A method for computing the partial derivatives of experimental data

This article describes a procedure for obtaining the partial derivatives of experimental data that depend on two independent variables. The starting equation is an ill‐posed integral equation of the first kind. Tikhonov regularization is used to keep noise amplification under control. Implementation of the computation steps is described and the performance of the procedure is demonstrated by four practical examples. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

A self-entanglement mechanism for continuous pulling of carbon nanotube yarns

We report an in situ electron microscopy study of pulling mechanism of super-aligned carbon nanotube (CNT) arrays grown by chemical vapor deposition. The formation of entangled structures at the ends of CNT bundles during pulling is very critical for the pulling process. By cutting the top and bottom layers of both pullable and not pullable CNT arrays, we confirm that the structures at the top or bottom surfaces of the as-grown CNT arrays are not the dominant reason to ensure the continuous pulling process. We have observed the formation of entangled structures when the pulling process approaches the bottom and top ends of the CNT arrays. These entangled structures are responsible for maintaining the continuity of pulling CNTs.     

Ultrafast modulation of optical transitions in monolayer and multilayer graphene

We study ultrafast modulations of absorption spectra for both monolayer and multilayer graphene, by performing time-resolved transmission measurements with tuning probe photon energy. While reduced absorptions by photo-excited carriers are observed in monolayer graphene irrespective of the probe energy, multilayer graphene shows increased absorption at around 0.6 eV, which is explained by the optical transitions between subband states. Intraband carrier relaxation and electron–hole recombination times are found to be as fast as 0.5 and 10 ps, respectively. Modifications of ultrafast carrier dynamics are also studied with changing temperature and excitation density.     

Enhancement of adhesion strength and corrosion resistance of nitrogen or platinum/ruthenium/nitrogen doped diamond-like carbon thin films by platinum/ruthenium underlayer

A platinum/ruthenium (PtRu) underlayer was grown on highly conductive p-Si (100) substrates, on which nitrogen doped diamond-like carbon (N-DLC) thin films without or with incorporation of Pt and Ru (PtRuN-DLC) were deposited, both via a DC magnetron sputtering system. The effect of PtRu underlayer on the bonding structure, surface morphology and adhesion strength of the N-DLC and PtRuN-DLC films was investigated using X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch testing, respectively. The effect of the PtRu underlayer on the corrosion performance of these films in a 0.1 M HCl solution was diagnosed using electrochemical impedance spectroscopy (EIS). Although the incorporation of Pt and Ru into the N-DLC films promoted sp² sites in the films via metal-induced graphitization, the PtRu underlayer along with the incorporation of Pt and Ru in the N-DLC films could enhance the charge transfer resistance of the films, indicating the increased corrosion resistance of the films.     

Mixed solvent system as binder for the production of silicified microcrystalline cellulose-based pellets

Silicified microcrystalline cellulose pellets with hydroxypropyl methylcellullose (HPMC) as modifier were prepared using a mixed solvent as liquid binder. Pellets were produced using extrusion-spheronization with a mixed solvent consisting of water and isopropanol as liquid binder. The key spheronization aid was Prosolv® SMCC 90. Low viscosity grade HPMC was incorporated aiming to modify release of indometacin. Physical characteristics including breaking load, apparent density and flow properties, particle size distribution and shape were determined. Drug loaded pellets were also tested for dissolution profiles. By adjusting liquid binder property, at isopropanol to water ratio of 3.5 to 6.5, pellets of desirable size and shape with reasonable yields were obtained. Pellets exhibited good flow property and they were mechanically strong. Pellet with higher HPMC content displayed a faster drug dissolution profile. This was because low viscosity grade HPMC was not enough to create strong gel. Instead hydration of HPMC molecules increased matrix's hydrophilicity and weakened the structure of pellet faster. The release of indometacin was partly based on the erosion of hydrated matrix. The presence of HPMC in the pellets would require a mixed solvent to produce desirable shape. Incorporation of HPMC had modified drug release from the pellets without further coating. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47924.     

Methyl Ester Sulfonate: A High-Performance Surfactant Capable of Reducing Builders Dosage in Detergents

The detergency performance of α-sulfo fatty-methyl ester sulfonate (α-MES) under different water hardness conditions was compared against the dominant workhorse in Home Care products, linear alkylbenzene sulfonate (LAS). Results demonstrate that α-MES has a higher soil removal index and its detergency performance is not drastically affected by water hardness, compared to that of LAS. The addition of α-MES to LAS also shows an improved cleaning performance and better water hardness resistance, due to the structural characteristics of α-MES, which allow the molecules to be relatively insensitive toward polyvalent ions such as Ca²⁺ and Mg²⁺. The washing performance of α-MES, α-MES/LAS, and LAS with different builders at various dosages was studied, and the results indicated that the dosage of builders in the detergent product could be reduced up to 33% with the application of α-MES, while the detergency is not sacrificed.     

Identification of Protein Markers in Patients Infected with Plasmodium knowlesi,Plasmodium falciparum and Plasmodium vivax

Malaria is caused by parasitic protozoans of the genus Plasmodium and is one of the most prevalent infectious diseases in tropical and subtropical regions. For this reason, effective and practical diagnostic methods are urgently needed to control the spread of malaria. The aim of the current study was to identify a panel of new malarial markers, which could be used to diagnose patients infected with various Plasmodium species, including P. knowlesi, P. vivax and P. falciparum. Sera from malaria-infected patients were pooled and compared to control sera obtained from healthy individuals using the isobaric tags for relative and absolute quantitation (iTRAQ) technique. Mass spectrometry was used to identify serum proteins and quantify their relative abundance. We found that the levels of several proteins were increased in pooled serum from infected patients, including cell adhesion molecule-4 and C-reactive protein. In contrast, the serum concentration of haptoglobin was reduced in malaria-infected individuals, which we verified by western blot assay. Therefore, these proteins might represent infectious markers of malaria, which could be used to develop novel diagnostic tools for detecting P. knowlesi, P. vivax and P. falciparum. However, these potential malarial markers will need to be validated in a larger population of infected individuals.     

The origin of melt-texture crystal growth process in a simple tube furnace

The melt-texture growth (MTG) method has been shown to be effective in fabricating high-T _csuperconducting bulk samples with highly oriented layers of single crystals. The critical current densityJ _cof the typical samples are enhanced significantly. Furthermore, making use of the nonzero spatial temperature gradient at certain locations of a common tube furnace, we fabricated Y-123 bulk samples with various dopants allowingJ _cup to 3.0×10⁴ A cm^–2 in our recent investigations. We followed up our project by analyzing the relations among the crucial parameters involved in the modified version of the MTG process. These parameters include the temperature gradient, the time rate of change of temperature, the growth front of the crystal, etc. Our study indicates that some of the empty space regions that appear between layers are only shallow gap lines. True layers of single crystals do exist, and we present an explanation for the growth of crystal layers along special directions as observed.     

Roles of gastrin and somatostatin in the regulation of gastric acid secretion in the fetal rabbit

In adult gastric epithelium, gastrin and somatostatin regulate parietal cell acid secretion; however, their expression and function in the fetus are largely unknown. We defined the developmental expression of gastrin and somatostatin in the fetal rabbit stomach and determined their effects on fetal acid secretion. To define peptide expression, fetuses from 12 time-mated New Zealand white rabbit does were analyzed at successive ages during the third trimester (term is 31 days). Peptides were extracted from fetal gastric tissue by boiling in water and then in acetic acid. Amidated gastrin and somatostatin levels were measured by radioimmunoassay using antisera 1296 for gastrin and 8402 for somatostatin. To determine the effects of gastrin and somatostatin, pentagastrin (64 microg/kg/hr) or octreotide (35 microg/kg/hr) were infused intravenously in conscious pregnant rabbits at 28 days of gestation for 3 hr. Fetuses (n = 45) were harvested and gastric acid was titrated with 0.02 N NaOH. Gastrin and somatostatin tissue content were 12 +/- 3 and 51 +/- 6 pmol/g at gestational day 20, respectively, and increased to 146 +/- 10 and 162 +/- 5 pmole/g by day 30 (P < 0.05). Between days 24 and 26, when gastric acid was first detectable, the molar ratio of somatostatin to gastrin decreased from 5.0 +/- 1.0 to 1.1 +/- 0.1 (P < 0.05). Fetal gastric acid content (micromole) was 28.5 +/- 1.7 in controls, 27.5 +/- 1.9 with pentagastrin treatment, and 15.8 +/- 1.4 micromole with octreotide (P < 0.05). In summary, 1) In fetal gastric tissue, gastrin increased 12-fold and somatostatin increased 3-fold between days 20 and 30 of gestation. 2) The decreased ratio of somatostatin to gastrin between days 24 and 26 of gestation coincides with the onset of fetal gastric acid secretion in the fetal rabbit. 3) Maternal administration of octreotide inhibited fetal gastric acid content; however, pentagastrin had no effect. We conclude that, in the fetal rabbit stomach, the relative expression of gastrin and somatostatin may regulate the onset of parietal cell acid secretion.