Traceless encryption approach for physical layer security in coherent optical communications system.

We proposed and numerically studied a traceless encryption approach for physical layer security in coherent optical communications system, the most attractive advantage of which is that it is hard for eavesdroppers to be aware that the transmission signal has been encrypted because the modulation formats of encrypted signal are still the regular ones, i.e. traceless encryption. In the proposed approach, the phase only or the combination of phase and amplitude dimensions can be used for encryption and decryption. Three simple encryption rules are designed and used to investigate the encryption security performance of the scheme, in which the QPSK signal can be encrypted to be as 8PSK, QPSK and 8QAM. The results show that three simple encryption rules can cause 37.5%, 25%, 62.5% of user signal binary codes to be misinterpreted by the eavesdroppers, respectively. When the modulation formats of encrypted signal and user signal are identical, the scheme can not only cover up the real information, but also have a potential application at misleading eavesdroppers. The impacts of the control light peak power at the receiver on the decryption performance are also analysed, the results indicate that the decryption performance of the scheme has a good tolerance to the peak power fluctuation of control light at the receiver.

1-(4-Amino-2-hydroxyphenyl)ethanone from Phomopsis liquidambari showed quorum sensing inhibitory activity against Pseudomonas aeruginosa.

Phomopsis liquidambari S47 is an endophytic fungus isolated from the leaves of Punica granatum. Here, we are the first to report a quorum sensing (QS) inhibitor 1-(4-amino-2-hydroxyphenyl)ethanone (AHE) isolated and identified from the metabolites of P. liquidambari S47. Exposure to AHE at sub-MIC concentrations notably suppressed the secretion of acyl-homoserine lactones and virulence factors in Pseudomonas aeruginosa PAO1. To investigate the metabolic variations of P. aeruginosa PAO1 exposed to AHE, magnetic resonance imaging-based metabolomic analysis was performed. AHE treatment created a disturbance in the QS system by suppressing the expressions of QS-related genes. The disturbed QS system resulted in the inhibited activity of antioxidant enzymes and thus enhanced oxidative stress. The vegetable infection assay showed that the virulence of P. aeroginosa PAO1 was attenuated which could be due to the impacts to the amino acid and nucleotide metabolism by enhanced oxidative stress. These findings suggest that AHE has a potential to become an antivirulence "agent" to tackle P. aeruginosa infection. KEY POINTS: • AHE treatment inhibited AHL secretion and virulence factors production. • AHE treatment aggravated oxidative stress and disturbed metabolism. • AHE suppressed QS-related gene expressions and reduced virulence of P. aeruginosa.

1-(4-Amino-2-Hydroxyphenyl)Ethenone Suppresses Agrobacterium tumefaciens Virulence and Metabolism.

The impact of 1-(4-amino-2-hydroxyphenyl)ethanone (AHPE) from the metabolites of endophytic fungus Phomopsis liquidambari on quorum sensing (QS) of Agrobacterium tumefaciens was evaluated for the first time in this study. Exposure to AHPE at concentrations ranging from 12.5 to 50 µg/mL, the ß-galactosidase activity, acyl-homoserine lactone level, swimming motility, chemotaxis, and flagella formation were significantly inhibited. qRT-PCR quantification combined with the docking analysis demonstrated that AHPE affected the QS system of A. tumefaciens by repressing the transcriptional levels of traI and traR rather than signal mimicry. 1H NMR-based metabolic analysis indicated that the metabolism of A. tumefaciens was notably disturbed with AHPE treatment. AHPE treatment also resulted in the enhanced oxidative stress in A. tumefaciens. The enhanced oxidative stress lead to the disorder of energy supply, protein synthesis, and nucleotide metabolism, and ultimately attenuated the pathogenicity of A. tumefaciens. Our study indicated that AHPE can serve as a potential pesticide to defend against A. tumefaciens.

Two new compounds from the roots of Pueraria peduncularis and their molluscicidal effects on Pomacea canaliculata.

Two oleanane-type triterpenoid saponins named pedunsaponin D (1) and pedunsaponin E (2) were isolated from the roots of Pueraria peduncularis. The structures of the new compounds were elucidated based on chemical and physicochemical evidence as follows: pedunsaponin D, 3-O-ß-glucopyranosyl-(1-3)-ß-glucuronopyranosyl-3ß,15α,23α-trihydroxy-11,13(18)-oleanadien-16-one (1); pedunsaponin E, 3-O-ß-glucopyranosyl-(1-2)-ß-glucopy ranosyl(1-2)[ß-glucopyranosyl(1-3)-ß-glucuronopyranosyl]-3ß-hydroxy-16-oxoolean-12-en-30-oic acid (2). The two compounds showed moderate molluscicidal activity.[Formula: see text].

Ultrahigh-speed all-optical half adder based on four-wave mixing in semiconductor optical amplifier.

A novel scheme for an ultrahigh-speed all-optical half adder based on four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) is proposed. This scheme is free of pattern effect, due to using the polarization-shift-keying (PolSK) modulation format. By numerical simulation, the output power level of logic "1" dependence on the operating conditions, such as two input signal powers, injection current, and input signal wavelength, are investigated in detail using the broad-band model of this all-optical half adder.