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In this study, open cell 25 % antimony-lead alloy foams are fabricated for possible use to lighten thick plates of lead-acid batteries. A new inexpensive and simple variant of the salt replication process is developed and explored. Different morphology and shapes have been successfully obtained with “excess salt replication” method (abbreviated as ESR method). Best porosity of about 68 % is obtained with salt particles size of about 3 mm. SEM and EDXS investigation of the composite salt/antimony alloy before NaCl leaching revealed the presence of the lead oxides microfilm coating cell walls and becoming lead carbonates after salt removal. Uniaxial compressive behaviour of the resulting cellular materials is studied for foams with porosities between 45 % and 70 %, and salt grain size ranging between 2.5 and 5 mm. A higher plateau stress is reached compared to the results obtained in the literature working on the aluminium foams. The reproducibility of the process is proved along samples. This work is licensed under a Creative Commons Attribution 4.0 International License. U ovom istraživanju izrađene su otvorene ćelije od 25 % antimon-olovnih pjena za moguću primjenu u osvjetljavanju debelih ploča olovno-kiselih baterija. Razvijena je i istražena nova jeftina i jednostavna varijanta procesa repliciranja soli. Različite morfologije i oblici uspješno su dobiveni metodom “prekomjerne replikacije soli” (ESR metodom). Najbolja poroznost od oko 68 % dobivena je pri veličini čestica soli od oko 3 mm. SEM i EDXS ispitivanje kompozitne legure soli/antimona prije ispiranja s NaCl otkrilo je prisutnost mikrofilma olovnih oksida koji oblažu zidove ćelije i nakon uklanjanja soli postaju olovni karbonati. Jednoosno tlačno ponašanje dobivenih materijala ćelije proučava se za pjene s poroznošću između 45 % i 70 % i za veličine zrna soli između 2,5 i 5 mm. Postignuta je veća granica stlačivanja u usporedbi s rezultatima o aluminijskim pjenama dobivenim u literaturi. Ponovljivost postupka dokazana je na uzorcima. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.

Today's chemical and physical-chemical wastewater discoloration methods do not completely meet demands regarding degree of discoloration. In this paper discoloration was performed using Fenton (FeSO4 · 7 H2O + H2O2 + H2SO4) and Fenton-like (FeCl3 · 6 H2O + H2O2 + HCOOH) chemical methods and physical-chemical method of coagulation/flocculation (using poly-electrolyte (POEL) combining anion active coagulant (modified poly-acrylamides) and cationic flocculant (product of nitrogen compounds) in combination with adsorption on activated carbon. Suitability of aforementioned methods was investigated on reactive and acid dyes, regarding their most common use in the textile industry. Also, investigations on dyes of different chromogen (anthraquinone, phthalocyanine, azo and xanthene) were carried out in order to determine the importance of molecular spatial structure. Oxidative effect of Fenton and Fenton-like reagents resulted in decomposition of colored chromogen and high degree of discoloration. However, the problem is the inability of adding POEL in stechiometrical ratio (also present in physical-chemical methods), when the phenomenon of overdosing coagulants occurs in order to obtain a higher degree of discoloration, creating a potential danger of burdening water with POEL. Input and output water quality was controlled through spectrophotometric measurements and standard biological parameters. In addition, part of the investigations concerned industrial wastewaters obtained from dyeing cotton materials using reactive dye (C. I. Reactive Blue 19), a process that demands the use of vast amounts of electrolytes. Also, investigations of industrial wastewaters was labeled as a crucial step carried out in order to avoid serious misassumptions and false conclusions, which may arise if dyeing processes are only simulated in the laboratory. Današnje kemijske i fizikalno-kemijske metode obezbojavanja otpadnih voda ne zadovoljavaju u potpunosti zahtjeve vezane uz stupanj obezbojavanja. U ovom radu obezbojavanje se provodilo pomoću Fentonove kemijske metode (FeSO4· 7 H2O + H2O2 + H2SO4) i modificirane Fentonove kemijske metode (FeCl3 · 6 H2O+H2O2+ HCOOH), te pomoću fizikalno-kemijske metode upotrebom koagulanata/flokulanata (polielektrolita-POEL), koja kombinira anionski koagulant (modificirani poliakrilamid) i kationski flokulant (produkt dušikovih spojeva) uz adsorpciju na aktivnom ugljenu. Prihvatljivost opisanih metoda ispitivana je za reaktivna i kisela bojila, s obzirom na njihovu raširenu primjenu u tekstilnoj industriji. Također, provedena su ispitivanja na bojilima različitih kromogena (antrakinon, ftalocijanin, azo i ksanten) s ciljem određivanja važnosti prostorne strukture molekule. Oksidativno djelovanje Fentonovog i modificiranog Fentonovog postupka dovodi do razgradnje obojenog kromogena i visokog stupnja obezbojavanja. Međutim, ustanovljena je nemogućnost dodavanja POEL u stehiometrijskom odnosu (također prisutno kod modificiranog Fentonovog postupka), odnosno dodavanje koagulanata u suvišku kako bi se postigao viši stupanj obezbojavanja, što u konačnici dovodi do opterećenja voda POEL-ima. Kvaliteta vode na ulazu i izlazu kontrolirana je pomoću spektrofotometrijskih mjerenja i uobičajenih bioloških parametara. U prilog tome, dio ispitivanja bio je vezan za industrijske otpadne vode bojadisaone, u kojoj se pamučni materijal bojadisao bojilom C. I. Reactive Blue 19 i to tehnološkim postupkom koji zahtijeva uporabu velike količine elektrolita. Također, ispitivanje industrijskih otpadnih voda označeno je ključnim korakom izbjegavanja niza krivih pretpostavki i zaključaka, koji bi mogli nastati u slučaju laboratorijskog simuliranja procesa bojadisanja.

Polyketides and non-ribosomal peptides represent a large class of structurally diverse natural products much studied over recent years because the enzymes that synthesise them, the modular polyketide synthases (PKSs) and the non-ribosomal peptide synthetases (NRPSs), share striking architectural similarities that can be exploited to generate "un-natural" natural products. PKS and NRPS proteins are multifunctional, composed of a co-linear arrangement of discrete protein domains representing each enzymic activity needed for chain elongation using either carboxylic acid or amino acid building blocks. Each domain is housed within larger modules which form the complex. Polyketide and peptide antibiotics, antifungals, antivirals, cytostatics, immunosuppressants, antihypertensives, antidiabetics, antimalarials and anticholesterolemics are in clinical use. Of commercial importance are also polyketide and peptide antiparasitics, coccidiostatics,animal growth promoters and natural insecticides.Polyketides are assembled through serial condensations of activated coenzyme-A thioester monomers derived from simple organic acids such as acetate, propionate and butyrate. The choice of organic acid allows the introduction of different chiral centres into the polyketide backbone. The active sites required for condensation include an acyltransferase (AT), an acyl carrier protein (ACP) and a ß-ketoacylsynthase (KS). Each condensation results in a ß-keto group that undergoes all, some or none of a series of processing steps. Active sites that perform these reactions are contained within the following domains; ketoreductase (KR), dehydratase (DH) and an enoylreductase (ER). The absence of any ß-keto processing results in the incorporation of a ketone group into the growing polyketide chain, a KR alone gives rise to a hydroxyl moiety, a KR and DH produce an alkene, while the combination of KR, DH and ER domains lead to complete reduction to an alkane. Most often, the last module contains the thioesterase domain (TE) responsible for the release of linear polyketide chain from the enzyme and final cyclisation. After assembly, the polyketide backbone typically undergoes post-PKS modifications such as hydroxylation(s), methylation(s) and glycosylation(s) to give the final active compound.Non-ribosomal peptides are assembled by the so-called "multiple carrier thio-template mechanism". Three domains are necessary for an elongation module: an adenylation (A) domain that selects the substrate amino acid, analogous to a polyketide AT domain, and activates it as an amino acyl adenylate; a peptidyl carrier protein (PCP) that binds the co-factor 4-phosphopantetheine to which the activated amino acid is covalently attached, analogous to the ACP of a PKS; and a condensation (C) domain that catalyzes peptide bond formation, again analogous to the KS in modular PKSs. The NRPSs also contain a (Te) domain located at the C-terminal of the protein which is essential for release of linear, cyclic or branched cyclic peptides. Auxiliary activities can further enlarge the structural diversity of the peptide especially common are epimerization domains (Epim) that convert the thioester-bound amino acid from an L- to D- configuration.There has been a lot of interest in the last few years in generating new compounds for the production of novel drugs by manipulating the programming of such clusters in vitro (e.g. the idea of combinatorial biosynthesis). However, an important barrier to the progress is the fact that most changes made by in vitro methods result in very low yields or no detectable product. A possible solution to the yield problem would be the generation of novel clusters by homologous recombination in vivo, because this would favour more closely related sequences and should reduce problems caused by non-functional incompatible junctions.The Unified Modeling Language (UML) was used to define the platform independent integral generic program packages, CompGen and ClustScan, which are under development to model these processes in silico. The heart of CompGen is a specially structured database, based on BioSQL v1.29, which connects the biosynthetic order of synthase/synthetase enzymes to the sequences of the component polypeptides. The additional linkage to the gene sequences allows the integration of DNA sequence with product structure. The database contains sequences of the well-characterised PKS/NRPS clusters, and non-annotated sequenced clusters whose structure and functionis yet unknown, to act as building blocks for the production of novel products. It is easy to add custom sequences to the database and to annotate them by the use of propriety protein profiles designed by Pfam database and HMMER. One function of the program is the ability to generate virtual recombinants between clusters. This can be done using a recombination model (with optional parameters) to predict sites for homologous recombination or by user defined recombination sites (e.g. to model in vitro genetic manipulation such as module replacement). The program predicts the linear polyketide structure of the resulting "un-natural" natural products with a chemical description using isomeric SMILES. Molecular modelling of the subsequent spontaneous cyclisation process produces structures for a virtual compound database for further molecular modelling studies using PASS and CDD technology. An optional "reverse genetics" module analyses a given chemical structure to see if it could be produced by a novel PKS/NRPS synthesis cluster and suggests the DNA sequence of a suitable cluster based on building blocks derived from clusters contained in the database.Overall, the CompGen allows in silico generation of the database of novel "un-natural" natural chemical compounds that can be used for in silico screening using PASS or CDD technology. The other integral generic program package, ClustScan, will recognise and annotate new gene clusters from microbial genome sequencing projects or in metagenomes of soil and/or marine microorganisms.

The teaching of the periodic system in the historical context has an advantage because students in this way comprehend more easily the basic chemical concepts, such as relative atomic mass, proton number, chemical element, elementary substance, equivalent and molar mass. The story of the periodic system also shows the following: (1) Before a key scientific discovery there is a long period of data collection and systematization, (2) Theories in chemistry must be based on experimental results and methods, (3) The advancement of science is also determined by the development of concepts, and (4) Scientific theories usually do not contradict but support each other. Therefore, the historical periodic system (based on relative atomic mass) is not obsolete, but complementary to the modern.

Polymeric nanocomposites are commonly considered as systems composed of a polymeric matrix and - usually inorganic - filler. The types of nanofillers are indicated in Fig. 1. Beside wellknown layered silicate fillers, recent attention is attracted to layered double hydroxide fillers (LDH), mainly of synthetic origin. The structure of LDH is based on brucite, or magnesium hydroxide, Mg(OH)2 and is illustrated in Fig. 2. The modification of LDHs is commonly done by organic anions, to increase the original interlayer distance and to improve the organophilicity of the filler, keeping in mind their final application as fillers for, usually hydrophobic, polymer matrices. We have used the modified rehydration procedure for preparing organically modified LDH. The stoichiometric quantities of Ca33Al2O6, CaO and benzoic (B) (or undecenoic (U)) acid were mixed with water and some acetone. After long and vigorous shaking, the precipitated fillers were washed, dried and characterized. X-ray diffraction method (XRD) has shown the increase of the original interlayer distance for unmodified LDH (OH–-saturated) of 0.76 nm to the 1.6 nm in LDH-B or LDH-U fillers (Fig. 3). Infrared spectroscopy method (FTIR) has confirmed the incorporation of benzoic anion within the filler layers (Fig. 4). For the preparation of LDH-B and LDH-U composites with polystyrene (PS), poly(methyl methacrylate) (PMMA) and copolymer (SMMA) matrices, a two-step in situ bulk radical polymerization was selected (Table 1 for recipes, azobisisobutyronitrile as initiator), using conventional stirred tank reactor in the first step, and heated mold with the movable wall (Fig. 6) in the second step of polymerization. All the prepared composites with LDH-U fillers were macroscopically phase-separated, as was the PMMA/LDH-B composite.PS/LDH-B and SMMA/LDH-B samples were found to be transparent and were further examined for deduction of their structure (Fig. 5) and thermal properties. FTIR measurements showed that there is some filler present in the nanocomposites (Fig. 7). XRD measurements pointed to the disturbance of the characteristic layered structure of the filler in the obtained composites (Fig. 8). Transmission electron microscopy (TEM) images showed that the filler was not homogeneously dispersed within the matrix (Fig. 9). However, the dispersion was quite good, and a high degree of exfoliation was obtained for PS/LDH-B composites (Fig. 10); the predominantly intercalated structure was found for SMMA/LDH-B composites (Fig. 11). Thus, in both cases nanocomposites were prepared. The thermal characterization by the differential scanning calorimetry (DSC) showed the increase of glass transition point of 10 °C for PS/LDH-B nanocomposite with intermediate (w = 2.5 or 5.0 %) filler content (in comparison with neat PS), a feature that is characteristic for exfoliated nanocomposites. No such increase was obtained for SMMA/LDH-B nanocomposites. The thermal degradation in the inert nitrogen atmosphere was studied by thermal gravimetric analysis (TGA) method. The improvement of thermal stability of PS/LDH-B in comparison with neat PS was found only for the nanocomposites with intermediate (w = 2.5 or 5.0 %) filler content (Fig. 12), again proving the exfoliated structure. The half-weight loss temperature of SMMA/LDH-B nanocomposites continuously increases with the increase of filler content (Fig. 13), a feature that is characteristic for intercalated nanocomposites. In conclusion, the described methods were found satisfactory for preparing the exfoliated nanocomposites of LDH-B and PS. New organic modifiers are to be sought, if exfoliated nanocomposites of SMMA and PMMA matrices are to be prepared. Further investigation will include the deduction of mechanical properties of prepared materials.

Liquid-liquid equilibria were experimentally investigated in systems in which the first component was aliphatic (n-hexane, n-heptane or i-octane) or aromatic hydrocarbon (toluene), the second component was pyridine or thiophene, and the third quasi-component was DES consisting of choline chloride and glycerol or choline chloride and ethylene glycol, at 25 °C and atmospheric pressure. The equilibria were successfully described by the NRTL and UNIQUAC models. The same models were successfully applied to describe the liquid-liquid equilibria in quasi-seven-component systems that comprised all the mentioned low molecular weight components and one DES. The restrictions of the models were discussed; it seems that the preference can be given to the UNIQUAC model. This work is licensed under a Creative Commons Attribution 4.0 International License. Eksperimentalno su istražene ravnoteže kapljevina-kapljevina u sustavima u kojem je prva komponenta alifatski (n-heksan, n-heptan odnosno i-oktan) ili aromatski ugljikovodik (toluen), druga komponenta je piridin ili tiofen, a treća kvazi-komponenta je DES koji se sastoji od kolin klorida i glicerola, odnosno kolin klorida i etilen-glikola, pri 25 °C i atmosferskom tlaku. Ravnoteže su uspješno opisane modelima NRTL i UNIQUAC. Isti su modeli uspješno primijenjeni i za opis ravnoteža kapljevina-kapljevina i u kvazi-sedmerokomponentnim sustavima koji uključuju sve navedene niskomolekulske komponente i jedan DES. Raspravljena su ograničenja modela; čini se da se prednost može dati modelu UNIQUAC. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.

In this paper, a review of reactions with benzotriazole as synthetic auxiliary is given. In contrast to most other azoles, benzotriazole reacts with phosgene in molar ratio 1:1 yielding carboxylic acid chloride (BtcCl, 1), which readily reacts with nucleophiles giving reactive compounds. These products can be easily transformed into carbamates, ureas, semicarbazides, carbazides, sulfonylureas, sulfonylcarbazides, nitroalkanic acid esters, etc. In addition, benzotriazole was used in the synthesis of various heterocyclic compounds: benzoxazine, kinazoline, triazinetrione, hydantoin and oxadiazine derivatives. The reaction of chloride 1 with amino acids enabled the use of benzotriazole in peptide chemistry, with triple role of benzotriazolecarbonyl group as N-protecting, N-activating, and both N-protecting/C-activating group. N-(1-benzotriazolecarbonyl)-amino acids 25 are starting compounds in the synthesis of various amino acid, di- and tripeptide derivatives, hydantoic acids and hydroxyureas.Benzotriazole was also applied in the preparation of polymer-drug and thiomer-drug conjugates, polymeric prodrugs with drugs covalently bound to the polymeric carriers. Such macromolecular prodrugs may offer many advantages compared to other drug delivery systems such as increased drug solubility, prolonged drug release, increased stability. It is also possible to accumulate the drug at the site of the pathological process and to minimize its toxicity. In this paper, the binding of drugs from various therapeutic groups (mostly nonsteroidal, anti-inflammatory drugs) to polymersof polyaspartamide type by the benzotriazolide method is described.

The effect of acid concentration, time and temperature of modification on the magnesium removal from sepiolite modified by hydrochloric acid, sulfuric acid and nitric acid and on its effectiveness as an active matrix for FCC catalysts, were investigated. The modified sepiolite was characterized by XRD, SEM and N2 adsorption. The results show that the removal of magnesium, specific surface area, and pore specific volume of modified sepiolite are improved with increasing acid concentration, treating time and treating temperature. Hydrochloric acid appears preferable to the modification of sepiolite. The suitable acid modification conditions of sepiolite for FCC catalysts are 80 for 2.5 h with 1 mol L-1 HCl acid, under which the removal of magnesium in sepiolite is 27 %. With the modified sepiolite as an active matrix for FCC catalysts, the specific surface area, pore specific volume and mesopore pore specific volume of the catalysts can increase effectively, the catalysts exhibit excellent heavy-metal resisting performance and better cracking properties as a result of the introduction of magnesium oxide from the modified sepiolite. U radu je istraživano djelovanje koncentracije kiseline, vremena i temperature modificiranja na uklanjanje magnezija iz sepiolita, kao i na djelotvornost aktivne matrice FCC-katalizatora pripravljenog korištenjem solne, sumporne i dušične kiseline. Modificirani sepiolit je bio karakteriziran rendgenskom difrakcijom praškastih uzoraka, pretražnom elektronskom mikroskopijom te adsorpcijom N2. Dobiveni rezultati ukazuju na povećanje uklanjanja magnezija, specifične površine i volumena pora modificiranog sepiolita s povišenjem koncentracije kiseline, vremena i temperature reakcije. Uvjeti pogodni za kiselinsko modificiranje sepiolita jesu 80 °C tijekom 2,5 sata te c(HCl) = 1,0 mol dm-3, pri čemu se postiže 27-postotno uklanjanje magnezija. Korištenjem modificiranog sepiolita kao aktivne matrice FCC katalizatora, povećana je specifična površina, volumen pora te volumen mezopora katalizatora. Također, tako pripravljeni katalizatori iskazuju odličnu otpornost na kontaminaciju teškim kovinama te bolja krekirajuća svojstva kao posljedicu uklanjanja magnezijeva oksida iz sepiolita.

HAZOP (Hazard and Operability Analysis) is a method of safety analysis, which is widely used in chemical processes. The conventional methods for safety analysis consist of human based safety analysis and computer aid safety analysis. All of them are off-line and qualitative and it is difficult to carry out on-line safety analysis. On-line safety analysis based on scenario object model was proposed for chemical processes. The scenario object model was built using ontology, by which the safety information can be transferred, reused and shared effectively. Deviation degree and qualitative trend were added to the model. Based on the model and new inference algorithm, on-line safety analysis can be implemented for chemical processes. Once a fault or abnormal event occurs, the causes can be traced and the consequences can be predicted. At the same time, semi-quantitative safety analysis is carried out. The resolution can be improved and it can help the operators handle the problems in time and effectively. The method was used for safety analysis of a reactor process and the effectiveness of the method was proved. This work is licensed under a Creative Commons Attribution 4.0 International License. HAZOP (analiza opasnosti i operativnosti) metoda je sigurnosne analize koja se primjenjuje u kemijskim procesima. Konvencionalne metode za analizu sigurnosti mogu biti ljudske i računalne. Sve su to kvalitativne i off-line analize, a sigurnosnu on-line analizu teško je provesti. Za kemijske procese predložena je sigurnosna on-line analiza temeljena na scenarijskom objektnom modelu. Scenarijski objektni model izrađen je ontološki, čime se sigurnosne informacije mogu učinkovito prenijeti, ponovno upotrijebiti i dijeliti. Stupanj devijacije i kvalitativni trend pridodani su modelu. Na temelju modela i novog algoritma zaključivanja sigurnosna se on-line analiza može implementirati u kemijske procese. Kada se dogodi pogreška ili abnormalni događaj, mogu se pratiti uzroci i predvidjeti posljedice. Istodobno se provodi polukvantitativna sigurnosna analiza. Rješenje je moguće poboljšati i time omogućiti operaterima pravodobno i učinkovito rješavanje problema. Metoda je primijenjena za sigurnosnu analizu reaktorskog procesa te je dokazana njezina učinkovitost. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.