Velocimetry of GHz elastic surface waves in quartz and fused silica based on full-field imaging of pump-probe reflectometry.

This study reports an imaging method for gigahertz surface acoustic waves in transparent layers using infrared subpicosecond laser pulses in the ablation regime and an optical pump-probe technique. The reflectivity modulations due to the photoelastic effect of generated multimodal surface acoustic waves were imaged by an sCMOS camera illuminated by the time-delayed, frequency-doubled probe pulses. Moving the delay time between 6 . 0 n s to 11 . 5 n s , image stacks of wave field propagation were created. Two representative samples were investigated: wafers of isotropic fused silica and anisotropic x-cut quartz. Rayleigh (SAW) and longitudinal dominant high-velocity pseudo-surface acoustic wave (HVPSAW) modes could be observed and tracked along a circular grid around the excitation center, allowing the extraction of angular profiles of the propagation velocity. In quartz, the folding of a PSAW was observed. A finite element simulation was developed to predict the measurement results. The simulation and measurement were in good agreement with a relative error of 2 % to 5 %. These results show the potential for fast and full-field imaging of laser-generated ultrasonic surface wave modes, which can be utilized for the characterization of thin transparent samples such as semiconductor wafers or optical crystals in the gigahertz frequency range.

Comparison of methods for estimating Young's moduli of mortar specimens.

Precisely estimating material parameters for cement-based materials is crucial for assessing the structural integrity of buildings. Both destructive (e.g., compression test) and non-destructive methods (e.g., ultrasound, computed tomography) are used to estimate Young's modulus. Since ultrasound estimates the dynamic Young's modulus, a formula is required to adapt it to the static modulus. For this formulas from the literature are compared. The investigated specimens are cylindrical mortar specimens with four different sand-to-cement mass fractions of 20%, 35%, 50%, and 65%. The ultrasound signals are analyzed in two distinct ways: manual onset picking and full-waveform inversion. Full-waveform inversion involves comparing the measured signal with a simulated one and iteratively adjusting the ultrasound velocities in a numerical model until the measured signal closely matches the simulated one. Using computed tomography measurements, Young's moduli are semi-analytically determined based on sand distribution in cement images. The reconstructed volume is segmented into sand, cement, and pores. Young's moduli, as determined by compression tests, were better represented by full-waveform inversions (best RMSE = 0.34 GPa) than by manual onset picking (best RMSE = 0.87 GPa). Moreover, material parameters from full-waveform inversion showed less deviation than those manually picked. The maximal standard deviation of a Young's modulus determined with FWI was 0.36, while that determined with manual picking was 1.11. Young's moduli from computed tomography scans match those from compression tests the closest, with an RMSE of 0.13 GPa.

Numerical evaluation of internal femur osteosynthesis based on a biomechanical model of the loading in the proximal equine hindlimb.

Femoral fractures are often considered lethal for adult horses because femur osteosynthesis is still a surgical challenge. For equine femur osteosynthesis, primary stability is essential, but the detailed physiological forces occurring in the hindlimb are largely unknown. The objective of this study was to create a numerical testing environment to evaluate equine femur osteosynthesis based on physiological conditions. The study was designed as a finite element analysis (FEA) of the femur using a musculoskeletal model of the loading situation in stance. Relevant forces were determined in the musculoskeletal model via optimization. The treatment of four different fracture types with an intramedullary nail was investigated in FEA with loading conditions derived from the model. The analyzed diaphyseal fracture types were a transverse (TR) fracture, two oblique fractures in different orientations (OB-ML: medial-lateral and OB-AP: anterior-posterior) and a "gap" fracture (GAP) without contact between the fragments. For the native femur, the most relevant areas of increased stress were located distally to the femoral head and proximally to the caudal side of the condyles. For all fracture types, the highest stresses in the implant material were present in the fracture-adjacent screws. Maximum compressive (-348 MPa) and tensile stress (197 MPa) were found for the GAP fracture, but material strength was not exceeded. The mathematical model was able to predict a load distribution in the femur of the standing horse and was used to assess the performance of internal fixation devices via FEA. The analyzed intramedullary nail and screws showed sufficient stability for all fracture types.

Frozen, Cold, or Cool? Chemical Assessment of the Effectiveness of Storage Conditions for Celluloid 3D Objects.

Preserving celluloid artifacts is challenging for museums, as this plastic is highly prone to degradation. Frozen, cold, and cool storage solutions are typically recommended for inhibiting the chemical degradation of celluloid. However, they are rarely implemented for three-dimensional celluloid (3D-CN) objects because low temperatures might cause irreversible effects (e.g., microcracking). This work presents the effects of four different storage temperatures (+23 °C, +13 °C, +9 °C, -15 °C) on the preservation of artificially aged 3D-CN mock-ups, aiming at understanding their effectiveness by measuring molecular weight distribution, camphor, and nitrogen contents after storage. Gel permeation chromatography (GPC) results showed that the least loss of camphor content and fewer polymer chain scissions happened at -15 °C, hinting that this temperature was the best for preservation. However, the heterogeneous nature of celluloid alteration, i.e., the development of degradation gradients in thicker 3D-CN objects (>0.5 mm), made it necessary to apply a novel sampling technique, which selectively considers several depths for analyses from the surface to the core (depth profiling). This depth profiling made monitoring the degradation evolution dependent on the storage conditions in the thicker mock-ups possible. This approach was also used for the first time to quantify the polymer chain scission, camphor loss, and denitration of historical artifacts, indicating a dramatic difference in the degradation stage between surface and core. The effectiveness of frozen storage on the chemical stability of 3D-CN after seven months could support museums to consider reducing the storage temperatures to preserve precious artifacts.

Mock-Ups in Plastic Conservation Research: Processing and Aging of 3D Celluloid Specimens Simulating Historical Objects.

The preparation of mock-ups in heritage science studies represents a valid alternative for investigation purposes, avoiding extensive sampling of cultural heritage objects. This work presents for the first time the successful preparation of three dimensional (3D) mock-ups made of celluloid, considering a combination of historical industrial production strategies and small-scale lab facilities. Prefabricated transparent celluloid sheets were acquired and then shaped through compression molding for creating mock-ups with 3D geometries. These reflected common and representative shapes encountered in the collection of the Deutsches Museum. Visual inspection of the mock-ups allowed determining the best compression molding conditions. Attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) confirmed the absence of molecular heterogeneity due to the processing method. Artificial aging of the mock-ups was conducted to reach degradation states comparable with naturally aged objects. ATR-FTIR investigation offered first insights into the induced artificial degradation. Ion chromatography (IC) and gel permeation chromatography (GPC) analyses allowed to assess the extent of the artificial aging of the celluloid mock-ups and confirmed the occurrence of loss of camphor, denitration, and main chain polymer scission, the latter being the predominant decay path. The comparison with historical objects highlighted that the mock-ups are representative of moderately aged artifacts. As such, this study paves the way for implementing moderately aged celluloid 3D mock-ups in heritage science research, enabling in-depth testing for the scope of conservation.

The restoration and erection of the world's first elevated obelisk.

Obelisks presented an important element in the architecture of ancient Egypt. This research is concerned with the re-erection of an obelisk that belongs to the famous Pharoah Ramses II. It was found broken and was transported to the Grand Egyptian Museum for restoration and display. An observation of Ramses II Cartouche at the bottom side of the obelisk base inspired the authorities to provide an innovative architectural design to display the obelisk elevated. The supporting structure was designed to allow the visitors to walk underneath the obelisk and observe Ramses II's signature. The idea of elevating the obelisk presented several challenges including evaluating the obelisk's current condition, restoration and fixation methodology, structural stability, and uncertainties of material characteristics, amongst others. To control the obelisk deformations under lateral loading, state-of-the-art base isolators were introduced. For the task to be achieved, a multidisciplinary team including historians, conservators, archaeologists, architects, and engineers with different specialties was appointed. The team performed the task successfully and currently, the obelisk stands at the entrance piazza of the Grand Egyptian Museum representing the world's first elevated obelisk.

Broadband Air-Coupled Ultrasound Emitter and Receiver Enable Simultaneous Measurement of Thickness and Speed of Sound in Solids.

Air-coupled ultrasound sensors have advantages over contact ultrasound sensors when a sample should not become contaminated or influenced by the couplant or the measurement has to be a fast and automated inline process. Thereby, air-coupled transducers must emit high-energy pulses due to the low air-to-solid power transmission ratios (10-3 to 10-8). Currently used resonant transducers trade bandwidth-a prerequisite for material parameter analysis-against pulse energy. Here we show that a combination of a non-resonant ultrasound emitter and a non-resonant detector enables the generation and detection of pulses that are both high in amplitude (130 dB) and bandwidth (2 µs pulse width). We further show an initial application: the detection of reflections inside of a carbon fiber reinforced plastic plate with thicknesses between 1.7 mm and 10 mm. As the sensors work contact-free, the time of flight and the period of the in-plate reflections are independent parameters. Hence, a variation of ultrasound velocity is distinguishable from a variation of plate thickness and both properties are determined simultaneously. The sensor combination is likely to find numerous industrial applications necessitating high automation capacity and opens possibilities for air-coupled, single-side ultrasonic inspection.

Evaluation of the Behavior of Carbon Short Fiber Reinforced Concrete (CSFRC) Based on a Multi-Sensory Experimental Investigation and a Numerical Multiscale Approach.

Carbon fiber reinforcement used in concrete has become a remarkable alternative to steel fibers. Admixing short fibers to fresh concrete and processing the material with a 3D printer leads to an orientation of fibers and a material with high uniaxial strength properties, which offers an economic use of fibers. To investigate its mechanical behavior, the material is subjected to flexural and tensional tests, combining several measuring techniques. Numerical analysis complements this research. Computed tomography is used with several post-processing algorithms for separating matrix and fibers. This helps to validate fiber alignment and serves as input data for numerical analysis with representative volume elements concatenating real fiber position and orientation with the three-dimensional stress tensor. Flexural and uniaxial tensional tests are performed combining multiple measuring techniques. Next to conventional displacement and strain measuring methods, sound emission analysis, in terms of quantitative event analysis and amplitude appraisal, and also high-resolution digital image correlation accompany the tests. Due to the electrical conductibility of carbon fibers, the material's resistivity could be measured during testing. All sensors detect the material's degradation behavior comparably, showing a strain-hardening effect, which results from multiple, yet locally restricted and distributed, microcracks arising in combination with plastic deformation.

Improving mandibular reconstruction by using topology optimization, patient specific design and additive manufacturing?-A biomechanical comparison against miniplates on human specimen.

In this study, topology optimized, patient specific osteosynthesis plates (TOPOS-implants) are evaluated for the mandibular reconstruction using fibula segments. These shape optimized implants are compared to a standard treatment with miniplates (thickness: 1.0 mm, titanium grade 4) in biomechanical testing using human cadaveric specimen. Mandible and fibula of 21 body donors were used. Geometrical models were created based on automated segmentation of CT-scans of all specimens. All reconstructions, including cutting guides for osteotomy as well as TOPOS-implants, were planned using a custom-made software tool. The TOPOS-implants were produced by electron beam melting (thickness: 1.0 mm, titanium grade 5). The fibula-reconstructed mandibles were tested in static and dynamic testing in a multi-axial test system, which can adapt to the donor anatomy and apply side-specific loads. Static testing was used to confirm mechanical similarity between the reconstruction groups. Force-controlled dynamic testing was performed with a sinusoidal loading between 60 and 240 N (reconstructed side: 30% reduction to consider resected muscles) at 5 Hz for up to 5 · 105 cycles. There was a significant difference between the groups for dynamic testing: All TOPOS-implants stayed intact during all cycles, while miniplate failure occurred after 26.4% of the planned loading (1.32 · 105 ± 1.46 · 105 cycles). Bone fracture occurred in both groups (miniplates: n = 3, TOPOS-implants: n = 2). A correlation between bone failure and cortical bone thickness in mandible angle as well as the number of bicortical screws used was demonstrated. For both groups no screw failure was detected. In conclusion, the topology optimized, patient specific implants showed superior fatigue properties compared to miniplates in mandibular reconstruction. Additionally, the patient specific shape comes with intrinsic guiding properties to support the reconstruction process during surgery. This demonstrates that the combination of additive manufacturing and topology optimization can be beneficial for future maxillofacial surgery.

Thickness measurement via local ultrasonic resonance spectroscopy.

Local ultrasonic resonance spectroscopy (LURS) is a new approach to material inspection, where the specimen is locally excited by a short mechanical impulse while its local mechanical response is recorded at a position nearby. The local material and geometrical properties can be extracted from the frequency spectrum of the response and visualized by performing a scan over the inspected area. In our experiment, the plate thickness and the reliefs of both plate surfaces (plate curvature) were obtained from thickness resonance and time of arrival analysis without physical contact to the specimen. Ultrasound was generated on the specimen surface by a laser pulse. Local mechanical response of a carbon fiber-reinforced polymer plate with a thickness ranging from 0.6 mm to 4.3 mm was recorded with a broadband optical microphone in through-transmission setup. The precision of this arrangement greatly exceeded the precision of conventional methods limited by the ultrasound wavelength. For thicknesses in the range around 1 mm, standard deviations of up to several µm were achieved. An influence of the through-plate ultrasound velocity on the measured relief of the plate surface nearest to the optical microphone was eliminated by a joint evaluation of thickness resonance and time of arrival. Furthermore, we demonstrated that internal delaminations have an influence on the spectrum of the local mechanical response and can therefore be detected by LURS.

The Influence of Different Auditory Stimuli on Attentiveness and Responsiveness in Road Traffic in Simulated Traffic Situations.

The use of portable media has become an integral part of our increasingly mobile society. The use of digital audio books is also growing steadily in Germany. The connection between the psychological effect of music of different volumes and rhythms and the change in reaction in road traffic with a corresponding increase in risk behavior, especially when driving, has already been proven in previous studies. Only a few studies are available on the effects of listening to radio plays on reaction behavior and concentration in road traffic as well as on risk behavior among pedestrians and cyclists. In the present study, we have investigated the influences of pop music and a radio play on reaction behavior and thus driving ability during the execution of a traffic psychological test series from the "Wiener Test System". The central topic deals with the performance of the test subjects in the individual tests. Conclusions are drawn on the reaction behavior and concentration during participation in road traffic and thus the risk of distraction and possible increased risk of accidents. Studies on the influence of auditory stimuli and their effects on concentration and reaction during participation in traffic are of great interest from the point of view of traffic psychology and occupational medicine, since a reduction in the risk of accidents can increase general traffic safety and lead to a decrease in sick leave and therefore fewer absences from work.

Full biomechanical mapping of the ovine knee joint to determine creep-recovery, stiffness and thickness variation.

BACKGROUND: Clinical cartilage repair strategies can be tested using the sheep model as suggest by the European Medicines Agency. To characterize variation within the joint a full biomechanical mapping is necessary. The aim of this study is to establish a loading model, to map regional differences within the knee and determine reference areas for area specific replacement techniques. METHODS: A porous indenter was selected to evaluate 22 defined test locations (femoral condyles, tibia plateau, patella, femoral groove) on ovine knees (n = 7). A high-dynamic force-controlled micro creep and creep-recovery indentation test system applied five loading (0.11 MPa) and unloading (5.6 kPa) cycles for 60 s each and recorded creep-recovery. Needle indentation was used to measure cartilage thickness and calculate total strain. FINDINGS: Steady state behaviour was observed from the third cycle and further evaluated. Little variation of stiffness in N/mm was found within the patella (4.3SD0.5) and femoral groove (8.1SD0.7) compared to larger variations in the femur (7.9SD2.0) and tibia (7.5SD3.2). Creep indentation showed values of 14.5%(SD2.7%) for the patella and 17.4%(SD3%) for the femoral grove opposed to 13.4%(SD4.3%) for the femoral condyles and 21.8%(SD6.6%) for the tibia plateau. Similar trends were observed analysing creep-recovery. Values were normalized to cartilage thickness which ranged between 0.36 mm and 1.14 mm. INTERPRETATION: Our setup allows a reliable evaluation of zonal differences. Homogenous biomechanical behaviour is found within the patella and femoral groove whereas significant biomechanical variation within the femoral condyles and tibia plateau indicates the need for site-specific cartilage repair products.

Concrete wave dispersion interpretation through Mindlin's strain gradient elastic theory.

Classical elastic wave features like pulse velocity and attenuation have been used for decades for concrete condition characterization. Relatively recently the effect of frequency has been studied showing no doubt over the dispersive behavior of the material. Despite the experimental evidence, there is no unified theory to model the material and explain this phase velocity change at frequencies below 200 kHz. Herein, the Mindlin's strain gradient elastic theory including the additional micro-stiffness and micro-inertia parameters is considered as an alternative of multiple scattering theory. Experimental results are produced from material with dictated microstructure using a specific diameter of glass beads in cement paste. Results show that Mindlin's theory provides conclusions on the microstructure of the material and is suitable for describing the observed dispersion in different length scales (from millimeters in the case of mortar to several centimeters in the case of concrete).

Novel silk protein barrier membranes for guided bone regeneration.

This study assesses the biocompatibility of novel silk protein membranes with and without modification, and evaluates their effect on facilitating bone formation and defect repair in guided bone regeneration. Two calvarian bone defects 12 mm in diameter were created in each of a total of 38 rabbits. Four different types of membranes, (silk-, hydroxyapatite-modified silk-, ß-TCP-modified silk- and commonly clinically used collagen-membranes) were implanted to cover one of the two defects in each animal. Histologic analysis did not show any adverse tissue reactions in any of the defect sites indicating good biocompatibility of all silk protein membranes. Histomorphometric and histologic evaluation revealed that collagen and ß-TCP modified silk membranes supported bone formation (collagen: bone area fraction p = 0.025; significant; ß-TCP modified silk membranes bone area fraction: p = 0.24, not significant), guided bone regeneration and defect bridging. The bone, which had formed in defects covered by ß-TCP modified silk membranes, displayed a more advanced stage of bone tissue maturation with restoration of the original calvarial bone microarchitecture when compared to the bone which had formed in defects, for which any of the other test membranes were used. Micro-CT analysis did not reveal any differences in the amount of bone formation between defects with and without membranes. In contrast to the collagen membranes, ß-TCP modified silk membranes were visible in all cases and may therefore be advantageous for further supporting bone formation beyond 10 weeks and preventing soft tissue ingrowth from the periphery. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2603-2611, 2017.

Hydrophobic Properties of Biofilm-Enriched Hybrid Mortar.

A mortar hybrid material is presented in which biomineralization processes are stimulated by adding a biological component, i.e., bacterial biofilm, to standard mortar. A material is obtained that exhibits increased roughness on the microscale and the nanoscale. Accordingly, the hybrid mortar not only resists wetting but also suppresses the uptake of water by capillary forces.

Time reverse modeling of acoustic emissions in a reinforced concrete beam.

The time reverse modeling (TRM) is applied for signal-based acoustic emission (AE) analysis of reinforced concrete (RC) specimens. TRM uses signals obtained from physical experiments as input. The signals are re-emitted numerically into a structure in a time-reversed manner, where the wavefronts interfere and appear as dominant concentrations of energy at the origin of the AE. The experimental and numerical results presented for selected AE signals confirm that TRM is capable of localizing AE activity in RC caused by concrete cracking. The accuracy of the TRM results is corroborated by three-dimensional crack distributions obtained from X-ray computed tomography images.

Two-State Intramolecular Charge Transfer (ICT) with 3,5-Dimethyl-4-(dimethylamino)benzonitrile (MMD) and Its Meta-Isomer mMMD. Ground State Amino Twist Not Essential for ICT.

From X-ray structure analysis, amino twist angles of 90.0° for 2,4-dimethyl-3-(dimethylamino)benzonitrile (mMMD), 82.7° for 4-(di-tert-butylamino)benzonitrile (DTABN), and 88.7° for 6-cyanobenzoquinuclidine (CBQ) are determined, all considerably larger than the 57.4° of 3,5-dimethyl-4-(dimethylamino)benzonitrile (MMD). This large twist leads to lengthening of the amino-phenyl bond, 143.5 pm (mMMD), 144.1 pm (DTABN), 144.6 pm (CBQ), and 141.4 pm (MMD), as compared with 136.5 pm for the planar 4-(dimethylamino)benzonitrile (DMABN). As a consequence, the electronic coupling between the amino and phenyl subgroups in mMMD, DTABN, CBQ, and MMD is much weaker than in DMABN, as seen from the strongly reduced molar absorption coefficients. The fluorescence spectrum of MMD in n-hexane at 25 °C consists of two emissions, from a locally excited (LE) and an intramolecular charge transfer (ICT) state, with a fluorescence quantum yield ratio Φ'(ICT)/Φ(LE) of 12.8. In MeCN, a single ICT emission is found. With mMMD in n-hexane, in contrast, only LE fluorescence is observed, whereas the spectrum in MeCN originates from the ICT state. These differences are also seen from the half-widths of the overall fluorescence bands, which in n-hexane are larger for MMD than for mMMD, decreasing with solvent polarity for MMD and increasing for mMMD, reflecting the disappearance of LE and the onset of ICT in the overall spectra, respectively. From solvatochromic measurements the dipole moments µe(ICT) of MMD (16 D) and mMMD (15 D) are obtained. Femtosecond excited state absorption (ESA) spectra at 22 °C, together with the dual (LE + ICT) fluorescence, reveal that MMD in n-hexane undergoes a reversible LE ⇄ ICT reaction, with LE as the precursor, with a forward rate constant ka = 5.6 × 10(12) s(-1) and a back-reaction kd ∼ 0.05 × 10(12) s(-1). With MMD in the strongly polar solvent MeCN, ICT is faster: ka = 10 × 10(12) s(-1). In the case of mMMD in n-hexane, the ESA spectra show that ICT does not take place, contrary to MeCN, in which ka = 2.5 × 10(12) s(-1). The ICT reactions with MMD and mMMD are much faster than that of the parent compound DMABN in MeCN, with ka = 0.24 × 10(12) s(-1). Because of the very short ICT reaction times of 180 fs (MMD, n-hexane), 100 fs (MMD, MeCN), and 400 fs (mMMD, MeCN), it is clear that the picosecond fluorescence decays of these systems appear to be single exponential, due to the insufficient time resolution of 3 ps. It is concluded that the faster LE → ICT reaction of MMD as compared with DMABN (ka = 0.24 × 10(12) s(-1) in MeCN) is caused by a smaller energy gap ΔE(S1,S2) between the lowest singlet excited states and not by the large amino twist angle. Similarly, the larger ΔE(S1,S2) of mMMD as compared with MMD is held responsible for its smaller ICT efficiency (no reaction in n-hexane).

MEMS Microphone Array Sensor for Air-Coupled Impact-Echo.

Impact-Echo (IE) is a nondestructive testing technique for plate like concrete structures. We propose a new sensor concept for air-coupled IE measurements. By using an array of MEMS (micro-electro-mechanical system) microphones, instead of a single receiver, several operational advantages compared to conventional sensing strategies in IE are achieved. The MEMS microphone array sensor is cost effective, less sensitive to undesired effects like acoustic noise and has an optimized sensitivity for signals that need to be extracted for IE data interpretation. The proposed sensing strategy is justified with findings from numerical simulations, showing that the IE resonance in plate like structures causes coherent surface displacements on the specimen under test in an area around the impact location. Therefore, by placing several MEMS microphones on a sensor array board, the IE resonance is easier to be identified in the recorded spectra than with single point microphones or contact type transducers. A comparative measurement between the array sensor, a conventional accelerometer and a measurement microphone clearly shows the suitability of MEMS type microphones and the advantages of using these microphones in an array arrangement for IE. The MEMS microphone array will make air-coupled IE measurements faster and more reliable.

Bionic approach for the prevention of exit-site infections of percutaneous devices.

Exit-site infections remain one of the main complications for percutaneous devices, such as catheters for peritoneal dialysis or drivelines for ventricular assist devices. Many efforts have been made to create a biological seal, yet without long-term success. This study investigates a new kind of percutaneous device which is coated with an extricable polymeric membrane. The bionic approach applies the naturally outwards directed growth of skin structures to technology: by pulling the protective membrane it slowly grows out of the body and a developing sulcus is exposed to dry air and an infection is avoided. In a feasibility study this kind of device was shown to reduce the rate of infection. To further investigate these devices, they were implanted in the skin of goats and observed for a period of more than 500 days. The membranes were pulled with a force of up to 2 N and the resulting movement was recorded. When being pulled, the membranes moved 0.4-0.9 mm per week, showing that the application of a continuously acting, defined force on the protective membrane causes the desired slow movement.

(2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-Mono(di,tri)fluoromethylcyclopropyl]alanines and their incorporation into hormaomycin analogues.

Efficient and scalable syntheses of enantiomerically pure (2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-mono(di,tri)fluoromethylcyclopropyl]alanines 9a-c, as well as allo-D-threonine (4) and (2S,3R)-ß-methylphenylalanine (3), using the Belokon' approach with (S)- and (R)-2-[(N-benzylprolyl)amino]benzophenone [(S)- and (R)-10] as reusable chiral auxiliaries have been developed. Three new fluoromethyl analogues of the naturally occurring octadepsipeptide hormaomycin (1) with (fluoromethylcyclopropyl)alanine moieties have been synthesized and subjected to preliminary tests of their antibiotic activity.