Formation of an Icosahedral Structure during the Freezing of Gold Nanoclusters: Surface-Induced Mechanism

The freezing behavior of gold nanoclusters was studied by employing molecular dynamics simulations based on a semi-empirical embedded-atom method. Investigations of the gold nanoclusters revealed that, just after freezing, ordered nano-surfaces with a fivefold symmetry were formed with interior atoms remaining in the disordered state. Further lowering of temperatures induced nano-crystallization of the interior atoms that proceeded from the surface towards the core region, finally leading to an icosahedral structure. These dynamic processes explain why the icosahedral cluster structure is dominantly formed in spite of its energetic metastability.Comment: 9 pages, 4 figures(including 14 eps-files

An Improved Upper Bound for the Ring Loading Problem

The Ring Loading Problem emerged in the 1990s to model an important special case of telecommunication networks (SONET rings) which gained attention from practitioners and theorists alike. Given an undirected cycle on $n$ nodes together with non-negative demands between any pair of nodes, the Ring Loading Problem asks for an unsplittable routing of the demands such that the maximum cumulated demand on any edge is minimized. Let $L$ be the value of such a solution. In the relaxed version of the problem, each demand can be split into two parts where the first part is routed clockwise while the second part is routed counter-clockwise. Denote with $L^*$ the maximum load of a minimum split routing solution. In a landmark paper, Schrijver, Seymour and Winkler [SSW98] showed that $L \leq L^* + 1.5D$, where $D$ is the maximum demand value. They also found (implicitly) an instance of the Ring Loading Problem with $L = L^* + 1.01D$. Recently, Skutella [Sku16] improved these bounds by showing that $L \leq L^* + \frac{19}{14}D$, and there exists an instance with $L = L^* + 1.1D$. We contribute to this line of research by showing that $L \leq L^* + 1.3D$. We also take a first step towards lower and upper bounds for small instances

Characteristics of Medial-Lateral Postural Control While Exposed to the External Perturbation in Step Initiation

Controllability of posture in the medial-lateral direction is critical for balance maintenance, particularly in step initiation. The objective of the current study was to examine the effects of external perturbation and landing orientation on medial-lateral control stability in step initiation. Eleven young healthy participants stood on the force platform and waited for the instruction of taking a step while experiencing a pendulum perturbation applied at the lateral side of the right shoulder. Eight experimental conditions were conducted by two levels of step side (right or left), two levels of perturbation (with or without), and two levels of landing orientation (forward or diagonal). The center of pressure (COP), pelvic movements, and muscle activities were recorded and analyzed as the onset of COP and pelvic movement, the COP displacement, and cocontraction and reciprocal muscle activation pattern. The temporal events of COP and pelvic movement were not significantly different in all experimental conditions. However, COP and pelvic movement were significantly later in the diagonal condition. Most of the segments showed reciprocal muscle activation patterns in relation to the perturbation released time. Subsequently, all segments showed cocontraction muscle activation patterns, which was significantly affected by step side, perturbation, and orientation. The results suggest that how the CNS initiated a step was identical with the COP then pelvic movement. The outcome highlights the importance of external perturbation and foot landing orientation effects on postural adjustments, which may provide a different approach to help step initiation

Free Energy Approach to the Formation of an Icosahedral Structure during the Freezing of Gold Nanoclusters

The freezing of metal nanoclusters such as gold, silver, and copper exhibits a novel structural evolution. The formation of the icosahedral (Ih) structure is dominant despite its energetic metastability. This important phenomenon, hitherto not understood, is studied by calculating free energies of gold nanoclusters. The structural transition barriers have been determined by using the umbrella sampling technique combined with molecular dynamics simulations. Our calculations show that the formation of Ih gold nanoclusters is attributed to the lower free energy barrier from the liquid to the Ih phases compared to the barrier from the liquid to the face-centered-cubic crystal phases

PENINGKATAN KESIAPSIAGAAN MASYARAKAT DALAM MENGHADAPI BENCANA MELALUI MEDIA BOOKLET DI KELURAHAN TANJUNG KABUPATEN ENDE

Kabupaten Ende memiliki beberapa wilayah yang kerap diguncang gempa dan tsunami salah satunya kelurahan Tanjung di kecamatan Ende Selatan. Kesiapsiagaan seluruh lapisan masyarakat akan bencana alam menjadi langkah strategis untuk meminimalisir kerugian-kerugian tersebut. Peran media pembelajaran sangatlah penting dalam mempengaruhi proses sehingga proses pembelajaran tidak monoton dan lebih mudah untuk dipahami. Tujuan Kegiatan pengabdian masyarakat ini adalah meningkatkan kesiapsiagaan masyarakat dalam menghadapi bencana di kelurahan Tanjung Kecamatan Ende Tengah Kabupaten Ende, Provinsi NTT. Tahapan - tahapan yang akan dilakukan dalam penyelesaian permasalahan adalah sebagai berikut Observasi lapangan, Identifikasi permasalahan, Penawaran Solusi, Perancangan kegiatan, Implementasi, Evaluasi dan Monitoring dan Integrasi tambahan. Metode yang digunakan dalam kegiatan pengabdian masyarakat ini adalah screening, ceramah, diskusi, simulasi dan praktek. Pelaksanaan pengabdian pada masyarakat ini berlansung dengan baik dan penuh antusiasme dari masyarakat. Dari hasil observasi lapangan yang tim lakukan terlihat bahwa pemahaman masyarakat akan bencana masih sangat kurang, sehingga masalah pengetahuan sasaran masih menjadi fokus intervensi kegiatan. Kegiatan pendidikan kebencanaan berbasis media booklet cukup membantu masyarakat mengetahui apa dan bagaimana menyikapi bencana. Media booklet di anggap sbagai media yang sangat tepat karena mudah digunakan dan mudah pahami dengan gambar-gambar. Berdasarkan hasil kegiatan pengabdian kepada masyarakat menunjukkan bahwa pengetahuan responden mayoritas berkategori kurang yakni 29 orang responden (96.7.%).  Sedangkan untuk sikap masyoritas sasaran masuk dalam kategori kurang yakni sebanyak 28 orang responden (93.3%)  dan untuk keterampilan sasaran menunjukkan sebagian besar responden masuk kategori cukup yaitu sejumlah 19 orang responden (63.3%)

Diffusion-enhanced exciton dissociation in single-material organic solar cells

Single-material organic solar cells have recently attracted research attention due to their simplicity, morphological robustness and high yield of exciton dissociation. Using α-sexithiophene as a model system, we show that the single-event probability of the exciton dissociation at the boundaries of polycrystalline domains with different molecular orientation is extremely low (∼0.5%), while a high efficiency of charge generation is gained via hundred-fold crossings of the domain boundaries due to the long exciton diffusion length (∼45 nm). This journal i

Dual-function artificial molecular motors performing rotation and photoluminescence

Molecular machines have caused one of the greatest paradigm shifts in chemistry, and by powering artificial mechanical molecular systems and enabling autonomous motion, they are expected to be at the heart of exciting new technologies. One of the biggest challenges that still needs to be addressed is designing the involved molecules to combine different orthogonally controllable functions. Here, we present a prototype of artificial molecular motors exhibiting the dual function of rotary motion and photoluminescence. Both properties are controlled by light of different wavelengths or by exploiting motors’ outstanding two-photon absorption properties using low-intensity near-infrared light. This provides a noninvasive way to both locate and operate these motors in situ, essential for the application of molecular machines in complex (bio)environments