scholarly journals Dispersive evaluation and surface chemistry of advanced, multifunctional silica/lignin hybrid biomaterials

2013 ◽  
Vol 11 (11) ◽  
pp. 1860-1873 ◽  
Author(s):  
Magdalena Nowacka ◽  
Łukasz Klapiszewski ◽  
Małgorzata Norman ◽  
Teofil Jesionowski

AbstractAdvanced silica/lignin hybrid biomaterials were obtained using hydrated or fumed silicas (Aerosil®200) and Kraft lignin as precursors, which is a cheap and biodegradable natural polymer. To extend the possible range of applications, the silicas were first modified with N-2-(aminoethyl)-3-aminopropyltrimethoxsysilane, and then with Kraft lignin, which had been oxidized with sodium periodate. The SiO2/lignin hybrids and precursors were characterised by means of determination of their physicochemical and dispersive-morphological properties. The effectiveness of silica binding to lignin was verified by FT-IR spectroscopy. The zeta potential value provides relevant information regarding interactions between colloid particles. Measurement of the zeta potential values enabled an indirect assessment of stability for the studied hybrid systems. Determination of zeta potential and density of surface charge also permitted the quantitative analysis of changes in surface charge, and indirectly confirmed the effectiveness of the proposed method for synthesis of SiO2/lignin hybrid materials. A particularly attractive feature for practical use is their stability, especially electrokinetic stability. It is expected that silica/lignin hybrids will find a wide range of applications (polymer fillers, biosorbents, electrochemical sensors), as they combine the unique properties of silica with the specific structural features of lignin. This makes these hybrids biomaterials advanced and multifunctional.

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2379 ◽  
Author(s):  
P. Yáñez-Sedeño ◽  
A. González-Cortés ◽  
S. Campuzano ◽  
J. M. Pingarrón

Proper functionalization of electrode surfaces and/or nanomaterials plays a crucial role in the preparation of electrochemical (bio)sensors and their resulting performance. In this context, copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) has been demonstrated to be a powerful strategy due to the high yields achieved, absence of by-products and moderate conditions required both in aqueous medium and under physiological conditions. This particular chemistry offers great potential to functionalize a wide variety of electrode surfaces, nanomaterials, metallophthalocyanines (MPcs) and polymers, thus providing electrochemical platforms with improved electrocatalytic ability and allowing the stable, reproducible and functional integration of a wide range of nanomaterials and/or different biomolecules (enzymes, antibodies, nucleic acids and peptides). Considering the rapid progress in the field, and the potential of this technology, this review paper outlines the unique features imparted by this particular reaction in the development of electrochemical sensors through the discussion of representative examples of the methods mainly reported over the last five years. Special attention has been paid to electrochemical (bio)sensors prepared using nanomaterials and applied to the determination of relevant analytes at different molecular levels. Current challenges and future directions in this field are also briefly pointed out.


2018 ◽  
Author(s):  
Christopher A. Whytock ◽  
Zachary D. Clopton

The Second Circuit held that “when a foreign government, acting through counsel or otherwise, directly participates in U.S. court proceedings by providing a sworn evidentiary proffer regarding the construction and effect of its laws and regulations, which is reasonable under the circumstances presented, a U.S. court is bound to defer to those statements.” In re Vitamin C Antitrust Litigation, 837 F.3d 175, 189 (2d Cir. 2016). This “bound-to-defer” rule is incorrect and unwise.First, the “bound-to-defer” rule is inconsistent with basic American conflict-of-laws principles governing the determination of foreign law. It is inconsistent with Federal Rule of Civil Procedure 44.1’s broad authorization for U.S. courts to “consider any relevant material or source” when determining foreign law. It is inconsistent with the principle that determinations of foreign law should be accurate. And it is inconsistent with the principle of judicial independence in the determination of foreign law.Second, the “bound-to-defer” rule is inconsistent with foreign and international practice. In most other countries, information about foreign law is not binding on courts. Moreover, the world’s two main treaties on the interpretation of foreign law expressly provide that information supplied by foreign governments in accordance with those treaties is not binding on courts. Simply put, foreign governments do not expect each other’s courts to be “bound to defer” to each other’s interpretations of foreign law, much less the interpretation of one executive agency of a foreign government.Third, there are important reasons why deference principles should be kept separate from the principles governing the determination of foreign law. The Second Circuit’s “bound-to-defer” rule would inappropriately delegate to foreign governments power to influence the application of domestic law — and hence the implementation of domestic policy — in a wide range of cases in which the proper application of U.S. law depends on the determination of foreign law. In addition, international comity does not require U.S. courts to defer to foreign governments in the determination of foreign law. International comity is a traditional rationale for choice-of-law rules that require the application of foreign law as a rule of decision under specified circumstances. But in this case, foreign law is at issue because the application of U.S. law depends on the interpretation of foreign law, not because choice-of-law rules require the application of foreign law. Therefore, this case does not implicate the comity rationale for choice-of-law rules. Moreover, the concerns that animate comity doctrines are not the same as those that animate the rules governing the determination of foreign law. The former are concerned with the respect owed between governments, whereas the latter are concerned with ensuring that U.S. courts independently and accurately determine the content of foreign law. In fact, the “bound-to-defer” rule raises issues that are likely to pose significant comity concerns that the ordinary Rule 44.1 approach avoids. U.S. courts can still address comity concerns — separately from their independent determination of foreign law.To be sure, U.S. courts should give respectful consideration to a foreign government’s statements about its law. But as a matter of law, a foreign government’s statements cannot be binding on U.S. courts. Instead, U.S. courts should accurately and independently determine the meaning of foreign law taking into account not only the foreign government’s own statements, but also other relevant information about that law. This independent approach is especially important when — as in this U.S. antitrust case and many other cases — the proper application of American law depends on a determination of foreign law.


2021 ◽  
Vol 887 ◽  
pp. 54-59
Author(s):  
D.O. Perevezentseva ◽  
Eduard V. Gorchakov

Portable electrochemical sensors based on noble metal nanoparticles (МеNPs) for the quantitative determination of hydrogen peroxide (H2O2) and sulfur-containing amino acids (cysteine, methionine, glutathione) are discussed. These sensors have high sensitivity (pM), with low sample requirements (<50 μl). This article discusses methods for producing sensors based on silver and gold nanoparticles and their application in voltammetry. It is shown that the sensitivity of H2O2 determination on a sensor based on silver nanoparticles (AgNPs) depends on their size. Their size is determined by the reducing agent. Sensors based on AgNPs of spherical shape with the smallest size from 0.5 to 17.5 nm have the highest sensitivity for determining H2O2, but a narrow range of determined concentrations. Sensors on medium-sized AgNPs have optimal metrological characteristics. Their size is from 10 to 55 nm, less sensitive, but with a wide range of determined concentrations from 0.1 to 1 nm H2O2. The linearity of the range of glutathione concentrations is 1.0-10.0 pM. The linearity of the range of determined concentrations of methionine is 1–26 рМ.


2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Łukasz Klapiszewski ◽  
Marcin Wysokowski ◽  
Izabela Majchrzak ◽  
Tomasz Szatkowski ◽  
Magdalena Nowacka ◽  
...  

Multifunctional chitin/lignin materials were synthesized. In order to combine mechanical milling of the biopolymers with simultaneous mixing, a centrifugal ball mill was utilized. The resulting materials, differing in terms of the proportions of precursors used, underwent detailed physicochemical and dispersive-morphological analysis. On the basis of FT-IR spectra and results of elemental analysis, the efficiency of the preparation of the materials was determined. The influence of the precursors on the thermal stability of the resulting systems was also evaluated. Zeta potential was determined as a function of pH to describe the electrokinetic stability of aqueous dispersions. This is important for evaluating the utility of the materials and indirectly confirms the effectiveness of the proposed method of synthesis of chitin/lignin products. Measurements were performed to determine basic colorimetric parameters, crucial in the production technology of multiple colored materials. It is expected that chitin/lignin materials will find a wide range of applications (biosorbents, polymer fillers, and electrochemical sensors), as they combine the unique properties of chitin with the specific structural features of lignin to provide a multifunctional material.


2020 ◽  
Vol 32 (1) ◽  
Author(s):  
Christopher B. Hughes ◽  
David M. Brown ◽  
Louise Camenzuli ◽  
Aaron D. Redman ◽  
J. Samuel Arey ◽  
...  

Abstract Under the European REACH regulation, chemicals are assessed for persistence as part of weight-of-evidence determinations of persistence, bioaccumulation and toxicity (PBT), as required under Annex XIII and supported by an Integrated Assessment and Testing Strategy (ITS). This study describes the persistence assessment of phenanthrene, a data-rich polycyclic aromatic hydrocarbon (PAH), in accordance with this framework. All available data from screening and simulation tests, for water, soil and sediment compartments, plus other relevant information, have been compiled. These have been evaluated for reliability and relevance, and a weight-of-evidence determination of persistence has been carried out. Aspects relevant to the assessment, such as degradation metabolites, non-extractable residues (NER), test temperature and bioavailability, have also been considered. The resulting assessment considered a wide range of evidence, including 101 experimental data points. Phenanthrene was demonstrated to be readily biodegradable, a first-tier screen for non-persistence in the ITS. Furthermore, weight-of-evidence assessment of data for water, soil and sediment compartments supported a conclusion of “not persistent” (not P). In non-standard soil studies with sludge-amended soils, longer half-lives were observed. This was attributable to pyrogenic sources of and significantly reduced bioavailability of phenanthrene, highlighting the importance of bioavailability as a major source of variability in persistence data. Available simulation test data for the sediment compartment were found to be unreliable due to the anoxic impact of the use of a biodegradable solvent in a closed system, and were inconsistent with the broader weight of evidence. Estimation of photodegradation using AOPWIN and the APEX model demonstrated this to be an important fate process not currently considered in persistence assessments under REACH. The assessment is not in agreement with a recent regulatory decision in which phenanthrene was determined to be very persistent (vP). This assessment provides a case study for persistence assessment using the REACH ITS and highlights the need for improved guidance to improve consistency and predictability of assessments. This is particularly important for complex cases with data-rich chemicals, such as phenanthrene.


Author(s):  
M. C. Câmara ◽  
A. F. dos Santos ◽  
M. P. Carpentier

A method for explicit Wiener–Hopf factorization of 2 × 2 matrix-valued functions is presented together with an abstract definition of a class of functions, C(Q1, Q2), to which it applies. The method involves the reduction of the original factorization problem to certain nonlinear scalar Riemann–Hilbert problems, which are easier to solve. The class C(Q1, Q2) contains a wide range of classes dealt with in the literature, including the well-known Daniele–Khrapkov class. The structure of the factors in the factorization of any element of the class C(Q1, Q2) is studied and a relation between the two columns of the factors, which gives one of the columns in terms of the other through a linear transformation, is established. This greatly simplifies the complete determination of the factors and gives relevant information on the nature of the factorization. Two examples suggested by applications are completely worked out.


2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Magdalena Nowacka ◽  
Damian Ambrożewicz ◽  
Teofil Jesionowski

The results of studies involving the innovative TiO2-SiO2/Ph-POSS hybrid were presented. An inorganic TiO2-SiO2oxide composite was precipitated from an emulsion media. The functionalisation of surface for the obtained composite was carried out with the use of TriSilanolPhenyl POSS (Ph-POSS) and a silane coupling agent—phenyltrimethoxysilane (PTMS). Electrokinetic and physicochemical as well as structural characteristics of obtained hybrids were evaluated. The zeta potential value has been determined, which provides relevant information regarding the interactions between colloid particles. Measurement of the zeta potential values allowed for an indirect assessment of stability for the studied hybrid fillers. In the next step, the degree of dispersion and surface morphology were evaluated based on the obtained particle size distribution curves and TEM images. The hydrophilic-hydrophobic character of the surface was assessed by analysing the wettability profiles. The modification degree of the TiO2-SiO2oxide composite was evaluated based on the infrared spectroscopy studies (FT-IR). Determination of the parameters of the porous structure was conducted by determining the specific surface area and the total volume and mean size of pores. Thermogravimetric measurements (TGA) were also carried out in order to measure the changes in sample mass as a function of temperature.


2017 ◽  
Vol 17 ◽  
pp. 245-252
Author(s):  
V. V. Somov

In carrying out an investigation into the explosion, among others, the investigative version of the use of a single-use reactive grenade launcher is being considered. The most common for criminal explosions are applied grenade launchers RPG-18, RPG-22, RPG-26. Their use is due to a number of such properties as small size and weight, which makes it possible to transfer them covertly, the range of the shot significantly exceeding the range of the hand grenade throw, the high detonating effect of the rocket grenade explosion. The single-use rocket launchers are generally of the same design. Their differences are in the features of the components construction and dimensional characteristics, which are given in the article. On the basis of expert practice, details ofgrenade launchers that remain at the site of the explosion and have the least damage are determined. These details are the objects of investigation of the explosion technical expertise. These objects include launchers of grenade launchers and rocket parts ofjet grenades. The design features of the launchers, their dimensional characteristics and marking symbols make it possible to determine their belonging to a specific type of jet grenade launchers. Missile parts of jet grenades differ in the form of the combustion chamber of the jet engine, nozzle, in the size ofthe outlet section of the nozzle, in the form and size of the stabilizerfeathers. To determine the belonging of the rocket part of the grenade to a specific type ofjet grenade launcher, it’s necessary to establish a set of structural features and dimensional characteristics. At considerable damage of the combustion chamber of the jet engine, as a rule, the nozzle block remains intact that allows to define diameter of critical section of a nozzle, and on it to establish type of the used single-use grenade launcher.


TAPPI Journal ◽  
2016 ◽  
Vol 15 (5) ◽  
pp. 331-335 ◽  
Author(s):  
LEBO XU ◽  
JEREMY MYERS ◽  
PETER HART

Retention of cationic dispersed rosin size was studied via turbidity measurements on stock filtrate with different alum and dispersed rosin size dosages. Stock charge characteristics were analyzed using both an analysis of charge demand determined via a streaming current detector and an evaluation of zeta potential of the fibers by streaming potential measurement. The results indicated that an optimum amount of alum existed such that good sizing retention was maintained throughout a wide range of dispersed rosin size dosages. However, when an excessive amount of alum was used and fines and colloidal particles were transitioned from anionic to cationic, the cationic size retention was reduced. Laboratory results were confirmed with a paper machine trial. All data suggested that a stock charge study was necessary to identify optimal alum dosage for a cationic dispersed rosin sizing program.


2017 ◽  
Vol 15 (1) ◽  
pp. 21
Author(s):  
Haryo Suganda ◽  
Raja Muhammad Amin

This study is motivated the identification of policies issued by the regional Governmentof Rokan Hulu in the form of Regulatory region number 1 by 2015 on the determination of thevillage and Indigenous Village. Political dynamics based on various interests against themanufacture of, and decision-making in the process of formation of the corresponding localregulations determination of Indigenous Villages in the Rokan Hulu is impacted to a verysignificantamount of changes from the initial draft of the number i.e. 21 (twenty one) the villagebecame Customary 89 (eighty-nine) the Indigenous Villages who have passed. Type of thisresearch is a qualitative descriptive data analysis techniques. The research aims to describe theState of the real situation in a systematic and accurate fact analysis unit or related research, aswell as observations of the field based on the data (information). Method of data collectionwas done with interviews, documentation, and observations through fieldwork (field research).The results of the research on the process of discussion of the draft local regulations andmutual agreement about Designation of Indigenous Villages in the Rokan Hulu is, showed thatthe political dynamics that occur due to the presence of various political interests, rejectionorally by Villagers who were judged to have met the requirements of Draft Regulations to beformulated and the area for the set to be Indigenous Villages, and also there is a desire fromsome villages in the yet to Draft local regulations in order to set the Indigenous village , there isa wide range of interests of these aspects influenced the agreement to assign the entire localVillage which is in the Rokan Hulu become Indigenous village, and the village of Transmigrationinto administrative Villages where the initiator of the changes in the number of IndigenousVillages in the Rokan Hulu it is the desire of the local Government of its own.


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