Simultaneous Removal of Mn(II) and Nitrate by the Manganese-Oxidizing Bacterium Acinetobacter sp. SZ28 in Anaerobic Conditions

A novel bacterium, strain SZ28, identified as Acinetobacter sp., showed anaerobic denitrification ability using Mn(II) as the electron donor. Nitrate-nitrogen concentration decreased from nearly 16.52–mg L^?1 to 4.4–mg L^?1, without accumulation of nitrite as an intermediate, with a maximum of 0.063–mg NO₃^?-N L^?1 h^?1, reaching a peak of 0.085–mg NO₃^?-N L^?1 h^?1 in sodium acetate. The nitrate removal rate reached 0.067–mg NO₃^?-N L^?1 h^?1, 0.059–mg NO₃^?-N L^?1 h^?1, and 0.078 mg NO₃^?-N L^?1 h^?1 using Mn(II), S(II), and Fe(II) as electron donors, respectively. The optimum pH was 6.0, with a removal rate of 0.063–mg NO₃^?-N L^?1 h^?1     

Interaction of aromatic donor molecules with horseradish peroxidase: identification of the binding site and role of heme iron in the binding and activity

The interaction of aromatic substrates with horseradish peroxidase (HRP) was studied. Chemical modification of HRP was performed using diethylpyrocarbonate (DEPC) and for the first time the amino acid involved in binding with these substrates has been identified. The kinetic parameters for this interaction have been calculated and the role of heme iron in the oxidation of aromatic substrates by HRP has been discussed.     

Poly(1,2,3-benzotriazolyl)borate complexes with copper(I) and tri-organophosphane: an unprecedented κ-coordination of [H2B(btz)2] (btz=1,2,3-benzotriazolyl) in the X-ray crystal structure of [Cu(PBn3)2{(btz)BH2(btz)}]

New copper(I) triorganophosphane derivatives [Cu(PR₃)_n{H₂B(btz)₂}] and [Cu(PR₃)_n{HB(btz)₃}] (n=1 or 2) have been synthesized from the reaction of CuCl with PR₃ (R=phenyl, cyclohexyl, benzyl, o-, m-, or p-tolyl) or PMePh₂ and potassium dihydrobis(1,2,3-benzotriazolyl)borate K[H₂B(btz)₂] or potassium hydrotris(1,2,3-benzotriazolyl)borate K[HB(btz)₃]. The complexes obtained have been characterized by elemental analyses and FT-IR in the solid state and by NMR (¹H and ³¹P{¹H}) spectroscopy and conductivity measurements in solution. Solution data are consistent with partial dissociation of complexes occurring throughout breaking of the CuP bond. Single crystal structural characterizations were undertaken for two of them. The structurally authenticated arrays are, (a) [Cu(PBn₃)₂{(btz)BH₂(btz)}] with a three coordinate P₂Cu(N) coordination sphere and the donor [H₂B(btz)₂] coordinated throughout only one N3 atom. (b) [Cu(P-m-tolyl₃)_n{(btz)₃BH}] with a four coordinate PCuN₃ coordination sphere with the tris(benzotriazolyl)borate acting as tripodal donor throughout all its N2 atoms.     

The determination of the carbonic anhydrases activators in vitro effect of mixed donor crown ethers

Carbonic anhydrases (CAs) play an important function in various physiological and pathological processes. Therefore, many researchers work in this field in order to design and synthesize new drugs. Both inhibitors and activators of CAs, which are associated with the diagnosis and treatment of many diseases, are very important. The emergence of the use of CA activators in the treatment of Alzheimer has led many scholars to work on this issue. In this study, CA activators and inhibitors are determined. The crown ethers compounds ( 1 , 2 , 3 , 6 , 7 , 8 , and 9 ) were found to cause activation on enzyme activities of hCA I and II. The AC₅₀ values on hCA I and II of the compounds are in the range of 4.6565–374.979 μM. The 4 (IC₅₀; 1.301 and 3.215 μM for hCA I and II) and 5 (IC₅₀; 73.96 and 378.5 μM for hCA I and II) compounds were found to cause inhibition on enzyme activities of hCA I and II.     

Identification of target proteins of clinical immunity to Plasmodium falciparum in a region of low malaria transmission

The target molecules of antibodies against falciparum malaria remain largely unknown. Recently we have identified multiple proteins as targets of immunity against Plasmodium falciparum using African serum samples. To investigate whether potential targets of clinical immunity differ with transmission intensity, we assessed immune responses in residents of low malaria transmission region in Thailand. Malaria asymptomatic volunteers (Asy: n = 19) and symptomatic patients (Sym: n = 21) were enrolled into the study. Serum immunoreactivity to 186 wheat germ cell-free system (WGCFS)-synthesized recombinant P. falciparum asexual-blood stage proteins were determined by AlphaScreen, and subsequently compared between the study groups. Forty proteins were determined as immunoreactive with antibody responses to 35 proteins being higher in Asy group than in Sym group. Among the 35 proteins, antibodies to MSP3, MSPDBL1, RH2b, and MSP7 were significantly higher in Asy than Sym (unadjusted p < 0.005) suggesting these antigens may have a protective role in clinical malaria. MSP3 reactivity remained significantly different between Asy and Sym groups even after multiple comparison adjustments (adjusted p = 0.033). Interestingly, while our two preceding studies using African sera were conducted differently (e.g., cross-sectional vs. longitudinal design, observed clinical manifestation vs. functional activity), those studies similarly identified MSP3 and MSPDBL1 as potential targets of protective immunity. This study further provides a strong rationale for the application of WGCFS-based immunoprofiling to malaria vaccine candidate and biomarker discovery even in low or reduced malaria transmission settings.     

Bis[dihydrobis(1-pyrazolyl)borate]cadmium(II): a monomeric, severely distorted tetrahedral complex of cadmium(II)

The crystal structure of the complex [H₂B(pz)₂]₂Cd has been determined: orthorhombic, Pbca, A = 16.052(3), B = 13.935(3), C = 14.974(4) Å, V = 3349.4(13) ų, Z = 8, R(F) = 3.61%. It is the first structurally characterized non-porphyrin CdN₄ complex. It is monomeric in the solid state with a pseudotetrahedral geometry about the cadmium atom. The N---Cd---N angles are distorted by the approximate 93° bite angle of the ligand; the interligand N---Cd---N angles also are distorted, ranging from 106.9 to 131.7°. These distortions are the result of intermolecular packing forces and are facilitated by the spherical set of valence orbitals for Cd²⁺.     

Effects of bicarbonate and formate on the donor side of Photosystem 2

Sodium formate at concentration of 5–20 M suppresses electron flow on the donor side of Photosystem 2 (PS 2) in pea subchloroplast membranes (DT-20) which is revealed by inhibition of photoinduced changes of chlorophyll fluorescence yield related to photoreduction of Q_A and pheophytin (the primary and intermediary electron acceptors) and oxygen evolution and the increase of absorbance changes related to photooxidation of P₆₈₀, the primary electron donor, under continuous illumination. These activities are also inhibited upon partial depletion of bicarbonate in the medium and restored by the addition of 0.1–10 mM NaHCO₃. At concentrations higher than 20 M formate induces the known bicarbonate effect on the acceptor side of PS 2 which dominates at millimolar concentrations of the agent. In Tris-treated (Mn-depleted) DT-20 the restoration of electron flow with 0.2 M MnCl₂ (4 Mn atoms per one PS 2 reaction center) in the medium depleted of bicarbonate is efficient only after the addition of 5 mM NaHCO₃. The restoration in the presence of NaHCO₃ is accompanied by an increased functional binding of Mn²⁺ to PS 2 membranes which is confirmed by experiments on removal of added Mn²⁺ by either sedimentation or the addition of EDTA. Pre-illumination increases the Mn binding in the presence of bicarbonate. The data show that the bicarbonate effect on the donor side of PS 2 is related to a relatively low-affinity bound pool of bicarbonate. It is suggested that bicarbonate takes part in the formation of the Mn-cluster capable of water oxidation as an obligatory ligand or through modification of the binding site(s) of Mn.Abbreviations CCCP carbonyl cyanide-m-chlorophenylhydrazone - DCMU 3-(3,4-dichlorphenyl)-1,1-dimethylurea - DPC diphenylcarbazide - EDTA ethylenediaminetetraacetic acid - SiMo silicomolibdate     

Localization of sulfate reduction in planted and unplanted rice field soil

Rates of in situ sulfate reduction (SRR) in planted and unplanted rice fieldsoil were measured by the ³⁵SO^2– ₄-radiotracermethod using soil microcosms. The concentration of ³⁵SO^2– ₄ decreased exponentially with time.However, time course experiments indicated that incubation times of10–30 min were appropriate for measurements of SRRusing a single time point in routine assays. Unplanted microcosmsshowed high SRR of 177 nmol cm^-3 d^-1 inthe uppermost centimeter where average sulfate concentrations were<33 µM. Fine scaled measurements (1 mmresolution) localized highest SRR (<100 nmol cm^-3d^-1) at the oxic/anoxic interface at 2–5 mmdepth. In planted rice field soil, SRR of <310 nmolcm^-3 d^-1 were observed at 0–2cm depth. Sulfate reduction rates were determined at a millimeter-scalewith distance to a two dimensional root compartment. The SRR was highestat 0–1.5 mm distance to the root layer with rates up to500 nmol cm^-3 d^-1, indicating a highstimulation potential of the rice roots. SRR seemed to be mainlydependent on the in situ sulfate porewater concentrations. At thesoil surface of unplanted microcosms sulfate concentration decreasedfrom <150 µM to <10 µM within the first 8 mm of depth. In planted microcosmssulfate concentration varied from 87–99 µMsulfate at the 0–3 mm distance to the root layer to48–62 µM sulfate at a root distance>4 mm from the roots.The depth distribution of inorganic sulfur compounds was determinedfor planted and unplanted rice field soil. Sulfate, acid volatilesulfide (AVS) and chromium reducible sulfide (CRS) were up to 20 foldhigher in planted than in unplanted microcosms. CRS was the majorinsoluble sulfur fraction with concentrations >1.7µmol cm^-3. Organic sulfur accounted for25–46% of the total sulfurpresent (269 µg/g dw) in an unplanted microcosm.The biogeochemical role of sulfate reduction forshort-term accumulation of inorganic sulfur compounds(FeS, FeS_{_2} and S°) in rice soil wasdetermined in a time course experiment with incubationperiods of 5, 10, 20, 30 and 60 min. The relativedistribution of CRS and AVS formation showedlittle depth dependence, whereas the formation of³⁵S° seemed to be the highest in themore oxidized upper soil layers and near the root surface.AV³⁵S was the first major product of sulfatereduction after 20–30 min, whereas CR³⁵Swas formed, as AV³⁵S and ³⁵S°decreased, at longer incubation periods of >30 min.     

Structure Evolution of Oligomer Fused‐Ring Electron Acceptors toward High Efficiency of As‐Cast Polymer Solar Cells

The structure evolution of oligomer fused‐ring electron acceptors (FREAs) toward high efficiency of as‐cast polymer solar cells (PSCs) is reported. First, a series of FREAs (IC‐(1‐3)IDT‐IC) based on indacenodithiophene (IDT) oligomers as cores are designed and synthesized, effects of IDT number (1–3) on their basic optical and electronic properties are investigated, and more importantly, the relationship between device performance of as‐cast PSCs and donor(D)/acceptor(A) matching (absorption, energy level, morphology, and charge transport) of IC‐(1‐3)IDT‐IC acceptors and two representative polymer donors, PTB7‐Th and PDBT‐T1 is surveyed. Then, the most promising D/A system (PDBT‐T1/IC‐1IDT‐IC) with the best D/A harmony among the six D/A combinations, which yields a power conversion efficiency (PCE) of 7.39%, is found. Finally, changing the side‐chains in IC‐1IDT‐IC from alkylphenyl to alkyl enhances the PCE from 7.39% to 9.20%.