Shallow Surface Research Articles

Nocturnal Boundary Layer Evolution and Its Impacts on the Vertical Distributions of Pollutant Particulate Matter

To investigate the evolution of the nocturnal boundary layer (NBL) and its impacts on the vertical distributions of pollutant particulates, a combination of in situ observations from a large tethered balloon, remote sensing instruments (aerosol lidar and Doppler wind lidar) and an atmospheric environment-monitoring vehicle were utilized. The observation site was approximately 100 km southwest of Beijing, the capital of China. Results show that a considerable proportion of pollutant particulates were still suspended in the residual layer (RL) (e.g., the nitrate concentration reached 30 μg m−3) after sunset. The NBL height calculated by the aerosol lidar was closer to the top of the RL before midnight because of the pollutants stored aloft in the RL and the shallow surface inversion layer; after midnight, the NBL height was more consistent with the top of the surface inversion layer. As the convective mixing layer gradually became established after sunrise the following day, the pollutants stored in the nocturnal RL of the preceding night were entrained downward into the mixing layer. The early morning PM2.5 concentration near 700 m in the RL on 20 December decreased by 83% compared with the concentration at 13:34 on 20 December at the same height. The nitrate concentration also decreased significantly in the RL, and the mixing down of nitrate from the RL could contribute about 37% to the nitrate in the mixing layer. Turbulence activities still existed in the RL with the bulk Richardson number (Rb) below the threshold value. The corresponding increase in PM2.5 was likely to be correlated with the weak turbulence in the RL in the early morning.

Evaluation of Subsurface Drip Irrigation Designs in a Soil Profile with a Capillary Barrier

Enhanced water use efficiency (WUE) is the key to sustainable agriculture in arid regions. The installation of capillary barriers (CB) has been suggested as one of the potential solutions. CB effects are observed between two soil layers with distinctly different soil hydraulic properties. A CB helps retain water in the upper, relatively fine-textured soil layer, suppressing water losses by deep drainage. However, retaining water in a shallow surface layer also intensifies water loss by evaporation. The use of subsurface drip irrigation (SDI) with a CB may prevent such water loss. This study evaluated the performance of SDI in a soil profile with a CB using a pot experiment and numerical analysis with the HYDRUS (2D/3D) software package. The ring-shaped emitter was selected for the SDI system for its low capital expenditures (CapEx) and maintenance. Strawberry was selected as a model plant. The results indicated that the proposed SDI system with a CB was effective in terms of WUE. The numerical analysis revealed that the CB’s depth influences the system’s water balance more than the ring-shaped emitter’s installation depth. While the CB’s shallow installation led to more root water uptake by the strawberry and less water loss by deep drainage, it induced more water loss by evaporation.

Landscape evolution of the granitic Criffel–Dalbeattie hills, south-west Scotland

ABSTRACT This paper examines the geomorphological evolution of the Criffel–Dalbeattie granitic pluton (CDGP). Research is based on data from Shuttle Radar Topography Mission, Google Earth, Ordnance Survey maps and field measurements. Granitic emplacement into Southern Uplands terrain along Caledonian structural trends took place during the mid-late Devonian. Faulting and subsidence during the late Palaeozoic and Mesozoic preceded assumed differential uplift of the pluton during the early Palaeocene. This led to the development of bidirectional palaeo-surfaces. Structural rather than lithological controls formed the dominant bases for subsequent weathering during the Palaeogene and Neogene. Shallow surface weathering over the CDGP and absence of saprolite imply that weathering episodes may have been relatively short-lived. However, joint enlargement and in situ eroded corestones indicate that earlier weathered features were substantially modified by glacial agencies. Pleistocene glacial events included ice streaming from the NNW which took place over moulded hills. Thinner late-stage ice scoured irregular hill long profiles while divergent ice contributed to basin erosion. Localised resurgent ice streaming was shortlived. After early uplift and palaeo-surface formation, the CDGP hills evolved through phases of granitic weathering and glacial erosion likely over the past 65 Ma since the early Palaeocene.

Vapor–liquid–solid growth of silicon nanowires from surface nanoholes formed with metal-assisted chemical etching

The influence of shallow surface nanoholes on the growth direction of silicon nanowires (SiNWs) with the vapor–liquid–solid (VLS) process was studied in order to realize a single-step way to promote integration of high-density SiNWs along a specific direction. Shallow surface nanoholes were formed by the short-time metal-assisted chemical etching (MACE) process with catalytic Au nanoparticles of 60 nm also used for the VLS process, in order to shape nanoholes with a similar diameter to the nanoparticles. With an increase in MACE processing time to 5 min, the ratio of perpendicularly grown SiNWs to the SiNWs that appeared on the (111) silicon surface significantly increased in the initial growth phase, reaching higher than 80%. This ratio was more than 3 times higher than without the MACE process. On the other hand, the excess processing time brought about a decrease of the SiNWs detected. This result indicated that the formation of surface nanoholes with an appropriate depth could be an effective way of controlling SiNW growth direction.

Flow-sediment regulation regime influencing mobilization of trace metals in shallow aquifer and surface water in the Yellow River Delta, China

The Yellow River Delta (YRD) is a typical case of frequent interaction between surface water and groundwater under the seasonal flow-sediment regulation regime. A total of 40 samples (20 surface water samples, 19 groundwater samples, and 1 seawater sample), were collected during the high flow (October, 2019). Trace metals, hydrochemical indicators (EC, pH, major ion of Na+, K+, Mg2+, Ca2+, Cl−, SO4 2−, and HCO3 −) and stable isotopes (δ18O and δD) were determined. The impact of water diversion on the hydrochemistry of groundwater was significant, accounting up to a 90% of river discharge in some sites calculated by 2-component mixing model. Factor analysis indicated that Fe, Mn, Al, and B in surface water were closely correlated and were present in the dissolution phase due to sediment remobilization controlled by flow-sediment regulation; Sr was influenced by the dissolution of evaporate salt, while Ba suffered precipitation in the oxidation processes. However, the source of Sr, Mn, B, and Fe in groundwater was accompanied by hydrochemical compositions and per cent surface water, implying that the trace metals in surface water contributed to that of accumulation in the shallow aquifer; Al was influenced by plagioclase weathering, while Ba precipitated too.

Landslide geometry and activity in Villa de la Independencia (Bolivia) revealed by InSAR and seismic noise measurements

Interferometric Synthetic Aperture Radar (InSAR) enables detailed investigation of surface landslide movements, but it cannot provide information about subsurface structures. In this work, InSAR measurements were integrated with seismic noise in situ measurements to analyse both the surface and subsurface characteristics of a complex slow-moving landslide exhibiting multiple failure surfaces. The landslide body involves a town of around 6000 inhabitants, Villa de la Independencia (Bolivia), where extensive damages to buildings have been observed. To investigate the spatial-temporal characteristics of the landslide motion, Sentinel-1 displacement time series from October 2014 to December 2019 were produced. A new geometric inversion method is proposed to determine the best-fit sliding direction and inclination of the landslide. Our results indicate that the landslide is featured by a compound movement where three different blocks slide. This is further evidenced by seismic noise measurements which identified that the different dynamic characteristics of the three sub-blocks were possibly due to the different properties of shallow and deep slip surfaces. Determination of the slip surface depths allows for estimating the overall landslide volume (9.18 · 107 m3). Furthermore, Sentinel-1 time series show that the landslide movements manifest substantial accelerations in early 2018 and 2019, coinciding with increased precipitations in the late rainy season which are identified as the most likely triggers of the observed accelerations. This study showcases the potential of integrating InSAR and seismic noise techniques to understand the landslide mechanism from ground to subsurface.

Spatial coherence of hybrid surface plasmon-phonon-polaritons in shallow n-GaN surface-relief gratings.

Dispersion characteristics of hybrid surface plasmon-phonon-polaritons (SPPhPs) on the air/polar semiconductor interface were investigated by means of shallow surface relief grating using emission spectroscopy methods. A set of grating structures with optimal 1 µm depth and periods from 8 to 22 µm was developed on a heavily-doped GaN crystal. The SPPhPs were excited by thermal heating or electrical biasing of the samples which radiated directive polarized features in an extremely narrowband spectrum range. Detailed analysis of damping factors and propagation losses revealed maximum values of quality factor and spatial coherence of hybrid SPPhPs modes. Highest quality factor was found to be practically independent on the period of the shallow grating, as it was always detected near the frequency of transverse optical phonon, demonstrating values as high as 88 and 200 in experiment and theory, respectively. Meanwhile, the largest values of coherence length strongly depended on the grating as the propagation losses of hybrid SPPhP modes showed a tendency to accumulate with the wavevector increase. The sample with 22 µm grating period demonstrated the highest coherence of hybrid polaritons with the experimental (theoretical) coherence length values as high as 1.6 mm (2.3 mm).

A Case Study of Cache Pit Construction, Use, and Abandonment from the Upper Great Lakes, USA

ABSTRACT Archaeological investigations on sandy, well-drained terraces of the Grand River in southwestern Michigan revealed a large number of shallow surface depressions, marking the locations of former cache pits, i.e., subterranean storage features. Our paper documents these pits, one of the largest arrays of cache pits reported for the Upper Great Lakes. Excavations into 29 cache pits revealed that they had been backfilled with generally artifact-poor sands. Prior to backfilling, the cache pits had been burned, leaving behind a black, charcoal-rich, charred horizon at their base, below the fill. This type of intentional burning has not previously been reported. Intentional re-use of cache pits was rare, if it occurred at all. Subsequently, pedogenesis has formed tongue-like soil horizons below the surface depressions. Radiocarbon dates from the cache pits, along with diagnostic artifacts, place the use of these features to the Late Precontact period, particularly the mid- to late 15th century a.d.

The Effect of Stress Distribution Around The Decline Shaft on The Support System Stability in Underground Mining

The decline shaft is one of the main facilities in an underground mining work that is used as access to the mining panel from the surface. Making decline shafts on materials with weak characteristics is one of the important geotechnical issues that must be considered. The initial stage of making decline shaft holes is carried out on a relatively shallow ground surface or soil depth so that the horizontal stress that works is greater than the vertical stress. This excavation process will change the direction and magnitude of the initial stress from being in an equilibrium state to being disturbed. In addition to the stress on the rock mass, the condition of weak soil strength will affect the behavior and distribution of stresses working around the decline shaft hole. If the stress around the decline shaft exceeds the strength of the rock, there will be instability in the decline shaft so that strength is needed to control the existing stress.

Testing the performance of a solar energy cooling system in Baghdad city

Renewable energy resources have become a promissory alternative to overcome the problems related to atmospheric pollution and limited sources of fossil fuel energy. The technologies in the field of renewable energy are used also to improve the ventilation and cooling in buildings by using the solar chimney and heat exchanger. This study addresses the design, construction and testing of a cooling system by using the above two techniques. The aim was to study the effects of weather conditions on the efficiency of this system which was installed in Baghdad for April and May 2020. The common weather in these months is hot in Baghdad. The test room of the design which has a size of 1 m3 was situated to face the geographical south. The test room is thermally insulated and connected to a solar chimney which generates a convection current to draw the air out of the room through a heat exchanger. The heat exchanger was submerged in a water tank of 2 m length, 1 m width and 1 m height. It was also covered with a layer of soil mixture with a thickness of 10 cm. The experiment simulates the natural conditions of a shallow water surface, connected to the room from the other side. The study results revealed that the air temperature inside the test room was lower than that of the ambient air outside. Pearson correlation coefficient showed that there was a strong direct relationship between solar radiation, temperature and wind speed from one side and the cooling efficiency from the other side. Also, there was a negative correlation between relative humidity and cooling efficiency.

High-resolution crustal velocity structure in the Shanxi rift zone and its tectonic implications

The Shanxi rift zone, located in the Trans-North China Orogen (TNCO) of the North China Craton (NCC), is wellknown for hosting large intraplate earthquakes in continental China. The TNCO is a suture zone formed by the amalgamation of the eastern and the western blocks of the NCC. After its formation, it was reactived and deformed by later tectonic activities, which result in complex lithospheric heterogeneities. Thus, the detailed crustal structure of the Shanxi rift zone is critical for understanding the tectonics and seismogenic mechanism in this area, which will shed new lights on the formation and dynamic evolution of the NCC. In this study, we applied ambient noise tomography based on 18 months continuous records from 108 seismic stations located in Shanxi and its surroundings, in order to constrain its detailed crustal structure. We measured 4437 Rayleigh wave phase velocity dispersion curves in the period of 5–45 s from the cross-correlation functions. Next, a surface wave direct inversion algorithm based on surface-wave ray tracing was used to resolve a 3-D S-wave velocity model in the upper 60 km with lateral resolution of ∼50–80 km. The tomographic images show that the sedimentary thickness of the Taiyuan Basin is less than 5 km. At depth of 0–10 km, we observe a good correlation between the imaged structural variations with geological and topographic features at the surface. For example, the center of rift shows low-velocity anomalies and the uplifting areas on both sides are characterized by high velocity anomalies. The western and eastern boundaries of the slow materials coincide with the faults that control the basin. The slow material extends from the shallow surface to depth of about 15 km but it getting smaller in shape at deeper depth. For the Taiyuan Basin, Linfen Basin, and Yuncheng Basin in the central and southern parts, the structure is dominant by slow materials in the upper crust but changes to strong high-velocity anomalies in the lower crust and the uppermost mantle at depth deeper than 25 km. We interprete these high-velocity anomalies to be associated with the cold remnant of the underplated basalt in the lower crust that were formed in early Tertiary before the basin was stretched. We also observe the low-velocity anomaly beneath the Datong volcanic area, which extends from the uppermost mantle to a depth of 20 km vertically and migrates from west to east laterally. It may reflect the upwelling channel of the magmatic material in Datong. Moreover, the strong low-velocity anomalies presented north of 38°N could be related to the heated crustal materials with paritial melting as a result of the intensive magmatic activities of the Datong Volcano since the Cenozoic. In our study region, seismicity mainly concentrates in the depth range of 5–20 km and we find that most earthquakes appear to occur in places where velocity changes from high to low rapidly, with slight higher concentration in the faster material areas. In summary, our high-resolution 3-D crustal velocity model provides important seismological constraints to understand the tectonic evolution and seismicity across the Shanxi rift zone.

Wave-slope soaring of the brown pelican

BackgroundFrom the laboratory at Scripps Institution of Oceanography, it is common to see the brown pelican (Pelecanus occidentalis) traveling along the crests of ocean waves just offshore of the surf-zone. When flying in this manner, the birds can travel long distances without flapping, centimeters above the ocean’s surface. Here we derive a theoretical framework for assessing the energetic savings related to this behavior, ‘wave-slope soaring,’ in which an organism in flight takes advantage of localized updrafts caused by traveling ocean surface gravity waves.MethodsThe energy cost of steady, constant altitude flight in and out of ground effect are analyzed as controls. Potential flow theory is used to quantify the ocean wave-induced wind associated with near-shoaling, weakly nonlinear, shallow water ocean surface gravity waves moving through an atmosphere initially at rest. Using perturbation theory and the Green’s function for Laplace’s equation in 2D with Dirichlet boundary conditions, we obtain integrals for the horizontal and vertical components of the wave-induced wind in a frame of reference moving with the wave. Wave-slope soaring flight is then analyzed using an energetics-based approach for waves under a range of ocean conditions and the body plan of P. occidentalis.ResultsFor ground effect flight, we calculate a ∼15 - 25% reduction in cost of transport as compared with steady, level flight out of ground effect. When wave-slope soaring is employed at flight heights ∼2m in typical ocean conditions (2m wave height, 15s period), we calculate 60-70% reduction in cost of transport as compared with flight in ground effect. A relatively small increase in swell amplitude or decrease in flight height allows up to 100% of the cost of transport to be offset by wave-slope soaring behavior.ConclusionsThe theoretical development presented here suggests there are energy savings associated with wave-slope soaring. Individual brown pelicans may significantly decrease their cost of transport utilizing this mode of flight under typical ocean conditions. Thus wave-slope soaring may provide fitness benefit to these highly mobile organisms that depend on patchy prey distribution over large home ranges.

Causes and treatment measures for deformation of retaining soil and slope

To explore reasons for deformation of retaining soil and slope in the Maternal-Child Health Care Hospital of Hanyuan County, the meteorology, geological lithology, geological structure, and hydrological conditions were surveyed. Moreover, types and distributions of weak intercalated layers were found out by drilling, and physical and mechanical properties were obtained through physical mechanics and field shear test. Meanwhile, by means of drilling and monitoring, deformation range and characteristics of retaining soil and slope were determined, and deformation mechanism was obtained through monitoring crack opening and deep displacement. The structures showed that deformation occurred at new 2# counterweight retaining wall is caused by shallow slip control surface RJ0; the pulling and crack of settlement joints between the new 2# counterweight retaining wall and the new 1# slab-pile wall are caused by the deformation of shallow slip control surface RJ0; the deformation and failure of new 2# counterweight retaining wall and new 1# slab-pile wall and their foundation rock mass at the lower part are caused by creep displacement of “shallow weak intercalated layers” RJ0 and RJ1; in addition, the deep creep control surface RJ2 has certain influence on the deformation of upper building and its foundation rock mass. Therefore, anti-slide piles should be used to control the shallow slipping control surface RJ1, with the depth reaching the structural plane where the deep creep control surface RJ2 is located.

On the Diversity of Phyllodocida (Annelida: Errantia), with a Focus on Glyceridae, Goniadidae, Nephtyidae, Polynoidae, Sphaerodoridae, Syllidae, and the Holoplanktonic Families

Phyllodocida is a clade of errantiate annelids characterized by having ventral sensory palps, anterior enlarged cirri, axial muscular proboscis, compound chaetae (if present) with a single ligament, and of lacking dorsolateral folds. Members of most families date back to the Carboniferous, although the earliest fossil was dated from the Devonian. Phyllodocida holds 27 well-established and morphologically homogenous clades ranked as families, gathering more than 4600 currently accepted nominal species. Among them, Syllidae and Polynoidae are the most specious polychaete groups. Species of Phyllodocida are mainly found in the marine benthos, although a few inhabit freshwater, terrestrial and planktonic environments, and occur from intertidal to deep waters in all oceans. In this review, we (1) explore the current knowledge on species diversity trends (based on traditional species concept and molecular data), phylogeny, ecology, and geographic distribution for the whole group, (2) try to identify the main knowledge gaps, and (3) focus on selected families: Alciopidae, Goniadidae, Glyceridae, Iospilidae, Lopadorrhynchidae, Polynoidae, Pontodoridae, Nephtyidae, Sphaerodoridae, Syllidae, Tomopteridae, Typhloscolecidae, and Yndolaciidae. The highest species richness is concentrated in European, North American, and Australian continental shelves (reflecting a strong sampling bias). While most data come from shallow coastal and surface environments most world oceans are clearly under-studied. The overall trends indicate that new descriptions are constantly added through time and that less than 10% of the known species have molecular barcode information available.

High-Resolution SMAP-Derived Root-Zone Soil Moisture Using an Exponential Filter Model Calibrated per Land Cover Type

Root-zone soil moisture (RZSM) plays a key role for most water and energy budgets, as it is particularly relevant in controlling plant transpiration and hydraulic redistribution. RZSM data is needed for a variety of different applications, such as forecasting crop yields, improving flood predictions and monitoring agricultural drought, among others. Remote sensing provides surface soil moisture (SSM) retrievals, whose key advantage is the large spatial coverage on a systematic basis. This study tests a simple method to retrieve RZSM estimates from high-resolution SSM derived from SMAP (Soil Moisture Active Passive). A recursive exponential filter using a time constant τ is calibrated per land cover type, which uses as an intermediate step a long-term ISBA-DIF (Interaction Soil Biosphere Atmosphere—Diffusion scheme) dataset over an area located in Catalonia, NE of Spain. The τ values thus obtained are then used as an input to the same recursive exponential filter, to derive 1 km resolution RZSM estimates from 1 km SMAP SSM, which are obtained from the original data by downscaling to a 1 km resolution, through the DISPATCH (DISaggregation based on a Physical and Theoretical scale CHange) methodology. The results are then validated with scaled in situ observations at different depths, over two different areas, one representative of rainfed crops, and the other of irrigated crops. In general, the estimates agree well with the observations over the rainfed crops, especially at a 10 cm and 25 cm depth. Nash–Sutcliffe (NS) scores ranging between 0.33 and 0.58, and between 0.37 and 0.56 have been found, respectively. Correlation coefficients for these depths are high, between 0.76 and 0.91 (10 cm), and between 0.71 and 0.90 (25 cm). For the irrigated sites, results are poorer (partly due to the extremely high heterogeneity present), with NS scores ranging between −2.57 and 0.16, and correlations ranging between −0.56 and 0.48 at 25 cm. Given the strong correlations and NS scores found in the surface, the sensitivity of the filter to different τ values was investigated. For the rainfed site, it was found, as expected, with increasing τ, increasing NS and correlations with the deeper layers, suggesting a better coupling. Nevertheless, a strong correlation with the surface (5 cm) or shallower depths (10 cm) observed over certain sites indicates a certain lack of skill of the filter to represent processes which occur at lower levels in the SM column. All in all, a calibration accounting for the vegetation was shown to be an adequate methodology in applying the recursive exponential filter to derive the RZSM estimates over large areas. Nevertheless, the relative shallow surface at which the estimates correlate in some cases seem to indicate that an effect of evapotranspiration in the profile is not well captured by the filter.

Natural binocular depth discrimination behavior in mice explained by visual cortical activity

In mice and other mammals, forebrain neurons integrate right and left eye information to generate a three-dimensional representation of the visual environment. Neurons in the visual cortex of mice are sensitive to binocular disparity,1-3 yet it is unclear whether that sensitivity is linked to the perception of depth.4-8 We developed a natural task based on the classic visual cliff and pole descent tasks to estimate the psychophysical range of mouse depth discrimination.5,9 Mice with binocular vision descended to a near (shallow) surface more often when surrounding far (deep) surfaces were progressively more distant. Occlusion of one eye severely impaired their ability to target the near surface. We quantified the distance at which animals make their decisions to estimate the binocular image displacement of the checkerboard pattern on the near and far surfaces. Then, we assayed the disparity sensitivity of large populations of binocular neurons in primary visual cortex (V1) using two-photon microscopy2 and quantitatively compared this information available in V1 to their behavioral sensitivity. Disparity information in V1 matches the behavioral performance over the range of depths examined and was resistant to changes in binocular alignment. These findings reveal that mice naturally use stereoscopic cues to guide their behavior and indicate a neural basis for this depth discrimination task.

Tracking and Assessing Oil Spill Toxicity to Aquatic Organisms: A Novel Approach.

An in situ exposure and effects bioassay system was developed for assessing the toxicity of oil spills to aquatic organisms. The assessment tool combines components of 2 previously developed systems, the sediment ecotoxicity assessment ring (SEA Ring) and the drifting particle simulator. The integrated drifting exposure and effects assessment ring (DEEAR) is comprised of a Global Positioning System (GPS) float, a drifter drogue, the SEA Ring, and the Cyclops-7 fluorescent sensor. Polyethylene passive sampling devices (PED) were mounted for an additional means to characterize water quality conditions and exposures. The DEEAR is optimized for evaluating oil exposure and toxicity in the shallow surface mixing layer of marine waters. A short-term preliminary test was conducted in San Diego, California, USA, to verify the operation of the GPS tracking, the iridium communications, and the integrated SEA Ring exposure system. Further, a proof-of-concept demonstration was conducted offshore in the Santa Barbara Channel, where natural oil seeps produce surface slicks and sheens. Two DEEAR units were deployed for 24 h-one within the oil slick and one in an area outside observable slicks. An aerial drone provided tracking of the surface oil and optimal sites for deployment. The DEEAR proof-of-concept demonstrated integrated real-time tracking and characterization of oil exposures by grab samples, PED, and fluorescent sensors. Oil exposures were directly linked to toxic responses in fish and mysids. This novel integrated system shows promise for use in a variety of aquatic sites to more accurately determine in situ oil exposure and toxicity. Environ Toxicol Chem 2021;40:1452-1462. © 2021 SETAC.

Evaluation of the surface dose for total body irradiation (TBI) technique with parallel-opposed anterior posterior geometry

AbstractAim:Total body irradiation (TBI) is an external radiotherapy technique in which the whole body including the superficial regions is required to receive the therapeutic dose. The purpose of this study is to evaluate the received surface dose during TBI technique.Methods and materials:The anterior/posterior (AP/PA) TBI was implemented with 18-MV photon beam at 312-cm treatment distance for human-like phantom. The GAFCHROMIC-EBT3 films were used for superficial dose measurements.Results and discussion:The percentage of surface-absorbed dose relative to the prescription point for 8 points of measurements was between 102·78–121·48% and 104·51–127·43% at 5 and 10 mm depth, respectively. In the chest wall region due to the presence of lung blocks, the absorbed dose was below the acceptable level, so an electron boost was required to increase the chest wall absorbed dose.Conclusions:According to the results, the implemented technique was able to deliver sufficient dose to the shallow surface of phantom’s body.

Recent developments in engineering protein-protein interactions using phage display.

Targeted inhibition of misregulated protein-protein interactions (PPIs) has been a promising area of investigation in drug discovery and development for human diseases. However, many constraints remain, including shallow binding surfaces and dynamic conformation changes upon interaction. A particularly challenging aspect is the undesirable off-target effects caused by inherent structural similarity among the protein families. To tackle this problem, phage display has been used to engineer PPIs for high-specificity binders with improved binding affinity and greatly reduced undesirable interactions with closely related proteins. Although general steps of phage display are standardized, library design is highly variable depending on experimental contexts. Here in this review, we examined recent advances in the structure-based combinatorial library design and the advantages and limitations of different approaches. The strategies described here can be explored for other protein-protein interactions and aid in designing new libraries or improving on previous libraries.

Shear properties and pore structure characteristics of soil–rock mixture under freeze–thaw cycles

Soil–rock mixtures (S-RMs) are widely distributed in the shallow surfaces of cold regions that experience frequent freeze–thaw cycles, considerably threatening the stability of the soil–rock slopes on both sides of the road. We examine the S-RM shear strength and deformation characteristics under different freeze–thaw cycles through experiment and simulation. Nuclear magnetic resonance (NMR) was used to analyze the influence of freeze–thaw cycles on the internal pore structure of S-RM and establish the internal relationship between pore structure and shear characteristics under freeze–thaw cycles. Results show that the shear strength parameters of S-RM first decrease, then increase, and finally decrease as the number of freeze–thaw cycles increases; besides, the vertical expansion range of cracks gradually increases during shearing with the number of cycles. Porosity first increases, then decreases, and increases again with the number of freeze–thaw cycles. NMR results showed that S-RM pores had fractal characteristics. According to the fractal dimension, the soil particles inside the sample formed larger aggregates after the first freeze–thaw cycle. After the second–third freeze–thaw cycles, the agglomerated soil particles gradually disintegrate and tend to homogenize. The soil particles cover the surface of the gravel under the skeleton deformation to form an inclusion structure. The subsequent increase in the number of freeze–thaw cycles causes the soil particles attached to the gravels to gradually peel off.