[Progress in research of economic evaluation of non-pharmaceutical interventions for COVID-19 prevention and control].

Objective: To understand the research progresses of economic evaluation of non-pharmaceutical interventions (NPIs) both at home and abroad, and provide reference for economic evaluation of NPIs using real-world data in China. Methods: The literature retrieval was conducted by searching Chinese and English databases to indude papers about economic evaluation of NPIs and integrated NPIs published from January, 2020 to December, 2021, and the results were analyzed comprehensively. Results: A total of 30 Chinese and English literatures about economic evaluation of NPIs for COVID-19 prevention and control were included; including 7 papers about nucleic acid and testing and screening, 6 papers about individual prevention and protection measures, 12 papers about integrated implementation of individual prevention and protection, social distancing, nucleic acid or antigen testing, community screening and symptom screening, as well as close contact tracing and isolation/quarantine, and 5 papers about contain strategies, such as lockdown. This study found that personal protection, social distancing, and testing-tracing-isolation measures were cost-effective; however, different combinations of NPIs might lead to different results. Moreover, the cost of lockdown was high, which might cause huge economic burden. Conclusions: Most NPIs are cost-effective except lockdown, while the cost-effectiveness of the integrations of NPIs at different levels and in different scenarios needs to be further evaluated. It is necessary to carry out economic evaluation of integrated NPIs and the combination of NPIs with other interventions, such as vaccination and medication, based on real-world settings in China.

[Clinical and microbiological characteristics of hypervirulent Klebsiella pneumoniae lung abscess].

Objective: To study the clinical and microbiological characteristics of hypervirulent Klebsiella pneumoniae (hvKP) lung abscess, and to compare with the classic Klebsiella pneumoniae (cKP) lung abscess. Methods: A total of 18 patients with Klebsiella pneumoniae lung abscesses admitted to the First Affiliated Hospital of Zhejiang University School of Medicine from January 2017 to September 2020 enrolled. The strains with positive result of string test were defined as hvKP, and the negative strains were defined as cKP. The patients' basic diseases, symptoms, laboratory data and other clinical characteristics were collected. The microbiological characteristics of the strains included as following: VITEK method to determine the in vitro susceptibility of the strains to antibiotics; PCR to detect the capsular serotypes and virulence genes. The differences in clinical characteristics and microbiological characteristics of strains between hvKP group and cKP group were compared. Results: Among the 18 patients with Klebsiella pneumoniae lung abscess, 12 were hvKP infection, mainly male (10 cases), with a median age of 59.0 years; 8 cases in the hvKP group had an onset time of ≤2 weeks, and the median onset time was 10.5 days. There were significantly more diabetes (12 cases) and extrapulmonary abscesses (11 cases) in hvKP group than those in cKP group (both P<0.001). The extrapulmonary abscesses in the hvKP group were mainly liver abscesses (10 cases), and 4 cases were multi-site (≥3) abscesses. The number of indwelling catheters and invasive procedures before infection were higher in cKP group than those in hvKP group (both P=0.025). The imaging of Klebsiella pneumoniae lung abscess was mainly subpleural with the size of less than 10 cm. There were more multiple abscesses cases in hvKP group (9 cases) than cKP group (P=0.009). The median interval time between the detection of a pulmonary abscess and an extrapulmonary abscess was 1.0 day. The resistance rate of common antibiotics was significantly lower in hvKP than cKP. Conclusions: hvKP lung abscesses are more common in patients with diabetes, and the clinical manifestations are nonspecific. The lung imaging manifestations are multiple subpleural abscesses, indicating hematogenous dissemination. Liver abscesses were present in most cases, suggesting the source of infection. The main virulent gene of hypervirulent Klebsiella pneumoniae is aero. For patients with hvKP lung abscess, attention should be paid to finding hidden lesions.

[Progress in research of economic evaluation of COVID-19 vaccination strategies].

Objective: To understand the research progresses of economic evaluation of COVID-19 vaccination strategies both at home and abroad, and provide reference for the economic evaluation of COVID-19 vaccination strategies using real word data in China. Methods: Literature retrieval was conducted for related papers published from January, 2020 to December, 2021 in Chinese and English databases, including the economic evaluation of COVID-19 vaccination, and the results of the related literatures were narratively integrated. Results: A total of 16 English literatures (including 3 reviews) were included, and it was found that the COVID-19 vaccination was cost-effective or cost-saving regardless of the vaccine types, while the cost-effectiveness in different population and under different vaccination dose strategies varied due to vaccine efficacy, vaccine price, duration of natural immunity, duration of vaccination campaign, vaccine supply, and vaccination pace. Conclusions: China lacks suitable evidences of economic evaluation of COVID-19 vaccination strategies based on real-world data in the context of long-term epidemic. Therefore, further researches of suitable strategies of booster COVID-19 vaccination are needed.

[Characteristics of disturbance coefficient in children without craniocerebral injury at different ages].

Objective: To explore the reference ranges and influential factors of disturbance coefficient (DC) in children without craniocerebral injury at different ages. Methods: Two hundred children without craniocerebral injury admitted to the Department of Orthopaedics in Children's Hospital of Chongqing Medical University from May 2018 to October 2019 were enrolled in this prospective study. The children were divided into four groups according to age, 0-1 year, >1-3 years, >3-5 years and >5-16 years, each of which included 50 children. Each child had DC measured twice with the non-invasive dynamic cerebral edema monitor, and the average value was used as the terminal DC value. Each measurement lasted 15 minutes, 12 hours apart. The difference of DC values among the four groups and between different genders were compared with ANOVA test and nonparametric test. And the Loess local weighted nonparametric regression analysis was used to explore the change of DC according to the increase of age, weight and head circumference (HC). Results: The reference values of DC for children of 0-1 year,>1-3 years, >3-5 years, and >5-16 years were 60±14, 92±18, 112±18, 135±18, respectively (F=175.690, P<0.01). There was no statistical significance in DC between male and female children either in the whole or in each separate age group (103 (81, 125) vs. 102 (68, 123) , Z=-0.739, P=0.460; 59 (52, 68) vs. 57 (53, 65) , Z=-0.243, P=0.808; 88 (81, 105) vs. 95 (70, 105) , Z=-0.776, P=0.437; 117 (99, 120) vs. 113 (101, 123) , Z=-0.170, P=0.865; 137 (123, 143) vs. 142 (123, 160) , Z=-1.279, P=0.201). When the child's age was younger than 5 years, weight was less than 18 kg or HC was less than 51 cm, the DC increased significantly with the increase of age, weight or HC. However, when the age, weight and HC were over the above values, the DC did not show obvious increase, but approaching to stable values of 135, 130, and 130, respectively. Conclusions: For children without craniocerebral injury, the reference values of DC are obviously different at different ages. DC is positively related to age, weight and HC, but not related to gender.

Graphene oxide-Au nano particle coated quartz crystal microbalance biosensor for the real time analysis of carcinoembryonic antigen.

A label-free quartz crystal microbalance (QCM) biosensor was developed for the selective and real-time estimation of carcinoembryonic antigen (CEA) through the present study. Graphene oxide-Au nanoparticles (GO-AuNPs) was in situ synthesised on the surface of the QCM electrode and the antibody of CEA (monoclonal anti-CEA from mouse) was covalently immobilized on this layer as the bioreceptor for CEA. Mercaptoacetic acid-EDC-NHS reaction mechanism was used for anti-CEA immobilization. The effect of oxygen plasma treatment of the QCM electrode surface before bioreceptor preparation on the performance of the biosensor was tested and was found promising. CEA solutions with various concentrations were analysed using the bioreceptors to estimate the sensitivity and detection limit of the biosensor. The biosensors selectively recognized and captured CEA biomolecules with a detection limit of 0.06 and 0.09 ng mL-1 of CEA for oxygen plasma-treated (E2) and untreated (E1) bioreceptors, respectively. The sensitivity was estimated at 102 and 79 Hz, respectively, for E2 and E1. Clinical serum samples were analysed and the results were found in good agreement with the ELISA analysis. Long term stability was also found to be excellent. Langmuir adsorption isotherm was also conducted using the experimental results.

Integrated sensing layer of bacterial cellulose and polyethyleneimine to achieve high sensitivity of ST-cut quartz surface acoustic wave formaldehyde gas sensor.

Surface acoustic wave (SAW)-based formaldehyde gas sensor using bi-layer nanofilms of bacterial cellulose (BC) and polyethyleneimine (PEI) was developed on an ST-cut quartz substrate using sol-gel and spin coating processes. BC nanofilms significantly improve the sensitivity of PEI films to formaldehyde gas, and reduces response and recovery times. The BC films have superfine filamentary and fibrous network structures, which provide a large number of attachment sites for the PEI particles. Measurement results obtained using in situ diffuse reflectance Fourier transform infrared spectroscopy showed that the primary amino groups of PEI strongly adsorb formaldehyde molecules through nucleophilic reactions, thus resulting in a negative frequency shift of the SAW sensor due to the mass loading effect. In addition, experimental results showed that the frequency shifts of the SAW devices are determined by thickness of PEI film, concentration of formaldehyde and relative humidity. The PEI/BC sensor coated with three layers of PEI as the sensing layer showed the optimal sensing performance, which had a frequency shift of 35.6 kHz for 10 ppm formaldehyde gas, measured at room temperature and 30 % RH. The sensor also showed good selectivity and stability, with a low limit of detection down to 100 ppb.

[Clinical feature analysis of 30 cases with pulmonary actinomycosis].

Objective: To summarize the clinical characteristics of pulmonary actinomycosis and analyze its diagnostic methods. Methods: The clinical symptoms, underlying diseases, imaging characteristics, preliminary diagnosis, diagnostic methods, treatment and prognosis of 30 patients with pulmonary actinomycetes admitted into the First Affiliated Hospital of Zhejiang University School of Medicine during the 10 years (January 2007 to November 2017) were retrospectively analyzed. Results: The 30 patients with pulmonary actinomycetes included were from 47 to 81 years old, with an average age of (59.5±7.8) years, with a course of disease from 5 days to 48 months, and a median course of disease of 1.5 months; 18 patients (60.0%) were complicated with underlying diseases, 10 patients (33.3%) had a history of smoking, 10 patients (33.3%) had a history of alcohol abuse. The main clinical manifestations were cough in 29 cases (96.7%), followed by sputum in 22 cases (73.3%), hemoptysis in 20 cases (66.7%), fever in 12 cases (40.0%), chest pain in 5 cases (16.7%) and shortness of breath in 3 cases (10.0%). Mass, nodules, consolidation, atelectasis can be seen by imaging, there can be a low-density lesion necrosis, formation of voids or vacuoles. Among the 25 patients (83.3%) who underwent bronchoscopy, 14 cases were abnormal, 5 cases showed endotracheal polypoid neoplasms, 9 cases showed endotracheal mucosal inflammatory changes, 2 cases of them showed bronchial foreign body, and 1 case showed broncholithiasis. All cases were diagnosed by pathology. Nine cases (30.0%) were confirmed by bronchoscopic biopsy. Two cases (6.7%) underwent CT-guided percutaneous lung biopsy, 18 cases (60.0%) underwent surgical resection of pathology, and 1 case (3.3%) was diagnosed by puncture of chest wall mass. Sufficient dose and course of penicillin were effective. Surgical excision of the lesion with antibiotics for 2-4 weeks was effective. Conclusion: The clinical manifestation of pulmonary actinomycosis is lack of specificity, obtaining positive pathological specimens is the key to the diagnosis of this disease, the first choice is bronchoscopy and percutaneous lung biopsy.

Molecular differentiation of three canine and feline hookworms in South China through HRM analysis.

To investigate the prevalence of canine and feline hookworms in South China, and to assess the risk of zoonotic hookworms to humans, one pair of primers (HRM-F/HRM-R) was designed to establish a high-resolution melting (HRM) method based on internal transcribed spacer 1 (ITS-1) rDNA for the detection of Ancylostoma ceylanicum, A. caninum and A. tubaeforme infection. The results showed that the HRM for the three hookworms produced different melting-curve profiles, where melting temperature (Tm) values were 84.50°C for A. ceylanicum, 82.25°C for A. caninum and 81.73°C for A. tubaeforme, respectively. The reproducibility of intra- and inter-assay melting curves was almost perfect. The lowest concentration detected was about 5.69 ×10-4 g/µl. The HRM detection results from 18 canine and feline hookworm samples were in complete accordance with their sequencing results. The HRM method was more sensitive than the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique in the detection of 98 clinical samples. It is concluded that the HRM method can differentiate between A. ceylanicum, A. caninum, A. tubaeforme and their mixed infections, which may provide important technical support for the zoonotic risk assessment and molecular epidemiological survey of canine and feline hookworms.

The mitochondrial genome of Dipetalonema gracile from a squirrel monkey in China.

Dipetalonema gracile is a common parasite in squirrel monkeys (Saimiri sciureus), which can cause malnutrition and progressive wasting of the host, and lead to death in the case of massive infection. This study aimed to identify a suspected D. gracile worm from a dead squirrel monkey by means of molecular biology, and to amplify its complete mitochondrial genome by polymerase chain reaction (PCR) and sequence analysis. The results identified the worm as D. gracile, and the full length of its complete mitochondrial genome was 13,584 bp, which contained 22 tRNA genes, 12 protein-coding genes, two rRNA genes, one AT-rich region and one small non-coding region. The nucleotide composition included A (16.89%), G (20.19%), T (56.22%) and C (6.70%), among which A + T = 73.11%. The 12 protein-coding genes used TTG and ATT as start codons, and TAG and TAA as stop codons. Among the 22 tRNA genes, only trnS1AGN and trnS2UCN exhibited the TΨC-loop structure, while the other 20 tRNAs showed the TV-loop structure. The rrnL (986 bp) and rrnS (685 bp) genes were single-stranded and conserved in secondary structure. This study has enriched the mitochondrial gene database of Dipetalonema and laid a scientific basis for further study on classification, and genetic and evolutionary relationships of Dipetalonema nematodes.

Bimorph material/structure designs for high sensitivity flexible surface acoustic wave temperature sensors.

A fundamental challenge for surface acoustic wave (SAW) temperature sensors is the detection of small temperature changes on non-planar, often curved, surfaces. In this work, we present a new design methodology for SAW devices based on flexible substrate and bimorph material/structures, which can maximize the temperature coefficient of frequency (TCF). We performed finite element analysis simulations and obtained theoretical TCF values for SAW sensors made of ZnO thin films (~5 µm thick) coated aluminum (Al) foil and Al plate substrates with thicknesses varied from 1 to 1600 µm. Based on the simulation results, SAW devices with selected Al foil or plate thicknesses were fabricated. The experimentally measured TCF values were in excellent agreements with the simulation results. A normalized wavelength parameter (e.g., the ratio between wavelength and sample thickness, λ/h) was applied to successfully describe changes in the TCF values, and the TCF readings of the ZnO/Al SAW devices showed dramatic increases when the normalized wavelength λ/h was larger than 1. Using this design approach, we obtained the highest reported TCF value of -760 ppm/K for a SAW device made of ZnO thin film coated on Al foils (50 µm thick), thereby enabling low cost temperature sensor applications to be realized on flexible substrates.

KrasG12D-LOH promotes malignant biological behavior and energy metabolism of pancreatic ductal adenocarcinoma cells through the mTOR signaling pathway.

Oncogenic Kras with loss of heterozygosity (LOH) is frequently detected in various tumours. However, the exact function and mechanism by which KrasG12D-LOH operates remain unclear. Therefore, the current study investigated the effect of KrasG12D-LOH on the malignant phenotype of pancreatic ductal adenocarcinoma (PDAC) cells. Our investigation revealed that KrasG12D-LOH is associated with increased proliferation, invasion and reduced apoptosis in PDAC cells. The results also exhibited enhanced glycolytic phenotype of KrasG12D-LOH PDAC cells. Hyperactive mTOR plays a significant role in the initiation and maintenance of tumors. To investigate the correlation between KrasG12D-LOH and mTOR, the mTOR signaling pathway was detected by western blot analysis. We found that KrasG12D-LOH up-regulated Akt, AMPK, REDD1 and mTOR in PDAC cells. In summary, our results demonstrated that KrasG12D-LOH promotes oncogenic Kras-induced PDAC by regulating energy metabolism and mTOR signaling pathway. These data may provide novel therapeutic perspectives for PDAC.

The mitochondrial genome of Ancylostoma tubaeforme from cats in China.

Ancylostoma tubaeforme may infect canids, felids and humans, and pose a potential risk to public health. Polymerase chain reaction (PCR) techniques were used to amplify the complete mitochondrial (mt) genome sequence of A. tubaeforme from cats and to analyse its sequence characteristics after molecular identification based on the internal transcribed spacer ITS1+ sequence. The results show that the complete mt genome sequence (GenBank accession number KY070315) of A. tubaeforme from cats was 13,730 bp in length, including 12 protein-coding genes, 22 transfer RNA (tRNA) genes, two ribosomal RNA (rRNA) genes, two non-coding regions and an AT-rich region. The nucleotide content of A and T was 77.93%, biased toward A and T. Twelve protein-coding genes used ATT, TTG and GTG as initiation codons, and TAA, TAG, TA and T as termination codons. The length of the 22 tRNA genes ranged from 52 to 62 bp, their predicted secondary structures were D loops and V loops. The lengths of the two rRNAs were 958 and 697 bp. Phylogenetic analyses showed that A. tubaeforme from cats was in the lineage of Ancylostoma, having a close phylogenetic relationship with A. caninum. This study reports for the first time the mt genome of A. tubaeforme from cats in China, which could enhance the mt genome database of Ancylostomatidae nematodes, and it offers the scientific basis for further studies in the genetic diversity of hookworms among different hosts.

[Clinical efficacy of one-lung ventilation in treatment of children postoperatively intractable atelectasis].

Objective: To investigate the effect of fiberoptic bronchoscope-guided one-lung ventilation (OLV) on treatment of intractable atelectasis in children. Method: This retrospective cohort study was conducted in Pediatric Intensive Care Unit, Children's Hospital of Chongqing Medical University from December 2014 to May 2017. Six patients with intractable atelectasis of left lung were included. Three cases were male and three female with the age from 1.5 to 11.0 years. The endotracheal tube was intubated to the left main bronchus for OLV by the guidance of fiberoptic bronchoscopy. The effect of treatment by monitoring the chest imaging after treatment was evaluated. Result: Six pediatric patients were successfully cured by OLV. The duration of OLV ranged from 1.5 to 30.0 hours, and the intervals of OLV were usually 3 to 5 days. Each patient received 6 to 20 OLV treatments. Chest images showed the left lung reexpanded obviously after OLV treatments. Five patients successfully weaned from invasive ventilation and were discharged. Another patient turned better, discharged from hospital with noninvasive ventilation and weaned from noninvasive ventilation one month later after discharge. During the procedure of OLV, the vital signs of all patients were stable and no complication occurred. Conclusion: OLV with selective bronchial intubation guided by fiber bronchoscope is a safe and effective treatment for intractable atelectasis in children.

[Patients of Escherichia coli bloodstream infection: analysis of antibiotic resistance and predictors of mortality].

Objective: To analyze the drug resistance of Escherichia coli (E.coli) from bloodstream infection (BSI) and the predictors of mortality in E. coli bloodstream infection (BSI). Methods: The clinical data of 139 E. coli BSI cases diagnosed from January 2012 to December 2015 in The Second Affiliated Hospital of Zhejiang University School of Medicine, Lanxi Branch (Lanxi People's Hospital), Zhejiang Province, were retrospectively analyzed. The antimicrobial susceptibility testing was performed using Vitek 2 system. Extended-spectrum beta-lactamases (ESBLs) were detected by disk diffusion confirmatory testing. The factors associated with ESBLs-producing strains were identified by univariate analysis. Multivariate analysis was used to identify independent predictors of infection mortality by applying Logistic regression. Results: 42.4% of E. coli isolates were ESBLs-producing. The resistant rate of imipenem was 0.7%. The percent of ESBLs in hospital-acquired infection was higher than that in community-acquired infection but without statistical significance (48.7% versus 40.0%, P=0.350). Univariate analysis suggested that the percent of ESBLs-producing strains in BSI happened on ≥15 d after admission and in BSI of biliary tract infection source was 76.9% and 68.0%, which were much higher than those in BSI happened on <15 d after admission and in BSI of non-biliary tract infection source (34.6% and 36.8%, P=0.013 and 0.004). The overall mortality of E. coli BSI was 13.7%. Multivariate Logistic regression analysis indicated that Sequential Organ Failure Assessment (SOFA ) score (OR=1.393, P<0.001), ceftazidime non-susceptibility (OR=4.444, P=0.018) and liver cirrhosis (OR=13.513, P=0.001) were independent risk factors of mortality. Conclusions: The frequency of ESBLs-producing E. coli was high in primary hospital of Zhejiang Province. SOFA score, ceftazidime non-susceptibility and cirrhosis were predictors of poor outcome in E. coli BSI.

Transparent flexible thermoelectric material based on non-toxic earth-abundant p-type copper iodide thin film.

Thermoelectric devices that are flexible and optically transparent hold unique promise for future electronics. However, development of invisible thermoelectric elements is hindered by the lack of p-type transparent thermoelectric materials. Here we present the superior room-temperature thermoelectric performance of p-type transparent copper iodide (CuI) thin films. Large Seebeck coefficients and power factors of the obtained CuI thin films are analysed based on a single-band model. The low-thermal conductivity of the CuI films is attributed to a combined effect of the heavy element iodine and strong phonon scattering. Accordingly, we achieve a large thermoelectric figure of merit of ZT=0.21 at 300 K for the CuI films, which is three orders of magnitude higher compared with state-of-the-art p-type transparent materials. A transparent and flexible CuI-based thermoelectric element is demonstrated. Our findings open a path for multifunctional technologies combing transparent electronics, flexible electronics and thermoelectricity.

[Application of improved regional citrate anticoagulation in continuous hemofiltration in children].

Objective: To investigate the application of regional citrate anticoagulation with calcium hemofiltration basic solution in continuous hemofiltration in children. Method: The clinical data of 18 patients with citrate anticoagulation in continuous hemofiltration in children, excluding the hepatic failure and septic shock cases, were analyzed retrospectively, from September 2015 to August 2016 in Intensive Care Unit of the Children's Hospital of Chongqing Medical University.The commercial calcium hemofiltration basic solution was used as displacement liquid . The blood gas analysis, electrolyte, four coagulation tests during the treatment and the corresponding relations of quantity of blood flow(QB), quantity of citrate flow(QCi), quantity of sodium bicarbonate flow(QSB), quantity of calcium flow(QCa), quantity of filtered solution flow (Qf) were monitored. Meanwhile, the blood gas analysis, electrolyte, four coagulation tests, useful life of filter, bleeding and clotting events internal and external before, during and after the treatments were monitored, too. And the common complications of citrate anticoagulation, such as hypocalcaemia, metabolic alkalosis, citrate accumulation and hypernatremia were observed. Result: Continuous hemofiltration was applied in 18 patients for 734.5 hours, and the average useful life of filter was (25±11)h.There was no obvious clotting event. There were 168 groups of datum of the blood gas analysis, electrolyte, four coagulation tests during the treatment and the relationships of QB, QCi, QSB, QCa, Qf had been collected. The relationships of the initial parameter settings of QB, QCi, QSB, QCa and Qf were concluded as QCi=1.8×QB, QCa=0.12×QB, QSB=0.01×Qf . There were 150 times(89.3%)of extracorporeal ionized calcium(iCa(E)(2+)) and 162 times(96.4%) of intracorporal ionized calcium(iCa(I)(2+)) reached the anticoagulation target. Although all the comparisons of Na(+) ((136.2±4.1)vs.(138.2±2.4)vs.(138.5±3.9)mmol/L), iCa(2+) ((1.07±0.11)vs.(1.21±0.12)vs.(1.17±0.09)mmol/L), HCO(3)(-) ((22±4)vs.(28±5)vs. (26±4)mmol/L) among before, during and after treatment had significant difference(F=6.414, 18.950, 19.151; P=0.002, 0.000, 0.000). Each mean parameter was within the nearly normal range, except that the HCO(3)(-) increased slightly. High HCO(3)(-) was the most common complications, which happened 87 times (51.8%) during the treatment and 11 cases(37.9%) after the treatment. There was none with refractory hypocalcemia and total ionized calcium(TCa(2+) )/iCa(2+) above 2.5, which hints the accumulation of citrate. Conclusion: The commercialized displacement liquid containing calcium can be used in RCA-CHF in children safely and simply.

Origin of Structural Transformation in Mono- and Bi-Layered Molybdenum Disulfide.

Mono- and multi-layered molybdenum disulfide (MoS2) is considered to be one of the next generation anode materials for rechargeable ion batteries. Structural transformation from trigonal prismatic (2H) to octahedral (1T) upon lithium or sodium intercalation has been in-situ observed experimentally using transmission electron microscope during studies of their electrochemical dynamics processes. In this work, we explored the fundamental mechanisms of this structural transformation in both mono- and bi-layered MoS2 using density functional theory. For the intercalated MoS2, the Li and Na donate their electrons to the MoS2. Based on the theoretical analysis, we confirmed that, for the first time, electron transfer is dominant in initiating this structural transformation, and the results provide an in-depth understanding of the transformation mechanism induced by the electron doping. The critical values of electron concentrations for this structural transformation are decreased with increasing the layer thickness.

Defect-Mediated Lithium Adsorption and Diffusion on Monolayer Molybdenum Disulfide.

Monolayer Molybdenum Disulfide (MoS2) is a promising anode material for lithium ion batteries because of its high capacities. In this work, first principle calculations based on spin density functional theory were performed to investigate adsorption and diffusion of lithium on monolayer MoS2 with defects, such as single- and few-atom vacancies, antisite, and grain boundary. The values of adsorption energies on the monolayer MoS2 with the defects were increased compared to those on the pristine MoS2. The presence of defects causes that the Li is strongly bound to the monolayer MoS2 with adsorption energies in the range between 2.81 and 3.80 eV. The donation of Li 2s electron to the defects causes an enhancement of adsorption of Li on the monolayer MoS2. At the same time, the presence of defects does not apparently affect the diffusion of Li, and the energy barriers are in the range of 0.25-0.42 eV. The presence of the defects can enhance the energy storage capacity, suggesting that the monolayer MoS2 with defects is a suitable anode material for the Li-ion batteries.

High sensitivity flexible Lamb-wave humidity sensors with a graphene oxide sensing layer.

This paper reports high performance flexible Lamb wave humidity sensors with a graphene oxide sensing layer. The devices were fabricated on piezoelectric ZnO thin films deposited on flexible polyimide substrates. Two resonant peaks, namely the zero order antisymmetric (A0) and symmetric (S0) mode Lamb waves, were observed and fitted well with the theoretical analysis and modelling. With graphene oxide microflakes as the sensing layer, the sensing performance of both wave modes was investigated. The humidity sensitivity of the A0 mode is 145.83 ppm per %RH (at humidity 85%RH), higher than that of S0 mode of 89.35 ppm per %RH. For the first time, we have demonstrated that the flexible humidity sensors work as usual without noticeable deterioration in performance even under severe bending conditions up to 1500 µÎµ. Also the sensors showed an excellent stability upon repeated bending for thousand times. All the results demonstrated that the Lamb wave flexible humidity sensors have a great potential for application in flexible electronics.