scholarly journals Impact of instrumental settings in electrospray ionization ion trap mass spectrometry on the analysis of multi-CH3-/CD3-isotopologs in cellulose ether analysis: a quantitative evaluation

2021 ◽  
Author(s):  
Sarah Schleicher ◽  
Inka-Rosalia Lottje ◽  
Petra Mischnick
Keyword(s):  
Electrospray Ionization ◽  
Ion Trap ◽  
Total Concentration ◽  
Degree Of Polymerization ◽  
Polymer Chains ◽  
Molar Ratio ◽  
Cellulose Ether ◽  
Molar Ratios ◽  
Sodium Adducts ◽  
The Impact

AbstractExact quantification of the molar ratios of isotopologous mixed O-methyl-O-methyl-d3-cellooligosaccharides (COS) comprising all combinations from fully methylated to fully deuteromethylated constituents within an individual degree of polymerization (DP) is the key step in the analysis of the substituent distribution over the polymer chains in methyl celluloses (MC). Deuteromethylation of MC is performed to level chemical differences, but due to a m/z range of 3 DP·ΔMe/Me-d3, bias during MS measurement cannot certainly be excluded. Therefore, ionization, ion transportation, and ion storage were studied with an electrospray ionization ion trap mass spectrometer (ESI-IT-MS) using binary equimolar mixtures of per-O-Me- and per-O-Me-d3-COS, defining the border cases of a particular Me/Me-d3-profile. Reference data of their molar ratio were determined after reductive amination with m-amino benzoic acid by HPLC-UV. COS of DP2–6 were measured as their sodium adducts at c = 10−6 M by syringe pump infusion. The impact of the RF voltage of the ion trap (TD), the octopole RF and DC voltages, and the Cap Exit potential on absolute and relative ion intensities were studied. Adapting the Cap Exit voltage was essential for correct quantification of DP2, while all COS of higher DP behaved insensitive with respect to bias. To check whether any bias occurs in the electrospray ionization process of the isotopologs, concentration-dependent measurements were performed with optimized instrumental settings for each DP. Intensity ratios IR = I (Me-d3)/I (Me) did not show any concentration-dependent trend and no selective ion suppression. Its decrease with DP observed under usually applied standard conditions (smart mode) is a consequence of discrimination according to m/z and can be overcome by appropriate instrumental settings of Oct 2 DC and TD. IR between 0.971 ± 0.008 and 1.040 ± 0.009 with no trend for DP (2-6) were obtained by averaging all measurements in the range 2 · 10−7 to 2 · 10−5 M total concentration. The DP-related optimized settings were applied to two MCs and compared with the results obtained under so far applied standard conditions. Graphical abstract

scholarly journals Effect of Aluminum Incorporation on the Reaction Process and Reaction Products of Hydrated Magnesium Silicate

2022 ◽  
Vol 8 ◽  
Author(s):  
Yuan Jia ◽  
Yuxin Zou ◽  
Xinmei Zou ◽  
Yaoting Jiang ◽  
Fangyuan Li ◽  
...  
Keyword(s):  
Aluminum Content ◽  
Magnesium Silicate ◽  
Degree Of Polymerization ◽  
Molar Ratio ◽  
Reaction Products ◽  
Obvious Effect ◽  
Molar Ratios ◽  
Aluminium Ion ◽  
The Impact ◽  
Silicon Oxygen

In this study, we investigated the impact of aluminium ion (Al3+) incorporation on the microstructure and the phase transformation of the magnesium silicate hydrate system. The magnesium silicate hydrate system with aluminium was prepared by mixing magnesium oxide and silica fume with different aluminium ion contents (the Al/Si molar ratios of 0.01, 0.02, 0.05, 0.1, 0.2) at room temperature. The high degree of polymerization of the magnesium silicate hydrate phases resulted in the limited incorporation of aluminium in the structure of magnesium silicate hydrate. The silicon-oxygen tetrahedra sites of magnesium silicate hydrate layers, however, were unable to substitute for silicon sites through inverted silicon-oxygen linkages. The increase in aluminium ion content raised the degree of polymerization of the magnesium silicate hydrate phases from 0.84 to 0.92. A solid solution was formed from residual aluminum-amorphous phases such as hydroxyl-aluminum and magnesium silicate hydrate phases. X-ray diffraction (XRD), field emission scanning electron microscope (F-SEM), and 29Si and 27Al MAS NMR data showed that the addition of Al3+ promotes the hydration process of MgO and has an obvious effect on the appearance of M-S-H gel. The gel with low aluminum content is fluffy, while the gel with high aluminum content has irregular flakes. The amount of Al3+ that enters the M-S-H gel increased with the increase of Al3+ content, but there was a threshold: the highest Al/Si molar ratio of M-S-H gel can be maintained at about 0.006.

Coagulation behavior and floc characteristics of a novel composite poly-ferric aluminum chloride–polydimethyl diallylammonium chloride coagulant with different OH/(Fe3+ + Al3+) molar ratios

2016 ◽  
Vol 74 (7) ◽  
pp. 1636-1643 ◽  
Author(s):  
Cuizhen Sun ◽  
Jinwei Qiu ◽  
Zhibin Zhang ◽  
Taha F. Marhaba ◽  
Yanhao Zhang
Keyword(s):  
Aluminum Chloride ◽  
Dominant Role ◽  
Peak Height ◽  
Synthetic Wastewater ◽  
Molar Ratio ◽  
Floc Size ◽  
Molar Ratios ◽  
Floc Characteristics ◽  
The Impact ◽  
Composite Coagulant

In this paper, flocculating performance and mechanisms of a new composite coagulant, poly-ferric aluminum chloride–polydimethyl diallylammonium chloride (PFAC-PD) with different OH−/(Fe3+ + Al3+) molar ratios, were investigated for humic acid (HA)–kaolin synthetic wastewater treatment. The impact of OH−/(Fe3+ + Al3+) molar ratios on the removal efficiencies of turbidity and dissolved organic carbon, specific UV absorbance, coagulation mechanisms and dynamics was explored during the coagulation process using composite coagulants. The coagulation experimental results revealed that the composite coagulants with lower OH−/(Fe3+ + Al3+) molar ratio exhibited better coagulation efficiency. When OH−/(Fe3+ + Al3+) molar ratio of the composite coagulant was 1.5, adsorption-bridging played a dominant role in coagulating HA–kaolin synthetic wastewater. The floc growth rate and floc size, increased with increasing OH−/(Fe3+ + Al3+) molar ratio and the highest peak height of the size distribution was obtained by PFAC-PD with OH−/(Fe3+ + Al3+) = 1.5. Also, the composite coagulants with higher OH−/(Fe3+ + Al3+) molar ratio formed more compact flocs, as reflected by the higher fractal dimension value. The flocs coagulated by PFAC-PD with basicity value of 1.0 gave strong strength and good recoverability.

Fabrication of rigid polyimide foams with overall enhancement of thermal and mechanical properties

2020 ◽  
pp. 0021955X2095692
Author(s):  
Jianwei Li ◽  
Ni Yu ◽  
Yuanqing Ding ◽  
Tianle Xu ◽  
Guangcheng Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Insulation ◽  
Polymer Chains ◽  
Molar Ratio ◽  
Mechanical And Thermal Properties ◽  
Thermal And Mechanical Properties ◽  
Foaming Agent ◽  
Molar Ratios ◽  
End Capping ◽  
Tetracarboxylic Dianhydride

Polyimide (PI) foams have been developed for decades and widely used as thermal insulation materials. However, the limited mechanical and thermal properties continually being a serious problem that restrict their further applications. In this study, a series of rigid PI foams with excellent mechanical and thermal performance were fabricated by the reaction of benzophenone-3,3',4,4'-tetracarboxylic dianhydride (BTDA) with two diamines of 2–(4-aminophenyl)-5-aminobenzimidazole (BIA) and 4,4'-diaminodiphenyl ether (ODA) with various molar ratios, and the cis-5-norbornene-endo-2,3-dicarbox-ylic acid (NA) was introduced as end-capping and foaming agent. The results demonstrate that the foaming degree decreases with increasing the BIA molar ratio in the polymer chains owing to the elevated melt viscosity of precursor. Furthermore, the prepared rigid PI foams exhibit excellent thermal and mechanical properties. When the BIA contend up to 40 mol%, the glass transition temperature ( Tg) and the temperature at 10% of weight loss ( Td 10 %) of PI foam increased ∼80°C and ∼35°C in comparison with the pristine PI-0, respectively. In addition, the compressive strength and modulus at 10% strain of PI-4 reached to 5.48 MPa and 23.8 MPa, respectively. For the above-mentioned advantages, the prepared rigid PI foams are promising candidates as thermal insulation and structure support composite materials in the aerospace and aviation industries.

scholarly journals Synthesis of Au (III) polyacrylates and study of their tumoricidal activity

2018 ◽  
pp. 98-104
Author(s):  
AV Shibaeva ◽  
NV Pozdniakova ◽  
VV Spiridonov ◽  
MS Smirnova ◽  
DB Korman ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Metal Salt ◽  
Uv Spectroscopy ◽  
Total Concentration ◽  
Biological Properties ◽  
Molar Ratio ◽  
Tumoricidal Activity ◽  
Human Breast Carcinoma Cells ◽  
The Impact

Aurumacryl is an incomplete metal salt of poly(acrylic acid) that exhibits hemostatic activity and inhibits the growth of transplantable carcinomas in vivo. The samples of aurumacryl synthesized following the original technique are insufficiently soluble, which complicates the study of the mechanisms involved in their synthesis and underlying their cytotoxic effect. The aim of this work was to study the impact of the following factors on aurumacryl properties: the molecular weight of the polyacrylate polymer in a range between 2 and 1,000 kDa, the presence of a counterion H+ or Na+, the molar ratio of AuCl– to the polyacrylate polymer (1 : 5 and 1 : 10), the total concentration of the polyacrylate polymer during synthesis (0.1 and 3%), and the type of drying (lyophilization). By comparing the cytotoxicity of aurumacryl samples with significantly different molar ratio of gold ions to the polyacrylate polymer against human breast carcinoma cells (MCF-7), we established that the proportion of the polymer and its molecular weight in the sample do not affect the biological properties of the synthesized substance. Using UV spectroscopy, we revealed that the concentration of Au (III) ions in aurumacryl determines its cytotoxicity.

Thermotropic copolyesters from methylhydroquinone, 4,4'-dipbenyldicarboxylic acid and 2,6-naphthalenedicarboxylic acid

1995 ◽  
Vol 7 (3) ◽  
pp. 303-311 ◽  
Author(s):  
Toshihide Inoue ◽  
Toru Yamanaka ◽  
Norikazu Tabata ◽  
Shigeru Okita
Keyword(s):  
Mechanical Properties ◽  
Polymer Chain ◽  
Packing Density ◽  
Polymer Chains ◽  
Molar Ratio ◽  
Thermal And Mechanical Properties ◽  
Predominant Role ◽  
Chain Packing ◽  
Molar Ratios ◽  
Orientation Function

Copolyesters from methylhydroquinone (Me-HQ), 4,4'-diphenyldicarboxylic acid (BB) and 2,6-naphthalenedicarboxylic acid (NDA) with various molar ratios were prepared and their thermal and mechanical properties were investigated. The modulus of as-spun fibres from Me-HQ/BB/NDA tends to increase as the orientation function of the nematic domains (F value) increases. As-spun fibre from a polymer with a molar ratio m/n=92.5/7.5 showed the highest modulus of 112GPa at F=0,91. However, the injection-moulded specimens did not show the same tendency and the highest modulus of 44 GPa was observed at the lowest F value of 0.56. From these results, it is assumed that the F value plays a predominant role in determining the modulus of the as-spun fibre, whereas other factors, such as rigidity of polymer chain. packing density of polymer chains and melt flowability, determine the modulus of the injection-moulded specimens.

scholarly journals Effects of load types and critical molar ratios on strength properties and geopolymerization mechanism

2021 ◽  
Vol 60 (1) ◽  
pp. 216-222
Author(s):  
Tao Meng ◽  
Sara Ahmed ◽  
Dawang Dai ◽  
Yue Yu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Bending Strength ◽  
Strength Properties ◽  
Degree Of Polymerization ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Loading Patterns ◽  
Load Types ◽  
The Relationship

Abstract In this study, the effect of SiO2/Al2O3 (S/A), Na2O/Al2O3 (N/A) and H2O/Na2O (H/N) molar ratios on bending and compressive strength of geopolymer were investigated. The geopolymerization mechanism was also analyzed from microstructure difference by FTIR. The experimental results showed that compressive strength and bending strength of geopolymer has an opposite reaction under different critical molar ratios. The increase of S/A molar ratio and the decrease of N/A and H/N molar ratios have resulted in an increase of the compressive strength. However, it caused a noticeable decrease in bending strength. The microstructure of geopolymer indicated that the degree of polymerization and cohesion of geopolymer have systematical depending on these critical molar ratios, making the mechanical properties of geopolymer susceptible to different types of loads. This paper reveals the relationship between the microstructure of geopolymer and different mechanical properties and helps to selectively prepare corresponding geopolymer for different loading patterns.

scholarly journals The Impact of AN Contribution on the Thermal Characteristics and Molecular Dynamics of Novel Acrylonitrile–Styrene–Styrene Sodium Sulfonate Terpolymers

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 420
Author(s):  
Hamud A. Altaleb ◽  
Abdullah M. Al-Enizi ◽  
Hany El-Hamshary ◽  
Sayed Z. Mohammady
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Molecular Model ◽  
Thermal Characteristics ◽  
Molar Ratio ◽  
Thermal Stabilities ◽  
Sodium Sulfonate ◽  
Molar Ratios ◽  
Donor Acceptor ◽  
The Impact

We performed a free radical solution polymerization of new acrylonitrile (AN), styrene (St) and styrene sodium sulfonate (SSS) acceptor–donor acceptor monomer systems. The compositions and structures of the produced terpolymers were elucidated using CHNS elemental analysis, and Fourier transform infrared (FTIR) spectroscopies. Three terpolymers candidates were chosen for detailed thermal investigations, where the AN molar ratio varied almost threefold (from ~6.9% to ~17.4%) while the molar ratios of St and SSS varied slightly, at average values around 76.0% and 12.9%, respectively. The glass transition (Tg) values of the terpolymers were measured calorimetrically. In addition, thermal gravimetric analyses (TGA) of the samples were conducted in the temperature range from room temperature to 800 °C. All terpolymers exhibited a single Tg value, indicating random copolymerization of the monomeric species. TGA results revealed that variation of the AN molar ratio had a significant influence on the thermal stabilities of the terpolymers. The impact of AN contribution on the molecular dynamics of the glass transition in the terpolymers was explained quantitatively in a framework of a molecular model.

scholarly journals Photocatalytic Reduction of CO2 to Methanol Using a Copper-Zirconia Imidazolate Framework

Catalysts ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 346
Author(s):  
Sonam Goyal ◽  
Maizatul Shima Shaharun ◽  
Ganaga Suriya Jayabal ◽  
Chong Fai Kait ◽  
Bawadi Abdullah ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Catalyst Support ◽  
Oxidation Potential ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
X Ray ◽  
Molar Ratios ◽  
Optimum Parameters ◽  
Reduction Of Co2 ◽  
Enhanced Yield

A set of novel photocatalysts, i.e., copper-zirconia imidazolate (CuZrIm) frameworks, were synthesized using different zirconia molar ratios (i.e., 0.5, 1, and 1.5 mmol). The photoreduction process of CO2 to methanol in a continuous-flow stirred photoreactor at pressure and temperature of 1 atm and 25 °C, respectively, was studied. The physicochemical properties of the synthesized catalysts were studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The highest methanol activity of 818.59 µmol/L.g was recorded when the CuZrIm1 catalyst with Cu/Zr/Im/NH4OH molar ratio of 2:1:4:2 (mmol/mmol/mmol/M) was employed. The enhanced yield is attributed to the presence of Cu2+ oxidation state and the uniformly dispersed active metals. The response surface methodology (RSM) was used to optimize the reaction parameters. The predicted results agreed well with the experimental ones with the correlation coefficient (R2) of 0.99. The optimization results showed that the highest methanol activity of 1054 µmol/L.g was recorded when the optimum parameters were employed, i.e., stirring rate (540 rpm), intensity of light (275 W/m2) and photocatalyst loading (1.3 g/L). The redox potential value for the CuZrIm1 shows that the reduction potential is −1.70 V and the oxidation potential is +1.28 V for the photoreduction of CO2 to methanol. The current work has established the potential utilization of the imidazolate framework as catalyst support for the photoreduction of CO2 to methanol.

scholarly journals Biogas Dry Reforming for Hydrogen through Membrane Reactor Utilizing Negative Pressure

Fuels ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 194-209
Author(s):  
Akira Nishimura ◽  
Tomohiro Takada ◽  
Satoshi Ohata ◽  
Mohan Lal Kolhe
Keyword(s):  
Energy Source ◽  
Reaction Temperature ◽  
Negative Pressure ◽  
Membrane Reactor ◽  
Reaction Chamber ◽  
Dry Reforming ◽  
Molar Ratio ◽  
Effect Of Pressure ◽  
The Impact

Biogas, consisting of CH4 and CO2, is a promising energy source and can be converted into H2 by a dry reforming reaction. In this study, a membrane reactor is adopted to promote the performance of biogas dry reforming. The aim of this study is to investigate the effect of pressure of sweep gas on a biogas dry reforming to get H2. The effect of molar ratio of supplied CH4:CO2 and reaction temperature is also investigated. It is observed that the impact of psweep on concentrations of CH4 and CO2 is small irrespective of reaction temperature. The concentrations of H2 and CO increase with an increase in reaction temperature t. The concentration of H2, at the outlet of the reaction chamber, reduces with a decrease in psweep. It is due to an increase in H2 extraction from the reaction chamber to the sweep chamber. The highest concentration of H2 is obtained in the case of the molar ratio of CH4:CO2 = 1:1. The concentration of CO is the highest in the case of the molar ratio of CH4:CO2 = 1.5:1. The highest sweep effect is obtained at reaction temperature of 500 °C and psweep of 0.045 MPa.

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