On-chip Diamond MEMS Magnetic Sensing through Multifunctionalized Magnetostrictive Thin Film

Electrically integrable, high-sensitivity, and high-reliability magnetic sensors are not yet realized at high temperatures (500 °C). In this study, an integrated on-chip single-crystal diamond (SCD) micro-electromechanical system (MEMS) magnetic transducer is demonstrated by coupling SCD with a large magnetostrictive FeGa film. The FeGa film is multifunctionalized to actuate the resonator, self-sense the external magnetic field, and electrically readout the resonance signal. The on-chip SCD MEMS transducer shows a high sensitivity of 3.2 Hz mT⁻¹ from room temperature to 500 °C and a low noise level of 9.45 nT Hz^−1/2 up to 300 °C. The minimum fluctuation of the resonance frequency is 1.9 × 10⁻⁶ at room temperature and 2.3 × 10⁻⁶ at 300 °C. An SCD MEMS resonator array with parallel electric readout is subsequently achieved, thus providing a basis for the development of magnetic image sensors. The present study facilitates the development of highly integrated on-chip MEMS resonator transducers with high performance and high thermal stability.     

Photothermal Heating-Assisted Superior Antibacterial and Antibiofilm Activity of High-Entropy-Alloy Nanoparticles

Antibacterial elements and non-contact heating abilities have been proven effective for antibacterial and antibiofilm activities, but it remains a challenge to integrate both within one material. Herein, assisted by the high-entropy effect, FeNiTiCrMnCu_x high-entropy alloy nanoparticles (HEA-NPs) with excellent photothermal heating properties for boosting antibacterial and antibiofilm performances are synthesized. Benefitting from the synergetic effect of copper ions released and thermal damage by the HEA-NPs, more reactive oxygen species (ROS) are generated, leading to the rupture of the cell membranes and the eradication of the biofilms. As a result, the antibiofilm efficiency (400 µg mL⁻¹) of the mostly optimized FeNiTiCrMnCu_1.0 HEA-NPs in the marine nutrient medium, which is the worst-case scenario for the antimicrobial material, can be improved from 81% to 97.4% under 30 min solar irradiation (1 sun). The present study demonstrates a new strategy for effectively treating marine microorganisms that cause biofouling and microbial corrosion using HEA-NPs with photothermal heating characteristics as an antibacterial auxiliary.     

Aggregate manganese Schiff base moieties by terephthalate or acetate: dinuclear manganese and trinuclear mixed metal Mn2/Na complexes

A reaction system consisting of terephthalic acid, NaOH, inorganic Mn(II) or Mn(III) salt, and salicylidene alkylimine resulted in dinuclear manganese complexes (salpn)(2)Mn(2)(mu-phth)(CH(3)OH)(2) (1, salpn = N,N'-1,3-propylene-bis(salicylideneiminato); phth = terephthalate dianion), (salen)(2)Mn(2)(mu-phth)(CH(3)OH)(2) (2, salen = N,N'-ethylene-bis(salicylideneiminato)), (salen)(2)Mn(2)(mu-phth)(CH(3)OH)(H(2)O) (3), and (salen)(2)Mn(2)(mu-phth) (4), while the absence of NaOH in the reaction led to a mononuclear Mn complex (salph)Mn(CH(3)OH)(NO(3)) (5, salph = N,N'-1,2-phenylene-bis(salicylideneiminato)). In addition, a trinuclear mixed metal complex H[Mn(2)Na(salpn)(2)(mu-OAc)(2)(H(2)O)(2)](OAc)(2) (6) was obtained from the reaction system by using maleic acid instead of terephthalic acid. Five-coordinate Mn ions were found in 4 giving rise to an intermolecular interaction and constructing a one-dimensional linear structure. Antiferromagnetic exchange interactions were observed for 1-3, and a total ferromagnetic exchange of 4 was considered to stem from intermolecular magnetic coupling. (1)H NMR signals of phenolate ring and alkylene (or phenylene) backbone of the diamine are similar to those reported in the literature, and the phth protons are at -2.3 to -10.1 ppm. Studies on structure, bond valence sum analysis, and magnetic properties indicate the oxidation states of the Mn ions in 6 to be +3, which are also indicated by ESR spectra in dual mode. Ferromagnetic exchange interaction between the Mn(III) sites was observed with J = 1.74 cm(-1). A quasireversible redox pair at -0.29V/-0.12V has been assigned to the redox of Mn(2)(III)/Mn(III)Mn(II), implying the intactness of the complex backbone in solution.     

Observations on the swelling characteristics of the zwitterionic hydrogel of poly(1-3-sulfopropyl)-2-vinyl-pyridinium-betaine hydrogel

Samples of poly[1-(3-sulfopropyl)-2-vinyl-pyridinium-betaine] (PSPV) have been synthesized to high conversion by free radical polymerization in aqueous solution of the zwitterionic monomer SPV with several concentrations of the crosslinker N,N′-methylene-bis-acrylamide (MBA). The densities of the resultant xerogels increased regularly with the content of MBA. Hydrogels obtained by swelling them in water and aqueous KSCN solution were examined by gravimetric and dimensional analysis. The water contents increased with decreasing content of MBA, the value of 92.7 wt% at the lowest MBA content being higher than that for other zwitterionic hydrogels. Enhanced swelling occurred in 1 M aq. KSCN at each MBA content, the total swelling being 98.1 wt% at the lowest crosslinker content. Swelling increased with increasing temperature. An approximate procedure to formulating swelling equilibrium in term of the volume fraction of water in hydrogel, in conjunction with the van’t Hoff equation, yields a small positive value for the enthalpy of swelling. This is compared with values derived similarly for other hydrogels.     

Sorption of 241Am by Aspergillus nigerspore and hyphae

Biosorption of ²⁴¹Am by a fungus A. niger, including the spore and hyphae, was investigated. The preliminary results showed that the adsorption of ²⁴¹Am by the microorganism was efficient. More than 96% of the total ²⁴¹Am could be removed from ²⁴¹Am solutions of 5.6-111 MBq/l (C _o) by spore and hyphaeof A. niger, with adsorbed ²⁴¹Am metal (Q) of 7.2-142.4 MBq/g biomass, and 5.2-106.5 MBq/g, respectively. The biosorption equilibrium was achieved within 1 hour and the optimum pH range was pH 1-3. No obvious effects on ²⁴¹Am adsorption by the fungus were observed at 10-45 °C, or in solutions containing Au³⁺ or Ag⁺, even 2000 times above the ²⁴¹Am concentration. The ²⁴¹Am biosorption by the fungus obeys the Freundlich adsorption equation. There was no significant difference between the adsorption behavior of A. nigerspore and hyphae. This revised version was published online in July 2006 with corrections to the Cover Date.     

New 2D graphical representation of DNA sequences

We consider a 2D graphical representations of DNA sequences, which avoids loss of information associated with crossing and overlapping of the corresponding curve. We outline an approach, which is based on the construction of a three-component vector whose components are the normalized leading eigenvalues of the L/L matrices associated with DNA. The examination of similarities/dissimilarities among the coding sequences of the first exon of beta-globin gene of different species illustrates the utility of the approach.     

Biosorption of americium-241 by Saccharomyces cerevisiae

The biosorption of radionuclide ²⁴¹Am from solution by Saccharomyces cerevisiae (S. cerevisiae), and the effects of experimental conditions on the adsorption were investigated. The preliminary results showed thatS. cerevisiae is a very efficient biosorbent. An average of more than 99% of the total ²⁴¹Am could be removed by S. cerevisiae of 2.1 g/l (dry weight) from ²⁴¹Am solutions of 17.54–4386.0 mg/l (2.22 MBq/l–555 MBq/l) with adsorption capacities of 7.45–1880.0 mg/g biomass (dry weight) (0.94 MBq/g–237.9 MBq/g). The adsorption equilibrium was achieved within 1 hour and the optimum pH ranged 1–3. No significant differences on ²⁴¹Am adsorption were observed at 10–45 °C, or in solutions containing Au³⁺ or Ag⁺, even 2000 times above ²⁴¹Am concentration. The relationship between concentrations and adsorption capacities of ²⁴¹Am indicated the biosorption process should be described by the Freundlich adsorption isotherm.     

A novel support with artificially created recognition for the selective removal of proteins and for affinity chromatography

Summary Acrylamide and N,N-methylenebisacrylamide were copolymerized in the presence of a protein to form a gel which was pressed through a sieve. The gel particles obtained were packed into a chromatographic tube. The experimental conditions for the polymerization are such that the pores of the gel particles are large enough to permit the protein to diffuse out of the particles, so that the entrapped protein can be removed from the bed by washing with an aqueous solution. However the interaction with the matrix is so strong that the protein can be desorbed only by a buffer containing 0.5 M sodium chloride or by a 10% solution of acetic acid containing 10% SDS. When a sample containing the protein present during the polymerization was applied to the column along with other proteins this protein was the only one adsorbed. The technique worked selectively with hemoglobin, cytochrome C and transferrin.     

Fe(II) in different macrocycles: electronic structures and properties

A theoretical comparative study of complexes of porphyrin (P), porphyrazine (Pz), phthalocyanine (Pc), porphycene (Pn), dibenzoporphycene (DBPn), and hemiporphyrazine (HPz) with iron (Fe) has been carried out using a density functional theory (DFT) method. The difference in the core size and shape of the macrocycle has a substantial effect on the electronic structure and properties of the overall system. The ground states of FeP and FePc were identified to be the 3A2g [(d(xy))2(d(z)2)2(d(pi))2] state, followed by 3E(g) [(d(xy))2(d(z)2)1(d(pi))3]. For FePz, however, the 3E(g)-3A2g energy gap of 0.02 eV may be too small to distinguish between the ground and excited states. When the symmetry of the macrocycle is reduced from D4h to D2h, the degeneracy of the d(pi) (d(xz), d(yz)) orbitals is removed, and the ground state becomes 3B2g [(d(xy))2(d(z)2)1(d(yz))2(d(xz))1] or 3B3g [...(d(yz))1(d(xz))2] for FePn, FeDBPn, and FeHPz. The calculations also show how the change of the macrocycle can influence the axial ligand coordination of pyridine (Py) and CO to the Fe(II) complexes. Finally, the electronic structures of the mono- and dipositive and -negative ions for all the unligated and ligated iron macrocycles were elucidated, which is important for understanding the redox properties of these compounds. The differences in the observed electrochemical (oxidation and reduction) properties between metal porphycenes (MPn) and metal porphyrins (MP) can be accounted for by the calculated results (orbital energy level diagrams, ionization potentials, and electron affinities).     

LiM2(NCN)Br3 (M = Sr,Eu): Synthesis and Crystal Structures of Solid‐State Carbodiimides with Empty Tetrahedral Metal Entities

Two solid‐state carbodiimide compounds, LiM₂(NCN)Br₃ (M = Sr, Eu), with characteristic empty tetrahedral M₄ entities have been synthesized using a flux route, and their structures were determined by single‐crystal X‐ray diffraction. The new phases LiSr₂(NCN)Br₃ and LiEu₂(NCN)Br₃ are isotypical with the corresponding iodides and crystallize in the cubic system (( , Z = 16) but with smaller unit cells (a = 14.641(1) Å for LiSr₂(NCN)Br₃ and 14.572(1) Å for LiEu₂(NCN)Br₃). The extended structures comprise two interpenetrating three‐dimensional networks: the first one is built from isolated M₄ tetrahedra capped by NCN^2? anions on their triangular faces while the second is made from vertex‐sharing LiBr₆ octahedra. The linear NCN^2? anions exhibit the symmetrical carbodiimide shape and serve as linkers between the tetrahedral entities.