Pikisi kwaiyai! (pictures tonight!): The screening and reception of ethnographic film in the Trobriand Islands,Papua New Guinea

Ethnographic films hold great historical value for the communities in which they were filmed, yet people in source communities often lack access to them. Visitors engaging in ‘visual repatriation’ of ethnographic film can enrich both sides of the ethnographic exchange. I review my experiences screening ethnographic films with Trobriand Islanders, their reactions, and the various ways in which local communities regain ownership of these films, including re‐narration and renaming. My findings reiterate how source communities' reception of, and uses for, ethnographic film can sharply differ from the filmmakers' original agenda.     

Intra- and inter-molecular charge transfer: Stark-spectroscopy,photo-induced polarization and pyroeffect in organic films

A transition of an organic molecule from the ground into an excited state is often accompanied by the intra-molecular electronic (or ionic) charge transfer. A degree of this spatial charge transfer may be expressed in terms of the difference between electrical dipole moments of the excited and the ground states. The same is true for the inter-molecular transitions in condensed media, namely, crystals, amorphous films, liquid and solid solutions, etc. The degree of the charge transfer determines the magnitude of various physical effects such as the electro-optical (Stark) effect, optical second harmonic generation, photo-induced polarization, pyro-electric effect and others. The quadratic Stark-effect can be used for a quantitative determination of the charge transfer degree , the other effects can be understood in terms of the charge transfer. This paper is a brief review of various experimental data mostly obtained by the authors which allow the quantitative interpretation using the concept of the charge transfer.     

Isomerization and Racemization of Menthols

The hitherto unknown cyanoacetates of menthol isomers, i.e., (±)-menthyl, (±)- and (+)-neomenthyl, and (±)- and (+)-isomenthyl cyanoacetate, have been prepared. It has been proved to be possible to isolate effectively pure (±)-menthol from optically inactive mixture of isomers through the cyanoacetate, followed by saponification.     

Chitosan film containing fucoidan as a wound dressing for dermal burn healing: Preparation and in vitro/in vivo evaluation

The aim of this study was to develop chitosan film containing fucoidan and to investigate its suitability for the treatment of dermal burns on rabbits. Porous films, thickness between 29.7 and 269.0 μm, were obtained by the solvent dropping method. Water vapor permeability (3.3–16.6/0.1 g), the swelling (0.67–1.77 g/g), tensile strength (7.1–45.8 N), and bioadhesion (0.076–1.771 mJ/cm²) of the films were determined. The thinnest films were obtained with the lowest chitosan concentration (P<.05). The water absorption capacity of the films sharply increased with the freeze-drying technique. The film having the thickness of 29.7 μm showed the highest amount of moisture permeability (16.6 g/0.1 g). Higher chitosan concentration significantly increased tensile strength of the films (P<.05). Using higher concentration of lactic acid made films more elastic and applicable, and these films were selected for in vivo studies. Seven adult male New Zealand white rabbits were used for the evaluation of the films on superficial dermal burns. Biopsy samples were taken at 7, 14, and 21 days after wounding, and each wound site was examined macroscopically and histopathologically. After 7 days treatment, fibroplasia and scar were observed on wounds treated with fucoidan-chitosan film. The best regenerated dermal papillary formation, best reepithelization, and the fastest closure of wounds were found in the fucoidan-chitosan film treatment group after 14 days compared with other treatment and control groups. It can be concluded that fucoidan-chitosan films might be a potential treatment system for dermal burns and that changing formulation variables can modulate the characterizations of the films. Published: May 24, 2007     

A fluorescent biosensor based on acetylcholinesterase and 5-oxazolone derivative immobilized in polyvinylchloride (PVC) matrix

A new 2-phenyl-4-[4-(1,4,7,10-tetraoxa-13-azacyclopentadecyl)benzylidene]-5-oxazolone (CPO) derivative was utilized to develop an optical acetylcholinesterase (AChE) biosensor in which the azlactone derivative was embedded in plasticized polyvinylchloride (PVC) matrix. The sensor system was calibrated for the detection of acetylcholine (ACh) and donepezil which is a competitive cholinesterase (ChE) inhibitor. Two different biosensing systems were developed by using AChE enzyme in solution and immobilized together with the fluorescent derivative (CPO) doped in transparent PVC membrane. The enzymatic hydrolysis of ACh was monitored by following changes in the pH induced fluorescence intensity. When AChE enzyme was immobilized in PVC matrix together with CPO, the sensitivity of the measuring system has increased approximately three times for ACh, in comparison to the sensing system where AChE enzyme was in solution phase.

The photophysical parameters of CPO were also examined in solvents of tetrahydrofuran (THF), acetonitrile (ACN) and dichloromethane (DCM) and in solid matrix of PVC. The azlactone derivative exhibits excellent photostability in PVC matrix.     

Chemical Consequences of Alkali Inhomogeneity in Cu2ZnSnS4 Thin‐Film Solar Cells

This study offers new insight into the role of Na in Cu₂ZnSnS₄ (CZTS) thin film solar cells by studying samples with a spatially varying alkali distribution. This is achieved by omitting a diffusion barrier between the soda‐lime glass substrate and the Mo back contact, where compositional variations of the glass inherently result in non‐uniform alkali distributions in the CZTS. By correlating light beam induced current (LBIC) maps with secondary ion mass spectrometry composition maps, it is shown that samples containing regions of higher Na concentration (“hot spots”) have corresponding LBIC hot spots on comparable length scales. Samples containing an alkali diffusion barrier have lower LBIC dispersion; thus, LBIC can be used to evaluate non‐uniformity in CZTS devices, where a common cause is Na inhomogeneity. Moreover, it is shown that the Na hot spots are strongly correlated with other compositional variations in the device, including increased Cu in‐diffusion with the underlying MoS₂ layer and decreased diffusion of Cd to the back contact. Neither of these effects are well understood in CZTS devices, and neither have previously been correlated with the presence or absence of Na.     

NDI‐Based Small Molecule as Promising Nonfullerene Acceptor for Solution‐Processed Organic Photovoltaics

A novel naphthalene diimide (NDI)‐based small molecule (BiNDI) is designed and synthesized by linking two NDI monomers via a vinyl donor moiety. The electronic structure of BiNDI is carefully investigated by ultraviolet photoelectron spectroscopy (UPS). Density functional theory (DFT) sheds further light on the molecular configuration and energy level distribution. Thin film transistors (TFT) based on BiNDI show a highest electron mobility of 0.365 cm² V^?1 s^?1 in ambient atmosphere. Organic photovoltaics (OPVs) by using BiNDI as the acceptor show a highest power conversion efficency (PCE) of 2.41%, which is the best result for NDI‐based small molecular acceptors. Transmission electron microscopy (TEM), atomic force microscopy (AFM), grazing incidence wide‐angle X‐ray diffraction (GIXD), and X‐ray photo­electron spectroscopy (XPS) characterization to understand the morphology and structure order of the bulk heterojunction film are performed. It is found that small amount of 1,8‐diiodooctane (DIO) (i.e., 0.5%) in the blended film facilitates the crystallization of BiNDI into fibrillar crystals, which is beneficial for the improvement of device performance.     

Hands-on or Video-based Learning with ANTicipation? A Comparative Approach to Identifying Student Motivation and Learning Enjoyment During a Lesson about Ants

The observation of living animals in school laboratories provides authentic views of biological research. Various studies stress the importance of primary experiences in biology classes. However, educational films may serve as an alternative in some cases. The aim of this study was to investigate student motivation before and after treatments, including (1) an educational film, (2) a hands-on activity with living animals accompanied by an educational film and (3) a hands-on activity with living animals. We investigated the influence of teaching method, gender and class level on student motivation and learning enjoyment. In all treatments, Temnothorax ants were addressed, which can be easily kept and observed. This paper is within the scope of a longitudinal project based on the concept of ‘ant research’ in class. Students (N = 140) from six classes (lower and intermediate secondary school levels) participated in the study. Student motivation was measured using a two-stage test design, including a standardised questionnaire on current motivation and a test on learning enjoyment. The findings of this study suggest that the younger students prefer hands-on activities, while students at an intermediate secondary school level are more interested in video-based learning. Since the combination of hands-on activity and video yielded the best results, the potential of using videos as facilitators for hands-on learning is discussed.