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Aldehydes as an environmental pollutant may lead to oxidative stress, which is an important mechanism in the development of osteoporosis. This suggests a possible link between aldehyde exposure and osteoporosis. Considering the mixed nature of aldehyde exposure and the interactions between different aldehydes, we explored for the first time the associations between mixed six aldehydes (benzaldehyde, butyraldehyde, heptanal, hexanal, isovaleraldehyde, and propionaldehyde) and BMD in three populations (men, premenopausal women, and postmenopausal women) by applying four statistical models: quantile g-computation (qgcomp) model, Bayesian kernel machine regression (BKMR) model, generalized linear regression model (GLM), and generalized additive model (GAM), based on the National Health and Nutrition Examination Survey (NHANES) 2013-2014. We found that mixed aldehydes could significantly reduce BMD in men, with hexanaldehyde and propanaldehyde having the greatest negative qgcomp model and BKMR model weights, also confirmed by GLM. The associations between isopentanaldehyde and propanaldehyde and femoral BMD in men were non-linear and had threshold effects as derived from the BKMR model and GAM. The associations turned positive when the concentrations of isopentanaldehyde and propanaldehyde exceeded their respective inflection points. To conclude, our study might provide new ideas for the prevention and treatment of osteoporosis, and hexanaldehyde and propanaldehyde should be more regulated to prevent osteoporosis.

In the repair of maxillofacial bone defects, autogenous craniofacial bone can often provide superior clinical results over long bone grafts. Most current studies have focused on the osteogenic differences between alveolar bone marrow (ABM) and long bone marrow (LBM), however, studies about the angiogenic differences between the two are currently lacking. We downloaded single-cell RNA sequencing (scRNA-seq) of mouse ABM and LBM respectively from the public database, and the data were processed by using Seurat package. CellphoneDB2 results showed that macrophages had the strongest interaction with mesenchymal stem cells (MSCs) and endothelial cells (ECs). ELISA results confirmed that ABM macrophages secreted a higher level of vascular endothelial growth factor A (Vegfa) compared to LBM macrophages, which further promoted angiogenesis of ECs and MSCs. Using SCENIC package, six key transcription factors (TFs) were identified to regulate the difference between ABM and LBM macrophages, and activating transcription factor 4 (Atf4) was confirmed to be more expressed in ABM macrophages by polymerase chain reaction (PCR) and western blot (WB), with predicted target genes including Vegfa. Besides, the result of scRNA-seq implied ABM macrophages more in M1 status than LBM macrophages, which was confirmed by the following experiments. From the results of another assay for transposase accessible chromatin sequencing (ATAC-seq) and RNA-seq about M1 macrophages, Atf4 was also confirmed to regulate the M1 polarization. So, we suspected that Atf4 regulated the different expression of Vegfa between ABM and LBM macrophages by activating M1 polarization. After knocking down Atf4, the expression of M1 polarization markers and Vegfa were downregulated and vasculogenic differences were eliminated, which were subsequently reversed by the addition of LPS/IFN-γ. Our study might provide a new idea to improve the success rate of autologous bone grafting and treatment of oral diseases.

Objectives The coronavirus disease 2019 (COVID-19) is a resource-intensive global pandemic. It is important for healthcare systems to identify high-risk COVID-19-positive patients who need timely health care. This study was conducted to predict the hospitalization of older adults who have tested positive for COVID-19. Methods We screened all patients with COVID test records from 11 Mass General Brigham hospitals to identify the study population. A total of 1495 patients with age 65 and above from the outpatient setting were included in the final cohort, among which 459 patients were hospitalized. We conducted a clinician-guided, 3-stage feature selection, and phenotyping process using iterative combinations of literature review, clinician expert opinion, and electronic healthcare record data exploration. A list of 44 features, including temporal features, was generated from this process and used for model training. Four machine learning prediction models were developed, including regularized logistic regression, support vector machine, random forest, and neural network. Results All 4 models achieved area under the receiver operating characteristic curve (AUC) greater than 0.80. Random forest achieved the best predictive performance (AUC = 0.83). Albumin, an index for nutritional status, was found to have the strongest association with hospitalization among COVID positive older adults. Conclusions In this study, we developed 4 machine learning models for predicting general hospitalization among COVID positive older adults. We identified important clinical factors associated with hospitalization and observed temporal patterns in our study cohort. Our modeling pipeline and algorithm could potentially be used to facilitate more accurate and efficient decision support for triaging COVID positive patients.

The operation of gyrotrons highly depends on the alignment between the magnet and the tube, which will cause instability problems or degrade the output efficiency, especially for high-frequency gyrotrons with a small cavity size. In this letter, the influence of misalignment, including parallel shift, arbitrary tilt, and their co-existence, on the behavior of the electron beam was studied. A prototype of an 800 GHz gyrotron with a sapphire window was developed to study the correlation between the misalignment and the beam trajectory. A method to determine the tilt angle and shift distance was proposed. The feasibility of the misalignment correction method was verified in the experiment.

Dopamine receptor, a polypeptide chain composed of 7 hydrophobic transmembrane regions, is a new and vital drug target, especially Dopamine receptor 2(D2). Targeting dopamine receptors, Dopamine receptor agonists are a class of drugs similar in function and structure to dopamine and can directly act on dopamine receptors and activate it. Clinically, Dopamine receptor agonist drugs have achieved significant therapeutic effects on prolactinoma and Parkinson's Disease. In the study, we virtually screened a series of potential effective agonists of Dopamine receptor by computer techniques. Firstly, we used the Molecular Docking (LibDock) step to screen out some molecules that can dock well with the protein. Then, analysis of toxicity prediction and ADME (adsorption, distribution, metabolism and excretion) were carried out. More precise molecular docking (CDOCKER) and 3-Dimensional Quantitative Structure-Activity Relationship Modeling Study(3D-QSAR) pharmacophore generation were implemented to research and explore these compounds' binding mechanism with Dopamine receptor. Last but not least, to assess compound's binding stabilities, we carried out a molecular dynamic analysis. As the results show, two compounds (ZINC000008860530 and ZINC000004096987) from the small molecule database (ZINC database) were potential effective agonists of Dopamine receptor. These two compounds can combine with Dopamine receptor with higher affinity and proved to be no toxic. The cell experiment showed that two compounds could inhibit the proliferation and PRL secretion of MMQ cells (pituitary tumor cells). Thus, this study provided valuable information about Dopamine receptor agonist-based drug discovery. So, this study will benefit patients with prolactinoma and Parkinson’s disease a lot.

To identify novel prognostic and therapeutic targets for osteosarcoma patients, we compared the gene expression profiles of osteosarcoma and control tissues from the GSE42352 dataset in the Gene Expression Omnibus. Differentially expressed genes were subjected to Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Gene Set Enrichment and protein-protein interaction network analyses. Survival curve analyses indicated that osteosarcoma patients with lower mRNA levels of cyclin-dependent kinase 1 (CDK1) and topoisomerase II alpha had better prognoses. Various computer-aided techniques were used to identify potential CDK1 inhibitors for osteosarcoma patients, and PHA-793887 was predicted to be a safe drug with a high binding affinity for CDK1. In vitro, MTT and colony formation assays demonstrated that PHA-793887 reduced the viability and clonogenicity of osteosarcoma cells, while a scratch assay suggested that PHA-793887 impaired the migration of these cells. Flow cytometry experiments revealed that PHA-793887 dose-dependently induced apoptosis in osteosarcoma cells. Western blotting and enzyme-linked immunosorbent assays indicated that CDK1 expression in osteosarcoma cells declined with increasing PHA-793887 concentrations. These results suggest that PHA-793887 could be a promising new treatment for osteosarcoma.

Phenols and parabens widely exist in personal care and consumer products and have been proved to be endocrine disrupting chemicals that could disturb bone metabolism. The current studies focusing on the associations between phenols and parabens with bone mineral density (BMD) drew contradictory conclusions. Considering the bias might be due to not considering the effects of mixed exposure, we conducted the first cross-sectional study to investigate the associations of both single and mixed metabolites of phenols and parabens with BMD in three populations by setting up four models: generalized linear regression model (GLM), weighted quantile sum (WQS) regression model, quantile g-computation (qgcomp) model and Bayesian kernel machine regression (BKMR) model, based on the US National Health and Nutrition Examination Survey (NHANES) database. We found that the association between the mixtures and total femur BMD in men was significantly negative. Bisphenol A (BPA) was shown to play the most important role in this negative association in the BKMR model, and this negative association was also confirmed in the GLM model with β coefficient (95% CI) being -0.02 (-0.04, -0.01). The relationships between the mixtures and femoral neck and trochanter BMD in postmenopausal women were significantly positive. Benzophenone-3 (BP-3) played the most significant role in the positive association with trochanter BMD, as confirmed by the WQS, qgcomp and BKMR models, and this positive association was also verified by the GLM model with β coefficient (95% CI) being 0.01 (0.00, 0.02). In conclusion, the association between the mixed phenols and parabens and BMD was negative in men while was positive in postmenopausal women, which was gender-specific. This study might provide new ideas for the prevention and treatment of osteoporosis and the control of personal care and consumer products containing phenols and parabens in the future.

Human adipose-derived stem cells (hASCs) have multi-directional differentiation potential including osteogenic differentiation. Mechanical stimulation is thought to be a key regulator of bone remodeling and has been proved to promote osteogenic differentiation of mesenchymal stem cells. However, the mechanism how mechanical tension-induced osteogenesis of hASCs still remains poor understood. Polycystin-2 (PC2), a member of the transient receptor potential polycystic (TRPP) family, is involved in cilia-mediated mechanical transduction. To understand the role of PC2 in osteogenic differentiation under mechanical stimuli in hASCs, PKD2 gene was stably silenced by using lentivirus-mediated shRNA technology. The results showed that mechanical tension sufficiently enhanced osteogenic differentiation but hardly affected proliferation of hASCs. Silencing PKD2 gene caused hASCs to lose the ability of sensing mechanical stimuli and subsequently promoting osteogenesis. PC2 knock-out also reduced the cilia population frequency and cilia length in hASCs. TAZ (transcriptional coactivator with PDZ-binding motif, also known as Wwtr1) could mediate the genes regulation and biological functions of mechanotransduction signal pathway. Here, mechanical tension also enhanced TAZ nuclear translocation of hASCs. PC2 knock-out blocked tension-induced upregulation of nuclear TAZ and suppress tension-induced osteogenesis. TAZ could directly interact with Runx2, and inhibiting TAZ could suppress tension-induced upregulation of Runx2 expression. In summary, our findings demonstrated that PC2 mediate mechanical tension-induced osteogenic differentiation of hASCs by activating TAZ.

The successful operation of the gyrotron strongly depends on the proper alignment of the gyrotron with the magnet. The difficulty of the alignment will increase as the frequency becomes higher, especially for the terahertz pulsed gyrotron. In this article, we describe an easily implemented alignment method in detail. A triaxial adjusting flange was designed to align the gyrotron. The alignment of the gyrotron can be identified by the fluorescent effect of the electron beam on the sapphire output window, which will be captured by triggering a charge-coupled device camera. The affine transformation was also used to correct the distorted image. The validity of the proposed alignment method is verified via a prototype of an 800-GHz second-harmonic pulsed gyrotron.

OBJECTIVES The aim was to evaluate the effectiveness of a pre-clinical training of ceramic crown preparation using the Virtual Educational System for Dentistry. MATERIAL AND METHODS Fifty-seven dental students were recruited to prepare a ceramic crown under the guidance of the Real-time Dental Training and Evaluation System (RDTES) in order to collect pre-learning data. They participated in the online virtual learning course independently on the Virtual Learning Network Platform (VLNP). One week later, the students were invited to complete their post-learning crown preparation with the RDTES. A questionnaire survey explored students' perceived benefits or drawbacks of the virtual educational system. Students were allocated into Group A (n = 15), B (n = 24) and C (n = 18) based on their pre-learning performance. Differences of assessment results amongst different groups were evaluated by ANOVA and Kruskal-Wallis tests. The pre- and post-learning assessment results in all groups were compared using paired t tests or Wilcoxon signed rank tests. RESULTS The error scores for four assessment items (instrument selection, preparation section, preparation reduction, preparation surface and profile) and total score of outcome assessment after the virtual learning were significantly different with those before the virtual learning (P

To investigate the longitudinal influence of alveolar bone grafting on the oral microbiota of children with cleft lip and palate (CLP). Twenty-eight children with nonsyndromic CLP were recruited and underwent secondary alveolar bone grafting at the first time. Unstimulated saliva and plaque samples were collected from the subjects preoperatively and at 2 days, 1 month, and 3 months postoperatively. The v3–v4 hypervariable regions of the 16S rRNA gene from bacterial DNA were sequenced using the Illumina MiSeq sequencing platform. The alpha diversity of the saliva and plaque microbiota was significantly decreased at 2 days postoperatively and then increased at 1 and 3 months postoperatively. The saliva and plaque microbiota compositions at 2 days postoperatively differed from those at the other time points, and the microbiota compositions at 1 and 3 months postoperatively showed a gradual shift toward the preoperative composition. The saliva, but not plaque, microbiota composition 3 months postoperatively was similar to that preoperatively. The effect of secondary alveolar bone grafting on the plaque microbiota in children with CLP lasted longer than the saliva microbiota. Alveolar bone grafting altered the saliva microbiota in children with CLP within 3 months postoperatively.

Natural adjuvants are novel options to reduce the doses of chemical herbicides. The aim of the current study was to examine the compositions and adjuvant effects of rosin and coconut oil on herbicides using a combination of indoor experiment and field trial. The GC-MS results showed that the main component of rosin was abietic acid (40.02%), and the main components of coconut oil were 2-pentanone, 4-hydroxy-4-methyl- (21.45%) and dodecanoic acid (14.59%). In greenhouse experiment, rosin showed a significant adjuvant effect on nicosulfuron against Digitaria sanguinalis and Amaranthus retroflexus, with the GR50 ratios of 1.47 and 1.69, respectively. The GR50 values of nicosulfuron in the present of coconut oil were 3.99 and 10.13 g a.i./hm2 against D. sanguinalis and A. retroflexus, lower than that of individual application. The adjuvant effect of rosin and coconut oil on mesotrione was also found. In field trial, the fresh weight control efficiency of nicosulfuron (45 g a.i./hm2) and mesotrione (112.5 g a.i./hm2) was significantly improved after the addition of rosin and coconut oil, similar with that of recommended dose. Rosin and coconut oil could reduce the contact angle of nicosulfuron, with the results of 56.68° and 53.90°, respectively, lower than that of individual application. Furthermore, rosin and coconut oil could decrease the surface tension, wetting and penetration time; and increase the spreading diameter and maximum retention. Both rosin and coconut oil have adjuvant effects on herbicides in the lab & field with multiple mechanisms. Thus, they have the potential to be developed into natural adjuvants for herbicide formulation to control weeds.

In order to predict the saturation output power of traveling wave tubes rapidly, analytical expression has been worked out. This theory is verified by comparison with two of large signal theory.

A 0.67THz sheet electron beam traveling-wave tube based upon sine waveguide slow-wave structure is studied. In this paper, the high frequency characteristics and transmission characteristics are calculated by a 3-D high frequency simulation software. The beam-wave interaction is also simulated. From the simulation results, the peak output power is 1.7W ranging from 0.65THz to 0.69THz with synchronous voltage of 17kV, operation current of 10mA and input power of 3.2mW.

As an interesting energy-absorbing structure, auxetic reentrant honeycomb has attracted much attention in recent decades. Furthermore, due to the adjustable design in the configuration of the graded auxetic reentrant honeycomb (GARH), its mechanical performances were of greater designability and controllability. In this manuscript, compressive properties of the positive gradient auxetic honeycomb (PGAH) and negative gradient auxetic honeycomb (NGAH) were both investigated under different compression velocities. Meanwhile, the negative Poisson's ratio effects on the deformation behaviours and crushing stresses of the PGAH and NGAH were systematically studied. It was found that a new shrinkage deformation mechanism existed in the NGAH, which was different from the dynamic compressive properties of the PGAH and homogeneous auxetic honeycomb in the existing studies. Besides, the energy dissipation characteristics of both the PGAH and NGAH were also investigated. The results showed that, when under the medium and high compression velocities, the energy dissipation of the NGAH were 12.1 times and 7.41 times of those in the PGAH, respectively. It could be indicated that the NGAH was an ideal energy-absorbing structure.

As the last step in the process of knowledge graph construction, knowledge graph completion predicts and inferences new factual triples according to the existing knowledge, which is of great significance to the downstream application of the knowledge graph. The knowledge graph completion technology learns representations of entities and relations in the knowledge graph and reconstructs triples factual relations in the representation space to measure their effectiveness, so as to predict and supplement entities and relations. At present, Graph Convolutional Network (GCN) is widely used in entity modeling, which combines the graph structure information to learn the vector representation of entities. However, most algorithms only focus on static knowledge graph completion, ignoring the important role of time in the knowledge graph, and the modeling of entities is not comprehensive enough. In this paper, a knowledge graph completion based on the joint embedding of entities is proposed, which combines structural feature embedding of the graph and dynamic embedding of entities to carry out multi-level learning of entities to improve the effect of entity prediction. Structural feature embedding of the graph takes advantage of the powerful feature aggregation capability of GCN to integrate the knowledge graph as the topological structure and node features of graph data into the representation learning of entities. Dynamic embedding of entities takes advantage of the characteristics that entities will behave in different states at different times and divides the entity features into two parts for learning. One part of the features changes dynamically over time and the other part retains its static properties. In this paper, the probability model ConvTransE is used to construct the model of relations and triples, ConvTransE uses the convolutional neural network to extract the semantic information of the triples and predict the missing elements. We have conducted experiments on public datasets and achieved better results on Hit@K and MRR.

Ninety-seven percent of drug-indication pairs that are tested in clinical trials in oncology never advance to receive U.S. Food and Drug Administration approval. While lack of efficacy and dose-limiting toxicities are the most common causes of trial failure, the reason(s) why so many new drugs encounter these problems is not well understood. Using CRISPR-Cas9 mutagenesis, we investigated a set of cancer drugs and drug targets in various stages of clinical testing. We show that-contrary to previous reports obtained predominantly with RNA interference and small-molecule inhibitors-the proteins ostensibly targeted by these drugs are nonessential for cancer cell proliferation. Moreover, the efficacy of each drug that we tested was unaffected by the loss of its putative target, indicating that these compounds kill cells via off-target effects. By applying a genetic target-deconvolution strategy, we found that the mischaracterized anticancer agent OTS964 is actually a potent inhibitor of the cyclin-dependent kinase CDK11 and that multiple cancer types are addicted to CDK11 expression. We suggest that stringent genetic validation of the mechanism of action of cancer drugs in the preclinical setting may decrease the number of therapies tested in human patients that fail to provide any clinical benefit.

Cyclin‐dependent kinase 7 (CDK7) is a protein kinase that plays a major role in transcription initiation. Yes‐associated protein (YAP) is a main effector of the Hippo/YAP signalling pathway. Here, we investigated the role of CDK7 on YAP regulation in human malignant pleural mesothelioma (MPM). We found that in microarray samples of human MPM tissue, immunohistochemistry staining showed correlation between the expression level of CDK7 and YAP (n = 70, r = .513). In MPM cells, CDK7 expression level was significantly correlated with GTIIC reporter activity (r = .886, P = .019). Inhibition of CDK7 by siRNA decreased the YAP protein level and the GTIIC reporter activity in the MPM cell lines 211H, H290 and H2052. Degradation of the YAP protein was accelerated after CDK7 knockdown in 211H, H290 and H2052 cells. Inhibition of CDK7 reduced tumour cell migration and invasion, as well as tumorsphere formation ability. Restoration of the CDK7 gene rescued the YAP protein level and GTIIC reporter activity after siRNA knockdown in 211H and H2052 cells. Finally, we performed a co‐immunoprecipitation analysis using an anti‐YAP antibody and captured the CDK7 protein in 211H cells. Our results suggest that CDK7 inhibition reduces the YAP protein level by promoting its degradation and suppresses the migration and invasion of MPM cells. Cyclin‐dependent kinase 7 may be a promising therapeutic target for MPM.

The star-shaped reentrant honeycomb produces lateral shrinkage but also rotation under compression. With the consideration of such interesting deformation characteristics, the dynamic deformation evolution of the sandwich beam with star-shaped reentrant honeycomb core (SSRHC) was carried out for the first time. In this experiment, the aluminum foam projectile was used to produce local impulsive loading on the sandwich beam to research failure/deformation modes and deformation evolution of the SSRHC. The experimental results demonstrated the simultaneous shrinking and rotating deformations in the core. Finite element model (FEM) was employed to capture the dynamic mechanical response of panels and SSRHC on account of experimental results. Numerical results illustrated that the face panel moved toward the loading area in the early stage of impact, and local shrinkage or expansion was found within different regions of the star honeycomb cores during the entire compression process. In addition, it was found that the rotational deformation of the star honeycomb cells mainly occurred in the local indentation stage of the sandwich beam.

Knowledge Graph provides an effective scheme for unstructured knowledge on the Internet. but, to a large extent, the lack of information in the knowledge graph restricts the application of the knowledge graph. Therefore, knowledge graph completion has been an attractive research area. In recent years, many researchers apply graph convolutional neural networks to knowledge graph embedding so as to solve this problem, including R-GCN, SACN et al. The current state-of-the-art SACN uses graph convolutional neural as an encoder to make more accurate embeddings of graph nodes, and uses a convolutional network as a decoder, leading a good performance of link prediction task. In this work, we produce a novel graph representation model based on SACN---property graph convolutional network called PGCN. PGCN treats the knowledge graph as a property graph, regarding the initial embedding vector of entities and relations as the property of nodes and edges. What makes the model different is that it introduces the node clustering before convolving the nodes, so that the graph takes into account the importance of neighbors when aggregating the neighbors of nodes. We adopt the probability model Conv-TransE proposed by SACN for the modeling of relation of graph, Conv-TransE takes advantages of ConvE and use probability method which greatly improves the efficiency of the experiment and avoids the construction of the corrupted triplet. We conduct experiments on the standard datasets WN18RR and FB15k-237, and demonstrate that our new model achieves better performance.

In gyrotrons operating in high-order modes, during the startup process, the shadowing of the operating mode by two sidebands may take place. By “shadowing,” we mean the situation when, during the voltage rise, one of the parasitic modes is excited first, and this excitation prevents the excitation of the desired mode. Then, the oscillations of the first parasitic mode, whose frequency is higher than the frequency of the desired operating mode, can be replaced by excitation of the second parasitic mode, whose frequency is lower than the operating one. As a result, the desired mode remains in the “shadow” of these parasitic modes and is never excited. This paper describes such effect in gyrotrons with diode-type electron guns. This paper consists of two parts. First, the problem is studied in a generalized approach, which means that the results are valid to gyrotrons operating at arbitrary voltages and in any modes. By using this approach, it is possible to determine the critical density of the mode spectrum, above which the shadowing occurs. This study is carried out for the cases when the interaction between modes is synchronous and when it is nonsynchronous. Second, this paper contains the analysis of a typical Megawatt-class gyrotron with a diode-type electron gun. It is studied whether the moving of this gyrotron to operating in higher-order modes will lead to the shadowing of the desired mode or other, more complicated, dynamic, and/or stochastic processes will take place.

A novel P-lattice was proposed to meet the engineering needs of combined high specific stiffness, specific strength and superior energy absorption characteristic. The effective elastic properties and plastic strength of the novel P-lattice were adequately investigated through numerical simulation. Results indicated that more superior mechanical properties could be obtained in the proposed novel P-lattice when compared with those of the traditional lattices. Besides, the quasi-static energy absorption of the novel P-lattice was also studied and compared with the competing topologies. A higher energy absorption characteristic was obtained in the proposed novel P-lattice for the reason that three different deformation features, i.e. compression deformation, bending deformation and torsional deformation, existed in the P-lattice under loading.

A high performance continuous-wave (CW) backward wave oscillator (BWO) with planar slow wave structure (SWS) and sheet electron beam in Y-band is presented in this paper. The mode selection is discussed by studying the dispersion curve of SWSs, distributions of the electric field, and particle-in-cell simulation results, showing that the designed BWO operates in the fundamental mode TM11. The planar SWSs are fabricated by using the UV-LIGA technology with the processing error less than 0.003 mm. The electron gun can provide the 2.5 mm × 0.14 mm sheet electron beam with maximum current density of 57 A/cm2 at the CW mode. Experimental results show that the developed BWO can operate in the fundamental mode TM11 and generate the state-of-art output power of 182 mW at the frequency of 0.3426 THz with a large frequency tuning range from 0.318 THz to 0.359 THz.

The design and analysis of a high power and high e-ciency helix traveling-wave tube operating in the Ka-band are presented. First, a double-slotted helix slow-wave structure is proposed and employed in the interaction circuit. Then, negative phase-velocity tapering technology is used to improve electronic e-ciency. From our calculations, when the design voltage and beam current are set to be 18.45kV and 0.2A, respectively, this tube can produce average output power over 800W ranging from 28GHz to 31GHz. The corresponding conversion e-ciency varies from 21.83% to 24.16%, and the maximum output power is 892W at 29GHz.

A novel slotted helix slow-wave structure (SWS) is proposed to develop high power, wide-bandwidth, high reliability millimeter-wave traveling-wave tube (TWT). This structure, which can improve the heat dissipation capability of the helix SWS, evolves from conventional helix SWS with three parallel rows of rectangular slots made in the outside of the helix. In this paper, thermal stress analysis, the electromagnetic characteristics and the beam-wave interaction of this structure are investigated. The conclusions of this paper will be a great help for the design of millimeter-wave traveling-wave tube.

Objective To assess the interdental septal thickness of grafted bone bridges using cone beam computed tomography (CBCT). Patients Of 71 patients with cleft lip and/or palate having undergone alveolar bone grafting for the first time at least 6 months previously, 52 patients with 57 grafted sites rated type I or II based on the Bergland scale using occlusal radiographs were selected. Interventions CBCT was performed for each bone-grafted alveolar cleft within 1 week after the occlusal radiographs were taken. Main Outcome Measures The thickness of the grafted bone bridge was evaluated using CBCT according to the relationship between crest thickness and the root width of cleft-adjacent teeth, and the results were classified into four categories, with scores of 1 to 4 indicating that the thickness of the bony bridge was ≥100%, ≥75%, ≥50%, and Results Of the 34 grafted sites rated type I on the Bergland scale, 15 (44.12%), 10 (29.41%), 4 (11.76%), and 5 (14.71%) clefts were scored 1 to 4 on interdental septal thickness using CBCT, respectively. Of the 23 cases of type II, 3 (13.04%), 9 (39.13%), 1 (3.45%), and 10 (43.48%) clefts were scored 1 to 4, respectively. Conclusions The interdental septal thickness of grafted bone bridges with clinically successful heights based on the Bergland scale (type I or II) using occlusal radiographs varied significantly in the evaluation using CBCT.

Two types of compact, THz radiation sources are developed in An Hui Huadong Photoelectric Technology Institute recently. One is Oroton and the other is backward wave oscillator (BWO). This paper will give the main technical characteristics of these two THz sources.

To propose a new three-dimensional method or grading scale in the evaluation of the secondary alveolar bone grafting, thus modifying the Bergland grading scale.A total of 40 patients (26 male, 14 female) with unilateral cleft lip and palate (UCLP), who underwent secondary alveolar bone grafting at least 3 months ago, were enrolled. Regional cone-beam CT (CBCT) scans were taken to evaluate the height and thickness of the postoperative bone bridges. A new three-dimensional grafting scale was established, including four grades respectively in alveolar height and thickness.According to the new three-dimensional scale in this study, 15 grafted sites were rated grade T-I or T-II in the alveolar thickness among 18 sites of grade H-I in height, and 10 among 15 of grade H-II in height. Therefore, 25 grafted sites were considered as clinical success in the alveolar thickness (grade T-I or T-II) among 33 sites with clinical success in alveolar height (grade H-I and H-II). There were 24% of 33 sites with clinical success in height, which were considered as clinical failure in the alveolar thickness.It is necessary to establish a new three-dimensional method or grading scale for evaluating the secondary alveolar bone grafting. The three-dimensional scale can take comprehensive view of the bone-grafted alveolar clefts and thus modify the Bergland grading scale.

Nowadays, with the continuous miniaturization of electronic packages, the solder balls used to join chips and substrates are downsizing. While the decrease in solder size may have a detrimental effect on the reliability of solder joints. In this paper, Sn-3.0Ag-0.5Cu solder balls were reflow soldered on two kinds of pads (Cu and Ni-P) to give a comparative study of the volume effect. Cu/Sn-3.0Ag-0.5Cu and Ni-P/Sn-3.0Ag-0.5Cu joints displayed volume effect of different forms. In the reaction of Cu/Sn-3.0Ag-0.5Cu, scallop-type Cu6Sn5 grains formed at the interface. The grain size and thickness of Cu6Sn5 IMC together with the Cu consumption were influenced by solder volume. In the reaction of Ni-P/Sn-3.0Ag-0.5Cu, different type of interfacial IMCs formed for solder balls with different sizes. Changes of Cu content in solder balls play an important role in both kinds of reactions.

In this study, we sought to investigate the oral microbiota structure of children with cleft lip and palate (CLP) and explore the pre-operative oral bacterial composition related to the prognosis of alveolar bone grafting. In total, 28 patients (19 boys, 9 girls) with CLP who were scheduled to undergo alveolar bone grafting for the first time were recruited. According to the clinical examination of operative sites at the third month after the operation, the individuals were divided into a non-inflammation group (n = 15) and an inflammation group (n = 13). In all, 56 unstimulated saliva samples were collected before and after the operation. The v3-v4 hypervariable regions of the 16S rRNA gene were sequenced using an Illumina MiSeq sequencing platform. Based on the beta diversity of the operational taxonomic units (OTUs) in the inflammation and non-inflammation samples, the microbial variation in the oral cavity differed significantly between the two groups before and after the operation (P < 0.05). Analysis of the relative abundances of pre-operative OTUs revealed 26 OTUs with a relative abundance higher than 0.01%, reflecting a significant difference of the relative abundance between groups (P < 0.05). According to a principal component analysis of the pre-operative samples, the inflammation-related OTUs included Tannerella sp., Porphyromonas sp., Gemella sp., Moraxella sp., Prevotella nigrescens, and Prevotella intermedia, most of which were enriched in the inflammation group and showed a significant positive correlation. A cross-validated random forest model based on the 26 different OTUs before the operation was able to fit the post-operative status of grafted sites and yielded a good classification result. The sensitivity and specificity of this classified model were 76.9% and 86.7%, respectively. These findings show that the oral microbiota profile before alveolar bone grafting may be related to the risk of post-operative inflammation at grafted sites.

Multiple conductor method is used to calculate the attenuation of the attenuator-coated helix slow-wave structure. The results have high-accuracy for practice and coincide with the experimental data.

A novel winding microstrip meander-line slow-wave structure (SWS) has been proposed to develop low-voltage and high-power millimeter-wave traveling-wave tube. This structure, which interacts with a round electron beam, evolves from a V-shaped microstrip meander-line SWS. The electromagnetic characteristics and beam-wave interaction of this novel structure are calculated in this letter. As is seen from the results, traveling-wave tubes with this novel circuit can provide over 130-W output power ranging from 58 to 63 GHz. In addition, the maximum electronic efficiency may reach 10% at 61 GHz.

A high performance continuous-wave (CW) clinotron with a sheet electron beam at 0.26 THz is presented in this paper. The mode selection is discussed by studying the dispersion curve of the high frequency structure, distribution of the electric field, coupling impedance, and particle-in-cell simulation result, showing that the designed clinotron operates in the fundamental mode TM10. The planar comb gratings are fabricated by using the wire electrical discharge machining technology with the processing error less than 0.005 mm. The electron gun can provide the 2.5 mm × 0.14 mm sheet electron beam with a maximum current density of 57 A/cm2 at the CW mode. Experimental results show that the developed clinotron can operate at the fundamental mode TM10 and generate an output power of 820 mW at a frequency of 0.26 THz with a large frequency tuning range from 0.25 THz to 0.262 THz.

A modified slotted helix slow-wave structure is proposed to develop high-power, wide-bandwidth millimeter TWT. The electromagnetic characteristics are calculated by HFSS. The results show that the modified structure has higher interaction impedance and lower attenuation compared with original slotted helix SWS, which would lead to higher output power in millimeterwave TWT.

A novel helical slow-wave structure is proposed to develop wide-bandwidth, high-gain, high-power millimeter-wave traveling wave tube. This structure evolves from a conventional helical slow-wave structure with three parallel rectangular or other arbitrarily-shaped slots made in the outside of the helix. In this paper, the electromagnetic characteristics and thermal analysis of this structure are obtained using the finite-element-method. From our calculations, the novel and the conventional structure have similar dispersion characteristics, while the novel structure has higher heat dissipation capability than that of conventional one.

Nowadays, with electronic products tending to become shorter, smaller, lighter, and thinner, solder balls used to join chips and substrates are also downsizing. This may have an adverse effect on the reliability of electronic products. The focus of this study is on the effect of solder volume on the interfacial reactions between Sn-3.5Ag, Sn-3.0Ag-0.5Cu lead-free solder balls and electroless nickel electroless palladium immersion gold (ENEPIG) pads on printed circuit board (PCB) after various reflows. The diameters of solder balls were 200, 300, 400 and 500 μm, respectively. In the interfacial reaction between Sn-3.5Ag solder balls and ENEPIG pads, as the diameters of the solder balls changed, obvious changes in Ni 3 Sn 4 intermetallic compound (IMC) morphologies and thickness were not found. We attribute this phenomenon to the limited Ni concentration in the solder. When a small amount of Cu was added into Sn-Ag lead-free solder, changes in type, morphology and growth kinetics of interfacial IMCs occurred. In the case of Sn-3.0Ag-0.5Cu/ENEPIG reaction, volume effect in the form of IMC type transition occurred. Only (Ni, Cu) 3 Sn 4 IMCs with morphologies of needle and chunk shape were observed at the interface of 200 μm solder ball. Interestingly, chunk type (Ni, Cu) 3 Sn 4 IMCs co-existed with the octahedron-type (Cu, Ni) 6 Sn 5 IMCs at the interface between Ni-P layer and 300 μm solder ball. And in the case of 400 μm and 500 μm solder balls, only (Cu, Ni) 6 Sn 5 IMCs in the needle-type shape were formed at the interface. This phenomenon was related to the absolute Cu content in the solder which was changed with solder volume.

The effect of solder volume on the interfacial reactions between Sn-3.0Ag-0.5Cu solder balls and Cu pads during reflow soldering was investigated. Sn-3.0Ag-0.5Cu solder balls of 200, 300, 400, and 500 μm in diameters were employed to react with Cu pads on PCB with the opening diameter of 250 μm The reflow profile was set to reach a peak temperature of 250 °C and maintain a duration of 45s above the liquidus line. The effect of solder volume on the interfacial reaction was obviously demonstrated in this study. Scallop-type Cu6Sn5 grains formed at the interface and grew into a continuous intermetallic compound (IMC) layer as the reaction time prolonged. The average diameter of Cu 6 Sn 5 grains and the thickness of Cu 6 Sn 5 IMC layer for the smaller volume of Sn-3.0Ag-0.5Cu solder ball were significantly larger than those for the larger Sn-3.0Ag-0.5Cu solder ball after the same reflow, but the Cu consumption of the smaller ball was lower than that of the larger one. For the same diameter solder ball, the average diameter of Cu 6 Sn 5 grains, the thickness of Cu 6 Sn 5 DVIC layer and the Cu consumption all increased with increasing reflow times, due to increasing reaction time between liquid solder and Cu pad. The growth of interfacial Cu 6 Sn 5 layer was affected by the dissolution of Cu pad into molten solder; in turn, it also took influence on the dissolution behavior of Cu into molten solder. Compared with our previous study, Sn-3.0Ag-0.5Cu solder ball consumed less Cu than Sn-3.5Ag solder ball for the same volume ball and after the same reflow; the average diameter of Cu 6 Sn 5 grains and the thickness of Cu6Sn5 DVIC layer of Sn-3.0Ag-0.5Cu solder balls were both larger than those of Sn-3.5Ag solder balls after the same reflows and in the same diameters.

This study focused on the effect of solder volume on the interfacial reaction between Sn3.5Ag0.75Cu solder balls and Cu pads on PCB after various reflow soldering times. The diameters of the solder balls were 200, 300, 400 and 500 µm, respectively, and the opening diameter of the Cu pads was 250 µm. The solder volume ratio for the 200, 300, 400 and 500 µm balls was approximately 1:4:8:16. The interfacial intermetallic compound (IMC) was common scallop-type Cu 6 Sn 5 . The thickness of the interfacial Cu 6 Sn 5 IMC layer was obviously thicker for the smaller solder ball after the same reflowing times from 1 to 5. After the first reflow, the thickness of the interfacial Cu 6 Sn 5 IMC layer for the 200 µm solder ball was 4.39 µm compared to that of 3.15 µm for the 500 µm solder ball. The average diameter of the interfacial Cu 6 Sn 5 grains for the smaller solder ball was significantly larger than that for the bigger one after the same reflowing times from 1 to 5. After the first reflow, the average diameter of the interfacial Cu 6 Sn 5 grains for the 200 µm solder ball was 5.23 µm compared to that of 4.22 µm for the 500 µm solder ball. Both the thickness of the Cu 6 Sn 5 IMC layer and the average diameter of the interfacial Cu 6 Sn 5 grains increased with the increasing reflow time. The ratios of the average diameter of Cu 6 Sn 5 grains to the thickness of the interfacial Cu 6 Sn 5 IMC layer for all the four kinds of solder balls varied from 1 to 1.5, which showed a vivid growth of the interfacial Cu 6 Sn 5 grains from the perspective of 3 dimensions. Based on the data from the experiment, the dissolution kinetics of the Cu pad can be simulated.

A novel slotted helix slow-wave structure (SWS) is proposed to develop a high power, wide-bandwidth, and high reliability millimeter-wave traveling-wave tube (TWT). This novel structure, which has higher heat capacity than a conventional helix SWS, evolves from conventional helix SWS with three parallel rows of rectangular slots made in the outside of the helix tape. In this paper, the electromagnetic characteristics and the beam-wave interaction of this novel structure operating in the Ka-band are investigated. From our calculations, when the designed beam voltage and beam current are set to be 18.45 kV and 0.2 A, respectively, this novel circuit can produce over 700-W average output power in a frequency range from 27.5 GHz to 32.5 GHz, and the corresponding conversion efficiency values vary from 19% to 21.3%, and the maximum output power is 787 W at 30 GHz.