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Background Contralateral C7 (CC7) nerve transfer has successfully restored hand function in patients with spastic hemiplegia from chronic central nervous system injuries. However, little is known about the morphology and anatomy of the donor C7 nerve root in patients undergoing this procedure. This study quantified intraoperative measurements of donor C7 nerve roots during CC7 transfer surgery for spastic hemiplegia in patients treated at a high-volume center to describe observed anatomical variations for successful direct anastomosis. Methods A database of images from 21 patients (2 females, 19 males) undergoing CC7 surgery was searched for photographic data that contained a standard ruler measuring donor C7 nerve root length after surgical sectioning and before transfer. Two independent observers analyzed these images and recorded C7 nerve root diameter, length, and branch lengths. Results Mean (SD) values of donor C7 nerve measurements were length, 53.5 (8.0) mm; diameter, 5.1 (0.9) mm; branch length following surgical sectioning, 18.3 (6.3) mm. Right-sided donor C7 nerve roots yielded significantly longer branches compared with left-sided donor C7 nerve roots (P = 0.01). Other patient factors such as age, sex, or laterality of brain injury did not influence intraoperative anatomy. Conclusions We report detailed intraoperative measurements of the donor C7 root during CC7 nerve transfer for spastic hemiplegia. These findings describe existing variation in surgical C7 nerve root anatomy in patients undergoing this procedure and may serve as a general reference for the expected donor C7 length in successful direct anastomosis.

Corticospinal neurons (CSNs) undertake direct cortical outputs to the spinal cord and innervate the upper limb through the brachial plexus. Our previous study has shown that the contralateral middle trunk transfer to the paralyzed upper extremity due to cerebral injury can reconstruct the functional cerebral cortex and improve the function of the paralyzed upper extremity. To interpret the cortical reconstruction and the motor improvement after the middle trunk transfer, we explored the distribution of CSNs connecting to the middle, upper, and lower trunk of the brachial plexus by retrograde trans-neuronal tracing using pseudorabies virus (PRV-EGFP or PRV-mRFP). We show that, rather than an individual specific area, these CSNs labelled by each trunk of the brachial plexus were widespread and mainly assembled within the primary motor cortex (M1), secondary motor cortex (M2), primary somatosensory cortex (S1), and slightly within the secondary somatosensory cortex (S2). The three trunk-labelled CSNs were intermingled in these cortices, and mostly connected to more than two trunks, especially the middle trunk-labelled CSNs with higher proportion of co-labelled neurons. Our findings revealed the distribution features of CSNs connecting to the adjacent spinal nerves that innervate the upper limb, which can improve our understanding of the corticospinal circuits associated with motor improvement and the functional cortical reconstruction after the middle trunk transfer.

Background: Since January 2020, COVID-19 has spread globally to more than 210 countries, and the epidemic lasted for more than 11 months. Scientists have studied many effective prevention and control strategies. Based on real-time big data on COVID-19 pneumonia captured by the Baidu App, our study aimed to analyse the characteristics of the COVID-19 pandemic in 10 epicentre countries. It also aimed to discuss the impact of politics, economy, and humanities on COVID-19 as well as effective strategies of prevention and control the epidemic. Methods: Based on the real-time big data report of the new coronavirus pneumonia epidemic in Baidu APP, collected from January 27 to December 22, 2020. Incidence and death data in the world and China, India, Europe UK, Italy, France, Spain, Russia, America Brazil, the United States, Mexico were collected.1 Excel 2016 was used to build a database and performed linear fitting analysis, R3.6.3 and ggplot2 package was used for descriptive statistical analysis. Current status and trends of morbidity and mortality in the world and epicenter countries were analyze. Findings: To December 22, 2020, in the recent 5 days, the top two incidence cases were America with 1,079,385 cases, and the United Kingdom with 197,037 cases; the bottom two were China with 507 cases, and Mexico 48,416 cases. The top two mortality cases were America with 12,180 cases, and Brazil with 3,500 cases; the bottom two were China 7 Cases, and Spain 664 cases. The top two incidence rates were in America 0.3303%, and the United Kingdom 0.2959%;the bottom two were in China 0.0000%,and India 0.0097%.The top two mortality rates were in Italy 0.0044%, and the United Kingdom 0.0042%;the bottom two were in China 0.0000%,and India 0.0001%.From January 27 to December 22, 2020,The top two cumulative confirmed cases were in America with 18,494,265 cases, and India with 10,094,801 cases; the bottom two were China 95,998 cases, and Mexico 1,325,915 cases. The top two incidence rate were America 5.6597%,and Spain 3.9442%;the bottom two were China 0.0069%, and India 0.7624%.The top two mortality cases were America with 327,171 cases, and Brazil with 187,322 cases; the bottom two were China with 4,773 cases, and Spain with 49,260 cases. The top two mortality rates were Italy 0.1144%,and Spain 0.1062%;the bottom two were China 0.0003%,and India 0.0111%.Compared with the global cumulative incidence rate general trend (κ=0.0141), there are significant differences between America (κ=0.0716), Brazil (κ=0.0579), Spain (κ=0.0547), and China (κ=4E-05). Compared with the global incidence rate in recent trend (κ=0.0283), there are obvious differences between America (κ=0.2962), Italy (κ=0.2171), France (κ=0.1840), and China (κ=1E-05).Compared with the global cumulative mortality general trend (κ=0.0003), there are significant differences between Brazil (κ=0.0016),America and Mexico (κ=0.0015), Spain and the United Kingdom (κ=0.0014), Italy (κ=0.0013), and China (κ=3E-06).Compared with the global incidence rate in recent trend (κ=0.0006), there are significant differences between Italy (κ=0.0048), France (κ=0.0037), America (κ=0.0033), and China (κ=E-07). Interpretation: The lives of people in India, the United States and most of epicenter countries in European and American are suffering from grave damage. The mutation of Coronavirus has made the already serious epidemic worse. The current epidemic situation in the epicenter country and the mutation of Coronavirus also pose a serious threat to the lives of people in the non-epicenter country. It is urgent to construct a new anti-epidemic strategy based on aseptic technology to end the devastation caused by Coronavirus to human beings. Funding Statement: The Key Projects of Research and Development of Hainan Province (No.: ZDYF2020109) Declaration of Interests: We declare no competing interests.

Usually, heat transfer coefficient of a high-viscosity fluid is very low at a small Reynolds number to avoid a huge pressure drop. Using twisted tube is an effect way to improve its heat transfer performance without obviously increasing its pressure drop. In this study, the heat transfer performance of epoxy resin, which is a kind of high-viscosity fluid, flowing in horizontal twisted tubes with different short-long-diameter ratios and twist ratios, was investigated. The impacts of Reynolds number, short-long-diameter ratios and twist ratios on heat transfer coefficients and pressure drops were discussed. The experimental results revealed that horizontal twisted tubes were commendable enhanced tubes for improving the heat transfer performance of the high-viscosity fluid. In addition, compared with twist ratios, the short-long-diameter ratios played a more significant role in heat transfer performance and pressure drop.

Many study utilize formaldehyde as a reducing agent to prepare copper coating on carbon fibers surface to improve the interface between carbon fibers and metal matrix. But formaldehyde is harmful to the environment and health. The copper coating on carbon fibers was plated in the electroless bath with hypophosphite as a reducing agent in this study. And the effect of Ni2+ concentration in the bath on the deposition rate, morphology, microstructure and binding capacity of copper deposits were investigated. The deposition rate increases with the increase of Ni2+ concentration in the bath. And the deposition particle sizes of the Cu–Ni composite coating become larger from 0.13 µm to 1 µm with the addition of Ni2+ in the bath, which is due to the increase of accumulation rate of copper atoms with the increase of coating rate. It has a small granular growth into an island shape with the aggregation and growth of the particles. The large particles cause deep grooves, which accelerate crack growth. The results of the thermal shock test shown that the binding capacity is best when the Ni2+ concentration is 3.8 mmol/L in the bath. The number of cycles is 50 when the coating begins to deteriorate. The final number of cycle is 62 and the coating accompanied by gradual weightle loss. At this time, the coating has the optimal thickness and shedding mode, which makes the crack propagation need more energy. This work also provides a reference for the electroless copper plating formula with sodium hypophosphite as the reducing agent.

Background With the tremendous advances in the field of brain–computer interfaces (BCI), the literature in this field has grown exponentially; examination of highly cited articles is a tool that can help identify outstanding scientific studies and landmark papers. This study examined the characteristics of 100 highly cited BCI papers over the past 10 years. Methods The Web of Science was searched for highly cited papers related to BCI research published from 2006 to 2015. The top 100 highly cited articles were identified. The number of citations and countries, and the corresponding institutions, year of publication, study design, and research area were noted and analyzed. Results The 100 highly cited articles had a mean of 137.1(SE: 15.38) citations. These articles were published in 45 high-impact journals, and mostly in TRANSACTIONS ON BIOMEDICAL ENGINEERING (n = 14). Of the 100 articles, 72 were original articles and the rest were review articles. These articles came from 15 countries, with the USA contributing most of the highly cited articles (n = 52). Fifty-seven institutions produced these 100 highly cited articles, led by Duke University (n = 7). Conclusions This study provides a historical perspective on the progress in the field of BCI, allows recognition of the most influential reports, and provides useful information that can indicate areas requiring further investigation.

A minor diterpenoid with a novel carbon skeleton, secoeuphoractin ( 1 ), was isolated from an ethanol extract of the roots of Euphorbia micractina . Its structure including the absolute configuration was determined by extensive spectroscopic studies, especially by 2D NMR and CD data analysis, in combination with a plausible biosynthetic pathway associated with co-occurring diverse diterpenoids. This compound showed activity against HIV-1 replication with an IC 50 value of 1.76 ± 0.61 μmol/L.

LiBr refrigeration cooling water contains a lot of low-temperature heat source, can use this part of the heat source heat boiler feed water. This paper introduced LiBr refrigeration – heat pump system which recovery heat of the LiBr refrigeration cooling water by heat pump system to heat the feed water of boiler. Hot economic analysis on the system has been performed based on the experimental data. Results show that LiBr refrigeration-heat pump system brings 26.6 percent decrease in primary energy rate consumption comparing with the combined heat and power production system(CHP) and separate generation of cold

A novel process to recovery natural gas liquids from oil field associated gas with liquefied natural gas (LNG) cryogenic energy utilization is proposed. Compared to the current electric refrigeration process, the proposed process uses the cryogenic energy of LNG and saves 62.6% of electricity. The proposed process recovers ethane, liquid petroleum gas (propane and butane) and heavier hydrocarbons, with total recovery rate of natural gas liquids up to 96.8%. In this paper, exergy analysis and the energy utilization diagram method (EUD) are used to assess the new process and identify the key operation units with large exergy loss. The results show that exergy efficiency of the new process is 44.3%. Compared to the electric refrigeration process, exergy efficiency of the new process is improved by 16%. The proposed process has been applied and implemented in a conceptual design scheme of the cryogenic energy utilization for a 300 million tons/yr LNG receiving terminal in a northern Chinese harbor.

We report the role of anthraquinone sulfonate dopants in promoting performance of electro-synthesized polypyrrole (PPy) composites for use in electrochemical supercapacitors. The incorporation of anthraquinone sulfonate species into the polymer matrix can significantly improve the surface area of PPy composites that are composed of submicron-/nano-sized particles, as evidenced from scanning electron microscopy (SEM) results. Cyclic voltammetry and galvanostatic charge–discharge measurements in 1 M KCl solution reveal that these dopants result in an improved specific capacitance, a wide working potential range and enhanced long-cycle stability as compared to ClO4− dopant. Among the samples investigated, the resulting PPy/AQS (9,10-anthraquinone-2-sulfonic acid sodium salt) composite exhibits the highest specific capacitance of 608 F g−1 at a scan rate of 5 mV s−1 within a potential range between −0.9 and 0.5 V (vs. saturated calomel electrode, SCE).

The focusing properties of a concentric piecewise cylindrical vector beam is investigated theoretically in this paper. The beam consists of three portions with different and changeable phase retardation and polarization. Numerical simulations show that the evolution of the focal shape is very considerable by changing the radius and polarization rotation angle of each portion of the vector beam. And some interesting focal spots may occur, such as two- or three-peak focus, dark hollow focus, ring focus, and two-ring-peak focus. Corresponding gradient force patterns are also computed, and novel trap patterns, including cup shell shape trap with one trap at its each side along axis, rectangle shell shape trap with one trap at its each side, dumbbell optical trap, spherical shell optical trap, may occur, which shows that the concentric piecewise cylindrical vector beam can be used to construct controllable optical tweezers.

Blue ray optical storage is one of the important trends in the area of information storage, and attracts a number of researchers. Static tester for blue ray optical storage plays an important role in storage media research. We designed and constructed a static tester, in which modularization makes it very convenient to expand function. Employment of modulation/demodulation technique weakens test error so as to increase test precision. Focus move mode and the nano-positioners facilitate the relocation of recording marks. Only one laser with wavelength 406.7 nm is used. In this paper, system design and characteristics are represented in detail, and some experimental results are also given to show that the static tester can perform successfully, acting as research platform for blue ray optical storage.

Static recording characteristic of super-resolution near-field structure with antimony (Sb) is investigated in this paper. The recording marks are observed by a scanning electron microscopy (SEM), a high-resolution optical microscopy with a CCD camera and an atomic force microscopy (AFM). The super-resolution mechanism is also analyzed based on these static recording marks. Results show that the light reaching on recording layer is composed of two parts, one is the linear transmissive light (propagating field) and the other is the nonlinear evanescent light in the optical near field. The evanescent light may be greatly enhanced in the center of the spot because Sb will transit from a semiconductor to a metal when it is melted under the high laser power irradiation. This local melted area in the spot center may be like a metal tip in the optical near field that can collect and enhance the information that is far beyond the diffraction limit, which leads to the super-resolution recording and readout.

The effective refractive index of a kind of granular composite, which consists of granular metallic and magnetic inclusions with different radius embedded in a host medium, is theoretically investigated. Results show that for certain volume fractions of these two inclusions, the negative permittivity peak shifts to low frequency and the peak value increases with increasing radius ratio of the radius of magnetic granulae to that of metallic granulae. Simultaneously, peak value of permeability decreases with the radius ratio, and value peak shifts to high frequency with increasing volume fraction of magnetic inclusion. Therefore, the radius ratio can affect the effective refractive index considerably, and it is found that by adjusting the radius ratio, the refractive index may change between negative and positive values for certain volume fractions of the two inclusions.

In this paper, the evolution of the gradient force pattern, focal shift, and focal switch induced by a three-portion pure phase-shifting apodizer is numerically investigated in detail. The results show that the proposed apodizer may induce tunable gradient force on the particles in the focal region, focal shift, and focal switch. By adjusting the geometrical parameters of the phase-shifting apodizer, multiple traps may occur with changeable distance between them, and the shape of the optical trap also evolves evidently. More interestingly, for certain geometrical parameters of the proposed apodizer, by changing the phase shift of inner annular portion, the considerable focal shift may occur with focal switch accompanying, which is discussed to show that this kind of apodizer may be a very promising method of transporting trapped particles.

An ion beam aperture array lithography process was employed to fabricate highly ordered polymeric microfiltration membranes with pores that were nearly cylindrical and uniform in size. In this process, a stencil mask, containing a periodic array of circular openings (the aperture array) was irradiated by a broad beam of energetic (30 keV) helium ions. The ions passing through the openings exposed a resist on a substrate that was placed in close proximity thereby faithfully replicating the mask pattern. Over one hundred filters with either 200 or 350 nm diameter pore and pore densities varying from 2.5 × 107 to 4 × 108 # /cm2 were fabricated during the course of this study. Electron microscopy revealed that they all had highly uniform and equally spaced pores without any that overlapped. Additionally, the coefficient of variation of the pore diameter was less than 7% for all samples investigated revealing a very narrow pore size distribution in these membranes as well as a high degree of control of the lithography process. The effective filtration area of individual membranes manufactured in this study was only 0.25 cm2. However, we also show that our current manufacturing process can be scaled-up to fabricate larger areas at high throughput by employing larger masks.

The concentration of trace elements and their distribution in the late Permian coal in the Heshan coal field, Guangxi Autonomous Region, were analysed in this paper. The late Permian coal of the Heshan mining district was developed in a low energy and shallow, confined carbonate platform. Heshan coal is a low volatile bituminous coal characterized by a high sulphur content, ranging between 2.0% and 8.2%. Compared with the worldwide average content of the trace elements in coal, the content of some trace element in the study coal is markedly high (Bi, Ce, Cr, Cs, Cu, Ga, Hf, Sr, Ta, Th, U, V, W, Y, Zr, La, Mo, Nb and Sc). The trace element associations were investigated by means of intracorrelation analysis. Some elements, such as Cl, F and Sr are found in coal in association with the carbonate minerals. V, Cr, Zn, Mo, Ni and As contents in coal vary significantly amongst the coal samples. They are mainly concentrated in the lower part of the coal #4 upper of Suhe and Lilan mines and the coal #4 lower of Dong mine, and these possibly occurring in minerals such as arsenide and sulphide. The content of U in Heshan coal is high and is mainly concentrated at the upper and the lower parts of the coal seam and it is associated with mineral assemblages with Ba, Mo, V, Ni, Zn, Rb and Cr. Furthermore, La and Ce are highly correlated with those found in phosphate minerals and Pb, Sc, Ga, Th, Y and Sn to those in aluminosilicate minerals. The enrichment of some elements such as V, Cr, Zn, Mo, Ni, Rb as well as total sulphur and iron in the lower part of most coal seams might be associated with the formation of soil horizon before the accumulation of peat in the basin. Some other elements such as Cl, F, Sr and Ca are locally concentrated in the top of specific coal seams as a result of the leaching from overlying carbonates.

Effect of a pure phase-shifting apodizer on the three-dimensional light intensity distribution in focal region is theoretically investigated in this paper. The results show that the proposed apodizer may induce focus splitting and local minimization of light intensity. By adjusting the geometrical parameters of the phase-shifting apodizer, the focus can split into two or three peaks. And one or two local minimums of light intensity may occur between two intensity peaks. Under the condition of two-peak focus, the distance between the peaks is tunable by the apodizer.

Constant pressure microfiltration of colloidal silica suspensions following coagulation using ferric chloride was investigated under conditions where surface deposition was the predominant cause of fouling. Experimental fluxes were found to be higher than that predicted by conventional cake filtration and blocking laws alone or in combination especially during the initial stages of filtration. Experimental inverse instantaneous fluxes depicted a concave downward behavior when analyzed as a function of volume of water filtered per unit membrane area, which cannot be explained by blocking laws. Further, flux decline under a wide range of pH, Fe3+ dosage, and pressure was accurately simulated by introducing a particle rearrangement term to conventional dead-end cake filtration theory. Equilibrium fluxes predicted by the rearrangement model increased in a straight-line fashion with increasing mean floc size whereas the cake specific resistance decreased as flocs became larger. These results are shown to be consistent with the rearrangement of coagulated aggregates and changes in cake morphology when the pressure increases with cake depth. In contrast, rearrangement effects may not be significant during microfiltration of highly colored waters because natural organic matter can bind particles to each other and to the membrane.

By using the classical nucleation and growth dynamics to describe the melting process of superheated solid materials induced by ultrafast laser pulse irradiation, we found that the melting process of highly superheated solid materials is governed by explosively homogeneous nucleation. For the superheating degree of 1.6–1.9, the melting time for aluminum is several tens of picoseconds. In this case the lattice is heated within a few picoseconds, thus the total melting time of the solid materials is governed by the explosively homogeneous nucleation. However, for the very short laser pulse irradiation, such as femtosecond laser pulses with high fluences, the nonthermal mechanism plays a critical role in the melting process, and the classical homogeneous nucleation theory and growth dynamics is not useful. That is to say, the classical homogeneous nucleation theory and growth dynamics is useful for describing the rapid thermal melting process, however, is not suitable for explaining the nonthermal melting process.

According to the change of refractive index of Sb thin film with temperature and the radial distribution of temperature within the spot, we consider the dynamic optical aperture as a self-focusing thermal lens of Sb thin film in super-resolution near-field structure of SiN/Sb/SiN, and obtain the radius of the dynamic optical aperture (self-focusing thermal lens) 80 nm, the focusing length 22.5 nm, and the diameter of spot through the self-focusing thermal lens 100 nm by setting the Sb thin film thickness 30 nm, laser power 2 mW, and irradiation time on the Sb thin film 1.45 ns. At the same time, the intensity of spot focused by the self-focusing thermal lens of Sb thin films can be greatly enhanced. The working mechanism of Sb thin film in super-resolution near-field structure of SiN/Sb/SiN has been explained.

Adopting mask during proton implantation, we obtain several areas with different proton implantation in a single wafer of GaAs/AlGaAs asymmetrically coupled double quantum wells (ACDQW) grown by MBE, and investigated the characteristics using photoluminescence (PL) and photo-modulated reflectance (PR) spectroscopy. Without rapid thermal annealing, the maximum transition energy shift of 82 meV in a single wafer has been obtained in different areas. The diffusion length of Al is deduced according to spectrum, and compared with that calculated by diffusion coefficient function. It might be very useful for both edge-emitting laser or VCSELs in GaAs-based materials to provide index guiding and better optical design for devices. It is also a good method to set up a library for optimizing the ion implantation processes.

This study focuses on the geochemistry and mineralogy of 23 coal seams from the Shuicheng and Luizhi coal fields from the Late Permian Liupanshui coal mining district, in the west of Guizhou province in southern China. Coal rank ranges widely from high volatile bituminous to low volatile bituminous and anthracite. Major mineral phases present in the Liupanshui coal are kaolinite, quartz, pyrite, and calcite. Traces of other primary minerals are marcasite, gypsum, and dolomite. The Shuicheng coal usually has higher kaolinite and quartz contents than the Luizhi coal. Marcasite occurs indiscriminately in the different coal seams without a clear distribution pattern. The presence of other minerals, such as rutile, anatase, tourmaline, zircon, and phosphates, was also noted. The total sulphur content of Liupanshui coals is higher in the marine-influenced coal seams (up to 7.5% dry), and lower in the nonmarine-influenced coals (as low as 0.3%). In the Luizhi coal field, the coal is characterised by a high sulphur and iron content, whereas in the Shuicheng coal field, contents varied from low to high, depending on the coal seams. An inverse geochemical distribution was detected for the mean contents of Ca–Mn–Ge, with lower contents in the Luizhi coal field. The Liupanshui coals are characterised by relatively high contents of Mn, V, Cu, Li, Zr, Nb, Hf, Ta, Tl, Th, and U, when comparing with the usual concentration ranges in bituminous coals. Trace elements in coals from Liupanshui showed narrow variations in their concentrations among coal seams and coal. Three major trace element affinities (aluminium-silicates, sulphides, and carbonates) accounted for the occurrence and distribution of most of the elements studied were determined.

We have studied the optical properties of surface quantum wells with different width of wells (5 nm and 10 nm) by in-situ photo-modulated reflectance spectroscopy on molecular beam epitaxy (MBE) system. The single surface quantum well (SQW) is confined by the vacuum on one side and by Al 0.3 Ga 0.7 As barrier on the other side. In experiments, we have observed clearly the transitions from the confined hole states to the confined electron states. The transitions between those excited states in 10 nm surface quantum well are observed for the first time. The effects of the surface on the confined states have been well studied by combination of the PR spectra and the effective mass approximation theory.

21 páginas, 6 figuras, 7 tablas., This study summarizes the results of geological, petrographical, geochemical and mineralogical studies performed to determine the geological controls on coal quality of the Fuxin deposit, Liaoning Province, in northeast China. The study is focused on the Haizhou mine, which currently mines a coal-bearing clastic Lower Cretaceous series affected by a diabase intrusion. Three major coal seams are differentiated: the Taiping, the Middle and the Shunjawan. Fuxin coal is a high quality coal with low ash and sulphur contents (4.0 to 18.0% HTA and 0.3 to 0.8%Stot) and high calorific value (5600 to 7500 cal/g, as received basis). Coal impurities (both major and trace elements) are at very low concentrations; only a high Mn concentration (up to 8600 ppm) was detected. The rank of Fuxin coal (mainly high volatile B-bituminous coal) is clearly influenced by the diabase intrusion, which has induced the formation of natural coke from coal. Natural coke surrounds the diabase dykes and sills with a thickness ranging from a few centimetres up to 1.5 m. In addition, a wide aureole made up of high volatile A-bituminous coal formed around the coke. The diabase intrusion was not a major source of elemental mobilization, Mn being the only element clearly enriched in the coal (by 1 to 2 orders of magnitude). However, major changes in major and trace element distribution (affinities) were induced in the coal by the intrusion. The geochemical study revealed that these changes were the consequence of the mobilization of organic-, sulphide- and carbonate-associated elements., The authors would like to express their gratitude to the Spanish Ministry of Foreign Affairs and the Academia Sinica for supporting this study.

We have investigated the photo-modulated reflection spectra of GaAs quantum wells where the top barrier is confined by thin Al 0.3 Ga 0.7 As layers. The optical transitions spectra of the first heavy hole hh1 and the first light hole lh1 states to the first electron sublevel e1 are observed. Due to the increase of the confinement potential in the near-surface quantum well by varying the Al 0.3 Ga 0.7 As top barrier thickness, we observe a significant blue-shift of the transition lines (hh1 to e1 and lh1 to e1) compared to the transition lines of the quantum well with a thick semiconductor barrier. The experimental observation on the energy shift and the variation of the strength ratio between the transitions e1–hh1 and e1–lh1 can be modeled by a rectangular well combined with a vacuum potential and built-in field.