEV1 changes before insertion and after removal were analysed using the paired samples t-test. A p-value of ≤0.05 was considered statistically significant. Results: Twenty-one patients had 27 covered retrievable expandable metallic stents placed. Stents were electively removed from 20 patients. The median duration of stent placement was 5 months (range 4–12 months). One stent was not removed due to mucopolysaccharidosis type II (MPS II or Hunter syndrome) with tracheomalacia. After stent removal, airway dimensions increased and airway occlusion was symptomatically relieved in all patients. CT and bronchovideoscopy showed patent lumens with increased dimensions. Stent-related complications occurred in 19 (91%) patients, including granulation tissue formation (n = 18, 86%), stent migration and stent expectoration (n = 2, 10%), mucus plugging (n = 1, 5%), and halitosis (n = 6, 29%). Some patients experienced multiple complications, which were all managed effectively while the stent was still in place. There was a statistically significant difference in the diameter of the stricture and FEV1 between the time of stent insertion and removal. An improvement in Hugh–Jones classification of greater than one grade was seen in patients after stent removal. Conclusion: Temporary placement of a fully covered retrievable expandable metallic stent is safe and effective in cuff-related tracheal stenosis. The optimal duration of stent placement may be 4–8 months. [Copyright &y& Elsevier]

Aim: To evaluate whether standard magnetic resonance imaging (MRI) could distinguish vagal paragangliomas (VPs) from carotid body tumours (CBTs) in the parapharyngeal space.Methods and Materials: Thirteen VPs in 13 patients and 29 CBTs in 26 patients were included in this study. MRI features were evaluated independently by two head and neck radiologists with 10 and 16 years of experience (X.Wang and Y.Chen).Results: Significant differences were found in shape, direction of internal carotid artery (ICA) displacement, splaying of the carotid bifurcation, involvement of the jugular foramen, and maximum vertical diameters between VPs and CBTs (p=0.016, <0.001, <0.001, <0.001 and <0.001, respectively). Splaying of the carotid bifurcation was found in all the 29 CBTs for both observers, whereas only four VPs for observer 1 and two for observer 2 showed this feature. The ICA was displaced posteriorly in all the 29 patients with CBTs for both observers, and only three patients with VPs for observer 1 and two for observer 2. Involvement of the jugular foramen was found in seven patients with VPs for both observers, while none of patients with CBT showed this feature. With the combination of splaying of the carotid bifurcation and involvement of the jugular foramen, the multiple logistic regression model revealed the diagnostic accuracy was 95.2% for observer 1 and 97.6% for observer 2. With the combination of ICA displacement direction and involvement of the jugular foramen, the diagnostic accuracy was 97.6% for both observers.Conclusion: MRI features can effectively differentiate VPs from CBTs in the parapharyngeal space. [ABSTRACT FROM AUTHOR]

The development of cost-effective electrocatalysts with high efficiency and long durability for hydrogen evolution reaction (HER) remains a great challenge in the field of water splitting. Herein, we design an ultrafine and highly dispersed Ru nanoparticles stabilized on porous V 8 C 7 /C matrix via pyrolysis of the metal-organic frameworks V-BDC (BDC: 1,4-benzenedicarboxylate). The obtained Ru-V 8 C 7 /C composite exhibits excellent HER performance in all pH ranges. At the overpotential of 40 mV, its mass activity is about 1.9, 4.1 and 9.4 times higher than that of commercial Pt/C in acidic, neutral and alkaline media, respectively. Meanwhile, Ru-V 8 C 7 /C shows the remarkably high stability in all pH ranges which, in particular, can maintain the current density of 10 mA cm -2 for over 150 h in 1.0 mol L -1 phosphate buffer saline (PBS). This outstanding HER performance can be attributed to the high intrinsic activity of Ru species and their strong interface interactions to the V 8 C 7 /C substrate. The synergistic effect of abundant active sites on the surface and the formed Ru-C-V units at the interface promotes the adsorption of reaction intermediates and the release of active sites, contributing the fast HER kinetics. This work provides a reference for developing versatile and robust HER catalysts by surface and interface regulation for pH tolerance., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest., (Copyright © 2024 Science China Press. Published by Elsevier B.V. All rights reserved.)