Changes in the etch rate of photosensitive polymers as a function of the pulse number

The ablation rates of a polyimide and a triazene polymer were studied gravimetrically by a quartz micro balance for 248-nm and 308-nm irradiation. Special care was taken to examine the dependence of the ablation rate at constant fluences for single pulses and the influence of consecutive pulses at the same position. A clear trend was observed in these measurements, i.e., that the mass loss after the first pulse is always different from values for the following pulses. This implies that it is very difficult to determine true ablation rates, which are the foundation of most ablation models. The differences of the mass loss between the first pulse and the following pulses is most probably due to carbonization of the material, resulting in varying ablation rates for the following pulses. The ablation rates are thus not a real material property but a superposition of the material ablation rates with the ablation rates of carbon and carbonized materia

The influence of KrF excimer laser irradiation on the surface of collagen and collagen/PVP films

The surface properties of collagen and collagen/poly(vinyl pyrrolidone) (PVP) films after KrF excimer laser irradiation (λ=248nm) were investigated by means of the technique of scanning electron microscopy (SEM) and optical microscopy (OM). The laser irradiation of the used specimens caused an expansion of materials above their surface with pronounced sings of its melting. The height of the ablated volume in a case of collagen film at a fluence of 1.1J/cm2 was approximately 5μm. A white damage appears on the treated surfaces at a threshold of 0.5J/cm2 with a single pulse and becomes more visible for a higher fluence. It is also noteworthy that along with increasing fluences (beginning from the fluence of 1.7J/cm2), the characteristic filaments at the spot edges are observed. The local heat and pressure generated by the laser radiation were able to induce bubble formation on the surface. Further bubble colliding and bursting produce a three-dimensional polymer “microfoam” structure with interconnected pores. These results can be of interest for some new applications

HPLC ANALYSIS AND ANTI-INFLAMMATORY PROPERTIES STUDIES OF TRUNK BARKS OF ACACIA NILOTICA VAR ADANSONII (GUILL AND PERR) O KTZE (MIMOSACEAE)

Objective: The objective of this study was to evaluate the in vitro and in vivo anti-inflammatory properties of the aqueous extract and fractions of the trunk bark of Acacia nilotica. Methods: A maceration of the powder of the trunks barks of the plant was realized. Then the aqueous macerate obtained was fractionated with dichloromethane, butanol and ethyl acetate successively. The phenolic compounds of the aqueous extract, butanol and ethyl acetate fractions were identified by HPLC/DAD. Lipoxygenase and phospholipase inhibition tests with the aqueous extract and the butanol and ethyl acetate fractions were carried out. The anti-inflammatory potential of the aqueous extract was assessed in vivo by the anti-edema test with carrageenan and the analgesic test with acetic acid at different doses (200 mg/ml; 400 mg/ml; 600 mg/ml). Aspirin (200 mg/ml) and paracetamol (200 mg/ml) were used as a reference. Results: The HPLC/DAD analysis of the extracts revealed that gallic acid is the most abundant phenol acid in the extracts. The aqueous extract inhibited lipoxygenase (IC50 = 18.32±1.18 μg/ml), phospholipase (11.44±0.32% per 100 μg/ml) and cyclooxygenase (56.48±0.29% for 100 μg/ml) as well as its tested fractions. It also reduced edema and pain in the mice by more than 50% from the 400 mg/ml dose. Conclusion: Aqueous extract of Acacia nilotica has anti-inflammatory properties. Hence its use in traditional medicine in the treatment of inflammation

Trypanocidal and leishmanicidal activity of six limonoids

Six limonoids [kotschyienone A and B (1, 2), 7-deacetylgedunin (3), 7-deacetyl-7-oxogedunin (4), andirobin (5) and methyl angolensate (6)] were investigated for their trypanocidal and leishmanicidal activities using bloodstream forms of Trypanosoma brucei and promastigotes of Leishmania major. Whereas all compounds showed anti-trypanosomal activity, only compounds 1–4 displayed anti-leishmanial activity. The 50% growth inhibition (GI 50) values for the trypanocidal and leishmanicidal activity of the compounds ranged between 2.5 and 14.9 μM. Kotschyienone A (1) was found to be the most active compound with a minimal inhibition concentration (MIC) value of 10 μM and GI 50 values between 2.5 and 2.9 μM. Only compounds 1 and 3 showed moderate cytotoxicity against HL-60 cells with MIC and GI 50 values of 100 μM and 31.5–46.2 μM, respectively. Compound 1 was also found to show activity against intracellular amastigotes of L. major with a GI 50 value of 1.5 μM. The results suggest that limonoids have potential as drug candidates for the development of new treatments against trypanosomiasis and leishmaniasis

Distribution of Potentially toxic elements in Water, Sediment and Soils in the Riparian Zones around a Kraft Pulp and Paper Mill in Western Kenya

This chapter discusses the impact of effluent discharge on the distribution of potentially toxic elements (Pb, Cd, Cu and Zn) in water, sediments and soils near a Kraft mill in Western Kenya. Potentially Toxic Elements (PTEs) concentrations were determined at three sites: Water Intake Point, Effluent Discharge Point and Downstream Point. The mill liquid effluent parameters and gaseous emissions were also characterized. One-way ANOVA was used to analyze the spatial differences in PTEs concentrations. Principal component analysis determined the correlations between the proximity to the Kraft mill and the PTEs in soils, water and sediments. In riverine soils, Cd was 0.78 ± 0.01 mg/kg, while Pb was 94.38 ± 9.65 mg/kg. In sediments, the concentration was 16.81 ± 2.46 mg/kg for Zn, 6.16 ± 0.72 mg/kg for Cd and 75.28 ± 5.97 mg/kg for Pb. In water, Zn was 0.26 ± 0.038 mg/L, Cu was 0.75 ± 0.11 mg/L, Cd was 0.05 ± 0.004 mg/L and Pb was 1.26 ± 9.65 mg/L. The spatial distributions of PTEs in soils near the factory and across the river may have resulted from the factory’s effluent discharge and gaseous emissions. These findings should help formulate more stringent industrial effluent management programs in Western Kenya

Addressing Corporate Ties to Slavery: Corporate Apologia in a Discourse of Reconciliation

Pressured by activists to take responsibility, American corporations recently found themselves in the spotlight for their past ties to slavery. Responding to the issue, they stepped into a complex discourse of reconciliation. Taking a rhetorical approach, this article analyzes the response of Aetna Inc. It explores how corporate rhetoric functions within present discourses about historical injustices and illustrates that Aetna\u27s response informed by common strategies of corporate apologia inhibited meaningful reconciliation. The article thus furthers criticisms of (corporate) apologia in the context of historical injustice and raises questions about the potentialities and limitations of corporate rhetoric for reconciliation

Organizational and Supervisory Apology Effectiveness: Apology Giving in Work Settings

We synthesize the interdisciplinary literature into a heuristic for crafting effective organizational and supervisory apologies (the OOPS four-component apology). In the first experiment, we demonstrate how an offense committed by an organization is perceived to be more egregious than an offense committed by a friend or supervisor. Furthermore, results did not support that OOPS apologies are unequally effective if issued by a friend, supervisor, or organization. In the second experiment, we test OOPS apology-training effectiveness. Results indicated that trained participants crafted more effective apologies. Our apology heuristic is an innovation for training business communicators how to apologize effectively.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Settler state apologies and the elusiveness of forgiveness : The purification ritual that does not purify

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Life satisfaction and resilience in medical school – a six-year longitudinal, nationwide and comparative study

BACKGROUND: This study examined the relationship between life satisfaction among medical students and a basic model of personality, stress and coping. Previous studies have shown relatively high levels of distress, such as symptoms of depression and suicidal thoughts in medical undergraduates. However despite the increased focus on positive psychological health and well-being during the past decades, only a few studies have focused on life satisfaction and coping in medical students. This is the first longitudinal study which has identified predictors of sustained high levels of life satisfaction among medical students. METHODS: This longitudinal, nationwide questionnaire study examined the course of life satisfaction during medical school, compared the level of satisfaction of medical students with that of other university students, and identified resilience factors. T-tests were used to compare means of life satisfaction between and within the population groups. K-means cluster analyses were applied to identify subgroups among the medical students. Analysis of Variance (ANOVA) and logistic regression analyses were used to compare the subgroups. RESULTS: Life satisfaction decreased during medical school. Medical students were as satisfied as other students in the first year of study, but reported less satisfaction in their graduation year. Medical students who sustained high levels of life satisfaction perceived medical school as interfering less with their social and personal life, and were less likely to use emotion focused coping, such as wishful thinking, than their peers. CONCLUSION: Medical schools should encourage students to spend adequate time on their social and personal lives and emphasise the importance of health-promoting coping strategies