Orthogonal frequency-division multiplexing (OFDM) effectively mitigates intersymbol interference (ISI) caused by the delay spread of wireless channels. Therefore, it has been used in many wireless ...systems and adopted by various standards. In this paper, we present a comprehensive survey on OFDM for wireless communications. We address basic OFDM and related modulations, as well as techniques to improve the performance of OFDM for wireless communications, including channel estimation and signal detection, time- and frequency-offset estimation and correction, peak-to-average power ratio reduction, and multiple-input-multiple-output (MIMO) techniques. We also describe the applications of OFDM in current systems and standards.
As a typical metal–organic framework material, UiO-66 has good potential for removing pharmaceuticals and personal care products from water. However, the application of this powdery adsorbent has ...been limited by the difficult recovery from the liquid. To overcome this weakness, we prepared composite beads constituted by sodium alginate and UiO-66 by solidification in CaCl
2
solution. The material was characterized by SEM, FTIR, XRD, BET, and TGA methods. These composite beads were applied to remove a common antibiotic Levofloxacin (LOFX) from water, and the experimental parameters (i.e., initial LOFX concentration, adsorption time, pH, and adsorbent dose) were optimized. The adsorption data could be satisfactorily fitted to the Langmuir isotherm model (
R
2
= 0.9871) and the pseudo-second-order kinetic model (
R
2
= 0.9990). The regeneration experiment of the composite beads revealed that the adsorption efficiency of levofloxacin was higher than 70% even after 5 cycles.
Scheme 1 Synthesis route of UiO-66/CA
A readily available small molecular hole‐transporting material (HTM), OMe‐TATPyr, was synthesized and tested in perovskite solar cells (PSCs). OMe‐TATPyr is a two‐dimensional π‐conjugated molecule ...with a pyrene core and four phenyl‐thiophene bridged triarylamine groups. It can be readily synthesized in gram scale with a low lab cost of around US$ 50 g−1. The incorporation of the phenyl‐thiophene units in OMe‐TATPyr are beneficial for not only carrier transportation through improved charge delocalization and intermolecular stacking, but also potential trap passivation via Pb–S interaction as supported by depth‐profiling XPS, photoluminescence, and electrochemical impedance analysis. As a result, an impressive best power conversion efficiency (PCE) of up to 20.6 % and an average PCE of 20.0 % with good stability has been achieved for mixed‐cation PSCs with OMe‐TATPyr with an area of 0.09 cm2. A device with an area of 1.08 cm2 based on OMe‐TATPyr demonstrates a PCE of 17.3 %.
A 2D hole‐transporting material with a pyrene core and four phenyl‐thiophene bridged triarylamine groups, OMe‐TATPyr, was readily synthesized at low cost on a gram scale. A power conversion efficiency (PCE) of up to 20.6 % (average PCE 20.0 %) was achieved for mixed‐cation perovskite solar cells with OMe‐TATPyr, outperforming devices with Spiro‐OMeTAD.
Chitosan modification is an important method for the development of adsorbents that has attracted considerable interest in recent years. In this regard, a new type of efficient Pb(II) adsorbent was ...prepared in a simple and cost-effective way. In this study, carboxylated chitosan (CYCS) and carboxylated nanocellulose (CNC) were used to chelate and synthesize hydrogel spheres with effective adsorption sites, in calcium chloride solution. The prepared carboxylated chitosan/carboxylated nanocellulose (CYCS/CNC) hydrogel beads were used as Pb(II) adsorbents, and using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, the structure and adsorption properties of the prepared beads were investigated. The CYCS/CNC adsorbents exhibited an excellent aqueous Pb(II) adsorption capacity (qm = 334.92 mg g−1), and the experimental results further revealed that the adsorption data fitted well with the Langmuir model, and the adsorption kinetics accorded with the pseudo-second-order model. Additionally, the adsorption mechanism was identified as monolayer chemisorption.
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•Efficient and economic CYCS/CNC composite is prepared for Pb(II) adsorption.•CYCS/CNC exhibits excellent aqueous Pb(II) adsorption capacity (Qm = 334.92 mg g−1).•Adsorption mechanism of CYCS/CNC includes chemical and electrostatic adsorption.•The adsorption performance is good even after four regeneration cycles.
Two new hole transporting materials (HTMs) based on triphenylamine and carbazole core moieties are designed and applied in planar perovskite solar cells. 18.2% power conversion efficiency (PCE) has ...been achieved, and 84% of the initial performance can be retained after 50 days.
Ventilator-induced lung injury (VILI) is caused by overdistension of the alveoli by the repetitive recruitment and derecruitment of alveolar units. This study aims to investigate the potential role ...and mechanism of fibroblast growth factor 21 (FGF21), a metabolic regulator secreted by the liver, in VILI development.
Serum FGF21 concentrations were determined in patients undergoing mechanical ventilation during general anesthesia and in a mouse VILI model. Lung injury was compared between FGF21-knockout (KO) mice and wild-type (WT) mice. Recombinant FGF21 was administrated in vivo and in vitro to determine its therapeutic effect.
Serum FGF21 levels in patients and mice with VILI were significantly higher than in those without VILI. Additionally, the increment of serum FGF21 in anesthesia patients was positively correlated with the duration of ventilation. VILI was aggravated in FGF21-KO mice compared with WT mice. Conversely, the administration of FGF21 alleviated VILI in both mouse and cell models. FGF21 reduced Caspase-1 activity, suppressed the mRNA levels of Nlrp3, Asc, Il-1β, Il-18, Hmgb1 and Nf-κb, and decreased the protein levels of NLRP3, ASC, IL-1β, IL-18, HMGB1 and the cleaved form of GSDMD.
Our findings reveal that endogenous FGF21 signaling is triggered in response to VILI, which protects against VILI by inhibiting the NLRP3/Caspase-1/GSDMD pyroptosis pathway. These results suggest that boosting endogenous FGF21 or the administration of recombinant FGF21 could be promising therapeutic strategies for the treatment of VILI during anesthesia or critical care.
Herein we report a new type of adsorbent for the efficient removal of Pb(II), which is prepared from cellulose nanofiber (CNF) and sodium alginate (SA) via a simple cross-linking method. During this ...process, the porous structure of the hydrogel beads was formed by the disintegration of calcium phosphate. The performance and structure of the prepared beads were systematically examined by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, zeta potential measurements, and scanning electron microscopy. Investigations revealed that the adsorption equilibrium was attained after approximately 120 min. In addition, 82% of Pb(II) ions were absorbed in the initial 40 min at 297 K. The adsorption process was consistent with a pseudo-second order kinetic model and the Langmuir adsorption isotherm model, and the limit adsorption capacity reached 318.47 mg g−1. Acid treatment and regeneration experiments verified that the adsorption capacity of Pb(II) on the beads was satisfactory, and the adsorption rate remained at >80% after 5 cycles. These results indicate that the prepared beads are potential adsorbents for water treatment.
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•Beads cellulose nanofiber alginate hydrogel beads were prepared by cross-linking.•In Pb(II) ion removal from aqueous solution, 82% of ions were adsorbed in 40 min.•A chemical adsorption mechanism via a single-layer process dominated.•The adsorption rate remained >80% (100% = 318.47 mg g−1) after 5 cycles.
To ascertain if preoperative short-term radiotherapy followed by chemotherapy is not inferior to a standard schedule of long-term chemoradiotherapy in patients with locally advanced rectal cancer.
...Patients with distal or middle-third, clinical primary tumor stage 3-4 and/or regional lymph node-positive rectal cancer were randomly assigned (1:1) to short-term radiotherapy (25 Gy in five fractions over 1 week) followed by four cycles of chemotherapy (total neoadjuvant therapy TNT) or chemoradiotherapy (50 Gy in 25 fractions over 5 weeks, concurrently with capecitabine chemoradiotherapy; CRT). Total mesorectal excision was undertaken 6-8 weeks after preoperative treatment, with two additional cycles of CAPOX (intravenous oxaliplatin 130 mg/m
, once a day on day 1 and capecitabine 1,000 mg/m
, twice a day from days 1 to 14) in the TNT group and six cycles of CAPOX in the CRT group. The primary end point was 3-year disease-free survival (DFS).
Between August 2015 and August 2018, a total of 599 patients were randomly assigned to receive TNT (n = 302) or CRT (n = 297). At a median follow-up of 35.0 months, 3-year DFS was 64.5% and 62.3% in TNT and CRT groups, respectively (hazard ratio, 0.883; one-sided 95% CI, not applicable to 1.11;
< .001 for noninferiority). There was no significant difference in metastasis-free survival or locoregional recurrence, but the TNT group had better 3-year overall survival than the CRT group (86.5%
75.1%;
= .033). Treatment effects on DFS and overall survival were similar regardless of prognostic factors. The prevalence of acute grade III-V toxicities during preoperative treatment was 26.5% in the TNT group versus 12.6% in the CRT group (
< .001).
Short-term radiotherapy with preoperative chemotherapy followed by surgery was efficacious with acceptable toxicity and could be used as an alternative to CRT for locally advanced rectal cancer.
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We synthesized composite microspheres from cellulose nanocrystal (CNC), polyvinyl alcohol (PVA), and sodium alginate (SA), which were modified with polyethyleneimine (PEI) to ...introduce a high density of active amino sites onto the surface via the Schiff base reaction. We hypothesized that these (SA/CNC/PVA)@PEI microspheres would have a high adsorption capacity for aqueous diclofenac sodium (DS).
The PEI-modified composite microspheres were characterized and assessed and optimized for aqueous DS adsorption. In addition, the morphology and synthesis mechanism of the adsorbent were studied.
The adsorption process showed a good fit with the pseudo-second-order kinetic model (i.e., the process is driven by a chemical adsorption mechanism) and Langmuir adsorption isotherm model (i.e., adsorption follows a single-layer process). Under the optimum experimental conditions (pH: 4.5, adsorption time: 50 min, temperature: 303 K), the maximum adsorption capacity was 418.4104 mg/g, which was relatively high compared to other reported adsorbents. Importantly, after five adsorption–desorption cycles, (SA/CNC/PVA)@PEI showed only a slight loss in adsorption capacity. Compared with other reported adsorbents, the core–shell composite has a good DS adsorptive capacity and high recyclability.
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