Hasil untuk "Physical and theoretical chemistry"

Кузнецов П.М., Гомзяк В.И.

В настоящее время исследования в области медицины направлены на разработку и внедрение новых стратегий профилактики, диагностики и лечения различного рода заболеваний, создания вакцин и т.д. Большинство исследований ориентировано на улучшение противораковой терапии. В последние десятилетия наблюдается повышенное внимание к разработке наносомальных форм для доставки лекарственных препаратов, в частности, для терапии онкологических заболеваний. Биоразлагаемые полимеры на основе лактида и его производных являются одними из перспективных материалов для получения наноразмерных носителей противораковых препаратов для адресной доставки. В обзоре приведены данные о некоторых коммерческих препаратах на основе данных полимеров.

Adsorption Science and Technology

A. M. H. Bond, A. M. H. Bond, M. M. Frey et al.

<p>Measurements of atmospheric nitrous acid (<span class="inline-formula">HONO</span>) amount fraction and flux density above snow were carried out using a long-path absorption photometer at Halley station in coastal Antarctica between 22 January and 3 February 2022. The mean <span class="inline-formula">±1<i>σ</i></span> <span class="inline-formula">HONO</span> amount fraction was (2.1 <span class="inline-formula">±</span> 1.5) <span class="inline-formula">pmol mol⁻¹</span> and showed a diurnal cycle (range of 1.0–3.2 <span class="inline-formula">pmol mol⁻¹</span>) with a maximum at solar noon. These <span class="inline-formula">HONO</span> amount fractions are generally lower than have been observed at other Antarctic locations. The flux density of <span class="inline-formula">HONO</span> from the snow, measured between 31 January and 1 February 2022, was between 0.5 and <span class="inline-formula">3.4×10¹²</span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M10" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">s</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="7aa9599418446b482f97cb2b6fbb5c99"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-5533-2023-ie00001.svg" width="39pt" height="13pt" src="acp-23-5533-2023-ie00001.png"/></svg:svg></span></span> and showed a decrease during the night. The measured flux density is close to the calculated <span class="inline-formula">HONO</span> production rate from photolysis of nitrate present in the snow. A simple box model of <span class="inline-formula">HONO</span> sources and sinks showed that the flux of <span class="inline-formula">HONO</span> from the snow makes a <span class="inline-formula">&gt;10</span> times larger contribution to the <span class="inline-formula">HONO</span> budget than its formation through the reaction of <span class="inline-formula">OH</span> and <span class="inline-formula">NO</span>. Ratios of these <span class="inline-formula">HONO</span> amount fractions to <span class="inline-formula">NO_<i>x</i></span> measurements made in summer 2005 are low (0.15–0.35), which we take as an indication of our measurements being comparatively free from interferences. Further calculations suggest that <span class="inline-formula">HONO</span> photolysis could produce up to 12 <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M21" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">pmol</mi><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">mol</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">h</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="73pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="c0553d142508f72f22d8e6a455d687cf"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-23-5533-2023-ie00002.svg" width="73pt" height="15pt" src="acp-23-5533-2023-ie00002.png"/></svg:svg></span></span> of <span class="inline-formula">OH</span>, approximately half that produced by ozone photolysis, which highlights the importance of <span class="inline-formula">HONO</span> snow emissions as an <span class="inline-formula">OH</span> source in the atmospheric boundary layer above Antarctic snowpacks.</p>

Junsong Cang, Yin-Zhe Ma, Yu Gao

Sufficiently large scalar perturbations in the early universe can create overdense regions that collapse into primordial black holes (PBHs). This process is accompanied by the emission of scalar-induced gravitational waves that behave like an extra radiation component, thus contributing to the relativistic degrees of freedom ( N _eff ). We show that the cosmological constraints on N _eff can be used to pose stringent limits on PBHs created from this particular scenario as well as the relevant small-scale curvature perturbation ( ${{ \mathcal P }}_{{ \mathcal R }}(k)$ ). We show that the combination of cosmic microwave background (CMB), baryon acoustic oscillation, and Big Bang nucleosynthesis data sets can exclude supermassive PBHs with peak mass M _• ∈ [5 × 10 ^5 , 5 × 10 ^10 ] M _⊙ as the major component of dark matter, while the detailed constraints depend on the shape of the PBHs’ mass distribution. A future CMB mission such as CMB-S4 can greatly broaden this constraint window to M _• ∈ [8 × 10 ^−5 , 5 × 10 ^10 ] M _⊙ , covering substellar masses. These limits on PBHs correspond to a tightened constraint on ${{ \mathcal P }}_{{ \mathcal R }}$ on scales of k ∈ [10, 10 ^22 ] Mpc ^−1 , much smaller than those probed by direct CMB and large-scale structure power spectra.

K. Dubey, Binju Wang, Yubing Si et al.

Department of Chemistry and Center for Informatics, School of Natural Sciences, Shiv Nadar University Delhi-NCR, Greater Noida, India, State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, China, College of Chemistry, Zhengzhou University, Zhengzhou, China, Third World Center for Science and Technology, H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan

Tatsuya Yamada, Tomohiko Hayashi, Simon Hikiri et al.

An oncoprotein MDM2 binds to the extreme N-terminal peptide region of a tumor suppressor protein p53 (p53NTD) and inhibits its anticancer activity. We recently discovered a peptide named MIP which exhibits much higher binding affinity for MDM2 than p53NTD. Experiments showed that the binding free energy (BFE) of MDM2-MIP is lower than that of MDM2-p53NTD by ~-4 kcal/mol. Here we develop a theoretical method which is successful in reproducing this quantitative difference and elucidating its physical origins. It enables us to decompose the BFE into a variety of energetic and entropic components, evaluate their relative magnitudes, and identify the physical factors driving or opposing the binding. It should be applicable also to the assessment of differences among ligands in the binding affinity for a particular receptor, which is a central issue in modern chemistry. In the MDM2 case, the higher affinity of MIP is ascribed to a larger gain of translational, configurational entropy of water upon binding. This result is useful to the design of a peptide possessing even higher affinity for MDM2 as a reliable drug against a cancer.

Manohar Chelli Sai, Kumar B Siva, Sadhu Sai Pavan Prashanth et al.

BCZT (Ba0.85Ca0.15Zr0.1Ti0.9O3) is a recent class of lead-free ferroelectric material associated with high piezoelectric coefficient, making it suitable to inspire hydroxyapatite (HA)-BCZT ceramics for bone materials. Nano-crystalline hydroxyapatite (HA) synthesized using the hydrothermal route was characterized via FT-IR, Raman spectroscopy, X-ray powder diffraction (XRD), and Scanning Electron Microscopy (SEM). We also rationalized its formation as a function of operating conditions such as dwell time and temperature in this route. The nano-crystalline BCZT powder was synthesized via a sol-gel technique and its structural and morphological characterization were carried out using Raman Spectroscopy, XRD and Transmission Electron Microscopy (TEM). These investigations facilitated the optimization of HA-BCZT compositions and their electrical poling conditions to achieve enhanced piezoelectric effect. The composites (HA-BCZT) sintered at 1350∘C exhibited promising piezoelectric properties. We report the enhanced piezoelectric coefficient (d33) of 7±1 pC/N for 50% HA-BCZT which is significant as compared to that reported in the literature for ~98% BT (barium titanate) -HA composites. We highlight the role of Simulated Body Fluid (SBF) on the intriguing phase-change of Tricalcium Phosphate (TCP) obtained at this sintering temperature, to hydroxyapatite for its essential contribution to promote bone growth. We theoretically support the confirmed in vitro biocompatibility of these composites.

B. Bozzini, M. Amati, T. Dobrovolska et al.

Fascinating spatiotemporal patterns forming during the electrodeposition of some alloys have attracted the interest of the scientific communities dealing with electrochemical materials science and dynamic processes. Notwithstanding extensive experimental work and recently achieved theoretical insights, several aspects of the physical chemistry of these dynamic structures are still elusive. In particular, the analytical methods employed so far to characterize these structures invariably failed to pinpoint any chemical or structural patterns correlated to those perceived by the naked eye or with a light microscope. In this work, we have made systematic use of the extreme surface sensitivity provided by synchrotron-based scanning photoelectron microspectroscopy, combined with progressive erosion by precisely controlled Ar+ sputtering, to achieve quantitative 3D understanding of the compositional and chemical-state distribution of an Ag–In electrodeposited layer, following the key elements Ag, In, and O. The ...

T. John, B. Abel, L. Martin

Baoshan He, Ming Li

An electrochemical method using carboxylic multi-walled carbon nanotubes (MWCNTs-COOH) modified glassy carbon electrode (GCE) was described for detecting nitrofurazone (NF) and semicarbazide (SEM) residual. The chemical structure and morphological features of carboxylic multi-walled carbon nanotubes were determined by FTIR spectroscopy and scanning electron microscope. The electrochemical behavior of NF and SEM on MWCNTs-COOH/GCE was also investigated by cyclic voltammetry (CV). And the effect of the buffer pH and scan rate was optimized. Under the optimized experimental conditions, the linear relationship between the peak current and the concentration of NF and SEM was determined using the amperometry (AMP). The linear relationship of NF was Ip(μA) =-21.050-0.095c(μmol L-1), r = 0.999, with a detection limit of 2.24×10-7 mol L-1 (S/N=3). The linear relationship of SEM was Ip(μA) =-0.269+0.0599c(mol L-1), r=0.998, with a detection limit of 1.88×10-7 mol L-1 (S/N=3). Finally, the modified electrode was successfully applied in the real sample and the average recoveries for NF and SEM were 91.1~94.0% and 92.9~98.0%, respectively.

M. Aaboud, G. Aad, B. Abbott et al.

Abstract The modification of the production of $$J/\psi $$ J/ψ , $$\psi (2\mathrm {S})$$ ψ(2S) , and $$\varUpsilon (n\mathrm {S})$$ Υ(nS) ($$n = 1, 2, 3$$ n=1,2,3 ) in p+Pb collisions with respect to their production in pp collisions has been studied. The p+Pb and pp datasets used in this paper correspond to integrated luminosities of $$28~\mathrm {nb}^{-1}$$ 28nb-1 and $$25~\mathrm {pb}^{-1}$$ 25pb-1 respectively, collected in 2013 and 2015 by the ATLAS detector at the LHC, both at a centre-of-mass energy per nucleon pair of 5.02 TeV. The quarkonium states are reconstructed in the dimuon decay channel. The yields of $$J/\psi $$ J/ψ and $$\psi (\mathrm {2S})$$ ψ(2S) are separated into prompt and non-prompt sources. The measured quarkonium differential cross sections are presented as a function of rapidity and transverse momentum, as is the nuclear modification factor, $$R_{p\mathrm {Pb}}$$ RpPb for $$J/\psi $$ J/ψ and $$\varUpsilon (n\mathrm {S})$$ Υ(nS) . No significant modification of the $$J/\psi $$ J/ψ production is observed while $$\varUpsilon (n\mathrm {S})$$ Υ(nS) production is found to be suppressed at low transverse momentum in p+Pb collisions relative to pp collisions. The production of excited charmonium and bottomonium states is found to be suppressed relative to that of the ground states in central p+Pb collisions.

Taniyuki Furuyama, N. Kobayashi

P. Takis, K. Papavasileiou, L. Peristeras et al.