Conjugate two-dimensional electric potential maps

Two dimensional electric potential maps based on voltage detection in conducting paper are common practice in many physics courses in college. Most frequently, students work on `capacitor-like' geometries with current flowing between two opposite electrodes. A `topographical' investigation across the embedding medium (map of equipotential curves) allows to reassure a number of physical properties. This paper focuses on some less common configurations that bear pedagogical interest. We analyze `open-geometries' with electrodes in the form of long strips with slits. They provide a natural groundwork to bring the student to complex variable methods. Aided by this, we show that shaping the conducting paper board one may analyze finite size effects, as well as some meaningful discontinuities in the measured potential. The concept of conjugate electric potentials is exploited. Equipotentials and electric field lines acquire interchangeable roles and may be obtained in complementary `dual' experiments. A feasible theoretical analysis based on introductory complex variables and standardized numerics gives a remarkable quantification of the experimental results.Comment: 15 pages, 8 figure

Sorption of Aldrich Humic Acids onto Hematite: Insights into Fractionation Phenomena by Electrospray Ionization with Quadrupole Time-of-Flight Mass Spectrometry

International audienceSorption induced fractionation of purified Aldrich humic acid (PAHA) on hematite is studied through the modification of electrospray ionization (ESI)quadrupole time-of-flight (QToF) mass spectra of supernatants from retention experiments. The ESI mass spectra show an increase of the “mean molecular masses” of the molecules that constitutes humic aggregates. The low molecular weight fraction (LMWF; m/z ≤ 600 Da) is preferentially sorbed compared to two other fractions. The resolution provided by ESI-QToF mass spectrometer in the low-mass range provided evidence of further fractionation induced by sorption within the LMWF. Among the two latter fractions, the high molecular weight fraction (HMWF; m/z ≈ 1700 Da) seems to be more prone to sorption compared to the intermediate molecular weight fraction (IMWF; m/z ≈ 900 Da). The IMWF seems to be more hydrophilic as it should be richer in O, N and alkyl C from the proportion of even mass, and poorer in aromatic structures from mass defect analysis in ESI mass spectra

Pengaruh Budaya Perusahaan dan Kepemimpinan Transformasional terhadap Kinerja Karyawan Pertamina Ru III Plaju pada Awal Transformasi Pertamina

The purpose of this research is to find out the influence of Corporate Culture and Transformational Leadership partially or jointly to the performance of the Pertamina RU III employee after 5 years Transformation in Pertamina. This study used a descriptive survey method approach. Survey method is a research method in which information is collected through the use of questionnaires. The number of sample were 8 x total of research indicator (14 indicators). The numbers of total sample were 112 respondents, were about 16,5 % of 680 population of Pertamina RU III Plaju. Regarding to the title of this research, the beginning phase was 2008 to 2013, and the population in this study were the employee of Pertamina RU III who have worked at least 5 years. Essential things that must be considered in writing the questionnaire, the determination of the list of questions, as well as the format of the questionnaire design, as well as using infrencial analysis with multiple linear regression analysis model (multiple regression analysis). The results showed that Corporate Culture variable (X1) which partially have a significant influence to the employee performance (Y), and the same thing for Transformational Leadership variable (X2), partially has a significant effect to the employee performance (Y). This is indicated by the significance p-value is smaller than alpha value of 0.05. Furthermore, from the results of the F test (Simultaneous Test), Corporate Culture (X1) and Transformational Leadership (X2) have a significant influence to performance of Pertamina RU III Plaju employee (Y)

Formulasi Sabun Pembersih Kewanitaan (Feminime Hygiene) dari Ekstrak Kulit Buah Durian (Durio Zibethinus Murray)

Sabun pembersih kewanitaan (feminine hygiene) adalah suatu sediaan pembersih daerah kewanitaan berbentuk cair yang dibuat dari bahan dasar dan digunakan untuk membersihkan daerah kewanitaan tanpa menimbulkan iritasi pada kulit. Kulit buah durian mengandung senyawa fenolik, flavonoid, saponin, dan tanin yang dapat digunakan sebagai antijamur. Penelitian ini bertujuan untuk memformulasi sabun pembersih kwanitaan dari ekstrak kulit buah durian.  Jenis penelitian ini adalah eksperimen, dilakukan ekstraksi kulit buah durian secara maserasi menggunakan pelarut etanol 96 %, dan dipekatkan menggunakan rotary evaporator. Formula sabun pembersih kewanitaan dibuat pada konsentrasi 25 % diantaranya formula A, B, dan C dengan konsentrasi asam stearat 7,5%, 8%, dan 8,5%, dan diuji evaluasi fisik yang meliputi uji organoleptik, homogenitas, pH, tinggi busa, dan uji iritasi. Hasil penelitian menunjukkan bahwa sabun pembersih kewanitaan (feminine   hygiene) dari ekstrak kulit buah durian (Durio zibethinus Murray) telah memenuhi syarat uji evaluasi fisik yang stabil yang meliputi uji organoleptik, homogenitas, pH, tinggi busa, dan uji iritasi

Brain–computer interfacing with interactive systems-Case study 2

info:eu-repo/semantics/publishedVersio

Effects of food nutrient content, insect age and stage in the feeding cycle on the FMRFamide immunoreactivity of diffuse endocrine cells in the locust gut

We have studied the influence of variations in dietary protein and digestible carbohydrate content, of insect age and of time during the feeding cycle on the endocrine cells of the ampullar region of the midgut in the African migratory locust Locusta migratoria L. Morphometric analysis of FMRFamide-like immunoreactivity was used as an indirect measure of the amount of FMRFamide-related peptides (FaRPs) stored in the gut endocrine cells. There was a highly significant correlation between FaRP content and the nutritional quality of the food, measured relative to the concentrations and ratio of protein to digestible carbohydrate in a nutritionally optimal diet. The direction of the relationship between FaRP content and diet quality varied with age during the fifth stadium. On day 1, FaRP levels increased with the nutritional quality of the food, while on day 4 the opposite relationship was observed. Release of peptide was triggered by the onset of a meal during ad libitum feeding, with cell FaRP levels returning to premeal values within 15 min of the meal ending. The results also suggested that cell contents were released during food deprivation beyond the normal intermeal interval. Locusts switched for a single meal during ad libitum feeding on day 4 from a low- to a high-carbohydrate food did not respond by reducing endocrine cell FaRP content. Our results show a relationship between the diffuse gut endocrine system and feeding and nutrition in locusts. The ampullar endocrine cells are in three-way contact with the midgut luminal contents, with the primary urine from the Malpighian tubules and with the haemolymph. They are thus ideally positioned to play an integrative receptor-secretory function in the regulation of a variety of post-ingestive processes, such as enzyme secretion, absorption, gut motility or nutrient metabolism

A new type of arthropod photoreceptor

A new type of photoreceptor for the phylum Arthropoda, found in the class Collembola (Arthropoda, Hexapoda) is reported. This new light-sensitive structure consists of a pair of interocular vesicles present in the genus Vesicephalus Richards, 1964 and is anatomically related to the cluster of ommatidia. The absence of a lens, the presence of a rabdome in the upper part of the vesicle and the reflection and refraction of light by a hemolymph bubble with incidence to the rhabdomeric structure are the main traits of this new photoreceptor

Material valorisation of amorphous polylactide. Influence of thermo-mechanical degradation on the morphology, segmental dynamics, thermal and mechanical performance

This paper reports the effects of multiple mechanical recycling on the structure and properties of amorphous polylactide (PLA). The influence of the thermo-mechanical degradation induced by means of five successive injection cycles was initially addressed in terms of macroscopic mechanical properties and surface modification. A deeper inspection on the structure and morphology of PLA was associated to the thermal properties and viscoelastic behaviour. Although FT-IR analysis did not show significant changes in functional groups, a remarkable reduction in molar mass was found by viscometry. PLA remained amorphous throughout the reprocessing cycles, but the occurrence of a cold-crystallization during DSC and DMTA measurements, which enthalpy increased with each reprocessing step, suggested chain scission due to thermo-mechanical degradation. The effect of chain shortening on the glass-rubber relaxation studied by DMTA showed an increase in free volume affecting the segmental dynamics of PLA, particularly after the application of the second reprocessing step, in connection to the overall loss of performance showed by the remaining properties