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In the present work phenyl phosphine-protected Au9 nanoclusters were deposited onto (3-mercaptopropyl) trimethoxysilane (MPTMS) modified and unmodified mesoporous screen printed TiO2. The removal of the cluster ligands by annealing was applied to enhance the interaction between Au cluster cores and semiconductor surfaces in the creation of efficient photocatalytic systems. The heat treatment could lead to undesired agglomeration of Au clusters, affecting their unique properties as size specific clusters. To address this challenge, the semiconductor surfaces were modified by MPTMS. Characterization techniques confirm the effectiveness of the modification processes, and XPS demonstrates that S functionalized MTiO2 is more efficient than MTiO2 in increasing Au9 NCs adsorption by a factor of 10 and preventing Au cluster agglomeration even after annealing. Overall, this work contributes valuable insights into photocatalytic systems through controlled modification of semiconductor surfaces and Au nanocluster deposition. [ABSTRACT FROM AUTHOR]

With increasing use of infrared imaging in medical diagnostics, military and civilian surveillance, and navigation of autonomous vehicles, there is a need for low‐cost alternatives to traditional materials used in infrared optics such as germanium. Sulfur‐rich copolymers hold promise, as they are made from low‐cost feedstocks and have a high refractive index. In this report, cyclopentadiene is copolymerized with sulfur to provide a plastic with the highest long‐wave infrared transparency reported to date for this class of materials. Diverse lens architectures are accessible through melt casting or reactive injection molding. The featured copolymer is black, which enabled its use as an infrared‐transparent blind for protection of thermal imaging equipment and clandestine surveillance. These findings portend expanded use of sulfur copolymers in infrared optics. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.forsciint.2009.12.048 Byline: Andrew Camilleri (a), Martin R. Johnston (b), Michael Brennan (c), Sean Davis (d), David G.E. Caldicott (e) Keywords: Designer drugs; Analogue; 4-Methylmethcathinone; [alpha]-Phthalimidopropiophenone; N-Ethylcathinone; 2-Fluoromethamphetamine Abstract: In August 2007, four capsules containing white powders, said to have originated from an Israel-based Internet company 'Neorganics', were anonymously delivered to the Royal Adelaide Hospital, South Australia. The capsules were analysed and the active components were identified including 4-methylmethcathinone, 2-fluoromethamphetamine, [alpha]-phthalimidopropiophenone and N-ethylcathinone, all of which were unlisted within South Australian controlled substance regulations. We examined the relevant scientific literature surrounding these chemicals and present both GCMS and NMR data for 4-methylmethcathinone and [alpha]-phthalimidopropiophenone, which have previously received little attention. We also present the vapour- and condensed-phase infrared spectra (IR) of 4-methylmethcathinone as these have also not been reported in the literature previously. We discuss the issues surrounding whether these chemicals can be classified as controlled substance analogues and the likely impact this could have on prosecutions of individuals distributing these products. Author Affiliation: (a) Forensic Science SA, 21 Divett Place, Adelaide, Australia (b) School of Chemistry, Physics and Earth Sciences, Flinders University, Adelaide, Australia (c) RaveSafe, Queensland, Australia (d) Queensland Health Forensic and Scientific Services (QHFSS), 39 Kessels Rd, Brisbane, Queensland, Australia (e) Emergency Department, Royal Adelaide Hospital, Adelaide, Australia Article History: Received 6 October 2009; Revised 11 December 2009; Accepted 11 December 2009

The group of P2P precursors including α‐phenylacetoacetonitrile (APAAN), α‐phenylacetoamide (APAA) and methyl α‐acetylphenylacetate (MAPA) has become increasingly popular in Europe and other parts of the world in the last decade. Previous investigations have reported the use of APAAN in the synthesis of amphetamine and methamphetamine and identified a range of characteristic impurities. This research has expanded upon the current literature by investigating the use of MAPA in the synthesis of methamphetamine. In this study methamphetamine was synthesized via three common clandestine methods: the Leuckart synthesis and two reductive amination methods. We report the identification of seven impurities, four of which are methyl ester equivalents of impurities previously reported for the detection of APAAN. These are methyl 2‐phenylbut‐2‐enoate, methyl 2‐phenyl‐3‐hydroxybutanoate, methyl 3‐(methylamino)‐2‐phenylbut‐2‐enoate and methyl 3‐(methylamino)‐2‐phenylbutanoate. The other impurities identified are ethyl ester compounds formed via transesterification of the methyl ester due to the reaction solvent. This susceptibility for transesterification suggests that identification of the pre‐precursor used may not always be straightforward and may be dependent on the reaction conditions employed. Of the impurities reported, methyl 3‐(methylamino)‐2‐phenylbutanoate was deemed to be a potentially reliable impurity for detection of the use of MAPA; however, it is expected that lower levels of characteristic impurities may be detected in methamphetamine synthesized from MAPA than that from APAAN. [ABSTRACT FROM AUTHOR]

The article discusses a new approach to the synthesis of mixed-metal ligand-bridged nuclear complexes. The technique to form rigidly linked [ML (sub)2-(rigid spacer)-M'L (sub)2] compounds is described.

Single pulse, solid-state 29Si nuclear magnetic resonance (NMR) spectroscopy offers an additional method of characterisation of opal-A and opal-CT through spin-lattice (T1) relaxometry. Opal T1 relaxation is characterised by stretched exponential (Weibull) function represented by scale (speed of relaxation) and shape (form of the curve) parameters. Relaxation is at least an order of magnitude faster than for silica glass and quartz, with Q3 (silanol) usually faster than Q4 (fully substituted silicates). 95% relaxation (Q4) is achieved for some Australian seam opals after 50 s though other samples of opal-AG may take 4000 s, while some figures for opal-AN are over 10,000 s. Enhancement is probably mostly due to the presence of water/silanol though the presence of paramagnetic metal ions and molecular motion may also contribute. Shape factors for opal-AG (0.5) and opal-AN (0.7) are significantly different, consistent with varying water and silanol environments, possibly reflecting differences in formation conditions. Opal-CT samples show a trend of shape factors from 0.45 to 0.75 correlated to relaxation rate. Peak position, scale and shape parameter, and Q3 to Q4 ratios offer further differentiating feature to separate opal-AG and opal-AN from other forms of opaline silica. T1 relaxation measurement may have a role for provenance verification. In addition, definitively determined Q3/Q4 ratios are in the range 0.1 to 0.4 for opal-AG but considerably lower for opal-AN and opal-CT. [ABSTRACT FROM AUTHOR]

The rise in popularity of 'designer' precursor compounds for the synthesis of amphetamine‐type stimulants poses a significant challenge to law enforcement agencies. One such precursor is α‐phenylacetoacetonitrile (APAAN). APAAN emerged in Europe in 2010 and quickly became one of the most popular precursors for amphetamine synthesis in that region. Previous literature has identified four APAAN‐specific impurities formed in the synthesis of amphetamine; however, there is currently no research on the use of APAAN in the synthesis of methamphetamine, which is more likely to be employed in a non‐European market. In this study methamphetamine was synthesised via three common clandestine methods: the Leuckart method and two reductive amination methods. We report the identification of five new impurities and two previously identified impurities characteristic for the use of APAAN in the synthesis of methamphetamine. The newly identified impurities were characterised by MS and NMR and determined to be (E)‐3‐(methylamino)‐2‐phenylbut‐2‐enenitrile, 3‐(methylamino)‐2‐phenylbutanenitrile, 3‐methyl‐2,4‐diphenylpentanedinitrile, 2‐phenylbutyronitrile and 3‐hydroxy‐2‐phenylbutanenitrile. [ABSTRACT FROM AUTHOR]

Several porphyrin-catenanes are synthesized with the help of a self-assembling process, which is employed for the construction of (2)-catenanes and rotaxanes. Template-directed technique facilitates porphyrin insertion into (2)-catenanes, involvement of pi-pi interaction and hydrogen bonding formations. 1H NMR and FAB-MS are employed to characterize these compounds.

Coded power line communication (PLC) promises significant enhancement to the overall system performance over uncoded PLC systems. Yet, there is limited contribution on the theoretical analysis of coded OFDM-PLC systems. In this letter, the β β2 /1 and β1β/β 2 1 NB-Convolutional (Non Binary) codes have been examined in an extreme PLC environment and an investigation of the performance analysis in terms of bit error rate (BER) of coded orthogonal frequency-division multiplexing (OFDM) PLC systems has been carried out. This analysis is accomplished with consideration of the realistic PLC frequency multi-path channels and for variant values of the background to impulsive noise ratio Γ. Finally, a fair comparison of the BER performance of β β2 /1 NB-convolutional code with (1, 7/5)8 binary code is carried out. [ABSTRACT FROM AUTHOR]

The natural extract pyrethrum is an insecticidal oil derived from Tanacetum cinerariifolium that is commonly used in domestic and agricultural pesticides. The major constituents of the extract are the Pyrethrins, six esters that provide pyrethrum with its insecticidal properties. These Pyrethrins readily degrade through several environmental means and as such, there can be significant Pyrethrin losses during processing and long-term storage of pyrethrum-based insecticides. This work attempts to alleviate the effect of these degradative processes through the pursuit of stabilised Pyrethrins by chemically removing oxidatively sensitive functionality. Several reduced Pyrethrin analogues were produced and a method to convert the more sensitive Pyrethrins present in the pyrethrum concentrate into their respective more stable jasmolin counterparts, as a mixture with the over-reduced tetrahydropyrethrins, was developed. All other reduction processes abolished insecticidal activity against Lucilia cuprina larvae, whereas some isomerised analogues showed comparable potency with the individual natural pyrethrin esters. This work has revealed new insights into the structure–activity relationships in this unique class of insecticide. The reduction chemistry of the natural insecticides the pyrethrins was investigated and a method to convert them into their more stable jasmolin counterparts, as a mixture with the over-reduced tetrahydropyrethrins, was developed. Reduced products resulting from other chemical treatments lacked insecticidal activity, whereas some isomerised analogues showed comparable potency with the individual natural pyrethrin esters. [ABSTRACT FROM AUTHOR]

In this work, two efficient low complexity Antenna Selection (AS) algorithms are proposed for downlink Multi-User (MU) Massive Multiple-Input Multiple-Output (M-MIMO) systems with Matched Filter (MF) precoding. Both algorithms avoid vector multiplications during the iterative selection procedure to reduce complexity. Considering a system with $N$ antennas at the Base Station (BS) serving $K$ single-antenna users in the same time-frequency resources, the first algorithm divides the available antennas into $K$ groups, with the $k$ th group containing the $N/K$ antennas that have the maximum channel norms for the $k$ th user. Therefore, the Signal-to-Interference plus Noise Ratio (SINR) for the $k$ th user can be maximized by selecting a subset of the antennas from only the $k$ th group, thereby resulting in a search space reduction by a factor of $K$. The second algorithm is a semiblind interference rejection method that relies only on the signs of the interference terms, and at each iteration the antenna that rejects the maximum number of interference terms will be selected. The performance of our proposed methods is evaluated under perfect and imperfect Channel State Information (CSI) and compared with other low complexity AS schemes in terms of the achievable sum rate as well as the energy efficiency. In particular, when the Signal-to-Noise Ratio (SNR) is 10 dB, and for a system with 20 MHz of bandwidth, the proposed methods outperform the case where all the antennas are employed by 108.8 and 49.2 Mbps for the first and second proposed algorithms, respectively, given that the BS has perfect CSI knowledge and is equipped with 256 antennas, out of which 64 are selected to serve 8 single-antenna users. [ABSTRACT FROM AUTHOR]

The scope of a tandem conjugate addition-fluorination sequence performed on [alpha],[beta]-unsaturated esters by using the enantiopure lithium amide derived from (S)-N-benzyl-N-([alpha]-methylbenzyl)amine, and the electrophilic fluorinating agent N-fluorobenzenesulfonimide is examined. The method is used for preparing enantiopure [alpha]-fluoro-[[beta].sup.3]-amino acids and its utility is shown by the preparation of orthogonally protected (2S,3S)-[alpha]-fluoro-[[beta].sup.3]-lysine.

Ruthenium porphyrin functionalized single-walled carbon nanotube arrays are prepared by using coordination of the axial position of the metal ion onto 4-aminopyridine preassembled single-walled carbon nanotubes directly anchored to a silicon (100) surface (SWCNTs-Si). The results have suggested the ruthenium porphyrin modified electrodes are excellent candidates for molecular memory devices and light harvesting antennae.

The photovoltaic performance of several porphyrin-derivatized TiO2 films in regenerative photoelectrochemical cells is reported and compared to that in cells sensitized with a Ru(2,2'-bipyridyl-4, 4E-dicarboxylate)2(NCS)2(N3) dye. The N3 and TCPP dyed generated very high IPCE values compared to TDTBPP and ZnTDTBPP.

Recently identified as another form of cooperativity, interannular cooperativity is rarely observed in supramolecular chemistry. A tetra‐porphyrin molecular tweezer with two bis‐porphyrin binding sites is reported that exhibits archetypal interannular cooperativity when complexing 1,4‐diazabicyclo[2.2.2]octane (DABCO). The UV/Vis titration data best supported a 1:2 plus 2:2 plus 1:4 complexation model (host:guest), giving K12=6.32×1013 m−2, K22=3.04×1020 m−3, and K14=1.92×1016 m−4 in CHCl3. The NMR titration data supported the formation of two sandwich species, including tetra‐porphyrin⋅(DABCO)2 as the major species, although there are speciation differences between UV/Vis and NMR concentrations. Using statistical analysis, interannular cooperativity (γ) for tetra‐porphyrin⋅(DABCO)2 was determined to be negative (γ=2.41×10−3), which may be explained by DABCO being too small to be optimally bound simultaneously at both bis‐porphyrin binding sites. [ABSTRACT FROM AUTHOR]

Common oxidants used in chemical synthesis, including newly developed perruthenates, were evaluated in the context of understanding (and better appreciating) the sensitiveness and associated potential hazards of these reagents. Analysis using sealed cell differential scanning calorimetry (scDSC) facilitated Yoshida correlations, which were compared to impact sensitiveness and electrostatic discharge experiments (ESD), that enabled sensitiveness ranking. Methyltriphenylphoshonium perruthenate (MTP3, 8), isoamyltriphenylphosphonium perruthenate (ATP3, 7) and tetraphenylphosphonium perruthenate (TP3, 9) were found to be the most sensitive followed by 2‐iodoxybenzoic acid (IBX, 2) and benzoyl peroxide (BPO, 10), whereas the most benign were observed to be Oxone (12), manganese dioxide (MnO2, 13), and N‐bromosuccinimide (NBS, 17). [ABSTRACT FROM AUTHOR]

In this study, the performance analyses of the proposed turbo-coded orthogonal frequency division multiplexing (TCOFDM) are investigated over the power-line communication with lognormal channel gain based on derived effective complexvalued ratio distributions of the individual and combined noise samples at the zero-forcing equaliser output. The effective noise samples are derived in the presence of Nakagami-m background interference (BI) noise, Middleton class A impulsive noise (MCAIN) and their combination. The performance of the turbo code has been improved by computing the exact log-likelihood ratio using derived distributions, with the derivation of pairwise error probability and the average upper-bounds (AUBs). Moreover, the bit error rate (BER) degradation in the conventional T-COFDM system has been improved by deriving two clipping thresholds to combat the effect of the non-Gaussian noise, the first one has been derived in the presence of the impulsive noise only modelled by MCAIN model and the second one in the presence of combined Nakagami-m BI noise and MCAIN model. Monte Carlo simulations demonstrate the significant BER improvements of the proposed T-COFDM system compared to the improved conventional T-COFDM system with a close agreement to the AUBs derivation and analytical BER expression. [ABSTRACT FROM AUTHOR]

The use of wireless sensor networks for the purposes of border surveillance is a very hot topic at the moment. Such a network comprises large numbers of sensor nodes, sparsely located over a wide terrain, where the generated data are collected by multiple sinks located in secure head quarters. Due to its importance and criticality, data disseminated through such a network is vulnerable to outsider attacks. Therefore, a location-dependent key management scheme could be employed in order to provide security in terms of confidentiality and authenticity. This paper presents a novel location-dependent key management protocol for multiple sinks (LKMP-MS) whose design is based on a cell reporters scheme. In this protocol, the generated report regarding any event contains three security levels. In particular, the third level is implemented as an endorsement of the set of cell reporters allocated inside each cell. Accordingly, the generated event report is accepted by the sink. As a result, the adversary would have to compromise all endorsement nodes and all cell reporters selected by all sinks in order to generate a fake report inside a particular spot. This paper introduces a novel algorithm to implement the required revocation for both compromised nodes and cells in order to overcome the possible consequences of these entities being compromised. In order to evaluate and compare the LKMP-MS with recent schemes, a mathematical analysis is implemented and a simulation environment is built based on Contiki and MATLAB to validate the mathematical analyses. Finally, an extensive mathematical analysis is presented in order to calculate the optimum number of cell reporters that gives the highest level of security. [ABSTRACT FROM AUTHOR]

Algebraic-geometric (AG) codes have good error-correction capability due to their generally large code word length. However, their decoding remains complex, preventing practical applications. Addressing the challenge, this paper proposes two interpolation-based low-complexity Chase (LCC) decoding algorithms for one of the most popular AG codes-Hermitian codes. By choosing $\eta $ unreliable symbols and realizing them with the two most likely decisions, $2^\eta $ decoding test-vectors can be formulated. The first LCC algorithm performs interpolation for the common elements of the test-vectors, producing an intermediate outcome that will be shared by the uncommon element interpolation. It eliminates the redundant computation for decoding each test-vector, resulting in a low-complexity. With an interpolation multiplicity of one, the decoding is further facilitated by removing the requirement of pre-calculating the Hermitian curve’s corresponding coefficients. The second LCC algorithm is an adaptive variant of the first algorithm, where the number of test-vectors is determined by the reliability of received information. When the channel condition improves, it can reduce the complexity without compromising the decoding performance. Simulation results show that the both LCC algorithms outperform a number of existing algebraic decoding algorithms for Hermitian codes. Finally, our complexity analysis will reveal the proposals’ low-complexity feature. [ABSTRACT FROM PUBLISHER]

We discuss the design rules of an energy-efficient wireless wiretap channel in this paper. On the transmitter side, we investigate the optimal power control policy for secrecy rate maximization over wiretap channels with the bit-interleaved coded modulation scheme. On the receiver side, an energy harvesting algorithm is used to collect wireless signal energy without degrading the secrecy rate performance. These objectives are challenging as the closed-form solution to the mutual information of finite-alphabet input schemes remains unknown. In this paper, we derive a closed-form relationship between the secrecy rate and the signal-to-noise ratio (SNR) by transforming the SNR from the linear domain to the logarithm domain. The optimal power control policy (PCP) can be easily obtained by exhaustive search in a small interval, whereas the traditional search is performed over the entire SNR range. We also propose a sub-optimal PCP algorithm that significantly reduces the search complexity with only a minor performance loss. The optimal power splitting ratio is studied to save energy while achieving the target secrecy rate. We show that if the transmission power is too high, the receiver is unable to simultaneously harvest energy from the wireless signals and achieve the target secrecy rate. [ABSTRACT FROM PUBLISHER]

Spatial diversity is an effective method to mitigate the effects of fading, and when used in conjunction with low-density parity-check (LDPC) codes, it can achieve excellent error-correcting performance. Noise added at each branch of the diversity combiner is generally assumed to be additive white Gaussian noise, but there are many applications where the received signal is impaired by noise with a non-Gaussian distribution. In this paper, we derive the exact bit-error probability of different linear combining techniques on Rayleigh fading channels with impulsive noise, which is modeled using symmetric alpha-stable distributions. The relationship for the signal-to-noise ratios of these linear combiners is derived and then different non-linear detectors are presented. A detector based on the bi-parameter Cauchy–Gaussian mixture model is used and shows near-optimal performance with a significant reduction in complexity when compared with the optimal detector. Furthermore, the threshold signal-to-noise ratio of LDPC codes for different combining techniques on these channels is derived using density evolution and an estimation of the waterfall performance of LDPC codes is derived that reduces the gap between simulated and asymptotic performance. [ABSTRACT FROM AUTHOR]

New examples of porphyrin-containing reagents which function as 1,3-dipoles are analyzed and their value in rigid structure formation is determined. These porphyrin reagents have more potential for the synthesis of rigid diads as shown by the use of dienophilic porphyrin Diels-Alder reagents in synthesis. Various topologies of the chromophores can be obtained on the rigid alicylic framework of the diad product by employing ACE BLOCK assembly protocol.

The current study evaluated the potential of gold nanoparticles (AuNPs) for the delivery of Taxol to breast cancer cells (T47D) using an in vitro cell culture model. For this study, new loading approaches and novel chemical attachments were investigated. Five different gold nanoparticle-based complexes were used to determine their cytotoxicity towards T47D cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) viability assay. There was no significant decrease (P>0.05) in cell viability when T47D cells were treated with AuNPs that did not contain Taxol. However, cells were significantly killed by gold nanoparticles chemically conjugated to Taxol using three different approaches and one novel hybrid AuNP-Taxol nanoparticle, wherein no chemical bonds were involved. These Taxolloaded AuNPs were more effective at inducing cell death in vitro than a solution of free Taxol used to treat cells. This result demonstrated that Taxol could be released from the particles in the cell culture media for subsequent therapeutic action. Additionally, the experiments proved that the Taxol-loaded AuNPs were more toxic in a dose dependent manner than Taxol as a formulation for the treatment of breast cancer cells. The results of this study suggest that gold nanoparticles have potential for the efficient delivery of Taxol to breast cancer cells. This could provide a future solution as an alternative application method to overcome adverse side effects resulting from current high-dose treatment regimes. [ABSTRACT FROM AUTHOR]