Digital-filter-aided crosstalk-mitigation for a high spatial resolution AWGR-based 2D IR beam-steered indoor optical wireless communication system.

The growing demand for wireless connectivity is attracting interest in optical wireless communication (OWC) technique. In this paper, a filter-aided crosstalk mitigation scheme, employing digital Nyquist filters, is proposed to eliminate the trade-off between the spatial resolution and the channel capacity for the AWGR-based 2D infrared beam-steered indoor OWC system. By shaping the transmitted signal for narrow spectral occupancy, the inter-channel crosstalk resulting from the imperfect AWGR filtering can be avoided, which enables a denser AWGR grid. In addition, the spectral-efficient signal reduces the bandwidth requirement of the AWGR, which allows a low-complexity AWGR design. Thirdly, the proposed method is not sensitive to the wavelength misalignment between AWGRs and lasers, which relaxes the design of high wavelength stability lasers. Moreover, the proposed method is cost-efficient as we can make use of the mature DSP technique without additional optical components. The 20-Gbit/s data rate OWC capacity using PAM4 format has been experimentally demonstrated over a 6-GHz bandwidth-limited AWGR-based 1.1-m free-space link. The experimental results show the feasibility and effectiveness of the proposed method. By combining our proposed method with the polarization orthogonality technique, a promising capacity per beam of 40 Gbit/s is potentially attainable.

Entropy subspace separation-based clustering for noise reduction (ENCORE) of scRNA-seq data.

Single-cell RNA sequencing enables us to characterize the cellular heterogeneity in single cell resolution with the help of cell type identification algorithms. However, the noise inherent in single-cell RNA-sequencing data severely disturbs the accuracy of cell clustering, marker identification and visualization. We propose that clustering based on feature density profiles can distinguish informative features from noise. We named such strategy as 'entropy subspace' separation and designed a cell clustering algorithm called ENtropy subspace separation-based Clustering for nOise REduction (ENCORE) by integrating the 'entropy subspace' separation strategy with a consensus clustering method. We demonstrate that ENCORE performs superiorly on cell clustering and generates high-resolution visualization across 12 standard datasets. More importantly, ENCORE enables identification of group markers with biological significance from a hard-to-separate dataset. With the advantages of effective feature selection, improved clustering, accurate marker identification and high-resolution visualization, we present ENCORE to the community as an important tool for scRNA-seq data analysis to study cellular heterogeneity and discover group markers.

Decoding Expression Dynamics of Protein and Transcriptome at the Single-Cell Level in Paired Picoliter Chambers.

Simultaneous analysis of mRNAs and proteins at the single-cell level provides information about the dynamics and correlations of gene and protein expressions in individual cells, enabling a comprehensive study of cellular heterogeneity and expression patterns. Here, we present a platform for about 1000 cellular indexing of mRNAs and membrane proteins, named multi-Paired-seq, with high cell utilization, accurate molecular measurement, and low cost. Based on hydrodynamic differential flow resistance, multi-Paired-seq largely improves cell utilization in the percentage of cells measured in population (>95%). Combined with the pump/valve structure, cell-free antibodies and mRNAs can be removed completely for highly accurate detection (R = 0.96) of protein copies. The picoliter reaction chambers allow high detection sensitivity for both mRNA transcripts and protein copies and low sequencing cost. Using multi-Paired-seq, three clusters of known breast cancer cell types are identified according to multimodal measurements, and the expression correlations between mRNAs and proteins under altered conditions are quantified. Multi-Paired-seq provides multimodal measurements at the single-cell level, which offers a new tool for cell biology, developmental biology, drug discovery, and precision medicine.

Overexpression of AHL9 accelerates leaf senescence in Arabidopsis thaliana.

BACKGROUND: Leaf senescence, the final stage of leaf growth and development, is regulated by numerous internal factors and environmental cues. Ethylene is one of the key senescence related hormones, but the underlying molecular mechanism of ethylene-induced leaf senescence remains poorly understood. RESULTS: In this study, we identified one AT-hook like (AHL) protein, AHL9, as a positive regulator of leaf senescence in Arabidopsis thaliana. Overexpression of AHL9 significantly accelerates age-related leaf senescence and promotes dark-induced leaf chlorosis. The early senescence phenotype observed in AHL9 overexpressing lines is inhibited by the ethylene biosynthesis inhibitor aminooxyacetic acid suggesting the involvement of ethylene in the AHL9-associated senescence. RNA-seq and quantitative reverse transcription PCR (qRT-PCR) data identified numerous senescence-associated genes differentially expressed in leaves of AHL9 overexpressing transgenic plants. CONCLUSIONS: Our investigation demonstrates that AHL9 functions in accelerating the leaf senescence process via ethylene synthesis or signalling.

Fluorescent Biosensor Based on Hairpin DNA Stabilized Copper Nanoclusters for Chlamydia trachomatis Detection.

Chlamydia trachomatis (C. trachomatis) is a kind of intracellular parasitic microorganism, which can causes many diseases such as trachoma. In this strategy, a specific hairpin DNA with the probe loop as specific regions to recognize C. trachomatis DNA with strong affinity was designed, and its stem consisted of 24 AT base pairs as an effective template for hairpin DNA-CuNCs formation. In the absence of C. trachomatis DNA, the detection system showed strong orange fluorescence emission peaks at 606 nm. In the presence of C. trachomatis DNA, the conformation of DNA probe changed after hybridizing with C. trachomatis DNA. Then, the amount of hairpin DNA-CuNCs was reduced and resulted in low fluorescence emission. C. trachomatis DNA displayed a significant inhibitory effect on the synthesis of fluorescent hairpin DNA-CuNCs due to the competition between C. trachomatis DNA and the specific hairpin DNA. Under the optimal experimental conditions, different concentrations of C. trachomatis were tested and the results showed a good linear relationship in the range of 50 nM to 950 nM. Moreover, the detection limit was 18.5 nM and this detection method possessed good selectivity. Finally, the fluorescent biosensor had been successfully applied to the detection of C. trachomatis target sequence in HeLa cell lysate, providing a new strategy for the detection of C. trachomatis.

Optimization of UC-MSCs cold-chain storage by minimizing temperature fluctuations using an automatic cryopreservation system.

The effective long-term cryopreservation of human mesenchymal stem cells is an essential prerequisite step and represents a critical approach for their sustained supply in basic research, regenerative medicine, and tissue engineering applications. Off-the-shelf availability of human umbilical cord-derived mesenchymal stromal cells (UC-MSCs) for regenerative medicine application requires the development of nontoxic, safe, and efficient protocols for cryopreservation. In the long-term low-temperature storage process of cells, traditional manual storage has a great impact on cell activity, recovery, and function due to repeated exposure of cells to room temperature. To minimize the effect of fluctuation in ambient temperature on stored cells, we designed an automatic cryopreservation system that handles cells under controlled temperatures. In this work, UC-MSCs were utilized to investigate and compare the influence of manual and automatic cryopreservation approaches. To simulate the manual process, the UC-MSCs were transferred back and forth repeatedly (up to 400 times) between the liquid nitrogen (LN2) tank (-150 °C) and room temperature by a robotic arm. Similarly, the UC-MSCs from the same batch were collected and transferred repeatedly between two storage units by the automatic cryopreservation system, where the cells were maintained below-150 °C throughout the cold chain process. Viability, percent recovery, adherence capability, cell proliferation, and multilineage differentiation ability were assessed for UC-MSCs. Compared to the manual approach, UC-MSCs handled by the automatic system demonstrated higher viability, percent recovery, and cell proliferation, as well as improved adherence to culture plate with greater potential in multilineage differentiation after 400 temperature cycles. The described entire cold chain system may provide a powerful tool to develop safe, reliable and efficient protocols for manufacturing and banking of UC-MSCs, improving their off-the-shelf availability for regenerative medicine applications.

HMGB1-activated fibroblasts promote breast cancer cells metastasis via RAGE/aerobic glycolysis.

Highly expressed high mobility group box-1 protein (HMGB1) promotes tumor metastasis. Whether HMGB1 participates in breast cancer cell activation of fibroblasts is unknown. The culture medium of 6 breast cancer cell lines with different migration potential, and with HMGB1 overexpression or knockdown was used to induce fibroblast activation, and collagen and α-SMA expression were measured. We evaluated the migration potential of MDA-MB-231 cells with fibroblasts treated with 3-PO (3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one) inhibitor, anti-HMGB1 treatment, or RAGE (receptor for advanced glycation end products) knockdown. A lung metastasis murine model was used to evaluate whether the RAGE-knockdown fibroblasts mitigates MDA-MB-231 metastasis. Breast cancer cells that are highly migratory and have a high invasive potential, had higher HMGB1 expression and induced greater fibroblast activation strongly than cells with poorer motility. hrHMGB1 and the supernatants of HMGB1-overexpressed MCF-7 cells promoted fibroblast activation, but loss-HMGB1 of MDA-MB-231 abolished potential. Moreover, a novel mechanism was identified by which HMGB1 facilitated fibroblast activation by RAGE/aerobic glycolysis. Consistently, fibroblasts enhanced MDA-MB-231 metastasis, but the enhancement was reversed by 3-PO inhibition, anti-HMGB1 treatment, or RAGE knockdown in vitro and in vivo. We identified that HMGB1 secreted by breast cancer cells promotes fibroblast activation via RAGE/aerobic glycolysis, and activated fibroblasts enhance breast cancer cell metastasis through increased lactate.

The evaluation of maximum condyle-tragus distance can predict difficult airway management without exposing upper respiratory tract; a prospective observational study.

BACKGROUND: Routine preoperative methods to assess airway such as the interincisor distance (IID), Mallampati classification, and upper lip bite test (ULBT) have a certain risk of upper respiratory tract exposure and virus spread. Condyle-tragus maximal distance(C-TMD) can be used to assess the airway, and does not require the patient to expose the upper respiratory tract, but its value in predicting difficult laryngoscopy compared to other indicators (Mallampati classification, IID, and ULBT) remains unknown. The purpose of this study was to observe the value of C-TMD to predict difficult laryngoscopy and the influence on intubation time and intubation attempts, and provide a new idea for preoperative airway assessment during epidemic. METHODS: Adult patients undergoing general anesthesia and tracheal intubation were enrolled. IID, Mallampati classification, ULBT, and C-TMD of each patient were evaluated before the initiation of anesthesia. The primary outcome was intubation time. The secondary outcomes were difficult laryngoscopy defined as the Cormack-Lehane Level > grade 2 and the number of intubation attempts. RESULTS: Three hundred four patients were successfully enrolled and completed the study, 39 patients were identified as difficult laryngoscopy. The intubation time was shorter with the C-TMD>1 finger group 46.8 ± 7.3 s, compared with the C-TMD<1 finger group 50.8 ± 8.6 s (p<0.01). First attempt success rate was higher in the C-TMD>1 finger group 98.9% than in the C-TMD<1 finger group 87.1% (P<0.01). The correlation between the C-TMD and Cormack-Lehane Level was 0.317 (Spearman correlation coefficient, P<0.001), and the area under the ROC curve was 0.699 (P<0.01). The C-TMD < 1 finger width was the most consistent with difficult laryngoscopy (κ = 0.485;95%CI:0.286-0.612) and its OR value was 10.09 (95%CI: 4.19-24.28), sensitivity was 0.469 (95%CI: 0.325-0.617), specificity was 0.929 (95%CI: 0.877-0.964), positive predictive value was 0.676 (95%CI: 0.484-0.745), negative predictive value was 0.847 (95%CI: 0.825-0.865). CONCLUSION: Compared with the IID, Mallampati classification and ULBT, C-TMD has higher value in predicting difficult laryngoscopy and does not require the exposure of upper respiratory tract. TRIAL REGISTRATION: The study was registered on October 21, 2019 in the Chinese Clinical Trial Registry ( ChiCTR1900026775 ).

[Sequence analysis for a case with Para-Bombay AB blood type].

OBJECTIVE: To explore the molecular basis for a rare case with Para-Bombay AB blood type. METHODS: Serological method was used to determine the blood type of the proband. Exons 6 and 7 of the ABO gene and the coding regions of FUT1 and FUT2 genes were analyzed by direct sequencing. RESULTS: Serological results showed that the proband was a Para-Bombay AB subtype. His genotype was determined as ABO*A1.02/B.01. The proband was also found to harbor c.551-552delAG and c.881-882delTT of the FUT1 gene. For his four children, there were three type B and one type A, though the expression of the H type was normal. CONCLUSION: The double deletions in the coding region of the FUT1 gene probably underlay the Para-Bombay blood type in the proband. Carrier of single-strand deletions may have a normal ABO phenotype.

Nonstochastic Protein Counting Analysis for Precision Biomarker Detection: Suppressing Poisson Noise at Ultralow Concentration.

Protein counting analysis obtains the quantitative results of specific protein through counting the number of target signals and displays a great value in disease diagnosis. Current protein counting techniques just stochastically count a small portion of the target signal, which causes a considerable information loss and limits the accuracy and precision of the protein assay at ultralow concentration. Here, we present a nonstochastic and ultrasensitive protein counting method through combining multiround evaporation-induced particle sedimentation, grid-assisted multiframe imaging, and microsphere-enhanced high-resolution signals. Using carcinoembryonic antigen (CEA) as the model, the dynamic range was from 5 × 10-18 M (aM) to 5 × 10-16 M, and the limit of detection was 4.9 aM. For CEA-spiked plasma detection, the relative standard deviation and the relative error of CEA concentrations were both lower than 8.0%, and the recoveries reached 92.5% and 98.8% for 20.0 aM and 40.0 aM CEA respectively. Two clinical plasma samples were measured by the standard addition method, and the results showed little deviation with the values provided by the hospital. The established approach suppresses Poisson noise of the stochastic counting, offers ultrahigh sensitivity, and features a remarkable potential in early disease screening.

A Highly Sensitive, Accurate, and Automated Single-Cell RNA Sequencing Platform with Digital Microfluidics.

Single-cell RNA sequencing (scRNA-seq) is a powerful method in investigating single-cell heterogeneity to reveal rare cells, identify cell subpopulations, and construct a cell atlas. Conventional benchtop methods for scRNA-seq, including multistep operations, are labor intensive, reaction inefficient, contamination prone, and reagent consuming. Here we report a digital microfluidics-based single-cell RNA sequencing (digital-RNA-seq) for simple, efficient, and low-cost single-cell mRNA measurements. Digital-RNA-seq automates fluid handling as discrete droplets to sequentially perform protocols of scRNA-seq. To overcome the current problems of single-cell isolation in efficiency, integrity, selectivity, and flexibility, we propose a new strategy, passive dispensing method, relying on well-designed hydrophilic-hydrophobic microfeatures to rapidly generate single-cell subdroplets when a droplet of cell suspension is encountered. For sufficient cDNA generation and amplification, digital-RNA-seq uses nanoliter reaction volumes and hydrophobic reaction interfaces, achieving high sensitivity in gene detection. Additionally, the stable droplet handling and oil-closed reaction space featured in digital-RNA-seq ensure highly accurate measurement. We demonstrate the functionality of digital-RNA-seq by quantifying heterogeneity among single cells, where digital-RNA-seq shows excellent performance in rare transcript detection, cell type differentiation, and essential gene identification. With the advantages of automation, sensitivity, and accuracy, digital-RNA-seq represents a promising scRNA-seq platform for a wide variety of biological applications.

Overexpression and Biochemical Characterization of an Endo-α-1,4-polygalacturonase from Aspergillus nidulans in Pichia pastoris.

Pectinases have many applications in the industry of food, paper, and textiles, therefore finding novel polygalacturonases is required. Multiple sequence alignment and phylogenetic analysis of AnEPG (an endo-α-1,4-polygalacturonase from Aspergillus nidulans) and other GH 28 endo-polygalacturonases suggested that AnEPG is different from others. AnEPG overexpressed in Pichia pastoris was characterized. AnEPG showed the highest activity at pH 4.0, and exhibited moderate activity over a narrow pH range (pH 2.0-5.0) and superior stability in a wide pH range (pH 2.0-12.0). It displayed the highest activity at 60 °C, and retained >42.2% of maximum activity between 20 and 80 °C. It was stable below 40 °C and lost activity very quickly above 50 °C. Its apparent kinetic parameters against PGA (polygalacturonic acid) were determined, with the Km and kcat values of 8.3 mg/mL and 5640 µmol/min/mg, respectively. Ba2+ and Ni2+ enhanced activity by 12.2% and 9.4%, respectively, while Ca2+, Cu2+, and Mn2+ inhibited activity by 14.8%, 12.8%, and 10.2% separately. Analysis of hydrolysis products by AnEPG proved that AnEPG belongs to an endo-polygalacturonase. Modelled structure of AnEPG by I-TASSER showed structural characteristics of endo-polygalacturonases. This pectinase has great potential to be used in food industry and as feed additives.

Cost-efficient half-duplex 10 Gbit/s all-optical indoor optical wireless communication enabled by a low-cost Fabry-Perot laser/photodetector.

To develop an indoor optical wireless communication (OWC) system, both the system complexity/cost and data rate need to be taken into consideration. In this Letter, a cost-efficient half-duplex OWC system for photonic home area network applications is proposed and experimentally demonstrated. A low-cost Fabry-Perot laser diode is proposed to be employed as both the downlink receiver (Rx) and uplink transmitter at the user side. Enabled by the Fabry-Perot transceiver, the indoor transmission of 10 Gbit/s four-level pulse-amplitude-modulation signal for both downlinks and uplinks is experimentally achieved over a 1.7 km single-mode fiber and 1.1 m free space. Moreover, the proposed scheme also enables us to operate an orthogonal frequency division multiplexing (OFDM) signal. The bit error rate levels of multi-gigabit OFDM data for both downlinks and uplinks over a 10 h measurements are all under a 7% forward error correction limit of 3.8×10-3, which indicates that the proposed system is robust and, thus, can provide a promising solution for high-speed low-cost home area OWC networks.

40 Gb/s indoor optical wireless system enabled by a cyclically arranged optical beamsteering receiver.

Indoor optical wireless communication with optical beamsteering capability is currently attracting a lot of attention. One major two-dimensional (2D) optical beamsteering scheme is realized by 2D grating or its active counterpart, which is usually based on a spatial light modulator (SLM). However, there is a fundamental trade-off between the field of view (FoV) and power efficiency due to the inherent feature of gratings. In this Letter, we propose a new class of 2D beamsteering, named cyclically arranged optical beamsteering (CAO-BS), which can break that trade-off. Traditional 2D gratings extend the optical beam in the Cartesian coordinates (1D grating in horizontal + 1D grating in vertical), while CAO-BS extends the optical beam in the polar coordinates (1D grating + angular rotation). Since only 1D grating is engaged, the power efficiency increases with the number of grating lobes reduced. In the polar coordinates, the angle rotation tuning in a SLM is quasi-continuous in a full 2π range. The CAO-BS is demonstrated at the receiving end in an indoor experimental system. The FoV is 18° by 360° in polar coordinates without any additional mechanical parts. Based on the CAO-BS, 40 Gbit/s on-off keying data is also successfully transmitted over 1 km single-mode fiber and 0.5 m free space.

Developmental changes in the level of free and conjugated sialic acids, Neu5Ac, Neu5Gc and KDN in different organs of pig: a LC-MS/MS quantitative analyses.

Recent studies have shown a relationship between the level of the sialic acid (Sia), N-glycolylneuraminic acid (Neu5Gc) in red meat and its risk in cancer, cardiovascular and inflammatory diseases. Unresolved is the Sia concentration in different organs of piglets during development. Our aim was to determine the level of free and conjugated forms of Neu5Gc, N-acetylneuraminic acid (Neu5Ac) and ketodeoxynonulsonic acid (Kdn) in fresh and cooked spleen, kidney, lung, heart, liver, and skeletal muscle from 3-days-old (n = 4-8), 38-days-old (n = 10) and adult piglets (n = 4) by LC-MS/MS. Our findings show: (1) Lung tissue from 3 days-old piglets contained the highest level of total Sia (14.6 µmol/g protein) compared with other organs or age groups; (2) Unexpectedly, Neu5Gc was the major Sia in spleen (67-79 %) and adult lung (36-49 %) while free Kdn was the major Sia in skeletal muscle. Conjugated Neu5Ac was the highest Sia in other organs (61-84 %); (3) Skeletal muscle contained the lowest concentration of Neu5Gc in fresh and cooked meat; (4) Kdn accounted for <5 % of the total Sia in most organs; (5) During development, the total Sia concentration showed a 44-79 % decrease in all organs; (6) In adult piglets, the high to low rank order of total Sia was lung, heart, spleen, kidney, liver and skeletal muscle. In conclusion, the high level of Neu5Gc in all organs compared to skeletal muscle is a potential risk factor suggesting that dietary consumption of organ meats should be discouraged in favor of muscle to protect against cancer, cardiovascular and other inflammatory diseases.

Refractory sciatica caused by gluteal varicosities.

We report a case of sciatica that fulfilled the diagnostic criteria for inferior gluteal vein varicosities according to patient history and on magnetic resonance imaging. Since conservative treatment was ineffective, excision-ligation of the varicose vein was performed as recommended in the previous literature. However, pain was only slightly relieved and then aggravated. Reoperation involving wide release and resection of the piriformis outlet was performed. Pain resolved immediately thereafter. We suggest that this case of sciatica resulted from both piriformis entrapment and vein varicosities. The piriformis entrapment led to inferior gluteal vein backflow obstruction, and varicosities could have been the trigger of piriformis syndrome. Excision-ligation of the varicose vein and piriformis release were recommended.

Advanced modulation formats for 400-Gbps short-reach optical inter-connection.

Besides the long-haul optical networks covering over thousands of kilometers for backbone transmission, short reach optical networks (SR-ONs) are widely deployed in metro-area for aggregation and accessing. The SR-ONs include the metro optical transport networks (Metro-OTN), optical access networks or other optical inter-connection systems with even shorter distance. As predicted, the growing bandwidth demanding from SR-ONs will be much more than that from the long-haul optical networks in the near future. Besides, there are tremendous amounts of optical terminals and end-users in SR-ONs compared with the long-haul transmission systems and thus will induce large cost and huge energy consumption. So, the power and cost efficiency should be the key consideration for SR-ONs besides the transmission performance. To improve the power and cost efficiency in SR-ONs, advanced modulations and detection techniques based on low power, low cost and integrated optical modulators should be utilized. In this paper, different advanced modulation formats have been discussed. 56Gbps PAM4, 112Gbps poly-binary and 100Gbps DMT that can be used to realize 400-Gbps SR-ONs for different applications have also been demonstrated respectively. In addition, low-cost and low-power opto-electronic components suitable for SR-ONs, the impairments induced by all kinds of defects and bandwidth limitation of opto-electronic components and the corresponding compensation techniques based on DSP algorithms have also been discussed in the experiments.

Theoretical studies on the polarization-modulator-based single-side-band modulator used for generation of optical multicarrier.

This paper focuses on the studies on the polarization- modulator-based single-side-band modulator (PSSBM) as well as its implementation in generation of frequency-locked multicarrier. The principle and properties of PSSBM have been analyzed in detail with theoretical and simulation results. Then, the PSSBM-based frequency-locked multicarrier generator (PSMCG) with recirculating frequency shifting loop has also been demonstrated via simulation. The results have a good agreement with the theoretical analysis. According to the results, multiple frequency-locked carriers with high quality can be achieved based on the proposed PSMCG. The generated carriers have the potential applications in different scenarios such as optical transmission, microwave photonics and so on.

Transmission of 100-Gb/s DDO-OFDM/OQAM over 320-km SSMF with a single photodiode.

In this paper, we propose a novel approach to simultaneously receive multi-band 100-Gb/s direct-detection optical signal with only one polarization and one conventional 40-GHz photodiode. The modulation format of orthogonal frequency-division multiplexing based on offset quadrature amplitude modulation (OFDM/OQAM) is selected to provide signal spectrum with high side-lobe suppression ratio, which can effectively reduce the electrical sub-band frequency interference. The whole 100-Gb/s OFDM/OQAM signal is comprised of 6 sub-bands with 16- and 32-QAM formats loading. Only one guard band is required to accommodate the overlapped 6-band signal-to-signal beat interference (SSBI). The receiver bandwidth is mainly limited by the digital storage oscilloscope (DSO) of 33 GHz. The transmission distance over standard single mode fiber (SSMF) is up to 320 km.

Single photodiode direct detection system of 100-Gb/s OFDM/OQAM-64QAM over 80-km SSMF within a 50-GHz optical grid.

We propose a novel guard-band-shared direct-detection (GBS-DD) scheme to improve the receiver spectrum efficiency (SE). The 100-Gb/s signal is modulated by 2 sub-bands, which are assigned onto two orthogonal polarizations. The central wavelengths of the two sub-bands are set as 10.84-GHz frequency space. The two sub-bands are then received simultaneously using a single conventional photodiode (PD) of 40-GHz bandwidth. Only one optical pilot carrier is inserted to beat with the 2 sub-bands on the two polarizations. When the 2 sub-band signal entering into the receiver, the signal-to-signal beat interference (SSBI) terms fall and overlap in the same guard band. As a consequence, the bandwidth usage of the PD is enhanced from 1/2 to 2/3. The 100-Gb/s signal is modulated using orthogonal frequency-division multiplexing based on offset quadrature-amplitude-modulation of 64-quadrature amplitude modulation (OFDM/OQAM-64QAM), and transmitted over 80-km standard single mode fiber (SSMF) within a 50-GHz optical grid. It is shown that the proposed GBS-DD scheme can be implemented by the current commercial optical/electrical devices.