Unique Formulas Research Articles

Complementary Ionization Techniques for the Analysis of Scotch Whisky by High Resolution Mass Spectrometry.

Fourier transform mass spectrometry (FTMS) is widely used to characterize the chemical complexity of mixtures, such as natural organic matter (NOM), petroleum, and agri-food products (including Scotch whisky). Although electrospray ionization (ESI) is by far the most widely used ionization source in these studies, other ionization techniques are available and may offer complementary information. In a recent study, we found matrix free laser desorption/ionization (LDI) to be effective for the analysis of Suwannee river fulvic acid (SRFA), and to provide complementary chemical insights. In this study, LDI along with atmospheric pressure photoionization (APPI) and atmospheric pressure chemical ionization (APCI) were compared to ESI for the analysis of Scotch whisky. High mass accuracy (54 ppb, mean) allowed for the assignment of 86% of peaks, with 3993 unique molecular formulas identified from four representative samples analyzed. All four ionization techniques, performed in negative mode, identified thousands of formulas. Many were unique to each ionization source, while 699 formulas were common to all techniques. Ions were identified in both deprotonated and radical anion forms. Our study highlights the importance of a multi-ionization source approach; we recommend that analysis of complex mixtures, especially novel ones, should not be limited solely to ESI.

Machine Learning and Energy Minimization Approaches for Crystal Structure Predictions: A Review and New Horizons

Predicting crystal structure has always been a challenging problem for physical sciences. Recently, computational methods have been built to predict crystal structure with success but have been limited in scope and computational time. In this paper, we review computational methods such as density functional theory and machine learning methods used to predict crystal structure. We also explored the breadth versus accuracy of building a model to predict across any crystal structure using machine learning. We extracted 24 913 unique chemical formulas existing between 290 and 310 K from the Pearson Crystal Database. Of these 24 913 formulas, there exists 10 711 unique crystal structures referred to as entry prototypes. Common entries might have hundreds of chemical compositions, while the vast majority of entry prototypes is represented by fewer than ten unique compositions. To include all data in our predictions, entry prototypes that lacked a minimum number of representatives were relabeled as “Other”. By selecting the minimum numbers to be 150, 100, 70, 40, 20, and 10, we explored how limiting class sizes affected performance. Using each minimum number to reorganize the data, we looked at the classification performance metrics: accuracy, precision, and recall. Accuracy ranged from 97 ± 2 to 85 ± 2%; average precision ranged from 86 ± 2 to 79 ± 2%, while average recall ranged from 73 ± 2 to 54 ± 2% for minimum-class representatives from 150 to 10, respectively.

In-depth molecular characterization and biodegradability of water-extractable organic nitrogen in Erhai Lake sediment.

Dissolved organic nitrogen (DON) constitutes a significant fraction of the total dissolved nitrogen content of most aquatic systems and is thus a major nitrogen source for bacteria and phytoplankton. The present work applied Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to a compound-level analysis of the depth-dependent molecular composition of water-extractable organic nitrogen (WEON) in lake sediment. The study focused on Erhai Lake, China. It was found that a large portion (from 16.33 ± 7.87 to 39.54 ± 5.77%) of the WEON in the lake sediment was reactive under cultivation by algal or bacteria. The WEON in the mid-region of Erhai sediment particularly exhibited a lower bioavailability, having been less affected by the basin environment. The FT-ICR MS results revealed the presence of thousands of compounds in the Erhai Lake sediment samples collected at different depths, with the N-containing compounds accounting for 28.3-34.4% of all the compounds. The WEON molecular weight was also observed to increase with increasing sediment depth. A van Krevelen diagram showed that the lignin-type components were dominant (~ 56.2%) in the sediment WEON, contributing to its stabilization and reducing the risk of sediment nutrient release. The FT-ICR MS results further revealed 204 overlapping formulas of WEON for each core sediment sample, attributable to the presence of refractory components. It was observed that 78.4% of the formulas were within the lignin-like region, suggesting unique allochthonous DON sources. The aliphatic component proportion of all the unique formulas was also found to increase with increasing sediment depth. This indicates that, with the development and evolution of the Erhai Basin, the more labile WEON components were transformed into more stable lignin-like substrates, with a positive effect on the Lake Erhai ecosystem. Graphical abstract ᅟ.

Elementos para un proceso de reconciliación sostenible

La reconciliación es uno de los retos principales a los que se enfrentan los países que salen de una situación de conflicto armado. Este es un proceso largo y complejo que supone recordar el pasado, rediseñar el presente y construir el futuro. El objetivo de este documento es hacer una reflexión en torno a los elementos que son necesarios tener en cuenta para un proceso de reconciliación sostenible en el que sea posible la atención de las víctimas, el cierre del ciclo de la violencia y la construcción de una paz estable y duradera. Para ello, se sigue la propuesta de John Paul Lederach quien desarrolla la idea de un marco integrado de reconciliación basado en tres ejes de coordenadas: el tiempo y los objetivos a corto, mediano y largo plazo; las dimensiones o ámbitos de acción (jurídica, psicológica y estructural); y los diferentes niveles de la sociedad (nivel político, medio y de las bases). Se concluye diciendo que no existen fórmulas únicas y satisfactorias de construcción de la paz en una sociedad. Los tiempos que se manejan, los mecanismos que se implementan y los actores que intervienen varían de una realidad o otra. Sin embargo, la idea de reconciliación como proceso integral es y debe ser la esencia para el éxito y la sostenibilidad de la paz.Publicación en línea: 11 diciembre 2017

Parsing Excel formulas: A grammar and its application on 4 large datasets

AbstractSpreadsheets are popular end user programming tools, especially in the industrial world. This makes them interesting research targets. However, there does not exist a reliable grammar that is concise enough to facilitate formula parsing and analysis and to support research on spreadsheet codebases. This paper presents a grammar for spreadsheet formulas that can successfully parse 99.99% of more than 8 million unique formulas extracted from 4 spreadsheet datasets. Our grammar is compatible with the spreadsheet formula language, recognizes the spreadsheet formula elements that are required for supporting spreadsheets research, and produces parse trees aimed at further manipulation and analysis. Additionally, we use the grammar to analyze the characteristics of the formulas of the 4 datasets in 3 different dimensions: complexity, functionality, and data utilization. Our results show that (1) most Excel formulas are simple, however formulas with more than 50 functions or operations exist, (2) almost all formulas use data from other cells, which is often not local, and (3) a surprising number of referring mechanisms are used by less than 1% of the formulas.

Understanding Interdependency Through Complex Information Sharing

The interactions between three or more random variables are often nontrivial, poorly understood and, yet, are paramount for future advances in fields such as network information theory, neuroscience and genetics. In this work, we analyze these interactions as different modes of information sharing. Towards this end, and in contrast to most of the literature that focuses on analyzing the mutual information, we introduce an axiomatic framework for decomposing the joint entropy that characterizes the various ways in which random variables can share information. Our framework distinguishes between interdependencies where the information is shared redundantly and synergistic interdependencies where the sharing structure exists in the whole, but not between the parts. The key contribution of our approach is to focus on symmetric properties of this sharing, which do not depend on a specific point of view for differentiating roles between its components. We show that our axioms determine unique formulas for all of the terms of the proposed decomposition for systems of three variables in several cases of interest. Moreover, we show how these results can be applied to several network information theory problems, providing a more intuitive understanding of their fundamental limits.

Reinvestigation of the Nitration of Tri­chloroethene – Subsequent Reactions of the Products and Evaluation of Their Anti­microbial and Antifungal Activity

AbstractThe nitration reaction of trichloroethene (1) to main products trichloronitroethene (TCNiE 2, up to 60.8 %, by GC), 1,1,2,2‐tetrachloro‐1‐nitroethane (8, up to 25.1 %, by GC), and 1,2,2‐trichloro‐2‐nitroethyl [chloro(nitro)methylene]azinate (9, up to 8.0 %, by GC) was comprehensively investigated and optimized. Different 1,1‐diamino‐2‐chloro‐2‐nitroethenes, 2‐nitroethoxyguanidines, and rare O‐(1,2,2‐trichloro‐2‐nitroethyl) oximes and carbimidoyl halides with unique formulas R–O–N=C(NO2)NRR1 and R–O–N=C(Hal)NRR1, respectively, were obtained from these nitration products in yields up to 91 %. The structure of (E)‐morpholino(nitro)methanone O‐(1,2,2‐trichloro‐2‐nitroethyl) oxime (19) was proven by single‐crystal X‐ray diffraction analysis. In addition, the antimicrobial and antifungal activity of the synthesized compounds was examined. Notably, N‐(1,2,2‐trichloro‐2‐nitroethoxy)‐3,4‐dihydroisoquinoline‐2(1H)carbimidoyl chloride (27) inhibited the growth of methicillin‐resistant and sensitive Staphylococcus aureus with minimum inhibitory concentrations of 1.3 μg mL–1, and reduced the viability of the MCF‐7 cancer cell line with an IC50 of 0.2 μg/mL.

Ultrafast PubChem searching combined with improved filtering rules for elemental composition analysis.

A new and improved software tool for elemental composition annotation of molecular ions detected in mass spectrometry, based on improved filtering rules followed by ultrafast querying in publicly available compound databases, is provided. Pubchem is used as a general source of 1.3 million unique chemical formulas. A plant metabolomics database containing ca. 100,000 formulas is used as a source of naturally occurring compounds. Four modes with different sets of rules for heuristic filtering of candidate formulas coming from elemental composition analysis are incorporated and tested on both databases. The elemental composition analysis is then coupled to ultrafast PubChem searching based on a mass-indexed intermediate system. The performance of the filters is compared and discussed. When reactive compounds are assumed not to be present, 99.95% of the 1.3 million PubChem formulas is correctly found, while ca. 30% less formulas per mass are given compared to previously published rules. For the ca. 100,000 plant metabolomics based formulas, 100% fit the improved rules.

Student Strategies Suggesting Emergence of Mental Structures Supporting Logical and Abstract Thinking: Multiplicative Reasoning

For many students, developing mathematical reasoning can prove to be challenging. Such difficulty may be explained by a deficit in the core understanding of many arithmetical concepts taught in early school years. Multiplicative reasoning is one such concept that produces an essential foundation upon which higher‐level mathematical thinking skills are built. The purpose of this study is to recognize indicators of multiplicative reasoning among fourth‐grade students. Through cross‐case analysis, the researcher used a test instrument to observe patterns of multiplicative reasoning at varying levels in a sample of 14 math students from a low socioeconomic school. Results indicate that the participants fell into three categories: premultiplicative, emergent, and multiplier. Consequently, 12 new sublevels were developed that further describe the multiplicative thinking of these fourth graders within the categories mentioned. Rather than being provided the standard mathematical algorithms, students should be encouraged to personally develop their own unique explanations, formulas, and understanding of general number system mechanics. When instructors are aware of their students' distinctive methods of determining multiplicative reasoning strategies and multiplying schemes, they are more apt to provide the most appropriate learning environment for their students.

Deciphering aromaticity in porphyrinoids via adaptive natural density partitioning.

The adaptive natural density partitioning (AdNDP) method has been applied for the first time to porphyrinoids in order to describe their aromaticity. The analysis of π-electron system reveals that aromaticity of annulene originates from 6-π-electron delocalization, while aromaticity of porphyrin can be better described in terms of local aromaticities of the appended 6-π-electron pyrrolic heterocycles and 6-π-electron central fragment. The patterns of chemical bonding for porphyrinoids obtained by AdNDP are consistent with chemical intuition and lead to unique and compact graphic formulas.

Unique and Explicit Formulas for Green's Function in Three-Dimensional Anisotropic Linear Elasticity

Unique, explicit, and exact expressions for the first- and second-order derivatives of the three-dimensional Green's function for general anisotropic materials are presented in this paper. The derived expressions are based on a mixed complex-variable method and are obtained from the solution proposed by Ting and Lee (Ting and Lee, 1997,“The Three-Dimensional Elastostatic Green's Function for General Anisotropic Linear Elastic Solids,” Q. J. Mech. Appl. Math. 50, pp. 407–426) which has three valuable features. First, it is explicit in terms of Stroh's eigenvalues pα (α=1,2,3) on the oblique plane with normal coincident with the position vector; second, it remains well-defined when some Stroh's eigenvalues are equal (mathematical degeneracy) or nearly equal (quasi-mathematical degeneracy); and third, they are exact. Therefore, both new proposed solutions inherit these appealing features, being explicit in terms of Stroh's eigenvalues, simpler, unique, exact and valid independently of the kind of degeneracy involved, as opposed to previous approaches. A study of all possible degenerate cases validate the proposed scheme.

Nutritional Delivery in Infants With CKD: Techniques to Avoid Hyperkalemia

asachelatingagentfor potassium. 3 Ithasbeenshownhistorically in the laboratory as well as in the use of this technique that by adding sodium polystyrene to liquid-based formulas one can reduce the potassium in the solution, making the clinical risk of hyperkalemia less of an issue in children. This paper points out that the younger the child, the more likely that the nutrition will be a formula that is based intheliquidform.Theyalsopointedoutthatthesechildren are polydipsic. Therefore, they take more than the usual amount of fluid for nutritional growth. Therefore, despite using a low-potassium formula (breast milk, PM 60/40), becauseof the polydipsia, theresult may ne excessive potassium intake with hyperkalemia. In older children and adults, it is easy to talk about a lowpotassium diet because the food is solid; however, in infants on liquid-based formula it is very difficult. These authors have followed through on studies that were conducted more than 2 decades ago looking at potassium-reducing techniques. They also acknowledge that there areother ways to deliver nutrition by unique formulas other than just the infant formulas. However,thebasisofthisissueishowtogiveoptimalnutritiontoaninfantwithchronicrenalfailurewhileavoiding hyperkalemia and potentially avoiding or postponing the need for dialysis. Aggressive nutrition is important for a cerebral growth, somatic growth, and an overall long-term benefit for the patient. 4 Therefore, the use of nutrition restriction may prevent hyperkalemia; however,it most likely results in negative neurologic and somatic growth in these infants, which has potential long-term implications. The Seattle group describes in clinical findings what was describedbyourgroupover2decadesago:homogenizingsodium polystyrene with formula and allowing the formula to settleout.Thisleavesaresinlayeratthebottomoftheformula, and when decanted the formula has an approximate 50% reduction in potassium. They pointed out that there is an effect on the calcium and creatinine of these patients. Whereas the creatinine has no clinical consequences, chelating out the calcium (sodium polystyrene is a nonspecific cation binder) may place the child at risk for long-term, low-calcium exposure. They further note that this will give sodium back to the patient, which in some patients may be detrimental, but in most patients with dysplasia it may be beneficial. Work by Hobbs and associates identified the use of noninfant formulas as a way to deliver low-potassium formula in infants. 5 Hobbs notes that these ‘‘adult-based formulas’’ may need to be diluted to avoid too large of an osmolal load. The Seattle group discusses that their experience with Hobbs’ approach was not always tolerated because of the formula hyperosmolality. The optimal formula, the optimal way to deliver nutrition, and the optimal amount of nutrition for infants with chronic kidney failure is still elusive. The Seattle group’s work and work by many others have identified these ongoing concerns. How can one deliver optimal nutrition and avoid the need for dialysis? For if one can have an infant grow, avoiding the risk of solute excess, then the infantmaybeabletogounder transplantationpreemptively

Insights into dissolved organic matter complexity in rainwater from continental and coastal storms by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry

Abstract. A series of seven rainwater samples were collected in Wilmington, North Carolina USA originating from both continental and coastal storms and analyzed by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). This data set is unique in that it represents a detailed comparison of the molecular level composition of DOM in rainwater collected from distinctly different air mass back trajectories by FT-ICR MS. Approximately 25% of the roughly 2000 assigned CHO molecular formulas are unique to a single storm classification indicating the importance of air mass back trajectory on the composition of rainwater dissolved organic matter (DOM). Analysis of the unique molecular formula assignments highlighted distinct groupings of various bio- and geo-molecule classes with coastal storms containing unique formulas representative of lignin and cellulose-like formulas while continental storms had lipid-like formulas. A series of 18 distinct methylene oligomers were identified in coastal storms and 13 unique methylene oligomers in continental storms, suggesting oligomer formation is ubiquitous in rainwater albeit different for each storm classification. Oligomers of small acids and C3H4O2 were detected in both storm types indicating their processing may be similar in both back trajectories. Condensed aromatic hydrocarbons were detected in continental storms with phenol moieties that are not as oxidized as similar compounds detected in aquatic DOM.

Characterization of dissolved organic matter from a Greenland ice core by nanospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Nanospray ionization Fourier transform ion cyclotron resonance mass spectrometry was developed as a tool for examining the dissolved organic matter (DOM) present in ice cores, significantly reducing the sample volume required for extraction compared with previous studies. Using smaller sample volumes is important for resolving temporal changes in ice-core DOM. We demonstrate that a small volume of ice-core meltwater can be extracted and analyzed with sufficient mass spectral sensitivity to describe the molecular composition of the DOM. Two different solid-phase extraction resins (PPL and C18) were compared to examine potential fractionation of the DOM. Over 2500 unique molecular formulas isolated from two different Greenland ice-core samples, dated to approximately AD 1660 and AD 1360, were obtained from the analyses. Method and sensitivity improvements provide an opportunity for organic matter characterization at higher temporal resolution than our previous analyses afforded and allows for examination of ice cores containing low levels of organic carbon.

Two-loop maximal unitarity with external masses

We extend the maximal-unitarity method at two loops to double-box basis integrals with up to three external massive legs. We use consistency equations based on the requirement that integrals of total derivatives vanish. We obtain unique formulas for the coefficients of the master double-box integrals. These formulas can be used either analytically or numerically.

Characterization of dissolved organic matter from a Greenland ice core by nanospray ionization Fourier transform ion cyclotron resonance mass spectrometry

AbstractNanospray ionization Fourier transform ion cyclotron resonance mass spectrometry was developed as a tool for examining the dissolved organic matter (DOM) present in ice cores, significantly reducing the sample volume required for extraction compared with previous studies. Using smaller sample volumes is important for resolving temporal changes in ice-core DOM. We demonstrate that a small volume of ice-core meltwater can be extracted and analyzed with sufficient mass spectral sensitivity to describe the molecular composition of the DOM. Two different solid-phase extraction resins (PPL and C18) were compared to examine potential fractionation of the DOM. Over 2500 unique molecular formulas isolated from two different Greenland ice-core samples, dated to approximately AD 1660 and AD 1360, were obtained from the analyses. Method and sensitivity improvements provide an opportunity for organic matter characterization at higher temporal resolution than our previous analyses afforded and allows for examination of ice cores containing low levels of organic carbon.

Low Molecular Weight Components in an Aquatic Humic Substance As Characterized by Membrane Dialysis and Orbitrap Mass Spectrometry

Suwannee River fulvic acid (SRFA) was dialyzed through a 100-500 molecular weight cutoff dialysis membrane, and the dialysate and retentate were analyzed by UV-visible absorption and high-resolution Orbitrap mass spectrometry (MS). A significant fraction (36% based on dissolved organic carbon) of SRFA passed through the dialysis membrane. The fraction of SRFA in the dialysate had a different UV-visible absorption spectrum and was enriched in low molecular weight molecules with a more aliphatic composition relative to the initial SRFA solution. Comparison of the SRFA spectra collected by Orbitrap MS and Fourier transform ion cyclotron resonance MS (FT-ICR MS) demonstrated that the mass accuracy of the Orbitrap MS is sufficient for determination of unique molecular formulas of compounds with masses <600 Da in a complex mixture, such as SRFA. The most intense masses detected by Orbitrap MS were found in the 100-200 Da mass range. Many of these low molecular masses corresponded to molecular formulas of previously identified compounds in organic matter, lignin, and plants, and the use of the standard addition method provided an upper concentration estimate of selected target compounds in SRFA. Collectively, these results provide evidence that SRFA contains low molecular weight components that are present individually or in loosely bound assemblies.

Neutral theory for life histories and individual variability in fitness components.

Individuals within populations can differ substantially in their life span and their lifetime reproductive success but such realized individual variation in fitness components need not reflect underlying heritable fitness differences visible to natural selection. Even so, biologists commonly argue that large differences in fitness components are likely adaptive, resulting from and driving evolution by natural selection. To examine this argument we use unique formulas to compute exactly the variance in life span and in lifetime reproductive success among individuals with identical (genotypic) vital rates (assuming a common genotype for all individuals). Such individuals have identical fitness but vary substantially in their realized individual fitness components. We show by example that our computed variances and corresponding simulated distribution of fitness components match those observed in real populations. Of course, (genotypic) vital rates in real populations are expected to differ by small but evolutionarily important amounts among genotypes, but we show that such differences only modestly increase variances in fitness components. We conclude that observed differences in fitness components may likely be evolutionarily neutral, at least to the extent that they are indistinguishable from distributions generated by neutral processes. Important consequences of large neutral variation are the following: Heritabilities for fitness components are likely to be small (which is in fact the case), small selective differences in life histories will be hard to measure, and the effects of random drift will be amplified in natural populations by the large variances among individuals.

Divine Concord

Divine Concord

A source location algorithm of lightning detection networks in China

Abstract. Fast and accurate retrieval of lightning sources is crucial to the early warning and quick repairs of lightning disaster. An algorithm for computing the location and onset time of cloud-to-ground lightning using the time-of-arrival (TOA) and azimuth-of-arrival (AOA) data is introduced in this paper. The algorithm can iteratively calculate the least-squares solution of a lightning source on an oblate spheroidal Earth. It contains a set of unique formulas to compute the geodesic distance and azimuth and an explicit method to compute the initial position using TOA data of only three sensors. Since the method accounts for the effects of the oblateness of the Earth, it would provide a more accurate solution than algorithms based on planar or spherical surface models. Numerical simulations are presented to test this algorithm and evaluate the performance of a lightning detection network in the Hubei province of China. Since 1990s, the proposed algorithm has been used in many regional lightning detection networks installed by the electric power system in China. It is expected that the proposed algorithm be used in more lightning detection networks and other location systems.