3D Printed Biomimetic PCL Scaffold as Framework Interspersed With Collagen for Long Segment Tracheal Replacement

The rapid development of tissue engineering technology has provided new methods for tracheal replacement. However, none of the previously developed biomimetic tracheas exhibit both the anatomy (separated-ring structure) and mechanical behavior (radial rigidity and longitudinal flexibility) mimicking those of native trachea, which greatly restricts their clinical application. Herein, we proposed a biomimetic scaffold with a separated-ring structure: a polycaprolactone (PCL) scaffold with a ring-hollow alternating structure was three-dimensionally printed as a framework, and collagen sponge was embedded in the hollows amid the PCL rings by pouring followed by lyophilization. The biomimetic scaffold exhibited bionic radial rigidity based on compressive tests and longitudinal flexibility based on three-point bending tests. Furthermore, the biomimetic scaffold was recolonized by chondrocytes and developed tracheal cartilage in vitro. In vivo experiments showed substantial deposition of tracheal cartilage and formation of a biomimetic trachea mimicking the native trachea both structurally and mechanically. Finally, a long-segment tracheal replacement experiment in a rabbit model showed that the engineered biomimetic trachea elicited a satisfactory repair outcome. These results highlight the advantage of a biomimetic trachea with a separated-ring structure that mimics the native trachea both structurally and mechanically and demonstrates its promise in repairing long-segment tracheal defects.

Low retinoic acid levels mediate regionalization of the Sertoli valve in the terminal segment of mouse seminiferous tubules

In mammalian testes, undifferentiated spermatogonia (Aundiff) undergo differentiation in response to retinoic acid (RA), while their progenitor states are partially maintained by fibroblast growth factors (FGFs). Sertoli valve (SV) is a region located at the terminal end of seminiferous tubule (ST) adjacent to the rete testis (RT), where the high density of Aundiff is constitutively maintained with the absence of active spermatogenesis. However, the molecular and cellular characteristics of SV epithelia still remain unclear. In this study, we first identified the region-specific AKT phosphorylation in the SV Sertoli cells and demonstrated non-cell autonomous specialization of Sertoli cells in the SV region by performing a Sertoli cell ablation/replacement experiment. The expression of Fgf9 was detected in the RT epithelia, while the exogenous administration of FGF9 caused ectopic AKT phosphorylation in the Sertoli cells of convoluted ST. Furthermore, we revealed the SV region-specific expression of Cyp26a1, which encodes an RA-degrading enzyme, and demonstrated that the increased RA levels in the SV region disrupt its pool of Aundiff by inducing their differentiation. Taken together, RT-derived FGFs and low levels of RA signaling contribute to the non-cell-autonomous regionalization of the SV epithelia and its local maintenance of Aundiff in the SV region.

Influence of Oil–Pressboard Mass Ratio on the Equilibrium Characteristics of Furfural under Oil Replacement Conditions

The distribution behavior of furfural in insulation systems is influenced by the oil–pressboard mass ratio. In addition, the equilibrium distribution of furfural between oil and pressboard will be disturbed after oil replacement. Therefore, it is of great significance to study the distribution ratio of furfural in oil with various oil–pressboard mass ratios after oil replacement. In this research, an accelerated thermal aging experiment and oil replacement experiment were conducted in the lab. Furthermore, the equilibrium characteristics of furfural dissolved in oil with various oil–pressboard mass ratios were studied. Multiple regression analysis was used to analyze the relationship between the oil–pressboard mass ratios and the distribution ratio of furfural in oil. The equilibrium distribution model of furfural was thus obtained. Afterwards, the modified furfural distribution model under oil replacement conditions was established. A novel scheme is provided for analyzing the equilibrium characteristics of furfural under various oil–pressboard mass ratios after oil replacement. The work of this paper is expected to improve the accuracy of furfural analysis.

Individual variation in the dear enemy phenomenon via territorial vocalizations in red squirrels

Territoriality arises when the benefits of resources exceed the costs of defending them. The dear enemy phenomenon, where familiar territorial neighbours refrain from intruding on one another and mutually reduce their defensive efforts, allows for reduction of these costs but requires discrimination between conspecifics. We hypothesized that territorial vocalizations in red squirrels (Tamiasciurus hudsonicus) are used for this discrimination. We performed a speaker replacement experiment where red squirrels (n = 41) were temporarily removed from their territories and replaced with a speaker broadcasting their own call, an unfamiliar call, or silence. Contrary to our prediction, there were no differences in overall intrusion risk among our three playbacks, but the identity of intruders did vary. Existing variation in familiarity within territorial neighbourhoods should be considered, rather than the binary classification of familiar or stranger, when studying dear enemy effects. We also discuss the variable importance of silence in acoustic territorial populations.

Individual variation in the dear enemy phenomenon via territorial vocalizations in red squirrels

Territoriality arises when the benefits of resources exceed the costs of defending them. The dear enemy phenomenon, where familiar territorial neighbours refrain from intruding on one another and mutually reduce their defensive efforts, allows for reduction of these costs but requires discrimination between conspecifics. We hypothesized that territorial vocalizations in red squirrels (Tamiasciurus hudsonicus) are used for this discrimination. We performed a speaker replacement experiment where red squirrels () were temporarily removed from their territories and replaced with a speaker broadcasting their own call, an unfamiliar call, or silence. Contrary to our prediction, there were no differences in overall intrusion risk among our three playbacks, but the identity of intruders did vary. Existing variation in familiarity within territorial neighbourhoods should be considered, rather than the binary classification of familiar or stranger, when studying dear enemy effects. We also discuss the variable importance of silence in acoustic territorial populations.

Competitive Ability of Capsicum annuum L. Relative to the Weed Amaranthus lividus L.

Amaranthus lividusis the most frequently reported troublesome weed in the production ofCapsicum annuumin some regions because it is an aggressive invader, difficult to control, and reduces yield significantly. The effects ofA.lividuson the growth ofC.annuum‘Baklouti’ were evaluated under greenhouse conditions. Three experiments were conducted to determine the effect ofA.lividuson the biomass accumulation ofC.annuumseedlings for 40 days. In an additive experiment, to oneC.annuumseedling and 1, 2, 3 or 4A.lividusseedlings were grown per pot. The second experiment was established to assessC. annuumintracompetition using from one to six plants per pot as the density. In a replacement experiment,C.annuumandA.lividusseedlings were transplanted into pots with different proportions of both plants (1/5, 2/4, 3/3, 4/2, 5/1). Competition byA.lividusreducedC.annuumplant dry weight by as much as 93%. However,C.annuumhad little effect onA.lividus, reducing dry weight by 31.3% at a 5:1 ratio ofC.annuum:A.lividus. Relative yield analysis betweenC. annuumandA. lividusdemonstrated the competitive advantage ofC. annuumoverA. lividus.The relative crowding coefficient of both plants changed significantly in the presence of the other plant, at any ratio. The aggressivity ofC.annuumwas higher at its lower proportion andC.annuumwas more aggressive towards itself than towardsA.lividuswhen its density increased.

A Review on Experimental Research on Natural Gas Production From the Hydrate With CO2

In this paper, the experimental researches on replacement of CH4 in the hydrate by use of CO2 reported by researchers both at home and abroad are summarized and analyzed, and the advantages and disadvantages of this method on natural gas production from hydrate is discussed. The latest progresses of CH4 replacement experiment with gaseous CO2, liquid CO2 and CO2 emulsion are present, and the superiority of CO2 emulsion on replacement of CH4 is emphasized. Moreover, the latest experimental research on preparation of CO2 emulsion is introduced, and the key technologies on the replacement of CH4 hydrate with different states of CO2 are indicated.