Atomic and electronic structure of solids of Ge2Br2PN,Ge2I2PN,Sn2Cl2PN,Sn2Br2PN and Sn2I2PN inorganic double helices: a first principles study

We report the results of density functional theory calculations on the atomic and electronic structure of solids formed by assembling A₂B₂PN (A = Ge and Sn, B = Cl, Br, and I) inorganic double helices. The calculations have been performed using a generalized gradient approximation for the exchange–correlation functional and including van der Waals interactions. Our results show that the double helices crystallize in a monoclinic lattice with van der Waals type weak interactions between the double helices. In all cases except Ge₂Cl₂PN, the solids are stable with a binding energy between the double helices ranging from 0.06 eV per atom to 0.09 eV per atom and inter-double helices separation of more than 3.33 Å. All the solids are semiconducting. Further calculations have been done by using meta-GGA with a modified Becke–Johnson functional to obtain better band gaps, which are found to lie in the range of 0.91 eV to 1.49 eV. In the case of Ge₂Br₂PN the solid is a direct band gap semiconductor although the isolated double helix has an indirect band gap and it is suggested to be interesting for photovoltaic, and other optoelectronic applications. The charge transfer between the atoms has been studied using Bader charge analysis and the DDEC6 method in the CHARGEMOL program, which suggests charge transfer from the outer helix to the inner helix.

We report the results of density functional theory calculations on the atomic and electronic structure of solids formed by assembling A₂B₂PN (A = Ge and Sn, B = Cl, Br, and I) inorganic double helices.     

Shape-dependent close-edge 2D-MoS2 nanobelts

Atomic-thin MoS₂ materials have attracted increasing attention due to their potentials in numerous fields. However, in 2D-MoS₂ sheets, the edge region usually has unique features differing from the interior region, which has potential application in enhancing catalysts and shape-dependent 2D-nanodevices. However, fabricating it cost-effectively is still very difficult. Here, we present one universal method to obtain various shape-dependent closed-edge 2D-MoS₂ nanobelts only using one simple step, and width of the MoS₂ nanobelts (minimum of 270 nm) were adjustable. Our strategy opens a new fabrication route for closed-edge 2D-MoS₂ nanobelts, and in principle, this method is also suitable for other CVD-grown 2D materials.

A very simple mechanical peeling method to obtain various closed and shape-dependent MoS₂ edge nanobelt.     

Efficient and stable transduction of dopaminergic neurons in rat substantia nigra by rAAV 2/1, 2/2, 2/5, 2/6.2, 2/7, 2/8 and 2/9

Dysfunction of the nigrostriatal system is the major cause of Parkinson's disease (PD). This brain region is therefore an important target for gene delivery aiming at disease modeling and gene therapy. Recombinant adeno-associated viral (rAAV) vectors have been developed as efficient vehicles for gene transfer into the central nervous system. Recently, several serotypes have been described, with varying tropism for brain transduction. In light of the further development of a viral vector-mediated rat model for PD, we performed a comprehensive comparison of the transduction and tropism for dopaminergic neurons (DNs) in the adult Wistar rat substantia nigra (SN) of seven rAAV vector serotypes (rAAV 2/1, 2/2, 2/5, 2/6.2, 2/7, 2/8 and 2/9). All vectors were normalized by titer and volume, and stereotactically injected into the SN. Gene expression was assessed non-invasively and quantitatively in vivo by bioluminescence imaging at 2 and 5 weeks after injection, and was found to be stable over time. Immunohistochemistry at 6 weeks following injection revealed the most widespread enhanced green fluorescence protein expression and the highest number of positive nigral cells using rAAV 2/7, 2/9 and 2/1. The area transduced by rAAV 2/8 was smaller, but nevertheless almost equal numbers of nigral cells were targeted. Detailed confocal analysis revealed that serotype 2/7, 2/9, 2/1 and 2/8 transduced at least 70% of the DNs. In conclusion, these results show that various rAAV serotypes efficiently transduce nigral DNs, but significant differences in transgene expression pattern and level were observed.     

Interleukin-2 (IL-2) immunotherapy

Various forms of immunotherapy have been employed for the treatment of cancer patients during the past 5 years, with recombinant interleukin-2 (IL-2) having been widely used in these treatment regimes. The progress of IL-2 immunotherapy is discussed.     

乳腺癌环氧合酶-2和基质金属蛋白酶-2及其抑制因子的表达

目的 研究环氧合酶(COX)-2、基质金属蛋白酶(MMP)-2及其抑制因子(TIMP-2)在乳腺癌组织中的蛋白表达及其相互关系.方法 建立组织芯片平台,应用免疫组织化学S-P法检测127例乳腺癌组织COX-2、MMP-2和TIMP-2蛋白的表达情况.结果 乳腺癌COX-2、MMP-2和TIMP-2阳性率分别为81.1%(103/127)、96.9%(123/127)和60.6%(77/127);COX-2的表达与乳腺癌腋淋巴结转移和TNM分期均呈正相关(P<0.01,P<0.05),与孕激素受体表达呈负相关(P<0.05);MMP-2蛋白表达与COX-2表达呈显著正相关(r=0.290,P<0.01).结论 乳腺癌COX-2表达状况与肿瘤侵袭转移有密切关系,COX-2可能通过调控MMP-2表达来促进肿瘤侵袭转移.     

Multiple endocrine neoplasia type 2; MEN 2

Multiple endocrine neoplasia type 2 (MEN 2) is an inherited disorder as an autosomal dominant trait, characterized by medullary thyroid carcinoma (MTC). MEN 2 is classified with associated diseases into three subtypes: MEN 2A, MEN 2B and familial MTC. It has recently been shown to be associated with germline mutation in the RET proto-oncogene. Genetic testing allows easily for accurate diagnosis of presymptomatic gene carriers and surgical treatment at an early stage of the disease. In this review we delivered the classification, clinical feature, mutation in RET, mutation analysis, and management of MEN 2, and we discuss recent progress of research on the molecular basis and how genetic testing could be used for clinical management of affected patients or individuals in at-risk families.     

有丝分裂原激酶MEKK2调节白细胞介素2生成的研究

目的 探讨有丝分裂原激酶MEKK2对IL-2生成的影响。方法 用MEKK2和JNK激酶活性测定、荧光素酶报告基因检测、逆转录-聚合酶链反应及Western blot等方法，检测在PHA／抗CD28抗体刺激Jurkat细胞后MEKK2对IL-2转录和翻译的影响结果经PHA／抗CD28抗体刺激后，亲本Jurkat细胞AP1和IL-2启动子荧光素酶报告基因活性分别增加4倍和5倍。而MEKK2功能域灭活的Jurkat细胞AP1和IL-2启动子荧光素酶报告基因活性仅各增加1倍。经PHA／抗CD28抗体刺激后，亲本Jurkat细胞IL-2 mRNA的转录和IL-2蛋白的表达明显增加，而MEKK2功能域灭活的Jurkat细胞IL-2 mRNA的转录和IL-2蛋白的表达无明显增加。结论 MEKK2在IL-2的生成过程中起重要的调节作用，MEKK2可以作为药物作用的靶点，从而筛选有效药物抑制免疫反应，提高移植物抗宿主病和自身免疫性疾病治疗的疗效。     

Interleukin 2 activates extracellular signal-regulated protein kinase 2

Interleukin 2 (IL-2) stimulated activation of the 42-kD extracellular signal-regulated kinase 2 (Erk2) in murine IL-3-dependent cells, expressing either high or intermediate affinity IL-2 receptors. Activation was both rapid, occurring within 5 min of IL-2 addition, and prolonged, remaining elevated for 30 min. Activation of Erk2 appeared to be necessary for IL-2 stimulation of proliferation, as deletion of a region of the cytoplasmic domain of the IL-2 receptor beta chain, essential for IL-2 stimulation of proliferation, abolished Erk2 activation by IL-2. Furthermore, cells that had been deprived of cytokine for 24 h were then refractory to IL-2 stimulation of both Erk2 activity and proliferation. However, elevation of Erk2 activity was not sufficient to stimulate proliferation, as protein kinase C activation stimulated Erk2 activity but not DNA synthesis. Also, cells exposed to IL-2 in the presence of rapamycin showed full Erk2 activation but not DNA synthesis. These data suggest that IL-2 must stimulate both Erk2 activity and a further pathway(s) to trigger cell proliferation.     

The iron-H2O2-iodide cytotoxic system

A potent antimicrobial system is described which consists of ferrous sulfate (Fe2+), hydrogen peroxide (H2O2), and iodide in 0.02 M sodium acetate buffer pH 5.5. H2O2 could be replaced by the H2O2-generating system glucose + glucose oxidase. This system, unlike the myeloperoxidase-H2O2-halide system, was ineffective when iodide was replaced by bromide, chloride, or thyroxine, and was inhibited by EDTA, the hydroxyl radical scavengers mannitol and ethanol, and phosphate and lactate buffers at the same concentration and pH as the acetate buffer used. The acetate buffer, however, could be replaced by water. It is proposed that Fe2+ and H2O2 (Fenton's reagent) generate OH X (or a closely related substance), which interacts with iodide to form one or more toxic species.     

2-hydroxyestradiol is a prodrug of 2-methoxyestradiol

Previous in vivo studies indicate that 2-hydroxyestradiol (2OHE) attenuates cardiovascular and renal diseases. In vitro studies suggest that the biological effects of 2OHE are mediated by 2-methoxyestradiol (2MEOE) after methylation of 2OHE by catechol-O-methyltransferase (COMT). This study tested the hypothesis that in vivo 2OHE is a prodrug of 2MEOE. We administered to male rats i.v. boluses of either 2OHE or 2MEOE and measured plasma levels of 2OHE and 2MEOE by gas chromatography-mass spectrometry at various time points after drug administration. After administration of 2OHE, plasma levels of 2OHE declined extremely rapidly [t(1/2(1)) = 0.94 min and t(1/2(2)) = 10.2 min] becoming undetectable after 45 min. Concomitant with the disappearance of 2OHE, 2MEOE occurred and then declined [t(1/2(1)) = 7.9 min and t(1/2(2)) = 24.9 min]. The peak concentration and total exposure (area under the curve) for 2OHE were much lower than for 2MEOE. 2OHE had a much higher plasma clearance (CL) and volume of distribution (V(d)) compared with 2MEOE (2OHE: CL = 1215 ml min(-1) kg(-1) and V(d) = 17,875 ml/kg; 2MEOE: CL = 50 ml min(-1) kg(-1) and V(d) = 1760 ml/kg). After administration of 2MEOE, plasma levels of 2MEOE declined [t(1/2(1)) = 2.5 min and t(1/2(2)) = 20.2 min] with a plasma CL of 50 ml min(-1) kg(-1) and a V(d) of 1500 ml/kg. We could not detect 2OHE in plasma from rats receiving 2MEOE. We conclude that the conversion of 2OHE to 2MEOE is so efficient that in terms of 2MEOE exposure, administration of 2OHE is bioequivalent to administration of 2MEOE itself.     

K-doped CeO2–ZrO2 for CO2 thermochemical catalytic splitting

Green syngas production is a sustainable energy-development goal. Thermochemical H₂O/CO₂ splitting is a very promising sustainable technology allowing the production of H₂ and CO with only oxygen as the by-product. CeO₂–ZrO₂ systems are well known thermochemical splitting catalysts, since they combine stability at high temperature with rapid kinetics and redox cyclability. However, redox performances of these materials must be improved to allow their use in large scale plants. K-doped systems show good redox properties and repeatable performances. In this work, we studied the effect of potassium content on the performances of ceria–zirconia for CO₂ splitting. A kinetic model was developed to get insight into the nature of the catalytic sites. Fitting results confirmed the hypothesis about the existence of two types of redox sites in the investigated catalytic systems and their role at different K contents. Moreover, the model was used to predict the influence of key parameters, such as the process conditions.

K-doping enhances redox properties of ceria–zirconia towards thermochemical CO₂ splitting, showing promising performances at about 7 wt% of K.     

A novel red-emitting phosphor Mg2Y2Al2Si2O12:Ce3+/Mn2+ for blue chip-based white LEDs

Traditional white light-emitting diodes (LEDs) (blue chip + YAG:Ce³⁺ yellow phosphor) have the limitation of red deficiency, which limits their application in the illumination field. The single cation/anion substitution or co-doping of activators can increase the red component; however, the large energy loss is attributed to the ultra-long Stokes shift and energy transfer. This work attempts to utilize the short-distance Stokes shift and a small amount of energy transfer to increase the red component in two steps. First, based on a large number of previous research results, the Mg₂Y₂Al₂Si₂O₁₂:Ce³⁺ phosphor is selected. Second, additional enhancement of the red component in the emission spectrum was achieved by ion co-doping Mn²⁺ into Mg₂Y₂Al₂Si₂O₁₂:Ce³⁺. The emission peaks for samples Mg₂Y₂Al₂Si₂O₁₂:Ce³⁺,Mn²⁺ shift from 600 to 635 nm with increase in the concentration of Mn²⁺, and the emission spectra intensity of Mg_1.97Y_1.93Al₂Si₂O₁₂:0.07 Ce³⁺,0.03 Mn²⁺ anomalously increased by ∼37%, which was attributed to the increase in the distance between Ce³⁺ ions because of the doping of Mn²⁺ ions, and reduction in the concentration of defects in the crystal, resulting in the energy loss decreases of Ce³⁺. The emission peak of Mg_1.97Y_1.93Al₂Si₂O₁₂:0.07 Ce³⁺,0.03 Mn²⁺ shifts to 618 nm and the quantum efficiency was as high as 83.07%. Furthermore, this sample has high thermal stability and the emission intensity was still 80.14% at 120 °C. As such, it has great potential in the application of white LEDs.

The change of the emission spectra of Mg_1.93Y_2-xAl₂Si₂O₁₂:0.07Ce³⁺, xMn²⁺ originates from the change of the structure and the energy transfer between ions.     

Electronic structure and luminescence assets in white-light emitting Ca2V2O7, Sr2V2O7 and Ba2V2O7 pyro-vanadates: X-ray absorption spectroscopy investigations

Ca₂V₂O₇, Sr₂V₂O₇, and Ba₂V₂O₇ pyro-vanadates were synthesized using a modified chemical precipitation method and annealing. Detailed crystal structure, morphology, electronic structure and optical properties were investigated by XRD, UV-visible absorption, FTIR, Raman, FE-SEM, XANES, and photoluminescence spectroscopy. Rietveld refinement on the XRD patterns of Ca₂V₂O₇, Sr₂V₂O₇, and Ba₂V₂O₇ has confirmed the triclinic structure (space group; P$\bar{1}$(2)) of the pyro-vanadates. The band gap energy of Ca₂V₂O₇, Sr₂V₂O₇, and Ba₂V₂O₇ is estimated to be ∼2.67 eV, ∼2.97 eV and ∼3.09 eV, respectively. XANES spectra at the Ca L-edge, Sr K-edge and Ba L-edge have confirmed the Ca²⁺, Sr²⁺ and Ba²⁺ ions in the Ca₂V₂O₇, Sr₂V₂O₇ and Ba₂V₂O₇ compounds, respectively. V K-edge XANES spectra have strengthened the presence of sub-pentavalent V ions in all of the pyro-vanadates. O K-edge XANES spectra of Ca₂V₂O₇, Sr₂V₂O₇ and Ba₂V₂O₇ have shown dominating tetrahedral symmetry of the V ions which is also corroborated with the V K-edge XANES. Broad-band emission spectra, ranging from 400 nm to 700 nm, have been observed from the charge-transfer transitions of VO₄ tetrahedra. ³T₁ → ¹A₁ and ³T₂ → ¹A₁ transitions, from the VO₄ tetrahedra, have provided two distinct emission peaks from the compounds which exhibit a red-shift with the decreasing ionic-radii of alkali-earth metal ions. The mixed compounds, with equal weight proportions, have shown remarkable emission characteristics towards the realization of rare-earth element free white-light-emitting devices.

Chemically synthesized pyro-vanadates exhibit sub-pentavalent V ions and white-light emission via charge transfer transitions of VO₄ tetrahedra.     

Pharmacokinetics of the antiviral agent beta-D-2'-deoxy-2'-fluoro-2'-C-methylcytidine in rhesus monkeys

beta-D-2'-Deoxy-2'-fluoro-2'-C-methylcytidine (PSI-6130) is an effective inhibitor of hepatitis C virus (HCV) replication in vitro. The purpose of this study was to evaluate the single-dose pharmacokinetics of PSIota-6130 in rhesus monkeys following intravenous (i.v.) and oral administration. Noncompartmental analysis of the serum data obtained following oral and i.v. administration was performed. Pharmacokinetic studies with rhesus monkeys indicated slow and incomplete absorption with a mean absorption time (MAT) of 4.6 h and an oral bioavailability of 24.0% +/- 14.3% (mean +/- standard deviation), with comparable mean apparent half-lives following i.v. (4.54 +/- 3.98 h) and oral (5.64 +/- 1.13 h) administrations. The average percentages of the total dose recovered unchanged and in deaminated form in the urine were 32.9% +/- 12.6% and 18.9% +/- 6.6% (i.v.) and 6.0% +/- 3.9% and 3.9% +/- 1.0% (oral), respectively. The total bioavailability, taking into account the parent drug and its deaminated metabolite 2'-deoxy-2'-fluoro-2'-C-methyluridine (PSI-6206), was 64% +/- 26%. PSI-6130 was present in the cerebrospinal fluid after oral and i.v. dosing. However, no deamination of radiolabeled PSI-6130 was detected after 8 h of incubation in monkey and human whole blood. An N(4)-modified prodrug of PSI-6130 (PSI-6419) was orally administered to monkeys, but it failed to improve the oral bioavailability of PSI-6130. Further studies are warranted to improve the oral bioavailability and reduce the deamination of PSI-6130 in order to explore the potential of this drug for the treatment of HCV-infected individuals.