A phenol-based compartmental ligand as a potential chemosensor for zinc(ii) cations

An "end-off"-type compartmental Lewis base, 2,6-bis(2-hydroxybenzyl-2-hydroxyethylamino)methyl-4-methylphenol (L), was synthesized as a potential chemosensor for Zn2+ ions. L coordinates two Zn2+ cations in methanol-water solution, forming a dinuclear complex whose formulation was confirmed by ESI-MS spectroscopy and Job's plot. The fluorescence of L is remarkably enhanced by Zn2+ as compared with K+, Ca2+, Mg2+, Cu2+, Pb2+, Mn2+, Fe3+, Fe2+, Co2+, Cd2+ and Ni2+ ions. The fluorescence enhancement is attributed to the complexation of Zn2+ with L, which interrupts the photoinduced electron transfer process and rigidifies the molecular skeleton of L. The fluorescence of L is greatly dependent on the acidity and polarity of the solvents. This compound may be used as a probe to sense Zn2+ ion in polar protic solvents after proper modification

Exploiting wireless received signal strength indicators to detect evil-twin attacks in smart homes

Evil-twin is becoming a common attack in Smart Home environments where an attacker can set up a fake AP to compromise the security of the connected devices. To identify the fake APs, The current approaches of detecting Evil-twin attacks all rely on information such as SSIDs, the MAC address of the genuine AP or network traffic patterns. However, such information can be faked by the attacker, often leading to low detection rates and weak protection. This paper presents a novel evil-twin attack detection method based on the received signal strength indicator (RSSI). Our key insight is that the location of the genuine AP rarely moves in a home environment and as a result the RSSI of the genuine AP is relatively stable. Our approach considers the RSSI as a fingerprint of APs and uses the fingerprint of the genuine AP to identify fake ones. We provide two schemes to detect a fake AP in two different scenarios where the genuine AP can be located at either a single or multiple locations in the property, by exploiting the multipath effect of the WIFI signal. As a departure from prior work, our approach does not rely on any professional measurement devices. Experimental results show that our approach can successfully detect 90% of the fake APs, at the cost of an one-off, modest connection delay

DRET:a system for detecting evil-twin attacks in smart homes

Evil-twin is one of most commonly attacks in the WIFI environments, with which an attacker can steal sensitive information by cloning a fake AP in Smart Homes. The current approaches of detecting Evil-twin AP uses some identities/fingerprints of legitimated APs to identify rouge APs. Prior work in the area uses information like SSIDs, MAC addresses, and network traffics to detect bogus APs. However, such information can be easily intimated by the attacker, leading to low detection rates. This paper introduces a novel Evil-Twin AP detection method based on received signal strength indicator (RSSI). Our approach exploits the fact that the AP location is relatively stable in Smart Homes, which is to great extent to meet the requirement of the detection factor not easy to imitate as previous refer. We employ two detection strategies: a single position detection and a multi-positioned detection methods. Our approach exploits the multipath effect of WIFI signals to translate the problem of attack detection into AP positioning detection. Compared to classical detection methods, our approach can perform detection without relying on professional devices. Experimental results show that the single position detection approach achieves 20 seconds’ reduction of delay time with an accuracy of 98%, whereas the multi-positioned detection approach achieves 90% correct

Drift Evaluation of a Quadrotor Unmanned Aerial Vehicle (UAV) Sprayer: Effect of Liquid Pressure and Wind Speed on Drift Potential Based on Wind Tunnel Test

Background: Unmanned Aerial Vehicles (UAVs) applied to agricultural plant protection is widely used, and the field of operation is expanding due to their high efficiency and pesticide application reduction. However, the work on pesticide drift lags behind the development of the UAV spraying device. Methods: We compared the spray drift potential at four liquid pressures of 2, 3, 4, and 5 bar ejected from the hydraulic nozzles mounted on a UAV test platform exposed to different wind speeds of 2, 4, and 6 m/s produced by a wind tunnel. The combination of the wind tunnel and the UAV test platform was used to obtain strict test conditions. The droplet size distribution under spray drift pressures was measured by a laser diffraction instrument. Results: Increasing the pressure leads to smaller droplet volume diameters and produced fine droplets of less than 100 µm. The deposition in the drift area was elevated at most of the sampling locations by setting higher pressure and faster wind speed. The deposition ratios were all higher than the flow ratios under three wind speeds after the adjustment of pressures. For most samples within a short drift distance (2–8 m), the drift with the rotor motor off was more than an order of magnitude higher than that with the rotor motor on at a pressure of 3 bar. Conclusions: In this study, the wind speed and liquid pressure all had a significant effect on the UAV spray drift, and the rotor wind significantly inhibited a large number of droplets from drifting further

NSOM/QD-Based Visualization of GM1 Serving as Platforms for TCR/CD3 Mediated T-Cell Activation

Direct molecular imaging of nanoscale relationship between T-cell receptor complexes (TCR/CD3) and gangliosidosis GM1 before and after T-cell activation has not been reported. In this study, we made use of our expertise of near-field scanning optical microscopy(NSOM)/immune-labeling quantum dots- (QD-)based dual-color imaging system to visualize nanoscale profiles for distribution and organization of TCR/CD3, GM1, as well as their nanospatial relationship and their correlation with PKCθ signaling cascade during T-cell activation. Interestingly, after anti-CD3/anti-CD28 Ab co-stimulation, both TCR/CD3 and GM1 were clustered to form nanodomains; moreover, all of TCR/CD3 nanodomains were colocalized with GM1 nanodomains, indicating that the formation of GM1 nanodomains was greatly correlated with TCR/CD3 mediated signaling. Specially, while T-cells were pretreated with PKCθ signaling inhibitor rottlerin to suppress IL-2 cytokine production, no visible TCR/CD3 nanodomains appeared while a lot of GM1 nanodomains were still observed. However, while T-cells are pretreated with PKCαβ signaling inhibitor GÖ6976 to suppress calcium-dependent manner, all of TCR/CD3 nanodomains were still colocalized with GM1 nanodomains. These findings possibly support the notion that the formation of GM1 nanodomains indeed serves as platforms for the recruitment of TCR/CD3 nanodomains, and TCR/CD3 nanodomains are required for PKCθ signaling cascades and T-cell activatio

Transient Global Amnesia following Neural and Cardiac Angiography May Be Related to Ischemia

Introduction. Transient global amnesia (TGA) following angiography is rare, and the pathogenesis has not been illustrated clearly till now. The aim of this research is to explore the pathogenesis of TGA following angiography by analyzing our data and reviewing the literature. Methods. We retrospectively studied 20836 cases with angiography in our hospital between 2007 and 2015 and found 9 cases with TGA following angiography. The data of these 9 cases were analyzed. Results. We found all 9 cases with TGA following neural angiography (5 in 4360) or cardiac angiography (4 in 8817) and no case with TGA following peripheral angiography (0 in 7659). Statistical difference was found when comparing the neural and cardiac angiography group with peripheral group (p=0.022). Two cases with TGA were confirmed with small acute infarctions in hippocampus after angiography. This might be related to the microemboli which were rushed into vertebral artery following blood flow during neural angiography or cardiac angiography. There was no statistical difference when comparing the different approaches for angiography (p=0.82) and different contrast agents (p=0.619). Conclusion. Based on the positive findings of imaging study and our analysis, we speculate that ischemia in the medial temporal lobe with the involvement of the hippocampus might be an important reason of TGA following angiography

Microstructure and tensile properties of AISI 321 stainless steel with aluminizing and annealing treatment

In the present work, the tensile properties and microstructure of pack cementation preparing aluminized AISI 321 stainless steel with subsequent annealing treatment was investigated. The results reveal that the coatings of aluminized AISI 321 stainless steel are mainly composed of outermost Al2O3 layer, Fe-Al compound intermediate layer and Fe(Al,Cr) solid solution diffusion layer. The cross shape precipitate (NiAl) and strip precipitate (Ni3Al) are observed in Fe(Al,Cr) layer. After annealing, no new phase in aluminized coating is detected, meanwhile, the thickness of the aluminized coatings is increased and the porosity of Fe-Al layer is increased as well. In addition, the size of NiAl precipitates is decreased. The strength and plasticity of stainless steel are degraded by aluminizing treatment. However, after annealing, the aluminized steel exhibits a lower strength but a higher ductility. The crack initiation region of both aluminized steel with or without annealing treatment comprise coarse columnar grains and cleavage planes with river patterns. The fracture model of aluminized steel is cleavage fracture, while a mixed of intergranular and transgranular fracture is observed in aluminized annealed steel

Influence of the Downwash Wind Field of Plant Protection UAV on Droplet Deposition Distribution Characteristics at Different Flight Heights

The aerial spraying of pesticides by plant protection unmanned aerial vehicles (UAV) is a process in which the spray droplet deposition on target sites occurs under the influence of the downwash wind field. The downwash wind field is the most important factor affecting droplet deposition distribution characteristics in an aerial spray. To understand the mechanism of the downwash wind field, spray tests were conducted at different flight heights by using a DJI UAV, and the downwash wind field in the three-dimensional direction (X-directional wind, Y-crosswind, and Z-vertical wind) was measured by using a wind speed measurement system for UAV. Combined with the droplet deposition of aerial spray, the distribution characteristics of the downwash wind field and the influence of the downwash wind field on droplet deposition were studied. The results showed that it had obvious differences in the distribution of the downwash wind field for UAV at different flight heights. As the flight height increases, the downwash wind field in X-direction and Z-direction showed a strong to weak trend, while the downwash wind field in Y-direction showed an opposite trend. In addition, it was found that the downwash wind field in Y-direction and Z-direction both have a significant influence on droplet deposition. With the increase of flight height, the change of the downwash wind field led to a gradual decrease in droplet deposition in the effective spray area, and droplets deposited more uniformly. For the DJI T16 plant protection UAV in this test, the optimal flight height was 2.0 m, and the downwash wind field had a better improvement effect on droplet deposition. Therefore, in order to make full use of the downwash wind field of UAV, the appropriate flight height should be selected to improve droplet deposition of liquid pesticide and achieve a better control effect for crop disease and pests when UAV is used for aerial spray operations in the field. This study revealed the influence mechanism of the downwash wind field on droplet deposition of aerial spray, and proposed appropriate operation parameters from the perspective of practical operation. It was expected to provide data support for improving the operation quality of aerial spraying and the formulation of field operation specifications