Laser-Spark Multicharged Ion Implantation System ‒ Application in Ion Implantation and Neural Deposition of Carbon in Nickel (111)

Carbon ions generated by ablation of a carbon target using an Nd:YAG laser pulse (wavelength λ = 1064 nm, pulse width τ = 7 ns, and laser fluence of 10-110 J/cm2) are characterized. Time-of-flight analyzer, a three-mesh retarding field analyzer, and an electrostatic ion energy analyzer are used to study the charge and energy of carbon ions generated by laser ablation. The dependencies of the ion signal on the laser fluence, laser focal point position relative to target surface, and the acceleration voltage are described. Up to C4+ are observed. When no acceleration voltage is applied between the carbon target and a grounded mesh in front of the target, ion energies up to ~400 eV/charge are observed. The time-of-flight signal is analyzed for different retarding field voltages in order to obtain the ion kinetic energy distribution. The ablation and Coulomb energies developed in the laser plasma are obtained from deconvolution of the ion time-of-flight signal. Deconvolution of the time-of-flight ion signal to resolve the contribution of each ion charge is accomplished using data from a retarding field analysis combined with the time-of-flight signal. The ion energy and charge state increase with the laser fluence. The position of the laser focal spot affects the ion generation, with focusing ~1.9 mm in front of the target surface yielding maximum ions. When an external electric field is applied in an ion drift region between the target and a grounded mesh parallel to the target, fast ions are extracted and separated, in time, due to increased acceleration with charge state. However, the ion energy accelerated by the externally applied electric field is less than the potential drop between the target and mesh due to plasma shielding. By coupling a spark discharge into a laser-generated carbon plasma, fully-stripped carbon ions with a relatively low laser pulse energy are observed. When spark-discharge energy of ~750 mJ is coupled to the carbon plasma generated by ~50 mJ laser pulse (wavelength 1064 nm, pulse width 8 ns, intensity 5 × 109 W/cm2), enhancement in the total ion charge by a factor of ~6 is observed, along with the increase of maximum charge state from C4+ to C6+. Spark coupling to the laser plasma significantly reduces the laser pulse energy required to generate highly-charged ions. Compared to the laser carbon plasma alone, the spark discharge increases the intensity of the spectral emission of carbon lines, the electron density ne, and the electron temperature Te. The effective ion plasma temperature associated with translational motion along the plume axis Tieff is calculated from the ion time-of-flight signal. Carbon laser plasma generated by an Nd:YAG laser (wavelength 1064 nm, pulse width 7 ns, fluence 4-52 J/cm2) is studied by optical emission spectroscopy and ion time-of-flight. Up to C4+ ions are detected with the ion flux strongly dependent on the laser fluence. The increase in ion charge with the laser fluence is accompanied by observation of multicharged ion lines in the optical spectra. The time-integrated electron temperature Te is calculated from the Boltzmann plot using the C II lines at 392.0, 426.7, and 588.9 nm. Te is found to increase from ~0.83 eV for a laser fluence of 22 J/cm2 to ~0.90 eV for 40 J/cm2. The electron density ne is obtained from the Stark broadened profiles of the C II line at 392 nm and is found to increase from ~2.1x1017 cm-3 for 4 J/ cm2 to ~3.5 x 1017 cm-3 for 40 J/cm2. Applying an external electric field parallel to the expanding plume shows no effect on the line emission intensities. Deconvolution of ion time-of-flight signal with a shifted Maxwell-Boltzmann distribution for each charge state results in an ion temperature Ti ~4.7 and ~6.0 eV for 20 and 36 J/cm2, respectively. Carbon ion emission from femtosecond laser ablation of a glassy carbon target is studied. A Ti:sapphire laser (pulse duration τ ~150 fs, wavelength λ = 800 nm, laser fluence F ≤ 6.4 J/cm2) is used to ablate the carbon target while ion emission is detected by a time-of-flight detector equipped with a three-grid retarding field analyzer. A strong effect of the laser pulse fluence on the yield of carbon ions is observed. Up to C6+ ions are detected. The carbon time-of-flight ion signal is fit to a shifted Maxwell-Boltzmann distribution and used to extrapolate the effective plasma ion temperature Tieff = 6.9 eV. Applying an external electric field along the plasma expansion direction increased ion extraction, possibly due to the retrograde motion of the plasma-vacuum edge. The laser ion source is utilized for carbon ion implantation of Ni(111), aiming for graphene synthesis. Ni(111) thin films are prepared with magnetron sputter coater on mica substrates at 500 °C with 400 nm thickness. Ni(111) thin films are analyzed with XRD and showed that the surface mostly contains single crystal Ni(111). Carbon at +5, -5, -10, and -15 keV of Ni (111) biasing with a series of dosages were implanted into Ni(111) films at room temperature. Carbon nanostructures such as amorphous carbon and diamond-like carbon were synthesized on Ni(111) substrates by the laser generated carbon ion implantation

Does Turkey’s economic crisis spell the end for Erdogan?

Turkey is currently in the midst of an economic crisis, with the Turkish lira plummeting in value and inflation hitting its highest level since 2002. Balki Begumhan Bayhan writes that ahead of elections set to be held in 2023, Turkish President Recep Tayyip Erdoğan now risks losing his hold on power

Loneliness and older adults: psychological resilience and technology use during the COVID-19 pandemic—a cross sectional study

Introduction: This study investigated how psychological resilience influenced greater technology use among older adults, and whether they moderated the impact of social isolation on loneliness during the COVID-19 pandemic. We also explored whether technology mediates the impact of psychological resilience on loneliness. To explain the relationship between variables, the research drew upon the socio-emotional selective theory, which posits the notion that older adults are more focused on current and emotionally important relationships and goals concerning emotional regulation goals such as psychological well-being.Methods: Using a cross-sectional observational design, data were collected from 92 residents aged 65 to 89 in England from March 2020 to June 2021. Participants completed the Connor–Davidson Resilience Scale, Technology Experience Questionnaire, UCLA Loneliness Scale, and Lubben Social Network Index. Pearson correlation, mediation and moderation analyses were conducted to investigate the hypotheses.Results: Most participants experienced moderate to severe levels of loneliness, displaying higher levels than pre-pandemic. Psychological resilience predicted greater technology use, and lower levels of loneliness. Technology was found to mediate the relationship between psychological resilience and loneliness. Neither technology use, nor psychological resilience was found to moderate the impact of social isolation on loneliness.Discussion: Findings suggested that strategies directed towards screening older adults for psychological resilience levels and low technology experience may help identify those most at risk for adapting poorly when exposed to stressors in situations like the Covid-19 pandemic. Early interventions can be initiated to increase psychological resilience and technology use, including empirical interventions, that may help decrease loneliness, especially in times of elevated risks for loneliness

Carbon Multicharged Ion Generation From Laser-Spark Ion Source

Multicharged carbon ions are generated by using a laser-assisted spark-discharge ion source. A Q-switched Nd:YAG laser pulse (1064 nm, 7 ns, ≤ 4.5 × 109 W/cm2) focused onto the surface of a glassy carbon target results in its ablation. The spark-discharge (∼1.2 J energy, ∼1 µs duration) is initiated along the direction of the plume propagation between the target surface and a grounded mesh that is parallel to the target surface. Ions emitted from the laser-spark plasma are detected by their time-of-flight using a Faraday cup. The ion energy-to-charge ratio is analyzed by a three-mesh retarding field analyzer. In one set of experiments, the laser plasma is generated by target ablation using a 50 mJ laser pulse. In another set of experiments, ∼1.2 J spark-discharge energy is coupled to the expanding plasma to increase the plasma density and temperature that results in the generation of carbon multicharged ions up to C6+. A delay-generator is used to control the time delay between the laser pulse and the thyratron trigger. Ion generation from a laser pulse when a high DC voltage is applied to the target is compared to that when a spark-discharge with an equivalent pulsed voltage is applied to the target. The laser-coupled spark-discharge (7 kV peak voltage, 810 A peak current) increases the maximum detected ion charge state from C4+ to C6+, accompanied by an increase in the ion yield by a factor of ∼6 compared to applying 7.0 kV DC voltage to the target

Doğu Akdeniz Bölgesi’nde Organik Turunçgil Üretiminde Hastalık, Zararlı ve Yabancı Otların Mücadelesinin Yönetimi

Bu çalışma, 2003-2006 yılları arasında Hatay (Dörtyol) ve Mersin (Erdemli) illerinde yürütülmüş olup, çalışmada Mars Seedless Altıntop ve Valensiya Portakal çeşidinde zararlı, hastalık ve yabancı otlara karşı organik tarıma uygun mücadele yöntemlerinin uygulanabilirliği araştırılmıştır. Çalışmada her iki turunçgil çeşidinin bulunduğu alanlarda Organik Tarım ve Entegre Mücadele uygulamaları birlikte yürütülmüştür. Organik tarım yapılan bahçelerde organik ürün sertifikası alımına yönelik gerekli denetlemeler yaptırılarak ürün sertifikalandırılmıştır. Tüm bahçelerde bulunan zararlı ve doğal düşmanlar gözle inceleme ve darbe yöntemi ile saptanmıştır. Organik tarım bahçelerinde, ekonomik zarar eşiğini aşan zararlılara (Turunçgil Unlubiti, Turunçgil Kırmızı Örümceği, Yıldız Koşnili) karşı doğal düşman salımı, kükürt ve yazlık beyaz yağ uygulaması yapılarak mücadele edilmiştir. Hastalık etmenleri makroskopik ve mikroskobik incelemelerle belirlenmiştir. Denemenin yürütüldüğü Mars Seedless Altıntop bahçesinde Gövde Zamklanma Hastalığı [Phytopthora citropthora (Sm. et Sm) Leonian] tespit edilmiştir. Bu hastalıkla mücadele için enfekteli ağaçların gövdesinde kabuk temizliği yapılmış temizlenen yara yerlerine %2 oranında Bordo Bulamacı uygulanmıştır. Yabancı otlarla organik yetiştiricilikte mücadele amacıyla örtücü bitki uygulaması yapılmıştır. Dört örtücü bitki türü; arpa, İngiliz Çimi, Adi Fiğ, Acem Üçgülü denemeye alınmıştır. Toprağı kaplama alanı yönünden en yüksek değerler, ile yabancı ot kaplama alanı ve birim alandaki yabancı ot tür ve sayısı yönünden en düşük değerler arpa ve fiğden alınırken, yaş ve kuru ağırlık yönünden en yüksek değer yine fiğ parselinden elde edilmiştir. Bahçelerde Turunçgil Nematodu (Tylenchulus semipenetrans Cobb.) da belirlenmiş ancak populasyonları zarar eşiğinin altında bulunmuştur. Parsellerde kullanılan çiftlik gübresi ve yeşil gübre toprak ve yaprak analizleri sonuçlarına göre uygulanmıştır. Kullanılan her türlü girdiler ve yapılan işlemler Tarım Bakanlığınca yayımlanan yönetmeliğe uygun olarak kontrol ve sertifikasyon kuruluşunun da onayı ile seçilmiştir. Her yıl meyve hasat döneminde kalıntı analizleri ve pomolojik analizler yaptırılmış, bir üretim periyodu sonunda ağaç başına ortalama verim belirlenmiştir. Proje çalışmaları, ürüne “organik ürün” sertifikası veren danışman firma tarafından kontrol edilmiş ve çalışmada organik meyve elde edilmiştir

Multicharged Carbon Ion Generation from Laser Plasma

Carbon ions generated by ablation of a carbon target using an Nd:YAG laser pulse (wavelength λ = 1064 nm, pulse width τ = 7 ns, and laser fluence of 10-110 J cm-2) are characterized. Time-of-flight analyzer, a three-mesh retarding field analyzer, and an electrostatic ion energy analyzer are used to study the charge and energy of carbon ions generated by laser ablation. The dependencies of the ion signal on the laser fluence, laser focal point position relative to target surface, and the acceleration voltage are described. Up to C4+ ions are observed. When no acceleration voltage is applied between the carbon target and a grounded mesh in front of the target, ion energies up to ∼400 eV/charge are observed. The time-of-flight signal is analyzed for different retarding field voltages in order to obtain the ion kinetic energy distribution. The ablation and Coulomb energies developed in the laser plasma are obtained from deconvolution of the ion time-of-flight signal. Deconvolution of the time-of-flight ion signal to resolve the contribution of each ion charge is accomplished using data from a retarding field analysis combined with the time-of-flight signal. The ion energy and charge state increase with the laser fluence. The position of the laser focal spot affects the ion generation, with focusing ∼1.9 mm in front of the target surface yielding maximum ions. When an external electric field is applied in an ion drift region between the target and a grounded mesh parallel to the target, fast ions are extracted and separated, in time, due to increased acceleration with charge state. Published by AIP Publishing. [http://dx.doi.org/10.1063/1.4966987

HIV infection and hepatitis B seroprevalence among antenatal clinic attendees in Niger, West Africa

This transversal study was suggested in order to estimate the nationwide seroprevalences of HIV infection and hepatitis B among 495 pregnant women in Niger in 2008. The study detected anti-HIV antibodies with Genscreen® Plus HIV Ag/Ab Ultra Kit (Bio-Rad; Hercules, CA), Vironostika® HIV Uni-Form II Ag/Ab (bioMérieux; Marcy-l’Etoile, France), and ImmunoComb® II HIV 1 and 2 BiSpot (Orgenics; Yavne, Israel). HBsAg was detected by Monolisa® HBsAg Ultra (Bio-Rad) and ImmunoComb® II HBsAg (Orgenics). The rates obtained were 2.02% (95% confidence intervals (CI): 1.03%–3.81%) and 16.16% (95% CI: 13.09%–19.77%), respectively. There were no significant variations according to environment, region, age, marital status, educational level, antecedent of surgery and transfusion. But these data need a large sample, and periodic updates for a better planning of activities in the framework of a national reproductive health program, including prevention of mother-to-child HIV transmission

Effect of seizure timing on long-term survival in patients with brain tumor

OBJECTIVE: Seizures often occur in patients with primary brain tumor (BT). The aim of this study was to determine if there is an association between the time of occurrence of seizures during the course of BT and survival of these patients. METHODS: This retrospective cohort study at Henry Ford Hospital, an urban tertiary referral center, included all patients who were diagnosed with primary BTs at Henry Ford Health System between January 2006 and December 2014. Timing of seizure occurrence, if occurred at presentation or after the tumor diagnosis during follow-up period, in different grades of BTs, and survival of these patients were analyzed. RESULTS: Of the 901 identified patients, 662 (53% male; mean age: 56 years) were included in final analysis, and seizures occurred in 283 patients (43%). Patients with World Health Organization (WHO) grade III BT with seizures as a presenting symptom only had better survival (adjusted hazard ratio (HR): 0.27; 95% confidence interval (CI), 0.11-0.67; P = 0.004). Seizures that occurred after tumor diagnosis only (adjusted HR: 2.11; 95% CI, 1.59-2.81; P \u3c 0.001) in patients with WHO grade II tumors (adjusted HR: 3.41; 95% CI, 1.05-11.1; P = 0.041) and WHO grade IV tumors (adjusted HR: 2.14; 95% CI, 1.58-2.90; P \u3c 0.001) had higher mortality. Seizures that occurred at presentation and after diagnosis also had higher mortality (adjusted HR: 1.34; 95% CI, 1.00-1.80; P = 0.049), in patients with meningioma (adjusted HR: 6.19; 95% CI, 1.30-29.4; P = 0.021) and grade III tumors (adjusted HR: 6.19; 95% CI, 2.56-15.0; P \u3c 0.001). CONCLUSION: Seizures occurred in almost half of the patients with BTs. The association between seizures in patients with BT and their survival depends on the time of occurrence of seizures, if occurring at presentation or after tumor diagnosis, and the type of tumor. Better survival was noted in patients with WHO grade III BTs who had seizures at presentation at the time of diagnosis, while higher mortality was noted in WHO grade II tumors who had seizure at presentation and after tumor diagnosis, and in grade IV tumors after tumor diagnosis