Catalytic molecularly imprinted polymer membranes: Development of the biomimetic sensor for phenols detection

Portable biomimetic sensor devices for the express control of phenols content in water were developed. The synthetic binding sites mimicking active site of the enzyme tyrosinase were formed in the structure of free-standing molecularly imprinted polymer membranes. Molecularly imprinted polymer membranes with the catalytic activity were obtained by co-polymerization of the complex Cu (II)–catechol–urocanic acid ethyl ester with (tri)ethyleneglycoldimethacrylate, and oligourethaneacrylate. Addition of the elastic component oligourethaneacrylate provided formation of the highly cross-linked polymer with the catalytic activity in a form of thin, flexible, and mechanically stable membrane. High accessibility of the artificial catalytic sites for the interaction with the analyzed phenol molecules was achieved due to addition of linear polymer (polyethyleneglycol Mw 20,000) to the initial monomer mixture before the polymerization. As a result, typical semi-interpenetrating polymer networks (semi-IPNs) were formed. The cross-linked component of the semi-IPN was represented by the highly cross-linked catalytic molecularly imprinted polymer, while the linear one was represented by polyethyleneglycol Mw 20,000. Extraction of the linear polymer from the fully formed semi-IPN resulted in formation of large pores in the membranes’ structure. Concentration of phenols in the analyzed samples was detected using universal portable device oxymeter with the oxygen electrode in a close contact with the catalytic molecularly imprinted polymer membrane as a transducer. The detection limit of phenols detection using the developed sensor system based on polymers–biomimics with the optimized composition comprised 0.063 mM, while the linear range of the sensor comprised 0.063–1 mM. The working characteristics of the portable sensor devices were investigated. Storage stability of sensor systems at room temperature comprised 12 months (87%). As compared to traditional methods of phenols detection the developed sensor system is characterized by simplicity of operation, compactness, an

Energy Dependence of Moments of Net-Proton Multiplicity Distributions at RHIC

We report the beam energy(√8NN = 7.7-200 GeV) and collision centrality dependence of the mean (M), standard deviation (σ), skewness (S), and kurtosis (κ) of the net-proton multiplicity distributions in Au+Au collisions. The measurements are carried out by the STAR experiment at midrapidity (|y|\u3c0.5) and within the transverse momentum range 0.4\u3cρτ\u3c0.8  GeV/c in the first phase of the Beam Energy Scan program at the Relativistic Heavy Ion Collider. These measurements are important for understanding the quantum chromodynamic phase diagram. The products of the moments, Sσ and κσ2, are sensitive to the correlation length of the hot and dense medium created in the collisions and are related to the ratios of baryon number susceptibilities of corresponding orders. The products of moments are found to have values significantly below the Skellam expectation and close to expectations based on independent proton and antiproton production. The measurements are compared to a transport model calculation to understand the effect of acceptance and baryon number conservation and also to a hadron resonance gas model

Isolation of Flow and Nonflow Correlations by Two- and Four-Particle Cumulant Measurements of Azimuthal Harmonics in sNN=\sqrt{s_{_{\rm NN}}} = 200 GeV Au+Au Collisions

A data-driven method was applied to measurements of Au+Au collisions at $\sqrt{s_{_{\rm NN}}} =$ 200 GeV made with the STAR detector at RHIC to isolate pseudorapidity distance $\Delta\eta$-dependent and $\Delta\eta$-independent correlations by using two- and four-particle azimuthal cumulant measurements. We identified a component of the correlation that is $\Delta\eta$-independent, which is likely dominated by anisotropic flow and flow fluctuations. It was also found to be independent of $\eta$ within the measured range of pseudorapidity $|\eta|<1$. The relative flow fluctuation was found to be $34\% \pm 2\% (stat.) \pm 3\% (sys.)$ for particles of transverse momentum $p_{T}$ less than $2$ GeV/$c$. The $\Delta\eta$-dependent part may be attributed to nonflow correlations, and is found to be $5\% \pm 2\% (sys.)$ relative to the flow of the measured second harmonic cumulant at $|\Delta\eta| > 0.7$

Сенсорная система для определения сульфаметоксазола на основе молекулярно импринтированных полимерных мембран

Проблематика. Розробка сенсорних систем на основі штучних аналогів біологічних макромолекул є актуальною для сучасної аналітичної біотехнології, оскільки забезпечує нові ефективні експрес-методи детекції малих органічних молекул, в тому числі фармацевтичних препаратів. Мета дослідження. У роботі пропонується аналітична система для високоселективного та чутливого визначення сульфаметоксазолу на основі молекулярно імпринтованих полімерних (МІП) мембран, синтезованих із застосуванням методу полімеризації in situ у комбінації з методом комп’ютерного моделювання. Методика реалізації. Молекули сульфаметоксазолу, селективно адсорбовані штучними рецепторними сайтами у структурі МІП мембран, візуалізували завдяки їх здатності формувати забарвлені у коричневий колір комплекси після реакції з фериціанідом калію та нітропрусидом натрію в лужному середовищі. Результати дослідження. Межа визначення сульфаметоксазолу становила 2 мМ, а лінійний динамічний діапазон роботи сенсорної системи – 2–15 мМ, що дає змогу визначати сульфаметоксазол у фармацевтичних препаратах. Стабільність розроблених сенсорних систем на основі МІП становила принаймні 6 місяців, що значно перевищує стабільність аналогічних пристроїв на основі природних рецепторів. Висновки. Доведено придатність розроблених сенсорних систем для аналізу сульфаметоксазолу як у модельних, так і в реальних зразках (комерційно доступних фармацевтичних препаратах). Розроблені сенсорні системи характеризуються високою селективністю, чутливістю, портативністю та невисокою вартістю.Background. Development of sensor systems based on synthetic mimics of biological molecules will provide new effective express-methods for detection of small organic molecules, including pharmaceuticals, for modern analytical biotechnology. Objective. An analytical system for highly selective and sensitive detection of sulfamethoxazole based on molecularly imprinted polymer (MIP) membranes is proposed, synthesized using the method of in situ polymerization in a combination with the method of computational modeling. Methods. Sulfamethoxazole molecules, that were selectively adsorbed by the synthetic binding sites in MIP membranes structure, were visualized due to their ability to form brown-colored complexes after reaction with potassium ferricyanide and sodium nitroprusside in alkaline media. Results. The limit for sulfamethoxazole detection comprised 2 mM, while the linear dynamic range – 2–15 mM, which allows one to detect sulfamethoxazole in pharmaceutical preparations. Stability of the developed MIP-based sensor systems was estimated as at least 6 months, which significantly increases stability of analogous devices based on natural receptors. Conclusions. Applicability of the developed sensor systems for the analysis of sulfamethoxazole in both model solutions and real samples (commercial pharmaceutical preparations) was proven. The developed systems are characterized with high selectivity, sensitivity, small size and low cost.Проблематика. Разработка сенсорных систем на основе искусственных аналогов биологических макромолекул является актуальной для современной аналитической биотехнологии, поскольку обеспечивает новые эффективные экспресс-методы детекции малых органических молекул, в том числе фармацевтических препаратов. Цель исследования. В работе предлагается аналитическая система для высокоселективного и чувствительного определения сульфаметоксазола на основе молекулярно импринтированных полимерных (МИП) мембран, синтезированных с использованием метода полимеризации in situ в комбинации с методом компьютерного моделирования. Методика реализации. Молекулы сульфаметоксазола, селективно адсорбированные синтетическими рецепторными сайтами в структуре МИП мембран, визуализировали благодаря их способности формировать окрашенные в коричневый цвет комплексы после реакции с феррицианидом калия и нитропруссидом натрия в щелочной среде. Результаты исследования. Предел обнаружения сульфаметоксазола составил 2 мМ, а линейный динамический диапазон сенсорной системы – 2–15 мМ, что дает возможность определять сульфаметоксазол в фармацевтических препаратах. Стабильность разработанных сенсорных систем на основе МИП составила по крайней мере 6 месяцев, что значительно превосходит стабильность аналогичных приборов на основе природных рецепторов. Выводы. Доказана возможность использования разработанных сенсорных систем для анализа сульфаметоксазола как в модельных, так и в реальных образцах (коммерчески доступных фармацевтических препаратах). Разработанные сенсорные системы характеризуются высокой селективностью, чувствительностью, портативностью и невысокой стоимостью

Charged-to-neutral correlation at forward rapidity in Au+Au collisions at sNN\sqrt{s_{NN}}=200 GeV

Event-by-event fluctuations of the ratio of inclusive charged to photon multiplicities at forward rapidity in Au+Au collision at $\sqrt{s_{NN}}$=200 GeV have been studied. Dominant contribution to such fluctuations is expected to come from correlated production of charged and neutral pions. We search for evidences of dynamical fluctuations of different physical origins. Observables constructed out of moments of multiplicities are used as measures of fluctuations. Mixed events and model calculations are used as baselines. Results are compared to the dynamical net-charge fluctuations measured in the same acceptance. A non-zero statistically significant signal of dynamical fluctuations is observed in excess to the model prediction when charged particles and photons are measured in the same acceptance. We find that, unlike dynamical net-charge fluctuation, charge-neutral fluctuation is not dominated by correlation due to particle decay. Results are compared to the expectations based on the generic production mechanism of pions due to isospin symmetry, for which no significant (<1%) deviation is observed.Comment: 14 pages, 6 figure

Studies of di-jet survival and surface emission bias in Au+Au collisions via angular correlations with respect to back-to-back leading hadrons

We report first results from an analysis based on a new multi-hadron correlation technique, exploring jet-medium interactions and di-jet surface emission bias at RHIC. Pairs of back-to-back high transverse momentum hadrons are used for triggers to study associated hadron distributions. In contrast with two- and three-particle correlations with a single trigger with similar kinematic selections, the associated hadron distribution of both trigger sides reveals no modification in either relative pseudo-rapidity or relative azimuthal angle from d+Au to central Au+Au collisions. We determine associated hadron yields and spectra as well as production rates for such correlated back-to-back triggers to gain additional insights on medium properties.Comment: By the STAR Collaboration. 6 pages, 2 figure

System size and energy dependence of near-side di-hadron correlations

Two-particle azimuthal ($\Delta\phi$) and pseudorapidity ($\Delta\eta$) correlations using a trigger particle with large transverse momentum ($p_T$) in $d$+Au, Cu+Cu and Au+Au collisions at $\sqrt{s_{{NN}}}$ =\xspace 62.4 GeV and 200~GeV from the STAR experiment at RHIC are presented. The \ns correlation is separated into a jet-like component, narrow in both $\Delta\phi$ and $\Delta\eta$, and the ridge, narrow in $\Delta\phi$ but broad in $\Delta\eta$. Both components are studied as a function of collision centrality, and the jet-like correlation is studied as a function of the trigger and associated $p_T$. The behavior of the jet-like component is remarkably consistent for different collision systems, suggesting it is produced by fragmentation. The width of the jet-like correlation is found to increase with the system size. The ridge, previously observed in Au+Au collisions at $\sqrt{s_{{NN}}}$ = 200 GeV, is also found in Cu+Cu collisions and in collisions at $\sqrt{s_{{NN}}}$ =\xspace 62.4 GeV, but is found to be substantially smaller at $\sqrt{s_{{NN}}}$ =\xspace 62.4 GeV than at $\sqrt{s_{{NN}}}$ = 200 GeV for the same average number of participants ($\langle N_{\mathrm{part}}\rangle$). Measurements of the ridge are compared to models.Comment: 17 pages, 14 figures, submitted to Phys. Rev.