Average SWCNT bundle length estimated by resistance measurement

The length of single-walled carbon nanotubes (SWCNTs) affects the optoelectronic and mechanical properties of macroscopic SWCNT layers. Modern methods are capable to measure the length of short nanotubes, and also require complex sample preparation procedures. In this work we show that the average length of SWCNTs can be estimated by measuring the resistance of randomly oriented SWCNTs array. We observe the change in the slope of the resistance dependence on the distance between the contacts with the interval between 100 and 200 μm. The change of resistance slope indicates a change in the path of current flow through the SWCNT. The change in the conduction path can be associated with the “effective bundle length”, which should be related to the average nanotube length. Thus, we have demonstrated a simple and quick technique to measure SWCNT bundle length, which can be used in-situ and does not require special sample preparation.

Non-destructive analysis of drug distribution in nonwovens as drug-delivery systems for biomedical applications

Analysis of the active ingredient distribution of medical devices is typically performed using Raman spectroscopy, a method that is fast and inexpensive [1]. In addition, it offers the advantage of non-destructive analysis without the need for special sample preparation. Assuming that all components are Raman-active and present in sufficient quantities, their distribution can be well represented. The drug distribution in dexamethasone-loaded polymer nonwovens was investigated in order to draw conclusions on the quality of the fleece batches and to make predictions for the release behavior. In the present study, dexamethasone (DMS), a glucocorticoid was used as the active ingredient. Qualitative and quantitative studies of the content of DMS in polymer films by means of Raman spectroscopy have already been carried out in the working group [2]. A representative square section was examined to describe the distribution of active ingredients. The required number of measurement points (spectra) was determined earlier [2].

Single Laboratory Validation to Extend the Scope of AOAC Official Method 2015.06 to Indian Infant, Child and Adult Nutritional Matrices

Background AOAC 2015.06 is a Final Action Official Method for the determination of 12 elements (Na, Mg, P, K, Ca, Cr, Mn, Fe, Cu, Zn, Se, and Mo) in infant formula and adult nutritional products, based on inductively coupled plasma-mass spectrometry (ICP-MS). Currently its scope does not include certain kinds of formulations used in India. The method would likely be used more in Indian laboratories if its performance were characterized on the Indian matrices. Objective In this study we describe a typical Single Laboratory Validation (SLV) exercise designed to characterize the precision and accuracy of AOAC 2015.06 for common Indian nutritional matrices so that the scope of the method can be extended to include them. Methods Six matrices specific to the Indian markets were carried through an SLV and the Standard Method Performance Requirements (SMPR) previously published for this method were used to evaluate the results. Results The method demonstrated typical repeatability (<5% RSD), and intermediate precision (5–8% RSD) on the Indian matrices, with very few exceptions. Accuracy was demonstrated by overspike recoveries in the range of 90–110% over three days for the Indian matrices, as well as excellent agreement with previously published results for three additional matrices tested. Some of the new Indian matrices required alternate sample preparation procedures vs. the usual reconstitution prescribed by the SMPRs. Conclusions and Highlights The SLV results showed that AOAC 2015.06 can be extended to include these Indian matrices. The two special sample preparation procedures can now be considered validated.

Study of the influence of interfering ions of heavy metals and various sample preparation on the determination of mercury impurity in protamine sulfate by stripping voltammetry

Aim. To determine the content of mercury in protamine sulfate samples with different sample preparation. To study the effect of interfering ions on the content of mercury impurity in protamine sulfate by stripping voltammetry (SV). Materials and methods. We used a solution for injection of protamine sulfate, batches 515091, 514062, 514111; for sample preparation — various options for dilution and precipitation. Dilution was carried out with bidistilled water, and the precipitation of proteins — with sodium tungstate in 2 options. Mercury impurities were determined by the SV method. Results. The mercury content in protamine sulfate samples was 0.000417 ± 0.00140 and 0.000420 ± 0.00152 mg/l when diluted with water 1 : 2 and 1 : 1 respectively and 0.000462 ± 0.00131 and 0.000459 ± 0.00121 when precipitated with tungstate in options 1 and 2 respectively. With the addition of an interfering ion, for example, Cu2+, the content of mercury in the medicinal product was 0.000606 ± 0.00015, 0.000452 ± 0.00013 and 0.0004212 ± 0.00011 mg/l for protamine sulfate batches 514062, 515091 and 514111 respectively, which does not exceed the values determined by the product specification. The addition of Pb2+, Fe2+, Zn2+, Cu2+, and Cd2+ ions also had no effect on the determination of the mercury content in protamine sulfate samples. Conclusion. To determine the mercury impurity in the protamine sulfate, special sample preparation is not required. Ions of Cu2+, Pb2+, Fe2+, Cd2+, Zn2+ do not affect the result of determining the mercury content in protamine sulfate samples by the SV method, which indicates a high selectivity of the method used.

Influence of Interstitial Oxygen on the Tribology of Ti6Al4V

Titanium alloys are used for their good mechanical and corrosion properties, but generally experience poor wear behavior. This can effectively be counteracted by a thermal oxidation treatment, reducing wear significantly. Employing a special sample preparation, we study the transition of tribological properties between thermally oxidized and bulk Ti6Al4V on a single sample. While oxygen signal intensity and hardness followed an exponential decay from the surface to bulk material, tribological results showed a step-like transition from low to high friction and wear with increasing distance from the surface. Low wear was associated with minor abrasive marks, whereas high wear showed as severe adhesive material transfer onto the steel counter body. Besides the mechanical property of hardness, also a change in fracture behavior by interstitial oxygen could influence the observed tribological behavior.

Non-destructive analysis of drug content in polymer coatings with Raman spectroscopy

The analysis of device drug content typically is carried out by means of chromatographic methods such as high performance liquid chromatography (HPLC) or liquid chromatography-mass spectrometry (LCMS). These approved methods are particularly fast, cost-efficient and ubiquitous in chemical-analytical laboratories. However, these quantitative methods necessitate the drug being eluted, which represents a destructive process. A novel alternative to these well-established methods [1, 2] is the Raman spectroscopy, which is fast and cost-efficient, as well [3]. Additionally, it offers the advantage of nondestructive analysis without the need for a special sample preparation. Within the current investigation we applied Raman spectroscopy for the qualitative and quantitative analysis of dexamethasone (DMS), a glucocorticoid, incorporated in a silicone matrix. The investigation was conducted in a rectangular area on the sample surface. The required number of measuring points (spectra) was determined. Calibration was performed with samples containing different amounts of DMS. The evaluation of Raman spectra is based on the analysis of the peak areas of the bands at 795 rel. cm-1(silicone) and 1,663 rel. cm-1(DMS). Remarkably, next to a precise overview of DMS distribution, an exact and reproducible quantification of incorporated DMS could be obtained.

Validation of the R-Biopharm AG RIDASCREEN® Histamine (Enzymatic) Kit

Background: RIDASCREEN® Histamine (enzymatic) is an enzymatic test kit for quantification of histamine in fresh fish, canned fish, fish meal, cheese, and wine. Methods: Fish products are extracted with boiling water, while cheese is extracted with water, and the extract is treated with perchloric acid/potassium hydroxyde. Wine is extracted with the reagents of RIDA® Sample Decolorant kit to eliminate color pigments and interfering compounds. The enzymatic determination is based on histamine dehydrogenase, which catalyzes the oxidative deamidation of histamine in the presence of an electron carrier that converts a dye to a color product. The resulting color intensity is directly proportional to histamine concentration and is measured at 450 nm. The substrates are coated on the microtiter plate. Results: The linear range is from 1 to 20 mg/L in the extract. LOQs are 2 mg/kg for fresh fish, canned fish, and cheese, 1.4 mg/L in wine, and 10 mg/kg for fish meal. The linear range is from 5 to 100 mg/kg for fish products and cheese, 3.6 to 72 mg/L for wine, and 25 to 500 mg/kg for fish meal. Recovery and precision are very good for all matrices, and comparisons with HPLC reference methods revealed that the method also delivers true results for fish products and wine. Agmatine shows a low side activity of around 0.75% at 10 g/kg. Possible interfering substances are ascorbic acid (more than 250 mg/L in wine or 250 mg/kg in fish). A special sample preparation to deplete ascorbic acid from fresh fish is described.

STUDY OF THE INFLUENCE OF THE MASS FRACTION OF FREE FATTY ACIDS AND PHOSPHOLIPIDS, EXHIBITING ACIDIC PROPERTIES, FOR NUCLEAR MAGNETIC RELAXATION CHARACTERISTICS OF SUNFLOWER LECITHINS

Изучено влияние массовой доли содержащихся в лецитинах компонентов, проявляющих кислотные свойства, на их ядерно-магнитные релаксационные (ЯМР) характеристики для выявления возможности использования указанных характеристик в качестве аналитического параметра определения кислотного числа лецитинов. В качестве объектов исследования взяты подсолнечные лецитины с различными кислотными числами: 17,8; 24,1 и 30,1 мг КОН/г, значения которых обусловлены различной массовой долей содержащихся в лецитинах свободных жирных кислот (3,5; 4,7 и 5,5% соответственно) и фосфолипидов, проявляющих кислотные свойства, (10,5; 12,0 и 13,0% соответственно). Установлено, что значения ни одной из ЯМР характеристик (время спин-спиновой релаксации и амплитуды сигналов ядерной магнитной релаксации) протонов лецитинов не могут быть выбраны в качестве аналитического параметра для определения кислотного числа, так как они не зависят от кислотного числа лецитинов. На основании полученных данных сделан вывод, что для определения кислотного числа лецитинов с применением импульсного метода ядерного магнитного резонанса необходима специальная пробоподготовка образца лецитина, позволяющая обеспечить: во-первых, различия в значениях ЯМР характеристик протонов свободных жирных кислот и протонов триацилглицеринов, содержащихся в масле, выделенном из лецитина; во-вторых, различия в значениях ЯМР характеристик протонов фосфолипидов, проявляющих кислотные свойства, и протонов других групп фосфолипидов, содержащихся в лецитине. The aim of the research was to study the effect of the mass fraction of components exhibiting acidic properties contained in lecithins on their NMR characteristics in order to identify the possibilities of using these characteristics as an analytical parameter for determining the acid number of lecithins. Sunflower lecithins with different acid numbers were taken as objects of study: 17,8; 24,1 and 30,1 mg KOH/g, the values of which are due to different mass fractions of free fatty acids (3,5; 4,7 and 5,5%, respectively) and different mass fractions of phospholipids, exhibiting acidic properties (10,5; 12,0 and 13,0%, respectively) contained in lecithins. It was established that the values of none of the NMR characteristics – times of spin-spin relaxation and amplitudes of NMR signals of protons of lecithins can not be selected as an analytical parameter for determining the acid number, since they do not depend on the acid number of lecithins. Based on the obtained data, it was concluded that to determine the acid number of lecithins using the pulsed method of nuclear magnetic resonance, special sample preparation of a sample of lecithin is necessary, which allows to ensure, first, differences in the NMR values of the characteristics of free fatty acid protons and triacylglycerol protons contained in oil extracted from lecithin, and, secondly, the differences in the NMR values of the characteristics of protons of phospholipids, exhibiting acidic properties, and protons of other phospho groups lipids contained in lecithin.

Cryo-SOFI enabling low-dose super-resolution correlative light and electron cryo-microscopy

Correlative light and electron cryo-microscopy (cryo-CLEM) combines information from the specific labeling of fluorescence cryo-microscopy (cryo-FM) with the high resolution in environmental context of electron cryo-microscopy (cryo-EM). Exploiting super-resolution methods for cryo-FM is advantageous, as it enables the identification of rare events within the environmental background of cryo-EM at a sensitivity and resolution beyond that of conventional methods. However, due to the need for relatively high laser intensities, current super-resolution cryo-CLEM methods require cryo-protectants or support films which can severely reduce image quality in cryo-EM and are not compatible with many samples, such as mammalian cells. Here, we introduce cryogenic super-resolution optical fluctuation imaging (cryo-SOFI), a low-dose super-resolution imaging scheme based on the SOFI principle. As cryo-SOFI does not require special sample preparation, it is fully compatible with conventional cryo-EM specimens, and importantly, it does not affect the quality of cryo-EM imaging. By applying cryo-SOFI to a variety of biological application examples, we demonstrate resolutions up to ∼135 nm, an improvement of up to three times compared with conventional cryo-FM, while maintaining the specimen in a vitrified state for subsequent cryo-EM. Cryo-SOFI presents a general solution to the problem of specimen devitrification in super-resolution cryo-CLEM. It does not require a complex optical setup and can easily be implemented in any existing cryo-FM system.

Special Sample Preparation Methodology for Cu Pillar Bump Characterization on Advance Thin Small Leadless Flip Chip with Copper Pillar Bump Interconnect Technology

Today, copper pillar bumping now in high volume production for mobile electronics is also a transformative technology for next generation flip chip [1] interconnects which offers advantages in many designs while meeting current and future requirements. With the continuous shrinking dimensions of semiconductor devices, the package’s design and size are approaching the dimensions of the singulated die. Moreover, failure analysis involving copper pillar packages would be the major challenges faced by analysts as copper pillar devices in nature hides its solder joints beneath its die causing obstruction in quality inspection as well as judging its solder joint strength. Chemical wet etch or deprocessing [2] by using potassium hydroxide (KOH) to remove all silicon die have disadvantages of over etching on silicon substrate and tin (Sn) surrounding the Cu pillar. Therefore, quality of sample preparation is critical and new methodology is needed.