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To present the efficacy and safety of surgical treatment of moderate to advanced stage of open-angle glaucoma using the surgical method of transscleral cyclophotocoagulation with MicroPulse® laser (Iridex, Silicon Valley, California, USA) and to compare these results with those of continuous transscleral cyclophotocoagulation with diode laser. In a prospective observational clinical study 22 patients (30 eyes) with moderate and advanced open-angle glaucoma underwent transscleral cyclophotocoagulation. 15 eyes were treated with transscleral cyclophotocoagulation with MicroPulse® laser with 2500 mW (group A) and 15 eyes with continuous diode laser 810 nm and power between 2000 and 2300 mW (group B). The follow-up period of the study was 12 months. A reduction of the intraocular pressure > 30% was achieved in 53.3% of the group A and in 60% of the group B during the follow-up period of 12 months. A statistically significant decrease of the number of antiglaucoma agents was observed in group A. One eye (6.6%) of group A underwent additional antiglaucoma procedures to achieve target intraocular pressure. The corresponding percentage is 40% in group B. The postoperative inflammatory response was significantly more limited in group A compared to group B. The transscleral cyclophotocoagulation with MicroPulse® diode laser with 2500 mW achieves a similar decrease of the intraocular pressure as cyclophotocoagulation with continuous diode laser for the first postoperative months, but more satisfactory reduction of the number of eye drops as well as more limited postoperative inflammatory response.

The study compares the efficacy and safety of PreserFlo™ MicroShunt (Santen, Osaka, Japan) and trabeculectomy in eyes with moderate to advanced open-angle glaucoma.In this prospective study, 300 patients (300 eyes) with moderate to advanced open-angle glaucoma were treated with either PreserFlo MicroShunt or trabeculectomy. The implantation of the PreserFlo MicroShunt was performed in 150 eyes (group A) and trabeculectomy was performed in 150 eyes (group B). The efficacy was evaluated by estimating the absolute and qualified success rates using the Kaplan-Meier survival analysis. Results: During the 12-month follow-up period, 81.33% of eyes in group A and 94% in group B reduced intraocular pressure (IOP)20% without glaucoma eye drops. The average IOP 12 months after surgery was 12.89±3.4 mmHg in group A and 11.39±4.5 mmHg in group B, which was significantly lower than the baseline intraocular pressure (group A: 23.47±8.36 mmHg, p=0.00053; group B: 22.03±5.2 mmHg, p= 0.0006). The number of topical medications administered 12 months after ocular surgery was 0.4±0.8 in group A and 0 in group B, compared to 2.5±1.2 in group A and 2.7±0.9 in group B at baseline (group A: p= 0.00091; group B: p= 0.00072). Ten eyes (6.67%) in group A and four eyes (2.67%) in group B were referred for bleb revision due to bleb fibrosis and consequent acute postoperative rise in IOP. Four eyes of group A and two eyes of group B were treated with transscleral cyclophotocoagulation. Five eyes in group B received re-trabeculectomy because of dysfunction of the primary bleb.PreserFlo MicroShunt reduced the number of antiglaucoma agents compared to baseline, but was inferior to trabeculectomy at reducing IOP after 12 months. Additionally, trabeculectomy produced better absolute success rates after 12 months than PreserFlo MicroShunt in the treatment of moderate to advanced open-angle glaucoma.

To compare the efficacy of transscleral cyclophotocoagulation with MicroPulse® laser (Iridex, Silicon Valley, California, USA) with 3000 mW to Ahmed valve implantation in eyes with advanced stage of primary open-angle glaucoma. In a prospective observational clinical study, 30 patients (30 eyes) with advanced open-angle glaucoma were randomized for either micropulse transscleral cyclophotocoagulation with 3000 mW or Ahmed valve implantation. Fifteen eyes were treated with transscleral cyclophotocoagulation with MicroPulse® laser with 3000 mW (group A) and 15 eyes with Ahmed valve implantation (group B). As inclusion criteria are included the diagnosis of advanced primary open-angle glaucoma, an intraocular pressure above 21 mmHg, cup-to-disk ratio 0.9–1.0, failure to meet the target IOP with either maximal tolerated local medical therapy (2–4 antiglaucoma agents) or systemic therapy (acetazolamide). The follow-up time of the study was 12 months. An absolute success was defined the achievement of IOP between 6 and 15 mmHg and at least 30% reduction of the IOP from baseline under reduced or the same number of antiglaucoma agents after the surgical procedure without following glaucoma surgeries and as qualified success the achievement of IOP between 6 and 18 mmHg and at least 20% reduction of the IOP from baseline regardless of the number of postoperative antiglaucoma agents. The efficacy was evaluated by estimating the absolute success rate and the qualified success rate using the Kaplan–Meier survival analysis. A reduction of the intraocular pressure > 30% was achieved in 33.3% of group A and in 73.3% of group B during the follow-up period of 12 months. A statistically significant decrease in the number of eye drops was observed in both groups (p < 0.01). 53.3% of the eyes of group A underwent additional anti-glaucoma procedures to achieve target intraocular pressure. The number of the local medications that were administered 12 months after the ocular surgery was 2 (± 1.3) in group A and 0.57 (± 0.9) in group B, compared to 3.2 (± 0.78) in group A and 3.33 (± 0.7) in group B administered prior to the surgery (p: 0.016). 8 eyes (53.33%) in group A were referred for additional treatment due to an acute postoperative rise in IOP (5 eyes: mTS-CPC, 1 eye: canaloplasty, 2 eyes: AGV implantation). No further anti-glaucoma procedures were necessary in group B. The Ahmed valve implantation achieves a more efficient decrease of the intraocular pressure as well as of the number of antiglaucoma agents than the transscleral cyclophotocoagulation with MicroPulse® diode laser 3000 mW. Additionally, the Ahmed valve implantation showed better results in terms of absolute and qualified success rates in the treatment of advanced primary open-angle glaucoma.

The coverage of chronic and painful corneal defects with a complete or partial conjunctival flap is a surgical practice that is still applied to advanced stage of keratopathies, which insist despite repeated treatments with a therapeutic contact lens, corneal transplantation or amniotic membrane transplantation.37 cases of refractory corneal defects were treated between January 2006 and December 2019 with conjunctival flap. 27 cases underwent a complete and 10 cases a partial conjunctival flap. The mean age of the patients (n = 37, 23 women and 14 men subjects) was 73 years (23 - 87 years). Unsuccessful efforts of intensive conservative treatment and repetitive surgical procedures for several weeks or even months ended up to the indication of performance of a conjunctival flap. Conjunctival flap was performed using the Gundersen technique. A very thin flap of the upper bulbar conjunctiva is dissected downward towards the limbus without creating buttonholes. When the limbus is reached, the resultant flap is freed and without tension it is pulled over the corneal defect and sutured with nylon sutures placed at the limbus (complete conjunctival flap) or at the stroma of healthy cornea (partial conjunctival flap).This kind of conjunctival flap has low rates of complication. The postoperative follow-up after the partial or complete conjunctival flap was satisfying in 34 cases and showed a good healing process without major complications. Partial conjunctival flap shrinkage was observed in 3 cases, which could be revised in 2 of them. One case underwent enucleation, because of recurrent severe keratopathy.Conjunctival flap is an established surgical procedure that is applied rarely. The more frequent performance of this technique is suggested as it consists the ultima ratio for the treatment of refractory neurotrophic keratitis and non-healing epithelial defects.Partielle oder auch komplette Bindehautdeckungen haben ihre Indikation fast nur noch bei chronischen und schmerzhaften Oberflächenproblemen der Hornhaut, die dauerhaft gelöst werden sollen.Wir berichten über 37 Patienten, 23 Frauen und 14 Männer, mit einem Alter von 23 – 87 Jahren (Mittelwert 73 Jahre), bei denen wir in dem Zeitraum 1/2006 bis 12/2019 27 × eine komplette und 10 × eine partielle Bindehautdeckung durchgeführt haben. Vor der eigentlichen chirurgischen Maßnahme der Bindehautdeckung erfolgt i. d. R. eine wochen- bis monatelange ambulante wie auch stationäre Behandlung der chronischen therapieresistenten Oberflächenveränderungen und auch der Schmerzsymptomatik. Dafür muss ein Bindehautlappen partiell oder komplett möglichst spannungsfrei über die Hornhaut gezogen und dann stromal oder am Limbus verankert werden, bis eine Verwachsung der Subkonjunktiva mit den erkrankten Hornhautarealen erfolgt ist. In der Regel wird heutzutage dafür die Technik nach Gundersen durchgeführt.Insgesamt ist diese Bindehautdeckung komplikationsarm. Bei 34 Patienten waren die postoperativen Verläufe regelrecht. Die partiellen oder auch kompletten Bindehautdeckungen heilten komplikationslos ein. In 3 Fällen wurde eine Bindehautretraktion beobachtet, die in 2 Fällen revidiert werden konnte. In einem Fall musste eine Enukleation vorgenommen werden.Bindehautdeckungen sind eine etablierte, leider zu selten durchgeführte Operationstechnik, die häufiger zur Behandlung einer neurotrophen Keratitis oder bei persistierenden, nicht abheilenden Epitheldefekten zur Anwendung kommen sollte.

Die DMEK („Descemet Membrane Endothelial Keratoplasty“) hat sich in den letzten Jahren als operatives Verfahren auch zur Behandlung von komplizierten Fallen einer Hornhautdekompensation mit bulloser Keratopathie etabliert. In dieser Fallserie wurden 9 Augen von 8 Patienten mit fortgeschrittener Hornhautdekompensation bei Zustand nach multiplen intraokularen Eingriffen mit einer DMEK therapiert. Bei jeweils 1 Auge wurde die DMEK mit einer intravitrealen Gabe von Bevacizumab, mit einem IOL-Austausch, mit einer transskleralen MicroPulse-Zyklophotokoagulation (Iridex, Silicon Valley, Kalifornien, USA) sowie einer intravitrealen Gabe von Bevacizumab und der Deckung einer Skleraperforation mittels Tutopatch® (DMR srl, Italien) und bei 2 Augen mit einer Kurzung des Drainageschlauchs des Ahmed-Valve-Implantats kombiniert. Bei 3 Patienten erfolgte die DMEK als alleiniger operativer Eingriff. Die Beobachtungszeit liegt bei 12 Monaten. Bei 2 von 9 Augen erfolgte bei abgehobener Lamelle und persistierender Hornhautdekompensation trotz wiederholten Rebubblings eine perforierende Keratoplastik mit guten postoperativen Ergebnissen. Eine Visusbesserung konnte bei diesen 2 Augen aufgrund einer vorbestehenden Optikusatrophie nicht erzielt werden, die perforierende Keratoplastik bewirkte jedoch Schmerzfreiheit. Diese 2 Augen wurden von der Datenauswertung der Fallserie ausgeschlossen, sodass die Ergebnisse aus den restlichen 7 Augen generiert wurden. Ein Visusanstieg und Schmerzfreiheit wurden bei allen diesen 7 Augen durch die DMEK innerhalb eines Jahres erreicht. Die Endothelzelldichte der Spenderhornhaut reduzierte sich von 2465 (±147) auf 1295 ± 254 und 1180 ± 197/mm2 (p

In der mikroinvasiven Glaukomchirurgie (MIGS) wurde der CyPass Micro-Stent (Alcon Inc.) in den suprachoroidalen Raum implantiert, um den uveoskleralen Abfluss zu verstarken und somit den Augeninnendruck zu senken. Aufgrund des Verlustes von Hornhautendothelzellen wurde das Implantat im August 2018 vom weltweiten Markt genommen. Drei Jahre nach der CyPass-Implantation wurde bei 6 Patienten (insgesamt 8 Augen) mit fruhem bis masigem primarem Offenwinkelglaukom ein Verlust von Hornhautendothelzellen beobachtet. Bei einem Auge entwickelte sich eine bullose Keratopathie. Bei allen Patienten wurde eine Implantatmigration in der Vorderkammer im Vergleich zur ursprunglichen postoperativen Position festgestellt, wobei mehr als ein Ring des CyPass-Implantats sichtbar war. In allen 8 Fallen erfolgte die Entfernung des CyPass-Implantats. Die lokale Therapie mit kortisonhaltigen Augentropfen in Kombination mit einer 5%igen Natriumchloridlosung verbesserte das chronische Hornhautodem bei einem Patienten nicht. Daher erfolgte eine DMEK („Descemet membrane endothelial keratoplasty“) mit postoperativer Verbesserung des Visus. Bei Patienten mit mehr als einem sichtbaren Ring des CyPass-Implantats und einem lokalisierten Verlust der Hornhautendothelzellen wird die CyPass-Kurzung oder Entfernung empfohlen, damit das Fortschreiten der generalisierten Reduktion der Hornhautendothelzellen und das Auftreten eines therapieresistenten, chronischen Hornhautodems vermieden wird.

Nucleosynthesis in the νp-process occurs in regions of slightly proton-rich nuclei in the neutrino-driven wind of core-collapse supernovae. The process proceeds via a sequence of (p,γ) and (n,p) reactions, and depending on the conditions, may produce elements between Ni and Sn. Recent studies show that a few key (n,p) reactions regulate the efficiency of the neutrino-p process (νp-process). We performed a study of one of such (n,p) reactions via the measurement of the reverse (p,n) in inverse kinematics with SECAR at NSCL/FRIB.Such proton-induced reaction measurements are particularly challenging, as the recoils and the unreacted projectiles have nearly identical masses. An appropriate separation level can be achieved with SECAR, and along with the incoincidence detection of neutrons these measurements become attainable. The preparation of the SECAR system for accommodating its first (p,n) reaction measurement, including the development of alternative ion beam optics, and the setup of the in-coincidence neutron detection, along with discussion on preliminary results from the p(58Fe,n)58Co reaction measurement are presented and discussed.

40K is one of the main isotopes responsible for the radiogenic heating of the mantle in Earth-like exoplanets [1] and hence, plays a very important role in the internal geophysical dynamics of a planet. The abundance of 40K in the mantle and the core of such planets is not always possible to be determined by astrophysical observations, although constraining the nuclear reaction rates of 40K during stellar evolution can also lead to constraining the present amount of 40K in these planets, which will improve our understanding on the habitability potential of Earth-like exoplanets. This study aims to constrain the 40K(n,α)37Cl reaction rate, one of the two major destruction paths of 40K in stellar nucleosynthesis,by measuring the reverse reaction 37Cl(α,n)40K and applying the principle of detailed balance as we have done before for the 40K (40K(n,p)40Ar reaction rate) [2]. During the first set of measurements we performed differential cross-section measurements of the 37Cl(α,n1γ)40K, 37Cl(α,n2γ)40K and 37Cl(α,n3γ)40K reaction channels, for six different center of mass energies in the range between 5.1 and 5.4 MeV. The experiment took place at the Edwards Accelerator Laboratory of Ohio University. The gamma rays from the reaction channels mentioned above were detected by two LaBr3 scintillators. Using the swinger facility to change the angle of the beam-target system with respect to the detection system, we were able to take measurements for the differential cross-section at six different angles between 20° and 120° in the lab system.

The formation of nuclei in slightly proton-rich regions of the neutrino-driven wind of core-collapse supernovae could be attributed to the neutrino-p process (νp-process). As it proceeds via a sequence of (p,γ) and (n,p) reactions, it may produce elements in the range of Ni and Sn, considering adequate conditions. Recent studies identify a number of decisive (n,p) reactions that control the efficiency of the νp-process. The study of one such (n,p) reaction via the measurement of the reverse (p,n) in inverse kinematics was performed with SECAR at NSCL/FRIB. Proton-induced reaction measurements, especially at the mass region of interest, are notably difficult since the recoils have nearly identical masses as the unreacted projectiles. Such measurements are feasible with the adequate separation level achieved with SECAR, and the in-coincidence neutron detection. Adjustments of the SECAR system for the first (p,n) reaction measurement included the development of new ion beam optics, and the installation of the neutron detection system. The aforementioned developments along with a discussion on the preliminary results of the p(58Fe,n)58Co reaction measurement are presented.

Several anomalous elemental abundance ratios have been observed in the metal-poor star HD94028. We assume that its high [As/Ge] ratio is a product of a weak intermediate (i) neutron-capture process. Given that observational errors are usually smaller than predicted nuclear physics uncertainties, we have first set up a benchmark one-zone i-process nucleosynthesis simulation results of which provide the best fit to the observed abundances. We have then performed Monte Carlo simulations in which 113 relevant (n,$\gamma$) reaction rates of unstable species were randomly varied within Hauser-Feshbach model uncertainty ranges for each reaction to estimate the impact on the predicted stellar abundances. One of the interesting results of these simulations is a double-peaked distribution of the As abundance, which is caused by the variation of the $^{75}$Ga (n,$\gamma$) cross section. This variation strongly anti-correlates with the predicted As abundance, confirming the necessity for improved theoretical or experimental bounds on this cross section. The $^{66}$Ni (n,$\gamma$) reaction is found to behave as a major bottleneck for the i-process nucleosynthesis. Our analysis finds the Pearson product-moment correlation coefficient $r_\mathrm{P} > 0.2$ for all of the i-process elements with $32 \leq Z \leq 42$, with significant changes in their predicted abundances showing up when the rate of this reaction is reduced to its theoretically constrained lower bound. Our results are applicable to any other stellar nucleosynthesis site with the similar i-process conditions, such as Sakurai's object (V4334 Sagittarii) or rapidly-accreting white dwarfs., Comment: 10 pages, 14 figures, 1 table, accepted for publication by MNRAS

To report the efficacy of ab externo canaloplasty by exclusively using only a nonabsorbable suture as a standalone operation or combined with phacoemulsification in terms of mean intraocular pressure (IOP), medication reduction, and intra- and postoperative complication rates as well as additional glaucoma surgery.Forty-eight patients with primary open-angle glaucoma (POAG) and 50 eyes were divided into two groups according to the operation performed (Group A canaloplasty, n = 34 and Group B canaloplasty combined with phaco, n = 16), respectively. The success criteria were evaluated between three IOP ranges: a) IOP ≤ 16 mmHg, b) ≤ 18 mmHg, and c) ≤ 21 mmHg. Complete success was considered the percentage of eyes reaching these goals with no medication and qualified success with or without medication. Groups A and B were compared with the Kaplan-Meier test. Mean IOP and medication reduction as well as additional glaucoma surgery were also evaluated. The follow-up time was 6 months. Statistical importance was given at p 0.05.Fail rate and intraoperative conversion of canaloplasty to other surgery (trabeculotomy due to extensive cheese-wiring) accounted for 12% (6 eyes), while a mandatory usage of the iTrack 250A microcatheter to successfully overcome intracanalicular bridging of the Schlemm's canal accounted for 20% (10 eyes). The most common early postoperative complications in both groups were hyphema, cheese wiring, and transient IOP rising. The mean IOP in Group A reduced from 23.67 ± 6.06 mmHg to 13.35 ± 4.23 mmHg and in Group B, it reduced from 23.55 ± 6.19 mmHg to 12.75 ± 1.5 mmHg at 6 months (p 0.001). Group A's absolute success rates accounted for a) 44%, b) 47.1%, and c) 52.9% in comparison to Group B [a) 50%, b) 50%, and c) 56.3%] at 6 months (p 0.05). Qualified success with or without medication showed no statistical differences between the groups. The mean medication reduction was significantly lower (p 0.001) in both groups (Group A from baseline 3.2 ± 1.23 to 0.95 ± 1.35 and Group B from 3.12 ± 0.88 to 1.12 ± 0.75 at 6 months, respectively). Five eyes (10%) required additional glaucoma surgery.Ab externo canaloplasty by exclusively using only a nonabsorbable suture as a standalone operation or combined with phacoemulsification seems to lower the mean IOP and medication sufficiently. However, they pose a greater surgical challenge and intraoperative complication rate. Additional glaucoma surgery or medication following both procedures may be necessary to achieve an optimal target IOP.Berichterstattung über die Wirksamkeit der Ab-externo-Kanaloplastik durch ausschließliche Verwendung nur einer nicht resorbierbaren Naht als eigenständige Operation oder in Kombination mit einer Phakoemulsifikation in Bezug auf den Mittelwert des Augeninnendrucks und die Reduktion der Antiglaukomatosa, die intra- und postoperativen Komplikationsraten sowie die zusätzliche Glaukomoperation.48 Patienten (50 Augen) mit POAG wurden gemäß der durchgeführten Operation in 2 Gruppen eingeteilt (Gruppe A Kanaloplastik, n = 34, und Gruppe B Kanaloplastik kombiniert mit Phako, n = 16). Die Erfolgskriterien wurden zwischen 3 IOP-Bereichen bewertet: a) IOD ≤ 16 mmHg, b) ≤ 18 mmHg und c) ≤ 21 mmHg. Der vollständige Erfolg wurde als Prozentsatz der Augen angesehen, die diese Zieldrücke ohne Antiglaukomatosa erreichten, und als qualifizierter Erfolg mit oder ohne Antiglaukomatosa. Gruppe A und B wurden mit dem Kaplan-Meier-Test verglichen. Der Mittelwert des Augeninnendrucks und die Reduktion der Antiglaukomatosa sowie eine zusätzliche Glaukomoperation wurden ebenfalls ausgewertet. Die Nachbeobachtungszeit betrug 6 Monate. Die statistische Signifikanz wurde bei p 0,05 angegeben.Die Umstellung der Kanaloplastik auf andere chirurgische Eingriffe (Trabekulotomie aufgrund umfangreichem „cheese wiring“) betrug 12% (6 Augen). Die Verwendung des iTrack 250A-Mikrokatheters zur erfolgreichen Katheterisierung des Kanals und Lösung der intrakanalikulären Vernarbungen des Schlemm-Kanals war bei 20% (10 Augen) erforderlich. Die häufigsten frühen postoperativen Komplikationen in beiden Gruppen waren Hyphema, „cheese wiring“ und vorübergehender Anstieg des Augeninnendrucks. Der Mittelwert des Augeninnendrucks wurde in Gruppe A von 23,67 ± 6,06 auf 13,35 ± 4,23 mmHg and in Gruppe B von 23,55 ± 6,19 auf 12,75 ± 1,5 mmHg nach 6 Monaten reduziert (p 0,001). Die absoluten Erfolgsraten der Gruppe A waren a) 44%, b) 47,1% und c) 52,9% im Vergleich zu denen der Gruppe B a) 50%, b) 50% und c) 56,3% nach 6 Monaten (p 0,05). Qualifizierter Erfolg mit oder ohne Antiglaukomatosa zeigte keine statistischen Unterschiede zwischen den Gruppen. Die mittelwertige Reduktion der Antiglaukomatosa war in beiden Gruppen signifikant niedriger (p 0,001) (Gruppe A von 3,2 ± 1,23 auf 0,95 ± 1,35 und Gruppe B von 3,12 ± 0,88 auf 1,12 ± 0,75 nach 6 Monaten). Fünf Augen (10%) erforderten eine zusätzliche Glaukomoperation.Eine Ab-externo-Kanaloplastik mithilfe einer nicht resorbierbaren Naht als eigenständige Operation oder in Kombination mit einer Phakoemulsifikation kann den mittleren Augeninnendruck und die Antiglaukomatosa ausreichend senken. Diese operative Technik stellt jedoch eine größere chirurgische Herausforderung dar und scheint eine höhere intraoperative Komplikationsrate zu haben. Zusätzliche Glaukomoperationen oder Antiglaukomatosa nach beiden Verfahren können erforderlich sein, falls ein optimaler Zieldruck nicht erreicht ist.

Tectonic eccentric sclerokeratoplasty à chaud is a very complex corneal operation and aims to preserve the eyeball and possibly to improve visual acuity in patients with peripheral corneal ulcerations or perforating corneal trauma.1650 eyes received corneal transplants in our clinic between 2006 and 2019. 14 of these 1650 eyes (0.8%) had a perforated or predescemetal peripheral corneal ulceration and these were treated between 2006 and 2019 with a tectonic eccentric sclerokeratoplasty à chaud. The mean age of the 8 women and 6 men included in this case series was 63 years (22 - 91 years).In the postoperative follow-up period, most complications and reoperations occurred in the first 6 months. Re-ulceration was observed in 2 cases as well as early suture loosening in 12 patients. These 2 cases were treated with a partial conjunctival flap. Additionally, prolonged superficial wound healing process was shown in 12 patients. Therefore 27 amniotic membrane transplantations, 12 suture replacements, and 6 partial conjunctival flaps were performed in total. No re-keratoplasties were required in this case series. All eyes could be stabilised through the sclerokeratoplasty as well as subsequent operations and intensive local or even systemic treatment. After removal of the corneal suture, the best-corrected visual acuity improved only insignificantly to hand movement in 1 case, finger counting in 3 cases, 0.1 in 5 cases, 0.2 in 4 cases and 0.5 in 1 case. Preservation of the eyeball with pain relief was achieved in all 14 eyes.Eccentric sclerokeratoplasty is a very demanding surgical procedure and is extremely rarely performed. The goal is to preserve the eye.Die tektonische exzentrische Sklerokeratoplastik à chaud ist eine sehr aufwendige Hornhautoperation, die auf einen Bulbuserhalt und ggf. zur Visusbesserung bei Fällen mit peripheren Ulzerationen oder perforierenden Verletzungen der Hornhaut zielt.1650 Augen erhielten eine Hornhauttransplantation in den Jahren 2006 bis 2019 in unserer Klinik. Davon wurden 14 Augen (0,8%) mit einer perforierten oder prädescemetalen peripheren Hornhautulzeration mit einer tektonischen exzentrischen Sklerokeratoplastik à chaud behandelt. Das Durchschnittsalter der 8 Frauen und 6 Männer lag bei 63 Jahren (22 – 91 Jahre).Im postoperativen Verlauf traten in den ersten 6 Monaten die meisten Komplikationen und Nachoperationen auf. So zeigte sich bei 2 Patienten an nahezu identischer Stelle eine Re-Ulzeration, die mit einer partiellen exzentrischen Bindehautdeckung behandelt wurde. Frühzeitige Fadenlockerungen wurden bei 12 Patienten und oberflächliche Wundheilungsstörungen bei ebenfalls 12 Patienten beobachtet. Es erfolgte bei 27 Augen eine Amnionmembranaufnähung, bei 12 eine Fadennachlegung, bei 6 eine partielle temporäre Tarsorrhaphie, bei 7 eine lokale Therapie mit Serumaugentropfen und bei 2 eine partielle exzentrische Bindehautdeckung. Eine Re-Keratoplastik war bei keinem Patienten dieser Fallserie erforderlich. Alle Augen konnten durch die Sklerokeratoplastik und die vielen Nachoperationen und die durchaus intensive systemische wie auch lokale Behandlung stabilisiert werden. Nach der Fadenentfernung verbesserte sich der bestkorrigierte Visus nur unwesentlich auf Handbewegung bei 1 Fall, Fingerzählen bei 3 Fällen, 0,1 bei 5 Fällen, 0,2 bei 4 Fällen und 0,5 bei 1 Fall. Eine Bulbuserhaltung mit Schmerzfreiheit wurde bei allen 14 Augen erreicht.Exzentrische Sklerokeratoplastiken sind sehr anspruchsvolle operative Eingriffe und werden extrem selten durchgeführt. Das Ziel ist der Erhalt des Auges.

To demonstrate a novel, alternative endothelium Descemet membrane layer (EDM) orientation method in Descemet membrane endothelial keratoplasty (DMEK) that does not involve prior ink or trepanation marking of the graft, or intraoperative ocular coherence tomography (OCT) guided graft implantation during surgery, thus preventing the occurrence of an upside-down graft implantation that leads with certainty to primary graft failure. From 2017 to early 2020, 500 eyes underwent DMEK operation using the “bubble-tap” technique first described from Dr. Perdikakis in the department of ophthalmology of St.-Johannes- Hospital in Dortmund in Germany. Primary graft failure and re-bubbling results following “bubble-tap” assisted DMEK are presented. Primary graft failure due to upside-down graft implantation was not observed in any patient. Re-bubbling was performed in 4.8% of the eyes. In 1.8% of the cases, a re-DMEK was performed due to a graft failure. The “bubble-tap” technique is a novel, reliable and easy to master orientation method of EDM that enables the surgeon to perform DMEK with safety even in complicated cases with poor visibility in the anterior chamber, while it yields superior or equal results in comparison to other graft marking methods or intraoperative OCT-guided graft implantation.

The abundances of n-capture elements in the CEMP-r/s stars agree with predictions of intermediate n-density nucleosynthesis, at $N_\mathrm{n}\sim 10^{13}$-$10^{15} \mathrm{cm}^{-3}$, in rapidly-accreting white dwarfs (RAWDs). We have performed Monte-Carlo simulations of this i-process nucleosynthesis to determine the impact of (n,$\gamma$) reaction rate uncertainties of 164 unstable isotopes, from $^{131}$I to $^{189}$Hf, on the predicted abundances of 18 elements from Ba to W. The impact study is based on two representative one-zone models with constant values of $N_\mathrm{n} = 3.16\times 10^{14}\ \mathrm{cm}^{-3}$ and $N_\mathrm{n} = 3.16\times 10^{13}\ \mathrm{cm}^{-3}$ and on a multi-zone model based on a realistic stellar evolution simulation of He-shell convection entraining H in a RAWD model with [Fe/H]=-2.6. For each of the selected elements, we have identified up to two (n,$\gamma$) reactions having the strongest correlations between their rate variations constrained by Hauser-Feshbach computations and the predicted abundances, with the Pearson product-moment correlation coefficients $|r_\mathrm{P}| > 0.15$. We find that the discrepancies between the predicted and observed abundances of Ba and Pr in the CEMP-i star CS31062-050 are significantly diminished if the rate of $^{137}$Cs(n,$\gamma)^{138}$Cs is reduced and the rates of $^{141}$Ba(n,$\gamma)^{142}$Ba or $^{141}$La(n,$\gamma)^{142}$La increased. The uncertainties of temperature-dependent $\beta$-decay rates of the same unstable isotopes have a negligible effect on the predicted abundances. One-zone Monte-Carlo simulations can be used instead of computationally time-consuming multi-zone Monte-Carlo simulations in reaction rate uncertainty studies if they use comparable values of $N_\mathrm{n}$ (abridged)., Comment: 15 pages, 16 figures, 3 tables, accepted for publication in MNRAS

To compare the efficacy of transscleral cyclophotocoagulation with MicroPulseIn a prospective observational clinical study, 30 patients (30 eyes) with advanced open-angle glaucoma were randomized for either micropulse transscleral cyclophotocoagulation with 3000 mW or Ahmed valve implantation. Fifteen eyes were treated with transscleral cyclophotocoagulation with MicroPulseA reduction of the intraocular pressure30% was achieved in 33.3% of group A and in 73.3% of group B during the follow-up period of 12 months. A statistically significant decrease in the number of eye drops was observed in both groups (p0.01). 53.3% of the eyes of group A underwent additional anti-glaucoma procedures to achieve target intraocular pressure. The number of the local medications that were administered 12 months after the ocular surgery was 2 (± 1.3) in group A and 0.57 (± 0.9) in group B, compared to 3.2 (± 0.78) in group A and 3.33 (± 0.7) in group B administered prior to the surgery (p: 0.016). 8 eyes (53.33%) in group A were referred for additional treatment due to an acute postoperative rise in IOP (5 eyes: mTS-CPC, 1 eye: canaloplasty, 2 eyes: AGV implantation). No further anti-glaucoma procedures were necessary in group B.The Ahmed valve implantation achieves a more efficient decrease of the intraocular pressure as well as of the number of antiglaucoma agents than the transscleral cyclophotocoagulation with MicroPulse

In microinvasive glaucoma surgery (MIGS) the CyPass microstent (Alcon Inc.) was implanted in the suprachoroidal space to increase the uveoscleral outflow, thereby lowering the intraocular pressure. Due to the excessive loss of corneal endothelial cells, the implant was withdrawn from the global market in August 2018.A loss of corneal endothelial cells was observed in 6 patients (8 eyes in total) with early to moderate primary open-angle glaucoma 3 years after CyPass implantation. One eye developed a bullous keratopathy. In all patients an implant migration in the anterior chamber compared to the original postoperative position was detected, with more than one ring of the CyPass implant being visible in the anterior chamber.In all eight cases the CyPass implant was removed. The local therapy with cortisone eye drops in combination with a 5% sodium chloride solution did not improve chronic corneal edema in one patient. Therefore, a Descemet membrane endothelial keratoplasty (DMEK) was performed with postoperative improvement of visual acuity.In patients with more than one visible ring of the CyPass implant in the anterior chamber and subsequent localized loss of corneal endothelial cells, CyPass trimming or removal is recommended to avoid the progression of generalized corneal endothelial cell reduction and the onset of refractory, chronic corneal edema.HINTERGRUND: In der mikroinvasiven Glaukomchirurgie (MIGS) wurde der CyPass Micro-Stent (Alcon Inc.) in den suprachoroidalen Raum implantiert, um den uveoskleralen Abfluss zu verstärken und somit den Augeninnendruck zu senken. Aufgrund des Verlustes von Hornhautendothelzellen wurde das Implantat im August 2018 vom weltweiten Markt genommen.Drei Jahre nach der CyPass-Implantation wurde bei 6 Patienten (insgesamt 8 Augen) mit frühem bis mäßigem primärem Offenwinkelglaukom ein Verlust von Hornhautendothelzellen beobachtet. Bei einem Auge entwickelte sich eine bullöse Keratopathie. Bei allen Patienten wurde eine Implantatmigration in der Vorderkammer im Vergleich zur ursprünglichen postoperativen Position festgestellt, wobei mehr als ein Ring des CyPass-Implantats sichtbar war.In allen 8 Fällen erfolgte die Entfernung des CyPass-Implantats. Die lokale Therapie mit kortisonhaltigen Augentropfen in Kombination mit einer 5%igen Natriumchloridlösung verbesserte das chronische Hornhautödem bei einem Patienten nicht. Daher erfolgte eine DMEK („Descemet membrane endothelial keratoplasty“) mit postoperativer Verbesserung des Visus.Bei Patienten mit mehr als einem sichtbaren Ring des CyPass-Implantats und einem lokalisierten Verlust der Hornhautendothelzellen wird die CyPass-Kürzung oder Entfernung empfohlen, damit das Fortschreiten der generalisierten Reduktion der Hornhautendothelzellen und das Auftreten eines therapieresistenten, chronischen Hornhautödems vermieden wird.

During the last decade Descemet membrane endothelial keratoplasty (DMEK) has been established as a surgical treatment even for complex cases of bullous keratopathy.In a case series 9 eyes from 8 patients with chronic corneal edema caused by multiple intraocular operations underwent DMEK surgery. It was the sole surgical procedure in three eyes. In one case DMEK was combined with an intravitreal injection of bevacizumab, with opacified intraocular lens exchange in a second case, with transscleral cyclophotocoagulation with Iridex micropulse laser (Iridex, Silicon Valley, CA, USA) and intravitreal injection of bevacizumab in a third case and with the Tutopatch® (DMR srl, Italy) coverage of a scleral perforation in a fourth case. Additionally, DMEK was combined with trimming of the Ahmed valve tube length in two cases. The follow-up period was 12 months.Out of 9 eyes 2 showed a persistent partial or total detachment of the graft with concomitant recurrence of bullous keratopathy despite repeated injection of 20% sulfur hexafluoride (SF6) in the anterior chamber. These 2 eyes were treated with penetrating keratoplasty and achieved satisfactory postoperative results including pain relief. Visual acuity did not improve in these 2 eyes due to optic atrophy. Visual acuity and pain improved in the first postoperative month in 7 eyes. Donor endothelial cell density decreased from 2465±147/mmAlthough DMEK is a technically demanding surgical treatment for complicated cases of severe bullous keratopathy, it provides satisfactory results in terms of the improvement of visual acuity, pain relief and a shorter postoperative period.HINTERGRUND: Die DMEK („Descemet Membrane Endothelial Keratoplasty“) hat sich in den letzten Jahren als operatives Verfahren auch zur Behandlung von komplizierten Fällen einer Hornhautdekompensation mit bullöser Keratopathie etabliert.In dieser Fallserie wurden 9 Augen von 8 Patienten mit fortgeschrittener Hornhautdekompensation bei Zustand nach multiplen intraokularen Eingriffen mit einer DMEK therapiert. Bei jeweils 1 Auge wurde die DMEK mit einer intravitrealen Gabe von Bevacizumab, mit einem IOL-Austausch, mit einer transskleralen MicroPulse-Zyklophotokoagulation (Iridex, Silicon Valley, Kalifornien, USA) sowie einer intravitrealen Gabe von Bevacizumab und der Deckung einer Skleraperforation mittels Tutopatch® (DMR srl, Italien) und bei 2 Augen mit einer Kürzung des Drainageschlauchs des Ahmed-Valve-Implantats kombiniert. Bei 3 Patienten erfolgte die DMEK als alleiniger operativer Eingriff. Die Beobachtungszeit liegt bei 12 Monaten.Bei 2 von 9 Augen erfolgte bei abgehobener Lamelle und persistierender Hornhautdekompensation trotz wiederholten Rebubblings eine perforierende Keratoplastik mit guten postoperativen Ergebnissen. Eine Visusbesserung konnte bei diesen 2 Augen aufgrund einer vorbestehenden Optikusatrophie nicht erzielt werden, die perforierende Keratoplastik bewirkte jedoch Schmerzfreiheit. Diese 2 Augen wurden von der Datenauswertung der Fallserie ausgeschlossen, sodass die Ergebnisse aus den restlichen 7 Augen generiert wurden. Ein Visusanstieg und Schmerzfreiheit wurden bei allen diesen 7 Augen durch die DMEK innerhalb eines Jahres erreicht. Die Endothelzelldichte der Spenderhornhaut reduzierte sich von 2465 (±147) auf 1295 ± 254 und 1180 ± 197/mmDie DMEK ist eine technisch anspruchsvolle operative Therapieoption in der Behandlung von komplizierten Fällen einer Hornhautdekompensation mit bullöser Keratopathie, die sich durch zufriedenstellende Visusergebnisse, Schmerzfreiheit und eine verkürzte Heilungsphase auszeichnet.

Purpose: To estimate a risk–benefit ratio by comparing the efficacy of canaloplasty to trabeculectomy exclusively in pseudophakic eyes with primary open angle glaucoma. Patients and methods: One hundred four eyes that underwent ab externo canaloplasty and 136 eyes that underwent trabeculectomy with mitomycin C 0.02% and collagen matrix implantation were retrospectively compared. The efficacy was evaluated by evaluating the absolute success rate (5 ⩽ intraocular pressure ⩽ 15 mmHg) and the qualified success rate (intraocular pressure ⩽15 mmHg) using the Kaplan–Meier survival analysis. A meta-analysis to evaluate the relative risk of both procedures in relation to post-operative interventions was performed. Results: Mean intraocular pressure was significantly lower in both groups. Intraocular pressure decreased by 32.17% in the canaloplasty group and by 55.04% in the trabeculectomy group at 12 months (analysis of variance, p Conclusion: The trabeculectomy group showed better results in terms of absolute success rate. However, canaloplasty may provide a better risk–benefit ratio in terms of qualified success rate, hospitalization time, and required post-operative interventions, since canaloplasty yielded equal or superior results compared to trabeculectomy.

Purpose: To compare the efficacy and safety of PreserFlo (TM) MicroShunt (Santen, Osaka, Japan) combined with phacoemulsification to PreserFlo (TM) MicroShunt as a standalone procedure in eyes with moderate to advanced open-angle glaucoma. Methods: In an observatory, prospective, clinical study, 30 patients (30 eyes) with moderate to advanced angle glaucoma were allocated to either PreserFlo (TM) MicroShunt combined with phacoemulsification (15 eyes; Group A) or PreserFlo (TM) MicroShunt as a standalone procedure (15 eyes; Group B). The follow-up time of the study was 12 months. Results: Average intraocular pressure (IOP) at 12 months was 11.62 +/- 1.6 mmHg in Group A and 13.8 +/- 3.6 mmHg in Group B, which was significantly lower than baseline IOP (Group A: 23.47 +/- 8.99 mmHg, P < 0.001; Group B: 23.4 +/- 8.68 mmHg, P < 0.001). The absolute reduction of IOP within the 12 postoperative months was not significantly different between the two groups (P = 0.056). The number of the topical medications that were administered 12 months after ocular surgery was 0 in Group A and 0.6 +/- 0.8 in Group B, compared to 3.13 +/- 1.02 in Group A (P < 0.001) and 2.4 +/- 1.45 in Group B (P = 0.004) at baseline. Phacoemulsification combined with PreserFlo (TM) MicroShunt significantly reduced the number of antiglaucoma agents after 12 months compared to the standalone procedure (P = 0.026). One eye in Group A was referred for bleb revision due to bleb fibrosis and a consequent acute postoperative rise in IOP. One eye in Group A required transscleral cyclophotocoagulation with MicroPulse (R) laser. One bleb revision was also necessary in Group B at the 4th postoperative week. Endothelial cell density did not significantly change over 12 months in either group (Group A: baseline, 2017.3 +/- 346.8 cells/mm(2); 12 months, 1968.5 +/- 385.6 cells/mm(2); P = 0.38; Group B: baseline, 2134.1 +/- 382.6 cells/mm(2); 12 months, 2094.4 +/- 373.3 cells/mm(2), P = 0.42). The PreserFlo (TM) MicroShunt combined with phacoemulsification produced higher absolute success rates after 12 months in patients with moderate to advanced open-angle glaucoma than the PreserFlo (TM) MicroShunt as standalone procedure (Group A: 80% and Group B: 60%, P = 0.022). Conclusions: In eyes with moderate to advanced open-angle glaucoma, PreserFlo (TM) MicroShunt with or without phacoemulsification is effective in reducing IOP and the number of the antiglaucoma agents with a very small incidence of complications and subsequent glaucoma surgeries. However, adding phacoemulsification to PreserFlo (TM) MicroShunt successfully reduces IOP without the need for ongoing topical medications as are needed after the standalone procedure.

Proton-and alpha-capture reactions on unstable proton-rich nuclei power astrophysical explosions like novae and X-ray bursts. Direct measurements of these reactions are crucial for understanding the mechanisms behind these explosions and the nucleosynthesis at such sites. The recoil mass separator, SECAR (SEparator for CApture Reactions) at the National Superconducting Cyclotron Laboratory (NSCL) and the Facility for Rare Isotope Beams (FRIB), has been designed with the required sensitivity to study (p,γ) and (α,γ) reactions, directly at astrophysical energies in inverse kinematics, with radioactive beams of masses up to about A = 65. The complete SECAR system, including two Wien Filters for high mass resolution, has been installed at Michigan State University and is currently being commissioned. The present article introduces the SECAR concept, its scientific goals, and provides an update of the current status of the project.

We have developed and tested an experimental technique for the measurement of low-energy (p,n) reactions in inverse kinematics relevant to nuclear astrophysics. The proposed setup is located at the ReA3 facility at the National Superconducting Cyclotron Laboratory. In the current approach, we operate the beam-transport line in ReA3 as a recoil separator while tagging the outgoing neutrons from the (p,n) reactions with the low-energy neutron detector array (LENDA). The developed technique was verified by using the $^{40}$Ar(p,n)$^{40}$K reaction as a probe. The results of the proof-of-principle experiment with the $^{40}$Ar beam show that cross-section measurements within an uncertainty of $\sim$25\% are feasible with count rates up to 7 counts/mb/pnA/s. In this article, we give a detailed description of the experimental setup, and present the analysis method and results from the test experiment. Future plans on using the technique in experiments with the separator for capture reactions (SECAR) that is currently being commissioned are also discussed., Comment: Submitted to NIMA. Revised manuscript after referees' first review

On the context of the Cern n_TOF collaboration the 232Th(n,2n)231Th reaction cross section has been measured relative to the 56Fe(n,p)56Mn and 27Al(n,a)24Na reaction cross sections by the activation method for neutron energies up to 11 MeV. The neutrons were produced via the 2H(d,n) reaction using a deuterium filled gas-cell, at the 5.5MV TANDEM Accelerator of NCSR "Demokritos". In addition to the experimental work, theoretical Statistical model calculations have been performed using the computer code STAPRE/F. The code STAPRE is designed to calculate energy averaged cross sections for particle induced nuclear reactions with several emitted particles and gamma rays under the assumption of sequential evaporation. For the first evaporation step preequilibrium emission is taken into account while population of states resulting from the first equilibrium evaporation step is calculated using the Hauser-Feschbach theory. Fission process competition is also taken into account in the evaporation steps. Sensitive parameters for the calculation, like level density parameters, have been adopted after fitting experimental data for the competing (n,f) reaction. The results are being compared to the experimental data.

Purpose To investigate histopathologic, immunohistochemical, and electron microscopic findings in 8 keratoplasty specimens with a history of corneal collagen crosslinking (CXL) for keratoconus. Five new (hitherto unreported) and 3 previously published specimens were analyzed. Methods Corneal buttons of 8 keratoconus corneas (5-114 months after CXL) were compared with 5 keratoconus specimens without CXL and 5 normal corneas for morphological alterations. Corneal buttons were evaluated by light microscopy and immunohistochemistry using antibodies against CD34, PGP 9.5, nestin, telomerase reverse transcriptase, and Ki67 as well as by transmission electron microscopy. Results Keratoconus corneas after CXL showed a significant keratocyte loss (except 1 specimen with an increased keratocyte number), whereas keratoconus corneas without CXL revealed a higher keratocyte density compared with healthy controls. Keratocyte loss could be clinically correlated with corneal opacification and corneal perforation. In corneas after CXL, the remaining keratocytes appeared more polymorphic and revealed a different expression of surface markers similar to keratocytes in corneal scars. The presence of proteoglycans, nerves, and endothelial cells was unaffected by CXL. Conclusions CXL may cause permanent keratocyte loss or repopulation of altered keratocytes, resulting in clinical complications such as corneal opacification or perforation. Despite its good safety profile and high effectiveness in progressive keratoconus, CXL should be performed in accordance with current guidelines strictly adhering to protocol and safety standards.

In the 5.5 MV tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" monoenergetic neutron beams can be produced in the energy ranges 120-650 keV, 4-11.5 MeV and 16-20.5 MeV by using the 7 Li(p,n), 2 H(d,n) and 3 H(d,n) reactions, respectively. The corresponding beam energies and ions delivered by the accelerator, are 1.92-2.37 MeV protons, 0.8-9.6 MeV deuterons and 0.8-3.7 MeV deuterons, for the three reactions, respectively. Experimental results for neutron energies from threshold up to 11.5 MeV and at 17.1 MeV will be given for the 232 Th(n,2n) 231 Th reaction, while for the 241 Am(n,2n) 240 Am reaction, preliminary cross section data at 10.4, 10.6 and 17.1 MeV will be discussed. In the framework of the CERN n-TOF collaboration, the cross section of these reactions have been measured relative to the 197 Au(n,2n) 196 Au, 27 Al(n,a) 24 Na and 93 Nb(n,2n) reaction cross sections, by using the activation method. In addition to the experimental work, theoretical Statistical model calculations are being carried out using the computer code STAPRE/F. The results are compared to the experimental data.

We present an account of the current status of the theoretical treatment of inclusive $(d,p)$ reactions in the breakup-fusion formalism, pointing to some applications and making the connection with current experimental capabilities. Three independent implementations of the reaction formalism have been recently developed, making use of different numerical strategies. The codes also originally relied on two different but equivalent representations, namely the prior (Udagawa-Tamura, UT) and the post (Ichimura-Austern-Vincent, IAV) representations. The different implementations have been benchmarked, and then applied to the Ca isotopic chain. The neutron-Ca propagator is described in the Dispersive Optical Model (DOM) framework, and the interplay between elastic breakup (EB) and non-elastic breakup (NEB) is studied for three Ca isotopes at two different bombarding energies. The accuracy of the description of different reaction observables is assessed by comparing with experimental data of $(d,p)$ on $^{40,48}$Ca. We discuss the predictions of the model for the extreme case of an isotope ($^{60}$Ca) currently unavailable experimentally, though possibly available in future facilities (nominally within production reach at FRIB). We explore the use of $(d,p)$ reactions as surrogates for $(n,\gamma)$ processes, by using the formalism to describe the compound nucleus formation in a $(d,p\gamma)$ reaction as a function of excitation energy, spin, and parity. The subsequent decay is then computed within a Hauser-Feshbach formalism. Comparisons between the $(d,p\gamma)$ and $(n,\gamma)$ induced gamma decay spectra are discussed to inform efforts to infer neutron captures from $(d,p\gamma)$ reactions. Finally, we identify areas of opportunity for future developments, and discuss a possible path toward a predictive reaction theory.

In this contribution we discuss new experimental approaches to indirectly provide information on neutron-capture rates relevant to the $r$-process. In particular, we focus on applications of the Oslo method to extract fundamental nuclear properties for reaction-rate calculations: the nuclear level density and the $\gamma$ strength function. Two methods are discussed in detail, the Oslo method in inverse kinematics and the beta-Oslo method. These methods present a first step towards constraining neutron-capture rates of importance to the $r$-process.

Systematic experimental and theoretical investigations of the 72,73Ge(n,p)72,73 Ga and 72,74Ge(n,α)69,71Znm reaction cross sections are presented in the energy range from thresh- old to about 17 MeV neutron energy. The above reaction cross sections were measured from 8.8 to 11.4 MeV by using the activation method, relative to the 27Al(n,α)24Na refer- ence reaction. The quasi-monoenergetic neutron beams were produced via the 2H(d,n)3He reaction at the 5 MV VdG Tandem T11/25 accelerator of NCSR “Demokritos”. Statisti- cal model calculations using the code EMPIRE-II (version 2.19) taking into consideration pre-equilibrium emission were performed on the data measured in this work as well as on data reported in literature.

The proton capture reaction cross sections on 116Sn and 118Sn have been determined at astrophysically relevant energies by means of activation, 7-ray angular distribution and angle-integrated 7-flux measurements. The results of the present work together with those obtained in previous measurements are compared to the predictions of the Hauser-Feshbach theory.

The cross section of the reaction 2ilAm(n, 2n), has been measured by the activation method in the range from 9.6 to 11.4 MeV, at the Tandem accelerator facility of NCSR Demokritos. Statistical model calculations in the framework of the Hauser- Feshbach theory have been performed, and the first results are presented. Experimental data on the neutron induced fission cross section of 241Am, have been used as a constraint for the calculations. The results of the investigation are presented in comparison with experimental data and previous theoretical evaluations.

The neutron facility at the 5.5 MV Tandem Tll/25 accelerator of NCSR "Demokritos" has been used to produce monoenergetic neutron beams in the energy range 120-650 keV and 4-11.5 MeV via the 7Li(p,n) and 2H(d,n) reactions, respectively. The flux variation of the neutron beam was monitored by using a BF3 detector, while an investigation of the energy dependence of the neutron fluence has been carried out with a liquid scintillator BC501A detector as well as with the multiple foil activation technique. The 232Th(n,2n)231Th and 241Am(n,2n)240Am as well as (n,2n), (n,p) and (η,α) reactions on natural Ge and Hf isotopes, have been investigated from threshold up to 11.5 MeV, by using the activation method.

Cross section measurements of deuteron-induced reactions on Ni and Ge isotopes have been carried out at energies well below the Coulomb barrier. The preliminary results are compared with statistical model calculations

The Low Energy Neutron Detector Array (LENDA) is a neutron time-of-flight (TOF) spectrometer developed at the National Superconducting Cyclotron Lab- oratory (NSCL) for use in inverse kinematics experiments with rare isotope beams. Its design has been motivated by the need to study the spin-isospin response of unstable nuclei using (p, n) charge-exchange reactions at intermediate energies (> 100 MeV/u). It can be used, however, for any reaction study that involves emission of low energy neutrons (150 keV - 10 MeV). The array consists of 24 plastic scintillator bars and is capable of registering the recoiling neutron energy and angle with high detection efficiency. The neutron energy is determined by the time-of-flight technique, while the position of interaction is deduced using the timing and energy information from the two photomultipliers of each bar. A simple test setup utilizing radioactive sources has been used to characterize the array. Results of test measurements are compared with simulations. A neutron energy threshold of < 150 keV, an intrinsic time (position) resolution of \sim 400 ps (\sim 6 cm) and an efficiency > 20 % for neutrons below 4 MeV have been obtained., Version accepted for publication in Nucl. Instr. Methods A. Revised text, 2 new figures added (one in section 4 and one in section 7)

The first-peak s-process elements Rb, Sr, Y and Zr in the post-AGB star Sakurai's object (V4334 Sagittarii) have been proposed to be the result of i-process nucleosynthesis in a post-AGB very-late thermal pulse event. We estimate the nuclear physics uncertainties in the i-process model predictions to determine whether the remaining discrepancies with observations are significant and point to potential issues with the underlying astrophysical model. We find that the dominant source in the nuclear physics uncertainties are predictions of neutron capture rates on unstable neutron rich nuclei, which can have uncertainties of more than a factor 20 in the band of the i-process. We use a Monte Carlo variation of 52 neutron capture rates and a 1D multi-zone post-processing model for the i-process in Sakurai's object to determine the cumulative effect of these uncertainties on the final elemental abundance predictions. We find that the nuclear physics uncertainties are large and comparable to observational errors. Within these uncertainties the model predictions are consistent with observations. A correlation analysis of the results of our MC simulations reveals that the strongest impact on the predicted abundances of Rb, Sr, Y and Zr is made by the uncertainties in the (n, γ) reaction rates of 85Br, 86Br, 87Kr, 88Kr, 89Kr, 89Rb, 89Sr, and 92Sr. This conclusion is supported by a series of multi-zone simulations in which we increased and decreased to their maximum and minimum limits one or two reaction rates per run. We also show that simple and fast one-zone simulations should not be used instead of more realistic multi-zone stellar simulations for nuclear sensitivity and uncertainty studies of convective–reactive processes. Our findings apply more generally to any i-process site with similar neutron exposure, such as rapidly accreting white dwarfs with near-solar metallicities.

Nuclear reactions where an exotic nucleus captures a neutron are critical for a wide variety of applications, from energy production and national security, to astrophysical processes, and nucleosynthesis. Neutron capture rates are well constrained near stable isotopes where experimental data are available; however, moving far from the valley of stability, uncertainties grow by orders of magnitude. This is due to the complete lack of experimental constraints, as the direct measurement of a neutron-capture reaction on a short-lived nucleus is extremely challenging. Here, we report on the first experimental extraction of a neutron capture reaction rate on ^{69}Ni, a nucleus that is five neutrons away from the last stable isotope of Ni. The implications of this measurement on nucleosynthesis around mass 70 are discussed, and the impact of similar future measurements on the understanding of the origin of the heavy elements in the cosmos is presented.

Cross section measurements of the 174 Hf(n, 2n) 173 Hf reaction have been carried out at the VdG Tandem accelerator of NCSR “Demokritos” in Athens, Greece in the neutron energy range 9.8–11.5 MeV, using the activation technique. Statistical model calculations based on the Hauser–Feshbach theory have also been performed by using the code EMPIRE-II with different sets of input parameters. The predictions were compared with the data of the present work as well as with data from literature.

Systematic experimental and theoretical investigations of the 70,72,73,74 Ge(n, p) 70,72,73,74 Ga reaction cross-sections are presented in the energy range from threshold to about 17 MeV neutron energy. The 72,73 Ge(n, p) 72,73 Ga reaction cross-sections were measured from 8.8 to 11.4 MeV by using the activation method, relative to the 27 Al(n, α ) 24 Na reference reaction. The quasi-monoenergetic neutron beams were produced via the 2 H(d, n) 3 He reaction at the 5 MV Van de Graaff (VdG) Tandem T11/25 accelerator of NCSR “Demokritos”. Statistical model calculations using the code EMPIRE (version 2.19) and taking into account pre-equilibrium emission were performed on the data measured in this work as well as on data reported in the literature.

The neutron facility at the 5.5 MV tandem T11/25 Accelerator of NCSR “Demokritos” can deliver monoenergetic neutron beams in the energy range from thermal to 450 keV, 4–11.5 MeV and 16–20.5 MeV via the 7Li(p,n), 2H(d,n) and 3H(d,n) reactions, respectively. The flux variation of the neutron beam is monitored by using a BF3 counter and a liquid scintillator BC501A detector. The 232Th(n,2n)231Th and 241Am(n,2n)240Am as well as (n,2n), (n,p) and (n,α) reactions on natural Ge and Hf isotopes, have been investigated from threshold up to 11.5 MeV, by using the activation method. The cross section values have been determined relative to the 197Au(n,2n)196Au, 27Al(n,α)24Na and 93Nb(n,2n) reference reaction cross sections.

The measurement of the cross section of the reaction 241Am(n,2n)240Am has been performed at neutron energies from 8.8 to 11.1 MeV, implementing the activation technique. The neutron beam was produced at the TANDEM accelerator of NCSR “Demokritos” by the 2H(d,n)3He reaction, using a deuterium gas target. During the 5-day long irradiation, the neutron beam fluctuations were monitored in 100 seconds intervals by a BF3 counter connected with a multiscaling unit. The radioactive target consisted of a 37 GBq 241Am source enclosed in a Pb container. A natural Au foil, a 27Al foil and a 93Nb foil were used as reference materials for the neutron flux determination. After the end of the irradiation the activity induced at the target and the reference foils, was measured off-line by a 56% HPGe detector.

We have undertaken the study of 6 Li breakup on a 28 Si target near the Coulomb barrier through an angular distribution measurement. Alpha particles were recorded in coincidence with deuterons in order to determine exclusively the breakup of lithium. The results are analysed and are discussed, in a continuum discretized coupled channel framework (CDCC).

In the present work the radiation damage effects induced by 5.88 MeV protons in Si and InP crystals, of ∼400 and 325 μm thickness, respectively, are examined and analyzed for high fluences ranging between 10 16 and 10 18 particles/cm 2 . The irradiation occurs in the random mode by constantly rotating the targets in order to minimize the channeling perturbations, while the control of the induced damage is performed by utilizing the RBS/C technique on the inverse side of the crystals, implementing the proton beam at a reduced energy ( E p = 1.2 MeV). The experimental results reveal impressive extensions of the damage profiles well beyond the end of range of implanted protons. Conventional theoretical calculations, as well as standard SRIM predictions, seem to underestimate the induced effects. An attempt is made in order to explain the experimental spectra via the adoption of the Coulomb explosion model and the results are compared to other already existing in literature for different beam–target combinations.

The production of α-particles in the reactions 6,7 Li+ 28 Si was studied as a means to disentangle the various reaction channels at near-barrier energies. The competition between compound and direct reactions was determined by using the shape of angular distributions and statistical model calculations. DWBA calculations were also performed to probe the various direct channels. It was found that, approaching barrier, transfer channels are the most dominant for both reactions. For 7 Li+ 28 Si d-transfer is one of the contributing channels without excluding t-transfer, while for 6 Li+ 28 Si, n-transfer and p-transfer have substantial contribution but without excluding d-transfer.

ReA is a reaccelerator of rare-isotope beams at the National Superconducting Cyclotron Laboratory (NSCL). The rare isotopes are produced by fast projectile fragmentation. After production, they are separated in-flight and thermalized in a He gas “catcher” cell before being sent to ReA for reacceleration to a few MeV/u. One of its main components is an electron-beam ion trap (EBIT) employed to convert injected singly charged ions to highly charged ions prior to injection into linear-accelerator structures. The ReA EBIT features a high-current electron gun, a long trap structure, and a two-field superconducting magnet to provide both the high electron-beam current density needed for fast charge breeding and high capture probability of injected beams. This paper presents recent commissioning results. In particular, 39 K + ions have been injected, charge bred to 39 K 16 + and extracted for reacceleration up to 60 MeV. First charge-breeding results of beams injected from a commissioning Rb ion source in the NSCL’s beam “stopping” vault are also presented.

In the present work, the determination of Be concentration in soil, asphalt and concrete samples using several IBA (ion beam analysis) techniques (PIGE – particle induced gamma-ray emission, and NRA – nuclear reaction analysis/charged-particle spectroscopy) is presented. The samples originated from various areas of the former airport of Athens that is now closed to be used as an Olympic site. The main characteristic of the samples analyzed is their complex matrix consisting of light elements in high concentrations. For such matrices, the implementation of a deuteron beam at energies between 1 and 2.1 MeV, via the 9Be(d, nγ)10B reaction, seems to be the most sensitive among the applied IBA techniques. A HP Ge detector of 20% relative efficiency was used to detect the 718 keV γ-ray of 10B. The absolute γ-ray yield of the 9Be(d, nγ)10B reaction is presented and an attempt is made in order to evaluate the applicability of PIGE in the determination of trace Be quantities in complex matrices. The results are compared to existing literature data obtained with other IBA techniques (e.g. heavy-ion spectroscopy).

We have measured the response of an array of monitored drift tubes (MDT) to fast neutrons produced by a t(d,n)/sup 4/He reaction at the TANDEM Van de Graaff accelerator of the National Center of Scientific Research (NCSR) "Demokritos". The MDT setup consisted of 24 drift tubes operating with a gas mixture of ArCO/sub 2/ (93:7%) at 3 bar absolute pressure. The neutron energy was 18.3 MeV. The operating anode wire voltage varied from 2200 V to 2800 V. The PC based data acquisition system was self-triggered by the OR of all 24 MDT. Data were also taken by triggering on a single tube. The data analysis is presented and the response of the MDT detector to energetic neutrons is discussed with emphasis on the determination of the MDT sensitivity to neutrons.

In the present work, the dechanneling of protons in Si [110] is studied combining theoretical Monte-Carlo and phenomenological simulation results in the energy range E p =1.8-2.4 MeV. The applicability of a Gompertz type sigmoidal dechanneling function, with two parameters, k and xc, which represent characteristic dechanneling rate and range, respectively, is examined, yielding the successful reproduction of backscattering spectra of channeled protons along the Si [110] crystal axis. The results are compared to the ones obtained in the past for different beam - crystal orientation combinations and an attempt is made to explain the occurring similarities and discrepancies.

Si(100) and (111) crystals were irradiated in the random as well as in the channeling direction, using 5 MeV F-19(+) ions, to a maximum fluence of approximately 1 x 10(17) particles/cm(2). The occurring deep implanted profiles were subsequently investigated using the Resonant Nuclear Reaction Analysis technique in the energy range E-p = 950-1200 keV. The reaction F-19(p, alphay)O-16 reaction exhibits a strong resonant behavior in the above mentioned energy range, thus providing an excellent tool for the depth profiling of fluorine, yielding minimum detection limits of the order of a few ppm. The occurring profiles are analyzed with SRIM and c-TRIM codes and an attempt is made to explain the characteristics of the experimental spectra, as well as to compare with results already existing in literature. (C) 2003 Elsevier Science B.V. All rights reserved. Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions with Materials and Atoms

The 6 Li + 28 Si elastic scattering was studied at near-barrier energies with the aim to probe the threshold anomaly. Angular distributions were measured over a wide angular range (θlab = 25 ◦ to 150 ◦ ) at 4 energies, namely, 7.5, 9, 11 and 13 MeV. The present data together with previous ones at higher energies, as well as elastic scattering data of 6 Li on various targets at near barrier energies, were analyzed by using optical potentials obtained in a double-folding framework. It was found that the strength of the real part of the potential remains almost independent of energy down to, and possible even below, barrier, while the strength of the imaginary part presents an increase at near barrier energies. The results are discussed.  2003 Elsevier Science B.V. All rights reserved.