Materials with a temperature‐controlled reversible electrical transition between insulator and conductor are attracting huge attention due to their promising applications in many fields. However, most of them are intrinsically rigid and require complicated fabrication processes. Here, a highly stretchable (680% strain) liquid metal polymer composite as a reversible transitional insulator and conductor (TIC), which is accompanied with huge resistivity changes (more than 4 × 109 times) reversibly through a tuning temperature in a few seconds is introduced. When frozen, the insulated TIC becomes conductive and recovers after warming. Both the phase change of the liquid metal droplets and the rigidity change of the polymer contribute directly to transition between insulator and conductor. A simplified model is established to predict the expansion and connection of liquid metal droplets. Along with high stretchability, straightforward fabrication methods, rapid triggering time, large switching ratio, good repeatability, the TIC offers tremendous possibilities for numerous applications, like stretchable switches, semiconductors, temperature sensors, and resistive random‐access memory. Accordingly, a system that can display numbers and letters via converting alternative TIC temperature to a binary signal on a computer is conceived and demonstrated. The present discovery suggests a general strategy for fabricating and stimulating a stretchable transitional insulator and conductor based on liquid metal and allied polymers.

Liquid metals (LMs) in an alkaline electrolyte, when placed on a graphite surface, are able to be manipulated into desired flat, stable shapes with sharp angles, like triangles. Unique transformations and worm-like anti-gravity upslope LM locomotion under a low-voltage electric field are also revealed.

In the present study, a magnetic liquid metal droplet (MLMD), which can be stretched in large scales both horizontally and vertically in the free space, is introduced. This MLMD is fabricated based on a multimaterial system including liquid metals, iron particles, and electrolytes. Such remarkable stretching capacity is reversible, longlasting, and can be repeated for multiple times. The seemingly contrary properties, the good stretchability and the mechanic strength for threedimensional (3D) stretch, should owe to the surface oxide over the MLMD. On the basis of the 3D stretching ability of the MLMD, an intelligent scalable conductor was achieved, which can make electrical connections at various directions in the 3D free space. Moreover, the vertically stretched MLMD can move horizontally with its half body in the solution and the other half in the air, which resembles the nature of an upright walking amphibian. All the behaviors can be precisely, conveniently, and contactlessly controlled by the magnetic field provided by permanent magnets. With all the appealing properties, this MLMD presents a fundamental and promising platform for the liquid metals to further develop the multifreedom actuation in free space and eventually lead to the dynamically reconfigurable intelligent and biomimetic soft robots in the future.

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Magnetic fields enable dexterous, precise, and real‐time control of ferromagnetic materials. However, most materials, including glasses, organics, and metals, are nonmagnetic and often do not respond to a magnetic field. Here, a transitional ferrofluid (TF) made by embedding magnetic iron particles into pure gallium through the treatment of highly concentrated HCl solutions, as well as its switchable interlocking force to objects during the phase change, is introduced to achieve magnetic manipulation of non‐magnetic objects. A gripper made by liquid TF enables intimate contact with arbitrarily shaped objects and then generates a strong interlocking force of as high as 1168 N (using only 10 g TF) upon solidification at room temperature, which can be reversibly eliminated (F < 0.01 N) through melting. Owing to electrical conductivity and magnetism, a solid TF can be melted through electromagnetic induction heating. By coupling the switchable physical force during the phase transition and magnetism of TF, embedded non‐magnetic objects can be manipulated using an applied magnetic field and become impervious to magnetic stimuli again after heating and releasing the TF. This study is expected to inspire numerous potential applications in the reversible magnetic actuation of soft robotics, remote operation systems, drug delivery, and liquid grippers.

This research developed an innovative approach to reveal nitrogen sources, transformation, and transport in large and complex river networks in the Taihu Lake basin using measurement of dual stable isotopes of nitrate. The spatial patterns of δN corresponded to the urbanization level, and the nitrogen cycle was associated with the hydrological regime at the basin level. During the high flow season of summer, nonpoint sources from fertilizer/soils and atmospheric deposition constituted the highest proportion of the total nitrogen load. The point sources from sewage/manure, with high ammonium concentrations and high δN and δO contents in the form of nitrate, accounted for the largest inputs among all sources during the low flow season of winter. Hot spot areas with heavy point source pollution were identified, and the pollutant transport routes were revealed. Nitrification occurred widely during the warm seasons, with decreased δO values; whereas great potential for denitrification existed during the low flow seasons of autumn and spring. The study showed that point source reduction could have effects over the short-term; however, long-term efforts to substantially control agriculture nonpoint sources are essential to eutrophication alleviation for the receiving lake, which clarifies the relationship between point and nonpoint source control.

Liquid Gripper In article number 2100274, Liang Hu, Yen Wei, Jing Liu, and co‐workers present a magnetic liquid gripper based on a metallic ferrofluid that enables intimate contact with arbitrarily shaped objects and then generates a strong adhesion force upon solidification, which can be reversibly eliminated by moderate melting. Through coupling the magnetism of metallic ferrofluid and switchable adhesion force to objects, any non‐magnetic targets can be manipulated via an applied magnetic field.

The unique motion of amoeba with a deformable body has long been an intriguing issue in scientific fields ranging from physics, bionics to mechanics. So far, most of the currently available artificial machines are still hard to achieve the complicated amoeba-like behaviors including stretching pseudopodia. Here through introducing a multi-materials system, we discovered a group of very unusual biomimetic amoeba-like behaviors of self-fueled liquid gallium alloy on the graphite surface immersed in alkaline solution. The underlying mechanisms were discovered to be the surface tension variations across the liquid metal droplet through its simultaneous electrochemical interactions with aluminum and graphite in the NaOH electrolyte. This finding would shed light on the packing and the structural design of future soft robots owning diverse deformation capability. Moreover, this study related the physical transformation of a non-living LM droplet to the life behavior of amoeba in nature, which is inspiring in human’s pursuit of advanced biomimetic machine.