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Multijunction solar cells offer a route to exceed the Shockley-Queisser limit for single-junction devices. In a few short years, silicon-perovskite tandems have significantly passed the efficiency of the best silicon single-junction cells. For scalable solution processing of silicon-perovskite tandem devices, with the avoidance of vacuum processing steps, a flat silicon sub-cell is normally required. This results in a flat top surface that can lead to higher optical reflection losses than conformal deposition on textured silicon bottom cells. To overcome this, textured anti-reflective coatings (ARCs) can be used on top of the finished cell, with textured polydimethylsiloxane (PDMS), a promising candidate. In this work, we vary the texture geometry and film thickness of PDMS anti-reflective foils to understand the effect of these parameters on reflectance of the foil. The best film is selected, and anti-reflective performance is compared with two common planar ARCs-lithium fluoride (LiF) and magnesium fluoride (MgF

(主査) 教授 田口 茂, 准教授 近藤 智彦, 准教授 コーカー・ケイトリン・クリスティーン, 准教授 張 政遠（東京大学）, 文学研究科（思想文化学専攻）

Horizon scanning is intended to identify the opportunities and threats associated with technological, regulatory and social change. In 2017 some of the present authors conducted a horizon scan for bioengineering (Wintle et al., 2017). Here we report the results of a new horizon scan that is based on inputs from a larger and more international group of 38 participants. The final list of 20 issues includes topics spanning from the political (the regulation of genomic data, increased philanthropic funding and malicious uses of neurochemicals) to the environmental (crops for changing climates and agricultural gene drives). The early identification of such issues is relevant to researchers, policy-makers and the wider public.

The purpose of this study was to estimate the frequency of retained ballistic fragment (RBF) removal and to identify factors associated with an increased risk for RBF removal. To date, there are no studies focused on identifying factors associated with removal of RBFs localized to the maxillofacial region.Using a retrospective cohort study design, the authors enrolled a sample composed of patients with RBFs localized to the maxillofacial region. The predictor variables included bullet size, location, involvement of bone, involvement of sinus, antibiotics, multiple antibiotics, and multiple locations. The primary outcome variable was RBF retrieval. The secondary outcome variables were timing of operative retrieval, fragment site infection, and migration of RBF. Appropriate uni- and bivariate statistics were computed and logistic regression modeling was used.The sample was composed of 20 patients (mean age, 30 yr; 80% male) and 55% (11 patients) required or desired object removal overall. The number of projectiles ranged from 1 to 19 (total, 48) in the 20 patients. The logistic model identified larger size, final location of bone, final location of soft tissue, and final location of sinus as having a higher probability of removal that was statistically significant (P .05); however, size was the only variable with a substantial odds ratio (OR; 1.96; P .05). There was no evidence of migration and a low rate (2.3%) of infection was noted at subsequent follow-up radiography and clinical examination.Size was the only statistically significant predictor variable with a substantial OR (1.96; 95% confidence interval, 1.31-3.40; P .05). There was a low risk of infection even when considering oral pharyngeal contamination and low risk of migration. Further studies could focus on prudent antibiotic use and larger patient populations.

Historians have not yet attempted to integrate the global nature of Britain’s war with the process and outcome of military learning, and British approaches are generally presented as being compartmentalised within each theatre. This article demonstrates that in the crucial field of coastal air power, while intra-theatre learning processes were important, the British were indeed capable of inter-theatre learning. A symbiotic, mutually beneficial relationship evolved between the Home and Mediterranean theatres that contributed positively to its development. However, they failed to create a similar arrangement for the Indian Ocean, which could only act as a receptor for externally created knowledge. Cognisance of these inter-theatre links helps us to understand the cause of Britain’s vital success in the maritime environment, which was utterly essential to Allied victory in the Second World War. It also offers a wider insight into British approaches to learning during the war.

Advances in biological engineering are likely to have substantial impacts on global society. To explore these potential impacts we ran a horizon scanning exercise to capture a range of perspectives on the opportunities and risks presented by biological engineering. We first identified 70 potential issues, and then used an iterative process to prioritise 20 issues that we considered to be emerging, to have potential global impact, and to be relatively unknown outside the field of biological engineering. The issues identified may be of interest to researchers, businesses and policy makers in sectors such as health, energy, agriculture and the environment.

The Mediterranean was a vital artery of the British Empire. It was a strategic corridor, linking Britain to its Middle and Far East possessions and precious resources. Its control was a central tenet of British imperial strategy, yet by the mid-1930s, this faced a new challenge from Fascist Italy. The Italian Navy was central to expansionist aspirations and forced British reappraisals of the allocation of defence resources both in the Mediterranean and elsewhere. It therefore came to exert a generally under-appreciated influence on prewar British imperial defence policy and war planning.Although consistently viewed as vastly inferior to the Royal Navy, it was still seen as an impediment to Britain’s ability to deliver imperial defence across the globe, or conduct a worldwide war against multiple enemies. This view persisted even after important defeats were inflicted on it in 1940-41, and continued right through to 1943. Awareness of the seriousness with which the British viewed Italian naval strength adds important context to debates about British strategy in the Far East and over Winston Churchill's preference for a 'Mediterranean first' strategy. Italian naval power played a greater role in shaping the Allied prosecution of the Second World War than is commonly accepted.

During World War II, the British ran a sustained anti-shipping campaign against Axis merchant and supply traffic in the Mediterranean. Although the effects of this on the land war in North Africa have been the subject of much debate, little attention has been paid to the nature and prosecution of the campaign itself. This article analyses the changes in British attitudes and policy towards attacking merchant shipping prior to and throughout the campaign. It then goes on to examine the conduct of the campaign itself and compare it with other British efforts elsewhere during the war. It concludes that the anti-shipping campaign in the Mediterranean was a unique combined arms offensive for the British, and a major evolution in their attitudes and policy towards maritime total war.

The exiled navies of many Allied nations came under British operational control in World War II. Six of these contributed significant proportions of their submarine fleets to the Mediterranean, where there was great need for them, yet troubled relations meant multinational naval cooperation (MNC) was often extremely difficult. British attempts to establish structures to improve this were frequently hampered, while perceived differing strategic “worth” led the British to treat their new allies in an unequal manner. Ultimately, while MNC was broadly successful in the British home theatre, it was much less effective in the Mediterranean and valuable resources subsequently went underused.

By specifically binding derivatized colloidal particles and physisorbing nonderivatized particles to the surface of a quartz crystal microbalance (QCM), we have observed positive shifts of frequency, Deltaf, in contrast to the negative frequency shifts typically found in adsorption experiments. Evidently, the Sauerbrey relation does not apply to this situation. A comparison of frequencies shifts and bandwidths on different overtones reveals a coupled resonance: at low overtones, Deltaf is negative, whereas it is positive at high overtones, with maximal resonance bandwidth observed at the crossover point. As predicted by the Dybwad model, the spheres bound to the surface form resonating systems on their own. A composite resonator is formed, consisting of a large crystal with resonance frequency omega and the adsorbed spheres with resonance frequency omega(S). In the case in which the resonance frequency of the small spheres (firmly attached to crystal), omega(S), is higher than the resonance frequency of the crystal, omega, Deltaf of the composite system is negative (leading to the Sauerbrey limit). In the opposite limit (that is, in the case of large adsorbed particles bound to the sensor surface via a sufficiently weak bridge) Deltaf is positive. Such a behavior is known from sphere-plate contacts in the dry state. Finite element calculation demonstrates that this phenomena is also plausible in liquid phase media, with Deltaf critically dependent on the strength of the sphere-plate contact. Operated in this mode, the QCM most likely probes the contact strength, rather than the mass of the particle.

Introduction. Cervical complications secondary to motor vehicle accidents (MVA) continues to be an area where patients experi- ence long-term complications despite having received therapy. Many of these problems relate to the delicate structures associated with the cervical spine and the precise alignment needed. We report on the findings of a specific cohort of patients from our larger multicenter study that presented

Effect of strained-Si thickness on electrical properties of furnace grown gate oxide has been investigated. Interface state density ( D it ) versus energy characteristics shows that D it increases with decreasing strained-Si thickness, probably due to the presence of Ge at the interface. From conductance measurement, two different types of traps are observed in the gate oxide. In thinner strained-Si samples, the onset of F–N tunneling happens at higher voltages, indicating thicker gate oxide. Gate voltage oscillations were observed during constant current stress under gate injection at low stress current. This sinusoidal characteristics are possibly due to the trapping and detrapping of charges in the oxide.

Carrier generation lifetime ( τ g ) in strained-Si/SiGe has been investigated using capacitance transient method in MOS structure. Interface properties of thermally grown gate oxide on strained-Si/SiGe has been studied prior to transient capacitance measurements. Average midgap value of interface state density ( D it ) extracted from quasi-static CV measurement is around 2×10 10 to 5×10 10 cm −2 eV −1 for both strained-Si and bulk-Si samples. The observed non-linear behavior of capacitance transient characteristics for strained-Si/SiGe heterostructure are due to the carrier confinement in the potential wells caused by virtue of the valence band and conduction band discontinuities. Generation lifetime in strained-Si and SiGe buffer layer estimated from the segments of Zerbst plot having different slopes. The value of generation lifetime in strained-Si, SiGe buffer and co-processed bulk-Si is ranges from 120 to 170 μs, 20 to 90 μs and 177 μs, respectively.

This article discusses the historical events that occurred in the early years of metamaterials leading to the current development of metamaterials in the Defense Advanced Research Projects Agency, Department of Defense, and Ministry of Defence.

During the Second World War, the British conducted a sustained campaign of interdiction against Axis supply shipping in the Mediterranean Sea. Air power became a crucial component of this campaign, but was initially highly unsuccessful, delivering few results at a heavy cost. However, a combination of factors, including technical and tactical development, a greater allocation of resources and a higher level of priority being accorded to the campaign, led to vast improvements. By the end of the campaign, the British were conducting highly effective anti-shipping operations, and air power was vital to this in both intelligence gathering and strike roles.

SiGe-free strained Si on insulator substrates were fabricated by wafer bonding and hydrogen-induced layer transfer of strained Si grown on bulk relaxed Si0.68Ge0.32 graded layers. Raman spectroscopy shows that the 49-nm thick strained Si on insulator structure maintains a 1.15% tensile strain even after SiGe layer removal. The strain in the structure is thermally stable during 1000 °C anneals for at least 3 min, while more extreme thermal treatments at 1100 °C cause slight film relaxation. The fabrication of epitaxially defined, thin strained Si layers directly on a buried insulator forms an ideal platform for future generations of Si-based microelectronics.

Strained-Si nMOSFETs with a standard polysilicon gate process were fabricated down to 25 nm gate length with well-behaved characteristics and small difference in short channel effects. The performance enhancement degrades linearly as the gate length becomes shorter, due to not only the parasitic resistance but also heavy halo implant. Thus the key integration issues are how to manage threshold difference and As diffusion without excess doping. With comparable doping and well controlled parasitic resistance, up to 45% improvement in drive current is predicted for sub-50 nm gate length strained-Si nMOSFETs on the Si/sub 0.8/Ge/sub 0.2/ substrate. In this work approximately 45% enhancement is in fact demonstrated for 35 nm gate length devices, through advanced channel engineering and implementation of metal gates.

Three topics in particular in the National Curriculum can benefit from use of the varied resources of the Internet. This article explains how to make the most of them.

Total and monomethyl mercury were measured at 39 river sites in Wisconsin during fall 1992 and spring 1993. Using a Geographic Information System (GIS), we delineated watersheds with unique and homogeneous physical characteristics. Mean unfiltered total Hg (Hg T ) was higher in spring (7.94 ng L -1 ) than in fall (3.45 ng L -1 ). Major differences in Hg T yields were observed among various land-use groupings. In wetland/forest watersheds, elevated Hg T fluxes were associated with the filtered phase, while in agricultural watersheds, increased Hg T fluxes were due to particle loading. Monomethylmercury (MeHg) yields from wetland/forest sites were higher than agricultural/forest sites and agricultural only sites. Percent wetland surface area was positively correlated with MeHg yield. These results identify the importance of land use and land cover in influencing Hg concentrations, speciaton, and transport in rivers.

The probability of a spin flip of an electron is calculated. It is assumed that the electron resides in a uniform magnetic field and interacts with an incoming electromagnetic pulse. The scattering matrix is constructed and the time needed to flip the spin is calculated., Comment: 4 pages, 0 figures

Background Nucleic acid based recognition of viral sequences can be used together with label-free biosensors to provide rapid, accurate confirmation of viral infection. To enhance detection sensitivity, gold nanoparticles can be employed with mass-sensitive acoustic biosensors (such as a quartz crystal microbalance) by either hybridising nanoparticle-oligonucleotide conjugates to complimentary surface-immobilised ssDNA probes on the sensor, or by using biotin-tagged target oligonucleotides bound to avidin-modified nanoparticles on the sensor. We have evaluated and refined these signal amplification assays for the detection from specific DNA sequences of Herpes Simplex Virus (HSV) type 1 and defined detection limits with a 16.5 MHz fundamental frequency thickness shear mode acoustic biosensor. Results In the study the performance of semi-homogeneous and homogeneous assay formats (suited to rapid, single step tests) were evaluated utilising different diameter gold nanoparticles at varying DNA concentrations. Mathematical models were built to understand the effects of mass transport in the flow cell, the binding kinetics of targets to nanoparticles in solution, the packing geometries of targets on the nanoparticle, the packing of nanoparticles on the sensor surface and the effect of surface shear stiffness on the response of the acoustic sensor. This lead to the selection of optimised 15 nm nanoparticles that could be used with a 6 minute total assay time to achieve a limit of detection sensitivity of 5.2 × 10-12 M. Larger diameter nanoparticles gave poorer limits of detection than smaller particles. The limit of detection was three orders of magnitude lower than that observed using a hybridisation assay without nanoparticle signal amplification. Conclusions An analytical model was developed to determine optimal nanoparticle diameter, concentration and probe density, which allowed efficient and rapid optimisation of assay parameters. Numerical analysis and subsequent associated experimental data suggests that the response of the mass sensitive biosensor system used in conjunction with captured particles was affected by i) the coupled mass of the particle, ii) the proximal contact area between the particle and the sensor surface and iii) the available capture area on the particle and binding dynamics to this capture area. The latter two effects had more impact on the detection limit of the system than any potential enhancement due to added mass from a larger nanoparticle.