Tetrahedral Homonuclear Tetrameric Species: Occurrence, Forms, Structures, Properties, and Perspectives

Tetrahedral homonuclear tetrameric species are neutral or ionic tetrahedra of chemical elements, true molecular tetrahedra in strict geometrical sense. The aim of this work was to find all true elemental tetrahedra experimentally determined as stable and capable of being transferred from one medium/condition to another, to rationalize their structures and properties, and seek their technological significance. A database of elemental tetrahedra was built based on reliable literature, and a dataset of molecular descriptors was generated. Correlation analysis, hierarchical cluster analysis, principal component analysis, and some regression analysis were carried out. Twelve chemical elements from Groups 13 – 15 have tetrahedral species: anions E48– (Al, Ga, In, Tl), anions E44– (Si, Ge, Sn, Pb), neutral molecules E4 (P, As, Sb), and cations E4+ (P, As, Sb, Bi). These species appear in 39 forms, such as gas phase, solid Zintl phases, thin films, Zintl phase ammoniates, and cage compounds, among others. Zintl phases and forms of P4 and As4 are important for synthesis of new materials, chemical reactions, and other applications. Data compression has shown that the true tetrahedral species are a three-dimensional phenomenon, and that true tetrahedra can be distinguished from fictive tetrahedra. Grouping of the tetrahedra according to their periodic groups, charges, frequency, and diversity class values, tetrahedral size, and metallic character, were observed. Empirical rules for species size and principal components were established for true tetrahedra. Most descriptors are parabolic functions of the class variable. True tetrahedral species partly remain a puzzle and should be further investigated

Integral Sign Change Problem Check in Quantitative Structure-Activity/Property Relationships: A Tutorial

Sign change problem (SCP) in multivariate Quantitative Structure-Activity/Property Relation¬ships (QSAR/QSPR) is the inconsistency in the direction of association between molecular descriptors and the dependent variable. Sign change is observed when the signs of the elements of the reference vec¬tor (correlation vector for the data set obtained from variable selection) are compared to the signs of the elements of all correlation and regression vectors related to a model. SCP check in this work, named Inte¬gral SCP (ISCP) check, is established to be a general effective anti-SCP procedure, consisting of five check levels. Twelve diverse QSAR/QSPR data sets from literature were tested, and performance of data sets, models and descriptors was assessed by qualitative labeling systems. Most data sets and models did not have satisfactory performance, what is discussed in terms possible data and model remedy

O kvantitativnim odnosima između kemijske strukture i fizičko-kemijskih svojstava kemijskih proizvoda: Studij slučaja: Bjelovarsko-bilogorska županija

Even small areas as Bjelovar-Bilogora County (BBC) are affected by increasing local and regional pollution. A large variety of organic compounds exists in all parts of the atmosphere, waters and soil, accumulates in living organisms and on anthropogenic objects. This work investigates organic pollutants in BBC in relation to their spread, behavior and chemical properties, based on literature data in absence of experimental measurements. More than 230 organic pollutants were identified in BBC: simple compounds, benzene derivatives, polycyclic aromatic hydrocarbons, polychlorinated and other biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans, halogenated alkanes and alkenes, diverse pesticides and antimicrobials. Geographic distribution of organic pollutants was investigated in relation to population density, agricultural activity, position of volatile organic compounds emitters, annual traffic data, and night sky brightness levels as light pollution. It is visible that towns and larger villages as well as main roads are emitters of various organic pollutants and smog generators, whilst typically rural regions are more characterized by pesticides pollution. Three examples for QSPR (Quantitative Structure-Property Relationship) are described and investigated in terms of their statistics (sign change problem) and chemical interpretability: 1) a partial least squares (PLS) regression model for boiling point of polycyclic aromatic hydrocarbons; 2) a multiple linear regression (MLR) model for micellar phase-water partition coefficient of diverse solutes; 3) a MLR model for bioconcentration factor of nonpolar organic compounds. Several samples in the models were already identified as existing pollutants in BBC. Models 2) and 3) failed in the sign check, for which explanations are given and remedies are proposed.Čak i mali krajevi kao Bjelovarsko-bilogorska županija sve su više pogođeni lokalnim i regionalnim zagađenjem. Razna zagađivala iz mnogih grupa organskih spojeva raspro-stranjena su u svim dijelovima atmosfere, u vodama i tlu, te se nagomilavaju u živim organizmima i na površinama antropogenih objekata. U ovom radu proučavaju se načini širenja i ponašanja te kemijska svojsta organskih zagađivala u Bjelovarsko-bilogorskoj županiji na temelju literaturnih podataka pošto ne postoje eksperimentalna mjerenja. Pronađeno je više od 230 organskih zagađivala u Bjelovarsko-bilogorskoj županiji, a to su: jednostavni spojevi, derivati benzena, policiklički aromatski ugljikovodici, poliklorirani i drugi bifenili, poliklorirani dibenzo-p-dioksini i dibenzofurani, halogenirani alkani i alkeni, te razni pesticidi i antimikrobni spojevi. Geografska rasprostanjenost organskih zagađivala proučavana je u odnosu na gustoću naseljenosti, poljoprivrednu djelatnost, položaj izvora hlapivih organskih spojeva, prosječan godišnji dnevni promet, te razine svjetla na noćnom nebu kao svjetlosno zagađenje. Vidljivo je da su gradovi, veća sela i glavne ceste izvori raznih organskih zagađivala i proizvođači smoga, dok su tipično seoska područja više zagađena pesticidima. Tri su primjera za KOSS (kvantitativni odnos stukture i svojstva) opisana i istražena u smislu njihove statistike (problem promjene predznaka) i kemijskog tumačenja: 1. regresijski model parcijalnih najmanjih kvadrata (PNK) za vrelište policikličkih aromatskih ugljikovodika; 2. model višestruke linearne regresije (VLR) za koeficijent raspodjele micelarna faza-voda raznih topivih spojeva; 3. model VLR za faktor biokoncentracije nepolarnih organskih spojeva. Mnogi su uzorci u modelima već utvrđena zagađivala u Bjelovarsko-bilogorskoj županiji. Modeli 2. i 3. zakazali su u provjeri predznaka za što se daju objašnjenja te se preporučuju popravci

Students’ Academic Honesty – a Prerequisite for the Economic Development

Studentsko poštenje ključan je element akademske čestitosti, s obzirom na to da udio visokoobrazovanih osoba stalno raste. Studenti su buduća pokretačka snaga društva, dio su populacije koja će bitno utjecati na cjelokupno društvo i njegov socioekonomski razvoj, uključujući i mlađe generacije. U radu je analizirano osam skupova podataka o konstantnom porastu studentskog nepoštenja u SAD-u, Ujedinjenom Kraljevstvu, Švedskoj i svijetu kao cjelini, s tendencijom naglog skoka u posljednja dva desetljeća. Situacija u Hrvatskoj uspoređena je s tim trendovima, iz podataka koji su dobiveni intenzivnim pretraživanjem raznih literaturnih i internetskih izvora te nekih procjena. Dobiveni su indeksi studentskog nepoštenja: prosječno (IC0) i maksimalno (IC1) prepisivanje na ispitima te prosječan (IP0) i maksimalan (IP1) plagijarizam. Indeksi uglavnom prate svjetske trendove, a u zadnja dva desetljeća imaju alarmantno visoke prosječne postotke studenata uključenih u nepoštene radnje: 64% (IC0), 76% (IC1), 33% (IP0) i 77% (IP1). Sakupljeni su i procijenjeni podaci za pet socioekonomskih indeksa: BDP (bruto domaći proizvod po stanovniku), HDI (indeks ljudskog razvoja), GII (globalni inovacijski indeks), CPI (indeks percepcije korupcije) i EI (edukacijski indeks). Uteženom korelacijom i regresijom utvrđeno je da su IC0, IC1, IP0 i IP1 različiti indeksi, da IP0 i IP1 slabo koreliraju s vremenom i socioekonomskim varijablama zbog nedovoljno podataka o studentskom plagiranju, a da IC0 i IC1 visoko koreliraju s vremenom, GDP, HDI i EI. IC0 i IC1 skromno padaju zadnjih nekoliko godina, a IP0 i IP1 ne pokazuju nikakav pad. Ovisnost IC0 i IC1 o GDP, HDI i EI predočuju dvije sigmoidne krivulje, s manjim skokom oko 1980. i s većim oko 2010. godine. Društvena uvjetovanost studentskog nepoštenja i njegova porasta znači kulturu koju treba mijenjati, od kulture profita, konkurencije i uspjeha u kulturu znanja i odgovornosti, s istaknutim socijalnim i moralnim komponentama sociekonomskog razvoja.Students’ honesty is a key element in the context of academic honesty, when taking into consideration that the share of academically educated persons is in permanent increase. Students are the future moving power of the society; they are the part of the population that will significantly influence the society on the whole and its socio-economic development, including the younger generations. The paper analyses eight groups of data on the constant growth of students’ dishonesty in the world, and particularly in the USA, the United Kingdom and Sweden. Over the last two decades, a significant increase has been recorded. The situation in Croatia has been compared with these trends on the basis of the data gained by studying various sources from literature and the internet, as well as several estimates. As a result, the following students’ dishonesty indices have been defined: average (IC0) and maximal (IC1) cheating at exams, and average (IP0) and maximal (IP1) plagiarism. The indices mainly follow global trends, whilst over the last two decades, the average percentage of students engaging in dishonest activities has been alarmingly high: 64 % (IC0); 76 % (IC1); 33 % (IP0) and 77 % (IP1). Data according to five socio-economic indices have been collected and estimated: GDP (gross domestic product per capita), HDI (human development index), GII (global innovation index), CPI (corruption perception index), and EI (education index). By the means of weighing correlation and regression, it has been determined that IC0, IC1, IP0 and IP1 are different indices; that IP0 and IP1 do not correlate well with time and the socio-economic variables due to an insufficient quantity of data on students’ plagiarism; that IC0 and IC1 correlate well with time, GDP, HDI and EI. Furthermore, IC0 and IC1 have modestly decreased over the last several years; and IP0 and IP1 have demonstrated no decrease at all. The dependence of IC0 and IC1 on GDP, HDI and EI has been presented by two sigmoid curves, with a minor increase around 1980, and a major around 2010. Since students’ dishonesty and its growth have been socially determined, the culture itself ought to be changed – from the culture of profit, competition and success to the culture of knowledge and responsibility, with pronounced social and moral components of the socio-economic development

Majčino mlijeko najbolji je izbor prehrane za novorođenče i dojenče Breast milk is the ideal food for newborns and infants

Nizom dugogodišnjih istraživanja potvrđene su prednosti majčinog mlijeka za zdravlje, rast i razvoj djece, a tako i za zdravlje njihovih majki. Majčino mlijeko sadržava mnogo komponenata koje imaju važnu nutritivnu i imunološku ulogu za dijete. Dojenje ima važnu zaštitnu ulogu i za majku. Velika važnost pridaje se promoviranju što duljeg dojenja s ciljem očuvanja i unapređenja zdravlja djeteta. Dojenje ima i važnu psihosocijalnu ulogu. Zbog navedenih razloga, potrebno je omogućiti dojenčadi sve blagodati prirodne prehrane te svesti hranjenje dojenčadi mlijekom drugih sisavaca, kao i adaptiranom prehranom na minimum. Tijekom gestacije majka i njezino dijete su povezani, a dojenjem se emocionalna povezanost produbljuje i jača. Prvi kontakt novorođenčeta s majkom ključan je za zdrav emocionalni razvoj u djetinjstvu i odrasloj dobi. Potrebno je osigurati povoljne ekonomske, psihosocijalne i kulturne uvjete u suvremenom društvu, smanjiti neinformiranost i negativan stav o dojenju da bi se dojenje provodilo u odgovarajućem vremenskom tijeku i da se izbjegne preuranjena ablaktacija

Kemometričko proučavanje i molekularno modeliranje derivata 1H-indol-3-octene kiseline s auksinskom aktivnošću

Quantitative Structure-Activity Relationship (QSAR) study on 22 1H-indole-3-acetic acid derivatives with auxin activity was performed by means of Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), Partial Least Squares Regression (PLS) and Multiple Linear Regression (MLR). Molecular geometry of the auxins was optimized at MMFF94 and ab initio B3LYP 6-31G** levels. Modeling of complexes of some auxin molecules with the auxin binding protein 1 (ABP1) was also carried out. Parsimonius PLS and MLR models for prediction of optimal and half-optimal auxin concentrations for Avena L. Sativa coleoptile elongation were obtained with 15 auxins in the training set. HCA and PCA on data for the half-optimal concentration exhibit auxin clustering with respect to substitutent type and position, biological activity, and the size of the active site pockets of ABP1. Molecular graphics of ABP1 – NAA derivative complexes and of the coordination spheres around NAA (1-naphthalenic acid) hydrogen atoms in the ABP1 – NAA complex agrees well with the chemometrics/QSAR results.Proučavanje kvantitativnih relacija izme|u strukture i auksinske aktivnosti za 22 derivata 1H-indol-3-octene kiseline sprovedeno je pomoću analize glavnih komponenata (PCA), hijerarhijske grozdaste analize (HCA), regresije parcijalnih najmanjih kvadrata (PLS) i višestruke linearne regresije (MLR). Molekularna geometrija auksina optimizirana je na razini MMFF94 i ab initio B3LYP 6-31G** teorije. Izvršeno je i modeliranje kompleksa nekih auksinskih molekula i auksinskoga proteina 1 (ABP1). Zadovoljavajući modeli PLS i MLR za predvi|anje optimalne i polu-optimalne auksinske koncentracije za produljenje koleoptila Avena L. Sativa dobiveni su pomoću test-skupova s 15 auksina. Analize podataka HCA i PCA za polu-optimalnu koncentraciju klasificirale su auksine s obzirom na vrstu i mjesto supstitucije, biološku aktivnost i veličinu d`epova u aktivnom mjestu proteina ABP1. Molekularna grafika kompleksa ABP1–NAA derivati kao i koordinacijskih sfera oko vodikovih atoma u NAA (1-naftalenska kiselina) dobro se sla`e s kemometričkim i QSAR rezultatima

A Priori Descriptors in QSAR: a Case of Gram-Negative Bacterial Multidrug Resistance to ß-Lactams

Over hundred new a priori global/local molecular descriptors that encoded steric, topological, electronic, hydrogen bonding, compositional and hydrophobic properties were generated for 16 ß-lactams, and two partial least squares regression models were constructed and cross-validated. These a priori models (Q2 > 0.80, R2 > 0.95, SEV < 0.50) are comparable with the previously obtained computed models. ß-Lactam intramolecular and ß-lactam-receptor intermolecular interactions are also discussed in terms of molecular descriptors

Inorganic Sulphur Compounds in the Human Body. II. Thiocyanates.

Sumpor je najzastupljeniji mikroelement u ljudskom tijelu, u obliku mnogobrojnih ne samo organskih već i anorganskih spojeva s različitim ulogama. Ovim pregledom prikazani su anorganski spojevi sumpora iz klase endogenih tiocianatnih spojeva u ljudskom organizmu. Ta se klasa izvodi iz tiocianatnog aniona SCN– ponajprije enzimskim i neenzimskim reakcijama u stanicama ili izvanstaničnom prostoru. SCN– nastaje detoksikacijom endogenih ili egzogenih cianida, djelovanjem endogene bakterijske flore, metabolizmom cianogene hrane ili industrijskom intoksikacijom. Opisani su molekulski i ionski spojevi: tiocianska, izotiocianska, hipotiocianska, (cianido-C)sulfinska i (cianido-C)sulfonska kiselina; soli tih kiselina i aniona 1,2,3-tricianotrisulfida(1–) s najzastupljenijim kationima u organizmu (Na+, K+, Ca2+ i Mg2+); cianotiocianat i bis[(cianido-C)sumpor](S-S) (tiocianogen). Anioni i molekule jesu endogene reaktivne sumporove vrste sa svojstvima pseudohalogena. Nalaze se u značajnim koncentracijama u tjelesnim tekućinama, gdje imaju zaštitne uloge – detoksikacijsku (uklanjanju cianid) i antimikrobne uloge (mikrobicidno i mikrobiostatski djeluju na razne bakterije, na neke viruse, gljivice i parazite). Metabolički su povezani s endogenim okso spojevima sumpora u ljudskom tijelu. Može se očekivati da će istraživanja o opisanoj klasi sumpornih spojeva razjasniti u bliskoj budućnosti njihove molekulske mehanizme djelovanja u ljudskom tijelu. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.Sulphur is the most abundant microelement in the human body, in the form not only of many organic but also of many inorganic compounds with diverse roles. This review presents inorganic sulphur compounds from the class of endogenous thiocyanate compounds present in the human body. The class is primarily produced from the thiocyanate anion SCN– in enzymatic and non-enzymatic reactions in cells or in extracellular matrix. SCN– is formed by detoxication of endogenous or exogenous cyanides, by action of the endogenous bacterial flora, in the metabolism of cyanogenic food, and during industrial intoxication. Molecular and ionic compounds are: thiocyanic, isothiocyanic, hypothiocyanic, (cyanido-C)sulphinic and (cyanido-C)sulphonic acid; salts of these acids and the anion 1,2,3-tricyanotrisulfide(1–) with the most abundant cations in the organism (Na+, K+, Ca2+ and Mg2+); cyano thiocyanate and bis[(cyanido-C)sulphur](S-S) (thiocyanogen). The anions and molecules are endogenous reactive sulphur species with pseudohalogen properties. They exist in significant concentrations in body fluids, in which they have protective roles – detoxication (removal of cyanide) and antimicrobial functions (microbicidal and microbiostatic effect on various bacteria, some viruses, fungi and parasites). They are metabolically coupled with endogenous oxo-sulphur compounds in the human body. It is to be expected that investigations on the described class of sulphur compounds in the near future will explain molecular mechanisms of their action in the human body. This work is licensed under a Creative Commons Attribution 4.0 International License

Inorganic Sulphur Compounds in the Human Body. I. Oxo Compounds.

Sumpor je nakon kalcija i fosfora najzastupljeniji element u ljudskom tijelu, gdje se nalazi u mnogobrojnim anorganskim i organskim spojevima, a u vrlo malim količinama i u elementarnom stanju. U ovom pregledu prikazani su anorganski spojevi sumpora iz klase endogenih okso-spojeva u ljudskom organizmu, koji ponajprije nastaju enzimskim i neenzimskim biosintetskim putevima u stanicama ili izvanstaničnom prostoru. Opisani su sulfati, tiosulfati, μ-disulfido-bis(trioksosulfati)(2–) (tetrationati), sulfiti, hidrogensulfiti, sulfonati i disulfiti najzastupljenijih metala u organizmu (Na+, K+, Ca2+ i Mg2+) i sumporov dioksid. Anioni i SO2 jesu endogene neradikalske sumporove vrste koje se nalaze u znatnim koncentracijama u tjelesnim tekućinama, gdje imaju zasebne fiziološke, patološke, metaboličke, detoksikacijske i druge uloge. Međusobno su povezani metaboličkim putevima sumporovih spojeva. Dok je sulfatni ion redovit sastojak elektrolita i izvor sumpora, tiosulfatni ion ima brojne zaštitne funkcije i važan je metabolit, a anioni nastali reakcijom SO2 i vode također su važni metabolički međuprodukti. Novijim istraživanjima prepoznate su uloge sumporova dioksida kao nove signalne molekule i aniona μ-disulfido-bis(trioksosulfata)(2–), kao metabolita koji se stvara tijekom upale crijeva. Istraživanja o opisanoj klasi sumporovih spojeva i njihovoj važnosti za ljudski organizam očito nisu završena i mogu još donijeti važne i neočekivane spoznaje. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna.Sulphur is, after calcium and phosphorus, the most abundant element in the human body, where it can be found in numerous inorganic and organic compounds, and in very small amounts in elementary state. This review presents inorganic sulphur compounds from the class of endogenous oxo compounds present in the human body, which are primarily produced in enzymatic and non-enzymatic biosynthethic pathways in cells or in extracellular matrix. Sulphates, thiosulphates, μ-disulphido-bis(trioxosulphates)(2–) (tetrathionates), sulphites, hydrosulphites, sulphonates and disulphites of the most abundant metals in the organism (Na+, K+, Ca2+, and Mg2+) as well as sulphur dioxide, are described. The anions and SO2 are endogenous non-radical sulphur species which exist in significant concentrations in body fluids, in which they have specific physiological, pathological, metabolic, detoxifying, and other roles. They are mutually connected by metabolic pathways of sulphur compounds. While the sulphate ion is a common component of electrolytes and is a source of sulphur, the thiosulphate ion has several protective roles and is an important metabolite, and the anions produced by the reaction of SO2 with water are also important metabolic intermediates. Newer researches have identified roles of sulphur dioxide as a novel signal molecule, and of the anion μ-disulphido-bis(trioxosulphate)(2–) as a metabolite generated in intestinal inflammation. Investigations on the described class of sulphur compounds and their roles in the human body are obviously not terminated and therefore, still may bring important and unexpected knowledge. This work is licensed under a Creative Commons Attribution 4.0 International License

Međugeneracijske i spolne razlike u seksualnom životu i upotrebi sredstava ovisnosti

Aim: Explore the habits of sexual life, knowledge, history and addictive substances use, analyze differences and similarities according to sex, age, religion, place of residence, parental education and generation. Methods: 364 random participants (17 - 56 years), visiting the outpatient department of the General hospital Bjelovar from 1st of January to 1st of June 2017. We used two criteria to include a person in the study-non health education occupation and finished high school diploma degree minimum. All subjects gave informed consent. The self-designed anonymous questionnaire contained general socio-demographic questions and those related to sexual behavior and addictive substances use. Results: Significantly more men than women use addictive substances, addictive substances are more often used in urban areas, men are less knowledgeable about sexually transmitted diseases, women have older partners, men have partners of the same age or younger, the age of first sexual intercourse as well as the number of sexual partners and the consumption of addictive substances shifts to through generations to a lower age limit, level of parental education has no protective effect on the risky behavior of participans. Life in rural areas and religious practice can be indicated as a protective factor for risky behavior. Conclusion: The results put new challenges in front of the experts in the humanities and public health areas as they provide insight into the changing sociological phenomena through decades and describe the Croatian society between the phenomena of globalization and retradionalisation. This and similar research may encourage relevant measures of prevention of these trends.Cilj: Istražiti navike seksualnog života, znanje, povijest i uporabu sredstava ovisnosti, analizirati razlike i sličnosti prema spolu, dobi, religiji, mjestu prebivališta, roditeljskom obrazovanju i generaciji. Metode: 364 randomizirana sudionika (u dobi između 17-56 godina), ambulantni pacijenti Opće bolnice Bjelovar od 1 siječnja do 1 lipnja 2017. Koristili smo dva kriterija za uključenje osoba u studiju: ne medicinsku okupaciju i završeno srednje školsko obrazovanje kao minimalni stupanj obrazovanja. Svi sudionici su dali informirani pristanak. Samoispunjavajući anonimni upitnik je sadržavao opća socio-demografska pitanja i ona povezana sa seksualnim ponašanjem i korištenjem sredstava ovisnosti. Rezultati: Značajno je više muškaraca nego žena koristilo sredstva ovisnosti, te su ta sredstva više korištena u urbanim sredinama, muškarci imaju manje znanje o spolno prenosivim bolestima, žene imaju starije partnere, muškarci imaju partnerice iste dobi ili mlađe. Dob prvog spolnog odnosa, kao i broj seksualnih partnera i konzumiranje sredstava ovisnosti prelazi s generacija na nižu dobnu granicu, razina roditeljskog obrazovanja nema zaštitni učinak na rizično ponašanje sudionika. Zaključak: Rezultati postavljaju nove izazove pred stručnjake za humanističke znanosti i javno zdravstvo, jer pružaju uvid u promjenjive sociološke pojave kroz desetljeća i opisuju hrvatsko društvo između pojava globalizacije i retradionalizacije. Ova i slična istraživanja mogu potaknuti odgovarajuće mjere prevencija ovih trendova