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1.
Sci Total Environ ; 938: 173495, 2024 May 24.
Article in English | MEDLINE | ID: mdl-38797410

ABSTRACT

Zero-valent aluminum (ZVAl) is a potential activator for peroxodisulfate (PDS), yet the dense oxide film on its surface hampers electron transfer for the O-O bond cleavage of PDS. We synthesized zero-valent aluminum-biochar (BM-ZVAl@BC) composites through ball milling, which effectively disrupted the native oxide layer on BM-ZVAl@BC. Within the BM-ZVAl@BC/PDS system, biochar (BC) not only suppressed the rapid oxidation of BM-ZVAl@BC but also enhanced the dispersion and electron transfer rate of ZVAl, thereby improving the overall catalytic efficiency. Consequently, the phenol removal efficacy in the BM-ZVAl@BC/PDS system was notably improved. Optimal catalytic performance of the prepared BM-ZVAl@BC was achieved at a charcoal-to­aluminum mass ratio of 2:1, resulting in 95.7 % phenol removal after 180 min. Quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that both free radicals (SO4•-, •OH, and O2•-) and non-radical species (1O2) contributed to phenol degradation, with SO4•- and •OH playing predominant roles. In summary, the BM-ZVAl@BC/PDS system represented an effective and promising technology for the remediation of phenolic water pollutants.

2.
Appl Opt ; 63(9): 2352-2361, 2024 Mar 20.
Article in English | MEDLINE | ID: mdl-38568591

ABSTRACT

Improving the spectrum efficiency (SE) is an effective method to further enhance the data rate of bandwidth-limited underwater wireless optical communication (UWOC) systems. Non-orthogonal frequency-division multiplexing (NOFDM) with a compression factor of 0.5 can save half of the bandwidth without introducing any inter-carrier-interference (ICI) only if the total number of subcarriers is large enough, and we termed it as half-spectrum OFDM (HS-OFDM). To the best of our knowledge, this is the first reported work on a closed-form HS-OFDM signal in the discrete domain from the perspective of a correlation matrix. Due to the special mathematical property, no extra complex decoding algorithm is required at the HS-OFDM receiver, making it as simple as the conventional OFDM receiver. Compared with traditional OFDM, HS-OFDM can realize the same data rate, but with a larger signal-to-noise ratio (SNR) margin. To fully use the SNR resource of the communication system, we further propose a digital power division multiplexed HS-OFDM (DPDM-HS-OFDM) scheme to quadruple the SE of conventional OFDM for the bandwidth-starved UWOCs. The experimental results show that HS-OFDM can improve the receiver sensitivity by around 4 dB as opposed to conventional 4QAM-OFDM with the same data rate and SE. With the help of the DPDM-HS-OFDM scheme, the data rate of multi-user UWOC can reach up to 4.5 Gbps under the hard-decision forward error correction (HD-FEC) limit of a bit error rate (BER) of 3.8×10-3. Although there is some performance degradation in comparison with single-user HS-OFDM, the BER performance of multi-user DPDM-HS-OFDM is still superior to that of conventional single-user 4QAM-OFDM. Both single-user HS-OFDM and multi-user DPDM-HS-OFDM successfully achieve 2 Gbps/75 m data transmission, indicating that the DPDM-HS-OFDM scheme is of great importance in bandwidth-limited UWOC systems and has guiding significance to underwater wireless optical multiple access.

3.
Opt Express ; 31(20): 33435-33448, 2023 Sep 25.
Article in English | MEDLINE | ID: mdl-37859126

ABSTRACT

Due to a great many superior features of infrared light communication (ILC), like high capacity and strong privacy, ILC is considered a potential candidate for serving the high demands of beyond fifth-generation/sixth-generation (B5G/6 G) communication systems. However, the terminal's limited field-of-view (FOV) induces great difficulty in establishing line-of-sight (LoS) link between the transceiver and the terminal. In this paper, we propose a wide-FOV auto-coupling optical antenna system that utilizes a wide-FOV telecentric lens to collect incident infrared beams and automatically couple them into a specific single-mode-fiber (SMF) channel of fiber array and optical switch. The performance of this optical antenna system is assessed through simulation and manual alignment operation, and validated by automatic alignment results. A coupling loss of less than 10.6 dB within a FOV of 100° for both downstream and upstream beams in C band is demonstrated by the designed system. Furthermore, we establish a bidirectional optical wireless communications (OWC) system employing this antenna and a fiber-type modulating retro-reflector (MRR) system in the terminal. Both 10-Gbps on-off keying (OOK) downstream and upstream transmissions are successfully realized with the FOV of up to 100° in C band where the measured bit-error-rate (BER) is lower than 3.8 × 10-3. To the best of our knowledge, this is a brand-new auto-coupling optical antenna system with the largest FOV in ILC automatic alignment works in terminals that have ever been reported.

4.
Chem Biodivers ; 20(12): e202301206, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37840218

ABSTRACT

Storage is a crucial part during grain production for the massive spoilage caused by stored product insects. Essential oils (EOs) of plant origin have been highly recommended to combating insects which are biodegradable and safe mode of action. Hence, to make the fullest use of natural resources, essential oils of different parts from Piper yunnanense (the whole part, PYW; fruits, PYF; leaves, PYL) and Piper boehmeriifolium (leaves, PBL) were extracted by steam distillation method in the present study. Gas chromatography-mass spectrometry (GC-MS) characterization revealed bicyclogermacrene (PYW), γ-muurolene (PYF), δ-cadinene (PYL) and methyl 4,7,10,13,16,19-docosahexaenoate (PBL) as the principal compound of each essential oil. Sesquiterpene hydrocarbons were also recognized as the richest class accounting for 56.3 %-94.9 % of the total oil. Three storage pests, Tribolium castaneum, Lasioderma serricorne and Liposceis bostrychophila, were exposed to different concentrations of EOs to determine their insecticidal effects. All tested samples performed modest contact toxicity in contrast to a bioactive ingredient pyrethrin, among which the most substantial effects were observed in PYF EOs against T. castaneum (35.84 µg/adult), PBL EOs against L. serricorne (15.76 µg/adult) and PYW EOs against L. bostrychophila (57.70 µg/cm2 ). In terms of repellency tests, essential oils of PYF at 78.63 nL/cm2 demonstrated to have a remarkable repellence against T. castaneum at 2h and 4h post-exposure. The investigations indicate diverse variations in the chemical profiles and insecticidal efficacies of P. yunnanense and P. boehmeriifolium EOs, providing more experimental evidence for the use of the Piper plants.


Subject(s)
Coleoptera , Insect Repellents , Insecticides , Oils, Volatile , Piper , Tribolium , Animals , Oils, Volatile/chemistry , Insecta , Insect Repellents/pharmacology , Insect Repellents/chemistry , Insecticides/chemistry
5.
PhytoKeys ; 227: 99-108, 2023.
Article in English | MEDLINE | ID: mdl-37303594

ABSTRACT

A new species of pelagic diatom, Pleurosigmapacificumsp. nov., is described from the tropical Western Pacific Ocean. It has the typical features of Pleurosigma, including a slightly sigmoid raphe, intersected transverse and oblique striae, and loculate areolae with external opening slits and internal poroids. Morphologically, P.pacificum belongs to a species group of Pleurosigma with lanceolate valves, including P.atlanticum Heiden & Kolbe, P.nubecula W. Smith, P.indicum Simonsen, and P.simonsenii Hasle. However, P.pacificum differs by its smaller lanceolate valve and smaller intersection angle as well as elliptical areolae without a silica bar. The SSU rDNA and rbcL sequence data place P.pacificum in a basal position relative to other species of Pleurosigma. Our molecular phylogenetic analyses did not support the monophyly of lanceolate and slightly sigmoid species. Thus, the sigmoidality of valve outline cannot be considered as a criterion to define the species group.

6.
Huan Jing Ke Xue ; 44(2): 1191-1200, 2023 Feb 08.
Article in Chinese | MEDLINE | ID: mdl-36775641

ABSTRACT

Rural sewage treatment in the Yangtze River basin is an important link to achieve the great protection of the Yangtze River, but the existing treatment technologies are difficult to choose and have various techniques and a lack of evaluation. Therefore, this study researched and collected the case information of rural sewage treatment projects in the middle reaches of the Yangtze River, analyzed the application of each treatment technology under different collection modes and discharge standards, constructed the evaluation index system of rural sewage treatment technologies, and then conducted a classification evaluation of processing technologies for each application scenario based on group decision making and the Analytic Hierarchy Process. The results showed that:the collection modes of rural sewage in the middle reaches of the Yangtze River were mainly single village or small-scale joint village, the treatment scale was mainly concentrated below 200 m3·d-1, the treatment technology was most applied by the anaerobic+ecological process (28.05%), and the application of integrated equipment was also more widely used (22.47%). The technical performance in the criterion layer had the largest weight (0.5039) in the evaluation index system, followed by those of economic benefits (0.2474), operation and management (0.1559), and environmental impact (0.0928), respectively; the four indicators of TP removal rate, ton water operation cost, ammonia nitrogen removal rate, and maintenance difficulty had higher weights. The evaluation and optimization results showed that the enhanced ecological and anaerobic+ecological treatment technologies were suitable for promotion and application in the rural areas of the middle reaches of the Yangtze River. The results of this study can provide scientific basis and reference for the selection of rural sewage treatment technologies in the middle reaches of the Yangtze River.


Subject(s)
Rivers , Sewage , Analytic Hierarchy Process , Nitrogen , Decision Making , China
7.
J Am Chem Soc ; 145(8): 4400-4407, 2023 Mar 01.
Article in English | MEDLINE | ID: mdl-36800284

ABSTRACT

Catalytic asymmetric cross-coupling of imines constitutes a particularly desirable method for the synthesis of chiral vicinal diamines directly from readily available achiral precursors. The potential of this method lies in the possibility of utilizing a variety of imines as reacting partners. However, the realization of highly stereoselective cross-coupling of two different imines proved to be a formidable challenge. Herein we report an unprecedented catalytic asymmetric cross-coupling reaction that tolerates a variety of ketimines and aldimines as nucleophiles and electrophiles, respectively. The realization of this reaction resulted from the development of a new chiral ammonium catalyst, which was guided by insights from studies of catalyst-substrate interactions. With a 0.5 mol % loading of an organocatalyst, this reaction proceeded in a highly diastereo- and enantioselective manner to afford a diverse range of chiral vicinal diamines as nearly single stereoisomers. This catalytic reaction establishes a new approach for the asymmetric synthesis of chiral vicinal diamines.

8.
Appl Opt ; 62(3): 541-551, 2023 Jan 20.
Article in English | MEDLINE | ID: mdl-36821256

ABSTRACT

Underwater wireless optical communication (UWOC) has broad prospects in underwater real-time applications. We design and experimentally demonstrate a real-time discrete Fourier transform spread discrete multi-tone (DFT-S DMT) signal transmission based on a field programmable gate array for a blue-LED-based UWOC system with a data rate of up to 30 Mbps over a 15-m underwater channel. The architecture and usage of an on-chip resource as well as power consumption are analyzed and discussed. To reduce the impacts of multipath fading and received intensity fluctuation, spatial diversity reception is also introduced. Furthermore, the receiver sensitivity at a specified bit error rate (BER) threshold and the quality of the images are evaluated using three types of Reed-Solomon (RS) codes. At the BER threshold of 10-4, over 2.8-dB receiver sensitivity improvement is obtained by the DFT-S DMT scheme with the RS (64, 56) code as compared to the uncoded one at the data rate of 30 Mbps. The performance of BER, color difference, and structural similarity in the image transmission of DFT-S DMT is superior to that of the conventional hard clipping quadrature amplitude modulation DMT in a high-data-rate region because of the low peak-to-average-power ratio and ability to mitigate high-frequency fading in a band-limited UWOC system. With schemes of the RS code, DFT-S, and diversity reception, error-free transmission of images is achieved over a 15-m water channel. The proposed UWOC system has the advantages of low power consumption and portability, which foresees a bright future in underwater applications over short to moderate distances.

9.
Appl Opt ; 61(22): 6534-6543, 2022 Aug 01.
Article in English | MEDLINE | ID: mdl-36255878

ABSTRACT

The nonlinearity of the light-emitting diode (LED) in underwater wireless optical communication (UWOC) systems is considered the one major limiting factor that degrades the system's performance. Volterra series-based nonlinear equalization is widely employed to mitigate such nonlinearity in communication systems. However, the conventional Volterra series-based model is of high complexity, especially for the nonlinearity of higher-order terms or longer memory lengths. In this paper, by pruning away some negligible beating terms and adaptively picking out some of the dominant terms while discarding the trivial ones, we propose and experimentally demonstrate a sparse pruned-term-based nonlinear decision-feedback equalization (SPT-NDFE) scheme for the LED-based UWOC system with an inappreciable performance degradation as compared to systems without the pruning strategy. Meanwhile, by replacing the self/cross beating terms with the terms formed by the absolute operation of a sum of two input samples instead of the product operation terms, a sparse pruned-term-based absolute operation nonlinear decision-feedback equalization (SPT-ANDFE) scheme is also introduced to further reduce complexity. The experimental results show that the SPT-NDFE scheme exhibits comparable performance as compared to the conventional NDFE (nonlinear decision-feedback equalization) scheme with lower complexity (the nonlinear coefficients are reduced by 63.63% as compared to the conventional NDFE scheme). While the SPT-ANDFE scheme yields suboptimal performance with further reduced complexity at the expense of a slight performance degradation, the robustness of the proposed schemes in different turbidity waters is experimentally verified. The proposed channel equalization schemes with low complexity and high performance are promising for power/energy-sensitive UWOC systems.

10.
Opt Express ; 30(20): 36343-36357, 2022 Sep 26.
Article in English | MEDLINE | ID: mdl-36258564

ABSTRACT

To cope with the nonlinear distortions and the chromatic dispersion (CD) induced power fading in double-side band (DSB) intensity modulation and direct detection (IM/DD) transmission systems, high-performance Volterra nonlinear equalizers (VNLEs) including Volterra feed-forward equalizer (VFFE) and Volterra decision-feedback equalizer (VDFE) are widely applied. However, the conventional VNLEs have high computational complexity, especially for longer memory lengths. In this paper, based on sparse and weight-sharing strategies for significant kernel reduction, we propose four low-complexity NLEs including a sparse diagonally pruned VDFE (S-DP-VDFE), a sparse diagonally pruned absolute-term DFE (S-DP-ATDFE), a weight-sharing DP-VDFE (WS-DP-VDFE), and a weight-sharing DP-ATDFE (WS-DP-ATDFE), and present a comprehensive comparison among them in terms of computational complexity and bit error ratio (BER) performance in a C-band 100-Gbit/s PAM-4 transmission system over 60-km standard single-mode fiber (SSMF). The experimental results show that the proposed S-DP-VDFE and WS-DP-VDFE not only exhibit comparable performance with the conventional DP-VDFE but also reduce the complexity by 54.5% and 45.9%, respectively. While the proposed S-DP-ATDFE and WS-DP-ATDFE yield lower complexity at the expense of a slight performance degradation. Compared with the proposed S-DP-VDFE, S-DP-ATDFE, and WS-DP-VDFE, the proposed WS-DP-ATDFE with the lowest number of real-valued multiplications of 45 achieves up to 90.9%, 81.6%, and 95.8% complexity reduction, respectively, at the 7% hard-decision forward error correction (HD-FEC) BER limit of 3.8 × 10-3. The proposed low-complexity WS-DP-ATDFE shows great potential in low-cost and high-performance IM/DD optical transmission systems.

11.
Opt Lett ; 47(12): 3035-3038, 2022 Jun 15.
Article in English | MEDLINE | ID: mdl-35709043

ABSTRACT

A nonlinearity-aware signal transmission scheme based on a low-complexity 3rd-order diagonally pruned absolute-term nonlinear equalizer (NLE) with weight sharing (DP-AT-NLE-WS) and rate-adaptable probabilistically shaped 16-level pulse amplitude modulation (PS-PAM-16) signal is proposed and experimentally demonstrated for C-band net-300-Gbit/s/λ short-reach optical interconnects. By replacing the multiplication operation with the absolute operation and applying weight sharing to reduce the kernel redundancy, the computational complexity of the proposed 3rd-order DP-AT-NLE-WS is reduced by >40% compared with the 3rd-order DP-Volterra NLE (DP-VNLE), DP-AT-NLE, and DP-VNLE-WS, with the achieved normalized general mutual information (NGMI) above a threshold of 0.857. Employing a commercial 32-GHz Mach-Zehnder modulator (MZM) and a single digital-to-analog converter (DAC), we demonstrate the single-lane transmission of 100-GBaud PS-PAM-16 signal using DP-AT-NLE-WS in the C band at record 370-Gbit/s line rate and 300.4-Gbit/s net rate over 1-km standard single-mode fiber (SSMF), achieving 21.2% (15.5%) capacity improvement over 100 (105)-GBaud PAM-8 transmission. To the best of our knowledge, this is the first net-300-Gbit/s intensity modulation and direct detection (IM/DD) short-reach transmission in the C band using commercially available components.

12.
Opt Express ; 30(2): 2326-2337, 2022 Jan 17.
Article in English | MEDLINE | ID: mdl-35209375

ABSTRACT

In this paper, a wideband photomultiplier tube (PMT)-based underwater wireless optical communication (UWOC) system is proposed and a comprehensive experimental study of the proposed PMT-based UWOC system is conducted, in which the transmission distance, data rate, and attenuation length (AL) is pushed to 100.6 meters, 3 Gbps, and 6.62, respectively. The receiver sensitivity at 100.6-meter underwater transmission is as low as -40 dBm for the 1.5-Gbps on-off keying (OOK) modulation signal. To the best of our knowledge, this is the first Gbps-class UWOC experimental demonstration in >100-meter transmission that has ever been reported. To further minimize the complexity of channel equalization, a sparsity-aware equalizer with orthogonal matching pursuit is adopted to reduce the number of the filter coefficients by more than 50% while keeping slight performance penalty. Furthermore, the performance of the proposed PMT-based UWOC system in different turbidity waters is investigated, which shows the robustness of the proposed scheme. Thanks to the great sensitivity (approaching the quantum limit) and a relatively larger effective area, benefits of misalignment tolerance contributed by the PMT is verified through a proof-of-concept UWOC experiment.

13.
Opt Express ; 29(2): 783-796, 2021 Jan 18.
Article in English | MEDLINE | ID: mdl-33726307

ABSTRACT

In this paper, a low-complexity two-level chaotic encryption scheme is introduced and experimentally demonstrated to improve the physical layer security of a 450-nm laser underwater optical wireless communication (UOWC) system using discrete Fourier transform spread discrete multi-tone (DFT-S DMT) modulation. In the first encryption stage, the original bit stream is encrypted with a chaotic sequence based on a one-dimensional Logistic map. In the second encryption stage, the real and imaginary components of the DFT-S symbols are further encrypted with a pair of separate chaotic sequences, which are generated from a two-dimensional Logistic iterative chaotic map with infinite collapse (2D-LICM). The experimental results indicate that the encryption operation has no negative effect on the performance of the proposed UOWC system. For chaotic encryption, the DFT-S DMT gives a better performance than the DMT scheme under different water turbidities. 55-m/4.5-Gbps and 50-m/5-Gbps underwater transmissions are successfully demonstrated by the chaotic encrypted DFT-S DMT scheme. To the best of our knowledge, this is the first time to verify the feasibility of chaotic encryption in a high-speed UOWC system.

14.
Rev Esp Enferm Dig ; 113(6): 418-422, 2021 Jun.
Article in English | MEDLINE | ID: mdl-33233904

ABSTRACT

BACKGROUND AND AIM: Glasgow prognostic score is a systemic inflammatory-based score. The aim of this study was to determine whether the Glasgow prognostic score was a useful predictor of short-term outcomes in patients who undergo total proctocolectomy for ulcerative colitis. METHODS: eighty ulcerative colitis patients who underwent a total proctocolectomy with ileal pouch-anal anastomosis or permanent end ileostomy from June 2014 to March 2020 were retrospectively analyzed. Patients were divided into a lower Glasgow prognostic score group and a higher Glasgow prognostic score group. RESULTS: postoperative infectious complication occurred more frequently in the higher Glasgow prognostic score group (8.3 % vs 29.5 %, p = 0.018). According to the univariate and multivariate analysis, only a higher Glasgow prognostic score was associated with an increased risk of postoperative infectious complication (OR: 5.478, 95 % CI: 1.236-24.279). CONCLUSION: Glasgow prognostic score is a simple and useful indicator of postoperative infectious complications.


Subject(s)
Colitis, Ulcerative , Colonic Pouches , Proctocolectomy, Restorative , Colitis, Ulcerative/surgery , Humans , Ileostomy , Postoperative Complications/diagnosis , Postoperative Complications/epidemiology , Postoperative Complications/etiology , Proctocolectomy, Restorative/adverse effects , Prognosis , Retrospective Studies
15.
Eur J Cancer ; 120: 10-19, 2019 10.
Article in English | MEDLINE | ID: mdl-31446212

ABSTRACT

BACKGROUND: The role of epidermal growth factor receptor (EGFR) pathways in regulating telomerase is increasingly being recognised. We analysed the impact of rs2853669 single nucleotide polymorphism (SNP) on telomere parameters and its prognostic value for non-small cell lung cancer (NSCLC) with or without EGFR mutation. METHODS: The association of rs2853669 with telomerase reverse transcriptase (TERT) mRNA level and relative telomere length (RTL) was analysed using resected tumour samples from 250 NSCLC patients. We also investigated the patients' clinical outcomes with a median follow-up of 57 months (2-99 months). RESULTS: The rs2853669 T/C allele was significantly associated with lower TERT mRNA expression (versus C/C and versus T/T; p < 0.001 for both) and shorter RTL (versus C/C and versus T/T; p = 0.039 and 0.023) in patients without EGFR mutation. Such difference was not observed in their counterparts harbouring EGFR mutation. When considering the cohort as a whole, T/C allele was significantly associated with shortest overall survival compared with T/T or C/C allele (mean: 61.8, 80.9 and 88.7 months, plog-rank < 0.001) and disease-free survival (mean: 78.3, 87.9 and 91.5 months, plog-rank = 0.019). Stratification analyses showed that the negative prognostic effect of T/C on OS was constrained in patients without EGFR mutation. CONCLUSION: Our study revealed significant associations of a common SNP within TERT promoter region on telomere parameters and survival in NSCLC patients without EGFR mutation. The result may help providing instruction for therapeutic interventions targeting telomerase and evidence for investigation of TERT-EGFR interacting mechanism in telomere biology.


Subject(s)
Carcinoma, Non-Small-Cell Lung/genetics , Mutation , Polymorphism, Single Nucleotide , Promoter Regions, Genetic , Telomerase/genetics , Telomere Homeostasis/genetics , Biomarkers, Tumor/genetics , Carcinoma, Non-Small-Cell Lung/pathology , Carcinoma, Non-Small-Cell Lung/surgery , ErbB Receptors/genetics , Female , Follow-Up Studies , Gene Expression Regulation, Neoplastic , Humans , Lung Neoplasms/genetics , Lung Neoplasms/pathology , Lung Neoplasms/surgery , Male , Middle Aged , Prognosis , Retrospective Studies , Survival Rate
16.
Opt Lett ; 44(3): 558-561, 2019 Feb 01.
Article in English | MEDLINE | ID: mdl-30702678

ABSTRACT

Probabilistic constellation shaping (PCS) is utilized to approach the channel capacity limit in discrete multitone (DMT) transmission for underwater optical wireless communication (UOWC) system. A fixed quadrature amplitude modulation (QAM) format with various probabilistic distributions is individually allocated for different subcarriers to obtain achievable maximum channel capacity in accordance with the pre-estimated signal-to-noise ratio. By using a 450-nm directly modulated laser diode (LD) with an available modulation bandwidth of ∼2.75 GHz, DMT with PCS technique is experimentally realized with a net data rate of 18.09 Gbit/s over 5 m, 17.21 Gbit/s over 25 m, and 12.62 Gbit/s over 35 m underwater transmission, giving substantial capacity improvement of 32.22%, 30.03%, and 27.55%, respectively, in comparison with the widely used regular QAM formats in DMT with bit-power loading scheme. The figure of merit of the UOWC system in terms of entropy, generalized mutual information (GMI), and normalized GMI are also presented. To the best of our knowledge, this is the first time to employ PCS-QAM-DMT in a UOWC system, and it is also the highest data rate ever reported for a single LD in UOWC.

17.
J Am Chem Soc ; 140(42): 13913-13920, 2018 10 24.
Article in English | MEDLINE | ID: mdl-30252465

ABSTRACT

Cinchona alkaloid-derived chiral catalysts represent one of the most widely applied classes of organocatalysts, which have been successfully utilized in the promotion of a wide variety of asymmetric reactions. Cinchona alkaloids exist in nature as pseudoenantiomers, which allow cinchona alkaloid-catalyzed reactions to provide high enantioselectivities and yields toward both enantiomers of interest in many reactions. On the other hand, the subtle structural difference between pseudoenantiomeric cinchona alkaloids could also lead to uneven efficiency that severely limits the applicability of some cinchona alkaloid-catalyzed reactions. We describe here the elucidation of the origin of and the consequent development of novel modified cinchona alkaloids to address such a problem in asymmetric imine umpolung reactions by cinchonium salts.


Subject(s)
Cinchona Alkaloids/chemistry , Catalysis , Imines/chemistry , Models, Molecular , Salts/chemistry , Stereoisomerism
18.
Proc Natl Acad Sci U S A ; 115(8): 1730-1735, 2018 02 20.
Article in English | MEDLINE | ID: mdl-29432161

ABSTRACT

This paper describes the mechanistic insight-guided development of a catalyst system, employing a phenolic proton donor catalyst in addition to a cinchonium-derived phase-transfer catalyst, to control the chemoselectivity of two distinct intermediates, thereby enabling the desired asymmetric tandem conjugate addition-protonation pathway to dominate over a number of side-reaction pathways to provide a synthetic approach for the direct generation of optically active amines bearing two nonadjacent stereocenters.


Subject(s)
Amines/chemistry , Catalysis , Imines/chemistry , Molecular Structure , Phenol/chemistry , Stereoisomerism
19.
Opt Express ; 26(26): 34060-34069, 2018 Dec 24.
Article in English | MEDLINE | ID: mdl-30650835

ABSTRACT

In this paper, we experimentally demonstrate a 450-nm laser underwater wireless optical transmission system by using adaptive bit-power loading discrete multi-tone (DMT) and Volterra series based post nonlinear equalization. Post nonlinear equalization mitigates the nonlinear impairment of the UWOC system. By incorporating post nonlinear equalization with a 3rd-order diagonal plane kernel, the received signal-to-noise ratio (SNR) can be improved by ~2 dB compared with a linear equalization method. The measured transmission capacity of the UWOC system is 16.6 Gbps over 5 m, 13.2 Gbps over 35 m, and 6.6 Gbps over 55 m tap water channel, with bit error rates (BERs) below the standard hard-decision forward error correction (HD-FEC) limit of 3.8 × 10-3. The used electrical signal bandwidth is 2.75 GHz, corresponding to electrical spectrum efficiency of ∼6 bit/s/Hz. The distance-datarate product reaches 462 Gbps*m at 35 m tap water transmission. To the best of our knowledge, both the data rate and distance-data rate product are the largest reported for single laser diode.

20.
Ann Thorac Surg ; 103(6): 1788-1794, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28366461

ABSTRACT

BACKGROUND: This study was performed to evaluate the effectiveness of sublobar resection for the treatment of pulmonary aspergilloma compared with lobectomy. METHODS: Patients with pulmonary aspergilloma who underwent lobectomy or sublobar resection in our department between March 2007 and December 2015 were retrospectively reviewed. Data were collected for patient demographic characteristics, medical history, preoperative investigations, perioperative findings, postoperative conditions, and recurrence status. Propensity-matched comparative analyses were performed to adjust for potential differences of patients' baseline characteristics between the groups. RESULTS: A total of 96 patients underwent lobectomy, 46 patients underwent attempted sublobar resection. The median follow-up time is 53 months. No recurrence was found in either group. Three patients (3.1%) in the lobectomy group required reoperation for bleeding. The patients who underwent sublobar resection had less underlying lung disease (p = 0.031), smaller lesions (p = 0.033), and were more likely to have been treated with video-assisted thoracic surgery (p < 0.001). These differences were eliminated by propensity score matching (46 pairs were successfully matched). Comparative analyses in matched groups demonstrate that there was no marked difference in the volume and duration of chest drainage or the length of postoperative hospital stay. However, the patients with sublobar resection had shorter operation time (p = 0.004), less blood loss (p = 0.042), and less postoperative complication (p = 0.048). CONCLUSIONS: Sublobar resection performed for small simple pulmonary aspergilloma and selected complex pulmonary aspergilloma has a low recurrence rate and confers perioperative advantages compared with lobectomy.


Subject(s)
Pneumonectomy/methods , Pulmonary Aspergillosis/surgery , Adult , Aged , Female , Follow-Up Studies , Humans , Lung/diagnostic imaging , Lung/surgery , Male , Middle Aged , Propensity Score , Radiography , Recurrence , Reoperation , Retrospective Studies , Young Adult
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