A New Linear Printed Vivaldi Antenna Array with Low Side Lobe Level and High Gain for the Band 3.5 GHz

This paper proposes a new design of low sidelobe level (SLL) and high gain linear printed Vivaldi antenna array. The array composes of two parts, which are a linear Vivaldi antenna array and a back reflector. The array consists of 10 single Vivaldi antennas and a series-fed network, those are based on Roger RO4003C substrate (ε = 3.55) with the dimension of 140 x 450 x 1.524 mm3. A new Bat algorithm with the amplitude-only control technique has been applied to optimize the output coefficients of the series-fed network for gaining a low SLL. The simulation results indicate that the proposed antenna provides a low SLL of -29.2 dB in E-plane with a high gain of 16.5 dBi at the frequency of 3500 MHz. A prototype of the proposed antenna array has been fabricated. The measured data has a good agreement with the simulated data

Detection of a Sudan dye at low concentrations by surface-enhanced Raman spectroscopy using silver nanoparticles

Sudan dyes are red colorants banned from use for food due to their toxic properties. However, because of the cheapness, they are sometimes adulterated into food illegally. Currently surface-enhanced Raman spectroscopy (SERS) is emerging as a good method to detect residues (including trace amounts) of Sudan dyes in food. In this report we present the SERS detection of Sudan I (a type of Sudan dyes) to concentrations as low as 1 ppb, using a very simple SERS substrate, which is made from silver nanoparticles chemically deposited on silicon surface

Deep Learning-Aided Multicarrier Systems

This paper proposes a deep learning (DL)-aided multicarrier (MC) system operating on fading channels, where both modulation and demodulation blocks are modeled by deep neural networks (DNNs), regarded as the encoder and decoder of an autoencoder (AE) architecture, respectively. Unlike existing AE-based systems, which incorporate domain knowledge of a channel equalizer to suppress the effects of wireless channels, the proposed scheme, termed as MC-AE, directly feeds the decoder with the channel state information and received signal, which are then processed in a fully data-driven manner. This new approach enables MC-AE to jointly learn the encoder and decoder to optimize the diversity and coding gains over fading channels. In particular, the block error rate of MC-AE is analyzed to show its higher performance gains than existing hand-crafted baselines, such as various recent index modulation-based MC schemes. We then extend MC-AE to multiuser scenarios, wherein the resultant system is termed as MU-MC-AE. Accordingly, two novel DNN structures for uplink and downlink MU-MC-AE transmissions are proposed, along with a novel cost function that ensures a fast training convergence and fairness among users. Finally, simulation results are provided to show the superiority of the proposed DL-based schemes over current baselines, in terms of both the error performance and receiver complexity

CONTRIBUTION ESTIMATE OF PAHS TOXIC COMPOUNDS IN AIR ENVIRONMENT AT MAJOR TRAFFIC JOINTS OF HANOI, VIETNAM

Joint Research on Environmental Science and Technology for the Eart

Synthesis of Flower-like Silver Nanostructures on Silicon and Their Application in Surface-enhanced Raman Scattering

To enhance the intensity of surface-enhanced Raman scattering (SERS), production of metal nanostructures with sharp points, lying side by side at the nanometer level plays an extremely important role. In this paper, we report on a manufacturing process in which the silver nanoparticles with the flower-like shape have been fabricated. Such silver nanoparticles have been fabricated by chemical deposition of silver particles on silicon wafers, using a solution of hydrofluoric acid (HF), silver nitrate (AgNO3) and ascorbic acid (AsA) in water, at room temperature. During the manufacturing we found that only when the concentrations of AgNO3 and AsA are appropriate, the flower-like silver nanoparticles will form. Note that while other authors mainly made flower-like silver nanoparticles in the form of suspensions, we have created flower-like silver nanoparticles with cabbage-shape on a silicon surface. The ensembles of flower-like silver nanoparticles above were used as SERS substrates to detect crystal violet (CV) in low concentrations and good results were obtained

TextANIMAR: Text-based 3D Animal Fine-Grained Retrieval

3D object retrieval is an important yet challenging task, which has drawn more and more attention in recent years. While existing approaches have made strides in addressing this issue, they are often limited to restricted settings such as image and sketch queries, which are often unfriendly interactions for common users. In order to overcome these limitations, this paper presents a novel SHREC challenge track focusing on text-based fine-grained retrieval of 3D animal models. Unlike previous SHREC challenge tracks, the proposed task is considerably more challenging, requiring participants to develop innovative approaches to tackle the problem of text-based retrieval. Despite the increased difficulty, we believe that this task has the potential to drive useful applications in practice and facilitate more intuitive interactions with 3D objects. Five groups participated in our competition, submitting a total of 114 runs. While the results obtained in our competition are satisfactory, we note that the challenges presented by this task are far from being fully solved. As such, we provide insights into potential areas for future research and improvements. We believe that we can help push the boundaries of 3D object retrieval and facilitate more user-friendly interactions via vision-language technologies.Comment: arXiv admin note: text overlap with arXiv:2304.0573

Smoke-free environment policy in Vietnam: What did people see and how did they react when they visited various public places?

Introduction: Since Vietnam has signed WHO framework on tobacco control (FCTC) in 2003 and has issued tobacco control law in 2013, there has been little research concerning about what impacts smoke-free regulations have had on public compliance. The objective of this study was to assess public exposure to secondhand smoke and reaction toward smoke-free policy regulations in Vietnam and the associated factor. Methods: Using the design of GATS (Global Adult Tobacco Survey), a nationally representative sample of 8,996 adults were approached for data collection. Logistic regression was used to examine the associated factor.Results: The study revealed that the prevalence of respondents exposed to secondhand smoke was much higher in bars/café/tea shops (90.07%) and restaurants (81.81%) than in any other public places, universities (36.70%), government buildings (31.12%), public transport (20.04%), healthcare facilities (17.85%) and schools (15.84%). 13.23% of respondents saw smokers violate smoke-free regulations. Among those who saw them violate smoke-free regulations, just one-third cautioned them to stop smoking. Strikingly, a higher rate of cautioning smokers to stop smoking was observed among the older, married, and better educated respondents. Respondents who were married, better educated and in lower economic status were more likely to remind smokers to stop smoking.Conclusions: The study has called for strengthening two of the six MPOWER (Monitor, Protect, Offer, Warn, Enforce and Raise) components of the tobacco free initiative introduced by WHO, Monitoring tobacco use and prevention policies and Protecting people from tobacco smoke

Synthesis of Silica-Coated Magnetic Nanoparticles and Application in the Detection of Pathogenic Viruses

Magnetic Fe3O4 nanoparticles were prepared by coprecipitation and then coated with silica. These Fe3O4/SiO2 nanoparticles consisted of a 10–15 nm magnetic core and a silica shell of 2–5 nm thickness. The superparamagnetic property of the Fe3O4/SiO2 particles with the magnetization of 42.5 emu/g was confirmed by vibrating sample magnetometer (VSM). We further optimized buffers with these Fe3O4/SiO2 nanoparticles to isolate genomic DNA of hepatitis virus type B (HBV) and of Epstein-Barr virus (EBV) for detection of the viruses based on polymerase chain reaction (PCR) amplification of a 434 bp fragment of S gene specific for HBV and 250 bp fragment of nuclear antigen encoding gene specific for EBV. The purification efficiency of DNA of both HBV and EBV using obtained Fe3O4/SiO2 nanoparticles was superior to that obtained with commercialized Fe3O4/SiO2 microparticles, as indicated by (i) brighter PCR-amplified bands for both HBV and EBV and (ii) higher sensitivity in PCR-based detection of EBV load (copies/mL). The time required for DNA isolation using Fe3O4/SiO2 nanoparticles was significantly reduced as the particles were attracted to magnets more quickly (15–20 s) than the commercialized microparticles (2-3 min)

A Multi-Center Randomised Controlled Trial of Gatifloxacin versus Azithromycin for the Treatment of Uncomplicated Typhoid Fever in Children and Adults in Vietnam

BACKGROUND: Drug resistant typhoid fever is a major clinical problem globally. Many of the first line antibiotics, including the older generation fluoroquinolones, ciprofloxacin and ofloxacin, are failing. OBJECTIVES: We performed a randomised controlled trial to compare the efficacy and safety of gatifloxacin (10 mg/kg/day) versus azithromycin (20 mg/kg/day) as a once daily oral dose for 7 days for the treatment of uncomplicated typhoid fever in children and adults in Vietnam. METHODS: An open-label multi-centre randomised trial with pre-specified per protocol analysis and intention to treat analysis was conducted. The primary outcome was fever clearance time, the secondary outcome was overall treatment failure (clinical or microbiological failure, development of typhoid fever-related complications, relapse or faecal carriage of S. typhi). PRINCIPAL FINDINGS: We enrolled 358 children and adults with suspected typhoid fever. There was no death in the study. 287 patients had blood culture confirmed typhoid fever, 145 patients received gatifloxacin and 142 patients received azithromycin. The median FCT was 106 hours in both treatment arms (95% Confidence Interval [CI]; 94-118 hours for gatifloxacin versus 88-112 hours for azithromycin), (logrank test p = 0.984, HR [95% CI] = 1.0 [0.80-1.26]). Overall treatment failure occurred in 13/145 (9%) patients in the gatifloxacin group and 13/140 (9.3%) patients in the azithromycin group, (logrank test p = 0.854, HR [95% CI] = 0.93 [0.43-2.0]). 96% (254/263) of the Salmonella enterica serovar Typhi isolates were resistant to nalidixic acid and 58% (153/263) were multidrug resistant. CONCLUSIONS: Both antibiotics showed an excellent efficacy and safety profile. Both gatifloxacin and azithromycin can be recommended for the treatment of typhoid fever particularly in regions with high rates of multidrug and nalidixic acid resistance. The cost of a 7-day treatment course of gatifloxacin is approximately one third of the cost of azithromycin in Vietnam. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN67946944

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke