2D MXenes are highly attractive for fabricating high-precision gas sensors operated at room temperature (RT) due to their high surface-to-volume ratio. However, the limited selectivity and low ...sensitivity are still long-standing challenges for their further applications. Herein, the self-assembly of 0D–2D heterostructure for highly sensitive NO2 detection was achieved by integrating ZnO nanoparticles on Ti3C2Tx MXene-derived TiO2 nanosheets (designated as ZnO@M−TiO2). ZnO nanoparticles can not only act as spacers to prevent the restacking of M−TiO2 nanosheets and ensure effective transfer for gas molecules, but also enhance the sensitivity of the sensor the through trapping effect on electrons. Meanwhile, M−TiO2 nanosheets facilitate gas diffusion for rapid sensor response. Benefiting from the synergistic effect of individual components, the ZnO@M−TiO2 0D–2D heterostructure-based sensors revealed remarkable sensitivity and excellent selectivity to low concentration NO2 at RT. This work may facilitate the sensing application of MXene derivative and provide a new avenue for the development of high-performance gas sensors in safety assurance and environmental monitoring.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The influence of shaft bending on the coupling vibration of rotor-blades system is nonignorable. Therefore, this paper analyzed the influence of shaft bending on the coupling vibration of ...rotor-blades system. The vibration mode function of shaft under elastic supporting condition was also derived to ensure accuracy of the model as well. The influence of the number of blades, the position of disk, and the support stiffness of shaft on critical speed of system was analyzed. The numerical results show that there were two categories of coupling mode shapes which belong to a set where the blade’s first two modes predominate in the system: shaft-blade (SB) mode and interblade (BB) mode due to the coupling between blade and shaft. The BB mode was of repeated frequencies of (Nb-2) multiplicity for number blades, and the SB mode was of repeated frequencies of (2) multiplicity for number blades. What is more, with the increase of the number of blades, natural frequency of rotor was decreasing linearly, that of BB mode was constant, and that of SB mode was increasing linearly. Natural frequency of BB mode was not affected while that of rotor and SB mode was affected (changed symmetrically with the center of shaft) by the position of disk. In the end, vibration characteristics of coupling mode shapes were analyzed.
Full text
Available for:
FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
In order to improve the precision of short-term power load forecasting, a short-term power load forecasting model based on improved extreme learning machine (MELM) is proposed. The structural risk ...minimization principle and least squares support vector machine are integrated into the model in order to solve the overfitting problem commonly faced by traditional extreme learning machine (ELM) in short-term forecasting. Experimental results using real-world data from electrical power systems show that the forecasting model is better than ELM and OS-ELM in both generalization performance and predictive accuracy, and may provide an effective and practical way for the short-term power load forecasting. This work is supported by National Natural Science Foundation of China (No. 61170120).
Our analytical protocol compared with traditional methods. Display omitted
► Sr and Nd from the same filament loading were sequentially measured without venting using TIMS. ► This protocol shows a ...great improvement in the analytical efficiency. ► Experimental costs and labour intensity are significantly cut down.
Thermal ionization mass spectrometry (TIMS) offers the excellent precision and accuracy of the Sr and Nd isotopic ratio analysis for geological samples, but this method is labour intensive, expensive and time-consuming. In this study, a new analytical protocol by TIMS is presented that aims at improving analytical efficiency and cutting down experimental cost. Using the single-step cation exchange resin technique, mixed Sr and rare earth elements (REEs) fractions were separated from matrix and evaporated to dryness. Afterwards, mixed Sr+REEs fractions were dissolved and loaded onto the same Re filament using 1μL of 2M HCl. Then, Sr and Nd were sequentially measured without venting using TIMS. In contrast to conventional TIMS methods, the merits of this analytical protocol are its cost- and time-saving adaptations. The applicability of our method is evaluated by replicated measurements of 87Sr/86Sr and 143Nd/144Nd for nine international silicate rock reference materials, spanning a wide range of bulk compositions. The typical internal precision in this study is ca. 0.001% (RSE) for 87Sr/86Sr and 143Nd/144Nd; the analytical results obtained for these standard rocks show a good agreement with reported values, indicating the effectiveness of the proposed method.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Primary esophageal or gastric melanoma is a very rare disease with early metastasis. Due to its atypical symptom and less efficiency of chemotherapy and radiotherapy, the prognosis of esophageal or ...gastric melanoma is still very poor. Surgical resection remains the preferential treatment for esophageal or gastric melanoma. Here we present an extremely rare case of primary advanced esophago-gastric melanoma. Debulking surgery was performed without chemotherapy or radiotherapy. However, abdominal recurrence and hepatic metastases were found within one month by a postoperative follow-up computed tomography. Three and a half months after surgical resection, the patient died of extensive abdominal metastasis.
To evaluate the effects of combining the assessment of circulating high-sensitivity C-reactive protein (hs-CRP) with that of Epstein-Barr virus DNA (EBV DNA) in the pretherapy prognostication of ...nasopharyngeal carcinoma (NPC).
Three independent cohorts of NPC patients (training set of n=3113, internal validation set of n=1556, and prospective validation set of n=1668) were studied. Determinants of disease-free survival, distant metastasis-free survival, and overall survival were assessed by multivariate analysis. Hazard ratios and survival probabilities of the patient groups, segregated by clinical stage (T1-2N0-1M0, T3-4N0-1M0, T1-2N2-3M0, and T3-4N2-3M0) and EBV DNA load (low or high) alone, and also according to hs-CRP level (low or high), were compared.
Elevated hs-CRP and EBV DNA levels were significantly correlated with poor disease-free survival, distant metastasis-free survival, and overall survival in both the training and validation sets. Associations were similar and remained significant after excluding patients with cardiovascular disease, diabetes, and chronic hepatitis B. Patients with advanced-stage disease were segregated by high EBV DNA levels and high hs-CRP level into a poorest-risk group, and participants with either high EBV DNA but low hs-CRP level or high hs-CRP but low EBV DNA values had poorer survival compared with the bottom values for both biomarkers. These findings demonstrate a significant improvement in the prognostic ability of conventional advanced NPC staging.
Baseline plasma EBV DNA and serum hs-CRP levels were significantly correlated with survival in NPC patients. The combined interpretation of EBV DNA with hs-CRP levels led to refinement of the risks for the patient subsets, with improved risk discrimination in patients with advanced-stage disease.
Full text
Available for:
GEOZS, IJS, NUK, OILJ, UL, UM, UPUK
Objective
To measure the factors that affect functional leg length of Crowe type IV Developmental dysplasia of the hip (DDH) patients and to review our own methods to balance leg length discrepancy ...(LLD) in Crowe type IV DDH patients.
Methods
This was a prospective observational study which started in June 2017 and ended in August 2019. Inclusion criteria included: (i) Crowe type I or Crowe type IV hip dysplasia patients who underwent total hip arthroplasty (THA) in the Department of Orthopaedics at our institution between July 2017 and June 2018; (ii) the patients were treated with our specific leg length balance strategy; and (iii) the related outcomes of patients were completely recorded. Finally, 18 consecutive Crowe type I patients (20 hips) and 14 consecutive Crowe type IV patients (18 hips) were selected and divided into two groups according to Crowe types. All patients received THA, and patients with a longer affected side and inferior anatomical acetabular positions in Crowe type IV group also received subtrochanteric osteotomy. During operation and after hip reduction, leg lengths were compared while two legs were in an extended position and the operative leg was on top of the non‐operative one. Additional leg length adjustment was applied when leg length was considered to be unequal. Prior to surgery, subluxation height of the femoral head on the affected side, functional LLD, bony length of lower limbs, and distance from teardrops to the lowest point line of the sacroiliac joint were recorded. After surgery, cup sizes, functional LLD, and height of hip rotational centers were measured. Clinical evaluations, such as Harris Hip Score (HHS) and SF‐12 scale, were also obtained before and after surgery for all patients.
Results
At the last follow‐up, functional LLD and clinical measurements of both Crowe type IV group and Crowe type I group were significantly improved. Compared with Crowe type I patients, Crowe type IV patients had a significantly lower MCS, a significantly longer leg lengthening length and a significantly lower hip center height after surgery. Significant differences of tibia length, leg length, and teardrop position were found between affected side and healthy side of Crowe type IV patients. Only three of 14 Crowe type IV patients remained under 1 cm functional LLD. Five patients in the Crowe type IV group developed lower limb numbness immediately following surgery, and they all recovered within 6 months. The average follow‐up period for either group was 14 months, and all patients were followed‐up at 1, 3, 6, and 12 months then yearly after surgery until the final follow‐up.
Conclusion
After detailed leg length balance process, THA combined with transverse sub‐trochanter osteotomy could be an effective method to achieve equal function leg length with most Crowe type IV patients.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Thermal ionization mass spectrometry and multiple-collector inductively coupled plasma mass spectrometry are considered to be "gold standards" for the determination of the isotope ratios of Sr-Nd and ...Hf in geological samples because of the extremely high precision and accuracy of these methods. However, the sample throughputs are hindered by time-consuming and tedious chemical procedures. Three-step ion exchange resin separation is traditionally employed to purify Sr-Nd-Hf from matrix elements. In this study, a one-step Sr-Nd-Hf separation scheme was developed to process geological samples. The separation scheme is based on the combined use of conventional AG50W-X12 cation-exchange resin and LN Spec extraction chromatographic material without any intervening evaporation step. The protocol not only prevents cross-contamination during operation using multiple-stage ion exchange resins but also significantly improves the efficiency of sample preparation. The stability of our chemical procedure was demonstrated by replicate measurements of
87
Sr/
86
Sr,
143
Nd/
144
Nd, and
176
Hf/
177
Hf ratios in six international reference materials of silicate rocks. The analytical results obtained for these standard rocks compare well with the published data. The external reproducibility (2 SD,
n
= 10) of a BCR-2 standard sample was ±0.000018 for
87
Sr/
86
Sr, ±0.000010 for
143
Nd/
144
Nd, and ±0.000014 for
176
Hf/
177
Hf.
One-step separation route based on AG50W-X12 cation-exchange resin and LN Spec extraction chromatographic material for purification of Sr-Nd-Hf from geological samples followed by TIMS and MC-ICP-MS.
Thermal ionization mass spectrometry (TIMS) is the workhorse for lead isotopic ratio analysis due to its excellent precision. Silica gel as ionization activator on Re filament is proved to the best ...emitter that can provide excellent sensitivity even small Pb sample size. However, the price of Re filament is three times that of Ta filament that leads to high experimental cost for TIMS laboratory. Here, we first present a novel silicon nitride (β-Si3N4) emitter on the Ta filament with good sensitivity for Pb isotopic ratio measurements. Hence, the cost of filament material is cut down ∼70%. The β-Si3N4 emitter can yield stable and long-life Pb+ signal, about 2–3 V 208Pb and 0.65–0.90 V 208Pb for 20 ng and 5 ng NIST SRM981 sample size that is applicable to the most geological materials for bulk analysis. A suite of silicate reference materials were analyzed to verify the reliability and accuracy of our method. For 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb isotope ratios of geological samples, excellent internal precisions (2 SE) of ±0.005%–0.013% are achieved. Replicate digestions and analyses of the basalt standard BCR-2 and coal fly ash standard GBW08401 demonstrate that good external precision is obtainable that is 0.10–0.18% (n = 6, 2 SD) for 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios.
Display omitted
•A low-cost and sensitive of β-Si3N4 emitter is presented for Pb isotope analysis.•This method is economy of materials that cut down (∼70%) the cost of the filaments.•β-Si3N4 emitter yields stable and high intensity Pb + signal for 5–20 ng NIST SRM981.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
