Search Results (23)

In this paper, the uplink spectral efficiency performance of a massive MIMO system based on full-duplex relay communication is investigated in Rician fading channels. The relay station is equipped with a large number of antennas, while multiple source and destination nodes are located at both ends of the transceiver. Each source and destination node is equipped with a single antenna. The relay station adopts Maximum Ratio Combining/Maximum Ratio Transmission (MRC/MRT) and Equal Gain Combining/Equal Gain Transmission (EGC/EGT) schemes to perform linear preprocessing on the received signals. Approximate expressions for uplink spectral efficiency under both MRC/MRT and EGC/EGT schemes are derived, and the effects of antenna number, signal-to-noise ratio (SNR), and loop interference on spectral efficiency are analyzed. In addition, the impact of full-duplex and half-duplex modes on system performance is compared, and a hybrid relay scheme is proposed to maximize the total spectral efficiency by dynamically switching between full-duplex and half-duplex modes based on varying levels of loop interference. Finally, a novel power allocation scheme is proposed to maximize energy efficiency under given total spectral efficiency and peak power constraints at both the relay and source nodes. The results show that the impact of loop interference can be eliminated by using a massive receive antenna array, leading to the disappearance of inter-pair interference and noise. Under these conditions, the spectral efficiency of the system can be improved up to $2N$ times, while the transmission power of the user and relay nodes can be reduced to $1/N_{\mathrm{rx}}$ and $1/N_{\mathrm{tx}}$, respectively. Full article

Strawberry crown and root rot diseases are caused by soil-borne pathogens including Macrophomina phaseolina (Mp) and Verticillium dahliae (Vd). The symptoms caused by these pathogens are very similar and difficult to distinguish, and traditional culture-based detection methods are laborious, time-consuming, and slow in providing results. In this work, we developed a duplex PCR-NALFIA assay using two pairs of species-specific primers labeled at the 5′ end with different molecules for the simultaneous identification of Mp and Vd. For the NALFIA assay, a lateral flow device (LFD) for the detection of two analytes was used. The method was developed by single and duplex PCR (Mp, Vd, Mp + Vd) using increasingly complex biological systems: (i) DNA from pure cultures of the pathogens; (ii) DNA from artificially inoculated cut melon stems; and (iii) DNA from artificially inoculated strawberry plants cv. Aromas. The duplex PCR protocol was effective in detecting the two pathogens within melon tissues and provided good results with strawberry crown tissues only when the DNA samples were purified by removing the PCR inhibitors. The amplicons were used for both agarose gel electrophoresis (AGE) and NALFIA assays and demonstrated the greater sensitivity of the NALFIA assay (10 pg) for simultaneous detection of the two pathogens. Full article

Fluorescent biosensor, which has the characteristics of high sensitivity, specificity, and low cost, can be directly detected in physiological fluids such as blood and serum. Therefore, the development of fluorescence sensor platforms for miRNA detection has a positive effect on the prevention and treatment of various diseases. In this paper, miR-34a was selected as a biological indicator of Alzheimer’s disease (AD). We designed a circular single-stranded DNA (CSSD) biosensor, which uses two unmodified single-stranded DNA (ssDNA) with complementary ends, DNAa and DNAb, to form CSSD by DNA sequence pairing to improve thermal stability and achieve signal amplification. At the same time, CSSD can react with miR-34a, and then the DNA of the DNA–RNA chain is hydrolyzed by duplex-specific nuclease (DSN enzyme). Finally, miR-34a is released to partake in the subsequent step, thus realizing cycle amplification. By evaluating the change in fluorescence signal under the optimized conditions, we discovered that this approach exhibits impressive sensitivity, with a detection threshold reaching as low as 0.36 nM. This surpasses the performance of numerous preceding miRNA detection biosensors. Furthermore, the system displays excellent detection capabilities even in intricate settings like serum, showcasing a strong ability to differentiate and choose effectively. In summary, this is a signal-off fluorescent biosensor, which realizes the purpose of double amplification of biosensor signal by using CSSD and enzyme assistance so that it can be used as a valuable tool for early diagnosis of diseases. Full article

The efficient preparation of single-stranded DNA (ssDNA) rings, as a macromolecular construction approach with topological features, has aroused much interest due to the ssDNA rings’ numerous applications in biotechnology and DNA nanotechnology. However, an extra splint is essential for enzymatic circularization, and by-products of multimers are usually present at high concentrations. Here, we proposed a simple and robust strategy using permuted precursor (linear ssDNA) for circularization by forming an intramolecular dynamic nick using a part of the linear ssDNA substrate itself as the template. After the simulation of the secondary structure for desired circular ssDNA, the linear ssDNA substrate is designed to have its ends on the duplex part (≥5 bp). By using this permuted substrate with 5′-phosphate, the splint-free circularization is simply carried out by T4 DNA ligase. Very interestingly, formation of only several base pairs (2–4) flanking the nick is enough for ligation, although they form only instantaneously under ligation conditions. More significantly, the 5-bp intramolecular duplex part commonly exists in genomes or functional DNA, demonstrating the high generality of our approach. Our findings are also helpful for understanding the mechanism of enzymatic DNA ligation from the viewpoint of substrate binding. Full article

Visible light communication has the advantages of large bandwidth, high security, and no RF interference, among which LED light sources are an important light source for indoor visible light communication. The use of LED as a light source for visible full-duplex communication is both to meet the lighting requirements and to ensure high-speed transmission of information. The uplink using the “cat’s eye” reverse modulation system can greatly reduce the system complexity of the reverse reflector. In order to analyze the factors affecting the optical power at the receiving end of the uplink of the indoor single light source visible light communication, this paper establishes the indoor visible light full-duplex communication system model and deduces the calculation method of the effective incidence angle of the uplink transmission light and the movable range of the reverse reflection end according to the model. The results show that when the link distance of the BK7 lens is 3 m, the lens aperture is increased from 100 mm to 150 mm, the lens focal length is increased from 100 mm to 150 mm, the travel distance of the reverse reflector is increased by 60%, and the effective range of the incidence angle is increased by about twice. In the absence of link loss, each 1 m increase in link distance increases the maximum travel distance of the reverse reflector by 0.8 m. Increasing the lens aperture, decreasing the focal length, and increasing the link distance can improve the movable range of the reverse reflector, and the effective incidence angle changes more gently with the position of the reverse reflector. Full article

In this work, a cognitive relay network (CRN) with interference constraint from the primary user (PU) with a mobile end user is studied. The proposed system model employs a half-duplex transmission between a single PU and a single secondary user (SU). In addition, an amplify and forward (AF) relaying technique is employed between the SU source and SU destination. In this context, the mobile end user (SU destination) is assumed to move at high vehicular speeds, whereas other nodes (SU Source, SU relays and PU) are assumed to be stationary. The proposed scheme dynamically determines the best relay for transmission based on the highest signal-to-noise (SNR) ratio by deploying selection combiner at the SU destination, thereby achieving diversity. All channels connected with the stationary nodes are modelled using Rayleigh distribution, whereas all other links connected with the mobile end user are modelled using Nakagami-m fading distribution ($m<1$). The outage probabilities (OPs) are obtained considering several scenarios and Monte Carlo simulation is used to verify the numerical results. The obtained results show that a variety of factors, including the number of SU relays, the severity of the fading channels, the position of the PU, the fading model, and the mobile end user speed, might influence the CRN’s performance. Full article

Understanding the patterns of noncovalent adsorption of double-stranded nucleic acids (dsDNA) on gold nanoparticles (GNPs) was the aim of this study. It was found that the high-affinity motifs in DNA can and do act as an “anchor” for the fixation of the whole molecule on the GNP (up to 98 ± 2 single-stranded (ss)DNA molecules per particle with diameter of 13 ± 2 nm). At the same time, the involvement of an “anchor” in the intramolecular DNA interaction can negatively affect the efficiency of the formation of ss(ds)DNA–GNP structures. It has been shown that the interaction of GNP with DNA duplexes is accompanied by their dissociation and competitive adsorption of ssDNAs on GNP, wherein the crucial factor of DNA adsorption efficiency is the intrinsic affinity of ssDNA to GNP. We propose a detailed scheme for the interaction of dsDNA with GNPs, which should be taken into account in studies of this type. Researchers focused on this field should accept the complicated nature of such objects and take into account the many competing processes, including the processes of adsorption and desorption of DNA on gold as well as the formation of secondary structures by individual DNA strands. Full article

Homologous recombination repairs potentially lethal DNA lesions such as double-strand DNA breaks (DSBs) and single-strand DNA gaps (SSGs). In Escherichia coli, DSB repair is initiated by the RecBCD enzyme that resects double-strand DNA ends and loads RecA recombinase to the emerging single-strand (ss) DNA tails. SSG repair is mediated by the RecFOR protein complex that loads RecA onto the ssDNA segment of gaped duplex. In both repair pathways, RecA catalyses reactions of homologous DNA pairing and strand exchange, while RuvABC complex and RecG helicase process recombination intermediates. In this work, we have characterised cytological changes in various recombination mutants of E. coli after three different DNA-damaging treatments: (i) expression of I-SceI endonuclease, (ii) γ-irradiation, and (iii) UV-irradiation. All three treatments caused severe chromosome segregation defects and DNA-less cell formation in the ruvABC, recG, and ruvABC recG mutants. After I-SceI expression and γ-irradiation, this phenotype was efficiently suppressed by the recB mutation, indicating that cytological defects result mostly from incomplete DSB repair. In UV-irradiated cells, the recB mutation abolished cytological defects of recG mutants and also partially suppressed the cytological defects of ruvABC recG mutants. However, neither recB nor recO mutation alone could suppress the cytological defects of UV-irradiated ruvABC mutants. The suppression was achieved only by simultaneous inactivation of the recB and recO genes. Cell survival and microscopic analysis suggest that chromosome segregation defects in UV-irradiated ruvABC mutants largely result from defective processing of stalled replication forks. The results of this study show that chromosome morphology is a valuable marker in genetic analyses of recombinational repair in E. coli. Full article

In this paper, the mechanical properties, microhardness and metallographic structure of 2205 duplex stainless steel by cold metal transfer (CMT) wire and arc additive manufacturing process are studied. The results show that the ultimate tensile strength, yield strength and elongation at break of reciprocating additive along building direction (BD) are 856.73 MPa, 710.5 MPa and 42.35%, respectively. In addition, the same direction motion (SDM) and reciprocating motion (RM) is selected as parameter variables in the experiment, and the finite element model is established by ABAQUS software, and the temperature and residual stress field of the additive forming at different paths are tested and simulated. Firstly, the accuracy of the selected finite element model was verified by comparing the experimental results from the simulation results to the macroscopic morphology of the cross-section of the single-pass additive specimen. The numerical simulation results show that due to the difference of the additive scanning paths, the distribution of the temperature field has a large difference, and with the increase of the deposited layer, the heat accumulation of the SDM additive is larger than that of the RM, so that the end collapses of the SDM additive will occur in the actual additive specimen. By simulating and comparing the equivalent stress distribution of different paths, the equivalent stress distribution of SDM and RM is approximately the same in the vertical direction, and the minimum of equivalent stress appears at the bottom of the deposition layers, about 116.5 MPa, and the maximum of equivalent stress appears at 8 mm from the top, about 348 MPa. Full article

Objective: To report early and mid-term outcomes of the arterialization of the deep venous system in no-option critical limb-threatening ischemia (CLTI) using duplex ultrasound and angiographic evaluation to improve limb perfusion. Methods: A single-center prospective study of patients with no-option CLTI treated with hybrid surgical arterialization of the deep venous circulation and staged endovascular embolization of the venous collateral. Embolization was performed using a controlled-release spiral, within two weeks after bypass surgery. Patients were assessed for clinical status, wound healing, median transcutaneous partial pressure of O₂ (TcPO₂), and post-operative duplex ultrasound evaluating peak systolic velocity (PSV), end diastolic velocity (EDV), and resistance index (RI) to assess foot perfusion and bypass features. Primary endpoint analysis was primary technical success, limb salvage, patency rates, and clinical improvement. Secondary endpoints were 30-day and long-term mortality, major cardiovascular events (MACE), including myocardial infarction or stroke, and serious adverse events (SAE). Results: Five patients with no-option CLTI were treated at our center using the hybrid deep vein arterialization technique. Clinical stage was grade 3 in one patient and grade 4 in the remaining four. Mean age was 65.8 years (range 49–76 years), and two patients were affected by Buerger’s disease. Primary technical success was achieved in all patients, and all the bypasses were patent at the angiographic examination. At 30-day and at average follow-up of 9.8 months (range 2–24 months), mortality, major cardiovascular events (MACE), and serious adverse events (SAE) were not reported, with a primary patency and limb salvage rates of 100%. Three patients required minor amputation. Clinical improvement was demonstrated in all patients with granulation, resolution of rest pain, or both. Median TcPO₂ values rose from 10 mm Hg (range 4–25) before the procedure to 35 (range 31–57) after surgery, and to 59 mm Hg (range 50–76) after the staged endovascular procedure. Conclusions: In our initial experience, the arterialization of the deep venous circulation, with subsequent selective embolization of the venous escape routes from the foot, seems a feasible and effective solution for limb salvage in patients with no-option CLTI and those in the advanced wound, ischemia, and foot infection (WIfI) clinical stage. Full article

The interplay between the mechanical properties of double-stranded and single-stranded DNA is a phenomenon that contributes to various genetic processes in which both types of DNA structures coexist. Highly stiff DNA duplexes can stretch single-stranded DNA (ssDNA) segments between the duplexes in a topologically constrained domain. To evaluate such an effect, we designed short DNA nanorings in which a DNA duplex with 160 bp is connected by a 30 nt single-stranded DNA segment. The stretching effect of the duplex in such a DNA construct can lead to the elongation of ssDNA, and this effect can be measured directly using atomic force microscopy (AFM) imaging. In AFM images of the nanorings, the ssDNA regions were identified, and the end-to-end distance of ssDNA was measured. The data revealed a stretching of the ssDNA segment with a median end-to-end distance which was 16% higher compared with the control. These data are in line with theoretical estimates of the stretching of ssDNA by the rigid DNA duplex holding the ssDNA segment within the nanoring construct. Time-lapse AFM data revealed substantial dynamics of the DNA rings, allowing for the formation of transient crossed nanoring formations with end-to-end distances as much as 30% larger than those of the longer-lived morphologies. The generated nanorings are an attractive model system for investigation of the effects of mechanical stretching of ssDNA on its biochemical properties, including interaction with proteins. Full article

Fiber-optic distributed temperature sensing (DTS) has been widely used since the end of the 20th century, with various industrial, Earth sciences, and research applications. To obtain precise thermal measurements, it is important to extend the currently available DTS calibration methods, considering that environmental and deployment factors can strongly impact these measurements. In this work, a laboratory experiment was performed to assess a currently available duplexed single-ended DTS calibration algorithm and to extend it in case no temperature information is available at the end of the cables, which is extremely important in geothermal applications. The extended calibration algorithms were tested in different boreholes located in the Atacama Desert and in the Central Andes Mountains to estimate the geothermal gradient in these regions. The best algorithm found achieved a root mean square error of 0.31 ± 0.07 °C at the far end of a ~1.1-km cable, which is much smaller than that obtained using the manufacturer algorithm (2.17 ± 0.35 °C). Moreover, temperature differences between single- and double-ended measurements were less than 0.3 °C at the far end of the cable, which results in differences of ~0.5 °C km⁻¹ when determining the geothermal gradient. This improvement in the geothermal gradient is relevant, as it can reduce the drilling depth by at least 700 m in the study area. Future work should investigate new extensions of the algorithms for other DTS configurations and determining the flow rate of the Central Andes Mountains artesian well using the geothermal profile provided by the DTS measurements and the available data of the borehole Full article

DNA from formalin-fixed paraffin-embedded (FFPE) tissues, which are frequently utilized in cancer research, is significantly affected by chemical degradation. It was suggested that approaches that are based on duplex sequencing can significantly improve the accuracy of mutation detection in FFPE-derived DNA. However, the original duplex sequencing method cannot be utilized for the analysis of formalin-fixed paraffin-embedded (FFPE) tissues, as FFPE DNA contains an excessive number of damaged bases, and these lesions are converted to false double-strand nucleotide substitutions during polymerase-driven DNA end repair process. To resolve this drawback, we replaced DNA polymerase by a single strand-specific nuclease P1. Nuclease P1 was shown to efficiently remove RNA from DNA preparations, to fragment the FFPE-derived DNA and to remove 5′/3′-overhangs. To assess the performance of duplex sequencing-based methods in FFPE-derived DNA, we constructed the Bottleneck Sequencing System (BotSeqS) libraries from five colorectal carcinomas (CRCs) using either DNA polymerase or nuclease P1. As expected, the number of identified mutations was approximately an order of magnitude higher in libraries prepared with DNA polymerase vs. nuclease P1 (626 ± 167/Mb vs. 75 ± 37/Mb, paired t-test p-value 0.003). Furthermore, the use of nuclease P1 but not polymerase-driven DNA end repair allowed a reliable discrimination between CRC tumors with and without hypermutator phenotypes. The utility of newly developed modification was validated in the collection of 17 CRCs and 5 adjacent normal tissues. Nuclease P1 can be recommended for the use in duplex sequencing library preparation from FFPE-derived DNA. Full article

In-band full duplex offers a new approach of meeting the ever-increasing data rate demands by operating the transmitter and receiver at the same frequency at the same time, potentially doubling the spectral efficiency. However, self-interference is the fundamental bottleneck of such systems. In contrast to non-planar or sub 6 GHz microstrip designs reported so-far, this paper presents an all SIW based antenna system for in-band full duplex systems. The proposed design integrates a dual linear polarized three port differential antenna, three port SIW common-mode power combiner and a 180°phase shifter at 28 GHz. Operating the antenna in TE201 mode provides inherent isolation between the differential receive and single-ended transmit port. The residual coupling is further reduced through use of TE101 based power combiner and a 180°phase shifter. Implemented on a 0.508 mm thick RT Duroid 5880 substrate, the antenna occupies a foot-print of 48 × 80 mm². Demonstrating a measured gain of 6.95 dBi and 3.42 dBi for Tx and Rx mode of operation, respectively, the proposed design offers a self-interference cancellation (SiC) of better than 36 dB over a 177 MHz bandwidth. Full article

The line-of-sight (LoS) channel is one of the requirements for efficient data transmission in visible-light communications (VLC), but this cannot always be guaranteed in indoor applications for a variety of reasons, such as moving objects and the layout of rooms. The relay-assisted VLC system is one of the techniques that can be used to address this issue and ensures seamless connectivity. This paper investigates the performance of half-duplex (HD) conventional DF relay system and cooperative systems (i.e., selective DF (SDF) and incremental DF (IDF)) over VLC channels in terms of outage probability and energy consumption. Analytical expressions for both outage probability and the minimum energy-per-bit performance of the aforementioned relaying systems are derived. Furthermore, Monte Carlo simulations are provided throughout the paper to validate the derived expressions. The results show that exploiting SDF and IDF relaying schemes can achieve approximately 25% and 15% outage probability enhancement compared to single-hop and DF protocols, respectively. The results also demonstrate that the performance of the single-hop VLC system deteriorates when the end-to-end distances become larger. For example, when the vertical distance is 3.5m, the single-hop approach consumes 20%, 40% and 45% more energy in comparison to the DF, SDF, and IDF approaches, respectively. Full article