Electronic and optical properties of thiogermanate AgGaGeS4: theory and experiment.

The electronic and optical properties of an AgGaGeS4 crystal were studied by first-principles calculations, where the full-potential augmented plane-wave plus local orbital (APW+lo) method was used together with exchange-correlation pseudopotential described by PBE, PBE+U, and TB-mBJ+U approaches. To verify the correctness of the present theoretical calculations, we have measured for the AgGaGeS4 crystal the XPS valence-band spectrum and the X-ray emission bands representing the energy distribution of the electronic states with the biggest contributions in the valence-band region and compared them on a general energy scale with the theoretical results. Such a comparison indicates that, the calculations within the TB-mBJ+U approach reproduce the electron-band structure peculiarities (density of states - DOS) of the AgGaGeS4 crystal which are in fairly good agreement with the experimental data based on measurements of XPS and appropriate X-ray emission spectra. In particular, the DOS of the AgGaGeS4 crystal is characterized by the existence of well-separated peaks/features in the vicinity of -18.6 eV (Ga-d states) and around -12.5 eV and -7.5 eV, which are mainly composed by hybridized Ge(Ga)-s/p and S-p state. We gained good agreement between the experimental and theoretical data with respect to the main peculiarities of the energy distribution of the electronic S 3p, Ag 4d, Ga 4p and Ge 4p states, the main contributors to the valence band of AgGaGeS4. The bottom of the conduction band is mostly donated by unoccupied Ge-s states, with smaller contributions of unoccupied Ga-s, Ag-s and S-p states, too. The AgGaGeS4 crystal is almost transparent for visible light, but it strongly absorbs ultra-violet light where the significant polarization also occurs.

Layered post-transition-metal dichalcogenide SnGe2N4 as a promising photoelectric material: a DFT study.

First-principles calculations were performed to study a novel layered SnGe2N4 compound, which was found to be dynamically and thermally stable in the 2H phase, with the space group P6̄m2 and lattice constant a = 3.143 Å. Due to its hexagonal structure, SnGe2N4 exhibits isotropic mechanical properties on the x-y plane, where the Young's modulus is 335.49 N m-1 and the Poisson's ratio is 0.862. The layered 2H SnGe2N4 is a semiconductor with a direct band gap of 1.832 eV, allowing the absorption of infrared and visible light at a rate of about 104 cm-1. The DOS is characterized by multiple high peaks in the valence and conduction bands, making it possible for this semiconductor to absorb light in the ultraviolet region with an even higher rate of 105 cm-1. The band structure, with a strongly concave downward conduction band and rather flat valence band, leads to a high electron mobility of 1061.66 cm2 V-1 s-1, which is substantially greater than the hole mobility of 28.35 cm2 V-1 s-1. This difference in mobility is favorable for electron-hole separation. These advantages make layered 2H SnGe2N4 a very promising photoelectric material. Furthermore, the electronic structure of 2H SnGe2N4 responds well to strain and an external electric field due to the specificity of the p-d hybridization, which predominantly constructs the valence bands. As a result, strain and external electric fields can efficiently tune the band gap value of 2H SnGe2N4, where compressive strain widens the band gap, meanwhile tensile strain and external electric fields cause band gap reduction. In particular, the band gap is decreased by about 0.25 eV when the electric field strength increases by 0.1 V Å-1, making a semiconductor-metal transition possible for the layered SnGe2N4.

First-principles study on the structural properties of 2D MXene SnSiGeN4 and its electronic properties under the effects of strain and an external electric field.

The MXene SnSiGeN4 monolayer as a new member of the MoSi2N4 family was proposed for the first time, and its structural and electronic properties were explored by applying first-principles calculations with both PBE and hybrid HSE06 approaches. The layered hexagonal honeycomb structure of SnSiGeN4 was determined to be stable under dynamical effects or at room temperature of 300 K, with a rather high cohesive energy of 7.0 eV. The layered SnSiGeN4 has a Young's modulus of 365.699 N m-1 and a Poisson's ratio of 0.295. The HSE06 approach predicted an indirect band gap of around 2.4 eV for the layered SnSiGeN4. While the major donation from the N-p orbitals to the band structure makes SnSiGeN4's band gap close to those of similar 2D MXenes, the smaller distributions from the other orbitals of Sn, Si, and Ge slightly vary this band gap. The work functions of the GeN and SiN surfaces are 6.367 eV and 5.903 eV, respectively. The band gap of the layered SnSiGeN4 can be easily tuned by strain and an external electric field. A semiconductor-metal transition can occur at certain values of strain, and with an electric field higher than 5 V nm-1. The electron mobility of the layered SnSiGeN4 can reach up to 677.4 cm2 V-1 s-1, which is much higher than the hole mobility of about 52 cm2 V-1 s-1. The mentioned characteristics make the layered SnSiGeN4 a very promising material for use in electronic and photoelectronic devices, and for solar energy conversion.

A critical review on relationship of CeO2-based photocatalyst towards mechanistic degradation of organic pollutant.

Nanostructured photocatalysts commonly offered opportunities to solve issues scrutinized with the environmental challenges caused by steep population growth and rapid urbanization. This photocatalyst is a controllable characteristic, which can provide humans with a clean and sustainable ecosystem. Over the last decades, one of the current thriving research focuses on visible-light-driven CeO2-based photocatalysts due to their superior characteristics, including unique fluorite-type structure, rigid framework, and facile reducing oxidizing properties of cerium's tetravalent (Ce4+) and trivalent (Ce3+) valence states. Notwithstanding, owing to its inherent wide energy gap, the solar energy utilization efficiency is low, which limits its application in wastewater treatment. Numerous modifications of CeO2 have been employed to enhance photodegradation performances, such as metals and non-metals doping, adding support materials, and coupling with another semiconductor. Besides, all these doping will form a different heterojunction and show a different way of electron-hole migration. Compared to conventional heterojunction, advanced heterojunction types such as p-n heterojunction, Z-scheme, Schottky junction, and surface plasmon resonance effect exhibit superior performance for degradation owing to their excellent charge carrier separation, and the reaction occurs at a relatively higher redox potential. This review attends to providing deep insights on heterojunction mechanisms and the latest progress on photodegradation of various contaminants in wastewater using CeO2-based photocatalysts. Hence, making the CeO2 photocatalyst more foresee and promising to further development and research.

Total serum cortisol level is low in children with severe dengue shock syndrome.

Dengue shock syndrome (DSS) is a potentially critical and life-threatening concern, especially in children of tropical countries. The serum cortisol levels in severe DSS or later stages of DSS are limited references. We prospectively studied an association between of serum cortisol as well as interleukin levels and the severity of DSS in pediatric patients. A prospective cross-sectional study of 35 consecutive DSS cases (3 months to 16 years old) admitted to our institution from July 1, 2019, to June 30, 2020 was conducted. Serum cortisol, IL-6, and IL-10 were measured at T0 (shock recognition) and T12 (12 hours after T0); their values were presented as median and interquartile ranges (25%-75%). Severe DSS included patients with impalpable pulses or systolic blood pressure < 70 mmHg, recurrent shock, and prolonged shock. In contrast, non-severe DSS presented circulatory failure without any features of severe DSS. A total of 8 (22.8%) severe DSS patients expressed the cortisol (T0) significantly lower compared to the non-severe DSS group (7.3 µg/dl versus 14.3 µg/dl, p=0.008). In severe DSS, there was a minimal change in cortisol levels between T0 and T12 (7.3 µg/dl and 4.7 µg/dl p>0.05), whereas the decrease is significant in their counterparts (14.3 µg/dl to 5.6 µg/dl, p<0.005). Additionally, there were moderate correlations between IL-6 (T0), IL-10 (T0), IL-10 (T12) and total fluid requirement (Spearman's rho = 0.47, 0.4, and 0.36, respectively; p<0.05). Our study demonstrated that adrenal dysfunction was present in patients with severe and non-severe DSS, as noted by cortisol level at T12. In addition, IL-6 and IL-10 levels are correlated with the total fluid requirement, which is a marker of DSS severity. Further studies could reveal how adrenal dysfunction in pediatric patients with DSS can affect outcomes and the potential roles of interleukin levels in fluid management strategy.

Insect nicotinic acetylcholine receptor agonists as flea adulticides in small animals.

Fleas are significant ectoparasites of small animals. They can be a severe irritant to animals and serve as a vector for a number of infectious diseases. In this article, we discuss the pharmacological characteristics of four insect nicotinic acetylcholine receptor (nAChR) agonists used as flea adulticides in dogs and cats, which include three neonicotinoids (imidacloprid, nitenpyram, and dinotefuran) and a macrocyclic lactone (spinosad). Insect nAChR agonists are one of the most important classes of insecticides, which are used to control sucking insects on both plants and animals. These novel compounds provide a new approach for practitioners to safely and effectively eliminate adult fleas.

Current controversies in colon and rectal cancer.

Colon and rectal cancer is one of the leading causes of cancer death worldwide. Several areas of uncertainty remain in the screening and treatment of this disease, even though significant advances have already led to decreased rates of incidence and mortality over the last several decades. This review addresses some of the current controversies in screening for and the treatment of colorectal cancer, including specifically looking at issues related to screening modalities, local versus radical resections, protocols for adjuvant therapy and the treatment of stage IV disease.

Thrombolysis in recurrent lacunar stroke: a case example.

BACKGROUND AND PURPOSE: We report a case of intravenous thrombolysis in a patient with early recurrent stroke. A 62-year-old man recovered nearly completely after a lacunar infarct of the left putamen. He suffered stroke recurrence 7 days later due to a new infarct in the left internal capsule. Intravenous alteplase 0.9 mg/kg was administered 40 min after the symptom onset resulting in significant neurologic improvement. CONCLUSION: Intravenous thrombolysis may be safe for early recurrent lacunar stroke in patients with relatively small risk of hemorrhage.

Plasma vasopressin concentrations in healthy foals from birth to 3 months of age.

BACKGROUND: Arginine vasopressin (AVP) has received increased attention in equine critical care but there is minimal information of AVP concentration in foals. The clinical usefulness of measuring AVP in ill foals depends on knowledge of age-related changes in AVP concentrations in healthy foals. HYPOTHESIS: Plasma AVP concentrations will be significantly different when measured from birth to 3 months of age in healthy foals. ANIMALS: Thirteen healthy university-owned foals. METHODS: Prospective, observational study. Blood was collected from healthy foals at birth and 3, 5, 7, 10, 14, 21, 28, 42, 56, and 84 days of age. Plasma was harvested and plasma AVP concentrations were determined by radioimmunoassay. RESULTS: No statistically significant differences were detected in plasma AVP concentrations over the study period. Plasma AVP concentrations over the entire study period was 6.2+/-2.5 pg/mL. CONCLUSIONS AND CLINICAL IMPORTANCE: There was no age-related variation in plasma AVP concentrations detected in healthy foals from birth to 3 months of age suggesting that AVP concentrations are similar across foals of these ages.

Containment wells to form hydraulic barriers along site boundaries.

In the field, aquifer remediation methods include pump and treat procedures based on hydraulic control systems. They are used to reduce the level of residual contamination present in the soil and soil pores of aquifers. Often, physical barriers are erected along the boundaries of the target (aquifer) site to reduce the leakage of the released soil contaminant to the surrounding regions. Physical barriers are expensive to build and dismantle. Alternatively, based on simple hydraulic principles, containment wells or image wells injecting clear water can be designed and built to provide hydraulic barriers along the contaminated site boundaries. For brevity, only one pattern of containment well system that is very effective is presented in detail. The study briefly reports about the method of erecting a hydraulic barrier around a contaminated region based on the simple hydraulic principle of images. During the clean-up period, hydraulic barriers can considerably reduce the leakage of the released contaminant from the target site to surrounding pristine regions. Containment wells facilitate the formation of hydraulic barriers. Hence, they control the movement of contaminants away from the site that is being remedied. However, these wells come into play, only when the pumping operation for cleaning up the site is active. After operation, they can be filled with soil to permit the natural ground water movement. They can also be used as monitoring wells.

The cyclin-dependent kinase Cdk5 controls multiple aspects of axon patterning in vivo.

Cyclin-dependent kinase 5 (Cdk5) is one of a subfamily of Cdks involved in the control of cell differentiation and morphology rather than cell division. Specifically, Cdk5 and its activating subunit, p35, have been implicated in growth cone motility during axon extension. Both Cdk5 and p35 are expressed in post-mitotic neurons and are localized to growth cones [1] [2] [3] [4]. The Cdk5-p35 complex interacts with the Rac GTPase, a protein required for growth cone motility [5]. Studies using cultured neurons have suggested that Cdk5 activity controls the efficiency of neurite extension [3] [4]. Mutant mice lacking p35 exhibit subtle axon-guidance defects [6], but these mice have severe defects in neuronal migration [6] [7] [8], making it difficult to define precisely the role of the Cdk5-p35 complex in vivo. Here, we examined Cdk5 function in axon patterning in the Drosophila embryo. Although our data support the idea that Cdk5-p35 is involved in axonogenesis, they do not support the view that Cdk5 simply promotes growth cone motility. Instead, we found that disrupting Cdk5 function caused widespread errors in axon patterning.

Repeated mappings of arm veins by physical examination: role of nephrologists in the selection of suitable veins for AV fistula surgery.

Multidisciplinary team work is important for a successful hemodialysis vascular access program. The authors present a clinical case to illustrate the potential dynamic factors that can affect vein sizes, independent from the operators' skills and experiences. Therefore, if the first examination fails to detect suitable veins, repeated examinations of arm veins by nephrologists during routine office visits may greatly assist the surgeons in the selection of suitable arm veins for arteriovenous fistula surgery.

Model system for removing neuroblastoma cells from bone marrow using monoclonal antibodies and magnetic immunobeads.

Variables effecting removal of neuroblastoma cells from bone marrow using monoclonal antibodies and magnetic immunobeads were studied. Human neuroblastoma cell lines were labeled with the supravital DNA stain Hoechst 33342, seeded into normal bone marrow, incubated with monoclonal antibodies recognizing neuroblastoma cell surface antigens (HSAN 1.2, antibody 459, antibody 390, BA-1, and Leu-7), and then mixed with magnetic microspheres coated with goat anti-mouse immunoglobulin. Tumor cells that attached to the magnetic immunobeads were then removed from the marrow with magnets. The efficacy of tumor cell removal depended on the amount of monoclonal antibody bound to tumor cells and the immunobead/tumor cell ratio. In addition, two cycles of purging with both monoclonal antibodies and immunobeads was superior to one cycle. Using a cocktail of the five antibodies, 3 to 4 logs of tumor cells could be depleted from marrow with good recovery of viable hematopoietic cells.

Large scale identification of genes involved in cell surface biosynthesis and architecture in Saccharomyces cerevisiae.

The sequenced yeast genome offers a unique resource for the analysis of eukaryotic cell function and enables genome-wide screens for genes involved in cellular processes. We have identified genes involved in cell surface assembly by screening transposon-mutagenized cells for altered sensitivity to calcofluor white, followed by supplementary screens to further characterize mutant phenotypes. The mutated genes were directly retrieved from genomic DNA and then matched uniquely to a gene in the yeast genome database. Eighty-two genes with apparent perturbation of the cell surface were identified, with mutations in 65 of them displaying at least one further cell surface phenotype in addition to their modified sensitivity to calcofluor. Fifty of these genes were previously known, 17 encoded proteins whose function could be anticipated through sequence homology or previously recognized phenotypes and 15 genes had no previously known phenotype.

Statistical evaluation of FRAM gamma-ray isotopic analysis data.

High-purity germanium (HPGe) detector gamma-ray spectra were analyzed using the FRAM (fixed energy, response function analysis with multiple efficiencies) gamma-ray isotopic analysis software. The analyses are based on multiple measurements of samples having well-documented isotopic composition from mass spectrometry measurements. Statistical analyses of the FRAM results are reported, the errors in FRAM analyses arising from the choice of detector type and the energy region are discussed, and the errors that resulted from sample-dependent and analysis-dependent effects are quantified.

Syntheses, calcium channel agonist-antagonist modulation activities, and voltage-clamp studies of isopropyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-pyridinylpyridine-5-carboxylate racemates and enantiomers.

A novel group of racemic isopropyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-pyridinylpyridine-5-carboxylate isomers [(+/-)-12-14] were prepared using a modified Hantzsch reaction that involved the condensation of nitroacetone with isopropyl 3-aminocrotonate and 2-, 3-, or 4-pyridinecarboxaldehyde. Determination of their in vitro calcium channel-modulating activities using guinea pig ileum longitudinal smooth muscle (GPILSM) and guinea pig left atrium (GPLA) assays showed that the 2-pyridinyl isomer (+/-)-12 acted as a dual cardioselective calcium channel agonist (GPLA)/smooth muscle selective calcium channel antagonist (GPILSM). In contrast, the 3-pyridinyl [(+/-)-13] and 4-pyridinyl [(+/-)-14] isomers acted as calcium channel agonists on both GPLA and GPILSM. The agonist effect exhibited by (+/-)-12 on GPLA was inhibited by nifedipine and partially reversed by addition of extracellular Ca2+. In anesthetized rabbits, the 4-pyridinyl isomer (+/-)-14 exhibited a hypertensive effect that was qualitatively similar to that exhibited by the nonselective agonist Bay K 8644 and the 3-pyridinyl isomer (+/)-13, whereas the 2-pyridinyl isomer (+/-)-12 induced a hypotensive effect similar to that of the calcium channel antagonist nifedipine. Similar results were obtained in a spontaneously hypertensive rat model. In vitro studies showed that the (+)-2-pyridinyl enantiomer (+)-12A exhibited agonist activity on both GPILSM and GPLA, but that the (-)-2-pyridinyl enantiomer (-)-12B exhibited agonist activity on GPLA and antagonist activity on GPILSM. Whole-cell voltage-clamp studies using isolated guinea pig ventricular myocytes indicated that (-)-12B inhibited the calcium current (ICa), that (+)-12A increased slightly ICa, and that (+/-)-12 inhibited ICa but the latter inhibition was less than that for (-)-12B. (-)-12B effectively inhibited ICa at all membrane potentials examined (-40-50 mV), whereas (+)-12A exhibited a weak agonist effect near the peak of the I-V curve. The 2-pyridinyl isomers (enantiomers) 12 represent a novel type of 1,4-dihydropyridine calcium channel modulator that could provide a potentially new approach to drug discovery targeted toward the treatment of congestive heart failure and probes to study the structure-function relationships of calcium channels.

Synthesis and calcium channel-modulating effects of alkyl (or cycloalkyl) 1,4-dihydro-2,6-dimethyl-3-nitro-4-pyridyl-5-pyridinecarboxylate racemates and enantiomers.

A group of racemic alkyl (or cycloalkyl) 1,4-dihydro-2,6- dimethyl-3-nitro-4-(2-, 3-, or 4-pyridyl)-5-pyridinecarboxylate isomers (6-14) were prepared using a modified Hantzsch reaction that involved the condensation of nitroacetone with an alkyl (or cycloalkyl) 3-aminocrotonate and 2-, 3-, or 4-pyridinecarboxaldehyde. Determination of their in vitro calcium channel-modulating activities using guinea pig ileum longitudinal smooth muscle (GPILSM) and guinea pig left atrium (GPLA) assays showed that the 2-pyridyl isomers acted as dual cardioselective calcium channel agonists (GPLA)/smooth muscle selective calcium channel antagonists (GPILSM). In contrast, the 3-pyridyl and 4-pyridyl isomers acted as calcium channel agonists on both GPLA and GPILSM. In the C-4 2-pyridyl group of compounds, the size of the C-5 alkyl (or cycloalkyl) ester substituent was a determinant of GPILSM antagonist activity where the relative activity profile was cyclopentyl and cyclohexyl > t-Bu, i-Bu, and Et > MeOCH2CH2 > Me. The point of attachment of the C-4 pyridyl substituent was a determinant of GPLA agonist activity where the potency order was generally 4- and 3-pyridyl > 2-pyridyl. (+)-Cyclohexyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-pyridyl)-5- pyridinecarboxylate [(+)-14a] was a less potent calcium antagonist (IC50 = 5.27 x 10(-6) M) than the (-)-enantiomer (IC50 = 7.48 x 10(-8) M) on GPILSM. In the GPLA assay, (+)-14a exhibited a much more potent agonist effect (EC50 = 8.45 x 10(-6) M) relative to the marginal agonist effect produced by (-)-14a. The C-4 2-pyridyl compounds (enantiomers) constitute a novel type of 1,4-dihydropyridine calcium channel modulator that could provide a new drug design concept directed toward the treatment of congestive heart failure, and for use as probes to study the structure-function relationships of calcium channels.

Synthesis, rotamer orientation, and calcium channel modulation activities of alkyl and 2-phenethyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(3- or 6-substituted-2-pyridyl)-5-pyridinecarboxylates.

A group of racemic alkyl and 2-phenethyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(3- or 6-substituted-2-pyridyl)-5-pyridinecarboxylates (13a-q) was prepared using a modified Hantzsch reaction that involved the condensation of a 3- or 6-substituted-2-pyridinecarboxaldehyde (7a-j) with an alkyl or 2-phenethyl 3-aminocrotonate (11a-d) and nitroacetone (12). Nuclear Overhauser (NOE) studies indicated there is a significant rotamer fraction in solution where the pyridyl nitrogen is oriented above the 1,4-dihydropyridine ring, irrespective of whether a substituent is located at the 3- or 6-position. A potential H-bonding interaction between the pyridyl nitrogen free electron pair and the suitably positioned 1,4-dihydropyridine NH moiety may stablize this rotamer orientation. In vitro calcium channel antagonist and agonist activities were determined using guinea pig ileum longitudinal smooth muscle (GPILSM) and guinea pig left atrium (GPLA) assays, respectively. Compounds having an i-Pr ester substituent acted as dual cardioselective calcium channel agonists (GPLA)/smooth muscle-selective calcium channel antagonists (GPILSM), except for the C-4 3-nitro-2-pyridyl compound which exhibited an antagonist effect on both GPLA and GPILSM. In contrast, the compounds with a phenethyl ester group, which exhibited antagonist activity (IC50 = 10(-5)-10(-7) M range) on GPILSM, were devoid of cardiac agonist activity on GPLA. Structure-activity relationships showing the effect of a substituent (Me, CF3, Cl, NO2, Ph) at the 3- or 6-position of a C-4 2-pyridyl moiety and a variety of ester substituents (Me, Et, i-Pr, PhCH2CH2-) upon calcium channel modulation are described. Compounds possessing a 3- or 6-substituted-2-pyridyl moiety, in conjuction with an i-Pr ester substituent, are novel 1,4-dihydropyridine calcium channel modulators that offer a new drug design approach directed to the treatment of congestive heart failure and may also be useful as probes to study the structure-function relationships of calcium channels.

Oleanane saponins from Polyscias fruticosa.

From the leaves and roots of Polyscias fruticosa, eight new oleanolic acid saponins named polysciosides A to H were isolated together with three known saponins. The structures of the saponins were established by means of spectral data, particularly NMR, which included COSY, HSQC, HMBC, HOHAHA and ROESY techniques.