旨在实现太位(Terabit)级密度的存储器研究项目

IBM公司的科学家向世人展示了他们运用新颖的纳米技术实现的1Terabit（一万亿位）每平方英寸数据存储密度——这一数值比当今市面上存储密度最高的磁性存储器高20倍。这项被称为Millipede的研究项目采用的是由位于显微机械加工的悬臂（Micromachined Cantilever）末端的受热硅探头触点（ProbeTip）在旋转磁盘的表面形成软化凹陷的方法来生成数据位。 在实际操作中。

扩展休克尔理论对NaCl晶体电子结构的研究

结合特殊点方案，利用自包容子程序，应用扩展休克尔理论到离子晶体．计算了NaCl晶体的电子结构，进行了理论分析，找出了NaCl晶体的能隙和价带宽度，定性解释了中性基态Na原子的低能ESD实验的结果．

Azobenzene/graphene hybrid for high-density solar thermal storage by optimizing molecular structure

A large capacity storing solar energy as latent heat in a close-cycle is essentially important for solar thermal fuels. This paper presents a solar thermal molecule model of a photo-isomerizable azobenzene(Azo) molecule covalently bound to graphene. The storage capacity of the Azo depending on isomerization enthalpy(ΔH) is calculated based on density functional theory. The result indicates that the ΔH of Azo molecules on the graphene can be tuned by electronic interaction, steric hindrance and molecular hydrogen bonds(H-bonds). Azo with the withdrawing group on the ortho-position of the free benzene shows a relatively high ΔH due to resonance effect. Moreover, the H-bonds on the trans-isomer largely increase ΔH because they stabilize the trans-isomer at a low energy. 2-hydroxy-4-carboxyl-2′,6′,-dimethylamino-Azo/graphene shows the maximum ΔH up to 1.871 e V(107.14 Wh kg^(-1)), which is 125.4% higher than Azo without functional groups. The Azo/graphene model can be used for developing high-density solar thermal storage materials by controlling molecular interaction.

Fabrication of Large Area High Density, Ultra-Low Reflection Silicon Nanowire Arrays for Efficient Solar Cell Applications

High density vertically aligned and high aspect ratio silicon nanowire （SiNW） arrays have been fabricated on a Si substrate using a template and a catalytic etching process. The template was formed from polystyrene （PS） nanospheres with diameter 30-50 nm and density 10^10/cm^2, produced by nanophase separation of PS-containing block-copolymers. The length of the SiNWs was controlled by varying the etching time with an etching rate of 12.5 nm/s. The SiNWs have a biomimetic structure with a high aspect ratio （-100）, high density, and exhibit ultra-low reflectance. An ultra-low reflectance of approximately 0.1% was achieved for SiNWs longer than 750 nm. Well-aligned SiNW/poly（3,4-ethylenedioxy-thiophene）：poly（styrenesulfonate） （PEDOT：PSS） heterojunction solar cells were fabricated. The n-type silicon nanowire surfaces adhered to PEDOT：PSS to form a core-sheath heterojunction structure through a simple and efficient solution process. The large surface area of the SiNWs ensured efficient collection of photogenerated carriers. Compared to planar cells without the nanowire structure, the SiNW/PEDOT：PSS heterojunction solar cell exhibited an increase in short-circuit current density from 2.35 mA/cm^2 to 21.1 mA/cm^2 and improvement in power conversion efficiency from 0.4% to 5.7%.

Design and synthesis of low band gap non-fullerene acceptors for organic solar cells with impressively high J_(sc) over 21 m A cm^(-2)

Three low bandgap non-fullerene acceptors based on thieno[3,2-b]thiophene fused core with different ending groups, named TTIC-M, TTIC, TTIC-F were designed and synthesized. Using a wide bandgap polymer PBDB-T as donor to form a complementary absorption in the range of 300–900 nm, high efficencies of 9.97%, 10.87% and 9.51% were achieved for TTIC-M, TTIC and TTFC-F based photovoltaic devices with impressively high short circuit current over21 mA cm^-2.

Averaged NmF2 of cusp-latitude ionosphere in northern hemisphere for solar minimum—Comparison between modeling and ESR during IPY

Based on the ionosphere observation data obtained by EISCAT Svalbard Radar (ESR) in solar minimum year-2007, we analyzed diurnal variations of F2-peak electron density (NmF2) in four seasons under disturbed and quiet geomagnetic conditions. It indicated that the soft precipitation electron had an evident effect on the NmF2 increase at magnetic noon in spring, summer and autumn and the electron precipitation effects were prominent in winter. The comparison between the IRI-2007 model and the observation exhibited that the IRI (International Reference Ionosphere) model had a better NmF2 prediction when the photoionization was dominant during the polar day, but worse when the electron precipitation was dominant during the polar night. We showed that the electrons in lower energy band decreased when the geomagnetic disturbance went greater, which resulted in the lower NmF2. By analyzing the spectrum of precipitation electron under different geomagnetic conditions, it was found that this phenomenon was induced by the energy flux enhancement of precipitation electron of low energy.

Efficacy evaluation of different forms of traditional Chinese health-preservation exercises for osteoporosis:a network meta-analysis

Objective To systematically evaluate the effects of different forms of traditional Chinese health-preservation exercises on osteoporosis(OP)using network meta-analysis.Methods A systematic search on Excerpta Medica Database(EMBASE),Springer Link,Allied and Complementary Medicine Database(AMED),PubMed,Cochrane Library,China National Knowledge Infrastructure(CNKI),Wanfang Academic Journal Full-text Database(Wanfang)and Chongqing VIP Database(CQVIP)targeted the randomized controlled trials(RCTs)studying traditional Chinese exercises for OP published up to January 2020.Cochrane handbook was adopted to estimate the publication bias in the included studies,and statistical analysis was performed using Stata 14.0 and GeMTC 0.14.3 when data were extracted.Results Fifty RCTs were included in the network meta-analysis,comprising a total of 4505 OP patients.The network meta-analysis showed that in terms of visual analog scale(VAS)for pain,Tai Ji Quan(Tai Chi)was the most efficacious,followed by Yi Jin Jing(Sinew-transforming Qigong Exercises),Ba Duan Jin(Eight-sectioned Exercise),Wu Qin Xi(Five-animal Exercises),sports training,drug and blank control;in terms of bone mineral density(BMD)of femoral neck,Yi Jin Jing was the most efficacious,followed by Wu Qin Xi,Ba Duan Jin,Tai Ji Quan,sports training,blank control and drug;regarding the lumbar BMD,it was Yi Jin Jing,Tai Ji Quan,Ba Duan Jin,Wu Qin Xi,sports training,blank control and drug in the descending order of efficacy;in terms of serum alkaline phosphatase,it was Yi Jin Jing,Tai Ji Quan,sports training,Wu Qin Xi,Ba Duan Jin,drug and blank control in the descending order of efficacy.Conclusion The evidence to date suggests that the first choice for OP amongst the traditional Chinese exercises should be Yi Jin Jing,which can not only reduce the subjective pain,but also promote bone formation and increase BMD,though this conclusion requires more high-quality large-scale RCTs for further proof.

Vertical structure of longitudinal differences in electron densities at mid-latitudes

By using Constellation Observing System for Meteorology, Ionosphere, and Climate satellite observa- tions, and Global Ionosphere and Thermosphere Model simulations, the altitudinal dependences of the longitudinal differences in electron densities Ne were studied at mid- latitudes for the first time. Distinct altitudinal dependences were revealed： （1） In the northern （southern） hemisphere, there were wave-1 variations mainly in the daytime in the altitudes below 180 km, but wave-2 （wave-l） variations over a whole day above 220 km; （2） a transition （or sep- aration） layer occurred mainly in the daytime within 180 and 220 km, showing reversed longitudinal variation from that at lower altitudes. Solar illumination was one of the plausible mechanisms for the zonal difference of Ne at lower altitudes. At higher altitudes, both neutral winds and solar illumination played important roles. The neutral winds effects accounted for the longitudinal differences in Ne in the European-Asian sector. Neutral composition changes and neutral wind effects both contributed to the formation of the transition layer.

Nighttime electron density enhancements at middle and low latitudes in East Asia

Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.

Enhanced performance of CdS/CdSe quantum dotsensitized solar cells by long-persistence phosphors structural layer

Light absorption plays an important role in improving the power conversion efficiency(PCE)of quantum dot-sensitized solar cells(QDSSCs).In this study,a multifunctional long-persistence phosphor(LPP)layer was introduced into the CdS/CdSe QDSSCs via a simple doctor blade method.The LPP layer can simultaneously improve the light harvesting and photo charge transfer in CdS/CdSe QDSSCs.As a result,their short-circuit current and corresponding PCE are effectively enhanced.The PCE can reach up to 5.07%,which is about 24%larger than that of the conventional CdS/CdSe QDSSCs without LPP layer.The solar cells can work in dark for a while due to the long-lasting fluorescence of the LPP layer.This research provides an effective way to improve the PCE of QDSSCs,and finds the possibility for all-weather QDSSCs.

Theoretical studies of the structures and spectroscopic properties of the photoelectrochemical cell ruthenium sensitizers,C101 and J13

A variety of heteroleptic ruthenium sensitizers have been engineered and synthesized because of their higher light-harvesting efficiency and lower charge-recombination possibility than the well known homoleptic N3 dye. As such, a great deal of atten- tion has been focused on sensitizers with the general formula Ru（ancillary-ligand）（anchoring-ligand）（NCS）2, among which important examples are Ru（4,4＇-bis（5-hexylthiophen-2-yl）-2,2＇-bipyridine）（4,4＇-carboxylic acid-4＇-2,2＇-bipyridine）（NCS）2 （C101） and Ru（N-（4-butoxyphenyl）-N-2-pyridinyl-2-pyridinamine）（4,4＇-carboxylic acid-4＇-2,2＇-bipyridine）（NCS）2 （J13）. In order to simulate experimental conditions with different pH values, the photosensitizing processes of these sensitizers pos- sessing different degrees of deprotonation （2I-I, lit to OH） have been explored theoretically in this work. Their ground/excited state geometries, electronic structures and spectroscopic properties are first calculated using density functional theory （DFT） and time-dependent DFT （TDDFT）. The absorption and emission spectra of all the complexes in acetonitrile solution are also predicted at the TDDFT （B3LYP） level. The calculated results show that the ancillary ligand contributes to the molecular or- bital （MO） energy levels and absorption transitions. It is intriguing to observe that the introduction of a thiophene group into the ancillary ligand leads directly to the increased energy of the absorption transitions in the 380-450 nm region. The calcula- tions reveal that although deprotonation destabilizes the overall frontier MOs of the chromophores, it tends to exert a greater influence on the unoccupied orbitals than on the occupied orbitals. Consequently, an obvious blue shift was observed for the absorptions and emissions in going from 21-1, 1H to OH. Finally, the optimal degree of deprotonation for C101 and J13 has al- so been evaluated, which is expected to lead to further improvements in the performance of dye-sensitized solar cells （DSSCs） coated with such sensitizers.

Influence of the layer parameters on the performance of the CdTe solar cells

Influence of the layer parameters on the performances of the CdTe solar cells is analyzed by SCAPS-1 D. The Zn O: Al film shows a high efficiency than SnO_2:F. Moreover, the thinner window layer and lower defect density of Cd S films are the factor in the enhancement of the short-circuit current density. As well, to increase the open-circuit voltage, the responsible factors are low defect density of the absorbing layer CdTe and high metal work function. For the low cost of cell production, ultrathin film CdTe cells are used with a back surface field(BSF) between CdTe and back contact, such as PbTe. Further, the simulation results show that the conversion efficiency of 19.28% can be obtained for the cell with 1-μm-thick CdTe, 0.1-μm-thick PbTe and 30-nm-thick CdS.

Al-doping effects on the photovoltaic performance of inverted polymer solar cells

The properties of Al-doped Zn O(AZO) play an important role in the photovoltaic performance of inverted polymer solar cells(PSCs), which is used as electron transport and hole blocking buffer layers. In this work, we study the effects of Al-doping level in AZO on device performance in detail. Results indicate that the device performance intensely depends on the Al-doping level. The AZO thin films with Al-doping atomic percentage of 1.0% possess the best conductivity. The resulting solar cells show the enhanced short current density and the fill factor(FF) simultaneously, and the power conversion efficiency(PCE) is improved by 74%, which are attributed to the reduced carrier recombination and the optimized charge transport and extraction between AZO and the active layer.

Model for increased efficiency of CIGS solar cells by a stepped distribution of carrier density and Ga in the absorber layer

In this paper, several structures for multilayer Cu(In1-xGax) Se2 (CIGS) thin film solar cells are proposed to achieve high conversion efficiency. All of the modeling and simulations were based on the actual data of experimentally produced CIGS cells reported in the literature. In standard CIGS cells with a single absorber layer, the effects of acceptor density and Ga content on device performance were studied, and then optimized for maximum conversion efficiency. The same procedure was performed for cells with two and three sectioned CIGS absorber layers in which Cu and/or Ga contents were varied within each consecutive section. This produces an internal additional electric field within the absorber layer, which resulted in an increase in carrier collection for longer wavelength photons, and hence, improvement in the conversion efficiency of the cell. An increase of approximately 3% in efficiency is predicted for cells with two layer absorbers. For multilayer cells in which Cu and Ga distribution were stepped simultaneously, the improvement could be approximately 3.5%. This improvement is due to; enhanced carrier collection for longer-wavelength photons, and reduced recombination at the heterojunction and back regions of the cell. These results are confirmed by the physics of the cells.