Efficient conversion from spoof surface plasmon polaritons to radiation mode.

A direct conversion from spoof surface plasmon polaritons (SSPPs) to radiation mode is proposed. A modified parallel two-wire SSPP transmission line is the key to the conversion, which is composed of traditional unit cells with slots among them. Taking advantages of the slots, the phase velocity of electromagnetic waves is larger than that of light, leading to the radiation. Both simulated and measured results show that the radiation occurs from 7.6 to 11 GHz, and the radiation angle keeps nearly stable in the whole operating frequency band, which can be predicted by theoretical calculation. The average gain and efficiency is 6.41 dBi and around 90%, respectively. The simple structure with flexibly tunable operating frequency makes the proposed design promising in planar integrated communication systems.

Frequency controlled beam scanning characteristic realized using a compact slow wave transmission line.

To simplify the design of a beam scanning device, we present a simple and compact structure to realize the frequency scanning characteristic based on a hybrid waveguide consisting of a spoof surface plasmon polariton (SSPP) transmission line and half-mode substrate integrated waveguide (HMSIW). Additionally, the radiation characteristic is implemented using periodically modulated slots. The scanning angle range covers backward to forward directions without an open stop band at the broadside. The results from both simulations and measurements show that the total scanning angle reaches 117° for a frequency range of 9-11.4 GHz. Owing to the inherent features of the HMSIW and the unique design of the SSPP transmission line, the entire structure is only 139.2mm×15mm in size. Moreover, the average gain is approximately 6.5 dBi. Overall, the compact size and good performance ensure that the proposed design is favorable for planar integrated communication systems.

Interleukin-41: a novel serum marker for the diagnosis of alpha-fetoprotein-negative hepatocellular carcinoma.

Background: For the lack of effective serum markers for hepatocellular carcinoma(HCC) diagnosis, it is difficult to detect liver cancer and identify its recurrence early. Methods: Databases were used to analyze the genes potentially associated with alpha-fetoprotein(AFP). ELISA assay was used to detect the serum IL-41 in HCC, liver metastases, hepatitis, and healthy people. Immunohistochemical staining was used to analyze the relative quantification of IL-41 in HCC and paracancer tissues. Various survival curves were plotted according to clinical pathological data and helped us draw the ROC curve of IL-41 diagnosis of HCC. Results: The serum expression of IL-41 was highest in AFP negative HCC patients and significantly higher than that in AFP positive HCC and metastatic cancer patients. There was a significant negative correlation between elevated serum IL-41 and AFP(<1500ng/ml). The clinicopathological features suggested that the serum IL-41 level was significantly correlated with capsule invasion, low differentiation and AFP. High serum expression of IL-41 suggests poorer survival and earlier recurrence after resection, and IL-41 upregulated in patients with early recurrence and death. The expression of IL-41 was higher in HCC tissues of patients with multiple tumors or microvascular invasion. The ROC curve showed that serum IL-41 had a sensitivity of 90.17 for HCC and a sensitivity of 96.63 for AFP-negative HCC, while the specificity was higher than 61%. Conclusion: IL-41 in serum and tissue suggests poor prognosis and postoperative recurrence in HCC patients and could be a new serum diagnostic marker for AFP negative patients.

A comprehensive survey on smart contract construction and execution: paradigms, tools, and systems.

Smart contracts are regarded as one of the most promising and appealing notions in blockchain technology. Their self-enforcing and event-driven features make some online activities possible without a trusted third party. Nevertheless, problems such as miscellaneous attacks, privacy leakage, and low processing rates prevent them from being widely applied. Various schemes and tools have been proposed to facilitate the construction and execution of secure smart contracts. However, a comprehensive survey for these proposals is absent, hindering new researchers and developers from a quick start. This paper surveys the literature and online resources on smart contract construction and execution over the period 2008-2020. We divide the studies into three categories: (1) design paradigms that give examples and patterns on contract construction, (2) design tools that facilitate the development of secure smart contracts, and (3) extensions and alternatives that improve the privacy or efficiency of the system. We start by grouping the relevant construction schemes into the first two categories. We then review the execution mechanisms in the last category and further divide the state-of-the-art solutions into three classes: private contracts with extra tools, off-chain channels, and extensions on core functionalities. Finally, we summarize several challenges and identify future research directions toward developing secure, privacy-preserving, and efficient smart contracts.

Simultaneous determination of palladium, platinum and rhodium by on-line column enrichment and HPLC with 5-(2,4-dihydroxyphenylazo)-rhodanine as pre-column derivatization reagent.

In this paper, a new method for the simultaneous determination of palladium, platinum and rhodium ions was developed using a rapid column high performance liquid chromatography equipped with on-line enrichment technique. The palladium, platinum and rhodium ions were pre-column derivatized with DHAR to form colored chelates. The Pb-DHAR, Pt-DHAR and Rh-DHAR chelates could be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column [ZORBAX Stable Bound, 4.6 x 10 mm, 1.8 microm] with a 0.05 mol L(-1) of phosphoric acid solution as mobile phase. After enrichment, and by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and traveling towards the analytical column. The separation of these chelates on the analytical column [ZORBAX Stable Bound, 4.6 x 50 mm, 1.8 microm] was satisfactory with 54% acetonitrile (containing 0.05 mol L(-1) of phosphoric acid and 0.1% of tritonX-100) as mobile phase. Palladium, platinum and rhodium were separated completely within 2 min. By on-line enrichment technique, the enrichment factor of 100 was achieved, and the detection limits (S/N = 3) of palladium, platinum and rhodium reaches 1.4 ng L(-1), 1.6 ng L(-1) and 2.0 ng L(-1), respectively. This method was applied to the determination of palladium, platinum and rhodium in water, urine and soil samples with good results.

[Study on solid phase extraction and spectrophotometric determination of uranium in water with 2-(2-quinolylazo)-5-dimthylaminophenol].

A new chromogenic reagent 2-(2-quinolylazo)-5-Dimthylaminophenol (QADMAP) was synthesized, and its structure was verified by elemental analysis, infrared spectrum, 1H nuclear magnetic resonance spectrum, mass spectrumand UV-spectrum. The color reaction of QADMAP with uranium was studied. In the presence of pH 7.8 buffer solution, when fluorin ion and TritonX-100 medium exist, QADMAP can react with uranium and fluorin to form a stable 1 : 1 : 1 stable complex [F- :QADMAP : U(VI)]. The molar absorptivity is 1.05 x 10(5) L x mol(-1) x cm(-1) at 590 nm. Beer's law is obeyed in range of 0-20 microg/10 mL. The uranium in samples can be enriched and separated by solid phase extraction with TBP resin cartridge. This method is applied to the determination of uranium in water sample. The relative standard deviations are 2.2%-3.6%, and the recoveries are 94%-105%.

Determination of transition metal ions in tobacco as their 2-(2-quinolinylazo)-5-dimethylaminophenol derivatives using reversed-phase liquid chromatography with UV-VIS detection.

This paper reports the utilization of solid-phase extraction and the reversed-phase high-performance liquid chromatography for the determination of six important transition metal ions: iron, cobalt, nickel, copper, zinc and manganese in tobacco with 2-(2-quinolinylazo)-5-dimethylaminophenol (QADMAP) as chelating reagent. Iron, cobalt, nickel, copper, zinc and manganese ions react with QADMAP to form colored chelates in the medium of acetic acid-sodium acetate buffer solution (pH 4.0). These chelates can be enriched by solid-phase extraction with Waters Sep-Pak-C18 cartridge, and eluted the retained chelates from cartridge with tetrahydrofuran. The chelates were separated on a Waters Nova-Pak-C18 column (150x3.9 mm, 5 microm) by gradient elution with methanol (containing 0.5% of acetic acid) and 0.05 mol/l pH 4.0 acetic acid-sodium acetate buffer solution as mobile phase at a flow-rate of 0.5 ml/min. The detection limits of iron, cobalt, nickel, copper, zinc and manganese are 10, 12, 8, 13, 17 and 22 ng/l, respectively. This method had been applied to the determination of iron, cobalt, nickel, copper, zinc and manganese in tobacco with good results.

Determination of lead, cadmium and mercury in microwave-digested foodstuffs by RP-HPLC with an on-line enrichment technique.

A new method for the simultaneous determination of lead, cadmium and mercury ions in microwave-digested foodstuffs by reversed-phase high-performance liquid chromatography combined with on-line enrichment technique has been developed. The foodstuff samples were digested by microwave digestion. The lead, cadmium and mercury ions can be precolumn derivatized with 5,10,15,20-tetrakis(3-aminophenyl)porphine (T3APP) to form color chelates; then, the Hg-T3APP, Cd-T3APP and Pb-T3APP chelates can be enriched and separated on a valve switching HPLC system combined with on-line enrichment technique. The linearity ranges are 0.01-120 microg/l for each metal ion. The detection limits (S/N = 3) of lead, cadmium and mercury are 1.2 ng/l, 0.5 ng/l and 0.8 ng/l, respectively. This method was applied to the determination of lead, cadmium and mercury in foodstuffs with good results.

Determination of nickel with 2-(2-quinolylazo)-5-diethylaminoaniline as a chromogenic reagent.

A sensitive, selective and rapid method for the determination of nickel based on a rapid reaction of nickel(II) with 2-(2-quinolylazo)-5-diethylaminoaniline (QADEAA) has been developed. In the presence of pH = 6.0 ammonia-ammonium chloride buffer solution and sodium dodecyl sulfonate (SDS) medium, QADEAA reacts with nickel to form a violet complex having a molar ratio of 1:2 (nickel to QADEAA). The molar absorptivity of the complex is 1.38 x 10(5) l mol(-1) cm(-1) at 595 nm. Beer's law is obeyed in the range of 0.01-0.4 microg/ml. This method had been applied to the determination of nickel with good results.

Solid phase extraction and spectrophotometric determination of silver with 2-(2-quinolylazo)-5-diethylaminophenol as chromogenic reagent.

A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP), was synthesized. A sensitive, selective and rapid method has been developed for the determination of microg/L level silver ion based on the rapid reaction of silver(l) with QADEAP and the solid phase extraction of the colored chelate with C18 cartridge. The QADEAP reacts with Ag(l) to form a violet chelate of a molar ratio 1:2 (silver to QADEAP) in pH 3.5-8.0. This chelate was prconcentrated by solid phase extraction with C18 cartridge. An enrichment factor of 100 was achieved. The molar absorptivity of the chelate is 1.30 x 10(5) L mol(-1) cm(-1) at 590 nm in measured solution. Beer's law is obeyed in the range of 0.01-0.6 microg/ml. The relative standard deviation for eleven replicate samples of 0.01 microg/ml is 1.15%. The detection limit is 0.02 microg/L in the original samples. This method was applied to the determination of microg/L level silver ion in water with good results.

Simultaneous determination of four heavy metal ions in tobacco and tobacco additive by online enrichment followed by RP-HPLC and microwave digestion.

A new method for the simultaneous determination of tin, lead, cadmium, and mercury in tobacco and tobacco additive by reversed-phase high-performance liquid chromatography combined with microwave digestion and an online enrichment technique is developed. The tin, lead, cadmium, and mercury ions are precolumn derivatized with tetra-(4-dimethylaminophenyl)-porphyrin (T(4)-DMAPP) to form color chelates. The Sn-T(4)-DMAPP, Hg-T(4)-DMAPP, Cd-T(4)-DMAPP, and Pb-T(4)-DMAPP chelates are absorbed onto the front of the enrichment column using a buffer solution of 0.05 mol/L pyrrolidine-acetic acid (pH = 10.0) as the mobile phase. After the concentration is finished (by switching the six-port switching valve) the retained chelates are back-flushed by the mobile phase and move to the analytical column. The chelate separation on the analytical column is satisfactory using gradient elution with methanol (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH = 10.0) and tetrahydrofuran (containing 0.05 mol/L pyrrolidine-acetic acid buffer salt, pH = 10.0). The linearity range is 0.01-120 micro g/L for each metal ion. The detection limits (S/N = 3) of tin, lead, cadmium, and mercury are 0.6, 0.8, 0.5, and 0.6 ng/L, respectively. This method is applied to the determination of tin, lead, cadmium, and mercury in tobacco and it's additive with good results.

Studies on the synthesis of 5-(p-aminobenzylidene)-rhodanine and its properties.

A new analytical reagent 5-(p-aminobenzylidene)-rhodanine (ABR) was synthesized. The acidic dissociation constant of ABR has been determined. The properties, the acid-base behavior of ABR and the reactions of ABR with metallic ions have been studied. The color reactions of the reagent with Pd(II), Au(III), Ag(I), Ru(III), Hg(II) and Cu(II) are studied in detail. The composition of Pd(II)-ABR, Au(III)-ABR and Ag(I)-ABR complexes were discussed.

[Study on solid phase extraction spectrophotometric determination of copper(II) with 2-(4-antipyrinylazo)-5-dimethylaminoaniline].

Based on the color reaction of 2-(4-Antipyrinylazo)-5-Dimethylaminoaniline (ADA) with copper (II) and the solid phase extraction of its colored complex with Waters Porapak(r) Sep-Park-C18 cartridge, a new method for the determination trace amount of copper(II) was studied. In the medium of Tween-80 and presence of pH = 4.5 buffer solution, ADA can react with copper (II) to form a stable 2:1 complex. The colored complex can extracted by Porapak(r) Sep-Park-C18 cartridge and eluted by ethanol contain 1% of acetic acid, then can be determined by spectrophotometer at 530 nm. Beer's law is obeyed in range of 0.05(1.0(g/ml. This method can be applied to the determination trace amount of copper in water with satisfactory results.

[Study on solid phase extraction and spectrophotometric determination of vanadium in environmental samples with 2-(2-quinolinylazo)-1,3-dihydroxidebenzene].

Based on the color reaction of 2-(2-quinolinylazo)-1,3-dihydroxidebenzene (QADHB) with vanadium (v) and the solid phase extraction of its colored complex with C18 cartridge, a new method for the determination of vanadium was studied. In the presence of CTMAB and citric acid-sodium hydroxide buffer solution (pH 3.5) medium. QADHB reacts with vanadium(II) to form a stable 2:1 complex. The colored complex was extracted by C18 cartridge and eluted the retained chelate from cartridge with ethanol (containing 2% of acetic acid), then can be determined by spectrophotometry at 552 nm. Beer's law is obeyed in range of 0-1.0 mg/l. This method can be applied to the determination of vanadium in environmental samples with good results.

[Study on the solid phase extraction spectrophotometric determination of mercury in water with 5-(2-hydroxy-4-sulfo-5-chlorophenol-1-azo)-thiorhodanine].

Based on the color reaction of mercurywith 5-(2-hydroxy-4-sulfo-5-chlorophenol-1-azo)-thiorhodanine (HSTC) and the solid phase extraction of the colored complex with C18 cartridge, a new method for the determinations microg x L(-1) level of mercury was studied. In the presence of pH 3.6 HAc-NaAc buffer solution. HSTC reacted with mercury (II) to form a stable 2:1 complex. This complex was enriched by solid phase extraction with C18 cartridge and the retained complex from cartridge was eluted with DMF. An enrichment factor of 80 was achieved. In the measured solution, the molar absorptivity was 6.24 x 10(4) L x moL(-1) x cm(-1) at 545 nm. Beer's law was obeyed in the range of 0-1.5 microg x mL(-1). This method was applied to the determination of mercury in water. The relative standard devitions were 1.8%-2.2% and the recoveries were 93%-106%. The results are satisfactory.

[Study on spectrophotometric determination of silver(I) with 2-(2-quinolinylazo)-1,5-dihydroxidebenzene].

The color reaction of silver(I) with 2-(2-quinolinylazo)-1,5-dihydroxidebenzene (QADHB) and the solid phase extraction of the colored chelate with Waters Sep-Park C18 cartridge were developed. In the presence of pH = 5.0 sodium citrate-sodium hydroxide buffer solution and sodium dodecyl sulfonate (SDS) medium, QADHB can reacts with silver to form a chelate of a molar ratio 1:2 (silver to QADHB). This chelate can be enriched by the solid phase extraction with Waters Sep-Park C18 cartridge. The retained chelate can be eluted from cartridge with ethanol. In ethanol medium, the molar absorptivity is 6.99 x 10(4) L x mol(-1) x cm(-1) at 550 nm. Beer's law is obeyed in the range of 0-1.2 microg x mL(-1). This method can be applied to the determination of silver in water with satisfactory results.

[Study on solid-phase-extraction spectrophotometric determination of silver with p-sulfobenzylidene-rhodanine].

The color reaction of silver with p-sulfobenzylidene-rhodanine (SBDR) was studied. Based on the color reaction of SBDR with silver (I) and the solid phase extraction of its colored complex with Waters Porapak Sep-Park-C18 cartridge, a new method for the determination of micro-amount of silver (I) was studied. In the presence of pH = 2.8 citric acid-sodium hydroxide buffer solution and Tween-80 medium, SBDR can react with silver (I) to form a stable 2:1 complex. The colored complex can be extracted by C18 cartridge and eluted by ethanol (containing 5% acetic acid), and then can be determined by spectrophotometry. The molar absorptivity is 7.53 x 10(4) L x mol(-1) x cm(-1) at 520 nm. Beer's law is obeyed in the range of 0-1.2 microg x (25 mL)(-1). This method can be applied to the determination of silver in water with satisfactory results.

Spectrophotometric determination of silver with 2-(2-quinolylazo)-5-diethylaminophenol as chromogenic reagent.

A new chromogenic reagent, 2-(2-quinolylazo)-5-diethylaminophenol (QADEAP) was synthesized. A highly sensitive, selective and rapid method for the determination of silver based on the rapid reaction of silver(I) with QADEAP has been developed. In the presence of citric acid-sodium hydroxide buffer solution (pH=5.0) and sodium dodecyl sulfonate (SDS) medium, QADEAP reacts with silver to form a violet complex of a molar ratio 1:2 (silver to QADEAP). The molar absorptivity of the complex is 1.33x10(5) L mol(-1) cm(-1)at 590 nm. Beer' s law is obeyed in the range of 0.01-0.6 micro g mL(-1). The relative standard deviations for eleven replicate samples of 0.2 microg mL(-1) is 1.38%. This method was applied to the determination of silver in water with satisfactory results.

Study on determination of iron, cobalt, nickel, copper, zinc and manganese in drinking water by solid-phase extraction and RP-HPLC with 2-(2-quinolinylazo)-5-diethylaminophenol as precolumn derivatizing reagent.

A new method for the determination of iron, cobalt, nickel, copper, zinc and manganese in drinking water by the reversed-phase high-performance liquid chromatography (RP-HPLC) with 2-(2-quinolinylazo)-5-diethylaminophenol (QADEAP) as precolumn derivatizing reagent was studied in this paper. The iron, cobalt, nickel, copper, zinc, and manganese ions react with QADEAP to form color chelates in the presence of cetyl trimethylammonium bromide (CTMAB) and acetic acid-sodium acetic buffer solution medium of pH 4.0. These chelates were enriched by solid-phase extraction with a Waters Nova-Pak C18 cartridge and eluted the retained chelates from the cartridge with tetrahydrofuran (THF). The enrichment factor of 100 was achieved. Then the chelates were separated on a Waters Nova-Pak C18 column (3.9 x 150 mm, 5 microm) by gradient elution with methanol (containing 0.2% of acetic acid and 0.1% of CTMAB) and 0.05 mol L(-1) acetic acid-sodium acetic buffer solution (containing 0.1% of CTMAB) (pH 4.0) as mobile phase at a flow rate of 0.5 ml min(-1), and monitored with a photodiode array detector from 450 approximately 700 nm. The detection limits (S/N = 3) of iron, cobalt, nickel, copper, zinc and manganese are 0.8, 1.1, 0.9, 1.1, 1.5 and 2.0 ng L(-1), respectively, in the original sample. This method can be applied to determination at the microg L(-1) level of iron, cobalt, nickel, copper, zinc and manganese in drinking water with good results.

Determination of trace lead, cadmium and mercury by on-line column enrichment followed by RP-HPLC as metal-tetra-(4-bromophenyl)-porphyrin chelates.

This paper reports the utilization of tetra-(4-bromophenyl)-porphyrin (T(4)BPP) as a chelating reagent using Waters Xterratrade mark RP(18) column for the on-line column enrichment and the separation of trace lead, cadmium and mercury ions by reversed-phase high-performance liquid chromatography (RP-HPLC) with photodiode array detector. When the Hg-T(4)BPP, Pb-T(4)BPP and Cd-T(4)BPP chelates were injected into the injector and sent to the enrichment column with 0.05 mol l(-1) of pH 10.0 pyrrolidine-phosphoric acid buffer solution (containing 10% of tetrahydrofuran (THF)) as mobile phase. The chelates were retained on the top of the enrichment column. After the enrichment is finished, by switching the valve of six-ports switching valve, the retained metal-T(4)BPP chelates will be eluted by mobile phase in reverse direction and will travel towards analytical column. With THF (containing 0.05 mol l(-1), pH 10.0 pyrrolidine-phosphoric acid buffer salt) and 0.05 mol l(-1), pH 10.0 pyrrolidine-phosphoric acid buffer solution (containinging 10% THF) gradient elution as mobile phase, the chelates separation on the analytical column was satisfactory. The linearity ranges are 0.01-120 mug l(-1) for each metal ion. The detection limits (S/N=3) of lead, cadmium and mercury are 1.0, 0.5 and 1.0 ng l(-1), respectively. This method can be applied to the determination (mug l(-1)) level of lead, cadmium and mercury in drinking water with satisfactory results.