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Coordination of hydralazine with Cu2+ at acidic pH promotes its oxidative degradation at neutral pH
No full textHydralazine (HL), a frequently prescribed oral antihypertensive drug, shows redox interactions with transition
metals such as copper that are not fully understood. Copper may be present at high concentrations in the digestive
tract and can affect oral drugs. An important parameter for such interactions is pH, which changes from
acidic in the gastric juice to neutral pH in intestines. In this study, we examined interactions of HL with Cu2+ ions
in conditions that mimic pH shift in the digestive tract using UV–Vis, Raman and EPR spectroscopy, cyclic
voltammetry and oximetry. In the acidic solution, Cu2+ formed a stable mononuclear complex with two bidentate
coordinated HL molecules. On the other hand, at neutral pH, Cu2+ initiated oxidation and degradation of
HL. The degradation was more rapid in the HL-Cu2+ system that was initially prepared at acidic pH and then
shifted to neutral pH. The formation of the complex at acidic pH increases the availability of Cu2+ for redox reactions
after the shift to neutral pH at which Cu2+ is poorly soluble. These results imply that the change of pH along
the digestive tract may promote HL degradation by allowing the formation of the complex at gastric pH which
makes Cu2+ available for subsequent oxidation of HL at neutral pH
Effect of dopants on anatase structure
Get PDFIt is well known that TiO2-based Degussa P-25 is the mostly used comer-cial photocatalyst and that TiO2 exists in three crystalline modifications: tetragonal anatase (I41/amd) and rutile (P42/mnm) and orthorhombic brookite (Pbca). On heating, anatase and brookite, as metastable phases, can be transformed to rutile. The aim of this work was to investigate the effect of different dopants on anatase-rutile phase transition and thus on their photocatalytic behavior. For that matter, samples TiO2 M (M = Cu, Mn and V) having 5 at.% of dopants were prepared by 30 minutes hand-mixing of anatase and corresponding oxide (CuO, MnO2 and V2O5) powders in an agate mortar following by heat treatment at 700 °C for 3 h. The powder of pure anatase phase was also treated at same conditions. TG/DTA was used to define thermal treatment, and the obtained samples were characterized by powder XRD method in order to reach phase compositions, unit cell parameters and crystallite sizes. Since in the case of undoped anatase only 3 wt.% of rutile was formed, the presence of dopants accelerated phase transition: 26 and 76 wt.% of rutile was obtained beside anatase in TiO2 Mn and TiO2 V, respectively, while complete anatase to rutile phase transition occured in TiO2-Cu. The least rutile quantity in TiO2-Mn is related to the isovalency of Ti4+ and Мn4+ meaning that the incorporation of Мn4+ in TiO2 is not followed by the formation of new defects, which are driving force for phase transition, as in the case of TiO2 Cu. About 5 wt.% of the unreacted CuO was found in TiO2 Cu, which is almost all introduced quantity of CuO. This can be related to the fact that the ionic radius of Cu2+ for octahedral environment (0.870 Å) is larger than that of Ti4+ (0.745 Å). As a result, Cu2+ ions can hardly be incorporated in TiO2 comparing to smaller Мn4+ (0.670 Å) and V5+ (0.680 Å) although a small amount of Cu2+ surely was necessary to cause phase transition. Since no residues of initial oxides were found in TiO2 Mn and TiO2 V, it can be concluded that these metal ions were incorporated into anatase lattice. By comparing the calculated unit cell parameters of anatase mutually, the shrinkage along c-axis was revealed meaning the shortening of bond distances between М–Оapical. The photocatalytic activity of all synthesized samples will be tested since nanocrystalline samples were obtained according to determined crystallite sizes (55–90 nm).Degussa P-25 је фотокатализатор на бази титан(IV)-оксида, који се најчешће користи у индустрији. TiO2 се јавља у три полиморфне модификације: тетрагоналним анатасу (I41/amd) и рутилу (P42/mnm) и ромбичном брукиту (Pbca). Анатас и брукит, као метастабилне фазе, приликом загревања прелазе у рутил. Циљ овог истраживања је испитивање утицаја различитих допаната на фазни прелаз анатаса у рутил као и на фотокаталитичка својства. Узорци TiO2-M (M = Cu, Mn и V), који садрже 5 at.% допанта, припремљени су термохемијском реакцијом на 700 °C током 3 h између хомогенизованих прахова анатаса и одговарајућих оксида (CuO, MnO2 и V2O5). Ради поређења, прах чистог анатаса је термички третиран под истим условима. Помоћу ТГ/ДТ анализе дефинисани су услови термичког третмана, док су добијени узорци окарактерисани рендгенском дифракцијом на поликристалном материјалу да би се одредио фазни састав, параметри јединичних ћелија и величина кристалита. У случају недопираног анатаса настало је свега 3 mas.% рутила, 26 и 76 mas.% рутила добијено је у TiO2 Mn и TiO2 V, редом, док се потпуни фазни прелаз анатас–рутил одиграо у TiO2 Cu. Ово значи да присуство допанта убрзава фазну трансформацију. Најмања количина рутила у TiO2 Mn може се објаснити изовалентним Ti4+ и Мn4+, тј. да уградња Мn4+ у TiO2 није праћена настанком нових дефеката који представљају вучну силу за одигравање фазног прелаза, као што је то случај код TiO2 Cu. Око 5 mas.% непрореаговалог CuO (готово почетна количина) заостало је у TiO2 Cu, зато што се Cu2+-јони теже уграђују у решетку TiO2 због већег радијуса Cu2+ у октаедарском окружењу (0,870 Å) од радијуса Ti4+ (0,745 Å), за разлику од мањих Мn4+ (0,670 Å) и V5+ (0,680 Å). Ипак, сигурно је мала количина Cu2+-јона била неопходна како би иницирала фазни прелаз. Како у TiO2 Mn и TiO2 V нису присутни остаци полазних оксида, може се закључити да су се ови јони метала уградили у решетку анатаса. Међусобним поређењем параметара јединичне ћелије анатаса, уочено је скраћење дуж c-осе, што указује на скраћење дужина веза М–Оапикални. Израчуната величина кристалита (55–90 nm) показала је да су сви добијени узорци нанокристални, па ће њихова фотокаталитичка својства бити испитана
GASTROINTESTINAL NEMATODES IN SHEEP - CURRENT SITUATION AND MODERN CONTROL STRATEGIES
Get PDFГастроинтестиналне нематоде представљају веома важне паразите код домаћих животиња, нарочито код малих преживара. Код оваца обољења најчешће имају субклиничан ток са смањењем телесне масе и производње, а понекад може доћи и до видљивих клиничких симптома попут анемије, јаке дијареје, анорексије и губитака протеина што све заједно може довести и до угинућа. Комерцијални препарати попут бензимидазола и макроцикличних
лактона су се деценијама са успехом користили у контроли ових паразита. Међутим, њихова нерационална примена је довела до развоја антихелминтичке резистенције, опадања ефикасности лекова и последичних економских губитака који угрожавају одрживост гајења оваца. Поред тога, примена комерцијалних препарата је повезана и са резидуама које остављају у животињским производима и животној средини, при чему је присутан и раст цене ових препарата. Због тога се активно трага за новијим стратегијама за контролу ових паразита, а које се ослањају на интегрисан приступ који подразумева примену више различитих стратегија. Са једне стране, ту спадају стратегије рационалне примене комерцијалних препарата заснованих на рефугији (циљани третмани и циљани селективни третмани), као и комбинација и ротација антихелминтика из различитих хемијских група. Са
друге стране, интегрисан приступ подразумева и употребу различитих алтернативних стратегија попут генетске селекције животиња природно резистентних на нематоде, рационално управљање пашњацима, избалансирану исхрану уз допунска хранива, биолошку контролу (употребу гљива, бактерија и слично), развој вакцина као и употребу ботаничких препарата (биљака и њихових производа попут екстракта и етарских уља).
Различита истраживања су доказала ефикасност наведених стратегија у контроли гастроинтестиналних нематода оваца, при чему се најбољи резултати постижу њиховом комбинованом применом. На овај начин је могуће постићи успоравање развоја и ширења антихелминтичке резистенције, као и одрживу контролу ових паразита и смањење економских губитака.Gastrointestinal nematodes represent very important parasites in domestic
animals, especially in small ruminants. In sheep, diseases usually have a
subclinical course with a decrease in body weight and production, whereby
sometimes visible clinical symptoms such as anaemia, severe diarrhea, anorexia
and protein loss with a possible fatal outcome may occur. Commercial drugs such
as benzimidasoles and macrocyclic lactones have been used successfully for
decades in the control of these parasites. However, their inappropriate use has led
to the development of anthelmintic resistance, decreasing efficacy of drugs and
consequent economic losses that endanger the sustainability of sheep farming. In
addition, application of commercial preparations is also associated with the
residues in animal products and the environment, while the increase in their price
is also present. Therefore, novel strategies for the control of these parasites are
actively sought, which rely on an integrated approach that involves the application
of several different strategies. On the one hand, these include strategies for the
rational application of commercial drugs based on refugia (target treatments and
target selective treatments), as well as the combination and rotation of
anthelmintics from different chemical groups. On the other hand, an integrated
approach implies the use of various alternative strategies, such as genetic
selection of animals naturally resistant to nematodes, rational management of
pastures, balanced nutrition with supplementary nutrients, biological control (use
of fungi, bacteria, etc.), development of vaccines, as well as the use of botanical
preparations (plants and their products such as extracts and essential oils).
Various studies have proven the effectiveness of the mentioned strategies in the
control of gastrointestinal nematodes of sheep, whereby the best results are
achieved by their combined application. In this way, it is possible to slow down
the development and spread of anthelmintic resistance, and to achieve sustainable
control of these parasites and reduction of economic losses
The crucial role of defect structure in understanding the electrical properties of spark plasma sintered antimony doped barium stannate
Get PDFThe influence of structural defects in spark plasma sintered BaSn1-xSbxO3 (BSSO, x=0.00 and 0.08)
ceramic samples on their electrical properties was investigated in the temperature range of 300–4K.
X-ray photoelectron spectroscopy (XPS) revealed the presence of point defects, primarily oxygen
vacancies (VO) and mixed oxidation states of tin (Sn2+/Sn4+) in both samples. As a result, the
undoped BSSO sample exibited a non-standard semiconductor behavior, retaining its temperaturedependent
resistivity. The electrical resistivity of the doped samples was two orders of magnitude
lower than that of the undoped sample. The presence of structural defects such asVO, mixed oxidation
states of the constituent elements, and significant amounts ofO− species make the electrical resistivity
of the doped sample constant in the temperature range of 300–70 K, indicating heavily-doped
semiconductor behavior
αVβ3-Integrin and mitochondria mediate astrocyte response to autoreactive immune cells
No full textThe astrocytic network maintains homeostasis in the central nervous system (CNS)
through interactions with neighboring cells. In the CNS autoimmune disease, multiple
sclerosis (MS), neuroinflammatory conditions modulate these cell-to-cell interactions.
Our previous work revealed that the immune cells infiltrated into the CNS (CNS-IICs)
of experimental autoimmune encemphalomyelitis (EAE) rat, an animal model of MS,
rapidly alter the activity pattern of astrocytes by activating the glial P2X7 receptor
(P2X7R). In the present study we further defined the mechanisms responsible for
astrocytes’ activation in the presence of CNS-IICs. For this purpose, we used an in
vitro experimental setup and monitored Ca2+ dynamics in Fluo-4-labeled cultured
naïve astrocytes following brief bath application of CNS-IICs isolated from the spinal
cord of the EAE rat. Our data indicate that the astroglial αvβ3-integrin is involved in
the initial contact of astrocytes with CNS-IICs, since blocking αvβ3-integrin reduced
the expected astrocytic Ca2+ response. Furthermore, blocking of mitochondrial
Na+/Ca2+- and H+/Ca2+- exchangers in astrocytes promoted an augmentation of the
intracellular Ca2+ increase and a higher ATP release after brief exposure to CNS-IICs,
demonstrating that mitochondria regulate the astrocyte-CNS IICs cell-cell interaction.
Overall, our study expands the understanding of astrocytes’ interaction with
autoreactive immune cells that are present in their local environment in an
autoimmune disease. This offers a new conceptual framework for considering direct
astrocyte–immune cell interaction to design new strategies for therapy development in
the treatment of MS
Properties and Potential Application of Lead-Free (BaZr0.2Ti0.8O3) and Lead-Based (PbZr0.52Ti0.48O3) Flexible Thick Films
Get PDFFor the last several decades, energy harvesters based on piezoelectricity from mechanical
vibration have emerged as very promising devices that are being explored extensively for their
functionality in energy technologies. In this paper, a series of flexible lead-free BaZr0.2Ti0.8O3
(BZT)/PVDF and lead-based PbZr0.52Ti0.48O3 (PZT)/PVDF piezocomposites with variable filler
content up to 50 vol% were prepared by a hot pressing method. The structure and morphology
of the BZT and PZT powders, as well as the distribution of the piezo-active filler in the obtained
flexible films were characterized by XRD and SEM analysis. In addition, the remnant polarization
(Pr) and leakage current were also investigated to evaluate the breakdown strength in both types of flexible films. The calculations of storage energies and output voltage obtained for the investigated materials revealed an increasing trend with an increasing amount of BZT and PZT active phases.
The maximum storage energy of 0.42 J/cm3 (and energy efficiency of 40.7 %) was obtained for the
PZT–PVDF (40–60) films, while the maximum output voltage of about 10 V (~10 μA) was obtained
for the PZT–PVDF (50–50) flexible film. In addition, a comparison between the properties of the
lead-based and lead-free flexible films, as well as the potential use of these films as energy storage and energy harvesting systems were analyzed
Humidity and Temperature Sensing of Mixed Nickel–Magnesium Spinel Ferrites
Get PDFTemperature- and humidity-sensing properties were evaluated of NixMg1-x spinel ferrites (0 ≤ x ≤ 1) synthesized by a sol-gel combustion method using citric acid as fuel and nitrate ions as oxidizing agents. After the exothermic reaction, amorphous powders were calcined at 700 °C ollowed by characterization with XRD, FTIR, XPS, EDS and Raman spectroscopy and FESEM
icroscopy. Synthesized powders were tested as humidity- and temperature-sensing materials in the form of thick films on interdigitated electrodes on alumina substrate in a climatic chamber. The physicochemical investigation of synthesized materials revealed a cubic spinel Fd3m phase, nanosized but agglomerated particles with a partially to completely inverse spinel structure with increasing Ni content. Ni0.1Mg0.9Fe2O4 showed the highest material constant (B30,90) value of 3747 K and temperature sensitivity (α) of −4.08%/K compared to pure magnesium ferrite (B30,90 value of 3426 K and α of −3.73%/K) and the highest average sensitivity towards humidity of 922 kΩ/%RH in the relative humidity (RH) range of 40–90% at the working temperature of 25 °C
Structure and properties of ZnO/ZnMn2O4 composite obtained by thermal decomposition of terephthalate precursor
Get PDFA biphasic [Mn(dipya)(H2O)4](tpht)/{[Zn(dipya)(tpht)]•H2O}n complex material, I, (dipya = 2,2’-dipyridylamine, tpht2- = dianion of terephthalatic acid) was synthesized by ligand exchange reaction and characterized by XRPD and FTIR spectroscopy. A ZnO/ZnMn2O4 composite, II, has been prepared via thermal decomposition of precursor I in an air atmosphere at 450°C. XRPD, FTIR and FESEM analyses of II revealed the simultaneous presence of spherical nanoparticles of wurtzite ZnO and elongated nanoparticles of spinel ZnMn2O4. The specific surface area of II was determined by the BET method, whereas the volume and average size of the mesopores were calculated in accordance with the BJH method. The measurements of the mean size, polydispersity index and zeta potential showed colloidal instability of II. Two band gap values of 2.4 and 3.3 eV were determined using UV-Vis diffuse reflectance spectroscopy, while the measurements of photoluminescence revealed that II is active in the blue region of the visible spectrum. Testing of composite II as a pigmentary material showed that it can be used for the colouring of a ceramic glaze.Двофазни [Mn(dipya)(H2O)4](tpht)/{[Zn(dipya)(tpht)]·H2O}n комплексни материјал, I,
(dipya = 2,2’-дипиридиламин, tpht2– = дианјон 1,4-бензендикарбоксилне киселине) синтетисан је реакцијом измене лиганада и окарактерисан XRPD мeтoдом и FTIR спектроскопијом. Композит ZnO/ZnMn2O4, II, добијен је термичком разградњом прекурcopa I у атмосфери ваздуха на 450 °C. XRPD мeтoдом, FTIR спектроскопијом и FESEM микроскопијом композита II утврђено је истовремено присуство сферних наночестица ZnO
вирцитне структуре и издужених наночестица ZnMn2O4 са структуром спинела. Специфична површина II одређена је BET методом, док су запремина и просечна величина мезопора израчунати у складу са BJH методом. Средња величина, индекс полидисперзије и цета потенцијал измерени су фотонском корелационом спектроскопијом и електрофоретским расејањем светлости и показали су нестабилност композита II. Вредности
ширине забрањене зоне 2,4 и 3,3 eV одређене су UV-Vis дифузно-рефлексионом спектроскопијом, док су мерења фотолуминесценције показала да је II активан у плавој области видљивог дела спектра. Испитивање композита II као пигментног материјала показало је да се може користити за бојење керамичке глазуре
Magnetic spinel ferrite nanoparticles from synthesis to biomedical applications
No full textSpinel ferrites are a widely investigated and applied class of materials with a cubic spinel lattice structure. Their unique multifunctional properties (magnetic characteristics, tunable shape/size, large number of active surface sites, high values of specific surface area, good chemical stability, and possibilities for enhancing properties through surface modification) influenced by the synthesis procedure make them attractive for biomedical applications as magnetic nanoparticles in drug delivery to a set target, magnetic hyperthermia, tissue engineering, magnetic extraction of biological components and magnetic diagnostics. In this review, we give an overview of up-to-date synthesis procedures for obtaining magnetic spinel nanoparticles and nanocomposites with optimal properties for biomedical applications
Prospects of fish scale and fin samples usage for nonlethal monitoring of metal contamination: a study on five fish species from the Danube River
Get PDFThe development of nonlethal methods for the monitoring of environmental contamination is
essential to minimize the negative effects on studied species and communities. Fish scales and fin clips can be used as nonlethal indicators of water quality given that they are in direct contact with the environment and can accumulate high concentrations of metals and trace elements. Fin clipping causes minimal harm to fish and it does not affect fish growth or survival. In this study, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, and Zn concentrations were measured by inductively-coupled plasma mass spectrometry (ICP-MS) in scales, fins, and muscle of common bream (Abramis brama), white bream (Blicca bjoerkna), wels catfish (Silurus glanis), northern pike (Esox lucius), and pikeperch (Sander lucioperca) from the Danube River. The analysis showed a positive correlation for Hg between scales and muscle in pikeperch. Anal fin and muscle were positively correlated in white bream for Hg, in wels catfish for Cu, and in northern pike and pikeperch for As. The results suggest that scales and fins have a potential to be used as indicators of muscle tissue contamination with As, Cu, and Hg, depending on species’ ecological traits