KM-408, a novel phenoxyalkyl derivative as a potential anticonvulsant and analgesic compound for the treatment of neuropathic pain.

BACKGROUND: Epilepsy frequently coexists with neuropathic pain. Our approach is based on the search for active compounds with multitarget profiles beneficial in terms of potential side effects and on the implementation of screening for potential multidirectional central activity. METHODS: Compounds were synthesized by means of chemical synthesis. After antiseizure and neurotoxicity screening in vivo, KM-408 and its enantiomers were chosen for analgesic activity evaluations. Further safety studies included acute toxicity in mice, the effect on normal electrocardiogram and on blood pressure in rats, whole body plethysmography in rats, and in vitro and biochemical assays. Pharmacokinetics has been studied in rats after iv and po administration. Metabolism has been studied in vivo in rat serum and urine. Radioligand binding studies were performed as part of the mechanism of action investigation. RESULTS: Selected results for KM-408: Ki sigma = 7.2*10-8; Ki 5-HT1A = 8.0*10-7; ED50 MES (mice, ip) = 13.3 mg/kg; formalin test (I phase, mice, ip)-active at 30 mg/kg; SNL (rats, ip)-active at 6 mg/kg; STZ-induced pain (mice, ip)-active at 1 mg/kg (von Frey) and 10 mg/kg (hot plate); hot plate test (mice, ip)-active at 30 mg/kg; ED50 capsaicin test (mice, ip) = 18.99 mg/kg; tail immersion test (mice)-active at 0.5%; corneal anesthesia (guinea pigs)-active at 0.125%; infiltration anesthesia (guinea pigs)-active at 0.125%. CONCLUSIONS: Within the presented study a novel compound, R,S-2-((2-(2-chloro-6-methylphenoxy)ethyl)amino)butan-1-ol hydrochloride (KM-408) with dual antiseizure and analgesic activity has been developed for potential use in neuropathic pain treatment.

Depression and workaholism in undergraduates: Examining gender as a moderator.

Introduction: This study aims to examine the association between depression and workaholism among university students. Methods: Participants were 182 undergraduates at a large university in the South of Poland, aged between 20-28 years old (M = 22.17, SD = 1.39), including 102 women (56%). The cross-sectional study used the Beck Depression Inventory (BDI) and the Work Addiction Risk Test (WART). Results: This study shows that depression and workaholism levels are significantly lower in Physical Education students than other faculties' students. Gender moderates the relationship between workaholism and depression. Women demonstrate a stronger association between depression and workaholism than men. Conclusions: Both physical activity and gender appear to play an essential role in mental health prevention. The result of this study should be considered in therapy and prevention programs at university campuses.

[Selected personality dimensions and occupational burnout in the group of professional and volunteer firefighters]. / Wybrane wymiary osobowosci a wypalenie zawodowe w grupie strazaków zawodowych i ochotników.

BACKGROUND: The purpose of this research was to examine the relationships between selected personality dimensions and occupational burnout among professional and volunteer firefighters. Difficult conditions are the cause of loss of not only health but also life. Such working conditions may cause occupational burnout consisting of employee's exhaustion. MATERIAL AND METHODS: The group under examination consisted of 164 firefighters, including 76 volunteers aged 19-61 years (M = 32.49, SD = 9.21) and 88 professional firefighters aged 20-49 years (M = 33.85, SD = 10.05). This research employed the Maslach Burnout Inventory and Gough and Heilburn's Adjective Check List along with the Personality and Axiological Model (MOA) (competences, relations, autonomy). RESULTS: The results of the conducted research indicate differences between the examined groups of firefighters in personality dimensions (Ord: t = -2.739, p = 0.006; Mls: t = -2.159, p = 0.032; competences t = -2.390, p = 0.017). The research also enabled assessing the correlations with occupational burnout. The greatest relationship with occupational burnout in the group of volunteer firefighters concerns succorance (Suc) and total occupational burnout, and the greatest relationship with occupational burnout in the group of professional firefighters pertains to the competence dimension from the MOA model. CONCLUSIONS: The results of the conducted research should be related to the cognitive aspect (the application of the new MOA model in this professional group) and attention should be paid to the personality differences between the groups of volunteer and professional firefighters. The application value for more effective work of psychologists with this professional group is also important in terms of the results obtained. Med Pr. 2021;72(5):509-19.

Comparative Quantitative Study of Ardisiacrispin A in Extracts from Ardisia crenata Sims Varieties and Their Cytotoxic Activities.

Ardisia crenata Sims (Primulaceae) occurs in natural habitats in two varieties, bearing red or white fruits. While roots of the red-berried ardisia are valued as a medicinal product, the pharmacological activity of which is attributed to triterpene saponins, including ardisiacrispin A, data on the white-berried variety are scarce. A TLC-densitometric method was developed and validated to estimate the levels of saponins, calculated as ardisiacrispin A, in different plant parts in both varieties. Their content amounted to 22.17±4.75 and 25.72±1.46 mg/g d.w. in roots, and 2.64±0.74 and 3.43±0.70 mg/g d.w. in fruits of red-berried and white-berried ardisia, respectively. Assessment of cytotoxicity of ardisiacrispin A and A. crenata extracts on a panel of human cancer cell lines revealed a similar effect of root extracts from both varieties, with the highest potency against melanoma WM793 and colon cancer Caco2. Thus, roots of the white-berried variety may be treated as a substitute for red-berried ardisia and serve as an alternative source for the acquisition of plant material rich in bioactive saponins.

ALK ligand ALKAL2 potentiates MYCN-driven neuroblastoma in the absence of ALK mutation.

High-risk neuroblastoma (NB) is responsible for a disproportionate number of childhood deaths due to cancer. One indicator of high-risk NB is amplification of the neural MYC (MYCN) oncogene, which is currently therapeutically intractable. Identification of anaplastic lymphoma kinase (ALK) as an NB oncogene raised the possibility of using ALK tyrosine kinase inhibitors (TKIs) in treatment of patients with activating ALK mutations. 8-10% of primary NB patients are ALK-positive, a figure that increases in the relapsed population. ALK is activated by the ALKAL2 ligand located on chromosome 2p, along with ALK and MYCN, in the "2p-gain" region associated with NB. Dysregulation of ALK ligand in NB has not been addressed, although one of the first oncogenes described was v-sis that shares > 90% homology with PDGF. Therefore, we tested whether ALKAL2 ligand could potentiate NB progression in the absence of ALK mutation. We show that ALKAL2 overexpression in mice drives ALK TKI-sensitive NB in the absence of ALK mutation, suggesting that additional NB patients, such as those exhibiting 2p-gain, may benefit from ALK TKI-based therapeutic intervention.

Development and Validation of Stability-Indicating HPLC Methods for the Estimation of Lomefloxacin and Balofloxacin Oxidation Process under ACVA, H2O2, or KMnO4 Treatment. Kinetic Evaluation and Identification of Degradation Products by Mass Spectrometry.

The oxidation of lomefloxacin (LOM) and balofloxacin (BAL) under the influence of azo initiator of radical reactions of 4,4'-azobis(4-cyanopentanoic acid) (ACVA) and H2O2 was examined. Oxidation using H2O2 was performed at room temperature while using ACVA at temperatures: 40, 50, 60 °C. Additionally, the oxidation process of BAL under the influence of KMnO4 in an acidic medium was investigated. New stability-indicating HPLC methods were developed in order to evaluate the oxidation process. Chromatographic analysis was carried out using the Kinetex 5u XB-C18 100A column, Phenomenex (Torrance, CA, USA) (250 × 4.6 mm, 5 µm particle size, core shell type). The chromatographic separation was achieved while using isocratic elution and a mobile phase with the composition of 0.05 M phosphate buffer (pH = 3.20 adjusted with o-phosphoric acid) and acetonitrile (87:13 v/v for LOM; 80:20 v/v for BAL). The column was maintained at 30 °C. The methods were validated according to the ICH guidelines, and it was found that they met the acceptance criteria. An oxidation process followed kinetics of the second order reaction. The most probable structures of LOM and BAL degradation products formed were assigned by the UHPLC/MS/MS method.

Preferences of Physical Education Profiles Among Polish Adolescents.

The purpose of this study was to examine the association of the preferred profiles of physical education (PE) classes with gender and school level among Polish adolescents. In the cross-sectional survey study, 1,340 Polish students (including 50% of girls) attending middle and high schools, aged between 13 and 19 years, participated. The participants selected one of four preferred profiles of PE classes. The majority (n = 845, 63%) of students participated in PE for "fun-pleasure-entertainment," whereas only one third of students (n = 419, 31%) preferred "exercise-sweat-fitness" as a profile of PE classes. The preference for "fun-pleasure-entertainment" decreased about 41% for boys and 31% for high school students. A preference for "exercise-sweat-fitness" increased about 56% for men and 31% for high school students. Teachers should comply with students' preferences related to PE profiles, organizing PE classes in more fun-related forms for girls and in more exercise-related forms for boys. The proportions of these two preferred profiles of PE classes should turn across adolescence, increasing exercise-related forms and decreasing those fun-related ones.

KM-416, a novel phenoxyalkylaminoalkanol derivative with anticonvulsant properties exerts analgesic, local anesthetic, and antidepressant-like activities. Pharmacodynamic, pharmacokinetic, and forced degradation studies.

Anticonvulsant drugs are used to treat a wide range of non-epileptic conditions, including chronic, neuropathic pain. We obtained a phenoxyalkylaminoalkanol derivative, KM-416 which had previously demonstrated a significant anticonvulsant activity and had also been shown to bind to 5-HT1A, α2-receptors and SERT and not to exhibit mutagenic properties. As KM-416 is a promising compound in our search for drug candidates, in the present study we further assessed its pharmacological profile (analgesic, local anesthetic, and antidepressant-like activities) accompanied with patch-clamp studies. Considering the importance of drug safety, its influence on the cardiovascular system was also evaluated. Moreover, KM-416 was subjected to forced degradation and pharmacokinetic studies to examine its stability and pharmacokinetic parameters. KM-416 revealed a significant antinociceptive activity in the tonic - the formalin test, neurogenic - the capsaicin test, and neuropathic pain model - streptozotocin-induced peripheral neuropathy. Moreover, it exerted a local anesthetic effect. In addition, KM-416 exhibited anti-depressant like activity. The results from the patch-clamp studies indicated that KM-416 can inhibit currents elicited by activation of NMDA receptors, while it also exhibited a voltage-dependent inhibition of Na+ currents. KM-416 did not influence ventricular depolarization and repolarization. Following oral administration, pharmacokinetics of KM-416 was characterized by a rapid absorption in the rat. The brain-to-plasma AUC ratio was 6.7, indicating that KM-416 was well distributed to brain. The forced degradation studies showed that KM-416 was very stable under stress conditions. All these features made KM-416 a promising drug candidate for further development against neuropathic pain and epilepsy.

Unrealistic Optimism in the Time of Coronavirus Pandemic: May It Help to Kill, If So-Whom: Disease or the Person?

Objective: The results of numerous empirical studies have showed the occurrence of so-called unrealistic optimism. Thus, we aimed to investigate whether in the situation of an imminent coronavirus pandemic, people would still perceive themselves as being less exposed to the disease than others. Methods: Survey studies were conducted to examine the level of unrealistic optimism. Participants (n = 171, 67.3% of women) in a subjective way judged the risk of their coronavirus infection and the likelihood that this would happen to an average student of the same sex from their class. The survey was conducted in three waves: prior to the announcement of the first case of coronavirus (2-3 March), immediately after that announcement (5-6 March), and a few days later (9-10 March). Results: We showed that women estimated the chances of being infected as significantly higher (M = 4.52, SD = 2.079; t = 2.387; p = 0.018; Cohen's d = 0.393) than men (M = 3.71, SD = 2.042). The phenomenon of unrealistic optimism was observed especially in men (as compared to other male participants) as it appeared in all three measures (M (you) = 3.95 vs. M (other male student) = 4.63; M = 3.71 vs. M = 4.68, and M = 4.46 vs. M = 5.38 in phase one, two, and three, respectively; p 0.006 for all comparison), but also in women in the last two measures (M(you) = 4.55 vs. M (other female student) = 4.95, and M = 4.99 vs. M = 5.38 in phase 2 and 3, respectively; p 0.012 for both comparisons). Conclusions: The study revealed a fairly general occurrence of unrealistic optimism, which was mainly observed in men as it appeared in all three measures, but also in women in the last two measures. This result is important for health experts who are responsible for making people comply with regulations concerning social distancing, putting masks on to stop infection, and staying at home. It is possible that unrealistically optimistic people will behave much less in line with the aforementioned recommendations, causing coronavirus to spread widely.

The mediating effect of self-efficacy on the relationship between health locus of control and life satisfaction: A moderator role of movement disability.

BACKGROUND: Self-efficacy and health locus of control are widely recognized as psychological factors related to life satisfaction. However, little is known about the mechanisms of the decrease in life satisfaction in disabled people. OBJECTIVE/HYPOTHESIS: The aim of the present study was to clarify the relationship between health locus of control (HLOC) and life satisfaction in people with acquired mobility impairment in comparison to a non-disabled sample, and to specify how self-efficacy interacts with these components. We hypothesized that self-efficacy is a mediator between HLOC and life satisfaction, and that disability moderates this relationship. METHODS: The cross-sectional study included a total of 120 participants (including 50% women) aged between 18 and 63 years (M = 33.33, SD = 9.55), and consisting equally of disabled and non-disabled persons. Data were collected using the Satisfaction With Life Scale (SWLS), the Multidimensional Health Locus of Control (MHLC), and the General Self-Efficacy Scale (GSES). RESULTS: Consistent with most previous research, the results of this study indicate that life satisfaction decreased in persons with an acquired mobility impairment when compared to non-disabled participants. The study indicates that the GSES fully mediates the relationship between SWLS and all three scales of the MHLC: internal (IHLC), powerful others (PHLC), and chance (CHLC). In addition, Movement disability moderates the PHLC-GSES and CHLC-GSES relationships. CONCLUSIONS: The findings suggest that people with movement disability may construct life satisfaction differently than persons without disability. Self-efficacy should be a target in therapy to improve life satisfaction in people with mobility impairment.

Increased lanosterol turnover: a metabolic burden for daunorubicin-resistant leukemia cells.

The cholesterol metabolism is essential for cancer cell proliferation. We found the expression of genes involved in the cholesterol biosynthesis pathway up-regulated in the daunorubicin-resistant leukemia cell line CEM/R2, which is a daughter cell line to the leukemia cell line CCRF-CEM (CEM). Cellular (2)H2O labelling, mass spectrometry, and isotopomer analysis revealed an increase in lanosterol synthesis which was not accompanied by an increase in cholesterol flux or pool size in CEM/R2 cells. Exogenous addition of lanosterol had a negative effect on CEM/R2 and a positive effect on sensitive CEM cell viability. Treatment of CEM and CEM/R2 cells with cholesterol biosynthesis inhibitors acting on the enzymes squalene epoxidase and lanosterol synthase, both also involved in the 24,25-epoxycholesterol shunt pathway, revealed a connection of this pathway to lanosterol turnover. Our data highlight that an increased lanosterol flux poses a metabolic weakness of resistant cells that potentially could be therapeutically exploited.

Simultaneous Determination of Eight Hypotensive Drugs of Various Chemical Groups in Pharmaceutical Preparations by HPLC-DAD.

A new sensitive, simple, rapid, and precise HPLC method with diode array detection has been developed for separation and simultaneous determination of hydrochlorothiazide, furosemide, torasemide, losartane, quinapril, valsartan, spironolactone, and canrenone in combined pharmaceutical dosage forms. The chromatographic analysis of the tested drugs was performed on an ACE C18, 100 Å, 250×4.6 mm, 5 µm particle size column with 0.0.05 M phosphate buffer (pH=3.00)-acetonitrile-methanol (30+20+50 v/v/v) mobile phase at a flow rate of 1.0 mL/min. The column was thermostatted at 25°C. UV detection was performed at 230 nm. Analysis time was 10 min. The elaborated method meets the acceptance criteria for specificity, linearity, sensitivity, accuracy, and precision. The proposed method was successfully applied for the determination of the studied drugs in the selected combined dosage forms.

Targeted Disruption of ALK Reveals a Potential Role in Hypogonadotropic Hypogonadism.

Mice lacking ALK activity have previously been reported to exhibit subtle behavioral phenotypes. In this study of ALK of loss of function mice we present data supporting a role for ALK in hypogonadotropic hypogonadism in male mice. We observed lower level of serum testosterone at P40 in ALK knock-out males, accompanied by mild disorganization of seminiferous tubules exhibiting decreased numbers of GATA4 expressing cells. These observations highlight a role for ALK in testis function and are further supported by experiments in which chemical inhibition of ALK activity with the ALK TKI crizotinib was employed. Oral administration of crizotinib resulted in a decrease of serum testosterone levels in adult wild type male mice, which reverted to normal levels after cessation of treatment. Analysis of GnRH expression in neurons of the hypothalamus revealed a significant decrease in the number of GnRH positive neurons in ALK knock-out mice at P40 when compared with control littermates. Thus, ALK appears to be involved in hypogonadotropic hypogonadism by regulating the timing of pubertal onset and testis function at the upper levels of the hypothalamic-pituitary gonadal axis.

Determination of neomycin in the form of neomycin derivative with dabsyl chloride by thin layer chromatography and densitometry.

A thin layer chromatographic-densitometric method has been developed for identification and quantitative determination of neomycin derivative with dabsyl chloride. The analysis of antibiotic was achieved on the silica gel TLC plates with fluorescent indicator with n-butanol--2-butanone--25% ammonia--water (10 : 6 : 2 : 2, v/v/v/v) as the mobile phase. The densitometric measurements were made at 460 nm. Under these conditions good separation of chosen aminoglycoside antibiotic from reagent used to make a complex was obtained. The method is characterized by high sensitivity, LOD from 0.1953 µg per band and LOQ from 0.5918 µg per band, wide linearity range from 0.5918 to 2.1960 µg per band for neomycin. The precision of the method was good; RSD varied from 1.17 to 2.05%. Satisfactory results of validation of the method were also confirmed by determination of selected antibiotic in pharmaceutical commercial preparation. The results obtained by TLC-densitometric method were compared with those obtained by spectrophotometric method.

The kinase ALK stimulates the kinase ERK5 to promote the expression of the oncogene MYCN in neuroblastoma.

Anaplastic lymphoma kinase (ALK) is an important molecular target in neuroblastoma. Although tyrosine kinase inhibitors abrogating ALK activity are currently in clinical use for the treatment of ALK-positive (ALK(+)) disease, monotherapy with ALK tyrosine kinase inhibitors may not be an adequate solution for ALK(+) neuroblastoma patients. Increased expression of the gene encoding the transcription factor MYCN is common in neuroblastomas and correlates with poor prognosis. We found that the kinase ERK5 [also known as big mitogen-activated protein kinase (MAPK) 1 (BMK1)] is activated by ALK through a pathway mediated by phosphoinositide 3-kinase (PI3K), AKT, MAPK kinase kinase 3 (MEKK3), and MAPK kinase 5 (MEK5). ALK-induced transcription of MYCN and stimulation of cell proliferation required ERK5. Pharmacological or RNA interference-mediated inhibition of ERK5 suppressed the proliferation of neuroblastoma cells in culture and enhanced the antitumor efficacy of the ALK inhibitor crizotinib in both cells and xenograft models. Together, our results indicate that ERK5 mediates ALK-induced transcription of MYCN and proliferation of neuroblastoma, suggesting that targeting both ERK5 and ALK may be beneficial in neuroblastoma patients.

Photodegradation assessment of ciprofloxacin, moxifloxacin, norfloxacin and ofloxacin in the presence of excipients from tablets by UPLC-MS/MS and DSC.

BACKGROUND: Ciprofloxacin (CIP), moxifloxacin (MOX), norfloxacin (NOR) and ofloxacin (OFL), are the antibacterial synthetic drugs, belonging to the fluoroquinolones group. Fluoroquinolones are compounds susceptible to photodegradation process, which may lead to reduction of their antibacterial activity and to induce phototoxicity as a side effect. This paper describes a simple, sensitive UPLC-MS/MS method for the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products. RESULTS: Chromatographic separations were carried out using the Acquity UPLC BEH C18 column; (2.1 × 100 mm, 1.7 µm particle size). The column was maintained at 40°C, and the following gradient was used: 0 min, 95% of eluent A and 5% of eluent B; 10 min, 0% of eluent A and 100% of eluent B, at a flow rate of 0.3 mL min(-1). Eluent A: 0.1% (v/v) formic acid in water; eluent B: 0.1% (v/v) formic acid in acetonitrile. The method was validated and all the validation parameters were in the ranges acceptable by the guidelines for analytical method validation. The photodegradation of examined fluoroquinolones in solid phase in the presence of excipients followed kinetic of the first order reaction and depended upon the type of analyzed drugs and coexisting substances. Photodegradation process of analyzed drugs was confirmed by differential scanning calorimetry. In addition, the identification of degradation products was carried out by mass spectrometry. CONCLUSION: The developed UPLC-MS/MS method enables the determination of CIP, MOX, NOR and OFL in the presence of photodegradation products and identification of photodegradation products.

Phosphoproteomic analysis of anaplastic lymphoma kinase (ALK) downstream signaling pathways identifies signal transducer and activator of transcription 3 as a functional target of activated ALK in neuroblastoma cells.

Activation of the anaplastic lymphoma kinase (ALK) receptor tyrosine kinase is a key oncogenic mechanism in a growing number of tumor types. In the majority of cases, ALK is activated by fusion with a dimerizing partner protein as a result of chromosomal translocation events, most studied in the case of the nucleophosmin-ALK and echinoderm microtubule-associated protein-like 4-ALK oncoproteins. It is now also appreciated that the full-length ALK receptor can be activated by point mutations and by deletions within the extracellular domain, such as those observed in neuroblastoma. Several studies have employed phosphoproteomics approaches to find substrates of ALK fusion proteins. In this study, we used MS-based phosphotyrosine profiling to characterize phosphotyrosine signaling events associated with the full-length ALK receptor. A number of previously identified and novel targets were identified. One of these, signal transducer and activator of transcription 3 (STAT3), has previously been observed to be activated in response to oncogenic ALK signaling, but the significance of this in signaling from the full-length ALK receptor has not been explored further. We show here that activated ALK robustly activates STAT3 on Tyr705 in a number of independent neuroblastoma cell lines. Furthermore, knockdown of STAT3 by RNA interference resulted in a reduction in myelocytomatosis neuroblastom (MYCN) protein levels downstream of ALK signaling. These observations, together with a decreased level of MYCN and inhibition of neuroblastoma cell growth in the presence of STAT3 inhibitors, suggest that activation of STAT3 is important for ALK signaling activity in neuroblastoma.

Kinetic and thermodynamic studies of moxifloxacin hydrolysis in the presence and absence of metal ions in acidic solutions.

Chromatographic and densitometric method for determination of moxifloxacin in the presence of products of acidic hydrolysis was developed. The established method had suitable specificity, precision, good accuracy, and high sensitivity. In addition, stability of moxifloxacin in acidic solutions at temperature 90 degrees C and 110 degrees C in the presence and absence of metal ions, such as Cu(II), Fe(III), Zn(II), and Al(III) was studied. It was proved that decomposition of moxifloxacin proceeds according to kinetics of the first-order reaction and is dependent on temperature, incubation time and the type of the metal ion. Based on the calculated kinetic (k, t0, and t0.5) and thermodynamic (Ea) parameters, it was observed that among studied ions the highest effect on decomposition process of moxifloxacin had Cu(II) ions. The liquid chromatography coupled with mass spectrometry detection (LC-MS) and proton nuclear magnetic resonance (1H NMR) techniques have been used to identify degradation products for the compound.

Separation and characterization of ciprofloxacin, difloxacin, lomefloxacin, norfloxacin, and ofloxacin oxidation products under potassium permanganate treatment in acidic medium by UPLC-MS/MS.

A simple, sensitive and reproducible ultra-performance liquid chromatography method for determination of ciprofloxacin, difloxacin, lomefloxacin, norfloxacin and ofloxacin oxidation stability under permanganate treatment in acidic conditions at pH from 3.0 to 6.0, was developed. Chromatographic separations were carried out using the Acquity UPLC BEH C18 column; (2.1×100 mm, 1.7 µm particle size). The column was maintained at 40°C, and eluted under isocratic conditions using 83% of eluent A and 17% of eluent B over 6.5 min, at a flow rate of 0.3 mL min(-1). Eluent A: water/formic acid (0.1 v/v%); eluent B: acetonitrile/formic acid (0.1 v/v%). An oxidation process followed kinetic of the second order reaction and depended upon solution acidity. Oxidation of fluoroquinolones proceeded at piperazine moiety yielding respective hydroxy and oxo analogs, and remaining the quinolone fragment intact. Structures of products formed were assigned on a basis of UPLC/MS/MS fragmentation pathways.

Controlling a nanowire quantum dot band gap using a straining dielectric envelope.

We tune the emission wavelength of an InAsP quantum dot in an InP nanowire over 200 meV by depositing a SiO(2) envelope using plasma-enhanced chemical vapor deposition without deterioration of the optical quality. This SiO(2) envelope generates a controlled static strain field. Both red and blue shift can be easily achieved by controlling the deposition conditions of the SiO(2). Using atomistic empirical tight-binding calculations, we investigate the effect of strain on a quantum dot band structure for different compositions, shape, and crystal orientations. From the calculations, we estimate the applied strain in our experiment. This enables engineering of the band gap in nanowires with unprecedented possibilities to extend the application range of nanowire devices.