Design of a Frequency Selective Rasorber Based on a Band-Patterned Octagonal Ring.

In this study, a dual-polarization and low-profile frequency-selective rasorber (FSR) constructed from a novel band-patterned octagonal ring and dipole slot-type elements is investigated. We show the process of designing from a full octagonal ring to realize a lossy frequency selective surface of our proposed FSR, and it has a passband with low insertion loss between the two absorptive bands. An equivalent circuit for our designed FSR is modeled to explain the introduction of the parallel resonance. Surface current, electric energy, and magnetic energy of the FSR are further investigated to illustrate the working mechanism. Simulated results indicate that S11 < -10 dB bandwidth within 5.2-14.8 GHz, S21 > -3 dB passband within 9.62-11.72 GHz, lower absorptive bandwidth within 5.02-8.80 GHz, and upper absorptive bandwidth within 12.94-14.89 GHz are obtained under normal incidence. Meanwhile, our proposed FSR possesses the properties of dual-polarization and angular stability. To verify the simulated results, a sample with thickness of 0.097 λL is manufactured, and the results are experimentally verified.

Broadband Bi-Directional All-Dielectric Transparent Metamaterial Absorber.

Water-based absorbers have shown great development potential in the past few years. In this paper, an all-dielectric transparent bi-directional water-based broadband metamaterial absorber is designed. The simulation results indicate that absorptance of the absorber is over 90% in 5.7-41.6 GHz, and its fraction bandwidth is 151.8%. The experimental results are greatly consistent with the simulations. The designed absorber has excellent performances of polarization insensitivity, oblique incidence stability and thermal stability. When the absorptance is more than 0.8, the maximum incident angle reaches 40° in TE mode and is over 60° in TM mode. In 0-80 °C, absorptance of the absorber is hardly changed. Because of the optical transparency of the designed absorber, it can be extensively used in stealth window weapons and electromagnetic compatibility equipment.

Low-profile and wide-band RCS-reduction antenna array based on the metasurface polarization converter.

Antenna elements with a low profile and high front-to-back (FB) ratio mean that no additional reflective cavity is required when forming the array, which greatly helps to simplify and lighten the entire array system. In this paper, we enhance the FB ratio of the antenna to 35 dB while maintaining an ultra-low profile of 0.05 λ0 by attaching the broadband polarization conversion metasurfaces (PCMs) as the parasitic patches to the surface of the radiating patch. Meanwhile, the array formed by the proposed antenna is arranged in a checkerboard form, which makes it have a lower radar cross section (RCS) in the X- and Ku- bands. Even with PCMs loaded, the antenna element maintains a small size of 0.58 λ0 × 0.58 λ0, which ensures the proposed array can achieve the ± 45° beam scanning, making it suitable for the phased array. For verification, we propose a low-sidelobe array composed of the proposed antenna elements, which exhibits a low profile, high FB ratio, and broadband RCS reduction through simulation and measurement.

Mutual Coupling Suppression of GPR Antennas by Depositing Wideband Meta-Absorber with Resistive Film.

The direct wave between the transceiver antenna negatively affects the dynamic range and imaging quality of ground penetrating radar (GPR). Suppressing this direct wave is a vital problem in enhancing the performance of the whole GPR system. In this paper, a Minkowski-fractal metamaterial absorber (MMA) with the resistive film is proposed in the GPR transceiver antenna to reduce the mutual coupling. The simulated and measured results indicate that this MMA has an effective wideband absorption in 1.0-8.0 GHz. And the thickness of MMA is only 0.007 λ0 (with respect to 2.0 GHz). This wideband MMA can reduce the mutual coupling of the proposed GPR transceiver antenna by an average of 10 dB. And it also mitigates the time-domain ringing problem of the transmit antenna. Real-world experiments demonstrate that the direct wave from the transmitting antenna can be reduced and the target echo arriving at the receiving antenna can be increased if this MMA is placed in the proposed transceiver antenna. This resistive film-based MMA offers great promise in realizing low-cost, compact, and lightweight GPR antennas, which can also be extended to high-frequency microwave imaging.

Imaging specific cell-surface sialylation using DNA dendrimer-assisted FRET.

Sialylation plays a vital role in multiple different physiologic processes, aberrant sialylation is highly related to disease development. Especially in cancer development, changed states of specific cell-surface sialylation implies rich cancer-related information. Therefore, it is necessary to image specific cell-surface sialylation for better understanding biological functions of sialylation. To meet this purpose, we designed a DNA dendrimer-assisted fluorescence resonance energy transfer (FRET) strategy in this work. By labeling multiple FRET donors and acceptors on the target molecules through metabolic oligosaccharide engineering (MOE) and targeted recognition of aptamer-tethered DNA dendrimer, the FRET was significantly improved. With the DNA dendrimer-assisted FRET strategy, specific imaging of cell-surface sialylation on SMMC-7721 and CEM cells were successfully achieved. The obtained FRET signal intensity was approximately four times higher than the control without the assistance of DNA dendrimer. Moreover, this method is competent to monitor changed states of PTK7-specific sialylation induced by tunicamycin. The proposed imaging strategy may provide a powerful tool to explore the physiological roles of specific cell-surface sialylation and the related mechanism of diseases.

[Using Simulation Teaching to Improve the Communication Skills of Clinicians].

BACKGROUND & PROBLEM: Better communication skills improve the ability of nurses to reduce conflicts with patients. In our medical center, complaints related to poor communication skills during the indwelling of venous catheters number as many as 20-25 cases per month. In our survey, we found that over half (56.25%) of nursing personnel in our medical center self-reported as having "below average" communication skills. Our project team decided to make improvements using interviews and a field survey. After analysis, the team found that reasons for poor communications skills include: the design of educational training courses do not match clinical care needs; the lack of communicative experience while performing venous catheters indwelling; the low confidence of medical personnel; and the lack of communication-skills-related video teaching materials. PURPOSE: Establish suitable teaching project modes that improve the communication skills of nursing personnel in the pediatric department during venous catheters indwelling procedures. METHODS: The improvement methods proposed by the project team consisted of: modifying the pediatric-venous-catheter-indwelling training course, designing teaching courses to enhance communication skills, training seed teachers to teach communication skills, produce videos clips showing scenarios of communication, holding regular case report discussions, and compiling these discussions into an instruction manual. RESULTS: Nursing personnel utilized language or non-language methods to guide pediatric patients and to communicate with their parents during venous catheters indwelling. They understood what patients and their parents were expressing and responded to their questions and concerns logically. The mean score for overall communication skills increased from 27.25 to 35.94 (range: 8 to 40). CONCLUSIONS: Communication teaching modes that combine simulation teaching were established in this project. The communication skills of nurse personnel increased significantly during venous catheters indwelling. We expect to promote a better relationship between nurse personnel, pediatric patients, and their parents by sharing this project.

Evolution of DNA aptamers against esophageal squamous cell carcinoma using cell-SELEX.

Esophageal cancer is the ninth most common cancer and the sixth most common cause of cancer-related death worldwide, and the esophageal squamous cell carcinoma (ESCC) subtype accounts for about 90% of all cases of esophageal cancer globally. Currently, ESCC is usually diagnosed in late stages, and targeted therapy is lacking. Therefore, the development of ESCC-specific recognition molecules for an early detection and targeted treatment of ESCC is urgently needed. Aptamers are an excellent molecular recognition tool with unique advantages. In this manuscript, three aptamers (S2, S3, and S8) specific to ESCC cells were successfully screened via cell-SELEX. The experimental results displayed the high affinities of the three aptamers for target KYSE150 cells with dissociation constants in the nanomolar range. The specificity evaluation showed that S2 only bound target KYSE150 cells, but S3 and S8 were capable of targeting a series of ESCC cells. Moreover, several truncated aptamers were generated through sequence optimization. In particular, an ultrashort aptamer S3-2-3 with only 18 bases was successfully obtained; after labeling with Cy5 dyes, it was feasible for the specific imaging of ESCC tissues. Furthermore, the target types of the selected aptamers were preliminarily identified as membrane proteins, and target proteins could be captured by S3-2-3, which may be useful for biomarker discovery. Therefore, the selected aptamers hold great potential for clinical diagnosis, biomarker discovery, and the targeted therapy of ESCC.

Highly sensitive and specific detection of tumor cells based on a split aptamer-triggered dual hybridization chain reaction.

Highly sensitive and specific detection of rare tumor cells is urgently needed for early tumor diagnosis. Herein, a split aptamer-based dual hybridization chain reaction (dual-HCR) strategy with flow cytometry analysis was developed to meet this purpose. With the split aptamer pair as the recognition unit and HCR as the signal amplification technique, this strategy achieved an improved detection limit as low as 20 cells in 200 µL binding buffer. Meanwhile, this method was highly specific with distinct recognition of the target cells from the control cell and mixed cell samples. Furthermore, we succeeded in the specific detection of the target cells in 50% human serum, demonstrating that this method has great potential in clinical applications. In theory, this strategy can be used to detect different target cells by using different split aptamers. Therefore, this general, sensitive and specific tumor cell detection method may be helpful for early clinical diagnosis and cancer research.

DNA Generated Electric Current Biosensor.

In addition to its primary function as a genetic material, deoxyribonucleic acid (DNA) is also a potential biologic energy source for molecular electronics. For the first time, we demonstrate that DNA can generate a redox electric current. As an example of this new functionality, DNA generated redox current was used for electrochemical detection of human epidermal growth factor receptor 2 (HER2), a clinically important breast cancer biomarker. To induce redox current, the phosphate of the single stranded DNA aptamer backbone was reacted with molybdate to form redox molybdophosphate precipitate and generate an electrochemical current of ∼16.8 µA/µM cm2. This detection of HER2 was performed using a sandwich detection assay. A HER2 specific peptide was immobilized onto a gold electrode surface for capturing HER2 in buffer and serum. The HER2 specific aptamer was used as both ligand to bind the captured HER2 and to generate a redox current signal. When tested for HER2 detection, the electrochemical current generated by the aptasensor was proportional to HER2 concentration in the range of 0.01 to 5 ng/mL, with a current generated in the range of ∼6.37 to 31.8 µA/cm2 in both buffer and serum. This detection level is within the clinically relevant range of HER2 concentrations. This method of electrochemical signal amplification greatly simplifies the signal transduction of aptasensors, broadening their use for HER2 analysis. This novel approach of using the same aptamer as biosensor ligand and as transducer can be universally extended to other aptasensors for a wide array of biodetection applications. Moreover, electric currents generated by DNA or other nucleic acids can be used in molecular electronics or implanted devices for both power generation and measurement of output.

A single electrochemical biosensor for detecting the activity and inhibition of both protein kinase and alkaline phosphatase based on phosphate ions induced deposition of redox precipitates.

Protein kinase (PKA) and alkaline phosphatase (ALP) are clinically relevant enzymes for a number of diseases. In this work, we developed a new simple electrochemical biosensor for the detection of the activity and inhibition of both PKA and ALP. One common feature of the PKA and ALP catalyzing process is that PKA can hydrolysis adenosine-5'-triphosphate (ATP) and ALP can hydrolysis pyrophosphate, both reactions produce phosphate ions, and the amount of phosphate ion produced is proportional to enzyme activity. Our assay is based on the principle that phosphate ions react with molybdate to form redox molybdophosphate precipitates on the electrode surface, thus generating electrochemical current. The detection limit for PKA and ALP were much lower than existing assays. The biosensor has good specificity and was used to measure drug-stimulated PKA from lysates of HeLa cells. We also evaluated the use of the biosensor as a screening tool for enzyme inhibitors. To the best of our knowledge, this is the first report of a biosensor capable of detecting the activity of both PKA and ALP. This tool has the potential to simplify PKA and ALP clinical measurement, thereby improving diagnostics of relevant diseases. It also may serve as the basis for a simple screening method for new enzyme inhibitors for disease treatment.

[Impact of different traffic crossroads exhaust pollution on immune function of the school-age children in Taiyuan City].

OBJECTIVE: to discuss the impact of different traffic crossroad exhaust pollution on the immune function of school-age children. METHODS: A school in the heavy traffic polluted area and B school in the less traffic polluted area were selected. Total 142 students from five to six grades in both areas were sampled. The level of peripheral blood cells (WBC, lymphocytes, neutral cells, red blood cells, platelets) and the T lymphocyte subpopulations (the percentages of CD3+, CD4+, CD8+ and the ratio of CD4+/CD8+), saliva lysozyme contents and immunoglobulin content were determined. RESULTS: Except for neutral cells, the peripheral blood cells level (WBC, lymphocytes, red blood cells, platelets) of children in the A school were higher than those in the B school. The contents of saliva lysozyme, immunoglobulin (IgG), T lymphocyte subpopulations (the percentages of CD3+, CD4+ and the ratio of CD4+/CD8+) in the A school were lower than those in the B school (P < 0.05). CONCLUSION: Exhaust pollution of different traffic crossroads could inhibit nonspecific immunity and cell immunity, and impact the level of blood cells and humoral immunity.